Abstract A296: Eribulin mesylate suppresses experimental metastasis in the MX-1 human breast cancer model by reversing phenotypic states between epithelial-mesenchymal transition (EMT) to mesenchymal-epithelial transition (MET).
Authors: Yoshida Taku , Kuznetsov Galina , KImura Takayuki , Sugi Naoko H. , Shimizu Hajime , Ozawa Yoichi , Sato Yoshiaki , Uehara Taisuke , Watanabe Hideki , Takahashi Kentaro , Matsuura Kentaro , Uesugi Mai , Toyama Osamu , Yanagimachi Mamoru , Funahashi Yasuhiro , Matsui Junji 
Published: August 2014

Abstract
Background: Eribulin mesylate (eribulin), a non-taxane microtubule dynamics inhibitor, has unexpectedly shown greater effects on overall survival compared to progression-free survival in late stage metastatic breast cancer patients in the clinic. This finding suggests that eribulin may have additional, previously-unrecognized anti-tumor mechanisms beyond its established antimitotic activity. To investigate this possibility, eribulin's effects on the balance of EMT/ MET in MX-1 human breast cancer cells were investigated.
Methods: MX-1 human breast cancer cells, which are ER-/PR-/HER2- and have a mesenchymal phenotype, were treated with eribulin for 7 days, followed by measurement of EMT-related gene and protein expression changes by qPCR and immunoblot, respectively. In addition, the EMT/MET status of MX-1 xenografts in mice treated with eribulin were also examined by qPCR, immunoblot, and immunohistochemical analysis. Proliferation, migration and invasion assays were also conducted. Finally, an experimental lung metastasis model was utilized to gauge the metastatic activity of eribulin treated MX-1 cells.
Results: Treatment of MX-1 cells with eribulin in vitro led to morphological changes consistent with transition from a mesenchymal to an epithelial phenotype. Gene expression analyses showed that eribulin treatment led to decreased expression of several mesenchymal marker genes, together with increased expression of several epithelial marker genes. Furthermore, protein levels of epithelial marker E-cadherin were increased following eribulin treatment, while protein levels of mesenchymal markers N-cadherin and vimentin were decreased. Consistent with these changes, MX-1 cells treated with low levels of eribulin for one week showed decreased capacity for in vitro migration and invasiveness. In the MX-1 xenograft model in vivo, eribulin treatment induced MET as assessed by qPCR, immunoblot, and immunohistochemical analyses of epithelial and mesenchymal marker genes and proteins. Finally, MX-1 cells treated in vitro with low levels of eribulin for one week led to decreased numbers of lung metastases when assessed in an in vivo experimental metastasis model. Conclusions: Eribulin exerted significant effects on EMT/MET-related pathway components in human breast cancer cells in vitro and in vivo, consistent with a phenotypic switch from mesenchymal to epithelial states, and corresponding to observed decreases in migration and invasiveness in vitro as well as experimental metastasis in vivo. These preclinical findings provide a scientific basis for clinical observations of prolonged overall survival without corresponding effects on progression-free survival in metastatic breast cancer patients treated with eribulin.
Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A296.
Citation Format: Taku Yoshida, Galina Kuznetsov, Takayuki KImura, Naoko H. Sugi, Hajime Shimizu, Yoichi Ozawa, Yoshiaki Sato, Taisuke Uehara, Hideki Watanabe, Kentaro Takahashi, Kentaro Matsuura, Mai Uesugi, Osamu Toyama, Mamoru Yanagimachi, Yasuhiro Funahashi, Junji Matsui. Eribulin mesylate suppresses experimental metastasis in the MX-1 human breast cancer model by reversing phenotypic states between epithelial-mesenchymal transition (EMT) to mesenchymal-epithelial transition (MET). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A296.