Lu Xiangdong, Ma Jingjing, Chu Jiahui, Shao Qing, Zhang Yao, Lu Guangping, Li Jun, Huang Xiang, Li Wei, Li Yongfei, Ling Yang, Zhao Tao
Department of Oncolgy, Jiangyin People's Hospital Affiliated to Southeast University, Jiangyin, China.
Department of Breast, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing, China.
Cell Physiol Biochem. 2017;44(6):2346-2356. doi: 10.1159/000486122. Epub 2017 Dec 15.
BACKGROUND/AIMS: Trastuzumab is an important treatment used for patients with Her-2-positive breast cancer, but an increasing incidence of trastuzumab resistance has been observed clinically during the past decade. Aberrant microRNA (miR) expression levels are correlated with prognosis and response to trastuzumab in breast cancer. MiR-129-5p is downregulated in trastuzumab-resistant human breast cancer cells (JIMT-1), but its potential function and underlying mechanism remain unclear.
Quantitative RT-PCR (qRT-PCR) was used to determine the expression levels of miR-129-5p and its potential target genes. The effects of miR-129-5p on cell responses to trastuzumab were analyzed by CCK-8 and flow cytometry assays in Her-2-positive breast cancer cells (SKBR-3 and JIMT-1). Bio-informatics analyses were performed to predict target genes of miR-129-5p, and luciferase assays were carried out to confirm the binding of miR-129-5p and rpS6.
MiR-129-5p, which was downregulated and predicted to target rpS6 in trastuzumab-resistant breast cancer cells, enhanced the sensitivity of breast cancer cells to trastuzumab by reducing the expression of rpS6. Moreover, the overexpression of rpS6 reversed the sensitivity of cells to trastuzumab induced by miR-129-5p.
MiR-129-5p sensitized Her-2-positive breast cancer to trastuzumab by downregulating rpS6. These findings provide novel insights into the common role of rpS6 and its related molecular mechanisms in mediating trastuzumab-resistance in Her-2-positive breast cancers.
背景/目的：曲妥珠单抗是用于治疗人表皮生长因子受体2（Her-2）阳性乳腺癌患者的重要药物，但在过去十年中，临床上观察到曲妥珠单抗耐药的发生率不断增加。异常的微小RNA（miR）表达水平与乳腺癌的预后及对曲妥珠单抗的反应相关。MiR-129-5p在曲妥珠单抗耐药的人乳腺癌细胞（JIMT-1）中表达下调，但其潜在功能及潜在机制仍不清楚。
采用定量逆转录聚合酶链反应（qRT-PCR）检测miR-129-5p及其潜在靶基因的表达水平。通过CCK-8和流式细胞术分析miR-129-5p对Her-2阳性乳腺癌细胞（SKBR-3和JIMT-1）对曲妥珠单抗反应的影响。进行生物信息学分析以预测miR-129-5p的靶基因，并进行荧光素酶测定以确认miR-129-5p与核糖体蛋白S6（rpS6）的结合。
MiR-129-5p在曲妥珠单抗耐药的乳腺癌细胞中表达下调，并预测其靶向rpS6，通过降低rpS6的表达增强了乳腺癌细胞对曲妥珠单抗的敏感性。此外，rpS6的过表达逆转了miR-129-5p诱导的细胞对曲妥珠单抗的敏感性。
MiR-129-5p通过下调rpS6使Her-2阳性乳腺癌对曲妥珠单抗敏感。这些发现为rpS6及其相关分子机制在介导Her-2阳性乳腺癌曲妥珠单抗耐药中的共同作用提供了新的见解。
