ABSTRACT
The methylation of histone lysine plays a pivotal role in epigenetic regulation of gene expression. Histone lysine methylation modifications have 5 sites within histone H3(K4, K9, K27, K36, K79)and 1 site within histone H4(K20). Methylation at various sites has been shown to lead to transcriptional activation or silencing. Histone lysine methyltransferases(HKMTs)and histone lysine demethylases(HKDMs)collectively regulate the methylation modification state of histone lysine. It was reported that the mis-regulation of HKDMs is associated with the occurring and resistance of numerous malignant tumors, so more and more attention are received to HKDMs. Therefore, it is great significant in the study and development of HKDMs inhibitors. The inhibitors could be served not only as a tool in the investigation of the biological function, but also could be used as novel anti-cancer agents in the anticancer therapy. In this review, we provide a short summary of the HKDMs inhibitors recently reported and their potential in the treatment of diseases.
ABSTRACT
<p><b>OBJECTIVE</b>The aim of this study was to investigate the effect of thalidomide on the growth of human hepatoma cell line SMMC-7721 cells in vitro, and to explore the curative possibility of hepatocellular carcinoma with thalidomide.</p><p><b>METHODS</b>SMMC-7721 cells were treated with Thalidomide at different concentrations. The cell growth and proliferation was assessed by MTT assay. DNA ladder, apoptosis rate and changes of cell nuclei were studied by agarose electrophresis, fluorescence microscopy and flow cytometry, respectively. The expression of caspase-3 was analyzed with flow cytometry. The VEGF content of SMMC-7721 cells in culture medium was tested by ELSIA.</p><p><b>RESULTS</b>When the concentration of Thalidomide solution was increased from 3.125 microg/ml to 200 microg/ml, the cell growth was inhibited by from 11.7% to 34.2%. Compared with the control group, the thalidomide solution at a concentration of 25, 50, 100 and 200 microg/ml solution significantly inhibited the proliferation of SMMC-7721 cells (P < 0.05). A ladder pattern of DNA fragments appeared after SMMC-7721 cells exposed to 200 microg/ml thalidomide for 24 h, especially for 48 h. Fluorescence microscopy revealed that the cell nuclei were condensed and fragmented after the cells were exposed to 200 microg/ml thalidomide for 48 h. In cells treated with 200 microg/ml thalidomide for 12, 24, 48 and 72 h, the apoptotic rate was 3.1% +/- 0.5%, 8.4% +/- 1.3%, 19.4% +/- 3.5% and 25.8% +/- 2.1%, respectively, significantly higher than that in the negative control group 1.6% +/- 0.6%. The cells treated with thalidomide at a concentration of 50, 100, 200 microg/ml for 48 h, the apoptotic rate was 8.7% +/- 1.2%, 16.8% +/- 2.5% and 25.4% +/- 4.5%, respectively, increasing in a dose-dependent manner, also significantly than that in the cells of control group 2.1% +/- 0.5%, (all were P < 0.05). The caspase-3 positivity of SMMC-7721 cells treated with thalidomide was increasing along with the increase of treatment time or drug concentration, but not in the control cells. The VEGF content in SMMC-7721 cells was lowering when thalidomide was used in an increasing concentration.</p><p><b>CONCLUSION</b>Under the conditions used in this study, thalidomide can inhibit the proliferation of SMMC-7721 cells in vitro. Induction of apoptosis and inhibition of angiogenesis may be possibly two mechanisms for its anticancer action.</p>