Gastric cancer (GC) is one of the most common malignancies and ranks the second leading cause of cancer death worldwide. Some studies had reported the tumor-promoting effects of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) as a competing endogenous RNA (ceRNA) by sponging to microRNAs. However, the molecular mechanism of ceRNA regulatory pathway involving MALAT1 in GC remains unclear.

MALAT1 and miR −202 expression was detected by quantitative real time PCR (qRT-PCR) in 60 gastric cancer tissues and adjacent normal tissues, CCK8 cell proliferation assays, cell cycle analysis and cell apoptosis assays were performed to detect the GC cell proliferation and apoptosis. The mRNA and protein levels of Gli2 were analyzed by quantitative real-time PCR and Western blotting assays. Furthermore, using online software, luciferase reporter assays, RNA immunoprecipitation (RIP) and RNA pulldown assays demonstrated miR-202 was a target of MALAT1.

We found that MALAT1 was upregulated in GC tissues and higher MALAT1 expression was correlated with larger tumor size, lymph node metastasis, and TNM stage. Moreover, we revealed that MALAT1 was a direct target of miR-202 and knockdown of MALAT1 significantly decreased the expression of Gli2 through negatively regulating miR-202. In addition, knockdown of Malat1 inhibited GC cells proliferation, S-phase cell number, and induced cell apoptosis via negatively regulating miR-202 in vitro.

Our results elucidated MALAT1/miR-202/Gli2 regulatory pathway, which maybe contribute to a novel therapeutic strategy for GC patients.