Investigation of the epigenetic biomarker potential of the NDUFB3 gene in oral premalinant lesions involved in mitochondrial electron transport

Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cavity cancers, which are among the head and neck cancers. Oral cancer is a type of cancer in which both genetic and epigenetic studies are examined together since it is frequently affected by environmental features. The most common epigenetic modification observed in oral cancers is DNA methylation, which is the covalent addition of a methyl group (CH3) to the carbon at position 5 of cytosine in the 5′-CG-3′ sequence of DNA. In the study numbered TÜBİTAK-SBAG-114S497 by Demokan et al., it was observed that tumor tissue in OSCC patients was hypomethylated in the CpG islets in the promoter region of the NADH:Ubiquinone NADH Dehydrogenase (NDUFB3) gene compared to the conjugated normal tissue, and accordingly, there was an increase in its expression levels. In our study, we examined the expression and methylation levels of the NDUFB3 gene in tumor, conjugated normal tissue, serum and saliva samples from 30 OSCC and 30 OPML patients and in normal mucosa, serum and saliva samples from 15 healthy individuals. The potential utility of the NDUFB3 gene as a biomarker in the early diagnosis of cancer was examined by comparing the clinical information and molecular differences between data from OSCC and OPML patient groups and healthy groups. The qRT-PCR method was used to determine the expression level of the NDUFB3 gene, and the qMSP method was used to determine the methylation level. As a result of the experiments; While a decrease in expression level was observed in approximately 23% of the OPML patient group, an increase in expression level was observed in approximately 36%, no significant change in expression level was observed in 40%. Compared to the conjugated normal tissue, approximately 33% of OSCC patients had an increase in expression level and a decrease in 40%. No methylation was found in tumor, normal serum and saliva samples of OSCC and OPML patients and healthy group. Although the changes in the expression level of OSCC and OPML patient groups were significant when compared with clinical parameters, it was determined that there was no significant effect on the changing expression levels because the presence of methylation could not be detected. Changes in the expression level of the NDUFB3 gene in OSCC and OPML patient groups are thought to be due to mutations in the carcinogenesis mechanism.