Expression of cyclooxygenase-2 and clinicopathologic features in human gastric adenocarcinoma

Abstract

Aim: To study the expression of cyclooxygenase-2 (COX-2) gene in gastric cancer and the relationship between COX-2 expression and clinicopathologic features of gastric cancer.

Methods: With reference to the expression of beta-actin gene, COX-2 mRNA level was examined in cancerous tissues and adjacent noncancerous mucosa from 33 patients by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Quantitation of relative band Adj volume counts was performed using molecular Analyst for windows software. The COX-2 index was determined from the band Adj volume counts ratio of COX-2 to constitutively expressed actin.

Results: The COX-2 index in gastric carcinoma was significantly higher than that in normal mucosa (0.5966+/-0.2659 vs 0.2979+/-0.171, u=5.4309, P<0.01). Significantly higher expression of COX-2 mRNA was also observed in patients with lymph node involvement than that in those without (0.6775+/-0.2486 vs 0.4105+/-0.2182, t=2.9341, P<0.01). Furthermore, the staging in the UICC TNM classification significantly correlated with COX-2 overexpression (F=3.656, P<0.05), the COX-2 index in stage III and IV was significantly higher than those in stage I and II (q=3.2728 and q=3.4906, P<0.05). The COX-2 index showed no correlation with patient's age, sex, blood group, tumor location, gross typing, depth of invasion, differentiation, and the greatest tumor dimension (P>0.05).

Conclusion: Expression of COX-2 mRNA in gastric carcinoma was significantly higher, which may enhance lymphatic metastasis in patients with gastric carcinoma. The staging in the UICC TNM classification was significantly correlated with COX-2 over-expression. COX-2 may contribute to progression of tumor in human gastric adenocarcinoma.

Figure 1

Representative β-actin mRNA expression in samples analyzed by RT-PCR. Lane M, molecular marker, from above down: 2000, 1000, 750, 500, 250, 100 bp.

Figure 2

Representative COX-2 mRNA expression in gastric carcinoma tissues analyzed by RT-PCR. Lane M, molecular marker, from above down: 2000, 1000, 750, 500, 250, 100 bp. Lane N, noncancerous tissue; lane T, cancerous tissue.