17-Allylamino-17-demethoxygeldanamycin induces the degradation of androgen receptor and HER-2/neu and inhibits the growth of prostate cancer xenografts Journal Article

Authors: Solit, D. B.; Zheng, F. F.; Drobnjak, M.; M√ľnster, P. N.; Higgins, B.; Verbel, D.; Heller, G.; Tong, W.; Cordon-Cardo, C.; Agus, D. B.; Scher, H. I.; Rosen, N.
Article Title: 17-Allylamino-17-demethoxygeldanamycin induces the degradation of androgen receptor and HER-2/neu and inhibits the growth of prostate cancer xenografts
Abstract: Purpose: Ansamycin antibiotics, including 17-allylamino-17-demethoxygeldanamycin (17-AAG), inhibit Hsp90 function and cause the selective degradation of signaling proteins that require this chaperone for folding. Because mutations in the androgen receptor (AR) and activation of HER2 and Akt may account, in part, for prostate cancer progression after castration or treatment with anti-androgens, we sought to determine whether an inhibitor of Hsp90 function could degrade these Hsp90 client proteins and inhibit the growth of prostate cancer xenografts with an acceptable therapeutic index. Experimental Design: The effect of 17-AAG on the expression of Hsp90 regulated signaling proteins in prostate cancer cells and xenografts was determined. The pharmacodynamics of target protein degradation was associated with the toxicology and antitumor activity of the drug. Results: 17-AAG caused the degradation of HER2, Akt, and both mutant and wild-type AR and the retinoblastoma-dependent G1 growth arrest of prostate cancer cells. At nontoxic doses, 17-AAG caused a dose-dependent decline in AR, HER2, and Akt expression in prostate cancer xenografts. This decline was rapid, with a 97% loss of HER2 and an 80% loss of AR expression at 4 h. 17-AAG treatment at doses sufficient to induce AR, HER2, and Akt degradation resulted in the dose-dependent inhibition of androgen-dependent and -independent prostate cancer xenograft growth without toxicity. Conclusions: These data demonstrate that, at a tolerable dose, inhibition of Hsp90 function by 17-AAG results in a marked reduction in HER2, AR, and Akt expression and inhibition of prostate tumor growth in mice. These results suggest that this drug may represent a new strategy for the treatment of prostate cancer.
Keywords: protein expression; treatment outcome; unclassified drug; human cell; animals; mice; cell division; protein degradation; down-regulation; antineoplastic activity; tumor xenograft; tumor cells, cultured; xenograft model antitumor assays; prostate cancer; prostate-specific antigen; prostatic neoplasms; mice, nude; heat shock protein 90; hsp90 heat-shock proteins; target cell; androgen receptor; receptor, erbb-2; neoplasm transplantation; castration; receptors, androgen; protein folding; tumor growth; retinoblastoma protein; ligand binding; g1 phase; androgens; benzoquinones; lactams, macrocyclic; enzyme induction; rifabutin; growth inhibition; geldanamycin; oncogene neu; ansamycin derivative; receptor, erbb-3; 17 allylamino 17 demethoxygeldanamycin; humans; human; male; female; priority journal; article
Journal Title: Clinical Cancer Research
Volume: 8
Issue: 5
ISSN: 1078-0432
Publisher: American Association for Cancer Research  
Date Published: 2002-01-01
Start Page: 986
End Page: 993
Language: English
PUBMED: 12006510
PROVIDER: scopus
Notes: Export Date: 14 November 2014 -- Source: Scopus