Mevastatin ameliorates sphingosine 1-phosphate-induced COX-2/PGE2-dependent cell migration via FoxO1 and CREB phosphorylation and translocation

A new look at angiogenesis inhibition of geniposide in experimental arthritis by blocking angiopoietin-2 exocytosis

Angiogenesis is a key player in the pathogenesis of rheumatoid arthritis. Exocytosis from Weibel-Palade bodies is a prerequisite for angiopoietin-2 (Ang-2) to activate endothelial cells and initiate angiogenesis. Geniposide (GE) was previously reported to exert anti-angiogenic effects. The aim of this study was to shed light on whether and how GE regulates Ang-2 exocytosis. A rat model of adjuvant arthritis (AA) was established to evaluate the therapeutic effect of GE (60 and 120 mg/kg) especially in synovial angiogenesis. In addition, the Matrigel plug assay was used to detect the effect of GE (120 and 240 mg/kg) on angiogenesis in AA mice. In vitro, sphingosine-1-phosphate (S1P)-stimulated human umbilical vein endothelial cells (HUVECs) were used to investigate the effect and mechanism of GE on Ang-2 exocytosis. It was found that GE improved the symptoms of AA rats and inhibited angiogenesis in AA, which may be related to the down-regulation of S1P receptors 1, 3 (S1PR1, S1PR3), phospholipase Cβ3 (PLCβ3), inositol 1,4,5-trisphosphate receptor (IP3 R) and Ang-2 expression. The results of in vitro experiments showed that S1P induced rapid release of Ang-2 from HUVECs with multigranular exocytosis. Suppression of the S1P/S1PR1/3/PLCβ3/Ca2+ signal axis by the S1PR1/3 inhibitor VPC23019 and the IP3 R inhibitor 2-APB blocked Ang-2 exocytosis, accompanied by diminished angiogenesis in vitro. GE dose-dependently weakened S1P/S1PR1/3/PLCβ3/Ca2+ signal axis activation, Ang-2 exocytosis and angiogenesis in HUVECs (p < 0.05, p < 0.01). Overall, these findings revealed that angiogenesis inhibition of GE was partly attributed to the intervention of Ang-2 exocytosis through negatively modulating the S1P/S1PR1/3/PLCβ3/Ca2+ signal axis, providing a novel strategy for rheumatoid arthritis anti-angiogenic therapy.

Noncoding RNA-mediated macrophage and cancer cell crosstalk in hepatocellular carcinoma

The tumor microenvironment (TME) is a well-recognized system that plays an essential role in tumor initiation, development, and progression. Intense intercellular communication between tumor cells and other cells (especially macrophages) occurs in the TME and is mediated by cell-to-cell contact and/or soluble messengers. Emerging evidence indicates that noncoding RNAs (ncRNAs) are critical regulators of the relationship between cells within the TME. In this review, we provide an update on the regulation of ncRNAs (primarily micro RNAs [miRNAs], long ncRNAs [lncRNAs], and circular RNAs [circRNAs]) in the crosstalk between macrophages and tumor cells in hepatocellular carcinoma (HCC). These ncRNAs are derived from macrophages or tumor cells and act as oncogenes or tumor suppressors, contributing to tumor progression not only by regulating the physiological and pathological processes of tumor cells but also by controlling macrophage infiltration, activation, polarization, and function. Herein, we also explore the options available for clinical therapeutic strategies targeting crosstalk-related ncRNAs to treat HCC. A better understanding of the relationship between macrophages and tumor cells mediated by ncRNAs will uncover new diagnostic biomarkers and pharmacological targets in cancer.

Stressed out - The role of oxidative stress in airway smooth muscle dysfunction in asthma and COPD

The airway smooth muscle (ASM) surrounding the airways is dysfunctional in both asthma and chronic obstructive pulmonary disease (COPD), exhibiting; increased contraction, increased mass, increased inflammatory mediator release and decreased corticosteroid responsiveness. Due to this dysfunction, ASM is a key contributor to symptoms in patients that remain symptomatic despite optimal provision of currently available treatments. There is a significant body of research investigating the effects of oxidative stress/ROS on ASM behaviour, falling into the following categories; cigarette smoke and associated compounds, air pollutants, aero-allergens, asthma and COPD relevant mediators, and the anti-oxidant Nrf2/HO-1 signalling pathway. However, despite a number of recent reviews addressing the role of oxidative stress/ROS in asthma and COPD, the potential contribution of oxidative stress/ROS-related ASM dysfunction to asthma and COPD pathophysiology has not been comprehensively reviewed. We provide a thorough review of studies that have used primary airway, bronchial or tracheal smooth muscle cells to investigate the role of oxidative stress/ROS in ASM dysfunction and consider how they could contribute to the pathophysiology of asthma and COPD. We summarise the current state of play with regards to clinical trials/development of agents targeting oxidative stress and associated limitations, and the adverse effects of oxidative stress on the efficacy of current therapies, with reference to ASM related studies where appropriate. We also identify limitations in the current knowledge of the role of oxidative stress/ROS in ASM dysfunction and identify areas for future research.

Sphingosine 1-Phosphate-Upregulated COX-2/PGE2 System Contributes to Human Cardiac Fibroblast Apoptosis: Involvement of MMP-9-Dependent Transactivation of EGFR Cascade

Human cardiac fibroblasts (HCFs) play key roles in normal physiological functions and pathological processes in the heart. Our recent study has found that, in HCFs, sphingosine 1-phosphate (S1P) can upregulate the expression of cyclooxygenase-2 (COX-2) leading to prostaglandin E2 (PGE2) generation mediated by S1P receptors/PKCα/MAPKs cascade-dependent activation of NF-κB. Alternatively, G protein-coupled receptor- (GPCR-) mediated transactivation of receptor tyrosine kinases (RTKs) has been proved to induce inflammatory responses. However, whether GPCR-mediated transactivation of RTKs participated in the COX-2/PGE2 system induced by S1P is still unclear in HCFs. We hypothesize that GPCR-mediated transactivation of RTKs-dependent signaling cascade is involved in S1P-induced responses. This study is aimed at exploring the comprehensive mechanisms of S1P-promoted COX-2/PGE2 expression and apoptotic effects on HCFs. Here, we used pharmacological inhibitors and transfection with siRNA to evaluate whether matrix metalloprotease (MMP)2/9, heparin-binding- (HB-) epidermal growth factor (EGF), EGF receptor (EGFR), PI3K/Akt, MAPKs, and transcription factor AP-1 participated in the S1P-induced COX-2/PGE2 system determined by Western blotting, real-time polymerase chain reaction (RT-PCR), chromatin immunoprecipitation (ChIP), and promoter-reporter assays in HCFs. Our results showed that S1PR1/3 activated by S1P coupled to Gq- and Gi-mediated MMP9 activity to stimulate EGFR/PI3K/Akt/MAPKs/AP-1-dependent activity of transcription to upregulate COX-2 accompanied with PGE2 production, leading to stimulation of caspase-3 activity and apoptosis. Moreover, S1P-enhanced c-Jun bound to COX-2 promoters on its corresponding binding sites, which was attenuated by these inhibitors of protein kinases, determined by a ChIP assay. These results concluded that transactivation of MMP9/EGFR-mediated PI3K/Akt/MAPKs-dependent AP-1 activity was involved in the upregulation of the COX-2/PGE2 system induced by S1P, in turn leading to apoptosis in HCFs.

Asperanstinoids A-E: Undescribed 3,5-dimethylorsellinic acid-based meroterpenoids from Aspergillus calidoustus

Large-scale culture is a complementary and practical method for genome mining and OSMAC approaches to discover novel natural products through accumulation and reprocessing effects. By employing a large-scale culture approach, twelve 3,5-dimethylorsellinic acid (DMOA)-based meroterpenoids, including five undescribed compounds, namely asperanstinoids A-E, were obtained from fungus Aspergillus calidoustus, which was isolated from the wetland soil collected at Dianchi Lake, Yunnan Province. The structures and absolute configurations of asperanstinoids A-E were determined by various spectroscopic analyses, including NMR spectroscopy, high-resolution electrospray ionization mass spectrometry (HRESIMS), single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations, and the absolute configurations of three known compounds, dehydroaustinol, austinol, and austin, were confirmed via single-crystal X-ray diffraction for the first time. Notably, asperanstinoid A represents the second example of a DMOA-based meroterpenoid featuring a unique 6/5/6/6/6/5-fused hexacyclic skeleton with a rare "1,13-epoxy" moiety. The cytotoxicity assay of all these isolates revealed that asperanstinoid D, dehydroaustinol, and austin displayed considerable cytotoxicity against the HL-60 and SU-DHL-4 tumor cell lines with IC₅₀ values ranging from 15.7 to 27.8 μM.

Upregulation of COX-2 and PGE2 Induced by TNF-α Mediated Through TNFR1/MitoROS/PKCα/P38 MAPK, JNK1/2/FoxO1 Cascade in Human Cardiac Fibroblasts

Purpose

Tumor necrosis factor-α (TNF-α) has been shown to exert as a pathogenic factor in cardiac fibrosis and heart failure which were associated with the up-regulation of cyclooxygenase (COX)-2/prostaglandin E₂ (PGE₂) axis. However, whether TNF-α-induced COX-2/PGE₂ upregulation mediated through ROS-dependent cascade remains elusive in human cardiac fibroblasts (HCFs). This study aims to address the underlying mechanisms of TNF-α-induced COX-2/PGE₂ expression.

Methods

Here, we used TNF receptor neutralizing antibody (TNFR nAb), pharmacologic inhibitors, and siRNAs to dissect the involvement of signaling components examined by Western blot and ELISA in TNF-α-mediated responses in HCFs. MitoSOX Red was used to measure mitoROS generation. Isolation of subcellular fractions was performed to determine membrane translocation of PKCα. Promoter luciferase assay and chromatin immunoprecipitation (ChIP) assay were used to determine the role of transcription factor.

Results

We found that TNF-α time- and concentration-dependently upregulated COX-2 protein and mRNA expression as well as PGE₂ synthesis which was attenuated by TNFR1 nAb, the inhibitor of mitochondrial ROS scavenger (MitoTEMPO), protein kinase C [(PKC)α, Gö6976], p38 MAPK [p38 inhibitor VIII, (p38i VIII)], JNK1/2 (SP600125), or forkhead box protein O1 [(FoxO1), AS1842856], and transfection with their respective siRNAs in HCFs. TNF-α-stimulated PKCα phosphorylation was inhibited by TNFR1 nAb, MitoTEMPO, or Gö6976. TNF-α stimulated phosphorylation of p38 MAPK and JNK1/2 was attenuated by TNFR1 nAb, MitoTEMPO, Gö6976, and their inhibitors p38i VIII and SP600125. Moreover, TNF-α-triggered FoxO1 phosphorylation was abolished by AS1842856, TNFR1 nAb, and its upstream inhibitors MitoTEMPO, Gö6976, p38i VIII, and SP600125. Phosphorylation of FoxO1 could enhance its interaction with the COX-2 promoter element revealed by ChIP assay, which was attenuated by AS1842856.

Conclusion

Our results suggested that TNF-α-induced COX-2/PGE₂ upregulation is mediated through TNFR1-dependent MitoROS/PKCα/p38 MAPK and JNK1/2 cascade to activate FoxO1 binding with the COX-2 promoter in HCFs.

PPARγ Attenuates Interleukin-1β-Induced Cell Apoptosis by Inhibiting NOX2/ROS/p38MAPK Activation in Osteoarthritis Chondrocytes

INTRODUCTION

Reactive oxygen species (ROS) induced by extracellular cytokines trigger the expression of inflammatory mediators in osteoarthritis (OA) chondrocyte. Peroxisome proliferator-activated receptor gamma (PPARγ) exerts an anti-inflammatory effect. The aim of this study was to elucidate the role of PPARγ in interleukin-1β- (IL-1β-) induced cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) expression through ROS generation in OA chondrocytes.

METHODS

IL-1β-induced ROS generation and chondrocyte apoptosis were determined by flow cytometry. Contents of NADPH oxidase (NOX), caspase-3, and caspase-9 were evaluated by biochemical detection. The involvement of NOX2 and mitogen-activated protein kinases (MAPKs) in IL-1β-induced COX-2 and PGE2 expression was investigated using pharmacologic inhibitors and further analyzed by western blotting. Activation of PPARγ was performed by using a pharmacologic agonist and was analyzed by western blotting.

RESULTS

IL-1β-induced COX-2 and PGE2 expression was mediated through NOX2 activation/ROS production, which could be attenuated by N-acetylcysteine (NAC; a scavenger of ROS), GW1929 (PPARγ agonist), DPI (diphenyleneiodonium chloride, NOX2 inhibitor), SB203580 (p38MAPK inhibitor), PD98059 (extracellular signal-regulated kinase, ERK inhibitor), and SP600125 (c-Jun N-terminal kinase, JNK inhibitor). ROS activated p38MAPK to enter the nucleus, which was attenuated by PPARγ.

CONCLUSION

In OA chondrocytes, IL-1β induced COX-2 and PGE2 expression via activation of NOX2, which led to ROS production and MAPK activation. The activation of PPARγ exerted protective roles in the pathogenesis of OA.

CircRNA hsa_circ_0110102 inhibited macrophage activation and hepatocellular carcinoma progression via miR-580-5p/PPARα/CCL2 pathway

Circular RNAs (circRNAs) have critical regulatory roles in tumor biology. However, their contributions in hepatocellular carcinoma (HCC) still remain enigmatic. The present study aimed to investigate the molecular mechanisms underlying the involvement of hsa_circ_0110102 in the occurrence and development of HCC. The expression level of hsa_circ_0110102 was significantly downregulated in HCC cell lines and tissues, which was associated with poor prognosis. Knockdown hsa_circ_0110102 significantly promoted cell proliferation, migration, and invasion. Moreover, the interaction between hsa_circ_0110102 and miR-580-5p was predicted and verified by luciferase assay and RNA pull-down. The findings indicated that hsa_circ_0110102 functioned as a sponge for miR-580-5p. Moreover, miR-580-5p directly bound to the 3' UTR of PPARα, which decreased the production and release of C-C chemokine ligand 2 (CCL2) in HCC cells. CCL2 could activate the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway in macrophage via FoxO1 in a p38 MAPK-dependent manner. Furthermore, the Δ256 mutant of FoxO1 showed no activation effect. These results concluded that hsa_circ_0110102 acted as a sponge for miR-580-5p and inhibited CCL2 secretion into tumor microenvironment by decrease the expression of PPARα in HCC cells, then inhibited the pro-inflammatory cytokine release from macrophages by regulating the COX-2/PGE2 pathway. In conclusion, hsa_circ_0110102 served as a potential prognostic predictor or therapeutic target for HCC.

Sphingosine-1 phosphate induces cAMP/PKA-independent phosphorylation of the cAMP response element-binding protein (CREB) in granulosa cells

BACKGROUND AND AIMS

Sphingosine-1 phosphate (S1P) is a lysosphingolipid present in the ovarian follicular fluid. The role of the lysosphingolipid in gonads of the female is widely unclear. At nanomolar concentrations, S1P binds and activates five specific G protein-coupled receptors (GPCRs), known as S1P_1-5, modulating different signaling pathways. S1P₁ and S1P₃ are highly expressed in human primary granulosa lutein cells (hGLC), as well as in the immortalized human primary granulosa cell line hGL5. In this study, we evaluated the signaling cascade activated by S1P and its synthetic analogues in hGLC and hGL5 cells, exploring the biological relevance of S1PR-stimulation in this context.

METHODS AND RESULTS

hGLC and hGL5 cells were treated with a fixed dose (0.1 μM) of S1P, or by S1P₁- and S1P₃-specific agonists SEW2871 and CYM5541. In granulosa cells, S1P and, at a lesser extent, SEW2871 and CYM5541, potently induced CREB phosphorylation. No cAMP production was detected and pCREB activation occurred even in the presence of the PKA inhibitor H-89. Moreover, S1P-dependent CREB phosphorylation was dampened by the mitogen-activate protein kinase (MEK) inhibitor U0126 and by the L-type Ca²⁺ channel blocker verapamil. The complete inhibition of CREB phosphorylation occurred by blocking either S1P₂ or S1P₃ with the specific receptor antagonists JTE-013 and TY52156, or under PLC/PI3K depletion. S1P-dependent CREB phosphorylation induced FOXO1 and the EGF-like epiregulin-encoding gene (EREG), confirming the exclusive role of gonadotropins and interleukins in this process, but did not affect steroidogenesis. However, S1P or agonists did not modulate granulosa cell viability and proliferation in our conditions.

CONCLUSIONS

This study demonstrates for the first time that S1P may induce a cAMP-independent activation of pCREB in granulosa cells, although this is not sufficient to induce intracellular steroidogenic signals and progesterone synthesis. S1P-induced FOXO1 and EREG gene expression suggests that the activation of S1P-S1PR axis may cooperate with gonadotropins in modulating follicle development.

Pro-Survival Lipid Sphingosine-1-Phosphate Metabolically Programs T Cells to Limit Anti-tumor Activity

Sphingosine 1-phosphate (S1P), a bioactive lysophospholipid generated by sphingosine kinase 1 (SphK1), regulates lymphocyte egress into circulation via S1P receptor 1 (S1PR1) signaling, and it controls the differentiation of regulatory T cells (Tregs) and T helper-17 cells. However, the mechanisms by which receptor-independent SphK1-mediated intracellular S1P levels modulate T cell functionality remains unknown. We show here that SphK1-deficient T cells maintain central memory phenotype and exhibit higher mitochondrial respiration and reduced differentiation to Tregs. Mechanistically, we discovered a direct correlation between SphK1-generated S1P and lipid transcription factor PPARγ (peroxisome proliferator-activated receptor gamma) activity, which in turn regulates lipolysis in T cells. Genetic and pharmacologic inhibition of SphK1 improved metabolic fitness and anti-tumor activity of T cells against murine melanoma. Further, inhibition of SphK1 and PD1 together led to improved control of melanoma. Overall, these data highlight the clinical potential of limiting SphK1/S1P signaling for enhancing anti-tumor-adoptive T cell therapy.

PTEN participates in airway remodeling of asthma by regulating CD38/Ca2+/CREB signaling

Both phosphatase and tensin homologue deleted on chromosome ten (PTEN) and cluster of differentiation 38 (CD38) have been suggested to be key regulators of the pathogenesis of asthma. However, the precise role and molecular mechanisms by which PTEN and CD38 are involved in airway remodeling throughout asthma pathogenesis remains poorly understood. This study aimed to elucidate the role of PTEN and CD38 in airway remodeling of asthma. Exposure to tumor necrosis factor-α (TNF-α) in airway smooth muscle (ASM) cells markedly decreased PTEN expression, and increased expression of CD38. Overexpression of PTEN suppressed the expression of CD38 and downregulated proliferation and migration induced by TNF-α stimulation, which was partially reversed by CD38 overexpression. PTEN/CD38 axis regulated Ca2+ levels and cyclic AMP response-element binding protein (CREB) phosphorylation in TNF-α-stimulated ASM cells. The in vitro knockdown of CD38 or overexpression of PTEN remarkably restricted airway remodeling and decreased Ca2+ concentrations and CREB phosphorylation in asthmatic mice. CD38 overexpression abolished the inhibitory effects of PTEN overexpression on airway remodeling. These findings demonstrate that PTEN inhibits airway remodeling of asthma through the downregulation of CD38-mediated Ca2+/CREB signaling, highlighting a key role of PTEN/CD38/Ca2+/CREB signaling in the molecular pathogenesis of asthma.

Nonesterified free fatty acids enhance the inflammatory response in renal tubules by inducing extracellular ATP release

In proteinuric renal diseases, excessive plasma nonesterified free fatty acids bound to albumin can leak across damaged glomeruli to be reabsorbed by renal proximal tubular cells and cause inflammatory tubular cells damage by as yet unknown mechanisms. The present study was designed to investigate these mechanisms induced by palmitic acid (PA; one of the nonesterified free fatty acids) overload. Our results show that excess PA stimulates ATP release through the pannexin 1 channel in human renal tubule epithelial cells (HK-2), increasing extracellular ATP concentration approximately threefold compared with control. The ATP release is dependent on caspase-3/7 activation induced by mitochondrial reactive oxygen species. Furthermore, extracellular ATP aggravates PA-induced monocyte chemoattractant protein-1 secretion and monocyte infiltration of tubular cells, enlarging the inflammatory response in both macrophages and HK-2 cells via the purinergic P2X7 receptor-mammalian target of rapamycin-forkhead box O1-thioredoxin-interacting protein/NOD-like receptor protein 3 inflammasome pathway. Hence, PA increases mitochondrial reactive oxygen species-induced ATP release and inflammatory stress, which cause a "first hit," while ATP itself is a "second hit" in amplifying the renal tubular inflammatory response. Thus, inhibition of ATP release or the purinergic P2X7 receptor may be an approach to reduce renal inflammation and improve renal function.

COX-2 in liver fibrosis

As a vital inducible sensor, cyclooxygenase-2 (COX-2) plays an important role in the progress of hepatic fibrogenesis. Activation of hepatic stellate cells (HSCs) in the liver can significantly accelerate the onset and development of liver fibrosis. COX-2 overexpression triggers inflammation that is an important inducer in hepatic fibrosis. Increasing evidence indicates that COX-2 is involved in the main pathogenesis of liver fibrosis, such as inflammation, apoptosis, and cell senescence. Moreover, COX-2 expression is altered in patients and animal models with non-alcoholic fatty liver disease or cirrhosis. These findings suggest that COX-2 has a broad and critical role in the development of liver fibrosis. In this review, we summarize the latest advances in the regulation and signal transduction of COX-2 and its impact on liver fibrosis.

Mevastatin-Induced AP-1-Dependent HO-1 Expression Suppresses Vascular Cell Adhesion Molecule-1 Expression and Monocyte Adhesion on Human Pulmonary Alveolar Epithelial Cells Challenged with TNF-α

Mevastatin (MVS) has been previously shown to induce heme oxygenase (HO)-1 expression through Nox/ROS-dependent PDGFRα/PI3K/Akt/Nrf2/ARE axis in human pulmonary alveolar epithelial cells (HPAEpiCs). However, alternative signaling pathways might involve in MVS-induced HO-1 expression. We found that tumor necrosis factor α (TNFα) induced vascular cell adhesion protein 1 (VCAM-1) expression and NF-κB p65 phosphorylation which were attenuated by pretreatment with MVS via up-regulation of HO-1, determined by Western blot and real-time qPCR. TNFα-induced VCAM-1 expression was attenuated by an NF-κB inhibitor, Bay117082. The inhibitory effects of MVS were reversed by tin protoporphyrin (SnPP)IX (an inhibitor of HO-1 activity). In addition, pretreatment with the inhibitor of pan-Protein kinase C (PKC) (GF109203X), PKCα (Gö6983), Pyk2 (PF431396), p38α MAPK (SB202190), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA), and transfection with their respective siRNAs abolished MVS-induced HO-1 expression in HPAEpiCs. c-Jun (one of AP-1 subunits) was activated by PKCα, Pyk2, p38α MAPK, and JNK1/2, which turned on the transcription of the homx1 gene. The interaction between c-Jun and HO-1 promoter was confirmed by a chromatin immunoprecipitation (ChIP) assay, which was attenuated by these pharmacological inhibitors. These results suggested that MVS induces AP-1/HO-1 expression via PKCα/Pyk2/p38α MAPK- or JNK1/2-dependent c-Jun activation, which further binds with AP-1-binding site on HO-1 promoter and suppresses the TNFα-mediated inflammatory responses in HPAEpiCs. Thus, upregulation of the AP-1/HO-1 system by MVS exerts a potentially therapeutic strategy to protect against pulmonary inflammation.

Induction of HO-1 by Mevastatin Mediated via a Nox/ROS-Dependent c-Src/PDGFRα/PI3K/Akt/Nrf2/ARE Cascade Suppresses TNF-α-Induced Lung Inflammation

Background: Mevastatin (MVS), a 3-hydroxy-3-methylglutaryl coenzyme, a reductase (HMG-CoA) inhibitor, has anti-inflammatory effects potentially via up-regulation of heme oxygenase-1 (HO-1). However, the mechanisms underlying MVS-induced HO-1 expression remain largely unknown in human pulmonary alveolar epithelial cells (HPAEpiCs). Methods: HO-1 and intercellular adhesion molecule (ICAM)-1 expression were determined using real-time PCR, Western blotting, and promoter reporter analyses. The signaling components were investigated using pharmacological inhibitors or specific small interfering RNA (siRNA)s. Interaction between Nrf2 and the antioxidant response element (ARE) binding site for the HO-1 promoter was determined by chromatin immunoprecipitation (ChIP) assay. Results: Upregulation of HO-1 by MVS attenuated the tumor necrosis factor (TNF)-α-stimulated ICAM-1 expression associated with THP-1 adhesion to HPAEpiCs. These inhibitory effects of HO-1 were reversed by tin protoporphyrin (SnPP)IX or by transfection with HO-1 siRNA. MVS-induced HO-1 expression was mediated via NADPH oxidase (Nox)-derived reactive oxygen species (ROS) generation. Activation of Nox2/ROS further stimulated the phosphorylation of p47^phox, proto-oncogene tyrosine-protein kinase (c-Src), platelet-derived growth factor receptor (PDFGR)α, protein kinase B (Akt), and Nrf2, which were inhibited by siRNAs. Pretreatment with pharmacological inhibitors, including diphenyleneiodonium (DPI), apocynin (APO), N-acetyl-L-cysteine (NAC), PP1, AG1296, or LY294002, reduced the MVS-activated Nrf2 nuclear-translocation binding to the ARE on the HO-1 promoter. Conclusions: MVS-induced HO-1 is, at least in part, mediated through a p47^phox/Nox2/ROS-dependent activation of c-Src/PDGFRα/PI3K/Akt-regulated Nrf2/ARE axis and suppresses the TNF-α-mediated inflammatory responses in HPAEpiCs.

SIK2 enhances synthesis of fatty acid and cholesterol in ovarian cancer cells and tumor growth through PI3K/Akt signaling pathway

Salt-inducible kinase 2 (SIK2) has been established as a regulator of diverse biological processes including cell metabolism. A recent study has reported that SIK2 is required for adipocyte-induced ovarian cancer (OC) survival through facilitating fatty acid oxidation. However, whether SIK2 also plays a role in the lipid synthesis in OC cells remains elusive. Here, we showed that SIK2 significantly promoted the lipid synthesis in OC cells. On the one hand, SIK2 enhanced fatty acid synthesis through upregulating the expression of sterol regulatory element binding protein 1c (SREBP1c) and thus the transcription of major lipogenic enzyme FASN. On the other hand, SIK2 promoted cholesterol synthesis through upregulating the expression of sterol regulatory element binding protein 2 (SREBP2) and thus the transcription of major cholesterol synthesis enzymes HMGCR. Moreover, PI3K/Akt signaling pathway was found to be involved in the upregulation of SREBP1c and SREBP2 in OC cells. Moreover, in vitro and in vivo assays indicated that the SIK2-regulated fatty acid and cholesterol synthesis played a critical role in the growth of OC cells. Our findings demonstrate that SIK2 is a critical regulator of lipid synthesis in OC cells and thus promotes OC growth, which provides a strong line of evidence for this molecule to be used as a therapeutic target in the treatment of this malignancy.

Protective effects of essential oil from Fructus Alpiniae zerumbet on retinal Müller gliosis via the PPAR-γ-p-CREB signaling pathway

Background

Diabetic retinopathy (DR) involves extensive retinal damage and is one of the most common and serious complications of diabetes mellitus. Hyperglycemia is the major pathological trigger for diabetic complications. Müller cell gliosis, a key pathophysiological process in DR, could finally lead to vision loss. Our previous finding revealed that the essential oil of Fructus Alpiniae zerumbet (EOFAZ) protects human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced injury via the PPAR-γ signal. However, Whether EOFAZ could prevent HG-induced Müller cell gliosis through the PPAR signaling remains unclear.

Methods

The neuroprotective effects of EOFAZ were evaluated in HG-treated rat retinal Müller cells (RMCs) and DR rat model.

Result

GFAP and VEGF upregulation is the biomarker of Müller glial reactivity gliosis. Results suggested that EOFAZ could remarkably ameliorate retinal reactive gliosis by suppressing p-CREB and GFAP and VEGF downstream effectors. Its effects on PPAR-γ, a major target for currently available anti-diabetes drugs, were also investigated. EOFAZ treatment remarkably attenuated the reduction of PPAR-γ and high level of p-CaMK II and p-CREB in HG-treated RMCs and diabetic rats. Furthermore, the activation and ectopic expression of PPAR-γ downregulated p-CREB and p-CaMK II in HG-treated RMCs. By contrast, CaMK II inhibitor KN93 and CREB gene silencing did not significantly affect the PPAR-γ expression.

Conclusions

A novel PPAR-γ-p-CREB signaling pathway accounts for the inhibitory effect of EOFAZ on RMCs gliosis. These findings provide scientific evidence for the potential use of EOFAZ as a complementary and alternative medicine for DR prevention and treatment in the future.

Role of the mTOR‑FOXO1 pathway in obesity‑associated renal tubulointerstitial inflammation

Since obesity is largely responsible for the growing incidence of renal tubulointerstitial inflammation, exploration into the mechanisms of obesity‑associated tubulointerstitial inflammation is essential. Studies have demonstrated that mammalian target of rapamycin (mTOR) is a crucial molecule in the pathogenesis of renal inflammation, including regulating the expression of inflammatory factors. The purpose of the present study was to further elucidate the role of mTOR in obesity‑associated tubulointerstitial inflammation. In the clinical study, obese and healthy subjects were recruited for physical examination, as well as the collection of blood and urine samples. Further study was performed on a high fat diet (HFD)‑induced obese rat model and a cultured human renal tubular epithelial cell line (HK‑2). The clinical study demonstrated that the participants with obesity had increased serum lipids, creatinine (Cr), urinary albumin to creatinine ratio (UACR) and urinary neutrophil gelatinase‑associated lipocalin (u‑NGAL). Moreover, the level of urinary monocyte chemoattractant protein‑1 (u‑MCP‑1) was increased in the participants with obesity, and it was positively correlated with free fatty acid (FFA), UACR and u‑NGAL. In the in vivo study, the results indicated that the levels of serum lipids, Cr and blood urea nitrogen (BUN), as well as 24 h urine protein and u‑NGAL, were significantly increased in the HFD‑fed obese rats. In addition, the infiltration of CD68+ cells into the renal interstitial area and the release of interleukin‑1β (IL‑1β) was observed in the kidneys of obese rats. Meanwhile, the supernatant from HK‑2 cells treated with palmitic acid stimulated THP‑1 monocyte migration. The upregulation of MCP‑1, phosphorylated forkhead boxO1 (p‑FOXO1), and phosphorylated mTOR (p‑mTOR) was observed in vivo and in vitro. However, inhibition of mTOR was able to alleviate the above effects. Overall, these results demonstrated that activated mTOR induced FOXO1 phosphorylation, which mediates renal MCP‑1 release, causes tubulointerstitial inflammation and ultimately leads to pathological renal changes and dysfunction. However, inhibition of mTOR may play a renoprotective role during the progression of obesity‑associated tubulointerstitial inflammation.

Lysophosphatidylcholine induces cyclooxygenase-2-dependent IL-6 expression in human cardiac fibroblasts

Lysophosphatidylcholine (LysoPC) has been shown to induce the expression of inflammatory proteins, including cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6), associated with cardiac fibrosis. Here, we demonstrated that LysoPC-induced COX-2 and IL-6 expression was inhibited by silencing NADPH oxidase 1, 2, 4, 5; p65; and FoxO1 in human cardiac fibroblasts (HCFs). LysoPC-induced IL-6 expression was attenuated by a COX-2 inhibitor. LysoPC-induced responses were mediated via the NADPH oxidase-derived reactive oxygen species-dependent JNK1/2 phosphorylation pathway, leading to NF-κB and FoxO1 activation. In addition, we demonstrated that both FoxO1 and p65 regulated COX-2 promoter activity stimulated by LysoPC. Overexpression of wild-type FoxO1 and S256D FoxO1 enhanced COX-2 promoter activity and protein expression in HCFs. These results were confirmed by ex vivo studies, where LysoPC-induced COX-2 and IL-6 expression was attenuated by the inhibitors of NADPH oxidase, NF-κB, and FoxO1. Our findings demonstrate that LysoPC-induced COX-2 expression is mediated via NADPH oxidase-derived reactive oxygen species generation linked to the JNK1/2-dependent pathway leading to FoxO1 and NF-κB activation in HCFs. LysoPC-induced COX-2-dependent IL-6 expression provided novel insights into the therapeutic targets of the cardiac fibrotic responses.

Sphingosine-1-phosphate induces airway smooth muscle cell proliferation, migration, and contraction by modulating Hippo signaling effector YAP

Sphingosine-1-phosphate (S1P), a bioactive lipid, has been shown to be elevated in the airways of individuals with asthma and modulates the airway smooth muscle cell (ASMC) functions, yet its underlying molecular mechanisms are not completely understood. The aim of the present study is to address this issue. S1P induced yes-associated protein (YAP) dephosphorylation and nuclear localization via the S1PR_2/3/Rho-associated protein kinase (ROCK) pathway, and this in turn increased forkhead box M1 (FOXM1) and cyclin D1 expression leading to ASMC proliferation, migration, and contraction. Pretreatment of cells with S1PR₂ antagonist JTE013, S1PR₃ antagonist CAY10444, or ROCK inhibitor Y27632 blocked S1P-induced alterations of YAP, FOXM1, cyclin D1, and ASMC proliferation, migration, and contraction. In addition, prior silencing of YAP or FOXM1 with siRNA reversed the effect of S1P on ASMC functions. Taken together, our study indicates that S1P stimulates ASMC proliferation, migration, and contraction by binding to S1PR_2/3 and modulating ROCK/YAP/FOXM1 axis and suggests that targeting this pathway might have potential value in the management of asthma.

The free fatty acid receptor 1 promotes airway smooth muscle cell proliferation through MEK/ERK and PI3K/Akt signaling pathways

Obesity is a risk factor for asthma and influences airway hyperresponsiveness, which is in part modulated by airway smooth muscle proliferative remodeling. Plasma free fatty acids (FFAs) levels are elevated in obese individuals, and long-chain FFAs act as endogenous ligands for the free fatty acid receptor 1 (FFAR1), which couples to both G_q and G_i proteins. We examined whether stimulation of FFAR1 induces airway smooth muscle cell proliferation through classical MEK/ERK and/or phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. The long-chain FFAs (oleic acid and linoleic acid) and a FFAR1 agonist (GW9508) induced human airway smooth muscle (HASM) cell proliferation, which was inhibited by the MEK inhibitor U0126 and the PI3K inhibitor LY294002 . The long-chain FFAs and GW9508 increased phosphorylation of ERK, Akt, and p70S6K in HASM cells and freshly isolated rat airway smooth muscle. Downregulation of FFAR1 in HASM cells by siRNA significantly attenuated oleic acid-induced phosphorylation of ERK and Akt. Oleic acid-induced ERK phosphorylation was blocked by either the Gα_i-protein inhibitor pertussis toxin or U0126 and was partially inhibited by either the Gα_q-specific inhibitor YM-254890 or the Gβγ signaling inhibitor gallein. Oleic acid significantly inhibited forskolin-stimulated cAMP activity, which was attenuated by pertussis toxin. Akt phosphorylation was inhibited by pertussis toxin, the ras inhibitor manumycin A, the Src inhibitor PP1, or LY294002 . Phosphorylation of p70S6K by oleic acid or GW9508 was significantly inhibited by LY294002 , U0126, and the mammalian target of rapamycin (mTOR) inhibitor rapamycin. In conclusion, the FFAR1 promoted airway smooth muscle cell proliferation and p70S6K phosphorylation through MEK/ERK and PI3K/Akt signaling pathways.

Fructose, but not glucose, impairs insulin signaling in the three major insulin-sensitive tissues

Human studies support the relationship between high intake of fructose-sweetened beverages and type 2 diabetes, but there is a debate on whether this effect is fructose-specific or it is merely associated to an excessive caloric intake. Here we investigate the effects of 2 months' supplementation to female rats of equicaloric 10% w/v fructose or glucose solutions on insulin sensitivity in target tissues. Fructose supplementation caused hepatic deposition of triglycerides and changed the fatty acid profile of this fraction, with an increase in monounsaturated and a decrease in polyunsaturated species, but did not cause inflammation and oxidative stress. Fructose but not glucose-supplemented rats displayed an abnormal glucose tolerance test, and did not show increased phosphorylation of V-akt murine thymoma viral oncogene homolog-2 (Akt) in white adipose tissue and liver after insulin administration. In skeletal muscle, phosphorylation of Akt and of Akt substrate of 160 kDA (AS160) was not impaired but the expression of the glucose transporter type 4 (GLUT4) in the plasma membrane was reduced only in fructose-fed rats. In conclusion, fructose but not glucose supplementation causes fatty liver without inflammation and oxidative stress and impairs insulin signaling in the three major insulin-responsive tissues independently from the increase in energy intake.

Inhibition of hypoxia-induced cyclooxygenase-2 by Korean Red Ginseng is dependent on peroxisome proliferator-activated receptor gamma

Background

Korean Red Ginseng (KRG) is a traditional herbal medicine made by steaming and drying fresh ginseng. It strengthens the endocrine and immune systems to ameliorate various inflammatory responses. The cyclooxygenase-2 (COX-2)/prostaglandin E2 pathway has important implications for inflammation responses and tumorigenesis. Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor that regulates not only adipogenesis and lipid homeostasis, but also angiogenesis and inflammatory responses.

Methods

The effects of the KRG on inhibition of hypoxia-induced COX-2 via PPARγ in A549 cells were determined by luciferase assay, Western blot, and/or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The antimigration and invasive effects of KRG were evaluated on A549 cells using migration and matrigel invasion assays.

Results and conclusion

We previously reported that hypoxia-induced COX-2 protein and mRNA levels were suppressed by KRG. This study examines the possibility of PPARγ as a cellular target of KRG for the suppression of hypoxia-induced COX-2. PPARγ protein levels and PPARγ-responsive element (PPRE)-driven reporter activities were increased by KRG. Reduction of hypoxia-induced COX-2 by KRG was abolished by the PPARγ inhibitor GW9662. In addition, the inhibition of PPARγ abolished the effect of KRG on hypoxia-induced cell migration and invasion.

Discussion

Our results show that KRG inhibition of hypoxia-induced COX-2 expression and cell invasion is dependent on PPARγ activation, supporting the therapeutic potential for suppression of inflammation under hypoxia. Further studies are required to demonstrate whether KRG activates directly PPARγ and to identify the constituents responsible for this activity.

Mevastatin ameliorates sphingosine 1-phosphate-induced COX-2/PGE2-dependent cell migration via FoxO1 and CREB phosphorylation and translocation

BACKGROUND AND PURPOSE

Sphingosine 1-phosphate (S1P), an important inflammatory mediator, has been shown to regulate COX-2 production and promote various cellular responses such as cell migration. Mevastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA), effectively inhibits inflammatory responses. However, the mechanisms underlying S1P-evoked COX-2-dependent cell migration, which is modulated by mevastatin in human tracheal smooth muscle cells (HTSMCs) remain unclear.

EXPERIMENTAL APPROACH

The expression of COX-2 was determined by Western blotting, real time-PCR and promoter analyses. The signalling molecules were investigated by pretreatment with respective pharmacological inhibitors or transfection with siRNAs. The interaction between COX-2 promoter and transcription factors was determined by chromatin immunoprecipitation assay. Finally, the effect of mevastatin on HTSMC migration and leukocyte counts in BAL fluid and COX-2 expression induced by S1P was determined by a cell migration assay, cell counting and Western blot.

KEY RESULTS

S1P stimulated mTOR activation through the Nox2/ROS and PI3K/Akt pathways, which can further stimulate FoxO1 phosphorylation and translocation to the cytosol. We also found that S1P induced CREB activation and translocation via an mTOR-independent signalling pathway. Finally, we showed that pretreatment with mevastatin markedly reduced S1P-induced cell migration and COX-2/PGE2 production via a PPARγ-dependent signalling pathway.

CONCLUSIONS AND IMPLICATIONS

Mevastatin attenuates the S1P-induced increased expression of COX-2 and cell migration via the regulation of FoxO1 and CREB phosphorylation and translocation by PPARγ in HTSMCs. Mevastatin could be beneficial for prevention of airway inflammation in the future.