Mutation Screening and Association Study of the Folylpolyglutamate Synthetase (FPGS) Gene with Susceptibility to Childhood Acute Lymphoblastic Leukemia

The impact of genetic variations in FPGS , MTHFR , and ATIC on methotrexate response among pediatric patients with acute lymphoblastic leukemia

OBJECTIVES

Genetic polymorphisms in FPGS , MTHFR , and ATIC have emerged as important modulators of methotrexate (MTX) metabolism and toxicity. We investigated the distribution of FPGS rs10106, MTHFR rs1801131, and ATIC rs2372536 polymorphisms in children with acute lymphoblastic leukemia (ALL) and assessed their influence on MTX concentrations, toxicity profiles, and clinical outcomes.

METHODS

Genotyping of FPGS rs10106 G > A, MTHFR rs1801131 A > C, and ATIC rs2372536 C > G polymorphisms was conducted using the Sequenom MassARRAY iPLEX platform in 145 pediatric ALL patients.

RESULTS

Significant ethnic differences were observed in the allelic and genotypic distributions of the three single nucleotide polymorphisms (SNPs) investigated. None of these three SNPs had a significant effect on MTX levels or toxicities. The frequencies of the ATIC rs2372536 CC genotype and C allele in ALL patients (44.8% and 68.6%, respectively) were significantly lower than those in Han Chinese in Beijing, China (58.3% and 78.2%, respectively; P  = 0.036 and 0.019, respectively). Patients carrying the ATIC rs2372536 GG genotype (36.4%, 4/11) had a significantly higher relapse rate than the CC genotype carriers (6.2%, 4/65, P  = 0.013). There, however, were no significant effects on relapse-free survival in Kaplan-Meier and Cox regression analyses for all three candidate SNPs.

CONCLUSION

Our findings offer valuable insights into the intricate interplay between genetic polymorphisms, MTX exposure, toxicities, and clinical outcomes in patients with ALL and have the potential to inform precision medicine strategies.

Research progress on gene mutations and drug resistance in leukemia

Leukemia is a type of blood cancer characterized by the uncontrolled growth of abnormal cells in the bone marrow, which replace normal blood cells and disrupt normal blood cell function. Timely and personalized interventions are crucial for disease management and improving survival rates. However, many patients experience relapse following conventional chemotherapy, and increasing treatment intensity often fails to improve outcomes due to mutated gene-induced drug resistance in leukemia cells. This article analyzes the association of gene mutations and drug resistance in leukemia. It explores genetic abnormalities in leukemia, highlighting recently identified mutations affecting signaling pathways, cell apoptosis, epigenetic regulation, histone modification, and splicing mechanisms. Additionally, the article discusses therapeutic strategies such as molecular targeting of gene mutations, alternative pathway targeting, and immunotherapy in leukemia. These approaches aim to combat specific drug-resistant mutations, providing potential avenues to mitigate leukemia relapse. Future research with these strategies holds promise for advancing leukemia treatment and addressing the challenges of drug-resistant mutations to improve patient outcomes.

Interethnic Differences in Single and Haplotype Structures of Folylpolyglutamate Synthase and Gamma-glutamyl Hydrolase Variants and Their Influence on Disease Susceptibility to Acute Lymphoblastic Leukemia in the Indian Population: An Exploratory Study

Aim: We aim to establish the genotype and haplotype frequencies of folylpolyglutamate synthase (FPGS rs10106 and rs1544105) and gamma-glutamyl hydrolase (GGH rs3758149 and rs11545078) variants in the South Indian population (SI) and to study the association of these variants with susceptibility to acute lymphoblastic leukemia (ALL). We also aim to compare the genotype and haplotype frequencies of studied variants with those of superpopulations from the 1000 Genomes Project collected in phase-3 and other published studies in the literature. Materials and Methods: A total of 220 unrelated healthy volunteers and 151 patients with ALL of both sexes were recruited for the study. Extracted DNA was subjected to genotyping by allelic discrimination using quantitative real-time-polymerase chain reaction. Genotype details of the studied variants in other ethnicities were obtained from 1000 genomes project Phase 3 data. Haploview software was used to construct haplotypes. Results:: In our study, the frequencies of FPGS rs1006'G' and rs1544105'A' alleles were found to be 37% and 37.2%, respectively, and the frequencies of GGH rs3758149'T' and GGH rs11545078'T' alleles were found to be 29.8% and 16.7%, respectively. Among the studied variants, FPGS rs1544105'AA' genotype carriers were found to be susceptible to the risk of ALL (odds ratio: 2.16; 95% confidence interval [CI]: 1.15–4.07; P = 0.02). Haplotype structures of FPGS and GGH variants in SI population were significantly different from other ethnicities (P < 0.05), except the South Asian superpopulation. Conclusion: FPGS rs1544105'AA' genotype was found to influence the risk for ALL. Intra and interethnic differences exist in the distribution of studied variants. Therefore, the impact of each variant on the susceptibility and outcome of diseases may differ between populations.

Effect of Antioxidants and Apoptosis Inhibitors on Cryopreservation of Murine Germ Cells Enriched for Spermatogonial Stem Cells

Spermatogonial stem cells (SSCs) are germline stem cells that serve as the foundation of spermatogenesis to maintain fertility throughout a male’s lifetime. To treat male infertility using stem cell banking systems and transplantation, it is important to be able to preserve SSCs for long periods of time. Therefore, this study was conducted to develop an optimal cryopreservation protocol for SSCs using antioxidants and apoptosis inhibitors in freezing medium. No differences were observed compared to controls when SSCs were cryopreserved in the presence of apoptosis inhibitors by themselves. However, mouse germ cells cryopreserved in basal medium containing the antioxidant hypotaurine (14 mM) resulted in significantly greater proliferation potential and mitochondrial activity. Furthermore, treatment groups with combinations containing 200 mM trehalose and 14 mM hypotaurine showed higher proliferation rates compared to controls. In addition, several serum free conditions were evaluated for SSC cryopreservation. Treatment media containing 10% or 20% knockout serum replacement resulted in similar cryopreservation results compared to media containing FBS. SSC transplantation was also performed to confirm the functionality of SSCs frozen in 14 mM hypotaurine. Donor SSCs formed normal spermatogenic colonies and sperm in the recipient testis. These data indicate that inclusion of 14 mM hypotaurine in cryopreservation media is an effective way to efficiently cryopreserve germ cells enriched for SSCs and that knockout serum replacement can replace FBS in germ cell cryopreservation media.

Folylpoly-γ-glutamate synthetase: A key determinant of folate homeostasis and antifolate resistance in cancer

Mammalians are devoid of autonomous biosynthesis of folates and hence must obtain them from the diet. Reduced folate cofactors are B9-vitamins which play a key role as donors of one-carbon units in the biosynthesis of purine nucleotides, thymidylate and amino acids as well as in a multitude of methylation reactions including DNA, RNA, histone and non-histone proteins, phospholipids, as well as intermediate metabolites. The products of these S-adenosylmethionine (SAM)-dependent methylations are involved in the regulation of key biological processes including transcription, translation and intracellular signaling. Folate-dependent one-carbon metabolism occurs in several subcellular compartments including the cytoplasm, mitochondria, and nucleus. Since folates are essential for DNA replication, intracellular folate cofactors play a central role in cancer biology and inflammatory autoimmune disorders. In this respect, various folate-dependent enzymes catalyzing nucleotide biosynthesis have been targeted by specific folate antagonists known as antifolates. Currently, antifolates are used in drug treatment of multiple human cancers, non-malignant chronic inflammatory disorders as well as bacterial and parasitic infections. An obligatory key component of intracellular folate retention and intracellular homeostasis is (anti)folate polyglutamylation, mediated by the unique enzyme folylpoly-γ-glutamate synthetase (FPGS), which resides in both the cytoplasm and mitochondria. Consistently, knockout of the FPGS gene in mice results in embryonic lethality. FPGS catalyzes the addition of a long polyglutamate chain to folates and antifolates, hence rendering them polyanions which are efficiently retained in the cell and are now bound with enhanced affinity by various folate-dependent enzymes. The current review highlights the crucial role that FPGS plays in maintenance of folate homeostasis under physiological conditions and delineates the plethora of the molecular mechanisms underlying loss of FPGS function and consequent antifolate resistance in cancer.

Mutation of the nm23-H1 gene has a non-dominant role in colorectal adenocarcinoma

Nm23-H1 is a metastasis suppressor gene, which is has a reduced expression in patients with digestive system cancer. However, the mechanistic basis for the genetic instability remains unknown. To study the expression of the nm23-H1 gene in patients with colorectal cancer, polymerase chain reaction-single strand conformation polymorphism was used to analyze any point mutation, and immunohistochemistry was used to detect the expression of nm23-H1. Results revealed that all 63 specimens of Chinese human colorectal cancer tissues exhibit no point mutation. Among those 63 specimens, 19 (30%) exhibited positive immunostaining for the nm23-H1 protein and 44 (70%) exhibited negative immunostaining. These observations suggested that the protein and gene expression levels of nm23-H1 are reduced in colorectal cancer compared with the adjacent normal tissues, and the point mutation in the nm23-H1 gene is not the dominant cause of metastatic colorectal cancer.

Multiplex RT-PCR Assay for Detection of Common Fusion Transcripts in Acute Lymphoblastic Leukemia and Chronic Myeloid Leukemia Cases

BACKGROUND

Acute lymphoblastic leukemia (ALL) is a heterogeneous disease which requires a risk-stratified approach for appropriate treatment. Specific chromosomal translocations within leukemic blasts are important prognostic factors that allow identification of relevant subgroups. In this study, we developed a multiplex RT-PCR assay for detection of the 4 most frequent translocations in ALL (BCR-ABL, TEL-AML1, MLL-AF4, and E2A- PBX1).

MATERIALS AND METHODS

A total of 214 diagnosed ALL samples from both adult and pediatric ALL and 14 cases of CML patients (154 bone marrow and 74 peripheral blood samples) were assessed for specific chromosomal translocations by cytogenetic and multiplex RT-PCR assays.

RESULTS

The results showed that 46 cases of ALL and CML (20.2%) contained the fusion transcripts. Within the positive ALL patients, the most prevalent cryptic translocation observed was mBCR-ABL (p190) at 8.41%. In addition, other genetic rearrangements detected by the multiplex PCR were 4.21% TEL-AML1 and 2.34% E2A-PBX1, whereas MLL-AF4 exhibited negative results in all tested samples. Moreover, MBCR-ABL was detected in all 14 CML samples. In 16 samples of normal karyotype ALL (n=9), ALL with no cytogentic result (n=4) and CML with no Philadelphia chromosome (n=3), fusion transcripts were detected.

CONCLUSIONS

Multiplex RT-PCR provides a rapid, simple and highly sensitive method to detect fusion transcripts for prognostic and risk stratification of ALL and CML patients.