靶向性抗癌蛋白色素上皮衍生因子在肿瘤中的研究进展

在肿瘤靶向治疗研究中,抗血管生成治疗是近十年来的一个研究热点.目前已有许多血管生成抑制剂应用于临床试验中.色素上皮衍生因子(PEDF)是一个能有效抑制新生血管形成的蛋白,与血管内皮生长因子(VEGF)等共同调控新生血管的发生过程.PEDF表达和抑制肿瘤生长、减少转移、良好的预后相关,对PEDF的深入研究有助于发挥其在肿瘤治疗中的作用.     

色素上皮衍生因子对角膜碱烧伤后新生血管形成的抑制

背景：角膜新生血管导致角膜透明性降低,造成严重的视觉障碍。色素上皮衍生因子是一种内源性血管生成抑制剂,其对于角膜新生血管是否具有抑制作用尚不清楚。 目的：探索局部运用色素上皮衍生因子对大鼠角膜碱烧伤后角膜新生血管的抑制作用。 方法：将20只大鼠随机分为生理盐水组与色素上皮衍生因子组,每组10只。用NaOH溶液将大鼠右眼角膜烧伤诱导产生新生血管。碱烧伤后2组每日分别给予生理盐水和色素上皮衍生因子点眼,并采用裂隙灯显微镜观察和测量各组角膜新生血管生长情况。碱烧伤后12 d处死大鼠,将角膜组织固定切片,行苏木精-伊红染色观察,并进行免疫组织化学染色检测各组大鼠角膜血管内皮生长因子和CD31的表达。 结果与结论：大鼠角膜碱烧伤后3,7,12 d,色素上皮衍生因子组大鼠角膜新生血管面积均小于生理盐水组(P < 0.05)。角膜碱烧伤后12 d,苏木精-伊红染色显示生理盐水组大鼠角膜产生大量新生血管,角膜组织结构紊乱;色素上皮衍生因子组新生血管较少,角膜组织结构趋于整齐。角膜碱烧伤后12 d,免疫组织化学染色示生理盐水组大鼠角膜上皮和基质层可见血管内皮生长因子大量表达,角膜基质层可见血管内皮生长因子和CD31大量表达;色素上皮衍生因子组新生血管稀少,CD31表达较弱。证实局部应用色素上皮衍生因子可有效抑制大鼠角膜化学伤后的血管新生。     

Changes in pigment epithelium-derived factor expression following kainic acid induced cerebellar lesion in rat

Pigment epithelium-derived factor (PEDF) is a potent and broad-acting neurotrophic factor that protects various types of cultured neurons against glutamate excitotoxicity and induced apoptosis. The expression pattern and functions of PEDF in the central nervous system (CNS) remain largely undetermined. In this study, we analyzed the spatial and temporal expression of PEDF in normal and kainic acid (KA)-induced lesioned rat cerebellum using immunoblotting, immunohistochemistry and fluorescent in situ hybridization techniques. In normal rat cerebellum, PEDF protein and mRNA were mostly confined and co-localized with calbindin-positive cells in the Purkinje cell layer of the cerebellum, but not with glial fibrillary acidic protein (GFAP)-, 2′, 3′-cyclic nucleotide 3′-phosphodiesterase (CNPase)-, and isolectin B4-positive cells. Injection of KA into the right cellebellum caused severe loss of calbindin-positive Purkinje neurons, and an increased number of GFAP-positive astrocytes and isolectin B4-positive microglia was observed on the ipsilateral side of the lesioned cerebellum. Although the PEDF level on the ipsilateral side of the cerebellum was dramatically decreased 2 days after KA treatment, significantly elevation of PEDF levels was observed at 7 days. In agreement with these results, PEDF protein and PEDF mRNA expression were co-localized with GFAP-positive reactive astrocytes in the ipsilateral side 7 days after KA treatment. Although the mechanism by which PEDF is induced in reactive astrocytes remains unclear, the increase in PEDF expression in injured brain may form part of a compensation mechanism against neuronal degeneration.     

色素上皮衍生因子在肿瘤中的研究进展

色素上皮衍生因子(PEDF)作为丝氨酸蛋白酶抑制剂超家族成员,通过抑制内皮细胞的增殖和迁移、诱导相关的凋亡信号通路和增加肿瘤细胞分化程度,从而发挥抑制肿瘤发生、发展及其转移的生物学功能.研究表明,PEDF在骨骼的正常生理和病理过程发挥重要调节作用.PEDF为基础的免疫治疗方法可以成功的用于治疗骨肉瘤(OS),并极大抑制了OS的进展和控制肺部转移.     

菩人丹超微粉对糖尿病大鼠视网膜血管内皮生长因子和色素上皮衍生因子表达的影响

目的 探讨菩人丹超微粉(PRD)对糖尿病大鼠视网膜血管内皮生长因子(VEGF)及色素上皮衍生因子(PEDF)表达的影响.方法 48只Wistar大鼠随机分为4组:正常对照组、糖尿病模型组、PRD组和导升明组,每组12只.糖尿病模型组、PRD组和导升明组大鼠均采用链脲佐菌素连续腹腔注射建立2型糖尿病大鼠模型.模型成功建立...     

色素上皮细胞衍生因子表达载体的构建

目的 构建色素上皮细胞衍生因子（PEDF）的表达载体。方法 从孕8周的胚胎绒毛中提取总RNA，经RTPCR扩增，获得编码人PEDF的全基因序列，采用T-A克隆法，将PEDF基因克隆入PMD18-T中间载体并转化人大肠杆菌E．coli JM109中，提取重组质粒并酶切鉴定，将鉴定正确的质粒命名为PMD18-T／PEDF，DNA测序，测序正确后构建重组表达载体pET28a／PEDF，转化大肠杆菌E．coli DH5α并酶切鉴定。结果 重组表达载体pET28a／PEDF在大肠杆菌E．coli DH5α中克隆表达。结论 构建了PEDF重组表达载体pET28a／PEDF，为重组PEDF的进一步表达及纯化奠定了基础。     

Pigment epithelium derived factor (PEDF) prevents methyl methacrylate monomer-induced cytotoxicity in H9c2 cells

Acrylic bone cements are currently the most frequently and extensively used materials in orthopedic implant treatment. However, adverse effects have been described of acrylic bone cement on the cardiovascular system. In the present study, we examined the cytotoxicity of bone cement ingredient methyl methacrylate (MMA) to cardiomyocytes and the potential detoxifying effect of pigment epithelium-derived factor (PEDF) in H9c2 cells. We found that high concentration of MMA ( > 120 mmol/L) led to necrotic cell death in H9c2 cells. However, MMA at low concentrations (30-90 mmol/L) caused apoptosis. Pretreatment of PEDF prevented MMA-induced cytotoxicity. In addition, PEDF enhanced total superoxide dismutase activities, and decreased MMA-induced production of malonaldehyde. Furthermore, MMA-induced downregulation of Akt activity was suppressed by PEDF. PEDF also increased the levels of peroxisome proliferator activated receptor gamma (PPARg) and lysophosphatidic acids (LPA) through PEDF receptor. These results indicated that PEDF inhibited MMA-induced cytotoxicity through attenuating oxidative stress, activating the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and/or PEDF receptorLPA-PPARg pathways in H9c2 cells. PEDF may be explored as a candidate therapeutic agent for alleviating bone cement implantation syndrome during orthopedic surgery.     

异搏定和肿瘤坏死因子α协同抗肿瘤作用的实验研究

目的:研究异搏定和肿瘤坏死因子α(TNFα)对肝癌的协同作用。方法:利用人肝癌HepG₂体外培养及裸鼠皮下移植模型,在异搏定、肿瘤坏死因子以及异搏定和肿瘤坏死因子同时存在的条件下,观察肿瘤细胞增殖及肿瘤组织生长状况、c-myc表达肿瘤组织的细胞增殖核抗原(PCNA)检验以及肿瘤组织微血管密度(MVD)的比较。结果:在异搏定以及异搏定和TNFα同时存在的条件下,HepG₂的增殖及移植肿瘤的生长受到明显抑制;c-myc的表达、PCNA的表达以及MVD明显降低。结论:钙通道阻滞剂可抑制肿瘤的增殖与生长;异搏定与TNFα有显著的协同抗肿瘤作用。     

Pigment epithelium derived factor (PEDF) is neuroprotective in two in vitro models of Parkinson's disease

Transplantation of retinal pigment epithelial (RPE) cells in the basal ganglia has been proposed as a novel cell-based therapy for Parkinson's disease (PD), by providing a constant source of dopamine replacement via the melanin synthetic pathway enzyme tyrosinase. We have demonstrated previously that human RPE cells also produce a neurotrophic effect on primary cultures of rat striata mesencephalic (dopaminergic) neurons and showed that pigment epithelium derived factor (PEDF) accounted for a major portion of the neurotrophic effect. We now have also begun studies that demonstrate that the neurotrophic effect of PEDF corresponds to neuroprotection against toxins used to produce experimental PD. This was shown in (1) rotenone and (2) 6-hydroxydopamine (6-OHDA) in vitro models. The toxins were added at day 10 in culture, PEDF was added 1 h prior. The cultures were fixed and analyzed after tyrosine hydroxylase (TH) immunocytochemical staining. Cell count of TH+ neurons clearly shows the neuroprotective potential of PEDF in both neurotoxin models. The neurotoxic effect of rotenone (25 nM) on dopaminergic neurons is reversed by addition of PEDF. At a concentration of 1 ng/ml PEDF the neurotoxic effect of rotenone is completely counteracted. PEDF (1 ng/ml) has also a neuroprotective effect in the 6-OHDA midbrain in vitro model. The effect is most pronounced at concentrations of 25 μM and 50 μM 6-OHDA. We conclude that the neurotrophic factor PEDF, produced from RPE cells, can improve neuronal survival in models of PD, and plan to test if this effect can be observed using in vivo models of PD following RPE transplantation.     

Human decellularized adipose tissue scaffold as a model for breast cancer cell growth and drug treatments

Human adipose tissue extracellular matrix, derived through decellularization processing, has been shown to provide a biomimetic microenvironment for adipose tissue regeneration. This study reports the use of human adipose tissue-derived extracellular matrix (hDAM) scaffolds as a three-dimensional cell culturing system for the investigation of breast cancer growth and drug treatments. The hDAM scaffolds have similar extracellular matrix composition to the microenvironment of breast tissues. Breast cancer cells were cultured in hDAM scaffolds, and cell proliferation, migration, morphology, and drug responses were investigated. The growth profiles of multiple breast cancer cell lines cultured in hDAM scaffolds differed from the growth of those cultured on two-dimensional surfaces and more closely resembled the growth of xenografts. hDAM-cultured breast cancer cells also differed from those cultured on two-dimensional surfaces in terms of cell morphology, migration, expression of adhesion molecules, and sensitivity to drug treatment. Our results demonstrated that the hDAM system provides breast cancer cells with a biomimetic microenvironment in vitro that more closely mimics the in vivo microenvironment than existing two-dimensional and Matrigel three-dimensional cultures do, and thus can provide vital information for the characterization of cancer cells and screening of cancer therapeutics.     

Erythropoietin as an angiogenic factor in gastric carcinoma

AIMS: Previous studies have shown that increased vascularity is associated with haematogenous metastasis and poor prognosis in gastric cancer. The role of erythropoietin (Epo) in angiogenesis has not been completely clarified, although its involvement has been reported. In this study we correlated microvascular density and Epo receptor (Epo-R) expression in endothelial and tumour cells with histopathological type in gastric cancer. METHODS AND RESULTS: Specimens of primary gastric adenocarcinomas obtained from 40 patients who had undergone curative gastrectomy were investigated immunohistochemically by using anti-CD31 and anti-Epo-R antibodies. Stage IV gastric carcinoma had a higher degree of vascularization than other stages, and Epo-R expression in both endothelial and tumour cells increased in parallel with malignancy grade and was highly correlated with the extent of angiogenesis. CONCLUSIONS: Epo-R level correlates with angiogenesis and progression of patients with gastric carcinoma and we suggest that Epo might have a trophic effect on the vasculature of the gastrointestinal tract. Understanding mechanisms of gastric cancer angiogenesis provides a basis for a rational approach to the development of an anti-angiogenic therapy in patients with gastric cancer.     

Tumor necrosis factor: Recent advances

Summary Tumor necrosis factor is a protein secreted by activated monocytes. In addition to its known cytotoxic or cytostatic effect on some tumor cells, recently it was discovered to have multiple effects on normal cells. These effects include modulation of cell growth and function, production of growth factors, and induction of surface antigens. In this article we review some of the advances which were made since the gene for tumor necrosis factor was cloned.Abbreviations CFU-GM Granulocyte-macrophage colonyforming unit - CSF Colony-stimulating factor - IL-1 Interleukin 1 - LT Lymphotoxin - TNF Tumor necrosis factor Supported in part by National Institutes of Health Grants CA 26038, CA 32737, CA 33936, and CA 30512, the Dr. Murray Geisler Memorial Leukemia Fund and the Louis Fagin Leukemia Research Foundation. Dr. Reinhold Munker is a Fellow of the Deutsche Forschungsgemeinschaft (Mu677/1-1). Dr. H. Phillip Koeffler is a member of the Jonsson Comprehensive Cancer Center, and holds a Career Development Award from the National Institutes of Health     

基因重组肿瘤坏死因子对LAK细胞体内外抗肿瘤作用的增强效果

TNF单独不能诱导LAK活性,也不能进一步提高最适剂量IL-2(1000U/ml)诱导的LAK活性,但能显著增强亚适剂量IL-2(10～100U/ml)诱导的LAK活性。抗TNF单抗和抗IL-2受体β链(p75)单抗显著抑制TNF/IL-2对LAK活性的协同诱导作用。实验证明,TNF能显著增强IL-2/LAK细胞的体内抗肿瘤效果,对于腹水型肝癌小鼠,以联合腹腔内注射TNF/IL-2/LAK细胞的体内抗肿瘤效果最佳。     

逆转录病毒介导的人TNF在人肝癌细胞系（SMMC）中的表达

利用逆转录病毒载体ＬＸＳＮ构建了含人ＴＮＦａ基因的重组逆转录病毒载体Ｌ－ｔｎｆＳＮ。磷酸钙沉淀法将重组载体引入病毒包装细胞ＰＡ３１７，挑选Ｇ４１８抗性克隆，用ＮＩＨ３Ｔ３细胞测定病毒滴度，获得滴度为１×１０５ＣＦＵ／ｍｌ的细胞克隆。应用这一重组病毒感染人肝癌细胞ＳＭＭＣ７７２１，经Ｇ４１８筛选获得抗性克隆。ＰＣＲ可从转导的细胞ＤＮＡ中扩增出ＴＮＦａ基因片段，提示目的基因完整地整合在细胞基因组中。测定转导细胞培养上清中ＴＮＦａ活性，结果显示ＴＮＦａ有相对稳定的表达（１５０～３７０Ｕ／１０６ｃｅｌｌｓ／２４小时）。实验还表明转导细胞的体外生长能力无明显变化，但是其在裸鼠中的致瘤性却明显降低，提示逆转录病毒介导ＴＮＦａ基因对人原发性肝场可能有一定的治疗作用。     

Vascular endothelial growth factor in tumor tissue and blood serum from patients with breast cancer

Enzyme immunoassay showed that the content of free vascular endothelial growth factor increases in tumor cytosols and blood serum from patients with breast cancer. A positive correlation was found between the contents of vascular endothelial growth factor in tumor cytosols and blood serum. After removal of the tumor the content of vascular endothelial growth factor decreased only in 49% patients. It should be emphasized that changes in these parameters did not depend on their initial values.     

Role of vascular endothelial growth factor during breast cancer

We review the results of experimental and clinical observations on neoangiogenesis in patients with breast cancer. Vascular endothelial growth factor is an important positive regulator of this process. Experiments showed the possibility of using various direct and indirect antiangiogenic means in the therapy of breast cancer, but clinical efficiency of these methods was not proved. Expression of vascular endothelial growth factor can serve as a prognostic criterion in breast cancer. Antiangiogenic preparations should not be used as monotherapy, but as the treatment complementary to standard therapy.     

Immunosuppressive role of transforming growth factor beta in breast cancer

Transforming growth factor beta (TGF-β) is a multifunctional cytokine, whose myriad of functions include its ability to potently suppress the immune system. Because of its ability to negatively modulate the inductive and effector phases of the immune response, TGF-β is thought to contribute to tumor progression and metastases formation. Immunosuppression by tumor-derived TGF-β is increasingly becoming recognized as an important factor in tumor progression and may, in part, explain the low response rates achieved in cancer patients undergoing immunotherapy for their disease. This review will focus on the immunosuppressive role of tumor-derived TGF-β in breast cancer. Due to the paucity of human studies, it will specifically address the actions of tumor-derived TGF-β on cells of the immune system in preclinical animal models, as well as discuss strategies to negate the deleterious effects of TGF-β in order to improve the anti-tumor immune response.     

Active immunotherapy of tumors with a recombinant xenogeneic endoglin as a model antigen

Angiogenesis play a critical role in tumor growth and metastasis. Increasing evidence suggests that endoglin is a powerful marker of angiogenesis in solid malignancies. Thus, breaking of immune tolerance of self-endoglin-associated angiogenesis is an attractive approach to cancer therapy. To test this concept, we recombined the extracellular domains of porcine endoglin, and used it as a xenogeneic vaccine. We found that immunotherapy with porcine endoglin was effective at both protective and therapeutic anti-tumor immunity in several mouse tumor models. Autoantibodies against mouse endoglin were identified by Western blot and ELISA. IgG1 and IgG2b were substantially increased. Anti-endoglin antibody-producing B cells were detectable by ELISPOT assay. There was endothelial deposition of immunoglobulins within tumors. The anti-tumor activity was also induced by the adoptive transfer of the purified immunoglobulins. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. The increased apoptotic cells were found within the tumor tissues from the mice treated with porcine endoglin. The anti-tumor activity and production of autoantibodies against mouse endoglin could be abrogated by depletion of CD4(+) T lymphocytes. Remarkably, no marked toxicity was found in the immunized mice. These observations may provide an alternative rational strategy for active cancer immunotherapy.