Cisplatin sensitization by concurrent mild hyperthermia in parental and mutant cell lines deficient in homologous recombination and non-homologous endjoining repair

The effect of mild hyperthermia on cisplatin sensitization was examined in two cell line pairs, CHO parental AA8 and irs ISF, an XRCC3 mutant (deficient in homologous recombination repair), and mouse parental MEF and knockout Ku80 mutants (deficient in non-homologous endjoining repair). The results showed that mild hyperthermia 40, 41 and 42°C given concurrently with cisplatin treatment caused significant sensitization. The degree of sensitization was comparable for the parental and mutant lines, indicating that these repair pathways were likely not involved in cisplatin thermal sensitization. The shorter concurrent treatments cause a larger sensitization than the longer treatments. The reasons for this are not clear, but thermotolerance may be a factor.