Cdx2 homeoprotein inhibits non-homologous end joining in colon cancer but not in leukemia cells

Cdx2, a gene of the paraHox cluster, encodes a homeodomain transcription factor that plays numerous roles in embryonic development and in homeostasis of the adult intestine. Whereas Cdx2 exerts a tumor suppressor function in the gut, its abnormal ectopic expression in acute leukemia is associated to a pro-oncogenic function. To try to understand this duality, we have hypothesized that Cdx2 may interact with different protein partners in the two tissues and set up experiments to identify them by tandem affinity purification. We show here that Cdx2 interacts with the Ku heterodimer specifically in intestinal cells, but not in leukemia cells, via its homeodomain. Ku proteins do not affect Cdx2 transcriptional activity. However, Cdx2 inhibits in vivo and in vitro the DNA repair activity mediated by Ku proteins in intestinal cells. Whereas Cdx2 does not affect the recruitment of Ku proteins and DNA-PKcs into the DNA repair complex, it inhibits DNA-PKcs activity. Thus, we report here a new function of Cdx2, acting as an inhibitor of the DNA repair machinery, that may contribute to its tumor suppressor function specifically in the gut

Early liver transplantation for severe alcohol-related hepatitis not responding to medical treatment: a prospective controlled study

peer reviewedBackground: Early liver transplantation for severe alcohol-related hepatitis is an emerging treatment option. We aimed to assess the risk of alcohol relapse 2 years after early liver transplantation for alcohol-related hepatitis compared with liver transplantation for alcohol-related cirrhosis after at least 6 months of abstinence. Methods: We conducted a multicentre, non-randomised, non-inferiority, controlled study in 19 French and Belgian hospitals. All participants were aged 18 years or older. There were three groups of patients recruited prospectively: patients with severe alcohol-related hepatitis who did not respond to medical treatment and were eligible for early liver transplantation according to a new selection scoring system based on social and addiction items that can be quantified in points (early transplantation group); patients with alcohol-related cirrhosis listed for liver transplantation after at least 6 months of abstinence (standard transplantation group); patients with severe alcohol-related hepatitis not responding to medical treatment not eligible for early liver transplantation according to the selection score (not eligible for early transplantation group), this group did not enter any further liver transplantation processes. We also defined a historical control group of patients with severe alcohol-related hepatitis unresponsive to medical therapy and non-transplanted. The primary outcome was the non-inferiority of 2-year rate of alcohol relapse after transplantation in the early transplantation group compared with the standard transplantation group using the alcohol timeline follow back (TLFB) method and a prespecified non-inferiority margin of 10%. Secondary outcomes were the pattern of alcohol relapse, 2-year survival rate post-transplant in the early transplantation group compared with the standard transplantation group, and 2-year overall survival in the early transplantation group compared with patients in the not eligible for early transplantation group and historical controls. This trial is registered with ClinicalTrials.gov, NCT01756794. Findings: Between Dec 5, 2012, and June 30, 2016, we included 149 patients with severe alcohol-related hepatitis: 102 in the early transplantation group and 47 in the not eligible for early transplantation group. 129 patients were included in the standard transplantation group. 68 patients in the early transplantation group and 93 patients in the standard transplantation group received a liver transplant. 23 (34%) patients relapsed in the early transplantation group, and 23 (25%) patients relapsed in the standard transplantation group; therefore, the non-inferiority of early transplantation versus standard transplantation was not demonstrated (absolute difference 9·1% [95% CI –∞ to 21·1]; p=0·45). The 2-year rate of high alcohol intake was greater in the early transplantation group than the standard transplantation group (absolute difference 16·7% [95% CI 5·8–27·6]) The time spent drinking alcohol was not different between the two groups (standardised difference 0·24 [95% CI −0·07 to 0·55]), but the time spent drinking a large quantity of alcohol was higher in the early transplantation group than the standard transplantation group (standardised difference 0·50 [95% CI 0·17–0·82]). 2-year post-transplant survival was similar between the early transplantation group and the standard transplantation group (hazard ratio [HR] 0·87 [95% CI 0·33–2·26]); 2-year overall survival was higher in the early transplantation group than the not eligible for early transplantation group and historical controls (HR 0·27 [95% CI 0·16–0·47] and 0·21 [0·13–0·32]). Interpretation: We cannot conclude non-inferiority in terms of rate of alcohol relapse post-transplant between early liver transplantation and standard transplantation. High alcohol intake is more frequent after early liver transplantation. This prospective controlled study confirms the important survival benefit related to early liver transplantation for severe alcohol-related hepatitis; and this study provides objective data on survival and alcohol relapse to tailor the management of patients with severe alcohol-related hepatitis. Funding: The present study has been granted by the French Ministry of Health—Programme Hospitalier de Recherche Clinique 2010

New non-transcriptional function of the homeotic transcription factor Cdx2

Le cancer colorectal (CCR) représente la 2ème cause de mortalité par cancer dans les pays industrialisés. De nouveaux traitements permettant de bloquer l’évolution de la maladie sont nécessaires. Il est donc important de mieux connaitre les acteurs impliqués dans la cancérogenèse. Lors du développement du cancer, des gènes suppresseurs de tumeur sont inhibés et des oncogènes sont activés, perturbant ainsi l’équilibre des cellules et les transformant. Au cours de ma thèse, je me suis intéressée à deux gènes homéotiques qui possèdent des rôles opposés dans les CCR. Cdx2 exerce un rôle suppresseur de tumeur, alors que HoxB7 agit comme un oncogène. Mon travail de thèse a permis (i) de mettre en évidence une nouvelle fonction non-transcriptionnelle de Cdx2 : inhibiteur de la réparation des cassures de l'ADN spécifiquement dans le côlon, (ii) et de révéler que le niveau d'expression des gènes Cdx2 et Hoxb7 au sein de la tumeur peut avoir une importance pour le choix du traitement des CCR.Colorectal cancer is the 2nd cause of mortality by cancer in industrialized countries. New treatments allowing to prevent the evolution of the disease are needed. It is important to better understand the actors implicated in carcinogenesis. During cancer development, tumor suppressor genes are inhibited and oncogenes are activated, thus disrupting the homeostasis of the tissue and transforming the cells. During my thesis, I have been interested in two genes having two opposite functions in CCR : Cdx2 is a tumor suppressor while Hoxb7 acts as an oncogene. My work allows to highlight (i) a new non-transcriptional function of Cdx2 : inhibitor of the reparation of DNA breaks specifically in the colon, (ii) and that the expression level of Cdx2 and Hoxb7 genes inside the tumor can have an importance in the choice of the CCR treatment

New non-transcriptional function of the homeotic transcription factor Cdx2

Le cancer colorectal (CCR) représente la 2ème cause de mortalité par cancer dans les pays industrialisés. De nouveaux traitements permettant de bloquer l’évolution de la maladie sont nécessaires. Il est donc important de mieux connaitre les acteurs impliqués dans la cancérogenèse. Lors du développement du cancer, des gènes suppresseurs de tumeur sont inhibés et des oncogènes sont activés, perturbant ainsi l’équilibre des cellules et les transformant. Au cours de ma thèse, je me suis intéressée à deux gènes homéotiques qui possèdent des rôles opposés dans les CCR. Cdx2 exerce un rôle suppresseur de tumeur, alors que HoxB7 agit comme un oncogène. Mon travail de thèse a permis (i) de mettre en évidence une nouvelle fonction non-transcriptionnelle de Cdx2 : inhibiteur de la réparation des cassures de l'ADN spécifiquement dans le côlon, (ii) et de révéler que le niveau d'expression des gènes Cdx2 et Hoxb7 au sein de la tumeur peut avoir une importance pour le choix du traitement des CCR.Colorectal cancer is the 2nd cause of mortality by cancer in industrialized countries. New treatments allowing to prevent the evolution of the disease are needed. It is important to better understand the actors implicated in carcinogenesis. During cancer development, tumor suppressor genes are inhibited and oncogenes are activated, thus disrupting the homeostasis of the tissue and transforming the cells. During my thesis, I have been interested in two genes having two opposite functions in CCR : Cdx2 is a tumor suppressor while Hoxb7 acts as an oncogene. My work allows to highlight (i) a new non-transcriptional function of Cdx2 : inhibitor of the reparation of DNA breaks specifically in the colon, (ii) and that the expression level of Cdx2 and Hoxb7 genes inside the tumor can have an importance in the choice of the CCR treatment

Mise en évidence d'une fonction non-transcriptionnelle du facteur de transcription homéotique Cdx2

Colorectal cancer is the 2nd cause of mortality by cancer in industrialized countries. New treatments allowing to prevent the evolution of the disease are needed. It is important to better understand the actors implicated in carcinogenesis. During cancer development, tumor suppressor genes are inhibited and oncogenes are activated, thus disrupting the homeostasis of the tissue and transforming the cells. During my thesis, I have been interested in two genes having two opposite functions in CCR : Cdx2 is a tumor suppressor while Hoxb7 acts as an oncogene. My work allows to highlight (i) a new non-transcriptional function of Cdx2 : inhibitor of the reparation of DNA breaks specifically in the colon, (ii) and that the expression level of Cdx2 and Hoxb7 genes inside the tumor can have an importance in the choice of the CCR treatment.Le cancer colorectal (CCR) représente la 2ème cause de mortalité par cancer dans les pays industrialisés. De nouveaux traitements permettant de bloquer l’évolution de la maladie sont nécessaires. Il est donc important de mieux connaitre les acteurs impliqués dans la cancérogenèse. Lors du développement du cancer, des gènes suppresseurs de tumeur sont inhibés et des oncogènes sont activés, perturbant ainsi l’équilibre des cellules et les transformant. Au cours de ma thèse, je me suis intéressée à deux gènes homéotiques qui possèdent des rôles opposés dans les CCR. Cdx2 exerce un rôle suppresseur de tumeur, alors que HoxB7 agit comme un oncogène. Mon travail de thèse a permis (i) de mettre en évidence une nouvelle fonction non-transcriptionnelle de Cdx2 : inhibiteur de la réparation des cassures de l'ADN spécifiquement dans le côlon, (ii) et de révéler que le niveau d'expression des gènes Cdx2 et Hoxb7 au sein de la tumeur peut avoir une importance pour le choix du traitement des CCR

A ZnS 4 Structural Zinc Site in the Helicobacter pylori Ferric Uptake Regulator

International audienceThe ferric uptake regulator (Fur) belongs to the family of the metal-responsive transcriptional regulators. Fur is a global regulator found in all proteobacteria. It controls the transcription of a wide variety of genes involved in iron metabolism but also in oxidative stress or virulence factor synthesis. As a general view, Fur proteins were considered to be dimeric proteins both in solution and when bound to DNA. However, our recent data demonstrate that Fur proteins can be classified into two subfamilies, according to their quaternary structure. The group of dimers is represented by E. coli, V. cholerae and Y. pestis Fur and the group of highly stable tetramers by P. aeruginosa and F. tularensis Fur. Here, another tetrameric structure of a PaFur mutant containing manganese and zinc metal ions is described. Through biochemical, structural and computational studies, we have deciphered the important structural characteristics of the tetramers and studied the main interactions responsible for their strength. Potential or mean force calculations for tetramer formation have been determinant to quantify these interactions. Moreover calculations allow us to propose that some conserved residues prevent the tetramerization in the subfamily of dimeric Fur. Keywords Metal homeostasis Á Structure of metalloregulators Á Quaternary structure Á Iron uptake Á Molecular interactions Á Potential of mean force Á Ferric uptake Á Tetrame

Successful retrieval of human papillomavirus DNA after a 4.5 year storage on FTA elute cards

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Distinct mechanisms for opposite functions of homeoproteins Cdx2 and HoxB7 in double-strand break DNA repair in colon cancer cells.

International audienceHomeobox genes, involved in embryonic development and tissues homeostasis in adults, are often deregulated in cancer, but their relevance in pathology is far from being fully elucidated. In colon cancers, we report that the homeoproteins HoxB7 and Cdx2 exhibit different heterogeneous patterns, Cdx2 being localized in moderately altered neoplasic glands in contrast to HoxB7 which predominates in poorly-differentiated areas; they are coexpressed in few cancer cells. In human colon cancer cells, both homeoproteins interact with the DNA repair factor KU70/80, but functional studies reveal opposite effects: HoxB7 stimulates DNA repair and cell survival upon etoposide treatment, whereas Cdx2 inhibits both processes. The stimulatory effect of HoxB7 on DNA repair requires the transactivation domain linked to the homeodomain involved in the interaction with KU70/80, whereas the transactivation domain of Cdx2 is dispensable for its inhibitory function, which instead needs the homeodomain to interact with KU70/80 and the C-terminal domain. Thus, HoxB7 and Cdx2 respectively use transcription-dependent and -independent mechanisms to stimulate and inhibit DNA repair. In addition, in cells co-expressing both homeoproteins, Cdx2 lessens DNA repair activity through a novel mechanism of inhibition of the transcriptional function of HoxB7, whereby Cdx2 forms a molecular complex with HoxB7 and prevents it to recognize its target in the chromatin. These results point out the complex interplay between the DSB DNA repair activity and the homeoproteins HoxB7 and Cdx2 in colon cancer cells, making the balance between these factors a determinant and a potential indicator of the efficacy of genotoxic drugs

Human papillomavirus DNA and p16 expression in head and neck squamous cell carcinoma in young French patients

International audienceObjectives Human papillomavirus (HPV) is a risk factor for head and neck squamous cell carcinoma (HNSCC), which is currently increasing worldwide. We evaluated the prevalence of HPV DNA and p16 expression in HNSCC patients age <45 years compared with patients aged ≥45 years. Methods Thirty-nine patients aged <45 years who presented at Besançon University Hospital with HNSCC since 2005 were included in this retrospective study. HPV DNA was detected by HPV genotyping and p16 expression was determined by immunohistochemistry using paraffin-embedded tissues. A matched-group of 38 patients aged ≥45 years from Besançon University Hospital was included. Results The overall prevalence of HPV infection was 11.7%. HPV16 was the only genotype detected in 4/39 and 5/38 patients, and p16 was expressed in 6/39 and 4/38 patients aged <45 years and ≥45 years, respectively. Conclusions HPV-positivity and p16 expression were similar in both age groups. The results suggest that p16 immunohistochemistry may provide a prognosis biomarker for all HNSCCs, not only oropharyngeal cancers, and this should be addressed in large clinical trials