Cryotherapy promotes glioma cells apoptosis

Abstract

Objective To explore the mechanism of apoptosis after cryotherapy on tumors. Methods (1) GL261 glioma cells (1×107 cell/10 μL) were injected into the subcutaneous one of C57 mice to establish tumor-bearing mouse models; when the diameter of tumor reached to 15-20 mm, the mice were randomly divided into cryogenic treatment group and sham-operated group (n=10); mice in the cryogenic treatment group were given surgical cryotherapy, while those in the sham-operated group only performed surgery without cryotherapy. TUNEL was used to detect the cell apoptosis in glioma tissues 12 and 24 h after operation; and Western blotting was employed to detect the protein expressions of pro-caspase-8, pro-caspase-9 and poly-ADP-ribose polymerase (PARP). (2) GL261 glioma cells were divided into control group and one time cryogenic release group, and DMEM and one time of cryogenic release were given to the two groups, respectively; 12 h after the treatment, TUNEL was used to observe the cell apoptosis in glioma tissues, and Western blotting was employed to detect the protein expressions. Results (1) TUNEL indicated that the cells in the S1 region of the glioma tissues from mice in the cryogenic treatment group were uniformly died; significant apoptosis was noted in cells of the S2 region at 12 h after treatment; while, 24 h after treatment, S1 region still showed uniform necrosis, S2 region showed apoptotic regression, and S3 region showed new apoptosis at the target side. Western blotting indicated that pro-caspase-9 and PARP protein expressions at the S2 region were signficantly decreased as compared with those at the S1, S3 and S4 regions (P<0.05), and pro-caspase-8 protein expression at the S3 region were signficantly reduced as compared with those at the S1, S2 and S4 regions in the cryogenic treatment group (P<0.05). (2) TUNEL showed that significantly increased GL261 glioma cell apoptosis rate was noted in the one time cryogenic release group as compared with that in the control group (P<0.05); Western blotting indicated that as compared with the control group, the cryogenic release group had significantly decreased pro-caspase-8 and pro-caspase-9 expressions (P< 0.05). Conclusion Cryogenic release or substances released from tumor tissues after cryoablation shows an effect on promoting apoptosis. Key words: Cryotherapy; Cryogenic release; Glioma; Apoptosis