Micro RNA 100 sensitizes luminal A breast cancer cells to paclitaxel treatment in part by targeting mTOR

• Published in: Oncotarget Vol. 7; no. 5; pp. 5702 - 5714
• Main Authors: Zhang, Baotong, Zhao, Ranran, He, Yuan, Fu, Xing, Fu, Liya, Zhu, Zhengmao, Fu, Li, Dong, Jin-Tang
• Format: Journal Article
• Language: English
• Published: Impact Journals LLC 02.02.2016
• Subjects: Research Paper
• DOI: 10.18632/oncotarget.6790
• ISSN: 1949-2553

Luminal A breast cancer usually responds to hormonal therapies but does not benefit from chemotherapies, including microtubule-targeted paclitaxel. MicroRNAs could play a role in mediating this differential response. In this study, we examined the role of micro RNA 100 (miR-100) in the sensitivity of breast cancer to paclitaxel treatment. We found that while miR-100 was downregulated in both human breast cancer primary tumors and cell lines, the degree of downregulation was greater in the luminal A subtype than in other subtypes. The IC 50 of paclitaxel was much higher in luminal A than in basal-like breast cancer cell lines. Ectopic miR-100 expression in the MCF-7 luminal A cell line enhanced the effect of paclitaxel on cell cycle arrest, multinucleation, and apoptosis, while knockdown of miR-100 in the MDA-MB-231 basal-like line compromised these effects. Similarly, overexpression of miR-100 enhanced the effects of paclitaxel on tumorigenesis in MCF-7 cells. Rapamycin-mediated inhibition of the mammalian target of rapamycin (mTOR), a target of miR-100, also sensitized MCF-7 cells to paclitaxel. Gene set enrichment analysis showed that genes that are part of the known paclitaxel-sensitive signature had a significant expression correlation with miR-100 in breast cancer samples. In addition, patients with lower levels of miR-100 expression had worse overall survival. These results suggest that miR-100 plays a causal role in determining the sensitivity of breast cancers to paclitaxel treatment.