The Cell Stress team focuses on understanding the genetic program for pancreatic cancer initiation, progression and metastasis formation.
Why we study this cancer?
Because, i/ although it has the 9th position in frequency, among the solid cancers, it is the 4th cause of death by cancer; ii/ pancreatic cancer has a ratio « incidence/death » of almost 1, that signify that every new patient diagnosed of this pathology will death of this disease; iii/ the 5 years survival is below 3%; iv/ the median survival of patients with this tumor is 6 months after its diagnosis; v/ surgery, which is the only therapeutic possibility to increases the survival, is available for only 15% of patients.
Why are these data so negative ? Probably, because the own characteristics of the PDAC’s. Our projects are covering several complementary aspects of the pancreatic cancer.
In fact, we are :
- studying the function of several genes involved in early lesions (PanINs) development; Nelson Dusetti
- studying proteins with tumor suppressive activity; Alice Carrier
- analyzing the metabolic changes occurring in transformed pancreatic cells; Sophie Vasseur
- screening novel antitumoral compounds synthesized by us and studying their mechanism of action; Juan Iovanna
- studying the role of the over-expressed stress proteins in pancreatic cancer cells; Juan Iovanna
- dissecting the molecular dialogue established between the stroma components and the transformed pancreatic cancer cells; Richard Tomasini
- analyzing the mechanism of the endothelial-to-mesenchymal transition that occurs in pancreatic cancer; Roselyne Tournaire
- developing all necessary tools for studying all known post translational modifications in pancreatic cancer cells; Philippe Soubeyran
- developing a project, which we named PaCaOmics, in which we will study the genomics, transcriptomics, epigenetics and proteomics aspects of the primary culture of the pancreatic cancer cells obtained by sonoendoscopy with biopsy and/or by surgery; Stéphane Garcia & Juan Iovanna.
To these ends, we have developed several sophisticated molecular, cellular and animal tolls such as vectors of expression (plasmids, retrovirus, letivirus, etc), complex co-culture systems mimicking the tumor microenvironment, some transgenic, KO, KI and immunodeficient animal models of pancreatic cancer, a platform for middle throughput screening of protein-protein interaction based on an original yeast two hybrid system, a platform for high throughput screening of inhibitor of protein-protein interaction based on the BRET approach and a cell culture platform on ISO9001 standard.
Our laboratory is about 40 people, including scientists, oncologists, gastroenterologists, surgeons, pathologists, informaticians, several engineers and technicians and post doc and PhD students.
Tumor suppression is a complex network of molecular and cellular processes leading to the reduction of pro-tumoral cell damage and/or removal of damaged or tumoral cells. These processes are activated in stressful conditions such as nutrient, oxidative or inflammatory stress.
My group is interested in studying the mechanisms underlying tumor suppression. In this context, our research has highlighted the tumor suppressive activity of two proteins initially identified as highly expressed in the thymus: the stress factor TP53INP1 (Tumor Protein 53-Induced Nuclear Protein 1) and the protease TSSP (Thymus-Specific Serine Protease).
Our functional genomics studies aimed at exploring the function of both proteins at the molecular and cellular level. In particular, we analyzed their impact on the cellular dysfunctions sustaining tumoral development, by the use of pancreatic and colorectal induced tumorigenesis models in deficient mice for each of these proteins (generated in our laboratory). Our studies demonstrated that these proteins are involved in tumor suppression through distinct mechanisms. In the case of TP53INP1, we evidenced its activity in biological processes that are affected in cancer cells (proliferation, apoptosis, migration, angiogenesis, genetic instability), tightly linked with its contribution in cell redox status regulation. Two major mechanisms by which TP53INP1 plays this regulatory function have been unveiled: (1) TP53INP1 regulates the transcriptional activity of p53 in the nucleus, and (2) TP53INP1 contributes to mitophagy, a process that ensures the quality control of the mitochondrial compartment by avoiding the accumulation of damaged mitochondria that produce an excess of pro-tumoral ROS (Reactive Oxygen Species).
In the case of TSSP, we demonstrated its involvement in MHC classII antigen presentation triggering CD4+ T cell differentiation in the thymus, thus impacting the generation of a fully efficient T lymphocytes repertoire against tumoral development.
These studies improve the full understanding of cancer development, which is required for developing novel avenues in cancer prevention.
Currently, we are developing a project which aims at deciphering the impact of mitochondrial alterations in pancreatic cancer cells aggressiveness and resistance to chemo- and radio-therapy. The Pancreatic Ductal AdenoCarcinoma (PDAC) is resistant to currently available treatments. Despite progress in our understanding of the physiopathology of this cancer, many aspects remain poorly understood, which impedes the development of novel therapeutic strategies. Among these strategies, targeting metabolic dysregulations of cancer cells is promising. In particular, the mitochondrial metabolism remains poorly explored in cancers despite the central role of these organelles in cell bioenergetics and apoptosis. The aims of our ongoing project are to decipher mitochondrial dysregulations in PDAC tumors, to correlate these alterations to tumor growth and therapeutic resistance, and to develop preclinical assays targeting mitochondria.
Pancreatic cancer develops silently without any symptoms. When it is diagnosed metastases are already spread or will appear shortly afterwards. In recent decades the scientific community made a considerable effort searching for treatements but remains unable to offer an effective therapy.
We believe that an original alternative is to act before cancer is settled.
Since 2001 our team focuses on molecules and cellular phenomena that precede the accumulation of genetic and epigenetic changes which characterize the process of pancreatic carcinogenesis. Few molecules involved in these early phenomena have been described so far despite the fact that they are of diagnostic and therapeutic interest.
The purpose of our team is to identify and functionally characterize these molecules and in this way to clarify cellular phenomena that are at the origin of this devastating tumor. Two molecules are at the heart of our current research, TP53INP1 (Tumor Protein 53 Induced Nuclear Protein 1) and the oncogenic microRNA miR-155.
We have shown that these two molecules are associated operating early in the pancreatic tumor development. More interestingly, the modulation of their expression in tumor cells can block their growth. We also identified their mechanisms of action and their involvement in cellular phenomena as varied as the regulation of free radicals, cell migration, autophagy, apoptosis and cell cycle arrest.
Our goal is, through these molecules and their associated processes, to identify new diagnostic and therapeutic targets which acting as earliest as possible in pancreatic carcinogenesis provide to clinicians an effective solution against this cancer.
The protein Nupr1/p8:
In the past we have shown that expression of this gene is necessary for tumor development. Recently, we were able to assign a major role in the regulation of epithelial-to-mesenchymal transition (EMT).
In particular, we demonstrated that expression of Nupr1/p8 is involved in a novel mechanism of cell death called entosis or cellular cannibalism. We have partially dissected the molecular mechanism of this new function of Nupr1/p8 and explored the involved pathways.
Finally, we demonstrated that expression of Nupr1/p8 is essential for the cellular response to nutrient deprivation or hypoxia (metabolic stress), the mechanism involved is dependent of the NFkB alternative (RelB), but not of the classical NFkB pathway (p65). We are currently fully characterizing this very original mechanism.
The PAP protein:
We have demonstrated that the interaction of PAP with its receptor activates, on one hand, the Jak-STAT3-SOCS3 and, on the other hand, inhibits the activation of NFkB. These two pathways appear to be involved in the anti-inflammatory effect of PAP.
Because PAP is a secretory protein and we demonstrated the existence of a specific receptor, the PAP-receptor could be a new target for treating certain inflammatory diseases. We are characterizing and trying to clone it.
We demonstrated that expression of VMP1 is “necessary and sufficient” to trigger autophagy. Overexpression of VMP1 induces vacuole formation while the use of a siRNA against VMP1 prevents the recruitment of LC3 and vacuole formation induced by nutrient deprivation or rapamycin treatment.
Then, we developed a transgenic mouse in which overexpression of VMP1 was induced in the pancreas and validated our in vitro studies.
Development of new small anticancer compounds:
In collaboration with a team of chemists from the CNRS we are interested in developing new compounds with antitumor activity in pancreatic cancer. Chemists have synthesized hundreds of novel compounds and we have systematically screened their activity in vitro and in vivo.
Among these molecules, we identified two compounds, structurally related, whose activity is higher than that of gemcitabine in vitro as well as in vivo. Our work is currently focusing on optimizing the structure of these molecules and actively researching on their mechanism of action.
ArgBP2: a scaffold protein in pancreatic cancer:
ArgBP2, a member of the SoHo family of adapter proteins, is a regulator of actin-dependent processes such as cell adhesion and migration.
We previously showed that by regulating adhesion and migration of pancreatic cancer cells, ArgBP2 is endowed with an anti-tumoral function. We could show that part of the molecular mechanism involved the interaction of ArgBP2 with the Arp2/3 activator WAVE1, the tyrosine phosphatase PTP-PEST, the tyrosine kinase c-Abl, and more recently CIP4.
The control of cell migration being an important issue in tumor treatment, our findings suggest that ArgBP2-dependent signaling pathways represent potential targets for the development of therapeutic strategies, and highlight the importance of elucidating its molecular mechanisms of cytoskeletal regulation.
Therefore, our goal is to determine the precise role of ArgBP2 within the control of these processes. To do so, we are studying the significance of the interaction of ArgBP2 with several new ArgBP2 associated proteins we identified by using yeast two-hybrid screens.
Ubiquitination and therapeutic escape:
Characterized by a 5 years survival rate of less than 5% the pancreatic cancer (pancreatic adenocarcinoma) remains one of the cancers with the worst outcome. This situation is notably due to the exceptional resistance of pancreatic tumors to conventional anticancer therapies. We think that we have to use original approaches to discover new fighting tools.
Ubiquitination is a post-translational modification process known for several tenths of years. However, this is only these last years that the great potential of ubiquitination to regulate cellular functions has been revealed. We think, and some data confirm it, that defects in ubiquitination play an important role in tumor development and resistance to chemo and radiotherapies.
We are trying to identify the proteins which ubiquitination is modified when pancreatic cancer cells undergo anti-cancer treatments. Then we are studying all candidate proteins by evaluating their importance, and the importance of their ubiquitination, regarding the resistance of pancreatic cancer cells.
Then we try to depict the molecular mechanisms responsible for the changing in ubiquitination of these candidate proteins.This should enable us to develop molecules capable to inhibit these modifications in vitro and importantly in vivo.
Our goal will be then to test these molecules upon the resistance of pancreatic cancer cells.
Despite advances in conventional therapy in the last 20 years, the 5-year survival of many cancer patients is unchanged, illustrating an unmet clinical need for new therapeutic approaches. Among cancers in critical clinical needs, pancreatic ductal adenocarcinoma (PDAC) is the most intractable with a 5-year survival below 6 months and the status of most fatal disease among solid cancer (based on the ratio “Cases/Death”).
Regarding our understanding of pancreatic tumorigenesis, it was hypothesized that the presence of a prominent non-tumoral cell compartment within the tumor (a main characteristic of PDAC) is directly impacting on such clinical outcomes. Although for a long time considered as a simplex support matrix for the development of tumoral cells, this “PDAC Stromal Compartment” is actually a known player of tumor evolution and patient fate.
We and others suppose that, by dialoguing with cancer cells (through cell-cell interactions or via secreted proteins), stromal cell compartment influences tumor cell biology by modifying processes as chemoresistance ability, metabolism adaptation, evasion processes or epithelial-to-mesenchymal transition.
However, beyond the presence of an important stromal compartment, the very unique characteristic of PDAC is the tremendous neural compartment remodeling observed within PDAC. This PDAC Associated Neural Remodeling (PANR) consists in both concepts of perineural invasion and neural remodelling (Fig. 1), and possesses a high correlation with local recurrence of PDAC at primary site after surgical removal of primary tumor, as well as with local/distant invasion and neuropathic associated pain.
Regarding the actual known implication of stromal compartment on PDAC biology, we suppose that the intra-tumoral microenvironment has an active and efficient role on the neural compartment remodeling and its implication in tumoral fate. However, it is not clear what factors from the tumor microenvironment promote this PANR phenotype nor the precise signaling pathway involved.
Our research is focused on the determination of a “stromal PDAC signature” and its specific components involved in PANR, through combinatory uses of human and relevant mice models (pancreatic driven Kras-activated mice combined to various deficient mice models as TAp73 or p53).
Indeed, the challenge is to block the cancer-promoting function of these and enhance the anti-tumor effects of existing therapies. Such improvement could permit to unravel novel diagnostic, prognostic, and therapeutic options making the use of such components involved in PANR a new tool-box against this deadly malignancy.
Stromal cells provide a microenvironment which is essential for tumoral growth, invasion and metastasis. Fibroblasts are essential components of this microenvironment. Activated fibroblasts (also called myofibroblasts or CAFs for Cancer-Associated Fibroblasts) are localized in close proximity to cancer cells. They are able to modify the phenotype of epithelial cells either by direct cell-cell contact, or through soluble factors, or by modifying the extracellular matrix. The interaction between myofibroblasts and cancer cells is essential for tumor growth and for the formation of metastasis, and the presence of such cells is associated with a poor clinical prognosis.
Endothelial-mesenchymal transition (EMT) is a process by which endothelial cells disaggregate; endothelial cells change shape and migrate to invade surrounding tissues. EMT is characterized by the loss of endothelial cell markers and the acquisition of mesenchymal cell markers: this process has been reported o occur during embryonic development and in cases of fibrosis.
Mesenchymal cells derived from endothelial cells behave like fibroblasts in damaged tissues.
We are interested in the receptors involved in angiogenesis and more specifically in Tie family receptors, Tie1 and Tie2, which are involved in blood vessel maturation.
We have recently demonsrated, first that the absence of Tie1 in endothelial cells leads to EMT, and second, that EMT occurs in human pancreatic tumors, including in humans. EMT thus contributes to generate the pool of fibroblasts associated with cancer. These data suggest that therapeutic strategies targeting EMT could offer new perspectives for the treatment of pancreatic cancer. Our aims are to analyze the mechanisms involved in EMT and determine the impact of tumor microenvironment on EMT.
Nos objectifs sont d’étudier les mécanismes impliqués au cours de l’EndMT et de déterminer l’impact du microenvironnement présent dans les tumeurs sur la transition endothélio-mésenchymateuse.
Pancreatic ductal adenocarcinoma remains one of the most lethal of all solid tumors with an overall five-year survival rate of only 3–5%. Its aggressive biology and resistance to conventional and targeted therapeutic agents lead to a typical clinical presentation of incurable disease once diagnosed. Presence of a prominent non-tumoral cell compartment within the tumor (a main characteristic of PDAC) is directly impacting on patient clinical outcomes.
In PDAC, cancer cells are “isolated” by a fortress of stromal cells, composed of very few blood vessels, which distorts the normal parenchymal architecture of pancreas and limits the oxygen and nutrient diffusion in the tissue. This severe hypoxic environment at the site of the tumor provides a strong selective pressure able to regulate tumor cell growth and to favor survival of the most aggressive malignant cells.
Another hallmark of PDAC is cachexia, defined as an unintend weight loss of 10% or more of the stable weight over a period of 6 months, and associated with loss of fat and muscle tissue. Pancreatic cancer-patients with cachexia often have an elevated resting energy expenditure (REE), a higher rate of more progressed tumor stages and have significantly reduced survival. Hence, this tumor must harbor metabolic pathways which are probably tied in a complex inter-organ dialogue during its development and illustrate this cancer as a real metabolic disease.
One of the major consequences of intra-tumoral hypoxia, combined with oncogene signaling, is the cell metabolic switch occurring in order to meet the requirements of tumor proliferation under low oxygen and low nutrient supply because of lack of vasculature. Since decades it has been accepted that tumor cells display fundamental changes in pathways of energy metabolism and nutrient uptake, and that alterations in cellular metabolism contribute to malignant phenotype. Cancer cells differ from healthy cells due to a plethora of molecular changes which are mechanistically linked to metabolic reprogramming. Metabolic signature of each type of tumor is then strongly associated to oncogenic mutations occurring in the tumor associated cells.
Our project is based on the concept that pancreatic cancer cells are probably metabolically flexible.
However, molecular changes leading to metabolic adaptations of pancreatic cancer cells remain unclear. We propose innovative strategies to abolish PDAC progression, based on the concept that targeting molecules belonging to a specific « PDAC Metabolic Signature » can be a new relevant therapeutic option to treat PDAC.
Based on the metabolic transcriptomic signature of PDAC, we propose strategies targeting molecules mainly involved in lipid, amino-acid and glucose metabolic pathways, 3 essential metabolic processes for energy production and biosynthesis during tumor growth.
Combined therapies to avoid resistance to a single anti-metabolic drug is challenging but appears to be a good strategy to counteract the tumor cell metabolism plasticity and pancreatic tumor progression.