Identification of MicroRNAs That Stabilize p53 in Human Papillomavirus-Positive Cancer Cells

Area of Science:

• Oncology
• Virology
• Molecular Biology
• Biochemistry

Background:

• High-risk human papillomaviruses (hrHPVs) are responsible for approximately 5% of global cancer cases.
• hrHPV oncoproteins E6 and E7 are crucial for cancer initiation and progression, targeting tumor suppressors like p53.
• The hrHPV E6 protein promotes p53 degradation via the E6AP ubiquitin ligase, hindering apoptosis.

Purpose of the Study:

• To identify exogenous microRNAs (miRNAs) capable of stabilizing p53 in hrHPV-positive cancer cells.
• To validate the potential of these miRNAs as therapeutic agents against HPV-driven cancers.

Main Methods:

• A high-throughput live cell screen was employed to assess p53 stabilization by miRNA transfection in hrHPV-positive cervical cancer cells.
• A p53-fluorescent protein reporter system was used to monitor p53 stability in real-time.
• Validated miRNAs were further tested in secondary reporter systems and non-reporter cells to confirm effects on endogenous p53 levels and apoptosis induction.

Main Results:

• MicroRNA-375-3p was identified as a potent stabilizer of p53, validating the screening approach.
• A total of 23 miRNAs were found to increase p53 levels in HeLa cells.
• While some miRNAs reduced E6AP levels, all identified miRNAs targeted HPV oncoprotein expression, with some inducing p53-mediated apoptosis.

Conclusions:

• Several miRNAs can stabilize p53 by counteracting the degradation pathway mediated by hrHPV E6 oncoproteins.
• The identified miRNAs demonstrate potential as novel therapeutic strategies for treating HPV-positive cancers.
• Responses to miRNA transfection showed heterogeneity across different cell lines, indicating the need for further investigation.