Evaluating and Promoter Hypermethylation in Nonsmokers, Cancer Free Smokers and Lung Cancer Patients: A Case Control Study.

Lung cancer has very high mortality due to late stage diagnosis not amenable to curative resection. Cancer specific methylation patterns of tumor suppressor genes may precede precursor lesions of lung cancer. Our aim was to evaluate the promoter hypermethylation of tumor suppressor gene NISCH and CDH1 in cfDNA from plasma of lung cancer patients and its possible correlation with smoking status and various clinicopathological parameters. Forty histopathologically confirmed lung cancer cases, thirty smoker and thirty nonsmoker controls were enrolled. Plasma cfDNA was extracted and subjected to bisulfite treatment followed by MS-PCR. Serum nischarin levels were estimated by ELISA. The frequency of promoter hypermethylation of NISCH and CDH1 was significantly higher in lung cancer patients as compared to lifelong non-smoker controls ( < 0.05). It did not vary with smoking status among cancer cases. No significant association was found with staging or histological grading. NISCH methylation was found to be significantly higher among smoker controls. Pack years and packs per day were significantly higher in the methylated group. Serum nischarin levels showed no significant association with NISCH methylation or clinicopathological variables. NISCH is highly methylated in both high risk smoker controls as well as cancerousnon-smokers and may mark the convergence of varied etiologies of lung cancer. Hence NISCH and CDH1 are highly methylated in plasma cfDNA of lung cancer patients.