Question

Compare and contrast the roles of oncogenes and tumor suppressors in oncogenesis. How were each discovered and studied? What is unusual about p53 in terms of being a tumor suppressor?

Answer 1

The oncogenes are genes which induces the formation of the tumor because of its potential to proliferate and become cancerous. The oncogenes are majorly present in the tumor cells and are expressed at a very high rate. The proto-oncogenes are activated when there is a mutation and it starts to multiply and produce multiple copies forming the oncogenes. The tumor suppressor genes are those which helps in slowing down mistakes during DNA replication, slow down cell division and signals apoptosis and hence helps in suppressing formation of tumor. The tumor suppressor genes when are inactivated through mutation causes cancer and oncogenes when activated causes cancer.

The first oncogene that was discovered with confirmation was in the year 1970 and was called sarcom and it was found within the chicken retrovirus. The tumor suppressor gene was found after the two hit hypothesis that was given by A.G Knudson and it was found in the retinoblastoma.

The p53 is a tumor suppressor gene but its activity depends on what is being inherited. If a person inherits one copy of the p53 that is function, it has predisposition to cancer formation and may form independent tumors. When it contains both copy, it helps in suppressing the tumor formation.