Leibovici J, Stark Y
J Natl Cancer Inst. 1984 Jun;72(6):1417-20.
In vitro treatment of Lewis lung carcinoma cells with the polysaccharide levan was shown previously to reduce the oncogenicity of these cells by acting on the cell membrane. In the present study the direct effect of levan on the tumorigenicity of Lewis lung carcinoma in C57BL male mice was tested at different doses and intervals and temperatures of incubation. A dose-dependent decrease in tumorigenicity was observed: Doses of 0.5, 1, and 2 mg levan/2 X 10(5) cells/0.2 ml reduced tumor incidence by 30, 50, and 70%, respectively. Some degree of inhibition was observed even with a dose of 0.004 mg. The inhibitory effect was rapid; 5 minutes of incubation resulted in the same reduction in oncogenicity as 60 minutes. Inhibition at 0 degree C was as effective as inhibition at 37 degrees C. The lack of temperature effect indicates that enzymatic activity probably is not involved. The data presented here, together with previous data, suggest that levan induces a physical, rather than a chemical, change in the affected tumor cells. The polysaccharide appears to be loosely, noncovalently bound to the cell membrane.
先前研究表明，用多糖果聚糖对Lewis肺癌细胞进行体外处理可通过作用于细胞膜来降低这些细胞的致癌性。在本研究中，测试了果聚糖在不同剂量、孵育间隔和温度下对C57BL雄性小鼠Lewis肺癌致瘤性的直接影响。观察到致瘤性呈剂量依赖性降低：果聚糖剂量为0.5、1和2mg/2×10(5)个细胞/0.2ml时，肿瘤发生率分别降低30%、50%和70%。即使剂量为0.004mg也观察到了一定程度的抑制作用。抑制作用迅速；孵育5分钟导致的致癌性降低与60分钟相同。0℃下的抑制作用与37℃下的抑制作用一样有效。缺乏温度效应表明可能不涉及酶活性。此处呈现的数据与先前的数据一起表明，果聚糖在受影响的肿瘤细胞中诱导的是物理变化而非化学变化。该多糖似乎以非共价方式松散地结合在细胞膜上。
