lncRNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 Promotes Proliferation and Invasion of Non-Small Cell Lung Cancer Cells via Down-Regulating miR-202 Expression

OBJECTIVE: Accumulating evidences indicate that long non-coding RNAs (lncRNAs) play key roles in cancer. This study aims to clarify role of the metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in non-small cell lung cancer (NSCLC) and uncover the underlying mechanisms. MATERIALS AND METHODS: In this experimental study, MALAT1 and miR-202 expression in tissues and cell lines were detected using quantitative real time polymerase chain reaction (qRT-PCR) assay. Cell transfection was conducted using Lipofectamine 3000. Cell proliferation was determined with CCK-8 assay. MMP2 and MMP9 expressions were measured with Western blot. Cell invasive ability was evaluated by Transwell assay. Starbase 2.0 tool was used to predict targets of MALAT1. Dual luciferase reporter assay, RNA-binding protein immunoprecipitation assay and RNA pull-down assay were conducted to confirm the potential direct interaction between MALAT1 and miR-202. RESULTS: MALAT1 was overexpressed in NSCLC samples and cell lines. High expression of MALAT1 was related to large tumor size (>3 cm), poor histological grade, advanced cancer and tumor metastasis in NSCLC. In vitro assays exhibited that knockdown of MALAT1 remarkably decreased A549 cell growth and invasion capacity, while overexpression of MALAT1 significantly enhanced NCI-H292 cell proliferation and invasion ability. Next, we verified that MALAT1 could act as a competing endogenous RNA (ceRNA) by sponging miR-202 in NSCLC and there is a negative correlation between MALAT1 and miR-202. Besides, overexpression of miR-202 inhibited cell proliferation and invasive ability in MALAT1-overexpressed cells. CONCLUSION: This study demonstrated that lncRNA-MALAT1 gets involved in NSCLC progression by targeting miR- 202, indicating that MALAT1 may serve as a novel therapeutic target for NSCLC treatment.