Water as a tumoricidal agent in bladder cancer - In vitro studies in parental and resistant cell lines

Objective: Water is widely used as a tumoricidal agent during transurethral resection of bladder tumour (TURBT), Despite this, recurrences are common. One possible explanation may be that while the parental bladder cancer cel ls are sensitive to water, their multidrug resistant (MDR) clones which occ ur commonly, may be resistant to it. If so, is this a preserve of the MDR p henotype or do other mechanisms confer resistance to water? Methods: The pa rental human urothelial cancer cell lines (MGHU-1 and RT112) and their drug -resistant variants (MDR and non-MDR) were exposed to short pulses of water . The MDR status of these cells was verified using confocal microscopy to d etect intracellular accumulation of fluorescent drug (epirubicin). A clonog enic assay was used to establish tumoricidal efficacy on cells in suspensio n. A thiozolyl blue (MTT) assay was used on adherent cells to assess the re sidual viable biomass, Results: In the MDR clone of cells, colony counts we re reduced by 20% after treatment with water as compared to a 60% reduction in the parental cell line. There was a similar reduction in colony counts between the parental RT 112 and its non-MDR cisplatin resistant variant. Co nclusion: Water is less effective on MDR cells. Resistance to water may be a function of the MDR phenotype.