By Dr Ananya Mandal, MD
A proto-oncogene is a normal gene that can undergo mutation to become an oncogene, a gene that has the ability to induce cancer.
A normal cell usually undergoes a process called apoptosis or programmed cell death but activated oncogenes can prevent these cells from dying and instead allow them to survive and proliferate.
Proto-oncogenes, oncogenes and cancer
There are trillions of living cells in the body that grow, divide, and die in an orderly fashion. This process is a tightly regulated by the DNA machinery or the genes within the nucleus of the cell. These genes code for proteins that help regulate cell growth and proliferation. These important genes are called proto-oncogenes.
However, a change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which produces a different protein and interferes with normal cell regulation. The cell containing the oncogene does not die, nor is the damaged DNA repaired. Instead, it gives rise to more abnormal cells containing abnormal DNA. These cells all have the same abnormal DNA as the original cancer cell. In addition, these cells can also invade other tissues, a property that normal cells do not possess.
One example of a proto-oncogene is the Myc gene, which codes for transcription factors. When the gene sequence of Myc is altered, these transcription factors are produced at increased rates and gene expression is altered giving rise to tumor formation.
Reviewed by Sally Robertson, BSc
Last Updated: Apr 1, 2014