Department of Microbiology, Center of Excellence for Innovation in Chemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
World J Gastroenterol. 2010 May 14;16(18):2235-43. doi: 10.3748/wjg.v16.i18.2235.
To investigate the growth inhibitory mechanism of four caged xanthones from Garcinia hanburyi in cholangiocarcinoma (CCA) KKU-100 and KKU-M156 cells.
Four caged xanthones, selected on the basis of their anticancer potency and chemical structure diversities (i.e. isomorellin, isomorellinol, forbesione and gambogic acid) were used in this study. Growth inhibition of these caged xanthones was determined using the sulforhodamine B assay. Induction of apoptosis was assessed by observing cell morphology, ethidium bromide and acridine orange staining and DNA fragmentation assay. Levels of apoptotic-related gene and protein expressions were determined by a real-time reverse transcriptase polymerase chain reaction and Western blotting analysis, respectively.
The compounds were found to inhibit growth of both cell lines in a dose-dependent manner and also showed selective cytotoxicity against the cancer cells when compared with normal peripheral blood mononuclear cells. Growth suppression by these compounds was due to apoptosis, as evidenced by the cell morphological changes, chromatin condensation, nuclear fragmentation, and DNA ladder formation. At the molecular level, these compounds induced down-regulation of Bcl-2 and survivin proteins with up-regulation of Bax and apoptosis-inducing factor proteins, leading to the activation of caspase-9 and -3 and DNA fragmentation. The functional group variations did not appear to affect the anticancer activity with regard to the two CCA cell lines; however, at a mechanistic level, isomorellinol exhibited the highest potency in increasing the Bax/Bcl-2 protein expression ratio (120 and 41.4 for KKU-100 and KKU-M156, respectively) and in decreasing survivin protein expression (0.01 fold as compared to control cells in both cell lines). Other activities at the molecular level indicate that functional groups on the prenyl side chain may be important.
Our findings for the first time demonstrate that four caged xanthones induce apoptosis in CCA cells which is mediated through a mitochondria-dependent signaling pathway.
研究从藤黄属植物汉布利中分离得到的 4 种笼状二氢黄酮醇对胆管癌细胞（CCA）KKU-100 和 KKU-M156 的生长抑制机制。
本研究选用了基于抗癌活性和化学结构多样性选择的 4 种笼状二氢黄酮醇（异美廉醇、异美廉醇、福布斯酮和藤黄酸）。采用磺酰罗丹明 B 法测定这些笼状二氢黄酮醇的生长抑制作用。通过观察细胞形态、溴化乙锭和吖啶橙染色和 DNA 片段化分析评估细胞凋亡的诱导。采用实时逆转录聚合酶链反应和 Western 印迹分析分别测定凋亡相关基因和蛋白的表达水平。
这些化合物呈剂量依赖性地抑制两种细胞系的生长，与正常外周血单个核细胞相比，对癌细胞也具有选择性细胞毒性。这些化合物的生长抑制作用是通过凋亡引起的，表现为细胞形态变化、染色质浓缩、核碎裂和 DNA 梯状形成。在分子水平上，这些化合物诱导 Bcl-2 和 survivin 蛋白下调，Bax 和凋亡诱导因子蛋白上调，导致 caspase-9 和 -3 的激活和 DNA 片段化。功能基团的变化似乎不会影响两种 CCA 细胞系的抗癌活性；然而，在机制水平上，异美廉醇在增加 Bax/Bcl-2 蛋白表达比值方面表现出最高的活性（对 KKU-100 和 KKU-M156 分别为 120 和 41.4），并降低 survivin 蛋白表达（与两种细胞系中的对照细胞相比为 0.01 倍）。其他分子水平上的活性表明，在 prenyl 侧链上的功能基团可能很重要。
我们的研究结果首次表明，4 种笼状二氢黄酮醇诱导 CCA 细胞凋亡，这是通过线粒体依赖性信号通路介导的。
