Glutaredoxin regulates vascular development by reversible glutathionylation of sirtuin 1.

Embryonic development depends on complex and precisely orchestrated signaling pathways including specific reduction/oxidation cascades. Oxidoreductases of the thioredoxin family are key players conveying redox signals through reversible posttranslational modifications of protein thiols. The importance of this protein family during embryogenesis has recently been exemplified for glutaredoxin 2, a vertebrate-specific glutathione-disulfide oxidoreductase with a critical role for embryonic brain development. Here, we discovered an essential function of glutaredoxin 2 during vascular development. Confocal microscopy and time-lapse studies based on two-photon microscopy revealed that morpholino-based knockdown of glutaredoxin 2 in zebrafish, a model organism to study vertebrate embryogenesis, resulted in a delayed and disordered blood vessel network. We were able to show that formation of a functional vascular system requires glutaredoxin 2-dependent reversible S-glutathionylation of the NAD(+)-dependent protein deacetylase sirtuin 1. Using mass spectrometry, we identified a cysteine residue in the conserved catalytic region of sirtuin 1 as target for glutaredoxin 2-specific deglutathionylation. Thereby, glutaredoxin 2-mediated redox regulation controls enzymatic activity of sirtuin 1, a mechanism we found to be conserved between zebrafish and humans. These results link S-glutathionylation to vertebrate development and successful embryonic angiogenesis.

Adipocytes Promote Early Steps of Breast Cancer Cell Dissemination via Interleukin-8.

Fat is a major tissue component in human breast cancer (BC). Whether breast adipocytes (BAd) affect early stages of BC metastasis is yet unknown. BC progression is dependent on angiogenesis and inflammation, and interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF) are key regulators of these events. Here, we show that BAd increased the dissemination of estrogen receptor positive BC cells (BCC) in vivo in the zebrafish model of metastasis, while dissemination of the more aggressive and metastatic BCC such as estrogen receptor negative was unaffected. While anti-VEGF and anti-IL-8 exhibited equal inhibition of angiogenesis at the primary tumor site, anti-IL-8 reduced BCC dissemination whereas anti-VEGF had minor effects on this early metastatic event. Mechanistically, overexpression of cell-adhesion molecules in BCC and neutrophils via IL-8 increased the dissemination of BCC. Importantly, the extracellular in vivo levels of IL-8 were 40-fold higher than those of VEGF in human BC. Our results suggest that IL-8 is a clinical relevant and promising therapeutic target for human BC.

Estradiol Promotes Breast Cancer Cell Migration via Recruitment and Activation of Neutrophils.

Estradiol (E2) plays a key role in breast cancer progression. Most breast cancer recurrences express the estrogen receptor (ER), but nearly 50% of patients are resistant to antiestrogen therapy. Novel therapeutic targets of ER-positive breast cancers are needed. Protumoral neutrophils expressing the lymphocyte function-associated antigen 1 (LFA-1) integrin may mediate cancer metastasis, and TGFß1 is the major chemoattractant for neutrophils. The role of E2 in neutrophil-ER+ breast cancer cell interactions is unknown. We studied this in vivo using murine breast cancers in immunocompetent mice and human breast cancers in nude mice. Cell dissemination was evaluated in a zebrafish model, and microdialysis of breast cancer patients was performed. In vitro studies were done with mammosphere cultures of breast cancer cells and human neutrophils. We found that E2 increased the number of LFA-1+ neutrophils recruited to the invasive edge of mouse tumors, increased TGFß1 secretion and promoted neutrophil infiltration in mammospheres, and induced overexpression of LFA-1 in neutrophils. In zebrafish, in the presence of E2, neutrophils increased dissemination of ER+ breast cancer cells via LFA-1 and TGFß1, thus causing noninvasive cancer cells to be highly metastatic. Time-lapse imaging in zebrafish revealed close interactions of neutrophils with cancer cells, which drove breast cancer metastasis. We also found that extracellular TGFß1 was overproduced in human breast cancer tissue compared with adjacent normal breast tissue. Thus, E2 can regulate immune/cancer cell interactions in tumor microenvironments. Our results indicate that extracellular TGFß1 is a relevant target in human breast cancer. Cancer Immunol Res; 5(3); 234-47. ©2017 AACR.

AEG-1 knockdown in colon cancer cell lines inhibits radiation-enhanced migration and invasion in vitro and in a novel in vivo zebrafish model.

BACKGROUND: Radiotherapy is a well-established anti-cancer treatment. Although radiotherapy has been shown to significantly decrease the local relapse in rectal cancer patients, the rate of distant metastasis is still very high. The aim of this study was to evaluate whether AEG-1 is involved in radiation-enhanced migration and invasion in vitro and in a novel in vivo zebrafish model. RESULTS: Migration and invasion were decreased in all the AEG-1 knockdown cell lines. Furthermore, we observed that radiation enhanced migration and invasion, while AEG-1 knockdown abolished this effect. The results from the zebrafish embryo model confirmed the results obtained in vitro. MMP-9 secretion and expression were decreased in AEG-1 knockdown cells. MATERIALS AND METHODS: We evaluated the involvement of AEG-1 in migration and invasion and, radiation-enhanced migration and invasion by Boyden chamber assay in three colon cancer cell lines and respective stable AEG-1 knockdown cell lines. Furthermore, we injected those cells into zebrafish embryos and evaluated the amount of disseminated cells into the tail. CONCLUSION: AEG-1 knockdown inhibits migration and invasion, as well as radiation-enhanced invasion both in vitro and in vivo. We speculate that this is done via the downregulation of the intrinsic or radiation-enhanced MMP-9 expression by AEG-1 in the cancer cells. This study also shows, for the first time, that the zebrafish is a great model to study the early events in radiation-enhanced invasion.

A microarray whole-genome gene expression dataset in a rat model of inflammatory corneal angiogenesis.

In angiogenesis with concurrent inflammation, many pathways are activated, some linked to VEGF and others largely VEGF-independent. Pathways involving inflammatory mediators, chemokines, and micro-RNAs may play important roles in maintaining a pro-angiogenic environment or mediating angiogenic regression. Here, we describe a gene expression dataset to facilitate exploration of pro-angiogenic, pro-inflammatory, and remodelling/normalization-associated genes during both an active capillary sprouting phase, and in the restoration of an avascular phenotype. The dataset was generated by microarray analysis of the whole transcriptome in a rat model of suture-induced inflammatory corneal neovascularisation. Regions of active capillary sprout growth or regression in the cornea were harvested and total RNA extracted from four biological replicates per group. High quality RNA was obtained for gene expression analysis using microarrays. Fold change of selected genes was validated by qPCR, and protein expression was evaluated by immunohistochemistry. We provide a gene expression dataset that may be re-used to investigate corneal neovascularisation, and may also have implications in other contexts of inflammation-mediated angiogenesis.

PDGF-BB modulates hematopoiesis and tumor angiogenesis by inducing erythropoietin production in stromal cells.

The platelet-derived growth factor (PDGF) signaling system contributes to tumor angiogenesis and vascular remodeling. Here we show in mouse tumor models that PDGF-BB induces erythropoietin (EPO) mRNA and protein expression by targeting stromal and perivascular cells that express PDGF receptor-ß (PDGFR-ß). Tumor-derived PDGF-BB promoted tumor growth, angiogenesis and extramedullary hematopoiesis at least in part through modulation of EPO expression. Moreover, adenoviral delivery of PDGF-BB to tumor-free mice increased both EPO production and erythropoiesis, as well as protecting from irradiation-induced anemia. At the molecular level, we show that the PDGF-BB-PDGFR-bß signaling system activates the EPO promoter, acting in part through transcriptional regulation by the transcription factor Atf3, possibly through its association with two additional transcription factors, c-Jun and Sp1. Our findings suggest that PDGF-BB-induced EPO promotes tumor growth through two mechanisms: first, paracrine stimulation of tumor angiogenesis by direct induction of endothelial cell proliferation, migration, sprouting and tube formation, and second, endocrine stimulation of extramedullary hematopoiesis leading to increased oxygen perfusion and protection against tumor-associated anemia.

Hypoxia-induced retinal angiogenesis in zebrafish as a model to study retinopathy.

Mechanistic understanding and defining novel therapeutic targets of diabetic retinopathy and age-related macular degeneration (AMD) have been hampered by a lack of appropriate adult animal models. Here we describe a simple and highly reproducible adult fli-EGFP transgenic zebrafish model to study retinal angiogenesis. The retinal vasculature in the adult zebrafish is highly organized and hypoxia-induced neovascularization occurs in a predictable area of capillary plexuses. New retinal vessels and vascular sprouts can be accurately measured and quantified. Orally active anti-VEGF agents including sunitinib and ZM323881 effectively block hypoxia-induced retinal neovascularization. Intriguingly, blockage of the Notch signaling pathway by the inhibitor DAPT under hypoxia, results in a high density of arterial sprouting in all optical arteries. The Notch suppression-induced arterial sprouting is dependent on tissue hypoxia. However, in the presence of DAPT substantial endothelial tip cell formation was detected only in optic capillary plexuses under normoxia. These findings suggest that hypoxia shifts the vascular targets of Notch inhibitors. Our findings for the first time show a clinically relevant retinal angiogenesis model in adult zebrafish, which might serve as a platform for studying mechanisms of retinal angiogenesis, for defining novel therapeutic targets, and for screening of novel antiangiogenic drugs.