celecoxib, Celebrex
From the cyclooxygenase-2 inhibitor celecoxib to a novel class of 3-phosphoinositide-dependent protein kinase-1 inhibitors.

Zhu J, Huang JW, Tseng PH, Yang YT, Fowble J, Shiau CW, Shaw YJ, Kulp SK, Chen CS.

Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, 43210, USA.

The blockade of Akt activation through the inhibition of 3-phosphoinositide-dependent kinase-1 (PDK-1) represents a major signaling mechanism whereby celecoxib mediates apoptosis. Celecoxib, however, is a weak PDK-1 inhibitor (IC(50), 48 microM), requiring at least 30 microM to exhibit discernable effects on the growth of tumor cells in vitro. Here, we report the structure-based optimization of celecoxib to develop PDK-1 inhibitors with greater potency in enzyme inhibition and growth inhibition. Kinetics of PDK-1 inhibition by celecoxib with respect to ATP suggest that celecoxib derivatives inhibit PDK-1 by competing with ATP for binding, a mechanism reminiscent to that of many kinase inhibitors. Structure-activity analysis together with molecular modeling was used to generate compounds that were tested for their potency in inhibiting PDK-1 kinase activity and in inducing apoptosis in PC-3 prostate cancer cells. Docking of potent compounds into the ATP-binding site of PDK-1 was performed for lead optimization, leading to two compounds, OSU-03012 and OSU-03013, with IC(50) values in PDK-1 inhibition and apoptosis induction in the low microM range. Exposure of PC-3 cells to these agents led to Akt dephosphorylation and inhibition of p70 S6 kinase activity. Moreover, overexpression of constitutively active forms of PDK-1 and Akt partially protected OSU-03012-induced apoptosis. Screening in a panel of 60 cell lines and more extensive testing in PC-3 cells indicated that the mean concentration for total growth inhibition was approximately 3 microM for both agents. Considering the conserved role of PDK-1/Akt signaling in promoting tumorigenesis, these celecoxib analogs are of translational relevance for cancer prevention and therapy.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15205346&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Modulation by celecoxib and difluoromethylornithine of the methylation of DNA and the estrogen receptor-alpha gene in rat colon tumors.

Pereira MA, Tao L, Wang W, Li Y, Umar A, Steele VE, Lubet RA.

Department of Pathology, Medical College of Ohio, Toledo, OH 43614, USA. pereira-l medctr.osu.edu

The ability of celecoxib and alpha-difluoromethylornithine (DFMO) to modulate the DNA hypomethylation and the hypermethylation of the estrogen receptor (ER)-alpha gene in colon tumors was evaluated as potential biomarkers for chemoprevention. Colon tumors were induced in rats by azoxymethane. Celecoxib (500 mg/kg), DFMO (100, 1000 and 3000 mg/kg) or celecoxib + 1000 mg/kg DFMO were administered in the diet for 7 or 28 days prior to death at week 37. Relative to the normal colon mucosa, colon tumors contained global hypomethylated DNA but simultaneous hypermethylation of the promoter plus exon-1 region of the ER-alpha gene. Limited treatment with celecoxib (500 p.p.m. in diet) or DFMO (1000 or 3000 p.p.m. in diet) reversed the DNA hypomethylation. Administering 1000 and 3000 p.p.m. DFMO for 7-days decreased the number of methylated CpG sites in the ER-alpha gene from 5.00 +/- 0.95 to 3.83 +/- 0.75 and 1.75 +/- 0.49 these levels were further reduced to 0.50 +/- 0.26 following administration of 1000 mg/kg for 28 days. Celecoxib administered for 7 and 28 days reduced the number of methylated sites to 4.25 +/- 0.48 and 1.5 +/- 0.50. The combination containing celecoxib and DFMO reduced the number of methylated sites to 0.20 +/- 0.20 at both 7 and 28 days. In parallel with the hypermethylation of the ER-alpha gene, the mRNA expression of the gene was decreased in colon tumors and was increased by celecoxib, DFMO or the combination. Celecoxib and DFMO reversed DNA hypomethylation and the hypermethylation of the ER-alpha gene in colon tumors supporting the hypothesis that modulation of methylation is a biomarker of chemoprevention.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15205357&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Relationship between COX-2 specific inhibitors and hypertension.

Solomon DH, Schneeweiss S, Levin R, Avorn J.

Division of Pharmacoepidemiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02120, USA. dhsolomon partners.org

There is controversy whether cyclooxygenase-2 (COX-2) specific inhibitors are associated with elevations in blood pressure requiring treatment in typical clinical practice. We examined the risk of new onset hypertension in a retrospective case-control study involving 17 844 subjects aged > or =65 years from 2 US states. Multivariable logistic models were examined to assess the relative risk of new onset hypertension requiring treatment in patients who used celecoxib or rofecoxib compared with patients taking either the other COX-2 specific inhibitor, a nonspecific NSAID, or no NSAID. During the 1999 to 2000 study period, 3915 patients were diagnosed and began treatment for hypertension; 4 controls were selected for every case. In no model was celecoxib significantly associated with the development of hypertension. Rofecoxib users were at a significantly increased relative risk of new onset hypertension compared with patients taking celecoxib (odds ratio [OR] 1.6; 95% confidence interval [CI], 1.2 to 2.1), taking a nonspecific NSAID (OR 1.4; 95% CI, 1.1 to 1.9), or taking no NSAID (OR 1.6; 95% CI, 1.3 to 2.0). There were no clear dosage or duration effects. In patients with a history of chronic renal disease, liver disease, or congestive heart failure, the relative risk of new onset hypertension was twice as high in those taking rofecoxib compared with celecoxib (OR 2.1; 95% CI, 1.0 to 4.3). In this retrospective case-control study of patients aged > or =65 years, rofecoxib use was associated with an increased relative risk of new onset hypertension; this was not seen in patients taking celecoxib.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15226279&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Celecoxib, a cyclooxygenase-2 inhibitor, reduces neointimal hyperplasia through inhibition of Akt signaling.

Yang HM, Kim HS, Park KW, You HJ, Jeon SI, Youn SW, Kim SH, Oh BH, Lee MM, Park YB, Walsh K.

Cardiovascular Laboratory, Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.

BACKGROUND: Celecoxib has been shown to have antitumor effects that may be mediated through the cyclooxygenase-independent inhibition of Akt signaling. Here, we examined the effects of celecoxib on neointimal formation after balloon injury and its mechanism of action. METHODS AND RESULTS: In vitro experiments were performed to evaluate the effects of celecoxib on the Akt/GSK signaling axis and the viability of rat vascular smooth muscle cells (VSMCs). In vivo experiments examined the effects of celecoxib, aspirin, and vehicle on neointimal growth after denudation injury to rat carotid arteries. In vitro, celecoxib suppressed the phosphorylation of Akt and GSK in cultured VSMCs, leading to a reduction in viable cell number, which was reversed by transduction of constitutively active Akt. Such a reduction in cell number was mediated by inhibition of proliferation and induction of apoptosis. In vivo, celecoxib reduced injury-induced phosphorylation of Akt and GSK, reduced VSMC proliferation, and increased caspase-3 activation and VSMC apoptosis at 3 days after injury, whereas aspirin had no effect. At 2 weeks after injury, celecoxib reduced intima-to-media ratio, whereas aspirin had no effect. Adenovirus-mediated delivery of dominant negative Akt was as effective as celecoxib at inhibiting neointimal formation. Conversely, gene delivery of constitutively active Akt significantly reversed the inhibition of intimal hyperplasia by celecoxib, providing causal evidence that the modulation of Akt signaling by celecoxib is a physiologically relevant mechanism. CONCLUSIONS: Celecoxib is a potential inhibitor of neointimal formation by blocking injury-induced Akt activation. These findings suggest a potential use for celecoxib in the prevention of restenosis after angioplasty.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15238462&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Eicosanoid metabolism in squamous cell carcinoma cell lines derived from primary and metastatic head and neck cancer and its modulation by celecoxib.

Schroeder CP, Yang P, Newman RA, Lotan R.

Department of Thoracic, Head and Neck Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.

Eicosanoid metabolism through cyclooxygenases (COXs) and lipoxygenases (LOXs) generates various lipids that play a role in squamous cell carcinogenesis. We used pairs of head and neck squamous cell carcinoma (HNSCC) cell lines derived from primary and metastatic tumors of the same patient to analyze eicosanoid metabolites by ESI-LC/MS/MS and COX/LOX expression by western immunoblotting. The effects of celecoxib on eicosanoid synthesis and HNSCC cell growth were examined. Prostaglandin E2 (PGE2) was the major metabolite in three of six cell lines. COX-2 was detected in three cell lines, which produced PGE2 (two from metastases). We found low expression of COX-1 at similar intensities for each pair of cell lines. 5-LOX was detected in all cells. Some expressed 12-LOX, 15-LOX-1, and 15-LOX-2, but there was no correlation between enzyme expression and endogenous product content. Exogenous arachidonic acid did not change the profile of eicosanoid biosynthesis. Low doses of celecoxib inhibited formation of PGE2 in UMSCC-14A cells by 84% as early as 6 hours. In contrast, 5-HETE, 12-HETE, and 15-HETE levels were increased by approximately 40-, 5- and 3-fold, respectively, with a decline to baseline levels within 24 hours. High dose celecoxib increased the 12-HETE level 2.3-fold after 3 days of incubation. Celecoxib inhibited growth of all HNSCC cell lines in a concentration-dependent manner regardless of their COX expression (IC50 values after 3 days; 33 to 62 microM). Our findings provide new informations about individual eicosanoids produced by HNSCC cells and their differential regulation by the selective COX-2 inhibitor celecoxib.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15254428&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Cyclooxygenase (COX)-2 inhibitor celecoxib abrogates activation of cigarette smoke-induced nuclear factor (NF)-kappaB by suppressing activation of IkappaBalpha kinase in human non-small cell lung carcinoma: correlation with suppression of cyclin D1, COX-2, and matrix metalloproteinase-9.

Shishodia S, Aggarwal BB.

Cytokine Research Laboratory, Department of Bioimmunotherapy, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.

Cigarette smoke (CS) has been linked to cardiovascular, pulmonary, and malignant diseases. CS-associated malignancies including cancers of the larynx, oral cavity, and pharynx, esophagus, pancreas, kidney, bladder, and lung; all are known to overexpress the nuclear factor-kappaB (NF-kappaB)-regulated gene products cyclin D1, cyclooxygenase (COX)-2, and matrix metalloprotease-9. Whether the COX-2 inhibitor, celecoxib, approved for the treatment of colon carcinogenesis and rheumatoid arthritis, affects CS-induced NF-kappaB activation is not known, although the role of NF-kappaB in regulation of apoptosis, angiogenesis, carcinogenesis, and inflammation is established. In our study, in which we examined DNA binding of NF-kappaB in human lung adenocarcinoma H1299 cells, we found that cigarette smoke condensate (CSC)-induced NF-kappaB activation was persistent up to 24 h, and celecoxib suppressed CSC-induced NF-kappaB activation. Celecoxib was effective even when administered 12 h after CSC treatment. This effect, however, was not cell type-specific. The activation of inhibitory subunit of NF-kappaB kinase (IkappaB), as examined by immunocomplex kinase assay, IkappaB phosphorylation, and IkappaB degradation was also inhibited. Celecoxib also abrogated CSC-induced p65 phosphorylation and nuclear translocation and NF-kappaB-dependent reporter gene expression. CSC-induced NF-kappaB reporter activity induced by NF-kappaB inducing kinase and IkappaB alpha kinase but not that activated by p65 was also blocked by celecoxib. CSC induced the expression of NF-kappaB-regulated proteins, COX-2, cyclin D1, and matrix metalloproteinase-9, and celecoxib abolished the induction of all three. The COX-2 promoter that is regulated by NF-kappaB was activated by CSC, and celecoxib suppressed its activation. Overall, our results suggest that chemopreventive effects of celecoxib may in part be mediated through suppression of NF-kappaB and NF-kappaB-regulated gene expression, which may contribute to its ability to suppress inflammation, proliferation, and angiogenesis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15256475&dopt=Abstract celecoxib, Celebrex



celecoxib, Celebrex
Cyclooxygenase (COX)-2 inhibitor celecoxib abrogates TNF-induced NF-kappa B activation through inhibition of activation of I kappa B alpha kinase and Akt in human non-small cell lung carcinoma: correlation with suppression of COX-2 synthesis.

Shishodia S, Koul D, Aggarwal BB.

Department of Bioimmunotherapy, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.

The cyclooxygenase 2 (COX-2) inhibitor celecoxib (also called celebrex), approved for the treatment of colon carcinogenesis, rheumatoid arthritis, and other inflammatory diseases, has been shown to induce apoptosis and inhibit angiogenesis. Because NF-kappa B plays a major role in regulation of apoptosis, angiogenesis, carcinogenesis, and inflammation, we postulated that celecoxib modulates NF-kappa B. In the present study, we investigated the effect of this drug on the activation of NF-kappa B by a wide variety of agents. We found that celecoxib suppressed NF-kappa B activation induced by various carcinogens, including TNF, phorbol ester, okadaic acid, LPS, and IL-1 beta. Celecoxib inhibited TNF-induced I kappa B alpha kinase activation, leading to suppression of I kappa B alpha phosphorylation and degradation. Celecoxib suppressed both inducible and constitutive NF-kappa B without cell type specificity. Celecoxib also suppressed p65 phosphorylation and nuclear translocation. Akt activation, which is required for TNF-induced NF-kappa B activation, was also suppressed by this drug. Celecoxib also inhibited the TNF-induced interaction of Akt with I kappa B alpha kinase (IKK). Celecoxib abrogated the NF-kappa B-dependent reporter gene expression activated by TNF, TNF receptor, TNF receptor-associated death domain, TNF receptor-associated factor 2, NF-kappa B-inducing kinase, and IKK, but not that activated by p65. The COX-2 promoter, which is regulated by NF-kappa B, was also inhibited by celecoxib, and this inhibition correlated with suppression of TNF-induced COX-2 expression. Besides NF-kappa B, celecoxib also suppressed TNF-induced JNK, p38 MAPK, and ERK activation. Thus, overall, our results indicate that celecoxib inhibits NF-kappa B activation through inhibition of IKK and Akt activation, leading to down-regulation of synthesis of COX-2 and other genes needed for inflammation, proliferation, and carcinogenesis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15265936&dopt=Abstract celecoxib, Celebrex