MTHFR rs1801133 polymorphism and susceptibility to colorectal cancer in Iranian population: evidence of a case-control study and meta-analysis

Meta Analysis of Methylenetetrahydrofolate Reductase (MTHFR) C677T polymorphism and its association with folate and colorectal cancer

BACKGROUND

DNA hypomethylation and uracil misincorporation into DNA, both of which have a very important correlation with colorectal carcinogenesis. Folate plays a crucial role in DNA synthesis, acting as a coenzyme in one-carbon metabolism, which involves the synthesis of purines, pyrimidines, and methyl groups. MTHFR, a key enzyme in folate metabolism, has been widely studied in relation to neural tube defects and hypertension, but its role in colorectal cancer remains underexplored. Therefore, understanding the role of folate and MTHFR genes in colorectal cancer may be helpful for potential preventive or therapeutic interventions. In this meta-analysis, the effects of MTHFR genotype and folate intake on colorectal cancer incidence were analyzed.

METHODS

We searched PubMed,Embase, Web of Science, and CNKI database to identify relevant studies up to January 2024. We included a series of studies on the association of MTHFR C677T genotype and folate intake with colorectal cancer incidence. The meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P). It included 100 studies (39702 cases and 55718 controls),that investigated the association between the MTHFR C677T polymorphism and colorectal cancer (CRC). Additionally, the analysis incorporated further stratification by ethnic population and geographical region. Furthermore, Six of the studies which clarified high amount of folate might be a protective factor for CRC in all three MTHFR C677T genotype, especially in TT genotype.

RESULTS

MTHFR 677TT genotype was negatively associated with CRC incidence compared with CC genotype (OR = 0.89; 95% CI: 0.85-0.93; P < 0.00001; Z = 5.17). MTHFR 677CT genotype was not significantly associated with colorectal cancer incidence (OR = 1.00; 95% CI: 0.98,1.03). A negative correlation between TT genotype and CRC was observed in ethnics of Asians (OR = 0.83, 95% CI: 0.76, 0.91), Caucasians (OR = 0.93, 95% CI: 0.88, 0.99) and the region of USA (OR = 0.77, 95% CI: 0.71, 0.85), Asia (OR = 0.93, 95% CI: 0.86, 1.00) and Europe (OR = 0.93, 95% CI:0.87, 1.00),but not in Indian (TT: OR = 1.67, 95% CI: 1.06, 2.63; CT: OR = 1.31, 95% CI: 1.00, 1.73)). Amount folate intakes might reduce the morbidity of CRC for people in MTHFR 677TT genotype (OR = 0.68; 95% CI: 0.48,0.96; P = 0.03).

CONCLUSION

The analysis showed that the incidence of colorectal cancer was reduced among individuals with TT genotype. The individuals with TT genotype and amount folate intake may collectively improve the incidence of colorectal cancer. While the MTHFR 677TT genotype is associated with a reduced risk of CRC, especially in certain populations, these findings should be interpreted with caution due to the limitations of retrospective studies.

Association of MTHFR C677T variant genotype with serum folate and Vit B12 in Iranian patients with colorectal cancer or adenomatous polyps

Background

The incidence of colorectal cancer (CRC) has increased during recent years in Iran and other developing countries. Clinical studies suggest that essential folate dietary intake and moderate deficiency of methylenetetrahydrofolate reductase (MTHFR) may protect and reduce the risk of CRC. The present study aimed to investigate the clinical significance of C677T polymorphism within the MTHFR gene and its correlation with the serum folate and Vit B₁₂ in the Iranian population suffering from CRC.

Methods

Blood samples were taken from 1017 Iranian individuals (517 cases and 500 controls) who were referred for colonoscopy. TaqMan probe assay was performed for C677T MTHFR polymorphism. Sera were fractionated from the blood samples of 43 patients and controls and folate and Vit B₁₂ concentrations were measured by a monobind kit. The correlation of MTHFR polymorphisms and folate/vitamin-B₁₂ with CRC risk was analyzed.

Results

In the current study, we found the frequency of three different genotypes of MTHFR polymorphism in the Iranian population i.e., CC, CT, and TT, to be 51.31, 26.73, 21.96 and 61, 32.2, 6.8 in case and control groups, respectively. The homozygote genotype of MTHFR rs1801133 polymorphism is associated with an increased risk of CRC by 3.68, 1.42, and 3.74-fold in codominant, dominant, and recessive models respectively (p value < 0.01). Our study revealed that there was no significant difference between the amount of folate and Vit B12 in the case and control groups (p value > 0.05).

Conclusions

This study revealed that there was no significant difference between the amount of folate and Vit B₁₂ in the case and control groups. Furthermore, our results demonstrated a higher risk association for 677TT and 677TT + C677T genotypes of MTHFR compared with 677CC carriers among CRC patients.

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.

Lack of association of CASC8 rs1447295 with colorectal cancer in Iranian population: A multicenter case-control study

Several studies reported the potential role of the rs1447295 polymorphism in susceptibility to cancer. This variant located in the cancer susceptibility candidate 8 (CASC8) is a long noncoding RNA (lnRNA) gene and does not code protein. LnRNA transcripts play a potential regulatory role in the expression of key genes involved in multiple cellular pathways, including cell cycle, pluripotency, and immune response. The aim of this study is to evaluate this association with colorectal cancer (CRC) in a large case-control study of the Iranian population. After extraction of genomic DNA by the standard protocols, the rs1447295 was genotyped in 2416 subjects (46% patients). Results of this case-control demonstrated no significant association between the rs1447295 polymorphism and risk of CRC or its characteristics under allele or alternative genotype models. In conclusion, it is unlikely that the rs1447295 polymorphism is a risk variant for the development of CRC in Iranian population.

MTRR rs1801394 and its interaction with MTHFR rs1801133 in colorectal cancer: a case-control study and meta-analysis

AIM

This study aims to evaluate the association between the MTRR rs1801394 alone or in interaction with the MTHFR rs1801133 and susceptibility to colorectal cancer (CRC) and its characteristics in Iranian population. Additionally, both a systematic review and meta-analysis were performed to derive a more precise assessment of this association.

MATERIALS & METHODS

Genomic DNA of 2332 subjects was genotyped for rs1801394. These data were pooled with 17 eligible studies for meta-analysis.

RESULTS

No significant association was found between the rs1801394 or rs1801394-rs1801133 and CRC risk. Meta-analysis results also demonstrated no significant relationship between the rs1801394 and CRC risk.

CONCLUSION

Results of this study showed that the rs1801394 alone or together with the rs1801133 is not a risk factor for CRC in Iranian population.