Characterizing mechanisms of potential inhibitors of the Hsp90 chaperone complex
Abstract
In this work, we characterized the effects of ten compounds reported to be inhibitors of the Hsp90 chaperone complex in Jurkat leukemia cells, and compared them to the N-terminal Hsp90 inhibitor AUY922. Our primary focus was to elucidate the proteomic profile of C-terminal Hsp90 inhibition. Changes in protein expression of treated cells were quantified by labeling peptides with Tandem Mass Tags (TMT) isobaric labels, and SPS-MS3 methodologies leading to approximately 6000 proteins identified in all biological replicates (n=6). We characterized the compounds for hallmark Hsp90 inhibition motifs including the induction of the heat shock response, and depletion of Hsp90-dependent protein kinases. In both our Western blotting and proteomic data: ailanthone, celastrol, clorobiocin, gambogic acid, coumermycin A1, derrubone, garcinol, daurisoline, β-lapachone, and α-mangostin failed to depleted Hsp90-dependent clients. Pairwise comparisons of proteomic perturbations in response to drug treatment showed negligible Pearson correlation between AUY922 and all the compounds in our panel, except celastrol. Bootstrapped hierarchical clustering was completed on our compound panel alone, and along with previously generated data by our lab group, and from the literature. The compounds from our panel generated a distinct cluster away from the branch containing N-terminal Hsp90 inhibitors and proteostasis perturbing compounds. From this we concluded that none of the compounds characterized are inhibitors of the Hsp90 chaperone complex. Additionally, we suggest scrapping the C-terminal Hsp90 inhibition model. Bioinformatics analysis consisting of GO, and protein-protein interaction networks enriched terms indicting that the majority of the compounds induce apoptosis through disruption of the endoplasmic reticulum and/or the mitochondria. After completing an additional literature review guided by our bioinformatics enrichments we found studies supporting our findings. As such, we suggest that future studies on the compounds not be focused on Hsp90 inhibition.
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- OSU Dissertations [11222]