Low Expression of SCN4B Correlated with DNA Hypermethylation and Poor Prognosis in Non-small Cell Lung Cancer

Abstract

Background:Voltage-gated sodium channels β subunits 4 (SCN4B), a tumor suppressor, was previously reported to be associated with DNA methylation and poor prognosis in multiple cancers except lung cancer. This study aimed to explore whether the low expression of SCN4B was correlated with DNA methylation and clinical prognosis in non-small cell lung cancer (NSCLC) . Methods:The gene expression profiles (GDS3837and GSE50081) were extracted from Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) analysis was performed to explore the expression of SCN4B in NSCLC tissue compared with normal tissue, with the cut-off value p < 0.05 and the absolute value of the log2 fold change ≥ 1.5. Immunohistochemistry staining was used to validated its expression using The Human Protein Atlas database. And MPRESS was used to analysis the relations of SCN4B expression between DNA methylation. Then, the Fisher exact and Wilcoxon rank-sum tests were used to calculate the associations of SCN4B expression with NSCLC clinicopathological features such as clinical grade and tumor node metastasis (TNM) stage, while Kaplan–Meier survival analysis and cox regression analysis were performed to estimate the prognostic value of SCN4B expression in NSCLC. Results: Our DEGS analysis results showed a significantly decreased expression of SCN4B (p=6.5e-22) in NSCLC, which were validated by immunohistochemistry staining. Besides, this decreasing trend continued as the clinical grade and T stage advanced (p<0.05). There was a negative correlation between the SCN4B expression and DNA promoter methylation (p<0.01). Kaplan–Meier survival analysis indicated that NSCLC patients with low expression of SCN4B had a worse prognosis than those with high expression (p < 0.004). Meanwhile, univariate and multivariate analysis indicated SCN4B expression was an independent unfavorable prognostic factor for OS in NSCLC (Hazard Ratio= 0.236, p = 0.009; Hazard Ratio=0.219, p = 0.003, respectively).Conclusions: SCN4B expression was significantly downregulated in NSCLC, which might be attributed to DNA promoter hypermethylation. The low expression of SCN4B indicated a potential unfavorable prognostic factor for NSCLC patients.