An in vitro and in vivo study of the combination of the heat shock protein inhibitor 17-allylamino-17-demethoxygeldanamycin and carboplatin in human ovarian cancer models.
OBJECTIVE
To study the interactions of the heat shock protein 90 (HSP90) inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) and carboplatin in vitro and in vivo.


METHODS
The combination of 17-AAG and carboplatin on the growth inhibition of A2780, SKOV-3, IGROV-1 and HX62 human ovarian cancer cells was studied in vitro by MTT assays. The effect of the sequence of administration of both drugs was further investigated in A2780 cells by sulforhodamine B assays. The ability of 17-AAG to deplete HSP90 client proteins either alone or in combination with carboplatin was evaluated by western blotting. Tumor concentrations of 17-AAG and carboplatin alone or in combination in vivo were determined by validated liquid chromatography with ultraviolet detection and atomic absorption spectroscopy methods. The growth inhibitory effects of 17-AAG, carboplatin and the combination were studied in the A2780 xenograft model.


RESULTS
The combination index (CI) at fu(0.5) for 17-AAG plus carboplatin was 0.97 (+/-0.12 SD) when A2780 cells were exposed to carboplatin followed by 17-AAG indicating additivity. The addition of carboplatin did not alter the ability of 17-AAG to cause C-RAF, CDK4 and p-AKT depletion or HSP70 induction. Tumor 17-AAG and carboplatin concentrations were not significantly different in the single agent and combination arms. Tumor weights relative to controls on day 6 (T/C) were 67% for the carboplatin, 64% for the 17-AAG and 22% for the combination.


CONCLUSIONS
In the specified sequences of drug exposure, 17-AAG and carboplatin have additive growth inhibitory effects in vitro and beneficial effects were seen with the combination in vivo. These findings form the basis for the possible evaluation of 17-AAG and carboplatin in a clinical trial.
Banerji
Udai
U
Cancer Research UK Centre for Cancer Therapeutics, Haddow Laboratories, The Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, UK.
Sain
Nivedita
N
Sharp
Swee Y
SY
Valenti
Melanie
M
Asad
Yasmin
Y
Ruddle
Ruth
R
Raynaud
Florence
F
Walton
Michael
M
Eccles
Suzanne A
SA
Judson
Ian
I
Jackman
Ann L
AL
Workman
Paul
P
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000378:metabolism; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D016227:Benzoquinones / Q000008:administration & dosage; D015153:Blotting, Western; D016190:Carboplatin / Q000008:administration & dosage / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000008:administration & dosage; D051379:Mice; D008819:Mice, Nude; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D012235:Rhodamines; D013778:Tetrazolium Salts; D013844:Thiazoles; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D012235:Rhodamines; D013778:Tetrazolium Salts; D013844:Thiazoles; C022027:lissamine rhodamine B; C112765:tanespimycin; D016190:Carboplatin; C022616:thiazolyl blue