Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Horinouchi 1432-1, Hachioji, Tokyo 192-0392, Japan.
J Endocrinol. 2011 Apr;209(1):33-43. doi: 10.1530/JOE-10-0357. Epub 2011 Jan 27.
To explore the role of prostaglandin E(2) (PGE(2)) in angiogenesis in the developing corpus luteum, luteal microvascular endothelial-like cells (luteal ECs) were prepared from highly luteinizing ovaries of rats using the percoll density gradient method. The cells abundantly expressed the mRNAs of the endothelial markers CD31 (PECAM-1) and responded to the vascular endothelial growth factor (VEGF) to form in vitro tube structures on Matrigel. Cyclooxygenase (COX) inhibitors significantly suppressed tube formation in luteal ECs, whereas PGE(2) counteracted the COX inhibitor-induced blockage. PGE(2)-induced tube formation was blocked by a cyclic AMP-dependent protein kinase A (PKA) inhibitor, H89. The antagonist against the PGE receptor type 2 (EP2 receptor), AH6809, completely inhibited PGE(2)-induced tube formation and partly suppressed the VEGF-induced tube formation but did not attenuate PGE(2)-induced phosphorylation of both AKT kinase and extracellular signal-regulated kinase 1/2. VEGF significantly enhanced the expression of COX-2 mRNAs detected by real-time RT-PCR and PGE(2) secretion into the media measured by ELISA in luteal ECs. In turn, PGE(2) stimulated VEGF expression. In vitro co-culture of luteal ECs with steroidogenic luteal cells (SLCs) promoted tube formation. Pre-treatment of SLCs with VEGF further enhanced tube formation of ECs, and this effect was blocked by the COX-2 inhibitor. This stimulatory effect was inhibited by treatment with AH6809. These data indicate that PGE(2) exerts a direct stimulatory effect on tube formation mainly via the EP2 receptor/PKA signaling in luteal ECs. Our results suggest the possibility that the endogenous PGE(2) that is produced from luteinizing follicular cells as well as ECs may stimulate luteal angiogenesis.
为了探究前列腺素 E2（PGE2）在黄体血管生成中的作用，本研究采用 Percoll 密度梯度法从大鼠高黄体化卵巢中制备黄体微血管内皮样细胞（黄体 ECs）。这些细胞大量表达内皮标志物 CD31（PECAM-1）的 mRNA，并对血管内皮生长因子（VEGF）做出反应，在 Matrigel 上形成体外管状结构。环氧化酶（COX）抑制剂显著抑制黄体 ECs 的管状结构形成，而 PGE2 则对抗 COX 抑制剂诱导的阻断作用。PGE2 诱导的管状结构形成被环腺苷酸依赖性蛋白激酶 A（PKA）抑制剂 H89 阻断。PGE 受体 2（EP2 受体）拮抗剂 AH6809 完全抑制 PGE2 诱导的管状结构形成，并部分抑制 VEGF 诱导的管状结构形成，但不减弱 PGE2 诱导的 AKT 激酶和细胞外信号调节激酶 1/2 的磷酸化。VEGF 显著增强黄体 ECs 中实时 RT-PCR 检测到的 COX-2 mRNA 的表达和 ELISA 检测到的 PGE2 分泌到培养基中的量。反过来，PGE2 刺激 VEGF 的表达。黄体 ECs 与类固醇生成黄体细胞（SLCs）的体外共培养促进了管状结构的形成。SLCs 先用 VEGF 预处理进一步增强了 ECs 的管状结构形成，这种作用被 COX-2 抑制剂阻断。这种刺激作用被 AH6809 抑制。这些数据表明，PGE2 通过黄体 ECs 中的 EP2 受体/PKA 信号通路对管状结构形成发挥直接刺激作用。我们的研究结果表明，黄体化滤泡细胞和 ECs 产生的内源性 PGE2 可能刺激黄体血管生成。
