Biology of cancer

1. PRESENTATION
ON
“BIOLOGY OF CANCER”
PRESENTED BY-
ANISHA MUKHERJEE
M.Sc FIRST SEMESTER
BIOTECHNOLOGY
GUIDED BY-
 Dr. BHAWANA PANDEY
MAM
 BHAVIKA SHARMA
MAM

2. CONTENTS
 What is cancer ?
 Characteristics of cancer cells
 Types of cancer/tumour
 Based on position
 Based on tissues
 Normal cells versus Cancer cells
 Etiology of cancer
 Physical and Chemical agents
 Molecular basis of cancer
 Oncogenes & Proto-oncogenes. E.g.:- ras gene
 Tumour suppressor gene.
E.g.:- p53 gene , Retinoblastoma(Rb)gene
• Cancer treatment
• Prevention
• Conclusion

3. WHAT IS CANCER?
 Derived from Latin word ‘cancrum’ meaning
crab.
 When any abnormality arise during cell
division or cell proliferation, then they are
called cancer or malignancy producing cells.
 It leads to abnormal growth or enlargement of
tissues.

4. CHARACTERISTICS OF CANCER CELLS
 The cancer cells do not follow the laws of proliferation
& divides uncontrollably.
 Cancer cells avoid apoptosis(programmed cell death)
and become immortal.
 Cancer cells are invasive & can spread to other tissues
& organs(Metastasis).
 Tumour cells originate from normal cells through
mutation caused by mutagens like chemicals and X-
rays.
 Cancer cells lose their contact inhibition.
 The cancer cells lose their ability to repair the damaged
DNA.

6. TYPES OF CANCER/TUMOUR
 Based on position:-
Malignant Tumour-They are characterized by
uncontrolled proliferation and spread of cells to various
parts of the body, a process referred to as metastasis.
Non-Malignant or Benign Tumour-They grow slowly &
remain localized in their place of origin. It can be cured
by surgically removing the tissue.

7. TYPES OF TUMOUR
 Based on tissues:-
Carcinoma-A tumour arising from epithelial cells.
Adenoma-A cancer of hormone secreting cell.
Sarcoma-They are malignant tumours arising from
any connective tissue.
Osteoma-They are tumours of bone.
Fibroma-It is a tumour arising from fibrous tissue.
Lymphoma-The cancerous growths developing on the
lymph nodes & the other tissues of the lymphatic
system.
Leukemia-Blood cancer.

8. NORMAL CELL VERSUS CANCER CELL

10. ETIOLOGY OF CANCER
 Multifactorial in origin:-
 Physical
 Chemical
 Biological(Viruses)
 Hormonal
 Genetic
 Mutation
 Environmental factors(physical & chemical agents)

12. PHYSICAL & CHEMICAL AGENTS
 PHYSICAL AGENTS :-
X-rays , Gamma rays , UV rays
 CHEMICAL AGENTS :-
 Aflatoxins
 Aniline(dye)
 Nitroso compounds
 Colouring agents etc
 Lifestyle-tobacco chewing, smoking, alcohol

13. MOLECULAR BASIS OF CANCER
ONCOGENES
 Greek word:- Oncos=tumour or mass
 The genes which can cause cancer are known as oncogenes.
 These oncogenes were originally discovered in tumour
causing viruses.
 These viral oncogenes were found to be closely similar to
certain genes present in normal host cells which are
referred to as proto-oncogenes.
 Proto-oncogenes encode for growth regulating proteins.
 The activation of proto-oncogenes to oncogenes is an
important step in the causation of cancer.
 Example- ras gene(sarcoma virus)

15. ras proto-oncogene

16. TUMOUR SUPPRESSOR GENES
 The genes which prevents cancer are called
anti-oncogenes or tumour suppressor genes.
 The products of these genes acts as breaks &
regulates cell proliferation.
 When these genes are mutated/deleted then it
leads to cancer.

18. CATEGORIES OF TUMOUR SUPPRESSOR
GENES
Caretaker Genes-
Maintain the integrity of the genome by
repairing DNA damage.
E.g.- BRCA1,BRCA2
Gatekeeper Genes-
Inhibit the proliferation or promote the death
of cells with damaged DNA.
E.g.- p53,Rb1

19. p53 Gene
 Called “the guardian of the genome”.
 Situated at the short arm of the chromosome 17.
 Mutated in most of the cancer cases.
 Normal functions:-
 It can activate DNA repair proteins when DNA has
sustained damage.
 It can arrest growth by holding the cell cycle at the G1/S
regulation point on DNA damage recognition(if it holds the
cell for long enough, the DNA repair proteins will have time
to fix the damage and the cell will be allowed to continue the
cell cycle).
 It can initiate apoptosis(the programmed cell death),if DNA
damage proves to be irreparable.

21. Retinoblastoma(Rb) Gene
 Responsible for retinoblastoma, a malignant tumour of
retina, a rare malignant tumour in infants.
 Two mutations are required in Rb gene to develop
Retinoblastoma.
 It occurs in two forms-
Familial Retinoblastoma-Children inherit a defective copy
of Rb gene, the other copy is normal. Retinoblastoma
develops when the normal copy
undergoes somatic mutation.
Sporadic Retinoblastoma-In sporadic
cases, both Rb alleles are lost by
somatic mutation in one of the
retinoblasts.

23. CANCER TREATMENT