Biomedical subjects

Adrian L Harris

Publications and source records attributed to Adrian L Harris.

At least 37 records · Page 2Linked to original sources

PubMed2006

Comparison of metabolic pathways between cancer cells and stromal cells in colorectal carcinomas: a metabolic survival role for tumor-associated stroma.

Understanding tumor metabolism is important for the development of anticancer therapies. Immunohistochemical evaluation of colorectal adenocarcinomas showed that cancer cells share common enzyme/transporter activities suggestive of an anaerobic metabolism [high lactate dehydrogenase 5 (LDH5)/hypoxia-inducible factor alphas (HIFalphas)] with high ability for glucose absorption and lactate extrusion [high glucose transporter 1 (GLUT1)/monocarboxylate transporter (MCT1)]. The tumor-associated fibroblasts expressed proteins involved in lactate absorption (high MCT1/MCT2), lactate oxidation (high LDH1 and low HIFalphas/LDH5), and reduced glucose absorption (low GLUT1). The expression profile of the tumor-associated endothelium indicated aerobic metabolism (high LDH1 and low HIFalphas/LDH5), high glucose absorption (high GLUT1), and resistance to lactate intake (lack of MCT1). It is suggested that the newly formed stroma and vasculature express complementary metabolic pathways, buffering and recycling products of anaerobic metabolism to sustain cancer cell survival. Tumors survive and grow because they are capable of organizing the regional fibroblasts and endothelial cells into a harmoniously collaborating metabolic domain.

Adenocarcinoma↗

PubMed2006

Proteomic identification of a role for the von Hippel Lindau tumour suppressor in changes in the expression of mitochondrial proteins and septin 2 in renal cell carcinoma.

The von Hippel Lindau (VHL) tumour suppressor gene, VHL, plays a central role in development of sporadic conventional renal cell carcinomas (RCCs). Studying VHL function may, therefore, increase understanding of the pathogenesis of RCC and identify markers/therapeutic targets. Comparison of 2-DE protein profiles of VHL-defective RCC cells (UMRC2) transfected with control vector or wild-type VHL showed differences in 30 proteins, including several novel changes. One of the findings confirmed by Western blotting was up-regulation of the mitochondrial protein ubiquinol cytochrome c reductase complex core protein 2 following VHL transfection, a change that was also observed in two other cell line backgrounds. A marked decrease in expression of this and several other mitochondrial proteins was demonstrated in RCC tissues and using VHL-transfectants, several were shown to exhibit VHL-dependent regulation. Thus, VHL may contribute to the decreased mitochondrial function seen in RCC. A form of septin 2 down-regulated following VHL transfection was also identified. Septin 2 was up-regulated in 12/16 RCCs, while alteration of the form present was also observed in 1/3 tumours analysed. Thus, increased expression of septin 2 is a common event in RCC and protein modification may also alter septin 2 function in a subset of tumours.

Blotting, Western↗

PubMed2006

Notch signaling in breast cancer and tumor angiogenesis: cross-talk and therapeutic potentials.

Notch signaling is an evolutionarily conserved pathway that regulates numerous physiological processes. Disruption of Notch has been implicated in multiple tumor types. Evidence from in vitro experiments, mouse models and human tumor samples indicates that Notch plays a predominantly oncogenic role in breast cancer and interacts with other pathways involved in tumorigenesis. In addition, Notch signaling is required for physiological angiogenesis and may promote tumor angiogenesis. A variety of strategies for blocking Notch signaling, in particular gamma-secretase inhibition, are discussed as potential therapies for breast cancer and tumor angiogenesis.

Amyloid Precursor Protein Secretases↗

PubMed2006

Loss of expression and nuclear/cytoplasmic localization of the FOXP1 forkhead transcription factor are common events in early endometrial cancer: relationship with estrogen receptors and HIF-1alpha expression.

The FOXP1 gene has been identified as a new member of the winged helix family of transcription factors that have important roles in cellular transformation, differentiation and proliferation. In this study, we examined the expression of FOXP1 in the normal and malignant endometrium (stage I endometrioid adenocarcinoma cases), showing a frequent deregulation of its expression in cancer. Proliferative endometrium showed predominantly nuclear localization of FOXP1, while exclusively weak cytoplasmic staining was present in the secretory phase. Loss of nuclear expression was the most striking event in endometrial adenocarcinoma. Nuclear expression ranged from 0 to 20% (median 0%). Cytoplasmic expression was noted more frequently, ranging from 0 to 90% of cancer cells (median 30%). Overall, 24/82 cases (29.3%) were observed to lack both nuclear and cytoplasmic FOXP1 expression. Tumors with exclusively cytoplasmic expression of FOXP1 were linked with deep myometrial invasion and hypoxia-inducible factors 1alpha (HIF-1alpha) expression. On the other hand, the presence of nuclear FOXP1 expression was significantly linked with ER-alpha reactivity. Survival analysis did not reveal significant differences among patients grouped by FOXP1 expression, presumably due to the high curability of stage I disease. This study provides evidence on pathways to be investigated to elucidate the interplay between FOXP1, ER-alpha and HIF-1alpha in hormone dependent cancers.

Cell Nucleus↗

PubMed2006

Phosphorylated KDR expression in endometrial cancer cells relates to HIF1alpha/VEGF pathway and unfavourable prognosis.

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor for many malignant neoplasms exerting its function through activation of specific membrane receptors, that is, KDR/flk-1, residing in endothelial cells. Several recent reports indicate that VEGF receptors are also expressed in cancer cells, suggesting that specific VEGF-originated cancer cell reactions may parallel the endothelial response. Using a novel monoclonal antibody, recognizing the activated (phosphorylated) form of the KDR receptor (pKDR), we assessed the expression of pKDR in normal and malignant endometrium. A strong and consistent cytoplasmic and nuclear pKDR expression was noted in the normally cycling endometrium, including epithelial, stromal and endothelial cells, suggesting a role in the normal menstrual cycle. Approximately, one-third of the 70 stage I endometrioid adenocarcinomas analysed exhibited an intense cytoplasmic and nuclear pKDR expression in both cancer cells and peritumoral vessels. It was noted that such pKDR reactivity in cancer cells was related directly to VEGF, VEGF/KDR complexes and HIF1alpha (hypoxia inducible factor 1alpha) expression. Furthermore, pKDR expression was significantly associated with poor prognosis. It is concluded that the VEGF/KDR pathway is activated in both normally cycling and malignant endometrium, suggestive of an important role in the biology of this tissue. The unfavourable prognosis that VEGF confers to endometrial adenocarcinomas could be attributed to its angiogenic activity, but also to a direct effect on cancer cells through an autocrine VEGF/KDR loop.

Endometrial Neoplasms↗

PubMed2006

Mechanisms of disease: angiogenesis in urologic malignancies.

Angiogenesis is critical for growth of tumors and their metastasis. In this article we review the literature on studies of angiogenesis pathways and markers for renal cancer, prostate cancer and bladder cancer. Overall, there is clear evidence that markers of angiogenesis and expression of angiogenic factors are associated with adverse outcomes in each of these tumor types. Relatively few angiogenic pathways have been investigated so far, although over 50 factors are known to be involved, and little has been studied on the antiangiogenic pathways and their suppression. The failing in many of the studies is small size and lack of suitable statistical analysis. Nevertheless, this review demonstrates the importance of these pathways and the need to develop selection criteria for patients who are candidates for antiangiogenic therapies. On the basis of the expression profiles reported so far, therapies that target vascular endothelial growth factor should be considered for the treatment of renal, prostate and bladder cancers. As most tumors express factors that are involved in multiple angiogenic pathways, further research is needed to determine which are coregulated and what the most common patterns are.

Humans↗

PubMed2006

Phosphorylated KDR can be located in the nucleus of neoplastic cells.

KDR (kinase insert domain receptor) phosphorylation induces several effects which lead eventually to cell proliferation and survival. The precise mechanisms by which KDR, once it is activated, communicates with the nucleus are starting to be understood but have not yet been completely unravelled. Two in vitro studies on animal cell lines reported in the literature have demonstrated that, following stimulation with VEGF, KDR is actually translocated within the nucleus. Our aim was to investigate whether this translocation occurs in human cells both in vitro and in vivo. Using laser scanning confocal microscopy, a variable nuclear localization of phosphorylated and total KDR in cell lines and tumour samples was found. In human neoplastic cell lines, hypoxic stimulation greatly increased the nuclear amount of total KDR but less so that of the phosphorylated form. Only after hypoxia and VEGF stimulation there was a comparably increased expression of phosphorylated and total KDR observed in the nuclei of these cells. We conclude that neoplastic cells show a variable expression of total and phosphorylated KDR in the nucleus. The precise functional meaning of nuclear location remains to be established.

Cell Hypoxia↗

PubMed2006

Endogenous markers of hypoxia/anaerobic metabolism and anemia in primary colorectal cancer.

Anemia has been implicated in the decreased oxygen tension noted within the tumor environment. In a series of 79 colorectal adenocarcinomas we investigated the role of anemia in activating molecular pathways regulated by hypoxia. Preoperative Hb levels were correlated with the immunohistochemical expression of HIF1alpha and HIF2alpha, LDH5, GLUT1, VEGF, DEC1 and BNIP3, and with angiogenesis and the cancer cell proliferation index. Upregulation of HIF1alpha and HIF2alpha proteins, found in 43% and 44.3% of cases, respectively, was not related to anemia (Hb < 10 g%). This is in agreement with other studies suggesting that HIF activation occurs for various reasons, such as poor or irregular vascularity, or oncogene activation. Nevertheless, low Hb levels (<10 g%) were linked to activated anaerobic metabolism (LDH5 overexpression) in a subset of tumors not expressing HIF1alpha (P < 0.01). Overexpression of HIFs, whether linked to anemia or not, was associated with a number of factors related to tumor aggressiveness (assessed as local invasion and nodal metastasis), anaerobic metabolism and intratumoral acidosis (LDH5, GLUT1; increased glucose metabolism to lactate), activation of genes related to necrosis (BNIP3) and angiogenesis (VEGF). Expression of BNIP3 emerged as the strongest independent factor related to transmural invasion and metastasis to lymph nodes. Identification of specific patterns of the hypoxia molecular cascade activated in cancer cells might help in developing specific therapeutic policies.

Adenocarcinoma↗

PubMed2006

Identification of novel small-molecule inhibitors of hypoxia-inducible factor-1 transactivation and DNA binding.

Hypoxia-inducible factor-alpha (Hif-alpha) plays an important role in tumor growth by increasing resistance to apoptosis and the production of angiogenic factors, such as vascular endothelial growth factor (VEGF). Therefore, Hif-alpha is an attractive target for development of novel cancer therapeutics. We have generated Chinese hamster ovary cells, which stably express luciferase reporter construct under the control of a hypoxia response element to screen 15,000 compounds. We identified 40 compounds that inhibited hypoxic up-regulation of luciferase, and the top 30 compounds were further screened in a secondary assay using MDA-468 breast cancer cell line. Eight compounds were shown to inhibit VEGF expression in hypoxic cells at subtoxic concentrations. Three top putative Hif inhibitors, DJ12, DJ15, and DJ30, were chosen for further analysis. Transient transfection of cells with hypoxia-regulated luciferase reporter plasmids further validated that these compounds inhibit hypoxia up-regulated genes. All three compounds failed to inhibit Hif-1alpha protein levels but they did inhibit induction of downstream targets of Hif-alpha under hypoxia. Two of the three compounds were cell type specific, whereas compound DJ12 inhibited VEGF at subtoxic levels in breast cancer cell lines MDA-468 and ZR-75, melanoma cell line MDA-435, and pVHL mutant renal cancer cell lines RCC4 and 786-0. Compound DJ12 down-regulated mRNA of downstream targets of Hif-alpha, and significantly inhibited Hif-1alpha transactivation activity by blocking Hif-1alpha hypoxia response element-DNA binding. Our cell-based approach and deconvolution of the inhibitory effect of DJ12 has identified a novel compound that targets the hypoxia pathway by inhibiting Hif-alpha-inducible transcription.

Animals↗

PubMed2006

Role of carbonic anhydrase IX expression in prediction of the efficacy and outcome of primary epirubicin/tamoxifen therapy for breast cancer.

The purpose of this study is to investigate the role of carbonic anhydrase IX (CAIX) expression in predicting the response to epirubicin and disease-free survival (DFS) in breast cancer patients enrolled in a single institution trial of primary anthracycline and tamoxifen therapy. CAIX expression was assessed in 183 patients with T2-4 N0-1 breast cancer enrolled in a randomized trial comparing four cycles of single agent epirubicin versus epirubicin+tamoxifen as primary systemic treatment. All patients received postoperatively four cycles of the four weekly i.v. cyclophosphamide, methotrexate, 5-fluorouracil regimen. Patients with estrogen receptor (ER)-positive primary tumors received 5 years of adjuvant tamoxifen. Pretreatment, p53 (P=0.007), c-erbB2 (P<0.01), and Ki67 (P=0.02) were directly associated with CAIX expression, while bcl2 (P<0.000) and ER (P=0.000) and progesterone receptor (PgR; P<0.01) were inversely correlated. In multivariate analysis, only high p53 and low bcl2 were independently associated with CAIX positivity. CAIX immunostaining was significantly associated with poor outcome for DFS (P<0.002) and overall survival (P=0.001). In multivariate analysis, a significant interaction was found between CAIX and markers of hormone sensitivity, bcl2 (P=0.01), ER (P=0.02), PgR (P=0.02), and lymph node involvement (P=0.04), in predicting DFS. Presently, there are few clinical markers of resistance to tamoxifen treatment in ER-positive tumors. CAIX expression in breast cancer patients shows a negative predictive role of treatment efficacy in ER-positive patients on the adjuvant tamoxifen after primary chemo-endocrine therapy. Studies investigating the effects of pH on tamoxifen uptake and the effects of therapy with CA inhibitors are planned.

Antibiotics, Antineoplastic↗

PubMed2006

The role of cell-free DNA size distribution in the management of prostate cancer.

Cell-free DNA has been shown to have diagnostic potential in a number of malignant diseases. Recently, the integrity or size distribution of these fragments has also been identified as having possible diagnostic value. The current study explores the role of this novel parameter in the clinical diagnosis of prostate cancer. Plasma samples, collected prospectively from men undergoing investigation for prostate cancer, were used to obtain a cell-free DNA sample. Real-time PCR was used to quantify the level of cell-free DNA (ng/ml) and its size distribution (delta CD in each case. Sixty-one samples were collected from patients with prostate cancer and 62 from those with benign histology. Analysis failed to reveal a statistically significant relationship between either the level of cell-free DNA (p = 0.82) or its size distribution (p = 0.91) and the presence of cancer. These results demonstrate that cell-free DNA is unlikely to be of diagnostic value in the clinical management of this disease.

Adenocarcinoma↗

PubMed2005

Inclusion of vasculature-related variables in the Dukes staging system of colon cancer.

PURPOSE: The Dukes stage is used to stratify colorectal cancer patients into groups of different prognosis and need of adjuvant radiotherapy and chemotherapy. However, approximately 80% of patients with Dukes stage C colorectal cancer receive cytotoxic therapy without any expected benefit, for such patients would either not relapse without adjuvant therapy or they would inevitably do so because of tumor resistance to the available regimens. On the other hand, as 20% of Dukes stage B patients would relapse after surgery, adjuvant therapy could improve their survival. Improvement of the Dukes stage predictive accuracy is necessary to better assign patients for adjuvant therapies, especially nowadays when antiangiogenic agents are being incorporated in the clinical practice. PATIENTS AND METHODS: In this study, we examined the prognostic role of Dukes staging system in parallel with three vasculature-related variables (vascular invasion, tumor angiogenic activity, and vascular survival ability) in a series of 130 stage B/C patients with colorectal cancer treated with surgery alone (without adjuvant radiotherapy or chemotherapy). RESULTS: Inclusion of vasculature-related variables in the Dukes staging system significantly improved the prognostic categorization of patients, identifying subgroups of B-stage and C-stage patients with an up to 40% and 60% 5-year survival difference, respectively. CONCLUSIONS: Preliminary results show that the prognostic value of Dukes staging system is significantly improved after taking into account vasculature-related variables, which may be useful in stratifying patients for adjuvant therapies, highlighting also subgroups that may benefit the most from antiangiogenic agents.

Blood Vessels↗

PubMed2005

Immunodominance of poxviral-specific CTL in a human trial of recombinant-modified vaccinia Ankara.

Many recombinant poxviral vaccines are currently in clinical trials for cancer and infectious diseases. However, these agents have failed to generate T cell responses specific for recombinant gene products at levels comparable with T cell responses associated with natural viral infections. The recent identification of vaccinia-encoded CTL epitopes, including a new epitope described in this study, allows the simultaneous comparison of CTL responses specific for poxviral and recombinant epitopes. We performed detailed kinetic analyses of CTL responses in HLA-A*0201 patients receiving repeated injections of recombinant modified vaccinia Ankara encoding a string of melanoma tumor Ag epitopes. The vaccine-driven CTL hierarchy was dominated by modified vaccinia Ankara epitope-specific responses, even in patients who had not received previous smallpox vaccination. The only recombinant epitope that was able to impact on the CTL hierarchy was the melan-A26-35 analog epitope, whereas responses specific for the weaker affinity epitope NY-ESO-1(157-165) failed to be expanded above the level detected in prevaccination samples. Our results demonstrate that immunodominant vaccinia-specific CTL responses limit the effectiveness of poxviruses in recombinant vaccination strategies and that more powerful priming strategies are required to overcome immunodominance of poxvirus-specific T cell responses.

HLA-A Antigens↗

PubMed2005

Bone morphogenetic protein 2 (BMP-2) and induction of tumor angiogenesis.

PURPOSE: Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta family and play an important role in the regulation of embryonic vasculogenesis but their role in postnatal angiogenesis remains to be clarified. In this study we investigated a possible role of BMP-2 in the promotion of tumor angiogenesis. METHODS: We studied the effect of BMP-2 on human dermal microvascular endothelial cells (HDMECs) and examined a possible angiogenic activity of BMP-2 with the mouse sponge assay. The effect of BMP-2 overexpression on tumor vascularization was also analyzed in xenografts of human BMP-2 transfected MCF-7 breast cancer cells (MCF-7/BMP2) in mice. RESULTS: BMP receptor activation selectively induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) in contrast to the ERK1/2 MAP kinases. In keeping with this finding, BMP-2 had no significant effect on endothelial cell proliferation but promoted HDMEC tube formation in the matrigel assay. The transcription factor inhibitor of differentiation 1 (Id1), which is known to play an important role in neovascularization of tumors, was confirmed as a BMP target in HDMECs. Immunohistochemical analysis of sponge sections revealed that BMP-2 induced vascularization and showed an additive enhancement of angiogenesis with VEGF. In the murine breast cancer xenograft model, human MCF-7 cells with stable overexpression of BMP-2 developed vascularized tumors while empty vector control MCF-7 cells failed to form tumors. CONCLUSIONS: We conclude that activation of the BMP pathway by BMP-2 can promote vascularization and might be involved in tumor angiogenesis possibly by stimulating the Id1 and p38 MAPK pathway.

Animals↗

PubMed2005

The androgen receptor is significantly associated with vascular endothelial growth factor and hypoxia sensing via hypoxia-inducible factors HIF-1a, HIF-2a, and the prolyl hydroxylases in human prostate cancer.

PURPOSE: Hypoxia regulates key biological processes including angiogenesis via the transcription factor, hypoxia-inducible factor (HIF). In prostate cancer, angiogenesis is also influenced by androgens, and recent cell line studies suggest that this effect is partly mediated by HIF. The study aimed to assess whether a relationship exists in human prostate cancer between expression of the androgen receptor, HIFs, and the key angiogenesis factor, vascular endothelial growth factor (VEGF). EXPERIMENTAL DESIGN: A tissue microarray comprised of 149 radical prostatectomy specimens was constructed. Semiquantitative immunohistochemical analysis was used to assess the expression of the androgen receptor, VEGF and HIF-1a and 2a, and their regulatory prolyl hydroxylase enzymes (PHD1, PHD2, and PHD3). Statistical analysis compared these factors with each other and with prostate-specific antigen relapse. RESULTS: There was a significant correlation between HIF-1a and HIF-2a expression (P = 0.02), and with androgen receptor (P = 0.04 and P < 0.001, respectively) and VEGF expression (P = 0.05 and P < 0.001, respectively). VEGF was also significantly related to the androgen receptor (P = 0.05), whereas PHD2 was inversely related to HIF-2a expression. No significant association was shown between HIF-1a or HIF-2a and time to prostate-specific antigen recurrence (P = 0.20 and P = 0.94, respectively). CONCLUSIONS: These findings confirm the relationship between hypoxia and the androgen receptor in prostate cancer, and show for the first time, the role of HIF-2a in this disease process. They provide clinical evidence to support the recent cell line findings that androgens may regulate VEGF levels through the activation of HIF in androgen-sensitive tumors. Inhibition of both the HIF pathways may provide new therapeutic options in the management of this disease.

Aged↗

PubMed2005

Relation of erythropoietin and erythropoietin receptor expression to hypoxia and anemia in head and neck squamous cell carcinoma.

PURPOSE: The use of erythropoietin in head and neck squamous cell carcinoma (HNSCC) has been associated with poor survival. This study examines the protein and mRNA expression of erythropoietin and erythropoietin receptor in HNSCC and their relation to hypoxia, hemoglobin (Hb), and clinical outcome. EXPERIMENTAL DESIGN: The immunohistochemical expression of erythropoietin and erythropoietin receptor was assessed in 151 cases of HNSCC. Expression was compared with the hypoxia-dependent proteins hypoxia-inducible factor-1alpha (HIF-1alpha) and carbonic anhydrase-9 (CA-9) and correlated with clinical outcome. The mRNA expression of erythropoietin and erythropoietin receptor was measured in paired samples of HNSCC. RESULTS: Erythropoietin and erythropoietin receptor were expressed in 95% and 99% of tumors, respectively. Using a weighed expression score, there was a positive correlation between erythropoietin and erythropoietin receptor expression (r = 0.18, P = 0.03). HIF-1alpha (r = 0.38, P < 0.01) and CA-9 (r = 0.26, P = 0.002) correlated with erythropoietin expression, but there was no correlation with erythropoietin receptor. No correlation was found between Hb and erythropoietin (r = 0.07, P = 0.36) or erythropoietin receptor (r = -0.02, P = 0.8), and no survival difference between high and low erythropoietin or erythropoietin receptor expression (P = 0.59 and P = 0.98, respectively). The mRNA expression of erythropoietin (P = 0.03) but not erythropoietin receptor (P = 0.62) was significantly increased in 11 paired samples of HNSCC. CONCLUSION: In vivo, the HIF pathway regulates erythropoietin at the mRNA level but not erythropoietin receptor expression in HNSCC. Anemia does not seem to influence the hypoxic microenvironment of tumors sufficiently to alter the expression of erythropoietin. The effects of exogenous erythropoietin may be acting via receptors expressed on tumor cells in vivo, or on vascular cells, which also express the pathway.

Anemia↗

PubMed2005

Gorham-Stout syndrome: a monocyte-mediated cytokine propelled disease.

UNLABELLED: We studied the biological features and the immunophenotype of a cell culture established from the lesion of soft tissues of a woman affected by Gorham-Stout syndrome. We found that these cells belonged to a monocytic lineage with some characteristics of immature osteoclasts and were able to release large amounts of osteoclastogenic and angiogenic molecules that may contribute to disease progression. INTRODUCTION: Gorham-Stout syndrome is a rare disease characterized by osteolysis and proliferation of vascular or lymphatic vessels, with a severe outcome. Its etiology and the identification of the cell types involved are completely unknown. MATERIALS AND METHODS: A cell culture from a lesion of soft tissues was established, and its behavior in vitro and in immunodeficient mice was studied. We analyzed (1) the cell phenotype by flow cytometry; (2) the adhesive and migratory properties on different substrates; (3) the ability to differentiate into mature osteoclasts; (4) the production of osteclastogenic and angiogenic molecules; (5) the in vivo angiogenic activity of the cells subcutaneously implanted in mouse in a Matrigel plug; and (6) the ability to recapitulate the disease when transplanted in nude mice. RESULTS AND CONCLUSIONS: The established culture consisted of a morphologically homogeneous cell population belonging to a monocytic lineage having some features of an osteoclast-like cell type. Cells had an invasive phenotype, were angiogenic, and produced osteoclastogenic (IL-6, TGF-beta1, IL-1beta) and angiogenic (vascular endothelial growth factor-A [VEGF-A], CXCL-8) molecules when challenged with inflammatory cytokines. Immunodeficient mice injected with these cells did not show any bone lesions or vascular alteration, but had high amounts of circulating human IL-6 and VEGF-A. Cells isolated from a cutaneous lymphangiomatosis did not show any of these findings. These data suggest that cells of monocyte-macrophage lineage play an essential role in the pathogenesis of Gorham-Stout disease, whose progression is propelled by cytokine circuits that accelerate angiogenesis and osteoclastogenesis.

Animals↗

PubMed2005

Up-regulation of the Notch ligand Delta-like 4 inhibits VEGF-induced endothelial cell function.

Delta-like 4 (Dll4), a membrane-bound ligand for Notch1 and Notch4, is selectively expressed in the developing endothelium and in some tumor endothelium, and it is induced by vascular endothelial growth factor (VEGF)-A and hypoxia. Gene targeting studies have shown that Dll4 is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are currently not defined. In this study, we generated primary human endothelial cells that overexpress Dll4 protein to study Dll4 function and mechanism of action. Human umbilical vein endothelial cells retrovirally transduced with Dll4 displayed reduced proliferative and migratory responses selectively to VEGF-A. Expression of VEGF receptor-2, the principal signaling receptor for VEGF-A in endothelial cells, and coreceptor neuropilin-1 was significantly decreased in Dll4-transduced endothelial cells. Consistent with Dll4 signaling through Notch, expression of HEY2, one of the transcription factors that mediates Notch function, was significantly induced in Dll4-overexpressing endothelial cells. The gamma-secretase inhibitor L-685458 significantly reconstituted endothelial cell proliferation inhibited by immobilized extracellular Dll4 and reconstituted VEGFR2 expression in Dll4-overexpressing endothelial cells. These results identify the Notch ligand Dll4 as a selective inhibitor of VEGF-A biologic activities down-regulating 2 VEGF receptors expressed on endothelial cells and raise the possibility that Dll4 may be exploited therapeutically to modulate angiogenesis.

Adaptor Proteins, Signal Transducing↗