Gene Polymorphisms Involved in Folate Metabolism and DNA Methylation with the Risk of Head and Neck Cancer

A new mathematical model of folate homeostasis in E. coli highlights the potential importance of the folinic acid futile cycle in cell growth

Folate (vitamin B9) plays a central role in one-carbon metabolism in prokaryotes and eukaryotes. This pathway mediates the transfer of one-carbon units, playing a crucial role in nucleotide synthesis, methylation, and amino acid homeostasis. The folinic acid futile cycle adds a layer of intrigue to this pathway, due to its associations with metabolism, cell growth, and dormancy. It also introduces additional complexity to folate metabolism. A logical way to deal with such complexity is to examine it by using mathematical modelling. This work describes the construction and analysis of a model of folate metabolism, which includes the folinic acid futile cycle. This model was tested under three in silico growth conditions. Model simulations revealed: 1) the folate cycle behaved as a stable biochemical system in three growth states (slow, standard, and rapid); 2) the initial concentration of serine had the greatest impact on metabolite concentrations; 3) 5-formyltetrahydrofolate cyclo-ligase (5-FCL) activity had a significant impact on the levels of the 7 products that carry the one-carbon donated from folates, and the redox couple NADP/NADPH; this was particularly evident in the rapid growth state; 4) 5-FCL may be vital to the survival of the cells by maintaining low levels of homocysteine, as high levels can induce toxicity; and 5) the antifolate therapeutic trimethoprim had a greater impact on folate metabolism with higher nutrient availability. These results highlight the important role of 5-FCL in intracellular folate homeostasis and mass generation under different metabolic scenarios.

DNA Methyltransferase Genes Are Associated with Oral Mucositis and Creatinine Levels in Oncopediatric Patients

The aim of this study was to investigate the association of single-nucleotide polymorphisms (SNPs) and the DNA methylation profiles of the DNA methyltransferase (DNMT) gene family with oral mucositis in children and adolescents with hematologic malignancies treated with methotrexate (MTX^®). The population was comprised of healthy and oncopediatric patients aged between 4 and 19 years. An evaluation of oral conditions was performed using the Oral Assessment Guide. Demographic, clinical, hematological, and biochemical data were obtained from medical records. Genomic DNA extracted from oral mucosal cells was used for the analysis of polymorphisms in DNMT1 (rs2228611), DNMT3A (rs7590760), and DNMT3B (rs6087990) using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique (n = 102) and for DNA methylation using the methylation-specific PCR (MSP) technique (n = 85). The allele and genotypic frequencies of SNPs did not reveal any differences between patients with or without oral mucositis. An increase in the methylation frequency for DNMT1 in patients recovered from mucositis was detected. The DNMT3A methylated profile associated with the CC genotype (SNP rs7590760) appeared to be connected to higher values of creatinine. In addition, the DNMT3B unmethylated profile associated with the CC genotype (SNP rs6087990) appeared to be connected with higher values of creatinine. We conclude that the DNMT1 methylation profile is associated with the post-mucositis period and that the genetic and epigenetic profiles of DNMT3A and DNMT3B are associated with creatinine levels.

A Paternal Methylation Error in the Congenital Hydrocephalic Texas (H-Tx) Rat Is Partially Rescued with Natural Folate Supplements

Folate deficiencies, folate imbalance and associated abnormal methylation are associated with birth defects, developmental delays, neurological conditions and diseases. In the hydrocephalic Texas (H-Tx) rat, 10-formyl tetrahydrofolate dehydrogenase (FDH) is reduced or absent from the CSF and the nuclei of cells in the brain and liver and this is correlated with decreased DNA methylation. In the present study, we tested whether impaired folate metabolism or methylation exists in sexually mature, unaffected H-Tx rats, which may explain the propagation of hydrocephalus in their offspring. We compared normal Sprague Dawley (SD, n = 6) rats with untreated H-Tx (uH-Tx, n = 6 and folate-treated H-Tx (TrH-Tx, n = 4). Structural abnormalities were observed in the testis of uH-Tx rats, with decreased methylation, increased demethylation, and cell death, particularly of sperm. FDH and FRα protein expression was increased in uH-Tx males but not in folate-treated males but tissue folate levels were unchanged. 5-Methylcytosine was significantly reduced in untreated and partially restored in treated individuals, while 5-hydroxymethylcytosine was not significantly changed. Similarly, a decrease in DNA-methyltransferase-1 expression in uH-Tx rats was partially reversed with treatment. The data expose a significant germline methylation error in unaffected adult male H-Tx rats from which hydrocephalic offspring are obtained. Reduced methylation in the testis and sperm was partially recovered by treatment with folate supplements leading us to conclude that this neurological disorder may not be completely eradicated by maternal supplementation alone.

A signature of immune-related gene pairs (IRGPs) for risk stratification and prognosis of oral cancer patients

Background

With low response to present immunotherapy, it is imperative to identify new immune-related biomarkers for more effective immunotherapies for oral cancer.

Methods

RNA profiles for 390 oral cancer patients and 32 normal samples were downloaded from The Cancer Genome Atlas (TCGA) database and differentially expressed genes (DEGs) were analyzed. Immune genesets from ImmPort repository were overlapped with DEGs. After implementing univariate Cox analysis and the least absolute shrinkage and selection operator (LASSO) Cox regression analysis, key immune-related gene pairs (IRGPs) among the overlapped DEGs for predicting the survival risk were obtained. Then, the cutoff of risk score was calculated by the receiver operating characteristic (ROC) curve to stratify oral cancer patients into high and low-risk groups. Multivariate Cox analysis was used to analyze independent prognostic indicators for oral cancer. Besides, infiltration of immune cells, functional annotation, and mutation analysis of IRGPs were conducted. Biological functions correlated with IRGPs were enriched by Gene Set Enrichment Analysis (GSEA) method.

Results

We identified 698 differentially expressed genes (DEGs) in response to oral cancer. 17 IRGPs among the DEGs were identified and integrated into a risk score model. Patients in the high-risk group have a significantly worse prognosis than those in the low-risk group in both training (P<0.001) and test (P=0.019) cohorts. Meanwhile, the IRGP model was identified as an independent prognostic factor for oral cancer. Different infiltration patterns of immune cells were found between the high- and low-risk groups that more types of T and B cells were enriched in the low-risk group. More immune-related signaling pathways were highly enriched in the low-risk group and Tenascin C (TNC) was the most frequently mutated gene. We have developed a novel 17-IRGPs signature for risk stratification and prognostic prediction of oral cancer.

Conclusion

Our study provides a foundation for improved immunotherapy and prognosis and is beneficial to the individualized management of oral cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02630-1.

MTHFD1 c.1958G>A and TCN2 c.776G>C polymorphisms of folate metabolism genes and their implication for oral cavity cancer

Background

Cancers of the head and neck can damage the brain, spinal cord, and nerves, as well as the sense organs responsible for contact with the outside world. Oncogenic transformation occurs following mutations that change the function of specific genes, such tumor suppressor genes or oncogenes, and their encoded protein products. Therefore, the aim of this study was to evaluate the relationship between the occurrence of MTHFD1 c.1958G>A and TCN2 c.776G>C gene polymorphisms and the risk of oral cavity cancer.

Materials and methods

The study population consisted of 439 patients and 200 healthy subjects. Genomic DNA was extracted from peripheral blood and from paraffin-embedded tissue. Analysis of the gene polymorphisms was performed using polymerase chain reaction–restriction fragment length polymorphism.

Results

Statistically significant differences were found in the distribution of genotypes of the rs2236225 and rs1801198 polymorphisms between patients and controls. Regarding MTHFD1 c.1958G>A, the GA genotype (p<0.0001, OR = 2.91, 95% CI = 1.88–4.49-GA) was more common among patients than healthy subjects. Regarding TCN2 c.776G>C, the frequency of CC genotype (p< 0.0001, OR = 0.17, 95% CI = 0.10–0.33-CC) was significantly less common among patients than healthy subjects. Tobacco smoking, alcohol use, and male gender (p<0.0001) were found to be predictors of the disease.

Conclusion

The results suggest that the MTHFD1 c.1958G>A polymorphism may be associated with a greater risk of oral cavity cancer, whereas a protective effect has been found for the TCN2 c.776G>C polymorphism.