Tea Polyphenols in Chemoprevention of Prostate Cancer

描述(由申请人提供)：绿茶(GT)和红茶(BT)的抗癌潜力已在许多动物和体外细胞培养研究中得到证实。茶多酚，如表没食子儿茶素没食子酸酯(EGCG)和茶黄素，通过抗氧化活性、改变氧化还原敏感的信号转导途径(核因子-kappaB、激活蛋白1、丝裂原激活蛋白激酶)和抑制胰岛素样生长因子(IGF-1)等多种机制抑制细胞生长，从而抑制细胞增殖、诱导细胞凋亡、细胞周期停滞和血管生成。然而，大多数细胞培养和动物研究都是在高于人类可以达到的浓度的情况下进行的。目前尚不清楚在动物和细胞培养研究中观察到的影响是否可以应用于人类研究。因此，这项研究的总体目标是进行II期临床干预试验，以调查在前列腺切除术前8周饮用相当于6杯GT或6杯BT的绿茶补充剂(Polyhenon E)是否会减少氧化应激，改变导致前列腺增殖抑制和细胞凋亡增加的信号通路。采用免疫组织化学方法检测人前列腺癌等形态改变切片中Ki67、Bax、Bcl2、NFkB蛋白表达及8-羟基脱氧鸟苷浓度。采用化学发光法测定血清前列腺特异性抗原和IGF-1/IGFBP-3。由于体内多酚和茶黄素经历了广泛的内源性和结肠代谢，我们认为代谢产物参与了GT和Bt的化学预防作用。我们将使用高效液相色谱-库拉雷电化学检测以及质谱仪(MS)和气相色谱/质谱仪(GC/MS)来检测茶干预试验参与者的前列腺、血清和尿液中多酚、茶黄素和六种不同内源性和结肠代谢物的浓度。我们还将使用在TEA干预前后收集的血清在我们的LNCaP前列腺癌细胞的体外生物测定中进行测试。最后，我们将确定六种代谢产物对肿瘤坏死因子α刺激后的LNCaP细胞的凋亡、Bax/Bcl2和NFkB-DNA结合的影响。这一结果将有助于设计膳食补充剂，用于前列腺癌早期阶段的化学预防或在警惕等待期间。

DESCRIPTION (provided by applicant): The anticarcinogenic potential of green (GT) and black tea (BT) has been demonstrated in many animal and in vitro cell culture studies. Tea polyphenols, such as epigallocatechin gallate (EGCG) and theaflavins, inhibit cell growth through a variety of mechanisms such as antioxidant activity, alteration of redox-sensitive signal transduction pathways (nuclear factor-kappa B, activator protein 1, mitogen-activated protein kinase) and inhibition of insulin-like growth factor (IGF-1) leading to the inhibition of proliferation, induction of apoptosis, cell cycle arrest as well as inhibition of angiogenesis. However most cell culture and animal studies have been performed with higher concentrations than achievable in humans. It is not clear whether effects observed in animal and cell culture studies can be applied to human studies. Therefore, the overall goal of this study is to perform a phase II clinical intervention trial to investigate whether the consumption of a green tea supplement (Polyphenon E) equivalent to 6 cups of GT or 6 cups of BT for 8 weeks prior to prostatectomy will decrease oxidative stress, alter signaling pathways leading to an inhibition of proliferation and increase of apoptosis in the prostate. We will use immunohistochemistry to determine the apoptotic index and protein expression of Ki67, Bax, Bcl-2, NFkB and concentration of 8-hydroxydeoxyguanosine in sections of equal morphological changes of adenocarcinoma in the human prostate. Serum prostate specific antigen and IGF-1/IGFBP-3 will be determined using chemiluminescent analysis. Since in vivo polyphenols and theaflavins are subject to extensive endogenous and colonic metabolism we propose that metabolites contribute to the chemopreventive effect of GT and BT. We will use high performance liquid chromatography with coularray electrochemical detection as well as mass spectrorrietry (MS) and gas chromatography/ MS to determine the concentrations of polyphenols, theaflavins and six different endogenous and colonic metabo- lites in the prostate, serum and urine of the participants of our tea intervention trial. We will also use the serum collected before and after the tea intervention to be tested in our ex vivo bioassay in LNCaP prostate cancer cells. Finally we will determine the effect of the six metabolites on apoptosis, Bax/Bcl-2 and NFkB- DNA binding after tumor necrosis factor alpha stimulation in LNCaP cells. The results will assist in designing dietary supplements for chemoprevention of early stages of prostate cancer or during watchful waiting.