Association between the MTHFR C677T Polymorphism and Breast Cancer Risk: A Meta-Analysis of 23 Case-Control Studies

C677T and A1298C methylenetetrahydrofolate reductase polymorphisms and breast cancer susceptibility among Latinos: a meta-analysis

BACKGROUND

Previous meta-analyses have shown an ethnic dependency of the C677T and the A1298C methylenetetrahydrofolate reductase (MTHFR) polymorphisms, with no focus on the Latino population. For Latinos, many studies have examined these polymorphisms and breast cancer susceptibility, yielding no concise result. Therefore, we undertook this meta-analysis to determine the effect these polymorphisms have on breast cancer risk for Latinos.

METHODS

PubMed, EBSCO, LILACS, Scopus, and Latin American-specific databases were searched for studies exploring the association between the MTHFR polymorphisms and breast cancer susceptibility in Latinos until January 2019. Genotype distributions were extracted and, depending on the level heterogeneity determined by the ψ²-based Q test and the I² test, fixed-effects or random-effects models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) for the heterozygous, homozygous, dominant, recessive, and allelic genetic models. No publication bias was detected by the Begg-Mazumdar's test and Egger's test.

RESULTS

Of the 280 retrieved publications, 9 studies were included: 9 for the C677T polymorphism and 5 for the A1298C polymorphism. For the C677T polymorphism, there was an elevated risk for the homozygous (OR 1.42, 95% CI 1.05-1.92), the dominant (OR 1.16, 95% CI 1.02-1.31), the recessive (OR 1.33, 95% CI 1.01-1.75), and the allelic model (OR 1.17, 95% CI 1.03-1.33, p < 0.01). No association between the A1298C polymorphism and the risk to develop breast cancer was determined.

CONCLUSION

The results indicated that, for Latinos, the C677T polymorphism is associated with a significant risk for developing breast cancer, whereas the A1289C polymorphism does not.

A Genetic Variant of rs145204276 in the Promoter Region of Long Noncoding RNA GAS5 Is Associated With a Reduced Risk of Breast Cancer

INTRODUCTION

Growth arrest-specific 5 (GAS5), downregulated in breast cancer (BC), functions as a tumor suppressor by affecting tumor growth and cell apoptosis in vivo and in vitro. This study was designed to determine whether an insertion (ins)/deletion (del) polymorphism (rs145204276 AGGCA/-) in the promoter region of GAS5 was a susceptibility gene to the occurrence of BC.

PATIENTS AND METHODS

A hospital-based case-control study was conducted and the GAS5 rs145204276 genotype was analyzed in 575 sporadic BC patients and 602 controls to test the association between the polymorphism and BC risk. Further functional analysis was performed to evaluate the effect of the polymorphism on the promoter activity and GAS5 expression levels using quantitative polymerase chain reaction and dual luciferase reporter assay.

RESULTS

The prevalence of BC was lower in carriers with rs145204276 ins/del and del/del genotypes compared with those with ins/ins genotype (adjusted odds ratio [OR], 0.74; 95% confidence interval [CI], 0.58-0.92; P = .009). An allelic test for association with BC was also significant (del vs. ins: adjusted OR, 0.78; 95% CI, 0.65-0.93; P = .007). Genotype-phenotype analysis revealed that individuals with rs145204276 ins/del and del/del genotypes expressed significantly higher levels of GAS5. Luciferase reporter analysis revealed that rs145204276 del allele enhanced the promoter activity of GAS5.

CONCLUSION

The rs145204276 del allele might protect against the development of BC via inducing the promoter activity by binding to transcriptional factor specificity protein 1, and finally resulting in higher levels of GAS5.

The association between MTHFR polymorphism and cervical cancer

Cervical cancer is an extremely prevalent disease worldwide. The purpose of this study was to illustrate the relationship between methylenetetrahydrofolate reductase (MTHFR) polymorphisms or methionine synthase reductase (MTRR) polymorphisms and cervical cancer. There were 372 women who performed genetic and folic acid assessments. For the MTHFR C677T, there was no significant difference in the distribution of C allele and T allele in the three groups. However, the mutant C allele of MTHFR A1298C was significantly higher in the cancer group than in the normal group. Similarly, the mutant G allele of MTRR A66G was also higher than the normal group. The serum folic acid levels were gradually decreased with the development of cervical lesions. Serum folate levels in 4–9 ng/ml and ≤4 ng/ml were both significantly associated with cervical cancer risk. However, the MTHFR C677T polymorphism was not associated with the risk of cervical cancer or CIN. In contrast, the MTHFR A1298C polymorphism could increase the risk of both cervical cancer and CIN. In addition, the MTRR A66G polymorphism was only associated with the risk of cervical cancer but not CIN.