Long Non-coding RNA CASC15 Inhibits Cell Migration And Invasion In Hepatocellular Carcinama

Research objectives:Hepatocellular carcinoma(HCC)is the fourth most common cause of cancer-related death worldwide.In China,the incidence of HCC ranks fourth in tumor incidence,its mortality rate ranks third,which causes approximately 383,000 death per year with an overall survival rate of only 36.9%.The prevention of HCC recurrence and intrahepatic metastasis of postoperative patients and the improvement of the survival of inoperable HCC patients to achieve "survival with tumor" have become research focuses worldwide.It is of great significance to explore the molecular mechanism of HCC occurrence and development and to find new strategies and methods for HCC treatment.Long-noncoding RNA(lnc RNA)cancer susceptibility candidate 15(CASC15)is located on chromosome 6p22.3.CASC15 has been shown to be related to the occurrence and metastasis in several cancers.However,the roles of CASC15 in different cancers are still under debate.For example,downregulation of CASC15 is associated with poor prognosis in neuroblastoma patients.Overexpression of CASC15 inhibits proliferation in acute leukemia cells.However,high expression level of CASC15 is the independent risk factor of metastasis in melanoma patients.By now,few study has reported role of CASC15 in HCC.Whether CASC15 plays an important role in the progression of HCC and is related to the recurrence,metastasis and prognosis of HCC remains to be explored.Its in-depth research provide new ideas for HCC treatment strategies.Methods:Gene expression profiles microarray assay was used to detect and compare the lnc RNA expressions in three HCC cell lines with increasing metastatic potentials,and the differentially expressed lnc RNA CASC15 which is related to HCC metastasis was screened out.Real-time quantitative PCR was used to verify the results of microarray data.Next,Real-time quantitative PCR and RNA in situ hybridization were used to detect the expression levels of CASC15 in tumor and para-tumor tissue samples of HCC patients.Univariate and multivariate COX regression models were used to analyze the association between CASC15 expression and clinical pathological data such as patient prognosis;Kaplan-Meier survival curve analysis was used to explore the relationship between CASC15 and prognosis of HCC patients.Next,we constructed stable HCC cell lines with CASC15 overexpression or downregulation.The effects of CASC15 on cell migration and metastasis were observed using wound healing,migrated and invaded in vitro.In situ intrahepatic metastatic mice model was also used to observed the effect of CASC15 in vivo.Results and conclusions:In this study we found that the expression levels of lnc RNA CASC15 decreased as metastasis capacity of the HCC cell increased.Real-time quantitative PCR test results showed that the expression level of CASC15 is highest in Huh7 cells with low metastatic capacity,second in MHCC97 L cells,and lowest in HCCLM3 cells.Results of real-time quantitative PCR method for RNA samples from clinical tissues showed that the expressions level of CASC15 in HCC tissues were significantly lower than those in adjacent para-tumor tissues.The results of in situ hybridization of RNA in clinical tissue sections also showed that the expression level of CASC15 in HCC tissues were lower than those in adjacent tissues.Univariate and Multivariate Cox models analysis showed that downregulation of CASC15 expression is an independent risk factor for poor prognosis in HCC patients(P < 0.05);The survival time of patients with high expression of CASC15 in HCC tissues was significantly longer than those patients with low expression levels of CASC15(P < 0.05).In vitro experimental results showed that overexpression of CASC15 inhibited the migration and invasion of HCC cells compared to the corresponding control cells,whereas downregulation of CASC15 promoted the migration and invasion of HCC cells compared to the corresponding control cells.In vivo experiments in mice had also suggested that CASC15 upregulation inhibited intrahepatic metastasis of HCC cells.In conclusion,CASC15 is related to HCC metastasis,and overexpression of CASC15 inhibits HCC progression.The results of this study provide new ideas and laboratory research basis for anti metastasis therapy in HCC.