Long noncoding RNA MALAT1 regulates autophagy associated chemoresistance via miR-23b-3p sequestration in gastric cancer

Background: Chemoresistance has long been recognized as a major obstacle in cancer therapy. Clarifying the underlying mechanism of chemoresistance would result in novel strategies to improve patient's response to chemotherapeutics. Methods: lncRNA expression levels in gastric cancer (GC) cells was detected by quantitative real-time PCR (qPCR). MALAT1 shRNAs and overexpression vector were transfected into GC cells to down-regulate or up-regulate MALAT1 expression. In vitro and in vivo assays were performed to investigate the functional role of MALAT1 in autophagy associated chemoresistance. Results: We showed that chemoresistant GC cells had higher levels of MALAT1 and increased autophagy compared with parental cells. Silencing of MALAT1 inhibited chemo-induced autophagy, whereas MALAT1 promoted autophagy in gastric cancer cells. Knockdown of MALAT1 sensitized GC cells to chemotherapeutics. MALAT1 acts as a competing endogenous RNA for miR-23b-3p and attenuates the inhibitory effect of miR-23b-3p on ATG12, leading to chemo-induced autophagy and chemoresistance in GC cells. Conclusions: Taken together, our study revealed a novel mechanism of lncRNA-regulated autophagy-related chemoresistance in GC, casting new lights on the understanding of chemoresistance.