Abstract: AIM: To investigate the sensitivity of hyperthermia at different temperatures to Gemcitabine and its mechanism.METHODS: Growth inhibiting rates of human pulmonary giant cell carcinoma cells (PLA-801D) in simple thermotherapy group, simple chemotherapy group, combined thermotherapy and chemotherapy group were determined by MTT colorimetric assay. Changes in cell cycle after treatment with hyperthermia at 42 ℃ and Gemcitabine were analyzed by flow cytometry (FCM).RESULTS: Hyperthermia at 42-43 ℃ suppressed the proliferation of PLA-801D cells (P<0.01). However, hyperthermia at 38-41 ℃ stimulated the proliferation of pulmonary carcinoma cells (P<0.01). Hyperthermia in combination with drugs could achieve best results, and the inhibitory rate was positively correlated with the change of temperature (r＝0.9683, P＝0.0001). Cell cycle analysis showed that the amplitude of cell cycles changed greatly after combined thermotherapy and chemotherapy.CONCLUSION: Simple hyperthermia should be applied in combination with chemotherapy. The higher the temperature of hyperthermia is, the better the effect of hyperthermia is, in the controlled range.

Key words: Hyperthermia, Gemcitabine, Human pulmonary carcinoma PLA-801D cell line, Cell cycle, Chemosensitization