Testis tumour cells are more sensitive than most other types of cancer cell to heat, radiation and chemotherapeutic drugs, both in the clinic and in vitro. Since heat shock proteins (HSP) can protect cells from the cytotoxic effects of stress, we studied their role in the sensitivity of testis tumour cells to the frequently used cancer chemotherapeutic drugs, cisplatin and doxorubicin. Clonogenic assays of 3 testis tumour cell lines (833K, GCT27, GH) and 3 bladder cancer cell lines (RT112, HT1376, MGH-U1) following a 1 h exposure to the two drugs confirmed that the testis tumour cell lines were inherently more sensitive. Having shown previously that heat shock proteins were upregulated in both cell types following a heat shock, in this study no induction of HSP was seen following treatment for 1 h with cisplatin or doxorubicin (at concentrations reducing colony forming ability by 50%) in either cell type. In contrast, chronic exposure to cisplatin (at concentrations on the threshold of cytotoxicity), but not doxorubicin, resulted in upregulation of HSP 27, but not HSP73/72, in both cell types. Testis and bladder cancer cells with heat-induced increases in HSP were thermotolerant, and this was associated with increased resistance to doxorubicin, but not cisplatin.

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