Structure based identification and characterization of flavonoids that disrupt human papillomavirus-16 E6 function

Area of Science:

• Molecular Biology
• Oncology
• Virology
• Medicinal Chemistry

Background:

• Human papillomavirus (HPV) oncoproteins, particularly E6, are crucial for viral replication and oncogenesis in cervical cancers.
• HPV E6 targets the tumor suppressor protein p53 for degradation by hijacking the E6AP ubiquitin ligase, promoting uncontrolled cell proliferation.
• Disrupting the E6-E6AP interaction offers a potential therapeutic strategy to stabilize p53 and inhibit HPV-driven cancers.

Purpose of the Study:

• To develop a high-throughput assay to identify inhibitors of the HPV-16 E6 and E6AP interaction.
• To synthesize and characterize novel flavonoid compounds based on luteolin as potential E6/E6AP inhibitors.
• To evaluate the efficacy of these compounds in disrupting the E6-E6AP interaction and their effect on HPV-positive cancer cells.

Main Methods:

• Development of an in vitro high-throughput binding assay for HPV-16 E6 and E6AP.
• Screening for compounds that inhibit E6/E6AP interaction, leading to the identification of luteolin.
• Synthesis and characterization of a novel flavone library inspired by luteolin's structure.
• Assessment of compound effects on p53 and p21(Cip1/Waf1) levels and proliferation in HPV-positive cell lines.
• Molecular docking analyses to predict binding modes and interactions within the E6/E6AP interface.

Main Results:

• A novel class of flavonoid compounds was identified that effectively disrupt the E6/E6AP interaction.
• These compounds increase the levels of tumor suppressor proteins p53 and p21(Cip1/Waf1) in HPV-positive cells.
• The identified inhibitors significantly decrease the proliferation of HPV-positive cancer cell lines.
• The flavonoid inhibitors exhibit high specificity for HPV-positive cells, with docking studies suggesting a mechanism involving binding to a hydrophobic pocket at the E6/E6AP interface.

Conclusions:

• Novel flavonoid compounds targeting the E6/E6AP interaction represent a promising new therapeutic lead for HPV infection and cervical cancer.
• These compounds demonstrate specific antiviral activity against HPV-positive cells by restoring p53 function.
• The findings support the development of flavonoid-based inhibitors as a targeted antiviral therapy for HPV-related malignancies.