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Erschienen in:
11.03.2016 | Original Article
Prognostic value of the DNMTs mRNA expression and genetic polymorphisms on the clinical outcome in oral cancer patients
Erschienen in: Clinical Oral Investigations | Ausgabe 1/2017
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Objectives
Although the importance of the epigenetic changes in tumors, including oral squamous cell carcinomas (OSCCs), is now becoming apparent, the mechanisms that trigger or cause aberrant DNA methylation in cancer are still unrevealed. DNA methylation is regulated by a family of enzymes, DNA methyltransferases (DNMTs). DNMT gene expression analysis, as well as genetic polymorphisms, has not been previously evaluated in OSCC.
Materials and methods
In 65 OSCC patients, SYBR Green real-time PCR method was assessed for relative quantification of DNMT1, DNMT3A, and DNMT3B mRNAs, normalized to TATA-binding protein (TBP) mRNA. The expression levels of all three genes were dichotomized as high or low, with a twofold change of normalized mRNA expression used as the cutoff value. Polymorphisms in DNMT1 (rs2228612) and DNMT3B (rs406193) were analyzed in 99 OSCCs by TaqMan SNPs genotyping assays.
Results
DNMT1, DNMT3A, and DNMT3B were overexpressed in 36.9, 26, and 23 % of the OSCC patients, respectively. DNMT1 overexpression was significantly associated with the overall survival, p = 0.029, and relapse-free survival of OSCC patients, p = 0.003. Patients with DNMT1 overexpression, as an independent prognostic factor, had a 2.385 times higher risk to relapse than those with lower expression. The DNMT1 A201G gene polymorphism was associated with a reduced overall survival in OSCC patients, p = 0.036.
Conclusions
Our results suggest that DNMT1 could play an important role in modulating OSCC patient survival.
Clinical relevance
DNMT gene expression could be a potential prognostic marker that might lead to an improvement in diagnosis, prognosis, and prospective use of epigenetic-targeted therapy of OSCC.