This presentation is about cancer and its types,causes. How does cell destined to become cancerous as compared to a normal cells and what are the factors that leads to carcinogenic cells. This slides is mostly targeted to degree students along with illustrative graphics to help them clearly understand about the topics.

1. CANCER

4. Formation of Cancer cells
Clonal theory

8. The Genes that have been implicated in
carcinogenesis are divided into two
broad categories:
1. Tumor-suppressor gene
2. Oncogenes
Tumor-suppressor genes act as a cell’s brakes.
Encode proteins that restrain cell growth and
prevent cell from becoming malignant. p53, RB
Oncogenes encode proteins that promote the
loss of growth control and the conversion of a
cell into a malignant state. Act as accelerators
of cell proliferation, promote metastasis. Ras,
myc

11. ACTIVATION OF ONCOGENES
• The normal-cell genes from which the retroviral oncogenes
originated are called, proto-oncogenes
• Proto-oncogenes are important cell regulatory genes, encoding
proteins that function in the signal transduction pathways
controlling normal cell proliferation (e.g., ras, src, raf)
• Oncogenes are the mutated or abnormally expressed form of
proto-oncogenes
• The mutations that convert a proto-oncogenes into an
oncogenes are created through several distinct mechanism:
1. Point mutation
2. Gene Amplification
3. Translocation

16. Retroviral Oncogenes
Oncogene Virus Species
abl Abelson leukemia Mouse
myc Avian myelocytomatosis Chicken
ras Rat sarcoma Rat
raf 3611 murine sarcoma Mouse
src Rous sarcoma Chicken
Representative Oncogenes of Human Tumor
Oncogene Type of Cancer Activation mechanism
abl Chronic myeloid leukemia, acute lymphocytic leukemia Translocation
bcl-2 Follicular B-cell lymphoma Translocation
cdk4 Melanomas Point mutation
c-myc Burkitt's lymphoma Translocation
c-myc Breast and Lung carcinomas Amplification
B-raf Melanoma, colon carcinoma Point mutation
Representative Tumor Suppressor Genes
Gene Type of Cancer
APC Colon/ rectum carcinoma
BRCA1 Breast and ovarian carcinomas
p53 Brain tumors; breast,colon/rectum, esophageal, liver and lung carcinomas
Rb Retinoblastoma; sarcomas; bladder, breast and lung carcinomas

17. • Substance that cause cancer, called carcinogens
• Many agents include radiation, chemicals and viruses have been
found to induce cancer in both experimental animals and
humans
• Radiation and many chemical carcinogens act by damaging DNA
and induce mutation.
• Solar UV radiation ( major cause of skin cancer)
• Carcinogenic chemicals in tobacco smoke (benzo(a) pyrene,
dimethylnitrosamine) & Aflatoxin( a potent liver carcinogen)
• Smoking cause nearly 90% of lung cancers, as well as cancer in
the oral cavity, pharynx, larynx, esophagus
• Smoking is responsible for nearly one-third of all cancer deaths
• Other carcinogens contribute to cancer development by
stimulating cell proliferation, rather than by inducing mutations
• Hormones such as estrogen can act as tumor promoters, when
exposure was in excess, endometrial cancer in women
• Virus , Heliobacter pylori, causes stomach cancer

20. H3C
N-N=O
H3C
Dimethylnitrosamine
Benzo(a) pyrene

21. • Both benign and malignant tumors are classified according
to the type of cell from which they arise
• Most cancer fall into one of the three main groups:
1. Carcinomas
2. Sarcomas
3. Leukemias or Lymphomas
• Carcinomas, which include approx. 90% of human cancers
are malignancies of epithelial cells
• Sarcomas, which are rare in humans, are solid tumors of
connective tissues, muscle, bone, cartilage, fibrous tissue
• Leukemia and Lymphomas, account for approx. 8% of
human malignancies arise from blood-forming cells and
from cells of the immune system
• Tumors are further classified according to tissue of origin
• For e.g., fibrosarcomas arise from fibroblasts, erythroid
leukemias from precursors of erythrocytes (RBC’s)