Mutations that increase both Hsp90 ATPase activity in vitro and Hsp90 drug resistance in vivo.
Hsp90 inhibitors are currently tested in clinical trials as anticancer agents. We investigated whether inhibitor resistance may arise as a result of a point mutation in Hsp90. We used yeast cells that expressed human Hsp90beta to select inhibitor-resistant mutants from the randomly mutagenized library. Single amino acid substitution, I123T, in a selected mutant was sufficient to confer inhibitor resistance. Transfection of human cells with the HSP90beta I123T and the corresponding HSP90alpha I128T yielded cell lines resistant to inhibitors of the Hsp90 ATPase. Unexpectedly, mutations did not result in diminished inhibitor binding in vitro. Similarly resistant cells were obtained after transfection with previously described A116N and T31I mutants of HSP90beta that cause increase in ATPase activity in vitro. Inhibitor-resistant phenotypes of the I123T and A116N mutants depended on their increased affinity for Aha1, whereas T31I mutation did not result in increased Aha1 binding. These results show possible scenario by which resistance may arise in patients treated with Hsp90 inhibitors. Additionally, our results show that each isoform of Hsp90 can alone sustain cellular functions.
International Institute of Molecular and Cell Biology, Warsaw, Poland.
Anna
A
Zurawska
Jakub
J
Urbanski
Jurgita
J
Matuliene
Janina
J
Baraniak
Marcin P
MP
Klejman
Slawomir
S
Filipek
Daumantas
D
Matulis
Pawel
P
Bieganowski
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D019943:Amino Acid Substitution; D016227:Benzoquinones / Q000494:pharmacology; D015153:Blotting, Western; D018833:Chaperonins / Q000235:genetics / Q000378:metabolism; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D007668:Kidney / Q000196:embryology; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C475092:AHA1 protein, S cerevisiae; C515652:AHSA1 protein, human; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; D018833:Chaperonins; C001277:geldanamycin