A reversible epigenetic memory of inflammatory injury controls lineage plasticity and tumor initiation in the mouse pancreas

Inflammation is essential to the disruption of tissue homeostasis and can destabilize the identity of lineage-committed epithelial cells. Here, we employ lineage-traced mouse models, single-cell transcriptomic and chromatin analyses, and CUT&TAG to identify an epigenetic memory of inflammatory injury in the pancreatic acinar cell compartment. Despite resolution of pancreatitis, our data show that acinar cells fail to return to their molecular baseline, with retention of elevated chromatin accessibility and H3K4me1 at metaplasia genes, such that memory represents an incomplete cell fate decision. In vivo, we find this epigenetic memory controls lineage plasticity, with diminished metaplasia in response to a second insult but increased tumorigenesis with an oncogenic Kras mutation. The lowered threshold for oncogenic transformation, in turn, can be restored by blockade of MAPK signaling. Together, we define the chromatin dynamics, molecular encoding, and recall of a prolonged epigenetic memory of inflammatory injury that impacts future responses but remains reversible.

Abstract PR008: An epigenetic memory of inflammation controls context-dependent lineage plasticity and KRAS-driven tumorigenesis in the pancreas

Tissue homeostasis depends on responses to environmental insults to restore cellular phenotype, microenvironment composition, and tissue architecture. Inflammation is essential to the disruption of homeostasis, and, in the pancreas, can destabilize the identity of terminally differentiated acinar cells. Herein we employ lineage-traced mouse models to delineate the chromatin dynamics that accompany the cycle of metaplasia and regeneration following pancreatitis, and unveil the presence of an epigenetic memory of inflammation in the pancreatic acinar cell compartment. We observe that despite histologic resolution of pancreatitis, acinar cells fail to return to their molecular baseline after several months, representing an incomplete cell fate decision. In vivo, this epigenetic memory controls lineage plasticity, with diminished metaplasia in response to a second inflammatory insult but increased tumorigenesis with an oncogenic Kras mutation. We demonstrate that both persistent chromatin and transcriptional changes constituting memory are recalled with oncogenic stress. Together, our findings define a capacity for an environmental insult to control future cell-fate decisions in a context-dependent manner. The ability of epigenetic memory to potentiate tumor initiation both broadens the relationship between inflammation and cancer and raises the possibility that inducing epigenetic ‘amnesia’ of an inflammatory insult could be leveraged as a novel cancer prevention strategy.

Citation Format: David J. Falvo, Adrien Grimont, Paul Zumbo, Julie L. Yang, Alexa Osterhoudt, Grace Pan, Andre F. Rendeiro, John Erby Wilkinson, Friederike Dundar, Olivier Elemento, Rhonda K. Yantiss, Doron Betel, Richard Koche, Rohit Chandwani. An epigenetic memory of inflammation controls context-dependent lineage plasticity and KRAS-driven tumorigenesis in the pancreas. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr PR008.

Abstract B055: Rac1 is essential for the maintenance of established KrasG12D-driven pancreatic ductal adenocarcinoma through senescence escape

The most prominent KRAS variants (G12D, G12V, G12R) that together represent around 80% of patients with pancreatic ductal adenocarcinoma (PDAC) are so far undruggable. While the role of several Kras mediators have been characterized in the initiation of PDAC, very little is known about the hierarchy of Kras effectors in the maintenance of the tumor. In recent years, strategies targeting the effectors downstream of mutant KRAS have offered scope for combined inhibition of EGFR and CRAF or MEK/RAF. However, these studies, unfortunately, have been limited by either narrow interrogation of downstream effectors in mouse models, or by the use of two-dimensional cell culture systems that may not recapitulate dependencies of the tumor in situ, respectively. To systematically interrogate the potential molecular dependencies in pancreatic tumor maintenance across several combinations of driver mutations, we have deployed in vitro and in vivo approaches in which we have selectively targeted key mediators of known KRAS-dependent pathways. These include Craf, Braf, PI3K, RalA, RalB, and Rac1, for which we have used inducible GFP-coupled shRNAs in 3D mouse and human tumor organoids harboring KrasG12D and p53R172H mutation. Using competition, cell cycle, and volumetric assays, we have uncovered that Rac1, Kras, and Craf are essential to the growth of PDAC organoids, whereas Braf, PI3K, RalA and RalB are dispensable. Interestingly, Rac1 depletion led to the strongest phenotype among the Kras mediators with a reduction of macropinocytosis, cell migration and colony formation in vitro. In an orthotopic pancreatic injection model, we observed that Rac1 inhibition in vivo led to diminished primary tumor growth, improved survival, and a reduction of metastatic incidence and outgrowth. In parallel, we performed RNA-sequencing on Kras-, Craf-, Rac1-, RalA- and Renilla-depleted organoids and found that Rac1 depletion rewires tumor cells to acquire a more PanIN-like phenotype, highlighting the importance of these proteins for the maintenance of PDAC cells. We also identify in Rac1- depleted cells evidence of deregulation of reactive oxygen species (ROS) and induction of a senescence-associated secretory phenotype (SASP) compared to control organoids. With a cytokine and chemokine array, we confirmed the increase of SASP chemokines (Csf3, Cxcl1, Cxcl2 and Cxcl5) and also detected bona fide senescence via SA-βgal staining. Finally, using several Rac1 inhibitors, we recapitulate the importance of Rac1 in PDAC growth. These data suggest that among the pleiotropic signaling downstream of mutant Kras, Rac1 is a critical node in PDAC maintenance that promotes tumor cell proliferation and senescence escape. Our findings point towards future efforts to couple Rac1 inhibition to define therapeutic synergies with immunotherapy and/or radiation. All together, we anticipate these findings can inform the subsequent development of novel therapies to address these vulnerabilities.

Citation Format: Adrien Grimont, David J. Falvo, Paul Zumbo, Grace Pan, John Nguyen, Rhonda K. Yantiss, Doron Betel, Laura Martin, Steven D. Leach, Rohit Chandwani. Rac1 is essential for the maintenance of established KrasG12D-driven pancreatic ductal adenocarcinoma through senescence escape [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B055.

Abstract PR009: An epigenetic memory of inflammation controls context-dependent lineage plasticity in the pancreas

Inflammation is essential to the disruption of tissue homeostasis, and, in the pancreas, can destabilize the identity of terminally differentiated acinar cells. A longstanding question has been whether a history of past injuries instructs subsequent homeostatic responses to future stimuli – despite being distantly separated in time. Thus, we employ here Mist1-CreERT2; LSL-tdTomato lineage-tracing mice to investigate the long-term effects of a transient inflammatory episode on pancreatic tissue homeostasis. We delineate the chromatin dynamics that accompany the cycle of metaplasia and regeneration following pancreatitis, and reveal that the pancreatic acinar cell compartment durably retains specific inflammation-induced epigenetic changes even 18-weeks after exposure to the original inflammatory stimulus. We observe that despite histologic resolution of pancreatitis, acinar cells fail to return to their molecular baseline after several months, representing an incomplete cell fate decision. Motif analysis demonstrates the enrichment of AP-1/Fra1 motifs at these persistently accessible memory regions—a transcriptional effector activated downstream of the Ras/MAPK pathway. This epigenetic memory controls lineage plasticity, with diminished metaplasia in response to a second inflammatory insult but increased tumorigenesis with an oncogenic Kras mutation. We demonstrate that pancreatic acinar cells exhibit rapid malignant transformation upon re-challenge with oncogenic stress via inflammatory memory recall, with robust reactivation of genes associated with differentially accessible memory regions. Together, our findings define the dynamics and recall of an epigenetic memory of inflammation that impacts cell fate decisions in a context-dependent manner.

Citation Format: David J. Falvo, Adrien Grimont, Paul Zumbo, Julie L. Yang, Alexa Osterhoudt, Grace Pan, Andre F. Rendeiro, John E. Wilkinson, Friederike Dündar, Olivier Elemento, Rhonda K. Yantiss, Doron Betel, Richard Koch, Rohit Chandwani. An epigenetic memory of inflammation controls context-dependent lineage plasticity in the pancreas [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr PR009.

Abstract PR-005: Chromatin dynamics in vivo define coordinate functions of inflammation and mutant Kras in pancreatic tumorigenesis

Pancreatic cancer initiation features abundant rewiring of the normal acinar cell,. but little is known about the chromatin specification of pancreatic cell types and the epigenetic dysregulation of normal acinar cells in tumor initiation. To address these questions, we employed a lineage-traced autochthonous mouse model to examine systematically perturbed acinar cells. We coupled the spatiotemporal control of inflammation (via caerulein injections) with inducible oncogene activation (mutant Kras) in the adult mouse along with bulk RNA-seq and ATAC-seq to sorted acinar and acinar-derived cells. In addition, we generated Ptf1a-TdTomato mice to reliably sort pancreatic progenitors at e10.5 and e15.5. We observe that Kras activation alone does not disturb acinar cell chromatin nor the histologic appearance of the pancreas. By contrast, caerulein alters chromatin significantly in metaplasia and even in regeneration, with putative enhancers derepressed despite normal histology. In the context of Kras activation and caerulein administration, we find a broad and stable reorganization of chromatin, reflecting cooperativity between oncogenic stress and an inflammatory insult. We also find that in PanIN, the chromatin state bears few, if any, ductal, progenitor, or islet features and instead reflects a largely novel cell fate. To understand the dependencies of these findings on an inflammatory insult and mutant Kras, we leveraged temporal resolution of pancreatitis and the iKras system to define the reversibility of this epigenetic rewiring. Notably, neither resolution of inflammation nor withdrawal of mutant Kras expression are sufficient to revert an acinar cell to its initial chromatin state. Analysis of the acinar-derived cells undergoing the transition to PanIN reveals the induction of specific proliferative and progenitor master transcription factors and activation of associated transcriptional programs. In these data we also observe a specific unveiling of the AP-1 isoform Fra-1 (Fosl1) transcript, protein, and binding sites in chromatin. To address if Fra-1-associated alterations to chromatin are bona fide requirements for tumorigenesis, we coupled conditional Fra-1 knockout alleles with the iKras system, finding nearly complete ablation of PanIN in the absence of Fra-1. Together, our findings suggest that (1) loss of acinar cell identity is resistant to oncogenic stress and is susceptible to inflammation; (2) the acquired acinar cell fate reflects neither ‘pure’ metaplasia nor transdifferentiation nor dedifferentiation events, and (3) acinar cell regeneration is incomplete. In contrast to recent studies, we demonstrate that pancreatic tumorigenesis does not re-establish a progenitor cell fate, but hijacks the AP-1 transcription factors for tumor-specific genomic locations, with Fra-1 emerging as a dependency in tumorigenesis. Our data thus highlight the complexity of cell fate decisions in the preneoplastic pancreas and reveal key regulators of acinar cell identity.

Citation Format: David Falvo, Jason Pitarresi, Alexa Osterhoudt, Adrien Grimont, Ben Stanger, Steven D. Leach, Anil K. Rustgi, Rohit Chandwani. Chromatin dynamics in vivo define coordinate functions of inflammation and mutant Kras in pancreatic tumorigenesis [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PR-005.

Uncertain Beginnings: Acinar and Ductal Cell Plasticity in the Development of Pancreatic Cancer

The pancreas consists of several specialized cell types that display a remarkable ability to alter cellular identity in injury, regeneration, and repair. The abundant cellular plasticity within the pancreas appears to be exploited in tumorigenesis, with metaplastic, dedifferentiation, and transdifferentiation processes central to the development of pancreatic intraepithelial neoplasia and intraductal papillary neoplasms, precursor lesions to pancreatic ductal adenocarcinoma. In the face of shifting cellular identity, the cell of origin of pancreatic cancer has been difficult to elucidate. However, with the extensive utilization of in vivo lineage-traced mouse models coupled with insights from human samples, it has emerged that the acinar cell is most efficiently able to give rise to both intraductal papillary neoplasms and pancreatic intraepithelial neoplasia but that acinar and ductal cells can undergo malignant transformation to pancreatic ductal adenocarcinoma. In this review, we discuss the cellular reprogramming that takes place in both the normal and malignant pancreas and evaluate the current state of evidence that implicate both the acinar and ductal cell as context-dependent origins of this deadly disease.

Abstract B20: KrasG12D effector dependencies in the maintenance of pancreatic ductal adenocarcinoma

More than 90% of pancreatic ductal adenocarcinoma (PDAC) tumors in humans feature activating mutations in the proto-oncogene KRAS. In mice, KrasG12D mutation alone is sufficient for PanIN formation; when coupled with mutational inactivation of TP53 (Tp53R172H), PanIN formation is accelerated and these neoplastic lesions progress to invasive and metastatic disease at high frequency. Several groups have demonstrated that inactivation of mutant Kras in established PanIN and PDAC leads to redifferentiation and apoptosis of the tumor, respectively. More recently, several combinatorial genetic and pharmacologic strategies have been employed that highlight RAF kinases as key oncoeffectors for KRAS addiction, but that RAF inhibition alone demonstrates little efficiency against KRAS mutant tumors. Additionally, previous studies suggest a requirement for both C-raf and EGFR blockade or the combination of RAF-MEK or RAF-PI3K inhibitors to inhibit to tumor growth. However, a systematic evaluation of dependencies of Kras effectors in tumor maintenance has not been explicitly performed. To investigate effector dependencies in the KrasG12D setting, we have developed an organoid platform to generate isogenic lines bearing doxycycline-inducible small hairpin (sh)RNAs coupled to GFP inserted into mouse pancreatic tumor organoids derived from KPC mice. These shRNAs are directed against each of the major Kras effector molecules, including B-raf, C-raf, Pi3k, RalA, RalB, and Rac1, with Kras shRNAs and Renilla shRNA used as controls. We identified 2 effective shRNAs per target, with strong and durable inhibition of each protein observed after doxycycline treatment. To investigate the hierarchy of Kras effectors, we employed a competition assay of the shRNA organoids, and observed the drop-out of Kras, C-raf, and Rac1 shRNA-bearing tumor organoid lines. Cell number and volumetric analyses confirmed strong dependencies on Kras, C-raf, and Rac1. Chromatin accessibility and transcriptomic analyses of Kras- , C-raf- , and Rac1-depleted organoids revealed consensus features of abrogated tumor maintenance and key molecular nodes in tumor maintenance. Together, we have employed a mouse organoid platform to create a rigorous map of the requirements for the key effectors of mutant Kras, and to dissect the biologic mechanisms shared by effectors disruptive of the mutant Kras epigenetic and transcriptional landscape. In turn, we anticipate these findings can inform the subsequent development of novel therapies to address these vulnerabilities.

Citation Format: Adrien Grimont, Zhen Zhao, Steven D. Leach, Rohit Chandwani. KrasG12D effector dependencies in the maintenance of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B20.

PanIN Neuroendocrine Cells Promote Tumorigenesis via Neuronal Cross-talk

Nerves are a notable feature of the tumor microenvironment in some epithelial tumors, but their role in the malignant progression of pancreatic ductal adenocarcinoma (PDAC) is uncertain. Here, we identify dense innervation in the microenvironment of precancerous pancreatic lesions, known as pancreatic intraepithelial neoplasms (PanIN), and describe a unique subpopulation of neuroendocrine PanIN cells that express the neuropeptide substance P (SP) receptor neurokinin 1-R (NK1-R). Using organoid culture, we demonstrated that sensory neurons promoted the proliferation of PanIN organoids via SP-NK1-R signaling and STAT3 activation. Nerve-responsive neuroendocrine cells exerted trophic influences and potentiated global PanIN organoid growth. Sensory denervation of a genetically engineered mouse model of PDAC led to loss of STAT3 activation, a decrease in the neoplastic neuroendocrine cell population, and impaired PanIN progression to tumor. Overall, our data provide evidence that nerves of the PanIN microenvironment promote oncogenesis, likely via direct signaling to neoplastic neuroendocrine cells capable of trophic influences. These findings identify neuroepithelial cross-talk as a potential novel target in PDAC treatment. Cancer Res; 77(8); 1868–79. ©2017 AACR.

PanIN Neuroendocrine Cells Promote Tumorigenesis via Neuronal Cross-talk

Nerves are a notable feature of the tumor microenvironment in some epithelial tumors, but their role in the malignant progression of pancreatic ductal adenocarcinoma (PDAC) is uncertain. Here, we identify dense innervation in the microenvironment of precancerous pancreatic lesions, known as pancreatic intraepithelial neoplasms (PanIN), and describe a unique subpopulation of neuroendocrine PanIN cells that express the neuropeptide substance P (SP) receptor neurokinin 1-R (NK1-R). Using organoid culture, we demonstrated that sensory neurons promoted the proliferation of PanIN organoids via SP-NK1-R signaling and STAT3 activation. Nerve-responsive neuroendocrine cells exerted trophic influences and potentiated global PanIN organoid growth. Sensory denervation of a genetically engineered mouse model of PDAC led to loss of STAT3 activation, a decrease in the neoplastic neuroendocrine cell population, and impaired PanIN progression to tumor. Overall, our data provide evidence that nerves of the PanIN microenvironment promote oncogenesis, likely via direct signaling to neoplastic neuroendocrine cells capable of trophic influences. These findings identify neuroepithelial cross-talk as a potential novel target in PDAC treatment. Cancer Res; 77(8); 1868-79. ©2017 AACR.

Abstract A45: Targeting eIF4A dependent translation as therapeutics in pancreatic cancer

RNA translation is activated in aggressive pancreatic cancer and at the same time is also refractory to mTOR inhibition. We have used a translation inhibitor for eIF4A, RNA helicase that is downstream of mTOR signaling and can be functionally targeted in pancreatic cancer. We establish that Silvestrol and its analog CR-31B showed potent anti-tumor activity in pancreatic cancer cell lines in vitro and in vivo. Silvestrol/CR-31B reduced pancreatic cancer cells and organoids growth derived from mouse model of pancreatic cancer and human patient samples in vitro. Further we identify the genome wide translational targets of Silvestrol in pancreatic cancer cell line that lacks response to mTOR signaling through loss of EIF4EBP1. Silvestrol down regulate translation of many key oncogenes and others cellular factors involved in oncogenic signaling specific to pancreatic cancer. Silvestrol targets were also enriched for G-quadruplex structure in their 5' UTR. With this study we establish a new mechanism of targeting pancreatic cancer cells through translation inhibition and identify newer proteins as therapeutic targets that are regulated independent of mTOR signaling.

Citation Format: Kamini Singh, Nicolas Lecomte, Stefan Stark, Antonija Burčul, Grbovic-Huezo Olivera, Adrien Grimont, Agnes Viale, Prathibha Mohan, Man Jiang, Elisa Destanchia, Askan Gokce, Gunnar Rätsch, Steve D. Leach, Hans-Guido Wendel. Targeting eIF4A dependent translation as therapeutics in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A45.

SOX9 regulates ERBB signalling in pancreatic cancer development

OBJECTIVE

The transcription factor SOX9 was recently shown to stimulate ductal gene expression in pancreatic acinar-to-ductal metaplasia and to accelerate development of premalignant lesions preceding pancreatic ductal adenocarcinoma (PDAC). Here, we investigate how SOX9 operates in pancreatic tumourigenesis.

DESIGN

We analysed genomic and transcriptomic data from surgically resected PDAC and extended the expression analysis to xenografts from PDAC samples and to PDAC cell lines. SOX9 expression was manipulated in human cell lines and mouse models developing PDAC.

RESULTS

We found genetic aberrations in the SOX9 gene in about 15% of patient tumours. Most PDAC samples strongly express SOX9 protein, and SOX9 levels are higher in classical PDAC. This tumour subtype is associated with better patient outcome, and cell lines of this subtype respond to therapy targeting epidermal growth factor receptor (EGFR/ERBB1) signalling, a pathway essential for pancreatic tumourigenesis. In human PDAC, high expression of SOX9 correlates with expression of genes belonging to the ERBB pathway. In particular, ERBB2 expression in PDAC cell lines is stimulated by SOX9. Inactivating Sox9 expression in mice confirmed its role in PDAC initiation; it demonstrated that Sox9 stimulates expression of several members of the ERBB pathway and is required for ERBB signalling activity.

CONCLUSIONS

By integrating data from patient samples and mouse models, we found that SOX9 regulates the ERBB pathway throughout pancreatic tumourigenesis. Our work opens perspectives for therapy targeting tumourigenic mechanisms.

Abstract LB-73: SOX9 regulates EGFR/ERBB signaling in pancreatic cancer

The transcription factor SOX9 has recently been shown to have a role in the ontogenesis of pancreatic ductal adenocarcinoma (PDAC) through metaplastic changes in pancreatic acinar cells. Nevertheless, the mechanisms through which SOX9 operates remain to be explored.

We analyzed genomic and transcriptomic data from a cohort of surgically resected cases of PDAC (n=90) from the Australian Pancreatic cancer Genome Initiative (APGI). Genetic aberrations (mutation and copy number changes) in the SOX9 gene were found in 15% of patient tumors. Protein expression analysis revealed that most PDAC samples strongly express SOX9 protein and differential SOX9 expression correlates with patient survival. SOX9 gene expression was higher in the classical PDAC subtype, which relates with better patient outcome and increased response to epidermal growth factor receptor (EGFR)-directed therapy.

In patient tumors, we found that SOX9 expression correlates with expression of EGFR signaling pathway genes, including ErbB2. Analysis of patient-derived xenografts confirmed strong correlation of SOX9 and ErbB2 expression and manipulation of human tumor cell lines demonstrated that Sox9 regulates the expression of ErbB2.

We extended these findings by using a mouse model lacking pancreatic Sox9 expression where we found reduced expression of Egfr/ErbB signaling components. Sox9-deficient pancreatic acinar cells failed to generate PDAC precursor lesions and did not respond to EGF, indicating that Sox9 is required for Egfr/ErbB signaling pathway activity.

In conclusion, by using an integrative approach that combines human and mouse models data, we discovered a new function of SOX9 in the regulation of EGFR/ERBB signaling throughout pancreatic tumorigenesis. This provides a novel mechanistic insight of potential therapeutic significance for pancreatic cancer patients.

Citation Format: Andreia V. Pinho, Adrien Grimont, Mark J. Cowley, Cecile Augereau, Amanda Mawson, Marc Giry-Laterriere, Geraldine Van den Steen, Nicola Waddell, Marina Pajic, Christine Sempoux, Australian Pancreatic Cancer Genome Initiative, Jianmin Wu, Sean M. Grimmond, Andrew V. Biankin, Frederic P. Lemaigre, Patrick Jacquemin, Ilse Rooman. SOX9 regulates EGFR/ERBB signaling in pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-73. doi:10.1158/1538-7445.AM2014-LB-73

Role of the ductal transcription factors HNF6 and Sox9 in pancreatic acinar-to-ductal metaplasia

OBJECTIVE

Growing evidence suggests that a phenotypic switch converting pancreatic acinar cells to duct-like cells can lead to pancreatic intraepithelial neoplasia and eventually to invasive pancreatic ductal adenocarcinoma. Histologically, the onset of this switch is characterised by the co-expression of acinar and ductal markers in acini, a lesion called acinar-to-ductal metaplasia (ADM). The transcriptional regulators required to initiate ADM are unknown, but need to be identified to characterise the regulatory networks that drive ADM. In this study, the role of the ductal transcription factors hepatocyte nuclear factor 6 (HNF6, also known as Onecut1) and SRY-related HMG box factor 9 (Sox9) in ADM was investigated.

DESIGN

Expression of HNF6 and Sox9 was measured by immunostaining in normal and diseased human pancreas. The function of the factors was tested in cultured cells and in mouse models of ADM by a combination of gain and loss of function experiments.

RESULTS

Expression of HNF6 and Sox9 was ectopically induced in acinar cells in human ADM as well as in mouse models of ADM. HNF6 and, to a lesser extent, Sox9 were required for repression of acinar genes, for modulation of ADM-associated changes in cell polarity and for activation of ductal genes in metaplastic acinar cells.

CONCLUSIONS

HNF6 and Sox9 are new biomarkers of ADM and constitute candidate targets for preventive treatment in cases when ADM may lead to cancer. This work also shows that ectopic activation of transcription factors may underlie metaplastic processes occurring in other organs.

Membrane progestin receptors alpha and gamma in renal epithelium

Sex hormones have broader effects than regulating reproductive functions. Recent identification of membrane progestin receptors expressed in kidney prompted us to investigate their putative involvement in the renal effects of this hormone. We first focused our investigations on mPRalpha and gamma by analyzing three parameters 1/ their distribution along the mouse nephron and their subcellular location in native kidney, 2/ the ability of progesterone to stimulate ERK pathway and/or Ca(2+) release from internal stores in native kidney structures and 3/ the cellular localization of mPRalpha and its molecular determinants in heterologous expression system. We observed that 1/ mPRalpha expression is restricted to proximal tubules of both male and female mice whereas mPRgamma exhibits a much broader expression all along the nephron except the glomerulus, 2/ mPRalpha and gamma are not localized at the plasma membrane in native kidney, 3/ this expression does not permit either progesterone-induced ERK phosphorylation or Ca(2+) release and 4/ in HEK transfected cells, mPRalpha localizes in the endoplasmic reticulum (ER) due to a C-terminal ER retention motif (-KXX). Therefore, we have characterized mPRs in kidney but their role in renal physiology remains to be elucidated.