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

A Cross-Talk about Radioresistance in Lung Cancer-How to Improve Radiosensitivity According to Chinese Medicine and Medicaments That Commonly Occur in Pharmacies

Lung cancer is one of the most common cancers in the population and is characterized by non-specific symptoms that delay the diagnosis and reduce the effectiveness of oncological treatment. Due to the difficult placement of the tumor, one of the main methods of lung cancer treatment is radiotherapy, which damages the DNA of cancer cells, inducing their apoptosis. However, resistance to ionizing radiation may develop during radiotherapy cycles, leading to an increase in the number of DNA points of control that protect cells from apoptosis. Cancer stem cells are essential for radioresistance, and due to their ability to undergo epithelial-mesenchymal transition, they modify the phenotype, bypassing the genotoxic effect of radiotherapy. It is therefore necessary to search for new methods that could improve the cytotoxic effect of cells through new mechanisms of action. Chinese medicine, with several thousand years of tradition, offers a wide range of possibilities in the search for compounds that could be used in conventional medicine. This review introduces the potential candidates that may present a radiosensitizing effect on lung cancer cells, breaking their radioresistance. Additionally, it includes candidates taken from conventional medicine-drugs commonly available in pharmacies, which may also be significant candidates.

LINC00461 Promoted Endometrial Carcinoma Growth and Migration by Targeting MicroRNA-219-5p/Cyclooxygenase-2 Signaling Axis

Endometrial carcinoma (EC) ranks as the most common female genital cancer in developed countries. Lately, more and more long noncoding RNAs (lncRNAs) have been identified as vital regulators in numerous physiological and pathological processes, including EC. However, the expression pattern and precise functions of different lncRNAs in EC remain unclear. In this study, we reported LINC00461 was upregulated in EC patient tissues and cell lines. In addition, LINC00461 knockdown could remarkably suppress cell proliferation, cell cycle progression, cell migration, and promote cell apoptosis in EC cells. We discovered LINC00461 could sponge microRNA-219-5p (miR-219-5p) and suppress its expression, thereby upregulating expression level of miR-219-5p’s target, cyclooxygenase-2 (COX-2). In vivo animal models, LINC00461 knockdown inhibited tumor growth by increasing miR-219-5p level and reducing COX-2 expression, thus confirming LINC00461 functions as an oncogene in EC. In this study, a novel regulatory role of LINC00461/miR-219-5p/COX-2 axis was systematically investigated in context of EC, with the aim to provide promising intervention targets for EC therapy from bench to clinic.

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.

Cyclooxygenase inhibitors combined with deuterium-enriched water augment cytotoxicity in A549 lung cancer cell line via activation of apoptosis and MAPK pathways

Objectives

Combination chemotherapy is a rational strategy to increase patient response and tolerability and to decrease adverse effects and drug resistance. Recently, the use of non-steroidal anti-inflammatory drugs (NSAIDs) has been reported to be associated with reduction in occurrence of a variety of cancers including lung cancer. On the other hand, growing evidences suggest that deuterium-enriched water (DEW, D2O) and deuterium-depleted water (DDW) play a role both in treatment and prevention of cancers. In the present study, we examined the effects of DEW and DDW in combination with two NSAIDs, celecoxib and indomethacin, on A549 human non-small lung cancer cell to identify novel treatment options.

Materials and Methods

The cytotoxicity of celecoxib or indomethacin, alone and in combination with DDW and DEW was determined. The COX-2, MAPK pathway proteins, the anti-apoptotic Bcl2 and pro-apoptotic Bax proteins and caspase-3 activity were studied for cytotoxic combinations.

Results

Co-administration of selective and non-selective COX-2 inhibitors with DEW led to a remarkable increase in cytotoxicity and apoptosis of A549 cells. These events were associated with activation of p38 and JNK MAPKs and decreasing pro-survival proteins Bcl-2, COX-2 and ERK1/2. Furthermore, the combination therapy activated caspase-3, and the apoptosis mediator, and disabled poly ADP-ribose polymerase (PARP), the key DNA repair enzyme, by cleaving it.

Conclusion

The combination of DEW with NSAIDs might be effective against lung cancer cells by influence on principal cell signalling pathways, and this has a potential to become a candidate for chemotherapy.

Pharmacological modulation of the AKT/microRNA-199a-5p/CAV1 pathway ameliorates cystic fibrosis lung hyper-inflammation

In cystic fibrosis (CF) patients, hyper-inflammation is a key factor in lung destruction and disease morbidity. We have previously demonstrated that macrophages drive the lung hyper-inflammatory response to LPS in CF mice, because of reduced levels of the scaffold protein CAV1 with subsequent uncontrolled TLR4 signalling. Here we show that reduced CAV1 and, consequently, increased TLR4 signalling, in human and murine CF macrophages and murine CF lungs, is caused by high microRNA-199a-5p levels, which are PI3K/AKT-dependent. Downregulation of microRNA-199a-5p or increased AKT signalling restores CAV1 expression and reduces hyper-inflammation in CF macrophages. Importantly, the FDA-approved drug celecoxib re-establishes the AKT/miR-199a-5p/CAV1 axis in CF macrophages, and ameliorates lung hyper-inflammation in Cftr-deficient mice. Thus, we identify the AKT/miR-199a-5p/CAV1 pathway as a regulator of innate immunity, which is dysfunctional in CF macrophages contributing to lung hyper-inflammation. In addition, we found that this pathway can be targeted by celecoxib.

Anti-tumor activity of non-steroidal anti-inflammatory drugs: cyclooxygenase-independent targets

Non-steroidal anti-inflammatory drugs (NSAIDs) are used extensively for analgesic and antipyretic treatments. In addition, NSAIDs reduce the risk and mortality to several cancers. Their mechanisms in anti-tumorigenesis are not fully understood, but both cyclooxygenase (COX)-dependent and -independent pathways play a role. We and others have been interested in elucidating molecular targets of NSAID-induced apoptosis. In this review, we summarize updated literature regarding cellular and molecular targets modulated by NSAIDs. Among those NSAIDs, sulindac sulfide and tolfenamic acid are emphasized in this review because these two drugs have been well investigated for their anti-tumorigenic activity in many different types of cancer.

Mycoplasma fermentans MALP-2 induces heme oxygenase-1 expression via mitogen-activated protein kinases and Nrf2 pathways to modulate cyclooxygenase 2 expression in human monocytes

Heme oxygenase-1 (HO-1) is a stress-inducible rate-limiting enzyme in heme degradation that confers cytoprotection against oxidative injury and performs a vital function in the maintenance of cell hemostasis. Increasing numbers of reports have indicated that mycoplasma-derived membrane lipoproteins/lipopeptides, such as macrophage-activating lipopeptide-2 (MALP-2), function as agents that stimulate the immune system by producing various inflammatory mediators, such as cytokines and cyclooxygenase 2 (COX-2), which play roles in the pathogenesis of inflammatory responses during mycoplasma infection. Here, we report that MALP-2 induced HO-1 mRNA and protein expression and upregulated HO-1 enzyme activity in THP-1 cells. Specific inhibitors of mitogen-activated protein kinases (MAPKs), SB203580, PD98059, and SP600125, significantly abolished HO-1 expression. In addition, MALP-2 also induced NF-E2-related factor 2 (Nrf2) translocation, and the silencing of Nrf2 expression in THP-1 cells decreased the levels of MALP-2-mediated HO-1 expression. Furthermore, COX-2 protein expression levels were upregulated in THP-1 cells in response to MALP-2, and transfection with small interfering RNAs of HO-1 significantly increased COX-2 accumulation. These results demonstrate that MALP-2 induces HO-1 expression via MAPKs and Nrf2 pathways and, furthermore, that MALP-2-induced COX-2 expression was modulated by HO-1 in THP-1 cells.

Breast ductal lavage for biomarker assessment in high risk women: rationale, design and methodology of a randomized phase II clinical trial with nimesulide, simvastatin and placebo

Background

Despite positive results from large phase III clinical trials proved that it is possible to prevent estrogen-responsive breast cancers with selective estrogen receptor modulators and aromatase inhibitors, no significant results have been reached so far to prevent hormone non-responsive tumors. The Ductal Lavage (DL) procedure offers a minimally invasive method to obtain breast epithelial cells from the ductal system for cytopathologic analysis. Several studies with long-term follow-up have shown that women with atypical hyperplasia have an elevated risk of developing breast cancer. The objective of the proposed trial is to assess the efficacy and safety of a daily administration of nimesulide or simvastatin in women at higher risk for breast cancer, focused particularly on hormone non-responsive tumor risk. The primary endpoint is the change in prevalence of atypical cells and cell proliferation (measured by Ki67) in DL or fine needle aspirate samples, after 12 months of treatment and 12 months after treatment cessation.

Methods-Design

From 2005 to 2011, 150 women with a history of estrogen receptor negative ductal intraepithelial neoplasia or lobular intraepithelial neoplasia or atypical hyperplasia, or unaffected subjects carrying a mutation of BRCA1 or with a probability of mutation >10% (according to BRCAPRO) were randomized to receive nimesulide 100mg/day versus simvastatin 20mg/day versus placebo for one year followed by a second year of follow-up.

Discussion

This is the first randomized placebo controlled trial to evaluate the role of DL to study surrogate endpoints biomarkers and the effects of these drugs on breast carcinogenesis. In 2007 the European Medicines Agency limited the use of systemic formulations of nimesulide to 15 days. According to the European Institute of Oncology Ethics Committee communication, we are now performing an even more careful monitoring of the study participants. Preliminary results showed that DL is a feasible procedure, the treatment is well tolerated and the safety blood tests do not show any significant liver toxicity. There is an urgent need to confirm in the clinical setting the potential efficacy of other compounds in contrasting hormone non-responsive breast cancer. This paper is focused on the methodology and operational aspects of the clinical trial.

Trial Registration

(ClinicalTrials.gov Identifier: NCT01500577)

From COX-2 inhibitor nimesulide to potent anti-cancer agent: synthesis, in vitro, in vivo and pharmacokinetic evaluation

Cyclooxygenase-2 (COX-2) inhibitor nimesulide inhibits the proliferation of various types of cancer cells mainly via COX-2 independent mechanisms, which makes it a good lead compound for anti-cancer drug development. In the presented study, a series of new nimesulide analogs were synthesized based on the structure-function analysis generated previously. Some of them displayed very potent anti-cancer activity with IC(50)s around 100 nM-200 nM to inhibit SKBR-3 breast cancer cell growth. CSUOH0901 (NSC751382) from the compound library also inhibits the growth of the 60 cancer cell lines used at National Cancer Institute Developmental therapeutics Program (NCIDTP) with IC(50)s around 100 nM-500 nM. Intraperitoneal injection with a dosage of 5  mg/kg/d of CSUOH0901 to nude mice suppresses HT29 colorectal xenograft growth. Pharmacokinetic studies demonstrate the good bioavailability of the compound.

Dietary administration of berberine or Phellodendron amurense extract inhibits cell cycle progression and lung tumorigenesis

Phellodendron amurense extract is a Chinese herbal remedy that has recently been studied for its antitumor, antimicrobial and other biological activities. It is previously unknown if these agents are bioavailable and effective against tumors when delivered as a dietary component. It is also unknown if the anti-tumorigenic properties of berberine, an isoquinoline alkaloid component of P. amurense, is equally effective when administered alone. There are contrasting reports on the cellular processes involved in anti-tumorigenesis by P. amurense and berberine. Here we find that berberine, when administered orally through the diet, inhibits in vivo tumorigenesis of both p53 expressing and p53 null lung tumor xenografts equally whether administered in its pure form or as a part of P. amurense extract. We also show that berberine induces G1 cell cycle arrest, inhibits proliferative kinase signaling and arrests the growth of lung tumor cells in culture. Berberine administered in the diet was detectable by HPLC in the lungs of mice fed P. amurense or equivalent doses of berberine at concentrations of 455 and 518 ng/ml respectively and inhibited the growth of xenografted A549 cell tumors, which grew to 9.4 and 6.4 mm³ respectively, compared to 58.9 mm³ in control mice (P < 0.001). Phosphorylation of Akt, CREB and MAPK was inhibited in A549 cells by P. amurense. Demonstration of oral bioavailability and anti-tumorigenic efficacy of dietary berberine, as well as further demonstration of signaling pathway modulation and cell-cycle arrest, implicate this relatively safe, natural compound as a potentially important therapeutic and chemopreventive agent for lung cancer.

Induction of heme oxygenase-1 attenuates lipopolysaccharide-induced cyclooxygenase-2 expression in mouse brain endothelial cells

Background

Prostaglandin E₂ (PGE₂), an arachidonic acid metabolite converted by cyclooxygenase-2 (COX-2), plays important roles in the regulation of endothelial functions in response to bacterial infection. The enzymatic activity of COX-2 can be down-regulated by heme oxygenase-1 (HO-1) induction. However, the mechanisms underlying HO-1 modulating COX-2 protein expression are not known.

Objective

The aim of the present study was to investigate whether the up-regulation of HO-1 regulates COX-2 expression induced by lipopolysaccharide (LPS), an endotoxin produced by Gram negative bacteria, in mouse brain endothelial cells (bEnd.3)

Methods

Cultured bEnd.3 cells were used to investigate LPS-induced COX-2 expression and PGE₂ production. Cobalt protoporphyrin IX (CoPP, an HO-1 inducer), infection with a recombinant adenovirus carried with HO-1 gene (Adv-HO-1), or zinc protoporphyrin (ZnPP, an HO-1 inhibitor) was used to stimulate HO-1 induction or inhibit HO-1 activity. The expressions of COX-2 and HO-1 were evaluated by western blotting. PGE₂ levels were detected by an enzyme-linked immunoassay. Hemoglobin (a chelator of carbon monoxide, CO, one of metabolites of HO-1) and CO-RM2 (a CO releasing molecule) were used to investigate the mechanisms of HO-1 regulating COX-2 expression.

Results

We found that LPS-induced COX-2 expression and PGE₂ production were mediated through NF-κB (p65) via activation of Toll-like receptor 4 (TLR4). LPS-induced COX-2 expression was inhibited by HO-1 induction by pretreatment with CoPP or infection with Adv-HO-1. This inhibitory effect of HO-1 was reversed by pretreatment with either ZnPP or hemoglobin. Pretreatment with CO-RM2 also inhibited TLR4/MyD88 complex formation, NF-κB (p65) activation, COX-2 expression, and PGE₂ production induced by LPS.

Conclusions

We show here a novel inhibition of HO-1 on LPS-induced COX-2/PGE₂ production in bEnd.3. Our results reinforce the emerging role of cerebral endothelium-derived HO-1 as a protector against cerebral vascular inflammation triggered by bacterial infection.

A new cyclooxygenase-2 inhibitor, (1E,4E)-1,5-bis(2-bromophenyl)penta-1,4-dien-3-one (GL63) suppresses cyclooxygenase-2 gene expression in human lung epithelial cancer cells: coupled mRNA stabilization and posttranscriptional inhibition

Lung cancer is a leading cause of morbidity and mortality worldwide. Cyclooxygenase-2 (COX-2) expression is upregulated in lung carcinomas and is considered an attractive therapeutic target. In this study, the effect of curcumin and curcumin analogues on COX-2 expression induced by phorbol 12-myristate 13-acetate (PMA) were investigated. We found that a novel curcumin analogue (GL63) inhibited PMA-induced COX-2 mRNA and protein levels in H460 cells to a greater degree than curcumin. To understand the molecular mechanisms governing COX-2 regulation, the effect on COX-2 mRNA degradation was examined; we found that GL63 significantly decreased COX-2 mRNA stability by reducing cytoplasmic localization and protein abundance of human antigen R (HuR). The 3'-untranslated region (3'-UTR) report gene assay also showed GL63 substantially reduced the 3'-UTR green fluorescent protein values, indicating that the destabilizing effect on COX-2 mRNA may be couple with the posttranscriptional inhibition of COX-2. Taken together, our results provide evidence that the novel curcumin analogue can effectively inhibit PMA-induced COX-2 expression in H460 cells, a mechanism associated with COX-2 mRNA stability and post-transcriptional regulation.

Redox Factor-1 Inhibits Cyclooxygenase-2 Expression via Inhibiting of p38 MAPK in the A549 Cells

In this study, we evaluated the role of apurinic/apyrimidinic endonuclease1/redox factor-1 (Ref-1) on the tumor necrosis factor-alpha (TNF-alpha) induced cyclooxygenase-2 (COX-2) expression using A549 lung adenocarcinoma cells. TNF-alpha induced the expression of COX-2 in A549 cells, but did not induce BEAS-2B expression. The expression of COX-2 in A549 cells was TNF-alpha dose-dependent (5~100 ng/ml). TNF-alpha-stimulated A549 cells evidenced increased Ref-1 expression in a dose-dependent manner. The adenoviral transfection of cells with AdRef-1 inhibited TNF-alpha-induced COX-2 expression relative to that seen in the control cells (Adbetagal). Pretreatment with 10 microM of SB203580 suppressed TNF-alpha-induced COX-2 expression, thereby suggesting that p38 MAPK might be involved in COX-2 expression in A549 cells. The phosphorylation of p38 MAPK was increased significantly after 5 minutes of treatment with TNF-alpha, reaching a maximum level at 10 min which persisted for up to 60 min. However, p38MAPK phosphorylation was markedly suppressed in the Ref-1-overexpressed A549 cells. Taken together, our results appear to indicate that Ref-1 negatively regulates COX-2 expression in response to cytokine stimulation via the inhibition of p38 MAPK phosphorylation. In the lung cancer cell lines, Ref-1 may be involved as an important negative regulator of inflammatory gene expression.

Genetic disruption of cyclooxygenase-2 does not improve histological or behavioral outcome after traumatic brain injury in mice

Increasing evidence suggests a role for cyclooxygenase-2 (COX-2) in traumatic brain injury (TBI). In the present study, the role of COX-2 in TBI was investigated using COX-2 gene-disrupted (COX-2 null) mice and wild-type (WT) controls that were subjected to the controlled cortical impact (CCI) model of TBI. There was increased expression of COX-2 in ipsilateral hippocampus in WT mice subjected to CCI. CCI resulted in a significant increase in prostaglandin E(2) concentrations in WT compared with COX-2 null hippocampi. There was a significant increase in TUNEL staining of CA1 neurons 24 hr after CCI in WT, but not in COX-2 null mice, compared with sham-operated controls, which is consistent with a protective role for COX-2 in the early phase of injury after TBI. However, there was no difference in lesion volume 21 days after CCI in COX-2 null and WT mice. COX-2 gene disruption did not alter Morris water maze performance. Taken together, these results suggest only a minor role for COX-2 activity in determining outcome after TBI in mouse.

Expression of the calcium-binding protein S100P is regulated by bone morphogenetic protein in pancreatic duct epithelial cell lines

We previously reported that bone morphogenetic protein (BMP)-4 induces epithelial-mesenchymal transition in a pancreatic cancer cell line. To further investigate the detailed molecular mechanism of BMP action in pancreatic cancer, we carried out comprehensive microarray analysis in Panc-1 cells. The microarray analysis elucidated novel BMP target genes, and among them, the calcium-binding protein S100P was identified as an upregulated gene. S100P induction by BMP4 was confirmed by real-time reverse transcription-polymerase chain reaction and western blot analysis in Panc-1 and HPDE cells. Short interfering RNA-based knockdown of S100P expression sufficiently repressed BMP4-induced cell migration in Panc-1 cells. Because Panc-1 and HPDE cells express wild-type Smad4, we hypothesized that Smad4 might be indispensable for S100P induction by BMP4. S100P induction by BMP4 was not observed in the Smad4-null cell line BxPC3, and was sufficiently attenuated in short interfering RNA-based Smad4-knockdown Panc-1 cells. Interestingly, detailed promoter analysis revealed that upregulation of S100P by BMP4 was independent of the Smad-binding element, indicating that an additional unknown downstream factor of the Smad4-dependent pathway is necessary for this induction. These findings are the first of their kind, and this Smad4-dependent regulation of S100P by BMP signaling might explain the migratory mechanism of cancer cells, which is still unknown.

Nimesulide inhibits IFN-gamma-induced programmed death-1-ligand 1 surface expression in breast cancer cells by COX-2 and PGE2 independent mechanisms

It is now well established that increased programmed death-1-ligand 1 (PD-L1) surface expression in cancer cells and the resultant T cell suppression contribute to cancer cell immune evasion. Blockade of PD-L1 function has been shown to stimulate anti-cancer immunity. Therefore, compounds that can down-regulate PD-L1 surface expression in cancer cells may serve as novel immune modulators to promote cancer cell-reactive immune responses. In the present study, we examined the effects of nimesulide, a selective COX-2 inhibitor, on PD-L1 surface expression in breast cancer cells by flow cytometry. We demonstrated that nimesulide was able to inhibit IFN-gamma-induced PD-L1 surface expression in breast cancer cells. However, our data indicate that the inhibitory effects of nimesulide appear to be independent of COX-2/PGE2 signaling. Since nimesulide also exhibits anti-tumor activities by inducing cancer cell apoptosis and inhibiting cancer cell proliferation, our findings suggest that nimesulide may represent a new class of chemotherapeutic agents that possess dual functions to inhibit cancer cell growth and promote cancer cell immune responses.

Nonsteroidal anti-inflammatory drugs suppress glioma via 15-hydroxyprostaglandin dehydrogenase

Studies have conjectured that nonsteroidal anti-inflammatory drugs (NSAID) inhibit growth of various malignancies by inhibiting cyclooxygenase-2 (COX-2) enzyme activity. Yet, several lines of evidence indicate that a COX-2-independent mechanism may also be involved in their antitumor effects. Here, we report that NSAIDs may inhibit the growth of glioblastoma multiforme (GBM) cells through COX-2-independent mechanisms, including up-regulation of both 15-hydroxyprostaglandin dehydrogenase (15-PGDH, the key prostaglandin catabolic enzyme) and the cell cycle inhibitor p21. Using Western blot and real-time PCR analysis in various GBM cell lines, we observed up-regulation of 15-PGDH and p21 after NSAIDs treatment. To elucidate the role of 15-PGDH in GBM, transfection assays were conducted using the T98G GBM cell line. Overexpression of 15-PGDH suppressed cell growth and was associated with increased expression of p21. In an attempt to investigate the roles of COX-2, 15-PGDH, and p21 in the inhibition of growth of GBM, small interfering RNA (siRNA) against each of these proteins was transfected into T98G cells. Inhibition of growth mediated by NSAIDs was partially reversed after knockdown of either 15-PGDH or p21, but not after COX-2 knockdown. Moreover, expression level of p21 was not affected in COX-2 siRNA transfected cells. Our studies provide evidence that the up-regulation of 15-PGDH induced by NSAIDs has the potential to inhibit growth of GBM, in part, by up-regulation of p21 possibly independent from COX-2 enzymatic function.

Cyclooxygenase-2 independent effects of cyclooxygenase-2 inhibitors on oxidative stress and intracellular glutathione content in normal and malignant human B-cells

We recently reported that inhibition of Cyclooxygenase-2 (Cox-2) reduced human B-CLL proliferation and survival. Herein, we investigated the mechanisms whereby small molecule Cox-2 selective inhibitors, SC-58125 (a Celebrex analog) and CAY10404 blunt survival of human B-cell lymphomas and chronic lymphocytic leukemia B-cells. SC-58125 and OSU03012 (a Celebrex analog that lacks Cox-2 inhibitory activity) both decreased intracellular glutathione (GSH) content in malignant human B-cells, as well as in Cox-2 deficient mouse B-cells. This new finding supports Cox-2 independent effects of SC-58125. Interestingly, SC-58125 also significantly increased B-cell reactive oxygen species (ROS) production, suggesting that ROS are a pathway that reduces malignant cell survival. Addition of GSH ethyl ester protected B lymphomas from the increased mitochondrial membrane permeability and reduced survival induced by SC-58125. Moreover, the SC-58125-mediated GSH depletion resulted in elevated steady-state levels of the glutamate cysteine ligase catalytic subunit mRNA and protein. These new findings of increased ROS and diminished GSH levels following SC-58125 exposure support novel mechanisms whereby a Cox-2 selective inhibitor reduces malignant B-cell survival. These observations also support the concept that certain Cox-2 selective inhibitors may have therapeutic value in combination with other drugs to kill malignant B lineage cells.

Akt-dependent heme oxygenase-1 induction by NS-398 in C6 glial cells: A potential role for CO in prevention of oxidative damage from hypoxia

We investigated whether increased heme oxygenase (HO)-1 activity by NS-398 is responsible for protection against hypoxia-induced damage in C6 cells. The expression of HO-1 was analyzed by Western blot and cell viability was analyzed by lactate dehydroxygease (LDH) activity. NS-398 increased HO-1 expression in a concentration- and time-dependent manner during both normoxia and hypoxia (95% N(2)/5% CO(2)), but the latter was much more sensitive. Because induction of HO-1 occurred due to hypoxia itself, NS-398 seemed to potentiate the expression of HO-1. The reduced cell viability due to hypoxia was significantly reversed by either NS-398 or [Ru(CO)(3)(Cl)(2)](2), a CO-donor. Zinc protophorphrin (ZnPPIX), a HO-1 inhibitor, inhibited the protective effect of NS-398 against hypoxia. Treatment with glucose oxidase (GOX, 20 mU/ml) increased ROS production and caused apoptotic death, as assayed by DCFH-DA and TUNEL, respectively. NS-398 significantly reduced GOX-induced cell death and ROS production; these effects were reversed by pre-treatment with oxyhemoglobin (HbO(2)), a CO/NO scavenger, or ZnPPIX. Finally, NS-398 increased PPAR-gamma luciferase activity in transiently PPAR-gamma transfected C6 cells, which was antagonized by ZnPPIX. NS-398 increased phosphorylation of Akt, and LY-294002, a specific PI(3) kinase inhibitor, inhibited NS-398-induced HO-1 expression. Taken together, we conclude that therapeutic use of NS-398 in the treatment of oxidative stress-oriented neuronal disorders would be beneficial through dual actions: HO-1 induction and COX-2 inhibition.

7,8-Dihydroxy-4-methylcoumarin induces apoptosis of human lung adenocarcinoma cells by ROS-independent mitochondrial pathway through partial inhibition of ERK/MAPK signaling

Coumarins have attracted intense interest in recent years because they have been identified from natural sources, especially green plants and have diverse pharmacological properties. In this study, we investigated whether 7,8-dihydroxy-4-methylcoumarin (DHMC) caused apoptosis in A549 human non-small cell lung carcinoma cells (NSCLC) and, if so, by what mechanisms. Here, we show that, in A549 human NSCLC cells, DHMC induces apoptosis through mitochondria-mediated caspase-dependent pathway. Although an increase in the levels of reactive oxygen species (ROS) was observed, pre-treatment with antioxidant showed no protective effect against DHMC-induced apoptosis. In addition, our immunoblot data revealed that DHMC treatment led to down-regulation of Bcl-xl, Bax, p21, Cox-2, p53 and upregulation of c-Myc. Results in the present study for the first time suggest that DHMC induces apoptosis in human lung A549 cells through partial inhibition of ERK/MAPK signaling.

Inhibition of cyclooxygenase-2 decreases breast cancer cell motility, invasion and matrix metalloproteinase expression

BACKGROUND

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the formation of prostaglandins. The inducible isoform of COX (COX-2) is highly expressed in aggressive metastatic breast cancers and may play a critical role in cancer progression (i.e. growth and metastasis). However, the exact mechanism(s) for COX-2-enhanced metastasis has yet to be clearly defined. It is well established that one of the direct results of COX-2 action is increased prostaglandin production, especially prostaglandin E2 (PGE2). Here, we correlate the inhibition of COX-2 activity with decreased breast cancer cell proliferation, migration, invasion and matrix metalloproteinase (MMP) expression.

METHODS

Breast cancer cells (Hs578T, MDA-MB-231 and MCF-7) were treated with selective COX-2 inhibitors (NS-398 and Niflumic acid, NA). Cell proliferation was measured by staining with erythrosin B and counting the viable cells using a hemacytometer. Cell migration and invasion were measured using migration and invasion chamber systems. MMP expression was determined by enzyme immunoassay (secreted protein) and real-time quantitative polymerase chain reaction (mRNA).

RESULTS

Our results show that there is a decline in proliferation, migration and invasion by the Hs578T and MDA-MB-231 breast cancer cell lines in the presence of either low concentrations (1 microM or lower) NA or NS-398. We also report that MMP mRNA and protein expression by Hs578T cells is inhibited by NS-398; there was a 50% decrease by 100 muM NS-398. PGE2 completely reversed the inhibitory effect of NS-398 on MMP mRNA expression.

CONCLUSION

Our data suggests that COX-2-dependent activity is a necessary component for cellular and molecular mechanisms of breast cancer cell motility and invasion. COX-2 activity also modulates the expression of MMPs, which may be a part of the molecular mechanism by which COX-2 promotes cell invasion and migration. The studies suggest that COX-2 assists in determining and defining the metastatic signaling pathways that promote the breast cancer progression to metastasis.