Inverse Association between miR-194 Expression and Tumor Invasion in Gastric Cancer

Abstract

MiR-194 has been shown to be specifically expressed in the human gastrointestinal tract and may play an antimetastatic role in primary liver cancer cells. However, the role of miR-194 in gastric cancer is still unclear. Total RNA was extracted from tissues of 119 patients with gastric cancer and three gastric cancer cell lines (SGC-7901, MGC-803, and BGC-823). Expression levels of miR-194 were determined by real-time polymerase chain reaction (PCR). Moreover, a MTT proliferation assay and transwell cell invasion assay were performed to study the effect of miR-194 on SGC-7901 cell proliferation and invasion. Finally, we used real-time PCR and western blot to verify which gene was the target of miR-194 in gastric cancer. Though there was no significant difference between cancerous and matching noncancerous tissues, we found patients with lower expression of miR-194 tended to have larger tumor size (P = 0.002) and more advanced pT stage (P = 0.028) in gastric cancer. Moreover, the expression of miR-194 was significantly lower in Borrmann IV type gastric cancer than in Borrmann I, II, and III types (P = 0.019). Furthermore, an in vitro invasion assay indicated that the penetrated cell intensity after miR-194 mimics transfection was significantly lower than the control. However, overexpression of miR-194 had little effect on the SGC-7901 cell cycle and proliferation. The results of real-time PCR and western blot highlighted that miR-194 interacted with N-cadherin and negatively regulated its expression at the translational level. These findings imply that miR-194 might play an important role in gastric cancer invasion and progression.