阿司匹林对DMBA诱导乳腺癌前病变的抑制作用及其体外抗肿瘤作用机制研究

摘要

近年,阿司匹林对肿瘤的预防及抑制作用被广为关注,且其对于结直肠癌的预防作用已基本明确.但是阿司匹林对于乳腺癌的作用以及其抗肿瘤机制仍没有定论.本研究中利用DMBA诱导的乳腺癌癌前病变模型考察阿司匹林对其的化学预防作用.经口服阿司匹林后,阿司匹林高剂量组(40 mg/kg),低剂量组(20 mg/kg)和模型对照组的癌前病变总数分别为16,13和35,证实阿司匹林可减少癌前病变的发生.体外实验中,SRB细胞增殖实验证实,阿司匹林能够抑制乳腺癌细胞MCF-7的增殖,给药剂量为10mM,8mM,6mM,4mM和2mM时,抑制率分别为86.96％,54.56％,24.83％,14.24％和4.49％.另外,基因芯片测试结果表明4mM和2mM阿司匹林能够改变MCF-7细胞内基因表达水平,并参与细胞周期,细胞骨架,MAPK信号通路,Wnt信号通路等过程的调节.Western blot实验证实相同剂量下阿司匹林能够下调细胞周期调节蛋白cyclin A和Cdk2的表达.研究结果表明阿司匹林能减少乳腺癌癌前病变的发生,其体外抑制乳腺癌细胞增殖与调节细胞肿瘤相关基因和细胞周期相关蛋白表达改变有关联.%The effects of Aspirin on tumor chemoprevention and inhibition have been debated and researched in recent years and its effects on colorectal cancer are quite clear.For breast cancer,however,conclusions are inconsistent and the anti-tumor mechanism of Aspirin is not clear yet.In our study,we used DMBA-induced mammary gland carcinogenesis model to assess the chemoprevention effect of Aspirin on mammary precancerous lesions.After SD rats were treated with Aspirin,the total numbers of precancerous lesion in experimental groups were 16 (40 mg/kg Aspirin) and 13 (20 mg/kg Aspirin),while the number in control group was 35.In vitro,we found that Aspirin inhibited cell proliferation in human breast cancer cell line MCF-7 by SRB assay with no apparent cytotoxity under the doses of 10,8,6,4 and 2 mM,the inhibitory rates were 86.96％,54.56％,24.83％,14.24％ and 4.49％,respectively.In mechanism research,the results of gene microarray assay demonstrated that 4 mM and 2 mM Aspirin were effective in changing gene expression profile in MCF-7 cells.The expression of cell cycle regulator,cyclin A,was significantly down-regulated under the same doses,while the down-regulation of Cdk2 was only remarkable at 4 mM.Our findings reveal that Aspirin is effective in tumor inhibition during initial phase in rats.In MCF-7 cells,Aspirin reduces cell proliferation without significant cytotoxity and its possible mechanism involves altering tumor-related gene expression and regulating cell cycle process.