Induction of N-Ras degradation by flunarizine-mediated autophagy

Ze Yi Zheng, Jing Li, Fuhai Li, Yanqiao Zhu, Kemi Cui, Stephen T. Wong, Eric C. Chang, Yi Hua Liao

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Ras GTPases are powerful drivers for tumorigenesis, but directly targeting Ras for treating cancer remains challenging. The growth and transforming activity of the aggressive basal-like breast cancer (BLBC) are driven by N-Ras. To target N-Ras in BLBC, this study screened existing pharmacologically active compounds for the new ability to induce N-Ras degradation, which led to the identification of flunarizine (FLN), previously approved for treating migraine and epilepsy. The FLN-induced N-Ras degradation was not affected by a 26S-proteasome inhibitor. Rather, it was blocked by autophagy inhibitors. Furthermore, N-Ras can be seen co-localized with active autophagosomes upon FLN treatment, suggesting that FLN alters the autophagy pathway to degrade N-Ras. Importantly, FLN treatment recapitulated the effect of N-RAS silencing in vitro by selectively inhibiting the growth of BLBC cells, but not that of breast cancer cells of other subtypes. In addition, in vivo FLN inhibited tumor growth of a BLBC xenograft model. In conclusion, this proof-of-principle study presents evidence that the autophagy pathway can be coerced by small molecule inhibitors, such as FLN, to degrade Ras as a strategy to treat cancer. FLN has low toxicity and should be further investigated to enrich the toolbox of cancer therapeutics.

Original languageEnglish
Article number16932
JournalScientific reports
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2018
Externally publishedYes

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    Zheng, Z. Y., Li, J., Li, F., Zhu, Y., Cui, K., Wong, S. T., Chang, E. C., & Liao, Y. H. (2018). Induction of N-Ras degradation by flunarizine-mediated autophagy. Scientific reports, 8(1), [16932]. https://doi.org/10.1038/s41598-018-35237-2