Sex Differences in mRNA Expression of Reduced Folate Carrier-1, Folypolyformyl Glutamate Synthase, and γ-Glutamyl Hydrolase in a Healthy Japanese Population

Effects of single nucleotide polymorphisms of the folylpolyglutamate synthase gene on pemetrexed administration-induced nephropathy

AIMS

Long-term administration of pemetrexed (PEM) in patients with lung cancer can cause renal damage, leading to treatment discontinuation. Previous reports have suggested that specific single nucleotide polymorphisms (SNPs) in the folylpolyglutamate synthase (FPGS) gene affect therapeutic efficacy; however, whether the FPGS SNPs affect renal function is unclear. Identifying SNPs related to renal damage during PEM administration may help predict the decrease in renal function caused by PEM.

METHODS

We retrospectively examined age, sex, body weight, total administered PEM, combined platinum, estimated glomerular filtration rate (eGFR) and serum creatinine (SCr) levels before and after PEM administration in patients with non-small cell lung cancer and searched for the alleles of FPGS SNPs (rs1544105 and rs10106) using DNA extracted from whole blood samples of patients.

RESULTS

Renal function decreased after PEM administration in 26 cases overall. The SCr and eGFR indices showed decreased renal function irrespective of concomitant cisplatin use. Based on promoter activity and miRNA binding predictions, rs1544105-C and rs10106-T were hypothesized to increase FPGS expression. Single SNP analyses showed no significant differences in renal function between groups with and without each SNP. Multiple regression analysis revealed that the most significant factors for decreased renal function were sex on SCr and the number of SNPs on eGFR. In subgroup analyses, the patients with rs10106-T showed a decline in renal function in the older group.

CONCLUSIONS

The number of FPGS SNPs may contribute to PEM-induced renal impairment. Detecting FPGS SNPs may help predict PEM-induced renal damage.

Metabolic Phenotype of Wild-Type and As3mt-Knockout C57BL/6J Mice Exposed to Inorganic Arsenic: The Role of Dietary Fat and Folate Intake

BACKGROUND

Inorganic arsenic (iAs) is a diabetogen. Interindividual differences in iAs metabolism have been linked to susceptibility to diabetes in iAs-exposed populations. Dietary folate intake has been shown to influence iAs metabolism, but to our knowledge its role in iAs-associated diabetes has not been studied.

OBJECTIVE

The goal of this study was to assess how folate intake, combined with low-fat (LFD) and high-fat diets (HFD), affects the metabolism and diabetogenic effects of iAs in wild-type (WT) mice and in As3mt-knockout (KO) mice that have limited capacity for iAs detoxification.

METHODS

Male and female WT and KO mice were exposed to 0 or [Formula: see text] iAs in drinking water. Mice were fed the LFD containing [Formula: see text] or [Formula: see text] folate for 24 weeks, followed by the HFD with the same folate levels for 13 weeks. Metabolic phenotype and iAs metabolism were examined before and after switching to the HFD.

RESULTS

iAs exposure had little effect on the phenotype of mice fed LFD regardless of folate intake. High folate intake stimulated iAs metabolism, but only in WT females. KO mice accumulated more fat than WT mice and were insulin resistant, with males more insulin resistant than females despite similar %fat mass. Feeding the HFD increased adiposity and insulin resistance in all mice. However, iAs-exposed male and female WT mice with low folate intake were more insulin resistant than unexposed controls. High folate intake alleviated insulin resistance in both sexes, but stimulated iAs metabolism only in female mice.

CONCLUSIONS

Exposure to [Formula: see text] iAs in drinking water resulted in insulin resistance in WT mice only when combined with a HFD and low folate intake. The protective effect of high folate intake may be independent of iAs metabolism, at least in male mice. KO mice were more prone to developing insulin resistance, possibly due to the accumulation of iAs in tissues. https://doi.org/10.1289/EHP3951.