Elimination of both rapidly dividing epithelial mammary cancer cells as well as breast cancer stem-like cells (bCSC) is essential for maximizing antitumor response. Withaferin A (WA), a small molecule derived from a medicinal plant ( Withania somnifera ), is highly effective in reducing burden and/or incidence of breast cancer in vivo in various preclinical models. We have shown previously that suppression of breast cancer incidence by WA administration in a rat model is associated with a decrease in self-renewal of bCSC but the underlying mechanism is still elusive. This study investigated the role of forkhead box Q1 (FoxQ1) transcription factor in antitumor responses to WA. Exposure of MDA-MB-231 and SUM159 cells to WA resulted in downregulation of protein and mRNA levels of FoxQ1 as well as inhibition of its transcriptional activity. FoxQ1 overexpression in SUM159 and MCF-7 cells resulted in a marked protection against WA-mediated inhibition of bCSC as judged by flow cytometric analysis of CD49fhigh population and mammosphere assay. RNA-sequencing analysis revealed upregulation of many bCSC-associated genes by FoxQ1 overexpression in SUM159 cells, including IL8 whose expression was decreased by WA treatment in SUM159 and MCF-7 cells. FoxQ1 was recruited to the promoter of IL8 that was inhibited significantly by WA treatment. On the other hand, WA-mediated inhibition of cell proliferation or migration was not affected by FoxQ1 overexpression. The FoxQ1 overexpression partially attenuated WA-mediated G2–M phase cell cycle arrest in SUM159 cells only. These results indicate that FoxQ1 is a target of WA for inhibition of bCSC fraction. Prevention Relevance: Withaferin A (WA) is highly effective in reducing burden and/or incidence of breast cancer in various preclinical models. However, the mechanism underlying breast cancer prevention by WA is not fully understood. This study shows a role for FoxQ1 in antitumor response to WA.

中文翻译：

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Forkhead Box Q1转录因子在Withaferin A抗癌作用中的作用

消除快速分裂的上皮性乳腺癌细胞和乳腺癌干细胞样细胞 (bCSC) 对于最大限度地提高抗肿瘤反应至关重要。Withaferin A (WA) 是一种源自药用植物 (Withania somnifera) 的小分子，在各种临床前模型中对减轻体内乳腺癌负担和/或发病率非常有效。我们之前已经表明，在大鼠模型中通过 WA 给药抑制乳腺癌发病率与 bCSC 自我更新的减少有关，但潜在的机制仍然难以捉摸。本研究调查了叉头盒 Q1 (FoxQ1) 转录因子在对 WA 的抗肿瘤反应中的作用。将 MDA-MB-231 和 SUM159 细胞暴露于 WA 会导致 FoxQ1 的蛋白质和 mRNA 水平下调，并抑制其转录活性。通过流式细胞术分析 CD49fhigh 群和乳腺球测定来判断，SUM159 和 MCF-7 细胞中的 FoxQ1 过表达导致对 WA 介导的 bCSC 抑制的显着保护。RNA 测序分析显示，SUM159 细胞中 FoxQ1 过表达导致许多 bCSC 相关基因上调，包括在 SUM159 和 MCF-7 细胞中通过 WA 处理降低其表达的 IL8。FoxQ1 被招募到被 WA 处理显着抑制的 IL8 的启动子。另一方面，WA 介导的细胞增殖或迁移抑制不受 FoxQ1 过表达的影响。FoxQ1 过表达仅在 SUM159 细胞中部分减弱 WA 介导的 G2-M 期细胞周期停滞。这些结果表明 FoxQ1 是 WA 抑制 bCSC 部分的靶标。预防相关：在各种临床前模型中，Withaferin A (WA) 在减轻乳腺癌负担和/或发病率方面非常有效。然而，WA预防乳腺癌的机制尚不完全清楚。这项研究显示了 FoxQ1 在对 WA 的抗肿瘤反应中的作用。