The mechanosensitive TRPV2 calcium channel promotes human melanoma invasiveness and metastatic potential

Melanoma is a highly aggressive cancer endowed with a unique capacity of rapidly metastasizing, which is fundamentally driven by aberrant cell motility behaviors. Discovering "migrastatics" targets, specifically controlling invasion and dissemination of melanoma cells during metastasis, is therefore of primary importance. Here, we uncover the prominent expression of the plasma membrane TRPV2 calcium channel as a distinctive feature of melanoma tumors, directly related to melanoma metastatic dissemination. In vitro as well as in vivo, TRPV2 activity is sufficient to confer both migratory and invasive potentials, while conversely TRPV2 silencing in highly metastatic melanoma cells prevents aggressive behavior. In invasive melanoma cells, TRPV2 channel localizes at the leading edge, in dynamic nascent adhesions, and regulates calcium-mediated activation of calpain and the ensuing cleavage of the adhesive protein talin, along with F-actin organization. In human melanoma tissues, TRPV2 overexpression correlates with advanced malignancy and poor prognosis, evoking a biomarker potential. Hence, by regulating adhesion and motility, the mechanosensitive TRPV2 channel controls melanoma cell invasiveness, highlighting a new therapeutic option for migrastatics in the treatment of metastatic melanoma.

Altered epithelial barrier functions in the colon of patients with spina bifida

Our objectives were to better characterize the colorectal function of patients with Spina Bifida (SB). Patients with SB and healthy volunteers (HVs) completed prospectively a standardized questionnaire, clinical evaluation, rectal barostat, colonoscopy with biopsies and faecal collection. The data from 36 adults with SB (age: 38.8 [34.1-47.2]) were compared with those of 16 HVs (age: 39.0 [31.0-46.5]). Compared to HVs, rectal compliance was lower in patients with SB (p = 0.01), whereas rectal tone was higher (p = 0.0015). Ex vivo paracellular permeability was increased in patients with SB (p = 0.0008) and inversely correlated with rectal compliance (r = - 0.563, p = 0.002). The expression of key tight junction proteins and inflammatory markers was comparable between SB and HVs, except for an increase in Claudin-1 immunoreactivity (p = 0.04) in SB compared to HVs. TGFβ1 and GDNF mRNAs were expressed at higher levels in patients with SB (p = 0.02 and p = 0.008). The levels of acetate, propionate and butyrate in faecal samples were reduced (p = 0.04, p = 0.01, and p = 0.02, respectively). Our findings provide evidence that anorectal and epithelial functions are altered in patients with SB. The alterations in these key functions might represent new therapeutic targets, in particular using microbiota-derived approaches.Clinical Trials: NCT02440984 and NCT03054415.

Integration of Raman spectra with transcriptome data in glioblastoma multiforme defines tumour subtypes and predicts patient outcome

Raman spectroscopy is an imaging technique that has been applied to assess molecular compositions of living cells to characterize cell types and states. However, owing to the diverse molecular species in cells and challenges of assigning peaks to specific molecules, it has not been clear how to interpret cellular Raman spectra. Here, we provide firm evidence that cellular Raman spectra (RS) and transcriptomic profiles of glioblastoma can be computationally connected and thus interpreted. We find that the dimensions of high-dimensional RS and transcriptomes can be reduced and connected linearly through a shared low-dimensional subspace. Accordingly, we were able to predict global gene expression profiles by applying the calculated transformation matrix to Raman spectra and vice versa. From these analyses, we extract a minimal gene expression signature associated with specific RS profiles and predictive of disease outcome.

Towards a Reduced In Silico Model Predicting Biochemical Recurrence After Radiotherapy in Prostate Cancer

OBJECTIVE

Purposes of this work were i) to develop an in silico model of tumor response to radiotherapy, ii) to perform an exhaustive sensitivity analysis in order to iii) propose a simplified version and iv) to predict biochemical recurrence with both the comprehensive and the reduced model.

METHODS

A multiscale computational model of tumor response to radiotherapy was developed. It integrated the following radiobiological mechanisms: oxygenation, including hypoxic death; division of tumor cells; VEGF diffusion driving angiogenesis; division of healthy cells and oxygen-dependent response to irradiation, considering, cycle arrest and mitotic catastrophe. A thorough sensitivity analysis using the Morris screening method was performed on 21 prostate computational tissues. Tumor control probability (TCP) curves of the comprehensive model and 15 reduced versions were compared. Logistic regression was performed to predict biochemical recurrence after radiotherapy on 76 localized prostate cancer patients using an output of the comprehensive and the reduced models.

RESULTS

No significant difference was found between the TCP curves of the comprehensive and a simplified version which only considered oxygenation, division of tumor cells and their response to irradiation. Biochemical recurrence predictions using the comprehensive and the reduced models improved those made from pre-treatment imaging parameters (AUC = 0.81 ± 0.02 and 0.82 ± 0.02 vs. 0.75 ± 0.03, respectively).

CONCLUSION

A reduced model of tumor response to radiotherapy able to predict biochemical recurrence in prostate cancer was obtained.

SIGNIFICANCE

This reduced model may be used in the future to optimize personalized fractionation schedules.

Sciadonic acid derived from pine nuts as a food component to reduce plasma triglycerides by inhibiting the rat hepatic Δ9-desaturase

Sciadonic acid (Scia) is a Δ5-olefinic fatty acid that is particularly abundant in edible pine seeds and that exhibits an unusual polymethylene-interrupted structure. Earlier studies suggested that Scia inhibited the in vitro expression and activity of the Stearoyl-CoA Desaturase 1 (SCD1), the hepatic Δ9-desaturase involved in the formation of mono-unsaturated fatty acids. To confirm this hypothesis, rats were given 10% Scia in diets balanced out with n-6 and n-3 fatty acids. In those animals receiving the Scia supplement, monoene synthesis in the liver was reduced, which was partly attributed to the inhibition of SCD1 expression. As a consequence, the presence of Scia induced a 50% decrease in triglycerides in blood plasma due to a reduced level of VLDL-secreted triglycerides from the liver. In non-fasting conditions, results showed that Scia-induced inhibition of SCD1 led to a decrease in the proportions of 16:1n-7 and 18:1n-7 in the liver without impacting on the level of 18:1n-9, suggesting that only triglycerides with neosynthesized monoenes are marked out for release. In conclusion, this in vivo study confirms that Scia highly inhibits SCD1 expression and activity. The work was performed on normo-triglyceride rats over six weeks, suggesting promising effects on hyper-triglyceridemic models.

One-step nucleic acid amplification for detecting lymph node metastasis of head and neck squamous cell carcinoma

BACKGROUND

In head and neck squamous cell carcinoma (HNSCC) 30% of cN0 patients have occult metastasis. LN invasion is a major prognostic factor. Sentinel lymph node (SLN) is an option for cN0 neck management. One-step nucleic acid amplification (OSNA) used to analyze SLN in breast cancer is also a candidate to get more reliable intraoperative HNSCC lymph node (LN) staging.

OBJECTIVE

To compare OSNA analysis to pathological analysis in cN0 HNSCC.

MATERIALS AND METHODS

157 LN from 26 cN0 HNSCC patients were prospectively analyzed (6.3LN/patient). Exclusion criteria were previous surgery or radiotherapy. Each node was cut into 4 equal pieces alternatively sent to pathological analysis and OSNA technique. IHC CK19 was performed on the primary tumor biopsy and RT-qPCR of CK19, PVA and EPCAM on the LN lysate of discordant cases.

RESULTS

OSNA was able to provide intraoperative result in all patients. OSNA detected 21 metastases. There were 139 concordant LN (88.5%). There were 18 initial discordant LN (11.5%), 13 (8.3%) were OSNA positive/pathological analysis negative, 5 (3.2%) were OSNA negative/pathological analysis positive. After elimination of allocation bias, false negative rate was 1.3%, sensitivity and specificity were 90% and 95.6%, PPV and NPV were 75% and 98.5%.

CONCLUSION

Our results suggest that OSNA should be considered to improve SNB analysis both for increasing micro metastasis diagnosis and offer extemporaneous results. Study registered under clinicaltrials.gov database number NCT02852343.

Autophagie et spermatozoïde

La spermiogenèse, étape ultime de la spermatogenèse, est un processus qui fait intervenir des acteurs qui participe à l’autophagie. C’est en effet lors de cette étape que se forme l’acrosome par fusion vésiculaire et que disparaît la majeure partie du cytoplasme du spermatozoïde. L’autophagie (littéralement « se manger soi-même »), en permettant l’élimination et le remplacement continuel des protéines et des organites non fonctionnels, assure le recyclage des constituants de la cellule. C’est un mécanisme cellulaire très conservé au sein des cellules eucaryotes. La machinerie de l’autophagie est également présente dans les spermatozoïdes. Elle régule la vitalité de ces cellules et leur mobilité. Les conséquences environnementales et comportementales sur l’autophagie et sur la spermatogenèse commencent à être étudiées. Le but de cette revue est de synthétiser les connaissances actuelles concernant les processus d’autophagie dans le gamète mâle mature.

Smooth muscle of the male pelvic floor: An anatomic study

Knowledge of the anatomy of the male pelvic floor is important to avoid damaging the pelvic floor muscles during surgery. We set out to explore the structure and innervation of the smooth muscle (SM) of the whole pelvic floor using male fetuses. We removed en-bloc the entire pelvis of three male fetuses. The specimens were serially sectioned before being stained with Masson's trichrome and hematoxylin and eosin, and immunostained for SMs, and somatic, adrenergic, sensory and nitrergic nerve fibers. Slides were digitized for three-dimensional reconstruction. We individualized a middle compartment that contains SM cells. This compartment is in close relation with the levator ani muscle (LAM), rectum, and urethra. We describe a posterior part of the middle compartment posterior to the rectal wall and an anterior part anterior to the rectal wall. The anterior part is split into (1) a centro-levator area of SM cells localized between the right and left LAM, (2) an endo-levator area that upholsters the internal aspect of the LAM, and (3) an infra-levator area below the LAM. All these areas are innervated by autonomic nerves coming from the inferior hypogastric plexus. The core and the infra-levator area receive the cavernous nerve and nerves supplying the urethra. We thus demonstrate that these muscular structures are smooth and under autonomic influence. These findings are relevant for the pelvic surgeon, and especially the urologist, during radical prostatectomy, abdominoperineal resection and intersphincteric resection. Clin. Anat., 2019. © 2019 Wiley Periodicals, Inc.

Casein kinase 1ε and 1α as novel players in polycystic kidney disease and mechanistic targets for (R)-roscovitine and (S)-CR8

Following the discovery of (R)-roscovitine's beneficial effects in three polycystic kidney disease (PKD) mouse models, cyclin-dependent kinases (CDKs) inhibitors have been investigated as potential treatments. We have used various affinity chromatography approaches to identify the molecular targets of roscovitine and its more potent analog (S)-CR8 in human and murine polycystic kidneys. These methods revealed casein kinases 1 (CK1) as additional targets of the two drugs. CK1ε expression at the mRNA and protein levels is enhanced in polycystic kidneys of 11 different PKD mouse models as well as in human polycystic kidneys. A shift in the pattern of CK1α isoforms is observed in all PKD mouse models. Furthermore, the catalytic activities of both CK1ε and CK1α are increased in mouse polycystic kidneys. Inhibition of CK1ε and CK1α may thus contribute to the long-lasting attenuating effects of roscovitine and (S)-CR8 on cyst development. CDKs and CK1s may constitute a dual therapeutic target to develop kinase inhibitory PKD drug candidates.

CD95-Mediated Calcium Signaling Promotes T Helper 17 Trafficking to Inflamed Organs in Lupus-Prone Mice

CD95 ligand (CD95L) is expressed by immune cells and triggers apoptotic death. Metalloprotease-cleaved CD95L (cl-CD95L) is released into the bloodstream but does not trigger apoptotic signaling. Hence, the pathophysiological role of cl-CD95L remains unclear. We observed that skin-derived endothelial cells from systemic lupus erythematosus (SLE) patients expressed CD95L and that after cleavage, cl-CD95L promoted T helper 17 (Th17) lymphocyte transmigration across the endothelial barrier at the expense of T regulatory cells. T cell migration relied on a direct interaction between the CD95 domain called calcium-inducing domain (CID) and the Src homology 3 domain of phospholipase Cγ1. Th17 cells stimulated with cl-CD95L produced sphingosine-1-phosphate (S1P), which promoted endothelial transmigration by activating the S1P receptor 3. We generated a cell-penetrating CID peptide that prevented Th17 cell transmigration and alleviated clinical symptoms in lupus mice. Therefore, neutralizing the CD95 non-apoptotic signaling pathway could be an attractive therapeutic approach for SLE treatment.

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CD95-mediated Ca²⁺ response promotes endothelial transmigration of Th17 cells

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CD95 interacts with PLCγ1 to induce Ca²⁺ response and Th17 cell migration

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Ca²⁺ response stems from a CD95 region different from death domain

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Inhibition of the CD95-mediated Ca²⁺ response alleviates disease in lupus-prone mice

Slice correspondence estimation using SURF descriptors and context-based search for prostate whole-mount histology MRI registration

Registration of histopathology volumes to Magnetic Resonance Images(MRI) is a crucial step for finding correlations in Prostate Cancer (PCa) and assessing tumor agressivity. This paper proposes a two-stage framework aimed at registering both modalities. Firstly, Speeded-Up Robust Features (SURF) algorithm and a context-based search is used to automatically determine slice correspondences between MRI and histology volumes. This step initializes a multimodal nonrigid registration strategy, which allows to propagate histology slices to MRI. Evaluation was performed on 5 prospective studies using a slice index score and landmark distances. With respect to a manual ground truth, the first stage of the framework exhibited an average error of 1,54 slice index and 3,51 mm in the prostate specimen. The reconstruction of a three-dimensional Whole-Mount Histology (WMH) shows promising results aimed to perform later PCa pattern detection and staging.

Abstract 1051: Activation of PI3K pathway in breast cancer associates with tumor phospholipid fatty acid composition

Background

Ever since the discovery of the PI3K/Akt/mTOR pathway key role in breast cancer resistance, several molecules have been developed to target this pathway. However, mechanisms of resistance restrain their efficacy. An in-depth understanding of the interactions of PI3K pathway is essential to improve its blockade and avoid resistance. Preclinical studies reported that lipid composition of cancer cells altered the activation of PI3K pathway, thus suggesting another possible molecular interaction with lipid metabolism. The aim of this study was to analyze the relationship between the activation of PI3K pathway and tumor lipid composition in breast cancer patients.

Methods

Frozen and formalin-fixed paraffin-embedded tumor specimens were retrieved for 50 French patients with stage I to III primary breast cancer treated uniformly with surgery, adjuvant chemotherapy, radiation therapy and endocrine therapy. The tumor specimens were analyzed for PIK3CA gene mutation, PTEN protein expression by immunohistochemistry, and pAktS473, pAktT308, mTOR, pS6K, and S6RP by protein array. Tumor total fatty acid (FA) and phospholipid FA compositions were analysed using mass spectroscopy. Pearson test was used for correlation analyses.

Results

Mean age was 53 years. All tumors were ER or PR positive and HER-2 negative, and 76% were node positive. PI3K mutation was observed in 14% of cases, and 34% were PTEN negative or had low PTEN expression. Mean tumor satured fatty acid (SFA) level was 33.78 mol%, monounsaturated FA (MUFA) level was 46.46 mol%, n-6 polyunsaturated FA (PUFA) level was 18.08 mol%, and n-3 PUFA level was 1.68 mol%. Large and high grade tumors had a higher SFA content. MUFA rich tumors were frequently low grade. There was a positive correlation between d18:1/C20:0 ceramide level and Akt, mTOR and p70S6K expression. mTOR expression also correlated with 18:0 lysophosphatidylserine (lysoPS), 36:1 PS, 38:3 PS, 38:5 PS, 40:5 PS, 40:6 PS, 34:0 phosphatidylcholine (PC), 34:1 PC, and 38:3 PC.

Conclusions

Our results show that SFA associated with a more aggressive tumor phenotype and that PI3K pathway activation significantly correlated with fatty acid composition of specific tumor phospholipids. These results suggest a potential role of tumor lipid metabolism in PI3K pathway activation.

Citation Format: Nawale Hajjaji, Flavie Arbion, Alain Fautrel, Claire Villalva, Lucie Karayan-Tapon, Marie-Lise Jourdan. Activation of PI3K pathway in breast cancer associates with tumor phospholipid fatty acid composition. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1051.

Gene expression profiling of the tumor microenvironment in human intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of malignant primary tumors in the liver. ICC is an aggressive cancer with a poor survival and limited therapeutic options. At the histological level, ICC is characterized by an abundant stroma (i.e. the tumor microenvironment that notably includes components of the extracellular matrix, stromal cells and soluble factors). Tumor microenvironment is known to play a key role in tumor onset and progression but it is poorly characterized at the molecular level. Thus, this study was specifically designed to identify genes that are significantly deregulated in the tumor microenvironment of human ICC. Here we provide a detailed description of the experimental design and methods used to acquire the genomic data deposited into Gene Expression Omnibus (GEO) under the accession number GSE45001. Our genomic dataset provides insights on the molecular pathways altered in the microenvironment of ICC and allows the identification of novel ICC biomarkers, as exemplified previously in Hepatology (PMID: 23775819).

Mid-infrared fibre evanescent wave spectroscopy of serum allows fingerprinting of the hepatic metabolic status in mice

Infrared spectroscopy from mice unveils a transition in the time course of steatosis.

Transcriptomic Analysis of Trout Gill Ionocytes in Fresh Water and Sea Water Using Laser Capture Microdissection Combined with Microarray Analysis

Fish gills represent a complex organ composed of several cell types that perform multiple physiological functions. Among these cells, ionocytes are implicated in the maintenance of ion homeostasis. However, because the ionocyte represents only a small percent of whole gill tissue, its specific transcriptome can be overlooked among the numerous cell types included in the gill. The objective of this study is to better understand ionocyte functions by comparing the RNA expression of this cell type in freshwater and seawater acclimated rainbow trout. To realize this objective, ionocytes were captured from gill cryosections using laser capture microdissection after immunohistochemistry. Then, transcriptome analyses were performed on an Agilent trout oligonucleotide microarray. Gene expression analysis identified 108 unique annotated genes differentially expressed between freshwater and seawater ionocytes, with a fold change higher than 3. Most of these genes were up-regulated in freshwater cells. Interestingly, several genes implicated in ion transport, extracellular matrix and structural cellular proteins appeared up-regulated in freshwater ionocytes. Among them, several ion transporters, such as CIC2, SLC26A6, and NBC, were validated by qPCR and/or in situ hybridization. The latter technique allowed us to localize the transcripts of these ion transporters in only ionocytes and more particularly in the freshwater cells. Genes involved in metabolism and also several genes implicated in transcriptional regulation, cell signaling and the cell cycle were also enhanced in freshwater ionocytes. In conclusion, laser capture microdissection combined with microarray analysis allowed for the determination of the transcriptional signature of scarce cells in fish gills, such as ionocytes, and aided characterization of the transcriptome of these cells in freshwater and seawater acclimated trout.

Excessive dietary linoleic acid induces proinflammatory markers in rats

Following the historical dietary recommendations, the substitution of polyunsaturated fatty acids (PUFAs) for saturated fatty acids (SFAs) resulted in a dramatic increase of linoleic acid (LA) in the Western diet. While proatherogenic properties of SFAs have been described, the involvement of LA on the inflammatory process remains controversial. Herein, we evaluated the effects of an excessive LA intake on the cytokine-induced expression of endothelial adhesion molecules vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1), through the nuclear factor (NF)-κB pathway, in comparison with a control diet and regarding a "positive" SFA diet. Wistar rats were fed experimental diets - a control diet or diets enriched with LA or SFA - for 11 weeks. Plasma lipid parameters and proinflammatory cytokine production such as interleukin-1β and tumor necrosis factor (TNF)-α were analyzed. Expression of endothelial adhesion molecules and NF-κB was determined by immunohistochemical analysis. No difference was observed in body weight. The enriched diets did not affect triglyceride and total cholesterol levels in plasma. Our results demonstrated that excessive dietary LA intake increased TNF-α levels (P<.05) in plasma. Rats fed the LA-enriched diet showed a significantly higher expression of VCAM-1, ICAM-1 and NF-κB in aortas. In addition, our results demonstrated that an excess of LA is more efficient to activate endothelial molecular process than an excess of SFA. The present study provides further support for the proinflammatory properties of LA and suggests an LA-derivatives pathway involved in the inflammatory process.

Prostate whole-mount histology reconstruction and registration to MRI for correlating in-vivo observations with biological findings

Multi-parametric magnetic resonance imaging (mMRI) is the standard exam for prostate cancer diagnosis, staging and risk assessment in current clinical routine. Correlating mMRI in-vivo observations with biological findings from radical prostatectomy specimen would improve the optimal therapy selection. Thus, we proposed a method for reconstructing and registering the prostate whole-mount histology (WMH) to the MRI, considering a thin slicing of the prostatectomy specimen. The method was evaluated on 3 patients, included in a prospective study, for which hematein-eosinsafran and immunohistochemistry stainings were performed. The registration error was assessed by measuring the Euclidean distance between landmarks, previously identified by an expert on both mMRI and histological slices. The mean error was 4:90α1:34 mm. Our method demonstrated promising results for registering prostate WMH to in-vivo mMRI, thus allowing for spatial accurate correlation between radiologic observations and biological information.

Involvement of purinergic receptors and NOD-like receptor-family protein 3-inflammasome pathway in the adenosine triphosphate-induced cytokine release from macrophages

Adenosine triphosphate (ATP) has been described as a danger signal activating the NOD-like receptor-family protein 3 (NLRP3)-inflammasome leading to the pro-inflammatory cytokine, interleukin (IL)-1β, release in the lung. The NLRP3-inflammasome pathway has been previously described to be involved in experimental collagen deposition and the development of pulmonary fibrosis. The aim of the present study was to investigate the role of the NLRP3 inflammasome pathway and P2X7 purinergic receptor in the activation of human macrophages in vitro by ATP. We showed that adenosine 5'-[γ-thio]triphosphate tetralithium salt (ATPγS) and 2',3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP), two stable analogs of ATP, are able to potentiate the release of IL-1β from human monocyte-derived macrophages induced by low concentration of lipopolysaccharide (LPS). However, in the same conditions no increase in IL-1α and IL-6 was observed. Immunochemistry has shown that human macrophages natively express NLRP3 and purinergic P2X7 receptors (P2X7 R). NLRP3 and IL-1β mRNA expression were induced from LPS-primed macrophages, but also after 5-h treatment of BzATP as analysed by reverse transcription quantitative polymerase chain reaction. However, other inflammasome pathways (NLRP1, NLRP2, NLRC4, NLRP6 and AIM2) and P2X7 R were not induced by BzATP. We observed that P2X7 R antagonists, A-438079 and A-740003, were able to reduce the release of IL-1β, but not of IL-1α and IL-6 from macrophages stimulated by ATPγS or BzATP. The present results showed the involvement of the P2X7 R-NLRP3 inflammasome pathway in the secretion of IL-1β from ATP-stimulated human macrophages, and suggest that P2X7 R were not involved in IL-1α and IL-6 release. This study also points out that repression of the P2X7 R represents a novel potential therapeutic approach to control fibrosis in lung injury.

Comparative transcriptional profiling of human Merkel cells and Merkel cell carcinoma

Merkel cell carcinoma is believed to be derived from Merkel cells after infection by Merkel cell polyomavirus (MCPyV) and other poorly understood events. Transcriptional profiling using cDNA microarrays was performed on cells from MCPy-negative and MCPy-positive Merkel cell carcinomas and isolated normal Merkel cells. This microarray revealed numerous significantly upregulated genes and some downregulated genes. The extensive list of genes that were identified in these experiments provides a large body of potentially valuable information of Merkel cell carcinoma carcinogenesis and could represent a source of potential targets for cancer therapy.

Overexpression of MLN51 triggers P-body disassembly and formation of a new type of RNA granules

Metastatic lymph node 51 (MLN51, also known as CASC3) is a core component of the exon junction complex (EJC), which is loaded onto spliced mRNAs and plays an essential role in determining their fate. Unlike the three other EJC core components [eIF4AIII, Magoh and Y14 (also known as RBM8A)], MLN51 is mainly located in the cytoplasm, where it plays a key role in the assembly of stress granules. In this study, we further investigated the cytoplasmic role of MLN51. We show that MLN51 is a new component of processing bodies (P-bodies). When overexpressed, MLN51 localizes in novel small cytoplasmic foci. These contain RNA, show directed movements and are distinct from stress granules and P-bodies. The appearance of these foci correlates with the process of P-body disassembly. A similar reduction in P-body count is also observed in human HER2-positive (HER2(+)) breast cancer cells overexpressing MLN51. This suggests that P-body disassembly and subsequent mRNA deregulation might correlate with cancer progression.

Molecular profiling of stroma identifies osteopontin as an independent predictor of poor prognosis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of primary cancer in the liver. ICC is an aggressive cancer with poor prognosis and limited therapeutic strategies. The identification of new drug targets and prognostic biomarkers is an important clinical challenge for ICC. The presence of an abundant stroma is a histological hallmark of ICC. Given the well-established role of the stromal compartment in the progression of cancer diseases, we hypothesized that relevant biomarkers could be identified by analyzing the stroma of ICC. By combining laser capture microdissection and gene expression profiling, we demonstrate that ICC stromal cells exhibit dramatic genomic changes. We identified a signature of 1,073 nonredundant genes that significantly discriminate the tumor stroma from nontumor fibrous tissue. Functional analysis of differentially expressed genes demonstrated that up-regulated genes in the stroma of ICC were related to cell cycle, extracellular matrix, and transforming growth factor beta (TGFβ) pathways. Tissue microarray analysis using an independent cohort of 40 ICC patients validated at a protein level the increased expression of collagen 4A1/COL4A1, laminin gamma 2/LAMC2, osteopontin/SPP1, KIAA0101, and TGFβ2 genes in the stroma of ICC. Statistical analysis of clinical and pathological features demonstrated that the expression of osteopontin, TGFβ2, and laminin in the stroma of ICC was significantly correlated with overall patient survival. More important, multivariate analysis demonstrated that the stromal expression of osteopontin was an independent prognostic marker for overall and disease-free survival.

CONCLUSION

The study identifies clinically relevant genomic alterations in the stroma of ICC, including candidate biomarkers for prognosis, supporting the idea that tumor stroma is an important factor for ICC onset and progression.

Gene expression profiling of the hyperplastic growth zones of the late trout embryo myotome using laser capture microdissection and microarray analysis

Background

A unique feature of fish is that new muscle fibres continue to be produced throughout much of the life cycle; a process termed muscle hyperplasia. In trout, this process begins in the late embryo stage and occurs in both a discrete, continuous layer at the surface of the primary myotome (stratified hyperplasia) and between existing muscle fibres throughout the myotome (mosaic hyperplasia). In post-larval stages, muscle hyperplasia is only of the mosaic type and persists until 40% of the maximum body length is reached. To characterise the genetic basis of myotube neoformation in trout, we combined laser capture microdissection and microarray analysis to compare the transcriptome of hyperplastic regions of the late embryo myotome with that of adult myotomal muscle, which displays only limited hyperplasia.

Results

Gene expression was analysed using Agilent trout oligo microarrays. Our analysis identified more than 6800 transcripts that were significantly up-regulated in the superficial hyperplastic zones of the late embryonic myotome compared to adult myotomal muscle. In addition to Pax3, Pax7 and the fundamental myogenic basic helix-loop-helix regulators, we identified a large set of up-regulated transcriptional factors, including Myc paralogs, members of Hes family and many homeobox-containing transcriptional regulators. Other cell-autonomous regulators overexpressed in hyperplastic zones included a large set of cell surface proteins belonging to the Ig superfamily. Among the secreted molecules found to be overexpressed in hyperplastic areas, we noted growth factors as well as signalling molecules. A novel finding in our study is that many genes that regulate planar cell polarity (PCP) were overexpressed in superficial hyperplastic zones, suggesting that the PCP pathway is involved in the oriented elongation of the neofibres.

Conclusion

The results obtained in this study provide a valuable resource for further analysis of novel genes potentially involved in hyperplastic muscle growth in fish. Ultimately, this study could yield insights into particular genes, pathways or cellular processes that may stimulate muscle regeneration in other vertebrates.

Pentoxifylline aggravates fatty liver in obese and diabetic ob/ob mice by increasing intestinal glucose absorption and activating hepatic lipogenesis

BACKGROUND AND PURPOSE

Pentoxifylline is in clinical trials for non-alcoholic fatty liver disease and diabetic nephropathy. Metabolic and hepatic effects of pentoxifylline were assessed in a murine model of obesity and type 2 diabetes.

EXPERIMENTAL APPROACH

Pentoxifylline (100 mg·kg(-1) ·day(-1)) was administered for 4 days or 3 weeks in lean and obese/diabetic ob/ob mice. Plasma lipids, glucose, other metabolites and relevant enzymes were measured by standard assays. Hepatic lipids in vivo were assessed with magnetic resonance spectroscopy and by histology. Hepatic extracts were also analysed with RT-PCR and Western blotting.

KEY RESULTS

Four days of pentoxifylline treatment slightly increased liver lipids in ob/ob mice. After 3 weeks, pentoxifylline exacerbated fatty liver and plasma transaminases in ob/ob mice but did not induce liver steatosis in lean mice. Plasma glucose was highest in fed, but not fasted, ob/ob mice treated with pentoxifylline. During the first 10 min of an oral glucose tolerance test, blood glucose increased more rapidly in pentoxifylline-treated mice. Jejunal expression of glucose transporter 2 isoform was increased in pentoxifylline-treated obese mice. Hepatic activity of carbohydrate response element binding protein (ChREBP) increased after pentoxifylline in ob/ob, but not lean, mice. Hepatic expression of lipogenic enzymes was highest in pentoxifylline-treated ob/ob mice. However, pentoxifylline reduced markers of oxidative stress and inflammation in ob/ob liver.

CONCLUSION AND IMPLICATIONS

Pentoxifylline exacerbated fatty liver in ob/ob mice through enhanced intestinal glucose absorption, increased postprandial glycaemia and activation of hepatic lipogenesis. Long-term treatment with pentoxifylline could worsen fatty liver in some patients with pre-existing hyperglycaemia.

C-kit, B-raf, and N-ras mutations in melanoma subtypes

e19037

Background: The recent understanding of melanomas’ molecular pathways improved their classification and clinical strategies. Initial studies showed that B-Raf/N-Ras mutations (respectively V600E and Q61) are the most frequent alterations being present in 70 to 80% of melanomas, characterizing non Chronic Sun-induced Damage skins (CSD). These include Superficial Spreading Melanomas (SSM) and Nodular Melanomas (NM). Other studies showed that c-Kit mutations are present at low rate (20-40%) in Acro-Lentiginous Melanomas (ALM), Mucous Melanomas (MM) and in melanomas arising on CSD skins. C-kit mutation pattern is complex with four exons being affected leading to numerous mutations. Because c-Kit targeted therapy is a critical clinical issue, we aimed to identify the most frequent mutations to propose appropriate screening test and adapted therapy. Methods: 186 melanoma samples corresponding to an homogeneous white-caucasian population (Brittany, France) were screened. c-Kit exons 11, 13,17 and 18 were sequenced, c-Kit copy number was quantified by q-PCR and level of c-Kit determined by immunohistochemistry (CD117). Samples were also analyzed for B-Raf mutations (codon 464, 466, 469, 600) and for N-Ras mutations (codon 12, 13, 61) by pyrosequencing. Results: Detectedmutations are shown in the table. Uveal melanomas (n=13) were never mutated. These mutations were never overlaped and comparable profiles were obtained between the primary tumour, nodes or metastatic lesions from a same patient. Conclusions: C-Kit mutations are much less common than in other previously described populations especially for MM or ALM. B-Raf/N-Ras mutations appeared also less frequent than waited in non-CSD , reaching 46% in SSM. Interestingly our population presents a high incidence of N-Ras mutations, especially in SSM and NM. Screening of B-Raf/N-Ras mutations is fundamental not only for SSM but also for NM, CSD and ALM for prescribing targeted therapies such as MEK-inhibitors. [Table: see text]

Carbon tetrachloride-mediated lipid peroxidation induces early mitochondrial alterations in mouse liver

Although carbon tetrachloride (CCl(4))-induced acute and chronic hepatotoxicity have been extensively studied, little is known about the very early in vivo effects of this organic solvent on oxidative stress and mitochondrial function. In this study, mice were treated with CCl(4) (1.5 ml/kg ie 2.38 g/kg) and parameters related to liver damage, lipid peroxidation, stress/defense and mitochondria were studied 3 h later. Some CCl(4)-intoxicated mice were also pretreated with the cytochrome P450 2E1 inhibitor diethyldithiocarbamate or the antioxidants Trolox C and dehydroepiandrosterone. CCl(4) induced a moderate elevation of aminotransferases, swelling of centrilobular hepatocytes, lipid peroxidation, reduction of cytochrome P4502E1 mRNA levels and a massive increase in mRNA expression of heme oxygenase-1 and heat shock protein 70. Moreover, CCl(4) intoxication induced a severe decrease of mitochondrial respiratory chain complex IV activity, mitochondrial DNA depletion and damage as well as ultrastructural alterations. Whereas DDTC totally or partially prevented all these hepatic toxic events, both antioxidants protected only against liver lipid peroxidation and mitochondrial damage. Taken together, our results suggest that lipid peroxidation is primarily implicated in CCl(4)-induced early mitochondrial injury. However, lipid peroxidation-independent mechanisms seem to be involved in CCl(4)-induced early hepatocyte swelling and changes in expression of stress/defense-related genes. Antioxidant therapy may not be an efficient strategy to block early liver damage after CCl(4) intoxication.

Overexpression of active Aurora-C kinase results in cell transformation and tumour formation

Aurora kinases belong to a conserved family of serine/threonine kinases key regulators of cell cycle progression. Aurora-A and Aurora-B are expressed in somatic cells and involved mainly in mitosis while Aurora-C is expressed during spermatogenesis and oogenesis and is involved in meiosis. Aurora-C is hardly detectable in normal somatic cells. However all three kinases are overexpressed in many cancer lines. Aurora-A possesses an oncogenic activity while Aurora-B does not. Here we investigated whether Aurora-C possesses such an oncogenic activity. We report that overexpression of Aurora-C induces abnormal cell division resulting in centrosome amplification and multinucleation in both transiently transfected cells and in stable cell lines. Only stable NIH3T3 cell clones overexpressing active Aurora-C formed foci of colonies when grown on soft agar, indicating that a gain of Aurora-C activity is sufficient to transform cells. Furthermore, we reported that NIH-3T3 stable cell lines overexpressing Aurora-C induced tumour formation when injected into nude mice, demonstrating the oncogenic activity of enzymatically active Aurora kinase C. Interestingly enough tumor aggressiveness was positively correlated with the quantity of active kinase, making Aurora-C a potential anti-cancer therapeutic target.

IL-1 and IL-23 mediate early IL-17A production in pulmonary inflammation leading to late fibrosis

Background

Idiopathic pulmonary fibrosis is a devastating as yet untreatable disease. We demonstrated recently the predominant role of the NLRP3 inflammasome activation and IL-1β expression in the establishment of pulmonary inflammation and fibrosis in mice.

Methods

The contribution of IL-23 or IL-17 in pulmonary inflammation and fibrosis was assessed using the bleomycin model in deficient mice.

Results

We show that bleomycin or IL-1β-induced lung injury leads to increased expression of early IL-23p19, and IL-17A or IL-17F expression. Early IL-23p19 and IL-17A, but not IL-17F, and IL-17RA signaling are required for inflammatory response to BLM as shown with gene deficient mice or mice treated with neutralizing antibodies. Using FACS analysis, we show a very early IL-17A and IL-17F expression by RORγt⁺ γδ T cells and to a lesser extent by CD4αβ⁺ T cells, but not by iNKT cells, 24 hrs after BLM administration. Moreover, IL-23p19 and IL-17A expressions or IL-17RA signaling are necessary to pulmonary TGF-β1 production, collagen deposition and evolution to fibrosis.

Conclusions

Our findings demonstrate the existence of an early IL-1β-IL-23-IL-17A axis leading to pulmonary inflammation and fibrosis and identify innate IL-23 and IL-17A as interesting drug targets for IL-1β driven lung pathology.

Merkel cell polyomavirus small T antigen mRNA level is increased following in vivo UV-radiation

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer involving Merkel cells. Recently, a new human polyomavirus was implicated in MCC, being present in 80% of the samples analyzed. In virus-positive MCC, the Merkel cell polyomavirus (MCPyV) is clonally integrated into the patients DNA, and carries mutations in its large T antigen, leading to a truncated protein. In non-symptomatic tissue MCPyV can reside at very low levels. MCC is also associated with older age, immunosuppression and sun exposure. However, the link with solar exposure remains unknown, as the precise mechanism and steps involved between time of infection by MCPyV and the development of MCC. We thus investigated the potential impact of solar simulated radiation (SSR) on MCPyV transcriptional activity. We screened skin samples of 20 healthy patients enrolled in a photodermatological protocol based on in vivo-administered 2 and 4 J/cm(2) SSR. Two patients were infected with two new variants of MCPyV, present in their episomal form and RT-QPCR analyses on SSR-irradiated skin samples showed a specific and unique dose-dependent increase of MCPyV small t antigen transcript. A luciferase based in vitro assay confirmed that small t promoter is indeed UV-inducible. These findings demonstrate that solar radiation has an impact on MCPyV mRNA levels that may explain the association between MCC and solar exposure.

Brassica orthologs from BANYULS belong to a small multigene family, which is involved in procyanidin accumulation in the seed

As part of a research programme focused on flavonoid biosynthesis in the seed coat of Brassica napus L. (oilseed rape), orthologs of the BANYULS gene that encoded anthocyanidin reductase were cloned in B. napus as well as in the related species Brassica rapa and Brassica oleracea. B. napus genome contained four functional copies of BAN, two originating from each diploid progenitor. Amino acid sequences were highly conserved between the Brassicaceae including B. napus, B. rapa, B. oleracea as well as the model plant Arabidopsis thaliana. Along the 200 bp in 5' of the ATG codon, Bna.BAN promoters (ProBna.BAN) were conserved with AtANR promoter and contained putative cis-acting elements. In addition, transgenic Arabidopsis and oilseed rape plants carrying the first 230 bp of ProBna.BAN fused to the UidA reporter gene were generated. In the two Brassicaceae backgrounds, ProBna.BAN activity was restricted to the seed coat. In B. napus seed, ProBna.BAN was activated in procyanidin-accumulating cells, namely the innermost layer of the inner integument and the micropyle-chalaza area. At the transcriptional level, the four Bna.BAN genes were expressed in the seed. Laser microdissection assays of the seed integuments showed that Bna.BAN expression was restricted to the inner integument, which was consistent with the activation profile of ProBna.BAN. Finally, Bna.BAN genes were mapped onto oilseed rape genetic maps and potential co-localisations with seed colour quantitative trait loci are discussed.

Chronic ethanol consumption lessens the gain of body weight, liver triglycerides, and diabetes in obese ob/ob mice

Clinical studies suggest that moderate alcohol consumption can have beneficial effects, in particular regarding cardiovascular events, insulin resistance, and type 2 diabetes. In this study, lean and obese diabetic ob/ob mice were submitted or not to chronic ethanol intake via the drinking water for 6 months, which was associated with moderate levels of plasma ethanol. Plasma levels of alanine aminotransferase and aspartate aminotransferase were not increased by alcohol intake. Ethanol consumption progressively reduced the gain of body weight in ob/ob mice, but not in lean mice, and this was observed despite higher calorie intake. Increased plasma free fatty acids and glycerol in ethanol-treated ob/ob mice suggested peripheral lipolysis. Glycemia and insulinemia were significantly reduced, whereas adiponectinemia was increased in ethanol-treated ob/ob mice. Liver weight and triglycerides were significantly decreased in ethanol-treated ob/ob mice, and this was associated with less microvesicular steatosis. Hepatic levels of AMP-activated protein kinase and the phosphorylated form of acetyl-CoA carboxylase were higher in ethanol-treated ob/ob mice, suggesting better fatty acid oxidation. However, hepatic mRNA expression of several lipogenic genes was not reduced by ethanol consumption. Finally, mild oxidative stress was noticed in the liver of ethanol-treated mice, regardless of their genotype. Hence, our data are in keeping with clinical studies suggesting that moderate ethanol intake can have beneficial effects on type 2 diabetes and insulin sensitivity, at least in part through increased levels of plasma adiponectin. However, further studies are needed to determine whether long-term drinking of light-to-moderate amounts of ethanol is safe for the liver.

Ectopic germinal centers are rare in Sjogren's syndrome salivary glands and do not exclude autoreactive B cells

This study reports on the characterization of B cells of germinal center (GC)-like structures infiltrating the salivary glands (SGs) of patients with Sjögren's syndrome. Eight two-color combinations were devised to characterize the phenotype of these B cells in 11 SG specimens selected from biopsies obtained from 40 Sjögren's syndrome patients and three normal tonsils. The 9G4 mAb, which recognizes V4.34-encoded autoAbs, enabled us to identify autoreactive B cells. Quantitative RT-PCR was used to determine the level of mRNAs for activation-induced cytidine deaminase (AICDA), repressors and transcription factors. CD20(+)IgD(-)CD38(+)CD21(+)CD24(-) B cells, similar to those identified in tonsil GCs, were seen in the SGs of four patients and, and since they expressed AICDA, they were termed "real GCs". CD20(+)IgD(+)CD38(-)CD21(+)CD24(+) B cells, seen in aggregates from the remaining seven samples, were characteristically type 2 transitional B cells and marginal zone-type B cells. They lacked AICDA mRNAs and were termed "aggregates". Real GCs from SGs contained mRNAs for Pax-5 and Bcl-6, like tonsil GC cells, whereas aggregates contained mRNAs for Notch-2, Blimp-1, IRF-4, and BR3, similar to marginal zone B cells. Further experimental data in support of this dichotomy included the restriction of CXCR5 expression to real GC cells, while sphingosine 1-phosphate receptor 1 was expressed only in aggregates. In contrast, both types of B cell clusters expressed the idiotype recognized by the 9G4 mAb. Our data indicate that, in SGs, a minority of B cell clusters represent genuine GC cells, while the majority manifest features of being type 2 transitional B cells and marginal zone cells. Interestingly, both types of B cell aggregates include autoreactive B cells.

RNAi-mediated ERK2 knockdown inhibits growth of tumor cells in vitro and in vivo

The MAPK MEK/ERK pathway is often upregulated in cancer cells and represents an attractive target for development of anticancer drugs. Only few data concerning the specific functions of ERK1 and 2 are reported in the literature. In this report, we investigated the specific role of ERK1 and 2 in liver tumor growth both in vitro and in vivo. DNA synthesis and cells in S phase analysed by flow cytometry, correlated with strong inhibition of Cdk1 and cyclin E levels, are strongly reduced after exposure to the MEK inhibitor, U0126. We obtained a significant reduction of colony formation in soft agar assays and a reduction in the size of tumor xenografts in nude mice treated with U0126. Then, we could specifically abolished ERK1 or 2 expression by small-interfering RNA (siRNA) and demonstrated that ERK2 knockdown but not ERK1 interferes with the process of replication. Moreover, we found that colony formation and tumor growth in vivo were significantly inhibited by targeting ERK2 using stable chemically modified siRNA. Taken together, our results emphasize the importance of the MEK/ERK pathway in liver cancer cell growth in vitro and in vivo and argue for a crucial role of ERK2 in this regulation.

Transcripts of ceruloplasmin but not hepcidin, both major iron metabolism genes, exhibit a decreasing pattern along the portocentral axis of mouse liver

BACKGROUND/AIMS

During iron overload of dietary origin, iron accumulates predominantly in periportal hepatocytes. A gradient in the basal and normal transcriptional control of genes involved in iron metabolism along the portocentral axis of liver lobules could explain this feature. Therefore, we aimed at characterizing, by quantitative RT-PCR, the expression of iron metabolism genes in adult C57BL/6 mouse hepatocytes regarding lobular localisation, with special emphasis to cell ploidy, considering its possible relationship with lobular zonation.

METHODS

We used two methods to analyse separately periportal and perivenous liver cells: 1) a selective liver zonal destruction by digitonin prior to a classical collagenase dissociation, and 2) laser capture microdissection. We also developed a method to separate viable 4N and 8N polyploid hepatocytes by flow cytometer.

RESULTS

Transcripts of ceruloplasmin, involved in iron efflux, were overexpressed in periportal areas and the result was confirmed by in situ hybridization study. By contrast, hepcidin 1, hemojuvelin, ferroportin, transferrin receptor 2, hfe and L-ferritin mRNAs were not differentially expressed according to either lobular zonation or polyploidisation level.

CONCLUSIONS

At variance with glutamine or urea metabolism, iron metabolism is not featured by a metabolic zonation lying only on a basal transcriptional control. The preferential periportal expression of ceruloplasmin raises the issue of its special role in iron overload disorders involving a defect in cellular iron export.

GATA-1 is essential in EGF-mediated induction of nucleotide excision repair activity and ERCC1 expression through ERK2 in human hepatoma cells

The nucleotide excision repair (NER) pathway and its leading gene excision-repair cross-complementary 1 (ERCC1) have been shown to be up-regulated in hepatocellular carcinomas even in the absence of treatment with chemotherapeutics. The aim of this study was to determine the mechanism involved in NER regulation during the liver cell growth observed in hepatocellular carcinoma. Both NER activity and ERCC1 expression were increased after exposure to the epidermal growth factor (EGF) in cultured normal and tumoral human hepatocytes. These increases correlated with the activation of the kinase signaling pathway mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK that is known to be a key regulator in the G(1) phase of the hepatocyte cell cycle. Moreover, EGF-mediated activation of ERCC1 was specifically inhibited by either the addition of U0126, a MEK/ERK inhibitor or small interfering RNA-mediated knockdown of ERK2. Basal expression of ERCC1 was decreased in the presence of the phosphoinositide-3-kinase (PI3K) inhibitor and small hairpin RNA (shRNA) against the PI3K pathway kinase FKBP12-rapamycin-associated protein or mammalian target of rapamycin. Transient transfection of human hepatocytes with constructs containing different sizes of the 5'-flanking region of the ERCC1 gene upstream of the luciferase reporter gene showed an increase in luciferase activity in EGF-treated cells, which correlated with the presence of the nuclear transcription factor GATA-1 recognition sequence. The recruitment of GATA-1 was confirmed by chromatin immunoprecipitation assay. In conclusion, these results represent the first demonstration of an up-regulation of NER and ERCC1 in EGF-stimulated proliferating hepatocytes. The transcription factor GATA-1 plays an essential role in the induction of ERCC1 through the mitogen-activated protein kinase (MAPK) pathway, whereas the PI3K signaling pathway contributes to ERCC1 basal expression.

Overexpression of the two nucleotide excision repair genes ERCC1 and XPC in human hepatocellular carcinoma

BACKGROUND/AIMS

Little is known about the nucleotide excision repair (NER) pathway in the resistance of human hepatocellular carcinoma (HCC) to chemotherapeutics. We investigated expression of several NER genes in human HCC and matching non-tumor tissue (NT) and in normal liver.

METHODS

Expression of CSA, CSB, XPC, hHR23B, XPA, XPB, ERCC1 and p53 genes was analyzed by quantitative RT-PCR and immunoblotting in 26 HCC and 9 normal livers.

RESULTS

The seven NER genes and p53 were frequently overexpressed in HCC compared to matched NT. XPA, XPC, hHR23B and ERCC1 mRNA levels were significantly increased (p<0.05) in HCC arising in cirrhotic livers compared to non fibrotic tissue. Moreover, expression of ERCC1, XPA and XPC mRNA was significantly augmented in HCC, even more in tumors arising in cirrhotic liver. ERCC1, XPC ad XPA mRNA levels were highly correlated in NT and HCC. XPC and ERCC1 protein levels were also increased in HCC.

CONCLUSIONS

Our findings strongly suggest that overexpression of two key genes involved in the early steps of the NER process, ERCC1 and XPC, is associated with liver fibrogenesis and cancer and could be related to the well recognized resistance of HCC to chemotherapeutics.

Behavioral and neurochemical effects induced by subchronic combined exposure to toluene at 40 ppm and noise at 80 dB-A in rats

We investigated whether exposure to noise, in addition to its well-known potentiating effect on toluene-induced ototoxicity, may also exacerbate behavioral disturbances and brain neurochemical alterations produced by subchronic exposure to low toluene concentration. To test this hypothesis, we evaluated whether subchronic combined exposure (16 weeks, 104 h per week) to noise at 80 dB-A and toluene at 40 ppm potentiates the recently reported neurotoxic effects of subchronic exposure to 40 ppm toluene. Locomotor and rearing activities, sensitization to narcosis induced by acute toluene at high concentration, and tyrosine and tryptophan hydroxylase activities in the caudate-putamen and hippocampus were investigated in both male and female rats. Our results confirm that subchronic exposure to 40 ppm toluene significantly decreases rearing activity and leads to a sensitization to toluene-induced narcosis, as evaluated by loss of righting reflex, but fails to demonstrate any adverse effect of noise, alone or in combination with toluene. Given that toluene has addictive properties, the lack of potentiating behavioral and neurochemical effect of noise is discussed with regards to a recent study that has shown that methamphetamine neurotoxicity is potentiated by exposure to loud noise.

Aryl hydrocarbon receptor activation and cytochrome P450 1A induction by the mitogen-activated protein kinase inhibitor U0126 in hepatocytes

The aryl hydrocarbon receptor (AhR) is involved in various processes such as cytochrome P450 (P450) 1A induction after xenobiotic exposure. It is also considered to play a major role in cell proliferation and differentiation. Recent evidences have suggested a cross-talk between AhR functions and the mitogen-activated protein kinase (MAPK) cascade. We now report that 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126), a specific inhibitor of MAPK kinase (MEK) MEK1/2, elicits a marked increase in CYP1A1 expression at both mRNA and protein levels associated with a significant increase of enzyme activity in primary rat hepatocytes and a human hepatoma cell line. This induction occurred independently of MEK/extracellular signal-regulated kinase (ERK) activation and in the absence of ERK1 and ERK2 expression. The effect of U0126 was mediated by its ability to transactivate xenobiotic responsive element (XRE)-driven genes, as demonstrated by transfection assays with an XRE-driven luciferase construct in the human B16A2 hepatoma cell line. CYP1A1 modulation was abolished by a cotreatment with resveratrol, an established AhR antagonist, arguing for AhR activation by U0126. Such an effect was demonstrated by direct in vitro ligand binding competition assays using rabbit liver cytosol, showing that this compound binds AhR with an EC(50) = 25 x 10(-6) M. Moreover, we demonstrated that U0126 is a substrate for several P450s including human CYP1A2, -1A1, and -1B1. We conclude that the widely used specific inhibitor of MEK/ERK, U0126, also acts as a potent AhR activator and an inducer of related genes. Such effects on the AhR may have an impact on biological functions attributed previously to MAPK inhibition.