Answer to Question #64957 in Molecular Biology for Sanjukta Ghosh

Question

I think this belongs to two categories: Molecular biology and Genetics

Can you tell me what are the differences between c-onc and v-onc?

Here's something what I have understood:

v-onc stands for viral-oncogene.It is a retroviral gene that induces cancer in host cell. It is derived from the cellular proto-oncogene and acquired from the host by recombination. It cause cancer by acute transformation. E.g. v-src

c-onc is cellular proto-oncogene. e.g. c-src.

What I don't understand is that whether c-onc is cellular the proto-oncogene a v-onc has been derived from? If so can it independently or in association with v-onc cause cancer?

Answer 1

Proto-oncogenes are called this way because they are the genes that may cause cancer if something goes wrong (proto-oncogene becomes oncogene). There is a variety of ways this change can happen: amplification of the proto-oncogene (results in more RNA product), enhancing mutations in the promoters or transcription factors, epigenetic changes etc.
Viral oncogenes (v-onc) are indeed derived from the c-onc. The most basic explanation of the v-onc cancerogenic effects is that insertion of v-onc into the genome mimics the amplification of c-onc (proto-oncogene). Also, insertion of v-onc under the control of strong promoter mimics activating mutations in the c-onc regulatory machinery.