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DhmR and gene expression related to Fig1

DhmR and gene expression tet-/- related to Fig3

Although numerous epigenetic aberrancies accumulate in melanoma, their contribution to initiation and progression remain unclear. The epigenetic mark 5-hydroxymethylcytosine (5hmC), generated through TET-mediated DNA modification, is now referred to as the sixth base of DNA and has recently been reported as a potential biomarker for multiple types of cancer. Loss of 5hmC is an epigenetic hallmark of melanoma, but whether a decrease in 5hmc levels contributes directly to pathogenesis or whether it merely results from disease progression–associated epigenetic remodeling remains to be established. Here, we show that NRAS-driven melanomagenesis in mice is accompanied by an overall decrease in 5hmC and specific 5hmC gains in selected gene bodies. Strikingly, genetic ablation of Tet2 in mice cooperated with oncogenic NRASQ61K to promote melanoma initiation while suppressing specific gains in 5hmC. We conclude that TET2 acts as a barrier to melanoma initiation and progression, partly by promoting 5hmC gains in specific gene bodies.Significance:This work emphasizes the importance of epigenome plasticity in cancer development and highlights the involvement of druggable epigenetic factors in cancer.

Histological examination of samples, mC measurement by Mass Spec, survival curves showing the effect of p16Ink4 deletion, qPCR of hmC-related enzymes and melanoma related genes, hmedIP-pcr confirmation of hmedIP-seq, list of primers

SummaryAlthough tremendous progress has been made in understanding the mechanisms leading to cancer, those governing metastases are still poorly understood. E-cadherin (Ecad) is a cell-cell adhesion molecule essential for tissue homeostasis, and its loss often correlates with the dissemination of human cancers. However, whether and how the loss of Ecad triggers the full metastatic program is largely unknown. Here, we show that the loss of Ecad promotes melanoma lung metastases in females. The loss of Ecad, after the induction of estrogen receptor α (ERα) expression, activates gastrin-releasing peptide receptor (GRPR) expression. GRPR promotes cellular processes essential for metastasis formation through G□qand YAP1 signaling and its pharmacological inhibition reduces metastasisin vivo. This study reveals an Ecad-ERα-GRPR metastatic sex dimorphism axis in melanoma that is conserved in human breast cancer and provides proof of concept that the G-coupled receptor GRPR is a therapeutic target for metastasis.

While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, in a BrafV600E PtenF/+ context, we show that BRN2 haplo-insufficiency promotes melanoma initiation and metastasis. However, metastatic colonization is less efficient in the absence of Brn2. Mechanistically, BRN2 directly induces PTEN expression and in consequence represses PI3K signaling. Moreover, MITF, a BRN2 target, represses PTEN transcription. Collectively, our results suggest that on a PTEN heterozygous background somatic deletion of one BRN2 allele and temporal regulation of the other allele elicits melanoma initiation and progression., The transcription factor BRN2 regulates melanoma migration and invasion, but its role during melanoma initiation is unclear. Here the authors show that BRN2 is a haplo-insufficient tumour suppressor that positively regulates PTEN expression and in the context of BRAF mutation and heterozygous PTEN, BRN2 loss promotes melanoma initiation and progression.

The canonical Wnt/β-catenin pathway governs a multitude of developmental processes in various cell lineages, including the melanocyte lineage. Indeed, β-catenin regulates transcription of Mitf-M, the master regulator of this lineage. The first wave of melanocytes to colonize the skin is directly derived from neural crest cells, whereas the second wave of melanocytes is derived from Schwann cell precursors (SCPs). We investigated the influence of β-catenin in the development of melanocytes of the first and second waves by generating mice expressing a constitutively active form of β-catenin in cells expressing tyrosinase. Constitutive activation of β-catenin did not affect the development of truncal melanoblasts but led to marked hyperpigmentation of the paws. By activating β-catenin at various stages of development (E8.5-E11.5), we showed that the activation of β-catenin in bipotent SCPs favored melanoblast specification at the expense of Schwann cells in the limbs within a specific temporal window. Furthermore, in vitro hyperactivation of the Wnt/β-catenin pathway, which is required for melanocyte development, induces activation of Mitf-M, in turn repressing FoxD3 expression. In conclusion, β-catenin overexpression promotes SCP cell fate decisions towards the melanocyte lineage.

Melanoblast migration is important for embryogenesis and is a key feature of melanoma metastasis. Many studies have characterized melanoblast movement, focusing on statistical properties and have highlighted basic mechanisms of melanoblast motility. We took a slightly different and complementary approach: we previously developed a mathematical model of melanoblast motion that enables the testing of biological assumptions about the displacement of melanoblasts and we created tests to analyze the geometric features of cell trajectories and the specific issue of trajectory interactions. Within this model, we performed simulations and compared the results with experimental data using geometric tests. In this paper, we developed the associated mathematical model and the main focus is to study the crossings between trajectories with new theoretical results about the variation of number of intersection points with respect to the crossing times. Using these results it is possible to study the random nature of displacements and the interactions between trajectories. This analysis has raised new questions, leading to the generation of strong arguments in favor of a trail left behind each moving melanoblast.

While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, we show that BRN2 haplo-insufficiency is sufficient to promote melanoma initiation and metastasis, acting as a non-canonical tumor suppressor. Mechanistically, BRN2 directly modulates PTEN expression, and PI3K signaling, to drive tumor initiation and progression. Collectively our results reveal that somatic deletion of one BRN2 allele elicits melanoma initiation and progression.SIGNIFICANCEHere, we report frequent mono-allelic loss of the transcription factor BRN2 in human cutaneous melanoma metastases. We developed a mouse model for Brn2-deficient melanoma based on the most common alterations (BrafV600E and Pten loss) in human melanoma and established the role of Brn2 as a functional regulator of tumor initiation, tumor growth, and the formation of metastases in vivo. Mechanistically, BRN2 loss increases PI3K-signaling through PTEN repression, either via MITF induction or not. Overall, we describe a novel tumor suppressor of high prevalence in human melanoma that regulates several steps of in vivo melanomagenesis through two previously unknown molecular mechanisms.

Simple Summary Targeted radionuclide therapy (TRT) aims to selectively deliver radioactive molecules to tumor cells. For this purpose, we deliver iodine-131 ([131I]) to melanoma cells by using our laboratory-developed melanin specific radiotracer, the ICF01012. Approximately 50% and 20%–30% of human melanomas have activating mutation in BRAF or NRAS genes, respectively. These mutations lead to a constitutive activation of the MAPK/ERK pathway, which is known to be involved in tumor cells’ radioresistance. In this work, we showed using 3D in vitro tumor models, an additive efficiency of combining [131I]ICF01012-TRT and MAPK/ERK inhibitors in BRAF- and NRAS-mutant melanoma cells. In mice bearing NRASQ61K-mutated melanoma, TRT induced an impressive decrease in tumor growth, as well as a highly extended survival. Additionally, we showed that TRT reduces the metastatic capacity of melanoma, especially through lymph-node dissemination. These results are therefore of great interest, especially for patients with NRAS-mutant metastatic melanoma who currently lack specific efficient therapies. Abstract Purpose: To assess the efficiency of targeted radionuclide therapy (TRT), alone or in combination with MEK inhibitors (MEKi), in melanomas harboring constitutive MAPK/ERK activation responsible for tumor radioresistance. Methods: For TRT, we used a melanin radiotracer ([131I]ICF01012) currently in phase 1 clinical trial (NCT03784625). TRT alone or combined with MEKi was evaluated in three-dimensional melanoma spheroid models of human BRAFV600E SK-MEL-3, murine NRASQ61K 1007, and WT B16F10 melanomas. TRT in vivo biodistribution, dosimetry, efficiency, and molecular mechanisms were studied using the C57BL/6J-NRASQ61K 1007 syngeneic model. Results: TRT cooperated with MEKi to increase apoptosis in both BRAF- and NRAS-mutant spheroids. NRASQ61K spheroids were highly radiosensitive towards [131I]ICF01012-TRT. In mice bearing NRASQ61K 1007 melanoma, [131I]ICF01012 induced a significant extended survival (92 vs. 44 days, p < 0.0001), associated with a 93-Gy tumor deposit, and reduced lymph-node metastases. Comparative transcriptomic analyses confirmed a decrease in mitosis, proliferation, and metastasis signatures in TRT-treated vs. control tumors and suggest that TRT acts through an increase in oxidation and inflammation and P53 activation. Conclusion: Our data suggest that [131I]ICF01012-TRT and MEKi combination could be of benefit for advanced pigmented BRAF-mutant melanoma care and that [131I]ICF01012 alone could constitute a new potential NRAS-mutant melanoma treatment.

The canonical Wnt/β-catenin pathway governs a multitude of developmental processes in various cell lineages, including the melanocyte lineage. Indeed, β-catenin regulatesMitf-Mtranscription, the master regulator of this lineage. The first wave of melanocytes to colonize the skin is directly derived from neural crest cells, while a small number of second wave melanocytes is derived from Schwann-cell precursors (SCPs). We investigated the influence of β-catenin in the development of melanocytes of the first and second waves by generating mice expressing a constitutively active form of β-catenin in cells expressing tyrosinase. Constitutive activation of β-catenin did not affect the development of truncal melanoblasts, but led to a marked hyperpigmentation of the paws. By activating β-catenin at various stages of development (E8.5-E11.5), we showed that the activation of β-catenin in bipotent SCPs favored melanoblast specification at the expense of Schwann cells in the limbs within a specific temporal window. In addition, hyperactivation of the Wnt/β-catenin pathway repressedFoxD3expression, which is necessary for Schwann cell development, throughMitf-Mactivation. In conclusion, β-catenin overexpression promotes SCP cell-fate decisions towards the melanocyte lineage.Summary statementActivation of β-catenin in bipotent Schwann-cell precursors during a specific developmental window, induces MITF and represses FoxD3 to promote melanoblast cell fate at the expense of Schwann cells in limbs.

The potential role of CLEC12B, a gene predominantly expressed by skin melanocytes discovered through transcriptomic analysis, in melanoma is unknown. In this study, we show that CLEC12B expression is lower in melanoma and melanoma metastases than in melanocytes and benign melanocytic lesions and that its decrease correlates with poor prognosis. We further show that CLEC12B recruits SHP2 phosphatase through its immunoreceptor tyrosine-based inhibition motif domain, inactivates signal transducer and activator of transcription 1/3/5, increases p53/p21/p27 expression/activity, and modulates melanoma cell proliferation. The growth of human melanoma cells overexpressing CLEC12B in nude mice after subcutaneous injection is significantly decreased compared with that in the vehicle control group and is associated with decreased signal transducer and activator of transcription 3 phosphorylation and increased p53 levels in the tumors. Reducing the level of CLEC12B had the opposite effect. We show that CLEC12B represses the activation of the signal transducer and activator of transcription pathway and negatively regulates the cell cycle, providing a proliferative asset to melanoma cells.

International audience; RAS is frequently mutated in various tumors and known to be difficult to target. NRASQ61K/R are the second most frequent mutations found in human skin melanoma after BRAFV600E . Aside from surgery, various approaches, including targeted therapies, immunotherapies, and combination therapies, are used to treat patients carrying NRAS mutations, but they are inefficient. Here, we established mouse NRASQ61K melanoma cell lines and genetically derived isografts (GDIs) from Tyr::NRASQ61K mouse melanoma that can be used in vitro and in vivo in an immune-competent environment (C57BL/6) to test and discover novel therapies. We characterized these cell lines at the cellular, molecular, and oncogenic levels and show that NRASQ61K melanoma is highly sensitive to the combination of Mek and Akt inhibitors. This preclinical model shows much potential for the screening of novel therapeutic strategies for patients harboring NRAS mutations that have limited therapeutic options and resulted in poor prognoses.

RAS is frequently mutated in various tumors and known to be difficult to target. NRAS

Melanocytes arise from the fourth embryonic layer, the neural crest. They emerge from the roof plate of the neural tube and migrate throughout the body. In mammals, these cells have the capacity to migrate in any type of environment and use various pathways and mechanisms to colonize the skin and hair, and for their maintenance throughout the life of the animal.

To distribute and establish the melanocyte lineage throughout the skin and other developing organs, melanoblasts undergo several rounds of proliferation, accompanied by migration through complex environments and differentiation. Melanoblast migration requires interaction with extracellular matrix of the epidermal basement membrane and with surrounding keratinocytes in the developing skin. Migration has been characterized by measuring speed, trajectory and directionality of movement, but there are many unanswered questions about what motivates and defines melanoblast migration. Here, we have established a general mathematical model to simulate the movement of melanoblasts in the epidermis based on biological data, assumptions and hypotheses. Comparisons between experimental data and computer simulations reinforce some biological assumptions, and suggest new ideas for how melanoblasts and keratinocytes might influence each other during development. For example, it appears that melanoblasts instruct each other to allow a homogeneous distribution in the tissue and that keratinocytes may attract melanoblasts until one is stably attached to them. Our model reveals new features of how melanoblasts move and, in particular, suggest that melanoblasts leave a repulsive trail behind them as they move through the skin., Summary: A mathematical model to simulate melanoblast distribution in the embryonic mouse epidermis, based on keratinocyte attraction, melanoblast repulsion and melanoblast memory of their previous path.

Although numerous epigenetic aberrancies accumulate in melanoma, their contribution to initiation and progression remain unclear. The epigenetic mark 5-hydroxymethylcyto-sine (5hmC), generated through TET-mediated DNA modification, is now referred to as the sixth base of DNA and has recently been reported as a potential biomarker for multiple types of cancer. Loss of 5hmC is an epigenetic hallmark of melanoma, but whether a decrease in 5hmc levels contributes directly to pathogenesis or whether it merely results from disease progression-associated epigenetic remodeling remains to be established. Here, we show that NRAS-driven melanomagenesis in mice is accompanied by an overall decrease in 5hmC and specific 5hmC gains in selected gene bodies. Strikingly, genetic ablation of Tet2 in mice cooperated with oncogenic NRASQ61K to promote melanoma initiation while suppressing specific gains in 5hmC. We conclude that TET2 acts as a barrier to melanoma initiation and progression, partly by promoting 5hmC gains in specific gene bodies. Significance: This work emphasizes the importance of epigenome plasticity in cancer development and highlights the involvement of druggable epigenetic factors in cancer., SCOPUS: ar.j, info:eu-repo/semantics/published

Vitiligo is the most common depigmenting disorder resulting from the loss of melanocytes from the basal epidermal layer. The pathogenesis of the disease is likely multifactorial and involves autoimmune causes, as well as oxidative and mechanical stress. It is important to identify early events in vitiligo to clarify pathogenesis, improve diagnosis, and inform therapy. Here, we show that E-cadherin (Ecad), which mediates the adhesion between melanocytes and keratinocytes in the epidermis, is absent from or discontinuously distributed across melanocyte membranes of vitiligo patients long before clinical lesions appear. This abnormality is associated with the detachment of the melanocytes from the basal to the suprabasal layers in the epidermis. Using human epidermal reconstructed skin and mouse models with normal or defective Ecad expression in melanocytes, we demonstrated that Ecad is required for melanocyte adhesiveness to the basal layer under oxidative and mechanical stress, establishing a link between silent/preclinical, cell-autonomous defects in vitiligo melanocytes and known environmental stressors accelerating disease expression. Our results implicate a primary predisposing skin defect affecting melanocyte adhesiveness that, under stress conditions, leads to disappearance of melanocytes and clinical vitiligo. Melanocyte adhesiveness is thus a potential target for therapy aiming at disease stabilization.

The epithelial to mesenchymal transition (EMT) is an essential process during development and during tumour progression. Here, we observed the accumulation of the selective autophagy receptor and signalling adaptor sequestosome-1 (SQSTM1/p62) during growth factor-induced EMT in immortalized and tumour-derived epithelial cell lines. Modulation of the p62 level regulated the expression of junctional proteins. This effect was dependent on the ubiquitin-associated domain of p62, which stabilized the TGFβ/Smad signalling co-activator Smad4 and the EMT transcription factor Twist. This study highlights a novel function of p62 in a major epithelial phenotypic alteration.

The exposure of skin to ultraviolet (UV) radiation can have both beneficial and deleterious effects: it can lead, for instance, to increased pigmentation and vitamin D synthesis but also to inflammation and skin cancer. UVB may induce genetic and epigenetic alterations and have reversible effects associated with post-translational and gene regulation modifications. β-catenin is a main driver in melanocyte development; although infrequently mutated in melanoma, its cellular localization and activity are frequently altered. Here, we evaluate the consequence of UVB on β-catenin in the melanocyte lineage. We report that in vivo, UVB induces cytoplasmic/nuclear relocalization of β-catenin in melanocytes of newborn mice and adult human skin. In mouse melanocyte and human melanoma cell lines in vitro, UVB increases β-catenin stability, accumulation in the nucleus and cotranscriptional activity, leading to the repression of cell motility and velocity. The activation of the β-catenin signalling pathway and its effect on migration by UVB are increased by an inhibitor of GSK3β, and decreased by an inhibitor of β-catenin. In conclusion, UVB represses melanocyte migration and does so by acting through the GSK3-β-catenin axis.

Sequence polymorphisms linked to human diseases and phenotypes in genome-wide association studies often affect non-coding regions. A single nucleotide polymorphism (SNP) within an intron of the gene encoding Interferon Regulatory Factor 4 (IRF4), a transcription factor with no known role in melanocyte biology, is strongly associated with sensitivity of skin to sun exposure, freckles, blue eyes and brown hair color. Here we demonstrate that this SNP lies within an enhancer of IRF4 transcription in melanocytes. The allele associated with this pigmentation phenotype impairs binding of the TFAP2A transcription factor which together with the melanocyte master regulator MITF, regulates activity of the enhancer. Assays in zebrafish and mice reveal that IRF4 cooperates with MITF to activate expression of Tyrosinase (TYR), an essential enzyme in melanin synthesis. Our findings provide a clear example of a non-coding polymorphism that affects a phenotype by modulating a developmental gene regulatory network.

Mammary epithelium comprises a layer of luminal cells and a basal myoepithelial cell layer. Both mammary epithelial compartments, basal and luminal, contain stem and progenitor cells, but only basal cells are capable of gland regeneration upon transplantation. Aberrant expansion of stem/progenitor cell populations is considered to contribute to breast tumorigenesis. Germline deletions of p53 in humans and mice confer a predisposition to tumors, and stem cell frequency is abnormally high in the mammary epithelium of p53-deficient mice. However, it is unknown whether stem/progenitor cell amplification occurs in both, basal and luminal cell populations in p53-deficient mammary tissue. We used a conditional gene deletion approach to study the role of p53 in stem/progenitor cells residing in the mammary luminal and basal layers. Using two- and three-dimensional cell culture assays, we showed that p53 loss led to the expansion of clonogenic stem/progenitor cells in both mammary epithelial cell layers. Moreover, following p53 deletion, luminal and basal stem/progenitor cells acquired a capacity for unlimited propagation in mammosphere culture. Furthermore, limiting dilution and serial transplantation assays revealed amplification and enhanced self-renewal in the basal regenerating cell population of p53-deficient mammary epithelium. Our data suggest that the increase in stem/progenitor cell activity may be, at least, partially mediated by the Notch pathway. Taken together, these results strongly indicate that p53 restricts the propagation and self-renewal of stem/progenitor cells in both layers of the mammary epithelium providing further insight into the impact of p53 loss in breast cancerogenesis.

Targeted gene knockout mouse models have helped to identify roles of autophagy in many tissues. Here, we investigated the retinal pigment epithelium (RPE) of Atg7f/f Tyr-Cre mice (on a C57BL/6 background), in which Cre recombinase is expressed under the control of the tyrosinase promoter to delete the autophagy gene Atg7. In line with pigment cell-directed blockade of autophagy, the RPE and the melanocytes of the choroid showed strong accumulation of the autophagy adaptor and substrate, sequestosome 1 (Sqstm1)/p62, relative to the levels in control mice. Immunofluorescence and Western blot analysis demonstrated that the RPE, but not the choroid melanocytes, of Atg7f/f Tyr-Cre mice also had strongly increased levels of retinoid isomerohydrolase RPE65, a pivotal enzyme for the maintenance of visual perception. In contrast to Sqstm1, genes involved in retinal regeneration, i.e. Lrat, Rdh5, Rgr, and Rpe65, were expressed at higher mRNA levels. Sequencing of the Rpe65 gene showed that Atg7f/f and Atg7f/f Tyr-Cre mice carry a point mutation (L450M) that is characteristic for the C57BL/6 mouse strain and reportedly causes enhanced degradation of the RPE65 protein by an as-yet unknown mechanism. These results suggest that the increased abundance of RPE65 M450 in the RPE of Atg7f/f Tyr-Cre mice is, at least partly, mediated by upregulation of Rpe65 transcription; however, our data are also compatible with the hypothesis that the RPE65 M450 protein is degraded by Atg7-dependent autophagy in Atg7f/f mice. Further studies in mice of different genetic backgrounds are necessary to determine the relative contributions of these mechanisms.

Triple-negative breast cancer is a heterogeneous disease characterized by the expression of basal cell markers, no estrogen or progesterone receptor expression and a lack of HER2 overexpression. Triple-negative tumors often display activated Wnt/β-catenin signaling and most have impaired p53 function. We studied the interplay between p53 loss and Wnt/β-catenin signaling in stem cell function and tumorigenesis, by deleting p53 from the mammary epithelium of K5ΔNβcat mice displaying a constitutive activation of Wnt/β-catenin signaling in basal cells. K5ΔNβcat transgenic mice present amplification of the basal stem cell pool and develop triple-negative mammary carcinomas. The loss of p53 in K5ΔNβcat mice led to an early expansion of mammary stem/progenitor cells and accelerated the formation of triple-negative tumors. In particular, p53-deficient tumors expressed high levels of integrins and extracellular matrix components and were enriched in cancer stem cells. They also overexpressed the tyrosine kinase receptor Met, a feature characteristic of human triple-negative breast tumors. The inhibition of Met kinase activity impaired tumorsphere formation, demonstrating the requirement of Met signaling for cancer stem cell growth in this model. Human basal-like breast cancers with predicted mutated p53 status had higher levels of MET expression than tumors with wild-type p53. These results connect p53 loss and β-catenin activation to stem cell regulation and tumorigenesis in triple-negative cancer and highlight the role of Met signaling in maintaining cancer stem cell properties, revealing new cues for targeted therapies.

ResumeCet article presente et discute les resultats d’une etude de la representation sociale du leadership chez des cadres dirigeants francais. Les resultats soulignent l’importance accordee par les dirigeants au developpement du leadership dans des fonctions de direction, et met en lumiere la centralite du charisme, de la vision et du management d’equipe dans le contenu de la representation. Ils decrivent egalement les cadres d’experience privilegies du leadership, les croyances et quelques pratiques d’apprentissage des dirigeants en la matiere. L’auteur souligne en conclusion l’importance d’expliciter les theories implicites du leadership aussi bien dans l’elaboration theorique du leadership que dans la formation des managers au leadership.

BACKGROUND The intestinal microbiota regulates key host functions. It is unknown whether modulation of the microbiota can affect a genetically determined host phenotype. Polymorphisms in the Nucleotide oligomerization domain (Nod) like receptor family confer genetic risk for inflammatory bowel disease (IBD). We investigated whether the intestinal microbiota and the probiotic strain Bifidobacterium breve NCC2950 affect intestinal barrier function and responses to intestinal injury in Nod1( / ); Nod2( / ) mice. METHODS Specific pathogen free (SPF) Nod1( / ); Nod2( / ) mice and mice gnotobiotically derived with altered Schaedler flora (ASF) biota were used. SPF Nod1(+/ ); Nod2(+/ ) littermates (generated by crossing SPF Nod1( / ); Nod2( / ) and germ free C57BL/6 mice) and ASF Nod1(+/ ); Nod2(+/ ) mice were used as controls. SPF mice were gavaged daily with 10(9) CFU B. breve for 14 days before colitis induction. Denaturing gradient gel electrophoresis (DGGE) and real time polymerase chain reaction (PCR) were used to assess microbiota composition. Intestinal permeability was assessed by in vitro and in vivo techniques. Expressions of epithelial apical junction proteins mucin and antimicrobial proteins were assessed by quantitative reverse transcription PCR (qRT PCR) and immunofluorescence. Responses to intestinal injury were investigated using an acute experimental model of colitis. RESULTS Under SPF conditions Nod1( / ); Nod2( / ) mice had increased paracellular permeability decreased E cadherin and lower colonic antimicrobial RegIII ? expression compared to Nod1(+/ ); Nod2(+/ ) littermate controls. These changes were associated with increased susceptibility to colitis. ASF colonization or B. breve supplementation normalized RegIII ? expression and decreased susceptibility to dextran sodium sulfate (DSS) colitis in Nod1( / ); Nod2( / ) mice. CONCLUSIONS The intestinal microbiota influences colitis severity in Nod1( / ); Nod2( / ) mice. The results suggest that colonization strategies with defined commensals or exogenous specific probiotic therapy may prevent intestinal inflammation in a genetically predisposed host.

Fermitin family member 1 (FERMT1, Kindlin-1) is an epithelial-specific regulator of integrin functions and is associated with Kindler syndrome, a genetic disorder characterized by skin blistering, atrophy, and photosensitivity. However, the possible role of kindlin-1 in cancer remains unknown. Kindlin-1 expression was quantified in several human cancers using quantitative real-time polymerase chain reaction and published microarray datasets. The association between kindlin-1 expression and patient metastasis-free survival (N = 516) was assessed with Kaplan-Meier analyses. Effects of ectopic expression or silencing of kindlin-1 on cell signaling, migration, and invasion were assessed in human breast cancer cell lines using western blotting, immunofluorescence, wound healing assays, and invasion on Matrigel or type I collagen substrates. Breast tumor growth and lung metastasis were evaluated in 12-week-old female BALB/c mice (10 controls and six Kindlin-1-knockdown mice). All statistical tests were two-sided. Kindlin-1 expression was consistently higher in tumors than in normal tissues in various cancer types metastasizing to the lungs, including colon and bladder cancer. Kindlin-1 expression was associated with metastasis-free survival in both breast and lung adenocarcinoma (breast cancer: hazard ratio of lung metastasis = 2.55, 95% confidence intervals [CI] = 1.39 to 4.69, P = .001; lung cancer: hazard ratio of metastasis = 1.96, 95% CI = 1.25 to 3.07, P = .001). Overexpression of kindlin-1 induced changes indicating epithelial-mesenchymal transition and transforming growth factor beta (TGF beta) signaling, constitutive activation of cell motility, and invasion (number of migrating cells, Kindlin-1 cells vs control, mean = 164.66 vs 19.00, difference = 145.6, 95% CI = 79.1 to 212.2, P = .004; invasion rate, Kindlin-1-cells vs control = 9.65% vs 1.92%, difference = 7.73%, 95% CI = 4.75 to 10.70, P < .001). Finally, Kindlin-1 depletion in an orthotopic mouse model statistically significantly inhibited breast tumor growth (P < .001) and lung metastasis (P = .003). These results suggest a role for kindlin-1 in breast cancer lung metastasis and lung tumorigenesis and advance our understanding of kindlin-1 as a regulator of TGF beta signaling, offering new avenues for therapeutic intervention against cancer progression.

The newly developed, high throughput, Vitros 3600 immunoassay system associates different technologies on board: MicroWell (analytes immunocapture), MicroSensor (visible interference analysis), and Intellicheck (real time process control for analytical error detection). During a three months period, Vitros 3600 system, ease of use, practicability and MicroSensor technology efficiency have been tested using the following assays: betaHCG, troponin, ferritin, aHBcT, HBsAg, aHCV, AFP and CEA. Within-day and within-batch, between-calibration precisions are acceptable. Overall assay correlations versus the methods in use in our laboratory are good, despite small numerical differences that never affect clinical interpretation of the results. We have appreciated the system reliability, reinforced by the ease of use (simple software, on-board VDocs, continuous access to reagent and sample loading, reagent stability, very low noise (60 dB)), the quality of the results, MicroSensor and Intellicheck technologies efficiency, the short maintenance time and its traceability, and the very low liquid waste volume (5 L of liquid waste for 1600 tests). In conclusion and considering its practicability, the Vitros 3600 system is fully validated and well suited for our laboratory.

International audience; The mammary gland epithelium comprises two major cell types: basal and luminal. Basal cells interact directly with the extracellular matrix (ECM) and express higher levels of the ECM receptors, integrins, than luminal cells. We show that deletion of beta1 integrin from basal cells abolishes the regenerative potential of the mammary epithelium and affects mammary gland development. The mutant epithelium was characterized by an abnormal ductal branching pattern and aberrant morphogenesis in pregnancy, although at the end of gestation, the secretory alveoli developed from beta1 integrin-positive progenitors. Lack of beta1 integrin altered the orientation of the basal-cell division axis and in mutant epithelium, in contrast to control tissue, the progeny of beta1 integrin-null basal cells, identified by a genetic marker, was found in the luminal compartment. These results reveal, for the first time, the essential role of the basal mammary epithelial cell-ECM interactions mediated by beta1 integrins in the maintenance of a functional stem cell population, mammary morphogenesis and segregation of the two major mammary cell lineages.

L’epithelium mammaire est une bicouche composee d’une part de cellules myoepitheliales basales et d’autre part de cellules luminales. Les proprietes si particulieres de la morphogenese post-natale de la glande mammaire, notamment la mise en place du reseau canalaire durant la puberte, et la formation d’alveoles a chaque grossesse, suggerent que des cellules souches resident dans l’epithelium mammaire adulte. Differentes strategies incluant notamment l’analyse de la retention de marqueurs de l’ADN, l’etude du potentiel de developpement in vivo de sous-populations cellulaires et des approches transgeniques, sont utilisees depuis quelques annees pour isoler et caracteriser les cellules souches et progenitrices de l’epithelium mammaire murin. Les caracteristiques moleculaires de ces cellules restent a definir de facon precise mais des progres notables ont deja ete realises pour leur enrichissement et leur identification.

SUMMARY Molecular signatures specific to particular tumor types are required to design treatments for resistant tumors. However, it remains unclear whether tumors and corresponding cell lines used for drug development share such signatures. We developed similarity core analysis (SCA), a universal and unsupervised computational framework for extracting core molecular features common to tumors and cell lines. We applied SCA to mRNA/miRNA expression data from various sources, comparing melanoma cell lines and metastases. The signature obtained was associated with phenotypic characteristics in vitro, and the core genes CAPN3 and TRIM63 were implicated in melanoma cell migration/invasion. About 90% of the melanoma signature genes belong to an intrinsic network of transcription factors governing neural development (TFAP2A, DLX2, ALX1, MITF, PAX3, SOX10, LEF1, and GAS7) and miRNAs (211-5p, 221-3p, and 10a-5p). The SCA signature effectively discriminated between two subpopulations of melanoma patients differing in overall survival, and classified MEKi/BRAFi-resistant and -sensitive melanoma cell lines., In Brief Cancer cell lines are at the forefront of drug discovery but are often limited in representing the tumor of origin due to the artificial culture conditions. Rambow et al. develop a computational approach for identifying tumor cell lineage expression cores. These core genes reveal relevant molecular dependencies linking aggressiveness, patient survival, and drug sensitivity.

HGF/Met signaling has recently been associated with basal-type breast cancers, which are thought to originate from progenitor cells residing in the luminal compartment of the mammary epithelium. We found that ICAM-1 efficiently marks mammary luminal progenitors comprising hormone receptor-positive and receptor-negative cells, presumably ductal and alveolar progenitors. Both cell populations strongly express Met, while HGF is produced by stromal and basal myoepithelial cells. We show that persistent HGF treatment stimulates the clonogenic activity of ICAM1-positive luminal progenitors, controlling their survival and proliferation, and leads to the expression of basal cell characteristics, including stem cell potential. This is accompanied by the induction of Snai1 and Snai2, two major transcription factors triggering epithelial–mesenchymal transition, the repression of the luminal-regulatory genes Elf5 and Hey1, and claudin down-regulation. Our data strongly indicate that paracrine Met signaling can control the function of luminal progenitors and modulate their fate during mammary development and tumorigenesis. DOI: http://dx.doi.org/10.7554/eLife.06104.001, eLife digest Throughout the life of a female mammal, the mammary glands undergo different phases of development to prepare for, and adapt to, feeding offspring. Luminal cells line the inside of branch-like structures throughout the mammary gland and are responsible for producing milk. When the mammary gland grows, new luminal cells develop from a kind of cell called luminal progenitor cells. However, these progenitor cells are also thought to be the source of certain types of breast cancer. Recently, it has been suggested that luminal progenitor cells display a receptor protein called Met on their surface. When Met and ‘co-receptor’ proteins bind to a molecule called HGF, this triggers a cascade of signals that can cause certain cells to change their properties. This is known as the epithelial–mesenchymal transition. Although this transition is important for new tissues to develop, it can also result in cancerous tumors forming if it is not correctly controlled. Luminal cells do not produce HGF themselves, which suggests that Met signaling in these cells is triggered by the HGF released from neighboring cells. However, neither the mechanisms behind this signaling nor the effects of signaling on the luminal progenitor cells are well understood. Di-Cicco et al. set out to identify where Met, its co-receptors and HGF are located in the mouse mammary gland during different phases of development. This revealed that one of the co-receptors—called ICAM-1—can be used as a marker to identify certain types of luminal progenitor cell. Di-Cicco et al. found that these progenitor cells display Met on their surface, and other types of mammary cell—called stromal cells and myoepithelial cells—produce HGF. When exposed to HGF, luminal progenitor cells grown in culture in the laboratory proliferated and went through the epithelial–mesenchymal transition. These findings suggest that myoepithelial and stromal cells regulate luminal progenitor cells by producing HGF to activate Met signaling in these cells. Such interactions could be of great importance during mammary development and tumorigenesis. The next big challenge will be to determine the circumstances under which luminal progenitor cells stimulated by HGF can give rise to breast cancers. This work will allow us to better define the cell population that should be targeted by anti-cancer drugs. DOI: http://dx.doi.org/10.7554/eLife.06104.002