Wu Lun, Zhou Wenbo, Zhou Shiji, Liu Chang'an, Li Shengwei
Zhonghua Gan Zang Bing Za Zhi. 2015 Feb;23(2):112-7. doi: 10.3760/cma.j.issn.1007-3418.2015.02.008.
To investigate the dynamic features of angiogenesis in residual tumors after high intensity focused ultrasound (HIFU),and to determine the temporal effect and mechanism of hypoxia inducible factor-2 alpha (HIF-2a) in the angiogenic process of residual tumors.
Xenograft tumors of HepG2 cells were generated by subcutaneously inoculating athymic BALB/c nu/nu mice with the hepatoma cells.About 30 days after inoculation,all mice (except in the control group) were treated by HIFU and assigned randomly to the following 7 groups according to various time intervals post-treatment:1st,3rd,5th day and 1st,2nd,3rd,4th week when the residual tumor tissues were obtained from the experimental groups.Protein levels of HIF-2a and vascular growth factor A (VEGF-A) were quantified by immunohistochemistry and western blotting,and mRNA levels were measured by (real-time quantitative) qPCR. Microvascular density (MVD) was calculated by counting the CD31-positive vascular endothelial cells identified by means of an immunohistochemical staining method.
Compared with results from the control group,the protein and mRNA levels of HIF-2a expression reached the highest level in the experimental mice at the 2nd week (P=0.000 and P < 0.01 respectively),and were decreased thereafter(3rd week and 4th week, P=0.000 and P < 0.05).VEGF-A expression in the residual tumor tissues group that received HIFU was significantly decreased,compared with the control group,at all time points uPto 1 week (all P=0.000 and P < 0.01),but the levels increased compared to controls in the 2nd through 4th week (all P=0.000, P < 0.05). Similar results were obtained for MVD.
HIFU treatment can inhibit angiogenesis in residual hepatoma tissues in the short-term (1 to 2 weeks post-treatment) in mice with hepatocellular carcinoma,but can promote angiogenesis overtime (2 to 4 weeks post-treatment); the angiogenic process may involve the HIF-2α/VEGFA pathway.
研究高强度聚焦超声（HIFU）治疗后残留肿瘤血管生成的动态特征，确定缺氧诱导因子-2α（HIF-2α）在残留肿瘤血管生成过程中的时效作用及机制。
将肝癌细胞皮下接种于无胸腺BALB/c nu/nu小鼠，建立HepG2细胞异种移植瘤模型。接种约30天后，除对照组外，所有小鼠均接受HIFU治疗，并根据治疗后的不同时间间隔随机分为以下7组：治疗后第1天、第3天、第5天以及第1周、第2周、第3周、第4周，从实验组获取残留肿瘤组织。采用免疫组织化学和蛋白质印迹法对HIF-2α和血管生长因子A（VEGF-A）的蛋白水平进行定量分析，通过（实时定量）qPCR检测mRNA水平。采用免疫组织化学染色法计数CD31阳性血管内皮细胞，计算微血管密度（MVD）。
与对照组相比，实验小鼠中HIF-2α表达的蛋白和mRNA水平在第2周达到最高（分别为P = 0.000和P < 0.01），此后下降（第3周和第4周，P = 0.000和P < 0.05）。接受HIFU治疗的残留肿瘤组织组中，VEGF-A表达在治疗后1周内的所有时间点均显著低于对照组（均为P = 0.000和P < 0.01），但在第2周至第4周与对照组相比水平升高（均为P = 0.000，P < 0.05）。MVD也得到了类似结果。
HIFU治疗可在短期内（治疗后1至2周）抑制肝癌小鼠残留肝癌组织中的血管生成，但长期（治疗后2至4周）可促进血管生成；血管生成过程可能涉及HIF-2α/VEGFA通路。
