Single nucleotide polymorphism and expression of P16 gene as a potential biomarker for oral and pre-oral cancer.

Objective: This study investigated the association between p16 gene and its 450 C > G (rs11515) polymorphism with risk of oral cancer and precancerous oral lesions/oral potentially malignant disorder (OPMD).

Method: The study included 230 individuals with OPMD conditions (70 with leukoplakia, 90 with oral submucous fibrosis, and 70 with lichen planus), 72 oral cancer patients, and 300 cancer-free healthy controls. Genotyping of the p16 450 C > G polymorphism was conducted using PCR-RFLP methods, and genotype and allele frequencies were analyzed using chi-square test. Additionally, p16 gene expression levels were measured using RT-PCR among oral cancer patients, those with OPMD, and healthy controls. RNA fold was used to calculate the MFE of p16 mRNA.

Results: The findings revealed that G allele of p16 450 C > G polymorphism significantly increased risk of oral diseases (oral cancer and OPMD) compared to C allele (OR 1.67, p = 0.0001). GG genotype was associated with higher risk of oral submucous fibrosis (OR 4.63, p = 0.0001), lichenplanus (OR 3.93, p = 0.0002), and leukoplakia (OR 2.38, p = 0.02) compared to CC genotype. Smokers and tobacco chewers carrying the G allele were at a significantly increased risk of developing OPMD (OR = 3.78 and 2.89). Notably, p16 transcript expression was significantly elevated (13.56-fold) in oral cancer patients compared to healthy controls. According to insilco analysis G allele gives more stable transcript of p16 (MEF - 64.90 kcal/mol) compared to C allele (MFE - 61.70 kcal/mol).

Conclusion: These findings suggest that p16 gene and its 450 C > G polymorphism may be associated with risk of oral diseases, indicating their potential utility as biomarkers for these conditions.