Development of Rational Strategy for Selective
COX-2 Inhibitors Searching as Potential Anticancer Drugs
Manivannan SENTHILRAJA*°, Vasyl V. ATAMANYUK**, Roman B. LESYK**, Danylo V. ATAMANYUK**, O. Roman PINYAZHKO**, I.O. NEKTEGAYEV**, Boris S. ZIMENKOVSKY**
Development of Rational Strategy for Selective COX-2 Inhibitors Searching as Potential Anticancer Drugs
Summary
Molecular docking for 145 compounds (4-thiazolidinone derivatives and related heterocyclic systems) has shown in vitro anticancer activity into the active site of enzyme COX-2 using crystallographic models 1CX2 and 6COX (www.rcsb.org). In silico investigations were performed stage- by-stage with OpenEye Scientific Software program package.
As a result selected 20 compounds, that are thiopyrano [2,3- d] thiazole-2-ones, 5-arylidene-4-thioxo-2-thiazolidinone and 2-thioxo-(heteryl, imino or oxo)-4-thiazolidinone derivatives selective COX-2 inhibition with blockage of COX-2 pathway in cancerogenesis, which determines a role of selective COX- 2 inhibitors in prevention and treatment of cancer.
Key Words: 4-thiazolidinones and related heterosystems, COX-2, anticancer activity, OpenEye, molecular docking.
Received: 14.05.2010 Revised: 23.01.2011 Accepted: 30.01.2011
Potansiyel Antikanser İlaçlar Olan Selektif COX-2 İnhibitörlerinin Araştırılması için Rasyonel Strateji Geliştirilmesi
1CX2 ve 6COX (www.rscb.org) kristalografik modelleri Özet kullanılarak, in vitro ortamda antikanser etkinliği gösterilmiş 145 bileşik (4-tiazolidinon türevleri ve ilgili heterosiklik sistemler) için COX-2 enziminin aktif bölgesine moleküler kenetlenme çalışmaları yürütülmüştür. İn siliko araştırmalar OpenEye Scientific Software program paketi ile aşama aşama gerçekleştirilmiştir. Bu çalışmaların sonunda tiyopirano [2,3-d] tiyazol- 2-on’lar, 5-ariliden-4- tiyokso- 2 – tiyazolidinon ve 2-tiyokso-(heteril, imino veya okso) -4- tiyazolidinon türevleri olan 20 bileşik seçilmiş, bu bileşikler, karsinojenezde COX-2 yolağını engelleyerek seçici COX-2 inhibisyonu gösterebileceği bulunmuştur. Bu da, seçici COX- 2 inhibitörlerinin kanserin önlenmesi ve tedavisindeki rolünü
ortaya koymaktadır.
Anahtar Kelimeler: 4-tiyazolidinon’lar ve bunlarla ilgili heterosistemler, COX-2, antikanser aktivite, OpenEye, moleküler kenetlenme.
* JKK Nataraja College of Pharmacy, Salem main road, Komarapalayam, Namakkal, TamilNadu, India
** Danylo Halytsky Lviv National Medical University, Lviv, Ukraine
° Corresponding Author E-mail: rajdanish2k@gmail.com INTRODUCTION
Cyclooxygenase (COX) is an enzyme which is responsible for biochemical transformations of arachidonic acid and synthesis of its metabolites prostanoids including prostaglandins, prostacyclin and thromboxan. Today three isoforms of the enzyme are known – COX-1, COX-2 and COX-3.
COX-3 is defined as the COX-1 analogue bonded with intron, therefore, for the denotation of this isoform abbreviation COX-1b is often used (1-7).
COX-3 is identified in the fabric of brain, however, to the present movement the biological role of this isoform is not exactly identified.
Two isoforms of cyclo-oxygenase (COX), the key enzyme in prostaglandin (PG) and thromboxane (TX) biosynthesis referred to as COX-1 and COX- 2 have been identified. Each enzyme is encoded by a separate gene and has a distinct pattern of expression and biological function. COX-1 is expressed constitutively and high levels can be detected in most tissues. In contrast, levels of COX-2 mRNA and protein are usually low or undetectable under basal conditions but are rapidly elevated during inflammation or mitogenic stimulation.
Selective inibition of COX-2 by non-steroidal anti- inflammatory drugs (NSAIDs) has been proposed as an approach to reduce their associated side effects while maintaining efficacy. The improved safety profile of selective COX-2 inhibitors will allow more widespread and sustained use than is currently possible with standard NSAIDs.
The crystalline structures of COX-1 and COX-2 were obtained in 1994 and 1996 respectively that brought in considerable contribution to the understanding of action and consequences of inhibition of this enzyme (8, 9).COX-1 takes part in adjusting vitally necessary functions, including work of stomach and blood clotting system, controls the production of prostaglandins (PG) that regulate the integrity of mucus membrane of gastro intestinal tract, function of thrombocytes , kidney and circulation of blood (10- 14). In spite of that this isoform is constitutional; its expression can be stimulated by violations of integrity of the nervous fibers (15-18). Isoenzyme COX-2 takes part in the origin of pain and inflammation, synthesis of PG within the inflammation, the Р-glycoprotein activation (transporting protein responsible for the development of the multidrug resistance) (19-25). In addition, in kidney and nervous tissue too there is a constitutional expression of mentioned isoform (26, 27). Constitutional COX-2 has an important role in spinal cord, particularly synthesis of PGE2 that leads to hyperalgesia (28).
Ghilardi et al29 assumes that blocking of the spinal COX- 2 can result in the decline of sensitiveness (centers and periphery) that leads to the certain damages. COX-2 plays an important role in proliferation of cells30-37. The results of numerous researches testify to its overexpression
within the non-small linear lung cancer, esophagus and colon adenocarcinomas and beginning from the early stages of cancer in 80-90% of the patients 38-47. An early expression of COX-2 is observed during oncogenesis of major cancer types: lung, breast, prostate, and colon (malignant) tumors.
During oncogenesis of the thyroid gland tumors COX-2 expression is marked that is accompanied by the high level PG, especially PGG2, an increase in the level of matrix metalloproteinase-2 (MMP-2).It has an important value for metastatic potential of these tumors. An increase in the COX-2 and ММР-2 levels in tumors depends on the age of patients that predetermines more aggressive development of malignant tumors of thyroid gland at the patients of senior age comparative with the youths (48-53).Similar situation is characteristic for the Khashimoto illness , follicle cancer and adenoma, medullary carcinoma, and adenoma from Gurtle celles . From the data of literature the special attention is spared to the colon cancer that by the conditioned trained mechanisms of the COX-2 action in oncogenesis, namely by activating of the PPARγ receptors and antiapoptotic gene Bcl-xL (increasing of level of anti- apoptotic protein Bcl-2) by PGE2 .
Both, COX-1 and COX-2 use arachidonic acid for the synthesis of PGH2, which is afterwards modified with the formation of bioactive lipids–prostanoids that include prostacyclin, thromboxane A2 and PGD2, E2 and F2 (Fig.
1) which have an influence on immune, cardiovascular, gastrointestinal, renovascular, respiratory systems, CNS and the reproductive functions .
Non-selective inhibition of COX with drugs such as aspirin, ibuprofen, indomethacin and naproxene that supress both the COX-1 and COX-2 enzymes which provides effective diminishment of pain syndrome at inflammation, however, at the same time it carries the risk of origin of erosive gastritis and gastrointestinal bleeding.
Selective inhibitors of COX-2 (Celecoxib, Ethoricoxib, Rofecoxib, Valdecoxib, Meloxicam) (Fig. 2) and other derivatives which are in the process of development were created with the purpose of minimization of toxic influence on a gastrointestinal tract that is conditioned by the relatively small expression of COX-2 in a gastrointestinal tract and considerable
Figure 1. COX-pathway of biochemical transformations of arachidonic acid.
Figure 2. Modern selective COX-2 inhibitors.
Phospholipids
Arachidonic acid
PGG2 (Prostaglandin G2)
Thromboxansynthase PGH2 Prostacyclinsynthase
Tromboxan A2
Isomerase
Reductase PGF2
Prostacyclin (PGI2)
PGE2 PGD2
Phospholipase A2
COX-Reaction
Cyclooxygenase Peroxydase-reaction
O N C H3
S NH2 O
O
S CH3 O
O O
O
NN S
NH2
O O F
F F
CH3
S CH3 O
O N
Cl
N C H3
S N OH
O O NH O
S N CH3
Rofecoxib Celecoxib Etoricoxib Meloxicam
Valdecoxib
in the inflammed fabrics and at all afore-mentioned pathological processes (cancer and multidrug resistance) (54-55).
Harris et al. (56) conducted the epidemiological research of influencing of non-steroidal anti- inflammatory drugs on the risk of origin of colon cancer, breast cancer, lung cancer and prostate cancer.
It was found that in a result of in taking 200 mg of Celecoxib or 25 mg of Rofecoxib daily during two years and more is observed high level of prophylaxis of these types of cancer (Fig. 3). 4-thiazolidinone derivatives are one of the perspective classes of heterocyclic compounds as potential selective COX- 2 inhibitors (Fig. 4). The aim of the research is to perform a molecular docking of some determined 4-thiazolidinone derivatives into COX-2 active site for the purposeful searching of COX-2 inhibitors as potential anticancer agents.
MATERIALS AND METHODS
Research is performed by the method of molecular docking as computer approach to the search of molecules with affinity to the certain biotargets.
Docking studies (57)were conducted with OpenEye Scientific Software program package that include Fred Receptor, Vida, Flipper, Babel3, Omega2 and Fred2. Chrystallographic models of COX-2 were obtained from Protein Data Bank (www.rcsb.org) particularly models 6COX (COX-2 in complex with selective inhibitor SC-558 at a resolution of 2,8 Å) and 1CX2 (COX-2 in complex with selective inhibitor SC- 558 at a resolution of 3,0 Å). Binding space groups are the differential parts of these crystallographic models (different conformations) (Fig. 5). In Figure 5 one can see images of A chains of COX-2 crystallographic models 1CX2 (chains A, B, C, D) and 6COX (and A, B) with ligands such as selective COX-2 inhibitor SC- 558, protoporphyrin IX (contain Fe) and N-acetyl- D-glucosamine. According to the literature data crystallographic models 1CX2 and 6COX are the space groups P 21 21 2 and I 2 2 2, respectively (58).
The resulted information testifies the difference of conformations of enzymes and consequently about the structural difference of binding sites that exert an influence on ligand-receptor interactions (59). It is, therefore, expedient to use both crystallographic models of COX-2 in docking researches.
As research objects were the selected 145 compounds, 4-thiazolidinone derivatives synthesized in the Figure 3. Celecoxib and rofecoxib in the prophylaxis
of certain types of cancer.
Figure 4. Selective COX-2 inhibitors from group of 4-thiazolidininones.
S N NH2
O O
H
CH3
C H3
CH3 C
H3 CH3 C
H3 S NH
O N O
CH3 O
H
CH3 C H3
CH3
C H3
CH3 C H3
S N
O
C O
H3 N
O S
O CH3 S
N O
N O S C O
H3
O CH3 O
CH3
O C H3
N S F
S O O
CH3 O
S N O
N CH3 O
C H3
CI-1004 PD 138387
Maguire et al. J. Med. Chem. 1999, 42, 1151-1160 32 Ottana et al. BMC 13 (2005) 4243–4252 43
Vigorita et al. BMC 11 (2003) 999-1006 4 Ottana et al. Eur. J. Pharm. 448 (2002) 71– 80 44 Afshin Zarghi et al. BMC Lett 17 (2007) 5634-5637 76
VIG3b
Maguire et al. J. Med. Chem. 1999, 42, 1151-1160 32
Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University that has shown in vitro anticancer activity and known selective COX-2 inhibitors such as Celecoxib, Etoricoxib, Rofecoxib, Valdecoxib, Meloxicam and non-selective inhibitor Aspirinum.
RESULTS AND DISCUSSION
Obtained seven scoring function values (Chemgauss2, Chemscore, PLP, Screenscore, Shapegauss, Zapbind and Consenses) were used for in silico estimation of COX-2- compound binding. Consensus (cumulative) scoring function ranking allowed us to select 20 compounds, which can prospectively be selective COX-2 inhibitors at the level of celecoxib for future
(in-depth) pharmacological studies as well as could be used as templetes for the synthesis of various related analogues.
With the help of Fred receptor, the active site (biotarget) of COX-2 was obtained from each crystallographic model for performing molecular docking. Molecular docking studies include stages such as:
1. Generating R-, S- and cys-trans isomers of ligands using program Flipper and Obtained 461 isomers of studied compounds.
2. 3D optimization of isomers using program Hyper Chem 7.5 (www.hyper.com) (molecular mechanics method MM+ and semi-empirical
NN S
NH2 O O F
F F
Br
SC-558
Figure 5. Fig. 5. Graphic images of A chains of COX-2 crystallographic models 1CX2 and 6COX with ligands such as selective COX-2 inhibitor SC-558, protoporphyrin IX (contain Fe), N-acetyl-D-glucosamine.
6COX (space group - I 2 2 2)
quantum-mechanical method PM3).
3. Conformers generating (Omega2). Further program Fred2 will choose minimum energy conformation for each molecule.
3D molecular docking (Fred2). In a result obtained meaning of seven scoring functions (Chemgauss2, Chemscore, PLP, Screenscore, Shapegauss, Zapbind ta Consensus). Consensus scoring function was selected to analyze the results because of its property
to result in ranking (compound ranking) that include the means of all scoring functions.
Analysis and ranking of the molecular docking results obtained using the selected compounds and two crystallographic models of COX-2 (6COX and 1CX2) with cumulative scoring function (consensus) allowed to select 20 compounds from 4-thiazolidinone group (Fig. 6 and 7) which probably exhibit selective inhibition of COX-2 on level of Celecoxib.
Figure 6. Structural formulas of potential COX-2 inhibitors obtained with molecular docking (crystallographic model 1CX2).
Figure 7. Structural formulas of potential COX-2 inhibitors obtained with molecular docking (crystallographic model 6COX).
S N S O
O
O OEt
NH N S Cl
O O
N
H S
S C O H3
O
N S
O O NH
N O S
N S
CH2
N OH
O Cl
NH O S
Cl
N+O O
O
S S N
O
N N
S
CH2
O H
S N
NH S N O O
C H3
O H
NH S S
O
O
O OH
O
CH3 N
S O
S
N O O
Cl
Les-942 Les-3390 Les-1520
Les-1204
Les-1312
Les-1005 Les-1616
Les-3440
Les-3034
Les-1396
N
S N
CH2
OH N O
H O
NH S O S Cl Cl
O
S N O
O NH
O
OH
NH S O O
N N NH O
NH S S
O N+
O O
O C
H3
NH S O
O N
OH Cl
N O
H N
S O
CH3 Cl
N+ O
O N
S O O
H EtO
NH
OH
S N O
O NH
O
F Et
Les-1009 Les-400
Les-1528 Les-429
Les-1640
Les-1353
Les-1563 Les-1592 Les-285
Below are shown an interactions between COX-2 active site and two “hit compounds” (Les-942 and Les-1009) (Fig. 8 and 9) selected in a result of docking results analysis. Data visualized with VIDA (Open Eye Scientific Software). Compound Les-942 and Compound Les-1009 docked in the active site of COX-2 in comparison with the selective inhibitor SC-558. This will enable the compounds to interact strongly on the selective targets.
CONCLUSION
Preliminary docking studies of in-house library could be considered as a first stage of long term project dedicated to rational design of COX-2-inhibitors among thiazolidinone-based compounds. Adapted elements of rational methods for searching selective inhibitors of COX-2 as potential anticancer drugs on the basis of molecular docking that allows to predict affinity of some compounds to its certain biotarget.
Figure 8. Compound Les-942 docked in the active site of COX-2 (a) in comparison with selective inhibitor SC-558 (b) (crystallographic model 1CX2).
Figure 9. Compound Les-1009 docked in the active site of COX-2 (a) in comparison with selective inhibitor SC-558 (b) (crystallographic model 6COX).
S N O S
O
O OEt
N S N
CH2 OH O
NH O
Based on the affinity studies, the compound Les-942 and compound Les-1009 docked in the active site of COX-2 in comparison with the selective inhibitor SC-558. As a result, this will allow the compounds to interact strongly on the selective targets & exerts the favorable results. Molecular docking for 145 compounds (4-thiazolidinone derivatives and related heterocyclic systems) that has shown in vitro anticancer activity into the active site of enzyme COX-2 using crystallographic models 1CX2 and 6COX. In silico investigations were performed stage- by-stage with OpenEye Scientific Software program package. As a result, 20 compounds were thiopyrano [2,3-d] thiazole-2-ones, 5-arylidene-4-thioxo-2- thiazolidinone and 2-thioxo-(heteryl, imino or oxo)-4-thiazolidinone derivatives that can show the selective COX-2 inhibition with blockage of COX- 2 pathway in cancerogenesis, which determines the role of selective COX-2 inhibitors in prevention and treatment of cancer. Consecuetly, molecular docking of 20 derivatives of 4-thiazolidinone that exhibit anticancer activity were selected for further investigations of this compound as selective COX-2 inhibitors.
ACKNOWLEDGEMENT
The authors would like to thank Department of Science & Technology, Govt.of India & Ministry of Education and Science of Ukraine in the context of international Indian-Ukrainian project “Rational
usage as anticancer drugs” according to contract M272-2008 from 19.05.2008 between department of science & technology of India & Ministry of Education and Science of Ukraine and Danylo Halytsky Lviv National Medical University. We would like to thank Mrs. Burceva M. I., worker of the Department of international cooperation and European integration (Ministry of Education and Science of Ukraine), for assistance and consultations in realization of project.
REFERENCES
1. Catella-Lawson F, Reilly M P., Kapoor S. C.
Cyclooxigenase inhibitors and the antiplatelet effects of aspirin. N. Engl. J. Med 345: 1809-1817, 2002.
2. Hida T, Yatabe Y, Achiwa H. Increased expression of cyclooxygenase-2 occurs frequently in human lung cancers, specifically in adenocarcinomas. Cancer Res.
58: 3761-3764, 1998.
3. Kang H, Lee E, Pyo H. Cyclooxygenase-independent down-regulation of multidrug resistance–associated protein-1 expression by celecoxib in human lung cancer cells. Mol. Cancer Ther 4:1358-1363, 2005.
4. Smith WL, Willis AL. Aspirin selectively inhibits prostaglandin production in human platelets. Nature 231:235–239, 1971.
5. Sorokin A. Cyclooxygenase-2: potential role in regulation of drug efflux and multidrug resistance phenotype. Curr. Pharm. Des 10: 647-657,2004.
6. Vane JR. Inhibition of Prostaglandin Synthesis as a.
Mechanism of Action for Aspirin-Like Drugs. Nature 231:232–235, 1971.
7. Adegboyega PA, Ololade O, Saada. Subepithelial myofibroblasts express cyclooxygenase-2 in colorectal tubular adenomas. J. Clin. Cancer Res 10:
5870-5879, 2004.
8. Eberhart CE, Coffey RJ, Radhika A. Up-regulation of cyclooxygenase 2 gene expression in human colorectal adenomas and adenocarci nomas. Gastroenterology 107:1183-1188, 1994.
9. Kurumbail RG, Stevens AM, Gierse JK. Structural basis for selective inhibition of cyclooxygenase-2 by anti-inflammatory agents. Nature 384:644-648,1996.
10. Zhang L, Yu J, Park BH, Kinzler KW. Role of BAX in the apoptotic response to anticancer agents. Science 290: 989-996,2000.
11. Araki M, Shigemitsu T, Sasao T. Various problems on model
1 Les-942 Les-1009
2 Les-3390 Les-400
3 Les1520 Les-1528
4 Les-1204 Les-942
5 Les-1312 Les-429
6 Les-1005 Les-1640
7 Les-1616 Les-1353
8 Les-3440 Les-1563
9 Les-3034 Les-1616
10 Les-1396 Les-1592
Table 1. Rating of 4-thiazolidinone derivatives based on binding quality of compounds with COX-2 active site (crystallographic models 1CX2 and 6COX)
subacute thyroiditis. Saishin Igak 24:1710-1715,1969.
12. Charlier C, Michaux C. Dual inhibition of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) as a new strategy to provide safer non- steroidal anti-inflammatory drugs. European Journal of Medicinal Chemistry 38 (7-8), 645 – 659, 2003.
13. Dannhardt G, Kiefer W. Cyclooxygenase inhibitors – current status and future prospects. Eur J Med Chem 36:109–126,2001.
14. Davydova J, Le LP, Gavrikova T. Infectivity-enhanced cyclooxygenase-2-based conditionally replicative adenoviruses for esophageal adenocarci noma treatment. Cancer Res 6: 4319-4327, 2004.
15. Dempke W, Rie C, Grothey A. Cyclooxygenase-2:
a novel target for cancer chemotherapy? J Cancer Res Clin Oncol 127: 411-417,2001.
16. Ferrandina G, Ranelletti FO, Legge F. Prognostic role of the ratio between cyclooxygenase-2 in tumor and stroma compartments in cervical cancer. Clin.
Cancer Res 10:3117-3123,2004.
17. Gaurel A, Martel AM. Castaner J. Celecoxib, anti- inflammatory, cyclooxygenase-2 inhibitor. Drugs Future 22: 711-714, 1997.
18. Geronikaki AA, Lagunin AA, Hadjipavlou- Litina DI. Computer-Aided Discovery of Anti- Inflammatory Thiazolidinones with Dual Cyclooxygenase/Lipoxygenase Inhibition. J Med Chem 51(6): 1601–1609.
19. Gupta RA, Dubois RN. Colorectal cancer prevention and treatment by inhibition of cyclooxygenase-2. Nat Rev Cancer 1:11-15, 2001.
20. Hao X, Bishop AE, Wallace M. Early ex pression of cyclooxygenase-2 during sporadic colorectal carcino genesis. J Pathol 187:295-301, 1999.
21. Hartner A, Pahl A, Brune K. Upregulation of cyclooxygenase-1 and the PGE2 receptor EP2 in rat and human mesangioproliferative glomerulonephritis. Inflamm. Res 49:345–354,2000.
22. Hawkey C. J. COX-2 inhitors. The Lancet 353:307-314,1999.
23. Jouzeau JY, Terlain B, Abid A. Cyclooxygenase isoenzymes. How recent findings affect thinking about nonsteroidal anti-inflammatory drugs.
Drugs 53:563-582,1997.
24. Kim SJ, Lee JH, Yoon JS. Immunohis-tochemical expression of COX-2 in thyroid nodules. Korean J In tern Med 18:225-229,2003.
25. Koga H, SaMsaka S, Ohishi M. Expression of cyclooxygenase-2 in human hepatocellular carcinoma: relevance to tumor dedifferentiation.
Hepatology 29:688-696,1999.
26. Kujubu DA, Fletcher BS, Varnum BC. TIS10, a phorbol ester tumor promoter-inducible mRNA from Swiss 3T3 cells, encodes a novel prostaglandin synthase/cyclooxygenase homologue. J Biol Chem 266:12866–12872,1991.
27. Kumagai H, Mukaisho K, Sugihara H.
Thioproline inhibits development of esophageal adenocarcinoma induced by gastroduodenal reflux in rats. Carcinogenesis 25:723-727,2004.
28. Lehmann JM, Lenhard JM, Oliver BB. Peroxisome proliferator-activated receptors alpha and gamma are activated by indomethacin and other non-steroidal anti-inflammatory drugs. J Biol Chem 272:3406-3411,1997.
29. Ghilardi JR, Svensson CI, Rogers SD. Constitutive spinal cyclooxygenase-2 participates in the initiation of tissue injury-induced hyperalgesia. J Neurosci 24:2727–2732,2004.
30. Li Z, Shimada Y. KawabeA. Suppression of N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in F344 rats by JTE- 522, a selective COX-2 inhibitor. Carcinogenesis .22:547-551,2001.
31. Liu CH, Chang SH, Narko K, Trifan OC.
Overexpression of cyclooxygenase-2 is sufficient to induce tumorigenesis in transgenic mice. J Biol Chem 276:18563-18569,2001.
32. Maguire AR, Plunkett SJ, Papot S. Synthesis of Indomethacin analogues for evaluation as modulators of MRP activity. Bioorg Med Chem 9:
745-762,2001.
33. Maguire AR, Plunkett SJ, Papot S. Synthesis, Structure−Activity Relationships, and in Vivo Evaluations of Substituted Di-tert-butylphenols as a Novel Class of Potent, Selective, and Orally Active Cyclooxygenase-2 Inhibitors. 1.
Thiazolone and Oxazolone Series. J Med Chem 42(7):1151-1160,1999.
34. Marnett LJ, DuBois RN, AB. Hancock Jr. COX-2:
a target for colon cancer prevention. Annu Rev Pharmacol Toxicol 42:55-80,2002.
35. Meric JB, Rottey S, Olaussen K. Cyclooxygenase-2 as a target for anticancer drug development. Crit Rev Oncol Hepatol 59:51-64,2006.
36. Miller B, Patel V, Sorokin A. COX-2 rescues rat mesangial cells from apoptosis induced by adriamycin via upregulation of MDR1 (P-glycoprotein).J Am Soc Nephrol 17:977-985,2006.
37. Morteau O. Prostaglandins and inflammation:
the cyclooxygenase controversy.Arch. Immunol.
Ther. Exp 48:473–480, 2000.
38. Mozziconacci J, Arnoult E, Bernard P. Virtual Screening for COX-2 Inhibitors. J Med Chem 48:1055-1068, 2005.
39. Murata H., Kawano S., Tsuji S. Cyclooxygenase-2 overexpression enhances lymphatic invasion and metastasis in human gastric carcinoma. Am J Gastroenterol 94:451-455, 1999.
40. O’Banion MK. Cyclooxygenase-2: molecular biology, pharmacology, and neurobiology. Crit Rev Neurobiol 13:45–82, 1999.
41. O’Banion MK, Sadows HB, Winn V. A serum- and glucocorticoid-regulated 4-kilobase mRNA encodes acyclooxygenase-related protein. J Biol Chem 266:23261-23267, 1991.
42. Ottana R, Maccari R, Barreca M. 5-Arylidene-2- imino-4-thiazolidinones: Design and synthesis of novel anti-inflammatory agents. Bioorganic &
Medicinal Chemistry 13:4243–4252, 2005.
43. Ottana´ R, Mazzon E, Dugo L. Modeling and biological evaluation of 3, 3’-(1, 2-ethanediyl) bis [2-(4-methoxyphenyl)-thiazolidin-4-one], a new synthetic cyclooxygenase-2 inhibitor. European Journal of Pharmacology 448: 71– 80, 2002.
44. Patel VA, MJ, Dunn A. Sorokin Regulation of MDR-1 (P-glycoprotein) by Cyclooxygenase-2.J Biol Chem 277: 38915-38920, 2002.
45. Pommery N, Taverne T, Telliez A. New COX- 2/5-LOX inhibitors: apoptosis-inducing agents potentially useful in prostate cancer chemotherapy. J Med Chem 47:6195–6206,2004.
46. Puxeddu E, Mitsutake N. Knauf JA. Microsomal prostaglandin E2 synthase-1 is induced by con- ditional expression of RET/PTC in thyroid PCCL3 cells through the activation of the MEK- ERK pathway. J Biol Chem 278:52131-52138,2003.
47. Quidville V, Segond N. Pidoux E. Tumor growth inhibition by indomethacin in a mouse model of human medullary thyroid cancer: implication of cyclooxygenases and 15-hydroxyprostaglandin dehydrogenase. Endocrinology 145:2561-2571, 2004.
48. Richard M. Peek Jr. Prevention of colorectal cancer through the use of COX-2 selective inhibitors.
Cancer Chemother Pharmacol 54(1):S50–S56,2004.
49. Samad TA, Sapirstein A, Woolf CJ. Prostanoids and pain: unraveling mechanisms and revealing ther apeutic targets. Trends Mol Med 8:390–396, 2002.
50. Sarkar HF, Adsule S, Li Y. Back to the Future:
COX-2 Inhibitors for Chemoprevention and Cancer Therapy. Mini-Reviews in Medicinal Chemistry. –7:599-608,2007.
51. Schaefer M, Hofmann T, Schultz G, Gudemann T. A new prostaglandin E receptor mediates calcium influx and acrosome reaction in human spermatozoa. Proc Natl Acad Sci 95:3008-3013,1998.
52. Schulz-Gasch T, Stahl M. Binding site characteristics in structure-based virtual screening: evaluation of current docking tools. J Mol Model 9 :47–57,2003.
53. Scott G, Leopardi S, Printup S. Proteinase-activated receptor-2 stimulates pros taglandin production in keratinocytes: analysis of prostaglandin receptors on human melanocytes and effects of PGE2 and PGF2alpha on melanocyte dendricity. J Invest Dermatol 122:1214-1224,2004.
54. Sellers RS, Silverman L, Khan KN. Cyclooxygenase-2 expression in the cornea of dogs with keratitis. Vet Patho 41:116-121,2004.
55. Shono T, Tofflon PJ, Bruner JM. Cyclooxygenase-2 expression in human gliomas: prognos tic significance and molecular correlations. Cancer Res 61:4375-4381,2001.
56. Harris RE, Beebe-Donk J, Alshafie GA.Cancer chemoprevention by cyclooxygenase-2 (COX- 2) blockade. Inflammation in the Pathogenesis of Chronic Diseases 193–212,2007.
57. McGann M R, Almond HR, Nicholls A. Gaussian Docking Functions. Biopolymers 68:76–90, 2003.
58. Schwab JM, Brechtel K, Nguyen TD. Persistent accumulation of cyclooxygenase-1 (COX- 1) expressing microglia/macrophages and upregulation by endothelium following spinal cord injury. J Neuroimmunol 111:122–130,2000.
59. Schulz-Gasch T, Stahl M. Scoring functions for protein–ligand interactions: a critical perspective .Drug Discovery Today: Technologies 1(3):231-239,2004.
