HPV16 E6 and E7 oncoproteins regulate Notch-1 expression and cooperate to induce transformation

Area of Science:

• Oncology
• Molecular Biology
• Virology

Background:

• Notch receptor signaling is involved in cellular transformation.
• Notch-1 expression increases during cervical intraepithelial neoplasia (CIN) progression to invasive cervical carcinoma.
• Notch-1 protein shifts from cytoplasmic to nuclear localization during cervical cancer progression.

Purpose of the Study:

• To investigate if human papillomavirus (HPV) E6 and E7 proteins cause Notch-1 upregulation.
• To determine the mechanisms behind E6/E7-mediated Notch-1 changes.
• To assess the impact of Notch-1 downregulation on cervical cancer cell proliferation and tumorigenicity.

Main Methods:

• Transfection of mouse and human primary cell lines with HPV16 E6 and E7.
• Analysis of Notch-1 expression, activity, and protein localization.
• Assessment of Presenilin-1 (PS-1) expression.
• Downregulation of Notch-1 in E6/E7-expressing human cervical carcinoma cells.

Main Results:

• HPV E6 and E7 independently upregulate Notch-1 expression and activity via transcriptional and post-transcriptional mechanisms.
• Presenilin-1 (PS-1), a Notch processing protein, is also upregulated by E6 and E7.
• Notch-1 protein is localized in the cytoplasm in the presence of E6 and E7.
• Downregulation of Notch-1 inhibited proliferation and tumorigenicity of E6/E7-expressing cervical cancer cells.

Conclusions:

• HPV E6 and E7 proteins upregulate Notch signaling pathways.
• E6/E7-mediated Notch signaling contributes to the disruption of normal cell growth in cervical cancer.
• Targeting Notch signaling may offer a therapeutic strategy for cervical cancer.