Shu-Mei Wang1,2,3, Xiao-Yan Kong4, Miao Li5, Lu-Lu Sun1, Dan Yan1,2,3. 1. Department of Pharmacy, Beijing Shijitan Hospital, Capital Medical University, Beijing, China. 2. Beijing Key Laboratory of Bio-characteristic Profiling for Evaluation of Rational Drug Use, Beijing, China. 3. International Cooperation & Joint Laboratory of Bio-characteristic Profiling for Evaluation of Rational Drug Use, Beijing, China. 4. Department of Pharmacy, Armed Police Beijing Corps Hospital, Beijing, China. 5. Department of Pediatrics, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
Abstract
BACKGROUND: It is known that γ-glutamyl hydrolase (GGH) is involved in the disposition of methotrexate (MTX), and GGH activity is regulated by DNA methylation in acute lymphoblastic leukemia (ALL) cells. The present study explores the methylation status of the GGH promoter in peripheral blood and its association with MTX levels and toxicities in Chinese children with ALL. METHODS: Serum MTX concentrations were determined by fluorescence polarization immunoassay. Methylation quantification and genotyping for GGH rs3758149 and rs11545078 was performed by Sequenom MassARRAY in 50 pediatric patients with ALL. RESULTS: Overall, the investigated region of the GGH promoter was in hypomethylated status. The methylation levels of cytosine phosphate guanine (CpG)_7, CpG_12, CpG_17, and CpG_20 were significantly higher in patients with B-cell ALL than other immunotypes (p<0.05). The methylation levels of CpG_13.14, CpG_17, and CpG_19 showed a significant negative correlation with MTX C24 hr (p<0.05). The methylation level of CpG_8.9 correlated significantly with MTX C42 hrs (p<0.05). The methylation level of CpG_19 was significantly lower in patients with MTX toxicities (p<0.05). CONCLUSIONS: The methylation levels of the GGH promoter might affect MTX exposure and toxicities. These findings provided reasonable explanations for the variability of MTX responses in patients with childhood ALL.
BACKGROUND: It is known that γ-glutamyl hydrolase (GGH) is involved in the disposition of methotrexate (MTX), and GGH activity is regulated by DNA methylation in acute lymphoblastic leukemia (ALL) cells. The present study explores the methylation status of the GGH promoter in peripheral blood and its association with MTX levels and toxicities in Chinese children with ALL. METHODS: Serum MTX concentrations were determined by fluorescence polarization immunoassay. Methylation quantification and genotyping for GGHrs3758149 and rs11545078 was performed by Sequenom MassARRAY in 50 pediatric patients with ALL. RESULTS: Overall, the investigated region of the GGH promoter was in hypomethylated status. The methylation levels of cytosine phosphate guanine (CpG)_7, CpG_12, CpG_17, and CpG_20 were significantly higher in patients with B-cell ALL than other immunotypes (p<0.05). The methylation levels of CpG_13.14, CpG_17, and CpG_19 showed a significant negative correlation with MTX C24 hr (p<0.05). The methylation level of CpG_8.9 correlated significantly with MTX C42 hrs (p<0.05). The methylation level of CpG_19 was significantly lower in patients with MTXtoxicities (p<0.05). CONCLUSIONS: The methylation levels of the GGH promoter might affect MTX exposure and toxicities. These findings provided reasonable explanations for the variability of MTX responses in patients with childhood ALL.