Gene expression profile of B 16(F10) murine melanoma cells exposed to hypoxic conditions in vitro

Molecular Imaging of Melanoma VEGF-expressing Tumors through [99mTc]Tc-HYNIC-Fab(Bevacizumab)

BACKGROUND

Angiogenesis is a process that many tumors depend on for growth, development, and metastasis. Vascular endothelial growth factor (VEGF) is one of the major players in tumor angiogenesis in several tumor types, including melanoma. VEGF inhibition is achieved by bevacizumab, a humanized monoclonal antibody that binds with high affinity to VEGF and prevents its function. In order to successfully enable in vivo VEGF expression imaging in a murine melanoma model, we previously labeled bevacizumab with [99mTc]Tc. We observed that this was feasible, but it had prolonged blood circulation and delayed tumor uptake.

OBJECTIVE

The aim of this study was to develop a radiolabeled Fab bevacizumab fragment, [99mTc]Tc-HYNICFab( bevacizumab), for non-invasive in vivo VEGF expression molecular imaging.

METHODS

Flow cytometry was used to examine VEGF presence in the murine melanoma cell line (B16-F10). Bevacizumab was digested with papain for six hours at 37°C to produce Fab(bevacizumab), which was then conjugated to NHS-HYNIC-Tfa for radiolabeling with [99mTc]Tc. Stability and binding affinity assays were also evaluated. Biodistribution and single photon emission computed tomography/computed tomography (SPECT/CT) were performed at 1, 3, and 6 h (n = 4) after injection of [99mTc]Tc-HYNIC-Fab(Bevacizumab) in normal and B16-F10 tumor-bearing C57Bl/6J mice.

RESULTS

Using flow cytometry, it was shown that the B16-F10 murine melanoma cell line has intracellular VEGF expression. Papain incubation resulted in the complete digestion of bevacizumab with good purity and homogeneity. The radiolabeling yield of [99mTc]Tc-HYNIC-Fab(bevacizumab) was 85.00 ± 6.06%, with a specific activity of 291.87 ± 18.84 MBq/mg (n=3), showing in vitro stability. Binding assays demonstrated significant intracellular in vitro VEGF expression. Fast blood clearance and high kidney and tumor uptake were observed in biodistribution and SPECT/CT studies.

CONCLUSIONS

We present the development and evaluation of [99mTc]Tc-HYNIC-Fab(bevacizumab), a novel molecular VEGF expression imaging agent that may be used for precision medicine in melanoma and potentially in other VEGF-expressing tumors.

Cerebrospinal fluid of progressive multiple sclerosis patients reduces differentiation and immune functions of oligodendrocyte progenitor cells

Oligodendrocyte progenitor cells (OPCs) are responsible for remyelination in the central nervous system (CNS) in health and disease. For patients with multiple sclerosis (MS), remyelination is not always successful, and the mechanisms differentiating successful from failed remyelination are not well-known. Growing evidence suggests an immune role for OPCs, in addition to their regenerative role; however, it is not clear if this helps or hinders the regenerative process. We studied the effect of cerebrospinal fluid (CSF) from relapsing MS (rMS) and progressive MS (pMS) patients on primary OPC differentiation and immune gene expression and function. We observed that CSF from either rMS or pMS patients has a differential effect on the ability of mice OPCs to differentiate into mature oligodendrocytes and to express immune functions. CSF of pMS patients impaired differentiation into mature oligodendrocytes. In addition, it led to decreased major histocompatibility complex class (MHC)-II expression, tumor necrosis factor (TNF)-α secretion, nuclear factor kappa-B (NFκB) activation, and less activation and proliferation of T cells. Our findings suggest that OPCs are not only responsible for remyelination, but they may also play an active role as innate immune cells in the CNS.

Co-administration of human MSC overexpressing HIF-1α increases human CD34+ cell engraftment in vivo

Background

Poor graft function or graft failure after allogeneic stem cell transplantation is an unmet medical need, in which mesenchymal stromal cells (MSC) constitute an attractive potential therapeutic approach. Hypoxia-inducible factor-1α (HIF-1α) overexpression in MSC (HIF-MSC) potentiates the angiogenic and immunomodulatory properties of these cells, so we hypothesized that co-transplantation of MSC-HIF with CD34⁺ human cord blood cells would also enhance hematopoietic stem cell engraftment and function both in vitro and in vivo.

Methods

Human MSC were obtained from dental pulp. Lentiviral overexpression of HIF-1α was performed transducing cells with pWPI-green fluorescent protein (GFP) (MSC WT) or pWPI-HIF-1α-GFP (HIF-MSC) expression vectors. Human cord blood CD34⁺ cells were co-cultured with MSC WT or HIF-MSC (4:1) for 72 h. Then, viability (Annexin V and 7-AAD), cell cycle, ROS expression and immunophenotyping of key molecules involved in engraftment (CXCR4, CD34, ITGA4, c-KIT) were evaluated by flow cytometry in CD34⁺ cells. In addition, CD34⁺ cells clonal expansion was analyzed by clonogenic assays. Finally, in vivo engraftment was measured by flow cytometry 4-weeks after CD34⁺ cell transplantation with or without intrabone MSC WT or HIF-MSC in NOD/SCID mice.

Results

We did not observe significant differences in viability, cell cycle and ROS expression between CD34⁺ cells co-cultured with MSC WT or HIF-MSC. Nevertheless, a significant increase in CD34, CXCR4 and ITGA4 expression (p = 0.009; p = 0.001; p = 0.013, respectively) was observed in CD34⁺ cells co-cultured with HIF-MSC compared to MSC WT. In addition, CD34⁺ cells cultured with HIF-MSC displayed a higher CFU-GM clonogenic potential than those cultured with MSC WT (p = 0.048). We also observed a significant increase in CD34⁺ cells engraftment ability when they were co-transplanted with HIF-MSC compared to CD34⁺ co-transplanted with MSC WT (p = 0.016) or alone (p = 0.015) in both the injected and contralateral femurs (p = 0.024, p = 0.008 respectively).

Conclusions

Co-transplantation of human CD34⁺ cells with HIF-MSC enhances cell engraftment in vivo. This is probably due to the ability of HIF-MSC to increase clonogenic capacity of hematopoietic cells and to induce the expression of adhesion molecules involved in graft survival in the hematopoietic niche.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02669-z.

The Multi-Elemental Composition of the Aqueous Humor of Patients Undergoing Cataract Surgery, Suffering from Coexisting Diabetes, Hypertension, or Diabetic Retinopathy

The aim of the study was the multi-elemental analysis of aqueous humor (AH) collected from patients undergoing cataract surgery. The study included: 16 patients with age-related macular degeneration AMD (99 controls), 10 patients with retinopathy (105 controls), 61 patients with hypertension (54 controls), and 33 patients with coexisting diabetes (82 controls). The control groups were recruited from patients with a lack of co-existing disease characterizing the specified studied group. The measurements were performed by the use of inductively coupled plasma optical emission spectrometry (ICP-OES). The statistical analysis was carried out using non-parametric testing (Mann–Whitney U). The level of significance was set at p = 0.05. The data obtained revealed substantial variations in elemental composition between the test groups in comparison to the controls. However, the significant variations concerned only a few elements. The phosphorous (P) level and the ratio of P/Ca were significant in retinopathy and diabetes, whereas cobalt (0.091 ± 0.107 mg/L vs. 0.031 ± 0.075 mg/L; p = 0.004) was significant in AMD. In co-existing hypertension, the levels of tin (0.293 ± 0.409 mg/L vs. 0.152 ± 0.3 mg/L; p = 0.031), titanium (0.096 ± 0.059 mg/L vs. 0.152 ± 0.192 mg/L; p = 0.045), and ruthenium (0.035 ± 0.109 mg/L vs. 0.002 ± 0.007 mg/L; p = 0.006) varied in comparison to the controls. The study revealed inter-elemental interactions. The correlation matrices demonstrated the domination of the positive correlations, whereas negative correlations mainly concerned sodium.

Activation of nuclear factor-κB in the angiogenesis of glioma: Insights into the associated molecular mechanisms and targeted therapies

Glioma is the most commonly observed primary intracranial tumour and is associated with massive angiogenesis. Glioma neovascularization provides nutrients for the growth and metabolism of tumour tissues, promotes tumour cell division and proliferation, and provides conditions ideal for the infiltration and migration of tumour cells to distant places. Growing evidence suggests that there is a correlation between the activation of nuclear factor (NF)‐κB and the angiogenesis of glioma. In this review article, we highlighted the functions of NF‐κB in the angiogenesis of glioma, showing that NF‐κB activation plays a pivotal role in the growth and progression of glioma angiogenesis and is a rational therapeutic target for antiangiogenic strategies aimed at glioma.

Galectin-3 Inhibition by a Small-Molecule Inhibitor Reduces Both Pathological Corneal Neovascularization and Fibrosis

Purpose

Corneal neovascularization and scarring commonly lead to significant vision loss. This study was designed to determine whether a small-molecule inhibitor of galectin-3 can inhibit both corneal angiogenesis and fibrosis in experimental mouse models.

Methods

Animal models of silver nitrate cautery and alkaline burn were used to induce mouse corneal angiogenesis and fibrosis, respectively. Corneas were treated with the galectin-3 inhibitor, 33DFTG, or vehicle alone and were processed for whole-mount immunofluorescence staining and Western blot analysis to quantify the density of blood vessels and markers of fibrosis. In addition, human umbilical vein endothelial cells (HUVECs) and primary human corneal fibroblasts were used to analyze the role of galectin-3 in the process of angiogenesis and fibrosis in vitro.

Results

Robust angiogenesis was observed in silver nitrate-cauterized corneas on day 5 post injury, and markedly increased corneal opacification was demonstrated in alkaline burn-injured corneas on days 7 and 14 post injury. Treatment with the inhibitor substantially reduced corneal angiogenesis and opacification with a concomitant decrease in α-smooth muscle actin (α-SMA) expression and distribution. In vitro studies revealed that 33DFTG inhibited VEGF-A-induced HUVEC migration and sprouting without cytotoxic effects. The addition of exogenous galectin-3 to corneal fibroblasts in culture induced the expression of fibrosis-related proteins, including α-SMA and connective tissue growth factor.

Conclusions

Our data provide proof of concept that targeting galectin-3 by the novel, small-molecule inhibitor, 33DFTG, ameliorates pathological corneal angiogenesis as well as fibrosis. These findings suggest a potential new therapeutic strategy for treating ocular disorders related to pathological angiogenesis and fibrosis.

Analysis and modelling of septic shock microarray data using Singular Value Decomposition

Being a high throughput technique, enormous amounts of microarray data has been generated and there arises a need for more efficient techniques of analysis, in terms of speed and accuracy. Finding the differentially expressed genes based on just fold change and p-value might not extract all the vital biological signals that occur at a lower gene expression level. Besides this, numerous mathematical models have been generated to predict the clinical outcome from microarray data, while very few, if not none, aim at predicting the vital genes that are important in a disease progression. Such models help a basic researcher narrow down and concentrate on a promising set of genes which leads to the discovery of gene-based therapies. In this article, as a first objective, we have used the lesser known and used Singular Value Decomposition (SVD) technique to build a microarray data analysis tool that works with gene expression patterns and intrinsic structure of the data in an unsupervised manner. We have re-analysed a microarray data over the clinical course of Septic shock from Cazalis et al. (2014) and have shown that our proposed analysis provides additional information compared to the conventional method. As a second objective, we developed a novel mathematical model that predicts a set of vital genes in the disease progression that works by generating samples in the continuum between health and disease, using a simple normal-distribution-based random number generator. We also verify that most of the predicted genes are indeed related to septic shock.

Phosphofructokinase-P Modulates P44/42 MAPK Levels in HeLa Cells

It is known that interfering with glycolysis leads to profound modification of cancer cell proliferation. However, energy production is not the major reason for this correlation. Here, using HeLa cells as a model for cancer, we demonstrate that phosphofructokinase-P (PFK-P), which is overexpressed in diverse types of cancer including HeLa cells, modulates expression of P44/42 mitogen-activated protein kinase (MAPK). Silencing of PFK-P did not alter HeLa cell viability or energy production, including the glycolytic rate. On the other hand, silencing of PFK-P induced the downregulation of p44/42 MAPK, augmenting the sensitivity of HeLa cells to different drugs. Conversely, overexpression of PFK-P promotes the upregulation of p44/42 MAPK, making the cells more resistant to the drugs. These results indicate that overexpression of PFK-P by cancer cells is related to activation of survival pathways via upregulation of MAPK and suggest PFK-P as a promising target for cancer therapy. J. Cell. Biochem. 118: 1216-1226, 2017. © 2016 Wiley Periodicals, Inc.

Hyperbaric Environment: Oxygen and Cellular Damage versus Protection

The elevation of tissue pO2 induced by hyperbaric oxygen (HBO) is a physiological stimulus that elicits a variety of cellular responses. These effects are largely mediated by, or in response to, an increase in the production of reactive oxygen and nitrogen species (RONS). The major consequences of elevated RONS include increased oxidative stress and enhanced antioxidant capacity, and modulation of redox-sensitive cell signaling pathways. Interestingly, these phenomena underlie both the therapeutic and potentially toxic effects of HBO. Emerging evidence indicates that supporting mitochondrial health is a potential method of enhancing the therapeutic efficacy of, and preventing oxygen toxicity during, HBO. This review will focus on the cellular consequences of HBO, and explore how these processes mediate a delicate balance of cellular protection versus damage. © 2017 American Physiological Society. Compr Physiol 7:213-234, 2017.

Hydrogels bearing bioengineered mimetic embryonic microenvironments for tumor reversion

Embryonic microenvironments can reverse the metastatic phenotype of aggressive tumors by inhibiting the Nodal signaling pathway. Here, we hypothesize that embryonic microenvironments can be transplanted for the purpose of oncotherapy. We report the development of an injectable bioactive hydrogel system containing the key antagonists of Nodal signaling-Cripto-1 receptor antibodies (2B11)-for the creation of embryonic microenvironments and the examination of their effect on tumor reversion treatment using a mouse model. Our in vitro results show that the hydrogel system can reduce the mitochondrial membrane potential of MDA-MB-231 and MCF-7, promote cell apoptosis, and reduce the invasive ability of cells. Our in vivo results illustrate that the hydrogel system can significantly inhibit tumor growth in both breast cancer and melanoma tumor-bearing mouse models, as well as transform the cell morphology of melanoma B16 cells to melanin-like cells. Furthermore, the results of the up-regulation of tumor suppressor genes and the down-regulation of oncogenes by high-throughput sequencing confirm that the developed system can also selectively turn on some tumor suppressor genes and turn off certain oncogenes so as to prompt the benign reversion of the tumor phenotype. Taken together, our results demonstrate the injectable biomaterial system is able to create an effective microenvironment for melanoma and breast tumor therapy.

Towards molecular mechanisms regulating the expression of galectins in cancer cells under microenvironmental stress conditions

Galectins, a family of soluble β-galactoside-binding proteins, serve as mediators of fundamental biological processes, such as cell growth, differentiation, adhesion, migration, survival, and death. The purpose of this review is to summarize the current knowledge regarding the ways in which the expression of individual galectins differs in normal and transformed human cells exposed to various stimuli mimicking physiological and pathological microenvironmental stress conditions. A conceptual point is being made and grounded that the modulation of galectin expression profiles is a key aspect of cellular stress responses. Moreover, this modulation might be precisely regulated at transcriptional and post-transcriptional levels in the context of non-overlapping transcription factors and miRNAs specific to galectins.

Galectin-3 up-regulation in hypoxic and nutrient deprived microenvironments promotes cell survival

Galectin-3 (gal-3) is a β-galactoside binding protein related to many tumoral aspects, e.g. angiogenesis, cell growth and motility and resistance to cell death. Evidence has shown its upregulation upon hypoxia, a common feature in solid tumors such as glioblastoma multiformes (GBM). This tumor presents a unique feature described as pseudopalisading cells, which accumulate large amounts of gal-3. Tumor cells far from hypoxic/nutrient deprived areas express little, if any gal-3. Here, we have shown that the hybrid glioma cell line, NG97ht, recapitulates GBM growth forming gal-3 positive pseudopalisades even when cells are grafted subcutaneously in nude mice. In vitro experiments were performed exposing these cells to conditions mimicking tumor areas that display oxygen and nutrient deprivation. Results indicated that gal-3 transcription under hypoxic conditions requires previous protein synthesis and is triggered in a HIF-1α and NF-κB dependent manner. In addition, a significant proportion of cells die only when exposed simultaneously to hypoxia and nutrient deprivation and demonstrate ROS induction. Inhibition of gal-3 expression using siRNA led to protein knockdown followed by a 1.7–2.2 fold increase in cell death. Similar results were also found in a human GBM cell line, T98G. In vivo, U87MG gal-3 knockdown cells inoculated subcutaneously in nude mice demonstrated decreased tumor growth and increased time for tumor engraftment. These results indicate that gal-3 protected cells from cell death under hypoxia and nutrient deprivation in vitro and that gal-3 is a key factor in tumor growth and engraftment in hypoxic and nutrient-deprived microenvironments. Overexpression of gal-3, thus, is part of an adaptive program leading to tumor cell survival under these stressing conditions.

Hypoxia induces a HIF-1α dependent signaling cascade to make a complex metabolic switch in SGBS-adipocytes

To elucidate the complex impact of hypoxia on adipose tissue, resulting in biased metabolism, insulin resistance and finally diabetes we used mature adipocytes derived from a Simpson-Golabi-Behmel syndrome patient for microarray analysis. We found a significantly increased transcription rate of genes involved in glycolysis and a striking association between the pattern of upregulated genes and disease biomarkers for diabetes mellitus and insulin resistance. Although their upregulation turned out to be HIF-1α-dependent, we identified further transcription factors mainly AP-1 components to play also an important role in hypoxia response. Analyzing the regulatory network of mentioned transcription factors and glycolysis targets we revealed a clear hint for directing glycolysis to glutathione and glycogen synthesis. This metabolic switch in adipocytes enables the cell to prevent oxidative damage in the short term but might induce lipogenesis and establish systemic metabolic disorders in the long run.

Identification of novel gene targets and functions of p21-activated kinase 1 during DNA damage by gene expression profiling

P21-activated kinase 1 (PAK1), a serine/threonine protein kinase, modulates many cellular processes by phosphorylating its downstream substrates. In addition to its role in the cytoplasm, PAK1 also affects gene transcription due to its nuclear localization and association with chromatin. It is now recognized that PAK1 kinase activity and its nuclear translocation are rapidly stimulated by ionizing radiation (IR), and that PAK1 activation is a component of the DNA damage response. Owing to the role of PAK1 in the cell survival, its association with the chromatin, and now, stimulation by ionizing radiation, we hypothesize that PAK1 may be contributing to modulation of genes with roles in cellular processes that might be important in the DNA damage response. The purpose of this study was to identify new PAK1 targets in response to ionizing radiation with putative role in the DNA damage response. We examined the effect of IR on the gene expression patterns in the murine embryonic fibroblasts with or without Pak1 using microarray technology. Differentially expressed transcripts were identified using Gene Spring GX 10.0.2. Pathway, network, functional analyses and gene family classification were carried out using Kyoto Encyclopedia of Genes and Genomes (KEGG), Ingenuity Pathway, Gene Ontology and PANTHER respectively. Selective targets of PAK1 were validated by RT-qPCR. For the first time, we provide a genome-wide analysis of PAK1 and identify its targets with potential roles in the DNA damage response. Gene Ontology analysis identified genes in the IR-stimulated cells that were involved in cell cycle arrest and cell death. Pathway analysis revealed p53 pathway being most influenced by IR responsive, PAK1 targets. Gene family of transcription factors was over represented and gene networks involved in DNA replication, repair and cellular signaling were identified. In brief, this study identifies novel PAK1 dependent IR responsive genes which reveal new aspects of PAK1 biology.

Heterogeneous nuclear ribonucleoprotein K (hnRNP-K) promotes tumor metastasis by induction of genes involved in extracellular matrix, cell movement, and angiogenesis

Cancer is a leading cause of death and still awaits effective therapies. Rapid industrialization has contributed to increase in incidence of cancer. One of the reasons why most of the cancers fail therapy is due to their metastatic property. Hence identification of factors leading to metastasis is highly important to design effective and novel anti-cancer therapeutics. In our earlier study (Inoue, A., Sawata, S. Y., Taira, K., and Wadhwa, R. (2007) Loss-of-function screening by randomized intracellular antibodies: identification of hnRNP-K as a potential target for metastasis. Proc. Natl. Acad. Sci. U.S.A. 104, 8983-8988), we had reported that the involvement of heterogeneous nuclear ribonucleoprotein K (hnRNP-K) in metastasis. Here, we established hnRNP-K-overexpressing and -underexpressing derivative cell lines and examined their proliferation and metastatic properties in vitro and in vivo. Whereas hnRNP-K compromised cells showed delayed tumor growth, its overexpression resulted in enhanced malignancy and metastasis. Molecular basis of the hnRNP-K induced malignant and metastatic phenotypes was dissected by cDNA microarray and pathway analyses. We found that the hnRNP-K regulates extracellular matrix, cell motility, and angiogenesis pathways. Involvement of the selected genes (Cck, Mmp-3, Ptgs2, and Ctgf) and pathways was validated by gene-specific expression analysis. Our results demonstrated that the hnRNP-K is a potential target for metastasis therapy.

Levels of aqueous humor trace elements in patients with non-exsudative age-related macular degeneration: a case-control study

Trace elements might play a role in the complex multifactorial pathogenesis of age-related macular degeneration (AMD). The aim of this study was to measure alterations of trace elements levels in aqueous humor of patients with non-exsudative (dry) AMD.

For this pilot study, aqueous humor samples were collected from patients undergoing cataract surgery. 12 patients with dry AMD (age 77.9±6.62, female 8, male 4) and 11 patients without AMD (age 66.6±16.7, female 7, male 4) were included. Aqueous levels of cadmium, cobalt, copper, iron, manganese, selenium, and zinc were measured by use of Flow-Injection-Inductively-Coupled-Plasma-Mass-Spectrometry (FI-ICP-MS), quality controlled with certified standards.

Patients with AMD had significantly higher aqueous humor levels of cadmium (median: 0.70 µmol/L, IQR: 0.40–0.84 vs. 0.06 µmol/L; IQR: 0.01–.018; p = 0.002), cobalt (median: 3.1 µmol/L, IQR: 2.62–3.15 vs. 1.17 µmol/L; IQR: 0.95–1.27; p<0.001), iron (median: 311 µmol/L, IQR: 289–329 vs. 129 µmol/L; IQR: 111–145; p<0.001) and zinc (median: 23.1 µmol/L, IQR: 12.9–32.6 vs. 5.1 µmol/L; IQR: 4.4–9.4; p = 0.020) when compared with patients without AMD. Copper levels were significantly reduced in patients with AMD (median: 16.2 µmol/L, IQR: 11.4–31.3 vs. 49.9 µmol/L; IQR: 32.0–.142.0; p = 0.022) when compared to those without. No significant differences were observed in aqueous humor levels of manganese and selenium between patients with and without AMD. After an adjustment for multiple testing, cadmium, cobalt, copper and iron remained a significant factor in GLM models (adjusted for age and gender of the patients) for AMD.

Alterations of trace element levels support the hypothesis that cadmium, cobalt, iron, and copper are involved in the pathogenesis of AMD.

Implications on glycobiological aspects of tumor hypoxia in breast ductal carcinoma in situ

Breast carcinoma is one of the most common neoplasia and the first cause of women cancer related deaths worldwide. In the past few years with diagnostic increment, the number of patients diagnosed with ductal carcinoma in situ (DCIS) increased considerably and opened up new ways in research and new dilemmas in diagnostic and clinical practice. This work aimed to evaluate differences in Galectin-1 and Galectin-3 expression and lectins ligands profile on DCIS cells in hypoxic microenvironment. Lectin histochemistry and immunohistochemistry were performed with Concanavalin A, Wheat Germ Agglutinin, Peanut Agglutinin and Ulex europaeus Agglutinin lectins and with anti-Galectin-1 and anti-Galectin-3 antibodies. Lectin ligands were more recognized in hypoxic lesions by Concanavalin A (p = 0.0019), Wheat Germ Agglutinin (p < 0.001) and Ulex europaeus Agglutinin (p = 0.0014), but not by Peanut Agglutinin (p = 0.5779) when compared to non-hypoxic. Galectin-1 was not observed in all cases analyzed on both groups, differing from Galectin-3 that was overexpressed on cytoplasm of DCIS hypoxic group in relation to control group (p = 0.031). As far as we are concerned, this is the first paper that describes glycobiological alterations in breast cancer hypoxic environment in vivo that could be used to validate in vitro models on this aspect. Moreover, comedogenic/necrotic carcinomas were usually associated with poor-prognostic than others, and our results show that glycosylation may play an important role in this event.

Hypoxia-induced transcriptional repression of the melanoma-associated oncogene MITF

Microphthalmia-associated transcription factor (MITF) regulates normal melanocyte development and is also a lineage-selective oncogene implicated in melanoma and clear-cell sarcoma (i.e., melanoma of soft parts). We have observed that MITF expression is potently reduced under hypoxic conditions in primary melanocytes and melanoma and clear cell sarcoma cells through hypoxia inducible factor 1 (HIF1)-mediated induction of the transcriptional repressor differentially expressed in chondrocytes protein 1 (DEC1) (BHLHE40), which subsequently binds and suppresses the promoter of M-MITF (melanocyte-restricted MITF isoform). Correspondingly, hypoxic conditions or HIF1α stabilization achieved by using small-molecule prolyl-hydroxylase inhibitors reduced M-MITF expression, leading to melanoma cell growth arrest that was rescued by ectopic expression of M-MITF in vitro. Prolyl hydroxylase inhibition also potently suppressed melanoma growth in a mouse xenograft model. These studies illuminate a physiologic hypoxia response in pigment cells leading to M-MITF suppression, one that suggests a potential survival advantage mechanism for MITF amplification in metastatic melanoma and offers a small-molecule strategy for suppression of the MITF oncogene in vivo.

Hypoxia and MITF control metastatic behaviour in mouse and human melanoma cells

Melanomas are very aggressive neoplasms with notorious resistance to therapeutics. It was recently proposed that the remarkable phenotypic plasticity of melanoma cells allows for the rapid development of both resistance to chemotherapeutic drugs and invasive properties. Indeed, the capacity of melanoma cells to form distant metastases is the main cause of mortality in melanoma patients. Therefore, the identification of the mechanism controlling melanoma phenotype is of paramount importance. In the present report, we show that deletion of microphthalmia-associated transcription factor (MITF), the master gene in melanocyte differentiation, is sufficient to increase the metastatic potential of mouse and human melanoma cells. MITF silencing also increases fibronectin and Snail, two mesenchymal markers that might explain the increased invasiveness in vitro and in vivo. Furthermore, ablation of this population by Forskolin-induced differentiation or MITF-forced expression significantly decreases tumour and metastasis formation, suggesting that eradication of low-MITF cells might improve melanoma treatment. Moreover, we demonstrate that a hypoxic microenvironment decreases MITF expression through an indirect, hypoxia-inducible factor 1 (HIF1)α-dependant transcriptional mechanism, and increases the tumourigenic and metastatic properties of melanoma cells. We identified Bhlhb2, a new factor in melanoma biology, as the mediator of hypoxia/HIF1α inhibitory effect on MITF expression. Our results reveal a hypoxia-HIF1α-BHLHB2-MITF cascade controlling the phenotypic plasticity in melanoma cells and favouring metastasis development. Targeting this pathway might be helpful in the design of new anti-melanoma therapies.

Intrauterine growth restriction modifies the developmental pattern of intestinal structure, transcriptomic profile, and bacterial colonization in neonatal pigs

Neonates with intrauterine growth restriction (IUGR) are prone to suffer from digestive diseases. Using neonatal pigs with IUGR, we tested the hypothesis that IUGR may induce alterations in the developmental pattern of intestinal barrier and thereby may be responsible for IUGR-associated increased morbidity. Piglets with a birth weight near the mean birth weight (+/-0.5 SD) were identified as normal birth weight (control) and piglets with a mean -2 SD lower birth weight (-30%) were defined as piglets with IUGR. The developmental pattern of intestinal structure, transcriptomic profile, and bacterial colonization was investigated from birth to d 5 postnatal. At birth, intestinal weight and length, ileal and colonic weight per unit of length, and villous sizes were lower (P < 0.05) in piglets with IUGR than in same-age control piglets. These IUGR-induced intestinal alterations further persisted, although they were less marked at d 5. Counts of adherent bacteria to ileal and colonic mucosa were greater (P < 0.05) in 2-d-old piglets with IUGR than in same-age control piglets. Dynamic analyses of the transcriptomic profile of the intestine revealed molecular evidence of IUGR-induced intestinal growth impairment that may result from a change in the cell proliferation-apoptosis balance during the first days of life, while a protective process would occur later on. In addition, changes in the expression of several genes suggest a pivotal role of both glucocorticoids and microbiota in driving IUGR intestinal development during the neonatal period.

Tungsten carbide cobalt nanoparticles exert hypoxia-like effects on the gene expression level in human keratinocytes

Background

Tungsten carbide (WC) and tungsten carbide cobalt (WC-Co) nanoparticles are of occupational health relevance because of the increasing usage in hard metal industries. Earlier studies showed an enhanced toxic potential for WC-Co compared to WC or cobalt ions alone. Therefore, we investigated the impact of these particles, compared to cobalt ions applied as CoCl₂, on the global gene expression level in human keratinocytes (HaCaT) in vitro.

Results

WC nanoparticles exerted very little effects on the transcriptomic level after 3 hours and 3 days of exposure. In contrast, WC-Co nanoparticles caused significant transcriptional changes that were similar to those provoked by CoCl₂. However, CoCl₂ exerted even more pronounced changes in the transcription patterns. Gene set enrichment analyses revealed that the differentially expressed genes were related to hypoxia response, carbohydrate metabolism, endocrine pathways, and targets of several transcription factors. The role of the transcription factor HIF1 (hypoxia inducible factor 1) is particularly highlighted and aspects of downstream events as well as the role of other transcription factors related to cobalt toxicity are considered.

Conclusions

This study provides extensive data useful for the understanding of nanoparticle and cobalt toxicity. It shows that WC nanoparticles caused low transcriptional responses while WC-Co nanoparticles are able to exert responses similar to that of free cobalt ions, particularly the induction of hypoxia-like effects via interactions with HIF1α in human keratinocytes. However, the enhanced toxicity of WC-Co particles compared to CoCl₂ could not be explained by differences in gene transcription.

Gene expression microarray analysis of early oxygen-induced retinopathy in the rat

Different inbred strains of rat differ in their susceptibility to oxygen-induced retinopathy (OIR), an animal model of human retinopathy of prematurity. We examined gene expression in Sprague-Dawley (susceptible) and Fischer 344 (resistant) neonatal rats after 3 days exposure to cyclic hyperoxia or room air, using Affymetrix rat Genearrays. False discovery rate analysis was used to identify differentially regulated genes. Such genes were then ranked by fold change and submitted to the online database, DAVID. The Sprague-Dawley list returned the term "response to hypoxia," absent from the Fischer 344 output. Manual analysis indicated that many genes known to be upregulated by hypoxia-inducible factor-1alpha were downregulated by cyclic hyperoxia. Quantitative real-time RT-PCR analysis of Egln3, Bnip3, Slc16a3, and Hk2 confirmed the microarray results. We conclude that combined methodologies are required for adequate dissection of the pathophysiology of strain susceptibility to OIR in the rat. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12177-009-9041-7) contains supplementary material, which is available to authorized users.

Causes and consequences of increased glucose metabolism of cancers

In this review we examine the mechanisms (causes) underlying the increased glucose consumption observed in tumors within a teleological context (consequences). In other words, we will ask not only "How do cancers have high glycolysis?" but also, "Why?" We believe that the insights gained from answering the latter question support the conclusion that elevated glucose consumption is a necessary component of carcinogenesis. Specifically we propose that glycolysis is elevated because it produces acid, which provides an evolutionary advantage to cancer cells vis-à-vis normal parenchyma into which they invade.

Connective tissue growth factor (CTGF) and cancer progression

Connective tissue growth factor (CTGF) is a member of the CCN family of secreted, matrix-associated proteins encoded by immediate early genes that play various roles in angiogenesis and tumor growth. CCN family proteins share uniform modular structure which mediates various cellular functions such as regulation of cell division, chemotaxis, apoptosis, adhesion, motility, angiogenesis, neoplastic transformation, and ion transport. Recently, CTGF expression has been shown to be associated with tumor development and progression. There is growing body of evidence that CTGF may regulate cancer cell migration, invasion, angiogenesis, and anoikis. In this review, we will highlight the influence of CTGF expression on the biological behavior and progression of various cancer cells, as well as its regulation on various types of protein signals and their mechanisms.

Hypoxia in human trophoblasts stimulates the expression and secretion of connective tissue growth factor

The mechanisms underlying cellular injury when human placental trophoblasts are exposed to hypoxia are unclear. Connective tissue growth factor (CTGF) mediates cell injury and fibrosis in diverse tissues. We hypothesized that hypoxia enhances the production of CTGF in primary term human trophoblasts. Using cultured term primary human trophoblasts as well as villous biopsies from term human placentas, we showed that CTGF protein is expressed in trophoblasts. When compared with cells cultured in standard conditions (FiO2 = 20%), exposure of primary human trophoblasts to low oxygen concentration (FiO2 = 8% or <or= 1%) enhanced the expression of CTGF mRNA in a time-dependent manner, with a significant increase in CTGF levels after 16 h (2.7 +/- 0.7-fold; P < 0.01), reaching a maximum of 10.9 +/- 3.2-fold at 72 h. Whereas exposure to hypoxia had no effect on cellular CTGF protein levels, secretion of CTGF to the medium was increased after 16 h in hypoxia and remained elevated through 72 h. The increase in cellular CTGF transcript levels and CTGF protein secretion was recapitulated by exposure of trophoblasts to agents that enhance the activity of hypoxia-inducible factor (HIF)1alpha, including cobalt chloride or the proline hydroxylase inhibitor dimethyloxaloylglycine, and attenuated using the HIF1alpha inhibitor 2-methoxyestradiol. Although all TGFbeta isoforms stimulated the expression of CTGF in trophoblasts, only the expression of TGFbeta1 mRNA was enhanced by hypoxia. We conclude that hypoxia increases cellular CTGF mRNA levels and CTGF protein secretion from cultured trophoblasts, likely in a HIF1alpha-dependent manner.

In vitro expression of hard metal dust (WC-Co)--responsive genes in human peripheral blood mononucleated cells

Hard metals consist of tungsten carbide (WC) and metallic cobalt (Co) particles and are important industrial materials produced for their extreme hardness and high wear resistance properties. While occupational exposure to metallic Co alone is apparently not associated with an increased risk of cancer, the WC-Co particle mixture was shown to be carcinogenic in exposed workers. The in vitro mutagenic/apoptogenic potential of WC-Co in human peripheral blood mononucleated cells was previously demonstrated by us. This study aimed at obtaining a broader view of the pathways responsible for WC-Co induced carcinogenicity, and in particular genotoxicity and apoptosis. We analyzed the profile of gene expression induced in vitro by WC-Co versus control (24 h treatment) in human PBMC and monocytes using microarrays. The most significantly up-regulated pathways for WC-Co treated PBMC were apoptosis and stress/defense response; the most down-regulated was immune response. For WC-Co treated monocytes the most significantly up- and down-regulated pathways were nucleosome/chromatin assembly and immune response respectively. Quantitative RT-PCR data for a selection of the most strongly modulated genes (HMOX1, HSPA1A, HSPA1L, BNIP3, BNIP3L, ADORA2B, MT3, PLA2G7, TNFAIP6), and some additionally chosen apoptosis related genes (BCL2, BAX, FAS, FASL, TNFalpha), confirmed the microarray data after WC-Co exposure and demonstrated limited differences between the Co-containing compounds. Overall, this study provides the first analysis of gene expression induced by the WC-Co mixture showing a large profile of gene modulation and giving a preliminary indication for a hypoxia mimicking environment induced by WC-Co exposure.

The 5' untranslated regions (UTRs) of CCN1, CCN2, and CCN4 exhibit cryptic promoter activity

CCNs are structurally related matricellular proteins that are highly expressed in many embryonic and adult tissues, including the skeletal system and tumors, where canonical cap-dependent translation is suppressed under hypoxic environments. CCNs are encoded by mRNAs containing long G/C rich 5'-untranslated regions (5'-UTRs). Given that they are expressed under conditions of cellular stress, it has been suggested that the long G/C-rich regions contain internal ribosomal entry sites (IRES) that allow these mRNAS to be translated under conditions where cap-dependent translation is suppressed. Previously published work supported this possibility. However, recent studies have shown that a number of previously reported cellular IRES elements do not in fact possess IRES activity. Here we aimed to reveal whether the 5'UTRs of CCNs harbor IRES activities. The 5'UTRs of CCN1, 2, and 4 were tested in this study. Our results showed that the 5'UTRs of these genes do not contain IRES elements, but instead appear to contain cryptic promoters. Both promoterless and hairpin-containing dicistronic tests showed that transcription was initiated by cryptic promoter elements in 5'UTRs of CCN1, 2, and 4. When dicistronic mRNAs were translated in vitro or in vivo, no IRES activities were detected in the 5'UTRs of CCN1, 2, and 4. Furthermore, these cryptic promoter activities from 5'UTRs of CCN1, 2, and 4 could be detected in various cell types, including chondrocytes, osteoblasts, and endothelial cells, where the cryptic promoter permitted varying degrees of activation. In addition, the core promoter element of the CCN2 5'UTR was identified. CCNs are expressed under conditions of cellular stress, and it has been suggested that some CCN family members utilize IRES-mediated translation initiation to facilitate this expression. We found no evidence for IRES activity, but rather found that the unusually long 5'UTRs of CCNs 1, 2, and 4 harbor cryptic promoters that showed varying degrees of activity in different cell types. These results suggest that these promoters may contribute to the regulation of CCN genes in vivo.