Expression of Chemokine Receptors in Uveal Melanoma

Purpose:Chemokine receptors are transmembrane G coupled proteins that might be involved in the directional metastatic migration of tumor cells to specific organs. CXCR4 and CCR7 have been implicated in the selective metastasis of cutaneous melanoma cells to lung and lymph node, respectively. CCR6 is expressed in metastases from colon, ovarian and thyroid carcinomas to the liver where its ligand, CCL20, is constitutively expressed. As uveal melanomas frequently metastasize to the liver, we hypothesized that specific chemokine receptors and their respective ligands might be involved in metastasis of uveal melanoma to the liver. Methods:Tissue microarrays were constructed using 100 non irradiated primary uveal melanomas and 84 liver metastases, as well as 12 non liver metastases, collected from the files of Jules Gonin Eye Hospital and Pathology Institute, University of Lausanne. Immunohistochemistry was performed using anti-human CXCR4, SDF1, CCR7, CCL21 and CCR6 antibodies. Results:CXCR4 expression was detected in 36% of primary uveal melanomas and in 63% of liver metastases but no expression was found in metastases to other organs, except for one pancreatic metastasis. SDF1 expression was detected in 3% of primary uveal melanomas and in 26% of liver metastases, as well as in pancreas, lymph node and breast metastases. CCR6 expression was observed in the majority of primary uveal melanomas and liver metastases (73 and 88%, respectively). In addition, CCR6 was also detected in 9 metastases to other organs (pancreas, thyroid, lymph node, skin and breast). CCR7 and CCL21 were neither detected in primary uveal melanoma, nor in the metastases. Conclusions:Chemokine receptors CCR6 and CXCR4 are expressed in a large number of primary uveal melanomas and in uveal melanoma metastases to the liver. CCR6 is also expressed in a small number of metastases to other organs. These findings form the basis for further studies on the potential involvement of CXCR4 and CCR6 in the selective metastasis of uveal melanoma to the liver.

Correlation between subjective evaluation of symptoms and objective findings in early recurrent head and neck squamous cell carcinoma.

IMPORTANCE: This study addresses the value of patients' reported symptoms as markers of tumor recurrence after definitive therapy for head and neck squamous cell carcinoma. OBJECTIVE: To evaluate the correlation between patients' symptoms and objective findings in the diagnosis of local and/or regional recurrences of head and neck squamous cell carcinomas in the first 2 years of follow-up. DESIGN: Retrospective single-institution study of a prospectively collected database. SETTING: Regional hospital. PARTICIPANTS: We reviewed the clinical records of patients treated for oral cavity, oropharyngeal, laryngeal, and hypopharyngeal carcinomas between January 1, 2008, and December 31, 2009, with a minimum follow-up of 2 years. MAIN OUTCOMES AND MEASURES: Correlation between symptoms and oncologic status (recurrence vs remission) in the posttreatment period. RESULTS: Of the 101 patients included, 30 had recurrences. Pain, odynophagia, and dysphonia were independently correlated with recurrence (odds ratios, 16.07, 11.20, and 5.90, respectively; P < .001). New-onset symptoms had the best correlation with recurrences. Correlation was better between 6 to 12 and 18 to 21 months after therapy and in patients initially treated unimodally (P < .05). Primary stage and tumor site had no effect. CONCLUSIONS AND RELEVANCE: The correlation between symptoms and oncologic status is low during substantial periods within the first 2 years of follow-up. New-onset symptoms, especially pain, odynophagia, or dysphonia, better correlate with tumor recurrence, especially in patients treated unimodally.

Integrative molecular bioinformatics study of human adrenocortical tumors : microRNA, tissue-specific target prediction, and pathway analysis.

MicroRNAs (miRs) are involved in the pathogenesis of several neoplasms; however, there are no data on their expression patterns and possible roles in adrenocortical tumors. Our objective was to study adrenocortical tumors by an integrative bioinformatics analysis involving miR and transcriptomics profiling, pathway analysis, and a novel, tissue-specific miR target prediction approach. Thirty-six tissue samples including normal adrenocortical tissues, benign adenomas, and adrenocortical carcinomas (ACC) were studied by simultaneous miR and mRNA profiling. A novel data-processing software was used to identify all predicted miR-mRNA interactions retrieved from PicTar, TargetScan, and miRBase. Tissue-specific target prediction was achieved by filtering out mRNAs with undetectable expression and searching for mRNA targets with inverse expression alterations as their regulatory miRs. Target sets and significant microarray data were subjected to Ingenuity Pathway Analysis. Six miRs with significantly different expression were found. miR-184 and miR-503 showed significantly higher, whereas miR-511 and miR-214 showed significantly lower expression in ACCs than in other groups. Expression of miR-210 was significantly lower in cortisol-secreting adenomas than in ACCs. By calculating the difference between dCT(miR-511) and dCT(miR-503) (delta cycle threshold), ACCs could be distinguished from benign adenomas with high sensitivity and specificity. Pathway analysis revealed the possible involvement of G2/M checkpoint damage in ACC pathogenesis. To our knowledge, this is the first report describing miR expression patterns and pathway analysis in sporadic adrenocortical tumors. miR biomarkers may be helpful for the diagnosis of adrenocortical malignancy. This tissue-specific target prediction approach may be used in other tumors too.

Immune response to MMTV infection.

Mouse mammary tumor virus (MMTV) has developed a strategy of exploitation of the immune response. It infects dendritic cells and B cells and requires this infection to establish an efficient chronic infection. This allows transmission of infection to the mammary gland, production in milk and infection of the next generation via lactation. The elaborate strategy developed by MMTV utilizes several key elements of the normal immune response. Starting with the infection and activation of dendritic cells and B cells leading to the expression of a viral superantigen followed by professional superantigen-mediated priming of naive polyclonal T cells by dendritic cells and induction of superantigen-mediated T cell B cell collaboration results in long-lasting germinal center formation and production of long-lived B cells that can later carry the virus to the mammary gland epithelium. Later in life it can induce transformation of mammary gland epithelium by integrating close to proto-oncogenes leading to their overexpression. Genes encoding proteins of the Wnt-pathway are preferential targets. This review will put these effects in the context of a normal immune response and summarize important facts on MMTV biology.

Normal pathogen-specific immune responses mounted by CTLA-4-deficient T cells: a paradigm reconsidered.

CTLA-4 is a critical negative regulator of T cell responses and CTLA-4-deficient (CTLA-4(-/-)) mice die of a lymphproliferative disease. Nevertheless, RAG-2-deficient mice reconstituted with a mixture of CTLA-4(-/-) and normal (CTLA-4(+/+)) bone marrow survive in the absence of any signs of disease, although 50% of their T cells do not express CTLA-4. Using such mixed chimeras, we analyzed the role of CTLA-4 in specific T cell responses to lymphocytic choriomeningitis virus, Leishmania major and mouse mammary tumor virus, which cause acute, chronic and persistent infections, respectively. The populations of antigen-specific CTLA-4(-/-)CD4(+) and CTLA-4(-/-)CD8(+) T cells became activated, expanded and contracted indistinguishably from CTLA-4(+/+)CD4(+) and CTLA-4(+/+)CD8(+) T cells after infection with all three pathogens. Thus, CTLA-4 is not involved in the down-regulation of specific T cell responses and peripheral deletion in a T cell-autonomous fashion.

Telomerase activation in colorectal carcinogenesis.

Telomerase activity has been detected in germ cells as well as in the developing embryo. Activity is no longer detectable in most somatic cells of the neonate, although low levels of activity persist in regenerative tissues. Telomerase has been found to be reactivated or up-regulated in the majority of cancers. The colorectal adenoma-carcinoma sequence is one of the best-characterized models of multistep tumourigenesis and is thus suitable for determining at which stage telomerase is activated. Telomerase activity was examined by telomeric repeat amplification protocol (TRAP) assay in 96 cases of colorectal tissues, including 50 carcinomas, 31 adenomas, and 15 normal colonic tissues. For each case, histological diagnosis and telomerase activity were determined on consecutive frozen sections. In order to reduce the chance of a false-negative TRAP assay due to RNA degradation, the integrity of rRNA in the tissues was verified in each case. Twenty-five carcinomas, 30 adenomas, and all of the 15 normal colorectal mucosal samples showed no or only partial rRNA degradation and only in these cases was the TRAP assay interpreted. None of the normal tissues exhibited telomerase activity. In contrast, all of the 25 cancers and 47 per cent (14/30) of the adenomas were positive. In adenomas, telomerase activation was highly significantly related to the grade of dysplasia (p< 0.0001). All adenomas which contained high-grade dysplasia revealed telomerase activity, whereas telomerase activity was detectable in only 20 per cent (4/20) of cases with exclusively low-grade dysplasia. These results indicate that telomerase activation, which may be an obligatory step in colorectal carcinogenesis, occurs in the progression from low-grade to high-grade dysplasia in adenomas. Furthermore, in the adenoma-carcinoma sequence, telomerase activation seems to occur later than K- ras mutation but earlier than p53 mutation.

Mitotic figure counts are overrated in resection specimen of invasive breast carcinoma

In order for some patients to benefit from aggressive chemotherapy for invasive breast carcinoma, many patients are currently being treated without little or no benefit. Enormous effort is hence being directed towards the identification of those patients who will need chemotherapy and those who will not. Since chemotherapy targets proliferating cells pathologists focus on the proliferative activity of tumors, as assessed by mitotic figure counts or by cell cycle specific immunohistochemical markers, such as Ki-67 and H3 histone. As far as the tumor grade is concerned, many of these studies have reported a tendency to up-grade carcinomas in resection specimen when compared to the initial diagnosis on the biopsy material, and most studies have noted that the upgrade in resection specimen is due solely or to a large extent to an increase in the mitotic figure count. In the present study, we propose a different explanation for the divergence in mitotic figure counts between biopsy and resection material. We assessed the proliferative activity of 52 invasive ductal carcinomas and confirm that the number of mitotic figures significantly increased by a factor of more than 3 in resection specimen over the biopsy material, while at the same time the pan-cell cycle specific marker MIB-1 yieldes comparable results. we propose that the delayed formalin fixation of resection specimen allows cell cycle activities to continue for a long time, up to many hours, and that this leads to an arrest of mitoses in metaphase where they are readily identified by the pathologist. We propose that the mitotic figure count in the rapidly fixed biopsy cores better represent the tumor biology and should be used as a basis for chemotherapy therapeutic decisions.

Inhibition of the Kit Ligand/c-Kit Axis Attenuates Metastasis in a Mouse Model Mimicking Local Breast Cancer Relapse after Radiotherapy.

PURPOSE: Local breast cancer relapse after breast-saving surgery and radiotherapy is associated with increased risk of distant metastasis formation. The mechanisms involved remain largely elusive. We used the well-characterized 4T1 syngeneic, orthotopic breast cancer model to identify novel mechanisms of postradiation metastasis. EXPERIMENTAL DESIGN: 4T1 cells were injected in 20 Gy preirradiated mammary tissue to mimic postradiation relapses, or in nonirradiated mammary tissue, as control, of immunocompetent BALB/c mice. Molecular, biochemical, cellular, histologic analyses, adoptive cell transfer, genetic, and pharmacologic interventions were carried out. RESULTS: Tumors growing in preirradiated mammary tissue had reduced angiogenesis and were more hypoxic, invasive, and metastatic to lung and lymph nodes compared with control tumors. Increased metastasis involved the mobilization of CD11b(+)c-Kit(+)Ly6G(high)Ly6C(low)(Gr1(+)) myeloid cells through the HIF1-dependent expression of Kit ligand (KitL) by hypoxic tumor cells. KitL-mobilized myeloid cells homed to primary tumors and premetastatic lungs, to give rise to CD11b(+)c-Kit(-) cells. Pharmacologic inhibition of HIF1, silencing of KitL expression in tumor cells, and inhibition of c-Kit with an anti-c-Kit-blocking antibody or with a tyrosine kinase inhibitor prevented the mobilization of CD11b(+)c-Kit(+) cells and attenuated metastasis. C-Kit inhibition was also effective in reducing mobilization of CD11b(+)c-Kit(+) cells and inhibiting lung metastasis after irradiation of established tumors. CONCLUSIONS: Our work defines KitL/c-Kit as a previously unidentified axis critically involved in promoting metastasis of 4T1 tumors growing in preirradiated mammary tissue. Pharmacologic inhibition of this axis represents a potential therapeutic strategy to prevent metastasis in breast cancer patients with local relapses after radiotherapy. Clin Cancer Res; 18(16); 4365-74. ©2012 AACR.

Mechanisms of CYR61 mediated breast cancer metastasis to the lung

CYR61 (Cysteine-rich angiogenic inducer 61) is a matricellular protein that regulates cell proliferation, adhesion, migration and cell survival through interaction with various types of integrin cell adhesion receptors. At tissue level it is implicated in the regulation of embryonic development, wound healing and angiogenesis. CYR61 has also been involved in cancer progression, however its role appears to be diverse and complex depending on the cancer type and stage. Its contribution to metastasis formation is still unclear. Previous findings reported by our laboratory demonstrated that CYR61 cooperates with avßs integrin to promote invasion and metastasis of cancers growing in a pre-irradiated microenvironment. In this work, we used an orthotopic model of breast cancer to show for the first time that silencing of CYR61 in breast cancer cells suppresses lung metastasis formation. Silencing of MDA-MB-231 reduced both local growth and lung metastasis formation of tumor cells implanted in a pre-irradiated mammary fat pad. CYR61 silencing in tumors growing in non-irradiated mammary fat pads did not impact primary tumor growth but decreased lung metastasis formation. The effect of CYR61 on spontaneous lung metastasis formation during natural cancer progression was further examined by using an experimental model of metastasis. Results from these experiments indicate that CYR61 is critically involved in promoting cancer cells entry into lung parenchyma rather than later steps of colonization. In vitro experiments showed that CYR61 promotes tumor cell spreading, migration and transendothelial migration. CYR61 also supported colony formation under anchorage-independent condition and promotes resistance to anoikis through the involvement of ß1 and ß3 integrin. These results indicate that CYR61 promotes lung metastasis of breast cancer by facilitating extravasation into lung parenchyma through enhanced motility, transendothelial migration and resistance to anoikis. - CYR61 (Cysteine-rich angiogenic inducer 61) est une protéine matricellulaire qui régule la prolifération, l'adhérence, la migration et la survie des cellules par son interaction avec différents types de récepteurs d'adhésion cellulaire de la famille des intégrine. Au niveau des tissus, CYR61 est impliquée dans la régulation du développement embryonnaire, de la cicatrisation et de l'angiogenèse. CYR61 a également été impliquée dans le cancer, mais son rôle semble être divers et complexe en fonction du type du cancer et de son stade. Son rôle dans la formation des métastases n'est pas encore clair. Des résultats antérieurs rapportés par notre laboratoire ont montré que CYR61 coopère avec l'intégrine avß5 pour favoriser l'invasion et la métastase de tumeurs se développant dans un micro-environnement pré-irradié. Dans ce travail, nous avons utilisé un modèle orthotopique de cancer du sein pour démontrer pour la première fois que l'extinction (silencing) du gène CYR61 dans le cancer du sein réduit la formation de métastases pulmonaires. L'extinction de CYR61 dans la lignée cellulaire de cancer du sein humain MDA-MB- 231 réduit à la fois la croissance local ainsi que la formation de métastases pulmonaires à partir de cellules implantés dans les coussinets adipeux mammaires pré-irradié. L'extinction de CYR61 dans des tumeurs grandissant dans les coussinets adipeux mammaires non irradiées n'a pas d'incidence sur la croissance tumorale primaire mais réduit la formation des métastases pulmonaires. Par la suite nous avons examiné l'effet de CYR61 sur la formation de métastases pulmonaires en utilisant un modèle expérimental de métastase. Les résultats de ces expériences indiquent que CYR61 est impliquée de manière cruciale dans les étapes précoces de la formation de métastases, plutôt que dans les étapes tardives de colonisation du poumon. Des expériences in vitro ont montré que CYR61 favorise l'étalement, la migration et la transmigration endothéliale des cellules tumorales. CYR61 favorise également la formation de colonies dans des conditions indépendante de l'ancrage et la résistance à l'anoïkis par l'engagement des intégrines ß1 et ß3. Ces résultats indiquent que CYR61 favorise les métastases pulmonaires du cancer du sein en facilitant l'extravasation dans le parenchyme pulmonaire grâce à la stimulation de la motilità, de la migration transmigration endothéliale et de la résistance à l'anoïkis.

Management of adenoid cystic carcinoma of the breast: a Rare Cancer Network study.

BACKGROUND: Mammary adenoid cystic carcinoma (ACC) is a rare breast cancer. The aim of this retrospective study was to assess prognostic factors and patterns of failure, as well as the role of radiation therapy (RT), in ACC.¦METHODS: Between January 1980 and December 2007, 61 women with breast ACC were treated at participating centers of the Rare Cancer Network. Surgery consisted of lumpectomy in 41 patients and mastectomy in 20 patients. There were 51(84%) stage pN0 and 10 stage cN0 (16%) patients. Postoperative RT was administered to 40 patients (35 after lumpectomy, 5 after mastectomy).¦RESULTS: With a median follow-up of 79 months (range, 6-285), 5-year overall and disease-free survival rates were 94% (95% confidence interval [CI], 88%-100%) and 82% (95% CI, 71%-93%), respectively. The 5-year locoregional control (LRC) rate was 95% (95% CI, 89%-100%). Axillary lymph node dissection or sentinel node biopsy was performed in 84% of cases. All patients had stage pN0 disease. In univariate analysis, survival was not influenced by the type of surgery or the use of postoperative RT. The 5-year LRC rate was 100% in the mastectomy group versus 93% (95% CI, 83%-100%) in the breast-conserving surgery group, respectively (p = 0.16). For the breast-conserving surgery group, the use of RT significantly correlated with LRC (p = 0.03); the 5-year LRC rates were 95% (95% CI, 86%-100%) for the RT group versus 83% (95% CI, 54%-100%) for the group receiving no RT. No local failures occurred in patients with positive margins, all of whom received postoperative RT.¦CONCLUSION: Breast-conserving surgery is the treatment of choice for patients with ACC breast cancer. Axillary lymph node dissection or sentinel node biopsy might not be recommended. Postoperative RT should be proposed in the case of breast-conserving surgery.

Carcinomes épidermoïdes de l'hypopharynx et du larynx : prise en charge fondée sur les preuves Squamous cell carcinoma of the hypopharynx and larynx: evidence-based care.

Les carcinomes épidermoïdes de l'hypopharynx et du larynx peuvent être traités par chirurgie et/ou radiothérapie en fonction de la taille tumorale. Pour les petites tumeurs, les résultats sont équivalents. Pour les tumeurs localement avancées, l'approche chirurgicale est mutilante et nécessite une (pharyngo)laryngectomie totale. La chimioradiothérapie exclusive a montré tout son intérêt mais au prix de séquelles tardives. Dans le but de diminuer ces séquelles et les mutilations, la chimiothérapie d'induction par cisplatine, docétaxel et 5FU à visée de préservation d'organe devient le standard de traitement mais il manque des études solides de comparaison de cette approche avec la chimioradiothérapie exclusive. Il n'est pas possible de conclure quant à la supériorité d'un schéma en survie globale. Quand la chimiothérapie d'induction est choisie, les modalités de potentialisation éventuelle de la radiothérapie ne sont pas établies. Squamous cell carcinomas of larynx and hypopharynx can be treated by surgery and/or radiotherapy according to tumor size. For small tumors, the results are similar. For locally advanced tumors, the surgical approach is mutilating and requires a total (pharyngo)laryngectomy. Exclusive chemoradiotherapy has shown its interest at the cost of late sequelae. In order to reduce these effects and mutilation, induction chemotherapy with cisplatin, docetaxel and 5FU for organ preservation becomes the standard treatment but there are no solid studies comparing this approach with the exclusive chemoradiotherapy. And it is not possible to conclude as to the superiority of a scheme in terms of overall survival. When chemotherapy is chosen, the modalities of any potentiation of radiation have not been yet established.

Peroxisome proliferator activated receptor BETA/DELTA as a central player in the skin response to ultra-violets radiation

Previous studies in the lab of Dr. Liliane Michalik, have shown thai the nuclear hormone receptor Peroxisome Proliferator Activated Receptor beta/delta (PPARß/ö) is an important regulator of skin homeostasis, being involved in the regulation of keratinocyte differentiation, inflammation, apoptosis, arid mouse skin wound healing. Studies of PPARß/ö knock out mice have suggested a possible role for this receptor in cancer. However, contradictory observations of the role for PPARß/ö on tumor growth have been published, depending on cellular contexts and biological models. Given the controversial role of PPARß/ö in skin carcinoma development, the main aim of this PhD work has been to further explore the implication of PPARß/ö in skin response to UV and skin tumor growth. This PhD dissertation is divided in four chapters. The first chapter describes the core part of the project, where I explored the changes in miRNA expression in the skin upon chronic UV irradiation of PPARß/ö wild type and knock-out mice. This analysis shed light on a miRNA- PPARß/ö signature and also predicted thai miR-21-3p (previously named miR-21*) is a key regulator of the PPARß/ö-dependent UV response in the pre-lesiona! skin. Using mice acutely UV-irradiated, ! further demonstrated that miR-21-3p is indirectly regulated by PPARß/ö through activation of Transforming Growth Factor (TGFß)-1 under UV exposure. I also show that miR-21-3p is deregulated in human cutaneous squamous celi carcinoma. In cultured keratinocytes, application of a miR-21 -3p mimic oligonucleotide sequence leads to the regulation of lipid metabolism-related pathway. In the second chapter, I demonstrate that the usage of an mRNA/miRNA combined bioinformatics analysis leads to the discovery of important pathways involved in the PPARß/ö-miRNA response of the skin to chronic UV irradiation, indeed, I validated angiogenesis and lipid metabolism as important functions regulated by PPARß/ö in this context. In the third chapter, we demonstrate that PPARß/5 knockout mice have decreased cutaneous squamous cell carcinomas incidence compared to wild type mice and that PPARß/5 directly activates the cSrc kinase gene. In the last chapter, we review novel insights into PPAR functions in keratinocytes and liver, with emphasis on PPARß/ö but also on PPARa. In summary, this PhD study shows that i) PPARß/5 is able to regulate biological function through regulation of miRNAs, and specifically through miR-21-3p, the passenger miRNA of the oncomiR miR-21, and that ii) the PPARß/5-dependent skin response to UV involves the regulation of angiogenesis and lipid metabolism. Furthermore, the bioinformatics study highlights the relevance of performing integrated mRNA and miRNA genome-wide studies in order to better screen mRNAs and/or miRNAs of interest in the biological context of diseases. - Des études préalables dans le laboratoire du Dr. Liliane Michalik ont démontré que le récepteur nucléaire PPARß/5 est un régulateur important de l'homéostasie de la peau, étant impliqué dans la régulation de la différenciation des keratinocytes, dans l'inflammation, dans l'apoptose et dans la cicatrisation de la peau chez !a souris. L'étude de souris knock-out pour le gène PPARß/5, ont suggérées un rôle possible de ce récepteur dans le cancer. Cependant, des observations opposées ont été publiées suggérant un rôle pro- ou anti- cancer selon le tissue impliqué et le type- cellulaire. En considérant cette controverse autour du rôle de PPARß/5 dans le développement des cancers de la peau, le but principal de mon projet de recherche aura été d'approfondir l'exploration du rôle de PPARß/5 dans la réponse de la peau aux UVs et dans le développement du cancer. Cette dissertation de thèse est divisée en quatre parties. Une première partie, représentant le coeur de mon travail de recherche, décrit la découverte de l'implication des microRNAs (rniRNAs) dans la réponse aux UVs de PPARß/ö et plus spécifiquement l'implication du miRNA miR- 21 -3p (précédemment nommé miR-21*). En étudiant un modèle de souris irradiées de manière aigüe aux UVs, nous montrons que ia régulation de miR-21-3p est PPARß/ö-däpenaante et que cette régulation à lieu par l'intermédiaire du facteur de transcription TGFß-1. Dans des cultures de keratinocytes Humains, la transfecticn d'une séquence oligonucléotidique similaire à celle de miR-21-3p (mimic), montre l'implication de rniR-21-3p dans des fonctions importantes pour le développement des cancers telles que le métabolisme des lipides. Dans un second chapitre, nous montrons que l'usage d'une méthode bioinformatique combinant l'expression des ARN messagers et des miRNAs permet de mettre en évidence des fonctions biologiques importantes lors de ia réponse de PPARß/ö à l'irradiation chronique. L'angiogenèse, le stress oxydatif et le métabolisme des lipides font partie de ces fonctions régulées par PPARß/5 dans la peau irradiée aux UVs. Nous mettons également en évidence la régulation du gène LpcatS par PPARß/5 dans la peau irradiée aux UV ainsi que dans des keratinocytes humains suggérant un rôle pour PPARß/5 dans le remodelage des lipides membranaires. Dans une troisième partie, nous établissons un lien entre la régulation de l'oncogène Src et l'activation de PPARß/5 dans les carcinomes spinocellulaires de la peau. Finalement dans un quatrième chapitre, nous faisons une revue des dernières recherches portées sur le rôle de PPARß/5 et de PPARa dans le foie et ia peau. En résumé ce projet de thèse représente un avancement pour la recherche sur rimplication de PPARß/5 dans la réponse aux UVs de la peau. Pour la première fois, un lien est établi entre ce facteur de transcription et la régulation de microRNAs dans le cadre du carcinome spinocellulare. Jusqu'alors resté dans l'ombre de rniR-21-5p, miR-21-3p est en fait fortement augmenté à la fois dans un modèle de souris d'irradiation aux UVs ainsi que dans ie carcinome spinocellulare chez i'humain. De nouvelles fonctions biologiques pour PPARß/5 ont été également mises en évidence dans ce travail, comme la régulation de l'angiogenèse ou du métabolisme des lipides dans Sa peau. De plus cette dissertation valorise l'intérêt d'une association entre le travail de laboratoire et celui de la bioinformatique.

Extrafollicular plasmablast B cells play a key role in carrying retroviral infection to peripheral organs.

B cells can either differentiate in germinal centers or in extrafollicular compartments of secondary lymphoid organs. Here we show the migration properties of B cells after differentiation in murine peripheral lymph node infected with mouse mammary tumor virus. Naive B cells become activated, infected, and carry integrated retroviral DNA sequences. After production of a retroviral superantigen, the infected B cells receive cognate T cell help and differentiate along the two main differentiation pathways analogous to classical Ag responses. The extrafollicular differentiation peaks on day 6 of mouse mammary tumor virus infection, and the follicular one becomes detectable after day 10. B cells participating in this immune response carry a retroviral DNA marker that can be detected by using semiquantitative PCR. We determined the migration patterns of B cells having taken part in the T cell-B cell interaction from the draining lymph node to different tissues. Waves of immigration and retention of infected cells in secondary lymphoid organs, mammary gland, salivary gland, skin, lung, and liver were observed correlating with the two peaks of B cell differentiation in the draining lymph node. Other organs revealed immigration of infected cells at later time points. The migration properties were correlated with a strong up-regulation of alpha(4)beta(1) integrin expression. These results show the migration properties of B cells during an immune response and demonstrate that a large proportion of extrafolliculary differentiating plasmablasts can escape local cell death and carry the retroviral infection to peripheral organs.

Treatment of extended skin defects with autologous composite cultured skin grafts in a patient with epidermolysis bullosa

Rationale: The purpose of this article is to demonstrate the use of homologous culture cells in treating an advanced coccon formation of the hand and three extended squamous cell carcinomas of the lower and upper limb in a patient with recessive dystrophic epidermolysis bullosa. The preparation and application of these cells in the operation room are being described. Methods: A number of surgical approaches have been described to correct these deformities in order to improve function.We propose a new therapeutic approach of treating loss of motion and independent digital function as well as coverage of large skin defects in a patient with recessive dystrophic epidermolysis bullosa by using autologous culture cells. Surgical treatment of these patients is really difficult because of the existing skin fragility. Furthermore, surgical wounds do not easily heal because of recurrent blisters and erosions as well as due to the patients' poor nutricial status. Results: We report our experience of mutiple extended cutaneous squamous cell carcinomas arising in our patient which were successfully managed using autologous composite cultured skin grafts. The cocoon hand deformity was also treated with the limb becoming functional. Conclusion: The use of autologous keratinocytes and fibroblasts in epidermolysis bullosa is hereby outlined for the fist time.

Roles of superantigens in microbial infections?

Superantigens have been defined in a variety of infectious particles such as bacteria and viruses. These superantigens have the capacity to stimulate a large percentage of the host T cells by interacting specifically with the T-cell receptor V beta chain which is shared by about 1-20% of mature T cells. The recent discovery that mammary tumour viruses express such superantigens enabled the analysis of the retroviral life cycle and led to questions about the role of superantigen in amplification of the infection.