Kelter Gerhard, Schierholz Jörg M, Fischer Imma U, Fiebig Heinz-Herbert
Oncotest GmbH, Institute for Experimental Oncology, Am Flughafen 12, 79018 Freiburg, Germany.
Anticancer Res. 2007 Jan-Feb;27(1A):223-33.
Mistletoe extracts are widely used in complementary and alternative cancer therapy in Europe. The extracts possess cytotoxic, as well as immunostimulatory effects. However, some investigators have suggested that low doses of mistletoe extracts could also induce tumor growth. The mistletoe extracts Helixor A, Helixor M and Helixor P were investigated for growth inhibitory and stimulatory effects in a panel of 38 human tumor cell lines in vitro. Mistletoe lectin I (ML-1), adriamycin and interleukin-6 (IL-6) were used as reference compounds. All three mistletoe preparations showed cytotoxic activity [T/C (Test/Control) < 30%]: Helixor P was the most potent, followed by Helixor M and Helixor A with IC50 (50% inhibitory concentration) values of 68.4, 114 and 133 microg/ml, respectively. The IC50 values of ML-1 and adriamycin were 0.026 and 0.069 microg/ml. None of the human tumor cell lines in the panel showed growth stimulation (T/C (Test/Control) > 125%) by the mistletoe extracts or ML-1, apart from two exceptions in the colon carcinoma cell line HCC-2998, in which Helixor M and ML-1 showed a marginal stimulation (TIC 128% and 131%, respectively) at one concentration only. Further investigations into the latter effect of Helixor M and ML-1 in the HCC-2998 line using five different proliferation assays, modified cell culture conditions and the identical production charge of mistletoe extract, as well as a new one, did not confirm the previous observation. It was concluded that the marginal stimulation found in the earlier experiments was a statistical coincidence. Helixor mistletoe preparations and ML-1 have cytotoxic activity and do not stimulate tumor cell proliferation in vitro which is in accordance with previous scientifically based observations on aqueous mistletoe extracts.
在欧洲，槲寄生提取物被广泛用于癌症的辅助和替代疗法。这些提取物具有细胞毒性以及免疫刺激作用。然而，一些研究人员认为低剂量的槲寄生提取物也可能诱导肿瘤生长。对槲寄生提取物Helixor A、Helixor M和Helixor P在38种人肿瘤细胞系中的体外生长抑制和刺激作用进行了研究。以槲寄生凝集素I（ML-1）、阿霉素和白细胞介素-6（IL-6）作为参考化合物。所有三种槲寄生制剂均显示出细胞毒性活性[T/C（试验组/对照组）<30%]：Helixor P的活性最强，其次是Helixor M和Helixor A，其IC50（50%抑制浓度）值分别为68.4、114和133微克/毫升。ML-1和阿霉素的IC50值分别为0.026和0.069微克/毫升。除了结肠癌细胞系HCC-2998中的两个例外情况外，该组中的人肿瘤细胞系均未显示出槲寄生提取物或ML-1的生长刺激作用（T/C（试验组/对照组）>125%），在这两个例外情况中，Helixor M和ML-1仅在一个浓度下显示出轻微的刺激作用（TIC分别为128%和131%）。使用五种不同的增殖测定法、改良的细胞培养条件以及相同生产批次的槲寄生提取物，对Helixor M和ML-1在HCC-2998细胞系中的后一种作用进行了进一步研究，结果并未证实之前的观察结果。得出结论认为，早期实验中发现的轻微刺激是一个统计上的巧合。Helixor槲寄生制剂和ML-1具有细胞毒性活性，在体外不会刺激肿瘤细胞增殖，这与之前对槲寄生水提取物的科学观察结果一致。
