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

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

来源：Oncotarget, 2016, 7(11): 12975-12996.

DOI：10.18632/oncotarget.7349

• OSU-03012
• sorafenib
• pazopanib
• chaperones
• ATPase

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 eIF2a/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.

• 出版日期2016-3-15