Lymphoid Enhancer Factor Research Articles

Multiple genes of the renin-angiotensin system are novel targets of Wnt/β-catenin signaling.

Activation of the renin-angiotensin system (RAS) plays an essential role in the pathogenesis of CKD and cardiovascular disease. However, current anti-RAS therapy only has limited efficacy, partly because of compensatory upregulation of renin expression. Therefore, a treatment strategy to simultaneously target multiple RAS genes is necessary to achieve greater efficacy. By bioinformatics analyses, we discovered that the promoter regions of all RAS genes contained putative T-cell factor (TCF)/lymphoid enhancer factor (LEF)-binding sites, and β-catenin induced the binding of LEF-1 to these sites in kidney tubular cells. Overexpression of either β-catenin or different Wnt ligands induced the expression of all RAS genes. Conversely, a small-molecule β-catenin inhibitor ICG-001 abolished RAS induction. In a mouse model of nephropathy induced by adriamycin, either transient therapy or late administration of ICG-001 abolished established proteinuria and kidney lesions. ICG-001 inhibited renal expression of multiple RAS genes in vivo and abolished the expression of other Wnt/β-catenin target genes. Moreover, ICG-001 therapy restored expression of nephrin, podocin, and Wilms' tumor 1, attenuated interstitial myofibroblast activation, repressed matrix expression, and inhibited renal inflammation and fibrosis. Collectively, these studies identify all RAS genes as novel downstream targets of Wnt/β-catenin. Our results indicate that blockade of Wnt/β-catenin signaling can simultaneously repress multiple RAS genes, thereby leading to the reversal of established proteinuria and kidney injury.

MicroRNA-26b represses colon cancer cell proliferation by inhibiting lymphoid enhancer factor 1 expression.

microRNAs (miR) can act as oncogenes and tumor suppressors and several miRs are associated with cancer development and progression through the modulation of multiple cellular processes. miR26b is downregulated in several cancers and tumors and miR26b directly targets the lymphoid enhancer factor 1 (Lef1)3'UTR and inhibits endogenous Lef1 expression. We report that miR26b expression is associated with human colon cancer through the regulation of LEF1 expression in colon cancer cells. Analyses of multiple colon cancer cell lines revealed an inverse correlation between miR26b and LEF1 expression. Normal human colon cells express low levels of LEF1 and high levels of miR26b; however, human colon cancer cells have decreased miR26b expression and increased LEF1 expression. We demonstrate that miR26b expression is a potent inhibitor of colon cancer cell proliferation and significantly decreases LEF1 expression. The LEF1-regulated genes cyclin D1 and c-Myc were indirectly repressed by miR26b and this was consistent with decreased proliferation. miR26b overexpression in SW480 colon cancer cells also inhibited tumor growth in nude mice and this was due to decreased tumor growth and not apoptosis. Analyses of human colon cancer databases also demonstrated a link between miR26b and LEF1 expression. c-Myc expression is associated with multiple cancers and we propose that miR26b may act as a potential therapeutic agent in reducing cancer cell proliferation through repressing LEF1 activation of c-Myc and cyclin D1 expression.

Myricetin enhances osteogenic differentiation through the activation of canonical Wnt/β-catenin signaling in human bone marrow stromal cells

Myricetina flavonoid compound, has been reported to possess antioxidative, antiproliferative and anti-inflammatory effects. However, no study has yet investigated the effect of myricetin on osteogenic differentiation of human bone marrow stem cells (hBMSCs). This study was designed to investigate the effects of myricetin on osteogenic differentiation of hBMSCs in vitro. Cell viability was analyzed by MTT and osteogenic differentiation was evaluated by alkaline phosphatase (ALP) activity assay, Alizarin red S dye, real time-polymerase chain reaction (RT-PCR) and Western blot analysis. We found that the ALP activity and the mineralization of hBMSCs were enhanced by treatment with myricetin. Myricetin increased the mRNA expressions of Osteocalcin (OCN), Collagen type I (COL-I), ALP and Runt-related transcription factor 2 (RUNX2). Additionally, we found that myricetin activated the Wnt/β-catenin pathway and increased the expression of several downstream genes including T-cell factor-1(TCF-1) and lymphoid enhancer factor-1 (LEF-1). Depletion of β-catenin almost completely blocked the positive role of myricetin on osteogenic differentiation. Taken together, our findings suggest that myricetin enhanced osteogenic differentiation of hBMSCs by activating the Wnt/β-catenin signaling. The study may aid in the development of a therapeutic approach utilizing myricetin for the enhancement of bone health and prevention of osteoporosis.

A Growth-Promoting Signaling Component Cyclin D1 in Neural Stem Cells Has Antiastrogliogenic Function to Execute Self-Renewal

Self-renewing proliferation of neural stem cells (NSCs) is intimately linked to the inhibition of neuronal and glial differentiation, however, their molecular linkage has been poorly understood. We have proposed a model previously explaining partly this linkage, in which fibroblast growth factor 2 (FGF2) and Wnt signals cooperate to promote NSC self-renewal via β-catenin accumulation, which leads to the promotion of proliferation by lymphoid enhancer factor (LEF)/T-cell factor (TCF)-mediated cyclin D1 expression and at the same time to the inhibition of neuronal differentiation by β-catenin-mediated potentiation of Notch signaling. To fully understand the mechanisms underlying NSC self-renewal, it needs to be clarified how these growth factor signals inhibit glial differentiation as well. Here, we demonstrate that cyclin D1, a NSC growth promoting signaling component and also a common component of FGF2 and Wnt signaling pathways, inhibits astroglial differentiation of NSCs. Interestingly, this effect of cyclin D1 is mediated even though its cell cycle progression activity is blocked. Forced downregulation of cyclin D1 enhances astrogliogenesis of NSCs in culture and in vivo. We further demonstrate that cyclin D1 binds to STAT3, a transcription factor downstream of astrogliogenic cytokines, and suppresses its transcriptional activity on the glial fibrillary acidic protein (Gfap) gene. Taken together with our previous finding, we provide a novel molecular mechanism for NSC self-renewal in which growth promoting signaling components activated by FGF2 and Wnts inhibit neuronal and glial differentiation.

Enhanced prostacyclin formation and Wnt signaling in sclerostin deficient osteocytes and bone

We show that prostacyclin production is increased in bone and osteocytes from sclerostin (Sost) knockout mice which have greatly increased bone mass. The addition of prostacyclin or a prostacyclin analog to bone forming osteoblasts enhances differentiation and matrix mineralization of osteoblasts. The increase in prostacyclin synthesis is linked to increases in β-catenin concentrations and activity as shown by enhanced binding of lymphoid enhancer factor, Lef1, to promoter elements within the prostacyclin synthase promoter. Blockade of Wnt signaling reduces prostacyclin production in osteocytes. Increased prostacyclin production by osteocytes from sclerostin deficient mice could potentially contribute to the increased bone formation seen in this condition.

Deciphering liver zonation: New insights into the β-catenin, Tcf4, and HNF4α triad

Deciphering liver zonation: New insights into the β-catenin, Tcf4, and HNF4α triad

Bortezomib inhibits STAT5-dependent degradation of LEF-1, inducing granulocytic differentiation in congenital neutropenia CD34+ cells

AbstractThe transcription factor lymphoid enhancer–binding factor 1 (LEF-1), which plays a definitive role in granulocyte colony-stimulating factor (G-CSF) receptor-triggered granulopoiesis, is downregulated in granulocytic progenitors of severe congenital neutropenia (CN) patients. However, the exact mechanism of LEF-1 downregulation is unclear. CN patients are responsive to therapeutically high doses of G-CSF and are at increased risk of developing acute myeloid leukemia. The normal expression of LEF-1 in monocytes and lymphocytes, whose differentiation is unaffected in CN, suggests the presence of a granulopoiesis-specific mechanism downstream of G-CSF receptor signaling that leads to LEF-1 downregulation. Signal transducer and activator of transcription 5 (STAT5) is activated by G-CSF and is hyperactivated in acute myeloid leukemia. Here, we investigated the effects of activated STAT5 on LEF-1 expression and functions in hematopoietic progenitor cells. We demonstrated that constitutively active STAT5a (caSTAT5a) inhibited LEF-1–dependent autoregulation of the LEF-1 gene promoter by binding to the LEF-1 protein, recruiting Nemo-like kinase and the E3 ubiquitin-ligase NARF to LEF-1, leading to LEF-1 ubiquitination and a reduction in LEF-1 protein levels. The proteasome inhibitor bortezomib reversed the defective G-CSF–triggered granulocytic differentiation of CD34+ cells from CN patients in vitro, an effect that was accompanied by restoration of LEF-1 protein levels and LEF-1 messenger RNA autoregulation. Taken together, our data define a novel mechanism of LEF-1 downregulation in CN patients via enhanced ubiquitination and degradation of LEF-1 protein by hyperactivated STAT5.

MP31-17 NOTCH 4 REGULATED, LEF1 MEDIATED PROSTATE CANCER METASTASIS AND ANDROGEN INDEPENDENCE

You have accessJournal of UrologyProstate Cancer: Basic Research II1 Apr 2014MP31-17 NOTCH 4 REGULATED, LEF1 MEDIATED PROSTATE CANCER METASTASIS AND ANDROGEN INDEPENDENCE Yirong Li, Liang Chen, Yang Yang, Hongying Huang, Jinhua Wang, Valerio Zhang, Garrett Daniels, A. de las Morenas, Hebert Lepor, Ross Basch, Xinyu Wu, Fei Ye, David Zhang, and Peng Lee Yirong LiYirong Li More articles by this author , Liang ChenLiang Chen More articles by this author , Yang YangYang Yang More articles by this author , Hongying HuangHongying Huang More articles by this author , Jinhua WangJinhua Wang More articles by this author , Valerio ZhangValerio Zhang More articles by this author , Garrett DanielsGarrett Daniels More articles by this author , A. de las MorenasA. de las Morenas More articles by this author , Hebert LeporHebert Lepor More articles by this author , Ross BaschRoss Basch More articles by this author , Xinyu WuXinyu Wu More articles by this author , Fei YeFei Ye More articles by this author , David ZhangDavid Zhang More articles by this author , and Peng LeePeng Lee More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.926AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The mechanism of Notch and Wnt on prostate cancer progression remains elusive. Our previous in vitro studies indicated that lymphoid enhancing factor 1 (LEF1) was highly expressed in androgen-independent prostate cancer cells. Furthermore, LEF1 regulated AR expression and, subsequently, growth and invasion of prostate cancer cells. In this study, we further assess the role of Notch and Wnt signaling in prostate cancer progression with human prostate cancer cells in vitro, coupled with xenograft mice model and human prostate cancer samples in vivo. METHODS Retrovirus system was used to construct stable cell lines overexpressing LEF1 (LNCaP-LEF1) in LNCaP or knockdown of LEF1 (LNCaP-AI-LEF1shRNA) in LNCaP-AI cells. Cell proliferation, invasion and migration were analyzed with WST-1 assay, matrigel assay and transwell assay in vitro. Subrenal capsule xenograft mice with LNCaP, LNCaP-LEF1, LNCaP-AI and LNCaP-AI-LEF1shRNA were established to evaluate the role of LEF1 in metastasis of prostate cancer in vivo. LEF1 expression in human benign prostatic tissue as well as primary and metastatic prostate cancer was examined by immunohistochemistry. RESULTS Overexpression of LEF1 in LNCaP cells induced epithelial-mesenchymal transition EMT). Consistent with changes of EMT morphology and marker expression, overexpression of LEF1 increased migration and invasion of prostate cancer cells in vitro. The established xenograft mice showed that mice with LNCaP-LEF1 and LNCaP-AI cells developed larger tumor volume and weight compared with that from mice with LNCaP and LNCaP-AI-LEF1shRNA, respectively. Importantly, mice injected with LNCaP-LEF1 and LNCaP-AI cells developed multi-organ metastasis while tumor only metastasized to kidney in mice with LNCaP and LNCaP-AI-LEF1shRNA cells. Interestingly, Proteomics Pathway Array Analysis (PPAA) indicated that Notch4 was overexpressed in LNCaP-AI cells and aggressive prostate cancer samples. Importantly, Notch4 was identified to be involved in regulation of LEF1 and AR expression. In agreement with these findings, LEF1 expression is not expressed in all human benign prostatic luminal cells and expressed at only 16% of primary prostate cancer, but in 47% metastatic prostate cancer cases. CONCLUSIONS Notch4-LEF1-AR axis might be critical for prostate cancer progression and LEF1 may serve as a potential biomarker for metastatic prostate carcinomas. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e328-e329 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Yirong Li More articles by this author Liang Chen More articles by this author Yang Yang More articles by this author Hongying Huang More articles by this author Jinhua Wang More articles by this author Valerio Zhang More articles by this author Garrett Daniels More articles by this author A. de las Morenas More articles by this author Hebert Lepor More articles by this author Ross Basch More articles by this author Xinyu Wu More articles by this author Fei Ye More articles by this author David Zhang More articles by this author Peng Lee More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A Wnt/β-catenin negative feedback loop represses TLR-triggered inflammatory responses in alveolar epithelial cells

Increasing evidence has demonstrated that the epithelial cells in the lung play crucial roles in regulating certain inflammatory responses by modulating Wnt signaling during microbial infection. However, the anti-microbial functions of Wnt signaling in alveolar epithelial cells remain elusive. In this report, we show that Wnt/β-catenin signaling is repressed in A549 alveolar epithelial cells during a Toll-like receptor ligand stimulation with Mycobacterium bovis Bacillus Calmette-Guerin (BCG) or lipopolysaccharide (LPS). In addition to activating TLR signaling, a stimulation of BCG or LPS led to the up-regulation of a Wnt receptor Frizzled-1, cytosolic GSK3β and Axin, and the down-regulation of nuclear β-catenin, lymphoid enhancer factor 1 and transcription factor 4. While an enhancement of β-catenin activity suppressed the TLR signal response, and substantially led to alleviate the TLR ligand-induced pro-inflammatory responses. Importantly, gain and loss of function studies by overexpressing or silencing of TLR signaling adaptor, myeloid differentiation primary response gene 88 (MyD88) further demonstrated an inverse relationship between TLR signaling and canonical Wnt signaling in A549 cells. These data imply that Wnt/β-catenin signaling acts as a negative feedback loop to suppress inflammation in alveolar epithelial cells, and averts cell injury from excessive inflammatory reactions. This study thus reveals a novel immunoregulatory mechanism in alveolar epithelial cells in response to bacterial infection.

The LEF1/CYLD axis and cIAPs regulate RIP1 deubiquitination and trigger apoptosis in selenite-treated colorectal cancer cells

Inhibitor-of-apoptosis protein (IAP) inhibitors have been reported to synergistically reduce cell viability in combination with a variety of chemotherapeutic drugs via targeted cellular IAP (cIAP) depletion. Here, we found that cIAP silencing sensitised colorectal cancer (CRC) cells to selenite-induced apoptosis. Upon selenite treatment, the K63-linked ubiquitin chains on receptor-interacting protein 1 (RIP1) were removed, leading to the formation of the death-inducing complex and subsequent caspase-8 activation. Although the ubiquitinases cIAP1 and cIAP2 were significantly downregulated after a 24-h selenite treatment, cylindromatosis (CYLD) deubiquitinase protein levels were marginally upregulated. Chromatin immunoprecipitation assays revealed that lymphoid enhancer factor-1 (LEF1) dissociated from the CYLD promoter upon selenite treatment, thus abolishing suppression of CYLD gene expression. We corroborated these findings in a CRC xenograft animal model using immunohistochemistry. Collectively, our findings demonstrate that selenite caused CYLD upregulation via LEF1 and cIAP downregulation, both of which contribute to the degradation of ubiquitin chains on RIP1 and subsequent caspase-8 activation and apoptosis. Importantly, our results identify a LEF1-binding site in the CYLD promoter as a potential target for combinational therapy as an alternative to cIAPs.

Sox2 modulatesLef-1expression during airway submucosal gland development

Tracheobronchial submucosal glands (SMGs) are derived from one or more multipotent glandular stem cells that coalesce to form a placode in surface airway epithelium (SAE). Wnt/β-catenin-dependent induction of lymphoid enhancer factor (Lef-1) gene expression during placode formation is an early event required for SMG morphogenesis. We discovered that Sox2 expression is repressed as Lef-1 is induced within airway SMG placodes. Deletion of Lef-1 did not activate Sox2 expression in SMG placodes, demonstrating that Lef-1 activation does not directly inhibit Sox2 expression. Repression of Sox2 protein in SMG placodes occurred posttranscriptionally, since the activity of its endogenous promoter remained unchanged in SMG placodes. Thus we hypothesized that Sox2 transcriptionally represses Lef-1 expression in the SAE and that suppression of Sox2 in SMG placodes activates Wnt/β-catenin-dependent induction of Lef-1 during SMG morphogenesis. Consistent with this hypothesis, transcriptional reporter assays, ChIP analyses, and DNA-protein binding studies revealed a functional Sox2 DNA binding site in the Lef-1 promoter that is required for suppressing β-catenin-dependent transcription. In polarized primary airway epithelium, Wnt induction enhanced Lef-1 expression while also inhibiting Sox2 expression. Conditional deletion of Sox2 also enhanced Lef-1 expression in polarized primary airway epithelium, but this induction was significantly augmented by Wnt stimulation. Our findings provide the first evidence that Sox2 acts as a repressor to directly modulate Wnt-responsive transcription of the Lef-1 gene promoter. These studies support a model whereby Wnt signals and Sox2 dynamically regulate the expression of Lef-1 in airway epithelia and potentially also during SMG development.

25 Nitric Oxide-cGMP Signalling Promotes B-Catenin Nuclear Translocation and Transcriptional Activity in Endothelial Cells

Nitric oxide (NO) derived from endothelial NO synthase (eNOS) exerts cardioprotective effects. eNOS binds to a number of proteins that regulate its function. Using mass spectroscopy to study eNOS immunoprecipitated...

Aberrant G-CSFR Signaling in Congenital Neutropenia

Clinical observations revealed that congenital neutropenia (CN) patients harboring either ELANE or HAX mutations have similar bone marrow morphology, responses to G-CSF therapy, requirements of G-CSF dosages, and the risk of developing leukemia. Therefore, we suggested a common pathomechanism of defective G-CSFR-triggered granulopoiesis downstream of both mutated genes in these patients. We identified severely diminished expression and functions of the transcription factors lymphoid enhancer binding factor-1 (LEF-1) and C/EBPa in myeloid cells of CN patients, in comparison to healthy individuals and patients with cyclic neutropenia (CyN). LEF-1 expression was abrogated in patients harboring either ELANE or HAX1 mutations, which suggested LEF-1 as a possible common candidate factor for defective G-CSFR signaling. We further identified a mechanism of the diminished LEF-1 expression downstream of HAX1 or ELANE mutations. HAX1 is HCLS1-Associated protein X1. HCLS1 is Hematopoietic Cell-Specific Lyn Substrate 1. We found that HCLS1 protein is expressed at high levels in human myeloid cells and is phosphorylated upon stimulation with G-CSF. HCLS1 interacted with LEF-1 protein, inducing nuclear translocation of LEF-1, LEF-1 autoregulation, C/EBPa activation, and granulocytic differentiation. In CN patients with HAX1 mutations, we found profound defects in the G-CSF-triggered phosphorylation of HCLS1, subsequently leading to abrogated nuclear transport and autoregulation of LEF-1. In CN patients with ELANE mutations we detected severely reduced levels of the natural inhibitor of neutrophil elastase (NE), and secretory leukocyte protease inhibitor (SLPI). We demonstrated the important role of SLPI in myeloid differentiation by activation of Erk1/2 phosphorylation and subsequent phErk1/2-triggered tyrosine phosphorylation and activation of the LEF-1 protein. Therefore, the direct link between ELANE mutations and diminished LEF-1 expression was established: in these patients LEF-1 protein expression is diminished due to the reduced levels of SLPI. We further evaluated how G-CSF treatment overcomes maturation arrest of granulopoiesis in CN patients despite the absence of LEF-1 and C/EBPa in myeloid cells. We identified nicotinamide phosphoribosyltransferase (NAMPT) as an essential enzyme mediating G-CSF-triggered granulopoiesis in healthy individuals and in CN patients. Treatment of healthy individuals with G-CSF resulted in upregulation of NAMPT levels in myeloid cells and in plasma. NAMPT and NAD+ amounts were even more dramatically elevated by G-CSF treatment of CN individuals. The molecular events triggered by NAMPT included elevation of NAD+, NAD+-dependent activation of protein deacetylase sirtuin-1 (SIRT1), binding of SIRT1 to the myeloid specific transcription factors C/EBPα and C/EBPβ, and activation of these transcription factors. In CN patients, C/EBPα expression is severely diminished; therefore “steady-state” granulopoiesis could not be activated. G-CSF treatment induces expression of C/EBPβ in these patients via NAMPT and SIRT1 and operated via the “emergency” pathway. We also investigated the patterns of acquisition of leukemia-associated-mutations in 31 CN patients developing leukemia using next-generation DNA deep sequencing. Intriguingly, 20 of the 31 patients (64.5%) demonstrated mutations within RUNX1. The majority of patients with RUNX1 mutations (85%) had acquired CSF3R mutations. Other leukemia-associated mutations in the patients with RUNX1 mutations were found infrequently. Cytogenetics of the leukemic cells revealed that 10 patients with RUNX1 mutations developed monosomy 7, and six patients had trisomy 21. Single cell analysis in two patients revealed that RUNX1 and CSF3R mutations were segregated in the same malignant clone. Functional studies demonstrated proliferative advantage of CD34+ cells transduced with mutated RUNX1 and CSF3R. By analysis of the leukemogenic role of the defective G-CSFR signaling in CN patients we identified a significant and sustained elevation in the levels of phospho-STAT5 in hematopoietic CD34+ cells of CN patients which were even higher in CN/ acute myeloid leukemia patients. The other possible reason for the leukemogenic transformation could be elevated NAMPT/SIRT-triggered deacetylation of tumor supressor protein p53, proto-oncogene FOXO3a and Akt proteins. Disclosures:No relevant conflicts of interest to declare.

Knockdown of Lymphoid Enhancer factor 1 Inhibits Colon Cancer Progression In Vitro and In Vivo

Expression of lymphoid enhancer factor 1 (LEF1) is frequently altered in different human cancers. This study aimed to assess LEF1 expression in colon cancer tissues and to explore changed phenotypes, gene expressions, and the possible mechanism after knocked down LEF1 expression in colon cancer cell lines. A total of 106 colon cancer and matched paratumorous normal tissues were used to assess LEF1 expression using immunohistochemistry and qRT-PCR. LEF1 lentivirus was used to knockdown LEF1 expression for the assessment of cell viability, cell cycle distribution, apoptosis, and gene expressions. The nude mouse xenograft assay was performed to detect the effects of LEF1 knockdown in vivo. The data showed that the levels of LEF1 mRNA and protein were significantly increased in human colon cancer tissues compared to the matched paratumorous normal tissues and were associated with infiltration depth, lymph node and distant metastases, advanced TNM (tumor-node-metastasis) stages, and shorter overall survival. Furthermore, LEF1 knockdown reduced tumor cell viability, invasion capacity, MMP2 and MMP-9 expression, but induced apoptosis. Nude mouse xenograft assay showed that LEF1 knockdown suppressed tumor formation and growth in vivo. In addition, the expression of Notch pathway-related proteins RBP-jκ and Hes1 was reduced in LEF1 knockdown cells. Taken together, LEF1 protein was overexpressed in colon cancer tissues and knockdown of LEF1 expression inhibited colon cancer growth in vitro and in vivo. These data suggest that targeting of LEF1 expression should be further evaluated for colon cancer prevention and therapy.

Targeting Wnt-Frizzled signaling in cardiovascular diseases

Wnts are secreted glycoproteins implicated in biological processes ranging from embryonic cardiac development to uncontrolled cell proliferation in diseased conditions. Cardiovascular disease is a major cause of morbidity and mortality worldwide. Phenotypic modulation of vascular smooth muscle cells, migration and proliferation in intimal layer and increased extracellular matrix production are some of the known hallmarks of cardiovascular pathologies. Heterogeneity associated with the binding of Wnts to their transmembrane receptors, Frizzled, and coreceptors low density lipoprotein-receptor-related protein is indeed intriguing. Nuclear-cytoplasmic shuttling of beta-catenin and activation of transcriptional factors, lymphoid enhancer factor and T cell activation factor leading to target gene activation has remained elusive. Our review highlights the emerging role of Wnt-Frizzled signaling in cardiovascular diseases. Overall, the pathway appears to be an attractive therapeutic target in identifying susceptible individuals at risk of developing restenosis/other vascular pathologies in the near future.

Expression of LEF1 is an independent prognostic factor for patients with oral squamous cell carcinoma

Lymphoid-enhancing factor 1 (LEF1) is a transcription factor mediating Wnt/β-catenin signaling. In this study, we analyzed the clinicopathologic significance of LEF1 expression in oral squamous cell carcinoma (OSCC). Expression levels of LEF1 in 135 cases of OSCC were determined by immunohistochemistry. The results were correlated with clinicopathologic parameters and patient outcome. LEF1 was only occasionally detected in basal and parabasal cells of nontumorous squamous epithelium. Overexpression of LEF1 was observed in 33 of 135 OSCCs (24%). LEF1 was more frequently expressed in moderately to poorly differentiated cancer (p = 0.0035) and was associated with lymphovascular invasion (p = 0.0252). Overexpression of LEF1 was significantly associated with poor prognosis (p = 0.0176, hazard ratio = 1.96, 95% CI = 1.02-3.75). Multivariate analysis revealed LEF1expression and margin status to be the significant independent predictors for overall survival. Our study suggests LEF1 expression in OSCC may play an important role in tumor progression and can be served as a predictor of poor prognosis for patients with OSCC.

Spatiotemporal expression of Wnt signaling pathway components during bovine placental development

It is well established that trophoblasts play a crucial role in pregnancy establishment and maintenance through production of various biological substances. In this regard, Wnt signaling is an important regulator of embryo implantation and placentation in various species. However, the role of the Wnt signaling pathway during bovine placental development has remained largely unknown. Employing multiple approaches, we herein found that Wnt2 mRNA was more abundant in cotyledon tissues compared with caruncle tissues, whereas Wnt5b mRNA was more abundant in caruncle tissues compared with cotyledon tissues. Moreover, the Wnt receptor Fzd4 was detected in caruncle epithelial cells and binucleate trophoblasts, but not in uninucleate trophoblasts. In addition, β-catenin, an integral cell-cell adhesion adaptor protein as well as transcriptional co-regulator of Wnt canonical pathway, was spatiotemporally expressed in bovine trophoblasts, with high levels of cellular accumulation and nuclear translocation, particularly in binucleate trophoblasts. Lymphoid enhancer factor-1 mRNA was more abundant in caruncle tissues compared with cotyledon tissues, which was well correlated with the expression profile of Dickkopf-1, a secreted antagonist of the canonical Wnt signaling pathway. These results provided new evidence that precisely regulated canonical Wnt activation may have a very important physiological role during fetal-maternal recognition and pregnancy maintenance in cattle.

Expression of the lymphoid enhancer factor 1 is required for normal hematopoietic stem and progenitor cell function

Expression of the lymphoid enhancer factor 1 is required for normal hematopoietic stem and progenitor cell function

Acquisition of t(11;14) in a patient with chronic lymphocytic leukemia carrying both t(14;19)(q32;q13.1) and +12

A rare recurrent chromosomal translocation, t(14;19)(q32;q13), has been identified in a variety of B-cell malignancies, including chronic lymphocytic leukemia (CLL). We report a unique case of CLL in a patient carrying both trisomy 12 and t(14;19) (q32;q13.1), in whom t(11;14)(q13;q32) developed at relapse. The patient was a 77-yr-old woman, and her lymphoma cells at presentation showed CD5(+), CD10(-), CD19(+), CD20(+)(dim), CD23(+), CD38(+), and CD11c(+). At relapse, the patient's lymphoma cells showed positive staining for cyclin D1 in addition to CD5, CD20, and CD23. Lymphoma cells in specimens at both presentation and relapse were positive for lymphoid enhancer factor 1 (LEF1) and negative for sex-determining region Y-box 11 (SOX11). IGH-BCL1 FISH became positive at relapse. Split FISH assay using BCL1, BCL3, IGH, and CCND1 probes on lymph node specimens obtained at presentation and at autopsy confirmed that the translocation of BCL3 was solely detected in the lymph node at presentation and detected BCL3 and CCND1 translocations in the specimen at autopsy. These observations indicated that IGH-BCL3 and IGH-CCND1 had occurred in the same clone after treatment of the disease. In line with immunohistochemical and cytogenetic studies, additional PCR analysis of the FR3-JH region showed the same sequence derived from IGHV4-34 in specimens obtained at disease onset and relapse.

Chibby drives β catenin cytoplasmic accumulation leading to activation of the unfolded protein response in BCR-ABL1 + cells

Chronic myeloid leukemia (CML) is a myeloproliferative disease caused by the constitutive tyrosine kinase (TK) activity of the BCR-ABL fusion protein. However, the phenotype of leukemic stem cells (LSC) is sustained by β catenin rather than by the BCR-ABL TK. β catenin activity in CML is contingent upon its stabilization proceeding from the BCR-ABL-induced phosphorylation at critical residues for interaction with the Adenomatous polyposis coli (APC)/Axin/glycogen synthase kinase 3 (GSK3) destruction complex or GSK3 inactivating mutations. Here we studied the impact of β catenin antagonist Chibby (CBY) on β catenin signaling in BCR-ABL1+ cells. CBY is a small conserved protein which interacts with β catenin and impairs β catenin-mediated transcriptional activation through two distinct molecular mechanisms: 1) competition with T cell factor (TCF) or lymphoid enhancer factor (LEF) for β catenin binding; and 2) nuclear export of β catenin via interaction with 14-3-3. We found that its enforced expression in K562 cell line promoted β catenin cytoplasmic translocation resulting in inhibition of target gene transcription. Moreover, cytoplasmic accumulation of β catenin activated the endoplasmic reticulum (ER) stress-associated pathway known as unfolded protein response (UPR). CBY-driven cytoplasmic accumulation of β catenin is also a component of BCR-ABL1+ cell response to the TK inhibitor Imatinib (IM). It evoked the UPR activation leading to the induction of BCL2-interacting mediator of cell death (BIM) by UPR sensors. BIM, in turn, contributed to the execution phase of apoptosis in the activation of ER resident caspase 12 and mobilization of Ca2+ stores.