Involvement of COX-2/PGE(2) Pathway in the Upregulation of MMP-9 Expression in Pancreatic Cancer. Gastroenterol Res Pract. 2011;2011:214269. [PMID: 21760774 DOI: 10.1155/2011/214269]

Molecular insights in repurposing selective COX-2 inhibitor celecoxib against matrix metalloproteinases in potentiating delayed wound healing: a molecular docking and MMPB/SA based analysis of molecular dynamic simulations

Matrix metalloproteinases (MMPs) are proteolytic enzymes that play a role in healing, including reducing inflammation, promoting fibroblast and keratinocyte migration, and modifying scar tissue. Due to their pleiotropic functions in the wound-healing process in diabetic wounds, MMPs constitute a significant cause of delayed wound closure. COX-2 inhibitors are proven to inhibit inflammation. The present study aims to repurpose celecoxib against MMP-2, MMP-8 and MMP-9 through in silico approaches, such as molecular docking, molecular dynamics, and MMPB/SA analysis. We considered five selective COX-2 inhibitors (celecoxib, etoricoxib, lumiracoxib, rofecoxib and valdecoxib) for our study against MMPs. Based on molecular docking study and hydrogen bonding pattern, celecoxib in complex with three MMPs was further analyzed using 1 µs (1000 ns) molecular dynamics simulation and MMPB/SA techniques. These studies identified that celecoxib exhibited significant binding affinity -8.8, -7.9 and -8.3 kcal/mol, respectively, against MMP-2, MMP-8 and MMP-9. Celecoxib formed hydrogen bonding and hydrophobic (π-π) interactions with crucial substrate pocket amino acids, which may be accountable for their inhibitory nature. The MMPB/SA studies showed that electrostatic and van der Waal energy terms favoured the total free binding energy component, while polar solvation terms were highly disfavored. The in silico analysis of the secondary structures showed that the celecoxib binding conformation maintains relatively stable along the simulation trajectories. These findings provide some key clues regarding the accommodation of celecoxib in the substrate binding S1' pocket and also provide structural insights and challenges in repurposing drugs as new MMP inhibitors with anti-inflammatory and anti-inflammatory wound-healing properties.Communicated by Ramaswamy H. Sarma.

Cannabinoids Transmogrify Cancer Metabolic Phenotype via Epigenetic Reprogramming and a Novel CBD Biased G Protein-Coupled Receptor Signaling Platform

The concept of epigenetic reprogramming predicts long-term functional health effects. This reprogramming can be activated by exogenous or endogenous insults, leading to altered healthy and different disease states. The exogenous or endogenous changes that involve developing a roadmap of epigenetic networking, such as drug components on epigenetic imprinting and restoring epigenome patterns laid down during embryonic development, are paramount to establishing youthful cell type and health. This epigenetic landscape is considered one of the hallmarks of cancer. The initiation and progression of cancer are considered to involve epigenetic abnormalities and genetic alterations. Cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer development, including DNA methylation, histone modifications, nucleosome positioning, non-coding RNAs, and microRNA expression. Endocannabinoids are natural lipid molecules whose levels are regulated by specific biosynthetic and degradative enzymes. They bind to and activate two primary cannabinoid receptors, type 1 (CB1) and type 2 (CB2), and together with their metabolizing enzymes, form the endocannabinoid system. This review focuses on the role of cannabinoid receptors CB1 and CB2 signaling in activating numerous receptor tyrosine kinases and Toll-like receptors in the induction of epigenetic landscape alterations in cancer cells, which might transmogrify cancer metabolism and epigenetic reprogramming to a metastatic phenotype. Strategies applied from conception could represent an innovative epigenetic target for preventing and treating human cancer. Here, we describe novel cannabinoid-biased G protein-coupled receptor signaling platforms (GPCR), highlighting putative future perspectives in this field.

Fisetin suppresses cigarette smoke extract-induced epithelial to mesenchymal transition of airway epithelial cells through regulating COX-2/MMPs/β-catenin pathway

Cigarette smoke exposure leads to upregulation of cyclooxygenase-2 (COX-2), an inducible enzyme that synthesizes prostaglandin E2 (PGE2) and promotes airway inflammation. COX-2 overexpression is frequently implicated in inflammation, invasion, metastasis, and epithelial-mesenchymal transition (EMT). However, its detailed molecular mechanism in cigarette smoke induced EMT is not clear. Further, fisetin, a bioflavonoid, exhibits antioxidant and anti-inflammatory properties, but its effect in modulating COX-2-mediated inflammation and downstream sequelae remains unexplored. Therefore, we have investigated the mechanism of cigarette smoke-induced COX-2-mediated EMT in airway epithelial cells and examined the role of fisetin in controlling this aberration. MTT, trypan blue staining, gelatin zymography, Western blotting, invasion, wound healing, and tumor sphere formation assays in cigarette smoke extract (CSE) and/or fisetin treated airway epithelial cells, and in-silico molecular docking studies were performed. Results revealed that CSE exposure increased the expression and activity of COX-2, MMP-2/9, and β-catenin and also enhanced expression of EMT markers leading to higher migration and invasion potential of airway epithelial cells. A specific COX-2 inhibitor NS-398 as well as fisetin treatment reversed the expression of EMT biomarkers, reduced the activity of MMP-2/9, and blocked the migration and invasion potential induced by CSE. Further, PGE2 also increased MMPs activity, invasion, and migration potential similar to CSE, which were significantly reversed by fisetin. In-silico studies showed a high binding affinity of fisetin to key EMT associated proteins, validating its anti-EMT potential. Thus, our study firstly unearths the mechanism of CSE-induced EMT in airway epithelial cells via COX-2/MMP/β-catenin pathway, and secondly, it reveals that fisetin could significantly reverse CSE-induced EMT by inhibiting COX-2, indicating that fisetin could be an effective drug candidate for cigarette smoke-induced lung dysfunction.

Regenerative Effects of Hypoxia Primed Flowable Placental Formulation in Muscle and Dermal Injury

The placental tissue, due to its angiogenic, anti-inflammatory, antioxidative, antimicrobial, and anti-fibrotic properties, has become a compelling source towards a solution for several indications in regenerative medicine. However, methods to enhance and capture the therapeutic properties with formulations that can further the applications of viable placental tissue have not been explored. In this study, we investigated the regenerative effects of a hypoxia primed flowable placental formulation (FPF), composed of amnion/chorion and umbilical tissue, in two in vivo injury models. Laser Doppler data from rodent ischemia hindlimbs treated with FPF revealed significant tissue perfusion improvements compared to control ischemic hindlimbs. To further corroborate FPF's effects, we used a rodent ischemic bipedicle skin flap wound model. FPF treatment significantly increased the rate of wound closure and the quality of wound healing. FPF-treated wounds displayed reduced inflammation and an increase in angiogenesis. Furthermore, quantitative PCR and next-generation sequencing analysis confirmed these changes in the FPF-treated group at both the gene and transcriptional level. The observed modulation in miRNAs was associated with angiogenesis, regulation of inflammatory microenvironment, cell migration and apoptosis, reactive oxygen species generation, and restoring epithelial barrier function, all processes involved in impaired tissue healing. Taken together, these data validate the tissue regenerative properties of the flowable placental formulation configuration tested.

Mucin 5AC is significantly upregulated in exosomes from the nasal lavage fluid and may promote the expression of COX-2, VEGF and MMP-9: an implication in nasal polyp pathogenesis

BACKGROUND

Exosomes are critical mediators of intercellular communication and could be involved in many human diseases; however, little is known about the role of exosomes in nasal polyps (NP).

METHODS

Exosomes in nasal lavage fluids (NLF) were isolated by ultracentrifugation. Exosome identity was validated by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and specific exosomal markers. The exosome proteome was revealed by LC-MS/MS, and the expression of the candidate exosomal protein, mucin 5AC, was confirmed by Western blot analysis and immunohistochemistry (IHC). Cellular uptake of the exosomes was monitored by fluorescence confocal microscopy and the ensuing effects on COX-2, VEGF and MMP-2/MMP-9 were determined by Western blotting, ELISA and gelatin zymography, respectively.

RESULTS

Mass spectrometry analysis and subsequent verification by Western blotting identified that mucin 5AC was significantly upregulated in exosomes from NLFs of NP patients. Moreover, the expression of mucin 5AC was increased in the tissue specimens of the NP patients. Functional assays suggest that the mucin 5 AC-enriched exosomes could be effectively taken up by chronic rhinosinusitis without NP (CRSsNP)-derived fibroblasts, the control cells, resulting in a significant increase in the expression of COX-2, VEGF and MMP-9.

CONCLUSIONS

Mucin 5AC, the major airway mucin, cannot only be carried and transferred by nasal exosomes, but may also promote tissue remodeling and angiogenesis and thus could be a potential therapeutic target of NP.

Assessment of the correlation between oxidative stress and expression of MMP-2, TIMP-1 and COX-2 in human aortic smooth muscle cells

INTRODUCTION

Smooth muscle cells (SMCs) are considered to be the main producer of matrix metalloproteinase-2 (MMP-2) participating primarily in extracellular matrix (ECM) remodeling. Any disturbances in ECM structure may underlie the pathogenesis of many cardiovascular diseases and contribute to angiogenesis, cancer development, invasion or metastasis. The purpose of the study was to examine the effect of oxidative stress on the expression of MMP-2, its tissue inhibitor type 1 (TIMP-1) and cyclooxygenase-2 (COX-2) in human aortic smooth muscle cells (HASMCs).

MATERIAL AND METHODS

HASMCs were treated with exogenously applied H₂O₂ or TNF-α. N-acetylcysteine (NAC) was used as an antioxidant. Gene expression levels were measured by real-time PCR and the protein levels were determined using ELISA assay.

RESULTS

The studies revealed no association between oxidative stress and either mRNA quantity or protein secretion of MMP-2 and TIMP-1. However, we found markedly reduced (p < 0.001) MMP-2 secretion in cells incubated with NAC. HASMCs stimulated with TNF-α demonstrated a significantly increased COX-2 mRNA level as well as enzyme activity. H₂O₂-induced cells showed lowered COX-2 activity in comparison to untreated cells. MMP-2 and TIMP-1 expression did not change after COX-2 inhibition with DuP-697.

CONCLUSIONS

We did not find any effect of oxidative stress on expression of MMP-2 and TIMP-1 in HASMCs. However, COX-2 mRNA and protein level were elevated in these conditions. There was no correlation between COX-2 activity and MMP-2 and TIMP-1 mRNA expression or protein secretion.

The COX-2-derived PGE2 autocrine contributes to bradykinin-induced matrix metalloproteinase-9 expression and astrocytic migration via STAT3 signaling

Background

The matrix metalloproteinase-9 (MMP-9) is up-regulated by several proinflammatory mediators in the central nervous system (CNS) diseases. Increasing reports show that MMP-9 expression is an inflammatory biomarker of several CNS disorders, including the CNS inflammation and neurodegeneration. Bradykinin (BK) is a common proinflammatory mediator and elevated in several brain injury and inflammatory disorders. The raised BK may be detrimental effects on the CNS that may aggravate brain inflammation through MMP-9 up-regulation or cyclooxygenase-2 (COX-2)-derived prostaglandin E₂ (PGE₂) production in brain astrocytes. However, the relationship between BK-induced MMP-9 expression and COX-2-derived PGE₂ release in brain astrocytes remains unclear.

Methods

Herein we used rat brain astrocytes (RBA) to investigate the role of the COX-2/PGE₂ system in BK-induced MMP-9 expression. We used zymographic, RT-PCR, EIA, and Western blotting analyses to confirm that BK induces MMP-9 expression via a COX-2/PGE₂-dependent pathway.

Results

Our results show activation of native COX-2 by BK led to PGE₂ production and release. Subsequently, PGE₂ induced MMP-9 expression via PGE₂ receptor (EP)-mediated c-Src, Jak2, ERK1/2, and then activated signal transducer and activator of transcription 3 (STAT3) signaling pathway. Finally, up-regulation of MMP-9 by BK via the pathway may promote astrocytic migration.

Conclusion

These results demonstrated that a novel autocrine pathway for BK-induced MMP-9 protein expression is mediated through activation of STAT3 by native COX-2/PGE₂-mediated c-Src/Jak2/ERK cascades in brain astrocytes.

Genetic Deletion or Pharmacological Inhibition of Cyclooxygenase-2 Reduces Blood-Brain Barrier Damage in Experimental Ischemic Stroke

Cyclooxygenase (COX)-2 and matrix metalloproteinase (MMP)-9 are two crucial mediators contributing to blood-brain barrier (BBB) damage during cerebral ischemia. However, it is not known whether MMP-9 activation is involved in COX-2-mediated BBB disruption in ischemic stroke. In this study, we hypothesized that genetic deletion or pharmacological inhibition of COX-2 reduces BBB damage by reducing MMP-9 activity in a mouse model of ischemic stroke. Male COX-2 knockout (COX-2^-/-) and wild-type (WT) mice were subjected to 60 min of middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. Genetic deletion of COX-2 or post-ischemic treatment with CAY10404, a highly selective COX-2 inhibitor, significantly reduced BBB damage and hemorrhagic transformation, as assessed by immunoglobulin G (IgG) extravasation and brain hemoglobin (Hb) levels, respectively. Immunoblotting analysis showed that tight junction proteins (TJPs) zonula occludens (ZO)-1 and occludin as well as junctional adhesion molecule-A (JAM-A) and the basal lamina protein collagen IV were dramatically reduced in the ischemic brain. Stroke-induced loss of these BBB structural proteins was significantly attenuated in COX-2^-/- mice. Similarly, stroke-induced loss of ZO-1 and occludin was significantly attenuated by CAY10404 treatment. Ischemia-induced increase in MMP-9 protein levels in the ipsilateral cerebral cortex was significantly reduced in COX-2^-/- mice. Stroke induced a dramatic increase in MMP-9 enzymatic activity in the ischemic cortex, which was markedly reduced by COX-2 gene deficiency or pharmacological inhibition with CAY10404. Levels of myeloperoxidase (MPO, an indicator of neutrophil infiltration into the brain parenchyma), neutrophil elastase (NE), and lipocalin-2 (LCN2, also known as neutrophil gelatinase-associated lipocalin), measured by western blot and specific ELISA kits, respectively, were markedly increased in the ischemic brain. Increased levels of markers for neutrophil infiltration were significantly reduced in COX-2^-/- mice compared with WT controls following stroke. Altogether, neurovascular protective effects of COX-2 blockade are associated with reduced BBB damage, MMP-9 expression/activity and neutrophil infiltration. Our study shows for the first time that MMP-9 is an important downstream effector contributing to COX-2-mediated neurovascular damage in ischemic stroke. Targeting the COX-2/MMP-9 pathway could represent a promising strategy to reduce neuroinflammatory events in order to preserve the BBB integrity and ameliorate ischemic stroke injury.

Gamma-Linolenic acid alters migration, proliferation and apoptosis in human and rat glioblastoma cells

Glioblastoma multiforme (GBM) is the most malignant astrocytoma, the main treatments consist of surgical resection followed by radiotherapy and chemotherapy. Patients, after diagnosed, have a survival rate of one year. GBM cells have an invasive, proliferative and migratory characteristic, also they do not respond properly for usual cancer treatment (radiotherapy, chemotherapy). Fatty acids have been studied as an adjuvant cancer treatment in breast, colorectal and GBM. The fatty acid can alter tumoural cell metabolism causing a modification of eicosanoids production. This study has observed some cellular aspects modified by fatty acid treatment in vitro, using GBM cells (human and rat). Modifications in cell behaviour were analyzed like cell proliferation, apoptosis, migration and invasion cell capacity after treatment with fatty acid (gamma-linolenic acid). The treatment suggested in this study showed an increased number of apoptotic cells and a decreased number of proliferative and migratory cells. These data recognize that gamma-linolenic acid could be used as an alternative treatment for glioblastoma.

Pancreatic cancer cell-derived exosomal microRNA-27a promotes angiogenesis of human microvascular endothelial cells in pancreatic cancer via BTG2

Pancreatic cancer (PC) remains a primary cause of cancer-related deaths worldwide. Existing literature has highlighted the oncogenic role of microRNA-27a (miR-27a) in multiple cancers. Hence, the current study aimed to clarify the potential therapeutic role of PC cell-derived exosomal miR-27a in human microvascular endothelial cell (HMVEC) angiogenesis in PC. Initially, differentially expressed genes (DEGs) and miRs related to PC were identified by microarray analysis. Microarray analysis provided data predicting the interaction between miR-27a and BTG2 in PC, which was further verified by the elevation or depletion of miR-27a. Next, the expression of miR-27a and BTG2 in the PC tissues was quantified. HMVECs were exposed to exosomes derived from PC cell line PANC-1 to investigate the effects associated with PC cell-derived exosomes carrying miR-27a on HMVEC proliferation, invasion and angiogenesis. Finally, the effect of miR-27a on tumorigenesis and microvessel density (MVD) was analysed after xenograft tumour inoculation in nude mice. Our results revealed that miR-27a was highly expressed, while BTG2 was poorly expressed in both PC tissues and cell lines. miR-27a targeted BTG2. Moreover, miR-27a silencing inhibited PC cell proliferation and invasion, and promoted apoptosis through the elevation of BTG2. The in vitro assays revealed that PC cell-derived exosomes carrying miR-27a stimulated HMVEC proliferation, invasion and angiogenesis, while this effect was reversed in the HMVECs cultured with medium containing GW4869-treated PANC-1 cells. Furthermore, in vivo experiment revealed that miR-27a knockdown suppressed tumorigenesis and MVD. Taken together, cell-derived exosomes carrying miR-27a promotes HMVEC angiogenesis via BTG2 in PC.

Dicentrine Potentiates TNF-α-Induced Apoptosis and Suppresses Invasion of A549 Lung Adenocarcinoma Cells via Modulation of NF-κB and AP-1 Activation

Numerous studies have indicated that tumor necrosis factor-alpha (TNF-α) could induce cancer cell survival and metastasis via activation of transcriptional activity of NF-κB and AP-1. Therefore, the inhibition of TNF-α-induced NF-κB and AP-1 activity has been considered in the search for drugs that could effectively treat cancer. Dicentrine, an aporphinic alkaloid, exerts anti-inflammatory and anticancer activities. Therefore, we investigated the effects of dicentrine on TNF-α-induced tumor progression in A549 lung adenocarcinoma cells. Our results demonstrated that dicentrine effectively sensitizes TNF-α-induced apoptosis in A549 cells when compared with dicentrine alone. In addition, dicentrine increases caspase-8, -9, -3, and poly (ADP-ribose) polymerase (PARP) activities by upregulating the death-inducing signaling complex and by inhibiting the expression of antiapoptotic proteins including cIAP2, cFLIP, and Bcl-XL. Furthermore, dicentrine inhibits the TNF-α-induced A549 cells invasion and migration. This inhibition is correlated with the suppression of invasive proteins in the presence of dicentrine. Moreover, dicentrine significantly blockes TNF-α-activated TAK1, p38, JNK, and Akt, leading to reduced levels of the transcriptional activity of NF-κB and AP-1. Taken together, our results suggest that dicentrine could enhance TNF-α-induced A549 cell death by inducing apoptosis and reducing cell invasion due to, at least in part, the suppression of TAK-1, MAPK, Akt, AP-1, and NF-κB signaling pathways.

Tumor-associated macrophages induce invasion and poor prognosis in human gastric cancer in a cyclooxygenase-2/MMP9-dependent manner

Cyclooxygenase-2 (COX2) and tumor-associated macrophages (TAMs) are associated with invasion, angiogenesis, and poor prognosis in many human cancers. However, the role of TAMs in human gastric cancer (GC) remains elusive. In the present study, we first measured COX2 expression and TAM infiltration in human GC tissues using double immunohistochemical staining. Then, we indirectly cocultured M2-polarized macrophages derived from human THP-1 cells with GC cells as an in vitro model. Transwell assays, siRNA transfection, treatment with a COX2 inhibitor and Western blotting were used to investigate the relationship among TAMs, invasion and COX2 expression as well as the underlying molecular mechanism. Double IHC staining showed that TAMs were aggregated near GC tumor nests and had high COX2 expression; moreover, the number of TAMs that infiltrated the tumor nest was correlated with the depth of invasion, COX2 expression and poor prognosis in human GC. In an in vitro assay, after treatment with phorbol myristate acetate (PMA), the THP-1 cells differentiated into M2 macrophages and induced COX2/MMP9-dependent invasiveness in GC cells. Pretreatment of GC cells with COX2 siRNA or a COX2 inhibitor (Celecoxib) can negate these promoting effects. The results of this study and those of our previous studies indicate that coculture with M2-polarized macrophages can induce the COX2-dependent release of matrix metalloproteinase-9 (MMP9), which subsequently increases the invasiveness of GC cells. Our data may provide a basis for targeting TAMs or for polarizing TAMs through immune regulation to halt GC progression, which could soon become a nonsurgical treatment for human gastric cancer.

Up-regulation of COX-2 and mPGES-1 by 27-hydroxycholesterol and 4-hydroxynonenal: A crucial role in atherosclerotic plaque instability

Atherosclerosis is currently understood to be mainly the consequence of a complicated inflammatory process at the different stages of plaque development. Among the several inflammatory molecules involved, up-regulation of the functional cyclooxygenase 2/membrane-bound prostaglandin E synthase 1 (COX-2/mPGES-1) axis plays a key role in plaque development. Excessive production of oxidized lipids, following low-density lipoprotein (LDL) oxidation, is a characteristic feature of atherosclerosis. Among the oxidized lipids of LDLs, the oxysterol 27-hydroxycholesterol (27-OH) and the aldehyde 4-hydroxynonenal (HNE) substantially accumulate in the atherosclerotic plaque, contributing to its progression and instability through a variety of processes. This study shows that 27-OH and HNE promote up-regulation of both the inducible enzymes COX-2 and mPGES-1, leading to increased production of prostaglandin (PG) E₂ and inducible nitric oxide synthase, and the subsequent release of nitric oxide in human promonocytic U937 cells. The study also examined the potential involvement of the functionally coupled COX-2/mPGES-1 in enhancing the production of certain pro-inflammatory cytokines and of matrix metalloproteinase 9 by U937 cells. This enhancement is presumably due to the induction of PGE₂ synthesis, as a result of the up-regulation of the COX-2/mPGES-1, stimulated by the two oxidized lipids, 27-OH and HNE. Induction of PGE₂ synthesis might thus be a mechanism of plaque instability and eventual rupture, contributing to matrix metalloproteinase production by activated macrophages.

MiR-31-5p-ACOX1 Axis Enhances Tumorigenic Fitness in Oral Squamous Cell Carcinoma Via the Promigratory Prostaglandin E2

During neoplastic development, a multitude of changes in genome-encoded information are progressively selected to confer growth and survival advantages to tumor cells. microRNAs-mRNAs regulatory networks, given their role as a critical layer of robust gene expression control, are frequently altered in neoplasm. However, whether and how these gene perturbations impact metabolic homeostasis remains largely unresolved.

Methods: Through targeted miRNA expression screening, we uncovered an oral squamous cell carcinoma (OSCC)-associated miRNAome, among which miR-31-5p was identified based on extent of up-regulation, functional impact on OSCC cell migration and invasion, and direct regulation of the rate-limiting enzyme in peroxisomal β-oxidation, ACOX1.

Results: We further found that both miR-31-5p and ACOX1 underpin, in an antagonistic manner, the overall cellular lipidome profiles as well as the migratory and invasive abilities of OSCC cells. Interestingly, the extracellular levels of prostaglandin E2 (PGE2), a key substrate of ACOX1, were controlled by the miR-31-5p-ACOX1 axis, and were shown to positively influence the extent of cell motility in correlation with metastatic status. The promigratory effect of this metabolite was mediated by an elevation in EP1-ERK-MMP9 signaling. Of note, functional significance of this regulatory pathway was further corroborated by its clinicopathologically-correlated expression in OSCC patient specimens.

Conclusions: Collectively, our findings outlined a model whereby misregulated miR-31-5p-ACOX1 axis in tumor alters lipid metabolomes, consequently eliciting an intracellular signaling change to enhance cell motility. Our clinical analysis also unveiled PGE2 as a viable salivary biomarker for prognosticating oral cancer progression, further underscoring the importance of lipid metabolism in tumorigenesis.

Direct growth-inhibitory effects of prostaglandin E2 in pancreatic cancer cells in vitro through an EP4/PKA-mediated mechanism

BACKGROUND

There is strong evidence linking inflammation and the development of pancreatic ductal adenocarcinoma. Cyclooxygenase-2 (COX-2) and COX-2-derived PGE₂ are overexpressed in human and murine pancreatic ductal adenocarcinoma. Several studies have demonstrated an important role of COX-2-derived PGE₂ in tumor-stroma interactions; however, the direct growth effects of prostaglandin E₂ (PGE₂) on pancreatic ductal adenocarcinoma cells is less well defined. Our aim was to investigate the effects of PGE₂ on pancreatic ductal adenocarcinoma cell growth and to characterize the underlying mechanisms.

METHODS

Human pancreatic ductal adenocarcinoma cell lines, Panc-1 and MIA PaCa-2, were treated with PGE₂ in varying doses (0-10 μM). Effects on the phosphorylation of ERK1/2 were evaluated by Western blot. Colony formation was observed for cells treated with PGE₂ for 11 days. DNA synthesis was determined by (3H)-thymidine incorporation assay. Gene expression of E-type prostaglandin (EP)2/EP4 receptors and their correlation with survival in patients with pancreatic ductal adenocarcinoma were assessed using the RNA-Seq data set from The Cancer Genome Atlas Research Network.

RESULTS

PGE₂ decreased the size and number of colonies in Panc-1 but not MIA PaCa-2 cells. In the Panc-1 cells, PGE₂ activated PKA/CREB and decreased phosphorylation of ERK1/2, which was reversed by an EP4 receptor antagonist, while an EP2 receptor antagonist had no effect. In contrast, in MIA PaCa-2 cells, PGE₂ had no effect on ERK1/2 phosphorylation. Treatment of both Panc-1 and MIA PaCa-2 cells with forskolin/IBMX decreased ERK1/2 phosphorylation. Finally, PGE₂ decreased DNA synthesis only in Panc-1 cells, which was reversed by an EP4 receptor antagonist. In human pancreatic ductal adenocarcinoma, high EP2 and low EP4 gene expression was correlated to worse median overall survival (15.6 vs 20.8 months, log-rank P = .017).

CONCLUSION

Our study provides evidence that PGE₂ can inhibit directly pancreatic ductal adenocarcinoma cell growth through an EP4-mediated mechanism. Together with our gene expression and survival analysis, this observation suggests a protective role of EP4 receptors in human pancreatic ductal adenocarcinoma that expresses E-type prostaglandin receptors.

Inhibition of cancer migration and invasion by knocking down delta-5-desaturase in COX-2 overexpressed cancer cells

We recently reported that knockdown of delta-5-desaturase (a key enzyme that converts dihomo-γ-linolenic acid, DGLA, to the downstream ω-6 arachidonic acid) promotes formation of an anti-cancer byproduct 8-hydroxyoctanoic acid from cyclooxygenase (COX)-catalyzed DGLA peroxidation. 8-hydroxyoctanoic acid can exert its growth inhibitory effect on cancer cells (e.g. colon and pancreatic cancer) by serving as a histone deacetylase inhibitor. Since histone deacetylase inhibitors have been well-known to suppress cancer cell migration and invasion, we thus tested whether knockdown of delta-5-desaturase and DGLA treatment could also be used to inhibit cancer migration and invasion of colon cancer and pancreatic cancer cells. Wound healing assay, transwell assay and western blot were used to assess cell migration and invasion as well as the associated molecular mechanisms. Formation of threshold level of 8-hydroxyoctanoic acid was quantified from COX-catalyzed DGLA peroxidation in the cancer cells that overexpress COX-2 and their delta-5-desaturases were knocked down by shRNA transfection. Our results showed that knockdown of delta-5-desaturase along with DGLA supplement not only significantly inhibited cell migration, but also improved the efficacies of 5-flurouracil and gemcitabine, two frontline chemotherapy drugs currently used in the treatment of colon and pancreatic cancer, respectively. The molecular mechanism behind these observations is that 8-hydroxyoctanoic acid inhibits histone deacetylase, resulting in downregulation of cancer metastasis promotors, e.g., MMP-2 and MMP-9 as well as upregulation of cancer metastasis suppressor, e.g. E-cadherin. For the first time, we demonstrated that we could take the advantage of the common phenomenon of COX-2 overexpression in cancers to inhibit cancer cell migration and invasion. With the shifting paradigm of COX-2 cancer biology, our research outcome may provide us a novel cancer treatment strategy.

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High level of COX-2 could be used to inhibit cancer cell migration and invasion.

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8-hydroxyoctanoic acid suppresses cancer migration and invasion via inhibiting HDAC.

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D5D knockdown and DGLA improves efficacy of chemotherapy to inhibit cancer metastasis.

Galeterone and its analogs inhibit Mnk-eIF4E axis, synergize with gemcitabine, impede pancreatic cancer cell migration, invasion and proliferation and inhibit tumor growth in mice

Survival rate for pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC) is poor, with about 80% of patients presenting with the metastatic disease. Gemcitabine, the standard chemotherapeutic agent for locally advanced and metastatic PDAC has limited efficacy, attributed to innate/acquired resistance and activation of pro-survival pathways. The Mnk1/2-eIF4E and NF-κB signaling pathways are implicated in PDAC disease progression/metastasis and also associated with gemcitabine-induced resistance in PDAC. Galeterone (gal), a multi-target, agent in phase III clinical development for prostate cancer has also shown effects on the aforementioned pathways. We show for the first time, that gal/analogs (VNPT55, VNPP414 and VNPP433-3β) profoundly inhibited cell viability of gemcitabine-naive/resistance PDAC cell lines and strongly synergized with gemcitabine in gemcitabine-resistant PDAC cells. In addition, to inducing G1 cell cycle arrest, gal/analogs induced caspase 3-mediated cell-death of PDAC cells. Gal/analogs caused profound downregulation of Mnk1/2, peIF4E and NF-κB (p-p65), metastatic inducing factors (N-cadherin, MMP-1/-2/-9, Slug, Snail and CXCR4) and putative stem cell factors, (β-Catenin, Nanog, BMI-1 and Oct-4). Gal/analog also depleted EZH2 and upregulated E-Cadherin. These effects resulted in significant inhibition of PDAC cell migration, invasion and proliferation. Importantly, we also observed strong MiaPaca-2 tumor xenograft growth inhibition (61% to 92%). Collectively, these promising findings strongly support further development of gal/analogs as novel therapeutics for PDAC.

Knockdown delta-5-desaturase promotes the formation of a novel free radical byproduct from COX-catalyzed ω-6 peroxidation to induce apoptosis and sensitize pancreatic cancer cells to chemotherapy drugs

Recent research has demonstrated that colon cancer cell proliferation can be suppressed in the cells that overexpress COX-2 via generating 8-hydroxyoctanoic acid (a free radical byproduct) during dihomo-γ-linolenic acid (DGLA, an ω-6 fatty acid) peroxidation from knocking down cellular delta-5-desaturase (D5D, the key enzyme for converting DGLA to the downstream ω-6, arachidonic acid). Here, this novel research finding is extended to pancreatic cancer growth, as COX-2 is also commonly overexpressed in pancreatic cancer. The pancreatic cancer cell line, BxPC-3 (with high COX-2 expression and mutated p53), was used to assess not only the inhibitory effects of the enhanced formation of 8-hydroxyoctanoic acid from cellular COX-2-catalyzed DGLA peroxidation but also its potential synergistic and/or additive effect on current chemotherapy drugs. This work demonstrated that, by inducing DNA damage through inhibition of histone deacetylase, a threshold level of 8-hydroxyoctanoic acid achieved in DGLA-treated and D5D-knockdown BxPC-3 cells subsequently induce cancer cell apoptosis. Furthermore, it was shown that a combination of D5D knockdown along with DGLA treatment could also significantly sensitize BxPC-3 cells to various chemotherapy drugs, likely via a p53-independent pathway through downregulating of anti-apoptotic proteins (e.g., Bcl-2) and activating pro-apoptotic proteins (e.g., caspase 3, -9). This study reinforces the supposition that using commonly overexpressed COX-2 for molecular targeting, a strategy conceptually distinct from the prevailing COX-2 inhibition strategy used in cancer treatment, is an important as well as viable alternative to inhibit cancer cell growth. Based on the COX-2 metabolic cascade, the outcomes presented here could guide the development of a novel ω-6-based dietary care strategy in combination with chemotherapy for pancreatic cancer.

Lactoferrin from Camelus dromedarius Inhibits Nuclear Transcription Factor-kappa B Activation, Cyclooxygenase-2 Expression and Prostaglandin E2 Production in Stimulated Human Chondrocytes

Background:

Osteoarthritis (OA) is a progressive joint disorder, which remains the leading cause of chronic disability in aged people. Nuclear factor-kappa B (NF)-κB is a major cellular event in OA and its activation by interleukin-1β (IL-1β) plays a critical role in cartilage breakdown in these patients.

Objective:

In this study, we examined the effect of lactoferrin on NF-κB activation, cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE₂) production in stimulated human articular chondrocytes.

Materials and Methods:

Human chondrocytes were derived from OA articular cartilage and treated with camel lactoferrin and then stimulated with IL-1β. Gene expression was determined by TaqMan assays and protein expression was studied by Western immunoblotting. NF-κB activity and PGE₂ levels were determined by ELISA based assays. NF-κB activity was also determined by treatment of chondrocytes with NF-κB specific inhibitor Bay 11–7082.

Results:

Lactoferrin inhibited IL-1β-induced activation and nuclear translocation of NF-κB p65 in human OA chondrocytes. Lactoferrin also inhibited mRNA/protein expression of COX-2 and production of PGE₂. Moreover, Bay 11–7082 also inhibited IL-1β-induced expression of COX-2 and production of PGE₂. The inhibitory effect of lactoferrin on the IL-1β induced expression of COX-2 or production of PGE₂ was mediated at least in part via suppression of NF-κB activation.

Conclusions:

Our data determine camel lactoferrin as a novel inhibitor of IL-1β-induced activation of NF-κB signaling events and production of cartilage-degrading molecule PGE₂ via inhibition of COX-2 expressions. These results may have important implications for the development of novel therapeutic strategies for the prevention/treatment of OA and other degenerative/inflammatory diseases.

SUMMARY

Lactoferrin shows anti-arthritic activity in IL-1β stimulated primary human chondrocytes.

Lactoferrin inhibits IL-1β-induced NF-κB activation.

Lactoferrin inhibits production of cartilage degrading PGE2 via inhibition of COX-2 expression.

Abbreviations Used: OA: Osteoarthritis IL-1β: Interleukin-1 beta NF-κB: Nuclear factor-kappa B COX-2: cyclooxygenase-2 PGE₂: prostaglandin E₂

Targeting Apoptosis and Multiple Signaling Pathways with Icariside II in Cancer Cells

Cancer is the second leading cause of deaths worldwide. Despite concerted efforts to improve the current therapies, the prognosis of cancer remains dismal. Highly selective or specific blocking of only one of the signaling pathways has been associated with limited or sporadic responses. Using targeted agents to inhibit multiple signaling pathways has emerged as a new paradigm for anticancer treatment. Icariside II, a flavonol glycoside, is one of the major components of Traditional Chinese Medicine Herba epimedii and possesses multiple biological and pharmacological properties including anti-inflammatory, anti-osteoporosis, anti-oxidant, anti-aging, and anticancer activities. Recently, the anticancer activity of Icariside II has been extensively investigated. Here, in this review, our aim is to give our perspective on the current status of Icariside II, and discuss its natural sources, anticancer activity, molecular targets and the mechanisms of action with specific emphasis on apoptosis pathways which may help the further design and conduct of preclinical and clinical trials. Icariside II has been found to induce apoptosis in various human cancer cell lines of different origin by targeting multiple signaling pathways including STAT3, PI3K/AKT, MAPK/ERK, COX-2/PGE2 and β-Catenin which are frequently deregulated in cancers, suggesting that this collective activity rather than just a single effect may play an important role in developing Icariside II into a potential lead compound for anticancer therapy. This review suggests that Icariside II provides a novel opportunity for treatment of cancers, but additional investigations and clinical trials are still required to fully understand the mechanism of therapeutic effects to further validate it in anti-tumor therapy.

Co-targeting of Cyclooxygenase-2 and FoxM1 is a viable strategy in inducing anticancer effects in colorectal cancer cells

Background

Cross-talk between deregulated signaling pathways in cancer cells causes uncontrolled growth and proliferation. These cancers cells become more aggressive and quickly develop resistance to therapy. Therefore targeting of these deregulated pathways simultaneously can result in efficient cell death of cancer cells. In this study we investigated co-expression of Cox-2 and FoxM1 in a cohort of colorectal carcinoma (CRC) samples and also examined whether inhibition of Cox-2 and FoxM1 simultaneously can lead to inhibition of cell viability and induction of apoptosis in colorectal cancer cell lines and in vivo xenografts.

Methods

Protein expression of Cox-2 and FoxM1 was determined in a large cohort of 770 clinical CRC samples in a tissue micro-array format by immunohistochemistry. Cell death was measured using live dead assay. Apoptosis was measured by annexin V/PI dual staining. Immunoblotting was performed to examine the expression of proteins. Calcusyn software was utilized to estimate the synergistic doses using chou and Talalay method.

Results

Co-expression of Cox-2 and FoxM1 was detected in 33.3 % (232/697) of CRC’s and associated with an aggressive phenotype characterized by younger age (p = 0.0191), high proliferative index marker; Ki-67 (p = 0.004) and MMP-9 (p = 0.0116) as well as activation of AKT (p = 0.0214). In vitro, inhibition of FoxM1 and Cox-2 with pharmacological inhibitors; Thiostrepton and NS398 resulted in efficient down-regulation of FoxM1 and Cox-2 expression along with in-activation of AKT and inhibition of colony formation, invasion and migratory capability of CRC cells. In addition, there was also inhibition of cell viability and induction of apoptosis via the mitochondrial apoptotic pathway in CRC cell lines. Finally, treatment of CRC xenograft tumors in nude mice with combination of Cox-2 and FoxM1 inhibitors inhibited tumor growth significantly via down-regulation of Cox-2 and FoxM1 expression.

Conclusions

These findings demonstrate that co-expression of Cox-2 and FoxM1 might play a critical role in the pathogenesis of CRC. Therefore, targeting of these pathways simultaneously with sub toxic doses of pharmacological inhibitors can be a potential therapeutic approach for the treatment of this subset of CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0406-1) contains supplementary material, which is available to authorized users.

Expression of matrix metalloproteinase-9, cyclooxygenase-2 and vascular endothelial growth factor are increased in gastrointestinal stromal tumors

This study is to investigate the expression of matrix metalloproteinase-9 (MMP-9), cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in gastrointestinal stromal tumor (GIST). Immunohistochemistry was performed to detect the expression of MMP-9, COX-2 and VEGF. The expression of MMP-9, COX-2 and VEGF was compared among different clinicopathological features of GIST. Spearman rank correlation analysis was conducted to analyze the correlation among MMP-9, COX-2 and VEGF. The positive expression rates of MMP-9, COX-2 and VEGF were 76.9%, 84.6% and 82.7%. The expression levels of MMP-9, COX-2 and VEGF were significantly different among the clinicopathological features of growth pattern, tumor diameter, metastasis, mitotic count and central necrosis (P < 0.05). Their expression levels were higher in GIST tissues with higher levels of malignancy, tumor size, metastasis, mitotic count and central necrosis. However, their expression levels were not significantly different among age, gender, primary tumor site or CD117 expression. Additionally, there were positive correlations between COX-2 and VEGF (r = 0.612, P < 0.01), between COX-2 and MMP-9 (r = 0.592, P < 0.05), and between MMP-9 and VEGF (r = 0.690, P < 0.01). MMP-9, COX-2 and VEGF expression levels are increased in GIST tissues and related with clinicopathological features of GIST.

Selective COX-2 inhibitors for treatment of pancreatic cancer: Research progress

Cyclooxygenase-2 (COX-2) is highly expressed in pancreatic cancer and closely related to the occurrence, development, differentiation, metastasis and prognosis of this malignancy. Selective COX-2 inhibitors have anti-tumor effects both in vivo and in vitro. In this paper we review the recent progress in research on the molecular characteristics of COX-2, the relationship between COX-2 and pancreatic cancer, and the use of selective COX-2 inhibitors for the treatment of pancreatic cancer.

Epstein-Barr virus Zta upregulates matrix metalloproteinases 3 and 9 that synergistically promote cell invasion in vitro

Zta is a lytic transactivator of Epstein-Barr virus (EBV) and has been shown to promote migration and invasion of epithelial cells. Although previous studies indicate that Zta induces expression of matrix metalloproteinase (MMP) 9 and MMP1, direct evidence linking the MMPs to Zta-induced cell migration and invasion is still lacking. Here we performed a series of in vitro studies to re-examine the expression profile and biologic functions of Zta-induced MMPs in epithelial cells derived from nasopharyngeal carcinoma. We found that, in addition to MMP9, MMP3 was a new target gene upregulated by Zta. Ectopic Zta expression in EBV-negative cells increased both mRNA and protein production of MMP3. Endogenous Zta also contributed to induction of MMP3 expression, migration and invasion of EBV-infected cells. Zta activated the MMP3 promoter through three AP-1 elements, and its DNA-binding domain was required for the promoter binding and MMP3 induction. We further tested the effects of MMP3 and MMP9 on cell motility and invasiveness in vitro. Zta-promoted cell migration required MMP3 but not MMP9. On the other hand, both MMP3 and MMP9 were essential for Zta-induced cell invasion, and co-expression of the two MMPs synergistically increased cell invasiveness. Therefore, this study provides integrated evidence demonstrating that, at least in the in vitro cell models, Zta drives cell migration and invasion through MMPs.

Potential role of garcinol as an anticancer agent

Garcinol, a polyisoprenylated benzophenone, is extracted from the rind of the fruit of Garcinia indica, a plant found extensively in tropical regions. Although the fruit has been consumed traditionally over centuries, its biological activities, specifically its anticancer potential is a result of recent scientific investigations. The anticarcinogenic properties of garcinol appear to be moderated via its antioxidative, anti-inflammatory, antiangiogenic, and proapoptotic activities. In addition, garcinol displays effective epigenetic influence by inhibiting histone acetyltransferases (HAT 300) and by possible posttranscriptional modulation by mi RNA profiles involved in carcinogenesis. In vitro as well as some in vivo studies have shown the potential of this compound against several cancers types including breast, colon, pancreatic, and leukemia. Although this is a promising molecule in terms of its anticancer properties, investigations in relevant animal models, and subsequent human trials are warranted in order to fully appreciate and confirm its chemopreventative and/or therapeutic potential.

CDK-4 inhibitor P276 sensitizes pancreatic cancer cells to gemcitabine-induced apoptosis

Despite advances in molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. It is a rapidly invasive, metastatic tumor that is resistant to standard therapies. The phosphatidylinositol-3-kinase/Akt and mTOR signaling pathways are frequently dysregulated in pancreatic cancer. Gemcitabine is the mainstay treatment for metastatic pancreatic cancer. P276 is a novel CDK inhibitor that induces G(2)/M arrest and inhibits tumor growth in vivo models. Here, we determined that P276 sensitizes pancreatic cancer cells to gemcitabine-induced apoptosis, a mechanism-mediated through inhibition of Akt-mTOR signaling. In vitro, the combination of P276 and gemcitabine resulted in a dose- and time-dependent inhibition of proliferation and colony formation of pancreatic cancer cells but not with normal pancreatic ductal cells. This combination also induced apoptosis, as seen by activated caspase-3 and increased Bax/Bcl2 ratio. Gene profiling studies showed that this combination downregulated Akt-mTOR signaling pathway, which was confirmed by Western blot analyses. There was also a downregulation of VEGF and interleukin-8 expression suggesting effects on angiogenesis pathway. In vivo, intraperitoneal administration of the P276-Gem combination significantly suppressed the growth of pancreatic cancer tumor xenografts. There was a reduction in CD31-positive blood vessels and reduced VEGF expression, again suggesting an effect on angiogenesis. Taken together, these data suggest that P276-Gem combination is a novel potent therapeutic agent that can target the Akt-mTOR signaling pathway to inhibit both tumor growth and angiogenesis.