Heat-induced cellular damage and tolerance in combination with adriamycin for the PC-3 prostate cancer cell line: relationships with cytotoxicity, reactive oxygen species and heat shock protein 70 expression.

Abstract

To analyze the relationships among the antitumor effect of chemothermotherapy, generation of reactive oxygen species (ROS), and expression of heat shock protein 70 (HSP-70) in the PC-3 prostate cancer cell line. Changes in cell proliferation, cell cycle fractions, intracellular ROS accumulation and HSP-70 expression were examined after thermotherapy of PC-3 cells at 41, 42, 43 and 44 degrees C and/or simultaneous treatment with Adriamycin for 1 h, using the trypan blue dye exclusion method, flow cytometry, fluorescent 2', 7'-dichlorofluorescein (DCF) assay, and Western blot analysis. A significant decrease in the number of viable cells was observed with chemothermotherapy compared with thermotherapy at 42, 43, or 44 degrees C (p<0.05). DNA distribution histograms revealed cell accumulation in the S-G(2)/M phase after thermotherapy at 43 degrees C and after chemothermotherapy at 37, 41, 42 and 43 degrees C. After thermotherapy and chemothermotherapy at 44 degrees C, DNA histograms revealed no accumulation of cells with S-G(2)/M DNA content and cells exhibited a marked loss of viability. A significant increase in DCF production was observed with chemothermotherapy compared with thermotherapy at 42, 43 or 44 degrees C (p<0.05, p<0.01 and p<0.01, respectively). HSP-70 levels increased linearly with increasing temperature. HSP-70 levels after thermotherapy and chemothermotherapy increased with time and reached plateaus at 30 min, whereas the level after thermotherapy at 44 degrees C decreased at 60 min. In conclusion, one possible synergism in cytotoxic effects of chemothermotherapy and Adriamycin could be evaluated by the relationship between ROS accumulation and HSP-70 expression in the PC-3 prostate cancer cell line.