The conformation change of Bcl-2 is involved in arsenic trioxide-induced apoptosis and inhibition of proliferation in SGC7901 human gastric cancer cells.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Zheng
Yihu
Y
Department of Surgery, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, China. zhengyihu@gmail.com
Zhou
Mengtao
M
Ye
Aifang
A
Li
Qiu
Q
Bai
Yongheng
Y
Zhang
Qiyu
Q
D017304:Annexin A5 / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D010087:Oxides / Q000494:pharmacology*; D011487:Protein Conformation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D017304:Annexin A5; D000970:Antineoplastic Agents; D001152:Arsenicals; D010087:Oxides; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D000077237:Arsenic Trioxide
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