title: Arsenic trioxide-induced growth arrest of breast cancer MCF-7 cells involving FOXO3a and IκB kinase β expression and localization.
abstract: Currently, arsenic has been clinically investigated as a therapeutic agent for a variety of solid malignancies, including breast cancer. However, the exact underlying molecular mechanisms through which arsenic trioxide (As(2)O(3)) induces cell growth arrest and apoptosis in solid tumors have not been clearly understood. The aim of our study was to gain an insight into the effect of As(2)O(3) on the human breast cancer MCF-7 cell line and investigate cell growth inhibition, apoptosis, and the molecular mechanism after As(2)O(3) treatment in MCF-7 cells. Expression of FOXO3a, nuclear-FOXO3a, caspase-3, and IκB kinase β (IKKβ) mRNA levels in MCF-7 cells was determined by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression was examined by the Western blot analysis and immunocytochemical staining. The distribution of apoptotic cells was assessed by flow cytometry, and the morphology of the apoptotic cells was investigated by Hoechest33258 staining. Our results showed that As(2)O(3) significantly induced the apoptosis of MCF-7 cells tested in this study in a dose-dependent manner. As(2)O(3) induced the decrease of IKKβ expression and the increase of total as well as nuclear FOXO3a expression, which triggered the phosphorylation of cytoplasmic FOXO3a at the Thr32 residue decrease. RT-PCR, Western blot analysis, and immunocytochemistry revealed that the expression of IKKβ in MCF-7 cells was upregulated when As(2)O(3) was combined with tumor necrosis factor-α (TNF-α), whereas the expression of FOXO3a was downregulated in comparison with the As(2)O(3)-alone group. These findings indicated a specific molecular mechanism by which MCF-7 cell lines were susceptible to the As(2)O(3) therapy through FOXO3a expression and localization. This FOXO3a accumulation may be well correlated with the As(2)O(3)-induced reduction of active IKKβ, which may provide new insights into As(2)O(3)-related signaling activities.
authors.affiliation: Department of Pathology, Xuzhou Medical College, Xuzhou, China.
authors.forename: Wenlou
authors.initials: W
authors.lastname: Liu
authors.forename: Yusen
authors.initials: Y
authors.lastname: Gong
authors.forename: Haili
authors.initials: H
authors.lastname: Li
authors.forename: Guan
authors.initials: G
authors.lastname: Jiang
authors.forename: Shining
authors.initials: S
authors.lastname: Zhan
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Yongping
authors.initials: Y
authors.lastname: Wu
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000096:biosynthesis / Q000235:genetics; D048708:Cell Growth Processes / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D051550:I-kappa B Kinase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007150:Immunohistochemistry; D061986:MCF-7 Cells; D010087:Oxides / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D001152:Arsenicals; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D006131:Growth Inhibitors; D010087:Oxides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051550:I-kappa B Kinase; D053148:Caspase 3; D000077237:Arsenic Trioxide