Yang Xing, Hu Qian, Hu Lan-Xin, Lin Xiao-Rong, Liu Jie-Qiong, Lin Xiao, Dinglin Xiao-Xiao, Zeng Jia-Yi, Hu Hai, Luo Man-Li, Yao He-Rui
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510120, China.
Department of Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510120, China.
Discov Med. 2017 Sep;24(131):75-85.
Chemotherapy is a cornerstone treatment for early and advanced stage breast cancer patients. However, resistance to chemotherapy remains a major obstacle, resulting in disease relapse and progression. Emerging studies demonstrated that miRNAs regulate chemotherapy-induced epithelial-mesenchymal transition (EMT) and drug resistance, but the underlying mechanisms remain unclear. Here we established a doxorubicin-resistant breast cancer cell line MCF-7/Adr, and found these cells exhibited an EMT phenotype featured by a fibroblast-like morphology, increased the capacity of migration and invasion, and underwent the changes of molecular markers of EMT including E-cadherin, N-cadherin, and vimentin. We then compared the miRNA expression profiles between MCF-7/Adr and parental MCF-7 by miRNA microarray, and identified miR-200b as the most dramatically down-regulated miRNA. Overexpression of miR-200b in chemo-resistant cells reversed the EMT phenotype and increased sensitivity to doxorubicin. Inhibition of miR-200b in parental cells induced EMT and resistance to doxorubicin. Furthermore, we characterized the target gene of miR-200b, and showed that overexpression of miR-200b down-regulated FN1 expression and the luciferase activity. Compared with the parental cells, FN1 was significantly elevated in MCF-7/Adr cells. Knockdown of FN1 reversed mesenchymal morphology, inhibited cell migration and invasion, and sensitized cells to doxorubicin. Our data suggest that miR-200b regulates EMT of chemo-resistant breast cancer cells by targeting FN1. miR-200b-based therapy may be an effective strategy in treating advanced breast cancer patients.
化疗是早期和晚期乳腺癌患者的基石治疗方法。然而，对化疗的耐药性仍然是一个主要障碍，导致疾病复发和进展。新兴研究表明，微小RNA（miRNA）调节化疗诱导的上皮-间质转化（EMT）和耐药性，但其潜在机制仍不清楚。在此，我们建立了阿霉素耐药乳腺癌细胞系MCF-7/Adr，并发现这些细胞表现出EMT表型，其特征为成纤维细胞样形态、迁移和侵袭能力增强，以及EMT分子标志物E-钙黏蛋白、N-钙黏蛋白和波形蛋白发生变化。然后，我们通过miRNA微阵列比较了MCF-7/Adr和亲本MCF-7之间的miRNA表达谱，鉴定出miR-200b是下调最显著的miRNA。在化疗耐药细胞中过表达miR-200b可逆转EMT表型并增加对阿霉素的敏感性。在亲本细胞中抑制miR-200b可诱导EMT和对阿霉素的耐药性。此外，我们对miR-200b的靶基因进行了表征，结果表明miR-200b过表达下调了纤连蛋白1（FN1）的表达和荧光素酶活性。与亲本细胞相比，MCF-7/Adr细胞中FN1显著升高。敲低FN1可逆转间充质形态，抑制细胞迁移和侵袭，并使细胞对阿霉素敏感。我们的数据表明，miR-200b通过靶向FN1调节化疗耐药乳腺癌细胞的EMT。基于miR-200b的治疗可能是治疗晚期乳腺癌患者的有效策略。
