Decreased 13-S-hydroxyoctadecadienoic acid levels and 15-lipoxygenase-1 expression in human colon cancers.
13-S-Hydroxyoctadecadienoic acid (13-S-HODE), the product of 15-lipoxygenase (15-LOX) metabolism of linoleic acid, enhances cellular mitogenic responses to certain growth factors. Other observations have questioned whether 13-S-HODE has tumorigenic effects. Our study evaluated the hypothesis that 15-LOX-1 is overexpressed in colon cancers resulting in an increase in intracellular 13-S-HODE. 15-LOX-1 and 13-S-HODE were quantified using western blots, ELISA and immunohistochemistry in 18 human colon cancers with paired normal colonic mucosa. Additionally, 15-LOX-1 expression was measured by western blots in three transformed colonic cell lines and in a human umbilical vein endothelial cell line. Next, we evaluated 13-S-HODE effects on cellular proliferation, cell cycle distribution and apoptosis in a transformed colonic cell line (RKO). Cell cycle distributions were measured by flow cytometry and apoptosis was assessed by phase contrast microscopy, electron microscopy, flow cytometry and DNA fragmentation assay. 15-LOX-1 immunohistochemistry staining scores were reduced in tumor tissues (P </= 0.0001) and 15-LOX-1 expression was absent in three transformed colonic cell lines. 13-S-HODE levels were also reduced in tumors tissues compared with normal controls by ELISA (median 3.3-fold, P = 0.02) and by immunohistochemistry (P </= 0.0001). In vitro 13-S-HODE inhibited RKO cell proliferation and induced cell cycle arrest and apoptosis. 13-S-HODE produced similar effects in HT-29 cells. Our observations indicate that: (i) human colon cancers are associated with a down-regulation in 15-LOX-1 expression and a reduction in 13-S-HODE intracellular levels; (ii) 13-S-HODE can suppress cell proliferation and induce apoptosis in transformed colonic epithelial cells.
Shureiqi
I
I
Division of Hematology, Department of Internal Medicine, Comprehensive Cancer Center, University of Michigan Medical, Ann Arbor, 48109, USA. ishureiq2notes.mdacc.tmc.edu
Wojno
K J
KJ
Poore
J A
JA
Reddy
R G
RG
Moussalli
M J
MJ
Spindler
S A
SA
Greenson
J K
JK
Normolle
D
D
Hasan
A A
AA
Lawrence
T S
TS
Brenner
D E
DE
D017209:Apoptosis; D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D015153:Blotting, Western; D002453:Cell Cycle; D002455:Cell Division; D003110:Colonic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D008041:Linoleic Acids / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D008041:Linoleic Acids; C024348:13-hydroxy-9,11-octadecadienoic acid; D001093:Arachidonate 15-Lipoxygenase