Impact of the MTHFR C677T polymorphism on colorectal cancer in a population with low genetic variability

C677T and A1298C MTHFR gene polymorphisms and response to fluoropyrimidine-based chemotherapy in Mestizo patients with metastatic colorectal cancer

OBJECTIVE

To assess the association between C677T and A1298C methylenetetrahydrofolate reductase (MTHFR) single-nucleotide polymorphisms (SNPs) and response to first-line fluoropyrimidine-based chemotherapy for metastatic colorectal adenocarcinoma.

METHODS

A total of 68 patients were prospectively followed up in San Juan de Dios Hospital (San José, Costa Rica) from January 2019 to November 2020. Patients received first-line therapy with capecitabine or 5-fluorouracil in combination with oxaliplatin or irinotecan. Germline and somatic DNA was extracted from blood samples and paraffin-embedded tissue, respectively. Overall response rate (partial response + complete response) was assessed according to RECIST 1.1 criteria. Cox regression models were performed to identify the effect of MTHFR C677T and A1298C SNPs on progression-free survival (PFS) and overall survival (OS) (NCT registration number: 03852290).

RESULTS

Patients harboring one or both T alleles of the MTHFR C677T SNP had better overall response than homozygous wild-type individuals [odds ratio (OR): 3.21; 95% confidence interval (CI), 1.05-9.81; P = 0.03]. No association was found between the MTHFR A1298C genotypes and overall response (OR: 0.75; 95% CI, 0.26-2.20; P = 0.60). Patients with the MTHFR 677 TT and CT genotypes had longer PFS than CC individuals (hazard ratio: 0.53; 95% CI, 0.28-0.98; P = 0.045), even after adjustment for confounders (hazard ratio: 0.50; 95% CI, 0.25-0.98; P = 0.04). We found no association between the MTHFR A1298C SNP and PFS (hazard ratio: 1.35; 95% CI, 0.72-2.55; P = 0.34). None of the SNPs was associated with OS.

CONCLUSION

Patients carrying at least one mutant allele of the MTHFR C677T SNP had a better overall response and longer PFS than wild-type homozygous patients.

Methylenetetrahydrofolate reductase polymorphisms and colorectal cancer prognosis: A meta-analysis

Background

The present study focused on understanding the prognostic value of the methylenetetrahydrofolate reductase (MTHFR) single nucleotide polymorphisms rs1801133 (C667T) and rs1801131 (A1298C) in patients with colorectal cancer (CRC).

Methods

A systematic literature search was conducted in March 2016. Databases, including Medline, EMBASE, Cochrane and Chinese databases (including CNKI, Wanfang and VIP), were searched to identify the relevant articles describing MTHFR polymorphisms in patients with CRC. Data regarding overall survival (OS), progression‐free survival (PFS) and disease‐free survival (DFS) were collected and analysed.

Results

Twenty‐four studies with 5423 patients with CRC were included. Significant differences in OS, PFS and DFS were not observed among the different comparisons of patients carrying different alleles of the MTHFR rs1801133 polymorphism (including TT versus CC, TT versus CT + CC, CT + TT versus CC and CT versus CC). Compared with patients with the rs1801131 CA + AA genotypes, patients with the CC genotype had a shorter OS (hazard ratio = 1.85; 95% confidence interval = 1.30–2.65) and DFS (hazard ratio = 2.16; 95% confidence interval= 1.19–3.93). Significant differences in OS, PFS and DFS were not observed among the other patient groups (including CC versus AA, CC + CA versus AA and CA versus AA). Subgroup analysis of rs1801133 and rs1801131 showed that patients with CRC from Asian regions and Western regions demonstrated similar results.

Conclusions

The MTHFR rs1801133 polymorphism was not associated with the prognosis of patients with CRC; however, rs1801131 may be associated with the prognosis of patients with CRC. Well‐designed prospective studies are necessary to obtain a better understanding of the prognostic value of rs1801133 and rs1801131.

Methylenetetrahydrofolate reductase C677T polymorphism and colorectal cancer susceptibility: a meta-analysis

The association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and colorectal cancer (CRC) susceptibility has been researched in numerous studies. However, the results of these studies were controversial. Therefore, the objective of this meta-analysis was to offer a more convincible conclusion about such association with more included studies. Eligible studies published till May 1, 2017 were searched from PubMed, Embase, Web of Science, and CNKI database about such association. Pooled odds ratios (ORs) together with 95% confidence intervals (CIs) were calculated to evaluate such association. And the Begg's funnel plot and Egger's test were applied to assess the publication bias. This meta-analysis contained 37049 cases and 52444 controls from 87 publications with 91 eligible case-control studies. Because of lack of data for a particular genotype in several studies, all the included studies were analysed barely in the dominant model. Originally, there was no association between MTHFR C677T polymorphism and CRC susceptibility (OR =0.99, 95% CI =0.94-1.05). After excluding 13 studies according to their heterogeneity and publication bias, rs1801133 polymorphism was found to reduce the risks of CRC significantly (OR =0.96, 95% CI =0.94-0.99). In the subgroup analysis of ethnicity, there was a significant association in Asians (OR =0.94, 95% CI =0.89-1.00). Furthermore, when stratified by the source of controls and genotyping methods, the positive results were observed in population-based control group (OR =0.97, 95% CI =0.93-1.00) and PCR-restriction fragment length polymorphism (PCR-RFLP) method (OR =0.95, 95% CI =0.91-0.99. The results of the meta-analysis suggested that MTHFR C677T polymorphism was associated with CRC susceptibility, especially in Asian population.

MTHFR C677T polymorphism and anatomopathological characteristics with prognostic significance in sporadic colorectal cancer

Methylenetetrahydrofolate reductase (MTHFR) plays a key role in folate metabolism, and folate is implicated in carcinogenesis due to its role in DNA methylation, repair and synthesis. The MTHFR C677T polymorphism is associated with decreased risk of CRC and increased sensitivity to 5-FU treatment. The present study addressed the relationship between this polymorphism and histopathological and immunohistochemical characteristics of prognostic significance in 50 patients from the Canary Islands. No differences were found between the MTHFR C677T genotypes with respect to tumor budding, tumor necrosis, desmoplastic fibrosis and tumoral eosinophilia. No significant differences were found in Ki-67, bcl-2 (cytoplasmic and nuclear), CD31, CD3+ T lymphocytes (both stromal and intraepithelial) and peritumoral CD20+ B lymphocytes. In carriers of the MTHFR CC variant, tumor margins were infiltrative more frequently (68.7%) than in CT+TT carriers (33.3%, p=0.03). In addition, wild-type CC genotype showed stromal CD20+ B lymphocytes (68.8%) more often than CT+TT carriers (33.3%, p=0.03). Both parameters indicate a better tumor prognosis when the MTHFR 677T variant is present.

Red blood cell folate and plasma folate are not associated with risk of incident colorectal cancer in the Women's Health Initiative observational study

The relationship between folate and colorectal cancer (CRC) risk is unclear. We investigated the association of two biomarkers of folate status, plasma folate and red blood cell (RBC) folate, with CRC risk using a nested case-control design in the Women's Health Initiative Observational Study. Postmenopausal women (n = 93,676) aged 50-79 years were enrolled in the Women's Health Initiative Observational Study (1993-1998). A fasting blood draw and extensive health, dietary and lifestyle data were collected upon enrollment. Through 2008, 988 incident CRC cases were reported and confirmed with medical records adjudication. Cases and controls were matched on age (± 3 years), enrollment date (± 1 year), race/ethnicity, blood draw date (± 6 months) and hysterectomy status. Plasma and RBC folate were determined by radio assay. Folate biomarker values were divided into quartiles, and conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CI) for the associations of folate with total CRC, by tumor site and by stage at diagnosis. Additional analyses examined whether risks varied across time periods corresponding to the United States folic acid fortification policy: prefortification (1994-1995), perifortification (1996-1997) and postfortification (1998). ORs for overall CRC risk comparing Q4 vs. Q1 were 0.91 (95% CI 0.67-1.24) and 0.91 (95% CI 0.67-1.23) for RBC and plasma folate, respectively. There were no changes in risk attributable to food supply fortification. These results do not support an overall association of folate with CRC risk and suggest that folic acid fortification of the US food supply did not alter the associations in these postmenopausal women.

Hyperhomocysteinemia as a potential contributor of colorectal cancer development in inflammatory bowel diseases: A review

Homocysteine is an amino acid generated metabolically by the S-adenosylmethionine-dependent transmethylation pathway. In addition to being a well-known independent risk factor for coronary heart disease, is also a risk factor for cancer. Patients suffering from inflammatory bowel diseases (IBD) including ulcerative colitis and Crohn’s disease are at increased risk of developing colorectal cancer in comparison to healthy individuals. Furthermore, the risk of hyperhomocysteinaemia is significantly higher in IBD patients when compared with controls. In the present article, we review the mechanisms in which hyperhomocysteinemia may contribute to increased risk of colorectal cancer in IBD patients.

Recent studies of 5-fluorouracil resistance in pancreatic cancer

Resistance to 5-fluorouracil (5-FU), an important anticancer drug, is a serious challenge in the treatment of pancreatic cancer. Equilibrative nucleoside transporter 1 and multidrug-resistance protein (MRP) 5 and MRP8, rather than P-glycoprotein, play important roles in 5-FU transport. Thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase and thymidine phosphorylase are four key enzymes involved in 5-FU metabolism. Other metabolic enzymes, including uridine monophosphate synthetase, also contribute to chemoresistance. Intracellular signaling pathways are an integrated network, and nuclear factor kappa-light-chain-enhancer of activated B cells, AKT and extracellular signal-regulated kinases are signaling pathways that are particularly relevant to 5-FU resistance. In addition, recent reports indicate that STAT-3 is a crucial survival protein. Proteomic assays provide a powerful tool for identifying target proteins and understanding the role of microRNAs and stromal factors to facilitate the development of strategies to combat 5-FU resistance.

MTHFR C677T polymorphism contributes to the risk for gastric cancer

Methylenetetrahydrofolate reductase (MTHFR) has been demonstrated to be involved in carcinogenesis. Increasing individual studies have investigated the role of MTHFR C677T polymorphism in gastric cancer pathogenesis, but with inconsistent findings. The aim of this study was to clarify the potential association of the MTHFR C677T polymorphism with gastric cancer risk by pooling all available data from published case-control studies. We searched the PubMed, Embase, Web of Science, and Wanfang databases for all relevant publications to date. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95% CI) was calculated. Stratified analysis and sensitivity analysis were also carried out to estimate the strength of this association. A total of 25 case-control studies with 6,572 cases and 9,584 controls were retrieved. Overall, the ORs under five contrast models indicated that the MTHFR C677T variant was positively associated with gastric cancer risk (ORT vs. C = 1.21, 95% CI 1.10–1.34, P(OR) < 0.001; OR(TT vs. CC) = 1.47, 95% CI 1.22–1.76, P(OR) < 0.001; OR(TC vs. CC) = 1.20, 95% CI 1.03-1.40, P(OR) = 0.022; OR(TT + TC vs. CC) = 1.27, 95% CI 1.10-1.47, P(OR) = 0.001; OR(TT vs. CC + TC) = 1.29, 95% CI 1.15-1.46, P(OR) < 0.001). Stratified analyses according to ethnicity and source of controls further confirmed the significant correlations. The current meta-analysis provides strong evidence that the MTHFR C677T polymorphism may be a risk factor for gastric cancer among Asians and Caucasians.

Genome-wide screening for understanding the role of DNA methylation in colorectal cancer

DNA methylation analysis methods have undergone an impressive revolution over the past 15 years. Regarding colorectal cancer (CRC), the localization and distribution of several differently methylated genes have been determined by genome-wide DNA methylation assays. These genes do not just influence the pathogenesis of CRC, but can be used further as diagnostic or prognostic markers. Moreover, the identified four DNA methylation-based subgroups of CRC have important clinical and therapeutic merit. Since genome-wide DNA methylation analyzes result in a large amount of data, there is a need for complex bioinformatic and pathway analysis. Future challenges in epigenetic alterations of CRC include the demand for comprehensive identification and experimental validation of gene abnormalities. By introduction of genome-wide DNA methylation profiling into clinical practice not only the patients' risk stratification but development of targeted therapies will also be possible.