Write the role of gene in malignant transformation.

Role of gene in malignant transformation:

1. Nonlethal genetic damage lies at the heart of carcinogenesis. Some of the genetic damage may be acquired by the action of environmental agents such as chemicals or virus or may be inherited.
2. A tumor is formed in the clonal expansion of a single precursor cell that has incurred the genetic damage.
3. Four classes of normal regulatory genes - i) The growth promoting protooncogenes, ii) The growth inhibiting tumor suppressor genes, iii) Genes that regulate programmed cell death, iv) And genes involved in DNA repair are principal targets of genetic damage.
4. DNA repair genes affect cell proliferation or survival indirectly by influencing the ability of the organism to repair non-lethal damage in other genes, including proto-oncogenes, tumor suppressor genes and genes that regulate apoptosis
5. Carcinogenesis is a multistep process at both the phenotypic and the genetic levels.