CCN5, a novel transcriptional repressor of the transforming growth factor β signaling pathway

The matricellular protein CCN5 prevents anti-VEGF drug-induced epithelial-mesenchymal transition of retinal pigment epithelium

Age-related macular degeneration (AMD) is one of the major causes of blindness in the elderly worldwide. Anti-vascular endothelial growth factor (VEGF) drugs have been widely used to treat the neovascular type of AMD (nAMD). However, VEGF acts not only as a pro-angiogenic factor but also as an anti-apoptotic factor in the eyes. In this study, we found that anti-VEGF drugs, including bevacizumab (Bev), ranibizumab (Ran), and aflibercept (Afl), induced epithelial-mesenchymal transition (EMT) in ARPE-19 cells in vitro, accompanied by the induction of CCN2, a potent pro-fibrotic factor. Similarly, intravitreal injection of Afl into mouse eyes resulted in EMT in the retinal pigmented epithelium (RPE). Co-treatment with CCN5, an anti-fibrotic factor that down-regulates CCN2 expression, significantly attenuated the adverse effects of the anti-VEGF drugs both in vitro and in vivo. Inhibition of the VEGF signaling pathway with antagonists of VEGF receptors, SU5416 and ZM323881, induced EMT and up-regulated CCN2 in ARPE-19 cells. Additionally, knock-down of CCN2 with siRNA abolished the adverse effects of the anti-VEGF drugs in ARPE-19 cells. Collectively, these results suggest that anti-VEGF drugs induce EMT in RPE through the induction of CCN2 and that co-treatment with CCN5 attenuates the adverse effects of anti-VEGF drugs in mouse eyes.

Modified mRNA-Mediated CCN5 Gene Transfer Ameliorates Cardiac Dysfunction and Fibrosis without Adverse Structural Remodeling

Modified mRNAs (modRNAs) are an emerging delivery method for gene therapy. The success of modRNA-based COVID-19 vaccines has demonstrated that modRNA is a safe and effective therapeutic tool. Moreover, modRNA has the potential to treat various human diseases, including cardiac dysfunction. Acute myocardial infarction (MI) is a major cardiac disorder that currently lacks curative treatment options, and MI is commonly accompanied by fibrosis and impaired cardiac function. Our group previously demonstrated that the matricellular protein CCN5 inhibits cardiac fibrosis (CF) and mitigates cardiac dysfunction. However, it remains unclear whether early intervention of CF under stress conditions is beneficial or more detrimental due to potential adverse effects such as left ventricular (LV) rupture. We hypothesized that CCN5 would alleviate the adverse effects of myocardial infarction (MI) through its anti-fibrotic properties under stress conditions. To induce the rapid expression of CCN5, ModRNA-CCN5 was synthesized and administrated directly into the myocardium in a mouse MI model. To evaluate CCN5 activity, we established two independent experimental schemes: (1) preventive intervention and (2) therapeutic intervention. Functional analyses, including echocardiography and magnetic resonance imaging (MRI), along with molecular assays, demonstrated that modRNA-mediated CCN5 gene transfer significantly attenuated cardiac fibrosis and improved cardiac function in both preventive and therapeutic models, without causing left ventricular rupture or any adverse cardiac remodeling. In conclusion, early intervention in CF by ModRNA-CCN5 gene transfer is an efficient and safe therapeutic modality for treating MI-induced heart failure.

Evolutionary dynamics of glucose-deprived cancer cells: insights from experimentally informed mathematical modelling

Glucose is a primary energy source for cancer cells. Several lines of evidence support the idea that monocarboxylate transporters, such as MCT1, elicit metabolic reprogramming of cancer cells in glucose-poor environments, allowing them to re-use lactate, a by-product of glucose metabolism, as an alternative energy source with serious consequences for disease progression. We employ a synergistic experimental and mathematical modelling approach to explore the evolutionary processes at the root of cancer cell adaptation to glucose deprivation, with particular focus on the mechanisms underlying the increase in MCT1 expression observed in glucose-deprived aggressive cancer cells. Data from in vitro experiments on breast cancer cells are used to inform and calibrate a mathematical model that comprises a partial integro-differential equation for the dynamics of a population of cancer cells structured by the level of MCT1 expression. Analytical and numerical results of this model suggest that environment-induced changes in MCT1 expression mediated by lactate-associated signalling pathways enable a prompt adaptive response of glucose-deprived cancer cells, while fluctuations in MCT1 expression due to epigenetic changes create the substrate for environmental selection to act upon, speeding up the selective sweep underlying cancer cell adaptation to glucose deprivation, and may constitute a long-term bet-hedging mechanism.

Expression and biological function of the cellular communication network factor 5 (CCN5) in primary liver cells

The cellular (centralized) communication network (CCN) factor protein family contains six small secreted cysteine-rich proteins sharing high structural similarity. These matricellular proteins have vital biological functions in cell adhesion, migration, cell cycle progression, and control of production and degradation of extracellular matrix. However, in liver the biological functions of CCN proteins become most visible during hepatic injury, disease, and remodeling. In particular, most of the hepatic functions of CCN proteins were derived from CCN2/CTGF, which becomes highly expressed in damaged hepatocytes and acts as a profibrogenic molecule. On the contrary, CCN1/CYR61 seems to have opposite effects, while the biological activity during hepatic fibrosis is somewhat controversially discussed for other CCN family members. In the present study, we analyzed the expression of CCN5/WISP2 in cultures of different types of primary liver cells and in an experimental model of hepatic fibrosis. We found that CCN5 is expressed in hepatic stellate cells, myofibroblasts and portal myofibroblasts, while CCN5 expression is virtually absent in hepatocytes. During hepatic fibrogenesis, CCN5 is significantly upregulated. Overexpression of CCN5 in portal myofibroblasts reduced expression of transforming growth factor-β receptor I (ALK5) and concomitant Smad2 activation, whereas JunB expression is upregulated. Moreover, elevated expression of CCN5 induces endoplasmic reticulum stress, unfolded protein response and apoptosis in portal myofibroblasts. We suggest that upregulated expression of CCN5 might be an intrinsic control mechanism that counteracts overshooting fibrotic responses in profibrogenic liver cells.

The role of CCNs in controlling cellular communication in the tumor microenvironment

The Cellular communication network (CCN) family of growth regulatory factors comprises six secreted matricellular proteins that promote signal transduction through cell-cell or cell-matrix interaction. The diversity of functionality between each protein is specific to the many aspects of healthy and cancer biology. For example, CCN family proteins modulate cell adhesion, proliferation, migration, invasiveness, apoptosis, and survival. In addition, the expression of each protein regulates many biological and pathobiological processes within its microenvironment to regulate angiogenesis, inflammatory response, chondrogenesis, fibrosis, and mitochondrial integrity. The collective range of CCN operation remains fully comprehended; however, understanding each protein's microenvironment may draw more conclusions about the abundance of interactions and signaling cascades occurring within such issues. This review observes and distinguishes the various roles a CCN protein may execute within distinct tumor microenvironments and the biological associations among them. Finally. We also review how CCN-family proteins can be used in nano-based therapeutic implications.

PARP Inhibitor Inhibits the Vasculogenic Mimicry through a NF-κB-PTX3 Axis Signaling in Breast Cancer Cells

Poly (ADP-ribose) polymerase inhibitors (PARPi) are targeted therapies that inhibit PARP proteins which are involved in a variety of cell functions. PARPi may act as modulators of angiogenesis; however, the relationship between PARPi and the vasculogenic mimicry (VM) in breast cancer remains unclear. To determine whether PARPi regulate the vascular channel formation, we assessed whether the treatment with olaparib, talazoparib and veliparib inhibits the vascular channel formation by breast cancer cell lines. Here, we found that PARPi act as potent inhibitors of the VM formation in triple negative breast cancer cells, independently of the BRCA status. Mechanistically, we find that PARPi trigger and inhibit the NF-κB signaling, leading to the inhibition of the VM. We further show that PARPi decrease the expression of the angiogenic factor PTX3. Moreover, PTX3 rescued the PARPi-inhibited VM inhibition. In conclusion, our results indicate that PARPi, by targeting the VM, may provide a new therapeutic approach for triple negative breast cancer.

Estrogen Receptor Beta 1: A Potential Therapeutic Target for Female Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by the absence of estrogen receptor alpha, progesterone receptor, and HER2. These receptors often serve as targets in breast cancer treatment. As a result, TNBCs are difficult to treat and have a high propensity to metastasize to distant organs. For these reasons, TNBCs are responsible for over 50% of all breast cancer mortalities while only accounting for 15% to 20% of breast cancer cases. However, estrogen receptor beta 1 (ERβ1), an isoform of the ESR2 gene, has emerged as a potential therapeutic target in the treatment of TNBCs. Using an in vivo xenograft preclinical mouse model with human TNBC, we found that expression of ERβ1 significantly reduced both primary tumor growth and metastasis. Moreover, TNBCs with elevated levels of ERβ1 showed reduction in epithelial to mesenchymal transition markers and breast cancer stem cell markers, and increases in the expression of genes associated with inhibition of cancer cell invasiveness and metastasis, suggesting possible mechanisms underlying the antitumor activity of ERβ1. Gene expression analysis by quantitative polymerase chain reaction and RNA-seq revealed that treatment with chloroindazole, an ERβ-selective agonist ligand, often enhanced the suppressive activity of ERβ1 in TNBCs in vivo or in TNBC cells in culture, suggesting the potential utility of ERβ1 and ERβ ligand in improving TNBC treatment. The findings enable understanding of the mechanisms by which ERβ1 impedes TNBC growth, invasiveness, and metastasis and consideration of ways by which treatments involving ERβ might improve TNBC patient outcome.

Fibroblast Growth Factors and Cellular Communication Network Factors: Intimate Interplay by the Founding Members in Cartilage

Fibroblast growth factors (FGFs) constitute a large family of signaling molecules that act in an autocrine/paracrine, endocrine, or intracrine manner, whereas the cellular communication network factors (CCN) family is composed of six members that manipulate extracellular signaling networks. FGFs and CCNs are structurally and functionally distinct, except for the common characteristics as matricellular proteins. Both play significant roles in the development of a variety of tissues and organs, including the skeletal system. In vertebrates, most of the skeletal parts are formed and grow through a process designated endochondral ossification, in which chondrocytes play the central role. The growth plate cartilage is the place where endochondral ossification occurs, and articular cartilage is left to support the locomotive function of joints. Several FGFs, including FGF-2, one of the founding members of this family, and all of the CCNs represented by CCN2, which is required for proper skeletal development, can be found therein. Research over a decade has revealed direct binding of CCN2 to FGFs and FGF receptors (FGFRs), which occasionally affect the biological outcome via FGF signaling. Moreover, a recent study uncovered an integrated regulation of FGF and CCN genes by FGF signaling. In this review, after a brief introduction of these two families, molecular and genetic interactions between CCN and FGF family members in cartilage, and their biological effects, are summarized. The molecular interplay represents the mutual involvement of the other in their molecular functions, leading to collaboration between CCN2 and FGFs during skeletal development.

The matricellular protein CCN5 induces apoptosis in myofibroblasts through SMAD7-mediated inhibition of NFκB

We previously showed that the matricellular protein CCN5 reverses established cardiac fibrosis (CF) through inducing apoptosis in myofibroblasts (MyoFBs) but not in cardiomyocytes or fibroblasts (FBs). In this study, we set out to elucidate the molecular mechanisms underlying CCN5-mediated selective apoptosis of MyoFBs. We first observed that the apoptotic protein p53 and the anti-apoptotic protein NFκB are simultaneously induced in MyoFBs. When the expression level of p53 was suppressed using a siRNA, CCN5 did not induce apoptosis in MyoFBs. By contrast, when NFκB signaling was inhibited using IKK VII, an IκB inhibitor, MyoFBs underwent apoptosis even in the absence of CCN5. SMAD7 is one of the downstream targets of CCN5 and it was previously shown to potentiate apoptosis in epithelial cells through inhibition of NFκB. In accordance with these reports, when the expression of SMAD7 was suppressed using a siRNA, NFκB signaling was enhanced, and CCN5 did not induce apoptosis. Lastly, we used a luciferase reporter construct to show that CCN5 positively regulated SMAD7 expression at the transcriptional level. Collectively, our data suggest that a delicate balance between the two mutually antagonistic proteins p53 and NFκB is maintained for MyoFBs to survive, and CCN5 tips the balance in favor of the apoptotic protein p53. This study provides insight into the anti-fibrotic activity of CCN5 during the regression of CF.

Suppression of choroidal neovascularization and epithelial-mesenchymal transition in retinal pigmented epithelium by adeno-associated virus-mediated overexpression of CCN5 in mice

Choroidal neovascularization (CNV) is a defining characteristic feature of neovascular age-related macular degeneration (nAMD) that frequently results in irreversible vision loss. The current strategies for the treatment of nAMD are mainly based on neutralizing vascular endothelial growth factor (VEGF). However, anti-VEGF therapies are often associated with subretinal fibrosis that eventually leads to damages in macula. In this study, we tested whether an anti-fibrotic and anti-angiogenic protein CCN5 can potentially be an effective and safe therapeutic modality in a mouse model of CNV. Laser photocoagulation was utilized to induce CNV, which was followed by intravitreal injection of recombinant adeno-associated virus serotype 2 encoding CCN5 (rAAV2-CCN5). Our data demonstrated that rAAV2-CCN5, but not a control viral vector, rAAV2-VLP, prominently attenuated both CNV lesions and angiogenesis. Aflibercept, which was utilized as a positive control, exhibited similar effects on CNV lesions and angiogenesis in our experimental settings. Upon laser photocoagulation, retinal pigmented epithelium (RPE) cells underwent significant morphological changes including cellular enlargement and loss of hexagonality. rAAV2-CCN5 significantly normalized these morphological defects. Laser photocoagulation also led to fibrotic deformation in RPE cells through inducing epithelial-mesenchymal transition (EMT), which was completely blocked by rAAV2-CCN5. In a striking contrast, aflibercept as well as rAAV2-VLP failed to exhibit any effects on EMT. Collectively, this study suggest that CCN5 might provide a potential novel strategy for the treatment of nAMD with a capability to inhibit CNV and fibrosis simaultaneously.

Matricellular Protein CCN5 Gene Transfer Ameliorates Cardiac and Skeletal Dysfunction in mdx/utrn (±) Haploinsufficient Mice by Reducing Fibrosis and Upregulating Utrophin Expression

Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration due to dystrophin gene mutations. Patients with DMD initially experience muscle weakness in their limbs during adolescence. With age, patients develop fatal respiratory and cardiac dysfunctions. During the later stages of the disease, severe cardiac fibrosis occurs, compromising cardiac function. Previously, our research showed that the matricellular protein CCN5 has antifibrotic properties. Therefore, we hypothesized that CCN5 gene transfer would ameliorate cardiac fibrosis and thus improve cardiac function in DMD-induced cardiomyopathy. We utilized mdx/utrn (±) haploinsufficient mice that recapitulated the DMD-disease phenotypes and used an adeno-associated virus serotype-9 viral vector for CCN5 gene transfer. We evaluated the onset of cardiac dysfunction using echocardiography and determined the experimental starting point in 13-month-old mice. Two months after CCN5 gene transfer, cardiac function was significantly enhanced, and cardiac fibrosis was ameliorated. Additionally, running performance was improved in CCN5 gene-transfected mice. Furthermore, in silico gene profiling analysis identified utrophin as a novel transcriptional target of CCN5. This was supplemented by a utrophin promoter assay and RNA-seq analysis, which confirmed that CCN5 was directly associated with utrophin expression. Our results showed that CCN5 may be a promising therapeutic molecule for DMD-induced cardiac and skeletal dysfunction.

The TSP-1 domain of the matricellular protein CCN5 is essential for its nuclear localization and anti-fibrotic function

The matricellular protein CCN5 exerts anti-fibrotic activity in hearts partly by inducing reverse trans-differentiation of myofibroblasts (MyoFBs) to fibroblasts (FBs). CCN5 consists of three structural domains: an insulin-like growth factor binding protein (IGFBP), a von Willebrand factor type C (VWC), and a thrombospondin type 1 (TSP-1). In this study, we set out to elucidate the roles of these domains in the context of the reverse trans-differentiation of MyoFBs to FBs. First, human cardiac FBs were trans-differentiated to MyoFBs by treatment with TGF-β; this was then reversed by treatment with recombinant human CCN5 protein or various recombinant proteins comprising individual or paired CCN5 domains. Subcellular localization of these recombinant proteins was analyzed by immunocytochemistry, cellular fractionation, and western blotting. Anti-fibrotic activity was also evaluated by examining expression of MyoFB-specific markers, α-SMA and fibronectin. Our data show that CCN5 is taken up by FBs and MyoFBs mainly via clathrin-mediated endocytosis, which is essential for the function of CCN5 during the reverse trans-differentiation of MyoFBs. Furthermore, we showed that the TSP-1 domain is essential and sufficient for endocytosis and nuclear localization of CCN5. However, the TSP-1 domain alone is not sufficient for the anti-fibrotic function of CCN5; either the IGFBP or VWC domain is needed in addition to the TSP-1 domain.

WISP2/CCN5 Suppresses Vasculogenic Mimicry through Inhibition of YAP/TAZ Signaling in Breast Cancer Cells

Simple Summary

Breast cancer is the most frequent malignancy in women worldwide. Advanced breast cancer with distant organ metastases is considered incurable with currently available therapies. The vasculogenic mimicry (VM) process is associated with an invasive and metastatic cancer phenotype and a poor prognosis for human breast cancer patients. Our aim was to study the effect of WISP2, a matricellular protein, on VM. We found that WISP2 inhibits VM through inhibition of CYR61 protein expression and YAP-TAZ signaling. Our finding may open promising candidates for blocking VM in breast cancer.

Abstract

Vasculogenic mimicry (VM) formed by aggressive tumor cells to create vascular networks connected with the endothelial cells, plays an important role in breast cancer progression. WISP2 has been considered as a tumor suppressor protein; however, the relationship between WISP2 and VM formation remains unclear. We used the in vitro tube formation assay and in vivo immunohistochemical analysis in a mouse model, and human breast tumors were used to evaluate the effect of WISP2 on VM formation. Here we report that WISP2 acts as a potent inhibitor of VM formation in breast cancer. Enforced expression of WISP2 decreased network formation while knockdown of WISP2 increased VM. Mechanistically, WISP2 increased retention of oncogenic activators YAP/TAZ in cytoplasm, leading to decreased expression of the angiogenic factor CYR61. Studies using an in vivo mouse model and human breast tumors confirmed the in vitro cell lines data. In conclusion, our results indicate that WISP2 may play a critical role in VM and highlight the critical role of WISP2 as a tumor suppressor.

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 α_vβ₃ 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 α_vβ₃ or α₆β₁. First, we took advantage of site-specific mutagenesis abolishing the CCN1 receptor-binding sites to α_vβ₃ 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 α_vβ₃ 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 α_vβ₃, drives an endocrine resistance phenotype that involves a direct binding of CCN1 to ERα to regulate its transcriptional activity in ER+ BC cells.

Nuclear respiratory factor-1 negatively regulates TGF-β1 and attenuates pulmonary fibrosis

The preclinical model of bleomycin-induced lung fibrosis is useful to study mechanisms related to human pulmonary fibrosis. Using BLM in mice, we find low HO-1 expression. Although a unique Rhenium-CO-releasing molecule (ReCORM) up-regulates HO-1, NRF-1, CCN5, and SMAD7, it reduces TGFβ1, TGFβr1, collagen, α-SMA, and phosphorylated Smad2/3 levels in mouse lung and in human lung fibroblasts. ChIP assay studies confirm NRF-1 binding to the promoters of TGFβ1 repressors CCN5 and Smad7. ReCORM did not blunt lung fibrosis in Hmox1-deficient alveolar type 2 cell knockout mice, suggesting this gene participates in lung protection. In human lung fibroblasts, TGFβ1-dependent production of α-SMA is abolished by ReCORM or by NRF-1 gene transfection. We demonstrate effective HO-1/NRF-1 signaling in lung AT2 cells protects against BLM induced lung injury and fibrosis by maintaining mitochondrial health, function, and suppressing the TGFβ1 pathway. Thus, protection of AT2 cell mitochondrial integrity via HO-1/NRF-1 presents an innovative therapeutic target.

Identification and analysis of novel endometriosis biomarkers via integrative bioinformatics

Endometriosis is a gynecological disease prevalent in women of reproductive age, and it is characterized by the ectopic presence and growth of the eutopic endometrium. The pathophysiology and diagnostic biomarkers of endometriosis have not yet been comprehensively determined. To discover molecular markers and pathways underlying the pathogenesis of endometriosis, we identified differentially expressed genes (DEGs) in three Gene Expression Omnibus microarray datasets (GSE11691, GSE23339, and GSE7305) and performed gene set enrichment analysis (GSEA) and protein-protein interaction (PPI) network analyses. We also validated the identified genes via immunohistochemical analysis of tissues obtained from patients with endometriosis or healthy volunteers. A total of 118 DEGs (79 upregulated and 39 downregulated) were detected in each dataset with a lower (fold change) FC cutoff (log2|FC| > 1), and 17 DEGs (11 upregulated and six downregulated) with a higher FC cutoff (log2|FC| > 2). KEGG and GO functional analyses revealed enrichment of signaling pathways associated with inflammation, complement activation, cell adhesion, and extracellular matrix in endometriotic tissues. Upregulation of seven genes (C7, CFH, FZD7, LY96, PDLIM3, PTGIS, and WISP2) out of 17 was validated via comparison with external gene sets, and protein expression of four genes (LY96, PDLIM3, PTGIS, and WISP2) was further analyzed by immunohistochemistry and western blot analysis. Based on these results, we suggest that TLR4/NF-κB and Wnt/frizzled signaling pathways, as well as estrogen receptors, regulate the progression of endometriosis. These pathways may be therapeutic and diagnostic targets for endometriosis.

Potential Role of CCN Proteins in Breast Cancer: Therapeutic Advances and Perspectives

CCNs are a specific type of matricellular protein, which are essential signaling molecules, and play multiple roles in multicellular eukaryotes. This family of proteins consists of six separate members, which exist only in vertebrates. The architecture of CCN proteins is multi-modular comprising four distinct modules. CCN Proteins achieve their primary functional activities by binding with several integrin7 receptors. The CCN family has been linked to cell adhesion, chemotaxis and migration, mitogenesis, cell survival, angiogenesis, differentiation, tumorigenesis, chondrogenesis, and wound healing, among other biological interactions. Breast cancer is the most commonly diagnosed cancer worldwide and CCN regulated breast cancer stands at the top. A favorable or unfavorable association between various CCNs has been reported in patients with breast carcinomas. The pro-tumorigenic CCN1, CCN2, CCN3, and CCN4 may lead to human breast cancer, although the anti-tumorigenic actions of CCN5 and CCN6 are also present. Several studies have been conducted on CCN proteins and cancer in recent years. CCN1 and CCN3 have been shown to exhibit a dual nature of tumor inhibition and tumor suppression to some extent in quiet recent time. Pharmacological advances in treating breast cancer by targeting CCN proteins are also reported. In our study, we intend to provide an overview of these research works while keeping breast cancer in focus. This information may facilitate early diagnosis, early prognosis and the development of new therapeutic strategies.

Matricellular protein WISP2 is an endogenous inhibitor of collagen linearization and cancer metastasis

Collagen remodeling contributes to many physiological and pathological processes. In primary tumors, the linearization of collagen fibers promotes cancer cell invasion and metastasis and is indicative of poor prognosis. However, it remains unknown whether there are endogenous inhibitors of collagen linearization that could be exploited therapeutically. Here, we show that collagen linearization is controlled by two secreted matricellular proteins with antagonistic functions. Specifically, WISP1 was secreted by cancer cells, bound to type I collagen (Col I), and linearized Col I via its cysteine-rich C-terminal (CT) domain. In contrast, WISP2, which lacks a CT domain, inhibited Col I linearization by preventing WISP1-Col I binding. Analysis of patient data revealed that WISP2 expression is lower in most solid tumors, in comparison to normal tissues. Consequently, genetic or pharmacological restoration of higher WISP2 levels impaired collagen linearization and prevented tumor cell invasion and metastasis in vivo in models of human and murine breast cancer. Thus, this study uncovers WISP2 as the first inhibitor of collagen linearization ever identified and reveals that collagen architecture can be normalized and metastasis inhibited by therapeutically restoring a high WISP2:WISP1 ratio.

Omics Profiling of S2P Mutant Fibroblasts as a Mean to Unravel the Pathomechanism and Molecular Signatures of X-Linked MBTPS2 Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by low bone density, bone fragility and recurrent fractures. The characterization of its heterogeneous genetic basis has allowed the identification of novel players in bone development. In 2016, we described the first X-linked recessive form of OI caused by hemizygous MBTPS2 missense variants resulting in moderate to severe phenotypes. MBTPS2 encodes site-2 protease (S2P), which activates transcription factors involved in bone (OASIS) and cartilage development (BBF2H7), ER stress response (ATF6) and lipid metabolism (SREBP) via regulated intramembrane proteolysis. In times of ER stress or sterol deficiency, the aforementioned transcription factors are sequentially cleaved by site-1 protease (S1P) and S2P. Their N-terminal fragments shuttle to the nucleus to activate gene transcription. Intriguingly, missense mutations at other positions of MBTPS2 cause the dermatological spectrum condition Ichthyosis Follicularis, Atrichia and Photophobia (IFAP) and Keratosis Follicularis Spinulosa Decalvans (KFSD) without clinical overlap with OI despite the proximity of some of the pathogenic variants. To understand how single amino acid substitutions in S2P can lead to non-overlapping phenotypes, we aimed to compare the molecular features of MBTPS2-OI and MBTPS2-IFAP/KFSD, with the ultimate goal to unravel the pathomechanisms underlying MBTPS2-OI. RNA-sequencing-based transcriptome profiling of primary skin fibroblasts from healthy controls (n = 4), MBTPS2-OI (n = 3), and MBTPS2-IFAP/KFSD (n = 2) patients was performed to identify genes that are differentially expressed in MBTPS2-OI and MBTPS2-IFAP/KFSD individuals compared to controls. We observed that SREBP-dependent genes are more downregulated in OI than in IFAP/KFSD. This is coupled to alterations in the relative abundance of fatty acids in MBTPS2-OI fibroblasts in vitro, while no consistent alterations in the sterol profile were observed. Few OASIS-dependent genes are suppressed in MBTPS2-OI, while BBF2H7- and ATF6-dependent genes are comparable between OI and IFAP/KFSD patients and control fibroblasts. Importantly, we identified genes involved in cartilage physiology that are differentially expressed in MBTPS2-OI but not in MBTPS2-IFAP/KFSD fibroblasts. In conclusion, our data provide clues to how pathogenic MBTPS2 mutations cause skeletal deformities via altered fatty acid metabolism or cartilage development that may affect bone development, mineralization and endochondral ossification.

CCN5 activation by free or encapsulated EGCG is required to render triple-negative breast cancer cell viability and tumor progression

Epigallocatechin-3-gallate (EGCG) has been considered an anticancer agent despite conflicting and discrepant bioavailability views. EGCG impairs the viability and self-renewal capacity of triple-negative breast cancer (TNBC) cells and makes them sensitive to estrogen via activating ER-α. Surprisingly, the mechanism of EGCG's action on TNBC cells remains unclear. CCN5/WISP-2 is a gatekeeper gene that regulates viability, ER-α, and stemness in TNBC and other types of cancers. This study aimed to investigate whether EGCG (free or encapsulated in nanoparticles) interacts with the CCN5 protein by emphasizing its bioavailability and enhancing its anticancer effect. We demonstrate that EGCG activates CCN5 to inhibit in vitro cell viability through apoptosis, the sphere-forming ability via reversing TNBC cells' stemness, and suppressing tumor growth in vivo. Moreover, we found EGCG-loaded nanoparticles to be functionally more active and superior in their tumor-suppressing ability than free-EGCG. Together, these studies identify EGCG (free or encapsulated) as a novel activator of CCN5 in TNBC cells and hold promise as a future therapeutic option for TNBC with upregulated CCN5 expression.

The matricellular protein CCN5 prevents adverse atrial structural and electrical remodelling

Atrial structural remodelling including atrial hypertrophy and fibrosis is a key mediator of atrial fibrillation (AF). We previously demonstrated that the matricellular protein CCN5 elicits anti‐fibrotic and anti‐hypertrophic effects in left ventricles under pressure overload. We here determined the utility of CCN5 in ameliorating adverse atrial remodelling and arrhythmias in a murine model of angiotensin II (AngII) infusion. Advanced atrial structural remodelling was induced by AngII infusion in control mice and mice overexpressing CCN5 either through transgenesis (CCN5 Tg) or AAV9‐mediated gene transfer (AAV9‐CCN5). The mRNA levels of pro‐fibrotic and pro‐inflammatory genes were markedly up‐regulated by AngII infusion, which was significantly normalized by CCN5 overexpression. In vitro studies in isolated atrial fibroblasts demonstrated a marked reduction in AngII‐induced fibroblast trans‐differentiation in CCN5‐treated atria. Moreover, while AngII increased the expression of phosphorylated CaMKII and ryanodine receptor 2 levels in HL‐1 cells, these molecular features of AF were prevented by CCN5. Electrophysiological studies in ex vivo perfused hearts revealed a blunted susceptibility of the AAV9‐CCN5–treated hearts to rapid atrial pacing‐induced arrhythmias and concomitant reversal in AngII‐induced atrial action potential prolongation. These data demonstrate the utility of a gene transfer approach targeting CCN5 for reversal of adverse atrial structural and electrophysiological remodelling.

Genome-wide estrogen receptor-α binding and action in human endometrial stromal cells

OBJECTIVE

To investigate the gene targets of estradiol (E2)-estrogen receptor-α (ESR1) in human endometrial stromal cells.

DESIGN

Basic science.

SETTING

University research center.

PATIENT(S)

Premenopausal women with or without endometriosis.

INTERVENTION(S)

Primary cultures of human endometrial stromal cells from healthy endometrium, with or without small-interfering RNA (siRNA) knockdown of ESR1 expression, were treated with E2 or vehicle control.

MAIN OUTCOME MEASURE(S)

Genome-wide RNA expression by RNA sequencing was compared in endometrial stromal cells with or without siRNA knockdown of ESR1 in the presence or absence of E2. Genome-wide recruitment of ESR1 to chromatin was assessed by chromatin immunoprecipitation sequencing. Gene expression by real-time qualitative polymerase chain reaction of a potential E2-ESR1 target gene was determined in endometrial stromal cells and endometriotic stromal cells.

RESULT(S)

We identified several important pathways that are dependent on E2-ESR1 signaling in endometrial stromal cells, including progesterone signaling, cell-matrix adhesion, and cytoskeleton rearrangement, as well as paracrine signaling by members of the fibroblast growth factor family. We detected a total of 709 ESR1 target sites on chromatin. By integrating data on genome-wide transcriptomic changes and E2-ESR1 binding sites, we identified inositol polyphosphate phosphatase type II (INPP4B) as a candidate E2-mediated suppressor of proliferation in healthy endometrial cells. INPP4B was downregulated in endometriosis-derived stromal cells.

CONCLUSION(S)

E2-ESR1 activates genes involved in human endometrial stromal cell cycle regulation, progesterone response, and production of stromal growth factors. Understanding the direct role of estrogen on the endometrial stroma and identifying downstream targets of E2-ESR1 can inform the development of targeted therapies for endometriosis and diminished endometrial receptivity.

Roles of Interaction between CCN2 and Rab14 in Aggrecan Production by Chondrocytes

To identify proteins that cooperate with cellular communication network factor 2 (CCN2), we carried out GAL4-based yeast two-hybrid screening using a cDNA library derived from the chondrocytic cell line HCS-2/8. Rab14 GTPase (Rab14) polypeptide was selected as a CCN2-interactive protein. The interaction between CCN2 and Rab14 in HCS-2/8 cells was confirmed using the in situ proximity ligation assay. We also found that CCN2 interacted with Rab14 through its IGFBP-like domain among the four domains in CCN2 protein. To detect the colocalization between CCN2 and Rab14 in the cells in detail, CCN2, wild-type Rab14 (Rab14WT), a constitutive active form (Rab14CA), and a dominant negative form (Rab14DN) of Rab14 were overexpressed in monkey kidney-tissue derived COS7 cells. Ectopically overexpressed Rab14 showed a diffuse cytosolic distribution in COS7 cells; however, when Rab14WT was overexpressed with CCN2, the Rab14WT distribution changed to dots that were evenly distributed within the cytosol, and both Rab14 and CCN2 showed clear colocalization. When Rab14CA was overexpressed with CCN2, Rab14CA and CCN2 also showed good localization as dots, but their distribution was more widespread within cytosol. The coexpression of Rab14DN and CCN2 also showed a dotted codistribution but was more concentrated in the perinuclear area. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that the reduction in RAB14 or CCN2 mRNA by their respective siRNA significantly enhanced the expression of ER stress markers, BIP and CHOP mRNA in HCS-2/8 chondrocytic cells, suggesting that ER and Golgi stress were induced by the inhibition of membrane vesicle transfer via the suppression of CCN2 or Rab14. Moreover, to study the effect of the interaction between CCN2 and its interactive protein Rab14 on proteoglycan synthesis, we overexpressed Rab14WT or Rab14CA or Rab14DN in HCS-2/8 cells and found that the overexpression of Rab14DN decreased the extracellular proteoglycan accumulation more than the overexpression of Rab14WT/CA did in the chondrocytic cells. These results suggest that intracellular CCN2 is associated with Rab14 on proteoglycan-containing vesicles during their transport from the Golgi apparatus to endosomes in chondrocytes and that this association may play a role in proteoglycan secretion by chondrocytes.

A chemotaxis-based explanation of spheroid formation in 3D cultures of breast cancer cells

Three-dimensional cultures of cells are gaining popularity as an in vitro improvement over 2D Petri dishes. In many such experiments, cells have been found to organize in aggregates. We present new results of three-dimensional in vitro cultures of breast cancer cells exhibiting patterns. Understanding their formation is of particular interest in the context of cancer since metastases have been shown to be created by cells moving in clusters. In this paper, we propose that the main mechanism which leads to the emergence of patterns is chemotaxis, i.e., oriented movement of cells towards high concentration zones of a signal emitted by the cells themselves. Studying a Keller-Segel PDE system to model chemotactical auto-organization of cells, we prove that it admits Turing unstable solutions under a time-dependent condition. This result is illustrated by two-dimensional simulations of the model showing spheroidal patterns. They are qualitatively compared to the biological results and their variability is discussed both theoretically and numerically.

Antimetastatic Properties of Tea Polyphenols

Metastasis of cells from primary site to distant organs involves a series of sequential steps, and molecules responsible for all these events are understandably considered as potential targets for metastasis management. Tea polyphenols, the secondary metabolites of the tea leaf Camellia sinensis, are increasingly being studied for their antimetastatic properties. In this article, effects of green tea polyphenols (GTP) and black tea polyphenols (BTP) on the molecules and events involved in metastasis are discussed in detail. As tea is a very popular beverage, tea polyphenols are expected to be potential chemopreventive agents that can be taken with normal diet and can be nontoxic due to their natural origin. However, individual variations in metabolic pathways, bioavailability, dose, and toxicity are some important factors that can modify the effectiveness of tea polyphenols within the human system.

The matricellular protein CCN5 inhibits fibrotic deformation of retinal pigment epithelium

Retinal pigment epithelium (RPE) plays an essential role in maintaining retinal function, and its defect is thought to be critically implicated in various ocular disorders. This study demonstrated that the matricellular protein CCN5 was down-regulated in ARPE-19 cells treated with the pro-fibrotic agent transforming growth factor (TGF)-β. A recombinant adenovirus expressing CCN5 (AdCCN5) was used to restore the level of CCN5 in these cells. AdCCN5 prevented TGF-β-induced fibrotic changes, including disruption of tight junctions, up-regulation of mesenchymal marker proteins, and down-regulation of epithelial marker proteins. In addition, AdCCN5 prevented TGF-β-induced functional defects, including increased migratory activity and reduced phagocytic activity. Notably, AdCCN5 reversed morphological and functional defects pre-established by TGF-β prior to viral infection. The CCN5 level was down-regulated in RPE of 18-month-old Ccl2-/- mice, which exhibited retinal defects. Restoration of the CCN5 level via intravitreal injection of a recombinant adeno-associated virus expressing CCN5 (AAV9-CCN5) normalized the altered expression of mesenchymal, epithelial, and functional marker proteins, as assessed by western blotting and immunohistochemistry. Taken together, these data suggest that down-regulation of CCN5 is associated with fibrotic deformation of RPE under pathological conditions and that restoration of the CCN5 level effectively promotes recovery of deformed RPE.

CCN5/WISP2 and metabolic diseases

Obesity and type 2 diabetes increase worldwide at an epidemic rate. It is expected that by the year 2030 around 500 million people will have diabetes; predominantly type 2 diabetes. The CCN family of proteins has become of interest in both metabolic and other common human diseases because of their effects on mesenchymal stem cell (MSCs) proliferation and differentiation as well as being important regulators of fibrosis. We here review current knowledge of the WNT1 inducible signaling pathway protein 2 (CCN5/WISP2). It has been shown to be an important regulator of both these processes through effects on both the canonical WNT and the TGFβ pathways. It is also under normal regulation by the adipogenic commitment factor BMP4, in contrast to conventional canonical WNT ligands, and allows MSCs to undergo normal adipose cell differentiation. CCN5/WISP2 is highly expressed in, and secreted by, MSCs and is an important regulator of MSCs growth. In a transgenic mouse model overexpressing CCN5/WISP2 in the adipose tissue, we have shown that it is secreted and circulating in the blood, the mice develop hypercellular white and brown adipose tissue, have increased lean body mass and enlarged hypercellular hearts. Obese transgenic mice had improved insulin sensitivity. Interestingly, the anti-fibrotic effect of CCN5/WISP2 is protective against heart failure by inhibition of the TGFβ pathway. Understanding how CCN5/WISP2 is regulated and signals is important and may be useful for developing new treatment strategies in obesity and metabolic diseases and it can also be a target in regenerative medicine.

Leptin-induced ER-α-positive breast cancer cell viability and migration is mediated by suppressing CCN5-signaling via activating JAK/AKT/STAT-pathway

Background

In menopausal women, one of the critical risk factors for breast cancer is obesity/adiposity. It is evident from various studies that leptin, a 16 kDa protein hormone overproduced in obese people, plays the critical role in neovascularization and tumorigenesis in breast and other organs. However, the mechanisms by which obesity influences the breast carcinogenesis remained unclear. In this study, by analyzing different estrogen receptor-α (ER-α)-positive and ER-α-negative BC cell lines, we defined the role of CCN5 in the leptin-mediated regulation of growth and invasive capacity.

Methods

We analyzed the effect of leptin on cell viability of ER-α-positive MCF-7 and ZR-75-1 cell lines and ER-α-negative MDA-MB-231 cell line. Additionally, we also determined the effect of leptin on the epithelial-mesenchymal transition (EMT) bio-markers, in vitro invasion and sphere-formation of MCF-7 and ZR-75-1 cell lines. To understand the mechanism, we determined the impact of leptin on CCN5 expression and the functional role of CCN5 in these cells by the treatment of human recombinant CCN5 protein(hrCCN5). Moreover, we also determined the role of JAK-STAT and AKT in the regulation of leptin-induced suppression of CCN5 in BC cells.

Results

Present studies demonstrate that leptin can induce cell viability, EMT, sphere-forming ability and migration of MCF-7 and ZR-75-1 cell lines. Furthermore, these studies found that leptin suppresses the expression of CCN5 at the transcriptional level. Although the CCN5 suppression has no impact on the constitutive proliferation of MCF-7 and ZR-75-1 cells, it is critical for leptin-induced viability and necessary for EMT, induction of in vitro migration and sphere formation, as the hrCCN5 treatment significantly inhibits the leptin-induced viability, EMT, migration and sphere-forming ability of these cells. Mechanistically, CCN5-suppression by leptin is mediated via activating JAK/AKT/STAT-signaling pathways.

Conclusions

These studies suggest that CCN5 serves as a gatekeeper for leptin-dependent growth and progression of luminal-type (ER-positive) BC cells. Leptin may thus need to destroy the CCN5-barrier to promote BC growth and progression via activating JAK/AKT/STAT signaling. Therefore, these observations suggest a therapeutic potency of CCN5 by restoration or treatment in obese-related luminal-type BC growth and progression.

Genome-wide RNA-Sequencing analysis identifies a distinct fibrosis gene signature in the conjunctiva after glaucoma surgery

Fibrosis-related events play a part in most blinding diseases worldwide. However, little is known about the mechanisms driving this complex multifactorial disease. Here we have carried out the first genome-wide RNA-Sequencing study in human conjunctival fibrosis. We isolated 10 primary fibrotic and 7 non-fibrotic conjunctival fibroblast cell lines from patients with and without previous glaucoma surgery, respectively. The patients were matched for ethnicity and age. We identified 246 genes that were differentially expressed by over two-fold and p < 0.05, of which 46 genes were upregulated and 200 genes were downregulated in the fibrotic cell lines compared to the non-fibrotic cell lines. We also carried out detailed gene ontology, KEGG, disease association, pathway commons, WikiPathways and protein network analyses, and identified distinct pathways linked to smooth muscle contraction, inflammatory cytokines, immune mediators, extracellular matrix proteins and oncogene expression. We further validated 11 genes that were highly upregulated or downregulated using real-time quantitative PCR and found a strong correlation between the RNA-Seq and qPCR results. Our study demonstrates that there is a distinct fibrosis gene signature in the conjunctiva after glaucoma surgery and provides new insights into the mechanistic pathways driving the complex fibrotic process in the eye and other tissues.

Role of CCN5 (WNT1 inducible signaling pathway protein 2) in pancreatic islets

In search of direct targets of insulin-like growth factor (IGF)-1 action, we discovered CCN5 (WNT1 inducible signaling pathway protein 2 [WISP2]) as a novel protein expressed in pancreatic β-cells. As a member of the "CCN" ( C ysteine-rich angiogenic inducer 61 [Cyr61], C onnective tissue growth factor [CTGF in humans], and N ephroblastoma overexpressed [Nov; in chickens]) family, the expression of CCN5/WISP2 is stimulated by IGF-1 together with Wnt signaling. When overexpressed in insulinoma cells, CCN5 promotes cell proliferation and cell survival against streptozotocin-induced cell death. The cell proliferation effect seems to be caused by AKT phosphorylation and increased cyclin D1 levels. These properties resemble those of CCN2/CTGF, another isoform of the CCN family, although CCN5 is the only one within the family of six proteins that lacks the C-terminal repeat. Treatment of primary mouse islets with recombinant CCN5 protein produced similar effects to those of gene transfection, indicating that either as a matricellular protein or a secreted growth factor, CCN5 stimulates β-cell proliferation and regeneration in a paracrine fashion. This review also discusses the regulation of CCN5/WISP2 by estrogen and its involvement in angiogenesis and tumorigenesis.

Deficiency of CCN5/WISP-2-Driven Program in breast cancer Promotes Cancer Epithelial cells to mesenchymal stem cells and Breast Cancer growth

Breast cancer progression and relapse is conceivably due to tumor initiating cells (TICs)/cancer stem cells. EMT (epithelial-mesenchymal-transition)-signaling regulates TICs’ turnover. However, the mechanisms associated with this episode are unclear. We show that, in triple-negative-breast cancer (TNBC) cells enriched with TICs, CCN5 significantly blocks cellular growth via apoptosis, reversing EMT-signaling and impairing mammosphere formation, thereby blocking the tumor-forming ability and invasive capacity of these cells. To corroborate these findings, we isolated tumor-initiating side populations (SP) and non-side population (NSP or main population) from MCF-7 cell line, and evaluated the impact of CCN5 on these subpopulations. CCN5 was overexpressed in the NSP but downregulated in the SP. Characteristically, NSP cells are ER-α positive and epithelial type with little tumorigenic potency, while SP cells are very similar to triple-negative ones that do not express ER-α- and Her-2 and are highly tumorigenic in xenograft models. The overexpression of CCN5 in SP results in EMT reversion, ER-α upregulation and delays in tumor growth in xenograft models. We reasoned that CCN5 distinguishes SP and NSP and could reprogram SP to NSP transition, thereby delaying tumor growth in the xenograft model. Collectively, we reveal how CCN5-signaling underlies the driving force to prevent TNBC growth and progression.

Molecular Therapy for Degenerative Disc Disease: Clues from Secretome Analysis of the Notochordal Cell-Rich Nucleus Pulposus

Degenerative disc disease (DDD) is associated with spinal pain often leading to long-term disability. However, the non-chondrodystrophic canine intervertebral disc is protected from the development of DDD, ostensibly due to its retention of notochordal cells (NC) in the nucleus pulposus (NP). In this study, we hypothesized that secretome analysis of the NC-rich NP will lead to the identification of key proteins that delay the onset of DDD. Using mass-spectrometry, we identified 303 proteins including components of TGFβ- and Wnt-signaling, anti-angiogeneic factors and proteins that inhibit axonal ingrowth in the bioactive fractions of serum free, notochordal cell derived conditioned medium (NCCM). Ingenuity Pathway Analysis revealed TGFβ1 and CTGF as major hubs in protein interaction networks. In vitro treatment with TGFβ1 and CTGF promoted the synthesis of healthy extra-cellular matrix proteins, increased cell proliferation and reduced cell death in human degenerative disc NP cells. A single intra-discal injection of recombinant TGFβ1 and CTGF proteins in a pre-clinical rat-tail disc injury model restored the NC and stem cell rich NP. In conclusion, we demonstrate the potential of TGFβ1 and CTGF to mitigate the progression of disc degeneration and the potential use of these molecules in a molecular therapy to treat the degenerative disc.

Overexpressing the novel autocrine/endocrine adipokine WISP2 induces hyperplasia of the heart, white and brown adipose tissues and prevents insulin resistance

WISP2 is a novel adipokine, most highly expressed in the adipose tissue and primarily in undifferentiated mesenchymal cells. As a secreted protein, it is an autocrine/paracrine activator of canonical WNT signaling and, as an intracellular protein, it helps to maintain precursor cells undifferentiated. To examine effects of increased WISP2 in vivo, we generated an aP2-WISP2 transgenic (Tg) mouse. These mice had increased serum levels of WISP2, increased lean body mass and whole body energy expenditure, hyperplastic brown/white adipose tissues and larger hyperplastic hearts. Obese Tg mice remained insulin sensitive, had increased glucose uptake by adipose cells and skeletal muscle in vivo and ex vivo, increased GLUT4, increased ChREBP and markers of adipose tissue lipogenesis. Serum levels of the novel fatty acid esters of hydroxy fatty acids (FAHFAs) were increased and transplantation of Tg adipose tissue improved glucose tolerance in recipient mice supporting a role of secreted FAHFAs. The growth-promoting effect of WISP2 was shown by increased BrdU incorporation in vivo and Tg serum increased mesenchymal precursor cell proliferation in vitro. In contrast to conventional canonical WNT ligands, WISP2 expression was inhibited by BMP4 thereby allowing normal induction of adipogenesis. WISP2 is a novel secreted regulator of mesenchymal tissue cellularity.

Human pancreatic cancer progression: an anarchy among CCN-siblings

Decades of basic and translational studies have identified the mechanisms by which pancreatic cancer cells use molecular pathways to hijack the normal homeostasis of the pancreas, promoting pancreatic cancer initiation, progression, and metastasis, as well as drug resistance. These molecular pathways were explored to develop targeted therapies to prevent or cure this fatal disease. Regrettably, the studies found that majority of the molecular events that dictate carcinogenic growth in the pancreas are non-actionable (potential non-responder groups of targeted therapy). In this review we discuss exciting discoveries on CCN-siblings that reveal how CCN-family members contribute to the different aspects of the development of pancreatic cancer with special emphasis on therapy.

Degradomic and yeast 2-hybrid inactive catalytic domain substrate trapping identifies new membrane-type 1 matrix metalloproteinase (MMP14) substrates: CCN3 (Nov) and CCN5 (WISP2)

Members of the CCN family of matricellular proteins are cytokines linking cells to the extracellular matrix. We report that CCN3 (Nov) and CCN5 (WISP2) are novel substrates of MMP14 (membrane-type 1-matrix metalloproteinase, MT1-MMP) that we identified using MMP14 "inactive catalytic domain capture" (ICDC) as a yeast two-hybrid protease substrate trapping platform in parallel with degradomics mass spectrometry screens for MMP14 substrates. CCN3 and CCN5, previously unknown substrates of MMPs, were biochemically validated as substrates of MMP14 and other MMPs in vitro-CCN5 was processed in the variable region by MMP14 and MMP2, as well as by MMP1, 3, 7, 8, 9 and 15. CCN1, 2 and 3 are proangiogenic factors yet we found novel opposing activity of CCN5 that was potently antiangiogenic in an aortic ring vessel outgrowth model. MMP14, a known regulator of angiogenesis, cleaved CCN5 and abrogated the angiostatic activity. CCN3 was also processed in the variable region by MMP14 and MMP2, and by MMP1, 8 and 9. In addition to the previously reported cleavages of CCN1 and CCN2 by several MMPs we found that MMPs 8, 9, and 1 process CCN1, and MMP8 and MMP9 also process CCN2. Thus, our study reveals additional and pervasive family-wide processing of CCN matricellular proteins/cytokines by MMPs. Furthermore, CCN5 cleavage by proangiogenic MMPs results in removal of an angiogenic brake held by CCN5. This highlights the importance of thorough dissection of MMP substrates that is needed to reveal higher-level control mechanisms beyond type IV collagen and other extracellular matrix protein remodelling in angiogenesis.

SUMMARY

We find CCN family member cleavage by MMPs is more pervasive than previously reported and includes CCN3 (Nov) and CCN5 (WISP2). CCN5 is a novel antiangiogenic factor, whose function is abrogated by proangiogenic MMP cleavage. By processing CCN proteins, MMPs regulate cell responses angiogenesis in connective tissues.

Regulation of the CCN genes by vitamin D: A possible adjuvant therapy in the treatment of cancer and fibrosis

The CCN family is composed of six cysteine-rich, modular, and conserved proteins whose functions span a variety of tissues and include cell proliferation, adhesion, angiogenesis, and wound healing. Roles for the CCN proteins throughout the entire body including the skin, kidney, brain, blood vessels, hematopoietic compartment and others, are continuously being elucidated. Likewise, an understanding of the regulation of this important gene family is constantly becoming clearer, through identification of transcription factors that directly activate, repress, or respond to upstream cell signaling pathways, as well as other forms of gene expression control. Vitamin D (1,25-dihydroxyvitamin D3 or calcitriol), a vitamin essential for numerous biological processes, acts as a potent gene expression modulator. The regulation of the CCN gene family members by calcitriol has been described in many contexts. Here, we provide a concise and thorough overview of what is known about calcitriol and its regulation of the CCN genes, and argue that its regulation is of physiological importance in a wide breadth of tissues in which CCN genes function. In addition, we highlight the effects of vitamin D on CCN gene expression in the setting of two common pathologic conditions, fibrosis and cancer, and propose that the therapeutic effects of vitamin D3 described in these disease states may in part be attributable to CCN gene modulation. As vitamin D is perfectly safe in a wide range of doses and already showing promise as an adjuvant therapeutic agent, a deeper understanding of its control of CCN gene expression may have profound implications in clinical management of disease.

Mechanisms of TGFβ-Induced Epithelial-Mesenchymal Transition

Transitory phenotypic changes such as the epithelial–mesenchymal transition (EMT) help embryonic cells to generate migratory descendants that populate new sites and establish the distinct tissues in the developing embryo. The mesenchymal descendants of diverse epithelia also participate in the wound healing response of adult tissues, and facilitate the progression of cancer. EMT can be induced by several extracellular cues in the microenvironment of a given epithelial tissue. One such cue, transforming growth factor β (TGFβ), prominently induces EMT via a group of specific transcription factors. The potency of TGFβ is partly based on its ability to perform two parallel molecular functions, i.e. to induce the expression of growth factors, cytokines and chemokines, which sequentially and in a complementary manner help to establish and maintain the EMT, and to mediate signaling crosstalk with other developmental signaling pathways, thus promoting changes in cell differentiation. The molecules that are activated by TGFβ signaling or act as cooperating partners of this pathway are impossible to exhaust within a single coherent and contemporary report. Here, we present selected examples to illustrate the key principles of the circuits that control EMT under the influence of TGFβ.

Emerging roles of CCN proteins in vascular development and pathology

The CCN family of proteins consists of 6 members (CCN1-CCN6) that share conserved functional domains. These matricellular proteins interact with growth factors, extracellular matrix (ECM) proteins, cell surface integrins and other receptors to promote ECM-intracellular signaling. This signaling leads to propagation of a variety of cellular actions, including adhesion, invasion, migration and proliferation within several cell types, including epithelial, endothelial and smooth muscle cells. Though CCNs share significant homology, the function of each is unique due to distinct and cell specific expression patterns. Thus, their correct spatial and temporal expressions are critical during embryonic development, wound healing, angiogenesis and fibrosis. Disruption of these patterns leads to severe development disorders and contributes to the pathological progression of cancers, vascular diseases and chronic inflammatory diseases such as colitis, rheumatoid arthritis and atherosclerosis. While the effects of CCNs are diverse, this review will focus on the role of CCNs within the vasculature during development and in vascular diseases.

CCN2 and CCN5 exerts opposing effect on fibroblast proliferation and transdifferentiation induced by TGF-β

Epidural fibrosis might occur after lumbar discectomy and contributes to failed back syndrome. Transforming growth factor (TGF)-β has been reported to influence multiple organ fibrosis, in which connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed 2 (CCN2) and CCN5 are involved. However, the effect of CCN2 and CCN5 on TGF-β induced fibrosis has not yet been elucidated. This study reports that CCN2 and CCN5 play opposing roles in cell proliferation and transdifferentiation of human skin fibroblasts or rabbit epidural scar-derived fibroblasts exposed to TGF-β. We observed that TGF-β1 induced fibroblasts proliferation and differentiation in a dose-dependent manner (from 0 μg/L to 20 μg/L). Meanwhile, CCN2 expression is up-regulated while CCN5 expression is inhibited by TGF-β1 exposure. Furthermore, it is demonstrated that CCN2 overexpression leads to promoted proliferation and elevated collagen and α-smooth muscle actin (α-SMA) expression, which are inhibited by CCN5 overexpression. Moreover, it is shown that the cysteine knot (CT) domain, present in CCN2 but absent in CCN5, plays an essential part in fibroblast proliferation and differentiation. Additionally, enhanced TGF-β and CCN2 expression but decreased CCN5 expression is found in rabbit epidural scar-derived fibroblasts. Overall, the results show the opposing effects of CCN2 and CCN5 on fibroblast proliferation and transdifferentiation induced by TGF-β.

Somatic gene copy number alterations in colorectal cancer: new quest for cancer drivers and biomarkers

Colorectal cancer (CRC) results from the accumulation of genetic alterations, and somatic copy number alterations (CNAs) are crucial for the development of CRC. Genome-wide survey of CNAs provides opportunities for identifying cancer driver genes in an unbiased manner. The detection of aberrant CNAs may provide novel markers for the early diagnosis and personalized treatment of CRC. A major challenge in array-based profiling of CNAs is to distinguish the alterations that play causative roles from the random alterations that accumulate during colorectal carcinogenesis. In this view, we systematically discuss the frequent CNAs in CRC, focusing on functional genes that have potential diagnostic, prognostic and therapeutic significance.

CCN5 attenuates profibrotic phenotypes of fibroblasts through the Smad6-CCN2 pathway: Potential role in epidural fibrosis

Epidural fibrosis is characterized by the development of dense and thick scar tissue adjacent to the dural mater and ranked as the major contributor for post-operative pain recurrence after laminectomy or discectomy. Recently, CCN5 exhibited an inhibitory effect on connective tissue growth factor (CTGF)/CCN2 (a critical regulator for fibrotic disease)-mediated fibrogenesis. However, its function in epidural fibrosis and the underlying mechanisms involved remain to be determined. In this study, an obvious downregulation of CCN5 was observed in scar tissues from laminectomized rats, concomitant with a marked upregulation of CCN2, suggesting a potential negative regulatory role of CCN5 in fibrogenesis. Furthermore, CCN5 overexpression notably mitigated transforming growth factor-β1-enhanced fibroblast viability and proliferation. Of note, CCN5 upregulation inhibited the switch of fibroblasts into myofibroblasts as its overexpression abrogated the expression of the myofibroblast marker, α-smooth muscle actin (α-SMA). CCN5 upregulation also reduced an increase in collagen type I, α1 (COL1A1) and total collagen concentrations. Additionally, CCN5 over expression decreased CCN2 expression and increased Smad6 phosphorylation. Mechanism analysis revealed that blocking Smad6 signaling significantly ameliorated the inhibitory effect of CCN5 on the CCN2 levels, accompanied by the reduction in cell proliferation and collagen production. These results confirm that CCN5 exerts an anti-fibrotic function by regulating the Smad6-CCN2 pathway, thereby indicating a potential approach for ameliorating epidural fibrosis after laminectomy.

Early gene expression in salivary gland after isoproterenol treatment

Isoproterenol, a β-adrenergic agonist, has been shown to induce salivary gland hyperplasia. However, the mechanism involved in this pharmacological phenomenon is not well understood. To gain a better understanding of the underlying changes, including genes, networks and pathways altered by isoproterenol, microarray-based gene expression analysis was conducted on rat parotid glands at 10, 30, and 60 min after isoproterenol injection. After isoproterenol treatment, the number of differentially expressed genes was increased in a time-dependent manner. Pathway analysis showed that cell hyperplasia, p38(MAPK), and IGF-1 were the most altered function, network and pathway, respectively. The balanced regulation of up- and down-expression of genes related to cell proliferation/survival may provide a better understanding of the mechanism of isoproterenol-induced parotid gland enlargement without tumor transformation.

The Tumor-Suppressor WWOX and HDAC3 Inhibit the Transcriptional Activity of the β-Catenin Coactivator BCL9-2 in Breast Cancer Cells

The WW domain containing oxidoreductase (WWOX) has recently been shown to inhibit of the Wnt/β-catenin pathway by preventing the nuclear import of disheveled 2 (DVL2) in human breast cancer cells. Here, it is revealed that WWOX also interacts with the BCL9-2, a cofactor of the Wnt/β-catenin pathway, to enhance the activity of the β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer factors family) transcription factor complexes. By using both a luciferase assay in MCF-7 cells and a Xenopus secondary axis induction assay, it was demonstrated that WWOX inhibits the BCL9-2 function in Wnt/β-catenin signaling. WWOX does not affect the BCL9-2-β-catenin association and colocalizes with BCL9-2 and β-catenin in the nucleus of the MCF-7 cells. Moreover, WWOX inhibits the β-catenin-TCF1 interaction. Further examination found that HDAC3 associates with BCL9-2, enhances the inhibitory effect of WWOX on BCL9-2 transcriptional activity, and promotes the WWOX-BCL9-2 interaction, independent of its deacetylase activity. However, WWOX does not influence the HDAC3-BCL9-2 interaction. Altogether, these results strongly indicate that nuclear WWOX interacts with BCL9-2 associated with β-catenin only when BCL9-2 is in complex with HDAC3 and inhibits its transcriptional activity, in part, by inhibiting the β-catenin-TCF1 interaction. The promotion of the WWOX-BCL9-2 interaction by HDAC3, independent of its deacetylase activity, represents a new mechanism by which this HDAC inhibits transcription.

IMPLICATIONS

The inhibition of the transcriptional activity of BCL9-2 by WWOX and HDAC3 constitutes a new molecular mechanism and provides new insight for a broad range of cancers.

Extracellular matrix in obesity – cancer interactions

Obesity or overweight is a risk factor for several health disorders such as type 2 diabetes, hypertension, and certain cancers. Furthermore, obesity affects almost all body systems including the extracellular matrix (ECM) by generating a pro-inflammatory environment, which are associated with abnormal secretions of several cytokines or hormonal substances, for example, insulin-like growth factors (IGFs), leptin, and sex hormones. These chemical mediators most likely have a great impact on the ECM. Accumulating evidence suggests that both obesity and ECM can influence tumor growth and progression through a number of chemical mediators. Conversely, cells in the connective tissue, namely fibroblasts and macrophages, support and aggravate the inflammatory situation in obesity by releasing several cytokines or growth factors such as vascular endothelial growth factor, epidermal growth factor, and transforming growth factor-beta (TGF-β). A wide range of functions are performed by TGF-β in normal health and pathological conditions including tumorigenesis. Breast cancer in postmenopausal women is a classic example of obesity-related cancer wherein several of these conditions, for example, higher levels of pro-inflammatory cytokines, impairment in the regulation of estrogen and growth factors, and dysregulation of different ECM components may favor the neoplastic process. Aberrant expressions of ECM components such as matrix metalloproteinases or matricellular proteins in both obesity and cancer have been reported by many studies. Nonstructural matricellular proteins, viz., thrombospondins, secreted protein acidic and rich in cysteine (SPARC), and Cyr61-CTGF-Nov (CCN), which function as modulators of cell-ECM interactions, exhibit protean behavior in cancer. Precise understanding of ECM biology can provide potential therapeutic targets to combat obesity-related pathologies.

CCN5/WISP-2 promotes growth arrest of triple-negative breast cancer cells through accumulation and trafficking of p27(Kip1) via Skp2 and FOXO3a regulation

The matricellular protein CCN5/WISP-2 represents a promising target in triple-negative breast cancer (TNBC) because treatment or induced activation of CCN5 in TNBC cells promotes cell growth arrest at the G0/G1 phase, reduces cell proliferation and delays tumor growth in the xenograft model. Our studies found that the p27(Kip1) tumor suppressor protein is upregulated and relocalized to the nucleus from cytoplasm by CCN5 in these cells and that these two events (upregulation and relocalization of p27(Kip1)) are critical for CCN5-induced growth inhibition of TNBC cells. In the absence of CCN5, p27(Kip1) resides mostly in the cytoplasm, which is associated with the aggressive nature of cancer cells. Mechanistically, CCN5 inhibits Skp2 expression, which seems to stabilize the p27(Kip1) protein in these cells. On the other hand, CCN5 also recruits FOXO3a to mediate the transcriptional regulation of p27(Kip1). The recruitment of FOXO3a is achieved by the induction of its expression and activity through shifting from cytoplasm to the nucleus. Our data indicate that CCN5 blocks PI3K/AKT signaling to dephosphorylate at S318, S253 and Thr32 in FOXO3a for nuclear relocalization and activation of FOXO3a. Moreover, inhibition of α6β1 receptors diminishes CCN5 action on p27(Kip1) in TNBC cells. Collectively, these data suggest that CCN5 effectively inhibits TNBC growth through the accumulation and trafficking of p27(Kip1) via Skp2 and FOXO3a regulation, and thus, activation of CCN5 may have the therapeutic potential to kill TNBC.

Targeting WNT1-inducible signaling pathway protein 2 alters human breast cancer cell susceptibility to specific lysis through regulation of KLF-4 and miR-7 expression

The molecular basis for the resistance of tumor cells to cell-mediated cytotoxicity remains poorly understood and thus poses a major challenge for cancer immunotherapy. The present study was designed to determine whether the WNT1-inducible signaling pathway protein 2 (WISP2, also referred to as CCN5), a key regulator of tumor cell plasticity, interferes with tumor susceptibility to cytotoxic T-lymphocyte (CTL)-mediated lysis. We found that silencing WISP2 signaling in human breast adenocarcinoma MCF7 cells impairs CTL-mediated cell killing by a mechanism involving stem cell marker Kruppel-like factor-4 (KLF-4) induction and microRNA-7 (miR-7) downregulation. Inhibition of transforming growth factor beta (TGF-β) signaling using the A83-01 inhibitor in MCF7-shWISP2 cells resulted in a significant reversal of the epithelial-to-mesenchymal-transitioned (EMT) phenotype, the expression of KLF-4 and a partial recovery of target susceptibility to CTLs. More importantly, we showed that silencing KLF-4 was accompanied by a reduction in MCF7-shWISP2 resistance to CTLs. Using human breast cancer tissues, we demonstrated the coexpression of KLF-4 with EMT markers and TGF-β pathway signaling components. More importantly, we found that KLF-4 expression was accompanied by miR-7 inhibition, which is partly responsible for impairing CTL-mediated lysis. Thus, our data indicate that WISP2 has a role in regulating tumor cell susceptibility through EMT by inducing the TGF-β signaling pathway, KLF-4 expression and miR-7 inhibition. These studies indicate for the first time that WISP2 acts as an activator of CTL-induced killing and suggests that the loss of its function promotes evasion of immunosurveillance and the ensuing progression of the tumor.

Loss of WISP2/CCN5 in estrogen-dependent MCF7 human breast cancer cells promotes a stem-like cell phenotype

It has been proposed that the epithelial-mesenchymal transition (EMT) in mammary epithelial cells and breast cancer cells generates stem cell features. WISP2 (Wnt-1-induced signaling protein-2) plays an important role in maintenance of the differentiated phenotype of estrogen receptor-positive breast cancer cells and loss of WISP2 is associated with EMT. We now report that loss of WISP2 in MCF7 breast cancer cells can also promote the emergence of a cancer stem-like cell phenotype characterized by high expression of CD44, increased aldehyde dehydrogenase activity and mammosphere formation. Higher levels of the stem cell markers Nanog and Oct3/4 were observed in those mammospheres. In addition we show that low-cell inoculums are capable of tumor formation in the mammary fat pad of immunodeficient mice. Gene expression analysis show an enrichment of markers linked to stem cell function such as SOX9 and IGFBP7 which is linked to TGF-β inducible, SMAD3-dependent transcription. Taken together, our data demonstrate that WISP2 loss promotes both EMT and the stem-like cell phenotype.