Which HPV types are MOST commonly implicated in cervical carcinoma, and what is the mechanism by which they cause malignant transformation?
- A HPV 16 and 18; E6 protein degrades p53 and E7 protein inactivates Rb ✓
- B HPV 6 and 11; E6 protein degrades p53 and E7 protein inactivates Rb
- C HPV 16 and 18; L1 protein integrates into host genome and activates MYC
- D HPV 31 and 33; E5 protein disrupts cell adhesion and promotes invasion
Correct answer: A. HPV 16 and 18; E6 protein degrades p53 and E7 protein inactivates Rb
Explanation
HPV 16 and 18 together account for approximately 70% of cervical cancers. The oncoproteins E6 and E7 are critical: E6 binds and degrades the tumor suppressor p53, preventing apoptosis, while E7 binds and inactivates the retinoblastoma (Rb) protein, releasing E2F transcription factors that drive cell cycle progression into S-phase. HPV 6 and 11 are low-risk types that cause condylomata acuminata but not cervical carcinoma.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
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