Saarinen Niina M, Power Krista, Chen Jianmin, Thompson Lilian U
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Int J Cancer. 2006 Aug 15;119(4):925-31. doi: 10.1002/ijc.21898.
In several epidemiological studies, a phytoestrogen-rich diet containing lignans and isoflavones is associated with reduced breast cancer risk, but experimental findings are controversial. In postmenopausal mammary cancer xenograft model, flaxseed (FS), a rich source of plant lignans, reduced breast cancer growth, while soy protein (SP), a rich source of isoflavones, enhanced it. The intake of phytoestrogens is increasing particularly among postmenopausal women, emphasizing the importance of elucidating their interactive effects on breast cancer. Our study determined the effect of FS and SP diets, alone and in combination, on the established human breast cancer MCF-7 tumor growth in ovariectomized athymic nude mice. Tumor bearing mice were divided into 4 groups and fed for 25 weeks either the basal diet (BD), or BD supplemented with 10% FS, 20% SP or 10% FS and 20% SP. After estrogen deprivation, FS regressed the tumor size similar to that of control. SP initially regressed the tumors but starting at week 13, the tumors regressed significantly less than in control and 43% of the tumors were regrowing until the end of the experiment and were significantly larger in size than in control. The combination of SP with FS reduced the tumor growth similar to that of control, as suggested also by the reduced tumor cell proliferation index. In conclusion, dietary FS did not stimulate the growth of estrogen responsive MCF-7 cancers in ovariectomized mice, while long-term consumption of SP did. Furthermore, FS reduced the tumor growth stimulating effect of SP to the same level as control, suggesting tumor growth attenuating effect of FS.
在多项流行病学研究中，富含木脂素和异黄酮的植物雌激素饮食与降低乳腺癌风险相关，但实验结果存在争议。在绝经后乳腺癌异种移植模型中，富含植物木脂素的亚麻籽（FS）可抑制乳腺癌生长，而异黄酮丰富的大豆蛋白（SP）则会促进其生长。植物雌激素的摄入量在绝经后女性中尤其增加，这凸显了阐明其对乳腺癌的交互作用的重要性。我们的研究确定了FS和SP单独及联合饮食对去卵巢无胸腺裸鼠中已建立的人乳腺癌MCF-7肿瘤生长的影响。荷瘤小鼠分为4组，分别喂食基础饮食（BD）、添加10% FS的BD、添加20% SP的BD或添加10% FS和20% SP的BD，持续25周。雌激素剥夺后，FS使肿瘤大小缩小至与对照组相似。SP最初使肿瘤缩小，但从第13周开始，肿瘤缩小程度明显低于对照组，43%的肿瘤直至实验结束仍在生长，且大小显著大于对照组。SP与FS联合使用使肿瘤生长降低至与对照组相似，肿瘤细胞增殖指数降低也表明了这一点。总之，饮食中的FS不会刺激去卵巢小鼠中雌激素反应性MCF-7癌的生长，而长期食用SP则会。此外，FS将SP对肿瘤生长的刺激作用降低至与对照组相同水平，表明FS具有肿瘤生长减弱作用。
