Oncogenes are mutated proto-oncogenes that can cause normal cells to become cancerous. Proto-oncogenes regulate cell growth and differentiation and are involved in signal transduction and mitogenic signals. They can become oncogenes through point mutations, increased expression from gene amplification, or chromosomal translocations. The first confirmed oncogene, src, was discovered in 1970. Oncogenes are classified into groups based on their functions, such as secreted growth factors, cell surface receptors, intracellular transducers, and regulators of the cell cycle. The challenge is developing cancer treatments that kill cancer cells without harming healthy cells.

1. Balbeer Singh
1248126
SZABIST, Karachi

2. Introduction
• Onco means Cancer
• Oncogene is a gene which in certain circumstances can
transform a cell into a tumor cell.
• A Proto-oncogene is a normal gene that can become an
oncogene due to mutations or Increased expression
• The resultant protein encoded by an oncogene is termed
Oncoprotein
Proto-oncogene  “Mutation”  Oncogene

3. History
• The term “Oncogene" was coined in 1969 by George Todaro
and Robert Heubner. Of National Cancer Institute.
• The first confirmed Oncogene was discovered in 1970 and
was termed src
• In 1976 Drs. Dominique Stehelin, J. Michael and Harold E.
Varmus of the University of California demonstrated that
oncogenes were activated Proto-Oncogenes, found in many
organisms including humans

4. Functions of Proto-Oncogene
• Help to regulate Cell growth and differentiation
• Involved in Signal Transduction
• Involved in execution of Mitogenic Signals

5. Activation
The proto-oncogene can become an oncogene by a relatively
small modification of its original function. There are three basic
methods of activation:
• A mutation within a proto-oncogene, or within a regulatory
region (for example the promoter region), can cause a change
in the protein structure.
• An increase in the amount of a certain protein
• A chromosomal Translocation(another type of Chromosome
abnormality)

6. Mechanisms of Oncogene
Activation
1. Point Mutation
H-ras [codon 12]
Normal CGC  Gly
Bladder cancer CTC  Val
2. Gene Amplification
Double minutes
HSRs
Normal copy Multiple copies

7. 3. Gene Translocation
Ex. Burkitt’s Lymphoma

8. On chromosome 18, there's an
oncogene called BCL2
In people with a certain kind of leukemia, this
gene has been moved in its entirety from
chromosome 18 to chromosome 14.

10. Classification of Oncogene
Secreted Growth Factors
• c-sis, hst
Cell Surface Receptors
• erb B, fms, ret, trk, fes, fms
Intracellular Transducers
• c-src, c-abl, mst, ras
DNA-binding Nuclear Proteins
• myc, jun, fos
Regulators of the Cell Cycle
• bcl, bax, bad

14. It is easy to kill cancer, but the
challenge is keeping the patients
alive at the same time