Abstract: Objective To investigate 5-lipoxygenase （5-LOX） expression in gastric carcinoma, its relationships with cyclooxygenase-2 （COX-2） and formyl peptide receptor type 2 （FPR2）, and their clinicopathological implications. Methods Expressions of the above three indexes were detected from 70 gastric carcinoma patients by immunohistochemistry. The relationships among them and clinicopathological features were analyzed. Moreover, whether knockdowning 5-LOX had effects on COX-2 and FPR₂ mRNA expression in SGC-7901 cells was investigated. Results The positive expression rates of 5-LOX were 76.0％ in cases ≤45 years and 84.4％ in cases >45 years; 82.1％ in cases with tumor diameter ≤3 cm and 81.0％ in cases with tumor diameter >3 cm; 80.0％, 80.0％, and 90.0％ in cases of poorly differentiated, middle-highly differentiated, and mucinous adenocarcinoma, respectively, with no significant difference （P>0.05）. The positive expression rates of 5-LOX in cases of gastric carcinoma without and with axillary node metastasis were 71.8％ and 93.5％; in cases at stage Ⅰ-Ⅱ and Ⅲ-Ⅳ, 75.0％ and 95.5％ respectively, with significant difference （P<0.05）. The positive expression rates of 5-LOX in cases of gastric carcinoma with positive COX-2 expression and negative COX-2 expression were 81.6％ and 81.0％ resepctively, without significant difference （P>0.05）, and the values in cases of gastric carcinoma with positive FPR2 expression and negative FPR2 expression were 78.1％ and 84.2％ respectively, without significant difference as well （P>0.05）. Moreover, silencing 5-LOX had no effects on COX-2 and FPR2 mRNA expressions in SGC-7901 cells. Conclusion 5-LOX plays an important role in the invasion and metastasis of gastric carcinoma, and combined targeting 5-LOX and COX-2 would be an effective approach for gastric carcinoma.

Key words: Gastric carcinoma, 5-Lipoxygenase, Cyclooxygenase-2, Formyl peptide receptor type 2