miR-509-3-5P inhibits the invasion and lymphatic metastasis by targeting PODXL and serves as a novel prognostic indicator for gastric cancer

BACKGROUND Our study aimed to investigate the clinicopathological feature and prognostic role of miR-509-3-5P in gastric cancer, to determine the invasive and metastatic role of miR-509-3-5P in vitro and in vivo and to explore the molecular mechanism between miR-509-3-5P and PODXL. RESULTS Strikingly lower miR-509-3-5P expression was detected in gastric cancer tissues with advanced tumor stage, poor differentiation and advanced pT stage, and was regarded as an independent prognostic role for poor prognosis. MiR-509-3-5P expression was markedly down-regulated in gastric cancer cell lines and tissues comparing with normal gastric cell and adjacent normal tissues, respectively. Decreased expression of miR-509-3-5P promoted the colony, migration and invasion abilities of gastric cancer cells in vitro as well as tumorigenesis and lymph node metastasis in vivo. Based on the luciferase assay and tissue microarray, PODXL was regarded as a target gene of miR-509-3-5P. MATERIALS AND METHODS The expression of miR-509-3-5P in gastric cancer patients and its clinicopathological relationships as well as prognostic role was studied employing tissue microarray; qRT-PCR was applied to explore miR-509-3-5P expression in gastric cancer cell lines and samples. Moreover, public database was used to analyze the expression of miR-509-3-5P and PODXL. Functional and molecular mechanism experiments were performed in vitro and in vivo. CONCLUSIONS Overexpression of miR-509-3-5P inhibits the invasion and metastasis of gastric cancer in vitro and in vivo, functioning as a tumor suppressor, by targeting PODXL. More importantly, miR-509-3-5P was downregulated in gastric cancer tissues and may serve as a novel prognostic indicator for gastric cancer.