Investigation of methylation and expression levels of theGNG7 gene in oral squamous cell carcinoma

Demokan et al. identified 88.9% methylation of GNG7, a tumor suppressor gene, among patients with oral cavity cancer (n=9), a subgroup of head and neck cancer patients, in their study with North American head and neck cancer patients published in 2013. We hope to define the applicability of GNG7 as a biomarker for diagnosis / early diagnosis of OSCC by establishing an invasive/noninvasive technique. In this investigation, we collected tumor, normal, and serum samples from 50 patients with OSCC who were diagnosed and treated, as well as normal mucosal tissue and serum samples from 10 healthy individuals. The ratio of methylation and expression of the GNG7 gene, as well as the downregulation of the expression ratio due to methylation, were studied after the DNA was isolated. To demonstrate methylation, the QMSP method was utilized, and the QRT-PCR method was used to define expression levels. While decreased expression levels were found in 48% (24/50) of tumor tissue after the study, increased expression levels were found in 32% (16/50). No significant change in expression levels was observed in 20% (10/50) of the patients. Methylation was identified in the promoter region of the gene in 18% (9/50) of the patients' tumor tissues. Reduced expression levels were seen in 7 of 9 (77.8%) of the patients who had methylation. In matched-normal OSCC tissue and serum samples, as well as normal mucosa and serum samples from healthy people, no methylation was identified. The gene's expression was shown to be 35 fold lower in OSCC patients with methylation than in the general population. After research with larger numbers of OSCC patients, it may be able to use the GNG7 gene, which has no methylation in healthy people, as a biomarker for OSCC early diagnosis and follow-up.