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Pioglitazone and Rosiglitazone Decrease Prostaglandin E₂ in Non–Small-Cell Lung Cancer Cells by Up-Regulating 15-Hydroxyprostaglandin Dehydrogenase

Department of Medicine (S.H., R.B., S.S., X.C., S.D.), Division of Pulmonary and Critical Care Medicine, Lung Cancer Research Program and Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California; Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (R.B., S.S., S.D.); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky (H.T.).

Received for publication December 12, 2006.

Accepted for publication April 5, 2007.

	Abstract

Top Abstract Methods and Materials Results Discussion References

 
Lung cancer cells elaborate the immunosuppressive and antiapoptotic mediator prostaglandin E₂ (PGE₂), a product of cyclooxygenase-2 (COX-2) enzyme activity. Because peroxisome proliferator-activated receptor (PPAR) ligands, such as thiazolidinediones (TZDs), inhibit lung cancer cell growth, we examined the effect of the TZDs pioglitazone and rosiglitazone on PGE₂ levels in non–small-cell lung cancer (NSCLC) A427 and A549 cells. Both TZDs inhibited PGE₂ production in NSCLC cells via a COX-2 independent pathway. To define the mechanism underlying COX-2 independent suppression of PGE₂ production, we focused on other enzymes responsible for the synthesis and degradation of PGE₂. The expression of none of the three prostaglandin synthases (microsomal PGES1, PGES2 and cystosolic PGES) was down-regulated by the TZDs. It is noteworthy that 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme that produces biologically inactive 15-ketoprostaglandins from active PGE₂, was induced by TZDs. The TZD-mediated suppression of PGE₂ concentration was significantly inhibited by small interfering RNA to 15-PGDH. Studies using dominant-negative PPAR overexpression or 2-chloro-5-nitrobenzanilide (GW9662; a PPAR antagonist) revealed that the suppressive effect of the TZDs on PGE₂ is PPAR-independent. Together, these findings indicate that it is possible to use a clinically available pharmacological intervention to suppress tumor-derived PGE₂ by enhancing catabolism rather than blocking synthesis.

Increased cyclooxygenase expression (Huang et al., 1998) and elevated PGE₂ production have been implicated in the pathogenesis of several malignancies and are also associated with a poor prognosis in lung cancer (Wolff et al., 1998). Two isoenzymes of cyclooxygenase (COX) have been described: the constitutive enzyme COX-1 and the inducible enzyme COX-2. Elevated expression of COX-2 is found in a variety of malignant tissues, including colon, gastric, esophageal, prostate, breast, and lung carcinomas (Huang et al., 1998; Dannenberg and Zakim, 1999; Molina et al., 1999; Shamma et al., 2000; Shao et al., 2000; Soslow et al., 2000; Williams et al., 2000; Yip-Schneider et al., 2000). The COX enzyme possesses two distinct enzymatic functions: a cyclooxygenase activity that converts arachidonic acids to prostaglandin (PG) G2 and a peroxidase activity, which converts PGG2 to PGH2. PGH2 is then converted to PGE₂, PGD₂, PGF₂, PGI₂, and thromboxane A₂ by their respective synthases (Smith et al., 1991).

PGE₂ may promote malignant growth by stimulating angiogenesis, tumor invasiveness, and apoptosis resistance and by inhibiting immune surveillance in human non–small-cell lung cancer (NSCLC) (Stolina et al., 2000; Heuze-Vourc'h et al., 2003; Krysan et al., 2004; Pôld et al., 2004). One strategy for inhibiting carcinogenesis or treating established disease is to prevent the overproduction of PGE₂ in premalignant or malignant tissues. In fact, in murine models, COX-2 inhibitory drugs or treatment with anti-PGE₂ monoclonal antibody have been demonstrated to reduce tumor growth, leading to prolonged survival (Stolina et al., 2000).

Considerable evidence suggests that COX-2, an inducible enzyme expressed in response to cytokines, growth factors, and other stimuli, is a potential pharmacologic target for inhibiting or preventing tumor growth (Riedl et al., 2004; Sandler and Dubinett, 2004). Although studies have suggested that COX-2 inhibition may be beneficial in cancer prevention, recent data raise concern regarding cardiovascular toxicities associated with the use of COX-2 inhibition (Schrör et al., 2005). An alternative approach that could potentially avoid this toxicity includes targeting other elements in the prostanoid pathway downstream of COX-2.

The nicotinamide adenine dinucleotide positive-dependent catabolic enzyme 15-PGDH metabolizes PGE₂ to the biologically inactive 15-keto derivatives (Cho and Tai, 2002). 15-PGDH has recently been identified as a tumor suppressor gene (Ding et al., 2005; Wolf et al., 2006). When the expression of 15-PGDH is suppressed, the limited degradation of PGE₂ may lead to increased tumor growth (Ding et al., 2005). Thus, augmentation of 15-PGDH expression and activity could limit PGE₂ without affecting COX-2.

Thiazolidinedione (TZDs), also known as peroxisome proliferator-activated receptor- (PPAR-) ligands, may modulate cancer progression and have been the subject of extensive investigation. For example, recent studies show that ciglitazone inhibited the growth of lung cancer cells via induction of apoptosis and differentiation (Chang and Szabo, 2000). In this study, we investigated the effect of the TZDs pioglitatzone and rosiglitazone on COX-2 and PGE₂ levels in NSCLC cell lines. We report that both TZDs suppress PGE₂ levels in a COX-2 expression-independent and 15-PGDH-dependent manner.

	Methods and Materials

Top Abstract Methods and Materials Results Discussion References

 
Cell Culture and Reagents. Human A427 (obtained from Dr. J. A. Radosevich, Northwestern University, Evanston, IL) and A549 (American Type Culture Collection, Manassas, VA) are maintained in Dulbecco's modified Eagle's medium (Mediatech, Herndon, VA) supplemented with 4.5 g/liter glucose and 4 mM L-glutamine, 100 units/ml penicillin/streptomycin (Invitrogen, Carsbad, CA), and 10% fetal calf serum (Gemini Bio-Products, Woodland, CA). Cell cultures were grown in 5% CO₂ atmosphere at 37°C. The TZDs used in these studies were pioglitazone (Actos; Eli Lilly, Toronto, ON, Canada) and rosiglitazone (Cayman Chemical, Ann Arbor, MI). DMSO was used as a diluent. The cells were incubated with 1 to 10 µM pioglitazone or rosiglitazone for 24 h for PGE₂ ELISA. Pioglitazone and rosiglitazone were used at a concentration of 10 µM for the rest of the experiments. To assess the role of PPAR, experiments were performed in the presence of the PPAR antagonist GW9662 (10 µM) (Sigma-Aldrich Co, St. Louis, MO) or dn.PPAR.

PGE₂ Enzyme Immunoassay. Cells were plated in six-well plates in RPMI 1640 medium containing 10% FBS and cultured overnight. The next day, cells were treated with pioglitazone and rosiglitazone (10 µM) for 24 h. Arachidonic acid (final concentration, 15 µM) was added to the culture 1 h before collecting the culture medium. Therefore, TZDs and arachidonic acid were both in the medium for only 1 h before collecting the supernatant for PGE₂ assays. PGE₂ levels were determined by PGE₂ enzyme immunoassay kits (Cayman Chemical). Cells were lysed with radioimmunoprecipitation assay buffer and the COX-2 levels were determined by human COX-2 ELISA kits (Assay Designs, Ann Arbor, MI).

COX-2 ELISA. Cells were plated in six-well plates in RPMI 1640 medium containing 10% FBS medium and treated as described above. The lysates were stored at –80°C for protein isolation. COX-2 protein was measured by the Human Cyclooxygenase-2 Enzyme Immunometric Assay Kit (Assay Designs) using 30 µg of each protein sample.

Western Blot Analysis of Cellular Proteins. NSCLC cells were cultured in a six-well plate for 24 h. Cells were washed with PBS once and lysed with a lysis buffer containing 50 mM Tris-HCl, pH 7.4, 1% Nonidet P-40, 0.25% sodium deoxycholate, 150 mM NaCl, 1 mM EDTA, 1 mM phenylmethylsulfonyl fluoride, 1x complete protease inhibitor mixture (Roche Diagnostics Corp., Indianapolis, IN), 1 mM Na₃VO₄, and 1 mM NaF. The protein content was measured using Bradford reagent (Bio-Rad Laboratories, Hercules, CA). An equal amount (20 µg) of the whole-cell protein was run and separated by SDS-polyacrylamide gel electrophoresis and transferred on polyvinylidene difluoride membranes (Millipore Corp., Billerica, MA). Proteins were detected by incubating the filter with COX-2 polyclonal antibody (Santa Cruz Biotechnology, Santa Cruz, CA), Glyceraldehyde-3-phosphate dehydrogenase monoclonal antibody (Advanced Immuno Chemicals Inc., Long Beach, CA) at a concentration of 0.2 to 2 µg/10 ml in Tris-buffered saline (100 mM Tris-HCl and 1.5 M NaCl, pH 7.4) with 5% nonfat milk. For determining the expression of all three prostaglandin E synthases and 15-PGDH after pioglitazone and rosiglitazone treatment, polyclonal antibodies (Cayman Chemical) against prostaglandin E synthase-1 (microsomal), prostaglandin E synthase (cytosolic), prostaglandin E synthase-2 (microsomal) and 15-PGDH were used. The blots were subsequently incubated with an appropriate horseradish peroxidase-conjugated secondary antibodies (Santa Cruz Biotechnology, Santa Cruz, CA) at 1 µg/10 ml. Detection of proteins on Western blots was achieved using the ECL detection system (Amersham, Piscataway, NJ). Equal protein loading was confirmed by immunodetecting the membranes with anti-GAPDH antibody.

View larger version (29K): [in this window] [in a new window]   Fig. 1. A and B, pioglitazone and rosiglitazone decrease PGE2. A427 and A549 cells were treated with 1 to 10 µM concentrations of either pioglitazone or rosiglitazone for 24 h in six-well plates in serum-free medium. Arachidonic acid (15 µM) was applied 1 h before collecting the conditioned medium. PGE2 concentrations in the medium were then assessed by ELISA. PGE2 was significantly decreased by pioglitazone and rosiglitazone (10 µM) by approximately 2- and 3-fold, respectively, in the A427 cell line (Fig. 1A) (*, P < 0.05, compared with the control "DMSO+ARA"). Pioglitazone and rosiglitazone (10 µM) decreased PGE2 by approximately 2-fold in A549 cells (B) (*, P < 0.05, compared with control "DMSO+ARA"). All data are representative of four independent experiments. ARA, arachidonic acid; Pio, pioglitazone; Rosi, rosiglitazone.

Transient Transfection/PGE₂ Assay. The dn.PPAR construct was a generous gift of Dr. V. K. Chatterjee (Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK) (Gurnell et al., 2000). Cells were seeded at a density of 3 x 10⁶ A549 cells/well in a six-well plate in RPMI 1640 medium containing 10% fetal bovine serum and cultured overnight. For each well, 1 µgofthe PCDNA3 control vector or 1 µg of dn.PPAR vector was transfected with the Effectene transfection reagent (QIAGEN) according to the manufacturer's protocol. The TZDs (10 µM) were added 24 h after the transfection in a serum-free medium for another 24 h. Arachidonic acid (15 µM) was added 1 h before harvesting the medium. Culture medium was collected and PGE₂ levels were determined using PGE₂ EIA kit (Cayman Chemicals, Ann Arbor, MI).

Statistical Analysis: Probability values were calculated using two-tailed non paired Student's t test. Tests of statistical significance were significant if P < 0.05.

	Results

Top Abstract Methods and Materials Results Discussion References

 
Pioglitazone and Rosiglitazone Inhibit PGE₂ Production in NSCLC Cell Lines. Two NSCLC cell lines, A427 and A549, were used to access the Effect of TZDs on PGE₂ production. These cells were incubated with 1 to 10 µM pioglitazone or rosiglitazone for 24 h. The greatest inhibition of PGE₂ by these TZDs was observed at 10 µM in both A427 (Fig. 1A) and in A549 (Fig. 1B) cells when 1, 5, and 10 µM TZDs were used for the treatment.

Suppression of PGE₂ by Pioglitazone and Rosiglitazone Is Mediated via a COX-2 Expression-Independent Pathway. To determine whether this inhibition of PGE₂ was COX-2-dependent, we tested the capacity of these TZDs to inhibit IL-1-induced COX-2 expression in NSCLC cells. Neither pioglitazone (Fig. 2A) nor rosiglitazone (Fig. 2A) decreased IL-1 induced COX-2 expression levels, as shown in Western blots. These results were also confirmed by COX-2 ELISA assay as shown in Fig. 2, B and C.

View larger version (31K): [in this window] [in a new window]   Fig. 2. NSCLC cells were pretreated with IL- (280 units/ml) for 30 min followed by treatment with 10 µM concentrations of either pioglitazone or rosiglitazone for 24 h in six-well plates in serum-free conditions. Western blot analysis shows that pioglitazone and rosiglitazone did not alter COX-2 protein levels in either A549 or A427 cell line (A). This was further confirmed by COX-2 ELISA assay. Neither pioglitazone (B) nor rosiglitazone (C) affected basal or IL1-induced COX-2 levels in NSCLC cell lines. Data are representative of four independent experiments. Pio, pioglitazone; Rosi, rosiglitazone.

Here, we determined whether these three enzymes (mPGES1, cPGES, mPGES2) were altered by TZDs in A427 and A549 cell lines (Fig. 3, A–D). Western blot analysis of the mPGES1, cPGES, and mPGES2 enzymes revealed no pioglitazone- or rosiglitazone-mediated decrease in expression.

View larger version (45K): [in this window] [in a new window]   Fig. 3. Neither pioglitazone nor rosiglitazone suppress PGES expression in NSCLC, although they up-regulate 15-PGDH protein expression. The cells were treated with TZDs or DMSO for 24 h in serum-free medium. Both pioglitazone (10 µM) and rosiglitazone (10 µM) failed to inhibit mPGES1 (A), cPGES (B), and mPGES2 (C) expression compared with the DMSO control in both A427 and A549 cells, suggesting that the TZDs suppressed PGE2 in a PGES-independent manner. The bottom panel of GAPDH expression (D) shows the equal loading of the protein samples. (Data are representative of three independent experiments). Pioglitazone and rosiglitazone increase 15-PGDH protein levels in NSCLC cell lines. Western blots were performed with the whole protein extracts from 24-h TZD-treated cells. Treatment with pioglitazone (10 µM) shows a significant increase in the 15-PGDH protein expression in both A427 and A549 cell lines (E). Rosiglitazone treatment (10 µM, 24 h) up-regulated 15-PGDH protein expression in both A427 and A549 cell lines (F). Blots were stripped and re-probed with anti-GAPDH antibody to verify equal loading (E and F, bottom). (Data are representative of three independent experiments).

15-PGDH Mediates the Inhibition of PGE₂ by TZDs in NSCLC Cells. To determine the role of 15-PGDH in the reduction of PGE₂ concentrations by pioglitazone and rosiglitazone, A549 cells were transiently transfected with siRNA targeting the 15-PGDH gene. After transfection with 15-PGDH siRNA, Western blot analysis revealed significant suppression of 15-PGDH protein, whereas it did not affect GAPDH protein expression in A549 cells (Fig. 4A). After 24-h treatment with pioglitazone or rosiglitazone, cell-free culture supernatants were harvested for PGE₂ assays. In the absence of TZDs, 15-PGDH siRNA-treated cells showed a marked increase in PGE₂ concentrations compared with those of control siRNA. (Fig. 4, B and C). Although significant reductions in PGE₂ concentrations (approximately 50% for both pioglitazone and rosiglitazone) were demonstrated in the control siRNA-transfected cells after TZD exposure, these reductions were not evident in 15-PGDH siRNA-transfected cells. This suggests that 15-PGDH induction is critical for the pioglitazone- and rosiglitazone-mediated suppression of PGE₂ levels.

View larger version (30K): [in this window] [in a new window]   Fig. 4. A–C, 15-PGDH inhibition by siRNA prevents the TZD-mediated suppression of PGE2 levels in A549 cells. Silencing of 15-PGDH by siRNA transfection shows a significant suppression of 15-PGDH protein, whereas no change in control GAPDH protein expression was demonstrated by Western blot analysis (A). In the control siRNA-transfected cells, PGE2 levels were increased in the presence of arachidonic acid (15 µM), whereas pioglitazone (B) or rosiglitazone (C) treatment significantly reduced PGE2 concentrations (*, P < 0.05). Inhibition of 15-PGDH by siRNA led to a marked increase in PGE2 levels compared with the control siRNA transfection in the presence of arachidonic acid (15 µM) (B and C). In the presence of 15-PGDH siRNA, pioglitazone and rosiglitazone did not significantly (NS, nonsignificant) decrease PGE2 levels (B and C). Data are representative of three independent experiments. ARA, arachidonic acid; Pio, pioglitazone; Rosi, rosiglitazone.

Suppression of PGE₂ by Pioglitazone and Rosiglitazone Is PPAR-Independent. To determine whether the suppressive effects of pioglitazone and rosiglitazone are PPAR-dependent, a dominant-negative PPAR plasmid construct (Gurnell et al., 2000) was transfected in A549 cells. As expected, the PPRE activity was increased in the presence of both pioglitazone and rosiglitazone in NSCLC (Fig. 5A). Expression of dn.PPAR significantly suppressed the induction of basal as well as TZD-mediated PPRE activity in A549 cell lines (Fig. 5A), indicating significant suppression of PPAR expression by dn.PPAR. In the presence of overexpression of dn.PPAR (Fig. 5, B and C), pioglitazone and rosiglitazone maintained the capacity to decrease PGE₂, suggesting that this effect of the TZDs is PPAR-independent. This observation was further verified by using GW9662, a PPAR antagonist (Fig. 5, D and E). GW9662 (10 µM) was added 1 h before addition of pioglitazone or rosiglitazone in A427 cells. The experimental results using dn.PPAR and GW9662 suggest that the suppression of PGE₂ by these TZDs is PPAR-independent.

View larger version (35K): [in this window] [in a new window]   Fig. 5. A–E, PPAR antagonists do not alter PGE2 levels in NSCLC cell lines. The cells were first transiently transfected with dn.PPAR for 24 h followed by incubation with 10 µM pioglitazone and rosiglitazone for another 24 h. A shows the effect of a dn.PPAR expression (by transient transfection) on pioglitazone- or rosiglitazone-mediated up-regulation of PPRE activity in A549 cell line. The basal and TZD-mediated PPRE activity was significantly suppressed by dn.PPAR expression (*, P < 0.05). Arachidonic acid (15 µM) was added before the collection of the medium for PGE2 assay. The overexpression of dn.PPAR did not abrogate the suppression effect of pioglitazone (B) and rosiglitazone (C) on PGE2 levels in A549 cell line. GW9662, a PPAR antagonist, was applied to A427 cells. One hour before adding pioglitazone (D) or rosiglitazone (E), GW9662 (10 µM) was applied to the medium. One representative experiment of three independent experiments is shown here. *, P 0.05. ARA, arachidonic acid; Pio, pioglitazone; Rosi, rosiglitazone.

	Discussion

Top Abstract Methods and Materials Results Discussion References

 
We report that pioglitazone and rosiglitazone have the capacity to reduce PGE₂ production in NSCLC. To avoid the potential cardiovascular toxicities of COX-2 inhibition, we evaluated pharmacologic agents for their capacity to regulate tumor derived PGE₂ by modulating arachidonic acid pathway elements downstream of COX-2. Because PGE₂ was decreased without changes in COX-2 levels, we concluded that these TZDs reduce PGE₂ in a COX-2 expression-independent manner. We found that PGES protein levels were not suppressed by the TZDs in NSCLC cells. In contrast, 15-PGDH expression was up-regulated by TZDs.

Colon cancers have been observed to manifest very limited expression of 15-PGDH; Backlund et al. (2005) also reported that 15-PGDH is down-regulated in colorectal cancer. Furthermore, levels of 15-PGDH are reduced in several other malignancies, including NSCLC; Ding et al. (2005) found that, compared with normal epithelial cells, 15-PGDH expression was diminished in human lung tumors. This led to the suggestion that 15-PGDH, by suppressing the level of PGE₂, may promote susceptibility to apoptosis and thus function as a tumor suppressor gene (Ding et al., 2005). Thus, the development of certain malignancies may require a combination of up-regulated COX-2 expression and a concomitant down-regulation of an opposing and putative tumor suppressor gene, 15-PGDH (Yan et al., 2004). Consistent with these previous investigations, we found that 15-PGDH inhibition by siRNA increases PGE₂ production in A549 cells. We report here that the capacity for pioglitazone and rosiglitazone to decrease PGE₂ was significantly decreased after 15-PGDH si-RNA transfection.

TZDs are currently used for the treatment of type 2 diabetes mellitus (Durbin, 2004) and have been shown to have a broad array of biological activities. Some of these TZDs have been shown to exert anti-inflammatory (Consoli and Devangelio, 2005), antiproliferative (Schmidt et al., 2004), and antiangiogenic effects (Keshamouni et al., 2005). TZD-mediated PPAR activation has been shown to regulate COX-2 expression in several malignancies including cervical (Han et al., 2003), colon, and liver cancers (Li et al., 2003). It has been reported that TZDs inhibit tumor formation in a variety of animal models, including colon (Yoshizumi et al., 2004) and lung cancers (Keshamouni et al., 2004). PPAR is expressed in many NSCLC cell lines (Chang and Szabo, 2000), and troglitazone and pioglitazone significantly inhibit angiogenesis in NSCLC (Keshamouni et al., 2005). These two TZDs were also shown to inhibit tumor-associated angiogenesis by blocking the expression of ELR+CXC chemokines.

Although TZDs are widely known as ligands for PPAR, they may mediate receptor-independent effects, as demonstrated here and as previously reported (Chawla et al., 2001; Lennon et al., 2002). For example, by using the embryonic stem cells from PPAR-null mice, Chawla et al. (2001) found that neither macrophage differentiation nor anti-inflammatory effects of synthetic PPAR ligands are PPAR receptor-dependent. To understand whether the suppression of PGE₂ by pioglitazone and rosiglitazone is PPAR-dependent in NSCLC, we performed experiments using either a dn.PPAR plasmid vector or a PPAR inhibitor GW9662. Here, for the first time, we report that pioglitazone and rosiglitazone increase 15-PGDH and thus decrease PGE₂ in a PPAR-independent manner.

PGE₂ is well-known to play an important role in tumorigenesis. However, the precise role of the 15-PGDH enzyme, which regulates the biological activity via degradation of PGE₂, has not yet been well defined in the pathogenesis of lung cancer.

The potential benefits of inhibiting PGE₂ levels in a COX-2-independent manner include the following. First, promoting 15-PGDH activity could decrease PGE₂ without modifying other prostaglandins such as PGI₂. This is potentially important because the latter has been noted to have antitumor properties (Keith et al., 2004). It has been suggested that a ratio of PGs may be important in regulating the malignant phenotype. Thus, inhibiting COX-2 activity would diminish both PGE₂ and PGI₂, whereas selective induction of 15-PGDH could lead to a more favorable PGI₂/PGE₂ ratio. Second, the suppression of PGE₂ levels without alteration in COX-2 may limit some of the cardiovascular toxicities associated with COX-2 inhibition. Finally, unlike COX-2 inhibition, which may lead to up-regulation of certain leukotrienes that favor malignant progression (Mao et al., 2004), 15-PGDH induction may lead only to a decrement of PGE₂. This speculation will require further investigation. Ultimately, these findings will allow strategies for developing PGE₂ inhibitors in the treatment and prevention of lung cancer.

	Acknowledgements

 
We thank Dr. Andrew Dannenberg (Department of Medicine, Weill Medical College of Cornell University, New York, NY) and Dr. Peter Tontonoz (Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA) for their valuable suggestions.

	Footnotes

 
This work was supported by UCLA Specialized Programs of Research Excellence in Lung Cancer, National Institutes of Health grants P50-CA90388 and R01-CA111851, UC Tobacco-Related Disease Research Program (13RT-0031); Medical Research Funds from The Department of Veteran Affairs; and The Flight Attendant Medical Research Institute (FAMRI) Young Clinical Scientist Awards.

Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.

doi:10.1124/mol.106.033357.

ABBREVIATIONS: COX, cyclooxygenase; PG, prostaglandin; NSCLC, non–small-cell lung cancer; PGDH, 15-hydroxyprostaglandin dehydrogenase; TZD, thiazolidinedione; PPAR-, peroxisome proliferator-activated receptor-; DMSO, dimethyl sulfoxide; ELISA, enzyme-linked immunosorbent assay; GW9662, 2-chloro-5-nitrobenzanilide; dn, dominant negative; FBS, fetal bovine serum; siRNA, small interfering RNA; PGES, prostaglandin E synthase; mPGES1, microsomal prostaglandin E synthase; cPGES, cytosolic prostaglandin E synthase; PPRE, peroxisome proliferator-activated receptor response element.

Address correspondence to: Saswati Hazra, UCLA Lung Cancer Research Program of the Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, 37-131 CHS, 10833 Le Conte Avenue, Los Angeles, CA 90095-1690. E-mail: shazra{at}mednet.ucla.edu

	References

Top Abstract Methods and Materials Results Discussion References

 
Backlund MG, Mann JR, Holla VR, Buchanan FG, Tai HH, Musiek ES, Milne GL, Katkuri S, and DuBois RN (2005) 15-Hydroxyprostaglandin dehydrogenase is down-regulated in colorectal cancer. J Biol Chem 280: 3217–3223.[Abstract/Free Full Text]

Chang TH and Szabo E (2000) Induction of differentiation and apoptosis by ligands of peroxisome proliferator-activated receptor gamma in non-small cell lung cancer. Cancer Res 60: 1129–1138.[Abstract/Free Full Text]

Chawla A, Barak Y, Nagy L, Liao D, Tontonoz P, and Evans RM (2001) PPAR-gamma dependent and independent effects on macrophage-gene expression in lipid metabolism and inflammation. Nat Med 7: 48–52.[CrossRef][Medline]

Cho H and Tai HH (2002) Inhibition of NAD⁺-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) by cyclooxygenase inhibitors and chemopreventive agents. Prostaglandins Leukot Essent Fatty Acids 67: 461–465.[CrossRef][Medline]

Consoli A and Devangelio E (2005) Thiazolidinediones and inflammation. Lupus 14: 794–797.[Abstract/Free Full Text]

Dannenberg AJ and Zakim D (1999) Chemoprevention of colorectal cancer through inhibition of cyclooxygenase-2. Semin Oncol 26: 499–504.[Medline]

Ding Y, Tong M, Liu S, Moscow JA, and Tai HH (2005) NAD⁺-linked 15-hydroxyprostaglandin dehydrogenase (15-PGDH) behaves as a tumor suppressor in lung cancer. Carcinogenesis 26: 65–72.[Abstract/Free Full Text]

Durbin RJ (2004) Thiazolidinedione therapy in the prevention/delay of type 2 diabetes in patients with impaired glucose tolerance and insulin resistance. Diabetes Obes Metab 6: 280–285.[CrossRef][Medline]

Gurnell M, Wentworth JM, Agostini M, Adams M, Collingwood TN, Provenzano C, Browne PO, Rajanayagam O, Burris TP, Schwabe JW, et al. (2000) A dominant-negative peroxisome proliferator-activated receptor (PPAR) mutant is a constitutive repressor and inhibits PPAR-mediated adipogenesis. J Biol Chem 275: 5754–5759.[Abstract/Free Full Text]

Han S, Inoue H, Flowers LC, and Sidell N (2003) Control of COX-2 gene expression through peroxisome proliferator-activated receptor in human cervical cancer cells. Clin Cancer Res 9: 4627–4635.[Abstract/Free Full Text]

Heuze-Vourc'h N, Zhu L, Krysan K, Batra RK, Sharma S, and Dubinett SM (2003) Abnormal interleukin 10Ralpha expression contributes to the maintenance of elevated cyclooxygenase-2 in non-small cell lung cancer cells. Cancer Res 63: 766–770.[Abstract/Free Full Text]

Huang M, Stolina M, Sharma S, Mao JT, Zhu L, Miller PW, Wollman J, Herschman H, and Dubinett SM (1998) Non-small cell lung cancer cyclooxygenase-2-dependent regulation of cytokine balance in lymphocytes and macrophages: up-regulation of interleukin 10 and down-regulation of interleukin 12 production. Cancer Res 58: 1208–1216.[Abstract/Free Full Text]

Keith RL, Miller YE, Hudish TM, Girod CE, Sotto-Santiago S, Franklin WA, Nemenoff RA, March TH, Nana-Sinkam SP, and Geraci MW (2004) Pulmonary prostacyclin synthase overexpression chemoprevents tobacco smoke lung carcinogenesis in mice. Cancer Res 64: 5897–5904.[Abstract/Free Full Text]

Keshamouni VG, Arenberg DA, Reddy RC, Newstead MJ, Anthwal S, and Standiford TJ (2005) PPAR-gamma activation inhibits angiogenesis by blocking ELR+CXC chemokine production in non-small cell lung cancer. Neoplasia 7: 294–301.[CrossRef][Medline]

Keshamouni VG, Reddy RC, Arenberg DA, Joel B, Thannickal VJ, Kalemkerian GP, and Standiford TJ (2004) Peroxisome proliferator-activated receptor-gamma activation inhibits tumor progression in non-small-cell lung cancer. Oncogene 23: 100–108.[CrossRef][Medline]

Krysan K, Merchant FH, Zhu L, Dohadwala M, Luo J, Lin Y, Heuze-Vourc'h N, Pôld M, Seligson D, Chia D, et al. (2004) COX-2-dependent stabilization of survivin in non-small cell lung cancer. FASEB J 18: 206–208.[Abstract/Free Full Text]

Lennon AM, Ramauge M, Dessouroux A, and Pierre M (2002) MAP kinase cascades are activated in astrocytes and preadipocytes by 15-deoxy-^12–14-prostaglandin J₂ and the thiazolidinedione ciglitazone through peroxisome proliferator activator receptor -independent mechanisms involving reactive oxygenated species. J Biol Chem 277: 29681–29685.[Abstract/Free Full Text]

Li MY, Deng H, Zhao JM, Dai D, and Tan XY (2003) PPARgamma pathway activation results in apoptosis and COX-2 inhibition in HepG2 cells. World J Gastroenterol 9: 1220–1226.[Medline]

Mao JT, Tsu IH, Dubinett SM, Adams B, Sarafian T, Baratelli F, Roth MD, and Serio KJ (2004) Modulation of pulmonary leukotriene B4 production by cyclooxygenase-2 inhibitors and lipopolysaccharide. Clin Cancer Res 10: 6872–6878.[Abstract/Free Full Text]

Molina MA, Sitja-Arnau M, Lemoine MG, Frazier ML, and Sinicrope FA (1999) Increased cyclooxygenase-2 expression in human pancreatic carcinomas and cell lines: growth inhibition by nonsteroidal anti-inflammatory drugs. Cancer Res 59: 4356–4362.[Abstract/Free Full Text]

Murakami M, and Kudo I (2006) Prostaglandin E synthase: a novel drug target for inflammation and cancer. Curr Pharm Des 12: 943–954.[CrossRef][Medline]

Parkin DM (2001) Global cancer statistics in the year 2000. Lancet Oncol 2: 533–543.[CrossRef][Medline]

Pôld M, Zhu LX, Sharma S, Burdick MD, Lin Y, Lee PP, Pôld A, Luo J, Krysan K, Dohadwala M, et al. (2004) Cyclooxygenase-2-dependent expression of angiogenic CXC chemokines ENA-78/CXC Ligand (CXCL) 5 and interleukin-8/CXCL8 in human non-small cell lung cancer. Cancer Res 64: 1853–1860.[Abstract/Free Full Text]

Riedl K, Krysan K, Pôld M, Dalwadi H, Heuze-Vourc'h N, Dohadwala M, Liu M, Cui X, Figlin R, Mao JT, et al. (2004) Multifaceted roles of cyclooxygenase-2 in lung cancer. Drug Resist Updat 7: 169–184.[CrossRef][Medline]

Sandler AB and Dubinett SM (2004) COX-2 inhibition and lung cancer. Semin Oncol 31(2 Suppl 7): 45–52.[Medline]

Schmidt S, Moric E, Schmidt M, Sastre M, Feinstein DL, and Heneka MT (2004) Anti-inflammatory and antiproliferative actions of PPAR-gamma agonists on T lymphocytes derived from MS patients. J Leukoc Biol 75: 478–485.[Abstract/Free Full Text]

Schrör K, Mehta P, and Mehta JL (2005) Cardiovascular risk of selective cyclooxygenase-2 inhibitors. J Cardiovasc Pharmacol Ther 10: 95–101.[Abstract/Free Full Text]

Shamma A, Yamamoto H, Doki Y, Okami J, Kondo M, Fujiwara Y, Yano M, Inoue M, Matsuura N, Shiozaki H, et al. (2000) Up-regulation of cyclooxygenase-2 in squamous carcinogenesis of the esophagus. Clin Cancer Res 6: 1229–1238.[Abstract/Free Full Text]

Shao J, Sheng H, Inoue H, Morrow JD, and DuBois RN (2000) Regulation of constitutive cyclooxygenase-2 expression in colon carcinoma cells. J Biol Chem 275: 33951–33956.[Abstract/Free Full Text]

Smith WL, Marnett LJ, and DeWitt DL (1991) Prostaglandin and thromboxane biosynthesis. Pharmacol Ther 49: 153–179.[CrossRef][Medline]

Soslow RA, Dannenberg AJ, Rush D, Woerner BM, Khan KN, Masferrer J, and Koki AT (2000) COX-2 is expressed in human pulmonary, colonic, and mammary tumors. Cancer 89: 2637–2645.[CrossRef][Medline]

Stolina M, Sharma S, Lin Y, Dohadwala M, Gardner B, Luo J, Zhu L, Kronenberg M, Miller PW, Portanova J, et al. (2000) Specific inhibition of cyclooxygenase 2 restores antitumor reactivity by altering the balance of IL-10 and IL-12 synthesis. J Immunol 164: 361–370.[Abstract/Free Full Text]

Williams CS, Tsujii M, Reese J, Dey SK, and DuBois RN (2000) Host cyclooxygenase-2 modulates carcinoma growth. J Clin Invest 105: 1589–1594.[Medline]

Wolf I, O'Kelly J, Rubinek T, Tong M, Nguyen A, Lin BT, Tai HH, Karlan BY, and Koeffler HP (2006) 15-hydroxyprostaglandin dehydrogenase is a tumor suppressor of human breast cancer. Cancer Res 66: 7818–7823.[Abstract/Free Full Text]

Wolff H, Saukkonen K, Anttila S, Karjalainen A, Vainio H, and Ristimaki A (1998) Expression of cyclooxygenase-2 in human lung carcinoma. Cancer Res 58: 4997–5001.[Abstract/Free Full Text]

Yan M, Rerko RM, Platzer P, Dawson D, Willis J, Tong M, Lawrence E, Lutterbaugh J, Lu S, Willson JK, et al. (2004) 15-Hydroxyprostaglandin dehydrogenase, a COX-2 oncogene antagonist, is a TGF-beta-induced suppressor of human gastrointestinal cancers. Proc Natl Acad Sci U S A 101: 17468–17473.[Abstract/Free Full Text]

Yip-Schneider MT, Barnard DS, Billings SD, Cheng L, Heilman DK, Lin A, Marshall SJ, Crowell PL, Marshall MS, and Sweeney CJ (2000) Cyclooxygenase-2 expression in human pancreatic adenocarcinomas. Carcinogenesis 21: 139–146.[Abstract/Free Full Text]

Yoshizumi T, Ohta T, Ninomiya I, Terada I, Fushida S, Fujimura T, Nishimura G, Shimizu K, Yi S, and Miwa K (2004) Thiazolidinedione, a peroxisome proliferator-activated receptor-gamma ligand, inhibits growth and metastasis of HT-29 human colon cancer cells through differentiation-promoting effects. Int J Oncol 25: 631–639.[Medline]

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