Gene and Protein Expression Profiling of Human Ovarian Cancer Cells Treated with the Heat Shock Protein 90 Inhibitor 17-Allylamino-17-Demethoxygeldanamycin

Abstract

The promising antitumor activity of 17-allylamino-17-demethoxygeldanamycin (17AAG) results from inhibition of the molecular chaperone heat shock protein 90 (HSP90) and subsequent degradation of multiple oncogenic client proteins. Gene expression microarray and proteomic analysis were used to profile molecular changes in the A2780 human ovarian cancer cell line treated with 17AAG. Comparison of results with an inactive analogue and an alternative HSP90 inhibitor radicicol indicated that increased expression of HSP72, HSC70, HSP27, HSP47, and HSP90B at the mRNA level were on-target effects of 17AAG. HSP27 protein levels were increased in tumor biopsies following treatment of patients with 17AAG. A group of MYC-regulated mRNAs was decreased by 17AAG. Of particular interest and novelty were changes in expression of chromatin-associated proteins. Expression of the heterochromatin protein 1 was increased, and expression of the histone acetyltransferase 1 and the histone arginine methyltransferase PRMT5 was decreased by 17AAG. PRMT5 was shown to be a novel HSP90-binding partner and potential client protein. Cellular protein acetylation was reduced by 17AAG, which was shown to have an antagonistic interaction on cell proliferation with the histone deacetylase inhibitor trichostatin A. This mRNA and protein expression analysis has provided new insights into the complex molecular pharmacology of 17AAG and suggested new genes and proteins that may be involved in response to the drug or be potential biomarkers of drug action. [Cancer Res 2007;67(7):3239-53]

Antitumor activity and molecular effects of the novel heat shock protein 90 inhibitor, IPI-504, in pancreatic cancer

“…8 In this study, we were unable to detect any alteration in genes coding for known Hsp90 client proteins including c-Raf-1, ErbB2, Akt, and cyclin-dependent kinase 4. Similarly, other investigators have found these phenomena in other cancer types (18,19). Interestingly, when we compared our results with a recently published study in ovarian cancer, we found that only the 70 kDa heat shock protein isoforms and eukaryotic translation initiation factor 3 matched between these two tumor types.…”

Inhibition of the heat shock protein 90 molecular chaperone in vitro and in vivo by novel, synthetic, potent resorcinylic pyrazole/isoxazole amide analogues

“…HSP27 was also induced after treatment with VER-49009 and VER-50589. We previously reported up-regulation of HSP27 in other cell lines and also in tumor tissues obtained from patients receiving 17-AAG in a phase I clinical trial at our institution (52). Both HSP72 and HSP27 have cytoprotective roles (49), and the induction of these chaperones and stress proteins may reduce the apoptotic response to HSP90 inhibitors.…”

“…Using proteomic analysis, we discovered that expression of the protein arginine methyltransferase PRMT5 was decreased by 17-AAG in human cancer cell lines (52). PRMT5 was shown to be a novel HSP90-binding partner and potential client protein.…”

“…VER-49009 and VER-50589 caused depletion of PRMT5 in human cancer cells. Because PRMT5 methylates proteins, including histones, and negatively regulates expression of the ST7 and NM23 tumor suppressor genes (59), it has been speculated that depletion of PRMT5 may contribute to the antitumor effects of HSP90 inhibition (52).…”

Molecular basis for the actions of Hsp90 inhibitors and cancer therapy

“…38 17-AAG decreases a group of Myc-regulated mRNAs and increases the mRNA expression of Hsp90b, Hsp72, Hsp70, Hsp47 and Hsp27. 39 The major molecular chaperones Hsp90, Hsp70 and Hsp60 interact with newly synthesized polypeptides, and maintain the proteins in unfolded states that are suitable for translocation across the membrane. The nuclear translocation of heparanase is abolished by GA and 17-AAG in HL-60 cells, indicating that Hsp90 is involved in the nuclear translocation of heparanase.…”