Combined lipoxygenase/cyclo-oxygenase inhibition in the elderly: the example of licofelone

Triterpene Acids from Frankincense and Semi-Synthetic Derivatives That Inhibit 5-Lipoxygenase and Cathepsin G

Age-related diseases, such as osteoarthritis, Alzheimer’s disease, diabetes, and cardiovascular disease, are often associated with chronic unresolved inflammation. Neutrophils play central roles in this process by releasing tissue-degenerative proteases, such as cathepsin G, as well as pro-inflammatory leukotrienes produced by the 5-lipoxygenase (5-LO) pathway. Boswellic acids (BAs) are pentacyclic triterpene acids contained in the gum resin of the anti-inflammatory remedy frankincense that target cathepsin G and 5-LO in neutrophils, and might thus represent suitable leads for intervention with age-associated diseases that have a chronic inflammatory component. Here, we investigated whether, in addition to BAs, other triterpene acids from frankincense interfere with 5-LO and cathepsin G. We provide a comprehensive analysis of 17 natural tetra- or pentacyclic triterpene acids for suppression of 5-LO product synthesis in human neutrophils. These triterpene acids were also investigated for their direct interference with 5-LO and cathepsin G in cell-free assays. Furthermore, our studies were expanded to 10 semi-synthetic BA derivatives. Our data reveal that besides BAs, several tetra- and pentacyclic triterpene acids are effective or even superior inhibitors of 5-LO product formation in human neutrophils, and in parallel, inhibit cathepsin G. Their beneficial target profile may qualify triterpene acids as anti-inflammatory natural products and pharmacological leads for intervention with diseases related to aging.

Targeting pancreatitis blocks tumor-initiating stem cells and pancreatic cancer progression

Recent development of genetically engineered mouse models (GEMs) for pancreatic cancer (PC) that recapitulates human disease progression has helped to identify new strategies to delay/inhibit PC development. We first found that expression of the pancreatic tumor-initiating/cancer stem cells (CSC) marker DclK1 occurs in early stage PC and in both early and late pancreatic intraepithelial neoplasia (PanIN) and that it increases as disease progresses in GEM and also in human PC. Genome-wide next generation sequencing of pancreatic ductal adenocarcinoma (PDAC) from GEM mice revealed significantly increased DclK1 along with inflammatory genes. Genetic ablation of cyclo-oxygenase-2 (COX-2) decreased DclK1 in GEM. Induction of inflammation/pancreatitis with cerulein in GEM mice increased DclK1, and the novel dual COX/5-lipoxygenase (5-LOX) inhibitor licofelone reduced it. Dietary licofelone significantly inhibited the incidence of PDAC and carcinoma in situ with significant inhibition of pancreatic CSCs. Licofelone suppressed pancreatic tumor COX-2 and 5-LOX activities and modulated miRNAs characteristic of CSC and inflammation in correlation with PDAC inhibition. These results offer a preclinical proof of concept to target the inflammation initiation to inhibit cancer stem cells early for improving the treatment of pancreatic cancers, with immediate clinical implications for repositioning dual COX/5-LOX inhibitors in human trials for high risk patients.

The role of inflammation in colon cancer

Colorectal cancer (CRC) is the one of the leading causes of cancer-related deaths in the world. CRC is responsible for more than 600,000 deaths annually and incidence rates are increasing in most of the developing countries. Epidemiological and laboratory investigations suggest that environmental factors such as western style dietary habits, tobacco-smoking, and lack of physical activities are considered as risks for CRC. Molecular pathobiology of CRC implicates pro-inflammatory conditions to promote the tumor malignant progression, invasion, and metastasis. It is well known that patients with inflammatory bowel disease are at higher risk of CRC. Many evidences exist reiterating the link between Inflammation and CRC. Inflammation involves interaction between various immune cells, inflammatory cells, chemokines, cytokines, and pro-inflammatory mediators, such as cyclooxygenase (COX) and lipoxygenase (LOX) pathways, which may lead to signaling towards, tumor cell proliferation, growth, and invasion. Thus, this review will focus on mechanisms by which pro-inflammatory mediators and reactive oxygen/nitrogen species play a role in promoting CRC. Based on these mechanisms, various preventive strategies, involving anti-inflammatory agents, such as COX inhibitors, COX-LOX inhibitors, iNOS inhibitors, natural supplements/agents, and synthetic agents, that blocks the inflammatory pathways and suppress CRC are discussed in this review.

Cytotoxic and apoptotic functions of licofelone on rat glioma cells

Gliomas are the largest group of central nervous system tumors and despite of clinical treatments death rate is very high. Inhibition of both cyclooxygenase and lipoxygenase pathways that take role in arachidonic acid metabolism prevents cancer development and induces apoptosis. One of the most promising compounds that blocks both of these pathways is licofelone. Using colchicine and 5-fluorouracil as positive controls, we questioned whether licofelone affects the survival of rat glioma cell line (C6) and induces apoptosis in vitro. After growing the cells in culture, we determined viability with MT, apoptosis with flow cytometry and activity of caspase enzymes with real time PCR. All used doses of colchicine and 5-fluorouracil were cytotoxic and reduced the number of surviving C6 cells as much as 44% and 60%, respectively. Comparing to the control, treatments with 10, 50 and 100 μM licofelone for 24 or 48 h did not influence C6 survival, however, 150, 200 and 250 μM licofelone reduced the number of living cells by 58, 88 and 93%, respectively, and induced apoptosis of C6 cells in a dose and time dependent manner. Licofelone did not change the level of caspase-9, but increased the level of caspase-3. Comparing with 5-fluorouracil and colchicine, the present study reveals for the first time the possibility that licofelone possesses a strong dose and time dependent antiproliferative and proapoptotic properties on glioma cells.

Novel di-tertiary-butyl phenylhydrazones as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, COX/LOX inhibition, molecular modeling, and insights into their cytotoxicities

Although dual inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) enzymes is highly effective than targeting COX or LOX alone, there are only a few reports of examining such compounds in case of colorectal cancers (CRC). In the present work we report that the novel di-tert-butyl phenol-based dual inhibitors DTPSAL, DTPBHZ, DTPINH, and DTPNHZ exhibit significant cytotoxicity against human CRC cell lines. Molecular docking studies revealed a good fit of these compounds in the COX-2 and 5-LOX protein cavities. The inhibitors show significant inhibition of COX-2 and 5-LOX activities and are effective against a panel of human colon cancer cell lines including HCA-7, HT-29, SW480 and intestinal Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressing colon cancer cells, through inhibition of the Hyaluronan/CD44v6 cell survival pathway. Western blot analysis and qRT-PCR analyses indicated that the di-tert-butyl phenol-based dual inhibitors reduce the expression of COX-2, 5-LOX, and CD44v6 in human colon cancer HCA-7 cells, while the combination of CD44v6shRNA and DTPSAL has an additional inhibitory effect on CD44v6 mRNA expression. The synergistic inhibitory effect of Celecoxib and Licofelone on CD44v6 mRNA expression suggests that the present dual inhibitors down-regulate cyclooxygenase and lipoxygenase enzymes through CD44v6. The compounds also exhibited enhanced antiproliferative potency compared to standard dual COX/LOX inhibitor, viz. Licofelone. Importantly, the HA/CD44v6 antagonist CD44v6shRNA in combination with synthetic compounds had a sensitizing effect on the cancer cells which enhanced their antiproliferative potency, a finding which is crucial for the anti-proliferative potency of the novel synthetic di-tert-butyl phenol based dual COX-LOX inhibitors in colon cancer cells.

Licofelone inhibits interleukin-18-induced pro-inflammatory cytokine release and cellular proliferation in human mesangial cells

Licofelone, a novel dual anti-inflammatory drug that inhibits 5-lipoxygenase (5-LOX) and cyclooxygenase (COX), has recently been defined to have therapeutic effects in osteoarthritis. Both 5-LOX and COX play functional roles in the pathogenesis of glomerulonephritis in children as well. Interleukin-18 is a pro-inflammatory cytokine. It remains unclear whether licofelone can ameliorate inflammatory response of human mesangial cells (HMC) exposed to interleukin-18. In this study, HMC were cultured and exposed to interleukin-18 with or without pre-treatment of licofelone. COX-2 and 5-LOX enzyme activities in mesangial cells were determined with chromometry or high-performance liquid chromatography. Prostaglandin E2, cysteinyl leukotriene, monocyte chemotactic protein-1 and interferon-γ concentrations in culture medium were measured using an enzyme-linked immunosorbent assay. Western blotting was employed to detect phosphorylated mitogen-activated protein kinases ERK1/2, p38 and JNK1/2 in HMC. It was found that licofelone attenuated interleukin-18-induced COX-2 enzyme activity in HMC and prostaglandin E2 release in a dose-dependent manner. Similarly, licofelone inhibited interleukin-18-induced 5-LOX enzyme activity and leukotriene release. Licofelone reduced interleukin-18-induced phosphorylation of p38 mitogen-activated protein kinase and suppressed monocyte chemotactic protein-1 and interferon-γ synthesis. Moreover, licofelone inhibited IL-18-induced proliferation of mesangial cells. We conclude that licofelone inhibits interleukin-18-induced pro-inflammatory cytokine release and cellular proliferation in HMC, which may represent a really interesting therapeutic approach for glomerulonephritis in children.

Chemoprevention of colon and small intestinal tumorigenesis in APC(Min/+) mice by licofelone, a novel dual 5-LOX/COX inhibitor: potential implications for human colon cancer prevention

Preclinical and clinical studies suggest that 5-lipoxygenase (5-LOX), such as COX-2, is a potential target for colon cancer inhibition and, in part, contributes to cardiovascular side effects associated with COX-2 inhibitors. Experiments were designed to assess the chemopreventive effects of a novel dual 5-LOX/COX inhibitor, licofelone {[6-(4-chlorophenyl)-2,2-dimethyl-7-phenyl-2,3-dihydro-1H-pyrrolizin-5-yl] acetic acid}, in APC(Min/+) mouse intestinal tumorigenesis. Six-week-old male and female APC(Min/+) mice (n = 10 per group) were fed with control American Institute of Nutrition-76A diet or diets containing 150 or 300 ppm licofelone for 14 weeks (∼100 days), and intestinal tumors were evaluated for tumor multiplicity and size. Licofelone significantly inhibited total intestinal tumor multiplicity and size in a dose-dependent manner (P < 0.0001; mean tumors for 0, 150, and 300 ppm: 48.8, 17, and 8, respectively, in male mice; and 34.3, 8.8, and 5.5, respectively, in female mice). Licofelone at high dose showed more than 83% (P < 0.0001) tumor inhibition in both genders of mice. One hundred and fifty and 300 ppm licofelone resulted in 86% to 97% inhibition of polyps having size greater than 2 mm. One hundred and fifty and 300 ppm licofelone caused more than 72% and 100% inhibition of colonic tumors, respectively. Importantly, in mice fed with licofelone, tumors showed significantly reduced proliferating cell nuclear antigen expression (70%, P < 0.0001), increased terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells (75%, P < 0.0001), and there was dose-dependent suppression of serum triglycerides (71%-83%, P < 0.0001), decreased inflammatory cytokines; and decreased COX and 5-LOX activities (57%-64%, P < 0.0001). Also, compared with 300 ppm celecoxib, 300 ppm licofelone provided better efficacy in suppressing tumor growth. These observations show that a novel dual 5-LOX/COX inhibitor dramatically suppresses small intestinal and colonic tumor formation in APC(Min/+) mice.

Licofelone attenuates quinolinic acid induced Huntington like symptoms: possible behavioral, biochemical and cellular alterations

Cyclo-oxygenase and lipoxygenase enzymes are involved in arachidonic acid metabolism. Emerging evidence indicates that cyclo-oxygenase and lipoxygenase inhibitors prevent neurodegenerative processes and related complications. Therefore, the present study has been designed to explore the neuroprotective potential of licofelone (dual COX-2/5-LOX inhibitor) against quinolinic acid induced Huntington like symptom in rats. Intrastriatal administration of quinolinic acid significantly caused reduction in body weight and motor function (locomotor activity, rotarod performance and beam walk test), oxidative defense (as evidenced by increased lipid peroxidation, nitrite concentration and decreased endogenous antioxidant enzymes), alteration in mitochondrial enzyme complex (I, II and IV) activities, raised TNF-α level and striatal lesion volume as compared to sham treated animals. Licofelone (2.5, 5 and 10 mg/kg) treatment significantly improved body weight, locomotor activity, rotarod performance, balance beam walk performance, oxidative defense, mitochondrial enzyme complex activities and attenuated TNF-α level and striatal lesion as compared to control (quinolinic acid). The present study highlights that licofelone attenuates behavioral, biochemical and cellular alterations against quinolinic acid induced neurotoxicity and this could be an important therapeutic avenue to ameliorate the Huntington like symptoms.

Efficacy and safety of flavocoxid, a novel therapeutic, compared with naproxen: a randomized multicenter controlled trial in subjects with osteoarthritis of the knee

INTRODUCTION

Flavocoxid is a novel flavonoid-based "dual inhibitor" of the 5-lipoxygenase (5-LOX) enzyme and the cyclooxygenase (COX) enzymes. This study was designed to compare the effectiveness and safety of flavocoxid to naproxen in subjects with moderate to severe osteoarthritis (OA) of the knee.

METHODS

In this randomized, multicenter, double-blind study, 220 subjects were assigned to receive either flavocoxid (500 mg twice daily) or naproxen (500 mg twice daily) for 12 weeks. The trial was structured to show noninferiority of flavocoxid to naproxen. Primary outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and subscales and a timed walk.

RESULTS

More than 90% of the subjects in both groups noted significant reduction in the signs and symptoms of knee OA. There were no statistically significant differences in efficacy between the flavocoxid and naproxen groups when the entire intent-to-treat population was analyzed. The flavocoxid group had significantly fewer upper gastrointestinal (UGI) and renal (edema) adverse events (AEs) as well as a strong trend toward fewer respiratory AEs.

CONCLUSION

Flavocoxid, a first-in-class flavonoid-based therapeutic that inhibits COX-1 and COX-2 as well as 5-LOX, was as effective as naproxen in managing the signs and symptoms of OA of the knee. Flavocoxid demonstrated better UGI, renal (edema), and respiratory safety profiles than naproxen.

Combination Therapy of PPARgamma Ligands and Inhibitors of Arachidonic Acid in Lung Cancer

Lung cancer is the leading cause of cancer death in the United States and five-year survival remains low. Numerous studies have shown that chronic inflammation may lead to progression of carcinogenesis. As a result of inflammatory stimulation, arachidonic acid (AA) metabolism produces proliferation mediators through complex and dynamic interactions of the products of the LOX/COX enzymes. One important mediator in the activation of the AA pathways is the nuclear protein PPARgamma. Targeting LOX/COX enzymes and inducing activation of PPARgamma have resulted in significant reduction of cell growth in lung cancer cell lines. However, specific COX-inhibitors have been correlated with an increased cardiovascular risk. Clinical applications are still being explored with a novel generation of dual LOX/COX inhibitors. PPARgamma activation through synthetic ligands (TZDs) has revealed a great mechanistic complexity since effects are produced through PPARgamma-dependent and -independent mechanisms. Furthermore, PPARgamma could also be involved in regulation of COX-2. Overexpression of PPARgamma has reported to play a role in control of invasion and differentiation. Exploring the function of PPARgamma, in this new context, may provide a better mechanistic model of its role in cancer and give an opportunity to design a more efficient therapeutic approach in combination with LOX/COX inhibitors.

Inhibition of lipoxygenases and cyclooxygenases by linoleyl hydroxamic acid: comparative in vitro studies

In this first comparative in vitro study, linoleyl hydroxamic acid (LHA), a simple and stable derivative of linoleic acid, was tested as an inhibitor of several enzymes involved in arachidonic acid metabolism in mammals. The tested enzymes were human recombinant 5-lipoxygenase (h5-LO), porcine leukocyte 12-LO, rabbit reticulocyte 15-LO, ovine cyclooxygenases 1/2 (COX1/COX2), and human microsomal prostaglandin E synthase-1 (mPGES-1). Potato tuber and soybean lipoxygenases (ptLOX and sLOX, respectively) were studied for comparative purposes. LHA inhibited most of the tested enzymes with the exception of mPGES-1. The LHA inhibitory activity increased as follows: mPGES-1 (no inhibition)<<COX1 = COX2<h5-LO = sLOX = ptLOX<12-LO<<15-LO. The IC(50) values for COX1/COX2, h5-LO, 12-LO, and 15-LO were 60, 7, 0.6, and 0.02 muM, respectively. sLOX was the only tested enzyme that was capable of aerobic oxygenation of LHA, producing 13-hydroperoxy-LHA. The enzyme rapidly inactivated during the reaction. Therefore, LHA could be used as an effective LO/LOX inhibitor without affecting COX1/COX2 and mPGES-1. Possible implications of this observation include treating diseases and pathological states that are caused by (or lead to) hyperproduction of LO-derived metabolites, e.g., inflammation, cardiovascular disorders, cancer, asthma, allergies, psoriasis, and stroke.

Licofelone, a dual COX/5-LOX inhibitor, induces apoptosis in HCA-7 colon cancer cells through the mitochondrial pathway independently from its ability to affect the arachidonic acid cascade

Nowadays, no data are available concerning the potential use of dual cyclooxygenase (COX)/5-lipoxygenase (LOX) inhibitors as anticancer agents in colon cancer treatment. Here, we report, for the first time, that the dual COX/5-LOX inhibitor licofelone triggers apoptosis in a dose- and time-dependent manner in HCA-7 colon cancer cells. Induction of apoptosis was related to the recruitment of the intrinsic mitochondrial apoptotic pathway, as shown by loss in mitochondrial membrane potential, cytochrome c release, caspase-9 and 3 activation and poly-(ADP-ribose)polymerase-1 cleavage. Moreover, licofelone induced the cleavage of the full-length p21(Bax) into p18(Bax), a more potent inducer of the apoptotic process than the uncleaved form. Pre-treatment of HCA-7 cells with the pan-caspase inhibitor z-VAD-fmk significantly blocked licofelone-induced apoptosis, confirming that this process occurred primarily in a caspase-dependent pathway. We also present evidences that licofelone was able to affect the arachidonic acid (AA) cascade, as it blocked the activity of 5-LOX and COX enzymes, and it induced, through the phosphorylation of cytoplasmic phospholipase A(2) (cPLA(2)), the release of unesterified AA from HCA-7 membrane phospholipids. However, apoptosis induction was not related to the ability of licofelone to affect the AA cascade, since neither exogenous prostaglandin E(2) and leukotriene B(4) addition, nor pharmacological inhibition of cPLA(2), was able to rescue HCA-7 cells from apoptosis. Even if further studies are needed to clarify the mechanism of licofelone-induced apoptosis, this study suggests that this drug, as well as similar dual COX/5-LOX inhibitors, may represent a novel and promising approach in colon cancer treatment.

Structure-activity relationship of 2-oxoamide inhibition of group IVA cytosolic phospholipase A2 and group V secreted phospholipase A2

The Group IVA cytosolic phospholipase A2 (GIVA cPLA2) is a key provider of substrates for the production of eicosanoids and platelet-activating factor. We explored the structure-activity relationship of 2-oxoamide-based compounds and GIVA cPLA2 inhibition. The most potent inhibitors are derived from delta- and gamma-amino acid-based 2-oxoamides. The optimal side-chain moiety is a short nonpolar aliphatic chain. All of the newly developed 2-oxoamides as well as those previously described have now been tested with the human Group V secreted PLA2 (GV sPLA2) and the human Group VIA calcium-independent PLA2 (GVIA iPLA2). Only one 2-oxoamide compound had appreciable inhibition of GV sPLA2, and none of the potent GIVA cPLA2 inhibitors inhibited either GV sPLA2 or GVIA iPLA2. Two of these specific GIVA cPLA2 inhibitors were also found to have potent therapeutic effects in animal models of pain and inflammation at dosages well below the control nonsteroidal anti-inflammatory drugs.

Licofelone, a balanced inhibitor of cyclooxygenase and 5-lipoxygenase, reduces inflammation in a rabbit model of atherosclerosis

Licofelone, a dual anti-inflammatory drug that inhibits 5-lipoxygenase (LOX) and cyclooxygenase (COX) enzymes, may have a better cardiovascular profile that cycloxygenase-2 inhibitors due to cycloxygenase-1 blockade-mediated antithrombotic effect and a better gastrointestinal tolerability. We examined the anti-inflammatory effect of licofelone on atherosclerotic lesions as well as in isolated neutrophils from whole blood of rabbits compared with a selective inhibitor of COX-2, rofecoxib. We also assessed the antithrombotic effect of licofelone in rabbit platelet-rich plasma. For this purpose, 30 rabbits underwent injury of femoral arteries, and they were randomized to receive 10 mg/kg/day licofelone or 5 mg/kg/day rofecoxib or no treatment during 4 weeks with atherogenic diet in all cases. Ten healthy rabbits were used as controls. Neutrophils and platelets were isolated from peripheral blood of rabbits for ex vivo studies. Licofelone reduced intima/media ratio in injured arteries, the macrophages infiltration in the neointimal area, monocyte chemoattractant protein-1 (MCP-1) gene expression, and the activation of nuclear factor-kappaB in rabbit atheroma. Moreover, licofelone inhibited COX-2 and 5-LOX protein expression in vascular lesions. Rofecoxib only diminished COX-2 protein expression and MCP-1 gene expression in vascular atheroma. Prostaglandin E(2) in rabbit plasma was attenuated by both drugs. Licofelone almost abolished 5-LOX activity by inhibiting leukotriene B4 generation in rabbit neutrophils and prevented platelet thromboxane B2 production from whole blood. Licofelone reduces neointimal formation and inflammation in an atherosclerotic rabbit model more markedly than rofecoxib. This effect, together with the antiplatelet activity of licofelone, suggests that this drug may have a favorable cardiovascular profile.

Monitoring eicosanoid biosynthesis via lipoxygenase and cyclooxygenase pathways in human whole blood by single HPLC run

Eicosanoids play an important role as lipid mediators for physiological and pathological processes. Inhibitors of their biosynthesis have been developed as drugs for various diseases with major health political relevance. The search for more efficient inhibitors of eicosanoid formation requires simultaneous monitoring of various metabolic pathways. We developed an HPLC-based assay system, which quantifies lipoxygenase metabolites leukotriene B4 (LTB4), 5-hydroxyeicosatetraenoic acid (5-HETE), 12-hydroxyeicosatetraenoic acid (12-HETE), 15-hydroxyeicosatetraenoic acid (15-HETE) and cyclooxygenase metabolite 12-hydroxy-5,8,10-heptadecatrienoic acid (12-HHT) in whole human blood. Eicosanoid formation in blood is initiated with calcium ionophore A23187, arachidonic acid and calcium and magnesium ions. After solid phase extraction the different eicosanoids were separated by isocratic RP-HPLC using prostaglandin B1 as authentic standard. To verify the assay we determined the IC50 of known inhibitors of eicosanoid biosynthesis (zileuton, indomethacin, nordihydroguaiaretic acid). The test system is simple. It does not require extensive methodological experience and can be carried out in any biochemical laboratory. The analytical procedure can be robotized and thus, the assay appears suitable for medium-throughput testing of drugs.