Cyclooxygenase inhibitors not inhibit resting lung cancer A549 cell proliferation

Cyclooxygenase-1 (COX-1) and COX-1 Inhibitors in Cancer: A Review of Oncology and Medicinal Chemistry Literature

Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE₂) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

Two new C-glucosyl flavonoids from Ziziphus jujube and their anti-inflammatory activity

Two new C-glucosyl flavonoids 6''-O-feruloylspinosin and 6''-O-feruloyl-6'''-p-hydroxybenzoylspinosin, together with five known compounds, were isolated from the seeds of Ziziphus jujube (Rhamnaceae family). Their structures were elucidated on the basis of chemical and spectroscopic evidences. Compounds 1-7 showed moderate inhibitory effects against COX-1 and COX-2 enzymes.

Amaryllidaceae alkaloids from the bulbs of Lycoris radiata with cytotoxic and anti-inflammatory activities

Four new Amaryllidaceae alkaloids, (+)-1-hydroxy-ungeremine (1), (+)-6β-acetyl-8-hydroxy-9-methoxy-crinamine (2), (+)-2-hydroxy-8-demethyl-homolycorine-α-N-oxide (3), (+)-N-methoxylcarbonyl-2-demethyl-isocorydione (4), together with two known compounds, (+)-6β-acetyl-crinamine (5) and 8-demethyl-homolycorine-α-N-oxide (6) were isolated from the ethanol extract of the bulbs of Lycoris radiata. Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D ((1)H-(1)H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. All the isolated alkaloids were in vitro evaluated for their cytotoxic activities against eight tumor cell lines (BEN-MEN-1, CCF-STTG1, CHG-5, SHG-44, U251, BGC-823, HepG2 and SK-OV-3) and anti-inflammatory activities against Cox-1 and Cox-2. As a result, alkaloids 1 and 4 exhibited significant cytotoxic activities against all tested tumor cell lines except against BEN-MEN-1. Additionally, alkaloids 1 and 4 possessed selective inhibition of Cox-2 comparable with the standard drug NS-398 (>90%).

Tolerance of neurite outgrowth to Rho kinase inhibitors decreased by cyclooxygenase-2 inhibitor

In this study, PC12 Adh cells and Neuro-2a cells were treated with Rho-associated kinase inhibitors (Y27632 and Fasudil), a cyclooxygenase-1 selective inhibitor (SC560), and a cyclooxygenase-2 inhibitor (NS398). We found that these cells became tolerant to Rho-associated kinase inhibitors, as neurite outgrowth induced by these inhibitors diminished following more than 3 days of exposure in either cell line. The proteins cyclooxygenase-2 and cytosolic prostaglandin E synthetase were upregulated at day 3. NS398 decreased the tolerance to neurite outgrowth induction in both cell lines, whereas SC560 had almost no effect. These findings indicate that cells become tolerant to neurite outgrowth induced by Rho-associated kinase inhibitors, this is at least partly associated with upregulation of proteins involved in the cyclooxygenase-2 pathway, and cyclooxygenases-2 inhibition prevents this tolerance.

Monoterpenoid indole alkaloids from Alstonia rupestris with cytotoxic, anti-inflammatory and antifungal activities

Phytochemical investigation of the 70% EtOH extract of the leaves of Alstonia scholaris afforded seven new monoterpenoid indole alkaloids: scholarisins I-VII (1-7), and three known compounds: (3R,5S,7R,15R,16R,19E)-scholarisine F (8), 3-epi-dihydro- corymine (9), and (E)-16-formyl-5α-methoxystrictamine (10). Structural elucidation of all the compounds was accomplished by spectral methods such as 1D- and 2D-NMR, IR, UV, and HRESIMS. The isolated compounds were tested in vitro for cytotoxicity against seven tumor cell lines, anti-inflammatory activities against Cox-1 and Cox-2, and antifungal potential against five species of fungi. Compounds 1, 6, and 10 exhibited significant cytotoxicities against all the tested tumor cell lines with IC₅₀ values of less than 30 μM and selective inhibition of Cox-2 comparable with the standard drug NS-398 (>90%). Additionally, 1, 2, 3 and 8 showed antifungal activity against two fungal strains (G. pulicaris and C. nicotianae).

Monoterpenoid indole alkaloids from Alstonia yunnanensis and their cytotoxic and anti-inflammatory activities

The 80% ethanol extract of Alstonia yunnanensis afforded five new monoterpenoid indole alkaloids: 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (1), 14-chloro-15-hydroxy-vincadifformine (2), perakine N₄-oxide (3), raucaffrinoline N₄-oxide (4), and vinorine N₁,N₄-dioxide (5), together with three known compounds: 11-methoxy-6,7-epoxy-8-oxo-vincadifformine (6), vinorine N₄-oxide (7) and vinorine (8). The structures of the isolated compounds were established based on 1D and 2D (¹H-¹H-COSY, HMQC, HMBC, and ROESY) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential against seven tumor cell lines and anti-inflammatory activities. Compounds 3, 4 and 7 exhibited weak cytotoxicity against the tested cell lines and selective inhibition of Cox-2 (>85%).

New guaianolides from Artemisia anomala

Two new guaianolides artemanomalides A and B were isolated from the aerial parts of Artemisia anomala S. Moore. Their structures were characterized as 2-oxo-5α, 10α-dihydroxy-guaia-3-en-1α, 6β, 7α, 11β H-12, 6-olide (1) and 8α-acetoxy-2-oxo-5α, 10α-dihydroxy-guaia-3, 11(13)-dien-1α, 6β, 7αH-12, 6-olide (2) on the basis of extensive spectroscopic analyses. Compounds 1 and 2 showed inhibitory activities against COX-2 enzyme with IC(50) values of 8.8 and 3.6 μM.

Cyclooxygenase-2 inhibitors: a literature and patent review (2009 - 2010)

INTRODUCTION

COXs catalyze the complex conversion of arachidonic acid to prostaglandins and thromboxanes, which trigger as autacoids with autocrine and paracrine biological effects many physiological and pathophysiological responses. The structural similarities of the COX-1 and -2 enzymes make the search for selective inhibitors for COX-2 versus -1 a formidable challenge.

AREAS COVERED

The present review provides a survey of the development of novel COX-2 inhibitors covering literature and patents between 2009 and 2010. The presence of a central, typically 1,2-diaryl substituted, heterocycle or carbocycle as a characteristic structural motif in many selective COX-2 inhibitors represents the basis of their classification in this review. The classification in this review includes COX-2 inhibitors based on five- and six-membered heterocycles, benzoheterocycles (e.g., benzopyrans, benzopyranones, indoles and quinolines), quinones, chalcones, natural products and miscellaneous. When available, COX-2 inhibitors are presented with their related COX-2 inhibitory potency and selectivity.

EXPERT OPINION

The availability of detailed information on the crystal structure of the COX-2 enzyme with various substrates, cofactors and inhibitors, and the recently reported increased risk of cardiovascular events associated with selective COX-2 inhibitors will further stimulate development of COX-2 inhibitors with favorable COX-2 inhibition profiles without adverse effects to the cardiovascular system.

Triterpene saponins from Clematis chinensis and their potential anti-inflammatory activity

Seven new triterpene saponins, clematochinenosides A-G (1-7), together with 17 known saponins (8-24), were isolated from the roots and rhizomes of Clematis chinensis. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products. Compounds 1, 3-7, and 20-24 showed inhibitory activities against COX-1 and COX-2 enzymes.

Monoterpenoid indole alkaloids from Alstonia yunnanensis

Eight new monoterpenoid indole alkaloids, alstoyunines A-H (1-8), along with 17 known analogues, were isolated from Alstonia yunnanensis. The structures of the new alkaloids were established by means of extensive spectroscopic methods. Alstoyunines C (3), E (5), and F (6) showed selective inhibition of Cox-2 (>75%). Alstoyunine F (6) showed weak cytotoxicity against the human myeloid leukemia HL-60 (IC50 = 3.89 microM) and hepatocellular carcinoma SMMC-7721 (IC50 = 21.73 microM) cell lines.

Itosides J-N from Itoa orientalis and structure - anti-COX-2 activity relationship of phenolic glycosides

Two new phenolic glycosides, itosides J (1) and K (2), two new cylcohexenoyl glycosides, itosides L (3) and M (4), a new flavone glycoside, itoside N (5), and echitin (6) were isolated from the extract of the bark, twigs, and leaves of Itoa orientalis, together with 22 known compounds. The structures were elucidated by means of UV, IR, MS, and NMR techniques, and the relative configuration of compound 3 was confirmed by X-ray crystallography. NMR data for 6 are reported for the first time. Compounds 1, 3, 5, and phenolic glycosides 7- 22 were also assayed for anti-inflammatory activity against COX-2. Compounds 8, 10, 12- 14, 16, 19, 24, 26, and 27 showed significant inhibitory effects, with inhibitory rates of 49.7-85.3% at 10 microM.

Copper-aspirin complex inhibits cyclooxygenase-2 more selectively than aspirin

The antiinflammatory effects of the copper-aspirin complex (Cu-Asp) were more potent than that of Asp in rats or mice with fewer classic adverse effects. The aim of this study was to determine the cause by evaluating Cu-Asp selective inhibition on cyclooxygenases (COX). COX-1 inhibition was evaluated based on 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)) in an endothelial cell model, and COX-2 inhibition was based on prostaglandin E(2) (PGE(2)) in a macrophage model. Radioimmunoassay (RIA) was applied to determine 6-keto-PGF(1alpha) in resting human umbilical vein endothelial cell line (ECV304), and PGE(2) in activated macrophages. The results showed that the inhibition of 6-keto-PGF(1alpha) yield by Cu-Asp (3 to 0.01 mM) was markedly weaker than that by aspirin (Asp); while the inhibition of PGE(2) yield by Cu-Asp (10 to 0.1 mM) was significantly stronger than that by Asp. Based on the inhibition on 6-keto-PGF(1alpha) and PGE(2), the medium inhibitory concentration (IC(50)) of Cu-Asp on COX-1 and on COX-2 was 1.03+/-0.15 mM, and 0.32+/-0.04 mM, respectively. The selective inhibition index on COX-2, IC(50) (COX-1)/IC(50) (COX-2), of Cu-Asp was 3.33+/-0.89, while that of Asp was 0.42+/-0.12. The results suggest that, unlike Asp, Cu-Asp is a relatively selective inhibitor of COX-2 in the present models; the selectivity of Cu-Asp is about seven-fold greater than that of Asp.

Induction of lung lesions in Wistar rats by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and its inhibition by aspirin and phenethyl isothiocyanate

Background

The development of effective chemopreventive agents against cigarette smoke-induced lung cancer could be greatly facilitated by suitable laboratory animal models, such as animals treated with the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In the current study, we established a novel lung cancer model in Wistar rats treated with NNK. Using this model, we assessed the effects of two chemopreventive agents, aspirin and phenethyl isothiocyanate (PEITC), on tumor progression.

Methods

First, rats were treated with a single-dose of NNK by intratracheal instillation; control rats received iodized oil. The animals were then sacrificed on the indicated day after drug administration and examined for tumors in the target organs. PCNA, p63 and COX-2 expression were analyzed in the preneoplastic lung lesions. Second, rats were treated with a single-dose of NNK (25 mg/kg body weight) in the absence or presence of aspirin and/or PEITC in the daily diet. The control group received only the vehicle in the regular diet. The animals were sacrificed on day 91 after bronchial instillation of NNK. Lungs were collected and processed for histopathological and immunohistochemical assays.

Results

NNK induced preneoplastic lesions in lungs, including 33.3% alveolar hyperplasia and 55.6% alveolar atypical dysplasia. COX-2 expression increased similarly in alveolar hyperplasia and alveolar atypical dysplasia, while PCNA expression increased more significantly in the latter than the former. No p63 expression was detected in the preneoplastic lesions. In the second study, the incidences of alveolar atypical dysplasia were reduced to 10%, 10% and 0%, respectively, in the aspirin, PEITC and aspirin and PEITC groups, compared with 62.5% in the carcinogen-treated control group. COX-2 expression decreased after dietary aspirin or aspirin and PEITC treatment. PCNA expression was significantly reduced in the aspirin and PEITC group.

Conclusion

(1) A single dose of 25 mg/kg body weight NNK by intratracheal instillation is sufficient to induce preneoplastic lesions in Wistar rat lungs. (2) COX-2 takes part in NNK-induced tumorigenesis but is not involved in proliferation. (3) Aspirin and PEITC have protective effects in the early stages of tumor progression initiated by NNK.

Screening method for nonsteroidal antiinflammatory drugs based on the cyclooxygenase 2 pathway activated by serum-free stimulation in A549 cells

Cyclooxygenase 2 (COX-2) pathway inhibitors were regarded as promising nonsteroidal antiinflammatory drugs (NSAIDs). We discovered that the COX-2 pathway in A549 cells, a human lung cancer cell line, was activated by serum-free stimulation, and a drug screening model for NSAIDs was established based on this principle with simple performance and sufficient reliability. The COX-2 pathway was activated by treating with serum-free medium for 12 h. The activated cells were incubated with NS398 (selective COX-2 inhibitor), SC560 (selective COX-1 inhibitor), acetyl salicylic acid (ASA) (nonselective COX inhibitor) at 37 degrees C for 15 min. Then the cells were incubated with 10 microM of arachidonic acid (AA) for another 30 min prostaglandin E2 and 6-keto-prostaglandin F(1alpha) were assayed in an enzyme immunoassay (EIA). The results showed that the COX-2 pathway was dominant in A549 cells whether activated by serum-free medium or not, and the COX-1 pathway could be ignored. The model accepted the positive inhibition threshold as NS398 2 microM; if a compound (10 microM) inhibited COX-2 pathway more than NS398 (2 microM), it was regarded as a hit. The COX-2 pathway inhibition experiment showed that the Z;-factor of the screening model was 0.62, which suggests that the model is suitable for COX-2 pathway inhibitor screening.