Promotor hypermethylation of p14ARF is a key alteration for progression of oral squamous cell carcinoma

We investigated the promotor hypermethylation status of multiple genes in 49 oral squamous cell carcinomas (OSCC), using the methytation-specific PCR (MSP) assay. The genes examined included p16(INK4a), p14(ARF), RB1, p21(waf1), p27(Kip1), PTEN, p73, 0(6)-MGMT, and GST-P. Detailed clinicopathotogicat data, such as patient age, sex, tobacco use, alcohol consumption, lesion site, degree of tumor differentiation, tumor size, presence of lymph node metastasis, and clinical stage, were collected for all 49 samples. Overall, gene methylation was detected in 46.9% (23/49) of samples and was closely correlated with tobacco use or/and alcohol consumption. Of the genes investigated, p16IN(4a), p14(ARF), 0(6)-MGMT, RB1, PTEN, and P27(Kip1) were found to be methytated in 34.7%, 20.4%, 12.2%, 10.2%, 6.1%, and 4.1% of these 49 tumors, respectively, but methylation of p21(Waf1), p73, and GSTP was not detected at all. Methytation frequencies were much higher for each gene when computed among informative cases only. Concurrent promotor hypermethylation of p16(INK4a) and p14(ARF) correlated significantly with tumor size, lymph node metastasis, and stage III/IV advanced OSCC; p14(ARF) hypermethytation, in particular, was significantly associated with both lymph node metastasis and late clinical stage. Our results suggest that DNA methytation of multiple genes, especially hypermethytation of the p14(ARF) promoter, is common in OSCC and is associated with the use of tobacco and/or alcohol consumption. For this type of cancer, the data further implicates gene methytation as playing an important role in tumor progression. (c) 2005 Elsevier Ltd. All rights reserved.