Hypermethylation in the promoter regions of genes is associated with suppression of gene expression and has been considered a potential molecular marker for several tumor types, including head and neck squamous cell carcinomas (HNSCC). Moreover, hypermethylation can be detected in body fluids such as saliva and can be useful for the diagnosis and prognosis of patients suffering from cancer. To evaluate the hypermethylation profile as a tool for early detection of tumor recurrences, this study determines the methylation status of 24 genes in salivary rinses collected from HNSCC patients at diagnosis, just after the last curative treatment and in the patients' follow-up visit at 6 months after treatment. In the analysis of salivary rinse samples taken at diagnosis of HNSCC patients, five genes (CCNA1, DAPK, DCC, MGMT and TIMP3) showed high specificity and sensitivity. Hypermethylation in any of these five genes was correlated with the presence of tumors in the oral cavity. Patients with TIMP3 methylation in samples collected 6 months after the last curative treatment had lower local recurrence-free survival (P = 0.008). Multivariate analysis confirmed that this hypermethylation pattern remained as an independent prognostic factor for local recurrence (P = 0.025). This study presents, for the first time, the detection of TIMP3 promoter hypermethylation in post-treatment salivary rinse as an independent prognostic maker for local recurrence-free survival in patients with HNSCC, justifying the use of DNA hypermethylation detection in saliva as a tool for identifying and monitoring HNSCC patients' subgroups with high risk of developing local recurrence.

BackgroundHypermethylation in the promoter regions is associated with the suppression of gene expression and has been considered a potential molecular marker for several tumor types, including head and neck squamous cell carcinomas (HNSCC).MethodsTo evaluate the gene hypermethylation profile as a prognostic marker, this retrospective study used a QMSP approach to determine the methylation status of 19 genes in 70 HNSCC patients.ResultsThe methylation profile analysis of primary HNSCC revealed that genes CCNA1, DAPK, MGMT, TIMP3 and SFRP1 were frequently hypermethylated, with high specificity and sensitivity. TIMP3 and CCNA1 hypermethylation was significantly associated with lower rates of second primary tumor-free survival (p = 0.007 and p = 0.001; log-rank test, respectively).ConclusionThis study, for the first time, presents CCNA1 and TIMP3 hypermethylation as a helpful tool to identify HNSCC subjects at risk of developing second primary carcinomas.

Background. Silencing of tumor suppressor genes plays a vital role in head and neck carcinogenesis. The purposes of this study were to determine the methylation profile of exfoliated tumors cells collected from patients with head and neck squamous cell carcinoma (HNSCC) and to evaluate its prognostic significance. Methods. The methylation profile and level of a 20-gene panel were evaluated by quantitative methylation-specific polymerase chain reaction (qMSP) in exfoliated tumor cell samples from 96 patients with HNSCC. Results. CCNA1 (60.4%), DCC (54.2%), and TIMP3 (35.4%) were frequently methylated in these samples. Patients with exfoliated tumors cells positive for DCC methylation showed a trend toward a lower local recurrence-free survival. Conclusion. These findings indicate that a low invasive method could be used to access the methylation profile of exfoliated cells from patients with HNSCC. Moreover, our data provide evidence that hypermethylation of DCC could be useful as prognostic indicator for this malignancy.

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