Correlation of p16 Protein Status With MicroRNA Expression in Squamous Cell Carcinoma of the Mobile Tongue: A Pilot Study

BackgroundThe role of p16 as a surrogate marker for human papillomavirus (HPV) infection in pure mobile-tongue squamous cell carcinoma (TSCC) remains controversial, and potential associations between p16 status and microRNA (miRNA) expression profiles are largely unexplored. ObjectiveThe objective of this study was to perform a pilot, hypothesis-generating correlative analysis of p16 protein expression (used here strictly as a surrogate marker, without direct HPV testing) and pre-existing miRNA data in an archival cohort of mobile-TSCCs, with the aim of nominating candidate miRNAs for future validation rather than identifying a definitive miRNA signature. MethodsPaired tumor and adjacent non-neoplastic specimens from 12 consecutive patients with primary mobile-TSCC who underwent surgical resection between 2010 and 2011 were previously profiled for mature miRNA expression.After exclusion of one sample for failure of the original quality-control criterion and one further case with incomplete p16 or miRNA data, a final matched cohort of 10 patients was analyzed.p16 immunohistochemistry was performed on formalin-fixed paraffin-embedded tumor sections; positivity was defined as moderate-to-intense nuclear and cytoplasmic staining in ≥70% of neoplastic cells.Associations between tumor miRNA cycle-threshold values (84 mature human miRNAs) and p16 status, as well as other clinicopathological variables, were examined with non-parametric tests and Benjamini-Hochberg falsediscovery-rate (FDR) correction. ResultsTwo of the 10 tumors (20%) were classified as p16-positive.Twelve miRNAs exhibited nominal differences between p16-positive and p16-negative tumors (uncorrected Mann-Whitney p = 0.044 for all 12); none remained statistically significant after FDR correction (all FDR ≥ 0.31).The most pronounced numerical elevations in the p16-positive subset were observed for miR-150-5p (approximate fold-change 9.6), miR-206 (6.9), miR-155-5p (4.9), miR-146a-5p (4.0) and miR-29b-3p (3.8).No robust associations were identified with patient outcome, sex, T-stage, histological differentiation, tumor side, hospital of origin, or age.The study was not powered to detect moderate effect sizes and all analyses are exploratory. ConclusionsIn this small pilot cohort, p16 status showed only nominal, non-FDR-significant differences in miRNA expression.The numerical elevation of the established oncomiR miR-155-5p in the two p16-positive tumors is hypothesis-generating but requires confirmation in larger multi-institutional series that incorporate both rigorous p16 assessment and direct HPV molecular testing.