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

Abstract

BackgroundArsenic 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.MethodsHuman 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.ResultsArsenic 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.ConclusionArsenic 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.

Inactivation of Akt by arsenic trioxide induces cell death via mitochondrial-mediated apoptotic signaling in SGC-7901 human gastric cancer cells

“…In the present study, apoptotic morphological changes were observed in the nuclei of the SGC-7901 cells following treatment with As 2 O 3 , and FACS analysis showed that As 2 O 3 caused dose-dependent apoptotic cell death. This result is similar to previous reports (11,51). Consistent with a previous report (52), As 2 O 3 increased active cleaved caspase-3 (17 kDa) and cleaved fragment of PARP (89 kDa).…”

“…However, with regard to solid tumors, it remains controversial whether apoptosis is involved in the cell death induced by As 2 O 3 (11,(24)(25)(26). Although the process of apoptosis is mediated primarily by proteolytic activities, there is compelling evidence that signal transduction pathways involving specific protein kinases modulate the apoptotic response (27).…”

“…At present, it is recognized as a potent chemotherapeutic agent and has been approved by the Food and Drug Administration for the treatment of certain leukemias (8)(9)(10). Previous studies have demonstrated that As 2 O 3 may have beneficial effects in the treatment of solid tumors including gastric cancer (11), hepatocellular carcinoma (12), breast cancer (13), lung cancer (14) and neuroblastoma (15); however, there are limitations to its application in the treatment of solid tumors owing to the necessity of high concentrations for antineoplastic efficacy (16,17). Therefore, a better understanding of the underlying mechanisms of action of As 2 O 3 may facilitate the development of strategies to induce therapeutic responses using lower concentrations of As 2 O 3 (18).…”

ABT-737 Synergizes with Arsenic Trioxide to Induce Apoptosis of Gastric Carcinoma Cells In Vitro and In Vivo

“…23 Mechanisms that might explain the antitumour cytotoxicity of ATO include its ability to induce cell apoptosis and differentiation, and to inhibit cell proliferation. 24 ATO has also been shown to induce the apoptosis of gastric cancer cells 25,26 and to downregulate Mcl-1, thereby enhancing the ability of ABT-737 to kill myeloma cells. 27 These results suggest that these two inducers of apoptosis (ABT-737 and ATO) might work synergistically to induce gastric cancer cell apoptosis.…”

MAPK/ERK Activation Sensitizes MKN-28 Cells to Cisplatin-Induced Apoptosis

“…35 Moreover, BCL-2 was reported as a target gene for many signaling cascades, such as Phosphatidylinositol 3 kinase (PI3K)/ nuclear factor-κB (NF-κB) signaling pathway, the cyclic AMP (cAMP)/protein kinase A (PKA) cascade, MAPK cascade and so on. 36,37 In this study, we found that treatment of cisplatin increased phosphorylation of ERK proteins, which intervened downstream anti-apoptosis molecular BCL-2 and up-regulation of pro-apoptosis molecular BAK in gastric cancer MKN-28 cells.…”