Thrombin induces epidermal growth factor receptor transactivation and CCL2 expression in human osteoblasts

Beyond Anticoagulation: A Comprehensive Review of Non-Vitamin K Oral Anticoagulants (NOACs) in Inflammation and Protease-Activated Receptor Signaling

Non-vitamin K oral anticoagulants (NOACs) have revolutionized anticoagulant therapy, offering improved safety and efficacy over traditional agents like warfarin. This review comprehensively examines the dual roles of NOACs-apixaban, rivaroxaban, edoxaban, and dabigatran-not only as anticoagulants, but also as modulators of inflammation via protease-activated receptor (PAR) signaling. We highlight the unique pharmacotherapeutic properties of each NOAC, supported by key clinical trials demonstrating their effectiveness in preventing thromboembolic events. Beyond their established anticoagulant roles, emerging research suggests that NOACs influence inflammation through PAR signaling pathways, implicating factors such as factor Xa (FXa) and thrombin in the modulation of inflammatory responses. This review synthesizes current evidence on the anti-inflammatory potential of NOACs, exploring their impact on inflammatory markers and conditions like atherosclerosis and diabetes. By delineating the mechanisms by which NOACs mediate anti-inflammatory effects, this work aims to expand their therapeutic utility, offering new perspectives for managing inflammatory diseases. Our findings underscore the broader clinical implications of NOACs, advocating for their consideration in therapeutic strategies aimed at addressing inflammation-related pathologies. This comprehensive synthesis not only enhances understanding of NOACs' multifaceted roles, but also paves the way for future research and clinical applications in inflammation and cardiovascular health.

MCP-1 controls IL-17-promoted monocyte migration and M1 polarization in osteoarthritis

Osteoarthritis (OA) is a low-grade inflammatory joint illness in which monocytes migrate and infiltrate synovial tissue, differentiating into the pro-inflammatory M1 macrophage phenotype. IL-17 is a proinflammatory mediator principally generated by Th17 cells, which is elevated in OA patients; nevertheless, investigators have yet to elucidate the function of IL-17 in M1 polarization during OA development. Our analysis of clinical tissues and results from the open online dataset discovered that the level of M1 macrophage markers is elevated in human OA tissue samples than in normal tissue. High-throughput screening demonstrated that MCP-1 is a potential candidate factor after IL-17 treatment in OA synovial fibroblasts (OASFs). Immunohistochemistry data revealed that the level of MCP-1 is higher in humans and mice with OA than in normal tissues. IL-17 stimulation facilitates MCP-1-dependent macrophage polarization to the M1 phenotype. It also appears that IL-17 enhances MCP-1 synthesis in human OASFs, enhancing monocyte migration via the JAK and STAT3 signaling cascades. Our findings indicate the IL-17/MCP-1 axis as a novel strategy for the remedy of OA.

NGF facilitates ICAM-1-dependent monocyte adhesion and M1 macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder in which monocytes adhering to synovial tissue differentiate into the pro-inflammatory M1 macrophage phenotype. Nerve growth factors (NGF) referred to as neurotrophins have been associated with inflammatory events; however, researchers have yet to elucidate the role of NGF in RA. Our examination of clinical tissue samples and analysis of data sourced from the Gene Expression Omnibus dataset unveiled elevated expression levels of M1 macrophage markers in human RA synovial tissue samples compared to normal tissue, with no such distinction observed for M2 markers. Furthermore, immunofluorescence data depicted increased expression levels of NGF and M1 macrophages in RA mice in contrast to normal mice. It appears that NGF stimulation facilitates macrophage polarization from the M0 to the M1 phenotype. It also appears that NGF promotes ICAM-1 production in human RA synovial fibroblasts, which enhances monocyte adhesion through the TrkA, MEK/ERK, and AP-1 signaling cascades. Our findings indicate NGF/TrkA axis as a novel target for the treatment of RA.

Protease-Activated Receptors (PARs): Biology and Therapeutic Potential in Perioperative Stroke

Perioperative stroke is a devastating complication that occurs during surgery or within 30 days following the surgical procedure. Its prevalence ranges from 0.08 to 10% although it is most likely an underestimation, as sedatives and narcotics can substantially mask symptomatology and clinical presentation. Understanding the underlying pathophysiology and identifying potential therapeutic targets are of paramount importance. Protease-activated receptors (PARs), a unique family of G-protein-coupled receptors, are widely expressed throughout the human body and play essential roles in various physiological and pathological processes. This review elucidates the biology and significance of PARs, outlining their diverse functions in health and disease, and their intricate involvement in cerebrovascular (patho)physiology and neuroprotection. PARs exhibit a dual role in cerebral ischemia, which underscores their potential as therapeutic targets to mitigate the devastating effects of stroke in surgical patients.

Thrombin-Induced COX-2 Expression and PGE2 Synthesis in Human Tracheal Smooth Muscle Cells: Role of PKCδ/Pyk2-Dependent AP-1 Pathway Modulation

In this study, we confirmed that thrombin significantly increases the production of COX-2 and PGE2 in human tracheal smooth muscle cells (HTSMCs), leading to inflammation in the airways and lungs. These molecules are well-known contributors to various inflammatory diseases. Here, we investigated in detail the involved signaling pathways using specific inhibitors and small interfering RNAs (siRNAs). Our results demonstrated that inhibitors targeting proteins such as protein kinase C (PKC)δ, proline-rich tyrosine kinase 2 (Pyk2), c-Src, epidermal growth factor receptor (EGFR), phosphatidylinositol 3-kinase (PI3K), or activator protein-1 (AP-1) effectively reduced thrombin-induced COX-2 and PGE2 production. Additionally, transfection with siRNAs against PKCδ, Pyk2, c-Src, EGFR, protein kinase B (Akt), or c-Jun mitigated these responses. Furthermore, our observations revealed that thrombin stimulated the phosphorylation of key components of the signaling cascade, including PKCδ, Pyk2, c-Src, EGFR, Akt, and c-Jun. Thrombin activated COX-2 promoter activity through AP-1 activation, a process that was disrupted by a point-mutated AP-1 site within the COX-2 promoter. Finally, resveratrol (one of the most researched natural polyphenols) was found to effectively inhibit thrombin-induced COX-2 expression and PGE2 release in HTSMCs through blocking the activation of Pyk2, c-Src, EGFR, Akt, and c-Jun. In summary, our findings demonstrate that thrombin-induced COX-2 and PGE2 generation involves a PKCδ/Pyk2/c-Src/EGFR/PI3K/Akt-dependent AP-1 activation pathway. This study also suggests the potential use of resveratrol as an intervention for managing airway inflammation.

Genetic and Functional Effects of Adiponectin in Type 2 Diabetes Mellitus Development

Diabetes mellitus (DM) is a common chronic metabolic disease, and the C57BLKsJ-db/db mice are good animal models for type 2 diabetes mellitus (T2DM). In this study, Western blotting and immunohistochemistry (IHC) were employed to examine the protein expression of adiponectin in the liver tissues of T2DM mice with different disease courses (4, 16, and 32 weeks). Adiponectin expression reduced in the liver tissues of T2DM mice in different disease courses. The genotypic and allelic frequencies of the adiponectin gene rs1063538 and rs2241766 single nucleotide polymorphisms (SNPs) in a Taiwanese population (570 T2DM patients and 1700 controls) were investigated. Based on the genetic distribution of the rs2241766 locus, the distribution frequency of the T allele in the T2DM group (72.8%) was higher than in the control group (68.8%). Individuals carrying the G allele had a 0.82-fold greater risk of developing T2DM than individuals carrying the T allele. Differences were evident in the genotypic and allelic distributions (p < 0.05). Enzyme-linked immunosorbent assay (ELISA) was used to measure changes in serum adiponectin protein concentrations in the healthy population and in patients with T2DM. Serum adiponectin concentration in patients with T2DM was lower than in the control group. In summary, adiponectin was determined to be a T2DM susceptibility gene and may be involved in T2DM progression.

S1P Increases VEGF Production in Osteoblasts and Facilitates Endothelial Progenitor Cell Angiogenesis by Inhibiting miR-16-5p Expression via the c-Src/FAK Signaling Pathway in Rheumatoid Arthritis

Angiogenesis is a critical process in the formation of new capillaries and a key participant in rheumatoid arthritis (RA) pathogenesis. Vascular endothelial growth factor (VEGF) stimulation of endothelial progenitor cells (EPCs) facilitates angiogenesis and the progression of RA. Phosphorylation of sphingosine kinase 1 (SphK1) produces sphingosine-1-phosphate (S1P), which increases inflammatory cytokine production, although the role of S1P in RA angiogenesis is unclear. In this study, we evaluated the impact of S1P treatment on VEGF-dependent angiogenesis in osteoblast-like cells (MG-63 cells) and the significance of SphK1 short hairpin RNA (shRNA) on S1P production in an in vivo model. We found significantly higher levels of S1P and VEGF expression in synovial fluid from RA patients compared with those with osteoarthritis by ELISA analysis. Treating MG-63 cells with S1P increased VEGF production, while focal adhesion kinase (FAK) and Src siRNAs and inhibitors decreased VEGF production in S1P-treated MG-63 cells. Conditioned medium from S1P-treated osteoblasts significantly increased EPC tube formation and migration by inhibiting miR-16-5p synthesis via proto-oncogene tyrosine-protein kinase src (c-Src) and FAK signaling in chick chorioallantoic membrane (CAM) and Matrigel plug assays. Infection with SphK1 shRNA reduced angiogenesis, articular swelling and cartilage erosion in the ankle joints of mice with collagen-induced arthritis (CIA). S1P appears to have therapeutic potential in RA treatment.

S1P facilitates IL-1β production in osteoblasts via the JAK and STAT3 signaling pathways

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease, in which the immune system attacks synovial joint tissues. Interleukin (IL)-1β is a critical proinflammatory cytokine in RA progression. Sphingosine-1-phosphate (S1P), a platelet-derived lysophospholipid mediator, reportedly regulates osteoimmunology. Here, we investigated how S1P mediates IL-1β expression in osteoblasts. Our analysis of records from the Gene Expression Omnibus (GEO) database demonstrate higher levels of IL-1β in patients with RA compared with those with osteoarthritis. Stimulation of osteoblasts with S1P concentration dependently increased mRNA and protein expression of IL-1β. Elevations in IL-1β mRNA expression induced by S1P were reduced by the small interfering RNA (siRNA) against the S1P₁ receptor. S1P also augmented JAK and STAT3 molecular cascades. We also found that JAK and STAT3 inhibitors and their siRNAs antagonized S1P-promoted IL-1β expression. Our results indicate that S1P promotes the expression of IL-1β in osteoblasts via the S1P₁ receptor and the JAK and STAT3 signaling pathways.

S1P promotes IL-6 expression in osteoblasts through the PI3K, MEK/ERK and NF-κB signaling pathways

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease, in which the immune system attacks joint tissue. Interleukin (IL)-6 is a key proinflammatory cytokine in RA progression. Sphingosine-1-phosphate (S1P), a platelet-derived lysophospholipid mediator, reportedly regulates osteoimmunology. Here, we examined the effects of S1P on IL-6 expression in osteoblasts. Our results and records from the Gene Expression Omnibus (GEO) database demonstrate higher levels of IL-6 in patients with RA compared with those with osteoarthritis. Stimulation of osteoblasts with S1P increased mRNA and protein expression of IL-6. PI3K, MEK, ERK and NF-κB inhibitors and their small interfering RNAs (siRNAs) reduced S1P-promoted IL-6 expression. S1P also facilitated PI3K, MEK/ERK and NF-κB signaling cascades. Our results indicate that S1P promotes the expression of IL-6 in osteoblasts via the PI3K, MEK/ERK and NF-κB signaling pathways.

Antizyme inhibitor 1 genetic polymorphisms associated with diabetic patients validated in the livers of diabetic mice

Diabetes mellitus (DM) is a complex disease caused by absolute or relative insulin deficiency. The C57BLKsJ-db/db mouse model is a useful animal model for studying type 2 DM (T2DM). The present study investigated the association between an antizyme inhibitor 1 (AZIN1) gene polymorphism (rs1062048) and T2DM susceptibility in 2,270 Taiwanese individuals (570 patients with T2DM and 1,700 controls). Additionally, the present study investigated AZIN1 gene and protein expression in the liver tissues of mice in three age groups (4, 16 and 32 weeks) through reverse transcription-quantitative PCR, western blotting and immunohistochemistry. The data indicated that the genotype frequency distribution of the rs1062048 single-nucleotide polymorphism differed significantly between the patients with T2DM and controls (P<0.05). Furthermore, gene and protein expression levels of AZIN1 were significantly lower in early stage and late stage T2DM mouse liver samples than in control samples. Overall, the data suggested that AZIN1 expression is involved in T2DM development.

Mechanisms of PAR-1 mediated kinase receptor transactivation: Smad linker region phosphorylation

Protease activated receptors (PARs) transactivate both epidermal growth factor receptors (EGFR) and transforming growth factor (TGF)-β receptors (TGFBR1) in vascular smooth muscle leading to the increased expression of genes (CHST11 and CHSY1) which are rate limiting for the enzymes that mediate hyperelongation of glycosaminoglycan (GAG) chains on the lipid-binding proteoglycan, biglycan. This is an excellent model to investigate mechanisms of transactivation as the processes are biochemically distinct. EGFR transactivation is dependent on the classical matrix metalloprotease (MMP) based triple membrane bypass mechanism and TGFBR1 transactivation is dependent on Rho/ROCK signalling and integrins. We have shown that all kinase receptor signalling is targeted towards phosphorylation of the linker region of the transcription factor, Smad2. We investigated the mechanisms of thrombin mediated kinase receptor transactivation signalling using anti-phospho antibodies and Western blotting and gene expression by RT-PCR. Thrombin stimulation of phospho-Smad2 (Ser 245/250/255) and of phospho-Smad2(Thr220) via EGFR transactivation commences quickly and extends out to at least 4 h whereas transactivation via TGFBR1 is delayed for 120 min but also persists for at least 4 h. Signalling of thrombin stimulated Smad linker region phosphorylation is approximately equally inhibited by the MMP inhibitor, GM6001 and the ROCK inhibitor, Y27632, and similarly expression of CHST11 and CHSY1 is approximately equally inhibited by GM6001 and Y27632. The data establishes Smad linker region phosphorylation as a central target of all transactivation signalling of GAG gene expression and thus an upstream kinase may be a target to prevent all transactivation signalling and its pathophysiological consequences.

Glucose suppresses IL-1β-induced MMP-1 expression through the FAK, MEK, ERK, and AP-1 signaling pathways

Osteoarthritis (OA) commonly affects the synovial joint and is characterized by degradation of articular cartilage. Increased matrix metalloproteinase (MMP) activity plays a major role in this degradation. Dextrose (D-glucose) prolotherapy has shown promising activity in the treatment of different musculoskeletal disorders, including OA. However, little is known about the role of glucose on MMP inhibition in OA therapy. We found that stimulating chondrocytes with the proinflammatory cytokine interleukin-1β (IL-1β) increased the expression of MMP-1, MMP-3, and MMP-13. Glucose reduced this increase in MMP-1 expression, but had no effect upon MMP-3 or MMP-13 expression. Analyses using a focal adhesion kinase (FAK) inhibitor, MEK inhibitors (U0126 and PD98059), an ERK inhibitor, AP-1 inhibitors (curcumin and tanshinone), or siRNAs demonstrated that the FAK, MEK, ERK, and AP-1 pathways mediate IL-1β-induced increases in MMP-1 expression. Glucose antagonized IL-1β-promoted phosphorylation of FAK, MEK, ERK, and c-Jun. Thus, glucose decreased IL-1β-induced MMP-1 expression through the FAK, MEK, ERK, and AP-1 signaling cascades. These findings may provide a better understanding of the mechanisms of prolotherapy on inhibiting MMP expression.

Effect of Thrombin-Induced MCP-1 and MMP-3 Production Via PAR1 Expression in Murine Intervertebral Discs

Structural changes in nucleus pulposus cells induce intervertebral disc (IVD) degeneration as a consequence of cytokine generation, biochemical products, and changes in the local environment. We have previously shown that inflammatory cytokines induce murine IVD (mIVD) angiogenesis and macrophage migration. Although the physiological roles of thrombin, a known proinflammatory factor, are documented, its relationship to IVD degeneration remains largely unexplored. Thrombin mediates cellular responses via the activation of protease-activated receptors such as PAR1 which has been studied in numerous cell types, but not extensively in IVD cells. This study was designed to investigate the endogenous expression of thrombin, tissue factor, and PAR1 in cultured coccygeal mIVDs. Thrombin exclusively induced MCP-1 via the MAPK-ERK and PI3K-AKT pathways. MCP-1 produced by mIVDs induced macrophage migration and thrombin treatment increased MMP-3 production to induce mIVD degeneration. These effects of thrombin on mIVDs were abrogated by a PAR1 inhibitor and suggest that thrombin may be a novel factor capable of stimulating cytokine activity implicated in the regulation several aspects of mIVDs. Mechanisms governing mIVDs, which are regulated by thrombin/PAR1 signaling, require elucidation if our understanding of IVD degenerative mechanisms is to advance.

Basic fibroblast growth factor promotes VEGF-C-dependent lymphangiogenesis via inhibition of miR-381 in human chondrosarcoma cells

A chondrosarcoma is a common, primary malignant bone tumor that can grow to destroy the bone, produce fractures and develop soft tissue masses. Left untreated, chondrosarcomas metastasize through the vascular system to the lungs and ultimately lead to large metastatic deposits of the malignant cartilage taking over lung volume and function. Vascular endothelial growth factor (VEGF)-C has been implicated in tumor-induced lymphangiogenesis and elevated expression of VEGF-C has been found to correlate with cancer metastasis. bFGF (basic fibroblast growth factor), a secreted cytokine, regulates biological activity, including angiogenesis and metastasis. We have previously reported on the important role of bFGF in angiogenesis in chondrosarcomas. However, the effect of bFGF in VEGF-C regulation and lymphangiogenesis in chondrosarcomas is poorly understood. In this investigation, we demonstrate a correlation exists between bFGF and VEGF-C in tissue specimens from patients with chondrosarcomas. To examine the lymphangiogenic effect of bFGF, we used human lymphatic endothelial cells (LECs) to mimic lymphatic vessel formation. We found that bFGF-treated chondrosarcomas promoted LEC tube formation and cell migration. In addition, bFGF knockdown inhibited lymphangiogenesis in vitro and in vivo. We also found that bFGF-induced VEGF-C is mediated by the platelet-derived growth factor receptor (PDGFR) and c-Src signaling pathway. Furthermore, bFGF inhibited microRNA-381 expression via the PDGFR and c-Src cascade. Our study is the first to describe the mechanism of bFGF-promoted lymphangiogenesis by upregulating VEGF-C expression in chondrosarcomas. Thus, bFGF could serve as a therapeutic target in chondrosarcoma metastasis and lymphangiogenesis.

Visfatin Promotes IL-6 and TNF-α Production in Human Synovial Fibroblasts by Repressing miR-199a-5p through ERK, p38 and JNK Signaling Pathways

Osteoarthritis (OA), an inflammatory form of arthritis, is characterized by synovial inflammation and cartilage destruction largely influenced by two key proinflammatory cytokines-interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α). Notably, levels of visfatin (a proinflammatory adipokine) are elevated in patients with OA, although the relationship of visfatin to IL-6 and TNF-α expression in OA pathogenesis has been unclear. In this study, visfatin enhanced the expression of IL-6 and TNF-α in human OA synovial fibroblasts (OASFs) in a concentration-dependent manner and stimulation of OASFs with visfatin promoted phosphorylation of extracellular-signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK), while ERK, p38, and JNK inhibitors or siRNAs all abolished visfatin-induced increases in IL-6 and TNF-α production. Moreover, transfection with miR-199a-5p mimics reversed visfatin-induced increases in IL-6 and TNF-α production. Furthermore, we also found that visfatin-promoted IL-6 and TNF-α production is mediated via the inhibition of miR-199a-5p expression through the ERK, p38, and JNK signaling pathways. Visfatin may therefore be an appropriate target for drug intervention in OA treatment.

Myostatin Promotes Interleukin-1β Expression in Rheumatoid Arthritis Synovial Fibroblasts through Inhibition of miR-21-5p

Rheumatoid arthritis (RA) is characterized by the infiltration of a number of pro-inflammatory cytokines into synovial fluid and patients with RA often develop joint destruction and deficits in muscle mass. The growth factor myostatin is a key regulator linking muscle mass and bone structure. We sought to determine whether myostatin regulates rheumatoid synovial fibroblast activity and inflammation in RA. We found that levels of myostatin and interleukin (IL)-1β (a key pro-inflammatory cytokine in RA) in synovial fluid from RA patients were overexpressed and positively correlated. In in vitro investigations, we found that myostatin dose-dependently regulated IL-1β expression through the ERK, JNK, and AP-1 signal-transduction pathways. Computational analysis confirmed that miR-21-5p directly targets the expression of the 3′ untranslated region (3′ UTR) of IL-1β. Treatment of cells with myostatin inhibited miR-21-5p expression and miR-21-5p mimic prevented myostatin-induced enhancement of IL-1β expression, showing an inverse correlation between miR-21-5p and IL-1β expression during myostatin treatment. We also found significantly increased paw swelling in an animal model of collagen-induced arthritis (CIA), compared with controls; immunohistochemistry staining revealed substantially higher levels of myostatin and IL-1β expression in CIA tissue. Our evidence indicates that myostatin regulates IL-1β production. Thus, targeting myostatin may represent a potential therapeutic target for RA.

Tanshinone IIA inhibits angiogenesis in human endothelial progenitor cells in vitro and in vivo

Accumulating evidence reports that bone marrow-derived endothelial progenitor cells (EPCs) regulate angiogenesis, postnatal neovascularization and tumor metastasis. It has been suggested that understanding the molecular targets and pharmacological functions of natural products is important for novel drug discovery. Tanshinone IIA is a major diterpene quinone compound isolated from Danshen (Salvia miltiorrhiza) and is widely used in traditional Chinese medicine (TCM). Evidence indicates that tanshinone IIA modulates angiogenic functions in human umbilical vein endothelial cells. However, the anti-angiogenic activity of tanshinone IIA in human EPCs has not been addressed. Here, we report that tanshinone IIA dramatically suppresses vascular endothelial growth factor (VEGF)-promoted migration and tube formation of human EPCs, without cytotoxic effects. We also show that tanshinone IIA markedly inhibits VEGF-induced angiogenesis in the chick embryo chorioallantoic membrane (CAM) model. Importantly, tanshinone IIA significantly attenuated microvessel formation and the expression of EPC-specific markers in the in vivo Matrigel plug assay in mice. Further, we found that tanshinone IIA inhibits EPC angiogenesis through the PLC, Akt and JNK signaling pathways. Our report is the first to reveal that tanshinone IIA reduces EPC angiogenesis both in vitro and in vivo. Tanshinone IIA is a promising natural product worthy of further development for the treatment of cancer and other angiogenesis-related pathologies.

Brain-derived neurotrophic factor promotes VEGF-C-dependent lymphangiogenesis by suppressing miR-624-3p in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignancy of bone, and one of the most difficult bone tumors to diagnose and treat. It is well known that increased levels of vascular endothelial growth factor-C (VEGF-C) promote active tumor lymphangiogenesis and lymphatic tumor spread to regional lymph nodes. Brain-derived neurotrophic factor (BDNF) is known to promote metastasis in human chondrosarcoma cells. Knowing more about the mechanism of BDNF in VEGF-C expression and lymphangiogenesis in human chondrosarcoma would improve our understanding as how to prevent chondrosarcoma angiogenesis and metastasis, which currently lacks effective adjuvant treatment. Here, we found that BDNF expression was at least 2.5-fold higher in the highly migratory JJ012(S10) cell line as compared with the primordial cell line (JJ012). In addition, VEGF-C expression and secretion was markedly increased in JJ012(S10) cells. Conditioned medium from JJ012(S10) cells significantly promoted migration and tube formation of human lymphatic endothelial cells (LECs), whereas knockdown of BDNF attenuated LEC migration and tube formation by suppressing VEGF-C production in JJ012(S10) cells. Mechanistic investigations indicated that BDNF facilitated VEGF-C-dependent lymphangiogenesis through the MEK/ERK/mTOR signaling pathway. We also showed that microRNA (miR)-624-3p expression was negatively regulated by BDNF via the MEK/ERK/mTOR cascade. Importantly, BDNF knockdown profoundly inhibited tumor-associated lymphangiogenesis in vivo. Further analyses identified that BDNF promoted tumor lymphangiogenesis by downregulating miR-624-3p in human chondrosarcoma tissues. In conclusion, this study is the first to reveal the mechanism underlying BDNF-induced lymphangiogenesis. We suggest that BDNF may serve as a promising therapeutic target for the restriction of VEGF-C-mediated tumor lymphangiogenesis and lymphatic metastasis.

YKL-40-Induced Inhibition of miR-590-3p Promotes Interleukin-18 Expression and Angiogenesis of Endothelial Progenitor Cells

YKL-40, also known as human cartilage glycoprotein-39 or chitinase-3-like-1, is a pro-inflammatory protein that is highly expressed in rheumatoid arthritis (RA) patients. Angiogenesis is a critical step in the pathogenesis of RA, promoting the infiltration of inflammatory cells into joints and providing oxygen and nutrients to RA pannus. In this study, we examined the effects of YKL-40 in the production of the pro-inflammatory cytokine interleukin-18 (IL-18), and the stimulation of angiogenesis and accumulation of osteoblasts. We observed that YKL-40 induces IL-18 production in osteoblasts and thereby stimulates angiogenesis of endothelial progenitor cells (EPCs). We found that this process occurs through the suppression of miR-590-3p via the focal adhesion kinase (FAK)/PI3K/Akt signaling pathway. YKL-40 inhibition reduced angiogenesis in in vivo models of angiogenesis: the chick embryo chorioallantoic membrane (CAM) and Matrigel plug models. We report that YKL-40 stimulates IL-18 expression in osteoblasts and facilitates EPC angiogenesis.

Enhancement of CCL2 expression and monocyte migration by CCN1 in osteoblasts through inhibiting miR-518a-5p: implication of rheumatoid arthritis therapy

Cysteine-rich 61 (Cyr61 or CCN1), a secreted protein from the CCN family, is an important proinflammatory cytokine. Migration and infiltration of mononuclear cells to inflammatory sites play a critical role in the pathogenesis of rheumatoid arthritis (RA). Monocyte chemoattractant protein-1 (MCP-1/CCL2) is the key chemokine that regulates migration and infiltration of monocytes. Here, we examined the role of CCN1 in monocyte migration, and CCL2 expression in osteoblasts. We found higher levels of CCN1 and CCL2 in synovial fluid from RA patients compared with levels from non-RA controls. We also found that the CCN1-induced increase in CCL2 expression is mediated by the MAPK signaling pathway and that miR-518a-5p expression was negatively regulated by CCN1 via the MAPK cascade. In contrast, inhibition of CCN1 expression with lentiviral vectors expressing short hairpin RNA ameliorated articular swelling, cartilage erosion, and infiltration of monocytes in the ankle joints of mice with collagen-induced arthritis. Our study describes how CCN1 promotes monocyte migration by upregulating CCL2 expression in osteoblasts in RA disease. CCN1 could serve as a potential target for RA treatment.

Adiponectin promotes VEGF-A-dependent angiogenesis in human chondrosarcoma through PI3K, Akt, mTOR, and HIF-α pathway

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes. On the other hand, angiogenesis is a critical step in tumor growth and metastasis. However, the relationship of adiponectin with vascular endothelial growth factor-A (VEGF-A) expression and angiogenesis in human chondrosarcoma is mostly unknown. In this study we first demonstrated that the expression of adiponectin was correlated with tumor stage of human chondrosarcoma tissues. In addition, we also found that adiponectin increased VEGF-A expression in human chondrosarcoma cells and subsequently induced migration and tube formation in human endothelial progenitor cells (EPCs). Adiponectin promoted VEGF-A expression through adiponectin receptor (AdipoR), phosphoinositide 3 kinase (PI3K), Akt, mammalian target of rapamycin (mTOR), and hypoxia-inducible factor-1α (HIF)-1α signaling cascades. Knockdown of adiponectin decreased VEGF-A expression and also abolished chondrosarcoma conditional medium-mediated tube formation in EPCs in vitro as well as angiogenesis effects in the chick chorioallantoic membrane and Matrigel plug nude mice model in vivo. Therefore, adiponectin is crucial for tumor angiogenesis and growth, which may represent a novel target for anti-angiogenic therapy in human chondrosarcoma.

WISP-1 promotes VEGF-C-dependent lymphangiogenesis by inhibiting miR-300 in human oral squamous cell carcinoma cells

Oral squamous cell carcinoma (OSCC), which accounts for nearly 90% of head and neck cancers, is characterized by a poor prognosis and a low survival rate. Vascular endothelial growth factor-C (VEGF-C) has been implicated in lymphangiogenesis and is correlated with cancer metastasis. WNT1-inducible signaling pathway protein-1 (WISP)-1/CCN4 is an extracellular matrix-related protein that belongs to the CCN family and stimulates many biological functions. Our previous studies showed that WISP-1 plays an important role in OSCC migration and angiogenesis. However, the effect of WISP-1 on VEGF-C regulation and lymphangiogenesis in OSCC is poorly understood. Here, we showed a correlation between WISP-1 and VEGF-C in tissue specimens from patients with OSCC. To examine the lymphangiogenic effect of WISP-1, we used human lymphatic endothelial cells (LECs) to mimic lymphatic vessel formation. The results showed that conditioned media from WISP-1-treated OSCC cells promoted tube formation and cell migration in LECs. We also found that WISP-1-induced VEGF-C is mediated via the integrin αvβ3/integrin-linked kinase (ILK)/Akt signaling pathway. In addition, the expression of microRNA-300 (miR-300) was inhibited by WISP-1 via the integrin αvβ3/ILK/Akt cascade. Collectively, these results reveal the detailed mechanism by which WISP-1 promotes lymphangiogenesis via upregulation of VEGF-C expression in OSCC. Therefore, WISP-1 could serve as therapeutic target to prevent metastasis and lymphangiogenesis in OSCC.

CCN1 Promotes VEGF Production in Osteoblasts and Induces Endothelial Progenitor Cell Angiogenesis by Inhibiting miR-126 Expression in Rheumatoid Arthritis

Angiogenesis is the formation of new capillaries from preexisting vasculature. The perpetuation of angiogenesis plays a critical role in the pathogenesis of various disease states including rheumatoid arthritis (RA). Cysteine-rich 61 (Cyr61 or CCN1) is an important proinflammatory cytokine in RA. Here, we investigated the role of CCN1 in angiogenesis associated with vascular endothelial growth factor (VEGF) production and osteoblasts. We found higher expression of CCN1 and VEGF in synovial fluid from RA patients compared with healthy controls. CCN1 induced VEGF expression in osteoblasts and increased endothelial progenitor cells (EPCs) angiogenesis by inhibiting miR-126 via the protein kinase C-alpha (PKC-α) signaling pathway. CCN1 knockdown inhibited angiogenesis in both in vitro and in vivo models. Inhibition of CCN1 expression with lentiviral vectors expressing short hairpin RNA (shRNA) ameliorated articular swelling, cartilage erosion, and angiogenesis in the ankle joint of mice with collagen-induced arthritis (CIA). Our study is the first to describe how CCN1 promotes VEGF expression in osteoblasts and increased EPCs angiogenesis in RA disease. CCN1 may serve as a potential target for RA treatment. © 2016 American Society for Bone and Mineral Research.

Osteopontin inhibition of miR-129-3p enhances IL-17 expression and monocyte migration in rheumatoid arthritis

BACKGROUND

Osteopontin (OPN) is an important proinflammatory cytokine in rheumatoid arthritis (RA). Levels of OPN have been shown to be significantly correlated with interleukin-17 (IL-17) production and expression of Th17 cells in the synovial fluid of RA patients. Here, we investigated the role of OPN in monocyte migration, IL-17 production and osteoblasts.

METHODS

OPN and IL-17 expression profiles in osteoarthritis (OA) and RA synovial fluid were determined by enzyme-linked immunosorbent assay (ELISA). The expression of the microRNA, miR-129-3p, in osteoblasts was analyzed by real-time quantitative polymerase chain reaction (qPCR). Immunoreactive proteins were spotted by Western blotting. We used the collagen-induced arthritis (CIA) mouse model to investigate the role of OPN in monocyte migration during RA.

RESULTS

OPN and IL-17 expression were higher in RA synovial fluid as compared to OA samples. We also found that OPN promotes IL-17 expression in osteoblasts and thereby enhances monocyte migration via the Syk/PI3K/Akt signaling pathway. miR-129-3p expression was found to be negatively regulated by OPN via the Syk/PI3K/Akt signal cascade. In contrast, lentiviral vectors expressing short hairpin RNA inhibited OPN expression and ameliorated articular swelling, cartilage erosion and monocyte infiltration in the ankle joints of CIA mice.

CONCLUSION

To our knowledge, our study is the first to describe how OPN promotes monocyte migration by upregulating IL-17 expression in osteoblasts in RA disease.

SIGNIFICANCE

These findings indicate that OPN could serve as a potential therapeutic target for the treatment of RA.

Characteristics of resistin in rheumatoid arthritis angiogenesis

Adipokines have been reported to be involved in the regulation of various physiological processes, including the immune response. Rheumatoid arthritis (RA) is an example of a systemic immune disease that causes chronic inflammation of the synovium and bone destruction in the joint. Recent therapeutic strategies based on the understanding of the role of cytokines and cellular mechanisms in RA have improved our understanding of angiogenesis. On the other hand, endogenous endothelial progenitor cells, which are a population isolated from peripheral blood monocytes have recently been identified as a homing target for pro-angiogeneic factor and vessel formation. In this review, we summarize the effects of common adipokines, such as adiponectin, leptin and resistin in RA pathogenesis and discuss other potential mechanisms of relevance for the therapeutic treatment of RA.

Thrombin induced by the extrinsic pathway and PAR-1 regulated inflammation at the site of fracture repair

Thrombin (coagulation factor IIa) is a serine protease encoded by the F2 gene. Pro-thrombin (coagulation factor II) is cut to generate thrombin in the coagulation cascade that results in a reduction of blood loss. Procoagulant states that lead to activation of thrombin are common in bone fracture sites. However, its physiological roles and relationship with osteoblasts in bone fractures are largely unknown. We herein report various effects of thrombin on mouse osteoblastic MC3T3-E1 cells. MC3T3-E1 cells expressed proteinase-activated receptor 1 (PAR1), also known as the coagulation factor II receptor. They also produced monocyte chemoattractant protein (MCP-1), tissue factor (TF), MCSF and IL-6 upon thrombin stimulation through the PI3K-Akt and MEK-Erk1/2 pathways. Furthermore, MCP-1 obtained from thrombin-stimulated MC3T3-E1 cells induced migration by macrophage RAW264 cells. All these effects of thrombin on MC3T3-E1 cells were abolished by the selective non-peptide thrombin receptor inhibitor SCH79797. We also found that thrombin, PAR-1, MCP-1, TF as well as phosphorylated AKT and p42/44 were significantly expressed at the fracture site of mouse femoral bone. Collectively, thrombin/PAR-1 interaction regulated MCP-1, TF, MCSF and IL-6 production by MC3T3-E1 cells. Furthermore, MCP-1 induced RAW264 cell migration. Thrombin may thus be a novel cytokine that regulates several aspects of osteoblast function and fracture healing.

Transactivation of Epidermal Growth Factor Receptor by G Protein-Coupled Receptors: Recent Progress, Challenges and Future Research

Both G protein-coupled receptors (GPCRs) and receptor-tyrosine kinases (RTKs) regulate large signaling networks, control multiple cell functions and are implicated in many diseases including various cancers. Both of them are also the top therapeutic targets for disease treatment. The discovery of the cross-talk between GPCRs and RTKs connects these two vast signaling networks and complicates the already complicated signaling networks that regulate cell signaling and function. In this review, we focus on the transactivation of epidermal growth factor receptor (EGFR), a subfamily of RTKs, by GPCRs. Since the first report of EGFR transactivation by GPCR, significant progress has been made including the elucidation of the mechanisms underlying the transactivation. Here, we first provide a basic picture for GPCR, EGFR and EGFR transactivation by GPCR. We then discuss the progress made in the last five years and finally provided our view of the future challenge and future researches needed to overcome these challenges.

CCL5 promotes VEGF-dependent angiogenesis by down-regulating miR-200b through PI3K/Akt signaling pathway in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignant bone cancer, with potential for local invasion and distant metastasis. Chemokine CCL5 (formerly RANTES) of the CC-chemokine family plays a crucial role in metastasis. Angiogenesis is essential for the cancer metastasis. However, correlation of CCL5 with vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma is still unknown. CCL5-mediated VEGF expression was assessed by qPCR, ELISA, and Western blotting. CCL5-induced angiogenesis was examined by migration and tube formation in endothelial progenitor cells in vitro. CCL5 increased VEGF expression and also promoted chondrosarcoma conditional medium-mediated angiogenesis in vitro and in vivo. Stimulation of chondrosarcoma with CCL5 augmented PI3K and Akt phosphorylation, while PI3K and Akt inhibitor or siRNA abolished CCL5-induced VEGF expression and angiogenesis. We also demonstrated CCL5 inhibiting miR-200b expression and miR-200b mimic reversing the CCL5-enhanced VEGF expression and angiogenesis. Moreover, in chondrosarcoma patients showed the positive correlation between CCL5 and VEGF; negative correlation between CCL5 and miR-200b. Taken together, results demonstrate CCL5 promoting VEGF-dependent angiogenesis in human chondrosarcoma cells by down-regulating miR-200b through PI3K/Akt signaling pathway.

Osteopontin Promotes Oncostatin M Production in Human Osteoblasts: Implication of Rheumatoid Arthritis Therapy

Accumulating evidence indicates that subchondral bone might play an essential role in rheumatoid arthritis (RA). Osteopontin (OPN) induces the production of an important proinflammatory cytokine involved in the pathogenesis of RA. This study evaluated the activation of oncostatin M (OSM) by OPN in human primary osteoblasts to understand RA pathogenesis and characterized the intracellular signaling pathways involved in this activation. Quantitative PCR, ELISA, and Western blot results indicated that stimulation of human primary osteoblasts with OPN induces OSM expression through αvβ3 integrin/c-Src/platelet-derived growth factor receptor transactivation/MEK/ERK. Treatment of osteoblasts with OPN also increased c-Jun phosphorylation, AP-1 luciferase activity, and c-Jun binding to the AP-1 element on the OSM promoter, as demonstrated using chromatin immunoprecipitation assay. Moreover, inhibition of OPN expression using lentiviral-OPN short hairpin RNA resulted in the amelioration of articular swelling, cartilage erosion, and OSM expression in the ankle joint of mice with collagen-induced arthritis as shown using microcomputed tomography and immunohistochemistry staining. Our results imply that OSM expression in osteoblasts increases in response to OPN-induced inflammation in vitro. Finally, lentiviral-OPN short hairpin RNA ameliorates the inflammatory response and bone destruction in mice with collagen-induced arthritis. Therefore, OPN may be a potential therapeutic target for RA.

Osteoblast-derived WNT-induced secreted protein 1 increases VCAM-1 expression and enhances prostate cancer metastasis by down-regulating miR-126

Bone metastases of prostate cancer (PCa) may cause intractable pain. Wnt-induced secreted protein-1 (WISP-1) belongs to the CCN family (CTGF/CYR61/NOV) that plays a key role in bone formation. We found that osteoblast-conditioned medium (OBCM) stimulates migration and vascular cell adhesion molecule-1 (VCAM-1) expression in human PCa (PC3 and DU145) cells. Osteoblast transfection with WISP-1 shRNA reduced OBCM-mediated PCa migration and VCAM-1 expression. Stimulation of PCa with OBCM or WISP-1 elevated focal adhesion kinase (FAK) and p38 phosphorylation. Either FAK and p38 inhibitors or siRNA abolished osteoblast-derived WISP-1-induced migration and VCAM-1 expression. Osteoblast-derived WISP-1 inhibited miR-126 expression. Moreover, miR-216 mimic reversed the WISP-1-enhanced migration and VCAM-1 expression. This study suggests that osteoblast-derived WISP-1 promotes migration and VCAM-1 expression in human PCa cells by down-regulating miR-126 expression via αvβ1 integrin, FAK, and p38 signaling pathways. Thus, WISP-1 may be a new molecular therapeutic target in PCa bone metastasis.

c-Src/Pyk2/EGFR/PI3K/Akt/CREB-activated pathway contributes to human cardiomyocyte hypertrophy: Role of COX-2 induction

Thrombin and COX-2 regulating cardiac hypertrophy are via various signaling cascades. Several transcriptional factors including CREB involve in COX-2 expression. However, the interplay among thrombin, CREB, and COX-2 in primary human neonatal ventricular cardiomyocytes remains unclear. In this study, thrombin-induced COX-2 promoter activity, mRNA and protein expression, and PGE2 synthesis were attenuated by pretreatment with the inhibitors of c-Src (PP1), Pyk2 (PF431396), EGFR (AG1478), PI3K/Akt (LY294002/SH-5), and p300 (GR343), or transfection with siRNAs of c-Src, Pyk2, EGFR, p110, Akt, CREB, and p300. Moreover, thrombin-stimulated phosphorylation of c-Src, Pyk2, EGFR, Akt, CREB and p300 was attenuated by their respective inhibitors. These results indicate that thrombin-induced COX-2 expression is mediated through PAR-1/c-Src/Pyk2/EGFR/PI3K/Akt linking to CREB and p300 cascades. Functionally, thrombin-induced hypertrophy and ANF/BNP release were, at least in part, mediated through a PAR-1/COX-2-dependent pathway. We uncover the importance of COX-2 regarding human cardiomyocyte hypertrophy that will provide a therapeutic intervention in cardiovascular diseases.

Resistin Promotes Angiogenesis in Endothelial Progenitor Cells Through Inhibition of MicroRNA206: Potential Implications for Rheumatoid Arthritis

Endothelial progenitor cells (EPCs) promote angiogenesis and are therefore key contributors to a wide variety of angiogenesis-related autoimmune diseases such as rheumatoid arthritis (RA). However, the signaling mechanisms through which these progenitor cells influence RA pathogenesis remain unknown. The aim of this study was to examine whether resistin plays a role in the pathogenesis of and angiogenesis associated with RA by circulating EPCs. We found that levels of resistin in synovial fluid and tissue from patients with RA and from mice with collagen-induced arthritis were overexpressed and promoted the homing of EPCs into the synovium, thereby inducing angiogenesis. EPCs isolated from healthy donors were used to investigate the signal transduction pathway underlying EPC migration and tube formation after treatment with resistin. We found that resistin directly induced a significant increase in expression of vascular endothelial growth factor (VEGF) in EPCs. We also found that the expression of microRNA-206 (miR-206) was negatively correlated with the expression of resistin during EPC-mediated angiogenesis. Notably, the increased expression of VEGF was associated with decreased binding of miR-206 to the VEGF-A 3' untranslated region through protein kinase C delta-dependent AMP-activated protein kinase signaling pathway. Moreover, blockade of resistin reduced EPC homing into synovial fluid and angiogenesis in vivo. Taken together, our study is the first to demonstrate that resistin promotes EPCs homing into the synovium during RA angiogenesis via a signal transduction pathway that involves VEGF expression in primary EPCs. These findings provide support for resistin as a therapeutic target for the patients with RA. Stem Cells 2015;33:2243-2255.

CCL5 promotes vascular endothelial growth factor expression and induces angiogenesis by down-regulating miR-199a in human chondrosarcoma cells

Chondrosarcoma is a primary malignant bone cancer, with a potent capacity to invade locally and cause distant metastasis. Angiogenesis is a critical step in tumor growth and metastasis. Chemokine CCL5 (previously called RANTES) has been shown to facilitate tumor progression and metastasis. However, the relationship of CCL5 with vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma is mostly unknown. In this study, CCL5 increased VEGF expression and also promoted chondrosarcoma medium-mediated angiogenesis in vitro as well as angiogenesis effects in the chick chorioallantoic membrane and Matrigel plug nude mice model in vivo. MicroRNA analysis was performed in CCL5-treated chondrosarcoma cells versus control cells to investigate the mechanism of CCL5-mediated promotion of chondrosarcoma angiogenesis. Among the miRNAs regulated by CCL5, miR-199a was the most downregulated miRNA after CCL5 treatment. In addition, co-transfection with miR-199a mimic reversed the CCL5-mediated VEGF expression and angiogenesis in vitro and in vivo. Moreover, overexpression of CCL5 increased tumor-associated angiogenesis and tumor growth by downregulating miR-199a in the xenograft tumor angiogenesis model. Taken together, these results demonstrated that CCL5 promotes VEGF-dependent angiogenesis in human chondrosarcoma cells by downregulating miR-199a.

The characteristics of thrombin in osteoarthritic pathogenesis and treatment

Osteoarthritis (OA) is a mechanical abnormality associated with degradation of joints. It is characterized by chronic, progressive degeneration of articular cartilage, abnormalities of bone, and synovial change. The most common symptom of OA is local inflammation resulting from exogenous stress or endogenous abnormal cytokines. Additionally, OA is associated with local and/or systemic activation of coagulation and anticoagulation pathways. Thrombin plays an important role in the stimulation of fibrin deposition and the proinflammatory processes in OA. Thrombin mediates hemostatic and inflammatory responses and guides the immune response to tissue damage. Thrombin activates intracellular signaling pathways by interacting with transmembrane domain G protein coupled receptors (GPCRs), known as protease-activated receptors (PARs). In pathogenic mechanisms, PARs have been implicated in the development of acute and chronic inflammatory responses in OA. Therefore, discovery of thrombin signaling pathways would help us to understand the mechanism of OA pathogenesis and lead us to develop therapeutic drugs in the future.

Leptin induces oncostatin M production in osteoblasts by downregulating miR-93 through the Akt signaling pathway

Inflammatory response and articular destruction are common symptoms of osteoarthritis (OA) and rheumatoid arthritis (RA). Leptin, an adipocyte-secreted hormone that centrally regulates weight control, may exert proinflammatory effects in the joint, depending on the immune response. Yet, the mechanism of leptin interacting with the arthritic inflammatory response is unclear. This study finds that leptin increased expression of oncostatin M (OSM) in human osteoblasts in a concentration- and time-dependent manner. In addition, OBRl, but not OBRs receptor antisense oligonucleotide, abolished the leptin-mediated increase of OSM expression. On the other hand, leptin inhibited miR-93 expression; an miR-93 mimic reversed leptin-increased OSM expression. Stimulation of osteoblasts with leptin promoted Akt phosphorylation, while pretreatment of cells with Akt inhibitor or siRNA reversed leptin-inhibited miR-93 expression. Our results showed that leptin heightened OSM expression by downregulating miR-93 through the Akt signaling pathway in osteoblasts, suggesting leptin as a novel target in arthritis treatment.

CCN1 induces oncostatin M production in osteoblasts via integrin-dependent signal pathways

Inflammatory response and articular destruction are common symptoms of osteoarthritis. Cysteine-rich 61 (CCN1 or Cyr61), a secreted protein from the CCN family, is associated with the extracellular matrix involved in many cellular activities like growth and differentiation. Yet the mechanism of CCN1 interacting with arthritic inflammatory response is unclear. This study finds CCN1 increasing expression of oncostatin m (OSM) in human osteoblastic cells. Pretreatment of αvβ3 monoclonal antibody and inhibitors of focal adhesion kinase (FAK), c-Src, phosphatidylinositol 3-kinase (PI3K), and NF-κB inhibited CCN1-induced OSM expression in osteoblastic cells. Stimulation of cells with CCN1 increased phosphorylation of FAK, c-Src, PI3K, and NF-κB via αvβ3 receptor; CCN1 treatment of osteoblasts increased NF-κB-luciferase activity and p65 binding to NF-κB element on OSM promoter. Results indicate CCN1 heightening OSM expression via αvβ3 receptor, FAK, c-Src, PI3K, and NF-κB signal pathway in osteoblastic cells, suggesting CCN1 as a novel target in arthritis treatment.

Brain-derived neurotrophic factor increases vascular endothelial growth factor expression and enhances angiogenesis in human chondrosarcoma cells

Chondrosarcomas are a type of primary malignant bone cancer, with a potent capacity for local invasion and distant metastasis. Brain-derived neurotrophic factor (BDNF) is commonly upregulated during neurogenesis. The aim of the present study was to examine the mechanism involved in BDNF-mediated vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma cells. Here, we knocked down BDNF expression in chondrosarcoma cells and assessed their capacity to control VEGF expression and angiogenesis in vitro and in vivo. We found knockdown of BDNF decreased VEGF expression and abolished chondrosarcoma conditional medium-mediated angiogenesis in vitro as well as angiogenesis effects in vivo in the chick chorioallantoic membrane and Matrigel plug nude mouse models. In addition, in the xenograft tumor angiogenesis model, the knockdown of BDNF significantly reduced tumor growth and tumor-associated angiogenesis. BDNF increased VEGF expression and angiogenesis through the TrkB receptor, PLCγ, PKCα, and the HIF-1α signaling pathway. Finally, we analyzed samples from chondrosarcoma patients by immunohistochemical staining. The expression of BDNF and VEGF protein in 56 chondrosarcoma patients was significantly higher than in normal cartilage. In addition, the high level of BDNF expression correlated strongly with VEGF expression and tumor stage. Taken together, our results indicate that BDNF increases VEGF expression and enhances angiogenesis through a signal transduction pathway that involves the TrkB receptor, PLCγ, PKCα, and the HIF-1α. Therefore, BDNF may represent a novel target for anti-angiogenic therapy for human chondrosarcoma.

Paeonol suppresses chondrosarcoma metastasis through up-regulation of miR-141 by modulating PKCδ and c-Src signaling pathway

Chondrosarcoma, a primary malignant bone cancer, has potential for local invasion and distant metastasis, especially to the lungs. Patients diagnosed with it show poor prognosis. Paeonol (2'-hydroxy-4'-methoxyacetophenone), the main active compound of traditional Chinese remedy Paeonia lactiflora Pallas, exhibits anti-inflammatory and anti-tumor activity; whether paeonol regulates metastatic chondrosarcoma is largely unknown. Here, we find paeonol do not increase apoptosis. By contrast, at non-cytotoxic concentrations, paeonol suppresses migration and invasion of chondrosarcoma cells. We also demonstrate paeonol enhancing miR-141 expression and miR-141 inhibitor reversing paeonol-inhibited cell motility; paeonol also reduces protein kinase C (PKC)d and c-Src kinase activity. Since paeonol inhibits migration and invasion of human chondrosarcoma via up-regulation of miR-141 via PKCd and c-Src pathways, it thus might be a novel anti-metastasis agent for treatment of metastatic chondrosarcoma.

Naringin suppress chondrosarcoma migration through inhibition vascular adhesion molecule-1 expression by modulating miR-126

Chondrosarcoma, a primary malignant bone cancer, has a potent capacity to invade locally and cause distant metastasis, especially to the lungs. Patients diagnosed with it have poor prognosis. Naringin, polymethoxylated flavonoid commonly found in citrus fruits, has anti-oxidant, anti-inflammatory and anti-tumor activity; whether naringin regulates migration of chondrosarcoma is largely unknown. Here we report that naringin does not expedite apoptosis in human chondrosarcoma. By contrast, at noncytotoxic concentrations, naringin suppressed migration and invasion of chondrosarcoma cells. Vascular cell adhesion molecule-1 (VCAM-1) of the immunoglobulin superfamily is linked with metastasis; we found incubation of chondrosarcoma cells with naringin reducing mRNA transcription for, and cell surface expression of, VCAM-1. We also observed that naringin enhancing miR-126 expression, and miR-126 inhibitor reversed the naringin-inhibited cell motility and VCAM-1 expression. Therefore, naringin inhibits migration and invasion of human chondrosarcoma via down-regulation of VCAM-1 by increasing miR-126. Thus, naringin may be a novel anti-migration agent for the treatment of migration in chondrosarcoma.

Syk/JNK/AP-1 signaling pathway mediates interleukin-6-promoted cell migration in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) typically migrates and metastasizes. Interleukin-6 (IL-6) is a multifunctional cytokine associated with disease status and cancer outcomes. The effect of IL-6 on human OSCC cells, however, is unknown. Here, we showed that IL-6 increased cell migration and Intercellular adhesion molecule-1 (ICAM-1) expression in OSCC cells. Pretreatment of OSCC cells with IL-6R monoclonal antibody (mAb) significantly abolished IL-6-induced cell migration and ICAM-1 expression. By contrast, IL-6-mediated cell motility and ICAM-1 upregulation were attenuated by the Syk and c-Jun N-terminal kinase (JNK) inhibitors. Stimulation of OSCC cells with IL-6 promoted Syk and JNK phosphorylation. Furthermore, IL-6 enhanced AP-1 activity, and the IL-6R mAb, Syk inhibitor, or JNK inhibitor all reduced IL-6-mediated c-Jun phosphorylation, c-Jun binding to the ICAM-1 promoter, and c-Jun translocation into the nucleus. Our results indicate that IL-6 enhances the migration of OSCC cells by increasing ICAM-1 expression through the IL-6R receptor and the Syk, JNK, and AP-1 signal transduction pathways.

Thrombin promotes matrix metalloproteinase-13 expression through the PKCδ c-Src/EGFR/PI3K/Akt/AP-1 signaling pathway in human chondrocytes

Thrombin is a key mediator of fibrin deposition, angiogenesis, and proinflammatory processes. Abnormalities in these processes are primary features of rheumatoid arthritis and osteoarthritis. Matrix metalloproteinase-13 (MMP-13) may contribute to the breakdown of articular cartilage during arthritis. However, the role of thrombin in MMP-13 production in chondrocytes is unknown. In this study, we investigated the intracellular signaling pathways involved in thrombin-induced MMP-13 expression in human chondrocytes. We found that stimulation with thrombin led to increased secretion of MMP-13 in cultured human chondrocytes. Further, this thrombin-induced MMP-13 production was reduced after transfection with siRNAs against protease activated receptors 1 and 3 (PAR1 and PAR3), but not with PAR4 siRNA. Treatment with specific inhibitors for PKCδ, c-Src, EGFR, PI3K, Akt, or AP-1 or with the corresponding siRNAs against these signaling proteins also abolished the thrombin-mediated increase in MMP-13 production in chondrocytes. Our results provide evidence that thrombin acts through the PAR1/PAR3 receptors and activates PKCδ and c-Src, resulting in EGFR transactivation and activation of PI3K, Akt, and finally AP-1 on the MMP-13 promoter, thereby contributing to cartilage destruction during arthritis.

Proteinase-activated receptors (PARs) - focus on receptor-receptor-interactions and their physiological and pathophysiological impact

Proteinase-activated receptors (PARs) are a subfamily of G protein-coupled receptors (GPCRs) with four members, PAR₁, PAR₂, PAR₃ and PAR₄, playing critical functions in hemostasis, thrombosis, embryonic development, wound healing, inflammation and cancer progression. PARs are characterized by a unique activation mechanism involving receptor cleavage by different proteinases at specific sites within the extracellular amino-terminus and the exposure of amino-terminal “tethered ligand“ domains that bind to and activate the cleaved receptors. After activation, the PAR family members are able to stimulate complex intracellular signalling networks via classical G protein-mediated pathways and beta-arrestin signalling. In addition, different receptor crosstalk mechanisms critically contribute to a high diversity of PAR signal transduction and receptor-trafficking processes that result in multiple physiological effects.

In this review, we summarize current information about PAR-initiated physical and functional receptor interactions and their physiological and pathological roles. We focus especially on PAR homo- and heterodimerization, transactivation of receptor tyrosine kinases (RTKs) and receptor serine/threonine kinases (RSTKs), communication with other GPCRs, toll-like receptors and NOD-like receptors, ion channel receptors, and on PAR association with cargo receptors. In addition, we discuss the suitability of these receptor interaction mechanisms as targets for modulating PAR signalling in disease.

Bradykinin promotes vascular endothelial growth factor expression and increases angiogenesis in human prostate cancer cells

Prostate cancer is the most commonly diagnosed malignancy in men and shows a tendency for metastasis to distant organs. Angiogenesis is required for metastasis. Bradykinin (BK) is an inflammatory mediator involved in tumor growth and metastasis, but its role in vascular endothelial growth factor (VEGF) expression and angiogenesis in human prostate cancer remains unknown. The aim of this study was to examine whether BK promotes prostate cancer angiogenesis via VEGF expression. We found that exogenous BK increased VEGF expression in prostate cancer cells and further promoted tube formation in endothelial progenitor cells and human umbilical vein endothelial cells. Pretreatment of prostate cancer with B2 receptor antagonist or small interfering RNA (siRNA) reduced BK-mediated VEGF production. The Akt and mammalian target of rapamycin (mTOR) pathways were activated after BK treatment, and BK-induced VEGF expression was abolished by the specific inhibitor and siRNA of the Akt and mTOR cascades. BK also promoted nuclear factor-κB (NF-κB) and activator protein 1 (AP-1) activity. Importantly, BK knockdown reduced VEGF expression and abolished prostate cancer cell conditional medium-mediated angiogenesis. Taken together, these results indicate that BK operates through the B2 receptor, Akt, and mTOR, which in turn activate NF-κB and AP-1, activating VEGF expression and contributing to angiogenesis in human prostate cancer cells.

Si-Wu-tang extract stimulates bone formation through PI3K/Akt/NF-κB signaling pathways in osteoblasts

BACKGROUND

Si-Wu-Tang (SWT), a Traditional Chinese Medicine (TCM) formula, is widely used for the treatment of gynopathies diseases such as menstrual discomfort, climacteric syndrome, dysmenorrhea, and other estrogen-related diseases. Recent studies have shown that SWT can treat primary dysmenorrhea, have anti-pruritic anti-inflammatory effects, and protect against radiation-induced bone marrow damage in an animal model. It has been reported that anti-inflammatory and anti-oxidant agents have the potential to treat osteoporosis by increasing bone formation and/or suppressing bone resorption. However, the effect of SWT on bone cell function has not yet been reported.

METHODS

Alkaline phosphatase (ALP), bone morphogenetic proteins (BMP)-2, and osteopontin (OPN) mRNA expression was analyzed by qPCR. The mechanism of action of SWT extract was investigated using western blotting. The in vivo anti-osteoporotic effect of SWT extract was assessed in ovariectomized mice.

RESULTS

Here, we report that SWT increases ALP, BMP-2, and OPN expression as well as bone mineralization. In addition, we show that the PI3K, Akt, and NF-κB signaling pathways may be involved in the SWT-mediated increase in gene expression and bone mineralization. Notably, treatment of mice with SWT extract prevented bone loss induced by ovariectomy in vivo.

CONCLUSION

SWT may be used to stimulate bone formation for the treatment of osteoporosis.

Apoptosis signal-regulating kinase 1 is involved in WISP-1-promoted cell motility in human oral squamous cell carcinoma cells

Oral squamous cell carcinoma (OSCC) has a tendency to migrate and metastasize. WNT1-inducible signaling pathway protein 1 (WISP-1) is a cysteine-rich protein that belongs to the Cyr61, CTGF, Nov (CCN) family of matrix cellular proteins. The effect of WISP-1 on human OSCC cells, however, is unknown. Here, we showed that WISP-1 increased cell migration and intercellular adhesion molecule-1 (ICAM-1) expression in OSCC cells. Pretreatment of cells with integrin αvβ3 monoclonal antibody (mAb) significantly abolished WISP-1–induced cell migration and ICAM-1 expression. On the other hand, WISP-1–mediated cell motility and ICAM-1 upregulation were attenuated by ASK1, JNK, and p38 inhibitor. Furthermore, WISP-1 also enhanced activator protein 1 (AP-1) activation, and the integrin αvβ3 mAb, and ASK1, JNK, and p38 inhibitors reduced WISP-1–mediated AP-1 activation. Moreover, WISP-1 and ICAM-1 expression correlated with the tumor stage of patients with OSCC. Our results indicate that WISP-1 enhances the migration of OSCC cells by increasing ICAM-1 expression through the αvβ3 integrin receptor and the ASK1, JNK/p38, and AP-1 signal transduction pathways.

Leptin induces IL-6 expression through OBRl receptor signaling pathway in human synovial fibroblasts

BACKGROUND

Leptin, an adipocyte-secreted hormone that centrally regulates weight control, may exert proinflammatory effects in the joint, depending on the immune response. Leptin is abundantly expressed in osteoarthritis (OA) cartilage and synovium. However, the relationship between leptin and interleukin-6 (IL-6) in OA synovial fibroblasts (OASFs) remains obscure.

METHODOLOGY/PRINCIPAL FINDINGS

Stimulation of OASFs with leptin induced IL-6 expression in a concentration- and time-dependent manner. OASFs expressed the long (OBRl) and short (OBRs) isoforms of the leptin receptor. However, OBRl, but not OBRs, antisense oligonucleotide (AS-ODN) abolished the leptin-mediated increase of IL-6 expression. Transfection with insulin receptor substrate (IRS)-1 siRNA decreased leptin-induced IL-6 production. In addition, pretreatment of cells with PI3K, Akt, or AP-1 inhibitor also inhibited the potentiating action of leptin. Leptin-induced AP-1 activation was inhibited by OBRl, IRS-1, PI3K, or Akt inhibitors and siRNAs.

CONCLUSIONS/SIGNIFICANCE

Our results showed that leptin activates the OBRl receptor, which in turn activates IRS-1, PI3K, Akt, and AP-1 pathway, leading to up-regulation of IL-6 expression.