Cisplatin abrogates the geldanamycin-induced heat shock response.
Benzoquinone ansamycin antibiotics such as geldanamycin (GA) bind to the NH(2)-terminal ATP-binding domain of heat shock protein (Hsp) 90 and inhibit its chaperone functions. Despite in vitro and in vivo studies indicating promising antitumor activity, derivatives of GA, including 17-allylaminogeldanamycin (17-AAG), have shown little clinical efficacy as single agents. Thus, combination studies of 17-AAG and several cancer chemotherapeutics, including cisplatin (CDDP), have begun. In colony-forming assays, the combination of CDDP and GA or 17-AAG was synergistic and caused increased apoptosis compared with each agent alone. One measurable response that results from treatment with Hsp90-targeted agents is the induction of a heat shock factor-1 (HSF-1) heat shock response. Treatment with GA + CDDP revealed that CDDP suppresses up-regulation of HSF-1 transcription, causing decreased levels of stress-inducible proteins such as Hsp27 and Hsp70. However, CDDP treatment did not prevent trimerization and nuclear localization of HSF-1 but inhibited DNA binding of HSF-1 as shown by chromatin immunoprecipitation. Melphalan, but not camptothecin, caused similar inhibition of GA-induced HSF-1-mediated Hsp70 up-regulation. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt cell survival assays revealed that deletion of Hsp70 caused increased sensitivity to GA (Hsp70(+/+) IC(50) = 63.7 +/- 14.9 nmol/L and Hsp70(-/-) IC(50) = 4.3 +/- 2.9 nmol/L), which confirmed that a stress response plays a critical role in decreasing GA sensitivity. Our results suggest that the synergy of GA + CDDP is due, in part, to CDDP-mediated abrogation of the heat shock response through inhibition of HSF-1 activity. Clinical modulation of the HSF-1-mediated heat shock response may enhance the efficacy of Hsp90-directed therapy.
Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Andrea K
AK
McCollum
Kara B
KB
Lukasiewicz
Cynthia J
CJ
Teneyck
Wilma L
WL
Lingle
David O
DO
Toft
Charles
C
Erlichman
D000970:Antineoplastic Agents / Q000494:pharmacology*; D016227:Benzoquinones / Q000494:pharmacology*; D002166:Camptothecin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000187:drug effects*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008558:Melphalan / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D000970:Antineoplastic Agents; D016227:Benzoquinones; D002843:Chromatin; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D047029:Lactams, Macrocyclic; D014157:Transcription Factors; D002945:Cisplatin; D008558:Melphalan; D002166:Camptothecin; C001277:geldanamycin