Seasonal variation in expression of markers in the vitamin D pathway in prostate tissue.
OBJECTIVE
Recent studies suggest variation in genes along the vitamin D pathway, as well as vitamin D receptor (VDR) protein levels, may be associated with prostate cancer. As serum vitamin D levels vary by season, we sought to determine whether the expression of genes on the vitamin D pathway, assessed in prostate tumor tissue, do the same.


METHODS
Our study incorporates mRNA expression data from 362 men in the Swedish Watchful Waiting cohort, diagnosed between 1977 and 1999, and 106 men enrolled in the US Physicians' Health Study (PHS) diagnosed between 1983 and 2004. We also assayed for VDR protein expression among 832 men in the PHS and Health Professionals Follow-up Study cohorts. Season was characterized by date of initial tissue specimen collection categorically and by average monthly ultraviolet radiation levels. One-way analysis of variance was used to examine variation in the expression levels of six genes on the vitamin D pathway-VDR, GC, CYP27A1, CYP27B1, RXRα, CYP24A1-and VDR protein by season, adjusted for age at diagnosis and Gleason grade. Variation was also examined separately among lethal and nonlethal cases.


RESULTS
Tumor expression levels of the six genes did not vary significantly by season of tissue collection. No consistent patterns emerged from subgroup analyses by lethal versus nonlethal cases.


CONCLUSIONS
Unlike circulating levels of 25(OH) vitamin D, expression levels of genes on the vitamin D pathway and VDR protein did not vary overall by season of tissue collection. Epidemiological analyses of vitamin D gene expression may not be biased by seasonality.
Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. mameyer@hsph.harvard.edu
Mara M
MM
Epstein
Ove
O
Andrén
Julie L
JL
Kasperzyk
Irene M
IM
Shui
Kathryn L
KL
Penney
Katja
K
Fall
Jennifer R
JR
Rider
Meir J
MJ
Stampfer
Swen-Olof
SO
Andersson
Edward
E
Giovannucci
Lorelei A
LA
Mucci
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000096:biosynthesis / Q000235:genetics; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D053493:Cholestanetriol 26-Monooxygenase / Q000096:biosynthesis / Q000235:genetics; D015331:Cohort Studies; D020869:Gene Expression Profiling; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018167:Receptors, Calcitriol / Q000096:biosynthesis / Q000235:genetics; D047490:Retinoid X Receptor alpha / Q000096:biosynthesis / Q000235:genetics; D012621:Seasons; D013250:Steroid Hydroxylases / Q000096:biosynthesis / Q000235:genetics; D014807:Vitamin D / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D014809:Vitamin D-Binding Protein / Q000096:biosynthesis / Q000235:genetics; D065668:Vitamin D3 24-Hydroxylase
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D047490:Retinoid X Receptor alpha; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; D013250:Steroid Hydroxylases; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase