Inhibition of Eicosanoids in Prostate Cancer by Fish Oil

我们假设前列腺癌细胞通过环氧合酶代谢其花生四烯酸（AA）储备 (COX)5-脂氧合酶（LOX）或15-LOX-1转化为前列腺素（PG）E2，5-羟基-二十碳四烯酸（5-HETE）， 或12-HETE，这些类二十烷酸中的一种或多种的产生对于前列腺增生是必需的。 癌细胞增殖，二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）干扰 来抑制这种增殖。我们已经开发了一个模型与这些假设。 Pten[loxp/loxp] xPB-Cre 4（Pten-/-）小鼠发生前列腺病变，从增生进展为癌症。这 在喂食n-6饮食（富含AA和AA前体）的小鼠中，进展加快，而在喂食 n-3饮食（富含EPA和DHA）。我们将在体外使用人类和小鼠前列腺细胞来验证我们的假设 和我们的动物模型在体内有三个特定的目的。这些目标旨在表明： 1)人前列腺癌细胞系和Pten-/-小鼠前列腺细胞使用5-LOX、考克斯-1/2和/或15-LOX-1 制备5-HETE、PGE 2和/或12-HETE以促进其自身的体外增殖。 2)EPA和DHA干扰一种或多种加氧酶以阻断类二十烷酸的产生， 体外抑制人前列腺癌细胞系和Pten-/-小鼠前列腺细胞的增殖。 3)n-3饮食类似地干扰一种或多种加氧酶以阻断类二十烷酸的产生， 前列腺的恶性生长，从而提高Pten-/-小鼠的存活率。 先前的研究已经在体外测量了前列腺癌细胞系中的AA代谢物，但预先加载了细胞 用AA检测代谢物AA预加载会妨碍对EPA影响的任何调查， DHA和n-3饮食对AA代谢的影响。我们建立了一种反相高效液相色谱 色谱/电喷雾电离tamdem质谱法，并与它检测的第一个 时间PGE 2、5-HETE和12-HETE在未预加载AA的静息PC-3细胞中。这是一个重大的 这一进展将使我们能够表征前列腺细胞产生的AA、EPA和DHA的代谢物， 组织在体外和体内。因此，我们可以测试我们的假设，从而确定 分子靶点，并确定EPA、DHA和鱼油的抗癌作用机制 含有这些脂肪酸的饮食。

We hypothesize that prostate cancer cells metabolize their arachidonic acid (AA) stores via cyclooxygenases (COX), 5-lipoxygenase (LOX), or 15-LOX-1 to prostaglandin (PG)E2, 5-hydroxy-eicosatetraenoate (5-HETE), or 12-HETE, respectively, that the production of one or more of these eicosanoids is essential for prostate cancer cell proliferation, and that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) interfere with the oxygenases to inhibit this proliferation. We have developed a model relevant to these hypotheses. Pten[loxp/loxp]xPB-Cre4 (Pten-/-) mice develop prostate lesions that progress from hyperplasia to cancer. This progression is speeded in mice fed an n-6 diet (rich in AA and AA precursors) and suppressed in mice fed an n-3 diet (rich in EPA and DHA). We will test our hypotheses using human and mouse prostate cells in vitro and our animal model in vivo with three Specific Aims. These Aims are designed to show that: 1) Human prostate cancer cell lines and Pten-/-' mouse prostate cells use 5-LOX, COX-1/2, and/or 15-LOX-1 to make 5-HETE, PGE2, and/or 12-HETE to promote their own proliferation in vitro. 2) EPA and DHA interfere with one or more of the oxygenases to block eicosanoid production and thereby inhibit the proliferation of human prostate cancer cell lines and Pten-/- mouse prostate cells in vitro. 3) The n-3 diet similarly interferes with one or more of the oxygenases to block eicosanoid production and the malignant growth of the prostate gland and thereby improves survival in Pten-/- mice. Previous studies have measured AA metabolites in prostate cancer cell lines in vitro but preloaded the cells with AA to detect the metabolites. AA preloading would pervert any investigation into the effects of EPA, DHA, and the n-3 diet on AA metabolism. We have established a reversed-phase high performance liquid chromatography/electrospray ionization tamdem mass spectroscopy method and with it detected for the first time PGE2, 5-HETE, and 12-HETE in resting PC-3 cells not preloaded with AA. This represents a significant advance that will allow us to characterize the metabolites of AA, EPA, and DHA made by prostate cells and tissues in vitro and in vivo. We are therefore positioned to test our hypotheses and thereby to identify the molecular targets and define the mechanism for the anti-cancerous effects of EPA, DHA, and the fish oil diets which contain these fatty acids.