Expression Of MIR155HG In Clear Cell Renal Cell Carcinoma And The Effect On Tumor Biological Behavior

OBJECTIVE:In recent years,more and more studies have pointed out that functional RNA molecules may play an important role in renal cell carcinoma-related pathophysiology,including cell proliferation,cell cycle regulation,apoptosis,and local invasion.This may help to reveal the molecular mechanism of the development of renal cancer and is expected to find reliable molecular markers and new therapeutic targets.Long noncoding RNAs(lncRNAs)are a class of linear RNA molecules with a length of more than 200 nt.Studies have confirmed that they may play an important role in the development of tumors.In the early study,we found that MIR155HG(MIR155 host gene)was significantly different in renal clear cell carcinoma tissue and corresponding paraneoplastic tissue,but the function and mechanism of MIR155HG in renal cell carcinoma have not been elucidated.Therefore,the purpose of this study is to investigate the expression of MIR155HG in clear cell renal cell carcinoma and its effects on the biological behavior such as tumor cell proliferation,invasion and metastasis.METHODS:We first used qRT-PCR technique to detect the expression level of MIR155HG in 88 pairs of renal clear cell carcinoma tissue and its corresponding adjacent normal renal tissue.Afterwards,we used the renal cancer cell lines 786-0 and 769-P as experimental subjects to explore the effect of MIR155HG on kidney cancer through a series of in vitro experiments(MTT assay,plate colony formation assay,cell cycle assay,scratch test,transwell assay).RESULTS:MIR155HG was 1500 bp in length and localized in the nucleus.Its expression level in renal clear cell carcinoma was 3.5 times higher than that of its normal counterpart(P<0.001).At the same time,the expression level of MIR155HG was significantly up-regulated in metastatic ccRCC(P<0.001),its expression is significantly related with tumor maximal diameter(P<0.001),Fuhrman grading(P=0.019),and TNM staging(P=0.003).Survival analysis showed that ccRCC patients with with up-regulated MIR155HG expression had poor disease-free survival(DFS,P = 0.0074)and overall survival(OS,P =0.0071).Then this study confirmed that knockdown of MIR155HG can inhibit the proliferation of tumor cells to play a role in tumor suppressor.Further study showed that MIR155HG can affect the migration and invasion of renal cancer cells.Conclusion:The results of this study suggest that MIR155HG may be used as an oncogene to participate in the biological processes of renal cell carcinoma such as the oncogenesis,development and metastasis.Inhibiting the expression of MIR155HG can significantly reduce the proliferation,invasion and migration of renal cell carcinoma.The survival analysis showed that the expression level of MIR155HG was significantly correlated with the survival of patients,indicating that MIR155HG may have the potential as a biomarker for prognosis of renal cancer.