HEAT-SHOCK PROTEIN EXPRESSION IN TESTIS AND BLADDER-CANCER CELL-LINESEXHIBITING DIFFERENTIAL SENSITIVITY TO HEAT

Testis cancer cells are more sensitive than bladder and most other can cer cells to chemotherapeutic drugs both in the clinic and ipl vitro. In this study we show that they are also more sensitive than bladder c ancer cells to heat. Since heat and drug sensitivity may be related to the ability of a cell to mount a stress response, constitutive and in duced levels of heat shock proteins (HSPs) in three testis and three b ladder human cancer cell lines were measured using Western blotting an d scanning densitometry. No correlation between constitutive levels of HSP 90 or HSP 73/72 and cellular heat sensitivity was found. However, HSP 27 levels were much lower in the testis tumour cells, suggesting that low HSP 27 expression might contribute to heat sensitivity. Prote in synthesis studies using [S-35]methionine indicated that, for the sa me heat shocks, the kinetics of synthesis and decay of HSP 90 and HSP 73/72 in 833K (the most heat sensitive testis cells) was similar to or greater than that in HT1376 (the most heat-resistant bladder cells). Both 833K and HT1376 developed thermotolerance, and this followed an i ncrease in synthesis of HSPs. These results indicate that, although th ere are differences in the constitutive levels of HSPs between testis and bladder cancer cells, both cell types are capable of mounting an i nduced heat shock response and can develop a similar degree of thermot olerance.