Xylocydine, a novel Cdk inhibitor, is an effective inducer of apoptosis in hepatocellular carcinoma cells in vitro and in vivo.

Hepatocellular carcinoma (HCC) frequently includes abnormalities in cell cycle regulators, including up-regulated cyclin-dependent kinase (Cdks) activities due to loss or low expression of Cdk inhibitors. In this study, we show that xylocydine, a cyclin-dependent kinase (Cdk) specific inhibitor, is a good anti-cancer drug candidate for HCC treatment. Xylocydine (50muM) selectively down-regulates the activity of Cdk1 and Cdk2, accompanied by significant cell growth inhibition in HCC cells. Xylocydine also strongly inhibits the activity of Cdk7 and Cdk9, in vitro as well as in cell cultures, that is temporally associated with apoptotic cell death in xylocydine-induced HCC cells. This is associated with inhibition of phosphorylation of RNA polymerase II at serine residues 5 and 2, which are targets of Cdk7 and Cdk9, respectively. The effects on apoptosis are concomitant with changes in the levels of anti-apoptotic proteins, Bcl-2, XIAP, and survivin, which are markedly down-regulated, and pro-apoptotic molecules, p53 and Bax, which are elevated in HCC cells after treatment with xylocydine. The up-regulated level of p53 was associated with increased stability of the protein, as levels of Ser15 and Ser392 phsophorylated p53 are similarly elevated in the inhibitor treated cells. We demonstrated that xylocydine can effectively suppress the growth of HCC xenografts in Balb/C-nude mice by preferentially inducing apoptosis in the xenografts, whereas the drug did not cause any apparent toxic effect on other tissues. Taken together, these data suggest that the novel Cdk inhibitor xylocydine is a good candidate for an anti-cancer drug for HCC therapy.

Cho SJ ，Lee SS ，Kim YJ ，Park BD ，Choi JS ，Liu L ，Ham YM ，Moon Kim B ，Lee SK ... -  《-》

Ibulocydine is a novel prodrug Cdk inhibitor that effectively induces apoptosis in hepatocellular carcinoma cells.

Cho SJ ，Kim YJ ，Surh YJ ，Kim BM ，Lee SK ... -  《-》

Inhibition of cyclin-dependent kinase 7 suppresses human hepatocellular carcinoma by inducing apoptosis.

Increasing evidence has shown that THZ1, a covalent cyclin-dependent kinase 7 (CDK7) inhibitor, exhibits therapeutic effects in various tumors. However, the possible effect of THZ1 on hepatocellular carcinoma (HCC) remains unknown. Our study was to investigate the roles of THZ1 in HCC cells and in subcutaneous HCC model and illustrate the molecular mechanisms. The phosphorylation levels of Ser2, Ser5, and Ser7 within RNA polymerase II (RNAPII) C-terminal domain (CTD) and the expression levels of Ki67, Mcl-1, survivin, XIAP, and p53 in HCC cells under different conditions were examined by Western blot analysis. Cell growth and apoptosis were assessed via 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Tumor volume was assessed in HCC mice with THZ1 or vehicle treatment and immunohistochemical (IHC) analysis was conducted on excised tumors. THZ1 significantly inhibited the phosphorylation of Ser2, Ser5, and Ser7 within RNAPII-CTD in the dose-dependent and irreversible manner. MTT assay and flow cytometry analysis showed that THZ1 inhibited HCC cell proliferation and induced apoptosis, respectively. Western blot analysis indicated THZ1 significantly upregulated p53 expression and downregulated the expressions of Mcl-1, survivin, XIAP, and Ki67. THZ1 suppressed tumor growth in Hep3B xenografted mice in a time-dependent manner. IHC analysis indicated that tumors in THZ1 group had less Ki67+ cells and more cleaved caspase-3+ cells than those in vehicle group. THZ1 exhibited anti-HCC effects through irreversibly inhibiting CDK7 activity, decreasing RNAPII-CTD phosphorylation, inducing p53 expression and inhibiting antiapoptotic gene expressions, which subsequently induced apoptosis and inhibited proliferation of HCC cells.

Zhong L ，Yang S ，Jia Y ，Lei K ... -  《-》

Longikaurin A, a natural ent-kaurane, induces G2/M phase arrest via downregulation of Skp2 and apoptosis induction through ROS/JNK/c-Jun pathway in hepatocellular carcinoma cells.

Liao YJ ，Bai HY ，Li ZH ，Zou J ，Chen JW ，Zheng F ，Zhang JX ，Mai SJ ，Zeng MS ，Sun HD ，Pu JX ，Xie D ... -  《Cell Death & Disease》

NCPMF-60 induces G2/M cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells.

Dai QS ，Liu W ，Wang XB ，Lu N ，Gong DD ，Kong LY ，Guo QL ... -  《-》