Overexpression of long noncoding RNA GAS5 suppresses tumorigenesis and development of gastric cancer by sponging miR-106a-5p through the Akt/mTOR pathway

Long noncoding RNAs (lncRNAs) have emerged as important regulators of human cancers. LncRNA GAS5 (GAS5) is identified as a tumor suppressor involved in several cancers. However, the roles of GAS5 and the mechanisms responsible for its functions in gastric cancer (GC) have not been well documented. Herein, the decreased GAS5 and increased miRNA-106a-5p levels were observed in GC and cell lines. GAS5 level was significantly inversely correlated with miRNA-106a-5p level in GC tissues. Moreover, dual-luciferase reporter and qRT-PCR assays showed that GAS5 bound to miRNA-106a-5p and negatively regulated its expression in GC cells. Functional experiments showed that GAS5 overexpression suppressed GC cell proliferation, migration and invasion capabilities, and promoted apoptosis, while miRNA-106a-5p overexpression inverted the functional effects induced by GAS5 overexpression. In vivo, GAS5 overexpression inhibited tumor growth by negatively regulating miRNA-106a-5p expression. Mechanistic investigations revealed that GAS5 overexpression inactivated the Akt/mTOR pathway by suppressing miRNA-106a-5p expression in vitro and in vivo. Taken together, our findings conclude the GAS5 overexpression suppresses tumorigenesis and development of gastric cancer by sponging miR-106a-5p through the Akt/mTOR pathway.