Expression of basic fibroblast growth factor is associated with poor outcome in non-Hodgkin's lymphoma

Exploiting the fibroblast growth factor receptor-1 vulnerability to therapeutically restrict the MYC-EZH2-CDKN1C axis-driven proliferation in Mantle cell lymphoma

Mantle cell lymphoma (MCL) is a lethal hematological malignancy with a median survival of 4 years. Its lethality is mainly attributed to a limited understanding of clinical tumor progression and resistance to current therapeutic regimes. Intrinsic, prolonged drug treatment and tumor-microenvironment (TME) facilitated factors impart pro-tumorigenic and drug-insensitivity properties to MCL cells. Hence, elucidating neoteric pharmacotherapeutic molecular targets involved in MCL progression utilizing a global "unified" analysis for improved disease prevention is an earnest need. Using integrated transcriptomic analyses in MCL patients, we identified a Fibroblast Growth Factor Receptor-1 (FGFR1), and analyses of MCL patient samples showed that high FGFR1 expression was associated with shorter overall survival in MCL patient cohorts. Functional studies using pharmacological intervention and loss of function identify a novel MYC-EZH2-CDKN1C axis-driven proliferation in MCL. Further, pharmacological targeting with erdafitinib, a selective small molecule targeting FGFRs, induced cell-cycle arrest and cell death in-vitro, inhibited tumor progression, and improved overall survival in-vivo. We performed extensive pre-clinical assessments in multiple in-vivo model systems to confirm the therapeutic potential of erdafitinib in MCL and demonstrated FGFR1 as a viable therapeutic target in MCL.

Vascular Growth in Lymphomas: Angiogenesis and Alternative Ways

The formation of new blood vessels is a critical process for tumor growth and may be achieved through different mechanisms. Angiogenesis represents the first described and most studied mode of vessel formation, but tumors may also use alternative ways to secure blood supply and eventually acquire resistance to anti-angiogenic treatments. These non-angiogenic mechanisms have been described more recently, including intussusceptive microvascular growth (IMG), vascular co-option, and vasculogenic mimicry. Like solid tumors, angiogenic and non-angiogenic pathways in lymphomas play a fundamental role in tumor growth and progression. In view of the relevant prognostic and therapeutic implications, a comprehensive understanding of these mechanisms is of paramount importance for improving the efficacy of treatment in patients with lymphoma. In this review, we summarize the current knowledge on angiogenic and non-angiogenic mechanisms involved in the formation of new blood vessels in Hodgkin's and non-Hodgkin's lymphomas.

Bisphenol A-induced DNA damages promote to lymphoma progression in human lymphoblastoid cells through aberrant CTNNB1 signaling pathway

Lymphoma is a group of blood cancers that develop from the immune system, and one of the main risk factors is associated with exposure to environmental chemicals. Bisphenol A (BPA) is a common chemical used in the manufacture of materials in polycarbonate and epoxy plastic products and can interfere with the immune system. BPA is considered to possibly induce lymphoma development by affecting the immune system, but its potential mechanisms have not been well established. This study performed a gene-network analysis of microarray data sets in human lymphoma tissues as well as in human cells with BPA exposure to explore module genes and construct the potential pathway for lymphomagenesis in response to BPA. This study provided evidence that BPA exposure resulted in disrupted cell cycle and DNA damage by activating CTNNB1, the initiator of the aberrant constructed CTNNB1-NFKB1-AR-IGF1-TWIST1 pathway, which may potentially lead to lymphomagenesis.

Comparative randomized trial evaluating the effect of proton pump inhibitor versus histamine 2 receptor antagonist as an adjuvant therapy in diffuse large B-cell lymphoma

The development of drug resistance remains the major obstacle to clinical efficacy of cancer chemotherapy. Consequently, finding new therapeutic options for cancerous patients is an urgent need. Sixty newly diagnosed diffuse large B-cell lymphoma (DLBCL) patients were recruited from Clinical Oncology Department, Faculty of Medicine, Menoufia University, Egypt prospectively randomized to three groups (n = 20 for each group). Group one (control group) received R-CHOP standard chemotherapy {Rituximab, Cyclophosphamide, Hydroxyldaunorubicin (Doxorubicin)®, Vincristine (oncovin)®, prednisolone in the first five days of cycle}, group two received lansoprazole (LAN) 60 mg p.o. bid for only one week before starting each of cycle + R-CHOP and group three received famotidine (FAM) 40 mg p.o. once daily one week before cycle and continues daily through the cycle + R-CHOP for six cycles. Blood samples were obtained for biochemical analysis of transforming growth factor-β (TGF-β), Basic fibroblast growth factor (bFGF), interleukin-9 (IL-9), nuclear factor-kappa B (NF-κB) and Caspase 3 before and after six cycles of therapy. The obtained data showed that LAN and FAM resulted in significant decrease in (LDH, TGF-β, bFGF and IL-9, respectively) and significant increase in (Caspase-3). In addition, LAN produced a significant elevation in the response rate compared to the control group or the FAM group. Both LAN and FAM as adjuvant therapy represents a promising anticancer strategy in DLBCL by modulation of malignancy homeostasis mechanisms and boosting chemotherapy antitumor effects without further toxicity. In addition, LAN has a synergetic effect in improving the response rate.Trial registration Clinical Trial.gov Identifier: NCT0364707.

Modeling hyperosmotic blood-brain barrier opening within human tissue-engineered in vitro brain microvessels

As the majority of therapeutic agents do not cross the blood-brain barrier (BBB), transient BBB opening (BBBO) is one strategy to enable delivery into the brain for effective treatment of CNS disease. Intra-arterial infusion of the hyperosmotic agent mannitol reversibly opens the BBB; however, widespread clinical use has been limited due to the variability in outcomes. The current model for mannitol-induced BBBO assumes a transient but homogeneous increase in permeability; however, the details are poorly understood. To elucidate the mechanism of hyperosmotic opening at the cellular level, we developed a tissue-engineered microvessel model using stem cell-derived human brain microvascular endothelial cells (BMECs) perturbed with clinically relevant mannitol doses. This model recapitulates physiological shear stress, barrier function, microvessel geometry, and cell-matrix interactions. Using live-cell imaging, we show that mannitol results in dose-dependent and spatially heterogeneous increases in paracellular permeability through the formation of transient focal leaks. Additionally, we find that the degree of BBB opening and subsequent recovery is modulated by treatment with basic fibroblast growth factor. These results show that tissue-engineered BBB models can provide insight into the mechanisms of BBBO and hence improve the reproducibility of hyperosmotic therapies for treatment of CNS disease.

Molecular and clinical significance of fibroblast growth factor 2 (FGF2 /bFGF) in malignancies of solid and hematological cancers for personalized therapies

Fibroblast growth factor (FGF) signaling is essential for normal and cancer biology. Mammalian FGF family members participate in multiple signaling pathways by binding to heparan sulfate and FGF receptors (FGFR) with varying affinities. FGF2 is the prototype member of the FGF family and interacts with its receptor to mediate receptor dimerization, phosphorylation, and activation of signaling pathways, such as Ras-MAPK and PI3K pathways. Excessive mitogenic signaling through the FGF/FGFR axis may induce carcinogenic effects by promoting cancer progression and increasing the angiogenic potential, which can lead to metastatic tumor phenotypes. Dysregulated FGF/FGFR signaling is associated with aggressive cancer phenotypes, enhanced chemotherapy resistance and poor clinical outcomes. In vitro experimental settings have indicated that extracellular FGF2 affects proliferation, drug sensitivity, and apoptosis of cancer cells. Therapeutically targeting FGF2 and FGFR has been extensively assessed in multiple preclinical studies and numerous drugs and treatment options have been tested in clinical trials. Diagnostic assays are used to quantify FGF2, FGFRs, and downstream signaling molecules to better select a target patient population for higher efficacy of cancer therapies. This review focuses on the prognostic significance of FGF2 in cancer with emphasis on therapeutic intervention strategies for solid and hematological malignancies.

The role of angiogenesis in human non-Hodgkin lymphomas

The role of angiogenesis in the growth of lymphomas and survival of patients with leukemias and other hematological malignancies has become evident since 1994. Angiogenic factors, such as vascular endothelial growth factor and its receptors together with other tumor microenvironment components, including myelo-monocytic cell, mast cells, endothelial progenitor cells, and circulating endothelial cells, have been shown to be important in the progression and maintenance of lymphoproliferative disorders. In this review article, we present an overview of the literature focusing on the relationship between angiogenesis and disease progression and the recent advantages in the antiangiogenic treatment in human non-Hodgkin lymphomas.

Fibroblast growth factor-2 (FGF2) and syndecan-1 (SDC1) are potential biomarkers for putative circulating CD15+/CD30+ cells in poor outcome Hodgkin lymphoma patients

Background

High risk, unfavorable classical Hodgkin lymphoma (cHL) includes those patients with primary refractory or early relapse, and progressive disease. To improve the availability of biomarkers for this group of patients, we investigated both tumor biopsies and peripheral blood leukocytes (PBL) of untreated (chemo-naïve, CN) Nodular Sclerosis Classic Hodgkin Lymphoma (NS-cHL) patients for consistent biomarkers that can predict the outcome prior to frontline treatment.

Methods and materials

Bioinformatics data mining was used to generate 151 candidate biomarkers, which were screened against a library of 10 HL cell lines. Expression of FGF2 and SDC1 by CD30+ cells from HL patient samples representing good and poor outcomes were analyzed by qRT-PCR, immunohistochemical (IHC), and immunofluorescence analyses.

Results

To identify predictive HL-specific biomarkers, potential marker genes selected using bioinformatics approaches were screened against HL cell lines and HL patient samples. Fibroblast Growth Factor-2 (FGF2) and Syndecan-1 (SDC1) were overexpressed in all HL cell lines, and the overexpression was HL-specific when compared to 116 non-Hodgkin lymphoma tissues. In the analysis of stratified NS-cHL patient samples, expression of FGF2 and SDC1 were 245 fold and 91 fold higher, respectively, in the poor outcome (PO) group than in the good outcome (GO) group. The PO group exhibited higher expression of the HL marker CD30, the macrophage marker CD68, and metastatic markers TGFβ1 and MMP9 compared to the GO group. This expression signature was confirmed by qualitative immunohistochemical and immunofluorescent data. A Kaplan-Meier analysis indicated that samples in which the CD30+ cells carried an FGF2+/SDC1+ immunophenotype showed shortened survival. Analysis of chemo-naive HL blood samples suggested that in the PO group a subset of CD30+ HL cells had entered the circulation. These cells significantly overexpressed FGF2 and SDC1 compared to the GO group. The PO group showed significant down-regulation of markers for monocytes, T-cells, and B-cells. These expression signatures were eliminated in heavily pretreated patients.

Conclusion

The results suggest that small subsets of circulating CD30+/CD15+ cells expressing FGF2 and SDC1 represent biomarkers that identify NS-cHL patients who will experience a poor outcome (primary refractory and early relapsing).

Phase II open label study of the oral vascular endothelial growth factor-receptor inhibitor PTK787/ZK222584 (vatalanib) in adult patients with refractory or relapsed diffuse large B-cell lymphoma

PTK787/ZK222584 (vatalanib), an orally active inhibitor of vascular endothelial growth factor receptors (VEGFRs), was evaluated in this phase II study of 20 patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL). Patients received once-daily PTK787/ZK222584 at a target dose of 1250 mg. Eighteen patients were evaluable for response: one patient had a complete response (CR), six patients had stable disease but subsequently progressed, 10 patients had progressive disease by three cycles and one subject withdrew before response evaluation. The patient who attained a CR underwent autologous stem cell transplant and remains disease-free 76 months after study completion. There were no grade 4 toxicities. Grade 3 thrombocytopenia occurred in 20% and grade 3 hypertension occurred in 10%. There were no episodes of grade 3 proteinuria. In conclusion, PTK787/ZK222584 was well tolerated in a heavily pretreated population of patients with DLBCL, although its therapeutic potential as a single agent in DLBCL appears limited.

Characterization of FGF receptor expression in human neutrophils and their contribution to chemotaxis

Several members of the fibroblast growth factor (FGF) family are potent endothelial cell (EC) mitogens and angiogenic factors, and their activities can be mediated by four tyrosine kinase receptors (FGFR1–4). In addition, FGFs can induce the release of inflammatory mediators by ECs and the expression of adhesion molecules at their surface, thereby favoring the recruitment and transvascular migration of inflammatory cells such as neutrophils. Neither the expression nor the biological activities that could be mediated by FGFRs have been investigated in human neutrophils. By biochemical and cytological analyses, we observed that purified circulating human neutrophils from healthy individuals expressed varying levels of FGFRs in their cytosol and at their cytoplasmic membrane. FGFR-2 was identified as the sole cell surface receptor, with FGFR-1 and -4 localizing in the cytosol and FGFR-3 being undetectable. We assessed the capacity of FGF-1 and FGF-2 to induce neutrophil chemotaxis in a modified Boyden microchamber and observed that they increase neutrophil transmigration at 10−10 and 10−9 M and by 1.77- and 2.34-fold, respectively, as compared with PBS-treated cells. Treatment with a selective anti-FGFR-2 antibody reduced FGF-1-mediated chemotaxis by 75% and abrogated the effect of FGF-2, while the blockade of FGFR-1 and -4 partially inhibited (15–40%) FGF-chemotactic activities. In summary, our data are the first to report the expression of FGF receptors in human neutrophils, with FGF-1 and FGF-2 promoting neutrophil chemotaxis mainly through FGFR-2 activation.

Angiogenesis-related growth factors and cytokines in the serum of patients with B non-Hodgkin lymphoma; relation to clinical features and response to treatment

Increased angiogenesis has been shown to be a feature of non-Hodgkin lymphomas (NHL). In the current study, the pretreatment levels of circulating molecules related to angiogenesis were determined in 49 B-cell NHL patients and correlated with histological grade, disease stage and prognostic score. In 25 patients, the same molecules were defined after standard treatment. Vascular endothelial growth factor (VEGF), angiogenin, interleukin-2 (IL-2), IL-6, IL-8 and IL-16 were measured. Increased levels of VEGF, IL-6 and IL-8 were found in the whole group of untreated patients in comparison with normal controls (P < 0.05), whereas, IL-2 was higher in the subgroup of indolent NHL. Overall, there was no significant decrease in the levels of these molecules after treatment. However, by stratification into group of responders vs. non-responders pretreatment IL-8 was significantly increased whereas IL-16 was decreased in the subgroup of complete responders. According to the REAL classification IL-2 was higher in the low risk compared with intermediate plus high-risk group. There was no association with disease stage or the International Prognostic Score. Both indolent and aggressive B cell lymphomas have increased production of angiogenic mediators and cytokines with IL-8 and IL-16 potentially reflecting the response to treatment.

The expression of fibroblast growth factors and their receptors in Hodgkin's lymphoma

The expression of fibroblast growth factors (FGF1 and FGF2) and their receptors has been reported in a variety of human neoplasms, including haematological neoplasia. Fibroblast growth factors can promote tumour growth directly, or indirectly through promoting the growth of vessels. In the present study, we evaluated the expression of FGF1 and FGF2 as well as FGF receptors 1-4 (FGFR1-FGFR4) in 39 cases of Hodgkin's lymphoma, including all subtypes, as well as Hodgkin's lymphoma cell lines. FGF1 and FGF2 and their receptors FGFR2-FGFR4, but not FGFR1, were found to be expressed by the malignant cells in the majority of cases. Interestingly, only FGFR3, but none of the FGFs or the other FGFRs, was expressed by the Hodgkin's lymphoma cell lines. This indicates that only FGFR3 is constitutively expressed by Hodgkin's lymphoma cells, whereas FGFs and the other FGFRs are induced in vivo. Culture of the Hodgkin's cell lines under conditions of hypoxic stress could induce vascular endothelial growth factor (VEGF) but not FGF expression. FGFs, in contrast to VEGF, might be expressed in response to paracrine stimuli. In situ hybridization did not reveal FGFR3 gene amplification or translocation as the cause of constitutive FGFR3 expression, as has been shown in a subset of multiple myeloma. FGFR3 might be expressed as part of the Hodgkin's cell phenotype. The demonstration of widespread expression of FGFs and some of their receptors in Hodgkin's lymphoma suggests that FGFs are important for sustaining growth of the lymphoma and suggests that anti-FGF antibodies could be used as an adjuvant treatment.

Tenascin and microvessel stromal changes in patients with non-Hodgkin's lymphoma are isolated to the sites of disease and vary in correlation to disease activity

This study investigated stromal changes in expression of tenascin and vasculogenesis in lymphoma. Documenting the dynamic nature of the stromal changes in lymphoma in relation to response to therapy is helpful in planning new therapies directed at these targets. Two hundred and sixty one samples from 111 patients with varying types of non-Hodgkin's lymphoma were reviewed and examined using immunohistochemistry techniques. Samples were stained for factor VIII - related antigen for microvessel density (MVD) analysis and anti-tenascin antibody for qualitative assessment of the stromal expression. Multiple samples from the same patient were taken at the same point in time to assess whether stromal changes were limited to sites of disease. Multiple samples were examined over the course of a patient's illness to assess whether the stromal changes were modulated according to disease activity. There was a significant increase in tenascin expression and MVD in the sites of disease compared with uninvolved sites (p = 0.01 and p < 0.0001, respectively). In patients who responded to therapy, there was a decrease in the expression of tenascin (p = 0.0049) and MVD (p < 0.0001), and in those with disease progression there was an increase in the tenascin expression (p = 0.0050) and MVD (p < 0.0001). Our results suggest stromal changes are isolated to the sites of disease within patients, allowing targeted therapies to be developed. Further, stromal changes correlate with disease response over the course of the patient's disease. This new finding may have implications for the timing of anti-stromally directed therapies.

Angiogenesis in malignant lymphoma

PURPOSE OF REVIEW

Angiogenesis plays an important role in the pathophysiology of both solid tumors and hematologic malignancies. Angiogenesis-associated parameters are important prognosticators, and tumor blood vessels are an emerging target for therapy. This review addresses the evidence of the role of angiogenesis in malignant lymphoma and discusses some therapeutic implications.

RECENT FINDINGS

In angiogenesis assays, lymphoma cells show angiogenic properties. Tumor vascularization is higher in lymphoma tissue than in reactive lymph nodes and increases in step with clinically more aggressive lymphoma subtypes and advanced-stage disease. High levels of vascular endothelial growth factor in blood and tissue are associated with adverse prognosis. Vascular endothelial growth factor and vascular endothelial growth factor receptors are also present in lymphoma cells. Therapy against vascular endothelial growth factor in animal models is effective and points to both the tumor cell and the host endothelium as targets. Structural microvessel abnormalities are present in some lymphoma subtypes. The role of angiogenesis might vary in lymphoma subtypes because the prognostic value of microvessel density and the expression of angiogenesis-related molecules differ between lymphoma subtypes. There are also differences in blood vessel phenotype between lymphoma subtypes. This heterogeneity may have implications for antiangiogenic therapies. Antiangiogenic therapy in human lymphoma is still in its infancy.

SUMMARY

The role of angiogenesis in malignant lymphoma is evident. Tumor vasculature is an attractive target for lymphoma therapy. Differences between lymphoma subtypes must be taken into account in the selection of the most suitable patients for trials with antiangiogenic agents.

Effective treatment of experimental human non-Hodgkin's lymphomas with antagonists of growth hormone-releasing hormone

Antagonists of growth hormone-releasing hormone (GHRH) were shown to inhibit the growth of various cancers. We investigated the antitumor activity and the mechanism of action of GHRH antagonists in human non-Hodgkin's lymphomas (NHL). Nude mice bearing xenografts of RL and HT human NHL were treated with GHRH antagonists MZ-5-156 and MZ-J-7-138 at a dose of 40 microg twice daily. The concentrations of serum IGF-1 and GHRH, bFGF, and VEGF in tumor tissue were measured by radioimmunoassays. Expression of GHRH and splice variant 1 of the GHRH receptor in both cell lines was examined by RT-PCR. The effects of MZ-5-156, MZ-J-7-138 and GHRH on cell proliferation were evaluated in vitro. Treatment with MZ-5-156 and MZ-J-7-138 significantly (P < 0.05) inhibited the growth of RL and HT tumors by 59.9-73.9%. High-affinity binding sites for GHRH and mRNA for GHRH and splice variant-1 of the GHRH receptors were found on RL and HT tumors. RL and HT cells contained GHRH peptide, and their growth in vitro was significantly inhibited by both antagonists. IGF-I levels in serum of mice were significantly decreased by antagonist MZ-5-156. Therapy with GHRH antagonists also significantly reduced tumoral bFGF, whereas VEGF levels were not suppressed. Our findings suggest that GHRH antagonists inhibit the growth of RL and HT lymphomas by direct effects mediated by tumoral receptors for GHRH. GHRH antagonists could offer a new therapeutic modality for the management of advanced NHL.

Serum levels of inflammatory cytokines at diagnosis correlate to the bcl-6 and CD10 defined germinal centre (GC) phenotype and bcl-2 expression in patients with diffuse large B-cell lymphoma

Circulating inflammatory cytokines have a prognostic impact independent of the information provided by the International Prognostic Index (IPI) in diffuse large B-cell lymphoma (DLBCL). The present study characterized prognostic cytokines in relation to stage-specific B-cell differentiation antigens and bcl-2 protein expression, assessed by immunohistochemistry in de novo DLBCL. Serum levels of interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) were found to be significantly lower in patients with a germinal centre (GC) phenotype (co-expression of bcl-6 and CD10) compared with the non-GC phenotype. IL-6 and TNF-alpha levels were significantly elevated in patients expressing bcl-2 protein. Serum levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were not associated with the GC phenotype. On the contrary, both VEGF and bFGF were strongly correlated to bcl-2 expression. In survival analysis, IPI score remained the most important independent prognostic factor. However, IL-6 and VEGF, combined with non-GC phenotype and bcl-2 positivity, respectively, had a similar independent prognostic power as the IPI. In conclusion, our data suggest that inflammatory cytokines are differently distributed in the GC and non-GC phenotypes and correlate to bcl-2 expression. Combining these biomarkers may add to the prognostic information given by clinical variables in the IPI alone.

Increased Vascularization Predicts Favorable Outcome in Follicular Lymphoma

Purpose: In malignant lymphoma, angiogenesis has been associated with adverse outcome or more aggressive clinical behavior. This correlation has been established in groups of patients with a large heterogeneity regarding lymphoma subtypes and treatment regimens. The aim of this study is to investigate the significance of vascularization in patients with follicular lymphoma receiving uniform first-line treatment.

Experimental Design: We assessed microvessel density (MVD) in pretreatment lymph node biopsies of 46 previously untreated patients with follicular lymphoma using anti-CD34 immunohistochemical staining and interactive quantification. In a selection of cases, vascular endothelial growth factor (VEGF)-RNA in situ hybridization was done. Patients were treated with cyclophosphamide-vincristine-prednisone induction chemotherapy combined with IFN-α2b. Thirty-six patients responded and received IFN-α as maintenance therapy.

Results: MVD ranged from 10 to 70 per measurement field of 0.19 mm2 (median, 38). Median progression-free survival was 47 months in patients with MVD in the highest tertile and only 13 months in patients with lower MVD. Overall survival in patients with low vessel density was 59 months. In patients with high vessel density, median overall survival was not reached. Multivariate analysis indicated that MVD was independently associated with overall survival. There was a lack of correlation between VEGF-RNA expression and vessel density.

Conclusion: This study shows that in follicular lymphoma increased vascularization is associated with improved clinical outcome. Furthermore, VEGF-A expression seems not to be involved in follicular lymphoma angiogenesis.

Chronic idiopathic myelofibrosis: independent prognostic importance of bone marrow microvascular density evaluated by CD105 (endoglin) immunostaining

Microvascular density (MVD) is substantially increased in bone marrow biopsies of patients with chronic idiopathic myelofibrosis (CIMF). CD105, a useful molecule for assessing MVD in various malignancies, is preferentially expressed by recently formed microvessels. Increased serum-soluble CD105 in patients with chronic myeloproliferative disorders, including CIMF, was documented. CD105 MVD has not so far been investigated in CIMF: to this end, the results in 55 patients with CIMF and 21 controls were compared with the conventional CD34 immunostaining as well as traditional histological and clinical disease features. The MVD mean values estimated by both CD105 and CD34 were significantly higher in CIMF patients than in controls (P<0.00001). In addition, the proportion of CD105-positive megakaryocytes was significantly higher in CIMF than in controls (P<0.0001). A degree of reticulin fibrosis >2 correlated with increased CD105 MVD (P=0.05). A multivariate analysis confirmed that CD105-positive MVD was an independent adverse prognosticator. This study demonstrates that while MVD, as assessed by both CD34 and CD105 immunostaining, is significantly increased in CIMF, only CD105-determined MVD correlates with the degree of fibrosis and is prognostically relevant. These findings provide a rationale for the investigational use of anti-CD105-targeted drugs in CIMF.

Inhibition of bFGF/EGF-dependent endothelial cell proliferation by the hyaluronan-binding protease from human plasma

Recently we identified a plasma serine protease with a high affinity to glycosaminoglycans like heparin or hyaluronic acid, termed hyaluronan-binding protease (HABP). Since glycosaminoglycans are found on cell surfaces and in the extracellular matrix a physiological role of this plasma protease in a pericellular environment was postulated. Here we studied the influence of HABP on the regulation of endothelial cell growth. We found that HABP efficiently prevented the basic fibroblast growth factor/epidermal growth factor (bFGF/EGF)-dependent proliferation of human umbilical vein endothelial cells. Proteolytic cleavage of adhesion molecules was found to be involved, but was not solely responsible for the anti-proliferative activity. Pre-treatment of growth factor-supplemented cell culture medium with HABP indicated that no direct contact between the active protease and cells was required for growth inhibition. In vitro studies revealed a growth factor-directed activity of HABP, resulting in complexation and partial hydrolysis and, thus, inactivation of basic fibroblast growth factor, a potent mitogen for endothelial cells. Heparin and heparan sulfate fully protected bFGF from complexation and cleavage by HABP, although these glycosaminoglycans are known to enhance the proteolytic activity of HABP. This finding suggested that free circulating bFGF rather than bFGF bound to heparan sulfate proteoglycans would be a physiologic substrate. In conclusion, down-regulation of bFGF-dependent endothelial cell growth represents an important mechanism through which HABP could control cell growth in physiologic or pathologic processes like angiogenesis, wound healing or tumor development.