三氧化二砷抑制乳腺癌裸鼠移植瘤的生长及其作用机制的探讨

Arsenic trioxide inhibition of tumor growth of subcutaneously implanted human breast cancer cells and its mechanism

目的探讨三氧化二砷(As2O3)对人乳腺癌细胞系MCF-7细胞裸鼠背部皮下移植瘤生长的抑制作用及其作用机制。方法建立BALB/C-nu/nu裸鼠MCF-7人乳腺癌皮下移植瘤模型,以不同浓度的As2O3行腹腔内注射,与5-氟脲尿嘧啶(5-FU)治疗进行对比,观察移植瘤的瘤重及瘤重抑制率。通过流式细胞仪检测移植瘤的凋亡情况,免疫组织化学法检测bcl-2,Fas基因表达水平的变化,并进行血常规及骨髓涂片检查。结果5-FU(8mg/kg)组,As2O3(4mg/kg)组,As2O3(8mg/kg)组均能明显抑制裸鼠皮下肿瘤的生长,抑瘤率分别为38.33%,51.42%和62.43%;As2O3对移植瘤的生长抑制作用明显强于5-FU,差异有显著性(P<0.01)。两种浓度As2O3组MCF-7细胞凋亡率明显高于5-FU组。各实验组乳腺癌细胞存在G2/M期阻滞,在G1峰前出现明显的凋亡峰。移植瘤组织中bcl-2蛋白阳性细胞数明显减少,Fas蛋白阳性细胞数明显增加。血常规及骨髓涂片计数显示As2O3实验组未见造血系统功能受抑,与5-FU组相比较,差异有显著性(P<0.05)。结论As2O3可明显抑制乳腺癌移植瘤的生长,诱导移植瘤MCF-7细胞凋亡;其作用的机制可能是下调bcl-2基因表达,上调Fas基因表达。

Objective To study the inhibitory effect of arsenic trioxide （ As2I3 ） on the tumor growth of breast cancer cell line MCF-7 implanted subcutaneously in nude mice and its mechanism. Methods BALB/C-nu/nu nude mice were subcutaneously injected with MCF-7 breast cancer cell line, and treated with intraperitoneal injection of As2 03 and 5-FU in different concentrations. The implanted tumor was weighed, and the tumor inhibition rates were calculated. The apoptosis of the implanted tumor was detected by flow cytometry. The expressions of bcl-2 and Fas induced by As2 03 were examined by immunohistochemical method. Routine blood test and bone marrow test were used to observe the function of hematopoietic system after As2O3 treatment. Results The growth of implanted tumor was markedly inhibited with 5-FU, low dose and high dose As2O3 , the inhibitory rates being 38.33% ,51.42% and 62.43% , respectively. The inhibitory effect of As2O3 was significantly stronger than that of 5-FU （ P 〈 0.01 ）. The apoptosis rate of MCF-7 cells treated with the 2 concentrations of As2O3 was significantly higher than that of 5-FU treated group. Breast cancer cells in all the study groups showed G2/M stage arrest, while a marked apoptosis peak was observed before the G1 peak. The immunohistochemical staining showed that the number of bcl-2 protein positive cells decreased, and the number of Fas protein positive cells increased. The function of hematopoietic system was not inhibited. Conclusions As2O3 inhibits the growth of human breast cancer cell implanted tumor and induces apoptosis of MCF-7. The molecular mechanism of As2O3 on induction of apoptosis of breast cancer cells may be through decreasing the expression of bcl-2 and increasing the expression of Fas.