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

BACKGROUND: γ-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)...

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Autores principales: Li, Yue, Liu, Sixi, Wang, Huihui, Mai, Huirong, Yuan, Xiuli, Li, Changgang, Chen, Xiaowen, Wen, Feiqiu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344458/
https://www.ncbi.nlm.nih.gov/pubmed/28278270
http://dx.doi.org/10.1371/journal.pone.0173472
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author Li, Yue
Liu, Sixi
Wang, Huihui
Mai, Huirong
Yuan, Xiuli
Li, Changgang
Chen, Xiaowen
Wen, Feiqiu
author_facet Li, Yue
Liu, Sixi
Wang, Huihui
Mai, Huirong
Yuan, Xiuli
Li, Changgang
Chen, Xiaowen
Wen, Feiqiu
author_sort Li, Yue
collection PubMed
description BACKGROUND: γ-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). METHODS: 70B-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. RESULTS: Methylations 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). CONCLUSION: Either 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.
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spelling pubmed-53444582017-03-29 Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia Li, Yue Liu, Sixi Wang, Huihui Mai, Huirong Yuan, Xiuli Li, Changgang Chen, Xiaowen Wen, Feiqiu PLoS One Research Article BACKGROUND: γ-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). METHODS: 70B-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. RESULTS: Methylations 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). CONCLUSION: Either 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. Public Library of Science 2017-03-09 /pmc/articles/PMC5344458/ /pubmed/28278270 http://dx.doi.org/10.1371/journal.pone.0173472 Text en © 2017 Li et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Li, Yue
Liu, Sixi
Wang, Huihui
Mai, Huirong
Yuan, Xiuli
Li, Changgang
Chen, Xiaowen
Wen, Feiqiu
Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title_full Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title_fullStr Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title_full_unstemmed Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title_short Methylation level of CpG islands in GGH gene promoter in pediatric acute leukemia
title_sort methylation level of cpg islands in ggh gene promoter in pediatric acute leukemia
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344458/
https://www.ncbi.nlm.nih.gov/pubmed/28278270
http://dx.doi.org/10.1371/journal.pone.0173472
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