Increased Plasma GDF15 Is Associated with Altered Levels of Soluble VEGF Receptors 1 and 2 in Symptomatic Multiple Myeloma

<b><i>Introduction:</i></b> In multiple myeloma, there is an increase in bone marrow microvascular density and enhanced renal lymphangiogenesis. Increased levels of the proangiogenic protein growth differentiation factor-15 (GDF15) have previously been reported to be associated with poor prognosis in myeloma. A possible association between GDF15 and the soluble forms of vascular endothelial growth factor receptors (sVEGFR) 1 and 2 has not yet been investigated, and a role for these receptors in pathological angiogenesis in myeloma is still to be defined. <b><i>Methods:</i></b> Plasma levels of GDF15 and sVEGFR1 and 2 were determined by ELISA in patients with smouldering multiple myeloma (sMM), patients with symptomatic multiple myeloma (abbreviated as MM), and healthy controls. The levels were compared between the three groups, and correlation coefficients were calculated, as were Kaplan-Meier curves for GDF15 and sVEGFR1 and sVEGFR2. <b><i>Results:</i></b> Levels of GDF15 were significantly higher in MM than in both patients with sMM and controls. A gradual decrease in mean sVEGFR1 concentration was observed, with MM &#x3e; sMM &#x3e; controls. Mean sVEGFR2 was lower in patients with MM than in controls. There was a positive correlation between GDF15 and sVEGFR1, and GDF15 correlated negatively with sVEGFR2. High GDF15 (&#x3e;3 ng/mL) was associated with poor prognosis. <b><i>Conclusion:</i></b> In multiple myeloma, increased expression of GDF15 correlates positively with sVEGFR1 and negatively with sVEGFR2. It is possible that the altered levels of sVEGFR1 and 2 contribute to the increased angio- and lymphangiogenesis observed in myeloma.

Nephrotoxicity induced by vascular endothelial growth factor inhibitors

Vascular endothelial growth factor (VEGF) is a special mitogen for vascular endothelial cells, an essential endogenous angiogenic cytokine, and the principal controller of vascular growth that plays a fundamental role in therapeutic angiogenesis pathways. VEGF-targeted therapy is categorized into the group of angiogenesis inhibitors that inhibit the expression or the activity of VEGF. It comprises counteracting VEGF antibodies, VEGF receptors, VEGF-trap, and tyrosine kinase inhibitor (TKIs) with selectivity for VEGF receptors. The kidney is both a target and a source of VEGF. VEGF may be a vital mediator to restore some types of renal diseases (e.g., non-diabetic renal diseases) and harmful in some other diseases (e.g., diabetes and diabetes complications). Due to their ability to prevent angiogenesis, VEGF inhibitors have been found as a powerful tool to treat angiogenesis-dependent diseases, including cancer and diabetic retinopathy. VEGF preserves the renal structure and function in normal physiologic conditions. Therefore, all treatments that inhibit the VEGF pathway may lead to renal disorders, especially renovascular diseases such as hypertension, proteinuria, nephrotic syndrome, decreased glomerular filtration rate (GFR), and thrombotic microangiopathy (TMA). In the present study, we reviewed some related reports and associated mechanisms, especially for hypertension and proteinuria.

VEGF-R2/Caveolin-1 Pathway of Undifferentiated ARPE-19 Retina Cells: A Potential Target as Anti-VEGF-A Therapy in Wet AMD by Resvega, an Omega-3/Polyphenol Combination

Age-related macular degeneration (AMD) is one of the main causes of deterioration in vision in adults aged 55 and older. In spite of therapies, the progression of the disease is often observed without reverse vision quality. In the present study, we explored whether, in undifferentiated ARPE-19 retinal cells, a disruption of the VEGF receptors (VEGF-R)/caveolin-1 (Cav-1)/protein kinases pathway could be a target for counteracting VEGF secretion. We highlight that Resvega®, a combination of omega-3 fatty acids with an antioxidant, resveratrol, inhibits VEGF-A secretion in vitro by disrupting the dissociation of the VEGF-R2/Cav-1 complex into rafts and subsequently preventing MAPK activation. Moreover, DNA ChIP analysis reveals that this combination prevents the interaction between AP-1 and vegf-a and vegf-r2 gene promoters. By these pathways, Resvega could present a potential interest as nutritional complementation against AMD.

VEGFR2 expressions in Th1 and CD8+ cytotoxic T lymphocytes (CTL) in colon cancer patients.

e15535 Background: VEGF receptors have an important role for inhibiting adaptive immun response in colon cancer. Therefore, we analyzed VEGF receptors in circulating T cell subsets according to stage in colon cancer patients. Methods: The prospective study group consisted of 50 patients with histologically confirmed colon cancer and 30 person without any cancer history as a control group. Peripheral blood specimens were collected from the patients after the diagnosis before inducing chemotherapy and radiotherapy. Patients with active infections or autoimmune disorders, who were treated with steroids and antibiotics in the last four weeks before the study enrollment were excluded from the study group. VEGFR2 expressions in circulating T cell subsets (Th1, Th2, Th17, CTL) were analyzed by flow cyctometry. Results: Age and gender were not different between the all study groups. Mean circulating CD4+ folicullar cells were less in colon cancer patients (9.54%±3.99) than the control group (12.03%±4.34), (p < 0.01). Mean circulating CD8+ follicular cells were higher in metastatic colon cancer (n = 26) 2.48% ± 1.68, than the non-metastatic colon cancer patients (n = 24) 1.63% ± 1.37, (p = 0.02). Mean VEGFR2 expressions in Th1 cells were higher in colon cancer patients 248.8 (Mean Flourescein intensity-MFI) than the control group 224.6, (P = 0.006). Mean VEGFR2 expressions in CTL were higher in colon cancer patients (381.8) than the control group (284.7), (p < 0.001). PD-1 expressions were not different between the colon cancer patients and the control group in all circulating T cell subsets. Mean VEGFR2 expressions in Th17 cells were higher non-metastatic colon cancer patients than the metastatic colon cancer patients (326.5 and 268.4 MFI, respectively, p = 0.02). Conclusions: VEGFR2 expressions are increased in circulating Th1 and CTL subsets in colon cancer patients. Whereas PD-1 expressions were not different in circulating T cell subsets than the control. VEGFRs may play an important role for the inhibition of circulating T cell subsets in colon cancer.

Levels of growth factors in the lungs affected by cancer with preventive effect of 1,3-diethylbenzimidazolium triiodide in the experiment

Purpose of the study. Analyzing the dynamics of VEGF-А, TGF-β and their receptors in the lung tissues in rats with antitumor effect of 1,3-diethylbenzimidazolium triiodide (Stellanin).Material and methods. The study included white outbred rats weighing 180–220 g. The main group included males (n=27) and females (n=27) with sarcoma 45 (s45) inoculated into the subclavian vein but not developed in the lungs (2×106 cells in 0.5 ml of saline) due to the subsequent intragastric administration of Stellanin (0.4 mg/kg once a day) according to an intermittent scheme: administration for 5 days and a break for 2 days. The control group included males (n=14) and females (n=14) without treatment with growing s45 in the lungs. Intact groups included 5 males and 5 females. After 4, 5 and 8 weeks of the experiment animals were decapitated, and levels of VEGF-A, sVEGF-R1, sVEGF-R2, TGF-β and sTGFβR2 were measured in 10% lung homogenates by ELISA (CUSABIO BIOTECH Co., Ltd., China).Results. Lung tissues of intact females showed 1.4 times (p<0.05) lower VEGF-А and 3.3 times higher sVEGF-R1, compared to males. The development of tumors in all control rats was accompanied by the VEGF-А increase (by 1.6–3.0 times) and the TGF-β reduction (by 3 times). The dynamics of both VEGF receptors differed in males and females. The levels of sVEGF-R1 in males increased by 1.5 times (p<0.05), while in females it decreased by 1.8 times (p<0.05), and as a result, the levels became similar in all animals. The levels of sVEGF-R2 in males decreased by 2 times, and in females it increased by 1.4 times (p<0.05), so the sVEGF-R2 content in females became 2.4 times higher than in males. In two-thirds of rats, Stellanin prevented s45 development in the lungs due to inhibition of VEGF-A growth by more than 2.0 times and an increase in concentrations of sVEGF-R1 by 10.0 times and TGF-β by 6.0 times, together with normalization of sVEGF-R2 and sTGFβR2.Conclusions. Stellanin prevents the development of malignant process in the lungs by inhibiting neoangiogenesis (deficiency of VEGF-A and excess of sVEGF-R1) and suppressing the proliferation of malignant cells (TGF-β growth).

Tivozanib, a highly potent and selective inhibitor of VEGF receptor tyrosine kinases, for the treatment of metastatic renal cell carcinoma

The VHL mutation– HIF upregulation– VEGF transcription sequence is the principal pathway in the development of renal cell carcinoma. Tyrosine kinase inhibitors target the VEGF receptors to inhibit further growth of renal cell carcinoma tumors. Tivozanib, originally named AV-951 and KRN-951, is a novel, orally bioavailable VEGF tyrosine kinase inhibitor that is selective for VEGF receptors 1, 2 and 3. Further, only picomolar concentrations of tivozanib are required to target these VEGF receptors and prevent phosphorylation; this potency prevents the debilitating side effects that occur with treatments whose mechanisms of action involve broad-spectrum tyrosine kinase inhibition. This review summarizes the growing body of evidence supporting tivozanib's efficacy and safety in the treatment of advanced renal cell carcinoma.

Abstract 455: The Roles of VEGF Receptors in Human Cardiac Progenitor Cell Contribution to New Vascular Formation

Background: Human cardiac progenitor cells (CPCs) have been shown to play a valuable role in myocardial tissue maintenance, including their ability to develop into endothelial and vascular smooth muscle cells. The vascular endothelial growth factor (VEGF) ligand family has been identified as essential for angiogenesis. VEGF receptors (VEGFRs) comprise three main subtypes, VEGFRs1,2,3; our prior data identified CPC expression of both VEGFRs and of pro-angiogenic secreted growth factors. Hypothesis: Human CPCs utilise VEGFR signalling to potentiate CPC-driven angiogenesis, directly via CPC differentiation and indirectly via secrotome. Methods: Human adult myocardial tissue samples were collected during cardiac surgery and c-Kit-positive (c-Kit + ), CD45-negative (CD45 - ) CPCs isolated by immunomagnetic bead sorting, with five CPC lines generated from individual-donor samples. The c-Kit + / CD45 - CPC population was then characterised by clonogenicity assay, immunocytochemistry (ICC), and real-time RT-qPCR. Human CPC lines were FACS sorted into 3 lineage groups: endothelial (CD31 + ), smooth muscle (CD91 + /CD140b + /CD31 - ) and uncommitted (CD91 - /CD140b - /CD31 - ). Expression of VEGFRs and markers (SDF1; TGF-β) in CPC sub-populations was assessed by: qPCR; Western blot; ICC. Impact on signal transduction by VEGF-A stimulation was identified by Western blot and ICC. Results: Human CPCs were sorted into populations of: endothelial linage CD31 + (1.26% of total cells), smooth muscle lineage CD91 + /CD140b + /CD31 - (13.77%) and CD91 - /CD140b - /CD31 - (31.28%) cells. Analysis of gene expression identified VEGFRs 1, 2 and 3 in all three sub-populations, but only VEGFR1 expression was confirmed at protein level, seen in all three sub-populations. High expression levels of growth factors secreted by CPCs (SDF, TGF-β, VEGFs, FGF-2) were identified in human CPCs, also in all three sub-populations. Conclusion: Human CPC lines were isolated and analysed in bulk and sub-populations, identifying VEGFR1 expression at both gene and protein levels, but not VEGFR2 and VEGFR3. Our further work will identify signalling pathways in human CPCs linked to VEGF-A stimulation, along with the impact of VEFG-A stimulation on CPC secretome and linked angiogenic potential.