The presentation highlights how recent investigations have shown extensive reprogramming of almost every component of the epigenetic machinery in cancer leading to the emergence of the promising field of epigenetic therapy.
This document discusses epigenetics and cancer epigenetics. It defines epigenetics as heritable changes in gene expression that do not involve changes to DNA sequence. There are two forms of information in cells - genetic information encoded in the DNA sequence, and epigenetic information involving modifications like DNA methylation and histone acetylation. These epigenetic changes can contribute to oncogenesis along with genetic variations. The document discusses mechanisms of epigenetic changes like DNA methylation and histone acetylation/deacetylation and how they regulate gene expression. It provides examples of epigenetic changes in tumors and diseases and potential epigenetic therapies using demethylating and HDAC inhibitor drugs.
1. Cancer epigenetics involves heritable changes in gene expression that are not due to changes in DNA sequence. Histone modifications and chromatin remodeling complexes play important roles in cancer development by regulating gene expression and transcription.
2. Many genes that encode histone modifying enzymes are mutated in cancer. Mutations in DNA methyltransferases, histone methyltransferases, and histone demethylases commonly occur in cancers.
3. Targeting epigenetic enzymes and pathways, such as with DNA methyltransferase or histone deacetylase inhibitors, shows promise as cancer therapies. Combination epigenetic and conventional chemotherapy may help reduce drug resistance.
The epigenetic regulation of DNA-templated processes has been intensely studied over the last 15
years. DNA methylation, histone modification, nucleosome remodeling, and RNA-mediated targeting regulate many biological processes that are fundamental to the genesis of cancer. Here, we
present the basic principles behind these epigenetic pathways and highlight the evidence suggesting that their misregulation can culminate in cancer. This information, along with the promising clinical and preclinical results seen with epigenetic drugs against chromatin regulators, signifies that it
is time to embrace the central role of epigenetics in cancer.
The document discusses epigenetics and the epigenome. It describes the key components of the epigenetic code, including DNA methylation and various histone modifications. It explains how these modifications can regulate gene expression and affect processes like transcription, development, and disease states like cancer. The document also outlines several methods for studying the epigenome, such as bisulfite sequencing and chromatin immunoprecipitation assays. Finally, it discusses potential therapeutic approaches that target the epigenome, including drugs that inhibit DNA methyltransferases and histone deacetylases.
Efficacy of epigenetic therapy as cancer treatmentjanelle_leggere
This document discusses epigenetic therapies for cancer treatment. It introduces DNA methylation and histone modifications as two main types of epigenetic modifications. It then reviews four FDA-approved epigenetic drugs - azacytidine, decitabine, vorinostat, and romidepsin - and their efficacy in treating various cancers like myelodysplastic syndromes and cutaneous T-cell lymphoma. The document finds that combination epigenetic therapies may have synergistic effects in solid tumors and help reduce side effects. Overall, the future of epigenetic cancer treatment likely involves effective combination approaches and more targeted epigenetic inhibitors.
This document provides information about epigenetics. It discusses:
1. What epigenetics is and some key epigenetic modifications like DNA methylation and histone modifications.
2. Examples of epigenetically regulated phenomena like cellular differentiation, X-chromosome inactivation, and imprinting.
3. The role of epigenetics in cancer, development, and how the environment can influence epigenetic changes. Diet, smoking, socioeconomic status, and toxins are discussed as environmental factors that can cause epigenetic modifications.
Pharmacogenomics uses a patient's genetic profile to select optimal drug therapies and dosages. Gene polymorphisms like substitutions, deletions and insertions can affect drug efficacy and toxicity. Biomarkers can help predict cancer prognosis and treatment response. For example, EGFR mutations predict response to EGFR inhibitors in NSCLC, while BRAF mutations indicate response to BRAF inhibitors in melanoma. Resistance often develops from additional mutations that prevent drug binding. Combination therapies can overcome resistance by targeting alternate pathways.
This document discusses epigenetics and cancer epigenetics. It defines epigenetics as heritable changes in gene expression that do not involve changes to DNA sequence. There are two forms of information in cells - genetic information encoded in the DNA sequence, and epigenetic information involving modifications like DNA methylation and histone acetylation. These epigenetic changes can contribute to oncogenesis along with genetic variations. The document discusses mechanisms of epigenetic changes like DNA methylation and histone acetylation/deacetylation and how they regulate gene expression. It provides examples of epigenetic changes in tumors and diseases and potential epigenetic therapies using demethylating and HDAC inhibitor drugs.
1. Cancer epigenetics involves heritable changes in gene expression that are not due to changes in DNA sequence. Histone modifications and chromatin remodeling complexes play important roles in cancer development by regulating gene expression and transcription.
2. Many genes that encode histone modifying enzymes are mutated in cancer. Mutations in DNA methyltransferases, histone methyltransferases, and histone demethylases commonly occur in cancers.
3. Targeting epigenetic enzymes and pathways, such as with DNA methyltransferase or histone deacetylase inhibitors, shows promise as cancer therapies. Combination epigenetic and conventional chemotherapy may help reduce drug resistance.
The epigenetic regulation of DNA-templated processes has been intensely studied over the last 15
years. DNA methylation, histone modification, nucleosome remodeling, and RNA-mediated targeting regulate many biological processes that are fundamental to the genesis of cancer. Here, we
present the basic principles behind these epigenetic pathways and highlight the evidence suggesting that their misregulation can culminate in cancer. This information, along with the promising clinical and preclinical results seen with epigenetic drugs against chromatin regulators, signifies that it
is time to embrace the central role of epigenetics in cancer.
The document discusses epigenetics and the epigenome. It describes the key components of the epigenetic code, including DNA methylation and various histone modifications. It explains how these modifications can regulate gene expression and affect processes like transcription, development, and disease states like cancer. The document also outlines several methods for studying the epigenome, such as bisulfite sequencing and chromatin immunoprecipitation assays. Finally, it discusses potential therapeutic approaches that target the epigenome, including drugs that inhibit DNA methyltransferases and histone deacetylases.
Efficacy of epigenetic therapy as cancer treatmentjanelle_leggere
This document discusses epigenetic therapies for cancer treatment. It introduces DNA methylation and histone modifications as two main types of epigenetic modifications. It then reviews four FDA-approved epigenetic drugs - azacytidine, decitabine, vorinostat, and romidepsin - and their efficacy in treating various cancers like myelodysplastic syndromes and cutaneous T-cell lymphoma. The document finds that combination epigenetic therapies may have synergistic effects in solid tumors and help reduce side effects. Overall, the future of epigenetic cancer treatment likely involves effective combination approaches and more targeted epigenetic inhibitors.
This document provides information about epigenetics. It discusses:
1. What epigenetics is and some key epigenetic modifications like DNA methylation and histone modifications.
2. Examples of epigenetically regulated phenomena like cellular differentiation, X-chromosome inactivation, and imprinting.
3. The role of epigenetics in cancer, development, and how the environment can influence epigenetic changes. Diet, smoking, socioeconomic status, and toxins are discussed as environmental factors that can cause epigenetic modifications.
Pharmacogenomics uses a patient's genetic profile to select optimal drug therapies and dosages. Gene polymorphisms like substitutions, deletions and insertions can affect drug efficacy and toxicity. Biomarkers can help predict cancer prognosis and treatment response. For example, EGFR mutations predict response to EGFR inhibitors in NSCLC, while BRAF mutations indicate response to BRAF inhibitors in melanoma. Resistance often develops from additional mutations that prevent drug binding. Combination therapies can overcome resistance by targeting alternate pathways.
The tumour microenvironment consists of cells, molecules and blood vessels that surround and support tumour cells. It includes cancer-associated fibroblasts, myeloid suppressor cells, tumour infiltrating lymphocytes, and the extracellular matrix. Hypoxic conditions in the tumour microenvironment activate HIF signalling pathways and cause changes that promote cancer progression in both tumour and stromal cells. Immune cells in the microenvironment like regulatory T cells and myeloid suppressor cells suppress antitumour immune responses and help tumours escape immune surveillance. Targeting the microenvironment may be a promising approach for future cancer immunotherapies.
This document provides an overview of the molecular foundations of cancer. It discusses how cancer arises from genetic and epigenetic aberrations that accumulate in cells and lead to altered gene expression and the acquisition of hallmark capabilities that allow tumors to form and progress. Key points covered include the types of genomic changes like mutations and chromosome defects that occur; the roles of oncogenes and tumor suppressor genes; how cancer risk can be inherited; and the uses of genomics in cancer diagnosis and targeted treatment.
The document discusses epigenetics and chromatin structure. It defines epigenetics as heritable changes in gene expression that do not involve changes to the underlying DNA sequence. This includes histone modifications and DNA methylation. It describes chromatin as being made up of nucleosomes, which consist of DNA wrapped around histone octamers. The structure of chromatin affects gene expression, with euchromatin typically being gene-rich and actively transcribed, while heterochromatin is gene-poor and transcriptionally silent. Histone modifications like acetylation and methylation also influence gene expression. DNA methylation typically silences genes and occurs most frequently at CpG islands. These epigenetic changes play important roles in development and diseases like
Genomic instability plays an important role in cancer development by accelerating the accumulation of genetic changes in cancer cells. Several mechanisms can cause genomic instability, including defects in DNA repair pathways like base excision repair, mismatch repair, and double-strand break repair. Loss of function in DNA repair genes like MLH1 and MSH2 can lead to hypermutation and microsatellite instability in colorectal cancer. Other causes include problems with DNA replication, chromosome segregation, and telomere dysfunction. Genetic disorders involving genomic instability include ataxia-telangiectasia, neurofibromatosis type 1, Bloom syndrome, and ring chromosomes.
CAR-T cells are T cells that are genetically engineered to express chimeric antigen receptors (CARs) that target specific antigens on tumor cells. The first CAR-T cell therapy, Kymriah, was approved in 2017 for treating B-cell acute lymphoblastic leukemia. It showed high rates of complete remission. While effective, CAR-T cells can cause cytokine release syndrome and neurotoxicity as side effects. Ongoing research aims to expand CAR-T cell use in solid tumors and improve their safety profile.
The document discusses the hallmarks of cancer as proposed by Hanahan and Weinberg. It identifies the eight hallmarks as sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, activating invasion and metastasis, deregulating cellular energetics, and avoiding immune destruction. It also discusses two enabling characteristics - genome instability and mutation, and tumor-promoting inflammation. Finally, it summarizes how several of these hallmarks, including sustaining proliferative signaling, activating invasion and metastasis, resisting cell death, and genome instability and mutation have been identified in breast cancer and contribute to its heterogeneity and treatment resistance.
Metastatic cascade and Epithelial Mesenchymal TransitionShruti Dogra
This document provides an overview of cancer metastasis and the epithelial-mesenchymal transition (EMT) process. It discusses the metastatic cascade, which involves tumor cell invasion, intravasation into blood vessels, transport through circulation, extravasation and homing to distant sites, and formation of secondary tumors. EMT is described as a key step in metastasis that allows epithelial cells to detach from primary tumors and migrate. The molecular and cellular changes involved in EMT include loss of epithelial markers like E-cadherin and gain of mesenchymal markers. Transcription factors such as Snail, Slug, Twist, and ZEB play important roles in inducing EMT. Understanding metastasis and EMT can help develop strategies to prevent cancer spread
Genomic instability refers to changes in chromosome structure and number that can lead to cancer. It is caused by failures in DNA replication, damage sensing and repair, and cell cycle checkpoints. There are several types of genetic instability, including chromosomal instability (CIN), microsatellite instability (MIN), and DNA replication errors. CIN results in chromosome gains and losses, while MIN causes repetitive DNA expansions and contractions. Genomic instability can arise from defects in DNA damage response genes like p53 and ATM, problems with DNA replication, fragile sites in the genome, and DNA secondary structures. While genetic instability promotes evolution, it also contributes to pathological conditions like cancer by enabling the accumulation of mutations needed for malignant transformation.
This document provides an overview of principles of cancer immunotherapy. It discusses anti-cancer immunity mechanisms like antigen presentation and T cell activation. It also examines how cancers can evade the immune system through strategies like low MHC expression and immunosuppressive factors. The document then reviews clinical applications of immunotherapy including cytokines, monoclonal antibodies, adoptive cell transfer, vaccines, and checkpoint inhibitors. Combination therapies are showing promise for enhancing anti-tumor responses.
ONCOGENE AND PROTOONCOGENE
P53 GENE AND ITS APPLICATION IN CANCER ETIOLOGY
TUMOUR SUPPRESSOR GENE AND BCA AND BAC GENE AND ITS APPLICATION ON THE APOPTOSIS AND DEATH RECEPTORS
Comparative genomic hybridization is a molecular cytogenetic method for analysing copy number variations (CNVs) relative to ploidy level in the DNA of a test sample compared to a reference sample, without the need for culturing cells
This presentation on Epigenetics is most advanced and evidence based one. Its Very helpful for Genetics students and research fellows, Reproductive Medicine specialist, Reproductive Biologist, Infertility practitioners
Epithelial and mesenchymal transition in invasion and metastasisAshwini Gowda
This document discusses neoplasia and the process of metastasis. It defines neoplasia as new, uncontrolled growth and describes the hallmarks of cancer cells, including autonomous growth, loss of differentiation, invasion and metastasis. It explains the multi-step process of metastasis, beginning with local invasion of tumor cells into surrounding tissue facilitated by degradation of the extracellular matrix and migration of cells. The document then discusses the vascular dissemination of tumor cells and colonization at distant sites, outlining several theories for how metastatic potential arises in tumors. Key genes and pathways involved in epithelial-mesenchymal transition and the generation of cancer stem cells are also reviewed.
Cancer is caused by mutations in genes that regulate cell growth and proliferation. These mutations can activate proto-oncogenes into oncogenes or inactivate tumor suppressor genes. Oncogenes promote cell growth while tumor suppressor genes normally inhibit cell proliferation. Common mechanisms of proto-oncogene activation include chromosomal translocations, gene amplifications, and point mutations. Disruptions to cell cycle checkpoints, apoptosis, telomere maintenance and DNA repair pathways can also contribute to cancer development by allowing abnormal cell growth and survival.
This document discusses epigenetics and its role in human disease. It begins with an introduction to epigenetics, explaining that epigenetic processes can alter gene expression without changing DNA sequence. It then discusses some key epigenetic mechanisms like DNA methylation and histone modifications. It provides examples of how epigenetic changes are implicated in several diseases, such as neurological disorders, autoimmune diseases, diabetes, and cancer. The document concludes by noting that epigenetic therapies are being explored for diseases like cancer, and that combining epigenetic drugs with immunotherapy shows promise in treating various cancer types.
Immunotherapy utilizes the body's immune system to fight cancer by improving its ability to detect and kill cancer cells. Chimeric antigen receptors (CARs) are engineered receptors that are used to graft the specificity of a monoclonal antibody onto a T cell. CARs are under investigation as a cancer therapy using adoptive cell transfer. To produce CAR T cells, T cells are engineered using a virus-based gene delivery system containing packaging elements and a vector to transfer genetic material that encodes the CAR receptor structure. CAR T cell therapy shows promise but also risks toxicity that requires careful management. Ongoing research focuses on improving CAR specificity and controlling their activity in the body.
chimeric antigen receptor, its structure and role in killing tumor cells,mechanism of antitumor killing, car's in clinic,evolution of cars and new chimeric antigen models
DNA methylation involves the addition of methyl groups to cytosine bases in DNA. It is an epigenetic process that plays an important role in normal development and diseases like cancer. Cytosine methylation occurs most widely and involves the addition of a methyl group to the C-5 position of cytosine. Methylation can repress gene expression by interfering with transcriptional protein binding or recruiting chromatin remodeling proteins. In cancer, aberrant methylation can lead to silencing of tumor suppressor genes or activation of oncogenes. Genomic imprinting involves differential gene expression based on parental origin through epigenetic mechanisms like methylation. Around 1% of genes show imprinting including IGF2 and H19. Imprinting errors
The Wnt cascade has emerged as a critical regulator of stem cells. In many tissues, activation of Wnt signaling has also been found to be associated with cancer. Understanding the regulation by Wnt signaling may serve as a paradigm for understanding the dual nature of self-renewal signals.
Paleoecology of Bivalves from Lower Miocene of Kutch, IndiaShibajyoti Das
This document summarizes a study on the paleoecology of bivalves from the Lower Miocene of Kutch, India. The study aimed to characterize the bivalve taxonomy, diversity, and morphology over time and evaluate the possible effects of climatic change. Bivalve shells were collected from two formations - the older Khari Nadi formation and younger Chhasra formation. Results showed higher taxonomic diversity, γ diversity, and larger average body sizes in the older formation. Isotopic analysis also indicated warmer temperatures in the younger formation. This supports the hypothesis that increased temperature leads to increased diversity but decreased body size, demonstrating the impact of climatic change on bivalve paleoecology.
The tumour microenvironment consists of cells, molecules and blood vessels that surround and support tumour cells. It includes cancer-associated fibroblasts, myeloid suppressor cells, tumour infiltrating lymphocytes, and the extracellular matrix. Hypoxic conditions in the tumour microenvironment activate HIF signalling pathways and cause changes that promote cancer progression in both tumour and stromal cells. Immune cells in the microenvironment like regulatory T cells and myeloid suppressor cells suppress antitumour immune responses and help tumours escape immune surveillance. Targeting the microenvironment may be a promising approach for future cancer immunotherapies.
This document provides an overview of the molecular foundations of cancer. It discusses how cancer arises from genetic and epigenetic aberrations that accumulate in cells and lead to altered gene expression and the acquisition of hallmark capabilities that allow tumors to form and progress. Key points covered include the types of genomic changes like mutations and chromosome defects that occur; the roles of oncogenes and tumor suppressor genes; how cancer risk can be inherited; and the uses of genomics in cancer diagnosis and targeted treatment.
The document discusses epigenetics and chromatin structure. It defines epigenetics as heritable changes in gene expression that do not involve changes to the underlying DNA sequence. This includes histone modifications and DNA methylation. It describes chromatin as being made up of nucleosomes, which consist of DNA wrapped around histone octamers. The structure of chromatin affects gene expression, with euchromatin typically being gene-rich and actively transcribed, while heterochromatin is gene-poor and transcriptionally silent. Histone modifications like acetylation and methylation also influence gene expression. DNA methylation typically silences genes and occurs most frequently at CpG islands. These epigenetic changes play important roles in development and diseases like
Genomic instability plays an important role in cancer development by accelerating the accumulation of genetic changes in cancer cells. Several mechanisms can cause genomic instability, including defects in DNA repair pathways like base excision repair, mismatch repair, and double-strand break repair. Loss of function in DNA repair genes like MLH1 and MSH2 can lead to hypermutation and microsatellite instability in colorectal cancer. Other causes include problems with DNA replication, chromosome segregation, and telomere dysfunction. Genetic disorders involving genomic instability include ataxia-telangiectasia, neurofibromatosis type 1, Bloom syndrome, and ring chromosomes.
CAR-T cells are T cells that are genetically engineered to express chimeric antigen receptors (CARs) that target specific antigens on tumor cells. The first CAR-T cell therapy, Kymriah, was approved in 2017 for treating B-cell acute lymphoblastic leukemia. It showed high rates of complete remission. While effective, CAR-T cells can cause cytokine release syndrome and neurotoxicity as side effects. Ongoing research aims to expand CAR-T cell use in solid tumors and improve their safety profile.
The document discusses the hallmarks of cancer as proposed by Hanahan and Weinberg. It identifies the eight hallmarks as sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, activating invasion and metastasis, deregulating cellular energetics, and avoiding immune destruction. It also discusses two enabling characteristics - genome instability and mutation, and tumor-promoting inflammation. Finally, it summarizes how several of these hallmarks, including sustaining proliferative signaling, activating invasion and metastasis, resisting cell death, and genome instability and mutation have been identified in breast cancer and contribute to its heterogeneity and treatment resistance.
Metastatic cascade and Epithelial Mesenchymal TransitionShruti Dogra
This document provides an overview of cancer metastasis and the epithelial-mesenchymal transition (EMT) process. It discusses the metastatic cascade, which involves tumor cell invasion, intravasation into blood vessels, transport through circulation, extravasation and homing to distant sites, and formation of secondary tumors. EMT is described as a key step in metastasis that allows epithelial cells to detach from primary tumors and migrate. The molecular and cellular changes involved in EMT include loss of epithelial markers like E-cadherin and gain of mesenchymal markers. Transcription factors such as Snail, Slug, Twist, and ZEB play important roles in inducing EMT. Understanding metastasis and EMT can help develop strategies to prevent cancer spread
Genomic instability refers to changes in chromosome structure and number that can lead to cancer. It is caused by failures in DNA replication, damage sensing and repair, and cell cycle checkpoints. There are several types of genetic instability, including chromosomal instability (CIN), microsatellite instability (MIN), and DNA replication errors. CIN results in chromosome gains and losses, while MIN causes repetitive DNA expansions and contractions. Genomic instability can arise from defects in DNA damage response genes like p53 and ATM, problems with DNA replication, fragile sites in the genome, and DNA secondary structures. While genetic instability promotes evolution, it also contributes to pathological conditions like cancer by enabling the accumulation of mutations needed for malignant transformation.
This document provides an overview of principles of cancer immunotherapy. It discusses anti-cancer immunity mechanisms like antigen presentation and T cell activation. It also examines how cancers can evade the immune system through strategies like low MHC expression and immunosuppressive factors. The document then reviews clinical applications of immunotherapy including cytokines, monoclonal antibodies, adoptive cell transfer, vaccines, and checkpoint inhibitors. Combination therapies are showing promise for enhancing anti-tumor responses.
ONCOGENE AND PROTOONCOGENE
P53 GENE AND ITS APPLICATION IN CANCER ETIOLOGY
TUMOUR SUPPRESSOR GENE AND BCA AND BAC GENE AND ITS APPLICATION ON THE APOPTOSIS AND DEATH RECEPTORS
Comparative genomic hybridization is a molecular cytogenetic method for analysing copy number variations (CNVs) relative to ploidy level in the DNA of a test sample compared to a reference sample, without the need for culturing cells
This presentation on Epigenetics is most advanced and evidence based one. Its Very helpful for Genetics students and research fellows, Reproductive Medicine specialist, Reproductive Biologist, Infertility practitioners
Epithelial and mesenchymal transition in invasion and metastasisAshwini Gowda
This document discusses neoplasia and the process of metastasis. It defines neoplasia as new, uncontrolled growth and describes the hallmarks of cancer cells, including autonomous growth, loss of differentiation, invasion and metastasis. It explains the multi-step process of metastasis, beginning with local invasion of tumor cells into surrounding tissue facilitated by degradation of the extracellular matrix and migration of cells. The document then discusses the vascular dissemination of tumor cells and colonization at distant sites, outlining several theories for how metastatic potential arises in tumors. Key genes and pathways involved in epithelial-mesenchymal transition and the generation of cancer stem cells are also reviewed.
Cancer is caused by mutations in genes that regulate cell growth and proliferation. These mutations can activate proto-oncogenes into oncogenes or inactivate tumor suppressor genes. Oncogenes promote cell growth while tumor suppressor genes normally inhibit cell proliferation. Common mechanisms of proto-oncogene activation include chromosomal translocations, gene amplifications, and point mutations. Disruptions to cell cycle checkpoints, apoptosis, telomere maintenance and DNA repair pathways can also contribute to cancer development by allowing abnormal cell growth and survival.
This document discusses epigenetics and its role in human disease. It begins with an introduction to epigenetics, explaining that epigenetic processes can alter gene expression without changing DNA sequence. It then discusses some key epigenetic mechanisms like DNA methylation and histone modifications. It provides examples of how epigenetic changes are implicated in several diseases, such as neurological disorders, autoimmune diseases, diabetes, and cancer. The document concludes by noting that epigenetic therapies are being explored for diseases like cancer, and that combining epigenetic drugs with immunotherapy shows promise in treating various cancer types.
Immunotherapy utilizes the body's immune system to fight cancer by improving its ability to detect and kill cancer cells. Chimeric antigen receptors (CARs) are engineered receptors that are used to graft the specificity of a monoclonal antibody onto a T cell. CARs are under investigation as a cancer therapy using adoptive cell transfer. To produce CAR T cells, T cells are engineered using a virus-based gene delivery system containing packaging elements and a vector to transfer genetic material that encodes the CAR receptor structure. CAR T cell therapy shows promise but also risks toxicity that requires careful management. Ongoing research focuses on improving CAR specificity and controlling their activity in the body.
chimeric antigen receptor, its structure and role in killing tumor cells,mechanism of antitumor killing, car's in clinic,evolution of cars and new chimeric antigen models
DNA methylation involves the addition of methyl groups to cytosine bases in DNA. It is an epigenetic process that plays an important role in normal development and diseases like cancer. Cytosine methylation occurs most widely and involves the addition of a methyl group to the C-5 position of cytosine. Methylation can repress gene expression by interfering with transcriptional protein binding or recruiting chromatin remodeling proteins. In cancer, aberrant methylation can lead to silencing of tumor suppressor genes or activation of oncogenes. Genomic imprinting involves differential gene expression based on parental origin through epigenetic mechanisms like methylation. Around 1% of genes show imprinting including IGF2 and H19. Imprinting errors
The Wnt cascade has emerged as a critical regulator of stem cells. In many tissues, activation of Wnt signaling has also been found to be associated with cancer. Understanding the regulation by Wnt signaling may serve as a paradigm for understanding the dual nature of self-renewal signals.
Paleoecology of Bivalves from Lower Miocene of Kutch, IndiaShibajyoti Das
This document summarizes a study on the paleoecology of bivalves from the Lower Miocene of Kutch, India. The study aimed to characterize the bivalve taxonomy, diversity, and morphology over time and evaluate the possible effects of climatic change. Bivalve shells were collected from two formations - the older Khari Nadi formation and younger Chhasra formation. Results showed higher taxonomic diversity, γ diversity, and larger average body sizes in the older formation. Isotopic analysis also indicated warmer temperatures in the younger formation. This supports the hypothesis that increased temperature leads to increased diversity but decreased body size, demonstrating the impact of climatic change on bivalve paleoecology.
An artificial cardiac pacemaker is an implantable medical device that generates electrical impulses to stimulate the heart and regulate its rhythm. The first pacemaker was implanted in 1958 and since then pacemaker technology has advanced significantly. Modern pacemakers are smaller, more durable, and can synchronize with the heart's natural rhythm. A pacemaker consists of a pulse generator and battery housed in a casing connected to pacing leads that are placed into the heart chambers. Pacemakers treat abnormal heart rhythms by sensing the heart's activity and delivering electrical pulses when needed to maintain a regular rhythm.
Coulter counter is a commercially available device for determining the size distribution of electrically nonconducting particles suspended in a conducting medium.
How to Make Awesome SlideShares: Tips & TricksSlideShare
Turbocharge your online presence with SlideShare. We provide the best tips and tricks for succeeding on SlideShare. Get ideas for what to upload, tips for designing your deck and more.
SlideShare is a global platform for sharing presentations, infographics, videos and documents. It has over 18 million pieces of professional content uploaded by experts like Eric Schmidt and Guy Kawasaki. The document provides tips for setting up an account on SlideShare, uploading content, optimizing it for searchability, and sharing it on social media to build an audience and reputation as a subject matter expert.
DNA methylation is a biological process where methyl groups are added to DNA, changing gene expression without altering the DNA sequence. It is essential for normal development in mammals and is associated with processes like genomic imprinting, carcinogenesis, and aging. DNA methyltransferases are enzymes that catalyze the addition of methyl groups to DNA from S-adenosylmethionine. DNA methylation plays important roles in gene silencing, X-chromosome inactivation, and suppressing viral genomes and repetitive elements incorporated into the host genome. Aberrant DNA methylation is also involved in cancer by transcriptionally silencing tumor suppressor genes.
DNA methylation is a biological process where methyl groups are added to DNA, changing gene expression without altering the DNA sequence. It is essential for normal development in mammals and is associated with processes like genomic imprinting and carcinogenesis. DNA methyltransferases are enzymes that catalyze the addition of methyl groups to DNA from S-adenosyl methionine. DNA methylation plays important roles in gene silencing, X-chromosome inactivation, and suppressing viral genomes and repetitive elements incorporated into the host genome. Abnormal DNA methylation is also associated with cancer by transcriptionally silencing tumor suppressor genes.
DNA methylation is an epigenetic mechanism that involves the addition of a methyl group to cytosine residues in DNA. It is catalyzed by DNA methyltransferase enzymes and plays a key role in gene expression and cellular differentiation. Aberrant DNA methylation, including both hypermethylation and hypomethylation, has been associated with cancer development by disrupting gene expression. Detection of DNA methylation patterns can provide insights into cancer biology and may have applications as a diagnostic tool.
This document summarizes recent developments in small molecule epigenetic drugs. It discusses four DNA methyltransferase (DNMT) inhibitors approved by the FDA, including Vidaza and Decitabine. It also discusses two histone deacetylase (HDAC) inhibitors approved, Vorinostat and Romidepsin. Other epigenetic targets discussed include Sirtuins, histone methyltransferases, and protein arginine methyltransferases. The document reviews the development stages of small molecules related to epigenetics and their role in disease development and progression. It provides examples of epigenetic targets disrupted in cancer and structures of common HDAC and other epigenetic inhibitors. In conclusion, it states that HDAC inhibitors
Epigenetic Changes in Hepatocellular Carcinoma (HCC) .dr_ekbalabohashem
The presentation illustrates the role of epigenetic mechanisms in HCC development .De in therapy scription of the role of DNA methylation ,histone modifications,and miRNA in etiopathogenesis of the disease is provided,together with the possible use in therapy .
DNA methylation, an epigenetic mechanism, plays a major role in gene expression and silencing. Changes in DNA methylation patterns, including global hypomethylation and hypermethylation of tumor suppressor genes, are consistently observed in cancer cells and contribute to tumor formation. Both hypomethylation of oncogenes and hypermethylation of tumor suppressor genes can provide a selective growth advantage for cancer cells.
This document discusses DNA methylation and its role in cancer development. It begins by defining epigenetics and describing the three main stages of epigenetic regulation: nucleosome positioning, histone modification, and DNA methylation. It then focuses on DNA methylation, the enzymes involved like DNMTs and TETs, and the processes of methylation and demethylation. Numerous studies have found that cancer cells exhibit disruptions to DNA methylation patterns, including hypomethylation of repetitive DNA and hypermethylation of CpG islands in gene promoters. These changes are associated with genomic instability, aberrant gene transcription, and silencing of tumor suppressor genes, which can promote cancer progression. Understanding DNA methylation alterations
DNA methylation is an epigenetic mechanism where a methyl group is added to DNA nucleotides, most commonly to the 5-carbon position of cytosine. This methylation can alter gene expression and affect cellular processes. DNA methyltransferases (DNMTs) establish and maintain DNA methylation patterns, while Ten-Eleven Translocation (TET) enzymes can remove methyl groups through a process called active DNA demethylation. Abnormal DNA methylation is associated with diseases like cancer, where tumor suppressor genes are often silenced by hypermethylation while genomes are globally hypomethylated.
This presentation discusses DNA methylation, an epigenetic mechanism where methyl groups are added to DNA. It describes how DNA methyltransferases (DNMTs) catalyze the transfer of methyl groups from S-adenosyl methionine to cytosine bases in DNA. DNMT1 maintains methylation patterns during DNA replication, while DNMT3a and DNMT3b establish new patterns during development. DNA methylation plays roles in gene silencing, genomic imprinting, and suppression of transposable elements. Abnormal methylation is associated with cancer, where global hypomethylation and gene-specific hypermethylation can contribute to oncogenesis. Sodium bisulfite conversion is commonly used to detect DNA methylation
Epigenetic silencing of MGMT (O6-methylguanine DNA methyltransferase) gene in...arman170701
O6–methylgunine-DNA methyltransferace (MGMT) is a DNA binding protein that is involved in repairing mutations.
MGMT gene - a tumor suppressor gene that codes MGMT (O6-methylguanine DNA methyltransferase) protein.
The MGMT protein removes mutagenic methyl groups from guanines through the methyltransferase activity.
Anindya seminar 1 growth factors and cell cycle signalling in pathogenesis of...Kazi Manir
The document discusses several key concepts regarding the molecular basis of cancer including:
1. Cancer is caused by mutations in proto-oncogenes, tumor suppressor genes, DNA repair genes, and apoptotic genes.
2. Self-sufficiency in growth signals is achieved through mutations in proto-oncogenes encoding growth factors, growth factor receptors, signal transducing proteins, and cell cycle regulators.
3. Examples of targeted cancer therapies include monoclonal antibodies, tyrosine kinase inhibitors, hormones, and hormonal agents.
Reduced representation bisulfite sequencing identified differential hypermethylation of the c-MER proto-oncogene (MERTK) in approximately 25% of colon cancer cell lines and tumors. Rapid amplification of cDNA ends showed predominantly 5' truncated MERTK mRNA transcripts in methylated colon cancer cell lines. The document aims to determine the mechanism by which hypermethylation alters MERTK expression and transcript structure. The authors hypothesize that methylation causes alternative splicing producing a constitutively active truncated tyrosine kinase. They plan to clone truncated cDNA fragments into cell lines to assess effects on MERTK activation, cell growth, and subcellular localization.
Epigenetics definition, history of epigenetics, molecular basis of epigenetics, epigenetic modification, tools to study epigenetics, disease linked with epigenetics, DNA methylation demethylation and enzymes regulating DNA methylation
Canine oncoprotein targets for Melanoma, Breast Cancer, OsteosarcomaSnehal Salunkhe
We can acquire the basic knowledge about canine oncoprotein targets specifically for Melanoma, Osteosarcoma and Breast cancer. I haven't mentioned all the proteins and their targets involved, but just a general overview of these targets with the drugs involved in their treatment/clinical trials.
Epigenetics involves heritable changes in gene expression that do not involve changes to DNA sequence. The main epigenetic mechanisms are chromatin remodeling, DNA methylation, and histone modification. Environmental factors like smoking, diet, and toxins can influence the epigenome. Errors in epigenetic programming have been linked to diseases. The epigenome responds dynamically to the environment and directs gene expression patterns during development and differentiation.
This document discusses anticancer drugs, also known as chemotherapy drugs. It describes the main classes of anticancer drugs, including alkylating agents, antimetabolites, cytotoxic antibiotics, hormones, and enzymes. Alkylating agents work by alkylating DNA and inhibiting its replication. Common alkylating agents include cyclophosphamide and cisplatin. Antimetabolites are structurally similar to essential metabolites and interfere with DNA synthesis, examples include methotrexate and fluorouracil. Cytotoxic antibiotics like doxorubicin act directly on DNA. The document also covers the mechanisms of action, clinical uses, and side effects of several important chemotherapy drugs.
The DNA damage response (DDR) is a multifaceted system of genes that are responsible for detecting and reacting to various forms of DNA damage. This intricate network encompasses specific mechanisms that facilitate DNA repair, regulate the cell cycle, respond to replication stress, and induce apoptosis.
Impairments in the DDR can lead to genomic instability in cells, which can contribute to the initiation and progression of cancer by promoting the accumulation of mutations. However, these defects also create exploitable vulnerabilities that are relatively specific to cancer cells, and can be targeted for clinical benefit through the use of DDR inhibitors.
This document discusses epigenetic modifications of proteins. It begins by defining epigenetics and describing how epigenetic modifications can alter gene expression without changing DNA sequences. It then focuses on histone modifications like acetylation, methylation, ubiquitination, and phosphorylation. The document also examines epigenetic modifications of specific proteins - Sox2, CCAAT/enhancer binding protein a (C/EBPa), and caveolae associated proteins. It provides details on studies that analyzed the methylation of promoters for these genes in cancer cell lines and patient samples.
This document discusses regulation of deoxynucleotide metabolism in cancer and its therapeutic implications. It describes how imbalanced levels of deoxynucleotide triphosphates (dNTPs) can lead to genomic instability and increased cancer risk. Several key points are made: 1) Enzymes like ribonucleotide reductase and SAMHD1 regulate dNTP levels and maintain genomic stability. 2) Mutations or dysregulation of these enzymes can cause elevated dNTP pools and increased mutagenesis, facilitating cancer development. 3) Many cancer therapies target dNTP synthesis pathways to inhibit tumor growth. 4) SAMHD1 specifically acts as a tumor suppressor by maintaining low dNTP levels
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2. Epigenetics
Heritable changes in a cellular phenotype that were independent of alterations in the DNA sequence.
•Every nucleated cell in our body contains
about 2 m of DNA, which is packaged and
regulated in a nucleus that is no more than 10
µm wide.
•The repetitive fundamental unit of chromatin
is the nucleosome :a histone octamer,
consisting of a tetramer of histones H3 and H4
wedged between dimers of histones H2A/H2B,
around which approximately 150 base pairs of
DNA are wrapped.
•Perhaps the most influential elements that
coordinate both the local and global chromatin
architecture are the covalent modifications of
DNA and histones.
•The term epigenetics is traditionally used to
describe heritable traits that were not
attributable to sequence-specific changes in
DNA.
•It is now clear that chromatin (epigenetic)
modifications play an instructive role in
regulating all DNA-templated processes,
including transcription, repair, and replication
3. Epigenetics
Heritable changes in a cellular phenotype that were independent of alterations in the DNA sequence.
•Every nucleated cell in our body contains
about 2 m of DNA, which is packaged and
regulated in a nucleus that is no more than 10
µm wide.
•The repetitive fundamental unit of chromatin
is the nucleosome :a histone octamer,
consisting of a tetramer of histones H3 and H4
wedged between dimers of histones H2A/H2B,
around which approximately 150 base pairs of
DNA are wrapped.
•Perhaps the most influential elements that
coordinate both the local and global chromatin
architecture are the covalent modifications of
DNA and histones.
•The term epigenetics is traditionally used to
describe heritable traits that were not
attributable to sequence-specific changes in
DNA.
•It is now clear that chromatin (epigenetic)
modifications play an instructive role in
regulating all DNA-templated processes,
including transcription, repair, and replication.
NA
4. Epigenetic Pathways Connected to Cancer:
DNA Methylation
•The methylation of the 5-carbon on cytosine residues (5mC) in CpG dinucleotides was the first
described covalent modification of DNA and is perhaps the most extensively characterized
modification of chromatin.
•DNA methylation is primarily noted within centromeres, telomeres, inactive X-chromosomes,
and repeat sequences.
•Although global hypomethylation is commonly observed in malignant cells, the methylation
changes that occur within CpG islands, which are present in 70% of all mammalian promoters.
•5%–10% of normally unmethylated CpG promoter islands become abnormally methylated in
various cancer genomes.
•CpG hyper methylation of promoters not only affects the expression of protein coding genes
but also the expression of various noncoding RNAs- role in malignancy.
5. Epigenetic Pathways Connected to Cancer:
DNA Methylation
•DNA methyltransferases (DNMTs) in higher eukaryotes
•DNMT1 is a maintenance methyltransferase that
recognizes hemimethylated DNA generated during DNA
replication and then methylates newly synthesized CpG
dinucleotides
•Conversely, DNMT3a and DNMT3b, although also
capable of methylating hemimethylated DNA, function
primarily as de novo methyltransferases to establish
DNA methylation during embryogenesis
•DNA methylation provides a platform for several
methyl-binding proteins like MBD1, MBD2, MBD3, and
MeCP2
•Recent sequencing of cancer genomes has identified
recurrent mutations in DNMT3A in up to 25% of
patients with acute myeloid leukemia (AML).
•These mutations are invariably heterozygous and are
predicted to disrupt the catalytic activity of the enzyme.
Moreover, their presence appears to impact prognosis
The5-carbonof cytosinenucleotidesare methylated(5mC)by a
familyof DNMTs.One of these,DNMT3A, ismutatedinAML,
myeloproliferativediseases(MPD),andmyelodysplasticsyndromes
(MDS).
6. Epigenetic Pathways Connected to Cancer:
DNA Methylation
The5-carbonof cytosinenucleotidesare methylated(5mC)by a
familyof DNMTs.One of these,DNMT3A, ismutatedinAML,
myeloproliferativediseases(MPD),andmyelodysplasticsyndromes
(MDS).
Therapy:
•Hypomethylating agents – has gained FDA approval for
routine clinical use.
•Azacitidine and decitabine have shown mixed results
in various solid malignancies, they have found a
therapeutic niche in the myelo-dysplastic syndromes
(MDS).
•Azacitidine reactivates the expression of certain
aberrantly silenced genes in cancer cells, but a gene-
specific signature that can guide the use of this drug in
MDS and other cancers has remained elusive.
•A part of the mechanism of action of DNMTi may relate
to the fact that these drugs produce a cell-intrinsic
stimulation of the immune system by reactivating
endogenous retroviral elements.
•These highlight an emerging theme in epigenetic cancer
therapies: functional interaction with host immunity.
7. Epigenetic Pathways Connected to Cancer:
DNA Hydroxy-Methylation and Its Oxidation Derivatives
•High-resolution genome-wide mapping of this modification in pluripotent and
differentiated cells has also confirmed the dynamic nature of DNA methylation.
•The ten-eleven translocation (TET 1–3) family of proteins are the mammalian DNA
hydroxylases responsible for catalytically converting 5mC to 5hmC. Iterative
oxidation of 5hmC by the TET family results in further oxidation derivatives, including
5-formylcytosine (5fC) and 5-carboxylcytosine (5caC).
•They are likely to be an essential intermediate in the process of both active and
passive DNA demethylation and they preclude or enhance the binding of several MBD
proteins.
•Genome-wide mapping of 5hmC has identified a distinctive distribution of this
modification at both active, repressed and bivalent genes including its presence
within gene bodies, promoters and enhancer elements.
•All these are consistent with the notion that 5hmC is likely to have a role in both
transcriptional activation and silencing.
8. Epigenetic Pathways Connected to Cancer:
DNA Hydroxy-Methylation and Its Oxidation Derivatives
TheTET family of DNA hydroxylasesmetabolizes5mCinto severaloxidative
intermediates,including5-hydroxymethylcytosine(5hmC), 5-formylcytosine
(5fC),and 5-carboxylcytosine(5caC).Theseintermediatesare likelyinvolved
in the processof activeDNA demethylation.Twoof the threeTET family
membersare mutatedin cancers,includingAML, MPD, MDS, andCMML.
Therapy:
•Loss-of-function mutations of TET-2 results in
decreased 5hmC levels and a reciprocal increase in
5mC levels within the malignant cells .
•Several reports emerged describing recurrent
mutations in TET2 in numerous hematological
malignancies.
•TET2- deficient mice develop a chronic
myelomonocytic leukemia (CMML) phenotype, which
is in keeping with the high prevalence of TET2
mutations.
•TET2 mutations appear to confer a poor prognosis.
9. These tables provide somatic cancer-associated mutations identified in
histone acetyltransferases and proteins that contain bromodomains
(readers). Several histone acetyltransferases possess chromatin-reader
motifs and, thus, mutations in the proteins may alter both their catalytic
activities as well as the ability of these proteins to scaffold multiprotein
complexes to chromatin.
Epigenetic Pathways Connected to Cancer:
Histone Acetylation
•Neutralizes lysine’s positive charge and may
consequently weaken the electrostatic interaction
between histones and negatively charged DNA; often
associated with a ‘‘open’’ chromatin conformation.
•There are two major classes of KATs: type-B-
predominantly cytoplasmic and modify free histones,
and type-A primarily nuclear and can be classified
into the GNAT, MYST, and CBP/p300 families.
•.There are numerous examples of recurrent
chromosomal translocations (e.g., MLL-CBP and
MOZ-TIF2) or coding mutations (e.g., p300/CBP)
involving various KATs and BETs in a broad range of
solid and hematological malignancies.
• Several nonhistone proteins, including many
important oncogenes and tumor suppressors such as
MYC, p53, and PTEN, are also dynamically acetylated.
•Derivatives of the naturally occurring KATi, such as
curcumin, anacardic acid, and garcinol, as well as
the synthesis of novel chemical probes, suggests
therapeutic targeting of KATs with some specificity in
the near future.
•
10. Interestingly,sequencingof cancer genomesto datehasnotidentifiedany
recurrentsomaticmutationsin HDACs.
Epigenetic Pathways Connected to Cancer:
Histone Deacetylation
•HDACs are enzymes that reverse lysine
acetylation and restore the positive charge on the side
chain.
• In the context of malignancy, chimeric fusion
proteins that are seen in leukemia, such as PML-RARa,
PLZF-RARa, and AML1- ETO, have been shown to
recruit HDACs to mediate aberrant gene silencing,
which contributes to leukemogenesis.
•HDACs can also interact with nonchimeric oncogenes
such as BCL6, whose repressive activity is controlled
by dynamic acetylation.
•Based on impressive preclinical and clinical data, two
pan-HDACi, Vorinostat and Romidepsin, has been
granted FDA approval for clinical use in patients with
cutaneous T-cell lymphoma.
11. Epigenetic Pathways Connected to Cancer:
Histone Methylation
•The enzymatic protagonists for lysine methylation
contain a conserved SET domain, which possesses
methyltransferase activity.
•NGS of various cancer genomes has demonstrated
recurrent translocations and/or coding mutations in a
large number of KMT, including MMSET, EZH2, and
MLL family members .
•EZH2 is the catalytic component of the PRC2 complex,
which is primarily responsible for the methylation of
H3K27. EZH2 has both oncogenic and tumor
suppressor ability. However, the precise mechanisms
by which gain and loss of EZH2 activity culminate in
cancers are an area of active investigation.
H3K4, H3K36, and H3K79 methylation are often associated with active genes in euchromatin, whereas
others H3K9, H3K27, and H4K20 are associated with heterochromatic regions of the genome. Different
methylation states on the same residue can also localize differently. For instance, H3K4me2/3 usually spans the
transcriptional startsite (TSS) of active genes, whereas H3K4me1 is a modification associated with active
enhancers.
12. •LSD1 (KDM1A), belongs to the first class of
demethylases that can function as a transcriptional
repressor by demethylating H3K4me1/2 as part of
the corepressor for RE1-silencing transcription factor
(Co-REST) complex.
•The second and more expansive class of enzymes is
broadly referred to as the Jumonji demethylases and
they have a conserved JmjC domain, which functions via
an oxidative mechanism and radical attack (involving
Fe(II) and α-ketoglutarate).
•Recurrent coding mutations have been noted in
KDM5A (JARID1A), KDM5C (JARID1C), and KDM6A
(UTX). Mutations in UTX, in particular, are prevalent in a
large number of solid and hematological cancers.
•Small-molecule inhibitors of the two families of
histone demethylases are at various stages of
development.
Epigenetic Pathways Connected to Cancer:
Histone Demethylation
13. •Histone-methylation readers are broadly classified into the following families: Chromodomain
(CHD ATPases, HP1, PC)
Tudor (some histone demethylases)
PHD (many chromatin regulators BPTF, ING2)
MBT (in some polycomb proteins)
WD-40 (WDR5)
•All three isoforms of the chromodomain protein HP1 have altered expression in numerous
cancers.
•Leukemia, induced by the fusion of NUP98 with the PHD finger, can be abrogated by mutations
that negate the ability of the PHD finger to bind H3K4me3.
•Small molecules that disrupt this important protein-protein interaction may be effective
anticancer agents.
Epigenetic Pathways Connected to Cancer:
Histone Methylation Readers
14. Epigenetic Pathways Connected to Cancer:
Histone Phosphorylation
•The phosphorylation of serine/threonine/tyrosine residues has been documented on
all core and most variant histones. Phosphorylation alters the charge of the protein,
affecting its ionic properties and influencing the overall structure and function of
the local chromatin environment.
•The specific histone phosphorylation sites on core histones can be divided into two
broad categories: (1) those involved in transcription regulation, and (2) those
involved in chromatin condensation. Notably, several of these histone modifications,
such as H3S10, are associated with both categories.
15. •Within the nucleus, JAK2, a non-receptor tyrosine kinase, specifically phosphorylates
H3Y41, disrupts the binding of the chromatin repressor HP1a, and activates the expression
of hematopoietic oncogenes such as Lmo2.
•Several of thesmall-molecule inhibitors against kinases (e.g., JAK2 and Aurora
inhibitors) are clinically used as anticancer therapies, result in a global reduction in the
histone modifications laid down by these enzymes. These agents can therefore be
considered as potential epigenetic therapies.
Epigenetic Pathways Connected to Cancer:
Histone Phosphorylation
BRCA1,whichcontainsaBRCTdomain,is
theonlypotentialphosphochromatinreaderrecurrentlymutatedin
breast,ovarianandprostatecancer.
16. Epigenetic Pathways Connected to Cancer:
Chromatin Remodelers
These complexes are evolutionarily conserved, use
ATP to evict, modify and exchange histones. All this
is done on the basis of chromatin reader motifs
which confer regional and contextual specificity.
Depending on their biochemical activity can be
classified as:
•Switching Defective/ Sucrose Non fermenting
family (SWI/SNF)
•Imitation SWI family (ISWI)
•Nucleosome remodeling and Deacetylation
(NuRD)/ Chromodomain binding DNA Helicase
family (CHD)
• Inositol requiring 80 family (INO80)
•Several members from the various chromatin-
remodeling families, such as SNF5, BRG1, and
MTA1, were known to be mutated in malignancies,
suggesting that they may be bone fide tumor
suppressors .
SWI/SNF is a multisubunit complex that binds chromatin and disrupts histone-
DNA contacts. The SWI/SNF complex alters nucleosome positioning and
structure by sliding and evicting nucleosomes to make the DNA more
accessible to transcription factors and other chromatin regulators. Recurrent
mutations in several members of the SWI/SNF complex have been identified in
a number of cancers.
17. Epigenetic Pathways Connected to Cancer:
Mutations in Histone Genes
The wild-type histone H3 recruits Polycomb repressive complex 2 (PRC2) and stimulates methyltransferase
activity of its catalytic subunit EZH2, which trimethylates histone H3 at lysine 27 (H3K27me3). The
replication-independent histone variant H3.3 mutant that contains the K27M substitution was recently
identified in many diffuse intrinsic pontine gliomas and supratentorial glioblastomas. This mutation leads to
dominant inhibition of EZH2 in both cis and trans and to concomitant global loss of H3K27me3. These data
provide the first direct evidence that mutations in histone variants themselves contribute to human disease.
18. Epigenetic Pathways Connected to Cancer:
Non-coding RNAs
•Small ncRNAs include small nucleolar RNAs (snoRNAs), PIWIinteracting RNAs
(piRNAs), small interfering RNAs (siRNAs), and microRNAs (miRNAs) are involved
in transcriptional and posttranscriptional gene silencing through specific base
pairing with their targets.
•On the other hand, lncRNAs appear to have a critical function at chromatin, where
they may act as molecular chaperones or scaffolds for various chromatin regulators.
One of the best-studied lncRNAs that emerges from
the mammalian HOXC cluster but invariably acts in
trans is HOTAIR. HOTAIR provides a molecular
scaffold for the targeting and coordinated action of
both the PRC2 complex and the LSD1-containing
CoREST/REST complex. HOTAIR is aberrantly
overexpressed in advanced breast and colorectal
cancer, and manipulation of HOTAIR levels within
malignant cells can functionally alter the invasive
potential of these cancers by changing PRC2
occupancy.
19. Cancer Mutations in “Dark Matter” Affect Chromatin
Regulation
•The mutation rate of the non-coding regulatory genome, or so-called “dark matter,” is nearly
double that of coding regions. Such mutations occur in multiple gene promoters and enhancer
elements and are found in a range of cancers.
•A pioneering example was the discovery of mutations within the promoter region of TERT,
the gene that encodes the catalytic subunit of telomerase, in more than 70% of melanomas.
Interestingly, the TERT promoter mutations appear to increase the expression of TERT by creating
a de novo binding motif for the ETS family of transcription factors.
•“Superenhancers” have been defined as regulatory DNA elements with a high density of binding
of transcriptional co-activators and other components of the transcription machinery. It appears
that malignant superenhancers, with their increased concentration of transcription co-activators,
provide a unique sensitivity to epigenetic therapies. Oncogenic superenhancers have been
described in T-ALL (T cell acute lymphoblastic leukemia), where somatic mutations create new
binding sites for the transcription factor MYB at a superenhancer upstream of the TAL1 oncogene.
20. Cancer Metabolism and Its Effects on the Epigenome
•In addition to mutations in IDH, other critical enzymes involved in the tricarboxylic acid
(TCA) cycle, including succinate dehydrogenase and fumarate hydratase, have also been
observed in cancer. Mutations in all these TCA cycle enzymes appear to induce a CpG island
hypermethylation phenotype (CIMP) in tumor DNA.
•This rapidly expanding area of investigation is likely to reveal new insights into the
mechanisms of epigenetic dysregulation in cancer and also provide new therapeutic avenues.
Several human cancers, particularly gliomas and AML, harbor mutations in isocitrate dehydrogenase (IDH1
and IDH2); these mutations confer neomorphic activity to the mutant enzyme. In contrast to wild-type IDH,
which converts isocitrate to aketoglutarate (aKG), IDH mutants preferentially metabolize aKG to the D-
enantiomer of 2-hydroxyglutarate (2HG). Elevated 2HG levels appear central to the pathogenesis of IDH
mutant malignancies, as 2-HG is a competitive inhibitor of the Fe(II)-dependent and 2-oxoglutarate (2OG)
dependent dioxygenases like TET (ten-eleven translocation) family of proteins involved in DNA demethylation
and the JumonjiC domain family of histone demethylases.
21. •Epigenetic heterogeneity is far more dynamic than genetic heterogeneity, and it is likely that
transcriptional plasticity driven by epigenetic regulators responding to environmental and
therapeutic pressures underpins the failure of many cancer drugs to induce durable disease
remission in patients. However, combination therapies are now used to achieve higher
efficacy.
•As normal and malignant epigenetic regulation iscell context–specific, empirical
combinations of therapies that substantially alter the epigenome may potentially be
detrimental. For example, monotherapy with a DNMTi extends the survival of many patients
with myelo-dysplastic syndromes (MDS), and HDAC inhibitors in isolation have also shown
some benefit in MDS. However, in contrast to the predicted synergy, several studies have
now demonstrated that the empirical combination of these agents results in no discernible
synergy and in fact may result in functional antagonism; several patients have had a poorer
outcome with combination therapy than those treated with a DNMTi alone.
•These findings highlight the need to thoroughly explore the molecular rationale for
combination epigenetic therapies and experimentally demonstrate the synergistic effects of
the combination therapy in appropriate preclinical models and primary human cancer cells.
•Combination of BETi and DOT1Li and a strategy of combining IDH inhibitors with BCL2
inhibitors have begun to emerge and set the stage for future combination therapies.
Combination Therapy
22. Developing New Epigenetic Therapies
•At present, however, there is no clear strategy to establish what these therapeutic targets should be. Much of
epigenetic drug discovery is being driven by what is possible from a medicinal chemistry viewpoint rather than
what is needed.
•First, it is important to recognize that many epigenetic proteins function in the context of multiprotein
member complexes, and a single epigenetic protein may have an essential scaffold/targeting/catalytic role in
several diverse complexes. Therefore, genetic ablation of a single member may disrupt the entire complex and
the “real” druggable target may not be the one identified in the screen.
•Furthermore, epigenetic proteins often contain several functional protein domains (reader/writer/eraser).
This is important because each of these domains may have a distinct role in epigenetic regulation. Therefore,
identifying the precise domain responsible for the phenotype of interest is critical to rational drug design.
23. Developing New Epigenetic Therapies
Identification and characterization of new epigenetic therapies.
Candidate epigenetic regulators are first identified with genetic RNAi screens in vitro and/or in vivo in cancer cells
to assess a phenotypic response. A challenge is that most epigenetic regulators have more than one functional
domain that can serve as a drug target. Genome editing with CRISPR/Cas9 could be used to identify the precise
domain that, when compromised, phenocopies the effects of genetic knockdown. Once a specific small molecule to
inhibit the functional domain is developed using advanced medicinal chemistry, the effects of this potential drug
can be validated by sophisticated cell and molecular biology assays in vitro as well as in animal models of cancer.
24. •Dawson, Mark A. "The cancer epigenome: Concepts, challenges, and
therapeutic opportunities." Science 355.6330 (2017): 1147-1152.
•Dawson, Mark A., and Tony Kouzarides. "Cancer epigenetics: from
mechanism to therapy." Cell 150.1 (2012): 12-27.
•Baylin, Stephen B., and Peter A. Jones. "A decade of exploring the cancer
epigenome—biological and translational implications." Nature Reviews
Cancer 11.10 (2011): 726-734.
•Ryan, Russell JH, and Bradley E. Bernstein. "Genetic events that shape the
cancer epigenome." Science 336.6088 (2012): 1513-1514.
•Maze, Ian, et al. "Every amino acid matters: essential contributions of
histone variants to mammalian development and disease." Nature Reviews
Genetics 15.4 (2014): 259-271.
•Yang, Hui, et al. "IDH1 and IDH2 mutations in tumorigenesis: mechanistic
insights and clinical perspectives." (2012): 5562-5571.
•Bhan, Arunoday, and Subhrangsu S. Mandal. "Long noncoding RNAs:
emerging stars in gene regulation, epigenetics and human
disease." ChemMedChem 9.9 (2014): 1932-1956.
References