MiR-199a-3p Regulates The Proliferation And Apoptosis Of Gastric Cancer Cells By Inhibiting The Expression Of ZHX1

?AIMS&Background? Gastric cancer is one of the most common cancers in China and the majority of patients with gastric cancer are still diagnosed at an advanced stage. Despite considerable improvements in surgical techniques, the clinical outcome for patients with advanced gastric cancer after curative gastrectomy is still unsatisfactory, mainly due to the poor understanding of the molecular mechanism of gastric cancer development. Therefore, an improved understanding of the molecular pathways involved in the carcinogenesis of gastric cancer will be definitely helpful in improving therapy and prognosis of this disease.Accumulating evidence has indicated that micro RNAs(mi RNAs) act as critical epigenetic regulators in tumor carcinogenesis. Here, we report that mi R-199a-3p was significantly upregulated in gastric cancer(GC) cell lines and tissues. Functional studies demonstrated that mi R-199a-3p dramatically increased cell proliferation and suppressed cell apoptosis both in vitro and in vivo. Furthermore,the transcriptional regulator zinc fingers and homeoboxes 1(ZHX1) was identified as one of the direct downstream targets of mi R-199a-3p, mi R-199a-3p bound to the ZHX1 3'untranslated region(3'UTR) to regulate ZHX1 protein expression.?Methods? The expression of mi R-199a-3p in gastric cancer cell lines, GES-1, 52 paired gastric cancer tissues and normal gastric mucosa were examined by q RT-PCR. The mi R-199a-3p mimics was transfected into gastric cancer cell line SGC-7901 to up-regulate mi R-199a-3p, retroviral vector was used as control. mi R-199a-3p inhibitors were transfected into NCI-N87 to down-regulate mi R-199a-3p. The biological effects, including proliferation, apoptosis and subcutaneous tumorigenesis, were investigated in SGC-7901 and NCI-N87 cells. Downstream target genes of mi R-199a-3p were predicted by bioimformatics and further validated by luciferase reportor system, q RT-PCR and immunoblot.?RESULTS?The expression of mi R-199a-3p was further evaluated by q RT-PCR in tumor samples and their matched nontumor samples from 52 GC patients. The expression of mi R-199a-3p is up-regulated in GC and correlates with tumor invasion and TNM stage. Ectopic expression of mi R-199a-3p induces GC cell proliferation and inhibits apoptosis. mi R-199a-3p can promote the tumorigenicity of GC cells in vitro.Bioinformatics analysis discovered putative binding sequences of mi R-199a-3p located at 3'UTR of transcription factor ZHX1. The regulation was validated by using dual-luciferase reporter assay. QRT-PCR and Western blotting analysis verified that mi R-199a-3p down-regulated ZHX1 expression through post-transcriptional way. Overexpression of ZHX1 rescues effect of mi R-199a-3p in GC cells. Growth promotion and apoptosis inhibition by mi R-199a-3p are related to ZHX1 expression.?CONCLUSIONS?The expression of mi R-199a-3p was significantly elevated in gastric cancer tissues compared with matched non-tumor tissues. The level of mi R-199a-3p was negatively correlated with tumor invasion. Overexpression of mi R-199a-3p in gastric cancer cells promoted their malignant behavior and vise versa. Signaling pathway analysis discovered ZHX1 as one of its major targets which mediated its effects on gastric cancer cells.