Jun N-terminal kinase inhibitor blocks angiogenesis by blocking VEGF secretion and an MMP pathway

Dose dependent effects of cadmium on tumor angiogenesis

Angiogenesis is crucial for tumor growth and metastasis. Cadmium (Cd) exposure is associated with elevated cancer risk and mortality. Such association is, at least in part, attributable to Cd-induced tumor angiogenesis. Nevertheless, the reported effects of Cd on tumor angiogenesis appear to be either stimulatory or inhibitory, depending on the concentrations. Ultra-low concentrations of Cd (<0.5 μM) inhibit endothelial nitric oxide synthase activation, leading to reduced endothelial nitric oxide production and attenuated tumor angiogenesis. In contrast, low-lose Cd (1-10 μM) up-regulates vascular endothelial growth factor (VEGF)-mediated tumor angiogenesis by exerting sub-apoptotic levels of oxidative stress on both tumor cells and endothelial cells (ECs). The consequent activation of protein kinase B/Akt, nuclear factor-κB, and mitogen-activated protein kinase signaling cascades mediate the increased secretion of VEGF by tumor cells and the up-regulated VEGF receptor-2 expression in ECs. Furthermore, Cd in high concentrations (>10 μM) induces EC apoptosis via the activation of caspase-3, resulting in destruction of tumor vasculature. In this review, we summarize the current knowledge concerning the roles of Cd in tumor angiogenesis, with a focus on molecular mechanisms underlying the dose dependent effects of Cd on various EC phenotypes.

Anti-angiogenic properties of artemisinin derivatives (Review)

Angiogenesis, the process involving the development of new blood vessels from existing capillaries, is critical for growth and wound healing. However, pathological angiogenesis contributes to the pathogeneses of numerous diseases, including cancer, rheumatoid arthritis, diabetic retinopathy and macular degeneration. Hence, the inhibition of angiogenesis is an effective therapeutic approach for these diseases. Apart from its anti-malarial properties, artemisinin and its derivatives also exhibit potent anti-angiogenic properties. The molecular mechanisms underlying their inhibitory effects on angiogenesis have been studied by several groups. These investigations have revealed that artemisinins inhibit angiogenesis via the perturbations of cellular signaling pathways involved in the regulation of angiogenesis. Along with a brief introduction to artemisinin derivatives, this review provides a detailed summary of the effects of artemisinins on the mitogen-activated protein kinase (MAPK) pathway, the nuclear factor-κB (NF-κB) pathway and the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway. Due to the multiplicity of their actions on relevant signaling pathways, artemisinins are promising candidates with potential for use as anti-angiogenic agents for the treatment of related diseases or disorders.

Galloyl benzamide-based compounds modulating tumour necrosis factor α-stimulated c-Jun N-terminal kinase and p38 mitogen-activated protein kinase signalling pathways

OBJECTIVES

The aim of this work is to investigate whether and how two newly synthesized 3,4,5-trimethoxygalloyl-containing compounds 1 and 3 interfere with the mitogen-activated protein kinase (MAPK) signalling pathways involved in several pathological events, ranging from inflammatory diseases to cancer.

METHODS

The effects on the phosphorylation of MAP kinases (c-Jun N-terminal kinases (JNKs), p38) and activation of nuclear factor-kappa B (NF-κB) pathways of 1 and its 1H-indazole-containing analogue 3, compared with those elicited by the known Adenosine Triphosphate (ATP)-competitive JNK inhibitor SP600125, were evaluated through Western blot analysis in murine fibroblasts NIH-3T3 and human endothelial cells EA.hy926 acutely treated with tumour necrosis factor-α (TNF-α). Their effects on cell viability were also assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay.

KEY FINDINGS

In cultured murine fibroblasts, 1 inhibited JNK signalling with a different mechanism from SP600125. It reduced c-Jun phosphorylation without altering phosphorylation levels of JNK protein. Compound 3, showing a profile similar to SP600125, inhibited JNK phosphorylation and partially inhibited p38 MAPK at 50 μm concentration. Compound 3 and SP600125 showed similar behaviour in both cell cultures. In contrast, compound 1 in EA.hy926 cells significantly interfered with JNK phosphorylation, did not decrease phosphorylation of c-Jun (Ser73), whereas significantly suppressed phosphorylation of p38 MAPK and reversed degradation of NF-κB signalling components.

CONCLUSIONS

3,4,5-Trimethoxygalloyl-based compounds 1 and 3, which did not show significant cell toxicity, modulate the TNF-α-induced activation of MAPK signalling, mainly inhibiting phosphorylation of JNK, c-Jun and p38 MAPK, in murine fibroblasts and human endothelial cells with different MAPK selectivity profiles. These compounds deserve future investigation in specific cell-based disease models and in-vivo pharmacology.

VEGF in the crosstalk between human adipocytes and smooth muscle cells: depot-specific release from visceral and perivascular adipose tissue

Adipose tissue secrets adipokines and fatty acids, which may contribute to obesity-associated vascular dysfunction and cardiovascular risk. This study investigated which factors are responsible for the synergistic effect of adipokine and oleic acid- (OA-) induced proliferation of human vascular smooth muscle cells (VSMC). Adipocyte-conditioned medium (CM) from human adipocytes induces proliferation of VSMC in correlation to its vascular endothelial growth factor (VEGF) content. CM increases VEGF-receptor (VEGF-R) 1 and 2 expression and VEGF secretion of VSMC, while OA only stimulates VEGF secretion. VEGF neutralization abrogates CM- and OA-induced proliferation and considerably reduces proliferation induced by CM and OA in combination. VEGF release is higher from visceral adipose tissue (VAT) of obese subjects compared to subcutaneous adipose tissue (SAT) and VAT from lean controls. Furthermore, VEGF release from VAT correlates with its proliferative effect. Perivascular adipose tissue (PAT) from type 2 diabetic patients releases significantly higher amounts of VEGF and induces stronger proliferation of VSMC as compared to SAT and SAT/PAT of nondiabetics. In conclusion, VEGF is mediating CM-induced proliferation of VSMC. As this adipokine is released in high amounts from VAT of obese patients and PAT of diabetic patients, VEGF might link adipose tissue inflammation to increased VSMC proliferation.

Critical role of c-Jun N-terminal kinase in regulating bFGF-induced angiogenesis in vitro

Angiogenesis, the process of new blood vessels formation, is a critical step for wound healing, tumour growth and metastasis, diabetic retinopathy, psoriasis, etc. The present study was designed to investigate whether c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) is critical for regulating basic fibroblastic growth factor (bFGF)-induced angiogenesis in human umbilical vein endothelial cells (HUVECs). Our results showed that bFGF-induced HUVECs proliferation, migration and tube formation with a concentration-dependent manner. Further results showed that bFGF induced the phosphorylation of JNK/SAPK at 15 min. Both JNK/SAPK inhibitor SP600125 and JNK/SAPK peptide inhibitor 420116 could inhibit bFGF-induced HUVECs proliferation, migration and tube formation, so did JNK/SAPK-specific siRNA. Moreover, when HUVECs were stimulated with bFGF, upstream signals of JNK/SAPK, SEK1/MKK4 and MKK7 were both activated at 2 min. In summary, our results indicate that JNK/SAPK signal pathway plays an important role in regulating bFGF-mediated angiogenesis in HUVECs, which may therefore be a new therapeutic approach for the treatment of angiogenesis-associated diseases.

Brain angiogenesis in developmental and pathological processes: neurovascular injury and angiogenic recovery after stroke

Pathophysiologic responses in brain after stroke are highly complex. Thus far, a singular focus on saving neurons alone has not revealed any clinically effective neuroprotectants. To address this limitation, the concept of a neurovascular unit was developed. Within this conceptual framework, brain function and dysfunction are manifested at the level of cell-cell signaling between neuronal, glial and vascular elements. For stroke, coordinated responses at the neurovascular interface will mediate acute as well as chronic events in ischemic and hemorrhagic brain tissue. In this minireview, we briefly survey two representative examples of neurovascular responses in stroke. During the early acute phase of neurovascular injury, blood-brain barrier perturbations should predominate with key roles for various matrix proteases. During the delayed phase, brain angiogenesis may provide the critical neurovascular substrates for neuronal remodeling. In this minireview, we propose the hypothesis that the biphasic nature of neurovascular responses represents an endogenous attempt by damaged parenchyma to trigger brain angiogenesis and repair. This phenomenon may allow acute deleterious signals to transition into beneficial effects during stroke recovery. Understanding how neurovascular signals and substrates make the transition from initial injury to angiogenic recovery will be important if we are to find new therapeutic approaches for stroke.

Impact of pancreatic cold preservation on rat islet recovery and function

BACKGROUND

Islet transplantation success depends on the number and quality of islets transplanted. This study aimed at exploring the molecular mechanisms associated with cold pancreas preservation and their impact on islet cell survival and function.

METHODS

Rat pancreata were stored in cold University of Wisconsin preservation solution for short (3 hr; control) or long (18 hr) cold ischemia times (CIT).

RESULTS

Pancreata exposed to long CIT yielded lower islet numbers and showed reduced cellular viability; isolated islets displayed higher levels of phosphorylated stress-activated protein kinase (c-jun N-terminal Kinase and Mitogen-Activated Protein Kinase-p38), and chemokine (C-C) ligand-3, and lower levels of vascular endothelial growth factor, interleukins (IL)-9 and IL-10. Islets obtained from long-CIT pancreata were functionally impaired after transplantation. Differential proteomic expression in pancreatic tissue after CIT included increased eukaryotic translation elongation factor-1-alpha-1 (apoptosis related) and reduced Clade-B (serine protease inhibitor).

CONCLUSIONS

Our study indicates that cold ischemia stimulates inflammatory pathways (chemokine (c-c)ligand-3, phosphorylation of c-jun N-terminal Kinase and mitogen-activated protein kinase-p38, and eukaryotic translation elongation factor-1-alpha-1) and decreases repair/cytoprotective pathways (IL-10, vascular endothelial growth factor, and Clade-B), all of which may negatively affect the quality and mass of islets obtained from a donor pancreas.