Colonic transcriptional response to 1α, 25(OH)2 vitamin D3 in African- and European-Americans. Issue 168 (April 2017)

• Record Type: Journal Article
• Authors: Alleyne, Dereck; Witonsky, David B.; Mapes, Brandon; Nakagome, Shigeki; Sommars, Meredith; Hong, Ellie; Muckala, Katy A.; Di Rienzo, Anna; Kupfer, Sonia S.
• Is Part Of: Journal of steroid biochemistry and molecular biology. Issue 168(2017)
• Page Start: 49
• Page End: 59
• Publication Date: 2017-04
• Subjects: Vitamin D -- Gene transcription -- Expression quantitative trait loci -- Colorectal cancer -- Health disparities; Steroid hormones -- Periodicals; Biochemistry -- Periodicals; Hormones -- Periodicals; Molecular Biology -- Periodicals; Hormones stéroïdes -- Périodiques; Steroid hormones; Periodicals; 572.579
• DOI: 10.1016/j.jsbmb.2017.02.001
• Languages: English
• ISSNs: 0960-0760

Abstract

Highlights: Colonic transcriptional response to 1α, 25(OH)2 D3 differs between African and European Americans independent of serum vitamin D levels. Two genes, UPP1 and ZSWIM4, showed definitive replication of inter-ethnic transcriptional response differences to vitamin D treatment in ex vivo colon tissue. A genetic mechanism underlying vitamin D response of ZSWIM4 and HDAC3 was identified and explains inter-ethnic differences in transcriptional responses. Abstract: Colorectal cancer (CRC) is a significant health burden especially among African Americans (AA). Epidemiological studies have correlated low serum vitamin D with CRC risk, and, while hypovitaminosis D is more common and more severe in AA, the mechanisms by which vitamin D modulates CRC risk and how these differ by race are not well understood. Active vitamin D (1α, 25(OH)2 D3 ) has chemoprotective effects primarily through transcriptional regulation of target genes in the colon. We hypothesized that transcriptional response to 1α, 25(OH)2 D3 differs between AA and European Americans (EA) irrespective of serum vitamin D and that regulatory variants could impact transcriptional response. We treated ex vivo colon cultures from 34 healthy subjects (16 AA and 18 EA) with 0.1 μM 1α, 25(OH)2 D3 or vehicle control for 6 h and performed genome-wide transcriptional profiling. We found 8 genes with significant differences in transcriptional response to 1α, 25(OH)2 D3 between AA and EA with definitive replication of inter-ethnic differences for uridine phosphorylase 1 ( UPP1 ) and zinc finger-SWIM containing 4 ( ZSWIM4 ). We performed expression quantitative trait loci (eQTL) mapping and identified response cis- eQTLs for ZSWIM4 as well as for histone deacetylase 3 ( HDAC3 ), the latter of which showed a trend toward significant inter-ethnic differences in transcriptional response. Allele frequency differences of eQTLs for ZSWIM4 and HDAC3 accounted for observed transcriptional differences between populations. Taken together, our results demonstrate that transcriptional response to 1α, 25(OH)2 D3 differs between AA and EA independent of serum 25(OH)D levels. We provide evidence in support of a genetic regulatory mechanism underlying transcriptional differences between populations for ZSWIM4 and HDAC3 . Further work is needed to elucidate how response eQTLs modify vitamin D response and whether genotype and/or transcriptional response correlate with chemopreventive effects. Relevant biomarkers, such as tissue-specific 1α, 25(OH)2 D3 transcriptional response, could identify individuals likely to benefit from vitamin D for CRC prevention as well as elucidate basic mechanisms underlying CRC disparities.