贝伐珠单抗诱导肿瘤血管正常化的时间窗及与紫杉醇联合治疗肺癌荷瘤鼠的实验研究

目的 探讨贝伐珠单抗诱导肿瘤血管正常化的时间窗及贝伐珠单抗联合紫杉醇对小鼠肺腺癌移植瘤的抑瘤效果。方法 选取成功构建的人肺腺癌A549裸鼠皮下移植瘤模型54只，实验分为两部分：第一部分荷瘤小鼠24只随机分为两组：对照组和贝伐珠单抗组各12只，分别腹腔注射生理盐水和贝伐珠单抗5 mg／kg，于给药后选取第1、3、5、8天共4个时间点，每个时间点各3只，测量瘤体体积及裸鼠体质量，采用Western blotting和免疫荧光法分别检测瘤体内血管内皮生长因子（VEGF）水平和微血管密度（MVD）。第二部分小鼠30只随机分为四组：对照组、紫杉醇单药组和贝伐珠单抗单药组各5只及联合组15只。联合组于贝伐珠单抗给药当天及给药后第3、5天各选取5只腹腔注射紫杉醇，紫杉醇和贝伐珠单抗的剂量分别为3 mg／kg和5 mg／kg，于给药后选取第3、7、10、14、17、20天共6个时间点测量瘤体体积，21天后处死裸鼠称取瘤体质量，采用Western blotting和免疫组化法分别检测瘤体VEGF水平和MVD。结果 在第一部分实验中，与对照组相比，贝伐珠单抗组给药后肿瘤的生长得到抑制，以第三天抑制效应最显著，此时瘤体的体积最小，瘤体内VEGF含量表达减少，瘤体MVD也相应减少。在第二部分实验中，与对照组相比，贝伐珠单抗不同时间点联合紫杉醇给药均可显著抑制肿瘤生长，以贝伐珠单抗联合紫杉醇第三天给药组抑制效应更为显著，且瘤体的体积、质量、VEGF含量及MVD均较其他联合给药组少。结论 贝伐珠单抗诱导的血管正常化时间窗可能在给药后第1～3天，在该时间窗内联合紫杉醇可达到最大的抗肿瘤效应。

Experimental study of vascular normalization window for tumor induced by bevacizumab and efficacy of bevacizumab plus paclitaxel in lung cancer-bearing mice

Objective To explore the time window of bevacizumab to normalize the vascular for tumor and analyze the efficacy of bevacizumab plus paclitaxel in lung cancer-bearing mice.Methods Athymic mice bearing A549 xenografts were constructed.The study can be divided into two parts.In first part, 24 nude mice were randomly assigned into two groups (n=12 per group): control group (intraperitoneal injection of saline) and bevacizumab group (intraperitoneal injection of bevacizumab 5 mg/kg).At four time points after injection (1, 3, 5, 8 d;n=3 at each time point), the volume of tumor and the weight of nude mice were measured.Meanwhile, the levels of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in tumor tissues were detected by Western blotting and immunofluorescence methods, respectively.In second part, 30 nude mice were randomly divided into four groups: control group (n=5), bevacizumab monotherapy group (n=5), paclitaxel monotherapy group (n=5) and paclitaxel plus bevacizumab group (n=15).On the day of administration or the third and fifth day after administration of bevacizumab, paclitaxel plus bevacizumab group received intraperitoneal injection of paclitaxel with five mice at each time point.The paclitaxel and bevacizumab were administered at doses of 3 mg/kg and 5 mg/kg, respectively.The volumes of tumor were measured at 6 time points including 3, 7, 10, 14, 17, 20 days after administration.The nude mice were killed and the weight of tumor was measured 21 days later.The VEGF and MVD of the tumor were detected by Western blotting and immunohistochemistry.Results In the first part of our study, the tumor growth was suppressed gradually after the treatment of bevacizumab as compared with control group.Tumor volume, VEGF level and MVD reached a nadir at 3 days after bevacizumab administration.In the second part, compared with the control group, bevacizumab in combination with paclitaxel at different time points could suppress the tumor growth with a much significant inhibition effect on day 3 after bevacizumab administration.The average tumor volume, tumor weight, VEGF level and MVD were less in combined administration on day 3 than other combined groups.Conclusion The possible timing of the normalization window was typically 1-3 days after the administration of bevacizumab.The normalization window may provide an opportunity to enhance the effect of paclitaxel with the aid of bevacizumab.