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

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE157982 | GEO | 2021/06/22

REPOSITORIES: GEO

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Project description:Background: In addition to its canonical functions, vitamin D has been proposed to be an important mediator of the immune system. Despite ample sunshine, vitamin D deficiency is prevalent (> 80%) in the Middle East, resulting in a high rate of supplementation. However, the underlying molecular mechanisms of the specific regimen and potential factors affecting an individual’s response to vitamin D are not well characterized. Objective: To characterize changes in blood transcriptomic and the potential mechanisms associated with vitamin D3 supplementation and response. Design: In this intervention study, one hundred vitamin D-deficient women were given a weekly oral dose (50,000 IU) of vitamin D3 for three months. A high-throughput targeted PCR, composed of 264 genes representing important blood transcriptomic fingerprints in health and disease states, was performed on pre- and post-supplementation blood samples to profile the molecular response to vitamin D3. Multivariate, network, gene ontology, and literature mining analyses were used for the interpretation of the transcriptomic profiling results. Results: We identified 54 differentially expressed genes that were strongly modulated by vitamin D3 supplementation. Network analyses showed significant changes in the immune-related pathways such as TLR4/CD14 and IFN receptors, and catabolic processes related to NFkB, which were subsequently confirmed by gene ontology enrichment analyses. We proposed a model for vitamin D3 response, using the reduced expression of the molecules involved and the receptor-mediated intra-cellular signaling leading to reduce cytokine production. Conclusions: Blood-transcriptomic profiles of vitamin D3 response were generated using a targeted blood gene panel. Vitamin D has a strong effect on the immune system, G-coupled protein receptor signaling, and the ubiquitin system. We highlighted the major molecular changes and biological processes induced by vitamin D3, which will help to further investigate the effectiveness of vitamin D supplementation among individuals in the Middle East.

Project description:Background: Colorectal cancer (CRC) is one of the major causes of cancer-related death worldwide. Although commercial biomarkers of CRC are currently available, they are still lacking in terms of sensitivity and specificity; thus, searching for reliable blood-based biomarkers are important for the primary screening of CRC. Methods: Plasma samples of patients with non-metastatic (NM) and metastatic (M) CRC and healthy controls were fractionated using MARS-14 immunoaffinity chromatography. The flow-through and elute fractions representing low- and high-abundant proteins, respectively, were analyzed by label-free quantitative proteomics mass spectrometry. The functional analysis of the proteins with greater than 1.5-fold differential expression level between the CRC and the healthy control groups were analyzed for their biological processes and molecular functions. In addition, the levels of plasma proteins showing large alterations in CRC patients were confirmed by immunoblotting using two independent cohorts. Moreover, receiver operating characteristic (ROC) curve analysis was performed for individual and combinations of biomarker candidates so as to evaluate the diagnostic performance of biomarker candidates. Results: From 163 refined identifications, five proteins were up-regulated and two proteins were down-regulated in NM-CRC while eight proteins were up-regulated and three proteins were down-regulated in M-CRC, respectively. Altered plasma proteins in NM-CRC were mainly involved in complement activation, while those in M-CRC were clustered in acute-phase response, complement activation, and inflammatory response. Results from the study- and validation-cohorts indicate that the levels of LRG, C9, AGP1, and A1AT were statistically increased, while FN level was statistically decreased in CRC patients compared to healthy controls, with most alterations found in a metastatic stage-dependent manner. ROC analysis revealed that FN exhibited the best diagnostic performance to discriminate CRC patients and healthy controls while AGP1 showed the best discrimination between the disease stages in both cohorts. The combined biomarker candidates, FN+A1AT+AGP1, exhibited perfect discriminatory power to discriminate between the CRC population and healthy controls whereas LRG+A1AT+AGP1 was likely to be the best panel to discriminate the metastatic stages in both cohorts. Conclusions: This study identified and quantified distinct plasma proteome profiles of CRC patients. Selected CRC biomarker candidates including FN, LRG, C9, A1AT, and AGP1 may be further applied for screening larger cohorts.

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

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