Many people think of cancer as a single disease, however, it actually results from more than 1,000 different disorders in normal cell and tissue function. All cancers have one feature in common: They all are diseases of uncontrolled cell division. For healthy people, the body regulates the production of new cells very precisely. But in cancer patients, gene mutation lead to breakdowns in the cell communication and growth control normal in healthy cells. Out of the normal control, cancer cells can become invasive and spread to other parts of the body. As a consequence, normal tissue and organ functions may be seriously disrupted.
Mutation in two main groups genes are closely related with cancers:
A: Proto-oncogenes, which encode for proteins important for normal cell behavior including proliferation, differentiation and survival. Proto-oncogenes will be converted to ongogenes by the change in gene structure, location, or function. At this stage, the proto-oncogenes become into the oncogenes.
Oncogens can be categorized to the following groups:
- Growth Factors: COLIA1-PDGFB, PDGF etc.
- Receptors: v-erb-b, EGF-receptor etc.
- Plasma membrane GTP-binding proteins: KRAS, Ras etc.
- Nonreceptor protein kinases: BRAF, Raf kinase etc.
- Transcription factors: MYC, v-jun, V-fos etc.
- Cell-cycle or cell-death regulators: CYCD1, CDK4 and BLC2
B: Tumor Suppressors: Tumor suppressor genes encode for proteins that regulate cell survival and slow or stop cell proliferation. Cells with mutation in these genes, will ignore signals that direct them to apoptosis.Examples of tumor suppressor genes: APC, BRCA1, BRCA2, SMAD4, NF-1, NF-2, CDKN2A, p53, RB, HL and WF1.