MiR-218 Inhibits Invasion and Metastasis of Gastric Cancer by Targeting the Robo1 Receptor

Abstract

MicroRNAs play key roles in tumor metastasis. Here, we describe the regulation and function of miR-218 in gastric cancer (GC) metastasis. miR-218 expression is decreased along with the expression of one of its host genes, Slit3 in metastatic GC. However, Robo1, one of several Slit receptors, is negatively regulated by miR-218, thus establishing a negative feedback loop. Decreased miR-218 levels eliminate Robo1 repression, which activates the Slit-Robo1 pathway through the interaction between Robo1 and Slit2, thus triggering tumor metastasis. The restoration of miR-218 suppresses Robo1 expression and inhibits tumor cell invasion and metastasis in vitro and in vivo. Taken together, our results describe a Slit-miR-218-Robo1 regulatory circuit whose disruption may contribute to GC metastasis. Targeting miR-218 may provide a strategy for blocking tumor metastasis.

Author Summary

MicroRNAs have been identified as playing important roles in tumor metastasis, but their impact on GC metastasis has been poorly explored. We have discovered miR-218, which functions as a suppressor of tumor metastasis and is correlated with clinical stage, lymph node metastasis, and prognosis in patients with GC. Our results show that miR-218 is part of a regulatory circuit involving the Slit-Robo1 pathway. In metastatic tumor cells, miR-218 was suppressed along with Slit3, one of its host genes. Meanwhile, Robo1, one of several Slit receptors, is upregulated in response to the decrease in miR-218, which in turn induced a reactive upregulation of the Slit-Robo1 pathway through an interaction with Slit2, thus facilitating tumor cell migration and invasion. Such findings not only provide new insights into the metastatic mechanisms in GC but also provide evidence for a novel miRNA–mediated regulatory mode of receptor signaling.