Interleukin-6-driven progranulin expression increases cholangiocarcinoma growth by an Akt-dependent mechanism

Activation of transglutaminase 2 by nerve growth factor in differentiating neuroblastoma cells: A role in cell survival and neurite outgrowth

NGF (nerve growth factor) and tissue transglutaminase (TG2) play important roles in neurite outgrowth and modulation of neuronal cell survival. In this study, we investigated the regulation of TG2 transamidase activity by NGF in retinoic acid-induced differentiating mouse N2a and human SH-SY5Y neuroblastoma cells. TG2 transamidase activity was determined using an amine incorporation and a peptide cross linking assay. In situ TG2 activity was assessed by visualising the incorporation of biotin-X-cadaverine using confocal microscopy. The role of TG2 in NGF-induced cytoprotection and neurite outgrowth was investigated by monitoring hypoxia-induced cell death and appearance of axonal-like processes, respectively. The amine incorporation and protein crosslinking activity of TG2 increased in a time and concentration-dependent manner following stimulation with NGF in N2a and SH-SY5Y cells. NGF mediated increases in TG2 activity were abolished by the TG2 inhibitors Z-DON (Z-ZON-Val-Pro-Leu-OMe; Benzyloxycarbonyl-(6-Diazo-5-oxonorleucinyl)-l-valinyl-l-prolinyl-l-leucinmethylester) and R283 (1,3,dimethyl-2[2-oxo-propyl]thio)imidazole chloride) and by pharmacological inhibition of extracellular signal-regulated kinases 1 and 2 (ERK1/2), protein kinase B (PKB) and protein kinase C (PKC), and removal of extracellular Ca²⁺. Fluorescence microscopy demonstrated NGF induced in situ TG2 activity. TG2 inhibition blocked NGF-induced attenuation of hypoxia-induced cell death and neurite outgrowth in both cell lines. Together, these results demonstrate that NGF stimulates TG2 transamidase activity via a ERK1/2, PKB and PKC-dependent pathway in differentiating mouse N2a and human SH-SY5Y neuroblastoma cells. Furthermore, NGF-induced cytoprotection and neurite outgrowth are dependent upon TG2. These results suggest a novel and important role of TG2 in the cellular functions of NGF.

Melatonin inhibits hypothalamic gonadotropin-releasing hormone release and reduces biliary hyperplasia and fibrosis in cholestatic rats

Melatonin is a hormone produced by the pineal gland with increased circulating levels shown to inhibit biliary hyperplasia and fibrosis during cholestatic liver injury. Melatonin also has the capability to suppress the release of hypothalamic gonadotropin-releasing hormone (GnRH), a hormone that promotes cholangiocyte proliferation when serum levels are elevated. However, the interplay and contribution of neural melatonin and GnRH to cholangiocyte proliferation and fibrosis in bile duct-ligated (BDL) rats have not been investigated. To test this, cranial levels of melatonin were increased by implanting osmotic minipumps that performed an intracerebroventricular (ICV) infusion of melatonin or saline for 7 days starting at the time of BDL. Hypothalamic GnRH mRNA and cholangiocyte secretion of GnRH and melatonin were assessed. Cholangiocyte proliferation and fibrosis were measured. Primary human hepatic stellate cells (HSCs) were treated with cholangiocyte supernatants, GnRH, or the GnRH receptor antagonist cetrorelix acetate, and cell proliferation and fibrosis gene expression were assessed. Melatonin infusion reduced hypothalamic GnRH mRNA expression and led to decreased GnRH and increased melatonin secretion from cholangiocytes. Infusion of melatonin was found to reduce hepatic injury, cholangiocyte proliferation, and fibrosis during BDL-induced liver injury. HSCs supplemented with BDL cholangiocyte supernatant had increased proliferation, and this increase was reversed when HSCs were supplemented with supernatants from melatonin-infused rats. GnRH stimulated fibrosis gene expression in HSCs, and this was reversed by cetrorelix acetate cotreatment. Increasing bioavailability of melatonin in the brain may improve outcomes during cholestatic liver disease.NEW & NOTEWORTHY We have previously demonstrated that GnRH is expressed in cholangiocytes and promotes their proliferation during cholestasis. In addition, dark therapy, which increases melatonin, reduced cholangiocyte proliferation and fibrosis during cholestasis. This study expands these findings by investigating neural GnRH regulation by melatonin during BDL-induced cholestasis by infusing melatonin into the brain. Melatonin infusion reduced cholangiocyte proliferation and fibrosis, and these effects are due to GNRH receptor 1-dependent paracrine signaling between cholangiocytes and hepatic stellate cells.

Bile Acid-Mediated Sphingosine-1-Phosphate Receptor 2 Signaling Promotes Neuroinflammation during Hepatic Encephalopathy in Mice

Hepatic encephalopathy (HE) is a neuropsychiatric complication that occurs due to deteriorating hepatic function and this syndrome influences patient quality of life, clinical management strategies and survival. During acute liver failure, circulating bile acids increase due to a disruption of the enterohepatic circulation. We previously identified that bile acid-mediated signaling occurs in the brain during HE and contributes to cognitive impairment. However, the influences of bile acids and their downstream signaling pathways on HE-induced neuroinflammation have not been assessed. Conjugated bile acids, such as taurocholic acid (TCA), can activate sphingosine-1-phosphate receptor 2 (S1PR2), which has been shown to promote immune cell infiltration and inflammation in other models. The current study aimed to assess the role of bile-acid mediated S1PR2 signaling in neuroinflammation and disease progression during azoxymethane (AOM)-induced HE in mice. Our findings demonstrate a temporal increase of bile acids in the cortex during AOM-induced HE and identified that cortical bile acids were elevated as an early event in this model. In order to classify the specific bile acids that were elevated during HE, a metabolic screen was performed and this assay identified that TCA was increased in the serum and cortex during AOM-induced HE. To reduce bile acid concentrations in the brain, mice were fed a diet supplemented with cholestyramine, which alleviated neuroinflammation by reducing proinflammatory cytokine expression in the cortex compared to the control diet-fed AOM-treated mice. S1PR2 was expressed primarily in neurons and TCA treatment increased chemokine ligand 2 mRNA expression in these cells. The infusion of JTE-013, a S1PR2 antagonist, into the lateral ventricle prior to AOM injection protected against neurological decline and reduced neuroinflammation compared to DMSO-infused AOM-treated mice. Together, this identifies that reducing bile acid levels or S1PR2 signaling are potential therapeutic strategies for the management of HE.

IL-6 is involved in malignancy and doxorubicin sensitivity of renal carcinoma cells

Various survival factors such as the pleiotropic cytokine interleukin-6 (IL-6), a major mediator of inflammation and activator of signal transducer and activator of transcription 3 (STAT3), serve to block apoptosis in cancer cells. Our present study revealed that the expression of IL-6, while not other IL-2, IL-4, IL-8, or IL-10, was significantly elevated in resistance of renal carcinoma cells (RCC) when compared with human renal proximal tubule epithelial cell line HK-2. The inhibition of IL-6 by siRNA can suppress the proliferation, migration and invasion of RCC cells and increase the doxorubicin (Dox) sensitivity. While recombination IL-6 can attenuate the inhibition effects of Dox on proliferation of RCC cells. Further studies indicated that inhibition of IL-6 by siRNA can decrease the phosphorylation of STAT3 in RCC cells. Over expression of STAT3 increased the proliferation, migration and invasion of RCC cells and reversed si-IL-6 induced increase of Dox sensitivity of ACHN and A498 cells. In addition, IL-6 treatment can activate ERK1/2 via increasing its phosphorylation. PD98059, the ERK1/2 inhibitor, attenuated IL-6 induced proliferation and synergistically increased the Dox sensitivity of si-IL-6 transfected ACHN cells. Collectively, our data suggested that IL-6 plays an important role in malignancy and Dox sensitivity of RCC. The targeted inhibition of IL-6 signals might be a promising therapeutic strategy for the treatment of renal cancer.

MiR-145 mediates zebrafish hepatic outgrowth through progranulin A signaling

MicroRNAs (miRs) are mRNA-regulatory molecules that fine-tune gene expression and modulate both processes of development and tumorigenesis. Our previous studies identified progranulin A (GrnA) as a growth factor which induces zebrafish hepatic outgrowth through MET signaling. We also found that miR-145 is one of potential fine-tuning regulators of GrnA involved in embryonic hepatic outgrowth. The low level of miR-145 seen in hepatocarinogenesis has been shown to promote pathological liver growth. However, little is known about the regulatory mechanism of miR-145 in embryonic liver development. In this study, we demonstrate a significant decrease in miR-145 expression during hepatogenesis. We modulate miR-145 expression in zebrafish embryos by injection with a miR-145 mimic or a miR-145 hairpin inhibitor. Altered embryonic liver outgrowth is observed in response to miR-145 expression modulation. We also confirm a critical role of miR-145 in hepatic outgrowth by using whole-mount in situ hybridization. Loss of miR-145 expression in embryos results in hepatic cell proliferation, and vice versa. Furthermore, we demonstrate that GrnA is a target of miR-145 and GrnA-induced MET signaling is also regulated by miR-145 as determined by luciferase reporter assay and gene expression analysis, respectively. In addition, co-injection of GrnA mRNA with miR-145 mimic or MO-GrnA with miR-145 inhibitor restores the liver defects caused by dysregulation of miR-145 expression. In conclusion, our findings suggest an important role of miR-145 in regulating GrnA-dependent hepatic outgrowth in zebrafish embryonic development.

PGRN Suppresses Inflammation and Promotes Autophagy in Keratinocytes Through the Wnt/β-Catenin Signaling Pathway

Psoriasis is a chronic, immune-mediated inflammatory skin disease that has a major impact on patients' quality of life. Progranulin (PGRN) is highly expressed in skin diseases and plays an important role in inflammation response and autophagy. However, the function of PGRN in the immune system and autophagy in psoriasis has not been clearly identified and elaborated on. Thus, this study aimed to investigate the role of PGRN on the inflammatory and autophagy process underlying inflammation in HaCaT cells. We showed that PGRN was markedly highly expressed in psoriasis lesions and inflammatory HaCaT cells. Specific silencing of PGRN promoted the production of the inflammatory cytokines IL-1β, IL-6, COX-2, iNOs, and MCP-1. Furthermore, PGRN siRNA promoted autophagy-related gene p62 and suppressed LC3II and Atg7 in HaCaT cells, while overexpression of PGRN showed a contrary effect. Moreover, knockdown of PGRN upregulated the expression levels of β-catenin, cyclin D1, and c-myc proteins. Finally, we demonstrated that IWP-2, an inhibitor of the Wnt/β-catenin signaling pathway, stemmed the pro-inflammatory and anti-autophagy effect of PGRN siRNA in TNF-α-treated HaCaT cells. Collectively, our findings suggest that PGRN is upregulated in psoriasis lesions and that the overexpression of PGRN inhibits the inflammation in keratinocytes induced by TNF-α by negatively regulating the production of inflammatory factors and positively mediating autophagy through the Wnt/β-catenin signaling pathway; this indicated that overexpression of PGRN may be a potential therapeutic option in psoriasis.

The Neuropeptide Galanin Is Up-Regulated during Cholestasis and Contributes to Cholangiocyte Proliferation

During the course of cholestatic liver diseases, mitotically dormant cholangiocytes proliferate and subsequently acquire a neuroendocrine phenotype. Galanin is a neuroendocrine factor responsible for regulation of physiological responses, such as feeding behavior and mood, and has been implicated in the development of fatty liver disease, although its role in biliary hyperplasia is unknown. Biliary hyperplasia was induced in rats via bile duct ligation (BDL) surgery, and galanin was increased in serum and liver homogenates from BDL rats. Treatment of sham and BDL rats with recombinant galanin increased cholangiocyte proliferation and intrahepatic biliary mass, liver damage, and inflammation, whereas blocking galanin expression with specific vivo-morpholino sequences inhibited hyperplastic cholangiocyte proliferation, liver damage, inflammation, and subsequent fibrosis. The proliferative effects of galanin were via activation of galanin receptor 1 expressed specifically on cholangiocytes and were associated with an activation of extracellular signal-regulated kinase 1/2, and ribosomal S6 kinase 1 signal transduction pathways and subsequent increase in cAMP responsive element binding protein DNA-binding activity and induction of Yes-associated protein expression. Strategies to inhibit extracellular signal-regulated kinase 1/2, ribosomal S6 kinase 1, or cAMP responsive element binding protein DNA-binding activity prevented the proliferative effects of galanin. Taken together, these data suggest that targeting galanin signaling may be effective for the maintenance of biliary mass during cholestatic liver diseases.

Role of transglutaminase 2 in PAC1 receptor mediated protection against hypoxia-induced cell death and neurite outgrowth in differentiating N2a neuroblastoma cells

The PAC₁ receptor and tissue transglutaminase (TG2) play important roles in neurite outgrowth and modulation of neuronal cell survival. In this study, we investigated the regulation of TG2 activity by the PAC₁ receptor in retinoic acid-induced differentiating N2a neuroblastoma cells. TG2 transamidase activity was determined using an amine incorporation and a peptide cross linking assay. In situ TG2 activity was assessed by visualising the incorporation of biotin-X-cadaverine using confocal microscopy. TG2 phosphorylation was monitored via immunoprecipitation and Western blotting. The role of TG2 in PAC₁ receptor-induced cytoprotection and neurite outgrowth was investigated by monitoring hypoxia-induced cell death and appearance of axonal-like processes, respectively. The amine incorporation and protein crosslinking activity of TG2 increased in a time and concentration-dependent manner following stimulation with pituitary adenylate cyclase-activating polypeptide-27 (PACAP-27). PACAP-27 mediated increases in TG2 activity were abolished by the TG2 inhibitors Z-DON and R283 and by pharmacological inhibition of protein kinase A (KT 5720 and Rp-cAMPs), protein kinase C (Ro 31-8220), MEK1/2 (PD 98059), and removal of extracellular Ca²⁺. Fluorescence microscopy demonstrated PACAP-27 induced in situ TG2 activity. TG2 inhibition blocked PACAP-27 induced attenuation of hypoxia-induced cell death and outgrowth of axon-like processes. TG2 activation and cytoprotection were also observed in human SH-SY5Y cells. Together, these results demonstrate that TG2 activity was stimulated downstream of the PAC₁ receptor via a multi protein kinase dependent pathway. Furthermore, PAC₁ receptor-induced cytoprotection and neurite outgrowth are dependent upon TG2. These results highlight the importance of TG2 in the cellular functions of the PAC₁ receptor.

Fractalkine suppression during hepatic encephalopathy promotes neuroinflammation in mice

Background

Acute liver failure is associated with numerous systemic consequences including neurological dysfunction, termed hepatic encephalopathy, which contributes to mortality and is a challenge to manage in the clinic. During hepatic encephalopathy, microglia activation and neuroinflammation occur due to dysregulated cell signaling and an increase of toxic metabolites in the brain. Fractalkine is a chemokine that is expressed primarily in neurons and through signaling with its receptor CX3CR1 on microglia, leads to microglia remaining in a quiescent state. Fractalkine is often suppressed during neuropathies that are characterized by neuroinflammation. However, the expression and subsequent role of fractalkine on microglia activation and the pathogenesis of hepatic encephalopathy due to acute liver failure is unknown.

Methods

Hepatic encephalopathy was induced in mice via injection of azoxymethane (AOM) or saline for controls. Subsets of these mice were implanted with osmotic minipumps that infused soluble fractalkine or saline into the lateral ventricle of the brain. Neurological decline and the latency to coma were recorded in these mice, and brain, serum, and liver samples were collected. Neurons or microglia were isolated from whole brain samples using immunoprecipitation. Liver damage was assessed using hematoxylin and eosin staining and by measuring serum liver enzyme concentrations. Fractalkine and CX3CR1 expression were assessed by real-time PCR, and proinflammatory cytokine expression was assessed using ELISA assays.

Results

Following AOM administration, fractalkine expression is suppressed in the cortex and in isolated neurons compared to vehicle-treated mice. CX3CR1 is suppressed in isolated microglia from AOM-treated mice. Soluble fractalkine infusion into the brain significantly reduced neurological decline in AOM-treated mice compared to saline-infused AOM-treated mice. Infusion of soluble fractalkine into AOM-treated mice reduced liver damage, lessened microglia activation, and suppressed expression of chemokine ligand 2, interleukin-6, and tumor necrosis factor alpha compared to saline-infused mice.

Conclusions

These findings suggest that fractalkine-mediated signaling is suppressed in the brain following the development of hepatic encephalopathy. Supplementation of AOM-treated mice with soluble fractalkine led to improved outcomes, which identifies this pathway as a possible therapeutic target for the management of hepatic encephalopathy following acute liver injury.

Progranulin: A key player in autoimmune diseases

Autoimmune disease encompasses an array of conditions with a variety of presentations and the involvement of multiple organs. Though the etiologies of many autoimmune conditions are unclear, uncontrolled inflammatory immune response is believed to be a major cause of disease development and progression. Progranulin (PGRN), an anti-inflammatory molecule with therapeutic effect in inflammatory arthritis, was identified as an endogenous antagonist of TNFα by competitively binding to TNFR. PGRN exerts its anti-inflammatory activity through multiple pathways, including induction of T_reg differentiation and IL-10 expression and inhibition of chemokine release from macrophages. In addition, the protective role of PGRN has also been demonstrated in osteoarthritis, inflammatory bowel disease, and psoriasis. Intriguingly, PGRN was reported to contribute to development of insulin resistance in high-fat diet induced diabetes. Emerging evidences indicate that PGRN may also be associated with various autoimmune diseases, including systemic lupus erythematous, systemic sclerosis, multiple sclerosis and Sjogren's syndrome. This review summarizes recent studies of PGRN as a novel target molecule in the field of autoimmune disease, and provides updated information to inspire future studies.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

Interleukin-6-stimulated progranulin expression contributes to the malignancy of hepatocellular carcinoma cells by activating mTOR signaling

This study aimed to determine the expression of progranulin (PGRN) in hepatocellular carcinoma (HCC) cells in response to interleukin 6 (IL-6), a non-cellular component of the tumor microenvironment, and the molecular mechanism of PGRN oncogenic activity in hepatocarcinogenesis. Levels of IL-6 and PGRN were increased and positively correlated in HCC tissues. IL-6 dose- and time-dependently increased PGRN level in HCC cells. IL-6-driven PGRN expression was at least in part mediated by Erk/C/EBPβ signaling, and reduced expression of PGRN impaired IL-6-stimulated proliferation, migration and invasion of HepG2 cells. PGRN activated mammalian target of rapamycin (mTOR) signaling, as evidenced by increased phosphorylation of p70S6K, 4E-BP1, and Akt-Ser473/FoxO1. Inhibition of mTOR signaling with rapamycin, an mTOR signaling inhibitor, disturbed PGRN- or IL-6-mediated proliferation, migration and invasion of HCC cells in vitro. Persistent activation of mTOR signaling by knockdown of TSC2 restored PGRN-knockdown-attenuated pro-proliferation effects of IL-6 in HepG2 cells. In addition, rapamycin treatment in vivo in mice slowed tumor growth stimulated by recombinant human PGRN. Our findings provide a better understanding of the biological activities of the IL-6/PGRN/mTOR cascade in the carcinogenesis of HCC, which may suggest a novel target in the treatment of HCC.

Bile Acid Signaling Is Involved in the Neurological Decline in a Murine Model of Acute Liver Failure

Hepatic encephalopathy is a serious neurological complication of liver failure. Serum bile acids are elevated after liver damage and may disrupt the blood-brain barrier and enter the brain. Our aim was to assess the role of serum bile acids in the neurological complications after acute liver failure. C57Bl/6 or cytochrome p450 7A1 knockout (Cyp7A1(-/-)) mice were fed a control, cholestyramine-containing, or bile acid-containing diet before azoxymethane (AOM)-induced acute liver failure. In parallel, mice were given an intracerebroventricular infusion of farnesoid X receptor (FXR) Vivo-morpholino before AOM injection. Liver damage, neurological decline, and molecular analyses of bile acid signaling were performed. Total bile acid levels were increased in the cortex of AOM-treated mice. Reducing serum bile acids via cholestyramine feeding or using Cyp7A1(-/-) mice reduced bile acid levels and delayed AOM-induced neurological decline, whereas cholic acid or deoxycholic acid feeding worsened AOM-induced neurological decline. The expression of bile acid signaling machinery apical sodium-dependent bile acid transporter, FXR, and small heterodimer partner increased in the frontal cortex, and blocking FXR signaling delayed AOM-induced neurological decline. In conclusion, circulating bile acids may play a pathological role during hepatic encephalopathy, although precisely how they dysregulate normal brain function is unknown. Strategies to minimize serum bile acid concentrations may reduce the severity of neurological complications associated with liver failure.

New discovery rarely runs smooth: an update on progranulin/TNFR interactions

Progranulin (PGRN) is a growth factor implicated in various pathophysiological processes, including wound healing, inflammation, tumorigenesis, and neurodegeneration. It was previously reported that PGRN binds to tumor necrosis factor receptors (TNFR) and has therapeutic effects in inflammatory arthritis (Tang et. al, in Science 332:478-484, 2011); however, Chen et al. reported their inability to demonstrate the PGRN-TNFR interactions under their own conditions (Chen et. al, in J Neurosci 33:9202-9213, 2013). A letter-to-editor was then published by the original group in response to the Chen et al. paper that discussed the reasons for the latter's inability to recapitulate the interactions. In addition, the group published follow-up studies that further reinforced and dissected the interactions of PGRN-TNFR. Recently, the dispute about the legitimacy of PGRN-TNFR interactions appears to be finally settled with independent confirmations of these interactions in various conditions by numerous laboratories. This review presents a chronological update on the story of PGRN-TNFR interactions, highlighting the independent confirmations of these interactions in various diseases and conditions.

Progranulin promotes colorectal cancer proliferation and angiogenesis through TNFR2/Akt and ERK signaling pathways

Progranulin (PGRN) has been shown to be involved in the process of inflammation, wound healing, and cartilage development; and its role in the progression of breast and ovarian cancer is also well established. However, the expression status of PGRN in colorectal cancers (CRCs) and its molecular mechanisms responsible for tumorigenesis have not been addressed so far. Herein, we demonstrated that PGRN was highly expressed and had clinical relevance with CRCs since its overexpression was associated with advanced stages of CRCs, poorer patients' prognosis, and increased expression of proliferation and angiogenesis markers. PGRN up-regulation significantly promoted the expression of Ki67 and vascular endothelial growth factor A (VEGF-A) as well as the growth rate in CRC cell lines, while PGRN down-regulation had the opposite effects. Strikingly, PGRN derived from CRCs could directly induce proliferation, migration, tubule formation, as well as VEGF-A expression in human umbilical vein endothelial cells (HUVECs). Furthermore, we provided mechanistic evidences that the regulation of Ki67 and VEGF-A expression by PGRN was mediated by tumor necrosis factor receptor 2 (TNFR2)/Akt and the ERK signaling pathways in both CRC cells and HUVECs. Taken together, these findings suggested that PGRN could promote proliferation and angiogenesis through TNFR2/Akt and ERK signaling pathways in CRCs, providing the new insight into the mechanism of PGRN in tumor proliferation and angiogenesis.

TGR5 signaling reduces neuroinflammation during hepatic encephalopathy

Hepatic encephalopathy (HE) is a serious neurological complication of acute and chronic liver failure. Expression of the neurosteroid/bile acid receptor Takeda G protein-coupled receptor 5 (TGR5) has been demonstrated in the brain and is thought to be neuroprotective. However, it is unknown how TGR5 signaling can influence the progression and associated neuroinflammation of HE. HE was induced in C57Bl/6 mice via intraperitoneal injection of azoxymethane (AOM) and tissue was collected throughout disease progression. TGR5 expression was elevated in the frontal cortex following AOM injection in mice. The cellular localization of TGR5 was found in both neurons and microglia in the cortex of C57Bl/6 mice. Central infusion of the TGR5 agonist, betulinic acid, prior to AOM injection delayed neurological decline, increased cortical cyclic adenosine monophosphate concentrations, reduced microglia activation and proliferation, and reduced proinflammatory cytokine production. Betulinic acid treatment in vitro reduced the neuronal expression of chemokine ligand 2, a chemokine previously demonstrated to contribute to HE pathogenesis. Lastly, treatment of the microglia cell line EOC-20 with conditioned media from betulinic acid-treated primary neurons decreased phagocytic activity and cytokine production. Together, these data identify that activation of TGR5, which is up-regulated during HE, alleviates neuroinflammation and improves outcomes of AOM-treated mice through neuron and microglia paracrine signaling.

The molecular basis for development of proinflammatory autoantibodies to progranulin

Recently we identified in a wide spectrum of autoimmune diseases frequently occurring proinflammatory autoantibodies directed against progranulin, a direct inhibitor of TNFR1 & 2 and of DR3. In the present study we investigated the mechanisms for the breakdown of self-tolerance against progranulin. Isoelectric focusing identified a second, differentially electrically charged progranulin isoform exclusively present in progranulin-antibody-positive patients. Alkaline phosphatase treatment revealed this additional progranulin isoform to be hyperphosphorylated. Subsequently Ser81, which is located within the epitope region of progranulin-antibodies, was identified as hyperphosphorylated serine residue by site directed mutagenesis of candidate phosphorylation sites. Hyperphosphorylated progranulin was detected exclusively in progranulin-antibody-positive patients during the courses of their diseases. The occurrence of hyperphosphorylated progranulin preceded seroconversions of progranulin-antibodies, indicating adaptive immune response. Utilizing panels of kinase and phosphatase inhibitors, PKCβ1 was identified as the relevant kinase and PP1 as the relevant phosphatase for phosphorylation and dephosphorylation of Ser81. In contrast to normal progranulin, hyperphosphorylated progranulin interacted exclusively with inactivated (pThr320) PP1, suggesting inactivated PP1 to cause the detectable occurrence of phosphorylated Ser81 PGRN. Investigation of possible functional alterations of PGRN due to Ser81 phosphorylation revealed, that hyperphosphorylation prevents the interaction and thus direct inhibition of TNFR1, TNFR2 and DR3, representing an additional direct proinflammatory effect. Finally phosphorylation of Ser81 PGRN alters the conversion pattern of PGRN. In conclusion, inactivated PP1 induces hyperphosphorylation of progranulin in a wide spectrum of autoimmune diseases. This hyperphosphorylation prevents direct inhibition of TNFR1, TNFR2 and DR3 by PGRN, alters the conversion of PGRN, and is strongly associated with the occurrence of neutralizing, proinflammatory PGRN-antibodies, indicating immunogenicity of this alternative secondary modification.

Gli1 activation and protection against hepatic encephalopathy is suppressed by circulating transforming growth factor β1 in mice

BACKGROUND & AIMS

Hepatic encephalopathy (HE) is a neurologic disorder that develops during liver failure. Few studies exist investigating systemic-central signalling during HE outside of inflammatory signalling. The transcription factor Gli1, which can be modulated by hedgehog signalling or transforming growth factor β1 (TGFβ1) signalling, has been shown to be protective in various neuropathies. We measured Gli1 expression in brain tissues from mice and evaluated how circulating TGFβ1 and canonical hedgehog signalling regulate its activation.

METHODS

Mice were injected with azoxymethane (AOM) to induce liver failure and HE in the presence of Gli1 vivo-morpholinos, the hedgehog inhibitor cyclopamine, Smoothened vivo-morpholinos, a Smoothened agonist, or TGFβ-neutralizing antibodies. Molecular analyses were used to assess Gli1, hedgehog signalling, and TGFβ1 signalling in the liver and brain of AOM mice and HE patients.

RESULTS

Gli1 expression was increased in brains of AOM mice and in HE patients. Intra-cortical infusion of Gli1 vivo-morpholinos exacerbated the neurologic deficits of AOM mice. Measures to modulate hedgehog signalling had no effect on HE neurological decline. Levels of TGFβ1 increased in the liver and serum of mice following AOM administration. TGFβ neutralizing antibodies slowed neurologic decline following AOM administration without significantly affecting liver damage. TGFβ1 inhibited Gli1 expression via a SMAD3-dependent mechanism. Conversely, inhibiting TGFβ1 increased Gli1 expression.

CONCLUSIONS

Cortical activation of Gli1 protects mice from induction of HE. TGFβ1 suppresses Gli1 in neurons via SMAD3 and promotes the neurologic decline. Strategies to activate Gli1 or inhibit TGFβ1 signalling might be developed to treat patients with HE.

Suppression of Ov-grn-1 encoding granulin of Opisthorchis viverrini inhibits proliferation of biliary epithelial cells

Multistep processes likely underlie cholangiocarcinogenesis induced by chronic infection with the fish-borne liver fluke, Opisthorchis viverrini. One process appears to be cellular proliferation of the host bile duct epithelia driven by excretory-secretory (ES) products of this pathogen. Specifically, the secreted growth factor Ov-GRN-1, a liver fluke granulin, is a prominent component of ES and a known driver of hyper-proliferation of cultured human and mouse cells in vitro. We show potent hyper-proliferation of human cholangiocytes induced by low nanomolar levels of recombinant Ov-GRN-1 and similar growth produced by low microgram concentrations of ES products and soluble lysates of the adult worm. To further explore the influence of Ov-GRN-1 on the flukes and the host cells, expression of Ov-grn-1 was repressed using RNA interference. Expression of Ov-grn-1 was suppressed by 95% by day 3 and by ~100% by day 7. Co-culture of Ov-grn-1 suppressed flukes with human cholangiocyte (H-69) or human cholangiocarcinoma (KKU-M214) cell lines retarded cell hyper-proliferation by 25% and 92%, respectively. Intriguingly, flukes in which expression of Ov-grn-1 was repressed were less viable in culture, suggesting that Ov-GRN-1 is an essential growth factor for survival of the adult stage of O. viverrini, at least in vitro. To summarize, specific knock down of Ov-grn-1 reduced in vitro survival and capacity of ES products to drive host cell proliferation. These findings may help to contribute to a deeper understanding of liver fluke induced cholangiocarcinogenesis.

Plasma levels of progranulin and interleukin-6 in frontotemporal lobar degeneration

We have measured plasma progranulin and interleukin-6 in 230 patients with frontotemporal lobar degeneration (FTLD), 104 patients with Alzheimer's disease, and 161 control subjects. We have replicated previous findings of decreased levels of progranulin protein in FTLD because of mutations in GRN and show this is not observed in FTLD cases because of other causes. interleukin-6 levels were increased in FTLD overall, but these did not discriminate between clinical and genetic subtypes.

Neuronal CCL2 is upregulated during hepatic encephalopathy and contributes to microglia activation and neurological decline

Background

Acute liver failure leads to systemic complications with one of the most dangerous being a decline in neurological function, termed hepatic encephalopathy. Neurological dysfunction is exacerbated by an increase of toxic metabolites in the brain that lead to neuroinflammation. Following various liver diseases, hepatic and circulating chemokines, such as chemokine ligand 2 (CCL2), are elevated, though their effects on the brain following acute liver injury and subsequent hepatic encephalopathy are unknown. CCL2 is known to activate microglia in other neuropathies, leading to a proinflammatory response. However, the effects of CCL2 on microglia activation and the pathogenesis of hepatic encephalopathy following acute liver injury remain to be determined.

Methods

Hepatic encephalopathy was induced in mice via injection of azoxymethane (AOM) in the presence or absence of INCB 3284 dimesylate (INCB), a chemokine receptor 2 inhibitor, or C 021 dihydrochloride (C021), a chemokine receptor 4 inhibitor. Mice were monitored for neurological decline and time to coma (loss of all reflexes) was recorded. Tissue was collected at coma and used for real-time PCR, immunoblots, ELISA, or immunostaining analyses to assess the activation of microglia and consequences on pro-inflammatory cytokine expression.

Results

Following AOM administration, microglia activation was significantly increased in AOM-treated mice compared to controls. Concentrations of CCL2 in the liver, serum, and cortex were significantly elevated in AOM-treated mice compared to controls. Systemic administration of INCB or C021 reduced liver damage as assessed by serum liver enzyme biochemistry. Administration of INCB or C021 significantly improved the neurological outcomes of AOM-treated mice, reduced microglia activation, reduced phosphorylation of ERK1/2, and alleviated AOM-induced cytokine upregulation.

Conclusions

These findings suggest that CCL2 is elevated systemically following acute liver injury and that CCL2 is involved in both the microglia activation and neurological decline associated with hepatic encephalopathy. Methods used to modulate CCL2 levels and/or reduce CCR2/CCR4 activity may be potential therapeutic targets for the management of hepatic encephalopathy due to acute liver injury.

Growth factor progranulin contributes to cervical cancer cell proliferation and transformation in vivo and in vitro

OBJECTIVE

The growth factor progranulin (PGRN) is overexpressed in a number of tumors. We aimed to investigate the expression and role of PGRN in cervical cancer tumorigenesis.

METHODS

PGRN expression and secretion was assessed in cells and normal and cancerous cervical tissues by Western blot analysis, ELISA or immunohistochemistry. The role of PGRN in cervical carcinogenesis was explored by cell-proliferation, colony-formation and tumor-growth assays. We assessed the role of PGRN-mediated signaling in the cervical cell with specific inhibitors.

RESULTS

PGRN expression was upregulated in cervical cancer cell lines and tissue. PGRN promoted the transformation of human cervical mucosa epithelial H8 cells in vitro and tumor formation in vivo. Knockdown of PGRN expression in cervical cancer cells in vivo decreased cell proliferation and slowed tumor growth. PGRN stimulated cervical cell proliferation, and transformation was mediated, at least in part, by Akt and Erk signaling.

CONCLUSIONS

PGRN is overexpressed in cervical cancer and promotes the malignant growth and transformation of cervical cells. Therefore, PGRN plays a critical role in carcinogenesis of cervical cancer and shows promise for therapeutic strategies for cervical cancer.

Progranulin promotes Temozolomide resistance of glioblastoma by orchestrating DNA repair and tumor stemness

Glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults with a dismal prognosis. Current therapy of surgical removal combined with Temozolomide (TMZ) and radiation therapy only slightly prolongs the survival of GBM patients. Thus, it is essential to elucidate mechanism underlying its highly malignant properties in order to develop efficacious therapeutic regimens. In this study, we showed that progranulin (PGRN) was overexpressed in most GBM cell lines and the majority of human tumor samples. PGRN overexpression conferred GBM cells with tumorigenic properties and TMZ resistance by upregulating DNA repair (PARP, ATM, BRCA1, Rad51, XRCC1 and so on) and cancer stemness (CD133, CD44, ABCG2) genes, in part via an AP-1 transcription factor, specifically cFos/JunB. Curcumin, an AP-1 inhibitor, was also found to regulate PGRN promoter activity and expression including its downstream effectors aforementioned. These data suggested a feedforward loop between PGRN signaling and AP-1. PGRN depletion significantly decreased unlimited self-renewal and multilineage differentiation and the malignant properties of GBMs cells S1R1, and enhanced their vulnerability to TMZ. In addition, S1R1 depleted of PGRN also lost the ability to form tumor in an orthotopic xenograft mouse model. In conclusion, PGRN had a critical role in the pathogenesis and chemoresistance of GBM and functioned at the top of the hierarchy of cellular machinery that modulates both DNA repair pathways and cancer stemness. Our data suggest that a new strategy combining current regimens with compounds targeting PGRN/AP-1 loop like curcumin may significantly improve the therapeutic outcome of GBM.

Novel diagnostic and prognostic biomarkers in biliary tract cancer

INTRODUCTION

The worldwide incidence of biliary tract carcinoma (BTC, tumours of the bile ducts and gall-bladder) continues to rise, with the only potentially curative treatment remaining surgical resection or transplantation, possible in only a minority of patients. Late presentation and a paucity of effective treatments mandate the development of techniques for early lesion detection.

AREAS COVERED

This article reviews currently available biomarkers for the diagnosis and prognosis of BTC, as well as recently published studies describing novel serum, bile and urinary biomarkers.

EXPERT OPINION

The incorporation of novel analysis techniques, such as digital image analysis and fluorescence in situ hybridization, into existing management algorithms enhances the accuracy of brush cytology taken at the time of therapeutic endoscopy. However, a key goal is the discovery of reliable non-invasive biomarkers with high sensitivity and specificity. Recent advances in gene sequencing and expression, clonal evolution and tumour heterogeneity in other cancers should advance understanding of BTC tumour biology and facilitate biomarker discovery.

Gankyrin promotes tumor growth and metastasis through activation of IL-6/STAT3 signaling in human cholangiocarcinoma

Although gankyrin is involved in the tumorigenicity and metastasis of some malignancies, the role of gankyrin in cholangiocarcinoma (CCA) is unclear. In this study we investigated the expression of gankyrin in human CCA tissues and cell lines. The effects of gankyrin on CCA tumor growth and metastasis were determined both in vivo and in vitro. The results showed that gankyrin was overexpressed in CCA tissues and cell lines. Gankyrin expression was associated with CCA histological differentiation, TNM stage, and metastasis. The multivariate Cox analysis revealed that gankyrin was an independent prognostic indicator for overall survival. Gankyrin overexpression promoted CCA cell proliferation, migration, and invasion, while gankyrin knockdown inhibited CCA tumor growth, metastasis, and induced Rb-dependent senescence and G1 phase cell cycle arrest. Gankyrin increased the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and promoted the nuclear translocation of p-STAT3. Suppression of STAT3 signaling by small interfering RNA (siRNA) or STAT3 inhibitor interfered with gankyrin-mediated carcinogenesis and metastasis, while interleukin (IL)-6, a known upstream activator of STAT3, could restore the proliferation and migration of gankyrin-silenced CCA cells. The IL-6 level was decreased by gankyrin knockdown, while increased by gankyrin overexpression. Gankyrin regulated IL-6 expression by way of facilitating the phosphorylation of Rb; meanwhile, rIL-6 treatment increased the expression of gankyrin, suggesting that IL-6 was regulated by a positive feedback loop involving gankyrin in CCA. In the xenograft experiments, gankyrin overexpression accelerated tumor formation and increased tumor weight, whereas gankyrin knockdown showed the opposite effects. The in vivo spontaneous metastasis assay revealed that gankyrin promoted CCA metastasis through IL-6/STAT3 signaling pathway.

CONCLUSION

Gankyrin is crucial for CCA carcinogenesis and metastasis by activating IL-6/STAT3 signaling pathway through down-regulating Rb protein.

A solid-phase assay for studying direct binding of progranulin to TNFR and progranulin antagonism of TNF/TNFR interactions

The discovery that TNF receptors (TNFR) serve as the binding receptors for progranulin (PGRN) reveals the significant role of PGRN in inflammatory and autoimmune diseases, including inflammatory arthritis. Herein we describe a simple, antibody-free analytical assay, i.e., a biotin-based solid-phase binding assay, to examine the direct interaction of PGRN/TNFR and the PGRN inhibition of TNF/TNFR interactions. Briefly, a 96-well high-binding microplate is first coated with the first protein (protein A), and after blocking, the coated microplate is incubated with the biotin-labeled second protein (protein B) in the absence or presence of the third protein (protein C). Finally the streptavidin conjugated with a detecting enzyme is added, followed by a signal measurement. Also discussed in this chapter are the advantages of the strategy, key elements to obtain reliable results, and discrepancies among various PGRN proteins in view of the binding activity with TNFR.

Activation of the PD-1 pathway contributes to immune escape in EGFR-driven lung tumors

The success in lung cancer therapy with programmed death (PD)-1 blockade suggests that immune escape mechanisms contribute to lung tumor pathogenesis. We identified a correlation between EGF receptor (EGFR) pathway activation and a signature of immunosuppression manifested by upregulation of PD-1, PD-L1, CTL antigen-4 (CTLA-4), and multiple tumor-promoting inflammatory cytokines. We observed decreased CTLs and increased markers of T-cell exhaustion in mouse models of EGFR-driven lung cancer. PD-1 antibody blockade improved the survival of mice with EGFR-driven adenocarcinomas by enhancing effector T-cell function and lowering the levels of tumor-promoting cytokines. Expression of mutant EGFR in bronchial epithelial cells induced PD-L1, and PD-L1 expression was reduced by EGFR inhibitors in non-small cell lung cancer cell lines with activated EGFR. These data suggest that oncogenic EGFR signaling remodels the tumor microenvironment to trigger immune escape and mechanistically link treatment response to PD-1 inhibition.

SIGNIFICANCE

We show that autochthonous EGFR-driven lung tumors inhibit antitumor immunity by activating the PD-1/PD-L1 pathway to suppress T-cell function and increase levels of proinflammatory cytokines. These findings indicate that EGFR functions as an oncogene through non-cell-autonomous mechanisms and raise the possibility that other oncogenes may drive immune escape.

Progranulin is a novel independent predictor of disease progression and overall survival in chronic lymphocytic leukemia

Progranulin (Pgrn) is a 88 kDa secreted protein with pleiotropic functions including regulation of cell cycle progression, cell motility, wound repair and tumorigenesis. Using microarray based gene expression profiling we have recently demonstrated that the gene for Pgrn, granulin (GRN), is significantly higher expressed in aggressive CD38(+)ZAP-70(+) as compared to indolent CD38(-)ZAP-70(-) chronic lymphocytic leukemia (CLL) cases. Here, we measured Pgrn plasma concentrations by enzyme-linked immunosorbent assay (ELISA) in the Essen CLL cohort of 131 patients and examined Pgrn for association with established prognostic markers and clinical outcome. We found that high Pgrn plasma levels were strongly associated with adverse risk factors including unmutated IGHV status, expression of CD38 and ZAP-70, poor risk cytogenetics (11q-, 17p-) as detected by flourescence in situ hybridization (FISH) and high Binet stage. Pgrn as well as the aforementioned risk factors were prognostic for time to first treatment and overall survival in this series. Importantly, these results could be confirmed in the independent multicentric CLL1 cohort of untreated Binet stage A patients (n = 163). Here, multivariate analysis of time to first treatment revealed that high risk Pgrn (HR = 2.06, 95%-CI = 1.13-3.76, p = 0.018), unmutated IGHV status (HR = 5.63, 95%-CI = 3.05-10.38, p<0.001), high risk as defined by the study protocol (HR = 2.06, 95%-CI = 1.09-3.89, p = 0.026) but not poor risk cytogenetics were independent prognostic markers. In summary our results suggest that Pgrn is a novel, robust and independent prognostic marker in CLL that can be easily measured by ELISA.

The challenge of cholangiocarcinoma: dissecting the molecular mechanisms of an insidious cancer

Cholangiocarcinoma is a fatal cancer of the biliary epithelium and has an incidence that is increasing worldwide. Survival beyond a year of diagnosis is less than 5%, and therapeutic options are few. Known risk factors include biliary diseases such as primary sclerosing cholangitis and parasitic infestation of the biliary tree, but most cases are not associated with any of these underlying diseases. Numerous in vitro and in vivo models, as well as novel analytical techniques for human samples, are helping to delineate the many pathways implicated in this disease, albeit at a frustratingly slow pace. As yet, however, none of these studies has been translated into improved patient outcome and, overall, the pathophysiology of cholangiocarcinoma is still poorly understood. There remains an urgent need for new approaches and models to improve management of this insidious and devastating disease. In this review, we take a bedside-to-bench approach to discussing cholangiocarcinoma and outline research opportunities for the future in this field.

The novel growth factor, progranulin, stimulates mouse cholangiocyte proliferation via sirtuin-1-mediated inactivation of FOXO1

Progranulin (PGRN), a secreted growth factor, regulates the proliferation of various epithelial cells. Its mechanism of action is largely unknown. Sirtuin 1 (Sirt1) is a protein deacetylase that is known to regulate the transcriptional activity of the forkhead receptor FOXO1, thereby modulating the balance between proapoptotic and cell cycle-arresting genes. We have shown that PGRN is overexpressed in cholangiocarcinoma and stimulates proliferation. However, its effects on hyperplastic cholangiocyte proliferation are unknown. In the present study, the expression of PGRN and its downstream targets was determined after bile duct ligation (BDL) in mice and in a mouse cholangiocyte cell line after stimulation with PGRN. The effects of PGRN on cholangiocyte proliferation were assessed in sham-operated (sham) and BDL mice treated with PGRN or by specifically knocking down endogenous PGRN expression using Vivo-Morpholinos or short hairpin RNA. PGRN expression and secretion were upregulated in proliferating cholangiocytes isolated after BDL. Treatment of mice with PGRN increased biliary mass and cholangiocyte proliferation in vivo and in vitro and enhanced cholangiocyte proliferation observed after BDL. PGRN treatment decreased Sirt1 expression and increased the acetylation of FOXO1, resulting in the cytoplasmic accumulation of FOXO1 in cholangiocytes. Overexpression of Sirt1 in vitro prevented the proliferative effects of PGRN. Conversely, knocking down PGRN expression in vitro or in vivo inhibited cholangiocyte proliferation. In conclusion, these data suggest that the upregulation of PGRN may be a key feature stimulating cholangiocyte proliferation. Modulating PGRN levels may be a viable technique for regulating the balance between ductal proliferation and ductopenia observed in a variety of cholangiopathies.

Progranulin antibodies in autoimmune diseases

Systemic vasculitides constitute a heterogeneous group of diseases. Autoimmunity mediated by B lymphocytes and their humoral effector mechanisms play a major role in ANCA-associated vasculitis (AAV) as well as in non-ANCA associated primary systemic vasculitides and in the different types of autoimmune connective tissue disorders and rheumatoid arthritis. In order to detect autoantibodies in systemic vasculitides, we screened protein macroarrays of human cDNA expression libraries with sera from patients with ANCA-associated and ANCA-negative primary systemic vasculitides. This approach led to the identification of antibodies against progranulin, a 88 kDA secreted glycoprotein with strong anti-inflammatory activity in the course of disease of giant-cell arteritis/polymyalgia rheumatica (14/65), Takayasu's arteritis (4/13), classical panarteritis nodosa (4/10), Behcet's disease (2/6) and in the course of disease in granulomatosis with polyangiitis (31/75), Churg-Strauss syndrome (7/23) and in microscopic polyangiitis (7/19). In extended screenings the progranulin antibodies were also detected in other autoimmune diseases such as systemic lupus erythematosus (39/91) and rheumatoid arthritis (16/44). Progranulin antibodies were detected only in 1 of 97 healthy controls. Anti-progranulin positive patients with systemic vasculitides, systemic lupus erythematosus or rheumatoid arthritis had significant lower progranulin plasma levels, indicating a neutralizing effect. In light of the anti-inflammatory effects of progranulin, progranulin antibodies might exert pro-inflammatory effects thus contributing to the pathogenesis of the respective autoimmune diseases and might serve as a marker for disease activity. This hypothesis is supported by the fact that a positive progranulin antibody status was associated with active disease in granulomatosis with polyangiitis.

Insights into the role of progranulin in immunity, infection, and inflammation

PGRN, a pleiotrophic growth factor, is known to play an important role in the maintenance and regulation of the homeostatic dynamics of normal tissue development, proliferation, regeneration, and the host-defense response and therefore, has been widely studied in the fields of infectious diseases, wound healing, tumorigenesis, and neuroproliferative and degenerative diseases. PGRN has also emerged as a multifaceted immune-regulatory molecule through regulating the signaling pathways known to be critical for immunology, especially TNF/TNFR signaling. In this review, we start with updates about the interplays of PGRN with ECM proteins, proteolytic enzymes, inflammatory cytokines, and cell-surface receptors, as well as various pathophysiological processes involved. We then review the data supporting an emerging role of PGRN in the fields of the "Cubic of I", namely, immunity, infection, and inflammation, with special focus on its regulation of autoimmune syndromes. We conclude with insights into the immunomodulating, anti-inflammatory, therapeutic potential of PGRN in treating diseases with an inflammatory etiology in a vast range of medical specialties.

Monoamine oxidase A expression is suppressed in human cholangiocarcinoma via coordinated epigenetic and IL-6-driven events

The secretion of dopamine and serotonin is increased in cholangiocarcinoma, which has growth-promoting effects. Monoamine oxidase A (MAOA), the degradation enzyme of serotonin and dopamine, is suppressed in cholangiocarcinoma via an unknown mechanism. The aims of this study were to (i) correlate MAOA immunoreactivity with pathophysiological parameters of cholangiocarcinoma, (ii) determine the mechanism by which MAOA expression is suppressed and (iii) evaluate the consequences of restored MAOA expression in cholangiocarcinoma. MAOA expression was assessed in cholangiocarcinoma and nonmalignant controls. The control of MAOA expression by promoter hypermethylation was evaluated and the contribution of interleukin-6 (IL-6) signaling to the suppression of MAOA expression was determined. The effects of MAOA overexpression on cholangiocarcinoma growth and invasion were also assessed. MAOA expression is correlated with differentiation, invasion and survival in cholangiocarcinoma. The MAOA promoter was hypermethylated immediately upstream of the start codon in cholangiocarcinoma samples and cell lines but not in nonmalignant counterparts. IL-6 signaling also decreased MAOA expression via a mechanism independent of hypermethylation, involving the regulation of the balance between SP-1 transcriptional activity and its inhibitor, R1 repressor. Inhibition of both IL-6 signaling and DNA methylation restored MAOA levels to those observed in cholangiocytes. Forced MAOA overexpression inhibited cholangiocarcinoma growth and invasion. MAOA expression is suppressed by the coordinated control of promoter hypermethylation and IL-6 signaling. MAOA may be a useful prognostic marker in the management of cholangiocarcinoma, and therapies designed to increase MAOA expression might prove beneficial in the treatment of cholangiocarcinoma.

The tumorigenic liver fluke Opisthorchis viverrini--multiple pathways to cancer

Liver fluke infection caused by Opisthorchis viverrini is a major public health problem in Thailand and adjacent countries. In addition to infection-associated morbidity, infection with O. viverrini and the related Clonorchis sinensis are unarguable risk factors for cholangiocarcinoma (CAA, bile-duct cancer). Here we review the pathogenesis of opisthorchiasis and the association between O. viverrini infection and bile-duct cancer, focusing on the molecular parallels between wound healing, chronic inflammation, and cancer development. We review a schema for human disease progression from fluke infection, chronic opisthorchiasis, advanced periductal fibrosis, and cholangiocarcinogenesis, and present a rationale for biomarker discovery to facilitate early intervention. We conclude by addressing post-genomic advances with a view to developing new control strategies to combat this infectious cancer.

Progranulin as a prognostic biomarker for breast cancer recurrence in patients who had hormone receptor-positive tumors: a cohort study

BACKGROUND

Progranulin (PGRN) is considered to play an important role in breast cancer tumorigenesis and in inhibiting tamoxifen-induced apoptosis. We aimed to determine whether PGRN levels are associated with breast cancer recurrence after curative surgery.

METHODOLOGY/PRINCIPAL FINDINGS

We evaluated the associations between preoperative serum PGRN levels and breast cancer recurrence in a cohort of 697 newly diagnosed breast cancer patients who underwent curative surgery between April 2001 and December 2004. The mean age ± standard deviation (SD) was 46 ± 9.8 years, and all patients with hormone receptor (HR)-positive tumors received adjuvant tamoxifen therapy. At a median follow-up of 62.2 months (range, 2.9-98.2), 89 patients (12.8%) had experienced a recurrence and 51 patients (7.3%) had died. In the HR-positive group, serum PGRN levels were associated with recurrence according to the log-rank test for trend (p for trend = 0.049). There was no association between PGRN levels and recurrence in the HR-negative group (p for trend = 0.658). Adjusted hazard ratios, including possible confounders, revealed a linear relationship between serum PGRN levels and recurrence in the HR-positive group (p for trend = 0.049), and this association was further strengthened after excluding patients who had no lymph node metastasis (p for trend = 0.038).

CONCLUSIONS/SIGNIFICANCE

Serum PGRN levels were clinically significant for predicting recurrence in patients with HR-positive breast cancer during adjuvant tamoxifen therapy.

Regulation of progranulin expression in human microglia and proteolysis of progranulin by matrix metalloproteinase-12 (MMP-12)

Background

The essential role of progranulin (PGRN) as a neurotrophic factor has been demonstrated by the discovery that haploinsufficiency due to GRN gene mutations causes frontotemporal lobar dementia. In addition to neurons, microglia in vivo express PGRN, but little is known about the regulation of PGRN expression by microglia.

Goal

In the current study, we examined the regulation of expression and function of PGRN, its proteolytic enzyme macrophage elastase (MMP-12), as well as the inhibitor of PGRN proteolysis, secretory leukocyte protease inhibitor (SLPI), in human CNS cells.

Methods

Cultures of primary human microglia and astrocytes were stimulated with the TLR ligands (LPS or poly IC), Th1 cytokines (IL-1/IFNγ), or Th2 cytokines (IL-4, IL-13). Results were analyzed by Q-PCR, immunoblotting or ELISA. The roles of MMP-12 and SLPI in PGRN cleavage were also examined.

Results

Unstimulated microglia produced nanogram levels of PGRN, and PGRN release from microglia was suppressed by the TLR ligands or IL-1/IFNγ, but increased by IL-4 or IL-13. Unexpectedly, while astrocytes stimulated with proinflammatory factors released large amounts of SLPI, none were detected in microglial cultures. We also identified MMP-12 as a PGRN proteolytic enzyme, and SLPI as an inhibitor of MMP-12-induced PGRN proteolysis. Experiments employing PGRN siRNA demonstrated that microglial PGRN was involved in the cytokine and chemokine production following TLR3/4 activation, with its effect on TNFα being the most conspicuous.

Conclusions

Our study is the first detailed examination of PGRN in human microglia. Our results establish microglia as a significant source of PGRN, and MMP-12 and SLPI as modulators of PGRN proteolysis. Negative and positive regulation of microglial PGRN release by the proinflammatory/Th1 and the Th2 stimuli, respectively, suggests a fundamentally different aspect of PGRN regulation compared to other known microglial activation products. Microglial PGRN appears to function as an endogenous modulator of innate immune responses.