Human Papillomavirus type 16

1. Overview of HPV16

HPV16 encodes proteins that interfere with human tumor suppressors:

Viral Protein	Function / Mechanism
E6	Binds p53 → promotes ubiquitination and degradation → prevents apoptosis, allows accumulation of mutations
E7	Binds pRb (retinoblastoma protein) → releases E2F transcription factor → uncontrolled cell cycle progression
E5	Enhances EGFR signaling and immune evasion

Tumor Type	Notes / Epidemiology
Cervical cancer	~50–60% of cases worldwide
Oropharyngeal squamous cell carcinoma (OPSCC)	~60–80% HPV-positive cases are HPV16
Anal cancer	~85–90% HPV-positive cases
Penile, vulvar, vaginal cancers	Less frequent, but HPV16 is common among high-risk types

Pathogenesis:
- HPV16 infection → integration into host genome → E6/E7 overexpression → inactivation of p53 and Rb → uncontrolled proliferation → malignant transformation
Prognosis:
- HPV16-positive oropharyngeal cancers often have better response to therapy and improved survival compared to HPV-negative cases
Screening / Prevention:
- Cervical cytology (Pap smear) and HPV DNA testing
- Vaccination (Gardasil, Cervarix) prevents infection with HPV16

No direct antiviral therapy for HPV16-induced cancers; therapy focuses on standard oncologic treatments:
- Surgery, radiation, chemotherapy, immunotherapy
Vaccine-preventable:
- HPV16 is a target in prophylactic vaccines, dramatically reducing risk of cervical and other HPV16-associated cancers
Emerging approaches:
- Therapeutic vaccines targeting E6/E7 proteins
- Immune checkpoint inhibitors in HPV-positive head & neck cancers

Key Points

HPV16 is a high-risk oncogenic virus driving multiple epithelial cancers.
E6 and E7 viral proteins inactivate p53 and Rb → cell cycle dysregulation → malignancy.
Vaccination and screening are critical for prevention.

Synonyms

HPV16