The 15-lipoxygenase-1 expression may enhance the sensitivity to non-steroidal anti-inflammatory drug-induced apoptosis in colorectal cancers from patients who are treated with the compounds.
OBJECTIVE
Non-steroidal anti-inflammatory drugs (NSAIDs) can prevent colorectal cancer (CRC), but their effect is limited. Recent studies have shown the involvement of 15-lipoxygenase-1 (15-LOX-1) in NSAID-induced apoptosis in colorectal carcinoma cells. We evaluate whether 15-LOX-1 expression influences the sensitivity of NSAID-induced apoptosis in CRCs.


METHODS
In 22 CRC surgical samples from NSAID users who had been constant for more than 5 years and 28 CRC surgical samples from NSAID non-users, the expressions of 15-LOX-1, cyclooxygenase-2 (COX-2), beta-catenin, and p53 were analyzed using immunohistochemistry. TUNEL assay was also performed for samples. The effects of the transient transfection of 15-LOX-1 cDNA on indomethacin-induced apoptosis were certified in HCT-116 cells. The effects of adding 13-S-hydroxyoctadecadinoic acid (13-S-HODE) on indomethacin-induced apoptosis were also examined in HCT-116 cells. The levels of apoptosis were determined by the analysis of the floating-cells ratio and DNA gel electrophoresis.


RESULTS
The expression of 15-LOX-1 on CRCs from NSAID users was significantly decreased compared with those from NSAID non-users; however, the expressions of other molecules were not significantly different between two groups. The levels of TUNEL scoring in samples from NSAID users were similar to those from NSAID non-users. Indomethacin (100 microM) induced less apoptosis in mocked cells, whereas the same concentrations of indomethacin enhanced the level of apoptosis in 15-LOX-1-transfected cells. 13-S-HODE also increased the level of indomethacin-induced apoptosis in cells.


CONCLUSIONS
Results suggest that 15-LOX-1 expression may be one of the mechanisms which enhance the sensitivity to NSAID-induced apoptosis in CRCs from patients who are treated with the compounds.
Yoshinaga
Masahiro
M
Department of Gastroenterology, National Hospital Organization Beppu Medical Center, Beppu, Oita, Japan. yoshinam@beppu.hosp.go.jp
Murao
Hiroyuki
H
Kitamura
Yosuke
Y
Koga
Koutaro
K
Tsuruta
Satoru
S
Igarashi
Hisato
H
Nakamura
Kazuhiko
K
Takayanagi
Ryoichi
R
D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004354:Drug Screening Assays, Antitumor; D005260:Female; D045325:HCT116 Cells; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007213:Indomethacin; D008041:Linoleic Acids / Q000494:pharmacology; D008297:Male; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D008041:Linoleic Acids; D016159:Tumor Suppressor Protein p53; D051176:beta Catenin; C024348:13-hydroxy-9,11-octadecadienoic acid; D001093:Arachidonate 15-Lipoxygenase; D051546:Cyclooxygenase 2; D007213:Indomethacin