What is Oncogenes?
Those genes which have the potential to cause cancers are called as
. These genes are present inside our body cells but in an inactivated form. Due to certain mutations or due to certain enzymes activations these genes become active and convert the normal cells to tumor cells. Most of these genes requires a additional process such as mutation by Xrays , some extreme environmental conditions or viral infections which mutate the DNA to cause cancer. The normal cells under goes programmed cell death process which causes the removal of old cells and let the new cells replace them. But, these activated cancerous genes make those cells to survive and proliferate instead of dying.
Formation of Proto Oncogenes:
When a normal gene, due to mutation or increased expression, becomes a oncogene, they are called as proto oncogenes. These genes releases a protein called as onco-protein. They codes for these proteins which in turn help them regulate the cell growth and differentiation. Examples of proto-oncogenes include RAS, WNT, MYC, ERK, and TRK.
What is the Factors Leading to Activation of Oncogenes?
- Mutation within a proto oncogene causes change in their protein structure leading to :
- Increase in enzyme activity.
- Loss of regulation.
- High level of protein expression (mis regulation).
- Increase in mRNA stability leading to its longer existence in the cell and hence even its activity in cell.
- Gene duplication which leads to high release of proteins in cell.
- High level of gene expression in a wrong type of cell and in a wrong time.
- Expression of a active hybrid protein. This condition leads to a type of error in a dividing stem cell of the bone marrow leading to adult leukemia.
Conversion of These Cancerous Genes
There are 2 mechanisms by which they get converted:
Increased production of cancerous genes in an inappropriate cell type.
Conversion of these genes to transforming genes by changing the nucleotide sequence.