miR-106b Promotes Metastasis of Early Gastric Cancer by Targeting ALEX1 in Vitro and in Vivo

Aberrant expression of miR-106b is a specific symptom of many solid carcinomas. Overexpression of miR-106b has been observed in gastric cancer. The effect of miR-106b on gastric cancer has been investigated in different cell culture models. However, the effect of miR-106b on metastasis of early gastric cancer (EGC) remains unknown. In the study, qRT-PCR, FISH, western blot, luciferase reporter assay, migration and invasion assays, flow cytometry and TUNEL staining were used to investigate the effect of miR-106b on metastasis of EGC. To explore the function of miR-106b in EGC, we investigated the downstream signaling of miR-106b and found that ALEX1 was a direct target of miR-106 in gastric cancer cells. Up-regulation of ALEX1 effectively rescued the cell apoptosis induced by miR-106b inhibitor and promoted the expression levels of phosphorylation of JAK1 and STAT3. Moreover, overexpression of JAK1 reduced the cell apoptosis induced by miR-106b inhibitor and decreased the expression levels of the apoptotic proteins in gastric cancer cells. Furthermore, down-regulation of miR-106b promoted apoptosis of gastric cancer cells via inhibiting JAK1/STAT3 signaling pathway in vitro and in vivo. In addition, GLPG0643, a JAK1 inhibitor, enhanced the inhibitory effect of miR-106b inhibitor on gastric cancer growth in vivo. These findings provided a potential therapeutic manner for the treatment of metastasis of EGC in clinic.