RESUMEN
This in vitro feasibility study has assessed a number of techniques and their applicability when looking at the role of multidrug resistance (MDR) in solid tumours. Fresh tumour material was obtained from 34 patients, (11 previously treated, 23 untreated) with ovarian adenocarcinoma. Doxorubicin sensitivity was measured using the MTT assay +/- the cyclosporins, Pgp expression was assessed by immunocytochemistry with the MRK-16 MoAb and flow cytometry was used to assess intracellular drug accumulation +/- PSC 833. 85% of samples showed some evidence of modest chemosensitisation by the cyclosporins (median 1.74-fold). We saw a marked variation in the number of Pgp positive cells between patients (1-87%, median 31%). 63% of samples tested showed an enhancement of DNR accumulation in the presence of PSC 833, with a median increase of 7% (sample range 0-29%). The present study highlights some of the technical difficulties encountered when working with fresh tumour material ex vivo. We conclude that screening of patients for their suitability to enter clinical trials incorporating MDR modulating agents is technically demanding, but feasible.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/fisiología , Adenocarcinoma/tratamiento farmacológico , Resistencia a Múltiples Medicamentos/fisiología , Neoplasias Ováricas/tratamiento farmacológico , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/biosíntesis , Adenocarcinoma/metabolismo , Adulto , Anciano , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Ciclosporinas/farmacología , Doxorrubicina/farmacocinética , Doxorrubicina/farmacología , Resistencia a Antineoplásicos , Células Epiteliales/patología , Estudios de Factibilidad , Femenino , Humanos , Persona de Mediana Edad , Neoplasias Ováricas/metabolismo , FenotipoRESUMEN
OBJECTIVES: The objective was to assess the relationship between glutathione content and drug sensitivity with glutathione modulation in ovarian cancer in a pilot study using 31 samples of freshly obtained ovarian tumor material from 26 patients with advanced disease. METHODS: Processed tumor samples were screened to determine the glutathione content using an enzyme recycling assay modified for use in a 96-well plate format. Chemosensitivity testing (MTT assay) was used to assess sensitivity to cisplatin and doxorubicin and modulation using buthionine sulfoximine. Multidrug-resistance-associated protein MRP1 (putative drug-glutathione conjugate transporter) expression was also assessed. RESULTS: There was a significant increase in the tumor cell GSH levels in samples from patients who had received previous chemotherapy (9) versus those from chemotherapy-naïve patients (20), P = 0.005. In vitro chemosensitivity testing with doxorubicin and cisplatin (using LC(50) values, i.e., drug dose causing 50% reduction in cell survival relative to untreated control) failed to show a relationship with glutathione levels. Coincubation of cisplatin and doxorubicin with buthionine sulfoximine resulted in a significant increase in sensitivity to both of these drugs overall (cisplatin, P = 0.05; doxorubicin, P = 0.025), with 20 samples showing sensitization to a drug to which they were previously resistant. MRP1 expression failed to show a correlation with drug sensitivity and glutathione levels. CONCLUSIONS: Our study supports the use of glutathione modulation using agents such as buthionine sulfoximine in patients with heavily pretreated, drug-resistant ovarian cancer.