Chromosomal Changes in Colon Cancer: Understanding Gene Mutations

Colorectal cancer (CRC) arises from accumulated mutations in multiple genes. Key driver mutations include:

Major Gene Alterations

1. APC (Adenomatous Polyposis Coli)

• Mutated in familial adenomatous polyposis (FAP) and ~1% of sporadic CRC.
• Tumor suppressor regulating cell growth; loss leads to multiple polyps.

2. KRAS (Kirsten Rat Sarcoma Viral Oncogene Homolog)

• Mutated in 20–40% of sporadic CRC.
• Oncogene in cell signaling (growth/differentiation); mutation causes uncontrolled proliferation.

3. TP53 (Tumor Protein p53)

• Mutated in 50–60% of CRC.
• Tumor suppressor for DNA repair, cell cycle, apoptosis; loss allows damaged cell survival.

4. BRAF (B-Raf Proto-Oncogene)

• Mutated in ~10% of CRC.
• Activates MAPK pathway, driving growth and proliferation.

5. PIK3CA (Phosphoinositide-3-Kinase Catalytic Subunit Alpha)

• Mutated in 15–20% of CRC.
• Activates PI3K pathway, promoting growth, proliferation, metabolism.

Other genetic, inherited, and environmental factors also contribute. Not all CRC cases involve these mutations.