Login to Access Video or Poster Abstract: MP44-19
Sources of Funding: none

Introduction

Gemcitabine and cisplatin chemotherapy (GC) is the current standard regimen for locally advanced and metastatic bladder cancer (BC). Despite a relatively high initial response rate, some cases do not regress (intrinsic resistance) and the remaining cases often show regrowth after initial shrinkage (acquired resistance). To identify novel therapeutic agents for overcoming these resistances, we applied a high-throughput screening of chemicals administered in combination with GC.

Methods

As a high-throughput screening, 2100 compounds were administered alone or in combination with GC to human BC cell lines (J82, UMUC-3). Cell viability was determined after 3-day incubation and chemicals that enhanced inhibitory effect of GC were screened. The in vivo effect of disulfiram (DSF) was studied in UMUC-3 cell xenografts, and western blot, immunofluorescence, induced coupled plasma spectrometry and measurement of reactive oxygen species (ROS) were done in vitro for mechanistic exploration.

Results

The initial screening identified 26 compounds and further validation narrowed them into the most synergistic agent disulfiram, an FDA-approved drug for alcoholism. Combination index assay showed synergistic effects of DSF with cisplatin but not with gemcitabine in J82, UMUC-3, T24, HT1197 and HT1376 cells. Co-administration of DSF significantly increased DNA-platinum adducts by regulating cisplatin efflux transporter ATP7A and enhanced apoptosis by GC treatment in UMUC-3 cells, with significant increase of ROS production. Use of DSF in combination with GC (GCD) significantly inhibited tumor growth of UMUC-3 subcutaneous xenograft on athymic mice (by 39% compared with GC alone, p = 0.02). GCD regimen was as tolerable as GC and no significant differences were observed in body weight of treated mice between the two regimens.

Conclusions

Repositioning of DSF to a chemotherapy sensitizer is a promising treatment strategy, which can be translated rapidly in the future.

Funding

none