ObjectiveTo explore the antitumor effect of tumor vaccine fused from dendritic cells (DC) and Walker-256 cancer cells on implanted liver cancer in rats and the related mechanism of inhibition for tumor angiogenesis. MethodsWalker-256 cancer cells and mature DC were fused by 50% polyethylene glycol method for preparation of DC-Walker-256 fusion vaccines. Implanted liver cancer models were established through operations on healthy male SD rats at the age of 6－8 weeks. All the rats were divided into four groups, and rats in each group were injected subcutanely with fusion vaccine (group), mixed cultured cells (group), simple DC (group), and PBS (blank control group), respectively. On 28 d after making model, the rats were put to death, the tumor was observed and pathological essays were prepared. All rats’ spleens were collected and prepared into lymphocyte to detect antigenic specificity cytotoxic T lymphocyte (CTL) by enzymelinked immunosorbent spot (ELISPOT) method. The expressions of VEGF, ANG-1, ANG-2, and MVD were detected by immunohistochemistry. ResultsThe numbers of rats survived in the fusion vaccine group, mixed culture cells group, simple DC group, and blank control group was 8, 5, 6, and 3, respectively. The rats in the other three groups except for fusion vaccine group were manifested as inaction, anorexia, and gloomy fur in some degree as well as ascites. The tumorigenesis was found in all survival rats except for two in the fusion vaccine group. The weight of liver tumors of rats in the fusion vaccine group 〔(32.4±9.2) g〕 was significantly lighter than that in the mixed culture cells group 〔(67.3±5.1) g, P=0.031〕, simple DC group 〔(75.0±8.3) g, P=0.019〕, and blank control group 〔(86.6±10.5) g, P=0.008〕, respectively. The number of tumorspecific CTL of rats in the fusion vaccine group was also significantly higher than that in the other three groups (P=0.019, P=0.025, and P=0.001, respectively). The MVD of tumor tissue in the fusion vaccine group was (24.12±2.32) vessels/HP, which was significantly lower than that in the mixed culture cells group 〔(40.34±1.29) vessels/HP, P=0.025〕, simple DC group 〔(42.36±3.16) vessels/HP, P=0.035〕, and blank control group 〔(56.48±5.16) vessels/HP, P=0.006〕, respectively. The MVD of tumor tissue in the mixed cultured cells group and simple DC group was similar (P=0.165), however, which was significantly lower than that in the blank control group (P=0.040 and P=0.043). The positive rate of VEGFA protein expression was 23.2% in the fusion vaccine group, which was significantly lower than that in the mixed culture cells group (42.5%, P=0.031), simple DC group (61.3%, P=0.019), and blank control group (89.6%, P=0.003), respectively. The positive rate of VEGF-A protein expression in the mixed cultured cells and simple DC groups was similar (P=0.089), however, which was significantly lower than that in the blank control group (P=0.027 and P=0.038). The positive rate of ANG-1 protein expression in the fusion vaccine group (43.2%) was not different from that in the mixed culture cells group (46.3%, P=0.292), simple DC group (51.3%, P=0.183), or blank control group (49.6%, P=0.179), respectively, and the difference of pairwise comparison in latter three groups was not significant (P=0.242, P=0.347, and P=0.182). The positive rate of ANG2 protein expression was 19.2% in the fusion vaccine group, which was significantly lower than that in the mixed culture cells group (62.3%, P=0.007), simple DC group (67.3%, P=0.005), and blank control group (71.6%, P=0.004), respectively, however, the difference of pairwise comparison in latter three groups was not significant (P=0.634, P=0.483, and P=0.379). ConclusionFused vaccine can induce CD8+ CTL aiming at tumor cells and establish the effective antitumor immunity in vivo and also downregulate the level of VEGF and ANG-2 to suppress tumor angiogenesis and thereby achieve the purpose of curing tumor.