LncRNA CASC2靶向调控miR-155-5p及其对HCC细胞恶性表型的影响OACSTPCD

Objective:Long non-coding RNA(lncRNA)cancer susceptibility candidate gene 2(CASC2)functions as a tumor suppressor gene in various malignancies,including ovarian cancer and hepatocellular carcinoma(HCC).However,its mechanism in HCC remains unclear.This study aims to analyze the expression and clinical significance of CASC2 in HCC tissues,and to explore the effect of CASC2 on the malignant phenotype of Huh-7 cells and its possible mechanism. Methods:Real-time RT-PCR was used to detect the expression levels of CASC2 and miR-155-5p in HCC tissues and cell lines.The relationship between CASC2 expression levels and clinicopathological features and prognosis of HCC patients was analyzed.The targeting relationship between CASC2 and miR-155-5p was verified using a dual-luciferase reporter assay.pcDNA3.1-CASC2 recombinant plasmid,pcDNA3.1 empty plasmid,miR-155-5p mimic,and miR-155-5p mimic negative control(miR-NC)were transfected into Huh-7 cells separately or together.According to the different infections,cells were divided into a blank control group,a pcDNA3.1 group,a pcDNA3.1-CASC2 group,a pcDNA3.1-CASC2+miR-155-5p group,and a pcDNA3.1-CASC2+miR-NC group.Methylthiazolyl tetrazolium(MTT),Annexin V/propidium iodide(PI)double staining,and Transwell assays were used to detect the effects of CASC2 targeting miR-155-5p on Huh-7 cell proliferation,apoptosis,migration,and invasion. Results:CASC2 expression was down-regulated in HCC tissues and cell lines,while miR-155-5p expression was up-regulated,showing a significant negative correlation(r=-0.388,P<0.05).CASC2 expression in HCC patients was closely related to alpha-fetoprotein levels,tumor size,TNM stage,differentiation degree,intrahepatic metastasis,and poor prognosis(all P<0.05).CASC2 negatively regulated the expression of miR-155-5p.The proliferation activity of the pcDNA3.1-CASC2 group was significantly lower than that of the blank control group and pcDNA3.1 group(both P<0.05).Compared with the pcDNA3.1-CASC2 group,the proliferation activity of the pcDNA3.1-CASC2+miR-155-5p group was significantly increased(P<0.05).The apoptosis rate of the pcDNA3.1-CASC2 group was significantly higher than that of the blank control group and the pcDNA3.1 group(both P<0.05).Compared with the pcDNA3.1-CASC2 group,the apoptosis rate of the pcDNA3.1-CASC2+miR-155-5p group was significantly reduced(P<0.05).The number of migrating and invading cells in the pcDNA3.1-CASC2 group was significantly lower than that in the blank control group and the pcDNA3.1 group(both P<0.05).Compared with the pcDNA3.1-CASC2 group,the number of migrating and invading cells in the pcDNA3.1-CASC2+miR-155-5p group was significantly increased(P<0.05). Conclusions:CASC2 is lowly expressed in HCC tissues and cells and is closely related to HCC prognosis.Overexpression of CASC2 can inhibit the proliferation,migration,and invasion of liver cancer cells and promote cell apoptosis by targeting and regulating miR-155-5p.