Antitumor effects of Cyclin D1 antisense cDNA on human hepatocellular carcinoma

Objective To investigate the effect of antisense cDNA of Cyclin D1 on the cell proliferation and tumorigenicity of human hepatocarcinoma HepG2 cell line.Methods Plasmids containing Cyclin D1 antisense cDNA were constructed and transfected into HepG2 cells.Their effects on cell proliferation and gene expression were examined by MTT method,RT-PCR method,immunofluorescent assay and flow cytometry.To assess the effect of antisense Cyclin D1 on tumorigenicity,the tansfected cells were injected subcutaneously in nude mice.Results Cyclin D1 antisense cDNA could significantly inhibit the growth of HepG2 cells.The inhibitory effecr peaked at 48 h after transfection by MTT method.RT-PCR analysis revealed that Cyclin D1 antisense cDNA could down-regulate the expression of Cyclin D1 mRNA.The expression level of Cyclin D1 protein was also decreased by immunofluorescent assay.Cell-cycle analysis by flow cytometry indicated that the transfected HepG2 cells were arrested at the G_1 phase of the cell cycle.Antisense expressing cells displayed complete loss of tumorigenicity in nude mice.Conclusion Cyclin D1 antisense cDNA could specifically inhibit the expression of Cyclin D1 mRNA and protein and regulate cell cycle.Furthermore,the cell proliferation and tumorigenicity of HepG2 cells were significantly inhibited.This therapeutic potential of Cyclin D1 antisense cDNA may lead to new cell-cycle-based antitumor strategies for human hepatocarcinoma.