Colorectal cancer is known to arise from multiple tumorigenic pathways; however, the underlying mechanisms remain not completely understood. Metabolomics is becoming an increasingly popular tool in assessing biological processes. Previous metabolomics research focusing on colorectal cancer is limited by sample size and did not replicate findings in independent study populations to verify robustness of reported findings. Here, we performed a ultrahigh performance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (UHPLC‐QTOF‐MS) screening on EDTA plasma from 268 colorectal cancer patients and 353 controls using independent discovery and replication sets from two European cohorts (ColoCare Study: n = 180 patients/n = 153 controls; the Colorectal Cancer Study of Austria (CORSA) n = 88 patients/n = 200 controls), aiming to identify circulating plasma metabolites associated with colorectal cancer and to improve knowledge regarding colorectal cancer etiology. Multiple logistic regression models were used to test the association between disease state and metabolic features. Statistically significant associated features in the discovery set were taken forward and tested in the replication set to assure robustness of our findings. All models were adjusted for sex, age, BMI and smoking status and corrected for multiple testing using False Discovery Rate. Demographic and clinical data were abstracted from questionnaires and medical records.

Plasma metabolites and colorectal cancer stage

Sporadic colorectal cancer is characterized by a multistep progression from normal epithelium to precancerous low-risk and high-risk adenomas to invasive cancer. Yet, the underlying molecular mechanisms of colorectal carcinogenesis are not completely understood. Within the “Metabolomic profiles throughout the continuum of colorectal cancer” (MetaboCCC) consortium we analyzed data generated by untargeted, mass spectrometry-based metabolomics using plasma from 88 colorectal cancer patients, 200 patients with high-risk adenomas and 200 patients with low-risk adenomas recruited within the “Colorectal Cancer Study of Austria” (CORSA). Univariate logistic regression models comparing colorectal cancer to adenomas resulted in 442 statistically significant molecular features. Metabolites discriminating colorectal cancer patients from those with adenomas in our dataset included acylcarnitines, caffeine, amino acids, glycerophospholipids, fatty acids, bilirubin, bile acids and bacterial metabolites of tryptophan. The data obtained discovers metabolite profiles reflecting metabolic differences between colorectal cancer and colorectal adenomas and delineates a potentially underlying biological interpretation.

SummaryAs it became evident recently, extracellular DNA could be a versatile nutrient source of the facultative pathogen Vibrio cholerae along the different stages of its life cycle. By the use of two extracellular nucleases and periplasmic phosphatases, V. cholerae degrades extracellular DNA to nucleosides. In this study, we investigated the nucleoside uptake via identification and characterization of VCA0179, VC1953 and VC2352 representing the three nucleoside transport systems in V. cholerae. Based on our results VC2352 seems to be the dominant nucleoside transporter. Nevertheless, all three transporters are functional and can contribute to the utilization of nucleosides as a sole source of carbon or nitrogen. We found that the transcriptional activity of these three distal genes is equally promoted or antagonized by CRP or CytR respectively. Finally, mutants impaired for nucleoside uptake exhibit decreased transition fitness from the host into low carbon environments along the life cycle of V. cholerae.

Abstract Background Folates, including folic acid, may play a dual role in colorectal cancer development. Folate is suggested to be protective in early carcinogenesis but could accelerate growth of premalignant lesions or micrometastases. Whether circulating concentrations of folate and folic acid, measured around time of diagnosis, are associated with recurrence and survival in colorectal cancer patients is largely unknown. Methods Circulating concentrations of folate, folic acid, and folate catabolites p-aminobenzoylglutamate (pABG) and p-acetamidobenzoylglutamate (apABG) were measured by liquid chromatography–tandem mass spectrometry at diagnosis in 2024 stage I-III colorectal cancer patients from European and U.S. patient cohort studies. Multivariable-adjusted Cox proportional hazard models were used to assess associations between folate, folic acid, and folate catabolites concentrations with recurrence, overall and disease-free survival. Results No statistically significant associations were observed between folate, pABG, and apABG concentrations and recurrence, overall and disease-free survival, with hazard ratios (HRs) ranging from 0.92 to 1.16. The detection of folic acid in the circulation (yes/no) was not associated with any outcome. However, among patients with detectable folic acid concentrations (n = 296), a higher risk of recurrence was observed for each two-fold increase in folic acid (HR (95% confidence interval (95%CI): 1.31 (1.02 to 1.58)). No statistically significant associations were found between folic acid concentrations and overall and disease-free survival. Conclusions Circulating folate and folate catabolites concentrations at colorectal cancer diagnosis were not associated with recurrence and survival. However, caution is warranted for high blood concentrations of folic acid as they may increase the risk of colorectal cancer recurrence.

Dysregulation of tryptophan metabolism has been linked to colorectal tumorigenesis; however, epidemiological studies investigating tryptophan metabolites in relation to colorectal cancer risk are limited. We studied associations of plasma tryptophan, serotonin and kynurenine with colon cancer risk in two studies with cancer patients and controls, and in one prospective cohort: ColoCare Study (110 patients/153 controls), the Colorectal Cancer Study of Austria (CORSA; 46 patients/390 controls) and the European Prospective Investigation into Cancer and Nutrition (EPIC; 456 matched case‐control pairs). Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for colon cancer risk. Tryptophan was inversely associated with colon cancer risk in ColoCare (OR per 1‐SD = 0.44; 95% CI, 0.31‐0.64) and EPIC (OR per 1‐SD = 0.86; 95% CI, 0.74‐0.99). Comparing detectable vs nondetectable levels, serotonin was positively associated with colon cancer in CORSA (OR = 6.39; 95% CI, 3.61‐11.3) and EPIC (OR = 2.03; 95% CI, 1.20‐3.40). Kynurenine was inversely associated with colon cancer in ColoCare (OR per 1‐SD = 0.74; 95% CI, 0.55‐0.98), positively associated in CORSA (OR per 1‐SD = 1.79; 95% CI, 1.27‐2.52), while no association was observed in EPIC. The kynurenine‐to‐tryptophan ratio was positively associated with colon cancer in ColoCare (OR per 1‐SD = 1.38; 95% CI, 1.03‐1.84) and CORSA (OR per 1‐SD = 1.44; 95% CI, 1.06‐1.96), but not in EPIC. These results suggest that higher plasma tryptophan may be associated with lower colon cancer risk, while increased serotonin may be associated with a higher risk of colon cancer. The kynurenine‐to‐tryptophan ratio may also reflect altered tryptophan catabolism during colon cancer development.

Background B vitamins have been associated with the risk and progression of colorectal cancer (CRC), given their central roles in nucleotide synthesis and methylation, yet their association with quality of life in established CRC is unclear. Objectives To investigate whether quality of life 6 months postdiagnosis is associated with: 1) circulating concentrations of B vitamins and related biomarkers 6 months postdiagnosis; 2) changes in these concentrations between diagnosis and 6 months postdiagnosis; 3) B-vitamin supplement use 6 months postdiagnosis; and 4) changes in B-vitamin supplement use between diagnosis and 6 months postdiagnosis. Methods We included 1676 newly diagnosed stage I–III CRC patients from 3 prospective European cohorts. Circulating concentrations of 9 biomarkers related to the B vitamins folate, riboflavin, vitamin B6, and cobalamin were measured at diagnosis and 6 months postdiagnosis. Information on dietary supplement use was collected at both time points. Health-related quality of life (global quality of life, functioning scales, and fatigue) was assessed by the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire 6 months postdiagnosis. Confounder-adjusted linear regression analyses were performed, adjusted for multiple testing. Results Higher pyridoxal 5′-phosphate (PLP) was cross-sectionally associated with better physical, role, and social functioning, as well as reduced fatigue, 6 months postdiagnosis. Associations were observed for a doubling in the hydroxykynurenine ratio [3-hydroxykynurenine: (kynurenic acid + xanthurenic acid + 3-hydroxyanthranilic acid + anthranilic acid); an inverse marker of vitamin B6] and both reduced global quality of life (β = −3.62; 95% CI: −5.88, −1.36) and worse physical functioning (β = −5.01; 95% CI: −7.09, −2.94). Dose–response relations were observed for PLP and quality of life. No associations were observed for changes in biomarker concentrations between diagnosis and 6 months. Participants who stopped using B-vitamin supplements after diagnosis reported higher fatigue than nonusers. Conclusions Higher vitamin B6 status was associated with better quality of life, yet limited associations were observed for the use of B-vitamin supplements. Vitamin B6 needs further study to clarify its role in relation to quality of life.

DNA repair processes are involved in both the onset and treatment efficacy of colorectal cancer (CRC). A change of a single nucleotide causing an amino acid substitution in the corresponding protein may alter the efficiency of DNA repair, thus modifying the CRC susceptibility and clinical outcome. We performed a candidate gene approach in order to analyze the association of non-synonymous single nucleotide polymorphisms (nsSNPs) in the genes covering the main DNA repair pathways with CRC risk and clinical outcome modifications. Our candidate polymorphisms were selected according to the foremost genomic and functional prediction databases. Sixteen nsSNPs in 12 DNA repair genes were evaluated in cohorts from the Czech Republic and Austria. Apart from the tumor-node-metastasis (TNM) stage, which occurred as the main prognostic factor in all of the performed analyses, we observed several significant associations of different nsSNPs with survival and clinical outcomes in both cohorts. However, only some of the genes (REV3L, POLQ, and NEIL3) were prominently defined as prediction factors in the classification and regression tree analysis; therefore, the study suggests their association for patient survival. In summary, we provide observational and bioinformatics evidence that even subtle alterations in specific proteins of the DNA repair pathways may contribute to CRC susceptibility and clinical outcome.