Wang Shihua, DeGroff Valerie L, Clinton Steven K
Division of Hematology and Oncology, Department of Internal Medicine, The Ohio State University College of Medicine and Public Health, Columbus, OH 43210, USA.
J Nutr. 2003 Jul;133(7):2367-76. doi: 10.1093/jn/133.7.2367.
We examined the ability of polyphenols from tomatoes and soy (genistein, quercetin, kaempferol, biochanin A, daidzein and rutin) to modulate insulin-like growth factor-I (IGF-I)-induced in vitro proliferation and apoptotic resistance in the AT6.3 rat prostate cancer cell line. IGF-I at 50 micro g/L in serum-free medium produced maximum proliferation and minimized apoptosis. Polyphenols exhibited different abilities to modulate IGF-I-induced proliferation, cell cycle progression (flow cytometry) and apoptosis (Annexin V/propidium iodide and terminal deoxynucleotidyltransferase-mediated deoxyuridine 5'-triphosphate nick end labeling). Genistein, quercetin, kaempferol and biochanin A exhibited dose-dependent inhibition of growth with a 50% inhibitory concentration (IC(50)) between 25 and 40 micro mol/L, whereas rutin and daidzein were less potent with an IC(50) of >60 micro mol/L. Genistein and kaempferol potently induced G(2)/M cell cycle arrest. Genistein, quercetin, kaempferol and biochanin A, but not daidzein and rutin, counteracted the antiapoptotic effects of IGF-I. Human prostate epithelial cells grown in growth factor-supplemented medium were also sensitive to growth inhibition by polyphenols. Genistein, biochanin A, quercetin and kaempferol reduced the insulin receptor substrate-1 (IRS-1) content of AT6.3 cells and prevented the down-regulation of IGF-I receptor beta in response to IGF-I binding. IGF-I-stimulated proliferation was dependent on activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) and phosphatidylinositide 3-kinase pathways. Western blotting demonstrated that ERK1/2 was constitutively phosphorylated in AT6.3 cells with no change in response to IGF-I, whereas IRS-1 and AKT were rapidly and sensitively phosphorylated after IGF-I stimulation. Several polyphenols suppressed phosphorylation of AKT and ERK1/2, and more potently inhibited IRS-1 tyrosyl phosphorylation after IGF-I exposure. In summary, polyphenols from soy and tomato products may counteract the ability of IGF-I to stimulate proliferation and prevent apoptosis via inhibition of multiple intracellular signaling pathways involving tyrosine kinase activity.
我们研究了番茄和大豆中的多酚类物质（染料木黄酮、槲皮素、山奈酚、鹰嘴豆芽素A、大豆苷元和芦丁）对胰岛素样生长因子-I（IGF-I）诱导的AT6.3大鼠前列腺癌细胞系体外增殖及凋亡抗性的调节能力。在无血清培养基中，50μg/L的IGF-I可产生最大增殖并使凋亡最小化。多酚类物质在调节IGF-I诱导的增殖、细胞周期进程（流式细胞术）和凋亡（膜联蛋白V/碘化丙啶及末端脱氧核苷酸转移酶介导的脱氧尿苷5'-三磷酸缺口末端标记）方面表现出不同能力。染料木黄酮、槲皮素、山奈酚和鹰嘴豆芽素A表现出剂量依赖性生长抑制，半数抑制浓度（IC50）在25至40μmol/L之间，而芦丁和大豆苷元效力较弱，IC50>60μmol/L。染料木黄酮和山奈酚有效诱导G2/M期细胞周期阻滞。染料木黄酮、槲皮素、山奈酚和鹰嘴豆芽素A可抵消IGF-I的抗凋亡作用，而大豆苷元和芦丁则不能。生长因子补充培养基中培养的人前列腺上皮细胞对多酚类物质的生长抑制也敏感。染料木黄酮、鹰嘴豆芽素A、槲皮素和山奈酚降低了AT6.3细胞中胰岛素受体底物-1（IRS-1）的含量，并防止了IGF-I结合后IGF-I受体β的下调。IGF-I刺激的增殖依赖于丝裂原活化蛋白激酶/细胞外信号调节激酶（ERK）和磷脂酰肌醇3-激酶途径的激活。蛋白质印迹法表明，ERK1/2在AT6.3细胞中组成性磷酸化，对IGF-I无反应变化，而IRS-1和AKT在IGF-I刺激后迅速且敏感地磷酸化。几种多酚类物质抑制了AKT和ERK1/2的磷酸化，并在IGF-I暴露后更有效地抑制了IRS-1酪氨酸磷酸化。总之，大豆和番茄制品中的多酚类物质可能通过抑制涉及酪氨酸激酶活性的多种细胞内信号通路来抵消IGF-I刺激增殖和防止凋亡的能力。
