Juan Iovanna - Academia.edu (original) (raw)

Papers by Juan Iovanna

BMC Developmental Biology, 2015

HP1γ, a well-known regulator of gene expression, has been recently identified to be a target of A... more HP1γ, a well-known regulator of gene expression, has been recently identified to be a target of Aurora A, a mitotic kinase which is important for both gametogenesis and embryogenesis. The purpose of this study was to define whether the Aurora A-HP1γ pathway supports cell division of gametes and/or early embryos, using western blot, immunofluorescence, immunohistochemistry, electron microscopy, shRNA-based knockdown, site-directed mutagenesis, and Affymetrix-based genome-wide expression profiles. We find that the form of HP1γ phosphorylated by Aurora A, P-Ser83 HP1γ, is a passenger protein, which localizes to the spermatozoa centriole and axoneme. In addition, disruption in this pathway causes centrosomal abnormalities and aberrations in cell division. Expression profiling of male germ cell lines demonstrates that HP1γ phosphorylation is critical for the regulation of mitosis-associated gene expression networks. In female gametes, we observe that P-Ser83-HP1γ is not present in meiotic centrosomes of M2 oocytes, but after syngamy, it becomes detectable during cleavage divisions, coinciding with early embryonic genome activation. These results support the idea that phosphorylation of HP1γ by Aurora A plays a role in the regulation of gene expression and mitotic cell division in cells from the sperm lineage and in early embryos. Combined, this data is relevant to better understanding the function of HP1γ in reproductive biology.

Encyclopedia of Cancer, 2011

Encyclopedia of Cancer, 2011

EMBO molecular medicine, Jan 30, 2015

The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D)... more The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D). T2D is characterized by insulin resistance resulting from both environmental and genetic factors. A genome-wide association study (GWAS) published in 2010 identified TP53INP1 as a new T2D susceptibility locus, but a pathological mechanism was not identified. In this work, we show that mice lacking TP53INP1 are prone to redox-driven obesity and insulin resistance. Furthermore, we demonstrate that the reactive oxygen species increase in TP53INP1-deficient cells results from accumulation of defective mitochondria associated with impaired PINK/PARKIN mitophagy. This chronic oxidative stress also favors accumulation of lipid droplets. Taken together, our data provide evidence that the GWAS-identified TP53INP1 gene prevents metabolic syndrome, through a mechanism involving prevention of oxidative stress by mitochondrial homeostasis regulation. In conclusion, this study highlights TP53INP1 as...

Oncotarget, Jan 10, 2015

It has been commonly found that in patients presenting Pancreatic Ductal Adenocarcinoma (PDAC), a... more It has been commonly found that in patients presenting Pancreatic Ductal Adenocarcinoma (PDAC), after a period of satisfactory response to standard treatments, the tumor becomes non-responsive and patient death quickly follows. This phenomenon is mainly due to the rapid and uncontrolled development of the residual tumor. The origin and biological characteristics of residual tumor cells in PDAC still remain unclear. In this work, using PDACs from patients, preserved as xenografts in nude mice, we demonstrated that a residual PDAC tumor originated from a small number of CD44+ cells present in the tumor. During PDAC relapse, proliferating CD44+ cells decrease expression of ZEB1, while overexpressing the MUC1 protein, and gain morphological and biological characteristics of differentiation. Also, we report that CD44+ cells, in primary and residual PDAC tumors, are part of a heterogeneous population, which includes variable numbers of CD133+ and EpCAM+ cells. We confirmed the propagation...

Molecular and clinical oncology, 2013

Stress proteins of the pancreas, such as tumor protein 53-induced nuclear protein 1 (TP53INP1), a... more Stress proteins of the pancreas, such as tumor protein 53-induced nuclear protein 1 (TP53INP1), are important factors in the invasion and metastasis of pancreatic cancer. TP53INP1 is a pro-apoptotic factor and is transcriptionally regulated in p53-dependent and -independent manners. A previous study proved that gemcitabine induces TP53INP1 expression in pancreatic cancer cells and the pancreatic cancer cell line (PANC-1). The present study aimed to clarify the association between TP53INP1 and gemcitabine sensitivity. The expression of TP53INP1 and its related factors, such as cell growth and cell cycle status in TP53INP1-knockout mouse embryonic fibroblasts [TP53INP1(-/-)-mouse embryonic fibroblasts (MEFs)] to those in wild-type counterparts (TP53INP1(+/+)-MEFs) were compared. Flow cytometric analysis demonstrated no difference of the checkpoint function in TP53INP1(-/-)-MEFs and TP53INP1(+/+)-MEFs when exposed to 10 ng/ml of gemcitabine. No significant difference was found in the l...

Archives of Biochemistry and Biophysics, 2015

The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being ... more The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being proposed to act as co-transcription factor whose expression is increased during inflammation. Recent data from astrocytes demonstrates that p8 suppression leads to induction of heme oxygenase 1 (HO-1). Here, we assessed the cross-talk between p8 and HO-1 in mouse embryonic fibroblasts (MEF) observing an increased expression of HO-1 in p8-deficient (p8(-/-)) MEFs in non-treated and treated conditions. This effect was independent of the cell cycle. Our findings revealed that generation of reactive oxygen species (ROS) was higher in p8(-/-) MEFs. Mitochondria and NADPH oxidases were not the origin of ROS. This observation was not restricted to MEF as suppression of p8 gene transcription in MiaPaCa-2 cells also led to increased intracellular ROS. Additionally, p8 deficiency did not affect the Rac1 dependant NADPH oxidase complex. Our data shows that p8 deficiency increases ROS and subsequently the expression of anti-oxidative enzymes, such as HO-1, suggesting an involvement in the anti-oxidative defense. Moreover, we suggest that the severity of AP observed in p8(-/-) mice is induced by an impaired anti oxidative capacity of the pancreas, which is caused by increased generation of ROS.

Frontiers in Oncology, 2012

Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months ... more Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months and a dismal 5-year survival rate of 3-5%. The development and progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways. Therefore, the strategies targeting these molecules as well as their downstream signaling could be promising for the prevention and treatment of pancreatic cancer. However, although targeted therapies for pancreatic cancer have yielded encouraging results in vitro and in animal models, these findings have not been translated into improved outcomes in clinical trials. This failure is due to an incomplete understanding of the biology of pancreatic cancer and to the selection of poorly efficient or imperfectly targeted agents. In this review, we will critically present the current knowledge regarding the molecular, biochemical, clinical, and therapeutic aspects of pancreatic cancer.

Proceedings of the National Academy of Sciences, 2015

The malignant progression of pancreatic ductal adenocarcinoma (PDAC) is accompanied by a profound... more The malignant progression of pancreatic ductal adenocarcinoma (PDAC) is accompanied by a profound desmoplasia, which forces proliferating tumor cells to metabolically adapt to this new microenvironment. We established the PDAC metabolic signature to highlight the main activated tumor metabolic pathways. Comparative transcriptomic analysis identified lipid-related metabolic pathways as being the most highly enriched in PDAC, compared with a normal pancreas. Our study revealed that lipoprotein metabolic processes, in particular cholesterol uptake, are drastically activated in the tumor. This process results in an increase in the amount of cholesterol and an overexpression of the low-density lipoprotein receptor (LDLR) in pancreatic tumor cells. These findings identify LDLR as a novel metabolic target to limit PDAC progression. Here, we demonstrate that shRNA silencing of LDLR, in pancreatic tumor cells, profoundly reduces uptake of cholesterol and alters its distribution, decreases tumor cell proliferation, and limits activation of ERK1/2 survival pathway. Moreover, blocking cholesterol uptake sensitizes cells to chemotherapeutic drugs and potentiates the effect of chemotherapy on PDAC regression. Clinically, high PDAC Ldlr expression is not restricted to a specific tumor stage but is correlated to a higher risk of disease recurrence. This study provides a precise overview of lipid metabolic pathways that are disturbed in PDAC. We also highlight the high dependence of pancreatic cancer cells upon cholesterol uptake, and identify LDLR as a promising metabolic target for combined therapy, to limit PDAC progression and disease patient relapse.

Methods, 2015

Prostate cancer is among the most frequent cancers in men, and despite its high rate of cure, the... more Prostate cancer is among the most frequent cancers in men, and despite its high rate of cure, the high number of cases results in an elevated mortality worldwide. Importantly, prostate cancer incidence is dramatically increasing in western societies in the past decades, suggesting that this type of tumor is exquisitely sensitive to lifestyle changes. Prostate cancer frequently exhibits alterations in the PTEN gene (inactivating mutations or gene deletions) or at the protein level (reduced protein expression or altered sub-cellular compartmentalization). The relevance of PTEN in this type of cancer is further supported by the fact that the sole deletion of PTEN in the murine prostate epithelium recapitulates many of the features of the human disease. In order to study the molecular alterations in prostate cancer, we need to overcome the methodological challenges that this tissue imposes. In this review we present protocols and methods, using PTEN as proof of concept, to study different molecular characteristics of prostate cancer.

PLoS ONE, 2014

Ductal adenocarcinoma of the pancreas is ranking 4 for patient&am... more Ductal adenocarcinoma of the pancreas is ranking 4 for patient' death from malignant disease in Western countries, with no satisfactory treatment. We re-examined more precisely the histone deacetylases (HDAC) and Sirtuin (SIRT) gene expression patterns in pancreatic cancer with more pancreatic tumors and normal tissues. We also examined the possible relationship between HDAC gene expression levels and long term disease outcome. Moreover, we have evaluated by using an in vitro model system of human pancreatic tumor cell line whether HDAC7 knockdown may affect the cell behavior. We analyzed 29 pancreatic adenocarcinoma (PA), 9 chronic pancreatitis (CP), 8 benign pancreatic (BP) and 11 normal pancreatic tissues. Concerning pancreatic adenocarcinoma, we were able to collect biopsies at the tumor periphery. To assess the possible involvement of HDAC7 in cell proliferation capacity, we have generated recombinant human Panc-1 tumor which underexpressed or overexpressed HDAC7. The expression of HDAC1,2,3,4,7 and Nur77 increased in PA samples at levels significantly higher than those observed in the CP group (p = 0.0160; 0.0114; 0.0227; 0.0440; 0.0136; 0.0004, respectively). The expression of HDAC7, was significantly greater in the PA compared with BP tissue samples (p = 0.05). Mean mRNA transcription levels of PA for HDAC7 and HDAC2 were higher when compared to their counterpart biopsies taken at the tumor periphery (p = 0.0346, 0.0053, respectively). Moreover, the data obtained using confocal microscopy and a quantitative method of immunofluorescence staining strongly support the HDAC7 overexpression in PA surgical specimens. The number of deaths and recurrences at the end of follow up were significantly greater in patients with overexpression of HDAC7. Interestingly, the rate of growth was significantly reduced in the case of cell carrying shRNA construct targeting HDAC7 encoding gene when compared to the parental Panc-1 tumor cells (p = 0.0015) at 48 h and 96 h (p = 0.0021). This study strongly support the notion that HDAC7play a role in pancreatic adenocarcinoma progression.

Results in Immunology, 2013

Tumor Protein 53-Induced Nuclear Protein 1 (TP53INP1) plays an important role during cell stress ... more Tumor Protein 53-Induced Nuclear Protein 1 (TP53INP1) plays an important role during cell stress response in synergy with the potent "genome-keeper" p53. In human, the gene encoding TP53INP1 is expressed at very high level in some pathological situations, such as inflammation and prostate cancer (PC). TP53INP1 overexpression in PC seems to be a worse prognostic factor, particularly predictive of biological cancer relapse, making TP53INP1 a relevant specific target for molecular therapy of Castration Resistant (CR) PC. In that context, detection of TP53INP1 in patient biological fluids is a promising diagnostic avenue. We report here successful development of a new Enzyme-Linked Immunosorbent Assay (ELISA) detecting TP53INP1, taking advantage of molecular tools (monoclonal antibodies (mAbs) and recombinant proteins) generated in the laboratory during the course of basic functional investigations devoted to TP53INP1. The ELISA principle is based on a sandwich immunoenzymatic system, TP53INP1 protein being trapped by a first specific mAb coated on microplate then recognized by a second specific mAb. This new assay allows specific detection of TP53INP1 in serum of several PC patients. This breakthrough paves the way towards investigation of a large cohort of patients and assessment of clinical applications of TP53INP1 dosage.

Journal of Clinical Investigation, 2014

Oncotarget, Jan 3, 2014

Pancreatic Ductal Adenocarcinoma (PDAC) is a disease with a great heterogeneity in the response t... more Pancreatic Ductal Adenocarcinoma (PDAC) is a disease with a great heterogeneity in the response to treatments. To improve the responsiveness to treatments there are two different approaches, the first one consist to develop new and more efficient drugs that intent to cure all patients and the second one is to use already-approved drugs, alone or in combination, but selecting beforehand the most sensitive patients. In this work we explored the efficiency of the second possibility. We developed a collection of 17 PDAC samples collected by Endoscopic Ultrasound-Guided Fine-Needle Aspiration (EUS-FNA) or surgery and preserved as xenografts and as primary cultures. This collection was characterized at molecular level by a transcriptomic analysis using an Affymetrix approach. In this paper we present data demonstrating that a subgroup of PDAC responds to low doses of 5-aza-dC. These tumors show a specific RNA expression profile that could serve as a marker, but there is no correlation wit...

PLoS ONE, 2014

ArgBP2 (Arg-Binding Protein 2/SORBS2) is an adaptor protein involved in cytoskeleton associated s... more ArgBP2 (Arg-Binding Protein 2/SORBS2) is an adaptor protein involved in cytoskeleton associated signal transduction, thereby regulating cell migration and adhesion. These features are associated with its antitumoral role in pancreatic cancer cells. Tyrosine phosphorylation of ArgBP2, mediated by c-Abl kinase and counterbalanced by PTP-PEST phosphatase, regulates many of its interactions. However, the exact mechanisms of action and of regulation of ArgBP2 remain largely unknown. We found that ArgBP2 has the capacity to form oligomers which are destabilized by tyrosine phosphorylation. We could show that ArgBP2 oligomerization involves the binding of one of its SH3 domains to a specific proline rich cluster. ArgBP2 self-association increases its binding to some of its molecular partners and decreased its affinity for others. Hence, the phosphorylation/oligomerization state of ArgBP2 directly regulates its functions by modulating its adaptive capabilities. Importantly, using a human pancreatic cancer cell model (MiaPaCa-2 cells), we could validate that this property of ArgBP2 is critical for its cytoskeleton associated functions. In conclusions, we describe a new mechanism of regulation of ArgBP2 where tyrosine phosphorylation of the protein interfere with a SH3 mediated self-interaction, thereby controlling its panel of interacting partners and related functions.

PLoS ONE, 2014

Background: The pancreatitis-associated protein (PAP) is increased in the serum of active inflamm... more Background: The pancreatitis-associated protein (PAP) is increased in the serum of active inflammatory bowel disease (IBD) patients and its levels seem to be correlated with disease activity. Our aim was to evaluate the usefulness of serum and fecal PAP measurements to predict relapse in patients with inactive IBD.

Pancreas, 1991

Expression of the c-myc and H-ras oncogenes, and of several genes specifically expressed in adult... more Expression of the c-myc and H-ras oncogenes, and of several genes specifically expressed in adult rat pancreas was investigated by monitoring changes in corresponding mRNA concentrations, by dot-blot hybridization, during the early phase of regeneration following subtotal pancreatectomy. The oncogenes c-myc and H-ras were overexpressed after 12-24 and 48 h, respectively, then returned to basal levels. The concentrations of mRNAs encoding amylase, chymotrypsinogen B, and trypsinogen I decreased during the regeneration time. By contrast, proinsulin I mRNA concentration was increased at 12-48 h after surgical resection, and actin mRNA concentration was increased at 12-48 h after surgical resection, and actin mRNA concentration was increased at 12 h after subtotal pancreatectomy and remained elevated thereafter. We concluded that regeneration after subtotal pancreatectomy is accompanied by repression of certain genes that are expressed in differentiated pancreatic tissue, and that derepression of other genes may be necessary for starting and/or maintaining the process of pancreatic regeneration.

Journal of Cellular Physiology, 2009

The stress protein p8 is a small, highly basic, unfolded, and multifunctional protein. We have pr... more The stress protein p8 is a small, highly basic, unfolded, and multifunctional protein. We have previously shown that most of its functions are exerted through interactions with other proteins, whose activities are thereby enhanced or repressed. In this work we describe another example of such mechanism, by which p8 binds and negatively regulates MSL1, a histone acetyl transferase (HAT)-associated protein, which in turn binds the DNA-damage-associated 53BP1 protein to facilitate DNA repair following DNA g-irradiation. Contrary to the HAT-associated activity, MSL1-dependent DNA-repair activity is almost completely dependent on 53BP1 expression. The picture that has emerged from our findings is that 53BP1 could be a scaffold that gets the HAT MSL1-dependent DNA-repair activity to the sites of DNA damage. Finally, we also found that, although p8 expression is transiently activated after g-irradiation, it is eventually submitted to sustained down-regulation, presumably to allow development of MSL1-associated DNA-repair activity. We conclude that interaction of MSL1 with 53BP1 brings MSL1-dependent HAT activity to the vicinity of damaged DNA. MSL1-dependent HAT activity, which is negatively regulated by the stress protein p8, induces chromatin remodeling and relaxation allowing access to DNA of the repair machinery.

Journal of Cardiac Failure, 2009

Journal of Biological Chemistry, 2013

The function of Krüppel-like factor 11 (KLF11) in the regulation of metabolic pathways is conserv... more The function of Krüppel-like factor 11 (KLF11) in the regulation of metabolic pathways is conserved from flies to human. Alterations in KLF11 function result in maturity onset diabetes of the young 7 (MODY7) and neonatal diabetes; however, the mechanisms underlying the role of this protein in metabolic disorders remain unclear. Here, we investigated how the A347S genetic variant, present in MODY7 patients, modulates KLF11 transcriptional activity. A347S affects a previously identified transcriptional regulatory domain 3 (TRD3) for which co-regulators remain unknown. Structure-oriented sequence analyses described here predicted that the KLF11 TRD3 represents an evolutionarily conserved protein domain. Combined yeast two-hybrid and protein array experiments demonstrated that the TRD3 binds WD40, WWI, WWII, and SH3 domain-containing proteins. Using one of these proteins as a model, guanine nucleotide-binding protein β2 (Gβ2), we investigated the functional consequences of KLF11 coupling to a TRD3 binding partner. Combined immunoprecipitation and biomolecular fluorescence complementation assays confirmed that activation of three different metabolic G protein-coupled receptors (β-adrenergic, secretin, and cholecystokinin) induces translocation of Gβ2 to the nucleus where it directly binds KLF11 in a manner that is disrupted by the MODY7 A347S variant. Using genome-wide expression profiles, we identified metabolic gene networks impacted upon TRD3 disruption. Furthermore, A347S disrupted KLF11-mediated increases in basal insulin levels and promoter activity and blunted glucose-stimulated insulin secretion. Thus, this study characterizes a novel protein/protein interaction domain disrupted in a KLF gene variant that associates to MODY7, contributing to our understanding of gene regulation events in complex metabolic diseases.

BMC Developmental Biology, 2015

HP1γ, a well-known regulator of gene expression, has been recently identified to be a target of A... more HP1γ, a well-known regulator of gene expression, has been recently identified to be a target of Aurora A, a mitotic kinase which is important for both gametogenesis and embryogenesis. The purpose of this study was to define whether the Aurora A-HP1γ pathway supports cell division of gametes and/or early embryos, using western blot, immunofluorescence, immunohistochemistry, electron microscopy, shRNA-based knockdown, site-directed mutagenesis, and Affymetrix-based genome-wide expression profiles. We find that the form of HP1γ phosphorylated by Aurora A, P-Ser83 HP1γ, is a passenger protein, which localizes to the spermatozoa centriole and axoneme. In addition, disruption in this pathway causes centrosomal abnormalities and aberrations in cell division. Expression profiling of male germ cell lines demonstrates that HP1γ phosphorylation is critical for the regulation of mitosis-associated gene expression networks. In female gametes, we observe that P-Ser83-HP1γ is not present in meiotic centrosomes of M2 oocytes, but after syngamy, it becomes detectable during cleavage divisions, coinciding with early embryonic genome activation. These results support the idea that phosphorylation of HP1γ by Aurora A plays a role in the regulation of gene expression and mitotic cell division in cells from the sperm lineage and in early embryos. Combined, this data is relevant to better understanding the function of HP1γ in reproductive biology.

Encyclopedia of Cancer, 2011

Encyclopedia of Cancer, 2011

EMBO molecular medicine, Jan 30, 2015

The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D)... more The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D). T2D is characterized by insulin resistance resulting from both environmental and genetic factors. A genome-wide association study (GWAS) published in 2010 identified TP53INP1 as a new T2D susceptibility locus, but a pathological mechanism was not identified. In this work, we show that mice lacking TP53INP1 are prone to redox-driven obesity and insulin resistance. Furthermore, we demonstrate that the reactive oxygen species increase in TP53INP1-deficient cells results from accumulation of defective mitochondria associated with impaired PINK/PARKIN mitophagy. This chronic oxidative stress also favors accumulation of lipid droplets. Taken together, our data provide evidence that the GWAS-identified TP53INP1 gene prevents metabolic syndrome, through a mechanism involving prevention of oxidative stress by mitochondrial homeostasis regulation. In conclusion, this study highlights TP53INP1 as...

Oncotarget, Jan 10, 2015

It has been commonly found that in patients presenting Pancreatic Ductal Adenocarcinoma (PDAC), a... more It has been commonly found that in patients presenting Pancreatic Ductal Adenocarcinoma (PDAC), after a period of satisfactory response to standard treatments, the tumor becomes non-responsive and patient death quickly follows. This phenomenon is mainly due to the rapid and uncontrolled development of the residual tumor. The origin and biological characteristics of residual tumor cells in PDAC still remain unclear. In this work, using PDACs from patients, preserved as xenografts in nude mice, we demonstrated that a residual PDAC tumor originated from a small number of CD44+ cells present in the tumor. During PDAC relapse, proliferating CD44+ cells decrease expression of ZEB1, while overexpressing the MUC1 protein, and gain morphological and biological characteristics of differentiation. Also, we report that CD44+ cells, in primary and residual PDAC tumors, are part of a heterogeneous population, which includes variable numbers of CD133+ and EpCAM+ cells. We confirmed the propagation...

Molecular and clinical oncology, 2013

Stress proteins of the pancreas, such as tumor protein 53-induced nuclear protein 1 (TP53INP1), a... more Stress proteins of the pancreas, such as tumor protein 53-induced nuclear protein 1 (TP53INP1), are important factors in the invasion and metastasis of pancreatic cancer. TP53INP1 is a pro-apoptotic factor and is transcriptionally regulated in p53-dependent and -independent manners. A previous study proved that gemcitabine induces TP53INP1 expression in pancreatic cancer cells and the pancreatic cancer cell line (PANC-1). The present study aimed to clarify the association between TP53INP1 and gemcitabine sensitivity. The expression of TP53INP1 and its related factors, such as cell growth and cell cycle status in TP53INP1-knockout mouse embryonic fibroblasts [TP53INP1(-/-)-mouse embryonic fibroblasts (MEFs)] to those in wild-type counterparts (TP53INP1(+/+)-MEFs) were compared. Flow cytometric analysis demonstrated no difference of the checkpoint function in TP53INP1(-/-)-MEFs and TP53INP1(+/+)-MEFs when exposed to 10 ng/ml of gemcitabine. No significant difference was found in the l...

Archives of Biochemistry and Biophysics, 2015

The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being ... more The gene p8 encodes for a small cytoprotective protein with no apparent enzymatic activity being proposed to act as co-transcription factor whose expression is increased during inflammation. Recent data from astrocytes demonstrates that p8 suppression leads to induction of heme oxygenase 1 (HO-1). Here, we assessed the cross-talk between p8 and HO-1 in mouse embryonic fibroblasts (MEF) observing an increased expression of HO-1 in p8-deficient (p8(-/-)) MEFs in non-treated and treated conditions. This effect was independent of the cell cycle. Our findings revealed that generation of reactive oxygen species (ROS) was higher in p8(-/-) MEFs. Mitochondria and NADPH oxidases were not the origin of ROS. This observation was not restricted to MEF as suppression of p8 gene transcription in MiaPaCa-2 cells also led to increased intracellular ROS. Additionally, p8 deficiency did not affect the Rac1 dependant NADPH oxidase complex. Our data shows that p8 deficiency increases ROS and subsequently the expression of anti-oxidative enzymes, such as HO-1, suggesting an involvement in the anti-oxidative defense. Moreover, we suggest that the severity of AP observed in p8(-/-) mice is induced by an impaired anti oxidative capacity of the pancreas, which is caused by increased generation of ROS.

Frontiers in Oncology, 2012

Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months ... more Pancreatic cancer is the fourth leading cause of cancer death with a median survival of 6 months and a dismal 5-year survival rate of 3-5%. The development and progression of pancreatic cancer are caused by the activation of oncogenes, the inactivation of tumor suppressor genes, and the deregulation of many signaling pathways. Therefore, the strategies targeting these molecules as well as their downstream signaling could be promising for the prevention and treatment of pancreatic cancer. However, although targeted therapies for pancreatic cancer have yielded encouraging results in vitro and in animal models, these findings have not been translated into improved outcomes in clinical trials. This failure is due to an incomplete understanding of the biology of pancreatic cancer and to the selection of poorly efficient or imperfectly targeted agents. In this review, we will critically present the current knowledge regarding the molecular, biochemical, clinical, and therapeutic aspects of pancreatic cancer.

Proceedings of the National Academy of Sciences, 2015

The malignant progression of pancreatic ductal adenocarcinoma (PDAC) is accompanied by a profound... more The malignant progression of pancreatic ductal adenocarcinoma (PDAC) is accompanied by a profound desmoplasia, which forces proliferating tumor cells to metabolically adapt to this new microenvironment. We established the PDAC metabolic signature to highlight the main activated tumor metabolic pathways. Comparative transcriptomic analysis identified lipid-related metabolic pathways as being the most highly enriched in PDAC, compared with a normal pancreas. Our study revealed that lipoprotein metabolic processes, in particular cholesterol uptake, are drastically activated in the tumor. This process results in an increase in the amount of cholesterol and an overexpression of the low-density lipoprotein receptor (LDLR) in pancreatic tumor cells. These findings identify LDLR as a novel metabolic target to limit PDAC progression. Here, we demonstrate that shRNA silencing of LDLR, in pancreatic tumor cells, profoundly reduces uptake of cholesterol and alters its distribution, decreases tumor cell proliferation, and limits activation of ERK1/2 survival pathway. Moreover, blocking cholesterol uptake sensitizes cells to chemotherapeutic drugs and potentiates the effect of chemotherapy on PDAC regression. Clinically, high PDAC Ldlr expression is not restricted to a specific tumor stage but is correlated to a higher risk of disease recurrence. This study provides a precise overview of lipid metabolic pathways that are disturbed in PDAC. We also highlight the high dependence of pancreatic cancer cells upon cholesterol uptake, and identify LDLR as a promising metabolic target for combined therapy, to limit PDAC progression and disease patient relapse.

Methods, 2015

Prostate cancer is among the most frequent cancers in men, and despite its high rate of cure, the... more Prostate cancer is among the most frequent cancers in men, and despite its high rate of cure, the high number of cases results in an elevated mortality worldwide. Importantly, prostate cancer incidence is dramatically increasing in western societies in the past decades, suggesting that this type of tumor is exquisitely sensitive to lifestyle changes. Prostate cancer frequently exhibits alterations in the PTEN gene (inactivating mutations or gene deletions) or at the protein level (reduced protein expression or altered sub-cellular compartmentalization). The relevance of PTEN in this type of cancer is further supported by the fact that the sole deletion of PTEN in the murine prostate epithelium recapitulates many of the features of the human disease. In order to study the molecular alterations in prostate cancer, we need to overcome the methodological challenges that this tissue imposes. In this review we present protocols and methods, using PTEN as proof of concept, to study different molecular characteristics of prostate cancer.

PLoS ONE, 2014

Ductal adenocarcinoma of the pancreas is ranking 4 for patient&am... more Ductal adenocarcinoma of the pancreas is ranking 4 for patient' death from malignant disease in Western countries, with no satisfactory treatment. We re-examined more precisely the histone deacetylases (HDAC) and Sirtuin (SIRT) gene expression patterns in pancreatic cancer with more pancreatic tumors and normal tissues. We also examined the possible relationship between HDAC gene expression levels and long term disease outcome. Moreover, we have evaluated by using an in vitro model system of human pancreatic tumor cell line whether HDAC7 knockdown may affect the cell behavior. We analyzed 29 pancreatic adenocarcinoma (PA), 9 chronic pancreatitis (CP), 8 benign pancreatic (BP) and 11 normal pancreatic tissues. Concerning pancreatic adenocarcinoma, we were able to collect biopsies at the tumor periphery. To assess the possible involvement of HDAC7 in cell proliferation capacity, we have generated recombinant human Panc-1 tumor which underexpressed or overexpressed HDAC7. The expression of HDAC1,2,3,4,7 and Nur77 increased in PA samples at levels significantly higher than those observed in the CP group (p = 0.0160; 0.0114; 0.0227; 0.0440; 0.0136; 0.0004, respectively). The expression of HDAC7, was significantly greater in the PA compared with BP tissue samples (p = 0.05). Mean mRNA transcription levels of PA for HDAC7 and HDAC2 were higher when compared to their counterpart biopsies taken at the tumor periphery (p = 0.0346, 0.0053, respectively). Moreover, the data obtained using confocal microscopy and a quantitative method of immunofluorescence staining strongly support the HDAC7 overexpression in PA surgical specimens. The number of deaths and recurrences at the end of follow up were significantly greater in patients with overexpression of HDAC7. Interestingly, the rate of growth was significantly reduced in the case of cell carrying shRNA construct targeting HDAC7 encoding gene when compared to the parental Panc-1 tumor cells (p = 0.0015) at 48 h and 96 h (p = 0.0021). This study strongly support the notion that HDAC7play a role in pancreatic adenocarcinoma progression.

Results in Immunology, 2013

Tumor Protein 53-Induced Nuclear Protein 1 (TP53INP1) plays an important role during cell stress ... more Tumor Protein 53-Induced Nuclear Protein 1 (TP53INP1) plays an important role during cell stress response in synergy with the potent "genome-keeper" p53. In human, the gene encoding TP53INP1 is expressed at very high level in some pathological situations, such as inflammation and prostate cancer (PC). TP53INP1 overexpression in PC seems to be a worse prognostic factor, particularly predictive of biological cancer relapse, making TP53INP1 a relevant specific target for molecular therapy of Castration Resistant (CR) PC. In that context, detection of TP53INP1 in patient biological fluids is a promising diagnostic avenue. We report here successful development of a new Enzyme-Linked Immunosorbent Assay (ELISA) detecting TP53INP1, taking advantage of molecular tools (monoclonal antibodies (mAbs) and recombinant proteins) generated in the laboratory during the course of basic functional investigations devoted to TP53INP1. The ELISA principle is based on a sandwich immunoenzymatic system, TP53INP1 protein being trapped by a first specific mAb coated on microplate then recognized by a second specific mAb. This new assay allows specific detection of TP53INP1 in serum of several PC patients. This breakthrough paves the way towards investigation of a large cohort of patients and assessment of clinical applications of TP53INP1 dosage.

Journal of Clinical Investigation, 2014

Oncotarget, Jan 3, 2014

Pancreatic Ductal Adenocarcinoma (PDAC) is a disease with a great heterogeneity in the response t... more Pancreatic Ductal Adenocarcinoma (PDAC) is a disease with a great heterogeneity in the response to treatments. To improve the responsiveness to treatments there are two different approaches, the first one consist to develop new and more efficient drugs that intent to cure all patients and the second one is to use already-approved drugs, alone or in combination, but selecting beforehand the most sensitive patients. In this work we explored the efficiency of the second possibility. We developed a collection of 17 PDAC samples collected by Endoscopic Ultrasound-Guided Fine-Needle Aspiration (EUS-FNA) or surgery and preserved as xenografts and as primary cultures. This collection was characterized at molecular level by a transcriptomic analysis using an Affymetrix approach. In this paper we present data demonstrating that a subgroup of PDAC responds to low doses of 5-aza-dC. These tumors show a specific RNA expression profile that could serve as a marker, but there is no correlation wit...

PLoS ONE, 2014

ArgBP2 (Arg-Binding Protein 2/SORBS2) is an adaptor protein involved in cytoskeleton associated s... more ArgBP2 (Arg-Binding Protein 2/SORBS2) is an adaptor protein involved in cytoskeleton associated signal transduction, thereby regulating cell migration and adhesion. These features are associated with its antitumoral role in pancreatic cancer cells. Tyrosine phosphorylation of ArgBP2, mediated by c-Abl kinase and counterbalanced by PTP-PEST phosphatase, regulates many of its interactions. However, the exact mechanisms of action and of regulation of ArgBP2 remain largely unknown. We found that ArgBP2 has the capacity to form oligomers which are destabilized by tyrosine phosphorylation. We could show that ArgBP2 oligomerization involves the binding of one of its SH3 domains to a specific proline rich cluster. ArgBP2 self-association increases its binding to some of its molecular partners and decreased its affinity for others. Hence, the phosphorylation/oligomerization state of ArgBP2 directly regulates its functions by modulating its adaptive capabilities. Importantly, using a human pancreatic cancer cell model (MiaPaCa-2 cells), we could validate that this property of ArgBP2 is critical for its cytoskeleton associated functions. In conclusions, we describe a new mechanism of regulation of ArgBP2 where tyrosine phosphorylation of the protein interfere with a SH3 mediated self-interaction, thereby controlling its panel of interacting partners and related functions.

PLoS ONE, 2014

Background: The pancreatitis-associated protein (PAP) is increased in the serum of active inflamm... more Background: The pancreatitis-associated protein (PAP) is increased in the serum of active inflammatory bowel disease (IBD) patients and its levels seem to be correlated with disease activity. Our aim was to evaluate the usefulness of serum and fecal PAP measurements to predict relapse in patients with inactive IBD.

Pancreas, 1991

Expression of the c-myc and H-ras oncogenes, and of several genes specifically expressed in adult... more Expression of the c-myc and H-ras oncogenes, and of several genes specifically expressed in adult rat pancreas was investigated by monitoring changes in corresponding mRNA concentrations, by dot-blot hybridization, during the early phase of regeneration following subtotal pancreatectomy. The oncogenes c-myc and H-ras were overexpressed after 12-24 and 48 h, respectively, then returned to basal levels. The concentrations of mRNAs encoding amylase, chymotrypsinogen B, and trypsinogen I decreased during the regeneration time. By contrast, proinsulin I mRNA concentration was increased at 12-48 h after surgical resection, and actin mRNA concentration was increased at 12-48 h after surgical resection, and actin mRNA concentration was increased at 12 h after subtotal pancreatectomy and remained elevated thereafter. We concluded that regeneration after subtotal pancreatectomy is accompanied by repression of certain genes that are expressed in differentiated pancreatic tissue, and that derepression of other genes may be necessary for starting and/or maintaining the process of pancreatic regeneration.

Journal of Cellular Physiology, 2009

The stress protein p8 is a small, highly basic, unfolded, and multifunctional protein. We have pr... more The stress protein p8 is a small, highly basic, unfolded, and multifunctional protein. We have previously shown that most of its functions are exerted through interactions with other proteins, whose activities are thereby enhanced or repressed. In this work we describe another example of such mechanism, by which p8 binds and negatively regulates MSL1, a histone acetyl transferase (HAT)-associated protein, which in turn binds the DNA-damage-associated 53BP1 protein to facilitate DNA repair following DNA g-irradiation. Contrary to the HAT-associated activity, MSL1-dependent DNA-repair activity is almost completely dependent on 53BP1 expression. The picture that has emerged from our findings is that 53BP1 could be a scaffold that gets the HAT MSL1-dependent DNA-repair activity to the sites of DNA damage. Finally, we also found that, although p8 expression is transiently activated after g-irradiation, it is eventually submitted to sustained down-regulation, presumably to allow development of MSL1-associated DNA-repair activity. We conclude that interaction of MSL1 with 53BP1 brings MSL1-dependent HAT activity to the vicinity of damaged DNA. MSL1-dependent HAT activity, which is negatively regulated by the stress protein p8, induces chromatin remodeling and relaxation allowing access to DNA of the repair machinery.

Journal of Cardiac Failure, 2009

Journal of Biological Chemistry, 2013

The function of Krüppel-like factor 11 (KLF11) in the regulation of metabolic pathways is conserv... more The function of Krüppel-like factor 11 (KLF11) in the regulation of metabolic pathways is conserved from flies to human. Alterations in KLF11 function result in maturity onset diabetes of the young 7 (MODY7) and neonatal diabetes; however, the mechanisms underlying the role of this protein in metabolic disorders remain unclear. Here, we investigated how the A347S genetic variant, present in MODY7 patients, modulates KLF11 transcriptional activity. A347S affects a previously identified transcriptional regulatory domain 3 (TRD3) for which co-regulators remain unknown. Structure-oriented sequence analyses described here predicted that the KLF11 TRD3 represents an evolutionarily conserved protein domain. Combined yeast two-hybrid and protein array experiments demonstrated that the TRD3 binds WD40, WWI, WWII, and SH3 domain-containing proteins. Using one of these proteins as a model, guanine nucleotide-binding protein β2 (Gβ2), we investigated the functional consequences of KLF11 coupling to a TRD3 binding partner. Combined immunoprecipitation and biomolecular fluorescence complementation assays confirmed that activation of three different metabolic G protein-coupled receptors (β-adrenergic, secretin, and cholecystokinin) induces translocation of Gβ2 to the nucleus where it directly binds KLF11 in a manner that is disrupted by the MODY7 A347S variant. Using genome-wide expression profiles, we identified metabolic gene networks impacted upon TRD3 disruption. Furthermore, A347S disrupted KLF11-mediated increases in basal insulin levels and promoter activity and blunted glucose-stimulated insulin secretion. Thus, this study characterizes a novel protein/protein interaction domain disrupted in a KLF gene variant that associates to MODY7, contributing to our understanding of gene regulation events in complex metabolic diseases.