Ivermectin inhibits HSP27 and potentiates efficacy of oncogene targeting in tumor models
Lucia Nappi, … , Gary D. Brayer, Martin Gleave
Lucia Nappi, … , Gary D. Brayer, Martin Gleave
Published December 17, 2019
Citation Information: J Clin Invest. 2020;130(2):699-714. https://doi.org/10.1172/JCI130819.
View: Text | PDF
Research Article Oncology

Ivermectin inhibits HSP27 and potentiates efficacy of oncogene targeting in tumor models

Abstract

HSP27 is highly expressed in, and supports oncogene addiction of, many cancers. HSP27 phosphorylation is a limiting step for activation of this protein and a target for inhibition, but its highly disordered structure challenges rational structure-guided drug discovery. We performed multistep biochemical, structural, and computational experiments to define a spherical 24-monomer complex composed of 12 HSP27 dimers with a phosphorylation pocket flanked by serine residues between their N-terminal domains. Ivermectin directly binds this pocket to inhibit MAPKAP2-mediated HSP27 phosphorylation and depolymerization, thereby blocking HSP27-regulated survival signaling and client-oncoprotein interactions. Ivermectin potentiated activity of anti–androgen receptor and anti-EGFR drugs in prostate and EGFR/HER2-driven tumor models, respectively, identifying a repurposing approach for cotargeting stress-adaptive responses to overcome resistance to inhibitors of oncogenic pathway signaling.

Authors

Lucia Nappi, Adeleke H. Aguda, Nader Al Nakouzi, Barbara Lelj-Garolla, Eliana Beraldi, Nada Lallous, Marisa Thi, Susan Moore, Ladan Fazli, Dulguun Battsogt, Sophie Stief, Fuqiang Ban, Nham T. Nguyen, Neetu Saxena, Evgenia Dueva, Fan Zhang, Takeshi Yamazaki, Amina Zoubeidi, Artem Cherkasov, Gary D. Brayer, Martin Gleave

×

Figure 2

Ivermectin inhibits phosphorylation and oligomerization of HSP27 in cancer cells.

Options: View larger image (or click on image) Download as PowerPoint
Ivermectin inhibits phosphorylation and oligomerization of HSP27 in canc...
(A) Protein expression of phosphorylated (S78) and total HSP27 was evaluated by Western blotting after heat shock (42°C for 1 hour) in lung HCC-827 and prostate 22RV1 and PC3 cancer cells after treatment with increasing doses of IVM for 24 hours. (B) Quantification of HSP27 phosphorylation expression assessed by Western blotting after in vitro incubation with MAPKAP2 kinase in the presence of DMSO or IVM, at time 0 and after 24 hours. Results were averaged and normalized as a percentage of the control at 24 hours. Data shown as mean ± SEM; *P < 0.05 by unpaired 2-tailed Student’s t test with Welch’s correction; n = 3 independent experiments. RIU, relative intensity units. (C) Expression of HSP27 protein fractions of glycerol gradient from PC3 (top panel) and HCC-827 (bottom panel) cells treated with DMSO (CTRL) or IVM (5 μM for 24 hours). (D) PC3 (top panel) and HCC-827 (bottom panel) cells treated with DMSO (CTRL) or IVM (5 μM for 24 hours) were exposed to heat shock (42°C for 1 hour), fixed using cold methanol, and stained for HSP27 (green). DAPI (blue) was used for nuclear staining. Scale bars: 20 μm.