Experimental studies of rAd-p53 injection by interventional approach for the treatment of rabbit VX2 liver cancer

Abstract

To evaluate the efficacy of recombinant human adenovirus p53 gene therapy (rAd-p53) in the rabbit VX2 liver cancer model using different interventional therapy approach. Thirty New Zealand rabbits implanted with VX2 tumor in the liver were randomized into five groups with six of each. The tumor volumes (V1) were measured by MRI and CT scan 11 days after tumors implanted. The interventional therapy scheme performed as below: intraarterial 0.9% saline solution perfusion in group A, transcatheter arterial embolization with 0.5 ml ultrafluid lipiodol in group B, intraarterial rAd-p53 gene perfusion in group C (1 x 10(6)/VP); intraarterial rAd-p53 gene perfusion (1 x 10(6)/VP) in combination with transcatheter arterial embolization (ultrofluid lipiodol, 0.5 ml) in group D and intratumoral rAd-p53 gene (1 x 10(6)/VP) injection in group E. The tumor volumes (V2) were measured by MRI and CT scan, and the tumor growth ratios were calculated 14 days after interventional procedures. Then all animals were sacrificed. The tumor tissues were explanted for immunohistochemistry to observe the expressions of vascular endothelial cell growth factor (VEGF) and factor VIII. Microvessel density (MVD) of the tumor tissues was assessed by factor VIII immunohistochemical analysis. In addition, apoptotic index was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The tumor volumes before therapy were (79.4+/-8.2), (75.3+/-7.8), (74.6+/-6.6), (78.7+/-9.1), (75.8+/-8.4) mm(3) respectively, without differences found among them (F = 12.248, P = 0.0636). But the tumor volumes after therapy were (564.7+/-96.7), (176.5+/-83.2), (239.6+/-42.8), (159.8+/-58.6), (334.7+/-32.6) mm(3) respectively (F = 24.537, P = 0.0218). The tumor growth ratios were 6.9, 2.6, 3.1, 1.6 and 4.1 respectively. The mean apoptosis index were 12.0%+/-1.1%, 14.5%+/-2.1%, 17.6%+/-2.3%, 18.6%+/-2.3% and 19.6%+/-2.5% respectively. with significant differences in group E in comparison with the other four groups. Mean positive ratio of VEGF was 50.0%, 83.3%, 83.3%, 50.0% and 50.0% respectively, with significant differences observed in group B and group C compared with the other three groups (F = 7.84, P = 0.019). The differences of VIII factor positive expression ratio among each group were significant (F = 0.854, P = 0.018). Statistical analysis showed a positive correlation between the expression of VEGF and MVD (r = 2.400, P = 0.0233). The rAd-p53 has effective treatment outcomes in VX2 rabbit liver cancer, and intra-arterial rAd-p53 gene perfusion in combination with transcatheter arterial embolization is the best approach in comparison with intra-arterial rAd-p53 gene perfusion, transcatheter arterial embolization and intratumoral rAd-p53 gene injection alone.