Department of Pathology, Xuzhou Medical College, Xuzhou, China.
Cancer Biother Radiopharm. 2012 Oct;27(8):504-12. doi: 10.1089/cbr.2012.1162. Epub 2012 Sep 18.
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.
目前，砷已在临床上被研究作为治疗各种实体恶性肿瘤的药物，包括乳腺癌。然而，三氧化二砷（As2O3）在实体肿瘤中诱导细胞生长停滞和凋亡的确切潜在分子机制尚不清楚。我们的研究旨在深入了解 As2O3 对人乳腺癌 MCF-7 细胞系的影响，并研究 MCF-7 细胞中 As2O3 处理后的细胞生长抑制、凋亡和分子机制。通过逆转录-聚合酶链反应（RT-PCR）测定 MCF-7 细胞中 FOXO3a、核-FOXO3a、caspase-3 和 IKKβ（IKKβ）mRNA 水平的表达。通过 Western blot 分析和免疫细胞化学染色检测蛋白质表达。通过流式细胞术评估凋亡细胞的分布，并通过 Hoechest33258 染色研究凋亡细胞的形态。我们的结果表明，As2O3 以剂量依赖的方式显著诱导本研究中 MCF-7 细胞的凋亡。As2O3 诱导 IKKβ 表达降低，总 FOXO3a 和核 FOXO3a 表达增加，从而触发细胞质 FOXO3a 在 Thr32 残基的磷酸化减少。RT-PCR、Western blot 分析和免疫细胞化学显示，当 As2O3 与肿瘤坏死因子-α（TNF-α）联合使用时，MCF-7 细胞中 IKKβ 的表达上调，而与单独使用 As2O3 相比，FOXO3a 的表达下调。这些发现表明 MCF-7 细胞系通过 FOXO3a 表达和定位对 As2O3 治疗敏感的特定分子机制。这种 FOXO3a 积累可能与 As2O3 诱导的活性 IKKβ 减少密切相关，这可能为 As2O3 相关信号转导活动提供新的见解。
