HPV-16 E6 and E7 Oncoproteins Promote Cell Proliferation and Migration Through the miR-218-5p/PIK3C2A Axis

The continuous expression of HPV oncogenes E6 and E7 contributes to the maintenance of the cervical cancer (CC) phenotype by altering gene expression programs involved in tumor progression and aggressiveness. MicroRNAs (miRNAs) have emerged as critical regulators of gene expression in CC, including miR-218-5p, which has been described as a tumor suppressor. In this study, we investigated the impact of HPV-16 oncoproteins E6 and E7 on the regulation of miR-218-5p expression and its target gene PIK3C2A, as well as their functional and clinical relevance in CC. We found that miR-218-5p expression is significantly reduced in HPV-16-positive CC cell lines, while PIK3C2A expression is increased. Silencing the expression of the E6/E7 oncogenes in Ca Ski cells restored miR-218-5p levels and reduced PIK3C2A expression. Conversely, overexpression of the E6 and E7 oncogenes in C-33 A cells significantly decreased miR-218-5p expression and increased PIK3C2A expression. Functional assays performed on C-33 A cells expressing E6 and E7 revealed that ectopic expression of miR-218-5p suppresses cell proliferation and migration, effects that are partially mediated by PIK3C2A. Bioinformatics analysis showed that low miR-218-5p expression and high PIK3C2A expression are associated with reduced overall survival in patients with cervical cancer. Our findings identify the miR-218-5p/PIK3C2A axis as a novel regulatory pathway modulated by HPV-16 oncoproteins E6 and E7 that contributes to CC cell proliferation and migration. Furthermore, miR-218-5p and PIK3C2A emerge as potential prognostic biomarkers in CC.