Endothelial Aldehyde Dehydrogenase 2 as a Target to Maintain Vascular Wellness and Function in Ageing

Endothelial cells are the main determinants of vascular function, since their dysfunction in response to a series of cardiovascular risk factors is responsible for disease progression and further consequences. Endothelial dysfunction, if not resolved, further aggravates the oxidative status and vessel wall inflammation, thus igniting a vicious cycle. We have furthermore to consider the physiological manifestation of vascular dysfunction and chronic low-grade inflammation during ageing, also known as inflammageing. Based on these considerations, knowledge of the molecular mechanism(s) responsible for endothelial loss-of-function can be pivotal to identify novel targets of intervention with the aim of maintaining endothelial wellness and vessel trophism and function. In this review we have examined the role of the detoxifying enzyme aldehyde dehydrogenase 2 (ALDH2) in the maintenance of endothelial function. Its impairment indeed is associated with oxidative stress and ageing, and in the development of atherosclerosis and neurodegenerative diseases. Strategies to improve its expression and activity may be beneficial in these largely diffused disorders

Targeting endothelial cell metabolism for cardio-protection from the toxicity of antitumor agents

The vascular endothelium plays a fundamental role in the maintenance of tissue homeostasis, regulating local blood flow and other physiological processes. Chemotherapeutic drugs and target therapies, including antiangiogenic drugs targeting vascular endothelial growth factor (VEGF) or its receptors, not only efficiently act against tumor growth, but may also induce endothelial dysfunction and cardiovascular toxicity. Continued research efforts aim to better understand, prevent and mitigate these chemotherapy associated cardiovascular diseases. Conventional chemotherapeutic agents, such as anthracyclines, platinum compounds, and taxanes, and newer targeted agents, such as bevacizumab, trastuzumab, and tyrosine kinase inhibitors, have known risk of cardiovascular toxicity, which can limit their effectiveness by promoting increased morbidity and/or mortality. This review describes a) the activity of anticancer agents in inducing endothelial dysfunction, b) the metabolic pathways and signalling cascades which may be targeted by protective agents able to maintain or restore endothelial cell function, such as endothelial nitric oxide synthase/fibroblast growth factor-2 (eNOS-FGF-2) pathway, and c) the drugs/strategies reported to improve endothelial function and to reduce the risks of cardiovascular diseases such as angiotensin converting enzyme inhibitors (ACEi) and beta blockers, that are fundamental therapies in chronic heart failure (HF), as well as non-standard HF treatments such ad nitric oxide donors and antioxidant strategies. There is increasing interest in whether ACEi, beta-blockers, and/or statins might prevent and/or therapeutically control cardiotoxic effects in cancer patients. Maintaining endothelial function during or following treatments with chemotherapeutic agents, without affecting anti-tumor drug-effectiveness, is essential for preserving or recovering cardiovascular homeostasis. In this respect, the early detection and immediate therapy of cardiovascular toxicityappear crucial for substantial recovery of cardiac function in cancer patients

Involvement of bradykinin B2 receptor in pathological vascularization in oxygen-induced retinopathy in mice and rabbit cornea

The identification of components of the kallikrein-kinin system in the vitreous from patients with microvascular retinal diseases suggests that bradykinin (BK) signaling may contribute to pathogenesis of retinal vascular complications. BK receptor 2 (B2R) signaling has been implicated in both pro-inflammatory and pro-angiogenic effects promoted by BK. Here, we investigated the role of BK/B2R signaling in the retinal neovascularization in the oxygen-induced retinopathy (OIR) model. Blockade of B2R signaling by the antagonist fasitibant delayed retinal vascularization in mouse pups, indicating that the retinal endothelium is a target of the BK/B2R system. In the rabbit cornea assay, a model of pathological neoangiogenesis, the B2 agonist kallidin induced vessel sprouting and promoted cornea opacity, a sign of edema and tissue inflammation. In agreement with these results, in the OIR model, a blockade of B2R signaling significantly reduced retinal neovascularization, as determined by the area of retinal tufts, and, in the retinal vessel, it also reduced vascular endothelial growth factor and fibroblast growth factor-2 expression. All together, these findings show that B2R blockade reduces retinal neovascularization and inhibits the expression of proangiogenic and pro-inflammatory cytokines, suggesting that targeting B2R signaling may be an effective strategy for treating ischemic retinopathy

Inhibition of cell cycle progression by the hydroxytyrosol-cetuximab combination yields enhanced chemotherapeutic efficacy in colon cancer cells

Hydroxytyrosol (HT), a polyphenol of olive oil, downregulates epidermal growth factor (EGFR) expression and inhibits cell proliferation in colon cancer (CC) cells, with mechanisms similar to that activated by the EGFR inhibitor, cetuximab. Here, we studied whether HT treatment would enhance the cetuximab inhibitory effects on cell growth in CC cells. HT-cetuximab combination showed greater efficacy in reducing cell growth in HT- 29 and WiDr cells at concentrations 10 times lower than when used as single agents. This reduction was clearly linked to cell cycle blockade, occurring at G2/M phase. The cell cycle arrest in response to combination treatment is related to cyclins B, D1, and E, and cyclin-dependent kinase (CDK) 2, CDK4, and CDK6 down-regulation, and to the concomitant over-expression of CDK inhibitors p21 and p27. HT and cetuximab stimulated a caspase-independent cell death cascade, promotedtranslocation of apoptosis-inducing factor (AIF) from mitochondria to nucleus and activated the autophagy process. Notably, normal colon cells and keratinocytes were less susceptible to comboinduced cell death and EGFR downregulation. These results suggest a potential role of diet, containing olive oil, during cetuximab chemotherapy of colon tumor. HT may be a competent therapeutic agent in CC enhancing the effects of EGFR inhibitors

Prostaglandin E2 Regulates Angiogenesis via Activation of Fibroblast Growth Factor Receptor-1

Prostaglandin E(2) (PGE(2)) behaves as a mitogen in epithelial tumor cells as well as in many other cell types. We investigated the actions of PGE(2) on microvascular endothelial cells (capillary venular endothelial cells) with the purpose of delineating the signaling pathway leading to the acquisition of the angiogenic phenotype and to new vessel formation. PGE(2) (100 nM) produced activation of the fibroblast growth factor receptor 1 (FGFR-1), as measured by its phosphorylation, but not of vascular endothelial growth factor receptor 2. PGE(2) stimulated the EP3 subtype receptor, as deduced by abrogation of EP3 Galpha(i) subunit activity through pertussis toxin. Consistent with this result, in human umbilical venular endothelial cells missing the EP3 receptor, PGE(2) did not phosphorylate FGFR-1. Upon binding to its receptor, PGE(2) initiated an autocrine/paracrine signaling cascade involving the intracellular activation of c-Src, activation of matrix metalloproteinase (predominantly MMP2), which in turn caused the mobilization of membrane-anchored fibroblast growth factor-2 (FGF-2). In fact, in cells unable to release FGF-2 the transfection with both FGFR-1 and EP3 did not result in FGFR-1 phosphorylation in response to PGE(2). Relevance for the FGF2-FGFR-1 system was highlighted by confocal analysis, showing receptor internalization after cell exposure to the prostanoid. ERK1/2 appeared to be the distal signal involved, its phosphorylation being sensitive to either cSrc inhibitor or FGFR-1 blocker. Finally, PGE(2) stimulated cell migration and capillary formation in aortic rings, which were severely reduced by inhibitors of signaling molecules or by receptor antagonist. In conclusion, this study provides evidence for the involvement of FGFR-1 through FGF2 in eliciting PGE(2) angiogenic responses. This signaling pattern is similar to the autocrine-paracrine mechanism which operates in endothelial cells to support neovascular growth

Safety of Anti-Angiogenic Drugs in Pediatric Patients with Solid Tumors: A Systematic Review and Meta-Analysis

Cancer is a clinical condition that can benefit from anti-angiogenic drugs (AADs). Given the low prevalence and the heterogeneity of childhood cancers, information about the safety of these drugs in pediatric patients is partially assessed. The aim of this study was to evaluate the safety of AADs in pediatric patients with solid tumors. Clinical trials and observational studies were searched in PubMed, ISI Web of Science, and ClinicalTrials database For each included study, adverse events (AEs) were extracted. A meta-analysis was conducted by pooling proportions of AEs using a random intercept logistic regression model. Seventy studies were retrieved. Most part were clinical trials (55 out of 70), and only fifteen observational studies were found. Overall, proportion of serious and non-serious AEs of AADs used as monotherapy was 46% and 89%, respectively. Proportions of serious AEs varied among drugs: sunitinib, 79%; lenvatinib, 64%; sorafenib, 48%; ramucirumab, 41%; pazopanib, 30%; and vandetanib, 27%. A higher proportion of non-serious hematological AEs was found in the patients receiving pazopanib with respect to sunitinib and lenvatinib. The safety profile of AADs has been extensively investigated for mostly drugs in phase I and II trials and is limited to acute toxicities. Overall, one out of two patients using AAD drugs in monotherapy experienced a serious AE despite proportions varied per single drugs. When AADs were combined with standard chemotherapy, the proportion of AEs varied in relation to the single combinations

Divergent effects of quercetin conjugates on angiogenesis

The present study reports the activities of quercetin and its main circulating conjugates in man (quercetin-3′-sulphate (Q3′S) and quercetin-3-glucuronide (Q3G)) on in vivo angiogenesis induced by vascular endothelial growth factor (VEGF) and examines the effects of these molecules on cultured endothelial cells. We found opposing effects of quercetin and its metabolites on angiogenesis. While quercetin and Q3G inhibited VEGF-induced endothelial cell functions and angiogenesis, Q3′S per se promoted endothelial cell proliferation and angiogenesis. The inhibitory effect elicited by Q3G was linked to inhibition of extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation elicited by VEGF. The activation of endothelial cells by Q3′S was associated to stimulation of VEGF receptor-2 and to downstream signalling activation (phosphatidylinositol-3 kinase/Akt and nitric oxide synthase pathways), ultimately responsible for ERK1/2 phosphorylation. These data indicate that the effects of circulating quercetin conjugates on angiogenesis are different depending on the nature of the conjugate. Q3G andQ3′S are the two major conjugates in plasma, but their ratio is dependenton several factors, so thatinhibition or activation of angiogenesis could be subtly shifted as a result of metabolismin viv

PGE2 mediates EGFR internalization and nuclear translocation via caveolin endocytosis promoting its transcriptional activity and proliferation in human NSCLC cells

Prostaglandin E2 (PGE2) contributes to tumor progression by promoting cancer cell growth, invasion and by creating a favorable pro-tumor microenvironment. PGE2 has been reported to transactivate and internalize into the nucleus receptor tyrosine kinases such as Epidermal growth factor receptor (EGFR), thereby supporting tumor progression. Here we demonstrate that in non-small cell lung carcinoma (NSCLC) cells, PGE2 induces EGFR nuclear translocation via different dynamin-dependent endocytic pathways, promotes the formation of an EGFR-STAT3 complex, affects nuclear EGFR target gene expression and mediates tumor cell proliferation. Indeed, we find that PGE2 induces EGFR internalization and consequent nuclear import through Clathrin- and Caveolin-mediated endocytosis and through the interaction of EGFR with Importin β1. Within the nucleus, EGFR forms a complex with STAT3, an event blocked by ablation of Clathrin Heavy Chain or Caveolin-1. The combination of EGF and PGE2 prolongs nuclear EGFR transcriptional activity manifested by the upregulation of CCND1, PTGS2, MYC and NOS2 mRNA levels and potentiates nuclear EGFR-induced NSCLC cell proliferation. Additionally, NSCLC patients with high expression of a nuclear EGFR gene signature display shorter survival times than those with low expression, thus showing a putative correlation between nuclear EGFR and poor prognosis in NSCLC. Together, our findings indicate a complex mechanism underlying PGE2-induced EGF/EGFR signaling and transcriptional control, which plays a key role in cancer progression