色素上皮衍生因子--肿瘤治疗的候选药物

色素上皮衍生因子（pigment epithelium—defived factor,PEDF）是一种具有神经营养保护、抑制新生血管增生和抑制肿瘤生长等作用的多功能蛋白质。体内外试验证明,PEDF通过抑制新生血管生成、诱导肿瘤细胞分化和抑制肿瘤细胞增殖及迁移等多个环节抑制肿瘤的生长,成为治疗肿瘤的候选药物。     

色素上皮细胞衍生因子

色素上皮细胞衍生因子(pigment epithelium-derived factor,PEDF)最初从视网膜色素上皮细胞分离,是维持角膜、玻璃体无血管状态的主要血管增生抑制因子。体内外试验证明：PEDF具有高效的抗血管生成活性,成为治疗血管增生性疾病的候选药物。     

氯化钴对原代大鼠肺动脉成纤维细胞的影响

目的:探究氯化钴对于原代大鼠肺动脉成纤维细胞(PAF)的增殖、迁移、表型转化作用的影响。方法:分离培养大鼠肺动脉成纤维细胞,利用氯化钴刺激PAF细胞,并通过MTT、细胞划痕、Transwell、表型转化标志蛋白测定以及PI3K/Akt信号通路蛋白的变化研究氯化钴对PAF的影响。结果:MTT结果显示,与对照组相比,氯化钴可以抑制大鼠肺动脉成纤维细胞的增殖活性(P0.001),并呈浓度依赖性。划痕实验及Transwell实验提示较高氯化钴(200μmol·L~(-1))处理PAF细胞后可以抑制细胞迁移。随浓度增加,氯化钴可以抑制PAF的P110α、p-Akt蛋白表达。结论:氯化钴对于体外培养的原代大鼠肺动脉成纤维细胞的增殖、迁移和表型转化特性有一定的抑制作用,这可能与氯化钴抑制PI3K/Akt信号通路的表达有关。     

矽肺成纤维细胞增生因子的纯化及分析

过去的研究资料充分证明,巨噬细胞和由巨噬细胞释放的可溶性因子在矽肺纤维化过程中起着重要的调节作用。然而,对这种调节矽肺纤维化过程的蛋白因子的理化特性迄今还知道得很少。本研究采用矽肺大鼠肺泡巨噬细胞体外培养的方法获得其培养上清液,实验证明,该上清液可以促进体外培养的成纤维细胞对~3H-TdR和~3H-脯氨酸的摄取。我们从巨噬细胞上清液中分离纯化出一种具有促进成纤维细胞增殖能力的蛋白质因子。该因子在聚丙烯酰胺凝胶电泳上显示单个带谱,在SDS-聚丙烯酰胺凝胶电泳上测得分子量为66kD,在pH3-11的等电聚焦电泳上测得该因子的等电点为4.72。我们认为这种具有成纤维细胞增生因子活性的蛋白质可能就是在矽肺纤维化过程中刺激成纤维细胞增殖和胶原合成的调节因子。     

糖尿病大鼠牙周膜成纤维细胞组织中TNF-α的表达及意义

目的:通过检测TNF-α在糖尿病大鼠牙周组织中的表达情况,探讨高糖环境下肿瘤坏死因子与口腔疾病发生发展的关系,为临床治疗提供理论依据。方法:选取SD大鼠40只,随机分为实验组(30只)和对照组(10只)。实验组采取腹腔注射链脲佐菌素的方法建立糖尿病大鼠模型,观察大鼠牙周组织的变化情况。采用RT-PCR法检测两组大鼠牙周膜成纤维细胞中TNF-α的表达水平,CCK-8法测定大鼠牙周膜成纤维细胞的增殖情况,分析TNF-α对PDLFs增殖的抑制作用。结果:实验组大鼠牙周组织胶原纤维束排列紊乱,有炎症细胞浸润;对照组大鼠牙龈未见红肿或出血。TNF-α在糖尿病大鼠牙周膜成纤维细胞中呈高表达,在健康大鼠牙周组织中不显著,差异具统计学意义(P0.05)。TNF-α可抑制PDLFs增殖,并且成浓度依赖性,随着浓度的增加,TNF-α对PDLFs增殖的抑制作用逐渐增强,差异具统计学意义(P0.05)。结论:糖尿病可增加牙周疾病的发病几率,糖尿病患者体内的TNF-α对牙周疾病的严重程度起重要作用。     

糖尿病大鼠牙周膜成纤维细胞组织中TNF-α的表达及意义

目的：通过检测TNF-α在糖尿病大鼠牙周组织中的表达情况,探讨高糖环境下肿瘤坏死因子与口腔疾病发生发展的关系,为临床治疗提供理论依据。方法：选取SD大鼠40只,随机分为实验组（30只）和对照组（10只）。实验组采取腹腔注射链脲佐菌素的方法建立糖尿病大鼠模型,观察大鼠牙周组织的变化情况。采用RT-PCR法检测两组大鼠牙周膜成纤维细胞中TNF-α的表达水平,CCK-8法测定大鼠牙周膜成纤维细胞的增殖情况,分析TNF-α对PDLFs增殖的抑制作用。结果：实验组大鼠牙周组织胶原纤维束排列紊乱,有炎症细胞浸润;对照组大鼠牙龈未见红肿或出血。TNF-α在糖尿病大鼠牙周膜成纤维细胞中呈高表达,在健康大鼠牙周组织中不显著,差异具统计学意义（P〈0.05）。TNF-α可抑制PDLFs增殖,并且成浓度依赖性,随着浓度的增加,TNF-α对PDLFs增殖的抑制作用逐渐增强,差异具统计学意义（P〈0.05）。结论：糖尿病可增加牙周疾病的发病几率,糖尿病患者体内的TNF-α对牙周疾病的严重程度起重要作用。     

重组人色素上皮细胞衍生因子融合蛋白的制备及其抑制新生血管

目的：人色素上皮细胞衍生因子 (pigment epithelium-derived factor, PEDF)是一种有效的新生血管形成抑制因子和神经营养因子。本文通过原核细胞表达人PEDF蛋白,鉴定其抑制新生血管的生物学活性。方法：采用PCR法扩增人PEDFcDNA,将其克隆到pET32a载体中,在大肠杆菌BL21中表达人PEDF蛋白。经SDS-PAGE和Western-blot鉴定后,镍柱亲和层析法变性条件下纯化重组融合蛋白。Bradford法测蛋白浓度,采用鸡胚脲囊膜法测其对新生血管形成的影响。结果：成功构建了pET32a-PEDF表达载体。重组人PEDF蛋白在BL21宿主菌中获得了稳定高效表达,鸡胚脲囊膜实验结果显示在重组蛋白浓度为0.4、0.04 ng/ml时均有对新生血管的显著抑制作用（P<0.01）,而在4 ng/ml时无抑制作用。结论： 成功高效表达及纯化了重组人PEDF蛋白,鉴定其抑制新生血管的生物学活性,并且证实该活性在一定范围内有效,为进一步研究其功能及推广应用奠定了基础。     

载脂蛋白E基因敲除小鼠血管外膜成纤维细胞G蛋白信号调节因子3,5的表达变化

目的:检测载脂蛋白E基因敲除小鼠(apoE(-/-))血管外膜成纤维细胞中G蛋白信号调节因子(regulator of G protein signaling,RGS)3,5的变化,探讨其在动脉粥样硬化发病中的作用.方法:体外培养高脂喂养2周的apoE(-/-)小鼠和C57BL/6小鼠动脉外膜成纤维细胞,利用基因芯片技术分析RGS3,RGS5mRNA的变化,通过RT-PCR进一步验证.结果:基因芯片数据分析显示,apoE(-/-)小鼠成纤维细胞中RGS3表达下调,与C57BL/6小鼠比值为0.46.RGS5表达上调,与C57BL/6小鼠比值为2.25.RT-PCR结果显示apoE(-/-)小鼠成纤维细胞RGS3mRNA水平低于对照组小鼠(比值为0.78),RGS5mRNA水平高于对照组小鼠(比值为2.34),与基因芯片检测结果相比,变化方向一致.结论:apoE(-/-)小鼠血管外膜成纤维细胞中选择性RGS3降低和RGS5升高可能与外膜成纤维细胞的激活密切相关,从而参与了动脉粥样硬化的发生与发展,RGS有可能成为动脉粥样硬化药物治疗及基因治疗的新靶点.     

Involvement of the collagen I-binding motif in the anti-angiogenic activity of pigment epithelium-derived factor

Pigment epithelium-derived factor (PEDF) is the most potent endogenous inhibitor of angiogenesis in age-related macular degeneration and tumors. However, the molecular mechanism of the anti-angiogenic activity of PEDF is poorly understood. PEDF interacts with the extracellular matrix (ECM) in vitro. Here, we investigated the possible involvement of the motif for ECM interaction in the anti-angiogenic activity of PEDF. The growth rates of HeLa cells in culture were not affected by transfection of PEDF, indicating that PEDF did not suppress tumor cell growth directly. In tumor xenografts, the overexpression of wild-type PEDF significantly suppressed tumor growth, whereas a mutant of the collagen I-binding site of PEDF (Col-mut PEDF) did not inhibit tumor growth. A mutant of the heparin-binding site of PEDF (Hep-mut PEDF) suppressed tumor growth. Histological analysis showed that the density and area of microvasculatures in either PEDF or Hep-mut PEDF were suppressed when compared with those in either vector or Col-mut PEDF. Our data indicate that PEDF inhibits tumor growth via its anti-angiogenic activity, and the collagen I-binding motif of PEDF is involved in the biological activity.     

Pigment epithelium-derived factor inhibits glioma cell growth in vitro and in vivo

Glioblastoma multiforme is the most common malignant brain tumor in adults, and it is among the most lethal of all cancers. Recent studies have shown that pigment epithelium-derived factor (PEDF) can induce differentiation and inhibit angiogenesis of several tumors. This study was designed to determine whether gliomas angiogenesis and tumor growth could be inhibited by PEDF. We found that PEDF down-regulated expression levels of vascular endothelial growth factor and up-regulated the expression of thrombospondin-2 and augmented apoptosis in a dose-dependent manner in both A172 and U87 glioma cells lines after 48 h of treatment. Analysis of the cell cycle showed arrest in the G₁ phase and block in S phase of the cell cycle. Meanwhile PEDF induced apoptosis was associated with increases of p53 and Bax and inhibition of Bcl-2. Conditioned medium with PEDF showed a significantly reductive effect on migration in vitro accompanied with a significant reduction of matrix metalloproteinase-9 expression. PEDF suppressed glioma cell migration in vitro and tumor burden in athymic nude mice. These results demonstrate for the first time inhibitory effects of PEDF on the growth and migration of human gliomas via induction of apoptosis and blocking of migratory-related factors. PEDF activation can be a novel approach for future therapeutic purposes against gliomas.     

Pigment epithelium-derived factor expression prolongs survival and enhances the cytotoxicity of low-dose chemotherapy in castration-refractory prostate cancer

There is currently no cure for advanced castration-refractory prostate cancer (CRPC) despite the recent approval of several new therapeutic agents. We report here the anti-tumor effect of the angio-inhibitory pigment epithelium-derived factor (PEDF) in the metastatic LNCaP-derivative CRPC CL1 model and explore PEDF anti-neoplasic efficacy in combination with low-dose chemotherapy. Androgen-sensitive LNCaP and CRPC PC3 cell lines were examined as comparison. Using a retroviral expression system, we showed that PEDF limited the proliferation of all prostatic cell lines tested; an effect attributed to interleukin 8 (IL8)-CXCR1/IL8RA inhibition. PEDF also reduced the number and size of 3D tumor spheroids in vitro, but only induced cell differentiation in CRPC spheroids. Similarly, PEDF inhibited the migration of CRPC cells suggesting both anti-proliferative and anti-migratory functions. In vivo, PEDF decreased by 85% and 65% the growth of subcutaneous (s.c.) PC3 and CL1 tumors, respectively. In the CL1 orthotopic model, tumor intake with lethal metastases was found in all animals; nevertheless, PEDF prolonged the median survival of tumor-bearing mice (95% confidence interval: 53±0.001 to 57±1 days). Accordingly, PEDF delayed the emergence of skeletal-related event in intra-tibial xenografts. Next, we evaluated low-dose docetaxel (DTX; 5, 1, 0.5 mg/kg) or cyclophosphamide (CTX; 10–20 mg/kg) on established s.c. PC3 tumors that conditionally express PEDF anti-tumoral epitope/NT3. Although NT3–DTX-5 mg/kg combination was inefficient, NT3–DTX-1 mg/kg and -0.5 mg/kg inhibited by 95% and 87.8%, respectively, tumor growth compared with control and induced tumor stasis. Both NT3–CTX combinations were advantageous. Inversely, PEDF–DTX-5 mg/kg and PEDF–CTX-10 mg/kg delayed the most CL1 tumor growth (15, 11 and 5 days for PEDF–DTX-5 mg/kg, PEDF–CTX-10 mg/kg and single treatments, respectively) with elevated apoptosis and serum thrombospondin-1 as possible mechanism and marker, respectively. As well, both PEDF–CTX-10 mg/kg and PEDF–DTX-5 mg/kg prolonged significantly the survival of tumor-bearing mice compared with single treatments. Metastases were reduced in PEDF–DTX-5 mg/kg compared with other treatments, suggesting that PEDF–DTX delayed metastases formation. Our results advocate that PEDF/low-dose chemotherapy may represent a new therapeutic alternative for CRPC.     

Recombinant human pigment epithelium-derived factor (PEDF): characterization of PEDF overexpressed and secreted by eukaryotic cells.

Pigment epithelium-derived factor (PEDF) is a serpin found in the interphotoreceptor matrix of the eye, which, although not a proteinase inhibitor, possesses a number of important biological properties, including promotion of neurite outgrowth and differential expression in quiescent versus senescent states of certain cell types. The low amounts present in the eye, together with the impracticality of using the eye as a source for isolation of the human protein, make it important to establish a system for overexpression of the recombinant protein for biochemical and biological studies. We describe here the expression and secretion of full-length glycosylated human recombinant PEDF at high levels (> 20 micrograms/ mL) into the growth medium of baby hamster kidney cells and characterization of the purified rPEDF by circular dichroism and fluorescence spectroscopies and neurite outgrowth assay. By these assays, the recombinant protein behaves as expected for a correctly folded full-length human PEDF. The availability of milligram amounts of PEDF has permitted quantitation of its heparin binding properties and of the effect of reactive center cleavage on the stability of PEDF towards thermal and guanidine hydrochloride denaturation.     

Role of pigment epithelium-derived factor in the involution of hemangioma: Autocrine growth inhibition of hemangioma-derived endothelial cells

Hemangioma is a benign tumor derived from abnormal blood vessel growth. Unlike other vascular tumor counterparts, a hemangioma is known to proliferate during its early stage but it is followed by a stage of involution where regression of the tumor occurs. The critical onset leading to the involution of hemangioma is currently not well understood. This study focused on the molecular identities of the involution of hemangioma. We demonstrated that a soluble factor released from the involuting phase of hemangioma-derived endothelial cells (HemECs) and identified pigment epithelium-derived factor (PEDF) as an anti-angiogenic factor that was associated with the growth inhibition of the involuting HemECs. The growth inhibition of the involuting HemECs was reversed by suppression of PEDF in the involuting HemECs. Furthermore, we found that PEDF was more up-regulated in the involuting phase of hemangioma tissues than in the proliferating or the involuted. Taken together, we propose that PEDF accelerates the involution of hemangioma by growth inhibition of HemECs in an autocrine manner. The regulatory mechanism of PEDF expression could be a potential therapeutic target to treat hemangiomas.     

Production of active pigment epithelium-derived factor in<Emphasis Type="Italic">E. coli</Emphasis>

Human pigment epithelium-derived factor (PEDF), a neurotrophic factor, is the most potent natural inhibitor of angiogenesis. To produce the active PEDF, the gene coding for the human PEDF protein was expressed in E. coli. The rPEDF protein was expressed at 457 mg l^–1 as a soluble protein. The yield of purified GST fusion protein was 14 mg ll^–1. Purified rPEDF inhibited tube formation in endothelial cells.Revisions requested 30 November 2004; Revisions received 25 January 2005     

Pigment epithelium-derived factor is differentially expressed in peripheral neuropathies

Peripheral neuropathies are characterized by asymmetrical slowly progressive weakness with no upper motor neuron signs, and can occur either with or without pain. Due to poor knowledge of the disease mechanisms, available pain treatment is very limited. Because of the difficulties and invasiveness involved when performing direct analysis on peripheral and CNS, pathological markers can be searched for in the cerebrospinal fluid (CSF) as an alternative. To investigate pain mechanisms in peripheral neuropathy and find diagnostic markers, CSF samples were analyzed by a differential expression proteomic approach. We studied CSF from: neuropathic patients with pain (PN), without pain (NPN) and healthy controls (CN). 2-DE analysis showed ten protein spots differentially expressed, and six of these were identified by MS. In NPN patients we found an expression level decrease of three pigment epithelium-derived factor (PEDF) protein isoforms. Immunoblot with a specific antibody revealed the presence of additional PEDF isoforms not highlighted by differential expression analysis. Fucose residues on the oligosaccharide chain were found only in the isoforms down regulated in NPN patients. Considered as PEDF has important neurobiological effects, it might be considered an interesting pathology marker.     

Pigment epithelium-derived factor is elevated in CSF of patients with amyotrophic lateral sclerosis

Pigment epithelium-derived factor (PEDF), a recently defined retinal trophic factor and anti-angiogenic factor for the eye, is also present in the CNS and is a motor neuron protectant. We asked whether PEDF levels in CSF are altered in patients with amyotrophic lateral sclerosis (ALS). Pigment epithelium-derived factor protein was detected by quantitative western blot analysis with a PEDF-specific antiserum. Levels of PEDF in CSF, expressed as a ratio to total CSF protein, were significantly elevated 3.4-fold in 15 patients with ALS compared with neurologic disease controls (p < 0.0003). This increase does not seem likely to reflect up-regulation of PEDF synthesis in muscle in response to denervation, as CSF PEDF was not elevated in severe denervating diseases other than ALS. Nor does the increase represent some non-specific release in neurodegeneration, as CSF PEDF was not elevated in other neurodegenerative diseases. While the mechanism of this presumably reactive increase is not known, the distinctive, surprisingly elevated level of PEDF in the CSF may be an autoprotective reaction in ALS.