RNF152 promoter methylation and gene expression in oral premalignant lesions and oral squamous cell carcinoma: implications for epigenetic biomarker development

Purpose Aberrant promoter DNA methylation represents an early molecular alteration in oral carcinogenesis and has emerged as a potential source of molecular biomarkers for oral cancer. Although RNF152 has been implicated in cancer-related molecular dysregulation, its promoter methylation and expression status have not previously been specifically investigated in oral premalignant lesions (OPML) or oral squamous cell carcinoma (OSCC). Experimental design RNF152 promoter methylation and gene expression were evaluated in paired tumor/lesion and matched adjacent normal tissues from 30 patients with OSCC and 30 patients with OPML, together with oral mucosal tissues from 15 healthy controls. Matched saliva and serum samples from the patient cohorts were also analyzed to evaluate RNF152 methylation as a potential liquid biopsy marker. Quantitative methylation-specific PCR (QMSP) and quantitative real-time PCR (QRT-PCR) were performed, and associations with clinicopathological characteristics, diagnostic performance, and the relationship between promoter methylation and gene expression were investigated. Results RNF152 promoter methylation was detected in 36.7% of OSCC tumors and 70.0% of OPML lesions, whereas no promoter methylation was identified in oral mucosal tissues from healthy controls. Promoter methylation was also detected in matched saliva and serum samples from both patient groups. Reduced RNF152 expression was observed in 33.3% of OSCC and 30.0% of OPML tissues. Methylation-associated RNF152 expression loss was identified in 13.3% of OSCC and 30.0% of OPML patients. Among methylation-positive cases, concomitant RNF152 expression loss was observed in 36.4% of patients with OSCC and 42.9% of patients with OPML. Continuous promoter methylation levels were not significantly correlated with tissue gene expression in either cohort. RNF152 promoter methylation demonstrated good discriminatory performance for distinguishing OPML from healthy controls (AUC = 0.867, p < 0.001), whereas its discriminatory performance for OSCC was statistically significant but more modest (AUC = 0.683, p = 0.047). Conclusions This study provides the first comprehensive evaluation of RNF152 promoter methylation and gene expression in oral premalignant lesions and oral squamous cell carcinoma. RNF152 promoter methylation showed greater diagnostic potential for OPML than for OSCC, whereas its performance in liquid biopsy specimens was limited. The incomplete concordance between promoter methylation and gene expression suggests that promoter methylation may contribute to RNF152 downregulation in a subset of cases but is not the sole determinant of its expression. These findings support further evaluation of RNF152 as a candidate component of multimarker epigenetic panels rather than as a standalone diagnostic biomarker. Validation in larger, independent cohorts is required to determine its clinical utility.