目的研究D类细胞周期蛋白（cyclin D3）在Burkitt淋巴瘤细胞Raji中的表达及白桦脂酸对其的影响。方法MTT法检测细胞增殖活性,Annexin-V/PI双标法检测细胞凋亡,流式细胞仪检测细胞周期分布,RT-PCR法分析白桦脂酸作用于Raji细胞后cyclin D3 mRNA表达的变化,Western blotting法检测细胞内cyclin D3的蛋白表达。结果白桦脂酸对Raji细胞有明显的增殖抑制作用。Annxin-V/PI双标法显示,白桦脂酸诱导细胞凋亡呈剂量依赖性。随着白桦脂酸剂量的加大,凋亡率增高。白桦脂酸作用Raji细胞后主要使细胞周期阻滞于G₀/G₁期,G₀/G₁期细胞比例随白桦脂酸剂量增大而逐渐增高。而S期细胞比例随白桦脂酸剂量增大而逐渐降低。对G₂/M期细胞作用不明显。RT-PCR结果显示白桦脂酸作用于Raji细胞使cyclin D3 mRNA表达减少,并与其剂量呈正相关。Western blotting结果显示白桦脂酸使cyclin D3蛋白表达降低.呈剂量依赖性。结论白桦脂酸抑制Raji细胞增殖并诱导细胞凋亡。可使细胞阻滞于G₀/G₁期,其可通过下调cyclin D3表达而发挥抗肿瘤作用。

Objective To investigate the anticancer effects and molecular mechanism of betulinic acid (BA)on Raji cells in vitro.Methods The effects of BA on the growth of Raji cells were studied by MTT assay.Apoptosis was assessed by Annexin-V/PI double-labeled cytometry.The influence on cell cycle was studied by flow cytometer.The cyclin D3 mRNA expression was checked by Western blotting and RT-PCR techniques.Results BA showed obvious inhibition on proliferation,as well as induction potency of apoptosis on Raji cells in vitro in a time-and dose-dependent manner by Annexin-V/PI double-labeled method.With the IC₍₅₀₎value for 24 h being(39.44±0.65)μg/mL,Raji cells treated with BA showed ac- cumulation in G₀/G₁ phase and reduction in the percentage of cells in S phase.The cyclin D3 mRNA ex- pression and protein were sharply decreased in Raji cells treated with BA.Conclusion BA could inhibit the proliferation of Raji cells by regulating the cell cycle that arrests cells at G₀/G₁ phase and induces apop- tosis of Raji cells.The antitumor effects of BA may be related to down-regulation of the expression of cy- clin D3.

国家自然科学基金(30500686)