Immunohistochemical expression of P-glycoprotein in the rat urinary bladder and the effect of verapamil on intravesical chemotherapy

A chemosensitivity test for superficial bladder cancer based on three-dimensional culture of tumour spheroids

OBJECTIVES

Three-dimensional (3D) spheroids are a good model for studying in vitro chemosensitivity because they reproduce unicellular and multicellular mechanisms of drug resistance. We aimed to develop a chemosensitivity test for intravesical drugs and to also verify the effects of verapamil (VPM) and ciprofloxacin (CIPRO).

METHODS

Cold cup biopsies from 40 superficial bladder tumours were taken, fragmented, and left in culture. 3D-spheroids were obtained and transferred into a 24 multiwell dish containing (1) wells 1-3: 1 mg/ml epirubicin (EPI); (2) 4-6: 1 mg/ml EPI+0.5 mg/ml VPM; (3) 7-9: 1 mg/ml adriamycin (ADR); (4) 10-12: 1 mg/ml thiotepa (THIO); (5) 13-15: 1 mg/ml mitomycin C (MMC); (6) 16-18: 1mg/ml EPI+0.2 mg/ml CIPRO; (7) 19-21: 0.2 mg/ml CIPRO; (8) 22-24: controls. Sensitivity was calculated by using the trypan blue assay.

RESULTS

Evaluability of clinically relevant tests (G1-G2 lesions) was 84% (21 of 25 patients). MMC was the best agent (p<0.001) with mean sensitivity being 50%, followed by THIO (37%), EPI (7%), and ADR (3%). We found no significant difference (p=0.370) between CIPRO and the control, or between EPI+CIPRO and EPI alone (p=0.550). VPM markedly enhanced sensitivity to EPI compared with EPI alone (97% vs. 7%, p<0.001).

CONCLUSIONS

Our assay allows determining sensitivity to several drugs in superficial bladder tumours. It might be used in clinical practice to select the best drug for each patient. It also has experimental utility in investigating the effect of new drugs or combinations. VPM reverted resistance to EPI. CIPRO showed no effect on bladder tumour spheroids.