Suppression of pancreatic carcinoma growth by activating peroxisome proliferator-activated receptor γ involves angiogenesis inhibition
Suppression of pancreatic carcinoma growth by activating peroxisome proliferator-activated receptor γ involves angiogenesis inhibition
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DOI：
10.3748/wjg.15.441
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发表时间：
2009-01-28
影响因子：
4.3
通讯作者：
Wu, Kai
中科院分区：
文献类型：
--
作者：
Dong, Yu-Wei;Wang, Xing-Peng;Wu, Kai
目的：探讨配体激活的转录因子--过氧化物酶体增殖物激活受体-γ(PPAR-γ)在胰腺癌发生过程中的作用及其机制。方法：采用逆转录聚合酶链式反应(RT-PCR)结合免疫细胞化学方法检测PPAR-γ和视黄酸受体(PXR-α)在胰腺癌发生、发展中的表达。胰腺癌细胞PANC-1分别用RXRα的配体9-cis-RA和PPAR-γ的配体15-脱氧-Delta(12，14)前列腺素J(2)(15d-PGJ(2))处理，或两者同时作用。用四甲基偶氮唑蓝(四甲基偶氮唑蓝)比色法测定细胞存活率来评价其抗增殖作用。通过皮下接种PANC-1细胞建立胰腺癌裸鼠移植瘤模型。实验组裸鼠饮水给予PPAR-γ的特异性配体罗格列酮。75d后处死所有小鼠。用免疫组织化学方法检测肿瘤组织中增殖细胞核抗原的表达。采用半定量RT-PCR方法检测不同浓度和不同作用时间的15d-PGJ(2)或9-cis-RA对PANC-1细胞血管内皮生长因子(VEGF)基因表达的影响。观察罗格列酮对移植瘤组织微血管密度(MVD)和血管内皮生长因子(VEGF)表达的影响。结果：RT-PCR和免疫细胞化学染色显示PPARγ和RXRα在PANC-1细胞转录和翻译水平均有表达。结果表明，15d-PGJ(2)、9-cis-RA及其联合作用可抑制PANC-1细胞的生长，并呈剂量依赖关系。9-顺式-维甲酸联合15d-PGJ(2)对胰腺癌生长有抑制作用。体内实验表明，罗格列酮对胰腺癌的生长有明显的抑制作用(0.48±0.23 cm(3)vs 2.488±0.59 cm(3)，P<；0.05)，抑制率为80.7%。免疫组织化学研究显示，罗格列酮治疗组与对照组相比，增殖细胞核抗原表达下调。15D-PGJ(2)、9-cis-RA及其联合应用可抑制PANC-1细胞中VEGF mRNA的表达，并呈剂量和时间依赖关系。罗格列酮治疗组小鼠微血管密度(10.67±3.07)显著低于对照组(31.44±6.06)(P<；0.01)。罗格列酮治疗的小鼠移植瘤组织中血管内皮生长因子的表达也明显下调。结论：PPAR-γ的激活在体内外均能抑制胰腺癌的生长。通过下调血管内皮生长因子的表达抑制肿瘤血管生成可能是PPAR激活抑制胰腺癌生长的机制之一。(C)2009年WJG Press和Baishiden。版权所有。
AIM: To study the possible actions and mechanisms of peroxisome proliferator-activated receptor gamma (PPAR gamma), a ligand-activated transcription factor, in pancreatic carcinogenesis, especially in angiogenesis.METHODS: Expressions of PPAR gamma and retinoid acid receptor (PXR alpha) were examined by reverse-transcription polymerase chain reaction (RT-PCR) with immunocytochemical staining. Pancreatic carcinoma cells, PANC-1, were treated either with 9-cis-RA, a ligand of RXR alpha, or with 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), a ligand of PPAR gamma, or both. Anti proliferative effect was evaluated by cell viability using methyltetrazolium (MTT) assay. A pancreatic carcinoma xenograft tumor model of nude mice was established by inoculating PANC-1 cells subcutaneously. Rosiglitazone, a specific ligand of PPAR gamma, was administered via water drinking in experimental group of nude mice. After 75 d, all mice were sacrificed. Expression of proliferating cell nuclear antigen (PCNA) in tumor tissue was examined with immunohistochemical staining. Expression of vascular enclothelial growth factor (VEGF) mRNA in PANC-1 cells, which were treated with 15d-PGJ(2) or 9-cis-RA at various concentrations or different duration, was detected by semi-quantitative RT-PCR. Effects of Rosiglitazone on changes of microvascular density (MVD) and VEGF expression were investigated in xenograft tumor tissue. Neovasculature was detected with immunohistochemistry staining labeled with anti-IV collagen antibody, and indicated by MVD.RESULTS: RT-PCR and immunocytochemical staining showed that PPAR gamma and RXR alpha were expressed in PANC-1 cells at both transcription level and translation level. MTT assay demonstrated that 15d-PGJ(2), 9-cis-RA and their combination inhibited the growth of PANC-1 cells in a dose-dependent manner. 9-cis-RA had a combined inhibiting action with 15d-PGJ(2) on the growth of pancreatic carcinoma. In vivo studies revealed that Rosiglitazone significantly suppressed the growth of pancreatic carcinoma as compared to control group (0.48 +/- 0.23 cm(3) vs 2.488 +/- 0.59 cm(3), P < 0.05), and the growth inhibition rate was 80.7%. Immunohistochemistry study showed that PCNA was down regulated in Rosiglitazone-treated group compared to the control group. 15d-PGJ(2), 9-cis-RA and their combination inhibited the expression of VEGF mRNA in PANC-1 cells in a dose- and time-dependent manner. MVD was decreased more significantly in Rosiglitazone-treated mice (10.67 +/- 3.07) than in the control group (31.44 +/- 6.06) (P < 0.01). VEGF expression in xenograft tumor tissue was also markedly down-regulated in Rosiglitazone-treated mice.CONCLUSION: Activation of PPAR gamma inhibits the growth of pancreatic carcinoma both in vitro and in vivo. Suppression of tumor angiogenesis by down-regulating the expression of VEGF may be one of the mechanisms by which PPAR gamma activation inhibits the growth of pancreatic carcinoma. (C) 2009 The WJG Press and Baishideng. All rights reserved.