Investigation of the genetic and epigenetic profile of the GPRC5C gene in malignant and premalignant lesions of the oral cavity

Oral cancer is one of the best cancer models showing gene-environment interaction. Oral Squamous Cell Carcinoma (OSCC) accounts for 30% of annual head and neck cancer cases and 95% of oral cancers in the world. It occurs as a result of the transformation of oral premaline lesions (OPML) as well as smoking / alcohol use, HPV and UV, which are among the etiological factors of OSCC. Genetic and epigenetic mechanisms are effective in OSCC and OPML development. Prof. Dr. According to the array results of the project of Semra Demokan et al., TÜBİTAK-114S497, the methylation and expression levels of the GPRC5C gene, whose expression level was decreased due to methylation, were examined in the patient group of oral squamous cell carcinoma (OSCC) and oral premaline lesion (OPML). In our study, molecular differences between OPML groups with high and low risk of malignancy transformation and between OPML and OSCC were determined by comparing the data obtained from healthy individuals, and the potential of GPRC5C as a biomarker that can be used in diagnosis, diagnosis and treatment with non-invasive methods was examined. In our study, DNA and RNA isolations were performed in tumor, conjugated normal tissue, serum and saliva of 30 patients who were diagnosed with OSCC and OPML and in normal mucosa, serum and saliva of 15 healthy individuals as a control group. The QMSP method was used to determine the methylation levels of the GPRC5C gene, and the QRT-PCR method was used to determine the expression level. Methylation and expression rates were determined and expression loss due to methylation was examined. As a result of the experiments, methylation in the promoter region of the GPRC5C gene was observed in 4 (13.33%) of 30 patients in the OSCC group, decreased expression levels of the GPRC5C gene in 13 (43.33%) and increased expression levels in 10 (33.33%) of them. Differences were observed in the expression levels of 7 (23.33%) patients. In the OPML group, 2 (6.67%) of 30 patients had methylation in the promoter region of the GPRC5C gene, 12 (40%) had decreased expression levels of the GPRC5C gene, and 13 (43.33%) had increased expression levels, while 5 (16%) , 67) observed differences in the expression levels of the patient. Although there were significant differences between the changes in expression level and clinical parameters (degree of differentiation, LNT, stage, anatomy, pathology) in OSCC and OPML patient groups, it was observed that methylation observed at low rates had no effect on varying expression levels.