Abstract: Objective To explore the expression of extracellular matrix metalloproteinase inducer（EMMPRIN） in human leukemic cell line（THP-1） macrophages produced by angiotensin Ⅱ（Ang Ⅱ） stimulation and its possible mechanisms.Methods THP-1 monocyte were cultured with 5 μg/L PMA and transformed into macrophages by 10-6 mol/L Ang Ⅱ.EMMPRIN gene and its protein were measured by real-time PCR and Western blot.PGE2 expression was assayed by ELISA angiotensin type 1 receptor（AT1R,10-5 mol/L）antagonist,angiotensin type 2 receptor（AT2R,10-5 mol/L）antagonist,cyclooxygenase-2（COX-2） inhibitor,NS-398,were used to inhibit the effect of Ang Ⅱ,and prostaglandin E2（PGE2） was added to delineate the mechanism of Ang Ⅱ-induced EMMPRIN expression.Results Ang Ⅱ induced the EMMPRIN expression obviously in macrophages,enhanced at 6 h,peaked at 12 h and declined after 24 h.Compared to the control group（RPMI-1640 group）,gene expression of EMMPRIN was increased to 5 times by Ang Ⅱ（10-6 mol/L） stimulation after 12 h;protein expression was increased to 4 times.In addition,the tendency of enhancement of COX-2 and PGE2 by Ang Ⅱ stimulation were coincident with the expression of EMMPRIN.AT1R antagonist and COX-2 inhibitor,but not AT2R antagonist,PD123319 inhibited the effect of Ang Ⅱ.Conclusion Ang Ⅱ up-regulate the EMMPRIN expression in THP-1 macrophages via AT1R/COX-2/PGE2 signal transduction pathway.