Multi-kinase inhibitors can associate with heat shock proteins through their NH2-termini by which they suppress chaperone function

Laurence Booth, Brian Shuch, Thomas Albers, Jane L. Roberts, Mehrad Tavallai, Stefan Proniuk, Alexander Zukiwski, Dasheng Wang, Ching Shih Chen, Don Bottaro, Heath Ecroyd, Iryna O. Lebedyeva, Paul Dent

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We performed proteomic studies using the GRP78 chaperone-inhibitor drug AR-12 (OSU-03012) as bait. Multiple additional chaperone and chaperone-associated proteins were shown to interact with AR-12, including: GRP75, HSP75, BAG2; HSP27; ULK-1; and thioredoxin. AR-12 down-regulated in situ immuno-fluorescence detection of ATP binding chaperones using antibodies directed against the NH2-termini of the proteins but only weakly reduced detection using antibodies directed against the central and COOH portions of the proteins. Traditional SDS-PAGE and western blotting assessment methods did not exhibit any alterations in chaperone detection. AR-12 altered the sub-cellular distribution of chaperone proteins, abolishing their punctate speckled patterning concomitant with changes in protein co-localization. AR-12 inhibited chaperone ATPase activity, which was enhanced by sildenafil; inhibited chaperone - chaperone and chaperone - client interactions; and docked in silico with the ATPase domains of HSP90 and of HSP70. AR-12 combined with sildenafil in a GRP78 plus HSP27 -dependent fashion to profoundly activate an eIF2α/ATF4/CHOP/Beclin1 pathway in parallel with inactivating mTOR and increasing ATG13 phosphorylation, collectively resulting in formation of punctate toxic autophagosomes. Over-expression of [GRP78 and HSP27] prevented: AR-12 -induced activation of ER stress signaling and maintained mTOR activity; AR-12 -mediated down-regulation of thioredoxin, MCL-1 and c-FLIP-s; and preserved tumor cell viability. Thus the inhibition of chaperone protein functions by AR-12 and by multi-kinase inhibitors very likely explains why these agents have anti-tumor effects in multiple genetically diverse tumor cell types.

Original languageEnglish (US)
Pages (from-to)12975-12996
Number of pages22
Issue number11
StatePublished - Mar 15 2016
Externally publishedYes


  • ATPase
  • Chaperones
  • OSU-03012
  • Pazopanib
  • Sorafenib

ASJC Scopus subject areas

  • Oncology


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