Zurawska Anna, Urbanski Jakub, Matuliene Jurgita, Baraniak Janina, Klejman Marcin P, Filipek Slawomir, Matulis Daumantas, Bieganowski Pawel
International Institute of Molecular and Cell Biology, Warsaw, Poland.
Biochim Biophys Acta. 2010 May;1803(5):575-83. doi: 10.1016/j.bbamcr.2010.03.002. Epub 2010 Mar 11.
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.
热休克蛋白90（Hsp90）抑制剂目前正在作为抗癌药物进行临床试验。我们研究了Hsp90中的点突变是否会导致抑制剂耐药性的产生。我们使用表达人Hsp90β的酵母细胞从随机诱变文库中筛选出抑制剂抗性突变体。在一个选定的突变体中，单个氨基酸取代I123T足以赋予抑制剂抗性。用HSP90β I123T和相应的HSP90α I128T转染人细胞，产生了对Hsp90 ATP酶抑制剂耐药的细胞系。出乎意料的是，这些突变在体外并未导致抑制剂结合减少。用先前描述的HSP90β的A116N和T31I突变体转染后也获得了类似的耐药细胞，这些突变体在体外会导致ATP酶活性增加。I123T和A116N突变体的抑制剂耐药表型取决于它们对Aha1亲和力的增加，而T31I突变并未导致Aha1结合增加。这些结果显示了接受Hsp90抑制剂治疗的患者可能出现耐药性的情况。此外，我们的结果表明，Hsp90的每种同工型都能单独维持细胞功能。
