Which factors can lead normal cells to become malignant?

Which factors can lead normal cells to become malignant?

• A. Overexpression of oncogenes
• B. Underexpression of tumor suppressor genes
• C. Viral infection
• D. All of the above

Answer: (C)

Normal cells become malignant when additional genetic changes remove growth restraints and push them toward unchecked proliferation. Overexpression or activation of oncogenes drives signals that promote cell growth and division. At the same time, loss or inactivation of tumor suppressor genes eliminates key brakes on the cell cycle and can enable accumulation of further mutations and resistance to cell death. Viral infections can contribute by introducing viral oncogenes or disrupting normal regulation of host genes, as seen with certain oncogenic viruses. Cancer typically requires multiple cooperating events, so any one of these mechanisms can initiate change, and together they often drive malignant transformation.

Normal cells become malignant when additional genetic changes remove growth restraints and push them toward unchecked proliferation. Overexpression or activation of oncogenes drives signals that promote cell growth and division. At the same time, loss or inactivation of tumor suppressor genes eliminates key brakes on the cell cycle and can enable accumulation of further mutations and resistance to cell death. Viral infections can contribute by introducing viral oncogenes or disrupting normal regulation of host genes, as seen with certain oncogenic viruses. Cancer typically requires multiple cooperating events, so any one of these mechanisms can initiate change, and together they often drive malignant transformation.