Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia

Abstract

Backgroundγ-Glutamyl hydrolase (GGH) regulates intracellular folates and antifolates such as methotrexate (MTX) for proper nucleotide biosynthesis and antifolate-induced cytotoxicity, respectively. In addition to genetic polymorphism and karyotypic abnormalities, methylation of CpG island 1 (CpG1) in the promoter region is found to modulate GGH activity by reducing GGH mRNA expression in acute lymphoblastic leukemia (ALL) cells. We aim to investigate methylation status of two CpG islands (CpG1 and CpG2) in the GGH promoter region in pediatric patients with ALL and acute myelogenous leukemia (AML).Methods70B-ALL, 29 AML, 10 ITP (idiopathic thrombocytopenic purpura) and 40 healthy children are recruited in the present study. MS-HRM (methylation-sensitive high-resolution melting) and bisulfite sequencing PCR (BSP) are used to detect methylation change and its level in CpG1 and CpG2 in the GGH promoter region. GGH mRNA expression is quantified by real-time PCR. Correlation between CpG island methylation and GGH mRNA expression is assessed by statistical software.ResultsMethylations of CpG1 are detected in leukemia cells samples obtained from 30.9% (21/68) of patients with ALL and 20.7% (6/29) of patients with AML. These methylations are not detected in the controls. Methylations of CpG2 are detected in leukemia cell samples obtained from 44.1% (30/68) of the ALL patients and 37.9% (11/29) of the AML patients. These percentages are significantly higher than that observed in the control cell samples: 6.0% (3/50) (Fisher's exact test, P = 0.000). The abundance of CpG1 methylation in all leukemia cell samples is classified as Grade I (methylation level is less than 10%) and the abundance of CpG2 methylation in leukemia cell samples is classified in separate grades. Our results indicate that methylation of CpG1 or hypermethylation (the methylation level is greater than 10%) of CpG2 could significantly reduce GGH mRNA expression in leukemia cells from the ALL and AML patients (ALL-CpG1: t = 4.632, P = 0.000; ALL-CpG2: t = 3.250, P = 0.006; AML-CpG1: t = -2.254, P = 0.037; AML-CpG2: t = 1.328, P = 0.202).ConclusionEither methylation of CpG1 or hypermethylation of CpG2 in GGH promoter region can significantly reduce GGH mRNA expression in pediatric patients with acute leukemia, which can improve the response to treatment.

Global methylation in relation to methotrexate-induced oral mucositis in children with acute lymphoblastic leukemia

“…These results do not confirm the hypothesis that global methylation is associated with MTX-induced mucositis. However, a recent study showed that the hypermethylation in CpG1 and CpG2 of the promotor of the ɣ-Glutamyl Hydrolase (GGH) gene, which is involved in polyglutamating MTX, can significantly reduce GGH mRNA expression in pediatric ALL [ 27 ]. Therefore, performing genome-wide DNA methylation analyses using an Illumina methylation EPIC array could be relevant in future studies to assess whether gene-specific DNA methylation status could be used as a possible biomarker in predicting MTX-induced toxicity, such as oral mucositis.…”

Differential expression profiles of long noncoding RNAs in synchronous multiple and solitary primary esophageal squamous cell carcinomas: A microarray analysis

“…Thus, it consequently had an impact on the regulation of cell cycle, cellular growth, and proliferation . Methylation of CpG1 islands in the GGH promoter region could remarkably reduce the GGH mRNA expression and improve treatment outcomes in pediatric patients with acute leukemia . Because of the previous observation of global hypomethylation in multiple ESCCs, we suggested a possible role of GGH in field carcinogenesis, which should be validated in future study.…”

Integrative Analysis of Multi-Omics Identified the Prognostic Biomarkers in Acute Myelogenous Leukemia

“…Methotrexate as a first-line chemotherapy drug for clinical treatment of AML; DNA methylation can reduce the response of the human body to methotrexate and then directly affect the therapeutic effect. Inhibition of DNA methylation can increase the sensitivity of the human body to methotrexate ( 28 ). Clinical studies have found that the combined use of anti-DNA methylation drugs can significantly improve the effect of chemotherapy and prolong survival time ( 22 ).…”