The role of autophagy in the cytotoxicity induced by trastuzumab emtansine (T-DM1) in HER2-positive breast cancer cells.

Abstract

Trastuzumab emtansine (T-DM1), an antibody-drug conjugate (ADC) of trastuzumab and cytotoxic agent emtansine (DM1), has been approved for the therapy of metastatic HER2-positive breast cancer after prior treatment of trastuzumab and taxane. The impressive efficacy exhibited by T-DM1 has heightened the need for more further studies on the underlying mechanisms of T-DM1 cytotoxicity. Previous research suggested that autophagy was crucial for cancer therapy, but the role of autophagy in T-DM1 treatment has not been investigated. Here, we demonstrated for the first time that T-DM1 triggered obvious autophagy in HER2-positive SK-BR-3 and BT-474 breast cancer cells. Blocking autophagy with pharmacological inhibitors chloroquine (CQ) or LY294002 partly reduced T-DM1-induced apoptosis and Caspase-3/7 activation, suggesting that autophagy played an essential role in the cytotoxicity induced by T-DM1 in HER2-positive breast cancer cells. Further investigation demonstrated that Akt/mTOR signaling pathway was involved in T-DM1-induced autophagy in a time-dependent manner. Altogether, our results highlighted the important role of autophagy as a novel mechanism for T-DM1-induced cytotoxicity and elucidated the critical relationships between T-DM1-induced autophagy and apoptosis in human HER2-positive breast cancer cells, which provides novel insight into the underlying anti-tumor mechanism of T-DM1.

• Authors: Peipei Liu, Jiajun Fan, Ziyu Wang, Wenjing Zai, Ping Song, Yongping Li, Dianwen Ju
• Journal: AMB Express (AMB Express) Vol. 10 Issue 1 Pg. 107 (Jun 03 2020) ISSN: 2191-0855 [Print] Germany
• PMID: 32495214 (Publication Type: Journal Article)