The combined effects of high-energy shock waves and cytostatic drugs or cytokines on human bladder cancer cells

Abstract

The effects of shock waves generated by an experimental Siemens lithotripter in combination with cytostatic drugs or cytokines on several bladder cancer cell lines were examined in vitro. Proliferation after treatment was determined with the 3-4,5-dimethylthiazol-2,5 diphenyl tetrazolium bromide assay. Dose enhancement ratios were calculated for each drug and each shock wave application mode in order to characterise the sensitising effect of shock wave pretreatment. The influence of the time between shock wave and drug treatment as well as the effects of different sequences of shock wave and drug treatment or concomitant treatment were assessed for selected combinations of cell lines and drugs. It was found that shock wave treatment could render certain cell lines more susceptible to subsequent cis-platinum, mitomycin C or actinomycin D incubation. Cell lines sensitive to tumour necrosis factor alpha or interferon alpha were further sensitised to these cytokines by shock wave pretreatment. The enhanced sensitivity to cis-platinum and actinomycin D decreased rapidly during the first hours after shock wave treatment. The antiproliferative effect was most pronounced after concomitant shock wave and drug treatment. The sensitisation to interferon alpha diminishes more slowly after shock wave exposure. From the results presented in this study it is concluded that transient shock wave-induced permeabilisation of cell membrane not only enhances drug efficiency, but also causes damage to cell organelles and alterations in cellular metabolism.