Five-lipoxygenase-activating protein inhibitor MK-886 induces apoptosis in gastric cancer through upregulation of p27kip1 and bax

Background and Aim: Products of the arachidonic acid metabolizing enzyme, 5-lipoxygenase (5-LOX), stimulate the growth of several cancer types. Inhibitors of 5-LOX and 5-LOX-activating protein (FLAP) induce apoptosis in some cancer cells. Here, the authors investigated the effect of a FLAP inhibitor, MK-886, on the inhibition of proliferation and induction of apoptosis in gastric cancer. Methods: Cell proliferation in gastric cancer cells was measured using an 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apoptosis was measured using acridine orange staining and flow cytometry. Protein expression of apoptosis-related genes p53, p21(waf1), p27(kip1), bcl-2 families, cytochrome c, and the caspases were examined using Western blotting. Caspase-3 activity was measured using colorimetric assay of substrate cleavage. Results: MK-886 inhibited cell growth in a dose- and time-dependent manner. Apoptosis was induced in gastric cancer cells and was characterized by upregulation of p27(kip1) and bax, with release of cytochrome c from mitochondria into cytosol, which initiated caspase-3 activation. Specific caspase-3 inhibitors partially blocked MK-886-induced apoptosis. Conclusion: The present results suggest that MK-886 induces apoptosis in gastric cancer cells through upregulation of p27(kip1) and bax, and that MK-886 is a potentially useful drug in gastric cancer prevention and therapy. (C) 2004 Blackwell Publishing Asia Pty Ltd.