[Inhibitive effect of polypeptide extract from scorpion venom on repopulation in H22 tumor cell during chemotherapy]

To observe the inhabitive effect and mechanism of polypeptide extract from scorpion venom (PESV) on repopulation in H22 tumor cell during chemotherapy.

H22 tumor cells were injected into 96 mice subcutaneously, then mice were divided into 4 groups radomly: Model, low-dose-PESV, high-dose-PESV, and control. Reppulation model was established by 5-Fu treating mice with H22. Four groups was treated differently, 6 mice of each group was sacrificed every 7 days, measured tumor volume twice one week. The expression of vascular endothelial growth factor (VEGF), proliferating cell nuclear antigen (PCNA), CD105 microvessel density (CD105-MVD) and platelet derived growth factor (PDGF) in H22 tumor issue was observed by using immunohistochemistry and grey analysis, the relation of VEGF and MVD was affirmed by correlation analysis.

In control group tumor volume of H22 increased quickly in 13-24 day, and all mice died before 27 day. In model tumor volume increased quickly before 17, in 17-22 day slowly, after 22 day quickly again, and all the mice died before 31 day. In low and high dose PESV, tumor volume added slowly, and only in 17 day there was significant difference between these two groups. Immunohistochemistry showed, PCNA expression of model group in 31 day was higher than in 21, 28 day, the expression level of high and low PESV group was lower than model group all the time, only in 17 day there was significant difference between high and low PESV group. Immunohistochemitry showed, compared with high and low dose PESV group, CD105-MVD of model group was higher in 21, 28 day (P < 0.05) and in 35 day (P < 0.01), and no difference was found between high and low dose PESV. VEGF expression of model group in 35 day was higher than in 21, 28 day (P < 0.01), and model group higher than high and low dose PESV in 21, 28, 35 day. The expression of PDGF in model decreased gradually, in high and low dose PESV, the expression was lowest in 21 day. In day 35 high dose PESV higher than low dose PESV. There was positive correlation (r = 0.669) between VEGF expression and CD105-MVD.

PESV can inhabit repopulation of H22 tumor cell during chemotherapy, and the mechanism maybe is through anti-angiogenesis and nomalizing tumor vessels.