Decreased miRNA-148a is associated with lymph node metastasis and poor clinical outcomes and functions as a suppressor of tumor metastasis in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, and only 15% of lung cancer patients live more than 5 years. microRNAs (miRNAs) are endogenously expressed non-coding RNAs, and dysregulation of miRNAs is a common feature in human cancers including lung cancer. In this study, we describe the epigenetic regulation of miRNA-148a and its prognostic value in NSCLC. Due to hypermethylation of the miRNA‑148a encoding region, the expression levels of miRNA-148a were decreased in NSCLC tissues and cells. Decreased miRNA‑148a expression was associated with lymph node metastasis, advanced clinical stage and shortened disease-free survival and overall survival in NSCLC, and was an independent prognostic factor for overall survival in multivariate analysis. In vitro, overexpression of miRNA-148a significantly suppressed the migratory and invasive abilities of A549 and H1299 lung cancer cells. Enforced expression of miRNA-148a in lung cancer cell lines resulted in a significant reduction in the expression of DNMT1. This, in turn, led to a decrease in DNA methylation of the tumor-suppressor gene E-cadherin and induced an increase in the protein levels of E-cadherin. By understanding the function and molecular mechanism of miRNA-148a in NSCLC, miRNA-148a may have therapeutic potential to suppress lung cancer metastasis.