How can mutations lead to tumors?

How can mutations lead to tumors?

• A. Mutations in genes that control the cell cycle can cause uncontrolled mitosis and tumor formation.
• B. Mutations in any gene always cause tumors.
• C. Mutations only affect non-dividing cells.
• D. Mutations have no effect on cell cycle.

Answer: (A)

Mutations that disrupt genes controlling the cell cycle remove the normal brakes on cell division, letting cells proliferate without the usual safeguards. The cell cycle relies on checkpoints, especially at G1/S and G2/M, governed by proteins like cyclins, CDKs, RB, and p53. When these genes are mutated, a cell can pass checkpoints despite DNA damage or abnormal growth signals, continuing to divide and accumulating more mutations. This uncontrolled mitosis leads to a clonal expansion of abnormal cells, which forms tumors. Over time, additional changes such as evading apoptosis, sustaining telomeres, and promoting blood vessel growth can further support tumor growth.

Mutations that disrupt genes controlling the cell cycle remove the normal brakes on cell division, letting cells proliferate without the usual safeguards. The cell cycle relies on checkpoints, especially at G1/S and G2/M, governed by proteins like cyclins, CDKs, RB, and p53. When these genes are mutated, a cell can pass checkpoints despite DNA damage or abnormal growth signals, continuing to divide and accumulating more mutations. This uncontrolled mitosis leads to a clonal expansion of abnormal cells, which forms tumors. Over time, additional changes such as evading apoptosis, sustaining telomeres, and promoting blood vessel growth can further support tumor growth.