Comparison of heat shock gene expression in mild hyperthermia-sensitive human prostatic carcinoma cells and heat-resistant human breast carcinoma cells

1. 1.|While human breast carcinoma (MCF-7) cells were resistant to heat shock, human prostatic carcinoma (DUT-145 and PC-3) cells were relatively sensitive to mild hyperthermia. For example, survival of both prostatic carcinoma cells or that of breast carcinoma cells was 10 or 93%, respectively, after heating at 41°C for 24h. 2. 2.|We investigated whether or not heat shock gene expression might be responsible for these differences in thermal sensitivity. 3. 3.|It was observed that transcriptional activation of heat shock genes was induced by heating at 41°C in all three cell lines. Studies from the gel mobility shift assay demonstrated the formation of heat shock factor and heat shock element (HSF-HSE) complex during heating at 41°C for 2 h in both MCF-7 and DUT-145 cell lines. 4. 4.|In addition, Northern blots and polyacrylamide gel electrophoresis demonstrated expression of heat shock genes, along with the synthesis of their proteins, particularly 68 kDa heat shock protein in all three cell lines. 5. 5.|These results demonstrate that differences in thermal sensitivity to mild hyperthermia are not due to differential heat shock gene expression.