Proliferation Of Liver Progenitor Cells Research Articles

Yes-associated protein promotes the proliferation and differentiation of liver progenitor cells during liver fibrosis.

Liver fibrosis is closely related to the proliferation and differentiation of liver progenitor cells (LPCs). Yes-associated protein (YAP) is a key effector molecule of the Hippo signaling pathway and plays an important role in regulating cell proliferation and liver homeostasis. However, its role in LPCs proliferation and differentiation during liver fibrosis are not well understood. Using immunohistochemistry, immunofluorescence staining, quantitative PCR and Western blotting, we discovered that LPCs expansion and enhanced YAP expression in LPCs in either choline-deficient, ethionine-supplemented (CDE) diet or 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet-induced fibrotic mice, as well as in patients with liver fibrosis. By injecting adeno-associated virus vectors under the transcriptional control of Lgr5 promoter, we found that targeted knockdown of YAP in LPCs attenuated the CDE/DDC diet-induced ductular reaction and liver fibrosis. Using EdU incorporation and Cell Counting Kit-8 assays, we demonstrated that YAP can modulate LPCs proliferation. Importantly, spleen transplantation of YAP-overexpressing LPCs improved their ability to differentiate into hepatocytes and alleviated carbon tetrachloride-induced liver fibrosis. Collectively, our findings indicate that LPCs expansion and differentiation during liver fibrosis could be modulated by YAP, further suggesting the possibility of manipulating YAP expression in LPCs as a potential treatment for chronic liver diseases.

Association between liver progenitor cells and liver regeneration

The liver has a strong ability of regeneration and the remaining liver cells can quickly enter the replication state after acute liver injury or partial hepatectomy. In case of chronic liver injury or severe liver disease, liver progenitor cell (LPC)-mediated regeneration may play a major role in liver regeneration. At present, the presence of dual-energy LPCs in animals and humans has been confirmed by lineage tracing and single-cell sequencing, and many studies have shown that the degree of LPC proliferation is associated with the severity of liver injury. This article briefly describes the origin and activation of LPCs and the role and regulatory mechanism of LPCs in mediating liver regeneration in different types of liver injury, and it is pointed out that in-depth research is needed for LPCs in the future to provide a basis for the reconstruction of liver parenchyma and the treatment of advanced liver disease by LPC transplantation.

Farnesoid X Receptor Activation Impairs Liver Progenitor Cell-Mediated Liver Regeneration via the PTEN-PI3K-AKT-mTOR Axis in Zebrafish.

Following mild liver injury, pre-existing hepatocytes replicate. However, if hepatocyte proliferation is compromised, such as in chronic liver diseases, biliary epithelial cells (BECs) contribute to hepatocytes through liver progenitor cells (LPCs), thereby restoring hepatic mass and function. Recently, augmenting innate BEC-driven liver regeneration has garnered attention as an alternative to liver transplantation, the only reliable treatment for patients with end-stage liver diseases. Despite this attention, the molecular basis of BEC-driven liver regeneration remains poorly understood. By performing a chemical screen with the zebrafish hepatocyte ablation model, in which BECs robustly contribute to hepatocytes, we identified farnesoid X receptor (FXR) agonists as inhibitors of BEC-driven liver regeneration. Here we show that FXR activation blocks the process through the FXR-PTEN (phosphatase and tensin homolog)-PI3K (phosphoinositide 3-kinase)-AKT-mTOR (mammalian target of rapamycin) axis. We found that FXR activation blocked LPC-to-hepatocyte differentiation, but not BEC-to-LPC dedifferentiation. FXR activation also suppressed LPC proliferation and increased its death. These defects were rescued by suppressing PTEN activity with its chemical inhibitor and ptena/b mutants, indicating PTEN as a critical downstream mediator of FXR signaling in BEC-driven liver regeneration. Consistent with the role of PTEN in inhibiting the PI3K-AKT-mTOR pathway, FXR activation reduced the expression of pS6, a marker of mTORC1 activation, in LPCs of regenerating livers. Importantly, suppressing PI3K and mTORC1 activities with their chemical inhibitors blocked BEC-driven liver regeneration, as did FXR activation. FXR activation impairs BEC-driven liver regeneration by enhancing PTEN activity; the PI3K-AKT-mTOR pathway controls the regeneration process. Given the clinical trials and use of FXR agonists for multiple liver diseases due to their beneficial effects on steatosis and fibrosis, the detrimental effects of FXR activation on LPCs suggest a rather personalized use of the agonists in the clinic.

Human Amnion Epithelial Cells Reduce Liver Fibrosis Via Effects On Macrophages Phenotype And Liver Progenitor Cells In Murine Liver Injury

Background & Aim Background: Chronic liver disease is characterised by progressive hepatocyte injury, inflammation and accumulation of extracellular matrix. Liver progenitor cells (LPC) are bipotent cells induced during liver injury that can regenerate both hepatocytes and cholangiocytes. In addition, macrophages play a pivotal role in fibrogenesis and fibrosis resolution. Classically, macrophages are classified into M1 (pro-inflammatory macrophages) and M2 (pro-resolution macrophages). Recently, Ly6C expression has been used to identify distinct macrophage populations, Ly6Chi (inflammatory) and Ly6Clow (resolution). We are developing a therapy for chronic liver fibrosis using human amnion epithelial cells (hAECs). The choline-deficient ethionine-supplemented (CDE) diet is a non-invasive and quick method to induce liver injury and LPC proliferation. Here, we aimed to investigate the effect of hAECs on macrophages and LPC during liver injury induced by a CDE diet. Aim Methods, Results & Conclusion Methods: C57/B16J mice were commenced on a CDE diet, then 2 or 4 million hAECs were infused intraperitoneally 24h later and the CDE diet continued. Outcomes were assessed at days 1, 3, 5, 14, 21 and 42 following hAEC administrations. Sirius red staining and immunohistochemistry were used to determine fibrosis and identify LPC in liver sections. Macrophages and LPC were further identified and characterised using flow cytometery sorting and PCR. Results In CDE treated mice, hAEC significantly reduced liver fibrosis compared to untreated mice. hAEC decreased the number of proinflammatory (Ly6Chi) monocyte-derived macrophages (MDM) and increased the number of anti-inflammatory and tissue remodelling (Ly6Clow) MDM. hAEC also enhanced the expression of matrix-metalloproteinase (MMP)12 and MMP13 in Ly6CLow sorted cells. LPC numbers were reduced significantly in hAEC treated mice. Conclusion Our data confirm the potential efficacy of hAECs as an effective therapy in liver fibrosis.

Human Amnion Epithelial Cells Produce Soluble Factors that Enhance Liver Repair by Reducing Fibrosis While Maintaining Regeneration in a Model of Chronic Liver Injury

Human amnion epithelial cells (hAECs) exert potent antifibrotic and anti-inflammatory effects when transplanted into preclinical models of tissue fibrosis. These effects are mediated in part via the secretion of soluble factors by hAECs which modulate signaling pathways and affect cell types involved in inflammation and fibrosis. Based on these reports, we hypothesized that these soluble factors may also support liver regeneration during chronic liver injury. To test this, we characterized the effect of both hAECs and hAEC-conditioned medium (CM) on liver repair in a mouse model of carbon tetrachloride (CCl4)-induced fibrosis. Liver repair was assessed by liver fibrosis, hepatocyte proliferation, and the liver progenitor cell (LPC) response. We found that the administration of hAECs or hAEC-CM reduced liver injury and fibrosis, sustained hepatocyte proliferation, and reduced LPC numbers during chronic liver injury. Additionally, we undertook in vitro studies to document both the cell–cell and paracrine-mediated effects of hAECs on LPCs by investigating the effects of co-culturing the LPCs and hAECs and hAEC-CM on LPCs. We found little change in LPCs co-cultured with hAECs. In contrast, hAEC-CM enhances LPC proliferation and differentiation. These findings suggest that paracrine factors secreted by hAECs enhance liver repair by reducing fibrosis while promoting regeneration during chronic liver injury.

Dysregulated Bile Transporters and Impaired Tight Junctions During Chronic Liver Injury in Mice

Liver fibrosis, hepatocellular necrosis, inflammation, and proliferation of liver progenitor cells are features of chronic liver injury. Mouse models have been used to study the end-stage pathophysiology of chronic liver injury. However, little is known about differences in the mechanisms of liver injury among different mouse models because of our inability to visualize the progression of liver injury invivo in mice. We developed a method to visualize bile transport and blood-bile barrier (BBlB) integrity in live mice. C57BL/6 micewere fed a choline-deficient, ethionine-supplemented (CDE)diet or a diet containing 0.1% 3,5-diethoxycarbonyl-1, 4-dihydrocollidine (DDC) for up to 4 weeks to induce chronic liver injury. We used quantitative liver intravital microscopy (qLIM) for real-time assessment of bile transport and BBlB integrity in the intact livers of the live mice fed the CDE, DDC, or chow (control) diets. Liver tissues were collected from mice and analyzed by histology, immunohistochemistry, real-time polymerase chain reaction, and immunoblots. Mice with liver injury induced by a CDE or a DDC diet had breaches in the BBlB and impaired bile secretion, observed by qLIM compared with control mice. Impaired bile secretion was associated with reduced expression of several tight-junction proteins (claudins 3, 5, and 7) and bile transporters (NTCP, OATP1, BSEP, ABCG5, and ABCG8). A prolonged (2-week) CDE, but not DDC, diet led to re-expression of tight junction proteins and bile transporters, concomitant with the reestablishment of BBlB integrity and bile secretion. We used qLIM to study chronic liver injury, induced by a choline-deficient or DDC diet, in mice. Progression of chronic liver injury was accompanied by loss of bile transporters and tight junction proteins.

A pivotal role of BEX1 in liver progenitor cell expansion in mice

BackgroundThe activation and expansion of bipotent liver progenitor cells (LPCs) are indispensable for liver regeneration after severe or chronic liver injury. However, the underlying molecular mechanisms regulating LPCs and LPC-mediated liver regeneration remain elusive.MethodsHepatic brain-expressed X-linked 1 (BEX1) expression was evaluated using microarray screening, real-time polymerase chain reaction, immunoblotting and immunofluorescence. LPC activation and liver injury were studied following a choline-deficient, ethionine-supplemented (CDE) diet in wild-type (WT) and Bex1−/− mice. Proliferation, apoptosis, colony formation and hepatic differentiation were examined in LPCs from WT and Bex1−/− mice. Peroxisome proliferator-activated receptor gamma was detected in Bex1-deficient LPCs and mouse livers, and was silenced to analyse the expansion of LPCs from WT and Bex1−/− mice.ResultsHepatic BEX1 expression was increased during CDE diet-induced liver injury and was highly elevated primarily in LPCs. Bex1−/− mice fed a CDE diet displayed impaired LPC expansion and liver regeneration. Bex1 deficiency inhibited LPC proliferation and enhanced LPC apoptosis in vitro. Additionally, Bex1 deficiency inhibited the colony formation of LPCs but had no effect on their hepatic differentiation. Mechanistically, BEX1 inhibited peroxisome proliferator-activated receptor gamma to promote LPC expansion.ConclusionOur findings indicate that BEX1 plays a pivotal role in LPC activation and expansion during liver regeneration, potentially providing novel targets for liver regeneration and chronic liver disease therapies.

Stat3 Regulates Liver Progenitor Cell-Driven Liver Regeneration in Zebrafish.

After liver injury, regeneration manifests as either (1) hepatocytes proliferating to restore the lost hepatocyte mass or (2) if hepatocyte proliferation is compromised, biliary epithelial cells (BECs) dedifferentiating into liver progenitor cells (LPCs), which subsequently differentiate into hepatocytes. Following pharmacogenetic ablation of hepatocytes in Tg(fabp10a:CFP-NTR) zebrafish, resulting in severe liver injury, signal transducer and activator of transcription 3 (Stat3) and its target gene and negative regulator, socs3a, were upregulated in regenerating livers. Using either Stat3 inhibitors, JSI-124 and S3I-201, or stat3 zebrafish mutants, we investigated the role of Stat3 in LPC-driven liver regeneration. Although Stat3 suppression reduced the size of regenerating livers, BEC dedifferentiation into LPCs was unaffected. However, regenerating livers displayed a delay in LPC-to-hepatocyte differentiation and a significant reduction in the number of BECs. While no difference in cell death was detected, Stat3 inhibition significantly reduced LPC proliferation. Notably, stat3 mutants phenocopied the effects of Stat3 chemical inhibitors, although the mutant phenotype was incompletely penetrant. Intriguingly, a subset of socs3a mutants also displayed a lower number of BECs in regenerating livers. We conclude that the Stat3/Socs3a pathway is necessary for the proper timing of LPC-to-hepatocyte differentiation and establishing the proper number of BECs during LPC-driven liver regeneration.

Dysregulated bile transporters and impaired tight junctions promote chronic liver injury in mice

Liver fibrosis, hepatocellular necrosis, inflammation and proliferation of liver progenitor cells are the hallmarks of chronic liver injury. Several murine models have been used to mimic the pathophysiology of chronic liver injury. However, the underlying differences in the molecular mechanism driving liver injury in different models remains largely unknown due to our inability to visualize the progression of liver injury in vivo in mice. Here, we use intravital imaging of bile transport and blood‐bile barrier integrity in the intact liver of live mice. We show for the first time that breach of blood‐bile barrier and impairment of bile secretion promotes choline‐deficient‐ethionine‐supplemented (CDE) and 3, 5‐diethoxycarbonyl‐1, 4‐dihydrocollidine (DDC) diets induced chronic liver injury in mice. The impairment in bile secretion was associated with the disruption of the blood‐bile barrier, differential expression of several tight junction adhesion molecules and loss of bile transporters. Surprisingly, the prolonged use of CDE diet led to reappearance of tight junction adhesion molecules as well as bile transporters, which was concomitant to the reestablishment of blood‐bile barrier integrity and rescue of bile secretion. Our findings demonstrate the potential of intravital imaging in elucidating the underlying pathophysiology in mice models of chronic liver injury and identify the loss of bile transporters or tight junction adhesion molecules as two distinct mechanisms contributing to progression of chronic liver injury.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Wnt/?-Catenin Signalling during Liver Metabolism, Chronic Liver Disease and Hepatocarcinogenesis

Chronic liver diseases (CLDs) are increasing in prevalence and their end-stage complications, namely, cirrhosis, liver failure and hepatocellular carcinoma represent major global challenges. The most common initiators of progressive CLD are viral hepatitis and long-term alcohol abuse as well as steatosis and steatohepatitis. Irrespective of the underlying aetiology, a common feature of CLD is the formation of hepatic ductular reactions, involving the proliferation of liver progenitor cells (LPCs) and their signalling to fibrosis-driving hepatic stellate cells. The Wnt/?-catenin pathway has been found to regulate development, stemness and differentiation, and alterations in its activity have been associated with tumour development. Recent data highlight the role of Wnt/?-catenin signalling in hepatic metabolism, steatosis and cancer, and suggest targeting of this pathway as a promising molecular strategy to potentially inhibit CLD progression and hepatocarcinogenesis.

Cellular and Molecular Effects of Prolonged Low-Level Sodium Arsenite Exposure on Human Hepatic HepaRG Cells.

Inorganic arsenic is a human carcinogen associated with several types of cancers, including liver cancer. Inorganic arsenic has been postulated to target stem cells, causing their oncogenic transformation. This is proposed to be one of the key events in arsenic-associated carcinogenesis; however, the underlying mechanisms for this process remain largely unknown. To address this question, human hepatic HepaRG cells, at progenitor and differentiated states, were continuously treated with a noncytotoxic concentration of 1 μM sodium arsenite (NaAsO2). The HepaRG cells demonstrated active intracellular arsenite metabolism that shared important characteristic with primary human hepatocytes. Treatment of proliferating progenitor-like HepaRG cells with NaAsO2 inhibited their differentiation into mature hepatocyte-like cells, up-regulated genes involved in cell growth, proliferation, and survival, and down-regulated genes involved in cell death. In contrast, treatment of differentiated hepatocyte-like HepaRG cells with NaAsO2 resulted in enhanced cell death of mature hepatocyte-like cells, overexpression of cell death-related genes, and down-regulation of genes in the cell proliferation pathway, while biliary-like cells remained largely unaffected. Mechanistically, the cytotoxic effect of arsenic on mature hepatocyte-like HepaRG cells may be attributed to arsenic-induced dysregulation of cellular iron metabolism. The inhibitory effect of NaAsO2 on the differentiation of progenitor cells, the resistance of biliary-like cells to cell death, and the enhanced cell death of functional hepatocyte-like cells resulted in stem-cell activation. These effects favored the proliferation of liver progenitor cells that can serve as a source of initiation and driving force of arsenic-mediated liver carcinogenesis.

The Murine Choline-Deficient, Ethionine-Supplemented (CDE) Diet Model of Chronic Liver Injury.

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual inflammation, progressive destruction and regeneration of the hepatic parenchyma, liver progenitor cell proliferation, and fibrosis. The end-stage of every chronic liver disease is cirrhosis, a major risk factor for the development of hepatocellular carcinoma. To study processes regulating disease initiation, establishment, and progression, several animal models are used in laboratories. Here we describe a six-week time course of the choline-deficient and ethionine-supplemented (CDE) mouse model, which involves feeding six-week old male C57BL/6J mice with choline-deficient chow and 0.15% DL-ethionine-supplemented drinking water. Monitoring of animal health and a typical body weight loss curve are explained. The protocol demonstrates the gross examination of a CDE-treated liver and blood collection by cardiac puncture for subsequent serum analyses. Next, the liver perfusion technique and collection of different hepatic lobes for standard evaluations are shown, including liver histology assessments by hematoxylin and eosin or Sirius Red stainings, immunofluorescent detection of hepatic cell populations as well as transcriptome profiling of the liver microenvironment. This mouse model is suitable for studying inflammatory, fibrogenic, and liver progenitor cell dynamics induced through chronic liver disease and can be used to test potential therapeutic agents that may modulate these processes.

Taurocholate Induces Biliary Differentiation of Liver Progenitor Cells Causing Hepatic Stellate Cell Chemotaxis in the Ductular Reaction: Role in Pediatric Cystic Fibrosis Liver Disease

Cystic fibrosis liver disease (CFLD) in children causes progressive fibrosis leading to biliary cirrhosis; however, its cause(s) and early pathogenesis are unclear. We hypothesized that a bile acid-induced ductular reaction (DR) drives fibrogenesis. The DR was evaluated by cytokeratin-7 immunohistochemistry in liver biopsies, staged for fibrosis, from 60 children with CFLD, and it demonstrated that the DR was significantly correlated with hepatic fibrosis stage and biliary taurocholate levels. To examine the mechanisms involved in DR induction, liver progenitor cells (LPCs) were treated with taurocholate, and key events in DR evolution were assessed: LPC proliferation, LPC biliary differentiation, and hepatic stellate cell (HSC) chemotaxis. Taurocholate induced a time-dependent increase in LPC proliferation and expression of genes associated with cholangiocyte differentiation (cytokeratin 19, connexin 43, integrin β4, and γ-glutamyltranspeptidase), whereas the hepatocyte specification marker HNF4α was suppressed. Functional cholangiocyte differentiation was demonstrated via increased acetylated α-tubulin and SOX9 proteins, the number of primary cilia+ LPCs, and increased active γ-glutamyltranspeptidase enzyme secretion. Taurocholate induced LPCs to release MCP-1, MIP1α, and RANTES into conditioned medium causing HSC chemotaxis, which was inhibited by anti-MIP1α. Immunofluorescence confirmed chemokine expression localized to CK7+ DR and LPCs in CFLD liver biopsies. This study suggests that taurocholate is involved in initiating functional LPC biliary differentiation and the development of the DR, with subsequent induction of chemokines that drive HSC recruitment in CFLD.

Aging-associated oxidative stress inhibits liver progenitor cell activation in mice.

Recent studies have discovered aging-associated changes of adult stem cells in various tissues and organs, which potentially contribute to the organismal aging. However, aging-associated changes of liver progenitor cells (LPCs) remain elusive. Employing young (2-month-old) and old (24-month-old) mice, we found diverse novel alterations in LPC activation during aging. LPCs in young mice could be activated and proliferate upon liver injury, whereas the counterparts in old mice failed to respond and proliferate, leading to the impaired liver regeneration. Surprisingly, isolated LPCs from young and old mice did not exhibit significant difference in their clonogenic and proliferative capacity. Later, we uncovered that the decreased activation and proliferation of LPCs were due to excessive reactive oxygen species produced by neutrophils infiltrated into niche, which was resulted from chemokine production from activated hepatic stellate cells during aging. This study demonstrates aging-associated changes in LPC activation and reveals critical roles for the stem cell niche, including neutrophils and hepatic stellate cells, in the negative regulation of LPCs during aging.

Basic Science Liver.

Basic Science Liver.

Large tumor suppressor homologs 1 and 2 regulate mouse liver progenitor cell proliferation and maturation through antagonism of the coactivators YAP and TAZ.

Hippo signaling, mediated by the LATS1 and LATS2 kinases, is required to restrict YAP and TAZ activation during both biliary and hepatocyte differentiation. These findings suggest that dynamic regulation of the Hippo signaling pathway plays an important role in differentiation and functional maturation of the liver. (Hepatology 2016;64:1757-1772).

DJ-1 deficiency attenuates expansion of liver progenitor cells through modulating the inflammatory and fibrogenic niches.

Our previous study suggested that DJ-1 has a critical role in initiating an inflammatory response, but its role in the liver progenitor cell (LPC) expansion, a process highly dependent on the inflammatory niche, remains elusive. The objective of this study is to determine the role of DJ-1 in LPC expansion. The correlation of DJ-1 expression with LPC markers was examined in the liver of patients with hepatitis B or hepatitis C virus (HBV and HCV, respectively) infection, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), nonalcoholic fatty liver disease (NAFLD), cirrhosis or hepatocellular carcinoma (HCC), respectively. The role of DJ-1 in LPC expansion and the formation of LPC-associated fibrosis and inflammation was examined in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet-induced liver injury murine model. We also determined the ability of hepatic stellate cells (HSCs) in recruiting macrophages in DJ-1 knockout (KO) mice. The expression levels of DJ-1 were upregulated in the liver of HBV, HCV, PBC and PSC patients and DDC-fed mice. Additionally, DJ-1 expression was positively correlated with LPC proliferation in patients with liver injury and mice with DDC exposure. DJ-1 has no direct effect on LPC proliferation. Reduced activation of HSCs and collagen deposition were observed in DJ-1 KO mice. Furthermore, infiltrated CD11b+Gr-1low macrophages and pro-inflammatory factors (IL-6, TNF-α) were attenuated in DJ-1 KO mice. Mechanistically, we found that HSCs isolated from DJ-1 KO mice had decreased secretion of macrophage-mobilizing chemokines, such as CCL2 and CX3CL1, resulting in impaired macrophage infiltration. DJ-1 positively correlates with LPC expansion during liver injury. DJ-1 deficiency negatively regulates LPC proliferation by impairing the formation of LPC-associated fibrosis and inflammatory niches.

Divergent Inflammatory, Fibrogenic, and Liver Progenitor Cell Dynamics in Two Common Mouse Models of Chronic Liver Injury

Complications of end-stage chronic liver disease signify a major cause of mortality worldwide. Irrespective of the underlying cause, most chronic liver diseases are characterized by hepatocellular necrosis, inflammation, fibrosis, and proliferation of liver progenitor cells or ductular reactions. Vast differences exist between experimental models that mimic these processes, and their identification is fundamental for translational research. We compared two common murine models of chronic liver disease: the choline-deficient, ethionine-supplemented (CDE) diet versus thioacetamide (TAA) supplementation. Markers of liver injury, including serum alanine transaminase levels, apoptosis, hepatic fat loading, and oxidative stress, as well as inflammatory, fibrogenic and liver progenitor cell responses, were assessed at days 3, 7, 14, 21, and 42. This study revealed remarkable differences between the models. It identified periportal injury and fibrosis with an early peak and slow normalization of all parameters in the CDE regimen, whereas TAA-treated mice had pericentral patterns of progressive injury and fibrosis, resulting in a more severe hepatic injury phenotype. This study is the first to resolve two different patterns of injury and fibrosis in the CDE and TAA model and to indisputably identify the fibrosis pattern in the TAA model as driven from the pericentral vein region. Our data provide a valuable foundation for future work using the CDE and TAA regimens to model a variety of human chronic liverdiseases.

Abstract LB-136: The role of ER chaperone GRP94 in endometrial cancer progression

Abstract Endometrial cancer is the most prevalent gynecologic cancer in the United States and accounts for nearly 50,000 incident cases annually. One of the most common mutations detected in the more prevalent Type 1 endometrial cancer is the loss of the tumor suppressor gene, Pten (phosphatase and tensin homolog). Pten mutations are involved in a wide variety of human cancers, including >60% of endometrial cancer. The glucose-regulated protein 94 (GRP94), also known as glycoprotein 96 (gp96), is a major chaperone protein in the ER. The client proteins of GPR94 include important regulators of cell growth and cell adhesion such as IGF-1, Toll-like receptors and integrins. GRP94 is known to play major roles in immune modulation. GRP94 also possesses anti-apoptotic properties. GRP94 elevation has been reported in a variety of human cancers and has been implicated in cancer development. Previously, GRP94 knockout in multiple myeloma reduced cell proliferation and survival, through inhibiting Wnt-LRP-survivin pathway. GRP94 knockout in macrophages reduced inflammatory colon tumorigenesis. On the other hand, GRP94 knockout in hepatocytes resulted in liver progenitor cell proliferation and acceleration of liver cancer, associating with repopulation of GRP94-positive hepatocytes. Therefore, the role of GRP94 in cancer appears to be context-dependent due to its multifaceted functions. Currently, little is known about GRP94 expression and function in endometrial cancer. We examined GRP94 expression in human endometrial cancer tissues and robust GRP94 expression was observed. In human endometrial cancer cell line, GRP94 knockdown by siRNA led to decreased proliferation and cell migration. To examine the requirement of GRP94 in the initiation and development of endometrial cancer, we utilized the Progesterone Receptor-Cre to specifically delete genes in the mouse endometrium. Before studying GRP94 in endometrial cancer, we first determined the effect of GRP94 depletion in normal uteri. Surprisingly, GRP94 single knockout uteri showed squamous cell metaplasia, confirmed by expression of K14 and p63, and reduction in size. Next, we created the biallelic mutant mice with concurrent deletion of Pten and Grp94 in the endometrium. We monitored the progress of endometrial cancer development, with mice bearing Pten knockout alone serving as the positive controls. As expected, Pten single knockout mice develop endometrial cancer by 4 week and initiate invasion into myometrium by 8 week. Analysis of the mice uteri indicated that GRP94 deficiency delayed the onset of endometrial cancer, associating with altered cell adhesion properties and pro-oncogenic signaling pathways. This study expands our understanding of GRP94 function in the progression of solid tumors and provides the first evidence that GRP94 could be a target for combating endometrial cancer. Citation Format: Jieli Shen, Yvonne G. Lin, Louis Dubeau, Amy S. Lee. The role of ER chaperone GRP94 in endometrial cancer progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-136. doi:10.1158/1538-7445.AM2015-LB-136

Kupffer cell-monocyte communication is essential for initiating murine liver progenitor cell-mediated liver regeneration.

Liver progenitor cells (LPCs) are necessary for repair in chronic liver disease because the remaining hepatocytes cannot replicate. However, LPC numbers also correlate with disease severity and hepatocellular carcinoma risk. Thus, the progenitor cell response in diseased liver may be regulated to optimize liver regeneration and minimize the likelihood of tumorigenesis. How this is achieved is currently unknown. Human and mouse diseased liver contain two subpopulations of macrophages with different ontogenetic origins: prenatal yolk sac-derived Kupffer cells and peripheral blood monocyte-derived macrophages. We examined the individual role(s) of Kupffer cells and monocyte-derived macrophages in the induction of LPC proliferation using clodronate liposome deletion of Kupffer cells and adoptive transfer of monocytes, respectively, in the choline-deficient, ethionine-supplemented diet model of liver injury and regeneration. Clodronate liposome treatment reduced initial liver monocyte numbers together with the induction of injury and LPC proliferation. Adoptive transfer of monocytes increased the induction of liver injury, LPC proliferation, and tumor necrosis factor-α production. Kupffer cells control the initial accumulation of monocyte-derived macrophages. These infiltrating monocytes are in turn responsible for the induction of liver injury, the increase in tumor necrosis factor-α, and the subsequent proliferation of LPCs.