Organization and chromosomal localization of the human platelet-derived endothelial cell growth factor gene

Thymidine Phosphorylase Expression and Microvascular Density Correlation Analysis in Canine Mammary Tumor: Possible Prognostic Factor in Breast Cancer

Purpose: The thymidine phosphorylase (TP) is a key enzyme involved in the metabolism of pyrimidines. Inhibition or downregulation of this enzyme causes accumulation of metabolites with consequences in DNA replication. TP regulates angiogenesis and chemotactic activity of endothelial cells. Different studies showed the presence of TP upregulation in human cancer but the correlation between TP expression and the microvascular density (MVD) in canine mammary tumors is unknown. The aim of this study was to investigate a possible correlation between the MVD and TP expression in tumor cells of canine mammary tumors of different degree of severity (G1–G3) by immunohistochemical analysis.

Methods: Sixty-eight samples of spontaneous mammary neoplasia of 5–12 cm in diameter were collected from purebred and mixed-breed dogs (mean aged = 9.5 ± 7), not subject to chemotherapy treatments in veterinary clinics. Histopathological analysis and immunostaining were performed.

Results: Carcinoma simple samples have been classified as 72.06% of tubule-papillary, 20.59% cysto-papillary, and 7.35% tubular carcinomas. Immunostainings revealed a marked cytoplasmic expression of TP in 30.88% of samples, mild in 32.35%, weaker in 22.07%, and negative in 14.70%. The correlation analysis and two-way ANOVA showed a linear correlation between MVD and TP with a coefficient of correlation (r) > 0.5 (p < 0.05) in G2 and G3. No correlation between variables was found in G1.

Conclusions: These findings suggest that cytoplasmic TP overexpression is correlated with microvascular density in canine mammary tumors, in severe grade, and it can be a potential prognostic factor in breast cancer.

The kinetic mechanism of Human Thymidine Phosphorylase - a molecular target for cancer drug development

Human Thymidine Phosphorylase (HTP), also known as the platelet-derived endothelial cell growth factor (PD-ECGF) or gliostatin, catalyzes the reversible phosphorolysis of thymidine (dThd) to thymine and 2-deoxy-α-d-ribose-1-phosphate (2dR1P). HTP is a key enzyme in the pyrimidine salvage pathway involved in dThd homeostasis in cells. HTP is a target for anticancer drug development as its enzymatic activity promotes angiogenesis. Here, we describe cloning, expression, and purification to homogeneity of recombinant TYMP-encoded HTP. Peptide fingerprinting and the molecular mass value of the homogenous protein confirmed its identity as HTP assessed by mass spectrometry. Size exclusion chromatography showed that HTP is a dimer in solution. Kinetic studies revealed that HTP displayed substrate inhibition for dThd. Initial velocity and isothermal titration calorimetry (ITC) studies suggest that HTP catalysis follows a rapid-equilibrium random bi-bi kinetic mechanism. ITC measurements also showed that dThd and Pi binding are favorable processes. The pH-rate profiles indicated that maximal enzyme activity was achieved at low pH values. Functional groups with apparent pK values of 5.2 and 9.0 are involved in dThd binding and groups with pK values of 6.1 and 7.8 are involved in phosphate binding.

Transcriptome analysis of human peripheral blood mononuclear cells exposed to Lassa virus and to the attenuated Mopeia/Lassa reassortant 29 (ML29), a vaccine candidate

Lassa virus (LASV) is the causative agent of Lassa Fever and is responsible for several hundred thousand infections and thousands of deaths annually in West Africa. LASV and the non-pathogenic Mopeia virus (MOPV) are both rodent-borne African arenaviruses. A live attenuated reassortant of MOPV and LASV, designated ML29, protects rodents and primates from LASV challenge and appears to be more attenuated than MOPV. To gain better insight into LASV-induced pathology and mechanism of attenuation we performed gene expression profiling in human peripheral blood mononuclear cells (PBMC) exposed to LASV and the vaccine candidate ML29. PBMC from healthy human subjects were exposed to either LASV or ML29. Although most PBMC are non-permissive for virus replication, they remain susceptible to signal transduction by virus particles. Total RNA was extracted and global gene expression was evaluated during the first 24 hours using high-density microarrays. Results were validated using RT-PCR, flow cytometry and ELISA. LASV and ML29 elicited differential expression of interferon-stimulated genes (ISG), as well as genes involved in apoptosis, NF-kB signaling and the coagulation pathways. These genes could eventually serve as biomarkers to predict disease outcomes. The remarkable differential expression of thrombomodulin, a key regulator of inflammation and coagulation, suggests its involvement with vascular abnormalities and mortality in Lassa fever disease.

The virulent Lassa fever virus (LASV) and the non-pathogenic Mopeia virus (MOPV) infect rodents and, incidentally, people in West Africa. The mechanism of LASV damage in human beings is unclear. There is no licensed Lassa fever vaccine and therapeutic intervention is usually too late. The ML29 vaccine candidate derived from Lassa and Mopeia viruses protects rodents and primates from Lassa fever disease. Peripheral blood mononuclear cells from healthy human subjects were exposed to either LASV or ML29 in order to identify early cellular responses that could be attributed to the difference in virulence between the two viruses. Differential expression of interferon-stimulated genes as well as coagulation-related genes could lead to an explanation for Lassa fever pathogenesis and indicate protective treatments for Lassa fever disease.

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

Structure and promoter characterization of aldo-keto reductase family 1 B10 gene

Aldo-keto reductase family 1 member B10 (AKR1B10) is overexpressed in human hepatocellular carcinoma, lung squamous carcinoma, and lung adenocarcinoma in smokers. Our recent studies have showed that AKR1B10 plays a critical role in the growth and proliferation of cancer cells by detoxifying reactive carbonyls and regulating fatty acid biosynthesis. However, little is known about the regulatory mechanisms of AKR1B10 expression. In this study, we determined the structure of AKR1B10 gene and characterized its promoter. The results demonstrated that AKR1B10 consists of 10 exons and 9 introns, stretching approximately 13.8 kb. A 5'-RACE study determined the transcriptional start site of AKR1B10 at 320 bp upstream of the ATG translational start codon. A TATA-like (TAATAA) and a CAAT box are present from -145 to -140 bp and -193 to -190 bp upstream of the transcriptional start site, respectively. Motif analysis recognized multiple putative oncogenic and tumor suppressor protein binding sites in the AKR1B10 promoter, including c-Ets-1, C/EBP, AP-1, and p53, but osmolytic response elements were not found. A -4091 bp of the 5'-flanking fragment of the AKR1B10 gene was capable of driving GFP and luciferase reporter gene expression in HepG2 cells derived from human hepatocellular carcinoma; progressive 5'-deletions revealed that a -255 bp fragment possesses full promoter activity.

Characterization of a novel TYMP splice site mutation associated with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)

Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disorder caused by loss-of-function mutations in the thymidine phosphorylase gene (TYMP). We report here a patient compound heterozygous for two TYMP mutations: a novel g.4009G>A transition affecting the consensus splice donor site of intron 9, and a previously reported g.675G>C splice site mutation. The novel mutation causes exon 9 skipping but leaves the reading frame intact; however, TYMP protein was not detected by immunoblot analysis, suggesting that neither mutant allele is expressed as protein. The patient's fibroblasts showed gradual loss of the mitochondrial DNA-encoded subunit I of cytochrome-c oxidase, suggesting a progressive mitochondrial DNA defect in culture.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) in two Mexican brothers harboring a novel mutation in the ECGF1 gene

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by mutations in the thymidine phosphorylase gene located on chromosome 22q13.32-ter, causing defective functioning of the enzyme. At present 87 sporadic or familial cases have been reported and 52 different mutations identified. We present herein the clinical, neuromuscular and molecular findings of two affected brothers from an indigenous Mexican family living in a very small village not far from Mexico City, both brothers being homozygous for a novel mutation (Leu133Pro) in exon 3 of the ECGF1 gene.

Thymidine and deoxyuridine accumulate in tissues of patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease due to ECGF1 gene mutations causing thymidine phosphorylase (TP) deficiency. Analysis of post-mortem samples of five MNGIE patients and two controls, revealed TP activity in all control tissues, but not in MNGIE samples. Converse to TP activity, thymidine and deoxyuridine were absent in control samples, but present in all tissues of MNGIE patients. Concentrations of both nucleosides in the tissues were generally higher than those observed in plasma of MNGIE patients. Our observations indicate that in the absence of TP activity, tissues accumulate nucleosides, which are excreted into plasma.

Mitochondrial Neurogastrointestinal Encephalomyopathy (MNGIE): Biochemical Features and Therapeutic Approaches

Over the last 15 years, important research has expanded our knowledge of the clinical, molecular genetic, and biochemical features of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). The characterization of mitochondrial involvement in this disorder and the seminal determination of its genetic cause, have opened new possibilities for more detailed and deeper studies on the pathomechanisms in this progressive and fatal disease. It has been established that MNGIE is caused by mutations in the gene encoding thymidine phosphorylase (TP), which lead to absolute or nearly complete loss of its catalytic activity, producing systemic accumulations of its substrates, thymidine (dThd) and deoxyuridine (dUrd). Findings obtained from in vitro and in vivo studies indicate that the biochemical imbalances specifically impair mitochondrial DNA (mtDNA) replication, repair, or both leading to mitochondrial dysfunction. We have proposed that therapy for MNGIE should be aimed at reducing the concentrations of these toxic nucleosides to normal or nearly normal levels. The first treatment, allogeneic stem-cell transplantation (alloSCT) reported in 2006, produced a nearly full biochemical correction of the dThd and dUrd imbalances in blood. Clinical follow-up of this and other patients receiving alloSCT is necessary to determine whether this and other therapies based on a permanent restoration of TP will be effective treatment for MNGIE.

Altered expression of angiogenesis-related placental genes in pre-eclampsia associated with intrauterine growth restriction

AIM

The normal endovascular invasion of trophoblast cells and spiral artery remodeling are impaired in pre-eclampsia. Neither the circulating factor secreted by the placenta nor the cause of the widespread endothelial dysfunction in pre-eclampsia has yet been identified. In an attempt to identify novel factors, we performed a gene expression profiling study of placental tissue from women with and without pre-eclampsia.

MATERIAL AND METHODS

The study group comprised two pre-eclamptic patients with intrauterine growth restriction while the control group comprised three healthy women with uncomplicated pregnancies. Gene expression was studied using Affymetrix Human Genome U133 Plus 2 micro arrays. We focused on genes associated with angiogenesis. Some of the micro array analysis results were verified using real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Gene expression profiling revealed that the expression level of nine genes--ECGF1, JAG1, Palladin, COL18A1, TNFSF12, VEGF, ANPEP, PDGFRA and SERPIN12 - was downregulated whereas the level of four genes--EPAS1, FLT1, SIGLE10 and ANG4--was upregulated in the study group compared with the control group. The real-time RT-PCR results from JAG1, COL18A1 and FLT1 genes were in accordance with the gene expression results.

CONCLUSION

Our results show new targets for research to understand the mechanisms leading to pre-eclampsia.

Targeting platelet-derived endothelial cell growth factor/thymidine phosphorylase for cancer therapy

Thymidine phosphorylase (TP) is a key enzyme in the pyrimidine nucleoside salvage pathway, but it also recognizes and inactivates various anti-cancer chemotherapeutic agents. Moreover, TP is identical to platelet-derived endothelial cell growth factor (PD-ECGF), an angiogenic factor with anti-apoptotic properties. Increased expression of PD-ECGF/TP is found in many tumor and stromal cells, and elevated TP levels are associated with aggressive disease and/or poor prognosis. Thus, progression and metastasis of TP-expressing tumors might be abrogated by TP inhibitors that are used as single agents or in combination with (TP-sensitive) nucleoside analogues. On the other hand, increased TP activity in tumors may be exploited for the tumor-specific activation of fluoropyrimidine prodrugs, such as capecitabine. This review will focus on the different biological activities of PD-ECGF/TP and their implications for cancer progression and treatment.

Thymidine phosphorylase gene mutation is not a primary cause of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)

OBJECTIVE

The authors identified a patient with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), who completely fulfilled the clinical criteria with low thymidine phosphorylase (TP) activity. However, the same homozygotic S471L TP gene mutation was also found in her unaffected mother, but with normal TP activity. To elucidate the pathogenesis of MNGIE, we performed the analysis below.

METHODS

We analyzed the TP gene mutation in the proband and 145 unrelated individuals by direct sequence and restriction fragment length polymorphism (RFLP). TP activity was determined by the spectrophotometric method for each TP S471L genotype.

RESULTS

Among 145 normal persons, the S471L homozygote mutants were identified in 2.76% and their enzyme activity was normal.

CONCLUSION

TP gene mutation is not a primary cause of MNGIE, but with a mitochondrial deletion mutation, a single nucleotide polymorphism (SNP) of the TP gene may be crucial in the pathogenesis of MNGIE.

Late-onset MNGIE due to partial loss of thymidine phosphorylase activity

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by mutations in the gene encoding thymidine phosphorylase (TP). All MNGIE patients have had severe loss of TP function and prominent plasma accumulations of the TP substrates thymidine (dThd) and deoxyuridine (dUrd). Here, we report for the first time to our knowledge three MNGIE patients with later onset, milder phenotype, and less severe TP dysfunction, compared with typical MNGIE patients. This report demonstrates a direct relationship between the biochemical defects and clinical phenotypes in MNGIE and supports the notion that reduction of dThd and dUrd accumulation or TP replacement could be useful therapy for MNGIE.

Thymidine phosphorylase gene mutations in patients with mitochondrial neurogastrointestinal encephalomyopathy syndrome

The mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome is characterized by the association of gastrointestinal and neurological symptoms. It is a rare autosomal recessive mitochondrial disorder with multiple mitochondrial DNA deletions and/or depletion. It is caused by thymidine phosphorylase (TP) gene mutations resulting in a complete abolition of TP activity. We tested 31 unrelated patients presenting either with a complete MNGIE syndrome (8 patients), a severe intestinal pseudo-obstruction (10 patients), and multiple deletions and/or depletion of mitochondrial DNA (13 patients). All the tested patients presenting with a complete MNGIE had increased thymidine levels in plasma and urine, and no TP activity. The group with pseudo-obstruction syndrome had normal or partial reduction of TP activity. We found pathogenic mutations on TP gene only in the MNGIE syndrome group: all the MNGIE patients were compound heterozygous or homozygous for mutations in the TP gene. Eight of these mutations are yet unreported, confirming the lack of genotype/phenotype correlation in this syndrome. Enzymatic activity and thymidine level are thus rapid diagnosis tests to detect MNGIE affected patients prior to genetic testing for patients with gastrointestinal symptoms.

Evidence for the involvement of SDF-1 and CXCR4 in the disruption of endothelial cell-branching morphogenesis and angiogenesis by TNF-alpha and IFN-gamma

Vigorous inflammatory responses are associated with tissue damage, particularly when toxic levels of inflammatory cytokines are produced. Despite proangiogenic factors being present early at sites of inflammation, vascular repair occurs toward the end of the inflammatory response, suggesting modulation of the proangiogenic response. Endogenous inhibitors of angiogenesis induced during acute inflammation are poorly characterized. Here, we looked for endothelial cell-derived modulators of angiogenesis that may account for delayed neovascularization during inflammation. Gene profiling of endothelial cells showed that the inflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interferon-gamma (IFN-gamma) selectively promote expression of the antiangiogenic molecules, IFN-inducible protein-10, monokine induced by IFN-gamma, tryptophanyl-tRNA synthetase, and tissue inhibitor of metalmetalloproteinase-1, and inhibit expression of the proangiogenic molecules, platelet-endothelial cell adhesion molecule-1, vascular endothelial growth factor receptor-2, stromal cell-derived factor-1 (SDF-1), collagen type IV, endothelial cell growth factor-1, and carcinoembryonic antigen-related cell adhesion molecule-1. Reduced endothelial cell expression of SDF-1 protein by TNF-alpha and IFN-gamma disrupts extracellular matrix-dependent endothelial cell tube formation, an in vitro morphogenic process that recapitulates critical steps in angiogenesis. Replacement of SDF-1 onto the endothelial cell surface reconstitutes this morphogenic process. In vivo, TNF-alpha and IFN-gamma inhibit growth factor-induced angiogenesis and SDF-1 expression in endothelial cells. These results demonstrate that SDF-1/CXC chemokine receptor-4 constitutes a TNF-alpha- and IFN-gamma-regulated signaling system that plays a critical role in mediating angiogenesis inhibition by these inflammatory cytokines.

Mitochondrial Neurogastrointestinal Encephalomyopathy (MNGIE): A Disease of Two Genomes

BACKGROUND

Mitochondrial encephalomyopathies are clinically and genetically heterogeneous because mitochondria are the products of 2 genomes: mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). Among the mendelian-inherited mitochondrial diseases are defects of intergenomic communication, disorders due to nDNA mutations that cause depletion and multiple deletions of mtDNA.

REVIEW SUMMARY

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder of intergenomic communication and is defined clinically by 1) severe gastrointestinal dysmotility; 2) cachexia; 3) ptosis, ophthalmoparesis, or both; 4) peripheral neuropathy; and 5) leukoencephalopathy. Skeletal muscle biopsies of patients have revealed abnormalities of mtDNA and mitochondrial respiratory chain enzymes. The disease is caused by mutations in the thymidine phosphorylase (TP) gene. TP protein catalyzes phosphorolysis of thymidine to thymine and deoxyribose 1-phosphate. In MNGIE patients, TP enzyme activity is reduced drastically, and plasma thymidine and deoxyuridine are elevated dramatically. We have hypothesized that alterations of nucleoside metabolism cause an imbalanced mitochondrial nucleotide pool that leads to depletion and deletions of mtDNA.

CONCLUSIONS

MNGIE is a recognizable clinical syndrome caused by mutations in TP. The diagnosis can be confirmed by measuring TP activity in buffy coat or plasma levels of thymidine and deoxyuridine. Reduction of circulating thymidine and deoxyuridine in MNGIE patients may be therapeutic.

Alteration of nucleotide metabolism: a new mechanism for mitochondrial disorders

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease caused by loss-of-function mutations in the gene encoding thymidine phosphorylase (TP). TP deficiency alters the metabolism of the nucleosides thymidine and deoxyuridine, which, in turn, produces abnormalities of mitochondrial DNA (mtDNA) including depletion, deletions, and point mutations. MNGIE is the best characterized of the expanding number of mitochondrial disorders caused by alterations in the metabolism of nucleosides/nucleotides. Because mitochondria contain their own machinery for nucleoside and nucleotide metabolism and have physically separate nucleotide pools, it is not surprising that disorders of these pathways cause human diseases. Other diseases in this group include mtDNA depletion syndromes caused by mutations on the nuclear genes encoding the mitochondrial thymidine kinase and deoxyguanosine kinase; autosomal dominant progressive external ophthalmoplegia with multiple deletions of mtDNA due to mutations in the genes encoding the muscle-isoform of mitochondrial ADP/ATP translocator; and mitochondrial DNA depletion due to toxicities of nucleoside analogues. Mutations in the deoxynucleotide carrier, a transporter of deoxynucleoside diphosphates, have been identified as a cause of congenital microcephaly. However, alterations of mtDNA have not yet been established in this disorder. Future studies are likely to reveal additional diseases and provide further insight into this new subject.

Effects of various steroids on platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA expression in uterine endometrial cancer cells

Progestins diminish the estrogen-induced angiogenic potential related to basic fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) in uterine endometrial cancer cells. This led us to study the effect of various steroids on the expression of platelet-derived endothelial cell growth factor (PD-ECGF) as the other pertinent angiogenic factor in well-differentiated uterine endometrial cancer cell line Ishikawa. In Ishikawa cells, estradiol induced the expression of PD-ECGF and its mRNA. The estrogen-induced expression was increased approximately two-fold by progesterone and by its metabolite, 17alpha-hydroxyprogesterone, but not by medroxyprogesterone acetate (MPA). Therefore, progesterone and 17alpha-hydroxyprogesterone as endogenous steroids might induce PD-ECGF-related angiogenic potential in uterine endometrial cancer cells, but not MPA as a synthetic steroid. In conclusion, the failure of PD-ECGF induction by MPA might be the great merit of anti-angiogenic treatment with MPA for uterine endometrial cancers.

Four novel thymidine phosphorylase gene mutations in mitochondrial neurogastrointestinal encephalomyopathy syndrome (MNGIE) patients

Mitochondrial neurogastrointestinal encephalomyopathy syndrome (MNGIE) is a rare autosomal recessive neurologic disorder characterised by multiple mitochondrial DNA deletions. In this study, five Turkish MNGIE patients are investigated for mtDNA deletions and TP gene mutations. The probands presented all the clinical criteria of the typical MNGIE phenotype; the muscle biopsy specimens also confirmed the diagnosis with ragged red fibres and cytochrome C oxidase (COX) negative fibres. The mitochondrial DNA analysis revealed no deletions in the probands' skeletal muscle samples. We have identified four novel mutations in the TP gene while one of the patients also harboured a nucleotide change, which was previously reported as a mutation.

The Sp1 transcription factor contributes to the tumor necrosis factor-induced expression of the angiogenic factor thymidine phosphorylase in human colon carcinoma cells

Thymidine phosphorylase (TP; also known as platelet-derived endothelial cell growth factor, PD-ECGF) is an angiogenic factor that is chemotactic for endothelial cells and has been found to induce neovascularization in vivo. TP is frequently overexpressed in human solid tumors, where its expression has been correlated with increased tumor microvessel density, invasion, and metastasis, and shorter patient survival. In this report, TP activity in the WiDr colon carcinoma cell line was found to be induced 100-fold by tumor necrosis factor (TNFalpha), a secretory product of activated macrophages that has indirect angiogenic activities. Increased TP activity was accompanied by increased TP mRNA levels and without an increase in mRNA stability. TNFalpha-induced TP mRNA levels were reduced by mithramycin, a DNA-binding transcription inhibitor specific for GC-rich sequences. Transcriptional regulation by TNFalpha was confirmed by transient transfection of WiDr with upstream TP sequences in a luciferase reporter construct. Deletion analysis of the reporter pinpointed two regions of the TP promoter with regulatory elements for both TNFalpha-inducible and basal expression, and they contained, respectively, three and one consensus binding sites for the Sp1-family of transcription factors. One additional region contributed only to basal TP expression, and it contained three Sp1 sites. TNFalpha-induced TP expression decreased when point mutations were made in three of the four Sp1 sites postulated to contribute to both basal and TNFalpha-inducible expression. Electrophoretic mobility shift assays further demonstrated binding of nuclear Sp1 to these three sites. Sp1-binding activity was also increased in cells treated with TNFalpha. These studies establish a role for Sp1 in the regulation of expression of the angiogenic factor TP in colon cancer WiDr cells.

Quantitative real-time PCR identifies a critical region of deletion on 22q13 related to prognosis in oral cancer

Quantitative real time PCR was performed on genomic DNA from 40 primary oral carcinomas and the normal adjacent tissues. The target genes ECGFB, DIA1, BIK, and PDGFB and the microsatellite markers D22S274 and D22S277, mapped on 22q13, were selected according to our previous loss of heterozygosity findings in head and neck tumors. Quantitative PCR relies on the comparison of the amount of product generated from a target gene and that generated from a disomic reference gene (GAPDH-housekeeping gene). Reactions have been performed with normal control in triplicates, using the 7700 Sequence Detection System (PE Applied Biosystems). Losses in the sequences D22S274 (22q13.31) and in the DIA1 (22q13.2-13.31) gene were detected in 10 out of 40 cases (25%) each. Statistically significant correlations were observed for patients with relative copy number loss of the marker D22S274 and stages T3-T4 of disease (P=0.025), family history of cancer (P=0.001), and death (P=0.021). Relative copy number loss involving the DIA1 gene was correlated to family history of cancer (P<0.001), death (P=0.002), and consumption of alcohol (P=0.026). Log-rank test revealed a significant decrease in survival (P=0.0018) for patients with DIA1 gene loss. Relative copy number losses detected in these sequences may be related to disease progression and a worse prognosis in patients with oral cancer.

Homeostatic control of uridine and the role of uridine phosphorylase: a biological and clinical update

Uridine, a pyrimidine nucleoside essential for the synthesis of RNA and bio-membranes, is a crucial element in the regulation of normal physiological processes as well as pathological states. The biological effects of uridine have been associated with the regulation of the cardio-circulatory system, at the reproduction level, with both peripheral and central nervous system modulation and with the functionality of the respiratory system. Furthermore, uridine plays a role at the clinical level in modulating the cytotoxic effects of fluoropyrimidines in both normal and neoplastic tissues. The concentration of uridine in plasma and tissues is tightly regulated by cellular transport mechanisms and by the activity of uridine phosphorylase (UPase), responsible for the reversible phosphorolysis of uridine to uracil. We have recently completed several studies designed to define the mechanisms regulating UPase expression and better characterize the multiple biological effects of uridine. Immunohistochemical analysis and co-purification studies have revealed the association of UPase with the cytoskeleton and the cellular membrane. The characterization of the promoter region of UPase has indicated a direct regulation of its expression by the tumor suppressor gene p53. The evaluation of human surgical specimens has shown elevated UPase activity in tumor tissue compared to paired normal tissue.

Expression of vascular endothelial growth factor isoforms and platelet-derived endothelial cell growth factor in bladder cancer

We analyzed the expression of vascular endothelial growth factor (VEGF) messenger ribonucleic acid (mRNA) isoforms and platelet-derived endothelial cell growth factor (PDECGF) mRNA in bladder cancer. We also attempted to determine if correlation exists between their expression level and conventional clinical variables in patients with bladder cancer. Tissues obtained from 60 patients with bladder carcinoma were used for analysis. Expression levels of VEGF isoforms and PDECGF were examined using reverse transcription-polymerase chain reaction (RT-PCR). Correlations between the expression levels of each VEGF isoform and PDECGF and histopathologic findings were evaluated. Four VEGF isoforms corresponding to VEGF121, 165, 189, and 206 were detected in bladder cancer tissue by RT-PCR. Gene expression of all VEGF isoforms as a ratio of the target to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) showed no correlation with pathologic stage of bladder cancer. However, with regard to relative expression levels of VEGF isoform, which is the ratio to the sum of total VEGF isoforms, the levels of VEGF206 and VEGF189 in tumor samples of grade pT2 or higher were significantly lower than those in tumors of grade pT1 or lower (P<.05). In contrast, the levels of VEGF121 in >/=pT2 tumors tended to be higher than those in </=pT1 tumors (P=.056). The expression level of PDECGF as a ratio to GAPDH in pT2</= tumors was significantly higher than that in either pTa or pT1 tumors (P<.05). Moreover, a higher expression level of PDECGF was observed in G3 tumors than in G1 tumors (P<.05). The results indicated that gene expression of VEGF isoforms do not play a significant role in tumor progression or invasion; however, the distribution of VEGF isoforms may play a role in tumor progression of bladder cancer. A high expression level of PDECGF correlated significantly with the tumor progression of bladder cancer.

Thymidine phosphorylase: its role in sensitivity and resistance to anticancer drugs

Thymidine phosphorylase (TP) is an angiogenic enzyme present in normal tissues. Increased levels are found in many tumors, in stromal cells, tumor cells or both. High tumor TP levels may confer a poor prognosis. Cytokines (including interferons), tissue hypoxia and low pH increase TP levels. The influence of tumor TP on fluoropyrimidine toxicity is variable, but capecitabine is a prodrug of fluorouracil that requires activation by TP and hence may have a higher therapeutic index than other fluoropyrimidines. Folate-based thymidylate synthase inhibitors may also be more effective in tumors with a high TP because of increased degradation of endogenous thymidine. Copyright 1999 Harcourt Publishers Ltd.

Expression of the thymidine phosphorylase gene in epithelial ovarian cancer

Thymidine phosphorylase (TP) is associated with angiogenesis and the progression of solid tumours. High intracellular levels of this enzyme indicate increased chemosensitivity to pyrimidine antimetabolites. TP gene expression in 56 cases of epithelial ovarian cancer (27 of serous, 10 mucinous, 12 endometrioid, five clear cell and two undifferentiated) were analysed by polymerase chain reaction of RNA after reverse transcription. These included eight of low malignant potential. Twenty were stage I, four stage II, 27 stage III and five stage IV. The level of TP gene expression was presented by the relative yield of the TP gene to the beta2-microglobulin gene. TP gene expression ranged from 0.19 to 5.38 (median 0.93). The value of TP gene expression in stage III-IV was significantly higher than that of TP gene expression in stage I-II (P = 0.0005). Histological grade significantly associated with TP gene expression (P = 0.008), but histological subtype did not (P = 0.166). A follow-up study of 34 cases after complete resection of the primary tumours by surgical operation was performed. TP gene expression of the cases with recurrence showed significantly higher levels compared to cases without recurrence (P = 0.049). Survival data were available for 47 of the 56 patients. The prognosis of the patients with high TP gene expression (equal to, or greater than, median) was to be significantly worse than patients with low TP gene expression (less than median) (P = 0.021). The TP gene expression level may play one of the key roles in the biology of ovarian epithelial cancer and define a more aggressive tumour phenotype. A new therapeutic intervention mediated by TP protein activity is anticipated.

Expression of platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA in uterine cervical cancers

Angiogenesis contributes to the growth and secondary spreading of solid tumours. Platelet-derived endothelial cell growth factor (PD-ECGF) is identified as such an angiogenic factor. In the present study, the prognosis of the patients with high PD-ECGF uterine cervical cancers was worse than those with low PD-ECGF cancers, and PD-ECGF expression correlated with cellular proliferation and with vascular density and venous invasion in uterine cervical cancers. Therefore, PD-ECGF might contribute to the growth of uterine cervical cancers via angiogenesis related to vascular spreading. Furthermore, PD-ECGF and its mRNA had a wide range and were highly expressed in uterine cervical cancers, especially squamous cell carcinoma, regardless of clinical stage. Therefore, PD-ECGF in uterine cervical cancers might play a role of basic angiogenesis in all processes of advancing of uterine cervical cancers. This indicates that 5'-deoxy-5-fluorouridine might be highly effective in squamous cell carcinoma of the cervix, which possesses a high activity of thymidine phosphorylase to convert 5'-deoxy-5-fluorouridine to 5-fluorouracil, and that some angiogenic inhibitors of new capillary formation might be effective in the inhibition of tumour growth and spreading associated with angiogenesis.

Expression of platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA in uterine endometrial cancers

To determine the potential of growth, invasion and metastasis of uterine endometrial cancer cells associated with neovascularization, the expressions of platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA in uterine endometrial cancers and in normal uterine endometria as controls were determined and the relationship between their expressions and histological grades, grades of myometrial invasion and clinical stages of uterine endometrial cancers was analyzed. The levels of PD-ECGF were significantly higher in uterine endometrial cancers of well-differentiated grade (G1) with invasion to < or =1/2 myometrium (B) and of stage 1 than in those of moderately and poorly differentiated grades (G2 and G3, respectively) limited to endometrium (A) and with invasion to >1/2 myometrium (C) and of stages II and III/IV and in normal uterine endometria. There was no significant difference in the levels between uterine endometrial cancers of G2 and G3, A and C, or stages II and III/IV and normal uterine endometria. Therefore, the active availability of PD-ECGF might contribute to the acceleration of angiogenic activity in the early process of invasion of well-differentiated uterine endometrial cancers.

Expression of platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA in ovarian cancers

The potential of growth, invasion and metastasis of ovarian cancer cells associated with neovascularization, and the expression of platelet-derived endothelial growth factor (PD-ECGF) and its mRNA in ovarian cancers were determined. The relationship between their expression and histopathological types and clinical stages of ovarian cancers was also analyzed. The levels of PD-ECGF and its mRNA were higher in ovarian cancers than in normal ovaries. Furthermore, some endometrioid carcinomas and serous cystadenocarcinomas of the ovary and some ovarian cancers in stages III and IV expressed remarkably high levels of PD-ECGF and its mRNA. Therefore, in some ovarian cancers, PD-ECGF might be related to advanced stages of ovarian cancers associated with neovascularization.

Stromal angiogenesis in human glioma: a role of platelet-derived endothelial cell growth factor

BACKGROUND

Although several tumor angiogenic factors have been identified previously and characterized, it is not yet fully clear how tumor angiogenic factors induce endothelial cell transformation and proliferation. Platelet-derived endothelial cell growth factor (PD-ECGF) has been recently discovered to be an endothelial cell growth factor initially purified from human platelets. However, there has been no previous report describing the significance of PD-ECGF in the growth of brain tumors by angiogenic stimulation. We report the immunohistochemical localization of PD-ECGF in human gliomas and meningiomas, and discuss whether PD-ECGF could play a role in the modulation of stromal angiogenesis in human glioblastoma multiforme.

METHODS

Twenty-eight cases of glioma (11 glioblastomas and 17 astrocytomas) derived from the neuroectoderm in embryogenesis and 12 meningiomas from the mesoderm were investigated by both immunohistochemical localization of the PD-ECGF and a semiquantitative assay to determine the degree of stromal angiogenesis.

RESULTS

Numerous PD-ECGF positive cells were observed within and around the blood vessels of glioblastoma multiforme, especially on the borders of tumor tissue. The PD-ECGF positive cells were negative for anti-von Willebrand factor (vWF) and antiglial fibrillary acidic protein (GFAP) antibodies and were positive for antimacrophage (HAM-56). The expression of PD-ECGF by macrophages closely correlated with the degree of stromal vascularity in glioblastoma multiforme; no such correlation was found in either astrocytoma or meningioma. Proliferating cell nuclear antigen (PCNA) was found to be positive in some endothelial cells of stromal vessels in glioblastoma multiforme. These findings suggest that PD-ECGF expressed by macrophages plays an important role in the growth of glioblastoma multiforme with stromal angiogenesis.

Tissue distribution of human gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression

Human tissue contents of gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression in tumor cells were currently examined by a sandwich enzyme immunoassay (EIA) system and a reverse transcription-polymerase chain reaction (RT-PCR) method. Gliostatin/PD-ECGF was found to distribute in rather ubiquitous than specific human tissues and organs, with a relatively high levels in the tissues of digestive system (esophagus and rectum), brain, spleen, bladder and lung, but not in gall bladder, aorta, muscle, fat and kidney. Most of examined human tumor cell lines showed 4- or 5-fold higher contents (21.5 +/- 3.9 ng/mg protein) than normal tissue contents (4.4 +/- 1.1 ng/mg protein) on the average. While gliostatin/PD-ECGF is known to lack a signal sequence, some tumor cells (A431 and MKN74) appeared to release it into the conditioned medium. Expression of gliostatin/PD-ECGF in epidermoid carcinoma cell (A431) and stomach cancer cell (MKN45) was induced by dibutyryl cyclic AMP and phorbol ester, and uniquely in MKN45 by hydrocortisone. In particular, this hydrocortisone specifically caused an increase of the apparent secretion of MKN74 without its cytotoxic effects, suggesting a possible secretion of gliostatin/PD-ECGF in the restricted but not universal cell line. Biological significance on the chemical induction of gliostatin/PD-ECGF in tumor cells and on its extracellular secretion are discussed.

A group of NotI jumping and linking clones cover 2.5 Mb in the 3p21-p22 region suspected to contain a tumor suppressor gene

The chromosomal region 3p21.2-p22 has been shown to be involved in the development of several forms of solid tumors. Such deletions, translocations, and rearrangements presumably result in the disturbance or loss of a critical gene function. Pulsed-field gel electrophoresis (PFGE), using NotI linking clones as a probe represent a powerful tool for analyzing such rearrangements. A NotI linking clone, AP20 (D3S1641), was localized by in situ hybridization to 3p21.3-p22. Two NotI jumping clones adjacent to this clone were isolated, clone J32-612 covering 0.5 Mb and clone J31-611 covering approximately 1 Mb. Clone J31-611 crosses the border of the deletion present in hybrid cell line MCH939.2, which contains a deleted 3p21 region. For these jumping clones, corresponding NotI linking clones, NLJ3 (D3S1642) and NL3-003, were isolated. Altogether, linking and jumping clones from the AP20 locus hybridize to NotI fragments totaling 2.5 Mb in length. These NotI-containing clones detect expressed sequences in several human tissues. Clone NLJ3 possesses homology to the human platelet-derived endothelial cell growth factor gene and may represent a new member of this gene family. Another clone (AP20) revealed 66% sequence similarity to rat skeletal muscle voltage-sensitive sodium channel subtype 2. Therefore, this group of clones will be useful not only for analyzing rearrangements in tumors, but also for the isolation of new genes from the 3p21.3-p22 region.

Structural properties of 3.0 kb and 3.2 kb transcripts encoding platelet-derived endothelial cell growth factor/thymidine phosphorylase in A431 cells

Platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) is a 90 kDa protein consisting of two non-covalently associated subunits. In addition to the previously identified 1.8 kilobase (kb) PD-ECGF/TP mRNA, the human epidermoid carcinoma cell line A431 was found to express 3.0 kb and 3.2 kb transcripts. cDNA cloning of the larger transcripts revealed that they contain long 5' leader sequences of 1.5 kb and 1.7 kb, respectively, and the same open reading frame encoding PD-ECGF/TP as that of the 1.8 kb transcript. Comparison with the published PD-ECGF/TP genomic sequence shows that the long 5' leader sequence contain 7 of 8 copies of Sp-1 binding sites present in the transcription promoter region of the 1.8 kb transcript.

Expression of recombinant platelet-derived endothelial cell growth factor in the yeast Saccharomyces cerevisiae

A platelet-derived endothelial cell growth factor cDNA has been cloned, sequenced and expressed using the Saccharomyces cerevisiae PRB1 promoter. Soluble recombinant platelet-derived endothelial cell growth factor constituted 0.5-1.0% of total soluble protein. Yeast soluble protein extracts containing recombinant platelet-derived endothelial cell growth factor stimulate the growth of calf pulmonary artery endothelial cells in vitro.

Platelet-derived endothelial cell growth factor

Platelet-derived endothelial cell growth factor (PD-ECGF) is a 45 kDa single chain polypeptide which stimulates endothelial cell growth and chemotaxis in vitro and angiogenesis in vivo. Analysis of a full length PD-ECGF cDNA revealed an open reading frame coding for 482 amino acids without homology to other known proteins. No signal sequence was observed, and analysis of the biosynthesis and processing of PD-ECGF in a thyroid carcinoma cell line revealed that PD-ECGF is released only very slowly. PD-ECGF becomes covalently associated with nucleotide triphosphates (e.g., ATP) in vivo, as well as in vitro. The physiological significance of this posttranslational modification remains to be elucidated. The tissue distribution and target cell specificity of PD-ECGF suggest roles in angiogenesis (e.g., during wound healing and in the developing placenta), as well as in the maintenance of the integrity of the endothelial cell lining of large vessels.

Morphological and cytogenetic studies of angiosarcoma in Stewart-Treves syndrome

A morphological and cytogenetic analysis of a multifocal angiosarcoma in a typical case of Stewart-Treves syndrome is reported. The morphological analysis indicated differentiation along both blood and lymph vessel endothelium lines. By light and electron microscopy there were areas with well-developed erythrocyte-containing, capillary-like vessels and poorly differentiated areas with abortive vascular formations. In these the endothelium revealed immunoreactivity to factor VIII RAg, binding of Ulex europaeus I and Psophocarpus tetragonolobus agglutinin lectins, Weibel-Palade bodies ultrastructurally and presented a continuous enclosing external lamina and immunoreactivity for laminin and collagen IV, all features of blood-vessel differentiation. There were also lymphangioma-like areas as well as poorly differentiated areas where the immunohistochemical, lectin-binding and ultrastructural features were compatible with a lymph vessel differentiation. Cytogenetic analysis of cultured tumour cells revealed chromosome counts in the diploid region. About 40% of the cells analysed had a normal diploid karyotype. The remaining cells showed a multitude of mainly nonclonal structural alterations; 17 unique marker types resulting from different translocations and deletions were observed. There were also a few cells with clonal numerical deviations showing monosomy 22, monosomy X and trisomy 2 respectively. It is of interest that the losses of chromosome 22 and the X chromosome also have been observed in Kaposi's sarcoma and that the PD-ECGF gene, a novel angiogenetic factor, has been mapped to chromosome 22.

Platelet-derived endothelial cell growth factor

Platelet-derived endothelial cell growth factor (PD-ECGF) is a 45 kDa single chain polypeptide, which stimulates the DNA synthesis and chemotaxis of endothelial cells in vitro and angiogenesis in vivo. Purification from human platelets and cDNA cloning from a human placental cDNA library, revealed that PD-ECGF is a novel type of peptide without sequence similarity to hitherto known proteins. PD-ECGF is present in human platelets and placenta, and is produced by certain normal and transformed cultured cells; it lacks a hydrophobic leader sequence and most of the protein remains inside the producer cells. Analysis of PD-ECGF produced by cultured cells, revealed that it contains nucleotide(s) covalently bound to serine residues. The in vivo function of PD-ECGF is not known; its target cell specificity and tissue distribution suggest roles in angiogenesis of the placenta and in the maintenance of the integrity of the endothelial cell layer of blood vessels. PD-ECGF may have a clinical utility in the stimulation of wound healing and re-endothelialization of vessels.