Kinetic and Angiogenic Activity of Circulating Endothelial Colony Forming Cells in Patients with Infantile Haemangioma Receiving Propranolol.

Endothelial progenitor cells (EPCs) have been suggested to contribute to the neovascularization of infantile haemangioma (IH). There is strong evidence of the efficacy of propranolol in the treatment of IH, possibly by inhibiting both vasculogenesis and angiogenesis in the tumour. We evaluate the frequency of circulating endothelial colony forming cells (ECFCs), as the best EPC surrogate, in patients with IH at diagnosis and while receiving propranolol by an ex vivo 12-month longitudinal study.

The role of endothelial colony forming cells in kidney cancer's pathogenesis, and in resistance to anti-VEGFR agents and mTOR inhibitors: A speculative review.

Renal cell carcinoma (RCC) is highly dependent on angiogenesis, due to the overactivation of the VHL/HIF/VEGF/VEGFRs axis; this justifies the marked sensitivity of this neoplasm to antiangiogenic agents which, however, ultimately fail to control tumor growth. RCC also frequently shows alterations in the mTOR signaling pathway, and mTOR inhibitors have shown a similar pattern of initial activity/late failure as pure antiangiogenic agents. Understanding mechanisms of resistance to these agents would be key to improve the outcome of our patients.

The spleen of patients with myelofibrosis harbors defective mesenchymal stromal cells.

Splenic hematopoiesis is a major feature in the course of myelofibrosis (MF). In fact, the spleen of patients with MF contains malignant hematopoietic stem cells retaining a complete differentiation program, suggesting both a pivotal role of the spleen in maintaining the disease and a tight regulation of hematopoiesis by the splenic microenvironment, in particular by mesenchymal stromal cells (MSCs). Little is known about splenic MSCs (Sp-MSCs), both in normal and in pathological context.

VEGF-induced intracellular Ca oscillations are down-regulated and do not stimulate angiogenesis in breast cancer-derived endothelial colony forming cells.

Endothelial colony forming cells (ECFCs) represent a population of truly endothelial precursors that promote the angiogenic switch in solid tumors, such as breast cancer (BC). The intracellular Ca toolkit, which drives the pro-angiogenic response to VEGF, is remodelled in tumor-associated ECFCs such that they are seemingly insensitive to this growth factor. This feature could underlie the relative failure of anti-VEGF therapies in cancer patients.

Stromal Cell-Derived Factor-1α Promotes Endothelial Colony-Forming Cell Migration Through the Ca-Dependent Activation of the Extracellular Signal-Regulated Kinase 1/2 and Phosphoinositide 3-Kinase/AKT Pathways.

Stromal cell-derived factor-1α (SDF-1α) drives endothelial colony-forming cell (ECFC) homing and incorporation within neovessels, thereby restoring tissue perfusion in ischemic tissues and favoring tumor vascularization and metastasis. SDF-1α stimulates ECFC migration by activating the G-protein-coupled receptor, CXCR4, and then engaging the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway. Sporadic evidence showed that SDF-1α may also act through an increase in intracellular Ca concentration ([Ca]) in bone marrow-derived hematopoietic progenitor cells and fully differentiated endothelial cells.

Primary myelofibrosis: Older age and high JAK2V617F allele burden are associated with elevated plasma high-sensitivity C-reactive protein levels and a phenotype of progressive disease.

We measured plasma levels of high-sensitivity C-reactive protein (hs-CRP) in 526 subjects with primary myelofibrosis (PMF). Thirty-eight percent had an elevated hs-CRP level (≥0.3mg/dL).

Liposomes as a Putative Tool to Investigate NAADP Signaling in Vasculogenesis.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the newest discovered intracellular second messengers, which is able to release Ca stored within endolysosomal (EL) vesicles. NAADP-induced Ca signals mediate a growing number of cellular functions, ranging from proliferation to muscle contraction and differentiation. Recently, NAADP has recently been shown to regulate angiogenesis by promoting endothelial cell growth.

Breast and renal cancer-Derived endothelial colony forming cells share a common gene signature.

Background: Neovascularisation supports the metastatic switch in many aggressive solid cancers. Tumour neovessels are mostly lined by endothelial cells sprouting from nearby capillaries, but they could also be contributed by circulating endothelial progenitor cells (EPCs). However, scant information is available about tumour-derived EPCs.

Arachidonic acid-evoked Ca signals promote nitric oxide release and proliferation in human endothelial colony forming cells.

Arachidonic acid (AA) stimulates endothelial cell (EC) proliferation through an increase in intracellular Ca concentration ([Ca]), that, in turn, promotes nitric oxide (NO) release. AA-evoked Ca signals are mainly mediated by Transient Receptor Potential Vanilloid 4 (TRPV4) channels. Circulating endothelial colony forming cells (ECFCs) represent the only established precursors of ECs.

Tie2 Expressing Monocytes in the Spleen of Patients with Primary Myelofibrosis.

Primary myelofibrosis (PMF) is a Philadelphia-negative (Ph-) myeloproliferative disorder, showing abnormal CD34+ progenitor cell trafficking, splenomegaly, marrow fibrosis leading to extensive extramedullary haematopoiesis, and abnormal neoangiogenesis in either the bone marrow or the spleen. Monocytes expressing the angiopoietin-2 receptor (Tie2) have been shown to support abnormal angiogenic processes in solid tumors through a paracrine action that takes place in proximity to the vessels. In this study we investigated the frequency of Tie2 expressing monocytes in the spleen tissue samples of patients with PMF, and healthy subjects (CTRLs), and evaluated their possible role in favouring spleen angiogenesis.

Targeting Stim and Orai Proteins as an Alternative Approach in Anticancer Therapy.

An increase in intracellular Ca2+ concentration plays a key role in the establishment of many cancer hallmarks, including aberrant proliferation, migration, invasion, resistance to apoptosis and angiogenesis. The dysregulation of Ca2+ entry is one of the most subtle mechanisms by which cancer cells overwhelm their normal counterparts and gain the adaptive advantages that result in tumour growth, vascularisation and dissemination throughout the organism. Both constitutive and agonist-induced Ca2+ influx may be mediated by store-dependent as well as store-independent Ca2+ entry routes.

Increased plasma nicotinamide phosphoribosyltransferase is associated with a hyperproliferative phenotype and restrains disease progression in MPN-associated myelofibrosis.

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a clonal, neoplastic disorder of the hematopoietic stem cells, in which inflammation and immune dysregulation play an important role. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), also known as visfatin, is a cytokine implicated in a number of inflammatory and neoplastic diseases. Here plasma levels of eNAMPT in patients with MPN-associated myelofibrosis and their effects on disease phenotype and outcomes were examined.

Endoplasmic Reticulum Ca(2+) Handling and Apoptotic Resistance in Tumor-Derived Endothelial Colony Forming Cells.

Truly endothelial progenitor cells (EPCs) can be mobilized from bone marrow to support the vascular network of growing tumors, thereby sustaining the metastatic switch. Endothelial colony forming cells (ECFCs) are the only EPC subtype belonging to the endothelial phenotype and capable of incorporating within neovessels. The intracellular Ca(2+) machinery plays a key role in ECFC activation and is remodeled in renal cellular carcinoma-derived ECFCs (RCC-ECFCs).

Constitutive Store-Operated Ca(2+) Entry Leads to Enhanced Nitric Oxide Production and Proliferation in Infantile Hemangioma-Derived Endothelial Colony-Forming Cells.

Clonal endothelial progenitor cells (EPCs) have been implicated in the aberrant vascular growth that features infantile hemangioma (IH), the most common benign vascular tumor in childhood that may cause ulceration, bleeding, and/or permanent disfigurement. Endothelial colony-forming cells (ECFCs), truly endothelial EPCs endowed with clonal ability and capable of forming patent vessels in vivo, remodel their Ca(2+) toolkit in tumor-derived patients to acquire an adaptive advantage. Particularly, they upregulate the proangiogenic store-operated Ca(2+) entry (SOCE) pathway due to the overexpression of its underlying components, that is, stromal interaction molecule 1 (Stim1), Orai1, and transient receptor potential canonical 1 (TRPC1).

Dysregulation of VEGF-induced proangiogenic Ca2+ oscillations in primary myelofibrosis-derived endothelial colony-forming cells.

Endothelial progenitor cells could be implicated in the aberrant neoangiogenesis that occurs in bone marrow and spleen in patients with primary myelofibrosis (PMF). However, antivascular endothelial growth factor (VEGF) monotherapy had only a modest and transient effect in these individuals. Recently it was found that VEGF-induced proangiogenic intracellular Ca(2+) oscillations could be impaired in endothelial progenitor cells of subjects with malignancies.

Endothelial progenitor cells support tumour growth and metastatisation: implications for the resistance to anti-angiogenic therapy.

Endothelial progenitor cells (EPCs) have recently been shown to promote the angiogenic switch in solid neoplasms, thereby promoting tumour growth and metastatisation. The genetic suppression of EPC mobilization from bone marrow prevents tumour development and colonization of remote organs. Therefore, it has been assumed that anti-angiogenic treatments, which target vascular endothelial growth factor (VEGF) signalling in both normal endothelial cells and EPCs, could interfere with EPC activation in cancer patients.

JAK2 exon 14 skipping in patients with primary myelofibrosis: a minor splice variant modulated by the JAK2-V617F allele burden.

Background: Primary myelofibrosis (PMF) is an acquired clonal disease of the hematopoietic stem cell compartment, characterized by bone marrow fibrosis, anemia, splenomegaly and extramedullary hematopoiesis. About 60% of patients with PMF harbor a somatic mutation of the JAK2 gene (JAK2-V617F) in their hematopoietic lineage. Recently, a splicing isoform of JAK2, lacking exon 14 (JAK2Δ14) was described in patients affected by myeloproliferative diseases.

May the remodeling of the Ca²⁺ toolkit in endothelial progenitor cells derived from cancer patients suggest alternative targets for anti-angiogenic treatment?

Endothelial progenitor cells (EPCs) may be recruited from bone marrow to sustain the metastatic switch in a number of solid cancers, including breast cancer (BC) and renal cellular carcinoma (RCC). Preventing EPC mobilization causes tumor shrinkage. Novel anti-angiogenic treatments have been introduced in therapy to inhibit VEGFR-2 signaling; unfortunately, these drugs blocked tumor angiogenesis in pre-clinical murine models, but resulted far less effective in human patients.

Hydrogen sulphide triggers VEGF-induced intracellular Ca²⁺ signals in human endothelial cells but not in their immature progenitors.

Hydrogen sulphide (H2S) is a newly discovered gasotransmitter that regulates multiple steps in VEGF-induced angiogenesis. An increase in intracellular Ca(2+) concentration ([Ca(2+)]i) is central to endothelial proliferation and may be triggered by both VEGF and H2S. Albeit VEGFR-2 might serve as H2S receptor, the mechanistic relationship between VEGF- and H2S-induced Ca(2+) signals in endothelial cells is unclear.

A functional transient receptor potential vanilloid 4 (TRPV4) channel is expressed in human endothelial progenitor cells.

Endothelial progenitor cells (EPCs) are mobilized into circulation to replace damaged endothelial cells and recapitulate the vascular network of injured tissues. Intracellular Ca(2+) signals are key to EPC activation, but it is yet to be elucidated whether they are endowed with the same blend of Ca(2+) -permeable channels expressed by mature endothelial cells. For instance, endothelial colony forming cells (ECFCs), the only EPC subset truly committed to acquire a mature endothelial phenotype, lack canonical transient receptor potential channels 3, 5 and 6 (TRPC3, 5 and 6), which are widely distributed in vascular endothelium; on the other hand, they express a functional store-operated Ca(2+) entry (SOCE).

Enhanced expression of Stim, Orai, and TRPC transcripts and proteins in endothelial progenitor cells isolated from patients with primary myelofibrosis.

Background: An increase in the frequency of circulating endothelial colony forming cells (ECFCs), the only subset of endothelial progenitor cells (EPCs) truly belonging to the endothelial phenotype, occurs in patients affected by primary myelofibrosis (PMF). Herein, they might contribute to the enhanced neovascularisation of fibrotic bone marrow and spleen. Store-operated Ca2+ entry (SOCE) activated by the depletion of the inositol-1,4,5-trisphosphate (InsP3)-sensitive Ca2+ store drives proliferation in ECFCs isolated from both healthy donors (N-ECFCs) and subjects suffering from renal cellular carcinoma (RCC-ECFCs).

Orai1 and transient receptor potential channels as novel molecular targets to impair tumor neovascularization in renal cell carcinoma and other malignancies.

The term "angiogenic switch" describes one of the earlier events of tumorigenesis, that occurs when the balance between pro-and anti-angiogenic factors shifts towards a pro-angiogenic outcome. This leads to the transition from a microscopic indolent lesion to a macroscopic and vascularised primary tumor, that may eventually metastasize and spread to distant sites. The molecular mechanisms underlying such a critical step in the carcinogenetic process have been extensively investigated.

JAK2 V617F genotype is a strong determinant of blast transformation in primary myelofibrosis.

Purpose: The influence of JAK2 V617F mutation on blast transformation (BT) and overall survival (OS) in primary myelofibrosis (PMF) is controversial. In a large cohort of patients we applied competing risks analysis for studying the influence of JAK2V617F mutation on BT in PMF.

Patients And Methods: In 462 PMF-fibrotic type patients (bone marrow [BM] fibrosis grade >0) we computed the incidence of BT and death in the framework of Cox regression analysis and of Fine and Gray competing risks analysis for BT.