[Effect of cryotherapy and 5-fluorouracil on apoptosis of G422 glioma cells].

Background & Objective: It was unknown whether the combination of cryotherapy and 5-fluorouracil (5-FU) could produce a synergistic effect, though both of them could induce apoptosis of glioma cells. The aim of this study was to observe the effect of cryotherapy and 5-fluorouracil on apoptosis of G422 glioma cells and to investigate the potential mechanism.

Methods: (1)Experimental mice models with G422 glioma were established. Cryotherapy (-180 degrees C,90s),chemotherapy (5-FU, 18 mg/kg), and cryochemotherapy were performed on them,respectively.(2)TUNEL was used to determine the apoptosis of glioma cells in each group at different time points.(3)The expression of the p53 and the HSP90alpha gene of the frozen glioma were analyzed by immunohistochemical staining.

Results: Cryotherapy or 5-FU induced apoptosis of G422 glioma cells, while the combination of cryotherapy and 5-FU remarkably increased the apoptosis rate. The numbers of apoptotic cells of combination group were 30.6+/-11.7, 86.4+/-21.5, 128.1+/-4.1, 237.0+/-30.1, 72.8+/-23.0 at 6h, 12h, 24h, 48h, 72h after cryochemotherapy, respectively, which were significantly higher than those of other groups. There was no expression of HSP90alpha and p53 in the center of freezing area. The p53 and the HSP90alpha proteins increased obviously in the periphery area especially at 48h after freezing compared with control group [(73.1+/-9.3)% vs (60.6+/-9.9)%, (35.6+/-6.6)% vs (13.7+/-6.5)%](P< 0.01). The expression of p53 was positively correlated with expression of HSP90alpha in frozen glioma (r=0.3610, P< 0.01).

Conclusion: Combination of cryotherapy with 5-FU could enhance the apoptosis of G422 glioma cells presumably through modulating the HSP90alpha and p53 expression pattern. Cryochemotherapy showed better effect than that of cryotherapy or chemotherapy alone.