Forkhead box K2 modulates epirubicin and paclitaxel sensitivity through FOXO3a in breast cancer.
Forkhead box K2 modulates epirubicin and paclitaxel sensitivity through FOXO3a in breast cancer.
复制标题
DOI：
10.1038/oncsis.2015.26
复制
发表时间：
2015-09-07
期刊：
影响因子：
6.2
通讯作者：
Lam EW
中科院分区：
文献类型：
--
作者：
Nestal de Moraes G;Khongkow P;Gong C;Yao S;Gomes AR;Ji Z;Kandola N;Delbue D;Man EP;Khoo US;Sharrocks AD;Lam EW
叉头转录因子FOXK2最近被认为与癌细胞增殖和存活有关，但在癌症化疗耐药中的作用迄今尚未被探索。在这里，我们证明FOXK2在介导乳腺癌细胞毒性药物反应中起核心作用。克隆性和细胞活力分析表明，FOXK2表达增强使MCF-7乳腺癌细胞对紫杉醇或表柔比星治疗敏感，而FOXK2被小干扰rna （sirna）耗尽则会产生耐药性。我们的数据还表明，紫杉醇和表柔比星对肿瘤抑制因子FOXO3a的激活是通过诱导FOXK2介导的，因为siRNA耗尽FOXK2限制了这些药物在MCF-7细胞中对FOXO3a的诱导。染色质免疫沉淀（ChIP）分析显示，在药物治疗的反应中，FOXK2在MCF-7细胞中积累并结合到FOXO3a近端启动子区域。此外，我们还发现FOXK2不受调控，因此可以在紫杉醇和表柔比星耐药MCF-7细胞的细胞核中高水平表达。我们的研究结果表明，异位过表达的FOXK2在耐药MCF-7细胞的细胞核中积累，但未能被招募到靶基因，包括FOXO3a。至关重要的是，我们发现FOXO3a是MCF-7细胞中FOXK2抗增殖和表柔比星诱导的细胞毒功能所必需的。乳腺癌患者样本中FOXO3a和FOXK2表达的显著相关性进一步证实了FOXK2调控FOXO3a的生理重要性。进一步的生存分析还表明，高核FOXK2表达与较差的临床结果显著相关，特别是在接受常规化疗的患者中，这与我们的发现一致，即FOXK2在耐药细胞中不受调节。总之，我们的研究结果表明，紫杉醇和表柔比星靶向FOXK2来调节它们的细胞毒性，而FOXK2的失调会导致耐药性。
The forkhead transcription factor FOXK2 has recently been implicated in cancer cell proliferation and survival, but a role in cancer chemotherapeutic drug resistance has hitherto not been explored. Here we demonstrate that FOXK2 has a central role in mediating the cytotoxic drug response in breast cancer. Clonogenic and cell viability assays showed that enhanced FOXK2 expression sensitizes MCF-7 breast cancer cells to paclitaxel or epirubicin treatment, whereas FOXK2 depletion by small interfering RNAs (siRNAs) confers drug resistance. Our data also showed that the activation of the tumour suppressor FOXO3a by paclitaxel and epirubicin is mediated through the induction of FOXK2, as depletion of FOXK2 by siRNA limits the induction of FOXO3a by these drugs in MCF-7 cells. Chromatin immunoprecipitation (ChIP) analysis showed that in response to drug treatment, FOXK2 accumulates and binds to the proximal FOXO3a promoter region in MCF-7 cells. Furthermore, we also uncovered that FOXK2 is deregulated and, therefore, can express at high levels in the nucleus of both the paclitaxel and epirubicin drug-resistant MCF-7 cells. Our results showed that ectopically overexpressed FOXK2 accumulates in the nuclei of drug-resistant MCF-7 cells but failed to be recruited to target genes, including FOXO3a. Crucially, we found that FOXO3a is required for the anti-proliferative and epirubicin-induced cytotoxic function of FOXK2 in MCF-7 cells by sulphorhodamine and clonogenic assays. The physiological importance of the regulation of FOXO3a by FOXK2 is further confirmed by the significant correlations between FOXO3a and FOXK2 expression in breast carcinoma patient samples. Further survival analysis also reveals that high nuclear FOXK2 expression significantly associates with poorer clinical outcome, particularly in patients who have received conventional chemotherapy, consistent with our finding that FOXK2 is deregulated in drug-resistant cells. In summary, our results suggest that paclitaxel and epirubicin target the FOXK2 to modulate their cytotoxicity and deregulated FOXK2 confers drug resistance.