Human papillomavirus type 16 Protein E6, Protein E7, and Protein E5 (HPV-16 E6/E7/E5)

The Human papillomavirus type 16 (HPV-16) E6, E7, and E5 oncoproteins are the primary drivers of viral-induced oncogenesis in high-risk HPV infections (PubMed: 31151218). E6 and E7 are constitutively expressed in HPV-associated cancers and are essential for the maintenance of the malignant phenotype (UniProt: P03126, P03129). E6 promotes the ubiquitin-mediated degradation of the tumor suppressor p53, thereby inhibiting apoptosis and allowing the accumulation of DNA damage (PubMed: 25747783). E7 binds to and inactivates the retinoblastoma protein (pRb), leading to the release of E2F transcription factors and uncontrolled cell cycle progression into the S-phase (PubMed: 25747783). E5, a membrane-associated protein, complements these activities by modulating growth factor signaling, such as the epidermal growth factor receptor (EGFR) pathway, and aiding in immune evasion (UniProt: P06463). Because these proteins are foreign to the host and specifically expressed in infected and cancerous cells, they are ideal targets for therapeutic vaccines and targeted molecular therapies (PubMed: 31151218). Current clinical efforts focus on therapeutic vaccines, such as VGX-3100 and ISA101, designed to elicit a robust T-cell response to eradicate HPV-positive lesions and prevent cancer progression (ClinicalTrials.gov: NCT02425306, NCT01107392).

Other names

HPV16 E6/E7/E5Human papillomavirus 16 early proteinsHPV-16 oncoproteinsHuman papillomavirus type 16 E6, E7, and E5

Therapeutic vaccines target these oncoproteins to induce a T-cell mediated immune response, specifically activating CD8+ cytotoxic T lymphocytes and CD4+ helper T cells to recognize and eliminate cells expressing the E6 and E7 antigens (PubMed: 31151218). Experimental small molecules and gene-silencing approaches (siRNA, CRISPR/Cas9) aim to disrupt the interaction of E6 with p53 and E7 with pRb, or directly reduce oncoprotein expression, thereby restoring tumor suppressor pathways and inducing apoptosis in malignant cells (PubMed: 25747783).