Modulation of COX-2 expression in peripheral blood cells by increased intake of fruit and vegetables?
BACKGROUND
Enhanced cyclooxygenase-2 (COX-2) expression is associated with carcinogenesis, ischemia, angiogenesis, inflammation, and neurodegeneration. The preventing effect of aspirin and nonsteroidal anti-inflammatory drugs is partly due to inhibition of the COX-2 enzyme. Fruit and vegetables (FVs) contain numerous compounds that may decrease disease risk by several different mechanisms, for example through the inhibition of COX-2 activity.


OBJECTIVE
We tested the hypothesis that an increased intake of FVs would modulate the COX-2 expression in peripheral blood cells.


METHODS
A strictly controlled dietary crossover study (n = 39). After 1 week run-in period with no FVs in the diet, one group was given two portions of FVs (2 FV), while another group was given five portions (5 FV) daily for 14 days. Following a 2 weeks washout period and 1 week run-in, the regimens were switched between the groups. Gene expression analysis of COX-2 mRNA in blood samples was performed by quantitative real-time-PCR.


RESULTS
No significant treatment effect of diet intervention was found in the crossover analyses (P = 0.74). However, the individual variation in response may seem large.


CONCLUSIONS
These data does not contradict the recommendations for an increased intake of FVs. Further studies on expression directly and indirectly, through analysis of factors regulating and being regulated by COX-2, should be carried out. A first step would be to evaluate the correspondence between COX-2 mRNA expression and products of the COX pathway, like prostaglandins. Naturally occurring polymorphisms of COX-2 promoters and coding regions might contribute to functional variations and response to different diets.


BACKGROUND
Norwegian Research Council, National Nutrition Council, Throne Holst Foundation for Nutrition Research, Freia Chokoladefabriks Medisinske Fond and the Norwegian Cancer Society.
Almendingen
K
K
Medical Department, Rikshospitalet University Hospital, 0027 Oslo, Norway. kari.almendingen@labmed.uio.no
Brevik
A
A
Nymoen
D A
DA
Hilmarsen
H T
HT
Andresen
P A
PA
Andersen
L F
LF
Vatn
M
M
D000328:Adult; D001773:Blood Cells / Q000502:physiology*; D018592:Cross-Over Studies; D051546:Cyclooxygenase 2; D005260:Female; D005638:Fruit; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D009664:Norway; D011451:Prostaglandin-Endoperoxide Synthases / Q000097:blood* / Q000235:genetics*; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013334:Students; D014675:Vegetables
D008565:Membrane Proteins; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases