Question

List the categories of genes that are typically mutated in cancer. For each category, briefly state how the mutation would contribute to carcinogenesis

Answer 1

Cancer can be defined as the uncontrolled growth of abnormal cells in the body . This results when the normal control mechanisms of body fails. There are different kinds of cancers and mutation of a number of genes can result in cancers.

The major category of gene mutations that are involved in cancer are,

• Tumor supressor genes - Tumor supressor genes are actually protective in function. They supress tumors by regularly checking the progress of cell cycle, its check points and identifies whether any error has occured in DNA replication or whether the error repair has been done by various repair mechanisms. So, a loss of function mutation in a tumor supressor gene (ie when its function of protection is lost) can result in cancer. An important example is a loss of function mutation in p53 gene ( a tumor supressor gene) which is also known as the guardian of our genome.

• Proto oncogenes - Proto oncogenes are group of genes when mutated becomes oncogenes that has the potential to cause cancer. ie; a gain of function mutation of a proto oncogene results in cancer. Usually mutations in proto oncogenes are dominant mutaions. Example for proto oncogenes include WNT, MYC, ERK etc.

• DNA repair genes - DNA repair mechanisms involve a collection of different processes by which a cell identifies and corrects the damage that has been caused to the genome. So, a loss of function mutation in this DNA repair genes can result in cancer. Different DNA repair genes include, Base Excission repair, Nucleotide Excission Repair, Recombinatorial repair and Mismatch repair genes.