Recombinant Connective Tissue Growth Factor Research Articles

Unraveling Connective Tissue Growth Factor as a Therapeutic Target and Assessing Kahweol as a Potential Drug Candidate in Triple-Negative Breast Cancer Treatment.

Triple-negative breast cancer (TNBC) is characterized by aggressive behavior and limited treatment options, necessitating the identification of novel therapeutic targets. In this study, we investigated the clinical significance of connective tissue growth factor (CTGF) as a prognostic marker and explored the potential therapeutic effects of kahweol, a coffee diterpene molecule, in TNBC treatment. Initially, through a survival analysis on breast cancer patients from The Cancer Genome Atlas (TCGA) database, we found that CTGF exhibited significant prognostic effects exclusively in TNBC patients. To gain mechanistic insights, we performed the functional annotation and gene set enrichment analyses, revealing the involvement of CTGF in migratory pathways relevant to TNBC treatment. Subsequently, in vitro experiments using MDA-MB 231 cells, a representative TNBC cell line, demonstrated that recombinant CTGF (rCTGF) administration enhanced cell motility, whereas CTGF knockdown using CTGF siRNA resulted in reduced motility. Notably, rCTGF restored kahweol-reduced cell motility, providing compelling evidence for the role of CTGF in mediating kahweol's effects. At the molecular level, kahweol downregulated the protein expression of CTGF as well as critical signaling molecules, such as p-ERK, p-P38, p-PI3K/AKT, and p-FAK, associated with cell motility. In summary, our findings propose CTGF as a potential prognostic marker for guiding TNBC treatment and suggest kahweol as a promising antitumor compound capable of regulating CTGF expression to suppress cell motility in TNBC. These insights hold promise for the development of targeted therapies and improved clinical outcomes for TNBC patients.

Hedgehog signaling regulates bone homeostasis through orchestrating osteoclast differentiation and osteoclast-osteoblast coupling.

Imbalance of bone homeostasis induces bone degenerative diseases such as osteoporosis. Hedgehog (Hh) signaling plays critical roles in regulating the development of limb and joint. However, its unique role in bone homeostasis remained largely unknown. Here, we found that canonical Hh signaling pathway was gradually augmented during osteoclast differentiation. Genetic inactivation of Hh signaling in osteoclasts, using Ctsk-Cre;Smof/f conditional knockout mice, disrupted both osteoclast formation and subsequent osteoclast-osteoblast coupling. Concordantly, either Hh signaling inhibitors or Smo/Gli2 knockdown stunted in vitro osteoclast formation. Mechanistically, Hh signaling positively regulated osteoclast differentiation via transactivation of Traf6 and stabilization of TRAF6 protein. Then, we identified connective tissue growth factor (CTGF) as an Hh-regulatory bone formation-stimulating factor derived from osteoclasts, whose loss played a causative role in osteopenia seen in CKO mice. In line with this, recombinant CTGF exerted mitigating effects against ovariectomy induced bone loss, supporting a potential extension of local rCTGF treatment to osteoporotic diseases. Collectively, our findings firstly demonstrate that Hh signaling, which dictates osteoclast differentiation and osteoclast-osteoblast coupling by regulating TRAF6 and CTGF, is crucial for maintaining bone homeostasis, shedding mechanistic and therapeutic insights into the realm of osteoporosis.

Abstract 431: FOXD1 promotes dedifferentiation and targeted therapy resistance in melanoma by regulating the expression of connective tissue growth factor

Abstract Metastatic melanoma is one of the most aggressive skin cancers and is associated with poor prognosis. BRAF and MEK inhibitors are used to treat patients with BRAFV600E-mutated advanced melanoma. However, the development of resistances to these treatments compromises therapeutic success. Our lab previously demonstrated that forkhead box D1 (FOXD1) plays a critical role in melanoma migration and invasion. Here, we found that FOXD1 was highly expressed in melanoma cells. Immunohistochemical assessment of 105 samples from patients with metastatic melanoma revealed that high FOXD1 expression in tumors was associated with poor survival and correlated with low MITF, SOX10 and high AXL expression. Upregulation of FOXD1 expression enhanced the resistance of melanoma to vemurafenib (BRAF inhibitor) or combinatorial treatment with vemurafenib and cobimetinib (MEK inhibitor). On the other hand, loss of FOXD1 increased the sensitivity of naïve melanoma cells towards vemurafenib or combinatorial treatment with vemurafenib and cobimetinib. Furthermore, high FOXD1 expression levels were found in BRAF inhibitor (BRAFi)-resistant cells. Downregulation of FOXD1 resulted in a resensitization of BRAFi-resistant cells to vemurafenib. By using microarray analysis, connective tissue growth factor (CTGF) was found to be one of the most downregulated genes in FOXD1 knockdown (KD) cells while its expression was highly increased upon FOXD1 overexpression. Thus, CTGF was identified as a downstream factor of FOXD1. In addition, in vitro expression analysis and evaluation of clinical samples demonstrated that CTGF and FOXD1 expression were positively correlated. By using a CHIP assay and a dual reporter luciferase assay, we discovered that FOXD1 could regulate the expression of CTGF by directly binding to the CTGF promoter. This result was confirmed with RT-PCR and western blot. In addition, we found that the protein level of CTGF was highly increased in BRAFi-resistant cells. Similar to FOXD1 knockdown, the knockdown of CTGF resensitized BRAFi-resistant cells to vemurafenib. FOXD1 KD cells treated with recombinant CTGF protein were less sensitive towards vemurafenib compared to untreated FOXD1 KD cells. Based on these findings, we conclude that the transcription factor FOXD1 could promote dedifferentiation and targeted therapy-resistance in melanoma cells by regulating the expression of CTGF. FOXD1 might be a promising new diagnostical marker and a therapeutic target of targeted therapy resistant melanoma. Citation Format: Qian Sun, Daniel Novak, Laura Hüser, Juliane Poelchen, Huizi Wu, Karol Granados, Aniello Federico Federico, Ke Liu, Tamara Steinfass, Marlene Vierthaler, Viktor Umansky, Jochen Utikal. FOXD1 promotes dedifferentiation and targeted therapy resistance in melanoma by regulating the expression of connective tissue growth factor [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 431.

The Role of CTGF in Liver Fibrosis Induced in 3D Human Liver Spheroids.

Connective tissue growth factor (CTGF) is involved in the regulation of extracellular matrix (ECM) production. Elevated levels of CTGF can be found in plasma from patients with liver fibrosis and in experimental animal models of liver fibrosis, but the exact role of CTGF in, e.g., diet-induced human liver fibrosis is not entirely known. To address this question, we utilized a 3D human liver co-culture spheroid model composed of hepatocytes and non-parenchymal cells, in which fibrosis is induced by TGF-β1, CTGF or free fatty acids (FFA). Treatment of the spheroids with TGF-β1 or FFA increased COL1A1 deposition as well as the expression of TGF-β1 and CTGF. Recombinant CTGF, as well as angiotensin II, caused increased expression and/or production of CTGF, TGF-β1, COL1A1, LOX, and IL-6. In addition, silencing of CTGF reduced both TGF-β1- and FFA-induced COL1A1 deposition. Furthermore, we found that IL-6 induced CTGF, COL1A1 and TGF-β1 production, suggesting that IL-6 is a mediator in the pathway of CTGF-induced fibrosis. Taken together, our data indicate a specific role for CTGF and CTGF downstream signaling pathways for the development of liver inflammation and fibrosis in the human 3D liver spheroid model.

EGF promotes human trophoblast cell invasion by downregulating CTGF expression via PI3K/AKT signaling.

Although the pro-invasive role of epidermal growth factor (EGF) has been reported in human trophoblast cells, the underlying mechanism remains largely unexplored. This work reveals that EGF-induced downregulation of connective tissue growth factor (CTGF) mediates the EGF-stimulated human trophoblast cell invasion. During the development of the placenta, trophoblast cell invasion must be carefully regulated. Although EGF has been shown to promote trophoblast cell invasion, the underlying mechanism remains largely undetermined. Our previous study using RNA-sequencing (RNA-seq) has identified that kisspeptin-1 is a downstream target of EGF in a human trophoblast cell line, HTR-8/SVneo, and mediates EGF-stimulated cell invasion. In the present study, after re-analysis of our previous RNA-seq data, we found that the CTGF was also downregulated in response to the EGF treatment. The inhibitory effects of EGF on CTGF mRNA and protein levels were confirmed in HTR-8/SVneo cells by reverse transcription quantitative real-time PCR and western blot, respectively. Treatment with EGF activated both PI3K/AKT and ERK1/2 signaling pathways. Using pharmacological inhibitors, our results showed that EGFR-mediated activation of PI3K/AKT signaling was required for the EGF-downregulated CTGF mRNA and protein levels. Matrigel-coated transwell invasion assays demonstrated that EGF treatment stimulated cell invasion. In addition, the invasiveness of HTR-8/SVneo cells was suppressed by treatment with recombinant human CTGF. By contrast, siRNA-mediated knockdown of CTGF increased cell invasion. Notably, the EGF-promoted HTR-8/SVneo cell invasion was attenuated by co-treatment with CTGF. This study provides important insights into the molecular mechanisms mediating EGF-stimulated human trophoblast cell invasion and increases the understanding of the biological functions of CTGF in the human placenta.

Loss of connective tissue growth factor permits mesenchymal transition in ovarian cancer (260)

<b>Objectives:</b> Epithelial-mesenchymal transition (EMT) is a characteristic feature of ovarian cancer (OC) metastasis. Our study aimed to determine the role of Connective Tissue Growth Factor (CTGF) in EMT. <b>Methods:</b> R182 and R2615 are epithelial OC cell lines that are CK18+, b-catenin+, TWIST -, and vimentin+. Time-course experiments +/- Transforming Growth Factor-b (TGF-b) and a TGF-b inhibitor were performed to evaluate the timing of CTGF expression in EMT. R182 and R2615 CTGF knockouts (KO) were derived utilizing a Cas9/CRISPR-Cas9 lentivirus plasmid vector. Phenotypic characterization of wild types (WT) and CTGF KO cell lines were performed with the assays, including scratch wound, proliferation, and anoikis resistance assays. Scratch wound assays were treated with 50 ng/mL and 100 ng/mL concentrations of recombinant CTGF for 48 hours (hr). Cells were plated in triplicate, and confluence was measured. Proliferation was determined by cell count using Biotek Cytation over 72 hr. For anoikis resistance, cells were plated in triplicate in an ultra-low adhesive cell plate with cell growth media. Using Promega CellTiter assay, cell viability was quantified by absorbance at 490 nm at the following time points: 1hr, 24hr, 48hr, and 120hr. Western blots were performed to evaluate the expression of epithelial and mesenchymal markers. RNA sequence analysis was performed, and pathway analysis was evaluated using the iPathway guide. <b>Results:</b> TGF-b induced CTGF expression in both OC cell lines tested. CTGF was induced as early as 30 minutes post-treatment, continued to increase until 6hr, and expression was maintained until 24 hr. No CTGF expression was seen in the mesenchymal mR182 and mR2615 OC cell lines. CTGF KO was confirmed by western blot analysis and indel sequencing. CTGF KO had no effect on the expression of epithelial markers, b-catenin, CK18, and vimentin, but SNAIL, a mesenchymal marker, was induced. Loss of CTGF also had no effect on cell proliferation but promoted anoikis resistance. R182 CTGF KO cells displayed 80% viability when grown in detached conditions for 48hr compared to only 20% viability in WT cells. At 120hr, 30% of KO cells remain viable compared to <10% for WT cells. R2615 WT and KO cells demonstrated similar results. Finally, the scratch assay showed that CTGF KO cells decrease the time to confluence compared to WT. Administration of recombinant CTGF does not rescue the phenotype to WT levels.Fig. 1 <b>Conclusions:</b> CTGF is expressed early in epithelial OC cells during EMT and is regulated by TGF-b. Our data suggest that CTGF permits maintenance of an epithelial phenotype through inhibition of SNAIL expression, and loss of CTGF should be evaluated as a poor prognosis indicator in OC.

Connective tissue growth factor expression maintains the epithelial phenotype of ovarian cancer in early epithelial to mesenchymal transition.

e17544 Background: Epithelial to Mesenchymal Transition (EMT) is essential to the process of metastasis in ovarian cancer (OC). Early expressions of proteins and pathways during EMT essential for understanding mechanism and potential therapeutic targets in OC. The aim of our study is to evaluate the role and mechanism of Connective Tissue Growth Factor (CTGF) in OC. Methods: R182 and R2615 are well-characterized epithelial OC cell lines. CTGF expression +/- Transforming Growth Factor -b (TGF-b) was determined via Western blot. R182 and R2615 CTGF knock out (KO) were derived utilizing a Cas9/CRISPR-Cas9 lentivirus plasmid vector and confirmed via PCR. Anoikis resistance and invasion assays were performed to characterize phenotypes of R182 and R2615 wild type (WT) and KO cells. For anoikis resistance, cells were plated in triplicate in an ultra-low adhesive (ULA) cell plate Promega CellTiter assay which measured cell viability quantified by absorbance at 450 nm at 0, 24, 48, and 72 hrs. For invasion assay, 3000 cells were suspended in 50% reduced growth factor Basement Membrane Extract. Human recombinant CTGF was added at 50 and 100 ng/mL concentrations. Cells were plated in tissue culture plate and placed in Cytation 5/Biospa and imaged at 4-hour interval for up to 6 days. Western blot evaluated expression of mesenchymal markers. Chemo-sensitivity was measured by half maximal inhibitory concentration (IC50) for Cisplatin between the WT and KO cells. RNA sequence analysis was performed for both R182 WT and KO cells and analyzed utilizing iPathway Guide. Results: CTGF is constitutively expressed in R182 and R2615 OC cells line as early as 6 hrs of culture and after 30 min of TGF-b treatment. Loss of CTGF promoted anoikis resistance. At 72 hr, R182 CTGF WT cells displayed 75% viability while R182 KO only have 10% viability. Further, we demonstrated that loss of CTGF increases invasion. Administration of exogeneous CTGF in KO cells suppresses invasion in a dose dependent manner demonstrated. Along with epithelial markers CK-18 and beta-catenin, the KO cells expressed the mesenchymal marker SNAIL. No difference in chemo-sensitivity to Cisplatin was seen between WT and KO in either cell line. RNA sequence analysis identified 1106 out of 14054 differentially expressed genes between the WT and KO cells. PI3KAkt, cell adhesion molecules and ECM receptor interaction were pathway that were most significantly regulated. Conclusions: CTGF expression maintains the epithelial phenotype of OC cells during EMT. Loss of CTGF allows anoikis resistance and invasion which are vital characteristics in the metastatic nature of OC. We suggest that loss of CTGF expression in OC cells could be a biomarker for more aggressive OC.

Connective-Tissue Growth Factor Contributes to TGF-β1-induced Lung Fibrosis.

Idiopathic pulmonary fibrosis is a fatal lung disease characterized by progressive and excessive accumulation of myofibroblasts and in the lung. Connective-tissue growth factor (CTGF) exacerbates pulmonary fibrosis in radiation-induced lung fibrosis, and in this study, we demonstrate upregulation of CTGF in a rat lung fibrosis model induced by an adenovirus vector encoding active TGF-β1 (AdTGF-β1). We show that CTGF is also upregulated in patients with idiopathic pulmonary fibrosis. Expression of CTGF was upregulated in vascular smooth muscle cells cultured from fibrotic lungs on Days 7 and 14 as well as endothelial cells sorted from fibrotic lungs on Days 14 and 28. These findings suggest contributions of different cells in maintaining the fibrotic phenotype during fibrogenesis. Treatment of fibroblasts with recombinant CTGF along with TGF-β increases profibrotic markers in fibroblasts, confirming the synergistic effect of recombinant CTGF with TGF-β in inducing pulmonary fibrosis. Also, the fibrotic extracellular matrix upregulated CTGF expression, compared with the normal extracellular matrix, suggesting that not only profibrotic mediators but also a profibrotic environment contributes to fibrogenesis. We also showed that pamrevlumab, a CTGF inhibitory antibody, partially attenuates fibrosis in the model. These results suggest that pamrevlumab could be an option for treatment of pulmonary fibrosis.

M2-polarized macrophages mediate wound healing by regulating connective tissue growth factor via AKT, ERK1/2, and STAT3 signaling pathways.

Timely and sufficient M1 recruitment and M2 polarization are necessary for fibrosis during wound healing. The mechanism of how M2 mediates wound healing is worth exploring. Abnormally up-regulated connective tissue growth factor (CTGF) influences multiple organ fibrosis, including cardiac, pulmonary, hepatic, renal, and cutaneous fibrosis. Previous studies reported that M2 contributed to hepatic and renal fibrosis by secreting CTGF. It is worth discussing if M2 regulates fibrosis through secreting CTGF in wound healing. We established the murine wound model and inhibited macrophages during proliferation phase with clodronate liposomes in vivo. Macrophages depletion led to down-regulation of wound healing rates, collagen deposition, as well as expression of collagen 1/3 and Ki67. M2 was induced by interleukin-4 (IL-4) and measured by flow cytometry in vitro. Secreted pro-fibrotic and anti-fibrotic factors were tested by enzyme-linked immunosorbent assay (ELISA). M2 was polarized, which producing more CTGF, transforming growth factor-beta1 (TGF-β1), and IL-6, as well as less tumor necrosis factor-α (TNF-α) and IL-10. M2 CTGF gene was blocked using siCTGF. Effects of M2 on fibroblasts activities were detected by cell counting kit 8 (CCK8) and cellular wound healing assay. Expressions of related signaling pathway were assessed by western blotting. Blockade of CTGF in M2 deactivated fibroblasts proliferation and migration by regulating AKT, ERK1/2, and STAT3 pathway. Recombinant CTGF restored these effects. Our research, for the first time, indicated that M2 promoted wound healing by secreting CTGF, which further mediating proliferation and migration of fibroblasts via AKT, ERK1/2, and STAT3 pathway.

FOXD1 promotes dedifferentiation and targeted therapy resistance in melanoma by regulating the expression of connective tissue growth factor.

Metastatic melanoma is an aggressive skin cancer and associated with a poor prognosis. In clinical terms, targeted therapy is one of the most important treatments for patients with BRAFV600E -mutated advanced melanoma. However, the development of resistance to this treatment compromises its therapeutic success. We previously demonstrated that forkhead box D1 (FOXD1) regulates melanoma migration and invasion. Here, we found that FOXD1 was highly expressed in melanoma cells and was associated with a poor survival of patients with metastatic melanoma. Upregulation of FOXD1 expression enhanced melanoma cells' resistance to vemurafenib (BRAF inhibitor [BRAFi]) or vemurafenib and cobimetinib (MEK inhibitor) combination treatment whereas loss of FOXD1 increased the sensitivity to treatment. By comparing gene expression levels between FOXD1 knockdown (KD) and overexpressing (OE) cells, we identified the connective tissue growth factor (CTGF) as a downstream factor of FOXD1. Chromatin immunoprecipitation and luciferase assay demonstrated the direct binding of FOXD1 to the CTGF promoter. Similar to FOXD1, knockdown of CTGF increased the sensitivity of BRAFi-resistant cells to vemurafenib. FOXD1 KD cells treated with recombinant CTGF protein were less sensitive towards vemurafenib compared to untreated FOXD1 KD cells. Based on these findings, we conclude that FOXD1 might be a promising new diagnostic marker and a therapeutic target for the treatment of targeted therapy resistant melanoma.

Connective tissue growth factor promotes retinal pigment epithelium mesenchymal transition via the PI3K/AKT signaling pathway.

Proliferative vitreoretinopathy (PVR) is a disease leading to the formation of contractile preretinal membranes (PRMs) and is one of the leading causes of blindness. Connective tissue growth factor (CTGF) has been identified as a possible key determinant of progressive tissue fibrosis and excessive scarring. Therefore, the present study investigated the role and mechanism of action of CTGF in PVR. Immunohistochemical staining was performed to detect the expression of CTGF, fibronectin and collagen type III in PRMs from patients with PVR. The effects and mechanisms of recombinant human CTGF and its upstream regulator, TGF-β1, on epithelial-mesenchymal transition (EMT) and the synthesis of extracellular matrix (ECM) by retinal pigment epithelium (RPE) cells were investigated using reverse transcription-quantitative PCR, western blotting and a [3H]proline incorporation assay. The data indicated that CTGF, fibronectin and collagen type III were highly expressed in PRMs. In vitro, CTGF significantly decreased the expression of the epithelial markers ZO-1 and E-cadherin and increased that of the mesenchymal markers fibronectin, N-cadherin and α-smooth muscle actin in a concentration-dependent manner. Furthermore, the expression of the ECM protein collagen type III was upregulated by CTGF. However, the trends in expression for the above-mentioned markers were reversed after knocking down CTGF. The incorporation of [3H]proline into RPE cells was also increased by CTGF. In addition, 8-Bromoadenosine cAMP inhibited CTGF-stimulated collagen synthesis and transient transfection of RPE cells with a CTGF antisense oligonucleotide inhibited TGF-β1-induced collagen synthesis. The phosphorylation of PI3K and AKT in RPE cells was promoted by CTGF and TGF-β1 and the latter promoted the expression of CTGF. The results of the present study indicated that CTGF may promote EMT and ECM synthesis in PVR via the PI3K/AKT signaling pathway and suggested that targeting CTGF signaling may have a therapeutic or preventative effect on PVR.

Cyclic Stretch Induces Vascular Smooth Muscle Cells to Secrete Connective Tissue Growth Factor and Promote Endothelial Progenitor Cell Differentiation and Angiogenesis

Endothelial progenitor cells (EPCs) play a vital role in endothelial repair following vascular injury by maintaining the integrity of endothelium. As EPCs home to endothelial injury sites, they may communicate with exposed vascular smooth muscle cells (VSMCs), which are subjected to cyclic stretch generated by blood flow. In this study, the synergistic effect of cyclic stretch and communication with neighboring VSMCs on EPC function during vascular repair was investigated. In vivo study revealed that EPCs adhered to the injury site and were contacted to VSMCs in the Sprague–Dawley (SD) rat carotid artery injury model. In vitro, EPCs were cocultured with VSMCs, which were exposed to cyclic stretch at a magnitude of 5% (which mimics physiological stretch) and a constant frequency of 1.25 Hz for 12 h. The results indicated that stretched VSMCs modulated EPC differentiation into mature endothelial cells (ECs) and promoted angiogenesis. Meanwhile, cyclic stretch upregulated the mRNA expression and secretion level of connective tissue growth factor (CTGF) in VSMCs. Recombinant CTGF (r-CTGF) treatment promoted endothelial differentiation of EPCs and angiogenesis, and increased their protein levels of FZD8 and β-catenin. CTGF knockdown in VSMCs inhibited cyclic stretch-induced EPC differentiation into ECs and attenuated EPC tube formation via modulation of the FZD8/β-catenin signaling pathway. FZD8 knockdown repressed endothelial differentiation of EPCs and their angiogenic activity. Wnt signaling inhibitor decreased the endothelial differentiation and angiogenetic ability of EPCs cocultured with stretched VSMCs. Consistently, an in vivo Matrigel plug assay demonstrated that r-CTGF-treated EPCs exhibited enhanced angiogenesis; similarly, stretched VSMCs also induced cocultured EPC differentiation toward ECs. In a rat vascular injury model, r-CTGF improved EPC reendothelialization capacity. The present results indicate that cyclic stretch induces VSMC-derived CTGF secretion, which, in turn, activates FZD8 and β-catenin to promote both differentiation of cocultured EPCs into the EC lineage and angiogenesis, suggesting that CTGF acts as a key intercellular mediator and a potential therapeutic target for vascular repair.

Transdermal peptide conjugated to human connective tissue growth factor with enhanced cell proliferation and hyaluronic acid synthesis activities produced by a silkworm silk gland bioreactor.

Human connective tissue growth factor (CTGF) is a secreted cysteine-rich peptide that stimulates cell proliferation, migration, and extracellular matrix production during tissue development, differentiation, angiogenesis, implantation, wound healing, and fibrosis processes, with broad application in the medical and cosmetic medical fields. However, the production of CTGF is currently limited by its low yield and purity in current bioreactors. In this study, two genetically modified silkworm strains were generated harboring artificially designed CTGF-8ht and pepCTGF-8ht genes, respectively, that contain an enhanced His-tag with eight histidine residues with or without a transdermal peptide (pep). Both recombinant CTGF-8ht and pepCTGF-8ht proteins were successfully expressed in the silkworm silk gland and cocoon, and could be easily extracted and purified from the cocoon by single-affinity immunoprecipitation column chromatography, achieving a purity of more than 95%. Moreover, compared with CTGF-8ht protein, pepCTGF-8ht protein exhibited better cell proliferation activity by activating the extracellular signal-regulated kinase (ERK) pathway and enhanced hyaluronic acid synthesis activity by upregulating hyaluronan synthase 3 expression; moreover, the addition of pep significantly improved the transmembrane ability of CTGF-8ht protein. These results should help to promote the application prospects of CTGF and further guide the design and development of protein drugs from silkworm and other bioreactor systems. KEY POINTS : A silkworm bioreactor was optimized to produce connective tissue growth factor (CTGF) The transgene contained an enhanced 8-His-tag and transmembrane peptide (pep) Recombinant CTGF was easily purified with maintained or higher biological activity.

Connective tissue growth factor mediates mouse spermatogonial migration associated with differentiation

Spermatogonia migrate to the microenvironment during the establishment from gonocytes and leave it when they differentiate. However, the mechanisms underlying the regulation of spermatogonial differentiation-associated migration remain mostly unknown. In this study, we show that spermatogonial differentiation induced by retinoic acid (RA) was accompanied with increased migration ability and elevated expression of connective tissue growth factor (CTGF), a member of the CCN family. CTGF was mainly expressed in the testicular somatic cells and committed spermatogonial progenitors. Recombinant CTGF (rCTGF) promoted the spermatogonial migration and silencing of endogenous CTGF suppressed the migration of homogenous spermatogonial cell lines. Moreover, depletion of CTGF by neutralizing antibody inhibited the elevated migration ability induced by RA, suggesting both the paracrine and autocrine roles of CTGF in spermatogonial migration associated with differentiation. Finally, CTGF interacted with β1-integrin and regulated its level in spermatogonial cell lines. Together, our study provides novel insights into the regulation of spermatogonial migration by CTGF, which may shed light on the diagnosis and treatment of male infertility.

Cyclic stretch induces vascular smooth muscle cell-derived connective tissue growth factor secretion and promotes endothelial progenitor cell differentiation and angiogenesis

Endothelial progenitor cells (EPCs) play an important role in endothelial repair following vascular injury and maintaining the integrity of endothelium, but the underlying molecular mechanisms regulating the differentiation of EPCs remain to be studied. In this study, the effects of cyclic stretch and the neighboring vascular smooth muscle cells (VSMCs) on the differentiation of EPCs, as well as the underlying mechanism were investigated in a co-culture model. Bone marrow-derived EPCs were cocultured with VSMCs, which were exposed to cyclic stretch with a magnitude of 5% (which mimics physiological mechanical stress) at a constant frequency of 1.25 Hz. The results indicated that stretched VSMCs modulated EPC differentiation into mature endothelial cell (ECs), with upregulation of EC markers (CD31, vWF and KDR) and promoted angiogenesis. Meanwhile, cyclic stretch unregulated the mRNA level and secretion level of connective tissue growth factor (CTGF). After treated with recombinant CTGF (r-CTGF) at the concentration of 20 ng/ml, the mRNA expression of CD31, vWF and KDR in EPCs were increased, EPC tube formation and the protein level of FZD8 and β-catenin were promoted. Small interfering RNA (siRNA)-mediated knockdown of CTGF in VSMCs inhibited cyclic stretch-induced EPC differentiation into ECs and attenuated EPC tube formation via modulation of FZD8/β-catenin signaling pathway in vitro. Consistently, in vivo matrigel plug assay demonstrated that r-CTGF treated EPCs enhanced angiogenesis. The present results indicate that cyclic stretch induces VSMC-derived CTGF secretion, which in turn activates FZD8 and β-catenin to promote co-cultured EPC differentiation into EC lineage and angiogenesis. Our findings provide insights into the mechanisms underlying the VSMC/EPC interactions and the pro-angiogenic function of cyclic stretch in modulating EPC differentiation. CTGF acts as a key intercellular mediator and may be as a potential therapeutic target for vascular injury.

CTGF Attenuates Tendon-Derived Stem/Progenitor Cell Aging.

Aged tendon-derived stem/progenitor cells (TSPCs) lead to age-related tendon disorders and impair tendon healing. However, the underlying molecular mechanisms of TSPC aging remain largely unknown. Here, we investigated the role of connective tissue growth factor (CTGF) in TSPC aging. CTGF protein and mRNA levels were markedly decreased in the aged TSPCs. Moreover, recombinant CTGF attenuates TSPC aging and restores the age-associated reduction of self-renewal and differentiation of TSPCs. In addition, cell cycle distribution of aged TSPCs was arrested in the G1/S phase while recombinant CTGF treatment promoted G1/S transition. Recombinant CTGF also rescued decreased levels of cyclin D1 and CDK4 and reduced p27kip1 expression in aged TSPCs. Our results demonstrated that CTGF plays a vital role in TSPC aging and might be a potential target for molecular therapy of age-related tendon disorders.

Identification of novel fibroblast-like cells from stem cells from human exfoliated deciduous teeth.

This study aimed to differentiate and characterize fibroblast-like cells from stem cells from human exfoliated deciduous teeth (SHED). The differentiation of fibroblast-like cells from SHED was carried out by using specific human recombinant connective tissue growth factor (CTGF). To characterize fibroblastic differentiation, the induced cells were subjected to morphological changes, proliferation rate, gene expression analysis using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), flow cytometry, and immunofluorescence staining. The commercial primary human gingival fibroblasts served as positive control in this study. The results from characterization analysis were compared with that of commercial cells to ensure that the cells differentiated from SHED were fibroblast-like cells. The results showed the inductive effect of CTGF for fibroblastic differentiation in SHED. SHED-derived fibroblasts were successfully characterized despite having similar morphological appearance, i.e., (i) significant proliferation rate between fibroblast-like cells and SHED, (ii) high expression of fibroblast-associated markers in qRT-PCR analysis, and (iii) positive staining against collagen type 1, fibroblast-specific protein 1, and human thymic fibroblasts in flow cytometry analysis and immunofluorescence staining. The same expression patterns were found in primary human gingival fibroblasts, respectively. SHED as negative control showed lower expression or no signal, thus confirming the cells differentiated from SHED were fibroblast-like cells. Taken together, the protocol adopted in this study suggests CTGF to be an appropriate inducer in the differentiation of SHED into fibroblast-like cells. The fibroblast-like cells differentiated from SHED could be used in future in vitro and in vivo dental tissue regeneration studies as well as in clinical applications where these cells are needed.

22P - Therapeutic potential of connective tissue growth factor (CTGF) in triple-negative breast cancer

Background: Matricellular proteins are a subset of extracellular matrix (ECM) proteins which are dynamically expressed and serve many regulatory roles. Among matricellular proteins, the CCN family, a group of secreted proteins are known to regulate cell adhesion, migration, proliferation, differentiation, apoptosis, survival, senescence, and gene expression. Connective tissue growth factor (CTGF), also known as CCN2, is a member of the CCN family. CTGF is known to have many roles in biological processes such as cell proliferation, migration, adhesion, and angiogenesis. Methods: To investigate the function of CTGF in triple-negative breast cancer cells (TNBC), we silenced CTGF in TNBC cell lines using short hairpin RNA. Knockdown of CTGF was verified by western blot, qPCR, and immunostaining. The effect of CTGF knockdown on TNBCs was examined by cell proliferation assay, adhesion assay, migration assays, metabolism assays, and cell cycle analysis. Results: Knockdown of CTGF decreased cell proliferation, adhesion, migration, glucose uptake, ATP production and lactate production. Since CTGF is a secreted protein, we gave recombinant human CTGF (rhCTGF) to the cells and found that rhCTGF induced activation of the Src/FAK/MAPK pathway and led to expression of proteins related to cell cycle progression. Also, when CTGF-specific antibodies were given to the cells, they expressed cytotoxicity by neutralizing the extracellular CTGF and decreasing CTGF-mediated signalling. Conclusions: We suggest that the secreted CTGF mediates tumor cell progression via modulation of cell proliferation, adhesion, migration and metabolism and could possess a potential for being a therapeutic target. Legal entity responsible for the study: Hanyang University. Funding: National Research Foundation of Korea. Disclosure: All authors have declared no conflicts of interest.

Essential role of connective tissue growth factor (CTGF) in transforming growth factor-\u03b21 (TGF-\u03b21)-induced myofibroblast transdifferentiation from Graves\u2019 orbital fibroblasts

Connective tissue growth factor (CTGF) associated with transforming growth factor-β (TGF-β) play a pivotal role in the pathophysiology of many fibrotic disorders. However, it is not clear whether this interaction also takes place in GO. In this study, we investigated the role of CTGF in TGF-β-induced extracellular matrix production and myofibroblast transdifferentiation in Graves’ orbital fibroblasts. By Western blot analysis, we demonstrated that TGF-β1 induced the expression of CTGF, fibronectin, and alpha-smooth muscle actin (α-SMA) in Graves’ orbital fibroblasts. In addition, the protein levels of fibronectin and α-SMA in Graves’ orbital fibroblasts were also increased after treatment with a recombinant human protein CTGF (rhCTGF). Moreover, we transfected the orbital fibroblasts with a small hairpin RNA of CTGF gene (shCTGF) to knockdown the expression levels of CTGF, which showed that knockdown of CTGF significantly diminished TGF-β1-induced expression of CTGF, fibronectin and α-SMA proteins in Graves’ orbital fibroblasts. Furthermore, the addition of rhCTGF to the shCTGF-transfected orbital fibroblasts could restore TGF-β1-induced expression of fibronectin and α-SMA proteins. Our findings demonstrate that CTGF is an essential downstream mediator for TGF-β1-induced extracellular matrix production and myofibroblast transdifferentiation in Graves’ orbital fibroblasts and thus may provide with a potential therapeutic target for treatment of GO.

TGF-β1 Inhibits Human Trophoblast Cell Invasion by Upregulating Connective Tissue Growth Factor Expression.

Appropriate trophoblast invasion into the maternal endometrium is essential for successful human implantation and placentation. Connective tissue growth factor (CTGF), also known as CCN2, is a matricellular protein that is expressed in the placenta. Interestingly, the CTGF expression levels in the placenta and serum from patients with severe preeclampsia or fetal growth restriction are higher than those from healthy controls. However, to date, the role of CTGF in the regulation of trophoblast cell invasion remains unclear. Transforming growth factor-β1 (TGF-β1) is a potent stimulator of CTGF expression and has been shown to inhibit trophoblast cell invasiveness. However, whether CTGF mediates TGF-β1-inhibited human trophoblast cell invasion is unknown. In the present study, we show that treatment with TGF-β1 upregulates CTGF expression in a human trophoblast cell line, HTR-8/SVneo, and in primary human trophoblast cells. Our results also demonstrate that the SMAD2/3 signaling pathways are required for TGF-β1-induced upregulation of CTGF. Importantly, CTGF knockdown attenuates TGF-β1-inhibited cell invasion. Furthermore, cell invasiveness is decreased by treatment with recombinant CTGF. These results provide evidence that CTGF mediates TGF-β1-inhibited human trophoblast cell invasion.