Aberrant methylation of mutL homolog 1 is associated with increased risk of non-small cell lung cancer.

Abstract

Non-small cell lung cancer (NSCLC) is a common malignant tumor. DNA hypermethylation in the promoter region has been served as a potential molecular marker for several tumors. The goal of the current study was to assess the diagnostic ability of mutL homolog 1 (MLH1) promoter methylation in NSCLC. A total of 111 NSCLC patients' paired tissue samples were obtained to explore the association between MLH1 promoter methylation and NSCLC by methylation-specific polymerase chain reaction (MSP) method. Public databases including The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were used to verify our findings. Our results showed a significantly higher MLH1 methylation frequency in tumor tissue samples than their paired adjacent tissues (P=.008). ROC curve indicated that MLH1MSP assay was a sensitive but not a specific method in the diagnosis for NSCLC (sensitivity=0.964, specificity=0.135, AUC=0.550). And the association between the methylation level and clinical characteristics has no statistical significance. TCGA cohort evinced a higher methylation probability in tumor group compared with nontumor group (the mean β value: -0.449 [-0.467, -0.437] vs -0.466 [-0.472, -0.437], P=.011), which was consistent with our results. Meanwhile, an inverse correlation between MLH1 methylation and MLH1 expression was detected in TCGA and GEO databases. The MSP method for MLH1 methylation was a sensitive but not a specific diagnostic method for NSCLC.