Kelavkar Uddhav P, Cohen Cynthia
Urological Research Laboratories, Department of Urology, University of Pittsburgh, Pittsburgh, PA 15232, USA.
Neoplasia. 2004 Jan-Feb;6(1):41-52. doi: 10.1016/s1476-5586(04)80052-6.
We previously discovered that a fat-metabolizing enzyme, 15-lipoxygenase-1 (15-LO-1), is high in human prostate cancer (PCa) and correlates with disease progression. The biologic link between the aberrant 15-LO-1/linoleic acid (LA) metabolism and fat (which is a rich source of growth factors) in PCa is unknown. Therefore, we tested the hypothesis that the metabolic product of the polyunsaturated fatty acid LA (i.e., 13-S-hydroxyoctadecadienoic acid or 13-(S)-HODE) affects the proliferation status of PCa cells through one or more growth factors. We used parental prostate cancer cell line-3 (PC-3) and engineered PC-3 cell lines [PC3-Zeo (mock-transfected), PC3-15LOS (15-LO-1-overexpressing), and PC3-15LOAS (15-LO-1-blocked)] to test our hypothesis. Of the growth factors examined, only insulin-like growth factor-1 (IGF-1) exhibited a two-fold to three-fold increase in growth response on PC3-15LOS cells compared to PC3-Zeo (control) cell line (P <.01). Insulin-like growth factor-1 receptor (IGF-1R) immunohistochemical analyses of human normal and adenocarcinoma prostate tissues, as well as levels in tumors derived from nude mice injected with PC-3 cells, demonstrated that elevated IGF-1R expression correlated with 15-LO-1 levels. Radioligand binding assays demonstrated two-fold higher IGF-1 binding sites in PC3-15LOS cells (P <.05 vs PC3-Zeo cells). IGF-1R promoter reporter assay and affinity-purified IGF-1R receptor levels demonstrated a four-fold higher activity in PC3-15LOS cells (P <.01 vs PC3-Zeo cells). IGF-1R promoter activation is 13-(S)-HODE-dependent. IGF-1R blockade with a dominant-negative adenovirus caused significant growth inhibition in PC-3 cells (P <.0001; PC3-15LOAS versus PC3-15LOS cells), as well as affected the IGF-1-stimulated mitogen-activated protein (MAP) kinase (Erk1/2) and Akt activation levels. Our study suggests that overexpression of 15-LO-1 in PCa contributes to the cancer progression by regulating IGF-1R expression and activation.
我们之前发现，一种脂肪代谢酶，15-脂氧合酶-1（15-LO-1），在人类前列腺癌（PCa）中含量很高，且与疾病进展相关。PCa中异常的15-LO-1/亚油酸（LA）代谢与脂肪（生长因子的丰富来源）之间的生物学联系尚不清楚。因此，我们检验了这样一个假设，即多不饱和脂肪酸LA的代谢产物（即13-S-羟基十八碳二烯酸或13-(S)-HODE）通过一种或多种生长因子影响PCa细胞的增殖状态。我们使用亲代前列腺癌细胞系-3（PC-3）和工程化的PC-3细胞系[PC3-Zeo（mock转染）、PC3-15LOS（15-LO-1过表达）和PC3-15LOAS（15-LO-1阻断）]来检验我们假设。在所检测的生长因子中，与PC3-Zeo（对照）细胞系相比，只有胰岛素样生长因子-1（IGF-1）对PC3-15LOS细胞的生长反应增加了两倍到三倍（P <.01）。对人类正常和腺癌前列腺组织进行胰岛素样生长因子-1受体（IGF-1R）免疫组织化学分析，以及对注射PC-3细胞的裸鼠肿瘤中的水平进行检测，结果表明IGF-1R表达升高与15-LO-1水平相关。放射性配体结合试验表明，PC3-15LOS细胞中的IGF-1结合位点高出两倍（与PC3-Zeo细胞相比，P <.05）。IGF-1R启动子报告基因试验和亲和纯化的IGF-1R受体水平表明，PC3-15LOS细胞中的活性高出四倍（与PC3-Zeo细胞相比，P <.01）。IGF-1R启动子激活依赖于13-(S)-HODE。用显性负性腺病毒阻断IGF-1R可导致PC-3细胞显著生长抑制（P <.0001；PC3-15LOAS与PC3-15LOS细胞相比），并影响IGF-1刺激的丝裂原活化蛋白（MAP）激酶（Erk1/2）和Akt激活水平。我们的研究表明PCa中15-LO-1的过表达通过调节IGF-1R表达和激活促进癌症进展。
