咖啡酸锗对小鼠U14瘤的抑制作用及其诱导肿瘤细胞凋亡的机制研究

目的：研究咖啡酸锗对荷瘤U14小鼠的体内抑瘤作用及体外抗肿瘤活性，探讨其抗肿瘤作用机制。方法：观察咖啡酸锗对小鼠U14宫颈癌的抑制率；用MG-P染色和透射电镜的方法观察肿瘤细胞的凋亡情况；流式细胞术(FCM)观察瘤组织的细胞凋亡率并分析细胞周期；免疫组化方法观察肿瘤组织中Bax和Bcl-2蛋白表达情况；MTT法评价咖啡酸锗体外抑制U14肿瘤细胞活性。结果：咖啡酸锗低、中、高剂量组对宫颈癌U14的抑瘤率分别为38.50％、47.17％和64.04％（P<0.01）。MG-P染色及电镜观察可见，咖啡酸锗治疗组出现较多的凋亡细胞（P<0.05），可见典型的细胞凋亡的形态学特征。流式细胞术检测表明咖啡酸锗能诱导U14肿瘤细胞凋亡，在G₀-G₁前出现1个明显的凋亡峰，细胞被阻滞在S期。咖啡酸锗处理后肿瘤组织中Bcl-2蛋白表达下调，Bax蛋白表达上调。咖啡酸锗对体外培养的U14细胞增殖均有一定程度的抑制作用，48 h的IC₅₀值为48.57 mg/L。结论：咖啡酸锗在体内、外均能有效抑制小鼠U14瘤细胞的增殖，并诱导肿瘤细胞凋亡。咖啡酸锗上调U14细胞中Bax蛋白的表达，下调Bcl-2蛋白的表达，进而促进肿瘤细胞凋亡，这可能是其发挥抗肿瘤作用的机制之一。

Inhibitory effect and induction of apoptosis of caffeic acid Ge on growth of U14 in mice

AIM: To evaluate the antitumor effect of caffeic acid Ge on U14 tumor bearing mice. METHODS: The tumor inhibitory ratios of caffeic acid Ge on the growth of U14 in mice was observed. Apoptosis morphological transformation of U14 cells induced by caffeic acid Ge was detected by electronic scan microscope and MG-P staining. Alteration of cell cycle was analyzed by flow cytometry. Apoptosis-related protein levels of Bax and Bcl-2 were determined by immunity histochemistry technology. MTT assay was applied to study the antitumor activities of caffeic acid Ge in U14 cell lines in vitro. RESULTS: Tumor inhibitory rates in caffeic-acid Ge groups were 38.50%, 47.17% and 64.02% (from low dose to high dose) (P<0.01). Caffeic acid Ge induced apoptosis in U14 cells detected by MG-P staining, histopathology and electronic microscopy, the typical apoptosis characteristics in morphology were observed. Flow cytometry results indicated that most of the U14 cells treated with caffeic acid Ge were arrested at the sub-G₀-G₁ phase and the U14 cells were blocked in S phase. The results of immunity histochemistry indicated that the expression of Bcl-2 protein was down-regulated by caffeic acid Ge while Bax protein was up-regulated in U14 tumor tissue (P<0.05). The MTT results suggested that cafffeic acid Ge exhibited high antiproliferative activity in U14 cell lines, and the IC₅₀ for 48 h was 48.57 mg/L. The above results showed that caffeic acid Ge exhibited high antiproliferative activity in vitro. CONCLUSION: Caffeic acid Ge has antiproliferative and proapoptotic effect on U14 tumor cells in vivo and in vitro. Caffeic acid Ge increases the expression of Bax and decreases the expression of Bcl-2 to induce apoptosis of U14 cells. This is one of the possible mechanisms of antitumor.