Role of PGE2 Receptors in Mouse Skin Cancer

PGE2 受体在小鼠皮肤癌中的作用

• 批准号: 7594028
• 负责人: Robert Langenbach
• 金额: $ 79.32万
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7594028
• 关键词: Agonist; Apoptosis; Apoptotic; CCL4 gene; Cell Surface Receptors; Complex; Cyclic AMP-Dependent Protein Kinases; Data; Development; Dinoprostone; Docking; Epidemiologic Studies; Family; Goals; Human; Immunoprecipitation; Indomethacin; Malignant Neoplasms; Mediating; Modeling; Mus; Numbers; PTGS2 gene; Papilloma; Production; Prostaglandin Production; Prostaglandin-Endoperoxide Synthase; Prostaglandins; Protein Kinase; Proteins; Proto-Oncogene Proteins c-akt; Role; Series; Signal Pathway; Signal Transduction; Signal Transduction Pathway; Skin; Skin Cancer; Skin Papilloma; UV induced; Ultraviolet B Radiation; Wild Type Mouse; arrestin B; cyclooxygenase 1; cyclooxygenase 2; human WFDC2 protein; inhibitor/antagonist; keratinocyte; progesterone 11-hemisuccinate-(2-iodohistamine); prostaglandin EP2 receptor; prostanoid receptor EP1; receptor; tumorigenesis

The major goal of the study was the elucidation of the role of prostaglandin E2 (PGE2) receptors (EP) in chemically and UV induced mouse skin tumorigenesis. Epidemiological studies in humans have confirmed an important role of PGs, including PGE2, in a variety of cancers including skin cancer. PGE2 produced via the cyclooxygenases (COX-1/COX-2) act on four different cell surface receptors (EP 1, -2, -3, -4), which belong to the family of GPCRs. In one series of studies, the mouse skin initiation/promotion model was used to investigate the contribution of the PGE2 receptors, EP2 and EP4, in papilloma development. Indomethacin was used to inhibit epidermal PG production and reduced papilloma formation about 60%. In indomethacin treated mice the EP2 agonist restored papilloma formation to TPA treatment levels, but the EP4 agonist was ineffective. In papillomas, the EP2 agonist increased Ras activation and levels as well as c-AMP, p-Src, p-EGFr, p-Erk and p-Akt levels. Treatment of papillomas with EGFr (Ag1478) or Src (PP2) inhibitors demonstrated that p-EGFr was downstream of p-Src. Ag1478 also inhibited the activation of Ras, Erk and AKT. EP2s role in papilloma development was confirmed by the observations that EP2 -/- mice showed a 60% reduction in papilloma numbers and reduced activation of Ras, Src, AKT and Erk. Immunoprecipitation of p-Src or EP2 indicated the presence of an EP2-b-arrestin1/2-p-Src complex in papillomas of wild type. B-arrestin can contribute to EP2 internalization as welll as serve as a docking protein and facilitate EP2 signaling. The data indicate that PGE2 acting via EP2 activates signal transduction pathways that can contribute to mouse skin papilloma development. In a second serries of studies, the roles of EP2 and EP4 on UV induced skin damage was investigated. Wild type (WT) and COX-2-/- mice were acutely treated with UVB (5 kJ/m2) and apoptotic signaling pathways compared. Following exposure, apoptosis was 2.5-fold higher in COX-2-/- compared to WT mice. Because prostaglandin (PG) E2 is the major UV-induced PG and manifests its activity via four receptors, EP1 to 4, possible differences in EP signaling were investigated in WT and COX-2-/- mice. Following UVB exposure, protein levels of EP1, EP2, and EP4 were elevated in WT mice, but EP2 and EP4 levels were 50% lower in COX-2-/- mice. Activated cAMP-dependent protein kinase (PKA) and Akt are downstream in EP2 and EP4 signaling, and their levels were reduced in UVB-exposed COX-2-/- mice. Furthermore, p-Bad (Ser136 and Ser155), anti-apoptotic products of activated Akt and PKA, respectively, were significantly reduced in UVB-exposed COX-2-/- mice. To further study EP2 and EP4s roles, UVB-exposed CD-1 mice were topically treated with indomethacin to block endogenous PGE2 production, and PGE2, an EP2 agonist or an EP4 agonist applied. Indomethacin reduced PKA and Akt activation about 60%, but PGE2 and the agonists restored their activities. Furthermore, both agonists decreased apoptosis in COX-2-/- mice by 50%. The data suggest that COX-2 generated PGE2 has anti-apoptotic roles in UVB-exposed mouse skin that involves EP2 and EP4 mediated signaling that reduced keratinocyte apoptosis.

该研究的主要目的是阐明前列腺素E2（PGE2）受体（EP）在化学和紫外线诱导的小鼠皮肤肿瘤发生中的作用。人类流行病学研究 在包括皮肤癌在内的各种癌症中，包括PGS（包括PGE2）的重要作用。通过环氧合酶（COX -1/COX -2）产生的PGE2对属于GPCR家族的四个不同细胞表面受体（EP 1，-2，-3，-4）作用。 在一系列研究中，使用小鼠皮肤起始/促进模型来研究PGE2受体EP2和EP4在乳头瘤发育中的贡献。吲哚美辛用于抑制表皮PG的产生，并降低乳头状瘤的形成约60％。在吲哚美辛治疗的小鼠中，EP2激动剂将乳头状瘤的形成恢复为TPA治疗水平，但EP4激动剂无效。在乳头状瘤中，EP2激动剂增加了RAS激活和水平以及C-AMP，P-SRC，P-EGFR，P-ERK和P-AKT水平。用EGFR（AG1478）或SRC（PP2）抑制剂治疗乳头状瘤表明P-EGFR是P-SRC的下游。 AG1478还抑制了RAS，ERK和AKT的激活。 EP2 - / - 小鼠的乳头瘤数量减少了60％，RAS，SRC，AKT和ERK的激活降低了60％，证实了EP2S在乳头瘤发育中的作用。 P-SRC或EP2的免疫沉淀表明在野生型乳头状瘤中存在EP2-B-arrestin1/2-P-SRC复合物。 B- arrestin可以促进EP2内在化以及作为对接蛋白的使用，并促进EP2信号传导。数据表明，通过EP2作用的PGE2激活信号转导途径，这可能有助于小鼠皮肤乳头状瘤的发育。 在第二次研究中，研究了EP2和EP4在紫外线诱导的皮肤损伤中的作用。比较用UVB（5 kJ/m2）和凋亡信号通路急性治疗野生型（WT）和COX-2 - / - 小鼠。暴露后，与WT小鼠相比，COX-2 - / - 的凋亡高2.5倍。由于前列腺素（PG）E2是主要的紫外线诱导的PG，并通过四个受体表现出其活性，因此EP1至4，在WT和COX-2 - / - 小鼠中研究了EP信号传导的可能差异。在UVB暴露后，WT小鼠中EP1，EP2和EP4的蛋白质水平升高，但是COX-2 - / - 小鼠的EP2和EP4水平降低了50％。活化的CAMP依赖性蛋白激酶（PKA）和AKT在EP2和EP4信号中下游，在暴露于UVB的COX-2 - / - 小鼠中它们的水平降低。此外，P-BAD（Ser136和Ser155）分别在UVB暴露的COX-2 - / - 小鼠中显着降低了活化Akt和PKA的抗凋亡产物。为了进一步研究EP2和EP4S的角色，用吲哚美辛局部治疗UVB暴露的CD-1小鼠，以阻断内源性PGE2的产生，而PGE2（EP2激动剂或EP4激动剂）应用。吲哚美辛降低了PKA和AKT激活约60％，但PGE2和激动剂恢复了其活动。此外，两种激动剂均在COX-2 - / - 小鼠中降低50％。数据表明，COX-2生成的PGE2在UVB暴露的小鼠皮肤中具有抗凋亡作用，涉及EP2和EP4介导的信号传导，从而降低了角质形成细胞的凋亡。