Role Of CCN1 Research Articles

Abstract 1667: The role of CCN1 in mutant K-RAS addiction in pancreatic cancer

Abstract Mutant K-RAS addiction of pancreatic ductal adenocarcinoma cells (PDAC) coordinates their transformation, proliferation, and survival. Therefore, initially, it had an impression that targeting mutant K-RAS could be an ideal strategy to treat PDAC. However, after decades of studies, no effective RAS inhibitors reached the clinic, indicating that RAS-oncoprotein is an undruggable target in PDAC. Thus, identifying a new target linked with K-RAS signaling was most needed. Using genetically engineered cell lines and K-RAS-driven genetically engineered mouse models (KC or KPC) with or without pancreas-specific CCN1 conditional knockout background, we identified a positive feedback circuit between CCN1 and mutant K-RAS expression. Moreover, blocking this feedback via conditional knockout of CCN1 in the pancreas significantly reduced invasive phenotypes, PDAC growth, and metastasis in the lung in KC and KPC mice. Mechanistically, we found that the K-RAS-CCN1 feedback circuit is regulated by microRNA miR-145 via a feedforward mechanism. Collectively, these studies highlight the clinical potential of targeting CCN1 in PDAC. (VA Merit Grant supports this work) Citation Format: Anjali Kambhampati, Archana De, Inamul Haque, Snigdha Banerjee, Sushanta K. Banerjee. The role of CCN1 in mutant K-RAS addiction in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1667.

Role for CCN1 in lysophosphatidic acid response in PC-3 human prostate cancer cells.

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive phospholipids that act as mitogens in various cancers. Both LPA and S1P activate G-protein coupled receptors (GPCRs). We examined the role of CCN1/CYR61, an inducible matricellular protein, in LPA-induced signal transduction in PC-3 human prostate cancer cells. We found that both LPA and S1P induced expression of CCN1 and CCN2 within 2-4h. CCN1 was induced by 18:1-LPA, but not by 18:0-, 18:2-, or 18:3-LPAs. A free fatty acid receptor-4 agonist inhibited LPA-induced CCN1 induction. CCN1 appeared in the ECM within 2h after LPA addition. LPA caused biphasic activation of Erk MAPK, with an initial peak at 10-20min followed by a later phase after 6h. LPA increased adhesion of PC-3 cells to culture substrates (standard culture plates, fibronectin, or extracellular matrix) at 2h, an intermediate event between early and late LPA signals. Knockdown of CCN1 suppressed LPA-induced adhesion to ECM or fibronectin. ECM from CCN1 knockdown cells was a poor substrate for adhesion, as compared to ECM from control cells. These results suggest that CCN1 contributes to LPA responses in the tumor microenvironment. The LPA-CCN1 axis holds promise for the development of novel therapeutic strategies in cancer.

Global Proteomics Analysis of Lysophosphatidic Acid Signaling in PC-3 Human Prostate Cancer Cells: Role of CCN1.

Cysteine-rich angiogenic factor 61 (CCN1/Cyr61) is a matricellular protein that is induced and secreted in response to growth factors. Our previous work showed that 18:1-lysophosphatidic acid (LPA), which activates the G protein-coupled receptor LPAR1, induces CCN1 between 2-4 h in PC-3 human prostate cancer cells in a manner than enhances cell-substrate adhesion. While the time course of induction suggests that CCN1 contributes to intermediate events in LPA action, the roles of CCN1 in LPA-mediated signal transduction have not been fully elucidated. This study utilized a comprehensive global proteomics approach to identify proteins up- or down-regulated in response to treatment of PC-3 cells with LPA for three hours, during the time of peak CCN1 levels. In addition, the effects of siRNA-mediated CCN1 knockdown on LPA responses were analyzed. The results show that, in addition to CCN1, LPA increased the levels of multiple proteins. Proteins up-regulated by LPA included metastasis-associated in colon cancer protein 1 (MACC1) and thrombospondin-1 (TSP1/THBS1); both MACC1 and TSP1 regulated cancer cell adhesion and motility. LPA down-regulated thioredoxin interacting protein (TXNIP). CCN1 knockdown suppressed the LPA-induced up-regulation of 30 proteins; these included MACC1 and TSP1, as confirmed by immunoblotting. Gene ontology and STRING analyses revealed multiple pathways impacted by LPA and CCN1. These results indicate that CCN1 contributes to LPA signaling cascades that occur during the intermediate phase after the initial stimulus. The study provides a rationale for the development of interventions to disrupt the LPA-CCN1 axis.

The role of CCN1 in the crosstalk between pancreatic stellate cells and Panc1 cancers cells in 3D spheroids

The role of CCN1 in the crosstalk between pancreatic stellate cells and Panc1 cancers cells in 3D spheroids

Abstract 536: The role of CCN1 in mutant K-RAS addiction in pancreatic ductal adenocarcinoma

Abstract Mutant K-RAS addiction of pancreatic ductal adenocarcinoma cells (PDAC) coordinates their transformation, proliferation, and survival. Therefore, initially, it had an impression that targeting mutant K-RAS could be an ideal strategy for treating PDAC. However, after decades of studies, no effective RAS inhibitors reached the clinic, indicating that RAS-oncoprotein is an undruggable target in PDAC. Thus, identifying a new target linked with K-RAS signaling was most needed. Using genetically engineered cell lines and K-RAS-driven genetically engineered mouse models (KC or KPC) with or without pancreas-specific CCN1 conditional knockout background, we identified a positive feedback circuit between CCN1 and mutant K-RAS expression. Moreover, blocking this feedback via conditional knockout of CCN1 in the pancreas significantly reduced invasive phenotypes, PDAC growth, and metastasis in the lung in KC and KPC mice. Mechanistically we found that the K-RAS-CCN1 feedback circuit is regulated by microRNA miR-145 via a feedforward mechanism. Collectively, these studies highlight the clinical potential of targeting CCN1 in PDAC. (This work is supported by VA Merit grants). Citation Format: Archana De, Vijayalaxmi Gupta, Amlan Das, Arnab Ghosh, Inamul Haque, Laster Lau, Sushanta K. Banerjee, Snigdha Banerjee. The role of CCN1 in mutant K-RAS addiction in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 536.

CCN1 Promotes Inflammation by Inducing IL-6 Production via α6β1/PI3K/Akt/NF-κB Pathway in Autoimmune Hepatitis.

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease with unknown etiology. CCN1, an extracellular matrix-associated protein, is associated with carcinoma, inflammation, liver fibrosis, and even autoimmune diseases. However, the role that CCN1 plays in AIH has remained undetermined. In this study, expression of CCN1 in liver was detected by real-time PCR, western blot and immunohistochemistry (IHC). CCN1 level in serum was detected by ELISA. Diagnostic value of CCN1 was determined by receiver operating characteristic (ROC) curve analysis. CCN1 conditional knockout (CCN1 fl/fl Cre+) mice were generated by mating CCN1 fl/fl C57BL/6J and CAG-Cre-ERT C57BL/6J mice. Autoimmune hepatitis mice model was induced by concanavalin A (ConA). IKKα/β, IκBα, NF-κB p65 and Akt phosphorylation were determined by western blot. NF-κB p65 nuclear translocation was examined by immunofluorescence. Here, we found that CCN1 was over-expressed in hepatocytes of AIH patients. CCN1 level also increased in serum of AIH patients compared to healthy controls (HC). ROC curve analysis results showed that serum CCN1 was able to distinguish AIH patients from HD. In ConA induced hepatitis mice model, CCN1 conditional knockout (CCN1 fl/fl Cre+) attenuated inflammation by reducing ALT/AST level and IL-6 expression. In vitro, CCN1 treatment dramatically induced IL-6 production in LO2 cells. Moreover, the production of IL-6 was attenuated by CCN1 knockdown. Furthermore, we showed that CCN1 could activate IL-6 production via the PI3K/Akt/NF-κB signaling pathway by binding to α6β1 receptor. In summary, our results reveal a novel role of CCN1 in promoting inflammation by upregulation of IL-6 production in AIH. Our study also suggests that targeting of CCN1 may represent a novel strategy in AIH treatment.

Binding of the angiogenic/senescence inducer CCN1/CYR61 to integrin α6β1 drives endocrine resistance in breast cancer cells.

CCN1/CYR61 promotes angiogenesis, tumor growth and chemoresistance by binding to its integrin receptor αvβ3 in endothelial and breast cancer (BC) cells. CCN1 controls also tissue regeneration by engaging its integrin receptor α6β1 to induce fibroblast senescence. Here, we explored if the ability of CCN1 to drive an endocrine resistance phenotype in estrogen receptor-positive BC cells relies on interactions with either αvβ3 or α6β1. First, we took advantage of site-specific mutagenesis abolishing the CCN1 receptor-binding sites to αvβ3 and α6β1 to determine the integrin partner responsible for CCN1-driven endocrine resistance. Second, we explored a putative nuclear role of CCN1 in regulating ERα-driven transcriptional responses. Retroviral forced expression of a CCN1 derivative with a single amino acid change (D125A) that abrogates binding to αvβ3 partially phenocopied the endocrine resistance phenotype induced upon overexpression of wild-type (WT) CCN1. Forced expression of the CCN1 mutant TM, which abrogates all the T1, H1, and H2 binding sites to α6β1, failed to bypass the estrogen requirement for anchorage-independent growth or to promote resistance to tamoxifen. Wild-type CCN1 promoted estradiol-independent transcriptional activity of ERα and enhanced ERα agonist response to tamoxifen. The α6β1-binding-defective TM-CCN1 mutant lost the ERα co-activator-like behavior of WT-CCN1. Co-immunoprecipitation assays revealed a direct interaction between endogenous CCN1 and ERα, and in vitro approaches confirmed the ability of recombinant CCN1 to bind ERα. CCN1 signaling via α6β1, but not via αvβ3, drives an endocrine resistance phenotype that involves a direct binding of CCN1 to ERα to regulate its transcriptional activity in ER+ BC cells.

The Role of CCN1 in Esophageal Adenocarcinoma: What We Have Learned From the Lab.

Background: Esophageal cancer is one of the most common and deadliest cancers in the world, particularly esophageal adenocarcinoma. There has never been a special drug to treat it.Purpose: This article summarizes the work that we have done in our laboratory about the role of CCN1 in esophageal cancer and gives a new perspective of CCN1 biology.Research Design: This is a review article. Study Sample: The work was done using validated cell lines and fixed human tissue slides.Data Collection and Analysis: This is a review article, therefore, no data collection or analysis was involved.Results: CCN1 is a matricellular protein supporting adhesion, migration, and survival in normal cells, but in the esophageal cancer cells, it induces TRAIL-mediated apoptosis. CCN1 promotes TRAIL and its death receptor expression but downregulates the decoy receptors and survivin in a p53-dependant manner. It was thought that CCN1 relies on TNF to induce apoptosis, but our study found that these two molecules antagonize each other. CCN1 promotes TNFR1 cleavage and uses the soluble product to block TNF signaling, while TNF upregulates PGLYRP1 to overcome this obstacle because PGLYRP1 is a secreted protein that competes with TNF for TNFR1 binding. As a result, when CCN1 and TNF are present together in the vicinity of esophageal tumors, they cancel each other out.Conclusions: Based on our laboratory study, CCN1 has much potential to be a candidate for the treatment of esophageal cancer.

Effects of Lysophosphatidic Acid Receptor and Free Fatty Acid Receptor Agonists on CCN1/Cyr61 Expression in Prostate Cancer Cells

Expression of CCN1/Cyr61, a member of the CCN family of matricellular proteins, can be induced by growth factors in cancer cells. CCN1 participates in cell migration and other regulatory processes in various cancers. However, the role of CCN1 in prostate cancer remains poorly understood. In previous work we observed that lysophosphatidic acid (LPA), a bioactive lipid, stimulates proliferation and migration in prostate cancer cells via the G protein-coupled receptor (GPCR) LPAR1, and also induces CCN1 expression. We also showed that activation of free fatty acid receptor 4 (FFAR4), another GPCR, inhibits LPA-induced proliferation and migration. For the current study, we hypothesized that CCN1 contributes to adhesion and migration of prostate cancer cells. We first confirmed that CCN1 protein levels were increased by LPA after 2-5 hours in PC-3 human prostate cancer cells. This response was inhibited by TUG-891, an FFA4 agonist. When serum-starved PC-3 cells were treated with LPA in an extended time course from 2 minutes to 24 hours, Erk, Akt, and FAK were initially activated within 30 minutes of LPA addition, as detected by immunoblotting for the phosphorylated kinases. However, all three kinases exhibited a later phase of activation after ~6 hours. Thus, CCN1 induction is downstream of early signals initiated by LPAR1, but potentially upstream of later events. For adhesion assays, serum-starved PC-3 cells were incubated with and without 10 μM LPA ± 1 μM TUG-891. Enhanced adhesion was prominent 1 hour after LPA addition, and was sustained for at least 8 hours. For migration assays, serum-starved cells were incubated with the same agents in modified Boyden chambers. Enhanced cell migration was observed by 2 hours after LPA addition, and continued for at least 24 hours. LPA-induced adhesion and migration were blocked by TUG-891. In other experiments, extracellular matrix was subjected to immunoblotting and to immunofluorescence microscopy for CCN1. In the immunoblotting experiments, CCN1 protein was increased in the extracted extracellular matrix 2-5 hours after LPA addition. In the immunohistochemistry experiments, CCN1 was detected in the extracellular space of PC-3 cells treated with LPA for 0-5 hours. In conclusion, the results suggest a role for LPA-induced CCN1 in adhesion and migration in prostate cancer cells, making CCN1 a potential therapeutic target. In addition, the results further indicate that FFAR activation is a strategy to suppress both short- and long-term LPA responses.

Abstract A18: Ccn1 expression by fibroblasts is required for melanoma metastasis

Abstract Metastatic melanoma is highly fatal. Within the tumor microenvironment, the role of cancer-associated fibroblasts (CAFs) in melanoma metastasis and progression is relatively understudied. Matricellular proteins of the CCN family are emerging targets for cancer therapy. Anti-CCN2 (CTGF) strategies are under clinical development; however, the role of CCN1 (cyr61) in cancers is unclear. Herein, we use bioinformatic analyses to report that the CCN1 is overexpressed, in a fashion independent of BRAF mutational status, in melanoma. In human melanoma patients, CCN1 expression negatively correlates with overall survival, disease-free, and metastasis-free survival (p<0.03). CCN1 expression positively correlates with expression of stroma and neovascularization markers. To assess the role of CAFs in melanoma progression, we used C57BL/6 mice expressing a tamoxifen-dependent cre recombinase expressed under the control of a fibroblast-specific promoter/enhancer (COL1A2) to delete CCN1 postnatally in fibroblasts. Mice deleted or not for CCN1 in fibroblasts were injected subcutaneously with B16-F10 melanoma cells. Loss of CCN1 in CAFs did not result in reduced CAF activation, as detected by staining with anti-α-smooth muscle actin antibodies, but resulted in reduced extracellular matrix surrounding tumors, as detected by trichrome stain, and reduced tumor-induced neovascularization, as detected by staining with anti-CD31 antibodies. CCN1-deficient skin showed reduced expression of mRNAs encoding collagen crosslinking enzymes (PLOD2 and LOX) and impaired formation of collagen fibers, as determined by electron microscopy. Tumor growth was not affected by loss of CCN1 from tumor stroma; however, micrometastasis to the lung was severely impaired (p<0.001). Our results provide new insights into the crosstalk among different cell types in the tumor microenvironment and confirm the essential role of CAFs in metastasis and tumor neovascularization. Our data are consistent with the hypothesis that CAFs are essential for melanoma metastasis and that CCN1 is a therapeutic target for melanoma. Citation Format: James Hutchenreuther, Katherine Quensel, Krista Vincent, Lynne-Marie Posrovit, Andrew Leask. Ccn1 expression by fibroblasts is required for melanoma metastasis [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr A18.

CCN1 promotes hepatic steatosis and inflammation in non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is characterized by increased uptake and accumulation of lipids in hepatocytes. Simple steatosis may progress to non-alcoholic steatohepatitis (NASH) with inflammation, hepatocellular injury and fibrosis. CCN1 is an important matrix protein that regulates cell death and promotes immune cell adhesion and may potentially control this process. The role of CCN1 in NASH remains unclear. We investigated the role of CCN1 in the pathogenesis of steatohepatitis. CCN1 upregulation was found to be closely related with steatosis in patients with NASH, obese mice and a FFA-treated hepatocyte model. Controlling the expression of CCN1 in murine NASH models demonstrated that CCN1 increased the severity of steatosis and inflammation. From the sequence results, we found that fatty acid metabolism genes were primarily involved in the MCD mice overexpressing CCN1 compared to the control. Then, the expression of fatty acid metabolism genes was determined using a custom-designed pathway-focused qPCR-based gene expression array. Expression analysis showed that CCN1 overexpression significantly upregulated the expression of fatty acid metabolism-associated genes. In vitro analysis revealed that CCN1 increased the intracellular TG content, the pro-inflammatory cytokines and the expression level of apoptosis-associated proteins in a steatosis model using murine primary hepatocytes. We identified CCN1 as an important positive regulator in NASH.

Recombinant CCN1 prevents hyperoxia-induced lung injury in neonatal rats.

BackgroundCystein-rich protein 61 (Cyr61/CCN1) is a member of the CCN family of matricellular proteins that has an important role in tissue development and remodeling. However, the role of CCN1 in the pathogenesis of bronchopulmonary dysplasia (BPD) is unknown. Accordingly, we have investigated the effects of CCN1 on a hyperoxia-induced lung injury model in neonatal rats.MethodsIn experiment 1, newborn rats were randomized to room air (RA) or 85% oxygen (O2) for 7 or 14 days, and we assessed the expression of CCN1. In experiment 2, rat pups were exposed to RA or O2 and received placebo or recombinant CCN1 by daily intraperitoneal injection for 10 days. The effects of CCN1 on hyperoxia-induced lung inflammation, alveolar and vascular development, vascular remodeling, and right ventricular hypertrophy (RVH) were observed.ResultsIn experiment 1, hyperoxia downregulated CCN1 expression. In experiment 2, treatment with recombinant CCN1 significantly decreased macrophage and neutrophil infiltration, reduced inflammasome activation, increased alveolar and vascular development, and reduced vascular remodeling and RVH in the hyperoxic animals.ConclusionThese results demonstrate that hyperoxia-induced lung injury is associated with downregulated basal CCN1 expression, and treatment with CCN1 can largely reverse hyperoxic injury.

Interplay between CCN1 and Wnt5a in endothelial cells and pericytes determines the angiogenic outcome in a model of ischemic retinopathy

CYR61-CTGF-NOV (CCN)1 is a dynamically expressed extracellular matrix (ECM) protein with critical functions in cardiovascular development and tissue repair. Angiogenic endothelial cells (ECs) are a major cellular source of CCN1 which, once secreted, associates with the ECM and the cell surface and tightly controls the bidirectional flow of information between cells and the surrounding matrix. Endothelium-specific CCN1 deletion in mice using a cre/lox strategy induces EC hyperplasia and causes blood vessels to coalesce into large flat hyperplastic sinuses with no distinctive hierarchical organization. This is consistent with the role of CCN1 as a negative feedback regulator of vascular endothelial growth factor (VEGF) receptor activation. In the mouse model of oxygen-induced retinopathy (OIR), pericytes become the predominant CCN1 producing cells. Pericyte-specific deletion of CCN1 significantly decreases pathological retinal neovascularization following OIR. CCN1 induces the expression of the non-canonical Wnt5a in pericyte but not in EC cultures. In turn, exogenous Wnt5a inhibits CCN1 gene expression, induces EC proliferation and increases hypersprouting. Concordantly, treatment of mice with TNP470, a non-canonical Wnt5a inhibitor, reestablishes endothelial expression of CCN1 and significantly decreases pathological neovascular growth in OIR. Our data highlight the significance of CCN1-EC and CCN1-pericyte communication signals in driving physiological and pathological angiogenesis.

CCN1 promotes IL-1\u03b2 production in keratinocytes by activating p38 MAPK signaling in psoriasis

CCN1, an extracellular protein also known as cysteine-rich protein 61 (Cyr61), is a novel pro-inflammatory factor involved in the pathogenesis of rheumatoid arthritis. As an inflammatory disease, psoriasis is characterized by keratinocyte activation-induced epidermal hyperplasia and cytokine-mediated inflammation. We demonstrated in our previous study that CCN1 promoted keratinocyte activation in psoriasis. However, the role of CCN1 in regulating inflammation in psoriasis is still unknown. Here, we showed that CCN1 increased inflammatory cytokine IL-1β production in keratinocytes. Furthermore, endogenous ATP and caspase-1 were required for mature IL-1β production stimulated by CCN1 in keratinocytes. After binding to the receptor of integrin α6β1, CCN1 activated the downstream p38 MAPK signaling pathway, thus inducing the expression of IL-1β. In addition, we inhibited CCN1 function in mouse models of psoriasis, and decreased IL-1β production was observed in vivo. Overall, we showed that CCN1 increased IL-1β production via p38 MAPK signaling, indicating a role for CCN1 protein in regulating inflammation in psoriasis.

Abstract 362: Ccn1 Induction and Its Role in the Neointima Formation-induced by Carotid Artery Ligation in Mice

Aim: Atherosclerosis, characterized by neointima formation, occurs preferentially at areas of disturbed flow. Extracellular matrix protein CCN1 is upregulated at the site of atherosclerotic lesions in humans and in animal models. Our aim was to examine the expression of CCN1-regulated by disturbed flow and its role in neointima formation. Methods and Results: Ccn1+/lacZ mice, in which a lacZ reporter gene was inserted to be driven by Ccn1-promoter, were subjected to complete ligation of the left common carotid artery. Progressive reduction in luminal diameters of the ligated artery were observed using B mode ultrasound compared with the right common carotid artery. Ccn1 expression, assessed by whole-mount X-gal staining, was detected in the intima and the media of carotid arteries 3 days after ligation, and the staining intensified between 1-4 weeks in the neointima after ligation. Specifically, Ccn1 expression was observed in endothelial cells, smooth muscle cells, and macrophages in the neointima. To dissect the role of CCN1 in the development of arterial lesions, knock-in mice carrying the integrin α6β1-binding-deficient mutant allele Ccn1-dm were tested in the carotid artery ligation model. Compared with wild-type mice, Ccn1dm/dm mice displayed significantly less neointima after ligation with improved endothelial function, less endothelial apoptosis, and lower oxidative stress, suggesting that the arterial expression of CCN1 induces endothelial dysfunction through its receptor integrin α6β1. Conclusions: CCN1 is a critical pathophysiological regulator mediating neointima formation induced by disturbed flow-generated after carotid artery ligation. CCN1 and its receptor integrin α6β1 represent potential therapeutic targets for atherosclerosis.

Characterization of long-term in vitro culture-related alterations of human tonsil-derived mesenchymal stem cells: role for CCN1 in replicative senescence-associated increase in osteogenic differentiation.

Although mesenchymal stem cells (MSC) isolated from bone marrow and adipose tissues are known to be subjected to in vitro culture-related alterations in their stem cell properties, such data have not been reported in human tonsil-derived MSC (T-MSC). Here, we investigated the culture-related changes of phenotypes, the senescence, and the differentiation potential of T-MSC. T-MSC were serially passaged by a standard protocol, and their characteristics were assessed, including MSC-specific surface antigen profiles, the senescence, and the differentiation potentials into adipocytes, chondrocytes and osteocytes. Up to at least passage 15, we found no alterations in either MSC-specific surface marker, CD14, CD34, CD45, CD73 and CD90, or the mRNA expression of embryonic stem cell gene markers, Nanog, Oct4-A and Sox-2. However, the expression of CD146, recently identified another MSC marker, dramatically decreased with increasing passages from ~23% at passage 3 to ~1% at passage 15. The average doubling time increased significantly from ~38h at passage 10 to ~46h at passage 15. From passage 10, the cell size increased slightly and SA-β-gal staining was evident. Both Alizarin Red S staining and osteocalcin expression showed that the osteogenic differentiation potential increased up to passage 10 and decreased thereafter. However, the adipogenic and chondrogenic differentiation potential decreased passage-dependently from the start, as evidenced by staining of Oil Red O and Alcian Blue, respectively. Consistent with a passage-dependent osteogenic differentiation, the expression of CCN1, an angiogenic protein known to be related to both senescence and osteogenesis, also increased up to passage 10. Furthermore, ectopic expression of small interfering RNA against CCN1 at passage 10 significantly reversed Alizarin Red S staining and osteocalcin expression. Altogether, our study demonstrates the characterization of long-term in vitro cultured T-MSC and that CCN1 may be involved in mediating a passage-dependent increase in osteogenic potential of T-MSC.

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

BackgroundCCN1 plays distinct roles in various tumor types, but little is known regarding the role of CCN1 in leukemia.MethodsWe 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.ResultsU937 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.ConclusionsThe 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.

Interaction of CCN1 with αvβ3 integrin induces P-glycoprotein and confers vinblastine resistance in renal cell carcinoma cells

Renal cell carcinoma (RCC) ranks among the most chemoresistant tumors, and P-glycoprotein (P-gp) predominates multidrug resistance mechanisms by reducing the accumulation of intracellular chemotherapy drugs such as vinblastine (VBL), which is considered the most effective chemotherapeutic agent for this neoplasia. Unfortunately, the mechanism by which the expression of P-gp is regulated and the ways to inhibit the function of P-gp are poorly understood. Our study was carried out to determine the possible role of CCN1 in P-pg-mediated drug resistance on the basis of the validated function of CCN1, an extracellular matrix protein, in promoting chemoresistance. As expected, CCN1 was overexpressed in VBL-resistant cell lines (ACHN/VBL, A498/VBL, Caki-1/VBL, and Caki-2/VBL) as measured by enzyme-linked immunosorbent assay. We then transfected non-VBL-resistant cell lines with Ad-CCN1 and observed that the IC50 of VBL increased by about 3-5 times. Furthermore, both CCN1 antibody neutralization and αvβ3 integrin antibody blockade decreased the IC50 of VBL, which showed that CCN1 and αvβ3 are associated with resistance to VBL in RCC. Simultaneously, the enhanced expression of CCN1 triggered the intracellular PI3K/Akt pathway by binding αvβ3 integrin, as shown by western blot. P-gp expression was augmented in response to activation of the PI3K/Akt pathway, which could be modified by PI3K inhibitor LY294002 or multidrug resistance siRNA transfection. Therefore, targeted restraint of CCN1 or αvβ3 integrin in combination with the administration of VBL may be beneficial in the treatment of primary and metastatic RCC.

Abstract 060: CCN1/a 6 β 1 Mediates Myocardial Injuries Induced by Work Overload or by Doxorubicin in Mice

Introduction: Matricellular protein CCN1 is expressed in myocardial infarction, pressure overload, and ischemia in mice, and in patients with a failing heart. Despite its well-documented angiogenic activities, CCN1 promotes fibroblast apoptosis in some contexts. The role of CCN1 in an injured heart was not clear. We assessed the hypothesis that CCN1 plays a detrimental role and mediates cardiac injury through its proapoptotic activities. Methods and Results: To test the role of CCN1 in cardiac injury, we employed two different myocardial injury models in mice, including a work-overload-induced injury created by isoproterenol treatment (ISO; 100 mg/kg/day; s.c. for 5 days; n= 6 for each group) and an injury induced by the cardiotoxicity of doxorubicin (DOX, single dose of 15 mg/kg; i.p. sacrificed after 14 days). Ccn1 expression was induced in the damaged myocardium in both injury models. A line of knock-in mice carrying an apoptosis-defective Ccn1 mutant allele, Ccn1-dm , which has disrupted integrin α 6 β 1 binding sites, were tested in the ISO- or DOX -induced cardiac injury. Myocardial damage was seen in tissues from wile-type (WT) hearts after receiving ISO. Ccn1 dm/dm (DM) mice possessed remarkable resistance against ISO or DOX treatments and exhibited no tissue damage or fibrosis compared to WT mice after H&E or Masson’s trichrome stainings. DM mice were resistant to both ISO- and DOX-induced cardiac cell apoptosis, indicating that CCN1 is critically mediating cardiomyocyte apoptotic death in cardiac injury. Moreover, we found that death factor Fas ligand (FasL) and its receptor Fas were upregulated in WT mice receiving ISO or DOX treatments by immunohistochemical staining, compared with the PBS-control. 8-OHdG-positive, a marker for oxidative stress, cardiomyocytes were increased by ISO or DOX treatments as well. In contrast, the expression of Fas/FasL, and the 8-OHdG-positive cardiomyocytes in the myocardium of DM mice were not changed by ISO or DOX. Conclusions: We identify CCN1 as a novel pathophysiological regulator of cardiomyocyte apoptosis in cardiac injury. Blocking apoptotic function of CCN1 effectively prevents myocardial injury in mice. CCN1 and its receptor α 6 β 1 represent promising future therapeutic targets in cardiac injury.

Extracellular matrix associated protein CCN1 regulates shedding of endothelial ICAM1

The extracellular matrix (ECM) provides essential contextual cues for appropriate cellular behavior. CCN1, an ECM associated protein, signals through integrins and heparan sulfate proteoglycans (HSPGs) to mediate multiple cellular responses including proliferation, differentiation, adhesion, migration, and apoptosis. Gene array analysis has identified CCN1 as one of the most highly upregulated genes in a number of TNFα‐mediated inflammatory disorders, including asthma, hyperoxia‐ and ventilator‐induced lung injury, and rheumatoid arthritis. Cytokines such as TNFα upregulate intercellular adhesion molecule 1 (ICAM1) expression in endothelial cells and stimulate shedding of soluble ICAM1. We demonstrate that in endothelial cells in culture, CCN1 inhibits TNFα‐stimulated increases in ICAM1 protein and this inhibition is transcription‐independent. Interestingly, we found that CCN1 promotes shedding of ICAM1 from TNFα‐stimulated endothelial cells via the action of a metalloproteinase. Further, we show that CCN1 acts through αV integrins but not HSPGs to regulate ICAM1 shedding. Together, these findings establish a novel role for CCN1 in regulating ICAM1, and identify CCN1 as a potential therapeutic target in inflammatory disorders. Supported by American Heart Association and NIEHS ES7026.