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- Gylling, Björn, 1978-, et al.
(author)
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One-carbon metabolite ratios as functional B-vitamin markers and in relation to colorectal cancer risk
- 2019
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In: International Journal of Cancer. - : John Wiley & Sons. - 0020-7136 .- 1097-0215. ; 144:5, s. 947-956
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Journal article (peer-reviewed)abstract
- Background: One-carbon metabolism biomarker are easily measured in plasma, but analyzing them one at a time in relation to disease does not take into account the interdependence of the many factors involved. The relative dynamics of major one-carbon metabolism branches can be assessed by relating the functional B-vitamin marker total homocysteine (tHcy) to transsulfuration (total cysteine) and methylation (creatinine) outputs.Objective: We validated the ratios of tHcy to total cysteine (Hcy:Cys), tHcy to creatinine (Hcy:Cre), and tHcy to cysteine to creatinine (Hcy:Cys:Cre) as functional markers of B-vitamin status. We also calculated the associations of these ratios to colorectal cancer (CRC) risk.Design: The relative contribution of potential confounders to the variance of the ratio-based B-vitamin markers was calculated by linear regression in a nested case-control study of 613 CRC cases and 1211 matched controls. Total B-vitamin status was represented by a summary score comprising Z-standardized plasma concentrations of folate, cobalamin, betaine, pyridoxal 5´-phosphate, and riboflavin. Associations with CRC risk were estimated using conditional logistic regression.Results: The ratio-based B-vitamin markers all outperformed tHcy as markers of total B-vitamin status, in both CRC cases and controls. Associations with CRC risk were similar for the ratio-based B-vitamin markers and total B-vitamin status (approximately 25% lower risk for high versus low B-vitamin status).Conclusions: Ratio-based B-vitamin markers were good predictors of total B-vitamin status, and displayed similar associations with CRC risk. Since tHcy and creatinine are routinely clinically analyzed, Hcy:Cre could be easily implemented in clinical practice to aid interpretation of tHcy results.
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| 2. |
- Myte, Robin, et al.
(author)
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Components of One-carbon Metabolism Other than Folate and Colorectal Cancer Risk
- 2016
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In: Epidemiology. - 1044-3983 .- 1531-5487. ; 27:6, s. 787-796
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Journal article (peer-reviewed)abstract
- BACKGROUND: Despite extensive study, the role of folate in colorectal cancer remains unclear. Research has therefore begun to address the role of other elements of the folate-methionine metabolic cycles. This study investigated factors other than folate involved in one-carbon metabolism, i.e., choline, betaine, dimethylglycine, sarcosine, and methionine and relevant polymorphisms, in relation to the risk of colorectal cancer in a population with low intakes and circulating levels of folate.METHODS: This was a prospective case-control study of 613 case subjects and 1,190 matched control subjects nested within the population-based Northern Sweden Health and Disease Study. We estimated odds ratios (OR) by conditional logistic regression, and marginal risk differences with weighted maximum likelihood estimation using incidence data from the study cohort.RESULTS: Higher plasma concentrations of methionine and betaine were associated with modest colorectal cancer risk reductions (OR [95% confidence interval {CI}] for highest versus lowest tertile: 0.76 [0.57, 0.99] and 0.72 [0.55, 0.94], respectively). Estimated marginal risk differences corresponded to approximately 200 fewer colorectal cancer cases per 100,000 individuals on average. We observed no clear associations between choline, dimethylglycine, or sarcosine and colorectal cancer risk. The inverse association of methionine was modified by plasma folate concentrations (OR [95% CI] for highest/lowest versus lowest/lowest tertile of plasma methionine/folate concentrations 0.39 [0.24, 0.64], Pinteraction = 0.06).CONCLUSIONS: In this population-based, nested case-control study with a long follow-up time from baseline to diagnosis (median: 8.2 years), higher plasma concentrations of methionine and betaine were associated with lower colorectal cancer risk. See Video Abstract at http://links.lww.com/EDE/B83.
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| 3. |
- Myte, Robin, et al.
(author)
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One-carbon metabolism biomarkers and genetic variants in relation to colorectal cancer risk by KRAS and BRAF mutation status
- 2018
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In: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:4
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Journal article (peer-reviewed)abstract
- Disturbances in one-carbon metabolism, intracellular reactions involved in nucleotide synthesis and methylation, likely increase the risk of colorectal cancer (CRC). However, results have been inconsistent. To explore whether this inconsistency could be explained by intertumoral heterogeneity, we evaluated a comprehensive panel of one-carbon metabolism biomarkers and some single nucleotide polymorphisms (SNPs) in relation to the risk of molecular subtypes of CRC defined by mutations in the KRAS and BRAF oncogenes. This nested case-control study included 488 CRC cases and 947 matched controls from two population-based cohorts in the Northern Sweden Health and Disease Study. We analyzed 14 biomarkers and 17 SNPs in prediagnostic blood and determined KRAS and BRAF mutation status in tumor tissue. In a multivariate network analysis, no variable displayed a strong association with the risk of specific CRC subtypes. A non-synonymous SNP in the CTH gene, rs1021737, had a stronger association compared with other variables. In subsequent univariate analyses, participants with variant rs1021737 genotype had a decreased risk of KRAS-mutated CRC (OR per allele = 0.72, 95% CI = 0.50, 1.05), and an increased risk of BRAF-mutated CRC (OR per allele = 1.56, 95% CI = 1.07, 2.30), with weak evidence for heterogeneity (Pheterogeneity = 0.01). This subtype-specific SNP association was not replicated in a case-case analysis of 533 CRC cases from The Cancer Genome Atlas (P = 0.85). In conclusion, we found no support for clear subtype-specific roles of one-carbon metabolism biomarkers and SNPs in CRC development, making differences in CRC molecular subtype distributions an unlikely explanation for the varying results on the role of one-carbon metabolism in CRC development across previous studies. Further investigation of the CTH gene in colorectal carcinogenesis with regards to KRAS and BRAF mutations or other molecular characteristics of the tumor may be warranted.
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| 4. |
- Myte, Robin, et al.
(author)
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Untangling the role of one-carbon metabolism in colorectal cancer risk : a comprehensive Bayesian network analysis
- 2017
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- The role of one-carbon metabolism (1CM), particularly folate, in colorectal cancer (CRC) development has been extensively studied, but with inconclusive results. Given the complexity of 1CM, the conventional approach, investigating components individually, may be insufficient. We used a machine learning-based Bayesian network approach to study, simultaneously, 14 circulating one-carbon metabolites, 17 related single nucleotide polymorphisms (SNPs), and several environmental factors in relation to CRC risk in 613 cases and 1190 controls from the prospective Northern Sweden Health and Disease Study. The estimated networks corresponded largely to known biochemical relationships. Plasma concentrations of folate (direct), vitamin B6 (pyridoxal 5-phosphate) (inverse), and vitamin B2 (riboflavin) (inverse) had the strongest independent associations with CRC risk. Our study demonstrates the importance of incorporating B-vitamins in future studies of 1CM and CRC development, and the usefulness of Bayesian network learning for investigating complex biological systems in relation to disease.
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