Induction of Apoptosis by Genistein in Human Melanoma Cells / 대한해부학회지

Genistein is a naturally occurring isoflavone that has been identified predominantly in soybean. It has been found that genistein can inhibit the growth of various cancer cell lines. Melanoma continues to increase in incidence in many parts of the world and remains among the top six cancers as a cause of death and morbidity. Understanding and overcoming resistance mechanism(s) of melanoma to apoptosis would therefore facilitate identification of new therapeutic targets and development of new treatments. This study was undertaken to investigate whether genistein induced apoptosis on human melanoma cells (G361). Genistein had a significant dose- and time-dependent inhibitory effect on the viability of G361 cells. The death of cells was further demonstrated to be due to apoptosis characterized by chromatin condensation and apoptotic bodies by hoechst staining, and DNA electrophoresis. p53 levels were not altered by genistein treatment. Genistein treatment induced caspase-3 cleavage and activation. Poly (ADP-ribose)-polymerase (PARP) and DNA fragmentation factor 45 (DFF45), which are caspase-3 substrates, were cleaved during genistein-induced apoptosis. It was found that the caspase-6 substrate lamin A was cleaved, whose cleavage has been reported to be necessary for complete condensation of DNA during apoptosis. The expression level and phosphorylation of focal adhesion kinase (FAK) were reduced by genistein treatment. These results suggest that genistein may constitute a potential antitumor compound against melanoma occurring at oral mucosa and skin.

Apoptotic Effect of Co-Treatment with a Natural Product, Chios Gum Mastic, and a Proteasome Inhibitor, Lactacystin, on Human Osteosarcoma Cells / 대한해부학회지

Chios gum mastic (CGM) is a resinous exudate obtained from the stem and the main leaves of Pistacia lenticulus tree native to Mediterranean areas. Recently, it was reported that CGM induced apoptosis in a few cancer cells in vitro. Since recent studies indicated the synergistic interactions between the apoptotic stimulus and a proteasome inhibitor, the ubiquintin-proteasome pathway has become an attractive target in cancer therapy. And to date, there has been no report of the synergistic apoptotic effect between CGM and a proteasome inhibitor to become an attractive target in cancer therapy. Therefore, this study was undertaken to investigate the synergistic apoptotic effect of co-treatment with a natural product, CGM, and a proteasome inhibitor, lactacystin, on human osteosarcoma (HOS) cells. To investigate whether the co-treatment of CGM and lactacystin compared with each single treatment efficiently induced apoptosis on HOS cells, MTT assay, DNA electrophoresis, Hoechst staining, DNA hypoploidy assay, Westen blot analysis, immunofluorescent staining, proteasome activity and mitochondrial membrane potential (MMP) change were performed. In this study, HOS cells co-treated with CGM and lactacystin showed several lines of apoptotic manifestation such as nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, the decrease of DNA content, the release of cytochrome c into cytosol, the translocation of AIF and DFF40 (CAD) onto nuclei, and activation of caspase-7, caspase-3, PARP and DFF45 (ICAD) whereas each single treated HOS cells hardly showed. We presented data indicating that the co-treatment of CGM and lactacystin induced potentially apoptosis whereas each single treatment did slightly. Moreover, the co-treatment of CGM and lactacystin potentiated the inhibition of proteasome activity. Therefore, our data provide the possibility that combination therapy of CGM and lactacystin could be considered as a novel therapeutic strategy for human osteosarcoma.

Synthetic Chenodeoxycholic Acid Derivative HS-1200-induced Apoptosis of Human Melanoma Cells / 체질인류학회지

Bile acids and their synthetic derivatives induced apoptosis in various kinds of cancer cells and anticancer effects. It has been reported that the synthetic chenodeoxycholic acid (CDCA) derivatives showed apoptosis-inducing activity on various cancer cells in vitro. It wasn't discovered those materials have apoptosis-inducing effects on G361 human melanoma cells. The present study was done to examine the synthetic bile acid derivatives, HS-1199 and HS-1200, induced apoptosis on G361 cells and such these apoptosis events. The viability of G361 cells was assessed by the MTT assay. Induction of apoptosis was confirmed by DNA electrophoresis and Hoechst staining. Westen blot analysis and immunofluorescent staining were performed to study the alterations in expression level and translocation of apoptosis-related proteins. Proteasome activity and mitochondrial membrane potential (MMP) change were also assayed. Tested G361 cells showed several lines of apoptotic manifestation such as activation of caspase-3, DFF and PARP, DNA degradation (HS-1200 only), nuclear condensation, inhibition of proteasome activity, reduction of mitochondrial membrane potential, and the release of cytochrome c and AIF to cytosol. Between two synthetic derivatives, HS-1200 showed stronger apoptosis-inducing effect than HS-1199 did. Taken collectively, we here demonstrated for the first time that synthetic CDCA dedrivatives induce apoptosis of human melanoma cells through the proteasome, mitochondria and caspase pathway. Therefore our data provide the possibility that HS-1200 could be considered as a novel therapeutic strategy for human melanoma cells from its powerful apoptosis-inducing activity.