Scottish Colorectal Cancer Vitamin D Intervention Study (SCoViDS) [RNA-seq]

Controversy surrounds whether vitamin D reduces colorectal cancer (CRC) risk, and/or beneficially impacts on CRC survival. We sought to delineate the transcriptomic in vivo response of human colorectal epithelium to vitamin D supplementation, define inter-subject variability and develop a predictive biomarker of response consistent with anti-tumour effects. Methodology Blood and rectal normal mucosa (NM) were sampled (176 subjects) and correlation sought between circulating vitamin D (25-OHD) level and NM gene expression (HT12 microarray) in the observational study. Oral vitamin D (3200IU/day) supplements were administered to 50 participants in an intervention study. Blood and NM (sigmoidoscopic biopsy) were sampled after 12 weeks. Transcriptomic analysis (HT12 and RNAseq) of post-treatment biopsies assessed enrichment for candidate genes and GO processes prioritised in the observational study. We identified transcriptomic changes in rectum that are consistent with anti-tumour responses. We then sought blood biomarkers predicting this response using receiver-operator curves and calculation of C-statistic. An independent expression dataset (BEST-D trial) was then used to validate candidate blood biomarkers of vitamin D response. Overall design: 98 rectal biopsy from 49 Patient's taken pre and post (12 weeks) oral vitamin D supplementation

关于维生素D是否可降低结直肠癌（colorectal cancer, CRC）风险，或对结直肠癌患者的生存产生有益影响，学界尚存争议。本研究旨在阐明人体结直肠上皮细胞对维生素D补充的体内转录组应答特征，明确个体间应答差异，并开发与抗肿瘤效应相符的应答预测生物标志物。

研究方法
本研究的观察性阶段共纳入176名受试者，采集其血液及直肠正常黏膜（rectal normal mucosa, NM）样本，分析循环维生素D（25-hydroxyvitamin D, 25-OHD）水平与直肠正常黏膜基因表达（HT12 microarray）之间的相关性。干预性阶段纳入50名受试者，给予其每日口服3200国际单位（IU）的维生素D补充剂；干预12周后，采集受试者血液及经乙状结肠镜活检获取的直肠正常黏膜样本。对干预后的活检样本进行转录组学分析（采用HT12微阵列与RNA测序技术，RNAseq），评估观察性研究阶段筛选出的候选基因及基因本体（Gene Ontology, GO）过程的富集情况。本研究在直肠组织中鉴定出与抗肿瘤应答相符的转录组学改变；随后通过受试者工作特征曲线（receiver-operator characteristic curve, ROC）及C统计量（C-statistic）计算，筛选可预测该应答的血液生物标志物。随后采用独立的表达谱数据集（BEST-D trial）对筛选出的维生素D应答血液候选生物标志物进行验证。

研究整体设计：共纳入49名受试者，分别在口服维生素D补充剂干预前及干预12周后采集直肠活检样本，总计98份。