The Mechanism Of Mir-9Regulates Epithelial-to-mesenchymal Transition And RAB34in Gastric Cancer

Background and Objectives The potential of invasion and metastasis in tumors depends oncancer cells and interaction of interior environment,such as, the promotion of growth and survivalof tumor cells, the formation of blood vessels, invasion and metastasis, etc.EMT is one of the mainfactors of invasion and metastasis in tumor cells. miRNAs is a new type of the small molecularRNAs, which regulate the expression level of genes after transcription.They have both highexpression and low expression in tumors. There is close relation between miRNAs and theoccurrence of EMT in cancer. The present studies explore the mechanism that mir-9regulatesepithelial-to-mesenchymal transition and the signaling pathway of RAB34in gastric cancer.Methods The expression of E-cadherin、RAB34proteins in45cases of gastric cancertissues were detected by immunohistochemical staining, The expression of microRNA-9wereexamined by RT-PCR. In addition, gastric cancer cell line SGC-7901were transfected withdifferent concentrations of has-mir-9and has-mir-9inhibitors. The expression of microRNA-9were examined by RT-PCR.The proliferation of transfected cells were detected by CCK-8andexpression of E-cadherin、RAB34proteins were detected by Western-blot.Results The expression level of E-cadherin、RAB34and mir-9were significantly lower in thetumor tissues than those in the adjacent tissues（p<0.05）. Among45cases of gastric cancer, thepositive rate of E-cadherin was35.6%（16/45）, and RAB34was44.4%（20/45）. The expressionof E-cadherin and RAB34proteins were closely related to the depth of tumor invasion,celldifferentiation, lymph node metastasis and TNM staging（p<0.05）, while no significant relationwith the state of gender, age, tumor location and tumor size.The expression of mir-9was notrelated to all above factors（p>0.05）. Gastric cancer cell line SGC-7901were transfected with50pmol and100pmol has-mir-9recpectively. In addition,0.5umol,0.75umol and1.0umolhas-mir-9inhibitors were transfected into SGC-7901. Compared with the control group，Theproliferation of gastric cancer cells which were transfected with50pmol,100pmol wasdecreased by2.00%and3.09%respectively.The expression of E-cadherin protein was increasedby37.8%and51.4%respectively.The expression of RAB34protein was increased by27.5%and47.5%respectively.The proliferation of gastric cancer cells which were transfected with0.5umol,0.75umol,1.0umol has-mir-9inhibitors was increased by0.13%,0.64%,3.99%respectively.The expression of E-cadherin protein was decreased by2.7%,5.4%,10.8%respectively.The expression of RAB34protein was decrease by5.0%,15.0%,25.0%respectively. These results showed that negative correlation between the concentration of mir-9and theproliferation of cells; and the expression of between E-cadherin protein and RAB34proteinwere positively correlated.Conclusion mir-9suppresses epithelial-to-mesenchymal transition and proliferation of gastriccancer cells, mir-9inhibitors promote epithelial-to-mesenchymal transition and proliferation ofgastric cancer cells, RAB34signaling pathway is the possible underlying mechanism.