Induction of N-Ras degradation by flunarizine-mediated autophagy
Journal
Scientific Reports
Journal Volume
8
Journal Issue
1
Date Issued
2018
Author(s)
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. ? 2018, The Author(s).
SDGs
Other Subjects
flunarizine; Ras protein; animal; autophagosome; autophagy; disease model; drug effect; drug screening; genetics; human; metabolism; mouse; protein degradation; reporter gene; signal transduction; tumor cell line; Animals; Autophagosomes; Autophagy; Cell Line, Tumor; Disease Models, Animal; Drug Screening Assays, Antitumor; Flunarizine; Genes, Reporter; Humans; Mice; Proteolysis; ras Proteins; Signal Transduction; Xenograft Model Antitumor Assays
Publisher
Nature Publishing Group
Type
journal article