| 1. |
- Gylling, Björn, 1978-, et al.
(författare)
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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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Ingår i: International Journal of Cancer. - : John Wiley & Sons. - 0020-7136 .- 1097-0215. ; 144:5, s. 947-956
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Tidskriftsartikel (refereegranskat)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. |
- Gylling, Björn, et al.
(författare)
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Vitamin B-6 and colorectal cancer risk : a prospective population-based study using 3 distinct plasma markers of vitamin B-6 status
- 2017
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 105:4, s. 897-904
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Tidskriftsartikel (refereegranskat)abstract
- Background: Higher plasma concentrations of the vitamin B-6 marker pyridoxal 5#-phosphate (PLP) have been associated with reduced colorectal cancer (CRC) risk. Inflammatory processes, including vitamin B-6 catabolism, could explain such findings. Objective: We investigated 3 biomarkers of vitamin B-6 status in relation to CRC risk. Design: This was a prospective case-control study of 613 CRC cases and 1190 matched controls nested within the Northern Sweden Health and Disease Study (n = 114,679). Participants were followed from 1985 to 2009, and the median follow-up from baseline to CRC diagnosis was 8.2 y. PLP, pyridoxal, pyridoxic acid (PA), 3-hydroxykynurenine, and xanthurenic acids (XAs) were measured in plasma with the use of liquid chromatography-tandem mass spectrometry. We calculated relative and absolute risks of CRC for PLP and the ratios 3-hydroxykynurenine: XA (HK: XA), an inverse marker of functional vitamin B-6 status, and PA:(PLP + pyridoxal) (PAr), a marker of inflammation and oxidative stress and an inverse marker of vitamin B-6 status. Results: Plasma PLP concentrations were associated with a reduced CRC risk for the third compared with the first quartile and for PLP sufficiency compared with deficiency [OR: 0.60 (95% CI: 0.44, 0.81) and OR: 0.55 (95% CI: 0.37, 0.81), respectively]. HK: XA and PAr were both associated with increased CRC risk [OR: 1.48 (95% CI: 1.08, 2.02) and OR: 1.50 (95% CI: 1.10, 2.04), respectively] for the fourth compared with the first quartile. For HK: XA and PAr, the findings were mainly observed in study participants with,10.5 y of follow-up between sampling and diagnosis. Conclusions: Vitamin B-6 deficiency as measured by plasma PLP is associated with a clear increase in CRC risk. Furthermore, our analyses of novel markers of functional vitamin B-6 status and vitamin B-6-associated oxidative stress and inflammation suggest a role in tumor progression rather than initiation.
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| 3. |
- Myte, Robin, et al.
(författare)
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Components of One-carbon Metabolism Other than Folate and Colorectal Cancer Risk
- 2016
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Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 27:6, s. 787-796
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Myte, Robin, et al.
(författare)
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Metabolic factors and the risk of colorectal cancer by KRAS and BRAF mutation status
- 2019
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Ingår i: International Journal of Cancer. - : John Wiley & Sons. - 0020-7136 .- 1097-0215. ; 145:2, s. 327-337
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Tidskriftsartikel (refereegranskat)abstract
- Factors related to energy metabolism and the metabolic syndrome, such as higher body mass index (BMI), blood glucose, or blood lipids, and blood pressure, are associated with an increased risk of colorectal cancer (CRC). However, CRC is a heterogeneous disease, developing through distinct pathways with differences in molecular characteristics and prognosis, and possibly also in risk factors. For subtypes defined by KRAS and BRAF mutation status, BMI is the only metabolic factor previously studied, with inconsistent findings. We investigated whether associations between BMI, blood glucose, blood lipids, and blood pressure and CRC risk differed by tumor KRAS and BRAF mutation status in 117,687 participants from two population-based cohorts within the Northern Sweden Health and Disease Study (NSHDS). Hazard ratios (HRs) for overall CRC and CRC subtypes by metabolic factors were estimated with Cox proportional hazards regression, using multiple imputation to handle missing exposure and tumor data. During a median follow-up of 15.6 years, we acquired 1,250 prospective CRC cases, of which 766 cases had complete baseline and molecular tumor data. Consistent with previous evidence, higher BMI, total cholesterol, triglyceride levels, and blood pressure were associated with an increased risk of overall CRC (HRs per 1 standard deviation increase: 1.07 to 1.12). These associations were similar regardless of CRC subtype by KRAS and BRAF mutation status (all pheterogeneity > 0.05). The same was true for subtypes based on microsatellite instability status. Poor metabolic health may therefore be a universal mechanism for colorectal cancer, acting across multiple developmental pathways.
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| 5. |
- Myte, Robin, 1989-
(författare)
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Metabolic Risk Factors and Molecular Subtypes of Colorectal Cancer
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Colorectal cancer (CRC) is a heterogeneous disease developing from distinct pathways, resulting in tumor subtypes with large differences in clinical and molecular characteristics. Molecular characteristics are increasingly being used clinically to guide therapy. However, whether molecular subtypes of CRC differ in etiology or risk factors is not clear. Clarifying such potential differences may lead to an improved understanding of CRC etiology, with implications for CRC prevention and screening.Aim: The aim of this thesis was to investigate whether risk factors related to energy metabolism, such as body fatness, and one-carbon metabolism, such as circulating B-vitamin status, were associated with specific subtypes of CRC defined by molecular characteristics of the tumor. Methods: These prospective studies are based on data and blood samples from cohorts within the population-based Northern Sweden Health and Disease Study (NSHDS). Prospective CRC cases with available archived tumor tissue were analyzed for key molecular features (KRAS and BRAF mutation status, Microsatellite instability (MSI) status, and CpG Island Methylator Phenotype (CIMP) status). Paper I was a cohort study of metabolic factors related to the metabolic syndrome (117 687 participants). Paper II was a nested-case control study on circulating insulin resistance-markers and adipokines (1010 cases and 1010 matched controls). Papers III and IV were nested case-control studies of one-carbon metabolism biomarkers and genetic variants (613 cases and 1190 matched controls).Results: In paper I, we observed associations between metabolic factors, such as BMI, blood pressure, and blood lipids, and CRC risk consistent with previous studies. These associations were similar regardless of tumor KRAS and BRAF mutation status. In paper II, circulating biomarkers of insulin resistance and adipokines were not associated with the risk of CRC or specific molecular subtypes of CRC defined by KRAS and BRAF mutation or MSI status. In paper III, higher circulating levels of metabolites involved in the methionine cycle (namely, betaine and methionine) were associated with a lower CRC risk. In paper IV, we found no support for clear subtype-specific roles of any circulating one-carbon metabolism biomarker or genetic variants in CRC development.Conclusions: The result of these prospective studies suggests that metabolic factors related to energy metabolism and one-carbon metabolism are generally associated with the risk of CRC, regardless of major subtypes defined by key molecular tumor features. If causal, metabolic risk factors likely influence the risk of colorectal cancer through more than one carcinogenic pathway.
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| 6. |
- Myte, Robin, et al.
(författare)
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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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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:4
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Myte, Robin, et al.
(författare)
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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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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)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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| 8. |
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| 9. |
- Wikberg, Maria L., et al.
(författare)
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Plasma miRNA can detect colorectal cancer, but how early?
- 2018
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Ingår i: Cancer Medicine. - : John Wiley & Sons. - 2045-7634. ; 7:5, s. 1697-1705
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Tidskriftsartikel (refereegranskat)abstract
- Colorectal cancer (CRC) is a major cause of deaths worldwide but has a good prognosis if detected early. The need for efficient, preferable non‐ or minimally invasive, inexpensive screening tools is therefore critical. We analyzed 12 miRNAs in pre‐ and postdiagnostic plasma samples to evaluate their potential as CRC screening markers. We used a unique study design with two overlapping cohorts, allowing analysis of pre‐ and postdiagnostic samples from 58 patients with CRC and matched healthy controls. Plasma concentrations of miR‐15b, ‐16, ‐18a, ‐19a, 21, ‐22, ‐25, ‐26a, ‐29c, ‐142‐5p, ‐150, and ‐192 were measured by semi‐quantitative real‐time PCR. Concentrations of miR‐18a, ‐21, ‐22, and ‐25 in plasma from patients with CRC were significantly altered compared to healthy controls. Combined as a multimarker panel, they detected CRC with an AUC of 0.93. Furthermore, levels of these three miRNAs also showed different levels in the prediagnostic case samples close to diagnosis. Only miR‐21‐levels were elevated several years before diagnosis. Plasma levels of miR‐18a, ‐21, ‐22, and ‐25 show promise as screening biomarkers for CRC. However, based on our unique analysis of prediagnostic and postdiagnostic samples from the same patients, we conclude that circulating miRNAs elevated at diagnosis may not automatically be suitable for CRC screening, if the increase occurs too close to clinical diagnosis.
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