Oncogenic activation of the mTOR signaling pathway occurs frequently in tumor cells and contributes to the devastating features of cancer, including breast cancer. mTOR inhibitors rapalogs are promising anticancer agents in clinical trials; however, rapalogs resistance remains an unresolved clinical challenge. Therefore, understanding the mechanisms by which cells become resistant to rapalogs may guide the development of successful mTOR-targeted cancer therapy. In this study, we found that eEF-2K, which is overexpressed in cancer cells and is required for survival of stressed cells, was involved in the negative-feedback activation of Akt and cytoprotective autophagy induction in breast cancer cells in response to mTOR inhibitors. Therefore, disruption of eEF-2K simultaneously abrogates the two critical resistance signaling pathways, sensitizing breast cancer cells to rapalogs. Importantly, we identified mitoxantrone, an admitted anticancer drug for a wide range of tumors, as a potential inhibitor of eEF-2K via a structure-based virtual screening strategy. We further demonstrated that mitoxantrone binds to eEF-2K and inhibits its activity, and the combination treatment of mitoxantrone and mTOR inhibitor resulted in significant synergistic cytotoxicity in breast cancer. In conclusion, we report that eEF-2K contributes to the activation of resistance signaling pathways of mTOR inhibitor, suggesting a novel strategy to enhance mTOR-targeted cancer therapy through combining mitoxantrone, an eEF-2K inhibitor.
|Journal||Cell Death and Disease|
|State||Published - Nov 1 2020|
Bibliographical noteFunding Information:
HA-AMPK plasmid was a gift from Xiamen University. This research was supported by grants from the National Natural Science Foundation of China 81422051 and 81972480; The Hunan Postgraduate Research Innovation Project 206021704.
© 2020, The Author(s).
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience
- Cell Biology
- Cancer Research