The Effect Of HIFU Combined With Ultrasound Microbubbles Encapsulating Herpes Simplex Virus Thymidine Kinase Gene (HSV1-TK) On Angiogenesis In The Rabbit VX2 Tumor

BackgroundHepatocellular carcinoma is the third common malignant tumor, whose mortality rate is only inferior to the stomach cancer and esophageal cancer. The majority of patients have lost surgery opportunity because of the partial infiltration and distant metastasis. Recent years, the non-invasive,partial high temperature treatment technology——High intensity focused ultrasound(HIFU) developed rapidly, which could destroy the tumor organization but not influence periphery normal tissue. But because of the energy attenuation, costal arch occlusion, liver movement with respiration shift and other factors, the remaining cancer cell often have a chance of survival. Therefore seeking for a new treatment method to destroy residual cancer cells as much as possible will be the key point to enhance the efficacy of HIFU treatment. ObjectiveTo observe the influence of the combined treatment of HIFU and ultrasound microbubbles encapsulating herpes simplex virus thymidine kinase gene(HSV1-TK) on the expression of HIF-1α,vascular endothelial growth factor(VEGF)and microvessel density(MVD) in rabbit liver vx2 cancer and discuss the treatment mechanism.MethodsA total of 40 New Zealand White rabbits were implanted with liver vx2 tumors in liver for two weeks. According to stochastic tables, 40 New Zealand white rabbits were divided into four groups as follows: control group (A group, n=10); HIFU group (B group, n=10); Ultrasound- micro bubble encapsulating herpes simplex virus thymidine kinase gene group(C group, n=10); HIFU combine with ultrasound-microbubble encapsulating herpes simplex virus thymidine kinase gene group(D group, n=10). Two weeks after treatment,40 rabbits were killed to study the growing condition of the primary tumors. Immunohito-chemical staining was performed to evaluate HIF-1α,vascular endothelial growth factor(VEGF) and microvessel density(MVD). Real-time polymerase chain reaction was performed to examine HIF-1αand VEGF mRNA levels.ResultsTwo weeks after reatment the tumor volumes in group D were lower than those in other groups(p<0.05); The results of Real-time polymerase chain reaction,Western-blot and Immunohito- chemical staining show that the expression of HIF-1α,VEGF were significantly lower in group B and C than those in A group(p﹤0.05). The expression of HIF-1α,VEGF were significantly lower in group D compared with other groups(p<0.05). The MVD of residual cancer in group B and C[(40.33±4.73)/mm2, (41.00±3.61)/ mm2,respectly] were significantly lower than that in group A[(68.67±9.91)/ mm2](p<0.05). The MVD of residual cancer was significantly lower in group D compared with group A,B and C(P<0.05).ConclusionThe combined treatment of HIFU and ultrasound microbubbles encapsulating herpes simplex virus thymidine kinase gene (HSV1-TK) could suppress the growth of tumors, decrease the expression level of HIF-1α, VEGF in residual tumors, enhance the effect of the HIFU.