Expression of COX-2 in stomach cancers and its relation to their biological features.
OBJECTIVE
Cyclooxygenase-2 (COX-2) is one of the key isoenzymes in the production of prostaglandins, and is believed to be involved in carcinogenesis. This study was conducted to examine the role of COX-2 in the development and biological behavior of stomach cancer.


METHODS
Expression of COX-2 at the mRNA and protein levels was analyzed using RT-PCR and immunoblotting assay in 50 cancerous and corresponding non-cancerous tissue specimens. Also, COX-2 expression was detected by an immunohistochemical method in 55 paraffin-embedded gastric adenocarcinoma tissues.


RESULTS
Of the 50 carcinoma tissue samples analyzed, 38 (76.0%) had overexpression of COX-2 as compared to the paired non-cancerous specimens. The overexpression of COX-2 (91.7%) was more prevalent in tumors with sizes of >5 cm than those (61.5%) of </=5 cm (p < 0.05). COX-2 overexpression was higher in tumors with >6 metastatic nodes compared to those with </=6 metastatic nodes (100.0 vs. 61.3%, p < 0.01). The rate of COX-2 overexpression in non-signet ring cell carcinoma was significantly higher compared with signet ring cell carcinoma (84.1 vs. 16.7%, p < 0.05). The rate of COX-2 overexpression (86.8 or 90.9%) in patients with a cancer invasion depth of pT3 + pT4 or with stage III + IV was significantly higher than that (41.7 or 47.1%) in patients with pT1 + pT2 or with stage I + II (both p < 0.01). Furthermore, consistent with the results at the protein and mRNA levels, immunohistochemical stain indicated that COX-2 protein was overexpressed in 39 of 55 (70.9%) carcinomas, and the 5-year survival rate (25.6%) for patients with COX-2 overexpression seemed better than that (50.0%) of patients without overexpression, though the difference was not significant (p < 0.05).


CONCLUSIONS
Our results indicate that COX-2 may play a role in the development of gastric cancer and its overexpression is associated with lymphatic metastasis, tumor invasion and differentiation of gastric carcinoma.
Han
S L
SL
Department of General Surgery, Henan Tumor Hospital, Zhengzhou, Henan Province, P.R. China.
Tang
H J
HJ
Hua
Y W
YW
Ji
S Q
SQ
Lin
D X
DX
D000230:Adenocarcinoma / Q000201:enzymology* / Q000401:mortality / Q000473:pathology*; D000328:Adult; D000368:Aged; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000032:analysis; D001707:Biopsy, Needle; D015153:Blotting, Western; D016022:Case-Control Studies; D046508:Culture Techniques; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D008969:Molecular Sequence Data; D009367:Neoplasm Staging; D011336:Probability; D011379:Prognosis; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000401:mortality / Q000473:pathology*
D014408:Biomarkers, Tumor; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases