Cyr61/CCN1 is regulated by Wnt/β-catenin signaling and plays an important role in the progression of hepatocellular carcinoma

CYR61 confers chemoresistance by upregulating survivin expression in triple-negative breast cancer

Cysteine-rich angiogenic inducer 61 (CYR61) is a protein from the CCN family of matricellular proteins that play diverse regulatory roles in the extracellular matrix. CYR61 is involved in cell adhesion, migration, proliferation, differentiation, apoptosis, and senescence. Here, we show that CYR61 induces chemoresistance in triple-negative breast cancer (TNBC). We observed that CYR61 is overexpressed in TNBC patients, and CYR61 expression correlates negatively with the survival of patients who receive chemotherapy. CYR61 knockdown reduced cell migration, sphere formation and the cancer stem cell (CSC) population and increased the chemosensitivity of TNBC cells. Mechanistically, CYR61 activated Wnt/β-catenin signaling and increased survivin expression, which are associated with chemoresistance, the epithelial-mesenchymal transition, and CSC-like phenotypes. Altogether, our study demonstrates a novel function of CYR61 in chemotherapy resistance in breast cancer.

Neuronally differentiated macula densa cells regulate tissue remodeling and regeneration in the kidney

Tissue regeneration is limited in several organs, including the kidney, contributing to the high prevalence of kidney disease globally. However, evolutionary and physiological adaptive responses and the presence of renal progenitor cells suggest an existing remodeling capacity. This study uncovered endogenous tissue remodeling mechanisms in the kidney that were activated by the loss of body fluid and salt and regulated by a unique niche of a minority renal cell type called the macula densa (MD). Here, we identified neuronal differentiation features of MD cells that sense the local and systemic environment and secrete angiogenic, growth, and extracellular matrix remodeling factors, cytokines and chemokines, and control resident progenitor cells. Serial intravital imaging, MD nerve growth factor receptor and Wnt mouse models, and transcriptome analysis revealed cellular and molecular mechanisms of these MD functions. Human and therapeutic translation studies illustrated the clinical potential of MD factors, including CCN1, as a urinary biomarker and therapeutic target in chronic kidney disease. The concept that a neuronally differentiated key sensory and regulatory cell type responding to organ-specific physiological inputs controls local progenitors to remodel or repair tissues may be applicable to other organs and diverse tissue-regenerative therapeutic strategies.

Matrix-bound Cyr61/CCN1 is required to retain the properties of the bone marrow mesenchymal stem cell niche but is depleted with aging

Previously, we showed that extracellular matrices (ECMs), produced ex vivo by various types of stromal cells, direct bone marrow mesenchymal stem cells (BM-MSCs) in a tissue-specific manner and recapitulate physiologic changes characteristic of the aging microenvironment. In particular, BM-MSCs obtained from elderly donors and cultured on ECM produced by young BM stromal cells showed improved quantity, quality and osteogenic differentiation. In the present study, we searched for matrix components that are required for a functional BM-MSC niche by comparing ECMs produced by BM stromal cells from "young" (≤25 y/o) versus "elderly" (≥60 y/o) donors. With increasing donor age, ECM fibrillar organization and mechanical integrity deteriorated, along with the ability to promote BM-MSC proliferation and responsiveness to growth factors. Proteomic analyses revealed that the matricellular protein, Cyr61/CCN1, was present in young, but undetectable in elderly, BM-ECM. To assess the role of Cyr61 in the BM-MSC niche, we used genetic methods to down-regulate the incorporation of Cyr61 during production of young ECM and up-regulate its incorporation in elderly ECM. The results showed that Cyr61-depleted young ECM lost the ability to promote BM-MSC proliferation and growth factor responsiveness. However, up-regulating the incorporation of Cyr61 during synthesis of elderly ECM restored its ability to support BM-MSC responsiveness to osteogenic factors such as BMP-2 and IGF-1. We next examined aging bone and compared bone mineral density and Cyr61 content of L4-L5 vertebral bodies in "young" (9-11 m/o) and "elderly" (21-33 m/o) mice. Our analyses showed that low bone mineral density was associated with decreased amounts of Cyr61 in osseous tissue of elderly versus young mice. Our results strongly demonstrate a novel role for ECM-bound Cyr61 in the BM-MSC niche, where it is responsible for retention of BM-MSC proliferation and growth factor responsiveness, while depletion of Cyr61 from the BM niche contributes to an aging-related dysregulation of BM-MSCs. Our results also suggest new potential therapeutic targets for treating age-related bone loss by restoring specific ECM components to the stem cell niche.

Cezanne is a critical regulator of pathological arterial remodelling by targeting β-catenin signalling

AIMS

Pathological arterial remodelling including neointimal hyperplasia and atherosclerosis is the main underlying cause for occluding arterial diseases. Cezanne is a novel deubiquitinating enzyme, functioning as a NF-кB negative regulator, and plays a key role in renal inflammatory response and kidney injury induced by ischaemia. Here we attempted to examine its pathological role in vascular smooth muscle cell (VSMC) pathology and arterial remodelling.

METHODS AND RESULTS

Cezanne expression levels were consistently induced by various atherogenic stimuli in VSMCs, and in remodelled arteries upon injury. Functionally, VSMCs over-expressing wild-type Cezanne, but not the mutated catalytically-inactive Cezanne (C209S), had an increased proliferative ability and mobility, while the opposite was observed in VSMCs with Cezanne knockdown. Surprisingly, we observed no significant effects of Cezanne on VSMC apoptosis, NF-κB signalling, or inflammation. RNA-sequencing and biochemical studies showed that Cezanne drives VSMC proliferation by regulating CCN family member 1 (CCN1) by targeting β-catenin for deubiquitination. Importantly, local correction of Cezanne expression in the injured arteries greatly decreased VSMC proliferation, and prevented arterial inward remodelling. Interestingly, global Cezanne gene deletion in mice led to smaller atherosclerotic plaques, but with a lower level of plaque stability. Translating, we observed a similar role for Cezanne in human VSMCs, and higher expression levels of Cezanne in human atherosclerotic lesions.

CONCLUSION

Cezanne is a key regulator of VSMC proliferation and migration in pathological arterial remodelling. Our findings have important implications for therapeutic targeting Cezanne signalling and VSMC pathology in vascular diseases.

The WNT1G177C mutation specifically affects skeletal integrity in a mouse model of osteogenesis imperfecta type XV

The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV (OI-XV) has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteoblasts. Although such an influence was supported by subsequent studies, a mouse model of OI-XV remained to be established. Therefore, we introduced a previously identified disease-causing mutation (G177C) into the murine Wnt1 gene. Homozygous Wnt1^G177C/G177C mice were viable and did not display defects in brain development, but the majority of 24-week-old Wnt1^G177C/G177C mice had skeletal fractures. This increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix quality. Importantly, the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5, the latter mimicking the effect of sclerostin neutralization. Finally, transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix modifiers. Taken together, our data demonstrate that regulating bone matrix quality is a primary function of WNT1. They further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.

The Wnt/β-catenin signaling pathway in the tumor microenvironment of hepatocellular carcinoma

The Wnt/β-catenin signaling pathway regulates many aspects of tumor biology, and many studies have focused on the role of this signaling pathway in tumor cells. However, it is now clear that tumor development and metastasis depend on the two-way interaction between cancer cells and their environment, thereby forming a tumor microenvironment (TME). In this review, we discuss how Wnt/β-catenin signaling regulates cross-interactions among different components of the TME, including immune cells, stem cells, tumor vasculature, and noncellular components of the TME in hepatocellular carcinoma. We also investigate their preclinical and clinical insights for primary liver cancer intervention, and explore the significance of using Wnt/β-catenin mutations as a biomarker to predict resistance in immunotherapy.

Dual agonist-antagonist effect of ulipristal acetate in human endometrium and myometrium

The aim of this study was to assess the molecular effect of ulipristal acetate (UPA) on gene expression in myometrium and endometrium of patients with symptomatic fibroids. Tissues isolated from four women treated preoperatively with UPA (5 mg) were compared to those from untreated controls using NanoString platform to assess the expression of 75 candidate genes modulated by UPA and ovarian steroids. Deregulated genes were then validated by real-time PCR. In myometrium, UPA exerted an antagonistic effect similar to that observed in fibroids. In UPA-treated endometrium, six genes were identified as highly and significantly upregulated, including matricellular genes CCN1 (54-fold, P = 0.0018) and CCN2 (11-fold, P = 0.00044), Krüppel-like factor 4 (>3-fold, P = 0.0036), and mast cell markers including tryptases TPSAB1/TPSB2 (31-fold, P = 0.023) and carboxypeptidase A (CPA3, 17-fold, P = 0.05). In endometrium, UPA induced the expression of genes involved in fibrogenesis and mast cell function-some of them being widely involved in hepatic injury, which could explain the marked fibrosis and inflammatory cell infiltration observed in explanted livers from patients under UPA treatment.

Constitutive androstane receptor induced-hepatomegaly and liver regeneration is partially via yes-associated protein activation

The constitutive androstane receptor (CAR, NR3I1) belongs to nuclear receptor superfamily. It was reported that CAR agonist TCPOBOP induces hepatomegaly but the underlying mechanism remains largely unknown. Yes-associated protein (YAP) is a potent regulator of organ size. The aim of this study is to explore the role of YAP in CAR activation-induced hepatomegaly and liver regeneration. TCPOBOP-induced CAR activation on hepatomegaly and liver regeneration was evaluated in wild-type (WT) mice, liver-specific YAP-deficient mice, and partial hepatectomy (PHx) mice. The results demonstrate that TCPOBOP can increase the liver-to-body weight ratio in wild-type mice and PHx mice. Hepatocytes enlargement around central vein (CV) area was observed, meanwhile hepatocytes proliferation was promoted as evidenced by the increased number of KI67⁺ cells around portal vein (PV) area. The protein levels of YAP and its downstream targets were upregulated in TCPOBOP-treated mice and YAP translocation can be induced by CAR activation. Co-immunoprecipitation results suggested a potential protein–protein interaction of CAR and YAP. However, CAR activation-induced hepatomegaly can still be observed in liver-specific YAP-deficient (Yap^–/–) mice. In summary, CAR activation promotes hepatomegaly and liver regeneration partially by inducing YAP translocation and interaction with YAP signaling pathway, which provides new insights to further understand the physiological functions of CAR.

Role of Wnt/β-catenin signaling pathway in occurrence and development of hepatocellular carcinoma

Studies have shown that the occurrence and development of liver cancer are related to a variety of signaling pathways. The Wnt/β-catenin signaling pathway is involved in all stages of liver disease progression, from initial liver damage to inflammation, fibrosis, and cirrhosis, as well as the occurrence and progression of tumors. Abnormal Wnt/β-catenin signaling promotes the development and progression of different liver diseases, including cancer. This review introduces the activation, biological function, and regulatory mechanism of the Wnt/β-catenin signaling pathway, discusses the role of ngthis pathway in the occurrence and progression of liver cancer, and describes factors that can inhibit the Wnt/β-catenin signaling pathway, such as small molecule inhibitors, traditional Chinese medicine extracts, and microRNAs, with an aim to provide reference for the basic and clinical research of liver cancer.

Oncogenic transcriptomic profile is sustained in the liver after the eradication of the hepatitis C virus

Hepatocellular carcinoma (HCC) developing after hepatitis C virus (HCV) eradication is a serious clinical concern. However, molecular basis for the hepatocarcinogenesis after sustained virologic response (SVR) remains unclear. In this study, we aimed to unveil the transcriptomic profile of post-SVR liver tissues and explore the molecules associated with post-SVR carcinogenesis. We analysed 90 RNA sequencing datasets, consisting of non-cancerous liver tissues including 20 post-SVR, 40 HCV-positive and 7 normal livers, along with Huh7 cell line specimens before and after HCV infection and eradication. Comparative analysis demonstrated that cell cycle- and mitochondrial function-associated pathways were altered only in HCV-positive non-cancerous liver tissues, whereas some cancer-related pathways were up-regulated in the non-cancerous liver tissues of both post-SVR and HCV-positive cases. The persistent up-regulation of carcinogenesis-associated gene clusters after viral clearance was reconfirmed through in vitro experiments, of which, CYR61, associated with liver fibrosis and carcinogenesis in several cancer types, was the top enriched gene and co-expressed with cell proliferation-associated gene modules. To evaluate whether this molecule could be a predictor of hepatocarcinogenesis after cure of HCV infection, we also examined 127 sera from independent HCV-positive cohorts treated with direct-acting antivirals (DAAs), including 60 post-SVR-HCC patients, and found that the elevated serum Cyr61 was significantly associated with early carcinogenesis after receiving DAA therapy. In conclusion, some oncogenic transcriptomic profiles are sustained in liver tissues after HCV eradication, which might be a molecular basis for the liver cancer development even after viral clearance. Among them, up-regulated CYR61 could be a possible biomarker for post-SVR-HCC.

PDLIM2 prevents the malignant phenotype of hepatocellular carcinoma cells by negatively regulating β-catenin

Hepatocellular carcinoma (HCC) is one of the most common malignancies and leading causes of cancer-related deaths globally. Despite significant advances in therapy, the molecular mechanisms underlying HCC development and progression remain unclear. Here, we aimed to explore the potential role of PDLIM2 in the development and epithelial-mesenchymal transition (EMT) of HCC via a possible modulation of β-catenin. We first confirmed that PDLIM2 was downregulated in HCC tissues and cells and found lower PDLIM2 expression was associated with worse prognosis in HCC patients. Loss- and gain- of function experiments were performed to evaluate the roles of PDLIM2 and β-catenin in HCC cell proliferation, migration, invasion, EMT, and colony formation. EMT was determined based on the levels of E-cadherin, zonula occludens-1, N-cadherin, and vimentin expression. In vivo, the roles of PDLIM2 and β-catenin in HCC were investigated by using a nude mouse xenograft model. It should be noted that PDLIM2 led to the inhibition of β-catenin activity and its downstream gene expression. Importantly, ectopic PDLIM2 expression inhibited the proliferation, migration, invasion, and EMT of HCC cells by reducing β-catenin expression both in vitro and in vivo, thereby suppressing the occurrence and progression of HCC. Taken together, our results demonstrated that overexpressed PDLIM2 exerts a tumor-suppressive role in HCC by regulating β-catenin. This study suggests that the PDLIM2 may be a promising target for the treatment of HCC.

Dickkopf‑1/cysteine‑rich angiogenic inducer 61 axis mediates palmitic acid‑induced inflammation and apoptosis of vascular endothelial cells

Cardiovascular diseases (CVDs) are a major cause of mortality around the world, and the presence of atherosclerosis is the most common characteristic in patients with CVDs. Cysteine-rich angiogenic inducer 61 (CCN1) has been reported to serve an important role in the pathogenesis of atherosclerotic lesions. The aim of the present study was to investigate whether CCN1 could regulate the inflammation and apoptosis of endothelial cells induced by palmitic acid (PA). Dickkopf-1 (DKK1) is an important antagonist of the Wnt signaling pathway, which can specifically inhibit the classic Wnt signaling pathway. Firstly, the mRNA and protein expression levels of CCN1 were detected. Additionally, endothelial nitric oxide (NO) synthase (eNOS), DKK1, β-catenin, and inflammation- and apoptosis-associated proteins were measured. Detection of NO was performed using a commercial kit. The expression levels of inflammatory cytokines were assessed to explore the effect of CCN1 on PA-induced inflammation. TUNEL assay was used to detect the apoptosis of endothelial cells. The results revealed that PA upregulated the expression levels of CCN1, inflammatory cytokines and pro-apoptotic proteins in endothelial cells. PA decreased the production of NO, and the levels of phosphorylated-eNOS, whereas knockdown of CCN1 partially abrogated these effects triggered by PA. Furthermore, the Wnt/β-catenin signaling pathway was activated in PA-induced endothelial cells; however, the levels of DKK1 were downregulated. Overexpression of DKK1 could reduce CCN1 expression via inactivation of the Wnt/β-catenin signaling pathway. In conclusion, knockdown of CCN1 attenuated PA-induced inflammation and apoptosis of endothelial cells via inactivating the Wnt/β-catenin signaling pathway.

Dermatopontin inhibits WNT signaling pathway via CXXC finger protein 4 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major cause of tumor associated deaths globally. Annually, the prevalence of HCC is increasing and the lack of early prognostic indicators manifests a dismal prognosis for HCC patients. A deep understanding of the molecular events that promote HCC progression are required for the design of new diagnostics and therapeutics. Dermatopontin (DPT) is an extracellular matrix protein that regulates the metastatic phenotypes of many cancers. However, the effects of DPT on HCC cell growth remain undefined. In this study, we demonstrate that the exogenous expression of DPT inhibits HCC cell growth both in vitro and in vivo. Furthermore, we show that DPT regulates CXXC4, which in turn targets c-Myc, EZH2, SOX2 and β-catenin, through its ability to impact Wnt signaling pathway. These data suggest that DPT regulates CXXC4, c-Myc, EZH2, SOX2 and β-catenin, through Wnt signaling to repress HCC proliferation. This highlights DPT as promising target for future HCC diagnostics and therapeutic targets.

Cyr61 overexpression induced by interleukin 8 via NF-kB signaling pathway and its role in tumorigenesis of gastric carcinoma in vitro

Cyr61 (CCN1) is a multifunctional matricellular protein in bridging inflammation and cancer, involved in many biological functions such as tumorigenesis and carcinogenesis. The role of Cyr61 in gastric cancer (GC) has not been fully understood and needs to be investigated and clarified. We examined Cyr61 expression in 6 GC cell lines and stable transfection of recombinants in to BGC823 specifically down regulated the Cyr61 mRNA and protein expression shown by the analysis with western blot, RT-PCR, western blot and immunofluorescence assay. The cells treated with siRNA shown markedly reduced activity in growth, migration and invasion compared with parental BGC823 cells as well as mock transfectants. The Cyr61 deficient cells demonstrated significantly inhibited colony formation in soft agar and reduced tumorigenicity was showed in nude mice, NF-kB pathway evidently inactivated respectively. However, under the stimulation of IL-8, the siRNA-treated cells can restore the capacity of proliferation and invasion. IL-8 can induce the high expression of Cyr61 and MMP11 through NF-kB signal pathway. Silencing of Cyr61 can inhibit or minimize the proliferation and invasiveness of gastric cancer cell. The results imply that Cyr61 enhance the proliferation and invasion of gastric cancer cells and this process is partially modulated by the IL-8 up-regulation. Cyr61 may mediate the proliferation and development of gastric carcinoma.

Up-regulation of THY1 attenuates interstitial pulmonary fibrosis and promotes lung fibroblast apoptosis during acute interstitial pneumonia by blockade of the WNT signaling pathway

Acute interstitial pneumonia (AIP) is an idiopathic pulmonary disease featuring rapid progressive dyspnea and respiratory failure. These symptoms typically develop within several days or weeks in patients without any pre-existing lung disease or external chest disease. Thymocyte differentiation antigen-1 (THY1) has been reported to have an effect on lung fibroblast proliferation and fibrogenic signaling. In this study, the mechanism of THY1 in AIP in influencing pulmonary fibrosis in terms of lung fibroblast proliferation and apoptosis was examined. An AIP mouse model with the pathological changes of lung tissues observed was established to identify the role of THY1 in the pathogenesis of AIP. The expression of THY1, a key regulator of the WNT pathway β-catenin and fibroblasts markers MMP-2, Occludin, α-SMA and Vimentin were determined. Lung fibroblasts of mice were isolated, in which THY1 expression was altered to identify roles THY1 plays in cell viability and apoptosis. A TOP/TOPflash assay was utilized to determine the activation of WNT pathway. Decrement of pulmonary fibrosis was achieved through THY1 up-regulation. The expression of MMP-2, Occludin, α-SMA, Vimentin and β-catenin, and the extent of β-catenin phosphorylation, significantly decreased, thereby indicating that THY1 overexpression inactivated WNT. Cell proliferation was inhibited and apoptosis was accelerated in lung fibroblasts transfected with vector carrying overexpressed THY1. Altogether, this study defines the potential role of THY1 in remission of AIP, via the upregulation of THY1, which renders the WNT pathway inactive. This inactivation of the WNT signaling pathway could alleviate pulmonary fibrosis by reducing lung fibroblast proliferation in AIP. Abbreviations: AIP: Acute interstitial pneumonia; ILDs: interstitial lung diseases; DAD: diffuse alveolar damage; SPF: specific-pathogen-free; NC: negative control; HCMV: human cytomegalovirus; HE: Hematoxylin-eosin; RIPA: radio-immunoprecipitation assay; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; BSA: bovine serum albumin; HRP: horseradish peroxidase; ECL: electrochemiluminescence; FBS: fetal bovine serum; DMSO: dimethyl sulfoxide; OD: optical density.

Yes-associated protein promotes early hepatocyte cell cycle progression in regenerating liver after tissue loss

The ability of the liver to restore its original volume following tissue loss has been associated with the Hippo‐YAP1 pathway, a key controller of organ size. Yes‐associated protein 1 (YAP1)—a growth effector usually restrained by Hippo signaling—is believed to be of particular importance; however, its role in liver regeneration remains ill‐defined. To explore its function, we knocked down YAP1 prior to standard 70%‐hepatectomy (sHx) using a hepatocyte‐specific nanoformulation. Knockdown was effective during the major parenchymal growth phase (S‐phase/M‐phase peaks at 32 hours/48 hours post‐sHx). Liver weight gain was completely suppressed by the knockdown at 32 hours, but was reaccelerated toward 48 hours. Likewise, proliferative markers, Ccna2/b2 and YAP1 target gene expression were downregulated at 32 hours, but re‐elevated at 48 hours post‐sHx. Nonetheless, knockdown slightly compromised survival after sHx. When assessing a model of resection‐induced liver failure (extended 86%‐hepatectomy, eHx) featuring deficient S‐ and M‐phase progression, YAP1 was not induced at 32 hours, but upregulated at 48 hours post‐eHx, confirming its dissociation from M‐phase regulation. Therefore, YAP1 is vital to push hepatocytes into cycle and through the S‐phase, but is not required for further cell cycle progression during liver regeneration. The examination of YAP1 in human livers suggested its function is conserved in the regenerating mammalian liver.

Molecular signatures for CCN1, p21 and p27 in progressive mantle cell lymphoma

Mantle cell lymphoma (MCL) is a comparatively rare non-Hodgkin's lymphoma characterised by overexpression of cyclin D1. Many patients present with or progress to advanced stage disease within 3 years. MCL is considered an incurable disease with median survival between 3 and 4 years. We have investigated the role(s) of CCN1 (CYR61) and cell cycle regulators in progressive MCL. We have used the human MCL cell lines REC1 < G519 < JVM2 as a model for disease aggression. The magnitude of CCN1 expression in human MCL cells is REC1 > G519 > JVM2 cells by RQ-PCR, depicting a decrease in CCN1 expression with disease progression. Investigation of CCN1 isoform expression by western blotting showed that whilst expression of full-length CCN1 was barely altered in the cell lines, expression of truncated forms (18-20 and 28-30 kDa) decreased with disease progression. We have then demonstrated that cyclin D1 and cyclin dependent kinase inhibitors (p21^CIP1and p27^KIP1) are also involved in disease progression. Cyclin D1 was highly expressed in REC1 cells (OD: 1.0), reduced to one fifth in G519 cells (OD: 0.2) and not detected by western blotting in JVM2 cells. p27^KIP1 followed a similar profile of expression as cyclin D1. Conversely, p21^CIP1 was absent in the REC1 cells and showed increasing expression in G519 and JVM2 cells. Subcellular localization detected p21^CIP1/ p27^KIP1 primarily within the cytoplasm and absent from the nucleus, consistent with altered roles in treatment resistance. Dysregulation of the CCN1 truncated forms are associated with MCL progression. In conjunction with reduced expression of cyclin D1 and increased expression of p21, this molecular signature may depict aggressive disease and treatment resistance.

ATF3 inhibits the tumorigenesis and progression of hepatocellular carcinoma cells via upregulation of CYR61 expression

Background

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers with a high incidence and high mortality in East Asia. Identifying biomarkers and clarifying the regulatory mechanisms of HCC are of great importance. Herein, we report the role and mechanism of activating transcription factor 3 (ATF3), a member of the ATF/cAMP-responsive element-binding protein family of transcription factors in HCC.

Methods

ATF3 overexpression vector and shRNAs were transfected into HCC cancer cells to upregulate or downregulate ATF3 expression. In vitro and in vivo assays were performed to investigate the functional role of ATF3 in hepatocellular carcinoma. RNA-Seq was performed to screen the differentially expressed genes downstream of ATF3. The dual-luciferase reporter assay, chromatin immunoprecipitation (Ch-IP) analysis and functional rescue experiments were used to confirm the target gene regulated by ATF3. Tissue microarrays (TMAs) comprising 236 human primary HCC tissues were obtained and immunohistochemical staining were carried out to analyze the clinical significance of ATF3.

Results

The results indicate that ATF3 significantly inhibited the proliferation and mobility of HCC cells both in vitro and in vivo. Cysteine-rich angiogenic inducer 61 (CYR61) is a key target for transcriptional regulation by ATF3. Both ATF3 and CYR61 were consistently downregulated in human HCC tissues, and their expression levels were significantly and positively correlated with each other.

Conclusions

Our findings indicate that ATF3 functions as a tumor suppressor in HCC through targeting and regulating CYR61.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0919-8) contains supplementary material, which is available to authorized users.

The matricellular protein CYR61 promotes breast cancer lung metastasis by facilitating tumor cell extravasation and suppressing anoikis

Matricellular proteins play multiple roles in primary tumor growth, local invasion and tumor angiogenesis. However, their contribution to metastasis and the putative mechanisms involved are less well characterized. In ER-negative human breast cancer, elevated expression levels of the matricellular protein Cysteine-rich angiogenic inducer 61 (CYR61) are associated with more aggressive progression. Here, we investigated the role of CYR61 in breast cancer lung metastasis using the triple negative human breast cancer cell lines MDA-MB-231 and SUM159. Silencing of CYR61 significantly decreased lung metastasis from tumors orthotopically implanted in pre-irradiated or naive mammary tissue and upon tail vein injection. Constitutive CYR61 silencing impaired cancer cell extravasation to the lung during the first 24 hours after tail vein injection. In contrast, CYR61 inducible silencing starting 24 hours after cancer cell injection had no impact on lung metastasis formation. In vitro experiments revealed that CYR61 silencing decreased cancer cell transendothelial migration and motility, reduced CYR61 levels present at the cell surface and sensitized cancer cells to anoikis. Furthermore, we demonstrate that CYR61-dependent cell survival under non-adhesive conditions relied, at least partially, on β1 integrin ligation and AMPKα signaling while it was independent of AKT, FAK and ERK1/2 activation. Our data provide the first evidence that CYR61 promotes breast cancer lung metastasis by facilitating tumor cell extravasation and protecting from anoikis during initial seeding to the lung. The uncovered CYR61-β1 integrin-AMPKα axis may serve as a potential therapeutic target to prevent breast cancer metastasis to the lung.

Cysteine-rich protein 61 regulates adipocyte differentiation from mesenchymal stem cells through mammalian target of rapamycin complex 1 and canonical Wnt signaling

Emerging evidence suggests that cysteine-rich protein 61 (CYR61) plays a role in the differentiation and development of chondrocytes, osteoblasts, and osteoclasts; however, little is known about its role in adipogenesis. The current study indicates that the expression level of Cyr61 was altered in primary cultured marrow stromal cells and the established mesenchymal cell line, C3H10T1/2, after adipogenic treatment. Overexpressing Cyr61 repressed C3H10T1/2 and primary marrow stromal cells to differentiate into mature adipocytes. Conversely, inhibition of endogenous Cyr61 induced C3H10T1/2 and primary marrow stromal cells to fully differentiate. Mechanism investigations reveal that knockdown of Cyr61 inhibited the nuclear translocation of β-catenin and decreased nuclear protein levels of β-catenin and transcription factor 7-like 2. Moreover, the silencing of Cyr61 increased protein levels of phosphorylated ribosomal protein S6 kinase B1, mammalian target of rapamycin, eukaryotic translation initiation factor 4E-binding protein 1, and ribosomal protein S6-the major components of mammalian target of rapamycin complex 1 (mTORC1) signaling-in C3H10T1/2 cells. Additional investigations demonstrated that treatment with rapamycin significantly attenuated adipocyte formation that was induced by Cyr61 small interfering RNA (siRNA) transfection. Moreover, Cyr61 siRNA also lost its ability to stimulate adipocyte formation under the background of β-catenin overexpression. Taken together, our study provides evidence that CYR61 regulates adipocyte differentiation via multiple signaling pathways that involve at least the inactivation of mTORC1 signaling and the activation of canonical Wnt signaling.-Yang, Y., Qi, Q., Wang, Y., Shi, Y., Yang, W., Cen, Y., Zhu, E., Li, X., Chen, D., Wang, B. Cysteine-rich protein 61 regulates adipocyte differentiation from mesenchymal stem cells through mammalian target of rapamycin complex 1 and canonical Wnt signaling.

CYR61 (CCN1) is a metastatic biomarker of gastric cardia adenocarcinoma

Gastric cardia adenocarcinoma (GCA) is the most aggressive subtype of gastric cancer with a high metastatic rate. In this report, we collected tumor tissue samples from 214 GCA cases and examined expression of CYR61, a target gene product of the Hippo-YAP/TAZ pathway, in the GCA tumors by immunohistochemical (IHC) staining using the tissue microarray assay (TMA). The results have shown that CYR61 is overexpressed in 44% of the GCA tumor samples. Expression of CYR61 is inversely correlated with cumulative survival of GCA patients (p<0.001) and significantly associated only with metastatic pathological categories (with N category, p=0.052; with TNM stage, p=0.001). Furthermore, knockdown of CYR61 in gastric cancer AGS cells impairs the cancer cell migration and invasion, suggesting a driver role of CYR61 in metastasis. Thus, our studies have established CYR61 as a metastatic biomarker for prediction of poor prognosis of GCA and provided a potential molecular target for anti-metastatic therapy of GCA.

A functional characteristic of cysteine-rich protein 61: Modulation of myeloid-derived suppressor cells in liver inflammation

There is increasing awareness of the immunologic roles of liver mononuclear populations, including myeloid-derived suppressor cells (MDSCs). We took advantage of a large well-defined cohort of 148 patients with liver inflammation and 45 healthy controls to focus on the qualitative and quantitative characteristics of MDSCs. We investigated the frequency, phenotype, and functional capacities of MDSCs by using peripheral blood MDSCs in a cohort of 55 patients with primary biliary cholangitis (PBC), 40 with autoimmune hepatitis, 39 with chronic hepatitis B, 14 with nonalcoholic fatty liver disease, and 45 healthy controls. This was followed by a liver-targeted determination in 27 patients with PBC, 27 with autoimmune hepatitis, 20 with chronic hepatitis B, 14 with nonalcoholic fatty liver disease, and 6 controls. We then focused on mechanisms of this expansion with PBC as an example, using both ursodeoxycholic acid-naive and treated patients. HLA-DR^-/low CD33⁺ CD11b⁺ CD14⁺ CD15^- monocytic MDSCs were elevated in diseases characterized by liver inflammation compared to healthy controls. Using PBC as a focus, there was a significant correlation between levels of circulating MDSCs and disease-related biochemical markers (alkaline phosphatase, total bilirubin). We found higher amounts of MDSCs in patients with PBC who were responsive to ursodeoxycholic acid. MDSCs from PBC were found to manifest a potent immunosuppressive function. There was a significant correlation in the accumulation of hepatic MDSCs in the inflamed lesions of PBC with histologic changes, such as fibrosis. We also found that cysteine-rich protein 61 (CCN1), a highly expressed protein in impaired cholangiocytes and hepatocytes, contributes to MDSC expansion and MDSC inducible nitric oxide synthase-associated immune suppression.

CONCLUSION

CCN1 modulates expansion and a suppressive function of MDSCs. Our data highlight the potential functions of CCN1 on MDSCs and suggest therapeutic implications in inflammatory liver diseases. (Hepatology HEPATOLOGY 2018;67:232-246).

CCN1/Cyr61 enhances the function of hepatic stellate cells in promoting the progression of hepatocellular carcinoma

Hepatic stellate cells (HSCs) are the main extracellular matrix (ECM)-producing cells in liver fibrosis. Activated HSCs stimulate the proliferation and migration of hepatocellular carcinoma (HCC) cells. Cysteine-rich 61 (CCN1/Cyr61) is an ECM protein. Our previous studies demonstrated that the expression of CCN1 was significantly higher in benign hepatic cirrhosis tissue and cancer-adjacent hepatic cirrhosis tissues. CCN1 is a target gene of β-catenin in HCC and promotes the proliferation of HCC cells. The present study aimed to examine whether CCN1 can activate HSCs and affect the function of activated HSCs in promoting the progression of HCC. CCN1 expression was determined during the progression of liver fibrosis in a mouse model. LX-2 cells, which were infected with adenoviruses AdCCN1 or AdRFP, and HepG2 cells were co-cultured or subcutaneously co-implanted into in nude mice. MTT assay, Crystal Violet staining, Boyden chamber, matrigel invasion and monolayer scratch assays were used to analyze the proliferation, migration and invasion capability of HepG2 cells. Xenograft sizes were measured and histological analyses were performed by hematoxylin and eosin, immunohistochemical, immunefluorescence and Sirius Red staining. It was demonstrated that the expression of CCN1 was continually increased in liver fibrosis and the that expression may be correlated with the progression of liver fibrosis. CCN1 affected the function of LX-2 and enhanced the effect of LX-2 on promoting the viability, migration and invasion of HepG2 cells in vitro. CCN1 enhanced the effect of LX-2 on promoting the growth of HepG2 xenografts in vivo. CCN1 also affected the function of activated HSCs and regulated the formation of the xenograft microenvironment, including fibrogenesis and angiogenesis, which are beneficial for the progression of HCC. These findings demonstrated that CCN1 may be involved in the progression of the hepatic cirrhosis-HCC axis through regulating HSCs.

Molecular basis for the recognition of CCN1 by monoclonal antibody 093G9

CCN1, also named Cyr61 (cysteine-rich protein 61), is the first identified member of the CCN family that is composed of 6 secreted extracellular matrix-associated glycoproteins. CCN1 has been demonstrated to participate in pathogenesis of rheumatoid arthritis through various pathways. A monoclonal antibody, namely, 093G9, is effective to antagonize the effects of CCN1 and hence has potential therapeutic benefits against rheumatoid arthritis. Here, we show that the epitope recognized by 093G9 is mapped to residues 77 to 80 of CCN1, and a cyclic peptide encompassing residues 75 to 81 of CCN1 displays high binding affinity for 093G9. The crystal structure of the 093G9 Fab in complex with the cyclic peptide was determined at 2.7 Å resolution, which reveals the intensive interactions between CCN1 and 093G9. Particularly, residues Asn79 and Phe80 of CCN1 are inserted into cavities mainly formed by residues of complementarity-determining region loop L3 and framework region L2 and by residues of complementarity-determining region loops H2 and H3, respectively, which contribute most of the interactions and therefore are critical for the recognition by 093G9. Together, these findings not only identify the epitope of CCN1 for 093G9 but also reveal the molecular mechanism of recognition and binding of CCN1 by 093G9.

The matricellular protein CYR61 interferes with normal pancreatic islets architecture and promotes pancreatic neuroendocrine tumor progression

The significance of matricellular proteins during development and cancer progression is widely recognized. However, how these proteins actively contribute to physiological development and pathological cancer progression is only partially elucidated. In this study, we investigated the role of the matricellular protein Cysteine-rich 61 (CYR61) in pancreatic islet development and carcinogenesis. Transgenic expression of CYR61 in β cells (Rip1CYR mice) caused irregular islets morphology and distorted sorting of α cells, but did not alter islets size, number or vascularization. To investigate the function of CYR61 during carcinogenesis, we crossed Rip1CYR mice with Rip1Tag2 mice, a well-established model of β cell carcinogenesis. Beta tumors in Rip1Tag2CYR mice were larger, more invasive and more vascularized compared to tumors in Rip1Tag2 mice. The effect of CYR61 on angiogenesis was fully abrogated by treating mice with the anti-VEGFR2 mAb DC101. Results from in vitro assays demonstrated that CYR61 modulated integrin α6β1-dependent invasion and adhesion without altering its expression. Taken together, these results show that CYR61 expression in pancreatic β cells interferes with normal islet architecture, promotes islet tumor growth, invasion and VEGF/VERGFR-2-dependent tumor angiogenesis. Taken together, these observations demonstrate that CYR61 acts as a tumor-promoting gene in pancreatic neuroendocrine tumors.

Activation of WNT/β-Catenin Signaling Enhances Pancreatic Cancer Development and the Malignant Potential Via Up-regulation of Cyr61

Pancreatic ductal adenocarcinoma (PDAC), a poor prognostic cancer, commonly develops following activating mutations in the KRAS oncogene. Activation of WNT signaling is also commonly observed in PDAC. To ascertain the impact of postnatal activation of WNT-stimulated signaling pathways in PDAC development, we combined the Elastase-tva-based RCAS-TVA pancreatic cancer model with the established LSL-Kras^G12D, Ptf1a-cre model. Delivery of RCAS viruses encoding β-catenin^S37A and WNT1 stimulated the progression of premalignant pancreatic intraepithelial neoplasias (PanIN) and PDAC development. Moreover, mice injected with RCAS-β-catenin^S37A or RCAS-Wnt1 had reduced survival relative to RCAS-GFP-injected controls (P < .05). Ectopic expression of active β-catenin, or its DNA-binding partner TCF4, enhanced transformation associated phenotypes in PDAC cells. In contrast, these phenotypes were significantly impaired by the introduction of ICAT, an inhibitor of the β-catenin/TCF4 interaction. By gene expression profiling, we identified Cyr61 as a target molecule of the WNT/β-catenin signaling pathway in pancreatic cancer cells. Nuclear β-catenin and CYR61 expression were predominantly detected in moderately to poorly differentiated murine and human PDAC. Indeed, nuclear β-catenin- and CYR61-positive PDAC patients demonstrated poor prognosis (P < .01). Knockdown of CYR61 in a β-catenin-activated pancreatic cancer cell line reduced soft agar, migration and invasion activity. Together, these data suggest that the WNT/β-catenin signaling pathway enhances pancreatic cancer development and malignancy in part via up-regulation of CYR61.

Genetic alterations in hepatocellular carcinoma: An update

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Although recent advances in therapeutic approaches for treating HCC have improved the prognoses of patients with HCC, this cancer is still associated with a poor survival rate mainly due to late diagnosis. Therefore, a diagnosis must be made sufficiently early to perform curative and effective treatments. There is a need for a deeper understanding of the molecular mechanisms underlying the initiation and progression of HCC because these mechanisms are critical for making early diagnoses and developing novel therapeutic strategies. Over the past decade, much progress has been made in elucidating the molecular mechanisms underlying hepatocarcinogenesis. In particular, recent advances in next-generation sequencing technologies have revealed numerous genetic alterations, including recurrently mutated genes and dysregulated signaling pathways in HCC. A better understanding of the genetic alterations in HCC could contribute to identifying potential driver mutations and discovering novel therapeutic targets in the future. In this article, we summarize the current advances in research on the genetic alterations, including genomic instability, single-nucleotide polymorphisms, somatic mutations and deregulated signaling pathways, implicated in the initiation and progression of HCC. We also attempt to elucidate some of the genetic mechanisms that contribute to making early diagnoses of and developing molecularly targeted therapies for HCC.

Members of the Cyr61/CTGF/NOV Protein Family: Emerging Players in Hepatic Progenitor Cell Activation and Intrahepatic Cholangiocarcinoma

Hepatic stem/progenitor cells (HPC) reside quiescently in normal biliary trees and are activated in the form of ductular reactions during severe liver damage when the replicative ability of hepatocytes is inhibited. HPC niches are full of profibrotic stimuli favoring scarring and hepatocarcinogenesis. The Cyr61/CTGF/NOV (CCN) protein family consists of six members, CCN1/CYR61, CCN2/CTGF, CCN3/NOV, CCN4/WISP1, CCN5/WISP2, and CCN6/WISP3, which function as extracellular signaling modulators to mediate cell-matrix interaction during angiogenesis, wound healing, fibrosis, and tumorigenesis. This study investigated expression patterns of CCN proteins in HPC and cholangiocarcinoma (CCA). Mouse HPC were induced by the biliary toxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Differential expression patterns of CCN proteins were found in HPC from DDC damaged mice and in human CCA tumors. In addition, we utilized reporter mice that carried Ccn2/Ctgf promoter driven GFP and detected strong Ccn2/Ctgf expression in epithelial cell adhesion molecule (EpCAM)⁺ HPC under normal conditions and in DDC-induced liver damage. Abundant CCN2/CTGF protein was also found in cytokeratin 19 (CK19)⁺ human HPC that were surrounded by α-smooth muscle actin (α-SMA)⁺ myofibroblast cells in intrahepatic CCA tumors. These results suggest that CCN proteins, particularly CCN2/CTGF, function in HPC activation and CCA development.

CYR61 and TAZ Upregulation and Focal Epithelial to Mesenchymal Transition May Be Early Predictors of Barrett's Esophagus Malignant Progression

Barrett's esophagus is the major risk factor for esophageal adenocarcinoma. It has a low but non-neglectable risk, high surveillance costs and no reliable risk stratification markers. We sought to identify early biomarkers, predictive of Barrett's malignant progression, using a meta-analysis approach on gene expression data. This in silico strategy was followed by experimental validation in a cohort of patients with extended follow up from the Instituto Português de Oncologia de Lisboa de Francisco Gentil EPE (Portugal). Bioinformatics and systems biology approaches singled out two candidate predictive markers for Barrett's progression, CYR61 and TAZ. Although previously implicated in other malignancies and in epithelial-to-mesenchymal transition phenotypes, our experimental validation shows for the first time that CYR61 and TAZ have the potential to be predictive biomarkers for cancer progression. Experimental validation by reverse transcriptase quantitative PCR and immunohistochemistry confirmed the up-regulation of both genes in Barrett's samples associated with high-grade dysplasia/adenocarcinoma. In our cohort CYR61 and TAZ up-regulation ranged from one to ten years prior to progression to adenocarcinoma in Barrett's esophagus index samples. Finally, we found that CYR61 and TAZ over-expression is correlated with early focal signs of epithelial to mesenchymal transition. Our results highlight both CYR61 and TAZ genes as potential predictive biomarkers for stratification of the risk for development of adenocarcinoma and suggest a potential mechanistic route for Barrett's esophagus neoplastic progression.

Furan-induced transcriptomic and gene-specific DNA methylation changes in the livers of Fischer 344 rats in a 2-year carcinogenicity study

Furan is a significant food contaminant and a potent hepatotoxicant and rodent liver carcinogen. The carcinogenic effect of furan has been attributed to genotoxic and non-genotoxic, including epigenetic, changes in the liver; however, the mechanisms of the furan-induced liver tumorigenicity are still unclear. The goal of the present study was to investigate the role of transcriptomic and epigenetic events in the development of hepatic lesions in Fischer (F344) rats induced by furan treatment in a classic 2-year rodent tumorigenicity bioassay. High-throughput whole-genome transcriptomic analysis demonstrated distinct alterations in gene expression in liver lesions induced in male F344 rats treated with 0.92 or 2.0 mg furan/kg body weight (bw)/day for 104 weeks. Compared to normal liver tissue, 1336 and 1541 genes were found to be differentially expressed in liver lesions in rats treated with 0.92 and 2.0 mg furan/kg bw/day, respectively, among which 1001 transcripts were differentially expressed at both doses. Pairing transcriptomic and next-generation bisulfite sequencing analyses of the common differentially expressed genes identified 42 CpG island-containing genes in which the methylation level was correlated inversely with gene expression. Forty-eight percent of these genes (20 genes, including Areg, Jag1, and Foxe1) that exhibited the most significant methylation and gene expression changes were involved in key pathways associated with different aspects of liver pathology. Our findings illustrate that gene-specific DNA methylation changes have functional consequences and may be an important component of furan hepatotoxicity and hepatocarcinogenicity.

CCN1 Regulates Chondrocyte Maturation and Cartilage Development

WNT/β-CATENIN signaling is involved in multiple aspects of skeletal development, including chondrocyte differentiation and maturation. Although the functions of β-CATENIN in chondrocytes have been extensively investigated through gain-of-function and loss-of-function mouse models, the precise downstream effectors through which β-CATENIN regulates these processes are not well defined. Here, we report that the matricellular protein, CCN1, is induced by WNT/β-CATENIN signaling in chondrocytes. Specifically, we found that β-CATENIN signaling promotes CCN1 expression in isolated primary sternal chondrocytes and both embryonic and postnatal cartilage. Additionally, we show that, in vitro, CCN1 overexpression promotes chondrocyte maturation, whereas inhibition of endogenous CCN1 function inhibits maturation. To explore the role of CCN1 on cartilage development and homeostasis in vivo, we generated a novel transgenic mouse model for conditional Ccn1 overexpression and show that cartilage-specific CCN1 overexpression leads to chondrodysplasia during development and cartilage degeneration in adult mice. Finally, we demonstrate that CCN1 expression increases in mouse knee joint tissues after meniscal/ligamentous injury (MLI) and in human cartilage after meniscal tear. Collectively, our data suggest that CCN1 is an important regulator of chondrocyte maturation during cartilage development and homeostasis.

CCN: core regulatory proteins in the microenvironment that affect the metastasis of hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) results from an underlying chronic liver inflammatory disease, such as chronic hepatitis B or C virus infections, and the general prognosis of patients with HCC still remains extremely dismal because of the high frequency of HCC metastases. Throughout the process of tumor metastasis, tumor cells constantly communicate with the surrounding microenvironment and improve their malignant phenotype. Therefore, there is a strong rationale for targeting the tumor microenvironment as primary treatment of HCC therapies. Recently, CCN family proteins have emerged as localized multitasking signal integrators in the inflammatory microenvironment. In this review, we summarize the current knowledge of CCN family proteins in inflammation and the tumor. We also propose that the CCN family proteins may play a central role in signaling the tumor microenvironment and regulating the metastasis of HCC.

The matricellular protein CCN1 suppresses hepatocarcinogenesis by inhibiting compensatory proliferation

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide, and is on the rise in the United States. Previous studies showed that the matricellular protein CCN1 (CYR61) is induced during hepatic injuries and functions to restrict and resolve liver fibrosis. Here we show that CCN1 suppresses hepatocarcinogenesis by inhibiting carcinogen-induced compensatory hepatocyte proliferation, thus limiting the expansion of damaged and potentially oncogenic hepatocytes. Consistent with tumor suppression, CCN1 expression is down-regulated in human HCC. Ccn1^ΔHep mice with hepatocyte-specific deletion of Ccn1 suffer increased HCC tumor multiplicity induced by the hepatocarcinogen diethylnitrosoamine (DEN). Knockin mice (Ccn1^dm/dm) that express an integrin α₆β₁-binding defective CCN1 phenocopied Ccn1^ΔHep mice, indicating that CCN1 acts through its α₆β₁ binding sites in this context. CCN1 effectively inhibits EGFR-dependent hepatocyte proliferation through integrin α₆-mediated accumulation of reaction oxygen species (ROS), thereby triggering p53 activation and cell cycle block. Consequently, Ccn1^dm/dm mice exhibit diminished p53 activation and elevated compensatory hepatocyte proliferation, resulting in increased HCC. Furthermore, we show that a single dose of the EGFR inhibitor erlotinib delivered prior to DEN-induced injury was sufficient to block compensatory proliferation and annihilate development of HCC nodules observed 8 months later, suggesting potential chemoprevention by targeting CCN1-inhibitable EGFR-dependent hepatocyte proliferation. Together, these results show that CCN1 is an injury response protein that functions not only to restrict fibrosis in the liver, but also to suppress hepatocarcinogenesis by inhibiting EGFR-dependent hepatocyte compensatory proliferation.

Inhibiting CCN1 blocks AML cell growth by disrupting the MEK/ERK pathway

Background

CCN1 plays distinct roles in various tumor types, but little is known regarding the role of CCN1 in leukemia.

Methods

We analyzed CCN1 protein expression in leukemia cell lines and in AML bone marrow samples. We also evaluated the effects of antibody- or siRNA-mediated inhibition of CCN1 on the growth of two AML cell lines (U937 and Kasumi-1 cells) and on the MEK/ERK pathway, β-catenin and other related genes.

Results

U937 and Kasumi-1 cells had markedly higher CCN1 expression than the 5 other leukemia cell lines, and CCN1 protein expression was higher in the AML bone marrow samples than in the normal bone marrow samples. Blocking CCN1 with an antibody in U937 and Kasumi-1 cells suppressed proliferation, increased apoptosis, down-regulated Bcl-xL and c-Myc expression, up-regulated Bax expression, and had no effect on Survivin. siRNA-mediated down-regulation of CCN1 inhibited the proliferation and colony formation of U937 and Kasumi-1 cells and increased cytarabine-induced apoptosis. Furthermore, CCN1 siRNA reduced MEK and ERK phosphorylation without affecting β-catenin; the CCN1 antibody similarly affected MEK and ERK phosphorylation. These changes in phosphorylation could influence the expression of Bcl-xL, c-Myc and Bax in AML cells.

Conclusions

The data suggested that CCN1 is a tumor promoter in AML that acts through the MEK/ERK pathway to up-regulate c-Myc and Bcl-xL and to down-regulate Bax.

Multilayer-omics analysis of renal cell carcinoma, including the whole exome, methylome and transcriptome

The aim of this study was to identify pathways that have a significant impact during renal carcinogenesis. Sixty-seven paired samples of both noncancerous renal cortex tissue and cancerous tissue from patients with clear cell renal cell carcinomas (RCCs) were subjected to whole-exome, methylome and transcriptome analyses using Agilent SureSelect All Exon capture followed by sequencing on an Illumina HiSeq 2000 platform, Illumina Infinium HumanMethylation27 BeadArray and Agilent SurePrint Human Gene Expression microarray, respectively. Sanger sequencing and quantitative reverse transcription-PCR were performed for technical verification. MetaCore software was used for pathway analysis. Somatic nonsynonymous single-nucleotide mutations, insertions/deletions and intragenic breaks of 2,153, 359 and 8 genes were detected, respectively. Mutations of GCN1L1, MED12 and CCNC, which are members of CDK8 mediator complex directly regulating β-catenin-driven transcription, were identified in 16% of the RCCs. Mutations of MACF1, which functions in the Wnt/β-catenin signaling pathway, were identified in 4% of the RCCs. A combination of methylome and transcriptome analyses further highlighted the significant role of the Wnt/β-catenin signaling pathway in renal carcinogenesis. Genetic aberrations and reduced expression of ERC2 and ABCA13 were frequent in RCCs, and MTOR mutations were identified as one of the major disrupters of cell signaling during renal carcinogenesis. Our results confirm that multilayer-omics analysis can be a powerful tool for revealing pathways that play a significant role in carcinogenesis.

A review on the diagnosis and treatment of hepatocellular carcinoma with a focus on the role of Wnts and the dickkopf family of Wnt inhibitors

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. There are multiple etiologic factors including viral and environmental influences that can lead to HCC. Successful screening for early HCC is challenging due to the lack of well characterized and specific biomarkers. However, achieving successful screening is critically important as early diagnosis can potentially provide curative opportunities. Once HCC is advanced, there are multiple therapeutic venues, but most eventually fail, therefore developing new targeted therapies may provide greater chance for effective therapies. Along these lines, the Wnt pathway has been identified as contributing to the development and progression of HCC. Wnts can modify HCC growth and invasive ability. A key factor in the Wnt pathway is the dickkopf (DKK) family of Wnt inhibitors. DKKs have also been shown to modulate HCC progression. Additionally, several studies have suggested that DKK expression in tissue and serum has diagnostic and prognostic value.

Matricellular protein CCN1 (CYR61) expression is associated with high-grade ductal carcinoma in situ

Cysteine-rich protein 61, connective tissue growth factor, and nephroblastoma overexpressed gene (CCN) comprise a family of matricellular proteins that have multiple physiologic functions including development, tissue repair, cell adhesion, migration, and proliferation. The expression of CCN1, cyclin D1, β-catenin, and p53 was explored by immunohistochemistry in different grades of ductal carcinoma in situ (DCIS) cases. These cases did not contain any infiltrating carcinoma components. In addition, all cysteine-rich protein 61 gene exons (encoding the CCN1 protein) were sequenced in 30 samples. Allred and H-scores were calculated for expression in both DCIS and the surrounding benign breast tissue. All cases of DCIS showed degrees of cytoplasmic CCN1 staining with median H-scores of 170, 160, and 60 in grades 3, 2, and 1, respectively (P = .043). Twelve of 28 DCIS 3, 1 of 15 DCIS 2, and 0 of 18 DCIS 1 also showed nuclear staining for CCN1. The cytoplasmic staining difference was preserved when the cases were divided into estrogen receptor (ER)+/DCIS grade 1, ER+/DCIS 2 and 3, and ER-/DCIS 2 and 3 by the H-score (P = .037). Cyclin D1 expression was positively correlated with the CCN1 cytoplasmic H-score in all DCIS samples (P = .038). Membranous β-catenin expression correlated with the grade of intraepithelial carcinoma by both H-score (P = .047) and Allred score (P = .026). Our results suggest that CCN1 has a role in the development of intraepithelial carcinoma. CCN1 expression correlates with grade of DCIS independent of ER status. It can induce cell cycle progression through cyclin D1. It is warranted to study high expression of CCN1 in DCIS as an independent risk factor in a larger cohort.

Aging increases CCN1 expression leading to muscle senescence

Using microarray analysis, we found that aging sarcopenia is associated with a sharp increase in the mRNA of the matricellular protein CCN1 (Cyr61/CTGF/Nov). CCN1 mRNA was upregulated 113-fold in muscle of aged vs. young rats. CCN1 protein was increased in aging muscle in both rats (2.8-fold) and mice (3.8-fold). When muscle progenitor cells (MPCs) were treated with recombinant CCN1, cell proliferation was decreased but there was no change in the myogenic marker myoD. However, the CCN1-treated MPCs did express a senescence marker (SA-βgal). Interestingly, we found CCN1 increased p53, p16(Ink4A), and pRP (hypophosphorylated retinoblastoma protein) protein levels, all of which can arrest cell growth in MPCs. When MPCs were treated with aged rodent serum CCN1 mRNA increased by sevenfold and protein increased by threefold suggesting the presence of a circulating regulator. Therefore, we looked for a circulating regulator. Wnt-3a, a stimulator of CCN1 expression, was increased in serum from elderly humans (2.6-fold) and aged rodents (2.0-fold) compared with young controls. We transduced C2C12 myoblasts with wnt-3a and found that CCN1 protein was increased in a time- and dose-dependent manner. We conclude that in aging muscle, the circulating factor wnt-3a acts to increase CCN1 expression, prompting muscle senescence by activating cell arrest proteins.

Enhancer of zeste homolog 2 activates wnt signaling through downregulating CXXC finger protein 4

Through silencing tumor suppressor genes, epigenetic changes can activate signaling pathways important to cancer development. In this report, we found an epigenetic contribution to the aberrant activation of wnt signaling in human gastric cancer. CXXC4 (CXXC finger protein 4) was identified as a novel target of EZH2 (enhancer of zeste homolog 2), and EZH2 promotes the activation of wnt singaling by downregulating CXXC4 expression. CXXC4 inhibits the growth of gastric cancer cells both in vitro and in vivo through inactivating wnt signaling. In contrast, depletion of CXXC4 activates wnt signaling and promotes the anchorage-independent growth of nontumor gastric epithelial cells. CXXC4 is downregulated in gastric carcinoma tissues and its downregulation is associated with poor outcome of gastric cancer patients (hazard ratio: 5.053, P<0.05). Through its binding to dishevelled (Dvl), CXXC4 stabilizes the destruction complex of β-catenin to inhibit wnt signaling. Two critical amino acid residues in CXXC4, K161 and T162 were found to be important to its binding to Dvl and the growth inhibitory effect of CXXC4. In summary, EZH2 promotes the activation of wnt signaling in gastric carcinogenesis through the downregulation of CXXC4 expression. CXXC4 is a novel potential tumor suppressor directly regulated by EZH2, and its expression is a significant prognosis factor for patients with early stages of gastric cancer.

Cyr61, a matricellular protein, is needed for dendritic arborization of hippocampal neurons

The shape of the dendritic arbor is one of the criteria of neuron classification and reflects functional specialization of particular classes of neurons. The development of a proper dendritic branching pattern strongly relies on interactions between the extracellular environment and intracellular processes responsible for dendrite growth and stability. We previously showed that mammalian target of rapamycin (mTOR) kinase is crucial for this process. In this work, we performed a screen for modifiers of dendritic growth in hippocampal neurons, the expression of which is potentially regulated by mTOR. As a result, we identified Cyr61, an angiogenic factor with unknown neuronal function, as a novel regulator of dendritic growth, which controls dendritic growth in a β1-integrin-dependent manner.