常规化疗联合节拍化疗对乳腺癌裸鼠移植瘤的实验研究

摘要

背景与目的:乳腺癌治疗应从全局出发,将针对肿瘤细胞本身和肿瘤微环境相结合,而研究发现节拍化疗在抗血管生成等改善肿瘤微环境方面有明显优势.本文旨在观察环磷酰胺(cyclophosphamide,CTX)常规化疗联合节拍化疗对乳腺癌裸鼠移植瘤的抑瘤效应,探讨其对血管新生和细胞增殖、凋亡的影响.方法:建立乳腺癌裸鼠原位移植瘤模型,随机分成4组:节拍化疗(LDM)组、常规化疗(MTD)组、联合(LDM+MTD)组和0.9％NaCl溶液对照组,治疗期间观察裸鼠一般状况、隔日称重并测量皮下移植瘤体积,每周尾静脉采血白细胞计数(white blood cell counts,WBC).实验结束后处死小鼠取瘤称重,计算各组抑瘤率.免疫组织化学法检测移植瘤组织中微血管密度(microvessel density,MVD),以及血管内皮细胞生长因子(vascularendothelial growth factor,VEGF)、凝血酶敏感蛋白1(thrombospondin-1,TSP-1)、增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)表达,TUNEL检测肿瘤细胞凋亡.结果:CTX 3种化疗方案均可不同程度抑制移植瘤生长,其中LDM组和MTD组移植瘤生长曲线类似,LDM+MTD组移植瘤生长明显缓于其他各组；LDM组、MTD组和LDM+MTD组的抑瘤率分别为32.95％、41.57％和69.15％; LDM组和LDM+MTD组MVD、VEGF相对低表达、TSP-1相对高表达,而组间比较差异无统计学意义(P＞0.05),但与其余两组比较差异有统计学意义(P＜0.05).MTD组和LDM+MTD组PCNA相对低表达,与其余两组比较差异有统计学意义(P＜0.05),LDM+MTD组凋亡指数(apoptosis index,AI)明显高于其他各组,差异有统计学意义(P＜0.05).结论:CTX常规化疗联合节拍化疗兼有抗血管生成、抑制细胞增殖、促进肿瘤细胞凋亡作用,抑瘤作用较单一传统化疗和节拍化疗更为明显,不良反应不明显.%Background and purpose: The treatment of breast cancer should aim at tumor cells themselves and tumor microenvironment. It has been reported that metronomic chemotherapy enjoys obvious advantages in improving tumor microenvironment. The purpose of this study was to compare the antitumor effects in nude mice with human breast cancer with different cyclophosphamide chemotherapy regimens and to observe two balances: between pro-angiogenesis and anti-angiogenesis and between tumor cell proliferation and apoptosis. Methods: Breast ortho-topic transplantation tumor model was established. Twenty nude mice bearing carcinoma were divided into 4 groups randomly: metronomic chemotherapy group (LDM), conventional chemotherapy group (MTD), combination group (LDM+MTD) and control group. The general condition of mice was observed and the mice were weighed every other day, at the same time the volume of subcutaneous tumor was measured. WBC was counted every week. In the end, tumors were taken off and weighed to calculate inhibitory rates of each group. Immunohistochemistry was used to detect the tumor microvessel density (MVD), and the expressions of VEGF, TSP-1 and PCNA. TUNEL was used to detectthe apoptosis of the tumor cells. Results: All nude mice were in good condition throughout the trial period without significant side effects. Three chemotherapy regimens could inhibit the growth of xenografts in different degrees, whose inhibitory rates were 32.95%, 41.75% and 69.15%, respectively. LDM and MTD had similar tumor growth curve, while the xenografts in combination group appeared to grow significantly slower than the other groups. In the combination group and LDM group, xenografts expressed lower level VEGF and MVD and higher level TSP-1 than those in the other groups (P<0.05), but there was no significant difference between the two groups (P>0.05). There was lower expression of PCNA in the combination group and MTD group than those in the LDM and control groups (P<0.05), but there was no statistically significant difference between the two groups (P>0.05). The apoptosis index (AI) in three chemotherapy groups had statically significant difference with control group (P<0.05). Furthermore, the AI in the combination group was the highest. Conclusion: Conventional chemotherapy combined with metronomic chemotherapy has more powerful anti-cancer effects compared to the single conventional or metronomic chemotherapy without obvious side effect. The probable mechanism may be related with suppressing angiogenesis, inhibiting tumor cell proliferation and inducing apoptosis.