15-LOX-1: a novel molecular target of nonsteroidal anti-inflammatory drug-induced apoptosis in colorectal cancer cells.
BACKGROUND
Nonsteroidal anti-inflammatory drugs (NSAIDs) appear to act via induction of apoptosis-programmed cell death-as potential colorectal cancer chemopreventive agents. NSAIDs can alter the production of different metabolites of polyunsaturated fatty acids (linoleic and arachidonic acids) through effects on lipoxygenases (LOXs) and cyclooxygenases. 15-LOX-1 is the main enzyme for metabolizing colonic linoleic acid to 13-S-hydroxyoctadecadienoic acid (13-S-HODE), which induces apoptosis. In human colorectal cancers, the expression of this enzyme is reduced. NSAIDs can increase 15-LOX enzymatic activity in normal leukocytes, but their effects on 15-LOX in neoplastic cells have been unknown. We tested the hypothesis that NSAIDs induce apoptosis in colorectal cancer cells by increasing the protein expression and enzymatic activity of 15-LOX-1.


METHODS
We assessed 15-LOX-1 protein expression and enzymatic activity, 13-S-HODE levels, and 15-LOX-1 inhibition in association with cellular growth inhibition and apoptosis induced by NSAIDs (primarily sulindac and NS-398) in two colorectal cancer cell lines (RKO and HT-29). All P values are two-sided.


RESULTS
Sulindac and NS-398 progressively increased 15-LOX-1 protein expression in RKO cells (at 24, 48, and 72 hours) in association with subsequent growth inhibition and apoptosis. Increased 13-S-HODE levels and the formation of 15-hydroxyeicosatetraenoic acid on incubation of the cells with the substrate arachidonic acid confirmed the enzymatic activity of 15-LOX-1. Inhibition of 15-LOX-1 in RKO cells by treatment with caffeic acid blocked NS-398-induced 13-S-HODE production, cellular growth inhibition, and apoptosis (P =. 007, P<.0001, and P<.0001, respectively); growth inhibition and apoptosis were restored by adding exogenous 13-S-HODE (P<.0001 for each) but not its parent compound, linoleic acid (P = 1.0 for each). Similar results occurred with other NSAIDs and in HT-29 cells.


CONCLUSIONS
These data identify 15-LOX-1 as a novel molecular target of NSAIDs for inducing apoptosis in colorectal carcinogenesis.
Shureiqi
I
I
Department of Clinical Cancer Prevention, The University of Texas M. D. Anderson Cancer Center, Houston 77030-4085, USA.
Chen
D
D
Lee
J J
JJ
Yang
P
P
Newman
R A
RA
Brenner
D E
DE
Lotan
R
R
Fischer
S M
SM
Lippman
S M
SM
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology* / Q000627:therapeutic use; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001093:Arachidonate 15-Lipoxygenase / Q000096:biosynthesis* / Q000187:drug effects; D015153:Blotting, Western; D002109:Caffeic Acids / Q000494:pharmacology; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D008401:Gas Chromatography-Mass Spectrometry; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008041:Linoleic Acids / Q000378:metabolism*; D009578:Nitrobenzenes / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013467:Sulindac / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000975:Antioxidants; D002109:Caffeic Acids; D016861:Cyclooxygenase Inhibitors; D008041:Linoleic Acids; D009578:Nitrobenzenes; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D013467:Sulindac; C024348:13-hydroxy-9,11-octadecadienoic acid; D001093:Arachidonate 15-Lipoxygenase; C040048:caffeic acid