Department of Surgery, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, China.
World J Surg Oncol. 2010 Apr 20;8:31. doi: 10.1186/1477-7819-8-31.
Arsenic trioxide has been established as a first-line agent for treating acute promyelocytic leukemia. Experimental data suggest that arsenic trioxide also can have a potential use as chemotherapeutic agent for other malignancies. The precise mechanisms of action of arsenic trioxide have though not been elucidated. As the role of Bcl-2 in arsenic trioxide-mediated cell apoptosis and conformation change of Bcl-2 in response to arsenic trioxide treatment has not been studied. The aim of the present study was to determine whether conformation change of Bcl-2 is involved in the action of arsenic trioxide.
Human gastric cancer SGC7901 cells were exposed to different concentrations of arsenic trioxide. Proliferation was measured by using the Kit-8 cell counting assay. Analysis of nuclear morphology was observed by DAPI staining. The apoptosis rates of cells treated with arsenic trioxide were analyzed by flow cytometry using Annexin V-FITC staining. The conformation change of Bcl-2 and Bax activation were detected by immunostaining and Western blot analysis. Total expression of Bcl-2 and Bax were examined by Western blot analysis.
Arsenic trioxide inhibited the growth of human gastric cancer SGC7901 cells and induced apoptosis. There were two Bcl-2 phenotypes coexisting in SGC7901 cells and the Bcl-2 cytoprotective phenotype could change into a cytodestructive phenotype following conformational change of Bcl-2, triggered by arsenic trioxide exposure. Bax activation might also be involved in arsenic trioxide-induced Bcl-2 conformational change. Arsenic trioxide did not change levels of total Bcl-2 expression, but up-regulated total Bax expression for the treatment time ranging from 3 to 24 hours.
Arsenic trioxide induces apoptosis through induction of Bcl-2 conformational change, Bax activation and up-regulation of total Bax expression rather than affecting total Bcl-2 expression in human gastric cancer SGC7901 cells. The conformational change of Bcl-2 may be a novel described mechanism of arsenic trioxide-induced apoptosis in cancer cells.
三氧化二砷已被确立为治疗急性早幼粒细胞白血病的一线药物。实验数据表明，三氧化二砷也可能作为其他恶性肿瘤的化疗药物。然而，三氧化二砷的确切作用机制尚未阐明。由于 Bcl-2 在三氧化二砷介导的细胞凋亡中的作用以及 Bcl-2 对三氧化二砷治疗的构象变化尚未研究。本研究旨在确定 Bcl-2 的构象变化是否参与三氧化二砷的作用。
将人胃癌 SGC7901 细胞暴露于不同浓度的三氧化二砷中。通过 Kit-8 细胞计数测定法测量增殖。通过 DAPI 染色观察核形态分析。用 Annexin V-FITC 染色通过流式细胞术分析用三氧化二砷处理的细胞的凋亡率。通过免疫染色和 Western blot 分析检测 Bcl-2 和 Bax 激活的构象变化。通过 Western blot 分析检查 Bcl-2 和 Bax 的总表达。
三氧化二砷抑制人胃癌 SGC7901 细胞的生长并诱导凋亡。SGC7901 细胞中存在两种共存的 Bcl-2 表型，并且 Bcl-2 细胞保护表型可以在三氧化二砷暴露后通过 Bcl-2 的构象变化转变为细胞破坏性表型。Bax 激活也可能参与三氧化二砷诱导的 Bcl-2 构象变化。三氧化二砷并未改变总 Bcl-2 表达水平，但在 3 至 24 小时的治疗时间内上调了总 Bax 表达。
三氧化二砷通过诱导 Bcl-2 构象变化、Bax 激活和上调总 Bax 表达而不是影响人胃癌 SGC7901 细胞中的总 Bcl-2 表达来诱导细胞凋亡。Bcl-2 的构象变化可能是三氧化二砷诱导癌细胞凋亡的一种新描述的机制。
