Roles of the transcription factors HNF6 and Sox9 in the initiation of metaplastic and neoplastic lesions of the pancreas

Pancreatic ductal adenocarcinoma originates from acinar cells that undergo acinar-to-ductal metaplasia (ADM) and evolve to pancreatic intraepithelial neoplasia (PanIN), and eventually to invasive cancer. Ductal transcription factors are induced in ADM but the roles of these transcriptional regulators, in particular Hepatocyte Nuclear Factor (HNF) 6 and SRY-related HMG-box (Sox) 9, have not yet been investigated. Here we show that HNF6 and SOX9 are expressed in human and mouse ADM. Using in vitro and in vivo gain- and loss-of-function experiments, we demonstrate that both factors are essential for ADM induced by pancreatic duct ligation-mediated pancreatitis or by exposure to the carcinogen 9,10-dimethyl-1,2-benzanthracene. HNF6 and, to a lesser extent, Sox9 are 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. SOX9, but not HNF6, is expressed in human and mouse PanIN lesions. Using in vitro and in vivo loss-of-function experiments, we show that Sox9 is required for development of PanIN from acinar cells harboring an oncogenic Kras mutation and exposed to an inflammatory stimulus. Sox9 stimulates expression of several metaplastic genes (cytokeratin 19, clusterin, ezrin) to promote ADM. It further stimulates the activity of the Erythroblastic leukemia viral oncogene homolog (ErbB) signaling pathway, which is required for initiation and progression of pancreatic ductal adenocarcinoma. Together, our findings demonstrate that HNF6 and Sox9 promote pancreatitisdriven ADM and are biomarkers of ADM. Also, Sox9 acts as an oncogene in pancreatic cancer by promoting tumor progression via stimulation of the ErbB signaling pathway.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 201

Membrane progestin receptors α and γ in renal epithelium

AbstractSex 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 mPRα and γ 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 Ca2+ release from internal stores in native kidney structures and 3/ the cellular localization of mPRα and its molecular determinants in heterologous expression system. We observed that 1/ mPRα expression is restricted to proximal tubules of both male and female mice whereas mPRγ exhibits a much broader expression all along the nephron except the glomerulus, 2/ mPRα and γ are not localized at the plasma membrane in native kidney, 3/ this expression does not permit either progesterone-induced ERK phosphorylation or Ca2+ release and 4/ in HEK transfected cells, mPRα 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

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

Abstract 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

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

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

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