Cyclooxygenase (COX) inhibitors induce apoptosis in non-small cell lung cancer through cyclooxygenase independent pathways

Searching for Drug Synergy Against Cancer Through Polyamine Metabolism Impairment: Insight Into the Metabolic Effect of Indomethacin on Lung Cancer Cells

Non-small cell lung cancer (NSCLC) is the most lethal and prevalent type of lung cancer. In almost all types of cancer, the levels of polyamines (putrescine, spermidine, and spermine) are increased, playing a pivotal role in tumor proliferation. Indomethacin, a non-steroidal anti-inflammatory drug, increases the abundance of an enzyme termed spermidine/spermine-N¹-acetyltransferase (SSAT) encoded by the SAT1 gene. This enzyme is a key player in the export of polyamines from the cell. The aim of this study was to compare the effect of indomethacin on two NSCLC cell lines, and their combinatory potential with polyamine-inhibitor drugs in NSCLC cell lines. A549 and H1299 NSCLC cells were exposed to indomethacin and evaluations included SAT1 expression, SSAT levels, and the metabolic status of cells. Moreover, the difference in polyamine synthesis enzymes among these cell lines as well as the synergistic effect of indomethacin and chemical inhibitors of the polyamine pathway enzymes on cell viability were investigated. Indomethacin increased the expression of SAT1 and levels of SSAT in both cell lines. In A549 cells, it significantly reduced the levels of putrescine and spermidine. However, in H1299 cells, the impact of treatment on the polyamine pathway was insignificant. Also, the metabolic features upstream of the polyamine pathway (i.e., ornithine and methionine) were increased. In A549 cells, the increase of ornithine correlated with the increase of several metabolites involved in the urea cycle. Evaluation of the levels of the polyamine synthesis enzymes showed that ornithine decarboxylase is increased in A549 cells, whereas S-adenosylmethionine-decarboxylase and polyamine oxidase are increased in H1299 cells. This observation correlated with relative resistance to polyamine synthesis inhibitors eflornithine and SAM486 (inhibitors of ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase, respectively), and MDL72527 (inhibitor of polyamine oxidase and spermine oxidase). Finally, indomethacin demonstrated a synergistic effect with MDL72527 in A549 cells and SAM486 in H1299 cells. Collectively, these results indicate that indomethacin alters polyamine metabolism in NSCLC cells and enhances the effect of polyamine synthesis inhibitors, such as MDL72527 or SAM486. However, this effect varies depending on the basal metabolic fingerprint of each type of cancer cell.

Nimesulide analogues: From anti-inflammatory to antitumor agents

Nimesulide is a nonsteroidal anti-inflammatory drug possessing analgesic and antipyretic properties. This drug is considered a selective cyclooxygenase-2 (COX-2) inhibitor and, more recently, has been associated to antitumor activity. Thus, numerous works have been developed to modify the nimesulide skeleton aiming to develop new and more potent and selective COX-2 inhibitors as well as potential anticancer agents. This review intends to provide an overview on analogues of nimesulide, including the general synthetic approaches used for their preparation and structural diversification and their main anti-inflammatory and/or antitumor properties.

In vitro antiglioma action of indomethacin is mediated via AMP-activated protein kinase/mTOR complex 1 signalling pathway

We investigated the role of the intracellular energy-sensing AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway in the in vitro antiglioma effect of the cyclooxygenase (COX) inhibitor indomethacin. Indomethacin was more potent than COX inhibitors diclofenac, naproxen, and ketoprofen in reducing the viability of U251 human glioma cells. Antiglioma effect of the drug was associated with p21 increase and G₂M cell cycle arrest, as well as with oxidative stress, mitochondrial depolarization, caspase activation, and the induction of apoptosis. Indomethacin increased the phosphorylation of AMPK and its targets Raptor and acetyl-CoA carboxylase (ACC), and reduced the phosphorylation of mTOR and mTOR complex 1 (mTORC1) substrates p70S6 kinase and PRAS40 (Ser183). AMPK knockdown by RNA interference, as well as the treatment with the mTORC1 activator leucine, prevented indomethacin-mediated mTORC1 inhibition and cytotoxic action, while AMPK activators metformin and AICAR mimicked the effects of the drug. AMPK activation by indomethacin correlated with intracellular ATP depletion and increase in AMP/ATP ratio, and was apparently independent of COX inhibition or the increase in intracellular calcium. Finally, the toxicity of indomethacin towards primary human glioma cells was associated with the activation of AMPK/Raptor/ACC and subsequent suppression of mTORC1/S6K. By demonstrating the involvement of AMPK/mTORC1 pathway in the antiglioma action of indomethacin, our results support its further exploration in glioma therapy.

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.

Indomethacin-enhanced anticancer effect of arsenic trioxide in A549 cell line: involvement of apoptosis and phospho-ERK and p38 MAPK pathways

BACKGROUND

Focusing on novel drug combinations that target different pathways especially apoptosis and MAPK could be a rationale for combination therapy in successful treatment of lung cancer. Concurrent use of cyclooxygenase (COX) inhibitors with arsenic trioxide (ATO) might be a possible treatment option.

METHODS

Cytotoxicity of ATO, dexamethasone (Dex), celecoxib (Cel), and Indomethacin (Indo) individually or in combination was determined at 24, 48, and 72 hrs in A549 lung cancer cells. The COX-2 gene and protein expression, MAPK pathway proteins, and caspase-3 activity were studied for the most cytotoxic combinations.

RESULTS

The IC50s of ATO and Indo were 68.7 μmol/L and 396.5 μmol/L, respectively. Treatment of cells with combinations of clinically relevant concentrations of ATO and Indo resulted in greater growth inhibition and apoptosis induction than did either agent alone. Caspase-3 activity was considerably high in the presence of ATO and Indo but showed no difference in single or combination use. Phosphorylation of p38 and ERK1/2 was remarkable in the concurrent presence of both drugs.

CONCLUSIONS

Combination therapy with ATO and Indo exerted a very potent in vitro cytotoxic effect against A549 lung cancer cells. Activation of ERK and p38 pathways might be the mechanism of higher cytotoxic effect of ATO-Indo combination.

Licofelone abolishes survival of carcinogenic fibroblasts by inducing apoptosis

Dual inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX) pathways of arachidonic acid metabolism prevent cancer development and induce apoptosis. One of the most promising compounds that blocks both of these pathways is licofelone. We questioned whether licofelone affects the survival and/or promotes apoptosis of H-ras transformed rat embryonic fibroblast (5RP7) cells in vitro. Using 5-fluorouracil (5-FU) and colchicine as positive controls, we determined cell viability with 3-3-(4,5-D-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, thyazolyl blue (MTT), apoptosis with flow cytometry and activity of caspase enzyme with real-time reverse transcription polymerase chain reaction (PCR). Compared to the control, all used six doses (10, 50, 100, 150, 250 and 250 µM) of 5-FU, colchicine and licofelone, which were cytotoxic and reduced the number of H-Ras transformed 5RP7 cells by as much as 78, 72 and 92%, respectively. In addition, we found that 150, 200 and 250 µM of licofelone induced apoptosis and necrosis of H-Ras transformed 5RP7 cells in a dose- and time-dependent manner. Each three tested drugs at 250 µM also increased the level of caspase-3 enzyme up to 5-fold. Although colchicine was effective in inducing early apoptosis, licofelone had much more capacity to induce the total of early plus late apoptosis by approximately 96% in cells after 48 hours. The present study reveals the possibility that licofelone posseses strong dose- and time-dependent anticancer and apoptotic properties on carcinogenic fibroblasts.

Sulfatide regulates caspase-3-independent apoptosis of influenza A virus through viral PB1-F2 protein

Influenza A virus (IAV) generally causes caspase-dependent apoptosis based on caspase-3 activation, resulting in nuclear export of newly synthesized viral nucleoprotein (NP) and elevated virus replication. Sulfatide, a sulfated galactosylsphingolipid, enhances IAV replication through promoting newly synthesized viral NP export induced by association of sulfatide with hemagglutinin delivered to the cell surface. Here, we demonstrated that sulfatide is involved in caspase-3-independent apoptosis initiated by the PB1-F2 protein of IAV by using genetically sulfatide-produced cells and PB1-F2-deficient IAVs. Sulfatide-deficient COS7 cells showed no virus-induced apoptosis, whereas SulCOS1 cells, sulfatide-enriched COS7 cells that genetically expressed the two transferases required for sulfatide synthesis from ceramide, showed an increase in IAV replication and were susceptible to caspase-3-independent apoptosis. Additionally, PB1-F2-deficient IAVs, which were generated by using a plasmid-based reverse genetics system from a genetic background of A/WSN/33 (H1N1), demonstrated that PB1-F2 contributed to caspase-3-independent apoptosis in IAV-infected SulCOS1 cells. Our results show that sulfatide plays a critical role in efficient IAV propagation via caspase-3-independent apoptosis initiated by the PB1-F2 protein.

Combined histone deacetylase and cyclooxygenase inhibition achieves enhanced antiangiogenic effects in lung cancer cells

Prostaglandin E2 (PGE2) is an important pro-angiogenic and pro-proliferative cytokine and the key enzymes modulating its levels, cyclooxygenase (COX)-2 and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) play important opposing roles in carcinogenesis. Previously we found loss of 15-PGDH expression in lung cancer and its reactivation leads to strong in vivo tumor-suppressive effect via an antiangiogenic mechanism. Here, we find that HDAC inhibitors (HDACI), such as trichostatin A (TSA) and vorinostat could reactivate 15-PGDH expression but overall induce PGE2 generation and this is the result of concomitant induction of COX-1 and -2 leading to functional promotion of endothelial cell proliferation and capillary formation. Direct TSA treatment inhibits endothelial cell proliferation and capillary formation in our study in line with prior reports as HDACIs have been shown to directly inhibit angiogenesis. The elevation of PGE2 levels induced by HDACI is potently neutralized by indomethacin (INN) or Celecoxib co-treatment and accordingly, angiogenesis is more effectively inhibited when using conditioned medium of co-treatment than either alone confirming that this effect is mediated via the PGE2 axis. Accordingly, blockage of EP2/4 receptors mitigates the stimulation of angiogenesis by excessive PGE2 generation mediated by TSA. In this study, we identify a potentially adverse effect of HDACIs through induction of both 15-PGDH and COX-2 leading to elevated PGE2 levels and thereby stimulation of angiogenesis. Co-treatment of TSA and INN shows more potent anti-angiogenic effects by inducing 15-PGDH and inhibiting COX-2. Overall, our results suggest that combined HDACI and COX inhibition should be explored clinically to achieve more meaningful benefits from HDACI therapy in lung cancer.

The effect of hypoxia and cycloxygenase inhibitors on nasal polyp derived fibroblasts

BACKGROUND AND PURPOSE

The pathogenesis of chronic rhinosinusitis with nasal polyposis is unknown. Chronic inflammation along with local tissue hypoxia may effect polyp's growth. Activation of Cycloxygenases may also be involved. COX-2 up-regulates in response to different stimuli including hypoxia. Its activation is associated with enhanced cell proliferation. Histologically, besides inflammatory cells, increased stromal fibrosis is seen in nasal polyposis. The aims of this study were to test whether hypoxia amplifies nasal polyp fibroblasts proliferation, whether treatment with various COX inhibitors could influence fibroblasts, and whether this effect may be modulated in response to different oxygenation conditions.

MATERIALS AND METHODS

Polyp fibroblasts were incubated under hypoxic or normoxic conditions with or without NSAIDs at different concentrations for 12 or 24 hours. Cell proliferation was quantified using BrdU ELISA. Metabolic activity was evaluated using MTT assay. Cell death was measured using Annexin V staining and FACS scan.

RESULTS

No significant difference was found between proliferation of fibroblasts treated under hypoxia or normoxia. Cells incubated with indomethacin proliferated in a slightly enhanced manner compared with non-treated cells. Celecoxib inhibited fibroblast proliferation (P < .001) but did not influence cell survival. Metabolic activity of cells treated with celecoxib was significantly reduced (P < .003), unlike cells treated with indomethacin or rofecoxib.

CONCLUSION

Hypoxia does not affect fibroblasts proliferation. It may contribute to nasal polyposis pathogenesis in other ways. The anti-proliferative effect of celecoxib may be associated with cell cycle arrest rather than with pro-apoptotic activity. Celecoxib may be considered for treating nasal polyposis.

Cycloxygenase inhibition enhances the effects of surfactant therapy in endotoxin-induced rat model of ARDS

The present study examines the relationships between inflammation and surfactant protein (SP) expression in a rodent model of acute respiratory distress syndrome (ARDS). Rats were intratracheally instilled with lipopolysaccharide (LPS) for 72 hours to induce ARDS and further treated with exogenous surfactant. Prostaglandin E(2) (PGE(2)) levels, cycloxygenase (COX) activity and alterations in SP-A apoprotein were measured. COX and SP-A expressions in lung tissue and SP-A-positive cells were determined by Western blot and immunofluorescence, respectively. PGE(2) levels and COX activity and its expression were increased with LPS exposure, whereas SP-A protein and percentage of SP-A-positive cells were decreased, which were subsequently reverted back by exogenous surfactant instillation. Because inhibition of COX-2 action is proposed to be useful in various inflammatory lung injuries, these results suggest that COX-2 expression and the possible beneficial effects of its inhibition on lung inflammation and dysfunction with LPS-ARDS corresponds closely with reduced SP-A expression.

The synergistic anticancer effect of troglitazone combined with aspirin causes cell cycle arrest and apoptosis in human lung cancer cells

Troglitazone (TGZ) is a synthetic thiazolidinedione drug belonging to a group of potent peroxisome proliferator-activated receptor gamma (PPAR gamma) agonists known to inhibit proliferation, alter cell cycle regulation, and induce apoptosis in various cancer cell types. TGZ is an oral anti-type II diabetes drug that can reverse insulin resistance. For more then 100 yr, aspirin, a nonselective cyclooxygenase (COX) inhibitor, has been successfully used as an anti-inflammatory drug. Recently, Aspirin (ASA) and some other nonsteroidal anti-inflammatory drugs (NSAIDs) have drawn much attention for their protective effects against colon cancer and cardiovascular disease; it has been observed that ASA's anti-tumor effect can be attributed to inhibition of cell cycle progression, induction of apoptosis, and inhibition of angiogenesis. In this report we demonstrate for the first time that, when administered in combination, TGZ and ASA can produce a strong synergistic effect in growth inhibition and G(1) arrest in lung cancer CL1-0 and A549 cells. Examination by colony formation assay revealed an even more profound synergy. In Western blot, combined TGZ and ASA also could downregulate Cdk2, E2F-1, cyclin B1, cyclin D3 protein, and the ratio of phospho-Rb/Rb. Importantly, apoptosis was synergistically induced by the combination treatment, as evidenced by caspase-3 activation and PARP cleavage. The involvement of PI3K/Akt inhibition and p27 upregulation, as well as hypophosphorylation of Rac1 at ser71, were demonstrated. Taken together, these results suggest that clinically achievable concentrations of TGZ and ASA used in combination may produce a strong anticancer synergy that warrants further investigation for its clinical applications.

Enhancement of 5-fluorouracil efficacy on high COX-2 expressing HCA-7 cells by low dose indomethacin and NS-398 but not on low COX-2 expressing HT-29 cells

The antiproliferative effect of 5-fluorouracil (5-FU) in the presence of low dose non-steroidal anti-inflammatory drugs (NSAIDs) on high cyclooxygenase-2 (COX-2)-expressing HCA-7 and low COX-2-expressing HT-29 colon carcinoma cell lines was investigated. Pharmacogenetic parameters were studied to characterize the 5-FU sensitivity of the two cell lines. Thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) polymorphisms were determined by PCR analysis. Cell proliferation was measured by SRB assay, cell cycle distribution and apoptosis by FACS analysis. Cyclooxygenase expression was detected by Western blot and also by fluorescence microscopy. Prostaglandin E(2) (PGE(2)) levels were investigated with ELISA kit. The HT-29 cell line was found to be homozygous for TS 2R and 1494ins6 and T homozygous for MTHFR 677 polymorphisms predicting high 5-FU sensitivity (IC(50): 10 microM). TS 3R homozygosity, TS 1496del6 and MTHFR 677CT heterozygosity may explain the modest 5-FU sensitivity (IC(50): 1.1 mM) of the HCA-7 cell line. Indomethacin and NS-398 (10 microM and 1.77 microM, respectively) reduced the PGE(2) level in HCA-7 cells (>90%). Low concentrations of NSAIDs without antiproliferative potency increased the S-phase arrest and enhanced the cytotoxic action of 5-FU only in HCA-7 cells after 48-hours treatment. The presented data suggested that the enhancement of 5-FU cytotoxicity by indomethacin or NS-398 applied in low dose is related to the potency of NSAIDs to modulate the cell-cycle distribution and the apoptosis; however, it seems that this effect might be dependent on cell phenotype, namely on the COX-2 expression.

Human monocytes but not dendritic cells are killed by blocking of autocrine cyclooxygenase activity

Dendritic cells (DCs), in peripheral tissues, derive mostly from blood precursors that differentiate into DCs under the influence of the local microenvironment. Monocytes constitute the main known DC precursors in blood and their infiltration into tissues is up-regulated during inflammation. During this process, the local production of mediators, like prostaglandins (PGs), influence significantly DC differentiation and function. In the present paper we show that treatment of blood adherent mononuclear cells with 10microM indomethacin, a dose achieved in human therapeutic settings, causes monocytes' progressive death but does not affect DCs viability or cell surface phenotype. This resistance of DCs was observed both for cells differentiated in vitro from blood monocytes and for a population with DCs characteristics already present in blood. This phenomenon could affect the local balance of antigen-presenting cells, influence the induction and pattern of immune responses developed under the treatment with non-steroidal anti-inflammatory drugs and, therefore, deserves further investigation.

Phase II study of celecoxib with cisplatin plus etoposide in extensive-stage small cell lung cancer

We performed a phase II trial to test whether a cyclooxygenase (COX-2) inhibitor, celecoxib, added to standard first-line combination chemotherapy (CT) and as maintenance therapy would improve outcomes in extensive-stage (ES) small-cell lung cancer (SCLC). This was a multicenter trial in CT-naive patients with ES-SCLC. They received standard cisplatin and etoposide (EP) up to 6 cycles and celecoxib 400 mg PO bid continuously until disease progression. Primary end points were response rate (RR), time to progression (TTP), and toxicity. Secondary were overall survival (OS) and quality of life. Of 74 expected patients, only 24 were enrolled and the study stopped earlier because of the published safety concerns about celecoxib. The patients, all male, were between 38 and 74 years. A total of 130 cycles of CT were administered. Toxicity associated with celecoxib was minimal. The RR was 56.5%. Median TTP and OS were 8.6 and 11.3 months, respectively. These data suggest that celecoxib may safely be combined with EP for treatment of ES-SCLC. This combination showed a promising activity and, despite the safety concerns regarding celecoxib, it would be interesting to further evaluate this regimen.

A COX-2 inhibitor nimesulide analog selectively induces apoptosis in Her2 overexpressing breast cancer cells via cytochrome c dependent mechanisms

Epidemiological and animal model studies have suggested that non-steroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anti-cancer effect in different type of cancers. In the current study, five breast carcinoma cell lines were used to explore the anti-cancer mechanisms of a nimesulide derivative compound 76. The compound dose dependently suppressed SKBR-3, BT474 and MDA-MB-453 breast cancer cell proliferation with IC(50) of 0.9microM, 2.2microM and 4.0microM, respectively. However, it needs much higher concentrations to inhibit MCF-7 and MDA-MB-231 breast cancer cell growth with IC(50) at 22.1microM and 19.6microM, respectively. Further investigation reveals that compound 76 induced apoptosis in SKBR-3 and BT474 cells. Since these cells are Her2 overexpressing cells, the Her2 intracellular signaling pathways were examined after the treatment. There was no significant changing of kinase activity. However, the cytochrome c release assay indicated that the apoptosis induced by the compound was mediated by the mitochondria. These results suggest that compound 76 selectively induce apoptosis in Her2 overexpressing breast cancer cells through the mitochondria, and could be used as a lead to design more potent derivatives.

Effects of COX-2 inhibition on expression of vascular endothelial growth factor and interleukin-8 in lung cancer cells

BACKGROUND

Cyclooxygenase (COX)-2 has been implicated in tumour progression, angiogenesis and metastasis in non-small cell lung cancer (NSCLC). We speculated that inhibition of COX-2 activity might reduce expression of the pro-angiogenic factors vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) in lung cancer cells.

METHODS

The levels of IL-8, VEGF and prostaglandin E2 (PGE2) were measured by ELISA. Expression of COX-1 and COX-2 was determined by Western blotting. Inhibition or knockdown of COX-2 was achieved by treating NSCLC cells with specific COX-2 inhibitor NS-398 or COX-2 siRNA, respectively.

RESULTS

We found that NSCLC cell lines produced more IL-8 than VEGF (p < 0.001). In contrast, small cell lung cancer (SCLC) cell lines produced more VEGF than IL-8 (p < 0.001). COX-1 was expressed in all cell lines, but COX-2 was expressed only in NSCLC cell lines. Consistent with this, PGE2 was significantly higher in NSCLC cell lines than SCLC cell lines (p < 0.001). We tested these cell lines with a potent specific COX-2 inhibitor NS-398 at concentrations of 0.02, 0.2, 2, 20 microM for 24 or 48 h. The COX-2 activity was reduced in a dose-dependent fashion as shown by reduced PGE2 production. VEGF was significantly reduced following the treatment of NS-398 in A549 (by 31%) and MOR/P (by 47%) cells lines which expressing strong COX-2, but not in H460 cell line which expressing very low COX-2. However, IL-8 was not reduced in these cell lines. To confirm these results, we knocked down COX-2 expression with COX-2 siRNA in these cell lines. VEGF was significantly decreased in A549 (by 24%) and in MOR/P (by 53%), but not in H460 whereas IL-8 was not affected in any cell line.

CONCLUSION

We conclude that NSCLC cells produce much higher levels of IL-8 than SCLC cells whereas both NSCLC and SCLC cells produce similar levels of VEGF. COX-2 is only expressed in NSCLC cells, but not in SCLC cells. VEGF is produced in both NSCLC and SCLC cells regardless of COX-2 expression. However, VEGF production is, at least partly, COX-2 dependent in NSCLC cells expressing COX-2. In contrast, IL-8 production is COX-2 independent in both NSCLC and SCLC cells. We speculate that combined targeting of COX-2 and IL-8 may be useful in the treatment of patients with NSCLC and targeting VEGF may be useful in the treatment of patients with SCLC.

Synthesis and biological evaluation of novel sulfonanilide compounds as antiproliferative agents for breast cancer

Combinatorial chemistry approaches facilitate drug discovery processes and result in structural modifications of lead compounds that enhance pharmacological activity, improve pharmacokinetic properties, or reduce unwanted side effects. Epidemiological and animal model studies have suggested that nonsteroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anticancer effects in several cancer cell lines via COX-2-dependent and -independent mechanisms. The molecular structure of nimesulide was used as a starting scaffold to design novel sulfonanilide analogs and examine the structural features that contribute to this anticancer effect. A systematic combinatorial chemical approach was used to generate diversely substituted sulfonanilide derivatives that were tested for their effects on the proliferation of human breast cancer cells. Structure-function analysis indicated that the inhibition of cell growth by compounds derived from the novel sulfonanilides required a bulky terminal phenyl ring, a methanesulfonamide, and a hydrophobic carboxamide moiety.

Selective COX-2 inhibitor celecoxib combined with EGFR-TKI ZD1839 on non-small cell lung cancer cell lines: in vitro toxicity and mechanism study

Constitutive expression of cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) occurs frequently in non-small cell lung cancer (NSCLC). Anticancer research targeting EGFR has got an extensive attention especially in NSCLC and COX-2 inhibitor also shown a certain anticancer activity in recent years. Simultaneously targeting COX-2 and EGFR may be a promising therapeutic way. We carried out the in vitro study using selective COX-2 inhibitor celecoxib combined with EGFR-tyrosine kinase inhibitor (EGFR-TKI) ZD1839 on NSCLC cell lines to investigate the anti proliferation effect and the cell molecular mechanism. MTT growth assay showed the synergistic therapeutic effect of certain concentration of celecoxib combined with ZD1839 and synergistic apoptosis effect was detected by Hoechest33258 fluorescence staining and flow cytometric analysis. In western blot analysis, ZD1839 single agent inhibited the activation of EGFR and downstream cell signal transduction AKT and extrocellular signal-regulated kinase (ERK) pathways, the transcription activity of nuclear factor-kappa B (NF-kappaB), and the expression of COX-2. Celecoxib single agent could also inhibit AKT and ERK pathway in NSCLC, even the EGFR expression under high concentration treatment. Celecoxib combined with ZD1839 led to stronger inhibition of related cell signal transduction pathways in NSCLC.

Isolation of cytoplasmatic proteins from cultured cells for two-dimensional gel electrophoresis

Cytoplasma is the cell interior place between the cellular membrane and the nucleus, where various intracellular activities take place, including energy production, reactive oxygen species (ROS) detoxification, heme synthesis, nitrogen and lipid metabolism, phosphorylation in signal transduction, and cytoskeletal meshwork construction. The rich cytoplasmatic proteins carrying out these intracellular functions are interesting targets for biochemical and molecular biological studies. The relatively recent discipline of proteomics offers a chance to globally analyze the changes in cytoplasmic proteins corresponding to drug treatments or disease conditions, and thus provide target candidates for further biological validation in drug development and biomarker discovery. Isolation of cytoplasmic proteins from cells is a necessary step for high resolution protein separation by two-dimensional gel electrophoresis (2DE) and specific proteomic analysis.

Cyclooxygenase in the treatment of glioma: its complex role in signal transduction

BACKGROUND

High-grade glioma remains one of the most difficult cancers to treat. Recent studies in oncology have identified a role of the ubiquitous enzyme, cyclooxygenase (Cox), especially cyclooxygenase-2 (COX-2) in cell proliferation, and its inhibition in cancer control, apoptosis, as well as synergy with other forms of therapy. The inhibitors of the Cox enzyme are well known as members of the nonsteroidal anti-inflammatory drug (NSAID) class of pharmaceuticals.

METHODS

In vitro and in vivo studies of different cancers expressing COX-2, including glioma studies, along with the few clinical trials that have been reported are reviewed to specifically identify the actions of these agents.

RESULTS

The anticancer effect of the COX-2 inhibitors may occur irrelevant of COX-2 expression, and it appears to be drug-specific, as well as dose-specific in different cancers. In combination with chemotherapeutic agents, the COX-2 inhibitors may have an additive, synergistic, or inhibitory effect on tumor growth.

CONCLUSIONS

As evaluations of this class of drugs begin in glioma, in vitro and in vivo data should be acquired to accurately predict which compounds will have an effect in controlling tumor growth and at which doses these should be used. The actual expression and inhibition of COX-2 may not always be relevant to the effects on tumor growth.

Radiosensitizing potential of the selective cyclooygenase-2 (COX-2) inhibitor meloxicam on human glioma cells

The COX-2 protein is frequently overexpressed in human malignant gliomas. This expression has been associated with their aggressive growth characteristics and poor prognosis for patients. Targeting the COX-2 pathway might improve glioma therapy. In this study, the effects of the selective COX-2 inhibitor meloxicam alone and in combination with irradiation were investigated on human glioma cells in vitro. A panel of three glioma cell lines (D384, U87 and U251) was used in the experiments from which U87 cells expressed constitutive COX-2. The response to meloxicam and irradiation (dose-range of 0-6 Gy) was determined by the clonogenic assay, cell proliferation was evaluated by growth analysis and cell cycle distribution by FACS. 24-72 h exposure to 250-750 microM meloxicam resulted in a time and dose dependent growth inhibition with an almost complete inhibition after 24 h for all cell lines. Exposure to 750 microM meloxicam for 24 h increased the fraction of cells in the radiosensitive G(2)/M cell cycle phase in D384 (18-27%) and U251 (17-41%) cells. 750 microM meloxicam resulted in radiosensitization of D384 (DMF:2.19) and U87 (DMF:1.25) cells, but not U251 cells (DMF:1.08). The selective COX-2 inhibitor meloxicam exerted COX-2 independent growth inhibition and radiosensitization of human glioma cells.

Synthesis and biological activities of novel dexibuprofen tetraacetylriboflavin conjugates

A series of novel dexibuprofen derivatives covalently linked via alkylene spacers of variable length to tetraacetylated riboflavin have been developed. The target compounds became accessible by reaction of the chloromethyl ester of dexibuprofen with tetraacetylriboflavin (compound 7) or by synthesis of the appropriate N3-(omega-iodoalkyl)-2',3',4',5'-Tetraacetylriboflavin followed by treatment with dexibuprofen (derivatives 8-11), respectively. Biological screening revealed that the target compounds exhibit antiproliferative effects on MCF-7 breast cancer and HT-29 colon carcinoma cells with IC50 values in the range of 8-15 microM. Enzymatic studies on human platelets indicated significant COX-1 inhibitory activities of the target compounds.

Synergistic induction of apoptosis by sulindac and arsenic trioxide in human lung cancer A549 cells via reactive oxygen species-dependent down-regulation of survivin

Survivin, a member of the inhibitor of apoptosis protein (IAP) family, may be a good target for cancer therapy because it is expressed in a variety of human tumors but not in differentiated adult tissues. In the present study, we show that a combination of sulindac and arsenic trioxide (ATO) induces more extensive apoptosis than either drug alone in A549 human non-small cell lung carcinoma (NSCLC) cells. Treatment with sulindac/ATO reduced the expression of survivin and promoted major apoptotic signaling events, namely, collapse of the mitochondrial membrane potential, release of cytochrome c, and activation of caspases. Combined sulindac/ATO treatment did not significantly affect the levels of other members of the IAP family (XIAP, cIAP1 and cIAP2), indicating that the effects were specific to survivin. In addition, sulindac/ATO treatment induced the production of reactive oxygen species and the antioxidant N-acetyl-l-cysteine blocked the down-regulation of survivin and induction of apoptotic signaling by the combination of sulindac and ATO. Combined sulindac/ATO treatment also activated p53 expression, and inhibition of p53 expression by small interfering RNA (siRNA) prevented sulindac/ATO-induced down-regulation of survivin, suggesting that survivin expression is negatively regulated by p53. Overexpression of survivin reduced sulindac/ATO-induced apoptosis in A549 cells and reduction of survivin levels by siRNA sensitized the cells to sulindac/ATO-induced cell death. These results demonstrate that, in A549 human NSCLC cells, sulindac/ATO-induced apoptosis is mediated by the reactive oxygen species-dependent down-regulation of survivin.

Parthenolide cooperates with NS398 to inhibit growth of human hepatocellular carcinoma cells through effects on apoptosis and G0-G1 cell cycle arrest

Chemotherapy to date has not been effective in the treatment of human hepatocellular carcinoma. More effective treatment strategies may involve combinations of agents with activity against hepatocellular carcinoma. Parthenolide, a nuclear factor-kappaB (NF-kappaB) inhibitor, and NS398, a cyclooxygenase (COX)-2 inhibitor, have been shown to individually suppress the growth of hepatocellular carcinoma cells in vitro. To investigate their effects in combination, three human hepatocellular carcinoma lines (Hep3B, HepG2, and PLC) were treated with parthenolide and/or NS398. Parthenolide (0.1-10 micromol/L) and NS398 (1-100 micromol/L) each caused concentration-dependent growth inhibition in all cell lines. The addition of parthenolide to NS398 reduced the concentration of NS398 required to inhibit hepatocellular carcinoma growth. Because parthenolide and COX-2 inhibitors have been reported to influence NF-kappaB activity, the effects on this pathway were investigated. The combination of parthenolide/NS398 inhibited phosphorylation of the NF-kappaB-inhibitory protein IkappaBalpha and increased total IkappaBalpha levels. NF-kappaB DNA-binding and transcriptional activities were inhibited more by the combination than the single agents in Hep3B and HepG2 cells but not in PLC cells. The response of PLC cells to NS398 was augmented by p65 small interfering RNA to inhibit NF-kappaB p65 protein expression. The combination of parthenolide/NS398 increased apoptosis only in PLC cells, suggesting that the combination may decrease the apoptotic threshold in these cells. In Hep3B and HepG2 cells, combination treatment with NS398/parthenolide altered the cell cycle distribution resulting in more G0-G1 accumulation. Cyclin D1 levels were further decreased by combination treatment in all cell lines, correlating with the cell cycle alterations. Our results suggest that parthenolide may be effective in combination with COX-2 inhibitors for the treatment of hepatocellular carcinoma.

Aldo-keto reductase (AKR) 1C3: role in prostate disease and the development of specific inhibitors

Human aldo-keto reductases (AKR) of the 1A, 1B, 1C and 1D subfamilies are involved in the pre-receptor regulation of nuclear (steroid hormone and orphan) receptors by regulating the local concentrations of their lipophilic ligands. AKR1C3 is one of the most interesting isoforms. It was cloned from human prostate and the recombinant protein was found to function as a 3-, 17- and 20-ketosteroid reductase with a preference for the conversion of Delta4-androstene-3,17-dione to testosterone implicating this enzyme in the local production of active androgens within the prostate. Using a validated isoform specific real-time RT-PCR procedure the AKR1C3 transcript was shown to be more abundant in primary cultures of epithelial cells than stromal cells, and its expression in stromal cells increased with benign and malignant disease. Using a validated isoform specific monoclonal Ab, AKR1C3 protein expression was also detected in prostate epithelial cells by immunoblot analysis. Immunohistochemical staining of prostate tissue showed that AKR1C3 was expressed in adenocarcinoma and surprisingly high expression was observed in the endothelial cells. These cells are a rich source of prostaglandin G/H synthase 2 (COX-2) and vasoactive prostaglandins (PG) and thus the ability of recombinant AKR1C enzymes to act as PGF synthases was compared. AKR1C3 had the highest catalytic efficiency (kcat/Km) for the 11-ketoreduction of PGD2 to yield 9alpha,11beta-PGF2 raising the prospect that AKR1C3 may govern ligand access to peroxisome proliferator activated receptor (PPARgamma). Activation of PPARgamma is often a pro-apoptotic signal and/or leads to terminal differentiation, while 9alpha,11beta-PGF2 is a pro-proliferative signal. AKR1C3 is potently inhibited by non-steroidal anti-inflammatory drugs suggesting that the cancer chemopreventive properties of these agents may be mediated either by inhibition of AKR1C3 or COX. To discriminate between these effects we developed potent AKR1C inhibitors based on N-phenylanthranilic acids that do not inhibit COX-1 or COX-2. These compounds can now be used to determine the role of AKR1C3 in producing two proliferative signals in the prostate namely testosterone and 9alpha,11beta-PGF2.

Inhibition of COX-2 aggravates neutrophil migration and pneumocyte apoptosis in surfactant-depleted rat lungs

Pulmonary inflammation and parenchymal apoptosis are implicated in the pathogenesis of the acute lung injury, but the mechanisms of these reactions are still unclear. Because inhibition of the proinflammatory cyclo-oxygenase (COX)-2 enzyme action is proposed to be useful in various inflammatory lung injuries, we decided to investigate the expression of COX-2 and the possible beneficial effects of its inhibition on pulmonary inflammation and apoptosis in surfactant-depleted lungs. The injury was induced in 2-mo-old rats by repeated lung lavage to remove alveolar surfactant. Eight of these rats were pretreated with a specific COX-2 inhibitor, NS-398. All rats, including control rats without lung lavage, were ventilated with 60% oxygen for 5 h, and the lungs were then studied histologically for tissue injury and with DNA nick-end labeling, cleaved caspase-3 immunohistochemistry, and electron microscopy for apoptotic cell death. Lung tissue myeloperoxidase activity and the expression of COX-2 protein and concentration of prostaglandin E2 were additionally analyzed. Lung lavage increased pulmonary neutrophil migration, histologic injury, and the occurrence of epithelial apoptosis. In contrast, expression of COX-2 and amount of PGE2 were significantly lower in surfactant-depleted lungs than controls. Pretreatment with the COX-2 inhibitor further increased the migration of neutrophils and occurrence of epithelial apoptosis in the surfactant-depleted lungs, compared with nontreated insulted lungs. These results suggest that specific inhibitors of COX-2 should be used cautiously in association with surfactant-deficient lung injuries.

Cytotoxicity of a non-cyclooxygenase-2 inhibitory derivative of celecoxib in non-small-cell lung cancer A549 cells

Lung cancer is one of the most common causes of cancer death worldwide. Although recent advances in chemotherapy and radiation therapy have yielded modest improvements in patient outcomes, overall survival remains poor. Therefore, new therapeutic targets are needed. Phosphoinositide-dependent kinase-1 (PDK1) is one potential target. The aim of the present studies was to investigate the potential of a celecoxib-derived PDK1 inhibitor (OSU03013), that does not inhibit cyclooxygenase-2, to kill lung cancer cells in vitro. Using human non-small-cell lung cancer A549 cells, OSU03013 dose-dependently induced apoptosis. After 6 h of treatment with 7.5 microM OSU03013, 26% of the cells were apoptotic, compared to 4% of the control cells as determined by measuring the sub-G1 peak of propidium iodide stained cells with flow cytometry. A similar increase in apoptosis was evident using the Cell Death ELISA assay. OSU03013-induced apoptosis was accompanied by a reduction in the mitochondrial membrane potential, the release of cytochrome c and the cleavage of caspase-3. Surprisingly, the phosphorylation of Akt at serine 473 was increased in A549 cells treated with 7.5 microM OSU03013. However, the toxicity of OSU03013 was reduced in A549 cells expressing a constitutively active form of Akt. These data demonstrate that OSU03013 induces apoptosis in A549 cells via the mitochondrial pathway. Inhibition of the Akt pathway appears uninvolved in this toxicity, although Akt can provide protection. These results also suggest the potential of celecoxib-derived agents to treat some forms of lung cancer.

COX-2 inhibitors suppress lung cancer cell growth by inducing p21 via COX-2 independent signals

COX-2 has been implicated in the control of human non-small cell lung carcinoma (NSCLC) cell growth. The mechanisms by which COX-2 exerts its mitogenic effects have not been entirely elucidated, but stimulation of prostaglandin E2 production and alterations in the expression of the cyclin-dependent kinase inhibitor p21(WAF-1/CIP1/MDA-6)(p2i) have been suggested. Here, we demonstrate that two COX-2 inhibitors (NS398 and Nimesulide) inhibit proliferation and induce apoptosis in NSCLC cells, and these effects were associated with induction of p21 mRNA and protein expression. However, the anti-growth effect of the COX-2 inhibitors and their ability to induce p21 were not affected by COX-2 siRNA suggesting that their actions were COX-2 independent. Instead, activation of the MEK-1/Erk pathway was necessary since COX-2 inhibitors stimulated the phosphorylation of ERKs, and their effects were blocked by PD98095, an inhibitor of this pathway. Furthermore, we show that both NS398 and Nimesulide induced p21 gene promoter activity and this was prevented by PD98095. COX-2 inhibitors increased nuclear protein binding to the Spl site in the promoter region of the p21 gene. Consistent with a role for p21, we found that p21 antisense oligonucleotides prevented the effects of COX-2 inhibitors on cell growth. In summary, our results suggest that COX-2 inhibitors suppress NSCLC cell growth by inducing the expression of the p21 gene through MEK-1/ERK signaling and DNA-protein interactions involving Spl. These observations unveil a mechanism for p21 gene regulation by COX-2 inhibitors in lung carcinoma cell growth and this pathway represents a potential target for therapy.

Chemoprevention strategies with cyclooxygenase-2 inhibitors for lung cancer

Clinical lung cancer is the ultimate event resulting from a series of genetic and epigenetic alterations in the respiratory epithelium at risk. According to the "field carcinogenesis" theory, these alterations can occur throughout the entire lung. In individuals with a genetic predisposition combined with a sufficient amount of procarcinogenic environmental influences, a few of these sites may eventually progress to malignancies. Recent advances in the understanding of tumor biology have identified new therapeutic targets for lung cancer chemoprevention, among which is cyclooxgygenase (COX)-2. Ample preclinical data suggest that the COX-2/prostaglandin E2 (PGE2) signaling pathway plays a pivotal role in conferring the malignant phenotype. Produced primarily by the action of COX on the free arachidonic acid liberated from membrane phospholipids, overproduction of PGE2, which is predominantly generated by upregulation of COX-2, is associated with a variety of mechanisms known to facilitate tumorigenesis. These mechanisms include abnormal expression of epithelial growth factors, epithelial and microvascular proliferation, resistance to apoptosis, and suppression of antitumor immunity. The lung is one of the major sites of PGE2 production, and previous studies have shown elevated PGE2 levels in bronchoalveolar lavage fluid of patients with bronchogenic carcinoma. In animal models, inhibition of COX-2 and PGE2 synthesis suppresses lung tumorigenesis. These preclinical data suggesting the antineoplastic effect of COX-2 inhibitors provide the basis for several ongoing pilot clinical trials to determine the feasibility of COX-2 inhibition in chemoprevention of bronchogenic carcinoma.

Molecular pathology of non-small-cell lung cancer

The molecular basis of lung carcinogenesis must be understood more fully and exploited to enhance survival rates of patients suffering from lung cancer. In this review we will discuss the major molecular alterations that occur in lung cancer. Emphasis is placed on alterations that occur early during carcinogenesis since they might be relevant for future screening programs. Finally we will shortly review new approaches that are used to study the molecular pathology of lung cancer and how they can be applied in a clinical setting.

Dimethyl celecoxib as a novel non-cyclooxygenase 2 therapy in the treatment of non-small cell lung cancer

OBJECTIVES

The cyclooxygenase 2 enzyme has become a therapeutic target in cancer treatment. Cyclooxygenase 2 blockade with selective inhibitors increases apoptosis and decreases the metastatic potential of lung cancer cells. Some of the antitumor effects of these inhibitors may occur through both cyclooxygenase 2-dependent and independent pathways. Our goal was to investigate these pathways using celecoxib (selective cyclooxygenase 2 inhibitor) and 2,5-dimethyl celecoxib, a structural analog modified to eliminate cyclooxygenase 2 inhibitory activity, while potentially maintaining antineoplastic properties.

METHODS

2,5-dimethyl celecoxib was synthesized in the Department of Chemistry at the University of Southern California. With the use of non-small cell lung cancer cells (A549), prostaglandin E2 production was quantified by enzyme-linked immunosorbent assay to assess cyclooxygenase 2 activity. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt assay. Cell migration was performed using transwell inserts that were matrigel coated for invasion experiments. Gelatin zymography was used to assess matrix-metalloproteinase activity.

RESULTS

2,5-dimethyl celecoxib did not inhibit interleukin-1beta-stimulated prostaglandin E2 production, whereas celecoxib did even at low doses. Both celecoxib and 2,5-dimethyl celecoxib decreased tumor cell viability and proliferation with IC50 for celecoxib and 2,5-dimethyl celecoxib of 73 and 53 micromol/L, respectively. Both drugs were also potent inducers of apoptosis, and both inhibited tumor cell migration and invasion. This was associated with down-regulation of matrix metalloproteinase activity.

CONCLUSIONS

2,5-dimethyl celecoxib is a structural analog of celecoxib that lacks cyclooxygenase 2 inhibitory activity but exhibits significant antineoplastic properties comparable to celecoxib. This suggests that the antineoplastic activities of celecoxib are, at least in part, cyclooxygenase independent and that therapeutic strategies can be developed without the side effects of global cyclooxygenase 2 blockade.

Non-COX-2 targets and cancer: Expanding the molecular target repertoire of chemoprevention

Chemoprevention represents a highly promising approach for the control of cancer. That nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and other cancers has led to novel approaches to cancer prevention. The known inhibitory effect of NSAIDs on the eicosanoid pathway prompted mechanistic and drug development work focusing on cyclooxygenase (COX), culminating in clinical trials of cyclooxygenase 2 (COX-2) inhibitors for cancer prevention or treatment. However, two COX-2 inhibitors have been withdrawn due to side effects. Here we review several pathways of the eicosanoid cascade that are relevant to cancer; summarize the evidence regarding the role of COX-2 as a target for cancer prevention; and discuss several of the molecular targets that may mediate the chemopreventive effect of NSAIDs. The clinically modest results obtained to date with COX-2 specific inhibitors used in cancer prevention; the multiple COX-2-independent targets of both NSAIDs and COX-2 inhibitors; and the limitations of some COX-2 inhibitors indicate that exploiting these (non-COX-2) molecular targets will likely yield effective new approaches for cancer chemoprevention.

Effects of celecoxib on cell proliferation and ERK2 expression of ERK2 in gastric cancer cells

AIM: To explore the role of celecoxib, a selective COX-2 inhibitor, in the proliferation of human gastric carcinoma cells SGC7901, and to investigate the relationship between cell proliferation and the expression of extracellular signal-regulated kinase 2 (ERK2).

METHODS: The cell proliferation of SGC7901 cells was measured by MTT assay, and the apoptoticsis rate of the cells was examined by TUNEL staining method and flow cytometry. The expression of phosphated ERK2 was detected by immunohistochemistry and quantified measured by image analysis systems.

RESULTS: Celecoxib inhibited the proliferation of SGC7901 gastric carcinoma cells and the expression of phosphated ERK2, as well as induced the apoptosis of the SGC-7901 cells in a dose-dependent manner. The growth inhibitory rates of SGC-7901 cells treated with 10, 20, 40, 80 and, 160 μmol/L celecoxib for 48 h were 9.8%, 30%, 58.9%, 76.3%, and 88.3%, respectively. The SGC7901 cells presented typical morphological features of apoptosis by TUNEL staining. By flow cytometry, the apoptosistic rates of SGC-7901 cells (4.23 ± 0.81%, 15.50 ± 2.10%, 24.35 ± 2.32%, 31.52±3.64%, and 45.82±5.92% for 10, 20, 40, 80 and 160 μmol/L celecoxib, respectively) were significantly higher than those inof the control group(1.85 ±0.31%, P < 0.01). The optical density value of ERK2 of SGC7901 cells (10, 20, 40, 80 and 160 μmol/L celecoxib: 2.96 ± 0.24, P >0.05; 2.56 ± 0.24, P<0.05; 2.04 ± 0.20, P < 0.01; 1.68 ± 0.16, P < 0.01; 1.52 ± 0.09, P < 0.01) were significantly lower than that ofin the control group (3.32 ± 0.28).

CONCLUSION: Celecoxib can inhibit the growth and induce the apoptosis of SGC7901 cells, and its mechanism may and induce the cell apoptosis. This effect may relate to the inhibition of ERK2 kinase signaling pathway.

COX-2 inhibitors suppress integrin alpha5 expression in human lung carcinoma cells through activation of Erk: involvement of Sp1 and AP-1 sites

Tumor cell expression of COX-2 has been implicated in the progression of murine and human lung cancer. Inhibition of COX-2 by nonsteroidal antiinflammatory drugs reduces the risk of cancer development in humans and suppresses tumor growth in animal models. However, the underlying mechanisms for this beneficial effect are not fully understood. Here we explore the potential link between the anticancer effects of COX-2 inhibitors and the expression of the integrin alpha5beta1. Expression of this integrin in carcinoma cells is associated with invasiveness and malignant progression. This, together with our studies showing that fibronectin, the ligand of alpha5beta1, stimulates the growth of human lung carcinoma cells, and that this effect is mediated through alpha5beta1-dependent signals, has prompted us to examine the effects of COX-2 inhibitors on alpha5beta1 expression in human non small cell lung carcinoma (NSCLC) cells. We found that the selective COX-2 inhibitors NS398 and Nimesulide decreased mRNA expression and protein production of the integrin alpha5 subunit. This effect was associated with inhibition of NSCLC cell adhesion to fibronectin. The COX-2 inhibitors triggered the phosphorylation of extracellular signal-regulated kinase (Erk) in a time-dependent manner, and the inhibitor of Mek-1/Erk PD98095 prevented their inhibitory effects on integrin alpha5 expression. Transient transfection assays showed that the COX-2 inhibitors affected integrin alpha5 gene transcription by acting between -92 to -41 bp of the human integrin alpha5 gene promoter. Gel mobility shift assays showed that the COX-2 inhibitors increased Sp1 DNA binding, but decreased that of AP-1. These effects were accompanied by an increase in Sp1 protein and a decrease in c-Jun protein expression, as well as inhibition of SAPK/JNK phosphorylation. The Sp1 inhibitor, Mithramycin A, also blocked the inhibitory effect of the COX-2 inhibitors on alpha5 expression and promoter activity. Overall, these findings suggest that COX-2 inhibitors suppress alpha5beta1 integrin expression in NSCLC through effects on integrin alpha5 gene transcription mediated by Erk activation, increased Sp1, decreased AP-1 DNA binding and inactivation of SAPK/JNK signals. Our observations unveil a new mechanism of action against NSCLC for COX-2 inhibitors that relates to regulation of integrin alpha5 gene expression and, consequently, recognition of extracellular matrices (i.e., fibronectin) by tumor cells. (c) 2005 Wiley-Liss, Inc.

Indomethacin-induced activation of the death receptor-mediated apoptosis pathway circumvents acquired doxorubicin resistance in SCLC cells

Small-cell lung cancers (SCLCs) initially respond to chemotherapy but are often resistant at recurrence. A potentially new method to overcome resistance is to combine classical chemotherapeutic drugs with apoptosis induction via tumour necrosis factor (TNF) death receptor family members such as Fas. The doxorubicin-resistant human SCLC cell line GLC₄-Adr and its parental doxorubicin-sensitive line GLC₄ were used to analyse the potential of the Fas-mediated apoptotic pathway and the mitochondrial apoptotic pathway to modulate doxorubicin resistance in SCLC. Western blotting showed that all proteins necessary for death-inducing signalling complex formation and several inhibitors of apoptosis were expressed in both lines. The proapototic proteins Bid and caspase-8, however, were higher expressed in GLC₄-Adr. In addition, GLC₄-Adr expressed more Fas (3.1x) at the cell membrane. Both lines were resistant to anti-Fas antibody, but plus the protein synthesis inhibitor cycloheximide anti-Fas antibody induced 40% apoptosis in GLC₄-Adr. Indomethacin, which targets the mitochondrial apoptotic pathway, induced apoptosis in GLC₄-Adr but not in GLC₄ cells. Surprisingly, in GLC₄-Adr indomethacin induced caspase-8 and caspase-9 activation as well as Bid cleavage, while both caspase-8 and caspase-9 specific inhibitors blocked indomethacin-induced apoptosis. In GLC₄-Adr, doxorubicin plus indomethacin resulted in elevated caspase activity and a 2.7-fold enhanced sensitivity to doxorubicin. In contrast, no effect of indomethacin on doxorubicin sensitivity was observed in GLC₄. Our findings show that indomethacin increases the cytotoxic activity of doxorubicin in a doxorubicin-resistant SCLC cell line partly via the death receptor apoptosis pathway, independent of Fas.

Cytokines differentially regulate the synthesis of prostanoid and nitric oxide mediators in tumorigenic versus non-tumorigenic mouse lung epithelial cell lines

Studies using transgenic and knockout mice have demonstrated that particular cytokines influence lung tumor growth and identified prostaglandin E2 (PGE2), prostacyclin (PGI2) and nitric oxide (NO) as critical mediators of this process. PGE2 and NO were pro-tumorigenic while PGI2 was antitumorigenic. We describe herein an in vitro experimental approach to examine interactions among cytokines, prostaglandins (PGs) and NO. PGE2, PGI2, and NO levels were assayed in culture media from non-tumorigenic mouse lung epithelial cell lines, their spontaneous transformants and mouse lung tumor-derived cell lines, before or after exposure to the cytokines TNFalpha, IFNgamma and IL1beta, alone and in combination. More PGE2 than PGI2 was produced by neoplastic cells, while the opposite was observed in non-tumorigenic lines. Cytokine exposure magnified the extent of these differential concentrations. The PGE2 to PGI2 ratio was also greater in chemically-induced mouse lung tumors than in adjacent tissue or control lungs, supporting the physiological relevance of this in vitro model. Expression of PG biosynthetic enzymes in these cell lines correlated with production of the corresponding PGs. Cytokine treatment enhanced NO production by inducing the inflammation-associated biosynthetic enzyme, inducible NO synthase (iNOS), but this did not correlate with the neoplastic status of cells. Inhibition of iNOS or cyclooxygenase 2 activity using aminoguanidine or NS-398 respectively, demonstrated that NO did not affect PG production nor did PGs influence NO production. Since lack of iNOS inhibits mouse lung tumor formation, we propose that this is independent of any modulation of PG synthesis in epithelial cells. The similar normal/neoplastic trends in PGE2 to PGI2 ratios both in vitro and in vivo, together with an amplification of this difference upon cytokine exposure, are consistent with the hypothesis that cytokines released during inflammation exacerbate differences in the behavior of neoplastic and normal lung cells.

Novel targeted agents in the treatment of lung cancer

Lung cancer is the leading cause of cancer-related mortality in the US. Although an improvement in outcome is possible with the continued advancement of cytotoxic-based treatment, clinical research is currently focused on utilising novel molecular targets with proven efficacy in preclinical models and a low toxicity profile. This is the result of advances in understanding of tumour biology and molecular pathways that have been implicated in cancer pathogenesis and progression. Novel agents targeting cell cycle regulation, angiogenesis and signal transduction pathways have reached clinical testing in lung cancer and are discussed in this review.

Sulindac enhances adenoviral vector expressing mda-7/IL-24–mediated apoptosis in human lung cancer

Several studies have shown antitumor activities of the melanoma differentiation–associated gene 7 (mda-7) and the nonsteroidal anti-inflammatory drug sulindac when used as a monotherapies against a wide variety of human cancers. However, the combined effects of mda-7 and sulindac have not previously been tested. Therefore, we tested the antitumor activity of an adenoviral vector expressing mda-7 (Ad-mda7) in combination with sulindac against non–small cell lung cancer cells in vitro and in vivo. When treated with Ad-mda7 in combination with sulindac, human lung cancer cells (A549 and H1299) underwent growth suppression resulting in apoptosis. The growth inhibition induced by Ad-mda7 in combination with sulindac was significantly greater than that observed with Ad-mda7 or sulindac alone. Furthermore, the degree of growth inhibition induced using this combination was dose-dependent for sulindac. Treatment with Ad-mda7 in combination with sulindac had no growth inhibitory effects on human normal lung (CCD-16) fibroblasts. We then investigated the mechanism by which sulindac enhances Ad-mda7-mediated apoptosis. Sulindac increased expression of ectopic MDA-7 protein in tumor cells, thereby increasing the expression of downstream effectors RNA-dependent protein kinase, p38MAPK, caspase-9, and caspase-3 and enhancing apoptosis of non–small cell lung cancer cells. Pulse-chase experiments showed that the increased expression of MDA-7 protein in sulindac-treated cells was due to increased half-life of the MDA-7 protein. Finally, treatment of human lung tumor xenografts in nude mice with Ad-mda7 plus sulindac significantly suppressed growth (P = 0.001) compared with Ad-mda7 or sulindac alone. Our results show for the first time that combined treatment with Ad-mda7 plus sulindac enhances growth inhibition and apoptosis of human lung cancer cells. The increased antitumor activity observed with the combination treatment is a result of increased half-life of MDA-7 protein. Regulation of protein turnover is a heretofore-unrecognized mechanism of this nonsteroidal anti-inflammatory drug.

Multifaceted roles of cyclooxygenase-2 in lung cancer

Lung cancer is the leading cause of cancer death in the United States. Although the low 5-year survival rate (under 15%) has changed minimally in the last 25 years, new agents and combinations of agents that target tumor proliferation, invasion, and survival may lead to improvement in patient outcomes. There is evidence that cyclooxygenase-2 (COX-2) is overexpressed in lung cancer and promotes tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. COX-2 inhibitors have been found to inhibit tumor growth in animal models and have demonstrated responses when combined with conventional therapy in phase II clinical trials. Further understanding of the mechanisms involved in COX-2-mediated tumorigenesis and its interaction with other molecules in lung cancer may lead to improved therapeutic strategies for this disease. In addition, delineation of how COX-2-dependent genes modulate the malignant phenotype will provide novel insights in lung cancer pathogenesis.

Non-steroidal anti-inflammatory drugs inhibit cellular proliferation and upregulate cyclooxygenase-2 protein expression in endometrial cancer cells

We determined the effects of several non-steroidal anti-inflammatory drugs (NSAIDs), aspirin (acetylsalicylic acid, ASA), indomethacin and a cyclooxygenase-2 (COX-2)-selective inhibitor (NS398), on cellular proliferation and regulation of COX-2 protein expression in endometrial cancer cells in vitro, and investigated their modes of action. All three NSAIDs markedly inhibited the proliferation of Ishikawa, HEC-1A and AN3CA endometrial cancer cell lines in a time- and concentration-dependent manner. ASA and indomethacin triggered apoptosis in cells of all three lines through release of cytosolic cytochrome c, activation of caspase-9 and-3, and cleavage of poly(ADP-ribose) polymerase (PARP), but NS398 induced minimal apoptosis only in Ishikawa cells. ASA altered the cell cycle distribution, with G2/M phase accumulation of cells, and induced overexpression of Ki-67 protein. Both ASA and indomethacin reduced the protein levels of Bcl-2 and Bcl-xl, but upregulated those of Bax and Bcl-xs. COX-2 protein expression and PGE(2) production were upregulated by ASA and indomethacin in all three cell lines. However, NS398 did not alter COX-2 protein expression or PGE(2) production in these cells. These results indicate that NSAIDs inhibit proliferation of endometrial cancer cells independently of the reduction of COX-2 protein expression. A cytochrome c-dependent apoptotic pathway and/or cell cycle arrest may contribute to the inhibitory effects of these NSAIDs.

Study of prostaglandin receptors in mitochondria on apoptosis of human lung carcinoma cell line A549

PGs (prostaglandins) are synthesized through the cyclo-oxygenase (COX-1 and -2) pathway in a variety of cells in response to various physiological stimuli. All cells require at least one pathway for apoptosis, and mitochondrial play a central role in regulation of apoptosis. In a previous study, incubation of A549 cells with NS-398 (a COX-2-specific inhibitor) induced apoptosis and inhibited cell proliferation, and the concentrations of different PGs between various cellular compartments were found to be changed. To determine whether PG receptors are involved in this regulation, Western-blot analyses were performed specific for PGE2 (EP receptors) and PGF2α (FP receptor) receptors, which were expressed in A549 cells. Western-blot analysis revealed that mitochondria that were isolated from A549 cells expressed EP receptors (EP2, EP3 and EP4), whereas FP receptors were undetectable. EP receptors (EP1, EP3 and EP4) and FP receptors were detected from A549 cell membrane. These results suggest that the change of PG production in A549-cells-induced cancer cell apoptosis might be related to the different expressions of EP and FP receptors in cell and mitochondrial membrane.

Development of nonsteroidal anti-inflammatory drug analogs and steroid carboxylates selective for human aldo-keto reductase isoforms: potential antineoplastic agents that work independently of cyclooxygenase isozymes

Human aldo-keto reductases (AKRs) regulate nuclear receptors by controlling ligand availability. Enzymes implicated in regulating ligand occupancy and trans-activation of the nuclear receptors belong to the AKR1C family (AKR1C1-AKR1C3). Nuclear receptors regulated by AKR1C members include the steroid hormone receptors (androgen, estrogen, and progesterone receptors) and the orphan peroxisome proliferator-activated receptor (PPARgamma). In human myeloid leukemia (HL-60) cells, ligand access to PPARgamma is regulated by AKR1C3, which diverts PGD(2) metabolism away from J-series prostanoids (Desmond et al., 2003). Inhibition of AKR1C3 by indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), caused PPARgamma-mediated terminal differentiation of the HL-60 cells. To discriminate between antineoplastic effects of NSAIDs that are mediated by either AKR1C or cyclooxygenase (COX) isozymes, selective inhibitors are required. We report a structural series of N-phenylanthranilic acid derivatives and steroid carboxylates that selectively inhibit recombinant AKR1C isoforms but do not inhibit recombinant COX-1 or COX-2. The inhibition constants, IC(50), K(I) values, and inhibition patterns were determined for the NSAID analogs and steroid carboxylates against AKR1C and COX isozymes. Lead compounds, 4-chloro-N-phenylanthranilic acid and 4-benzoyl-benzoic acid for the N-phenylanthranilic acid analogs and most steroid carboxylates, exhibited IC(50) values that had greater than 500-fold selectivity for AKR1C isozymes compared with COX-1 and COX-2. Crystallographic and molecular modeling studies showed that the carboxylic acid of the inhibitor ligand was tethered by the catalytic Tyr55-OH(2)(+) and explained why A-ring substituted N-phenylanthranilates inhibited only AKR1C enzymes. These compounds can be used to dissect the role of the AKR1C isozymes in neoplastic diseases and may have cancer chemopreventive roles independent of COX inhibition.

The role of targeted therapy in non-small cell lung cancer

The therapy of non-small cell lung cancer (NSCLC) has reached a plateau in improving patient survival, with overall disappointing results. Thus, clinical research for new treatment strategies is warranted. Advances in the singling out molecular targets for NSCLC treatment has granted the development of several new biological agents. In the present paper we describe the main clinical data currently available on targeted agents in the treatment of NSCLC, focusing on epidermal growth factor receptor family inhibitors, angiogenesis inhibitors, signal transduction inhibitors, eicosanoid pathway inhibitors, vaccines and gene therapy. Several targeted agents have been introduced into clinical trials in NSCLC, mainly in advanced disease, with the first phase III study results being recently made available. To date, few of these new agents can offer hope of a substantial impact on the natural history of NSCLC, and negative results are more commonly reported than positive ones. Nevertheless, clinically-meaningful advances have already been achieved in chemotherapy refractory advanced NSCLC patients, with gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, representing a further chance of tumor control and symptom palliation. Moreover, important lessons can be learned from this first generation of clinical trials.