ABSTRACT
The naturally occurring compound α-pinene induces cell cycle arrest and antitumor activity. We examined effects of α-pinene on cell cycle regulation in hepatocellular carcinoma cells (HepG2) cells to establish a foundation for its development as a novel treatment for hepatocellular carcinoma (HCC). HepG2 cells treated with α-pinene exhibited dose-dependent growth inhibition as a result of G2/M-phase cell cycle arrest. Cell cycle arrest was associated with down-regulated cyclin-dependent kinase 1 (CDK1) and miR-221 levels and up-regulated levels of CDKN1B/p27, γ-H2AX, phosphorylated ATM, phosphorylated Chk2 and phosphorylated p53. Our observations are consistent with a model in which α-pinene inhibits miR221 expression, which leads to G2/M-phase arrest and activation of CDKN1B/p27-CDK1 and ATM-p53-Chk2 pathways that suppress human hepatoma tumor progression. Additionally, α-pinene was found to trigger oxidative stress and induce apoptosis of HepG2 cells. α-pinene, therefore, represents a potential chemotherapeutic compound for the treatment of HCC.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Hepatocellular/drug therapy , G2 Phase Cell Cycle Checkpoints/drug effects , Liver Neoplasms/drug therapy , M Phase Cell Cycle Checkpoints/drug effects , MicroRNAs/genetics , Monoterpenes/pharmacology , Bicyclic Monoterpenes , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/metabolism , Down-Regulation/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Hep G2 Cells , Humans , Liver Neoplasms/genetics , Liver Neoplasms/metabolismABSTRACT
To investigate the anti-hepatoma mechanism of α-pinene, HepG2 cell was treated with α-pinene and the change of cell cycle was examined by flow cytometry. The expression of miR-221, which was related the regulation of G2/M phase, was detected by quantitative Real-time PCR. Meanwhile, TargetScan and other online bioinformatics methods were used to analyze and predict the target genes of miR-221, then the expression level of related target genes were detected by quantitative Real-time PCR. The results showed that α-pinene inhibited the proliferation of HepG2 cells in dose-dependent manner. It was also proved that HepG2 cells were arrested at G2/M phase by α-pinene (P<0.05). The expression of miR-221 was down-regulated in α-pinene treated HepG2 cell. The bioinformatics analysis showed that CDKN1B/P27 and CDKN1C/P57 may be the protential targets of miR-221 and both of them were significantly up-regulatedï¼P<0.001,P<0.05ï¼by α-pinene treatment. According to these results, it was believed that α-pinene may inhibit the proliferation of hepatocellular carcinoma cells through arrest the cell at G2/M phase, which may be associated with the down-regulate of the miR-221 expression and up-regulate of the CDKN1B/P27 and CDKN1C/P57 expression.
