title: Inhibition of 5-lipoxygenase by MK886 augments the antitumor activity of celecoxib in human colon cancer cells.
abstract: Cyclooxygenase (COX)-2 and 5-lipoxygenase (5-LOX) are key enzymes involved in arachidonic acid metabolism. Their products, prostaglandins and leukotrienes, are involved in colorectal tumor development. We aimed at evaluating whether combined blocking of the COX-2 and 5-LOX pathways might have additive antitumor effects in colorectal cancer. The expression/activity of COX-2 and 5-LOX were assessed in 24 human colorectal cancer specimens. The effects of the COX-2 inhibitor celecoxib and the 5-LOX inhibitor MK886 on prostaglandin E(2) and cysteinyl leukotriene production, tumor cell proliferation, cell apoptosis, and Bcl-2/Bax expression were evaluated in the Caco-2 and HT29 colon cancer cells. We also investigated the effect of the enzymatic inhibition on mitochondrial membrane depolarization, one of the most important mechanisms involved in ceramide-induced apoptosis. Up-regulation of the COX-2 and 5-LOX pathways was found in the tumor tissue in comparison with normal colon mucosa. Inhibition of either COX-2 or 5-LOX alone resulted in activation of the other pathway in colon cancer cells. Combined treatment with 10 micromol/L celecoxib and MK886 could prevent this activation and had additive effects on inhibiting tumor cell proliferation, inducing cell apoptosis, decreasing Bcl-2 expression, increasing Bax expression, and determining mitochondrial depolarization in comparison with treatment with either inhibitor alone. The administration of the ceramide synthase inhibitor fumonisin B1 could prevent some of these antineoplastic effects. In conclusion, our study showed that inhibition of 5-LOX by MK886 could augment the antitumor activity of celecoxib in human colorectal cancer.
authors.affiliation: Dipartimento di Area Critica Medico-Chirurgica Medical School, University of Florence, Viale Morgagni 85, 50134 Florence, Italy. cianchif@mail.unifi.it
authors.forename: Fabio
authors.initials: F
authors.lastname: Cianchi
authors.forename: Camillo
authors.initials: C
authors.lastname: Cortesini
authors.forename: Lucia
authors.initials: L
authors.lastname: Magnelli
authors.forename: Elena
authors.initials: E
authors.lastname: Fanti
authors.forename: Laura
authors.initials: L
authors.lastname: Papucci
authors.forename: Nicola
authors.initials: N
authors.lastname: Schiavone
authors.forename: Luca
authors.initials: L
authors.lastname: Messerini
authors.forename: Alfredo
authors.initials: A
authors.lastname: Vannacci
authors.forename: Sergio
authors.initials: S
authors.lastname: Capaccioli
authors.forename: Federico
authors.initials: F
authors.lastname: Perna
authors.forename: Matteo
authors.initials: M
authors.lastname: Lulli
authors.forename: Valentina
authors.initials: V
authors.lastname: Fabbroni
authors.forename: Giuliano
authors.initials: G
authors.lastname: Perigli
authors.forename: Paolo
authors.initials: P
authors.lastname: Bechi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Masini
mesh_terms: D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D018938:Caco-2 Cells; D000068579:Celecoxib; D002460:Cell Line; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D019073:HT29 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology* / Q000627:therapeutic use; D016859:Lipoxygenase Inhibitors; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D011720:Pyrazoles / Q000494:pharmacology* / Q000627:therapeutic use; D018077:Receptors, Leukotriene / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology* / Q000627:therapeutic use; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D002722:Chlorobenzenes
chemical_list: D000970:Antineoplastic Agents; D001094:Arachidonate 5-Lipoxygenase; D000068579:Celecoxib; D051546:Cyclooxygenase 2; D016861:Cyclooxygenase Inhibitors; D015232:Dinoprostone; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D008565:Membrane Proteins; D011720:Pyrazoles; D018077:Receptors, Leukotriene; D013449:Sulfonamides; D051028:bcl-2-Associated X Protein; C060893:MK-886; D002722:Chlorobenzenes; C496540:PTGS2 protein, human; C083169:leukotriene D4 receptor