CTGF enhances migration and MMP-13 up-regulation via αvβ3 integrin, FAK, ERK, and NF-κB-dependent pathway in human chondrosarcoma cells

Key regulators of hepatic stellate cell activation in alcohol liver Disease: A comprehensive review

Alcoholic liver disease (ALD) is a broad category of disorders that begin with liver injury, lead to liver fibrosis, and ultimately conclude in alcohol-induced liver cirrhosis, the most chronic and irreversible liver damage. Liver fibrosis (LF) is a common pathological characteristic observed in most chronic liver inflammatory conditions that involve prolonged inflammation. In this review, we have summarized ethanol-mediated hepatic stellate cell (HSCs) activation and its role in liver fibrosis progression. We highlight important molecular mechanisms that are modulated by ethanol, play a role in the activation of HSCs and the progression of liver fibrosis and identifying potential targets to ameliorate liver fibrosis.

Fibrotic pathways and fibroblast-like synoviocyte phenotypes in osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis, characterized by osteophyte formation, cartilage degradation, and structural and cellular alterations of the synovial membrane. Activated fibroblast-like synoviocytes (FLS) of the synovial membrane have been identified as key drivers, secreting humoral mediators that maintain inflammatory processes, proteases that cause cartilage and bone destruction, and factors that drive fibrotic processes. In normal tissue repair, fibrotic processes are terminated after the damage has been repaired. In fibrosis, tissue remodeling and wound healing are exaggerated and prolonged. Various stressors, including aging, joint instability, and inflammation, lead to structural damage of the joint and micro lesions within the synovial tissue. One result is the reduced production of synovial fluid (lubricants), which reduces the lubricity of the cartilage areas, leading to cartilage damage. In the synovial tissue, a wound-healing cascade is initiated by activating macrophages, Th2 cells, and FLS. The latter can be divided into two major populations. The destructive thymocyte differentiation antigen (THY)1─ phenotype is restricted to the synovial lining layer. In contrast, the THY1+ phenotype of the sublining layer is classified as an invasive one with immune effector function driving synovitis. The exact mechanisms involved in the transition of fibroblasts into a myofibroblast-like phenotype that drives fibrosis remain unclear. The review provides an overview of the phenotypes and spatial distribution of FLS in the synovial membrane of OA, describes the mechanisms of fibroblast into myofibroblast activation, and the metabolic alterations of myofibroblast-like cells.

Drugs targeting CTGF in the treatment of pulmonary fibrosis

Pulmonary fibrosis represents the final alteration seen in a wide variety of lung disorders characterized by increased fibroblast activity and the accumulation of substantial amounts of extracellular matrix, along with inflammatory damage and the breakdown of tissue architecture. This condition is marked by a significant mortality rate and a lack of effective treatments. The depositing of an excessive quantity of extracellular matrix protein follows the damage to lung capillaries and alveolar epithelial cells, leading to pulmonary fibrosis and irreversible damage to lung function. It has been proposed that the connective tissue growth factor (CTGF) plays a critical role in the advancement of pulmonary fibrosis by enhancing the accumulation of the extracellular matrix and exacerbating fibrosis. In this context, the significance of CTGF in pulmonary fibrosis is examined, and a summary of the development of drugs targeting CTGF for the treatment of pulmonary fibrosis is provided.

Knockdown of ribosome RNA processing protein 15 suppresses migration of hepatocellular carcinoma through inhibiting PATZ1-associated LAMC2/FAK pathway

BACKGROUND

Ribosomal RNA processing protein 15 (RRP15) has been found to regulate the progression of hepatocellular carcinoma (HCC). Nevertheless, the extent to which it contributes to the spread of HCC cells remains uncertain. Thus, the objective of this research was to assess the biological function of RRP15 in the migration of HCC.

METHODS

The expression of RRP15 in HCC tissue microarray (TMA), tumor tissues and cell lines were determined. In vitro, the effects of RRP15 knockdown on the migration, invasion and adhesion ability of HCC cells were assessed by wound healing assay, transwell and adhesion assay, respectively. The effect of RRP15 knockdown on HCC migration was also evaluated in vivo in a mouse model.

RESULTS

Bioinformatics analysis showed that high expression of RRP15 was significantly associated with low survival rate of HCC. The expression level of RRP15 was strikingly upregulated in HCC tissues and cell lines compared with the corresponding controls, and TMA data also indicated that RRP15 was a pivotal prognostic factor for HCC. RRP15 knockdown in HCC cells reduced epithelial-to-mesenchymal transition (EMT) and inhibited migration in vitro and in vivo, independent of P53 expression. Mechanistically, blockade of RRP15 reduced the protein level of the transcription factor POZ/BTB and AT hook containing zinc finger 1 (PATZ1), resulting in decreased expression of the downstream genes encoding laminin 5 subunits, LAMC2 and LAMB3, eventually suppressing the integrin β4 (ITGB4)/focal adhesion kinase (FAK)/nuclear factor κB kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway.

CONCLUSIONS

RRP15 promotes HCC migration by activating the LAMC2/ITGB4/FAK pathway, providing a new target for future HCC treatment.

Combination of Anti-Angiogenics and Immunotherapies in Renal Cell Carcinoma Show Their Limits: Targeting Fibrosis to Break through the Glass Ceiling?

This review explores treating metastatic clear cell renal cell carcinoma (ccRCC) through current therapeutic modalities-anti-angiogenic therapies and immunotherapies. While these approaches represent the forefront, their limitations and variable patient responses highlight the need to comprehend underlying resistance mechanisms. We specifically investigate the role of fibrosis, prevalent in chronic kidney disease, influencing tumour growth and treatment resistance. Our focus extends to unravelling the intricate interplay between fibrosis, immunotherapy resistance, and the tumour microenvironment for effective therapy development. The analysis centres on connective tissue growth factor (CTGF), revealing its multifaceted role in ccRCC-promoting fibrosis, angiogenesis, and cancer progression. We discuss the potential of targeting CTGF to address the problem of fibrosis in ccRCC. Emphasising the crucial relationship between fibrosis and the immune system in ccRCC, we propose that targeting CTGF holds promise for overcoming obstacles to cancer treatment. However, we recognise that an in-depth understanding of the mechanisms and potential limitations is imperative and, therefore, advocate for further research. This is an essential prerequisite for the successful integration of CTGF-targeted therapies into the clinical landscape.

Therapeutic strategies to target connective tissue growth factor in fibrotic lung diseases

The treatment of interstitial lung diseases, including idiopathic pulmonary fibrosis (IPF), remains challenging as current available antifibrotic agents are not effective in halting disease progression. Connective tissue growth factor (CTGF), also known as cellular communication factor 2 (CCN2), is a member of the CCN family of proteins that regulates cell signaling through cell surface receptors such as integrins, the activity of cytokines/growth factors, and the turnover of extracellular matrix (ECM) proteins. Accumulating evidence indicates that CTGF plays a crucial role in promoting lung fibrosis through multiple processes, including inducing transdifferentiation of fibroblasts to myofibroblasts, epithelial-mesenchymal transition (EMT), and cooperating with other fibrotic mediators such as TGF-β. Increased expression of CTGF has been observed in fibrotic lungs and inhibiting CTGF signaling has been shown to suppress lung fibrosis in several animal models. Thus, the CTGF signaling pathway is emerging as a potential therapeutic target in IPF and other pulmonary fibrotic conditions. This review provides a comprehensive overview of the current evidence on the pathogenic role of CTGF in pulmonary fibrosis and discusses the current therapeutic agents targeting CTGF using a systematic review approach.

Focal adhesion kinase (FAK): its structure, characteristics, and signaling in skeletal system

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase and distributes important regulatory functions in skeletal system. Mesenchymal stem cell (MSC) possesses significant migration and differentiation capacity, is an important source of distinctive bone cells production and a prominent bone development pathway. MSC has a wide range of applications in tissue bioengineering and regenerative medicine, and is frequently employed for hematopoietic support, immunological regulation, and defect repair, although current research is insufficient. FAK has been identified to cross-link with many other keys signaling pathways in bone biology and is considered as a fundamental "crossroad" on the signal transduction pathway and a "node" in the signal network to mediate MSC lineage development in skeletal system. In this review, we summarized the structure, characteristics, cellular signaling, and the interactions of FAK with other signaling pathways in the skeletal system. The discovery of FAK and its mediated molecules will lead to a new knowledge of bone development and bone construction as well as considerable potential for therapeutic use in the treatment of bone-related disorders such as osteoporosis, osteoarthritis, and osteosarcoma.

Ensemble learning model for identifying the hallmark genes of NFκB/TNF signaling pathway in cancers

BACKGROUND

The nuclear factor kappa B (NFκB) regulatory pathways downstream of tumor necrosis factor (TNF) play a critical role in carcinogenesis. However, the widespread influence of NFκB in cells can result in off-target effects, making it a challenging therapeutic target. Ensemble learning is a machine learning technique where multiple models are combined to improve the performance and robustness of the prediction. Accordingly, an ensemble learning model could uncover more precise targets within the NFκB/TNF signaling pathway for cancer therapy.

METHODS

In this study, we trained an ensemble learning model on the transcriptome profiles from 16 cancer types in the TCGA database to identify a robust set of genes that are consistently associated with the NFκB/TNF pathway in cancer. Our model uses cancer patients as features to predict the genes involved in the NFκB/TNF signaling pathway and can be adapted to predict the genes for different cancer types by switching the cancer type of patients. We also performed functional analysis, survival analysis, and a case study of triple-negative breast cancer to demonstrate our model's potential in translational cancer medicine.

RESULTS

Our model accurately identified genes regulated by NFκB in response to TNF in cancer patients. The downstream analysis showed that the identified genes are typically involved in the canonical NFκB-regulated pathways, particularly in adaptive immunity, anti-apoptosis, and cellular response to cytokine stimuli. These genes were found to have oncogenic properties and detrimental effects on patient survival. Our model also could distinguish patients with a specific cancer subtype, triple-negative breast cancer (TNBC), which is known to be influenced by NFκB-regulated pathways downstream of TNF. Furthermore, a functional module known as mononuclear cell differentiation was identified that accurately predicts TNBC patients and poor short-term survival in non-TNBC patients, providing a potential avenue for developing precision medicine for cancer subtypes.

CONCLUSIONS

In conclusion, our approach enables the discovery of genes in NFκB-regulated pathways in response to TNF and their relevance to carcinogenesis. We successfully categorized these genes into functional groups, providing valuable insights for discovering more precise and targeted cancer therapeutics.

The role of YAP1 target gene CTGF in the anoikis resistance of rheumatoid arthritis synovial fibroblasts

OBJECTIVE

To analyse pro-survival mechanisms elicited in RA synovial fibroblasts (RASFs) upon detachment from their extracellular matrix dependent on the disintegrin metalloproteinase ADAM15 and Yes-associated protein kinase 1 (YAP1).

METHODS

Detachment-induced apoptosis was determined by caspase 3/7 assays. Immunofluorescent stainings, cell surface biotinylation and immunoblotting were applied to analyse phosphorylated kinases and subcellular localization of YAP1 and connective tissue growth factor (CTGF). Caspase and transwell transmigration assays served to study CTGF function.

RESULTS

Silencing of ADAM15 or YAP1 in RASFs leads to significantly increased levels of detachment-induced caspase activity. In non-silenced RASFs detachment causes simultaneous ADAM15-enhanced phosphorylation of YAP1 at S127, known for promoting its cytoplasmic localization, and Src-dependent phosphorylation at tyrosine Y357. The majority of nuclear YAP1 leaves the nucleus shortly after cell detachment, but prolonged detachment causes a marked nuclear re-entry of YAP1, resulting in significantly increased synthesis of CTGF. The newly synthesized CTGF, however, is not detectable in the supernatant, but is bound to the outside of the plasma membrane. In vitro studies demonstrated autocrine binding of CTGF to the EGF receptor and β1 integrin, with concomitant triggering of survival kinases, AKT1, ERK1/2, Src and focal adhesion kinase. Functional studies revealed anti-apoptotic effects of CTGF on detached RASFs and an enhancement of their potential for endothelial transmigration using HUVEC-coated transwells.

CONCLUSION

The elucidation of a new molecular mechanism that protects RASFs in the highly pro-apoptotic environment of inflamed RA joints by promoting anoikis-resistance and transendothelial migration via ADAM15/YAP1-mediated CTGF upregulation uncovers potentially new targets for future therapeutic intervention.

The TAZ-CAMTA1 Fusion Protein Promotes Tumorigenesis via Connective Tissue Growth Factor and Ras-MAPK Signaling in Epithelioid Hemangioendothelioma

PURPOSE

A consistent genetic alteration in vascular cancer epithelioid hemangioendothelioma (EHE) is the t(1;3)(p36;q25) chromosomal translocation, which generates a WWTR1(TAZ)-CAMTA1 (TC) fusion gene. TC is a transcriptional coactivator that drives EHE. Here, we aimed to identify the TC transcriptional targets and signaling mechanisms that underlie EHE tumorigenesis.

EXPERIMENTAL DESIGN

We used NIH3T3 cells transformed with TC (NIH3T3/TC) as a model system to uncover TC-dependent oncogenic signaling. These cells proliferated in an anchorage-independent manner in suspension and soft agar. The findings of the cell-based studies were validated in a xenograft model.

RESULTS

We identified connective tissue growth factor (CTGF) as a tumorigenic transcriptional target of TC. We show that CTGF binds to integrin αIIbβ3, which is essential for sustaining the anchorage-independent proliferation of transformed NIH3T3/TC cells. NIH3T3/TC cells also have enhanced Ras and MAPK signaling, and the activity of these pathways is reduced upon CTGF knockdown, suggesting that CTGF signaling occurs via the Ras-MAPK cascade. Further, pharmacologic inhibition of MAPK signaling through PD 0325901 and trametinib abrogated TC-driven anchorage-independent growth. Likewise, for tumor growth in vivo, NIH3T3/TC cells require CTGF and MAPK signaling. NIH3T3/TC xenograft growth was profoundly reduced upon CTGF knockdown and after trametinib treatment.

CONCLUSIONS

Collectively, our results demonstrated that CTGF and the Ras-MAPK signaling cascade are essential for TC-mediated tumorigenesis. These studies provided the preclinical rationale for SARC033 (NCI 10015-NCT03148275), a nonrandomized, open-label, phase II study of trametinib in patients with unresectable or metastatic EHE.

Extracellular ATP promotes angiogenesis and adhesion of TNBC cells to endothelial cells via up-regulation of CTGF

Our previous works have indicated that extracellular ATP is an important prometastasis factor. However, the molecular mechanism involved needs to be further studied. We demonstrated that extracellular ATP treatment could upregulate the expression of connective tissue growth factor (CTGF) in both triple‐negative breast cancer (TNBC) cells and endothelial cells (ECs). Extracellular ATP stimulated the migration of TNBC cells and ECs, and angiogenesis of ECs via the P2Y2––YAP‐CTGF axis. Furthermore, we demonstrated that adenosine triphosphate (ATP) stimulated TNBC cell adhesion to ECs and transmigration through the EC layer via CTGF by upregulation of integrin β1 on TNBC cells and VCAM‐1 on ECs. Both apyrase (ATP‐diphosphohydrolase) and CTGF shRNA treatments could inhibit the metastasis of inoculated tumors to lung and liver in a mouse model, and these treated tumors had fewer blood vessels. Collectively, our data indicated that extracellular ATP promotes tumor angiogenesis and the interactions between TNBC cells and ECs through upregulation of CTGF, thereby stimulating TNBC metastasis. The pleiotropic effects of ATP in angiogenesis and cell adhesion suggest that extracellular ATP or CTGF could be an effective target for TNBC therapy.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

Atractylenolide-I Sensitizes Triple-Negative Breast Cancer Cells to Paclitaxel by Blocking CTGF Expression and Fibroblast Activation

This investigation was conducted to elucidate whether atractylenolide-I (ATL-1), which is the main component of Atractylodes macrocephala Koidz, can sensitize triple-negative breast cancer (TNBC) cells to paclitaxel and investigate the possible mechanism involved. We discovered that ATL-1 could inhibit tumor cell migration and increase the sensitivity of tumor cells to paclitaxel. ATL-1 downregulated the expression and secretion of CTGF in TNBC cells. Apart from inhibiting TNBC cell migration via CTGF, ATL-1 downregulated the expression of CTGF in fibroblasts and decreased the ability of breast cancer cells to transform fibroblasts into cancer-associated fibroblasts (CAFs), which in turn increased the sensitivity of TNBC cells to paclitaxel. In a mouse model, we found that ATL-1 treatments could enhance the chemotherapeutic effect of paclitaxel on tumors and reduce tumor metastasis to the lungs and liver. Primary cultured fibroblasts derived from inoculated tumors in mice treated with ATL-1 combined with paclitaxel expressed relatively low levels of CAF markers. Collectively, our data indicate that ATL-1 can sensitize TNBC cells to paclitaxel by blocking CTGF expression and fibroblast activation and could be helpful in future research to determine the value of ATL-1 in the clinical setting.

CCN proteins in the musculoskeletal system: current understanding and challenges in physiology and pathology

The acronym for the CCN family was recently revised to represent “cellular communication network”. These six, small, cysteine-enriched and evolutionarily conserved proteins are secreted matricellular proteins, that convey and modulate intercellular communication by interacting with structural proteins, signalling factors and cell surface receptors. Their role in the development and physiology of musculoskeletal system, constituted by connective tissues where cells are interspersed in the cellular matrix, has been broadly studied. Previous research has highlighted a crucial balance of CCN proteins in mesenchymal stem cell commitment and a pivotal role for CCN1, CCN2 and their alter ego CCN3 in chondrogenesis and osteogenesis; CCN4 plays a minor role and the role of CCN5 and CCN6 is still unclear. CCN proteins also participate in osteoclastogenesis and myogenesis. In adult life, CCN proteins serve as mechanosensory proteins in the musculoskeletal system providing a steady response to environmental stimuli and participating in fracture healing. Substantial evidence also supports the involvement of CCN proteins in inflammatory pathologies, such as osteoarthritis and rheumatoid arthritis, as well as in cancers affecting the musculoskeletal system and bone metastasis. These matricellular proteins indeed show involvement in inflammation and cancer, thus representing intriguing therapeutic targets. This review discusses the current understanding of CCN proteins in the musculoskeletal system as well as the controversies and challenges associated with their multiple and complex roles, and it aims to link the dispersed knowledge in an effort to stimulate and guide readers to an area that the writers consider to have significant impact and relevant potentialities.

PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression in MIO mice

This study aims to investigate the effects and mechanisms of parathyroid hormone [1-34] (PTH1-34) on TNF-α-stimulated mice chondrocytes, as well as cartilage from a meniscus injury induced osteoarthritis (MIO) mice model. The C57BL/6J mice received medial meniscectomy, and then administrated with PTH1-34. The results showed that PTH1-34 administration decreased secondary allodynia and the pain-related transcripts. The IHC, ELISA, Micro-CT imaging and histopathology analysis revealed the significantly improved subchondral plate thickness and bone porosity, the reduced pro-inflammatory cytokines in serum and joint fluid. In vitro, mice chondrocyte was treated with TNF-α or co-cultured with synovial cells. The results showed that TNF-α markedly upregulated the MMP13 expression, and the ERK1/2, NF-κB or PI3K signaling pathway inhibitors could reverse the induction effect of TNF-α on expression of MMP13 in chondrocytes. PTH1-34 alone has no effect on the expression of MMP13 and NF-κB signaling pathways, but the PTH1-34 could reverse the induction effect of TNF-α on MMP13 expression and NF-κB signaling pathway activation in chondrocytes. In addition, PTH1-34 administration inhibited the expression of TNF-α and MMP13, and chondrocyte viability, while the PKA repressor reversed the effect of PTH1-34 in chondrocytes co-cultured with synovial cells. In conclusion, PTH1-34 has an obvious analgesic and anti-inflammatory effect, inhibits the matrix synthesis and alleviates the progression of osteoarthritis. In vitro, PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression via the PKA pathway and the NF-κB signaling pathways, respectively.

A CTGF-RUNX2-RANKL Axis in Breast and Prostate Cancer Cells Promotes Tumor Progression in Bone

Metastasis to bone is a frequent occurrence in patients with breast and prostate cancers and inevitably threatens the patient's quality of life and survival. Identification of cancer-derived mediators of bone metastasis and osteolysis may lead to novel therapeutic strategies. In this study, we established highly bone-metastatic PC3 prostate and MDA-MB-231 (MDA) breast cancer cell sublines by in vivo selection in mice. In bone-metastatic cancer cells, the expression and secretion of connective tissue growth factor (CTGF) were highly upregulated. CTGF knockdown in bone-metastatic cells decreased invasion activity and MMP expression. RUNX2 overexpression in the CTGF knockdown cells restored the invasion activity and MMP expression. In addition, CTGF increased RUNX2 protein stability by inducing its acetylation via p300 acetyl transferase. The integrin αvβ3 receptor mediated these effects of CTGF. Furthermore, CTGF promoted RUNX2 recruitment to the RANKL promoter, resulting in increased RANKL production from the tumor cells and subsequent stimulation of osteoclastogenesis from precursor cells. In addition, animal model with injection of CTGF knocked-down prostate cancer cells into 6-week old BALB/c male mice showed reduced osteolytic lesions. More importantly, the expression levels of CTGF and RANKL showed a strong positive correlation in human primary breast tumor tissues and were higher in bone metastases than in other site metastases. These findings indicate that CTGF plays crucial roles for osteolytic bone metastasis both by enhancing invasiveness of tumor cells and by producing RANKL for osteoclastogenesis. Targeting CTGF may lead to the development of effective preventive and therapeutic strategies for osteolytic metastasis. © 2019 American Society for Bone and Mineral Research.

Induction of Fibrogenic Phenotype in Human Mesenchymal Stem Cells by Connective Tissue Growth Factor in a Hydrogel Model of Soft Connective Tissue

Scar formation is the typical endpoint of wound healing in adult mammalian tissues. An overactive or prolonged fibrogenic response following injury leads to excessive deposition of fibrotic proteins that promote tissue contraction and scar formation. Although well-defined in the dermal tissue, the progression of fibrosis is less explored in other connective tissues, such as the vocal fold. To establish a physiologically relevant 3D model of loose connective tissue fibrosis, we have developed a synthetic extracellular matrix using hyaluronic acid (HA) and peptidic building blocks carrying complementary functional groups. The resultant network was cell adhesive and protease degradable, exhibiting viscoelastic properties similar to the human vocal fold. Human mesenchymal stem cells (hMSCs) were encapsulated in the HA matrix as single cells or multicellular aggregates and cultured in pro-fibrotic media containing connective tissue growth factor (CTGF) for up to 21 days. hMSCs treated with CTGF-supplemented media exhibited an increased expression of fibrogenic markers and ECM proteins associated with scarring. Incorporation of α-smooth muscle actin into F-actin stress fibers was also observed. Furthermore, CTGF treatment increased the migratory capacity of hMSCs as compared to the CTGF-free control groups, indicative of the development of a myofibroblast phenotype. Addition of an inhibitor of the mitogen-activated protein kinase (MAPK) pathway attenuated cellular expression of fibrotic markers and related ECM proteins. Overall, this study demonstrates that CTGF promotes the development of a fibrogenic phenotype in hMSCs encapsulated within an HA matrix and that the MAPK pathway is a potential target for future therapeutic endeavors towards limiting scar formation in loose connective tissues.

ADAM8 promotes chondrosarcoma cell migration and invasion by activating the NF-κB/MMP-13 signaling axis

ADAM8 is reported to promote extracellular matrix degradation to provide conditions for tumor metastasis. However, the underlying mechanism of ADAM8 in modulating chondrosarcoma (CHS) metastasis remains unclear. We used two human CHS cell lines SW1353 and HCS-2/8 to analyze the expression profiles of ADAM8 in CHS cells compared with the normal chondrocytes. An important proteolytic enzyme MMP-13 was detected as a marker for extracellular matrix degradation in chondrocytes. Then, by silencing or overexpressing ADAM8, the effects on cell migration and invasion in SW1353 and HCS-2/8, and the downstream signal transduction pathways were evaluated. ADAM8 and MMP-13 were highly expressed, and the NF-κB pathway was activated in SW1353 and HCS-2/8 cells. Silencing ADAM8 significantly reduced the ability of cell migration and invasion, and blocked the NF-κB signaling pathway through IκBα and p65 dephosphorylation, leading to reduced NF-κB transcription activity and decreased MMP-13 expression. ADAM8 overexpression promoted these processes, which, however, were reversed by an inhibitor Bay 11-7085. Our data showed a novel regulation mechanism for ADAM8 in promoting CHS migration and invasion by activating the NF-κB/MMP-13 signaling axis. Modulation of their levels may serve as potential targets in the treatment of CHS and even other cartilage diseases.

Differential expression of connective tissue growth factor and hepatocyte growth factor in the vitreous of patients with high myopia versus vitreomacular interface disease

Background

To determine the levels of connective tissue growth factor (CTGF) and hepatocyte growth factor (HGF) in the vitreous of patients with high myopia, in comparison with those with a vitreomacular interface disease (VMID).

Methods

Patients with either high myopia (high myopia group) or a VMID (VMID group) were included in this study. Each of the two groups were further subdivided into two subgroups: group A (high myopia with macular hole), group B (high myopia with macular retinoschisis), group C (idiopathic macular hole), and group D (idiopathic epiretinal membrane). Vitreal specimens were collected during vitrectomy, and enzyme-linked immunosorbent assay was used to quantitatively measure the CTGF and HGF levels in the vitreous.

Results

The average axial length was markedly longer in the high myopia group than in the VMID group. The vitreal CTGF level was significantly higher in the high myopia group than in the VMID group. Subgroup analysis revealed significantly higher vitreal CTGF in group A than in the other three subgroups. The vitreal HGF level was not significantly different between the high myopia and VMID groups, but was significantly higher in group D than in group C in the subgroup analysis. Correlation analysis showed that the vitreal CTGF level was positively correlated with the axial length.

Conclusions

The vitreal CTGF level is elevated in highly myopic eyes and may be related to the pathogenesis of high myopia, whereas increased expression of HGF may be involved in the development of idiopathic epiretinal membrane.

Connective tissue growth factor stimulates osteosarcoma cell migration and induces osteosarcoma metastasis by upregulating VCAM-1 expression

Osteosarcoma is the most common bone malignancy that occurs in the young population. After osteosarcoma cells metastasize to the lung, prognosis is very poor owing to difficulties in early diagnosis and effective treatment. Recently, connective tissue growth factor (CTGF) was reported to be a critical contributor to osteosarcoma metastasis. However, the detailed mechanism associated with CTGF-directed migration in bone neoplasms is still mostly unknown. Through the in vivo and in vitro examination of osteosarcoma cells, this study suggests that VCAM-1 up-regulation and increased osteosarcoma cell migration are involved in this process. Antagonizing αvβ3 integrin inhibited cell migration. Moreover, FAK, PI3K, Akt and NF-κB activation were also shown to be involved in CTGF-mediated osteosarcoma metastasis. Taken together, CTGF promotes VCAM-1 production and further induces osteosarcoma metastasis via the αvβ3 integrin/FAK/PI3K/Akt/NF-κB signaling pathway, which could represent a promising clinical target to improve patient outcome.

Effects of connective tissue growth factor on prostate cancer bone metastasis and osteoblast differentiation

Previous studies have demonstrated that connective tissue growth factor (CTGF) is expressed at increased levels in prostate cancer bone metastasis mouse models and patients with prostate cancer which metastasizes to the bone; however, the underlying molecular mechanism(s) remain unknown. The present study investigated the function of CTGF in osteoblast differentiation and its effect on prostate cancer bone metastasis by analyzing CTGF gene expression and transcription at different levels of invasion, metastasis of prostate cancer cells, and the influence of CTGF on proliferation and xenotransplantation. A mouse model demonstrating bone metastasis was used to investigate the function(s) of CTGF in bone metastasis and osteoblast differentiation. Results demonstrated that CTGF expression was increased in association with high bone metastasis in prostate cancer cells, and its expression was significantly decreased in whole cell lysates. CTGF expression in prostate cancer cells with high levels of bone metastasis was increased 1.9-fold compared with prostate cancer cells with low levels of bone metastasis. The expression of CTGF in mesenchymal cells was markedly increased compared with epithelial cells. Results indicated that the increased expression of CTGF does not affect the proliferation of tumor cells and possesses no influence on tumor volume. Control and CTGF plasmids were transfected into RM1 cells and led to 4 and 17% bone lesions, respectively. Increased expression of CTGF significantly enlarged the tumor area in the bone metastatic position compared with the control. Positive areas of alkaline phosphatase were significantly decreased as the concentration of CTGF increased. The results of the present study demonstrated that CTGF promotes prostate carcinoma to metastasize in the bone by dysregulating osteoblast differentiation.

Chondrosarcoma: A Rare Misfortune in Aging Human Cartilage? The Role of Stem and Progenitor Cells in Proliferation, Malignant Degeneration and Therapeutic Resistance

Unlike other malignant bone tumors including osteosarcomas and Ewing sarcomas with a peak incidence in adolescents and young adults, conventional and dedifferentiated chondrosarcomas mainly affect people in the 4th to 7th decade of life. To date, the cell type of chondrosarcoma origin is not clearly defined. However, it seems that mesenchymal stem and progenitor cells (MSPC) in the bone marrow facing a pro-proliferative as well as predominantly chondrogenic differentiation milieu, as is implicated in early stage osteoarthritis (OA) at that age, are the source of chondrosarcoma genesis. But how can MSPC become malignant? Indeed, only one person in 1,000,000 will develop a chondrosarcoma, whereas the incidence of OA is a thousandfold higher. This means a rare coincidence of factors allowing escape from senescence and apoptosis together with induction of angiogenesis and migration is needed to generate a chondrosarcoma. At early stages, chondrosarcomas are still assumed to be an intermediate type of tumor which rarely metastasizes. Unfortunately, advanced stages show a pronounced resistance both against chemo- and radiation-therapy and frequently metastasize. In this review, we elucidate signaling pathways involved in the genesis and therapeutic resistance of chondrosarcomas with a focus on MSPC compared to signaling in articular cartilage (AC).

Kahweol decreases hepatic fibrosis by inhibiting the expression of connective tissue growth factor via the transforming growth factor-beta signaling pathway

Kahweol is a diterpene molecule found in Coffea Arabica beans. Previous studies have shown that coffee reduces liver fibrosis, but it is not clear which component of coffee has the protective effect. In this study, we examined whether kahweol has a protective effect on hepatic fibrosis in vivo and in vitro. Kahweol decreased hepatic fibrosis by inhibiting connective tissue growth factor (CTGF) expression in thioacetamide (TAA)-treated mice. The expression of phospho-Smad3, signal transducer and activator of transcription 3 (STAT3), extracellular signal-regulated kinases (ERK), and c-Jun N-terminal protein kinase (JNK) increased in the livers of TAA-treated mice and decreased in the kahweol-treated group. Kahweol significantly decreased the expression of transforming growth factor beta (TGF-β)-stimulated type I collagen and CTGF expression in vitro. In addition, kahweol significantly decreased the expression of Smad3, STAT3, ERK and JNK, which are involved in the induction of CTGF expression by TGF-β in hepatocytes, but not in HSCs. These results suggest that kahweol may be a new candidate for treatment of liver fibrosis.

Mesenchymal stem cell-derived CCN2 promotes the proliferation, migration and invasion of human tongue squamous cell carcinoma cells

Recent studies have demonstrated that mesenchymal stem cells (MSC) exhibit a tropism to tumors and form the tumor stroma. In addition, we found that MSC can secrete different types of factors. However, the involvement of MSC‐derived factors in human tongue squamous cell carcinoma (TSCC) growth has not been clearly addressed. The CCN family includes multifunctional signaling molecules that affect the initiation and development events of various tumors. In our study, we report that CCN2/connective tissue growth factor (CTGF) was the most highly induced among the CCN family members in MSC that were co‐cultured with TSCC cells. To evaluate the relationship between CCN2 and TSCC growth, we downregulated MSC‐derived CCN2 expression with shRNA targeting CCN2 and found that MSC‐secreted CCN2 promotes TSCC cell proliferation, migration and invasion. We also confirmed that MSC‐derived CCN2 partially accelerated tumor growth in vitro. Taken together, these results suggest that MSC‐derived CCN2 contributes to the promotion of proliferation, migration and invasion of TSCC cells and may be a possible therapy target in the future.

CTGF promotes osteosarcoma angiogenesis by regulating miR-543/angiopoietin 2 signaling

Osteosarcoma is the most common primary solid tumor of bone. It has a high metastatic potential and occurs predominantly in adolescents and young adults. Angiopoietin 2 (Angpt2) is a key regulator in tumor angiogenesis, facilitating tumor growth and metastasis. Connective tissue growth factor (CTGF, also known as CCN2), is a cysteine-rich protein that has been reported to promote metastasis of osteosarcoma. However, the effect of CTGF on Angpt2 regulation and angiogenesis in human osteosarcoma remains largely unknown. We found that overexpression of CTGF in osteosarcoma cells increased Angpt2 production and induced angiogenesis, in vitro and in vivo. Our findings demonstrate that CTGF-enhanced Angpt2 expression and angiogenesis is mediated by the phospholipase C (PLC)/protein kinase C (PKCδ) signaling pathway. Moreover, endogenous microRNA-543 (miR-543) expression was negatively regulated by CTGF via the PLC/PKCδ pathway. We also provide evidence showing clinical significance between CTGF, Angpt2, and miR-543 as well as tumor staging in human osteosarcoma tissue. CTGF may serve as a therapeutic target in the process of osteosarcoma metastasis and angiogenesis.

Cyclic RGD peptides target human trabecular meshwork cells while ameliorating connective tissue growth factor-induced fibrosis

The major risk factor for primary open-angle glaucoma is increased intraocular pressure stemming from elevated outflow resistance in the trabecular meshwork (TM) region. Integrins play a pivotal role in the TM by influencing its biological properties and growth factor signaling. Pathologic changes in the TM are partially mediated by growth factors like connective tissue growth factor (CTGF). Specific targeting of TM cells could play a critical clinical role by increasing the therapeutic efficacy of nanoparticles, e.g. for nonviral gene delivery. Quantum dots with cyclo(RGDfC) covalently immobilized to their surface effectively targeted cultured TM cells and were rapidly and efficiently endocytosed by binding to α_vβ₃ and α_vβ₅ integrins. Compared to the integrin-overexpressing U87-MG cell line, the association of RGD-modified nanoparticles with the TM cells was significantly higher. Binding and uptake into TM cells was receptor-mediated and suppressible with free peptide. Soluble cyclic RGD peptides effectively attenuated CTGF-mediated effects and inhibited CTGF signaling. Due to their antagonism for αvβ3 and αvβ5 integrins, these cyclic RGD pentapeptides effectively ameliorated the CTGF-induced effects and strongly promoted specific nanoparticle association. Thus, cyclic RGD peptides are powerful multifunctional ligands for both addressing nanomaterials to the TM and interfering with pathologic CTGF signaling upon arrival.

Myeloid Zinc Finger 1 (MZF-1) Regulates Expression of the CCN2/CTGF and CCN3/NOV Genes in the Hematopoietic Compartment

Connective Tissue Growth Factor (CCN2/CTGF) and Nephroblastoma Overexpressed (CCN3/NOV) execute key functions within the hematopoietic compartment. Both are abundant in the bone marrow stroma, which is a niche for hematopoiesis and supports marrow function. Roles for 1,25-dihydroxyvitamin D3 (calcitriol) and all-trans retinoic acid in the bone marrow have also been elucidated. Interestingly, some of the annotated roles of these vitamins overlap with established functions of CCN2 and CCN3. Yet, no factor has been identified that unifies these observations. In this study, we report the regulation of the CTGF and NOV genes by Myeloid Zinc Finger-1 (MZF-1), a hematopoietic transcription factor. We show the interaction of MZF-1 with the CTGF and NOV promoters in several cell types. Up-regulation of MZF-1 via calcitriol and vitamin A induces expression of CTGF and NOV, implicating a role for these vitamins in the functions of these two genes. Lastly, knockdown of MZF1 reduces levels of CTGF and NOV. Collectively, our results argue that MZF-1 regulates the CTGF and NOV genes in the hematopoietic compartment, and may be involved in their respective functions in the stroma.

CTGF increases matrix metalloproteinases expression and subsequently promotes tumor metastasis in human osteosarcoma through down-regulating miR-519d

Osteosarcoma, the most common primary malignant bone tumor, shows potent capacity for local invasion and distant metastasis. Connective tissue growth factor (CTGF/CCN2), a secreted protein, binds to integrins, modulates invasive behavior of certain human cancer cells. Effect of CTGF in metastasis of human osteosarcoma is unknown. We found overexpression of CTGF increasing matrix metalloproteinases (MMPs)-2 and MMP-3 expression as well as promoting cell migration. MicroRNA (miRNA) analysis of CTGF-overexpressed osteosarcoma versus control cells probed mechanisms of CTGF-mediated promotion of migration. Among miRNAs regulated by CTGF, miR-519d was most downregulated after CTGF treatment. Co-transfection with miR-519d mimic reversed CTGF-mediated MMPs expression and cell migration. Also, MEK and ERK inhibitors or mutants reduced CTGF-increased cell migration and miR-519d suppression. By contrast, knockdown of CTGF diminished lung metastasis in vivo. Clinical samples indicate CTGF expression as linked with clinical stage and tumor metastasis. Taken together, data show CTGF elevating MMPs expression and subsequently promoting tumor metastasis in human osteosarcoma, down-regulating miR-519d via MEK and ERK pathways, making CTGF a new molecular therapeutic target in osteosarcoma metastasis.

CRIM1, a newfound cancer-related player, regulates the adhesion and migration of lung cancer cells

CRIM1 is a member of the bone morphogenetic protein (BMP) antagonists; however, the role of CRIM1 in controlling cancer cell behavior remains unknown. This study investigated its function in the A549 cell line in vitro. The results show that treating cells with CRIM1 peptide could increase the migration and adhesion of A549. Consistently, silencing the CRIM1 expression decreased the migration and adhesion of A549. Furthermore, the CRIM1 protein expression was increased in A549 which were treated with transforming growth factor beta 1 to induced EMT. However, CRIM1 peptide treatment could increase the expression of N-CAD and E-CAD expression. Finally, overexpression of the oncogene YAP1 resulted in an up-regulation of the CRIM1 expression in A549, suggesting that CRIM1 was a target of the Hippo pathway. These observations provide evidence for the first time that CRIM1 plays a role in cancer cells by enhancing the migration and adhesion and increasing the expression of N-CAD and E-CAD.

Growth differentiation factor-15 (GDF-15) suppresses in vitro angiogenesis through a novel interaction with connective tissue growth factor (CCN2)

Growth differentiation factor-15 (GDF-15) and the CCN family member, connective tissue growth factor (CCN2), are associated with cardiac disease, inflammation, and cancer. The precise role and signaling mechanism for these factors in normal and diseased tissues remains elusive. Here we demonstrate an interaction between GDF-15 and CCN2 using yeast two-hybrid assays and have mapped the domain of interaction to the von Willebrand factor type C domain of CCN2. Biochemical pull down assays using secreted GDF-15 and His-tagged CCN2 produced in PC-3 prostate cancer cells confirmed a direct interaction between these proteins. To investigate the functional consequences of this interaction, in vitro angiogenesis assays were performed. We demonstrate that GDF-15 blocks CCN2-mediated tube formation in human umbilical vein endothelial (HUVEC) cells. To examine the molecular mechanism whereby GDF-15 inhibits CCN2-mediated angiogenesis, activation of αV β3 integrins and focal adhesion kinase (FAK) was examined. CCN2-mediated FAK activation was inhibited by GDF-15 and was accompanied by a decrease in αV β3 integrin clustering in HUVEC cells. These results demonstrate, for the first time, a novel signaling pathway for GDF-15 through interaction with the matricellular signaling molecule CCN2. Furthermore, antagonism of CCN2 mediated angiogenesis by GDF-15 may provide insight into the functional role of GDF-15 in disease states.

Cdc42 and p190RhoGAP activation by CCN2 regulates cell spreading and polarity and induces actin disassembly in migrating keratinocytes

Cell migration requires spatiotemporal integration of signals that regulate cytoskeletal dynamics. In response to a migration-promoting agent, cells begin to polarise and extend protrusions in the direction of migration. These cytoskeletal rearrangements are orchestrated by a variety of proteins, including focal adhesion kinase (FAK) and the Rho family of GTPases. CCN2, also known as connective tissue growth factor, has emerged as a regulator of cell migration but the mechanism by which CCN2 regulates keratinocyte function is not well understood. In this article, we sought to elucidate the basic mechanism of CCN2-induced cell migration in human keratinocytes. Immunohistochemical staining was used to demonstrate that treatment with CCN2 induces a migratory phenotype through actin disassembly, spreading of lamellipodia and re-orientation of the Golgi. In vitro assays were used to show that CCN2-induced cell migration is dependent on FAK, RhoA and Cdc42, but independent of Rac1. CCN2-treated keratinocytes displayed increased Cdc42 activity and decreased RhoA activity up to 12 hours post-treatment, with upregulation of p190RhoGAP. An improved understanding of how CCN2 regulates cell migration may establish the foundation for future therapeutics in fibrotic and neoplastic diseases.

New strategy to control cell migration and metastasis regulated by CCN2/CTGF

Connective tissue growth factor (CTGF)/CCN family member 2 (CCN2) is a CCN family member of matricellular signaling modulators. It has been shown that CCN2/CTGF mediates cell adhesion, aggregation and migration in a large variety of cell types, including vascular endothelial cells, fibroblasts, epithelial cells, aortic smooth muscle and also pluripotent stem cells. Others matricellular proteins are capable of interacting with CCN2/CTGF to mediate its function. Cell migration is a key feature for tumor cell invasion and metastasis. CCN2/CTGF seems to be a prognostic marker for cancer. In addition, here we intend to discuss recent discoveries and a new strategy to develop therapies against CCN2/CTGF, in order to treat cancer metastasis.

Genetics of breast cancer bone metastasis: a sequential multistep pattern

Bone metastasis accounts for the vast majority of breast cancer (BC) metastases, and is related to a high rate of morbidity and mortality. A number of seminal studies have uncovered gene expression signatures involved in BC development and bone metastasis; each of them points at a distinct step of the 'invasion-metastasis cascade'. In this review, we provide most recently discovered functions of sets of genes that are selected from widely accepted gene signatures that are implicate in BC progression and bone metastasis. We propose a possible sequential pattern of gene expression that may lead a benign primary breast tumor to get aggressiveness and progress toward bone metastasis. A panel of genes which primarily deal with features like DNA replication, survival, proliferation, then, angiogenesis, migration, and invasion has been identified. TGF-β, FGF, NFκB, WNT, PI3K, and JAK-STAT signaling pathways, as the key pathways involved in breast cancer development and metastasis, are evidently regulated by several genes in all three signatures. Epithelial to mesenchymal transition that is also an important mechanism in cancer stem cell generation and metastasis is evidently regulated by these genes. This review provides a comprehensive insight regarding breast cancer bone metastasis that may lead to a better understanding of the disease and take step toward better treatments.

The CCN family proteins: modulators of bone development and novel targets in bone-associated tumors

The CCN family of proteins is composed of six extracellular matrix-associated proteins that play crucial roles in skeletal development, wound healing, fibrosis, and cancer. Members of the CCN family share four conserved cysteine-rich modular domains that trigger signal transduction in cell adhesion, migration, proliferation, differentiation, and survival through direct binding to specific integrin receptors and heparan sulfate proteoglycans. In the present review, we discuss the roles of the CCN family proteins in regulating resident cells of the bone microenvironment. In vertebrate development, the CCN family plays a critical role in osteo/chondrogenesis and vasculo/angiogenesis. These effects are regulated through signaling via integrins, bone morphogenetic protein, vascular endothelial growth factor, Wnt, and Notch via direct binding to CCN family proteins. Due to the important roles of CCN family proteins in skeletal development, abnormal expression of CCN proteins is related to the tumorigenesis of primary bone tumors such as osteosarcoma, Ewing sarcoma, and chondrosarcoma. Additionally, emerging studies have suggested that CCN proteins may affect progression of secondary metastatic bone tumors by moderating the bone microenvironment. CCN proteins could therefore serve as potential therapeutic targets for drug development against primary and metastatic bone tumors.

Novel strategies for the treatment of chondrosarcomas: targeting integrins

Chondrosarcomas are a heterogeneous group of malignant bone tumors that are characterized by the production of cartilaginous extracellular matrix. They are the second most frequently occurring type of bone malignancy. Surgical resection remains the primary mode of treatment for chondrosarcomas, since conventional chemotherapy and radiotherapy are largely ineffective. Treatment of patients with high-grade chondrosarcomas is particularly challenging, owing to the lack of effective adjuvant therapies. Integrins are cell surface adhesion molecules that regulate a variety of cellular functions. They have been implicated in the initiation, progression, and metastasis of solid tumors. Deregulation of integrin expression and/or signaling has been identified in many chondrosarcomas. Therefore, the development of new drugs that can selectively target regulators of integrin gene expression and ligand-integrin signaling might hold great promise for the treatment of these cancers. In this review, we provide an overview of the current understanding of how growth factors, chemokines/cytokines, and other inflammation-related molecules can control the expression of specific integrins to promote cell migration. We also review the roles of specific subtypes of integrins and their signaling mechanisms, and discuss how these might be involved in tumor growth and metastasis. Finally, novel therapeutic strategies for targeting these molecules will be discussed.

Cardiac stem cells with electrical stimulation improve ischaemic heart function through regulation of connective tissue growth factor and miR-378

AIMS

In this study, we investigated whether pre-conditioning (PC) by electrical stimulation (EleS) induces cytoprotective effect on cardiac stem cells (CSCs) and determined its underlying molecular mechanisms.

METHODS AND RESULTS

Sca-1(+) CSCs were isolated from male C57BL6 mice (12 weeks) hearts. PC of CSCs with EleS ((EleS)CSCs) was carried out for 3 h at 1.5 V followed by exposure to 300 µM H2O2 for 5 h. Cytoprotective effects and cell adhesion ability were significantly increased by EleS as evaluated by transferase-mediated dUTP nick-end labelling (TUNEL), lactate dehydrogenase (LDH) release assay, and adhesion assay. EleS increased phosphorylation of AKT, focal adhesion kinase (FAK), and glycogen synthase kinase (GSK3β), as well as decreased caspase-3 cleavage. Interestingly, inhibition of AKT or FAK abolished the pro-survival effects of EleS. We found that connective tissue growth factor (Ctgf) was responsible for EleS-induced CSC survival and adhesion.The survival rate of (EleS)CSCs after transplantation in the infarcted myocardium was significantly increased together with improvement in cardiac function. Importantly, knockdown of Ctgf abolished EleS-induced cytoprotective effects and recovery of cardiac function. Furthermore, we identified miR-378 as a potential Ctgf regulator in (EleS)CSCs.

CONCLUSION

EleS enhanced CSC survival in vitro and in vivo as well as functional recovery of the ischaemic heart through an AKT/FAK/CTGF signalling pathway. It is suggested that Ctgf and miR-378 are novel therapeutic targets for stem cell-based therapy.

AMP-activated protein kinase activation mediates CCL3-induced cell migration and matrix metalloproteinase-2 expression in human chondrosarcoma

Chemokine (C-C motif) ligand 3 (CCL3), also known as macrophage inflammatory protein-1α, is a cytokine involved in inflammation and activation of polymorphonuclear leukocytes. CCL3 has been detected in infiltrating cells and tumor cells. Chondrosarcoma is a highly malignant tumor that causes distant metastasis. However, the effect of CCL3 on human chondrosarcoma metastasis is still unknown. Here, we found that CCL3 increased cellular migration and expression of matrix metalloproteinase (MMP)-2 in human chondrosarcoma cells. Pre-treatment of cells with the MMP-2 inhibitor or transfection with MMP-2 specific siRNA abolished CCL3-induced cell migration. CCL3 has been reported to exert its effects through activation of its specific receptor, CC chemokine receptor 5 (CCR5). The CCR5 and AMP-activated protein kinase (AMPK) inhibitor or siRNA also attenuated CCL3-upregulated cell motility and MMP-2 expression. CCL3-induced expression of MMP-2 and migration were also inhibited by specific inhibitors, and inactive mutants of AMPK, p38 mitogen activated protein kinase (p38 or p38-MAPK), and nuclear factor κB (NF-κB) cascades. On the other hand, CCL3 treatment demonstrably activated AMPK, p38, and NF-κB signaling pathways. Furthermore, the expression levels of CCL3, CCR5, and MMP-2 were correlated in human chondrosarcoma specimens. Taken together, our results indicate that CCL3 enhances the migratory ability of human chondrosarcoma cells by increasing MMP-2 expression via the CCR5, AMPK, p38, and NF-κB pathways.

CCN2 is transiently expressed by keratinocytes during re-epithelialization and regulates keratinocyte migration in vitro by the ras-MEK-ERK signaling pathway

BACKGROUND

CCN2 (previously known as connective tissue growth factor) is a multifunctional matricellular protein that has numerous effects on cell life and cell interactions with the connective tissue. Although the importance of CCN2 for the fibrotic process in wound healing has been well studied, the involvement of CCN2 in keratinocyte function has not yet been explored. Therefore, the aim of the present study was to investigate the role of CCN2 in the epidermis during wound healing.

MATERIALS AND METHODS

Immunohistochemistry was done on sections from full-thickness porcine wounds. The effect of CCN2 on the migration of cultured human keratinocytes exposed to scratch wounds, the effect on phosphorylation of extracellular signal-related kinases (ERK), and the effect of adding inhibitors to the ERK/mitogen-activated protein kinase pathway to human keratinocytes were studied.

RESULTS

The CCN2 protein was transiently expressed in vivo at the leading keratinocyte edge during re-epithelialization of full-thickness porcine wounds. In vitro, exogenous addition of CCN2 to human keratinocyte cultures regulated keratinocyte migration and resulted in phosphorylation of ERK. The addition of inhibitors of ERK/mitogen-activated protein kinase counteracted the effect of CCN2 on migration.

CONCLUSIONS

CCN2 was transiently expressed at the leading keratinocyte edge in vivo. The biologic importance of this was supported in vitro, because CCN2 regulated human keratinocyte migration through activation of the Ras-mitogen-activated protein kinase kinase-ERK signal transduction pathway.

CCN2/CTGF is required for matrix organization and to protect growth plate chondrocytes from cellular stress

CCN2 (connective tissue growth factor (CTGF/CCN2)) is a matricellular protein that utilizes integrins to regulate cell proliferation, migration and survival. The loss of CCN2 leads to perinatal lethality resulting from a severe chondrodysplasia. Upon closer inspection of Ccn2 mutant mice, we observed defects in extracellular matrix (ECM) organization and hypothesized that the severe chondrodysplasia caused by loss of CCN2 might be associated with defective chondrocyte survival. Ccn2 mutant growth plate chondrocytes exhibited enlarged endoplasmic reticula (ER), suggesting cellular stress. Immunofluorescence analysis confirmed elevated stress in Ccn2 mutants, with reduced stress observed in Ccn2 overexpressing transgenic mice. In vitro studies revealed that Ccn2 is a stress responsive gene in chondrocytes. The elevated stress observed in Ccn2−/− chondrocytes is direct and mediated in part through integrin α5. The expression of the survival marker NFκB and components of the autophagy pathway were decreased in Ccn2 mutant growth plates, suggesting that CCN2 may be involved in mediating chondrocyte survival. These data demonstrate that absence of a matricellular protein can result in increased cellular stress and highlight a novel protective role for CCN2 in chondrocyte survival. The severe chondrodysplasia caused by the loss of CCN2 may be due to increased chondrocyte stress and defective activation of autophagy pathways, leading to decreased cellular survival. These effects may be mediated through nuclear factor κB (NFκB) as part of a CCN2/integrin/NFκB signaling cascade.

Induction of thoracic aortic remodeling by endothelial-specific deletion of microRNA-21 in mice

MicroRNAs (miRs) are known to have an important role in modulating vascular biology. MiR21 was found to be involved in the pathogenesis of proliferative vascular disease. The role of miR21 in endothelial cells (ECs) has well studied in vitro, but the study in vivo remains to be elucidated. In this study, miR21 endothelial-specific knockout mice were generated by Cre/LoxP system. Compared with wild-type mice, the miR21 deletion in ECs resulted in structural and functional remodeling of aorta significantly, such as diastolic pressure dropping, maximal tension depression, endothelium-dependent relaxation impairment, an increase of opening angles and wall-thickness/inner diameter ratio, and compliance decrease, in the miR21 endothelial-specific knockout mice. Furthermore, the miR21 deletion in ECs induced down-regulation of collagen I, collagen III and elastin mRNA and proteins, as well as up-regulation of Smad7 and down-regulation of Smad2/5 in the aorta of miR21 endothelial-specific knockout mice. CTGF and downstream MMP/TIMP changes were also identified to mediate vascular remodeling. The results showed that miR21 is identified as a critical molecule to modulate vascular remodeling, which will help to understand the role of miR21 in vascular biology and the pathogenesis of vascular diseases.

The role of ERK and JNK signaling in connective tissue growth factor induced extracellular matrix protein production and scar formation

CCN2 plays an important role in the pathogenesis of hypertrophic scars (HTSs). Although CCN2 is involved in many fibroproliferative events, the CCN2 induction signaling pathway in HTSs is yet to be elucidated. Here, we first investigated the effect of the mitogen-activated protein kinases (MAPKs) on CCN2-induced α-smooth muscle actin (α-SMA) and collagen I expression in human HTS fibroblasts (HTSFs). Then, we established HTSs in a rabbit ear model and determined the effect of MAPKs on the pathogenesis of HTSs. MAPK pathways were activated by CCN2 in HTSFs. Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) inhibitors significantly inhibited CCN2-induced expression of α-SMA and collagen I in HTSFs. In the rabbit ear model of the HTS, JNK and ERK inhibitors significantly improved the architecture of the rabbit ear scar and reduced scar formation on the rabbit ear. Our results indicate that ERK and JNK mediate collagen I expression and scarring of the rabbit ear, and may be considered for specific drug therapy targets for HTSs.

MicroRNA-145 is downregulated in glial tumors and regulates glioma cell migration by targeting connective tissue growth factor

Glioblastomas (GBM), the most common and aggressive type of malignant glioma, are characterized by increased invasion into the surrounding brain tissues. Despite intensive therapeutic strategies, the median survival of GBM patients has remained dismal over the last decades. In this study we examined the expression of miR-145 in glial tumors and its function in glioma cells. Using TCGA analysis and real-time PCR we found that the expression of miR-145/143 cluster was downregulated in astrocytic tumors compared to normal brain specimens and in glioma cells and glioma stem cells (GSCs) compared to normal astrocytes and neural stem cells. Moreover, the low expression of both miR-145 and miR-143 in GBM was correlated with poor patient prognosis. Transfection of glioma cells with miR-145 mimic or transduction with a lentivirus vector expressing pre-miR 145 significantly decreased the migration and invasion of glioma cells. We identified connective tissue growth factor (CTGF) as a novel target of miR-145 in glioma cells; transfection of the cells with this miRNA decreased the expression of CTGF as determined by Western blot analysis and the expression of its 3′-UTR fused to luciferase. Overexpression of a CTGF plasmid lacking the 3′-UTR and administration of recombinant CTGF protein abrogated the inhibitory effect of miR-145 on glioma cell migration. Similarly, we found that silencing of CTGF decreased the migration of glioma cells. CTGF silencing also decreased the expression of SPARC, phospho-FAK and FAK and overexpression of SPARC abrogated the inhibitory effect of CTGF silencing on cell migration. These results demonstrate that miR-145 is downregulated in glial tumors and its low expression in GBM predicts poor patient prognosis. In addition miR-145 regulates glioma cell migration by targeting CTGF which downregulates SPARC expression. Therefore, miR-145 is an attractive therapeutic target for anti-invasive treatment of astrocytic tumors.

The tumor suppressor gene ARHI (DIRAS3) inhibits ovarian cancer cell migration through multiple mechanisms

ARHI is an imprinted tumor suppressor gene that is downregulated in > 60% of ovarian cancers, associated with decreased progression-free survival. ARHI encodes a 26 kDa GTPase with homology to Ras. Re-expression of ARHI inhibits ovarian cancer growth, initiates autophagy and induces tumor dormancy. Recent studies have demonstrated that ARHI also plays a particularly important role in ovarian cancer cell migration. Re-expression of ARHI decreases motility of IL-6- and EGF-stimulated SKOv3 and Hey ovarian cancer cells, inhibiting both chemotaxis and haptotaxis. ARHI inhibits cell migration by binding and sequestering STAT3 in the cytoplasm, and preventing STAT3 translocation to the nucleus and localization in focal adhesion complexes. Re-expression of ARHI inhibits FAK (Y397) phosphorylation, disrupts focal adhesions and blocks FAK-mediated RhoA signaling, resulting in decreased levels of GTP-RhoA. Re-expression of ARHI disrupts formation of actin stress fibers in a FAK- and RhoA-dependent manner. Recent studies indicate that re-expression of ARHI inhibits expression of β-1 integrin which may also contribute to inhibition of migration, adhesion and invasion.

CTGF increases IL-6 expression in human synovial fibroblasts through integrin-dependent signaling pathway

Background

Connective tissue growth factor (CTGF; also known as CCN2) is an inflammatory mediator, and shows elevated levels in regions of severe injury and inflammatory diseases. CTGF is abundantly expressed in osteoarthritis (OA). However, the relationship between CTGF and IL-6 in OA synovial fibroblasts (OASFs) is mostly unknown.

Methodology/Principal Findings

OASFs showed significant expression of CTGF, and expression was higher than in normal SFs. OASFs stimulation with CTGF induced concentration-dependent increases in IL-6 expression. CTGF mediated IL-6 production was attenuated by αvβ5 integrin neutralized antibody and apoptosis signal-regulating kinase 1 (ASK1) shRNA. Pretreatment with p38 inhibitor (SB203580), JNK inhibitor (SP600125), AP-1 inhibitors (Curcumin and Tanshinone IIA), and NF-κB inhibitors (PDTC and TPCK) also inhibited the potentiating action of CTGF. CTGF-mediated increase of NF-κB and AP-1 luciferase activity was inhibited by SB203580 and SP600125 or ASK1 shRNA or p38 and JNK mutant.

Conclusions/Significance

Our results suggest that CTGF increased IL-6 production in OASFs via the αvβ5 integrin, ASK1, p38/JNK, and AP-1/NF-κB signaling pathways.

Adenoviral gene transfer of endothelin-1 in the lung induces pulmonary fibrosis through the activation of focal adhesion kinase

Endothelin-1 (ET-1) has been implicated in the development of pulmonary fibrosis, based on its capacity in vitro to promote extracellular matrix (ECM) production and contraction, and on studies showing elevated expression of ET-1 and its receptors in patients with pulmonary fibrosis. However, the in vivo fibrogenic effect of ET-1 is not well characterized. We used the adenoviral-mediated gene transfer of ET-1 to overexpress ET-1 transiently in murine lungs by intratracheal administration. An increased expression of ET-1 for 3 to 10 days after injection resulted in a moderate but reversible fibrotic response, peaking on Day 14 after infection and characterized by the deposition of ECM components, myofibroblast formation, and a significant inflammatory infiltrate, mainly in the peribronchiolar/perivascular region. Adenoviral-mediated ET-1 overexpression activated focal adhesion kinase (FAK) both in vitro, using primary murine lung fibroblasts, and in vivo, intratracheally administered in the lungs of mice. The inhibition of FAK with the compound PF-562,271 prevented ET-1-mediated collagen deposition and myofibroblast formation, thereby preventing the development of lung fibrosis. In conclusion, we demonstrate that the overexpression of ET-1 directly in the lungs of mice can initiate a fibrogenic response characterized by increased ECM deposition and myofibroblast formation, and that this effect of ET-1 can be prevented by inhibition of FAK. Our data suggest that the ET-1/FAK axis may contribute importantly to the pathogenesis of fibrotic disorders, and highlight FAK as a potential therapeutic target in these devastating diseases.