Platelet-derived endothelial cell growth factor: structure and function.

Platelet-derived endothelial cell growth factor (PD-ECGF) is a 45-kDa single chain polypeptide, which stimulates the growth and chemotaxis of endothelial cells in vitro and angiogenesis in vivo. Purification from human platelets and cDNA cloning of PD-ECGF disclosed that it is a novel type of angiogenic factor without sequence similarity to hitherto known proteins. PD-ECGF is present in human platelets as well as in placenta. Amino acid sequencing of PD-ECGF from human placenta revealed that the placental form has an additional 5 amino acids at the N-terminus. In cultured cells, it is produced by normal fibroblasts as well as some transformed cell lines. PD-ECGF lacks a hydrophobic signal sequence and remains inside the producer cells. PD-ECGF may act at sites of injury as a wound hormone and thus play an important role under several physiological and pathological conditions.     

Synthesis and secretion of proteins resembling platelet-derived growth factor by human glioblastoma and fibrosarcoma cells in culture.

Immunoprecipitation of proteins extracted from metabolically labeled human glioblastoma and fibrosarcoma cells with antiserum to platelet-derived growth factor (PDGF) showed that these cells express and secrete proteins that are recognized specifically by the antiserum. The molecular masses of immunoprecipitated proteins in the lysates of the malignant cells ranged from 16 kDa to 140 kDa. Both cell lines secreted a 31-kDa polypeptide with structural, immunological, and biological properties similar to those of human PDGF. These cell lines were shown to synthesize a 4.4-kb mRNA that contained sequences from all the six currently identified exons of the human c-sis gene. These data suggest that the PDGF-like proteins in the two mesenchyme-derived transformed cells are encoded at least in part by the c-sis locus.     

A large cell-adhesive scatter factor secreted by human gastric carcinoma cells.

Human gastric carcinoma cell line STKM-1 secretes a large protein that induces scattering of a rat liver epithelial cell line (BRL) into disconnected individual cells in monolayer culture. This cell-scattering factor was purified from serum-free conditioned medium of STKM-1 cells and found to be composed of three disulfide-linked subunits of 140, 150, and 160 kDa. The 140-kDa peptide contains an amino acid sequence homologous to that of the laminin B2t chain. The native protein has an apparent molecular mass of > 1000 kDa and a pI of 5.0. In addition to the cell-scattering activity, the purified protein stimulates attachment of BRL cells to substrate and their migration. Similar effects have been observed toward various cell lines, including nontumorigenic epithelial, endothelial, and fibroblastic cell lines and human cancer cell lines. Similar cell-scattering activity was secreted by human squamous carcinoma and gastric carcinoma cell lines and nontumorigenic epithelial and endothelial cell lines. These results indicate that the protein, named "ladsin," is probably an extracellular matrix protein that regulates cell-cell and cell-substrate interactions and cell migration.     

Expression of platelet-derived endothelial cell growth factor in inflammatory bowel disease

Background: Platelet-derived endothelial cell growth factor (PD-ECGF) is reported to be highly expressed in tumors and inflammatory tissues, but its expression and role in inflammatory bowel disease (IBD) are still unclear. In this study we examined the location and tissue density of cells immunoreactive for PD-ECGF in the colonic mucosa of IBD. Methods: Paraffin-embedded sections of colonic tissue from patients with ulcerative colitis (UC) or Crohn's disease (CD) were immunostained for PD-ECGF. As controls, noninflamed mucosa of IBD, as well as normal colonic mucosa from patients with colorectal cancer, were used. Also, cancer tissues were evaluated. In addition, changes in the expression of PD-ECGF in human umbilical vein endothelial cells (HUVEC) after treatment with inflammatory cytokines and angiogenic factors, as well as after coculture with colon cancer cell lines, were evaluated by flow cytometry. Results: In normal colonic mucosa and noninflamed mucosa of IBD, PD-ECGF expression was negligible. In inflamed colonic mucosa, strong expression was observed, predominantly in macrophages and fibroblasts. Vascular endothelial cells of the inflamed colonic mucosa, but not of normal colonic mucosa or of neoplastic tissues, stained for PD-ECGF, and the microvessel density was significantly increased in the severely inflamed mucosa. Flow cytometry demonstrated that PD-ECGF was constitutively expressed in HUVEC. Inflammatory cytokines and vascular endothelial growth factor (VEGF) increased its expression, whereas basic fibroblast growth factor (bFGF) decreased it. Coculture with colon cancer cell lines in direct contact, but not in those without contact, also resulted in an important decrease in the expression of PD-ECGF in HUVEC. Conclusions: Autocrine production of PD-ECGF by endothelial cells may be a mechanism of inflammatory angiogenesis, but not tumor angiogenesis, and may be particularly important for the maintenance of damaged vasculature in IBD. Received: September 17, 2001 / Accepted: September 6, 2002 Acknowledgments. This study was supported partly by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and partly by a grant from the Ministry of Health, Labour, and Welfare of Japan. Reprint requests to: S. Saito, Present address: Department of Surgery, Chigasaki Municipal Hospital, 5-15-1 Honson, Chigasaki 253-0042, Japan     

胃癌组织血小板衍化内皮细胞生长因子的表达与血管生成和凋亡的关系

目的探讨血小板衍化内皮细胞生长因子（PD．ECGF）在胃癌组织中的表达及与血管生成和凋亡的关系。方法应用免疫组化技术对67例胃癌组织进行PD－ECGF表达、肿瘤组织微血管密度（MVD）检测，流式细胞技术检测胃癌组织细胞凋亡指数（川，凋亡百分率八结果＊r＊＊＊F的表达与胃癌淋巴结转移（P＜0．oj）。分化程度（P＜0．05）及组织分型（P＜0．05）显著相关，与＊V则尸＜001）和胃癌细胞凋亡指数（P＜001）显著相关。＊＊D和＊1与淋巳结转移（P＜001）显著相关。结论胃癌组织中P＊。 ECGF可促进血管生成，抑制胃癌细胞凋亡，促进胃癌的增殖与转移。     

血管内皮生长因子与血小板衍化内皮细胞生长因子在老年人胃癌组织中的表达

目的　探讨老年人胃癌术前活检标本血管内皮生长因子 (VEGF)和血小板衍化内皮细胞生长因子 (PD ECGF)的表达及其与老年胃癌患者预后的关系。　方法　采用免疫组化法检测 92例老年胃癌VEGF、PD ECGF表达情况 ,并分析它们与胃癌临床病理特征关系及对预后的影响。　结果　VEGF、PD ECGF在胃癌组织的表达明显高于慢性萎缩性胃炎 ,进展期癌的表达又高于早期癌(P <0 0 1) ,VEGF、PD ECGF表达呈显著正相关 (相关系数R =0 4 0 5 4 )。VEGF、PD ECGF的阳性表达随着肿瘤大小、浸润深度、TNM分期的递增而呈上调表达 ,有淋巴结转移、血管癌栓的患者表达也明显高于无淋巴结转移、血管癌栓者 (P <0 0 1)。VEGF、PD ECGF阳性表达者总体生存率明显低于VEGF、PD ECGF阴性表达者 (P <0 0 1) ,VEGF、PD ECGF共同表达者生存率更低 (P <0 0 1)。多因素分析表明 ,淋巴结转移、TNM分期、VEGF的表达是老年人胃癌独立的预后因素。　结论　VEGF与PD ECGF表达呈正相关 ,均与胃癌生长、浸润转移关系密切 ,可作为估计老年人胃癌预后的重要因素。     

Platelet-derived endothelial cell growth factor inhibits DNA synthesis in vascular smooth muscle cells

Platelet-derived endothelial cell growth factor (PD-ECGF) is linked to angiogenesis in human cancer. Direct studies have demonstrated that PD-ECGF is a potent mitogen for endothelial cells in vivo. Because endothelial repair and smooth muscle cell proliferation are two processes that affect arterial wall structure and tone, we analyzed the effects of PD-ECGF on DNA synthesis and creatine kinase BB-specific activity (CK) in human umbilical artery smooth muscle cells (SMC) and in a human umbilical endothelial cell line (E304). In SMC, PD-ECGF (0.001 to 10 U/mL) inhibited DNA synthesis dose dependently (−24% + 6% to −63% + 15%) assessed by ³[H]thymidine incorporation into DNA, whereas in E304 it stimulated DNA synthesis dose dependently (30% + 4% to 100% + 4%). In both SMC and E304, however, PD-ECGF elicited an increase in CK-specific activity by 54% to 130% and 79% to 163%, respectively. These effects were reversed by a specific anti-PD-ECGF antibody. In E304 cells PD-ECGF enhanced 17β-estradiol (E₂) or dihydrotestosterone (DHT)-induced DNA synthesis from 56% to 122% and from 127% to 359%, and CK activity from 70% to 180% and from 90% to 190%, respectively. In SMC PD-ECGF, an inhibitor of ³[H]thymidine incorporation by itself, markedly enhanced the stimulatory effect of low concentrations of E₂ and DHT on ³[H]thymidine incorporation. It also increased E₂ and DHT CK induction from 40% to 140% and from 52% to 120%, respectively. In both E304 and SMC, PD-ECGF inhibited the proliferative and the CK-inducing effects of platelet-derived growth factor (PDGF) and immunoglobulin F₁ (IGF₁). Thus, PD-ECGF, an established growth promoter for endothelial cells, is a potent inhibitor of DNA synthesis in human arterial SMC. However, in both E304 endothelial cells and SMC, PD-ECGF enhances the stimulatory effect of low concentrations of gonadal steroids on ³[H]thymidine incorporation. PD-ECGF antagonizes PDGF- and IGF₁-induced DNA synthesis in both E304 and SMC cells. By inhibiting arterial SMC proliferation and accelerating endothelial cell replication, PD-ECGF may buffer the effect of PDGF and favorably modulate arterial wall response to injury.     

血小板衍化内皮细胞生长因子在胰腺癌组织中的表达及其临床意义

目的:观察血小板衍化内皮细胞生长因子(PD-ECGF)在胰腺癌组织中的表达,探讨其临床意义.方法:利用Elivison免疫组织化学法检测36例手术切除的胰腺癌及21例癌旁正常胰腺组织,以及胃癌、食管癌、肝癌、结肠癌、肺癌及乳腺癌组织各10例中PD-ECGF的表达.分析PD-ECGF与胰腺癌大小、分化程度及淋巴结转移的相关性.结果:PD-ECGF在胰腺癌组织中的表达阳性率显著高于在癌旁正常胰腺组织(88.9% vs 28.6%,P<0.01).PD-ECGF在结肠癌、肝癌、乳腺癌、食管癌、胃癌及肺癌组织中的表达阳性率为60%、70%、80%、90%、90%及80%.Ⅱ-Ⅳ期胰腺癌组织中PD-ECGF的表达阳性率显著高于Ⅰ期胰腺癌组织(100% vs 75%,P<0.05).结论:PD-ECGF为一种非特异性的肿瘤相关因子,其可能与胰腺癌的病程进展有关.     

The Fanconi anemia polypeptide FACC is localized to the cytoplasm.

Fanconi anemia (FA) is an autosomal recessive disease characterized by congenital anomalies, aplastic anemia, and chromosomal instability. A cDNA encoding the FA complementation group C (FACC) polypeptide was recently cloned [Strathdee, C. A., Gavish, H., Shannon, W. R. & Buchwald, M. (1992) Nature (London) 356, 763-767]. To further characterize this polypeptide, we generated a rabbit polyclonal antiserum against its carboxyl terminus. We used this antiserum to analyze the FACC polypeptide from normal or mutant (FA) lymphoblast cell lines. By immunoprecipitation, the wild-type FACC was a 60-kDa protein, consistent with its predicted molecular mass. FA group C cell lines expressed full-length FACC, truncated FACC, or no detectable FACC polypeptide. In addition, the antiserum specifically immunoprecipitated a 50-kDa and a 150-kDa FACC-related protein (FRP-50 and FRP-150). Unexpectedly, cell fractionation and immunofluorescence studies demonstrated that the FACC polypeptide localizes to the cytoplasm. In conclusion, we have generated an antiserum specific for the human FACC polypeptide. The antiserum should be useful for screening FA cells for mutant FACC polypeptides and for identifying and cloning FACC-related proteins.     

Vascular endothelial cell growth factor (VEGF) produced by A-431 human epidermoid carcinoma cells and identification of VEGF membrane binding sites.

A distinct family of endothelial cell mitogens that are homologous to platelet-derived growth factor has recently been identified. Unlike other known endothelial cell mitogens, these vascular endothelial cell growth factors (VEGFs) are secreted and appear to act specifically on endothelial cells. We have purified VEGF 2083-fold to apparent homogeneity from protein-free culture medium conditioned by A-431 human epidermoid carcinoma cells. This A-431-derived VEGF was characterized as a homodimer composed of 22-kDa subunits with an N-terminal sequence that was similar to VEGFs produced by human HL-60 leukemic and U-937 histiocytic lymphoma cells. A-431 VEGF was used to identify specific and saturable binding sites for VEGF on human umbilical vein endothelial cells (HUVEC). By affinity cross-linking, VEGF-binding site complexes of 230, 170, and 125 kDa were detected on HUVEC. VEGF specifically induced the tyrosine phosphorylation of a 190-kDa polypeptide, which was similar in mass to the largest binding site detected by affinity cross-linking.     

Platelet-derived endothelial cell growth factor/thymidine phosphorylase concentrations differ in small cell and non-small cell lung cancer.

OBJECTIVE: Platelet-derived endothelial cell growth factor (PD-ECGF)/thymidine phosphorylase (TP) has been implicated in cancer angiogenesis, which is critical for tumor growth and metastasis. We investigated the relationship between the tissue concentration of PD-ECGF/TP and the clinicopathologic status in human lung cancer. METHODS: The concentrations of PD-ECGF/TP in the tumor extracts of 139 primary human lung carcinomas were measured by using a highly specific and sensitive enzyme-linked immunosorbent assay. RESULTS: PD-ECGF/TP was detected in the extracts from 137 of 139 specimens at concentrations that ranged from 2.0 to 169.5 U/mg protein. PD-ECGF/TP concentrations in patients with adenocarcinoma (n = 73) and squamous cell carcinoma (n = 49) were (mean +/- SD) 30.7+/-22.9 U/mg protein (range, 7.6 to 169.5 U/mg protein) and 32.0+/-19.8 U/mg protein (range, 8.0 to 84.4 U/mg protein), respectively. No significant difference was found in the PD-ECGF/TP concentration between these two types of non-small cell lung cancer (NSCLC). However, a > 8-fold lower mean concentration of PD-ECGF/TP was found in tissue extracts from small cell lung cancer (SCLC) (n = 17; 3.65+/-2.01 U/mg protein, ranging from undetectable to 6.1 U/mg protein) than in those from adenocarcinomas (p = 0.00005) or squamous cell carcinomas (p < 0.00001). CONCLUSIONS: The striking difference in PD-ECGF/TP concentrations between SCLC and NSCLC suggests that these two types of lung cancer use alternative pathways for angiogenesis. The present study suggests that inhibitors of PD-ECGF/TP, which have been recently developed and are under laboratory investigation to test their effectiveness as treatments for various types of cancer, may not be effective against SCLC.     

A major endothelial plasmalemmal sialoglycoprotein, gp60, is immunologically related to glycophorin.

Glycophorins, the major sialoglycoproteins of red blood cells in many species, are generally considered to be specific to erythroid cells. Using polyclonal antibodies directed against mouse glycophorin (alpha gp), we have identified a glycoprotein antigenically related to glycophorin on the surface of bovine and rat cultured endothelial cells. Immunoblotting with alpha gp identified a single 60-kDa polypeptide on transfers of SDS/polyacrylamide gels of solubilized confluent endothelial monolayers. In addition, a 60-kDa polypeptide was immunoprecipitated by alpha gp from lysates of 125I-labeled intact endothelial cells. Controls with preimmune serum were negative. This antibody interaction was inhibited by murine erythrocyte ghosts and purified glycophorins. Our past work identified several endothelial surface sialoglycoproteins including a 60-kDa glycoprotein (gp60) that (i) interacts with albumin, (ii) binds Limax flavus, Ricinus communis, and Triticum vulgare agglutinins but not other lectins, (iii) is sequentially precipitated from 125I-labeled cell lysates by using R. communis agglutinin followed by T. vulgare agglutinin, and (iv) is sensitive to sialidase digestion. Immunoblotting of such precipitates with alpha gp demonstrates that lectins recognize the same glycoprotein, namely gp60. These results indicate that gp60, a major endothelial surface sialoglycoprotein, shares antigenic epitope(s) with glycophorin.     

Interrelationship of platelet-derived endothelial cell growth factor, liver macrophages, and tumor microvessel density in patients with cholangiocellular carcinoma

BACKGROUND/AIMS: Microvessel density (MVD) has been studied extensively as the only factor reflecting angiogenesis and a prognostic factor in various malignant tumors. Macrophages and platelet-derived endothelial cell growth factor (PD-ECGF) also play important roles in regulating angiogenesis. The present study was conducted to examine the interrelationship of MVD, liver macrophages and PD-ECGF-positive cells in patients with cholangiocellular carcinoma. METHODOLOGY: Thirty-one patients underwent resection of cholangiocellular carcinoma, and samples of the tumors were immunostained with CD34 antibody to evaluate the relationship between MVD and prognosis. Double immunohistochemical labeling for CD68 and PD-ECGF-positive cells was performed and classified as grade 0, grade 1, or grade 2 according to the number of double-positive cells. We also evaluated the relationship between the double-positive cell grading and prognosis or MVD, and furthermore the relationship between cancer cell PD-ECGF immunoreactivity and prognosis or MVD. RESULTS: Univariate analysis showed that patients with a median MVD exceeding 48/field had asignificantly poorer prognosis (p=0.02). The survival rate of grade 2 patients was significantly worse than that of the other two groups (p=0.011, p=0.0001), and the survival rate of grade 1 patients was significantly worse than that of grade 0 patients (p=0.007). MVD differed significantly among the three grades (p=0.0007, Kruskal-Wallis test), and there was a significant positive correlation between MVD and grade (p=0.0001). No correlation was observed between MVD and the number of cells positive for PD-ECGF alone (p=0.42). Neither the survival rate nor MVD of PD-ECGF (+) patients differed significantly from that of PD-ECGF (-) patients (p=0.08, p=0.6). CONCLUSIONS: Although the present results are based on a small number of patients, they suggest that liver macrophages at the invasive margin of cholangiocellular carcinoma might contribute to tumor angiogenesis through PD-ECGF secretion, and thus influence the prognosis of patients.     

Inhibition of human breast carcinoma growth by a soluble recombinant human CD40 ligand

CD40 is present on B cells, monocytes, dendritic cells, and endothelial cells, as well as a variety of neoplastic cell types, including carcinomas. CD40 stimulation by an antibody has previously been demonstrated to induce activation-induced cell death in aggressive histology human B-cell lymphoma cell lines. Therefore, we wanted to assess the effects of a recombinant soluble human CD40 ligand (srhCD40L) on human breast carcinoma cell lines. Human breast carcinoma cell lines were examined for CD40 expression by flow cytometry. CD40 expression could be detected on several human breast cancer cell lines and this could be augmented with interferon-gamma. The cell lines were then incubated with a srhCD40L to assess effects on in vitro growth. srhCD40L significantly inhibited the proliferation of the CD40(+) human breast cancer cell lines. This inhibition could also be augmented with interferon-gamma. Viability was also affected and this was shown to be due to increased apoptosis of the cell lines in response to the ligand. Treatment of tumor-bearing mice was then performed to assess the in vivo efficacy of the ligand. Treatment of tumor-bearing SCID mice with the ligand resulted in significant increases in survival. Thus, CD40 stimulation by its ligand directly inhibits human breast carcinoma cells in vitro and in vivo. These results suggest that srhCD40L may be of clinical use to inhibit human breast carcinoma growth.     

Spontaneous production of human interferon.

Several established lines of human lymphoblastoid cells were evaluated for abilities to produce interferons. Some cell lines were able to produce interferon when induced with either Newcastle disease virus or Sendai virus, whereas others failed to produce detectable interferon when so induced. However, several cell lines were able to spontaneously produce interferon without induction. Spontaneously produced interferon was liberated by cells only during logarithmic growth phase, reaching levels ranging from about 10 reference units/ml of growth medium for some cell lines to 1000 reference units/ml for others. The interferons produced by induced lymphoblastoid cells and the spontaneously produced interferons were all characterized as type I human leukocyte interferon by high levels of cross-species antiviral activities on bovine cells and by neutralizations by antiserum to human leukocyte interferon but not by antiserum to human fibroblast interferon. However, analysis by electrophoresis in sodium dodecyl sulfate/polyacrylamide gels revealed that spontaneously produced interferon was less size heterogeneous than human leukocyte interferon, migrating as a single band of activity with a peak at 20,000 daltons, whereas human leukocyte interferon contained peaks of major activity at 23,000 and 18,000 daltons and virus-induced Namalva lymphoblastoid cell interferon migrated predominantly as the 18,000-dalton form. Also, although neither virus-induced primary leukocyte interferon nor any of the virus-induced lymphoblastoid cell interferons were neutralized by antiserum to mouse interferon, all of the spontaneously produced interferons were neutralized by antiserum to mouse interferons. These data suggest significant structural similarities between the active cores of certain interferons from phylogenetically diverse animal species.