Serum levels of angiogenic cytokines decrease after radiotherapy in non-Hodgkin lymphomas.

PURPOSE: Serum levels of angiogenic cytokines decrease after radiotherapy in patients with cancer, and this may be relevant for treatment response and progression-free survival. Herein, we set out to determine whether circulating fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and platelet-derived growth factor-beta (PDGF-beta) decrease after radiotherapy in patients with non-Hodgkin lymphomas (NHLs) and if so, whether their decrease correlates with age, tumour histotype and stage, and radiation dose. MATERIAL AND METHODS: The serum levels of FGF-2, VEGF, HGF and PDGF-beta were evaluated before and after radiotherapy by an enzyme-linked immunosorbent assay (ELISA). These levels were correlated both reciprocally and with age, histotype, stage and radiation dose. RESULTS: After radiotherapy, FGF-2, VEGF and PDGF-beta, but not HGF, significantly decreased in relation to the radiation dose and response. No correlation was established between cytokine levels, except for VEGF and PDGF-beta, which decreased in parallel. Haemoglobin levels did not decrease after radiotherapy, while FGF-2, VEGF, HGF and PDGF-beta levels did not correlate with age, NHL stage and histotype. CONCLUSIONS: Soluble FGF-2, VEGF and PDGF-beta levels decline after radiotherapy in NHLs, and may have predictive significance for response to treatment and recurrence.

Validation of PDGFRbeta and c-Src tyrosine kinases as tumor/vessel targets in patients with multiple myeloma: preclinical efficacy of the novel, orally available inhibitor dasatinib.

Inhibition of multiple myeloma (MM) plasma cells in their permissive bone marrow microenvironment represents an attractive strategy for blocking the tumor/vessel growth associated with the disease progression. However, target specificity is an essential aim of this approach. Here, we identified platelet-derived growth factor (PDGF)-receptor beta (PDGFRbeta) and pp60c-Src as shared constitutively activated tyrosine-kinases (TKs) in plasma cells and endothelial cells (ECs) isolated from MM patients (MMECs). Our cellular and molecular dissection showed that the PDGF-BB/PDGFRbeta kinase axis promoted MM tumor growth and vessel sprouting by activating ERK1/2, AKT, and the transcription of MMEC-released proangiogenic factors, such as vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). Interestingly, pp60c-Src TK-activity was selectively induced by VEGF in MM tumor and ECs, and the use of small-interfering (si)RNAs validated pp60c-Src as a key signaling effector of VEGF loop required for MMEC survival, migration, and angiogenesis. We also assessed the antitumor/vessel activity of dasatinib, a novel orally bioactive PDGFRbeta/Src TK-inhibitor that significantly delayed MM tumor growth and angiogenesis in vivo, showing a synergistic cytotoxicity with conventional and novel antimyeloma drugs (ie, melphalan, prednisone, bor-tezomib, and thalidomide). Overall data highlight the biologic and therapeutic relevance of the combined targeting of PDGFRbeta/c-Src TKs in MM, providing a framework for future clinical trials.

Endothelial differentiation of hematopoietic stem and progenitor cells from patients with multiple myeloma.

PURPOSE: Vasculogenesis is a physiologic process typical of fetal development in which new blood vessels develop from undifferentiated precursors (or angioblasts). In tumors, near angiogenesis, vasculogenesis contributes to the formation of the microvascular plexus that is important for diffusion. Here, we show that hematopoietic stem and progenitor cells (HSPC) of multiple myeloma (MM) patients are able to differentiate into cells with endothelial phenotype on exposure to angiogenic cytokines. EXPERIMENTAL DESIGN: Circulating HSPCs were purified with an anti-CD133 antibody from patients with newly diagnosed MM before autologous transplantation and exposed to vascular endothelial growth factor (VEGF), fibroblast growth factor-2 and insulin-like growth factor in a 3-week culture. RESULTS: HSPCs gradually lost CD133 expression and acquired VEGF receptor-2, factor VIII-related antigen, and vascular endothelial-cadherin expression. The expression pattern overlapped with paired MM endothelial cells (MMEC). During culture, cells adhered to fibronectin, spread, and acquired an endothelial cell shape. Differentiated HSPCs also became capillarogenic in the Matrigel assay with maximal activity at the third week of culture. Bone marrow biopsies revealed HSPCs inside the neovessel wall in patients with MM but not in those with monoclonal gammopathy of undetermined significance. CONCLUSIONS: In patients with MM, but not in those with monoclonal gammopathy of undetermined significance, HSPCs contribute to the neovessel wall building together with MMECs. Therefore, besides angiogenesis, HSPC-linked vasculogenesis contributes to neovascularization in MM patients. Tentatively, we hypothesize that in HSPC cultures a multipotent cell population expressing low VEGF receptor-2 levels corresponds to the endothelial progenitor cell precursor and seems to be the MMEC precursor.

Zoledronic acid affects over-angiogenic phenotype of endothelial cells in patients with multiple myeloma.

Therapeutic doses of zoledronic acid markedly inhibit in vitro proliferation, chemotaxis, and capillarogenesis of bone marrow endothelial cells of patients with multiple myeloma. Zoledronic acid also induces a sizeable reduction of angiogenesis in the in vivo chorioallantoic membrane assay. These effects are partly sustained by gene and protein inhibition of vascular endothelial growth factor and vascular endothelial growth factor receptor 2 in an autocrine loop. Mevastatin, a specific inhibitor of the mevalonate pathway, reverts the zoledronic acid antiangiogenic effect, indicating that the drug halts this pathway. Our results provide evidence of a direct antiangiogenic activity of zoledronic acid on multiple myeloma patient-derived endothelial cells due to at least four different mechanisms identified either in vitro or in vivo. Tentatively, we suggest that the zoledronic acid antitumoral activity in multiple myeloma is also sustained by antiangiogenesis, which would partly account for its therapeutic efficacy in multiple myeloma.

Loss of inhibitory semaphorin 3A (SEMA3A) autocrine loops in bone marrow endothelial cells of patients with multiple myeloma.

Vascular endothelial growth factor165 (VEGF165) and semaphorin3A (SEMA3A) elicit pro- and antiangiogenic signals respectively in endothelial cells (ECs) by binding to their receptors VEGFR-2, neuropilin-1 (NRP1), and plexin-A1. Here we show that the VEGF165-driven angiogenic potential of multiple myeloma (MM) ECs is significantly higher than that of monoclonal gammopathy of undetermined significance (MGUS) ECs (MGECs) and human umbilical vein (HUV) ECs. This is probably due to a constitutive imbalance of endogenous VEGF165/SEMA3A ratio, which leans on VEGF165 in MMECs but on SEMA3A in MGECs and HUVECs. Exogenous VEGF165 induces SEMA3A expression in MGECs and HUVECs, but not in MMECs. Moreover, by counteracting VEGF165 activity as efficiently as an anti-VEGFR-2 antibody, exogenous SEMA3A restrains the over-angiogenic potential of MMECs. Our data indicate that loss of endothelial SEMA3A in favor of VEGF165 could be responsible for the angiogenic switch from MGUS to MM.

Bone marrow endothelial cells in multiple myeloma secrete CXC-chemokines that mediate interactions with plasma cells.

Bone marrow endothelial cells (EC) from patients with multiple myeloma (MM) were found to express and secrete higher amounts of the CXC-chemokines CXCL8/interleukin (IL)-8, CXCL11/interferon-inducible T-cell alpha chemoattractant (I-TAC), CXCL12/stromal cell-derived factor (SDF)-1alpha, and CCL2/monocyte chemotactic protein(MCP)-1 than EC from human umbilical vein (HUVEC), considered as a healthy counterpart. Paired plasma cells and several MM cell lines expressed cognate receptors of each chemokine to a variable extent. When cells were exposed to chemokines, CXCL8/IL-8 and CXCL12/SDF-1alpha stimulated their proliferation and all chemokines stimulated cell chemotaxis. It is suggested that angiogenesis also favours MM progression through the release of CXC-chemokines.

Antiangiogenesis for rheumatoid arthritis.

Angiogenesis, i.e., the induction of new blood vessels from existing vasculature, is a crucial event in the formation and maintenance of the pannus in rheumatoid arthritis (RA). The arthritis is characterized by destruction of peripheral joints in which the cartilage and bone are destroyed by proliferative synovitis. This is characterized by infiltration of inflammatory cells and formation of new blood vessels. Angiogenesis occurs since the early stage of the disease, and supports progression of the arthritis. It has been demonstrated in animal models of arthritis that inhibition of angiogenesis reduces of the arthritis. This suggests that pharmacological inhibition of angiogenesis may play an important role in the treatment of RA. In particular, disruption of new blood vessels can not only prevent delivery of nutrients to the inflammatory site, but can also lead to vessel regression, hence reversal of disease. To sum up, since angiogenesis is central in maintaining of synovitis in RA, antiangiogenesis probably represents a therapeutic tool. This view is supported by recent studies in animal models of arthritis where antiangiogenic drugs deliver a therapeutic benefit.

A VEGF-dependent autocrine loop mediates proliferation and capillarogenesis in bone marrow endothelial cells of patients with multiple myeloma.

The expression/function of vascular endothelial growth factor (VEGF) and its receptor 2 (VEGFR-2/KDR) in multiple myeloma (MM)-associated angiogenesis is under scrutiny. We show here that bone marrow endothelial cells (EC) from 16 patients with MM (MMEC) highly expressed VEGF-A (the main VEGF isoform) and VEGFR-2 at both mRNA and protein level, whereas EC from 14 patients with monoclonal gammopathy unassociated/unattributable (MG[u]) (MG[u]EC) and 12 human umbilical veins (HUVEC) expressed very low mRNAs and/or proteins. MMEC showed constitutive autophosphorylation in both VEGFR-2 and the associated extracellular signal-regulated kinase-2 (ERK-2), whereas this was marginal in MG[u]EC and HUVEC. MMEC proliferated rapidly and formed a closely-knit capillary meshwork on Matrigel. These cell functions were reduced in the other EC. Autophosphorylation, proliferation and capillarogenesis were prevented by a neutralizing anti-VEGF-A antibody, and more efficaciously by an anti-VEGFR-2 antibody. Both antibodies had no effect or were poorly effective on the other EC. These findings as a whole suggest the existence of an autocrine loop of VEGF in MMEC. Since this is very likely a mechanism for the amplification of VEGF activity in neovascularization, it would constitute an appropriate target for antiangiogenic management in MM.

Serum levels of angiogenic cytokines decrease after antineoplastic radiotherapy.

Serum levels of angiogenic cytokines decrease after radiotherapy in patients with cancer and their may have an impact on response to treatment and progression-free survival. Here, we have evaluated sera of patients before and after radiotherapy for various tumour types for levels of soluble fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) to assess whether these factors decrease after radiotherapy, and whether their diminution is related to the radiation dose, tumour type, age and haemoglobin level. We demonstrate that levels of FGF-2 and VEGF, but not HGF, decrease significantly, and that the extent of their diminution is related to the radiation dose and response.

Lymphatics at the crossroads of angiogenesis and lymphangiogenesis.

The lymphatic system is implicated in interstitial fluid balance regulation, immune cell trafficking, oedema and cancer metastasis. However, the sequence of events that initiate and coordinate lymphatic vessel development (lymphangiogenesis) remains obscure. In effect, the understanding of physiological regulation of lymphatic vasculature has been overshadowed by the greater emphasis focused on angiogenesis, and delayed by a lack of specific markers, thereby limiting this field to no more than a descriptive characterization. Recently, new insights into lymphangiogenesis research have been due to the discovery of lymphatic-specific markers and growth factors of vascular endothelial growth factor (VEGF) family, such as VEGF-C and VEGF-D. Studies using transgenic mice overexpressing VEGF-C and VEGF-D have demonstrated a crucial role for these factors in tumour lymphangiogenesis. Knowledge of lymphatic development has now been redefined at the molecular level, providing an interesting target for innovative therapies. This review highlights the recent insights and advances into the field of lymphatic vascular research, outlining the most important aspects of the embryo development, structure, specific markers and methods applied for studying lymphangiogenesis. Finally, molecular mechanisms involved in the regulation of lymphangiogenesis are described.