羊栖菜多糖体外抗肿瘤的作用及其机制(英文)

Effects and mechanism of sargassum fusiforme polysaccharide on antitumor in vitro

背景:药物治疗是肿瘤治疗的主要手段之一,近年来从天然植物中寻找低毒抗癌活性成分的研究广受重视。其中,多糖类成分通过调节机体免疫而发挥抗癌作用的机制已经得到公认,但从诱导细胞凋亡等多个角度探讨多糖的抗癌机制将为癌症治疗提供新的理论依据。目的:观察羊栖菜多糖对不同组织肿瘤的抑制作用及其对肿瘤治疗的组织特异性,并从细胞凋亡角度探讨其作用机制。设计:以6种不同的肿瘤细胞为观察对象的体外平行对照实验及动态测定实验。单位:哈尔滨商业大学药物研究所博士后科研工作站。材料:实验于2002-11/2003-10在哈尔滨医科大学药理研究室完成。药物选用羊栖菜多糖,5-氟尿嘧啶;细胞株选用处于对数生长期的人肝癌Bel-7405、人宫颈癌克隆cc-801、人乳腺癌MCF-7、人直肠癌COLO-205、人胃癌SGC-7901、人食管癌Eca-109。方法:采用四甲基偶氮唑盐法和集落形成实验法观察羊栖菜多糖的体外抗肿瘤作用;采用流式细胞仪观察羊栖菜多糖对肿瘤细胞周期及细胞凋亡的影响;采用Fluo-3/AM探针标记,激光共聚焦技术观测细胞内Ca2+浓度。主要观察指标:羊栖菜多糖对6种细胞的对细胞抑制50%的药物浓度和集落形成率;对SGC-7901细胞的凋亡率测定、细胞周期分析及细胞内Ca2+浓度含量测定。结果:①羊栖菜多糖的体外抗肿瘤作用:羊栖菜多糖对6种人胃癌细胞株均有一定的抑制作用,而尤以对人胃癌(SGC-7901)和直肠癌(COLO-205)效果最为明显。②羊栖菜多糖对SGC-7901人胃癌细胞周期及细胞凋亡的影响:通过对给药后4,8,12,24,485个时间段细胞凋亡的观察,发现羊栖菜多糖组各时间段G0/G1期细胞都多于空白对照组,羊栖菜多糖给药12h后,凋亡指数较相应时间段空白对照组明显升高(12.17±0.88,1.43±0.32;20.33±0.69,1.56±0.67;18.77±0.68,1.55±0.46,P<0.01)。③羊栖菜多糖对SGC-7901细胞内Ca2+浓度的影响:给药前SGC-7901细胞内Ca2+浓度处于一个相对恒定的浓度。给药后Ca2+浓度迅速升高然后又降低,加入CaCl2后Ca2+浓度又升高。结论:羊栖菜多糖对人胃癌细胞和直肠癌细胞效果较好,这一作用是通过诱导肿瘤细胞凋亡达到的。羊栖菜多糖可阻滞SGC-7901人胃癌细胞内G0/G1期进入S期,升高细胞凋亡指数。羊栖菜多糖能通过引起肿瘤细胞内钙库Ca2+的释放而升高肿瘤细胞内Ca2+浓度,从而达到诱导肿瘤细胞凋亡而抗肿瘤的作用。

BACKGROUND： Medication is one of main means in treatment of tumor. In recent years, the study has been drawn great attention on searching lowtoxic antitumor active components from natural plants, in which, the public recognition has been given to the mechanism of polysaecharide on antitumor by regulating body immunity. New theoretical basis for treatment of carcinoma will be provided from the mechanism of polysaccharide on antitumor discussed in various views, such as induction of cell apoptosis. OBJECTIVE： To observe the inhibition of sargassum fusiforme polysaccharide （SFPS） on various tumor tissues and its tissue specialty in tumor treatment so as to probe into its mechanism in view of cell apoptosis. DESIGN： Parallel controlled experiment in vitro and dynamic determination experiment was designed, in which, 6 kinds of tumor cells were employed as objects. SETTING： Postdoctoral Scientific Research Working Station, Institute of Materia Mediea , Harbin University of Commerce MATERIALS：The experiment was performed in the Department of Pharmacology, Harbin Medical University from November 2002 to October 2003, in which, SFPS and 5- fluorouracil （FU） were selected. The cell lines included human hepatoma Bel-7405, human cervical carcinoma clone ec801, human breast carcinoma MCF-7, human rectum carcinoma COLC-205, human gastric carcinoma SGC-7901 and human esophagus carcinoma Eca- 109 at logarithmic growth phase. METHODS：Methylthiazolyl tetrazolium assay （MIT） and colony-forming methods were adopted to study antitumor activity of SFPS in vitro. Flow cytometer （FCM） was used to observe the effect of SFPS on cycle and apoptosis of tumor cell. Laser eonfocal scanning microscopy （LCM） was used to measure [Ca^2＋]i in cells marked by Fluo-3/AM probe. MAIN OUTCOME MEASURES： Drug concentration and colony forming rate of cell inhibition of SFPS by 50% on 6 kinds of cells. Determination of apoptosis rate of SGC-7901 cell, analysis on cell cycle and determination of [Ca^2＋]i in cells RESULTS： ① Antitumor of SFPS in vitro： SFPS provided a certain inhibition on 6 kinds of cell lines of gastric carcinoma, of which, the results on 5GC-7901 and COLO-205 were the most obvious. ② Effect of SFPS on cell cycle and apoptosis of SGC-7901： By the observation of cell apoptosis on 5 time divisions after medication, named in 4, 8, 12, 24 and 48 hours, it was discovered that the cell count at G0/G1 stage in various time divisions in SFPS group was more than blank control, in which, in 12 hours medication with SFPS, the apoptosis index was increased remarkably at corresponding times compared with blank control （12.17±0.88, 1.43±0.32; 20.33±0.69, 1.56±0.67; 18.77±0.68, 1.55±0.46, P 〈 0.01）. ③ Effect of SFPS on intracellular [Ca^2＋]i of SGC-7901： before medication, [Ca^2＋]i in 5GC-7901 cell was relative constant. After medication, it was increased swiftly and followed by decreasing, and it was increased again after CaC12 was added. CONCLUSION： SFPS provides better results on human gastric cancer cell and rectum cancer cell, which is achieved by inducing apoptosis of tumor cells. SFPS blocks SGC-7901 entering S phase from G0/G1 phase and increases cell apoptosis index. SFPS increases [Ca^2＋]i in tumor cells by leading to Ca^2＋ release from calcium pool in tumor cells so as to induce apoptosis of tumor cells end achieve antitumor.