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Annals of Surgical Oncology 8:458-465 (2001)
© 2001 Society of Surgical Oncology

ORIGINAL ARTICLES

Association of Enhanced Cyclooxygenase-2 Expression With Possible Local Immunosuppression in Human Colorectal Carcinomas

Masayuki Kojima, MD, Takashi Morisaki, MD, Akihiko Uchiyama, MD, Fukashi Doi, MD, Ryuichi Mibu, MD, Mitsuo Katano, MD and Masao Tanaka, MD

From the Departments of Surgery and Oncology (MKo, AU, FD, RM, MT), and Cancer Therapy and Research (TM, MKa), Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.

Correspondence: Address correspondence and reprint requests to: Masayuki Kojima, MD, Department of Molecular Therapeutics, John Wayne Cancer Institute, 2200 Santa Monica Boulevard, Santa Monica, CA 90404; Fax: 310-979-5529; E-mail: kojimam{at}jwci.org


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Background: Prostaglandin (PG) E2 has an influence on antitumor lymphocyte reactions and causes local immunosuppression at tumor sites. The contribution of cyclooxygenase (COX), a key enzyme in PGE2 synthesis, to this effect is still unclear. We examined if cyclooxygenase (COX)-2 is involved in local immunosuppression in human colon carcinoma cell lines and in clinical tumor specimens.

Methods: PGE2 concentrations were measured in culture media from a highly COX-2-expressing human colon carcinoma cell line (CE-1) and other cell lines. Lymphocyte proliferation in response to a mitogen was used to evaluate immunosuppression in tumor cell-lymphocyte cocultures with and without selective COX-2 inhibitor NS-398. We also evaluated expression of COX-2 mRNA in surgical specimens of colorectal carcinoma by reverse transcription polymerase chain reaction (RT-PCR) and COX-2 protein by immunohistochemistry, correlating COX-2 expression with clinicopathologic features.

Results: CE-1 cells produced large amounts of PGE2, which was significantly inhibited by NS-398. The proliferation index of lymphocytes cocultured with CE-1 cells was significantly less than that of control lymphocytes; again, this effect was inhibited by NS-398. While human colorectal carcinoma tissue expressed more COX-2 mRNA and protein than nonneoplastic tissue, no significant correlation was found between COX-2 levels and clinicopathologic features.

Conclusions: Overexpression of COX-2 in colon cancer may cause local immunosuppression, and COX-2 inhibitors might be therapeutically useful against these tumors.

Key Words: Colorectal carcinoma • COX-2 • PGE2 • Immunosuppression • RT-PCR


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Several epidemiologic studies have suggested that nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, reduce mortality from colorectal carcinoma.1–3 Administration of sulindac, another NSAID, reduced the size and number of adenomas in patients with familial adenomatous polyposis.4,5 Several animal studies have suggested that NSAIDs, including indomethacin, sulindac, and piroxicam, exhibit chemopreventive effects against chemically induced colon carcinogenesis.6–8 How NSAIDs reduce the risk of colorectal carcinoma, however, is not clearly understood. One possible mechanism is that NSAIDs inhibit the activity of cyclooxygenase (COX) enzymes, thereby reducing levels of prostaglandins (PGs).9–12

COX is present as two isozymes, constitutive COX-1 and inducible COX-2. COX-1 exists in most tissues and is involved in physiologic production of PGs as part of normal homeostasis.13–15 COX-2 is induced in response to such inflammatory stimuli as mitogens, cytokines, and growth factors.16–18 Elevated levels of COX-2 have recently been described in colorectal carcinoma tissue.19–21 COX-2 overexpression may not only induce colon carcinogenesis but may also alter the biologic behavior of tumor cells.22–24

Previous studies have suggested that PGs may play a role in development of colon carcinoma by showing that tumor cells and tumor-related macrophages produce more PGs than normal cells.25,26 PGE2, a product of a COX-mediated pathway, has been shown to inhibit apoptosis in colon carcinoma cells.27 Furthermore, PGE2 is a potent inhibitor of normal T-lymphocyte proliferation.28 Thus, PGE2 may be a critical factor in enabling colon carcinoma cells to escape host immune defenses. Although recent studies have shown that COX-2 also regulates tumor metastasis and angiogenesis in colon carcinoma,29,30 few reports have suggested a direct immunosuppressive action of COX-2 in colon carcinoma.

In the present study, we investigated the involvement of COX-2 in local immunosuppression, using the human colon carcinoma cell lines. We then evaluated COX-2 mRNA expression in surgical specimens of colorectal carcinoma by reverse transcription polymerase chain reaction (RT-PCR) and COX-2 protein by immunohistochemistry, seeking correlations between COX-2 expression and clinicopathologic features.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Tumor Cells
The human colon adenocarcinoma CE-1 cell line was established in our laboratory from a surgical specimen31 (moderately differentiated adenocarcinoma of the descending colon, pT4pN2pM0 stage III according to the TNM classification32). Two other human colon carcinoma cell lines (DLD-1 and WiDr) were obtained from the American Type Culture Collection (Rockville, MD). These cells were maintained in RPMI-1640 medium (Sanko Pure Chemicals, Tokyo, Japan) supplemented with 10% fetal bovine serum (FBS) (Filtron Pty Ltd., Australia) and antibiotics (100 U/ml penicillin and 100 mg/ml streptomycin) at 37°C.

Reagent
NS-398 was a selective COX-2 inhibitor and supplied by Calbiochem (La Jolla, CA). Phytohemagglutinin (PHA) was purchased from Sigma Chemical Company (St. Louis, MO).

Clinical Samples
Fifty-seven colon cancer patients were studied (Table 1). We obtained informed consent from all patients before including them in the study. Both carcinoma and noncarcinoma tissue samples were obtained from the surgical specimens. Tissue samples from each site were either fixed by immersion in neutral-buffered formalin (Mildform, Wako Pure Chemical Industries, Osaka, Japan) for histologic examination and immunolabeling studies or rapidly frozen and stored at -80°C for RT-PCR analysis of COX-2 mRNA.


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  		TABLE 1. Clinical and pathologic features of colorectal cancer patients
 
Measurement of PGE2
Tumor cells or normal lymphocytes were seeded in 24-well plates (5x105/well) and incubated in RPMI with 2% FBS for 24 hours, after which the culture supernatant was collected to measure PGE2 concentration using monoclonal antibody in an enzyme-linked immunosorbent assay (ELISA) kit as specified by the manufacturer (Cayman Chemical, Ann Arbor, MI). The limit of sensitivity for detection of PGE2 was 10 pg/ml. In some wells, NS-398 was added to inhibit COX-2 activity.

Lymphocyte Proliferation Assay
Blood was obtained from normal human volunteers by venipuncture. Peripheral blood mononuclear cells were isolated and allowed to adhere to a tissue culture flask for a minimum of 3 hours at 37°C. Nonadherent cells were harvested and used for subsequent assays as normal lymphocytes. Lymphocytes (5x105 cells/well) were cocultured for 48 hours with or without tumor cells (5x105 cells/well) in 24-well culture plates. Cell populations were separated using Intercell (pore size, 0.45 mm; Kurabo, Osaka, Japan). After the lymphocytes were isolated, phytohemagglutinin (PHA)-induced proliferation was measured using a [3H]-thymidine incorporation assay. The assay was performed in a plate with 96 round-bottom wells. Lymphocytes (1x105 cells) were seeded in triplicate in a final volume of 200 ml of complete medium with PHA (0.5 mg/ml). Plates were incubated at 37°C in a humidified atmosphere containing 5% CO2 in air for 60 hours before addition of a radioactive thymidine label. After [3H]-thymidine incorporation for 12 hours, the cells were trapped on glass fiber filter paper with a cell harvester (LKB Wallac, Turku, Finland) by vacuum filtration, and radioactivity was measured in a scintillation counter (LKB Wallac). Cell proliferation analyses were performed in triplicate.

RT-PCR and Semiquantitative Measurement
Total RNA was extracted from tissue samples using the guanidinium thiocyanate phenol extraction method described previously.33 Total RNA (1 mg) was converted to cDNA with Superscript II (Life Technologies, Inc., Rockville, MD) with random hexamers (Life Technologies, Inc.). To assess the amount of COX-2-specific mRNA, PCR was performed for COX-2 and for a constitutively expressed housekeeping gene coding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Oligonucleotide primers for COX-2 were 5'-TTC AAA TGA GAT TGT GGG AAA AT-3' (sense) and 5'-AGA TCA TCT CTG CCT GAG TAT CTT-3' (antisense). Those for GAPDH were 5'-CCA CCC ATG GCA AAT TCC ATG GCA-3' (sense) and 5'-TCT AGA CGG CAG GTC AGG TCC ACC-3' (antisense).34 PCR products were separated by electrophoresis on 1.5% agarose gels and stained with ethidium bromide. For quantitation, photographs of gels were scanned with a ScanJet 4C/T (Hewlett Packard, San Diego, CA), and densitometry was performed using the NIH Image program 1.60 (NIH Division of Computer Research and Technology, Bethesda, MD) on a Macintosh personal computer (Apple Computer, Inc., Cupertino, CA). COX-2 mRNA expression was expressed relative to corresponding GAPDH mRNA expression.

Immunohistochemistry
Tissue samples were fixed in 10% neutral-buffered formalin, embedded in paraffin, sectioned at a 4- to 5-mm thickness, and deparaffinized. Slides were immersed first in 0.3% hydrogen peroxidase for 30 minutes and then in normal goat serum (1.5%) for 20 minutes to block endogenous peroxidase activity and nonspecific binding sites, respectively. Immunostaining was performed with a rabbit polyclonal IgG specific for COX-2 (Cayman Chemical) at a dilution of 1:500 at 37°C for 1 hour. Sections were treated with biotinylated secondary antibodies at a dilution of 1:200 (Nichirei Co., Ltd., Tokyo, Japan), and antibody-binding sites were visualized by avidin-biotin peroxidase complex solution and 3,3'-diaminobenzidine (Wako Pure Chemical Industries, Ltd.).

Statistical Analysis
Results are expressed as the mean ± standard error (SE). Statistical significance was examined by Student’s t-test, one-factor ANOVA, and {chi}2 test, with P < .05 considered significant.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Effect of COX-2 Inhibitor on PGE2 Production and Immunosuppression by Colon Carcinoma Cells
PGE2 is a highly potent immunosuppressive factor. Since CE-1 was an established cell line showing high COX-2 mRNA expression, we first examined the amounts of PGE2 produced by CE-1 cells and compared them with normal lymphocytes or other colon carcinoma cell lines, DLD-1 and WiDr. In vitro study revealed that CE-1 cells produced high amounts of PGE2 (855.0 ± 86.1 pg/ml) (Fig. 1A). The PGE2 amounts of lymphocytes and DLD-1 were less than the limit of sensitivity for detection. WiDr produced small amounts of PGE2 (143.1 ± 5.6 pg/ml). The expression of COX-2 mRNA correlated with PGE2 production (Fig. 1B). We also examined the effect of the selective COX-2 inhibitor (NS-398) in concentrations ranging from 0.1–10 mM. Ten mM of NS-398 significantly inhibited the PGE2 production of CE-1 (92.0 ± 4.1 pg/ml, P < .0001) (Fig. 2). NS-398 did not affect the PGE2 production of other cells (data not shown). Next, to examine the immunosuppressive effect of the products of the tumor cell lines, lymphocyte proliferation assay was performed using [3H]-thymidine. Normal lymphocytes and tumor cells were cocultured for 48 hours in the presence or absence of COX-2 inhibitor. Lymphocytes then were collected and the PHA-stimulated proliferation response was assessed. The PHA-stimulation index of lymphocytes cocultured with CE-1 was significantly less than that of control lymphocytes (P < .005). NS-398 (10 mM) inhibited the suppressive effect of CE-1 cells on the PHA-stimulated lymphocyte proliferation (Fig. 3). NS-398 did not influence lymphocytes to proliferate independently. The supernatants from other cell lines and other NS-398-treated cell lines had no effect on the PHA index. To evaluate the immunosuppression of PGE2 produced by CE-1, we assessed titration of the effects of the CE-1 supernatants (Fig. 4). Inhibition of the PHA-stimulated lymphocyte proliferation was dependent on concentration of the supernatants. These results suggest that high levels of PGE2 production, which can be inhibited by the selective COX-2 inhibitor, may be associated with immunosuppression in colon carcinoma.



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  		FIG. 1. (A) PGE2 production by normal lymphocytes and tumor cells (5x105/well in 2.0 ml of RPMI-1640/2% FBS). The leftmost column shows the PGE2 concentration in medium alone. PGE2 production in the culture supernatant was assessed after 24 hours incubation. Values represent the mean ± SE of triplicate measurements. (B) COX-2 mRNA expression by CE-1, DLD-1, and WiDr cells.

 


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  		FIG. 2. Inhibition of PGE2 production of CE-1 by selective COX-2 inhibitor, NS-398. Values represent the mean ± SE of triplicate measurements in the absence or presence of NS-398, ranging from 0.1 to 10 mM. *P < .0001 vs. PGE2 concentration without NS-398.

 


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  		FIG. 3. Influence of supernatant from tumor cells culture on PHA-stimulated lymphocyte proliferation. Lymphocytes were cocultured with tumor cells for 48 hours as described in text. The lymphocytes (1x105 cells) were separated, stimulated with 0.5 mg/ml of PHA for 60 hours, and then pulsed with [3H]-thymidine for 12 hours. The PHA index was calculated as follows: PHA index = thymidine uptake by PHA-stimulated lymphocytes/thymidine uptake by nonstimulated lymphocytes. The leftmost column is the PHA index of the lymphocytes in medium alone as control. Data are given as the mean ± SE of triplicate measurements. *P < .005 vs. control.

 


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  		FIG. 4. Titration of the inhibitory effects of the CE-1 supernatants on PHA-stimulated lymphocyte proliferation. Data are given as the mean ± SE of triplicate measurements.

 
COX-2 mRNA Expression in Clinical Samples
We compared COX-2 mRNA expression in colorectal carcinoma tissue with that in adjacent nontumor tissue. The data are summarized in Figs. 5 and 6. The frequency of COX-2 mRNA expression in carcinoma was significantly higher than that in noncarcinoma tissue (positive %; noncarcinoma, 52.6%; carcinoma, 98.2%; P < .0001). Relative expression of COX-2 mRNA, as determined by semiquantitative RT-PCR, was significantly greater in carcinoma than in noncarcinoma tissue (0.168 ± 0.042 vs. 0.554 ± 0.048, P < .0001) (Fig. 6). Relative expression of COX-2 mRNA showed no correlation with clinicopathologic parameters: depth of tumor invasion, lymph node metastasis, distant metastasis, and stage (Fig. 7).32



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  		FIG. 5. Representative COX-2 and GAPDH mRNA expression in colon carcinoma tissues analyzed by RT-PCR. Lane M, molecular marker; lane C, human colon carcinoma cell line CE-1 as the positive control; lane N, noncarcinoma tissue; lane T, carcinoma tissue.

 


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  		FIG. 6. Semiquantitative RT-PCR of COX-2 mRNA expression in total RNA extracted from colon carcinoma specimens and from their paired control noncarcinoma samples. Data are expressed as the ratio of COX-2 mRNA/GAPDH mRNA calculated from the arbitrary densitometric units. Values represent the mean ± SE. *P < .0001.

 


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  		FIG. 7. Relationship between the ratio of COX-2 mRNA/GAPDH mRNA and clinicopathologic factors. (A) No correlation with the depth of invasion (a marginal statistical significance: P = .51, by one-factor ANOVA). (B) No correlation with grades of lymph node metastasis (P = .89, by one-factor ANOVA). (C) No correlation with existence of distant metastatic foci (P = .12, by Student’s t-test). (D) No correlation with the clinical stage (P = .50, by one-factor ANOVA). Stages I, II, III, and IV coincide with Dukes stages A, B, C, and D, respectively. Each factor was determined according to the TNM classification.32 Values represent the mean ± SE.

 
COX-2 Protein Expression
We assessed COX-2 protein expression in colon carcinoma tissue and compared it with that in noncarcinoma tissue from the same specimen. Anti-COX-2 immunoreactivity was demonstrated in all carcinoma tissue samples from the 30 patients tested. A representative section is shown in Fig. 8. The immunoreactivity was seen in well- to poorly differentiated as well as undifferentiated adenocarcinoma cells. Some regions of the carcinoma showed strong immunoreactivity while others showed weak reactivity. In normal colon mucosa, COX-2 protein expression was barely detectable in epithelial or stromal cells. In some stromal tissue specimens from normal colonic areas, COX-2 was weakly immunostained in macrophages.



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  		FIG. 8. Immunohistochemical staining of COX-2 in colon carcinoma tissue. (A) Noncarcinoma tissue. Weak COX-2 immunoreactivity was observed in the normal tissue stroma but not in the normal epithelium. (B) Carcinoma tissue. Immunoreactive COX-2 is strongly expressed in carcinoma foci (original magnification x 400).

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
In this study, we showed that the colon carcinoma cell line, with a high level of COX-2 mRNA expression and consequent marked production of PGE2, suppressed lymphocyte proliferation in response to a mitogen. Suppression of lymphocyte proliferation was reversed by addition of the selective COX-2 inhibitor, NS-398. We also found that human colon carcinoma tissues expressed more COX-2 mRNA and protein than did nonneoplastic tissues. Our results suggest that increased levels of COX-2 in colorectal carcinomas may be associated with escape from host immunity through inhibition of lymphocyte proliferation.

COX isozymes catalyze a critical step in prostanoid synthesis. Previous studies have shown the importance of COX-2 in colon carcinogenesis.22 COX-2 overexpression may alter the biologic behavior of tumor cells in a number of ways,23,24 and it may influence metastasis and angiogenesis in colon carcinoma.29,30 A recent study has suggested a correlation between the COX-2 level and depth of invasion,35 but we could not find a correlation between COX-2 expression and clinicopathologic parameters—including depth of invasion. This divergence of findings may be partly due to differences in patient background or in the COX-2 primer used.

The mechanism by which COX-2 expression is regulated in tumor tissue is still unclear. Activation of the transcription factor NF-kB has been found to be critical for COX-2 activation in macrophages after exposure to lipopolysaccharide.36 Our recent studies have suggested that activation of NF-kB may be increased in colorectal carcinoma tissues (data not shown); the raised activity of NF-kB may participate in COX-2 overexpression.

PGE2 has been shown to reduce activation of natural killer cells and cytotoxic T cells, inducing inhibition of interleukin (IL)-2 production and downregulation of IL-2 receptor expression on the effector cell surface.37,38 Although the mechanism by which PGE2 inhibits lymphocyte responses is not well known, Huang et al.39 have reported that PGE2 suppresses the immune reaction against tumor cells through modulation of production of such cytokines as IL-10 and IL-12 by lymphocytes and macrophages. Recently Elliott et al.40 have suggested that PGE2 induces T-cell anergy, and Sergeeva et al.41 have demonstrated that PGE2 in picomolar concentrations inhibits lymphocyte proliferation. In our in vitro study we found that the colon carcinoma cell line showing abundant COX-2 expression could produce high amounts of PGE2 in nanomolar concentrations and suppress PHA-stimulated lymphocyte proliferation, whereas the selective COX-2 inhibitor significantly reduced the suppressive effect. These results suggest that large amounts of PGE2 produced in colon carcinoma tissue may influence antitumor lymphocyte reactions to result in immunosuppression. Accordingly, the administration of a COX-2 inhibitor might improve the antitumor immune responses in colon cancer patients.

In conclusion, high expression of COX-2 may be associated with such pathophysiologic states as local immunosuppression in colon cancer. COX-2 mRNA and protein were found to be overexpressed in human colon carcinoma tissue. COX-2 inhibitors might prove therapeutically useful in the treatment of colon cancer, as also suggested by epidemiologic investigations with respect to NSAIDs.

Received for publication August 2, 2000. Accepted for publication February 1, 2001.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Thun MJ, Namboodiri MM, Heath CW Jr. Aspirin use and reduced risk of fatal colon cancer. N Engl J Med 1991; 325: 1593–6.[Abstract]
  2. Rosenberg L, Palmer JR, Zauner AG, Warshauer ME, Stolley PD, Shapiro S. A hypothesis: non-steroidal anti-inflammatory drugs reduce the incidence of the bowel cancer. J Natl Cancer Inst 1991; 83: 355–8.[Abstract/Free Full Text]
  3. Smalley WE, DuBois RN. Colorectal cancer and nonsteroidal anti-inflammatory drugs. Adv Pharmacol 1997; 39: 1–20.
  4. Labyle D,D, Fischer D, Vielh P, et al. Sulindac causes regression of rectal polyps in familial adenomatous polyposis. Gastroenterology 1991; 101: 635–9.[Medline]
  5. Giardiello FM, Hamilton SR, Krush AJ, et al. Treatment of colonic and rectal adenomas with sulindac in familial adenomatous polyposis. N Engl J Med 1993; 328: 1313–6.[Abstract/Free Full Text]
  6. Rao CV, Rivenson A, Simi B, et al. Chemoprevention of colon carcinogenesis by sulindac, a nonsteroidal anti-inflammatory agent. Cancer Res 1995; 55: 1464–72.[Abstract/Free Full Text]
  7. Tanaka T, Kojima T, Yoshimi N, Sugie S, Mori H. Inhibitory effect of the non-steroidal anti-inflammatory drug, indomethacin on the naturally occurring carcinogen, 1-hydroxyanthraquinone in male ACI/N rats. Carcinogenesis 1991; 12: 1949–52.[Abstract/Free Full Text]
  8. Reddy BS, Maruyama H, Kelloff G. Dose-related inhibition of colon carcinogenesis by dietary piroxicam, a nonsteroidal anti-inflammatory drug, during different stages of rat colon tumor development. Cancer Res 1987; 47: 5340–56.[Abstract/Free Full Text]
  9. Smith WL, Marnett L. Prostaglandin endoperoxide synthase: structure and catalysis. Biochim Biophys Acta 1991; 1083: 1–17.[Medline]
  10. Vane JR., Inhibition of prostaglandin synthesis as a mechanism of action for aspirin- like drugs. Nat New Biol 1971; 231: 232–5.[Medline]
  11. Battistini B, Botting R, Bakhle YS. COX-1 and COX-2: toward the development of more selective NSAIDS. Drug News Perspect 1994; 7: 501–12.
  12. Smith WL, DeWitt DL. Biochemistry of prostaglandin endoperoxide H synthase-1 and synthase-2 and their differential susceptibility to nonsteroidal anti-inflammatory drugs. Semin Nephrol 1995; 15: 179–94.[Medline]
  13. Smith WL, Bell TG. Immunohistochemical localization of prostaglandin forming cyclooxygenase in renal cortex. Am J Physiol 1978; 235: F451–7.[Abstract/Free Full Text]
  14. Dewitt DL, Day JS, Sonnenburg WK, Smith WL. Concentration of endoperoxide synthase and prostaglandin I2 synthase in the endothelium and smooth muscle of bovine aorta. J Clin Invest 1983; 72: 1882–8.
  15. Simmons DL, Xie W, Chipman JG, Evett GE. Multiple cyclooxygenase: cloning of a mitogen-inducible form.In: Bailey, JM, ed. Prostaglandin, Leukotrienes, Lipoxins and PAF.0 New York: Plenum Press, 1991: 57–78.
  16. Funk CD, Funk LB, Kennedy ME, Pong AS, Fitzgerald GA. Human platelet/erythroleukemia cell prostaglandin G/H synthetase: cDNA cloning, expression, and gene chromosomal assignment. FASEB J 1991; 5: 2304–12.[Abstract]
  17. Hla T, Neilson K. Human cyclooxygenase-2 cDNA. Proc Natl Acad Sci U S A 1992; 89: 7384–8.[Abstract/Free Full Text]
  18. Crofford LJ, Wilder RL, Ristimaki AP, et al. Cyclooxygenase-1 and -2 expression in rheumatoid synovial tissues: effects of interleukin-1b, phorbol ester, and corticosteroids. J Clin Invest 1994; 93: 1095–101.
  19. Sano H, Kawahiyo Y, Wilder RL, et al. Expression of cyclooxygenase-1 and -2 in human colorectal cancer. Cancer Res 1995; 55: 3785–9.[Abstract/Free Full Text]
  20. Eberhart CE, Coffey RJ, Radhika A, Giardiello FM, Ferrenbach S DuBois RN. Up- regulation of cyclooxygenase 2 gene expression in human colorectal adenomas and adenocarcinomas. Gastroenterology 1994; 107: 1183–8.[Medline]
  21. Kargman SL, O’Neill GP, Vickers PJ, Evans JF, Mancini JA, Jothy S. Expression of prostaglandin G/H synthase-1 and -2 protein in human colon cancer. Cancer Res 1995; 55: 2556–9.[Abstract/Free Full Text]
  22. Oshima M, Dinchuk JE, Kargman SL, et al. Suppression of intestinal polyposis in Apc delta716 knockout mice by inhibition of cyclooxygenase 2 (COX-2). Cell 1996; 87: 803–9.[CrossRef][Medline]
  23. Tsujii M,M, DuBois RN. Alterations in cellular adhesion and apoptosis in epithelial cells overexpressing prostaglandin endoperoxide synthase 2. Cell 1995; 83: 493–501.[CrossRef][Medline]
  24. DuBois RN, Shao J, Tsujii M, Sheng H, Beauchamp RD. G1 delay in cells overexpressing prostaglandin endoperoxide synthase-2. Cancer Res 1996; 56: 733–7.[Abstract/Free Full Text]
  25. Rigas B, Goldman IS, Levine L. Altered eicosanoid levels in human colon cancer. J Lab Clin Med 1993; 122: 518–23.[Medline]
  26. Maxwell WJ, Kelleher D, Keating JJ, et al. Enhanced secretion of prostaglandin E2by tissue-fixed macrophages in colonic carcinoma. Digestion 1990; 47: 160–6.[Medline]
  27. Sheng H, Shao J, Morrow JD, Beauchamp RD, DuBois RN. Modulation of apoptosis and Bcl-2 expression by prostaglandin E2in human colon cancer cells. Cancer Res 1998; 58: 362–6.[Abstract/Free Full Text]
  28. Mastino A, Grelli S, Piacentini M, Oliverio S, Favalli C, Perno CF, Garaci E. Correlation between induction of lymphocyte apoptosis and prostaglandin E2 production by macrophages infected with HIV. Cell Immunol 1993; 152: 120–30.[CrossRef][Medline]
  29. Tsujii M, Kawano S, DuBois RN. Cyclooxygenase-2 expression in human colon cancer cells increases metastatic potential. Proc Natl Acad Sci U S A 1997; 94: 3336–40.[Abstract/Free Full Text]
  30. Tsujii M, Kawano S, Tsuji S, Sawaoka H, Hori M, DuBois RN. Cyclooxygenase regulates angiogenesis induced by colon cancer cells. Cell 1998; 93: 705–16.[CrossRef][Medline]
  31. Kojima M, Morisaki T, Izuhara K, et al. Lipopolysaccharide increases cyclo-oxygenase-2 expression in a colon carcinoma cell line through nuclear factor-kB activation. Oncogene 2000; 19: 1225–31.[CrossRef][Medline]
  32. International Union Against Cancer. Colon and Rectum.In: Sobin LH, Wittekind C eds. TNM Classification of Malignant Tumors. 5th ed. New York: Wiley-Liss, Inc., 1997: 66–9.
  33. Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem 1987; 162: 156–9.[Medline]
  34. O’Neill GP, Ford-Hutchinson AW. Expression of mRNA for cyclooxygenase-1 and cyclooxygenase-2 in human tissues. FEBS Lett 1993; 330: 156–60.[Medline]
  35. Fujita T, Matsui M, Takaku K, et al. Size- and invasion-dependent increase in cyclooxygenase 2 levels in human colorectal carcinomas. Cancer Res 1998; 58: 4823–6.[Abstract/Free Full Text]
  36. D’Acquist F, Iuvone T, Rombola L, Sautebin L, Di Rosa M, Carnuccio R. Involvement of NF-kB in the regulation of cyclooxygenase-2 protein expression in LPS-stimulated J774 macrophages. FEBS Lett 1997; 418: 175–8.[CrossRef][Medline]
  37. Parhar RS, Lara PK. PGE2-mediated inactivation of various killer lineage cells by tumor bearing host macrophage. J Leukoc Biol 1988; 46: 474–84.
  38. Chouaib S, Welte K, Mertelsmann R, Dupont B. Prostaglandin E2 acts at two distinct pathways of T lymphocyte activation: inhibition of interleukin 2 production and down-regulation of transferrin receptor expression. J Immunol 1985; 135: 1172–9.[Abstract]
  39. Huang M,M, Stolina M, Sharma S, et al. 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 1998; 58: 1208–16.[Abstract/Free Full Text]
  40. Elliott LH, Levay AK. Costimulation with dexamethasone and prostaglandin E2: a novel paradigm for the induction of T-cell anergy. Cell Immunol 1997; 180: 124–31.[CrossRef][Medline]
  41. Sergeeva MG, Gonchar AT, Mevkh AT, Varfolomeyev SD. Prostaglandin E2biphasic control of lymphocyte proliferation: inhibition by picomolar concentrations. FEBS Lett 1997; 418: 235–8.[CrossRef][Medline]



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L. T. Soumaoro, H. Uetake, T. Higuchi, Y. Takagi, M. Enomoto, and K. Sugihara
Cyclooxygenase-2 Expression: A Significant Prognostic Indicator for Patients With Colorectal Cancer
Clin. Cancer Res., December 15, 2004; 10(24): 8465 - 8471.
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A. P. Simopoulos
The Mediterranean Diets: What Is So Special about the Diet of Greece? The Scientific Evidence
J. Nutr., November 1, 2001; 131(11): 3065S - 3073.
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