s-adenosylhomocysteine and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

This study aimed to investigate: (i) changes of plasma homocysteine, methionine and S-adenosylhomocysteine levels following high-dose methotrexate (HD-MTX) treatment and (ii) the correlation of these sulfur-containing amino acids with MTX-induced hepatotoxicity. Fifteen pediatric patients with acute lymphoblastic leukemia and one patient with Burkitt lymphoma, with a total of 26 treatment courses of HD-MTX, were enrolled. Homocysteine levels increased at 24 h after HD-MTX treatment, and showed marginal decreases at 48 and 72 h. Methionine levels showed a biphasic pattern, i.e. an initial decrease at 24 h followed by increases at 48 and 72 h. S-adenosylhomocysteine exhibited a marginal decrease at 24 h. Changes of homocysteine exhibited significant correlation only with a maximum increase of alanine aminotransferase or total bilirubin from baseline. This study has demonstrated, for the first time, simultaneous changes of plasma homocysteine, methionine and S-adenosylhomocysteine following HD-MTX. The potential of homocysteine as a marker of hepatotoxicity is also presented.

Topics: Antimetabolites, Antineoplastic; Burkitt Lymphoma; Chemical and Drug Induced Liver Injury; Child; Child, Preschool; Female; Homocysteine; Humans; Liver Function Tests; Male; Methionine; Methotrexate; Precursor Cell Lymphoblastic Leukemia-Lymphoma; S-Adenosylhomocysteine

The prognosis of patients with acute lymphoblastic leukemia (ALL) in childhood has improved with intensive chemotherapy. In particular, central nervous system (CNS) leukemia has been well controlled by the presymptomatic administration of intrathecal methotrexate (MTX), high dose systemic MTX, and irradiation. However, the prolonged intrathecal administration and/or the administration of high doses of systemic MTX, especially when combined with irradiation, can lead to leukoencephalopathy (LE), a serious CNS complication of such prophylaxis. Because the mechanisms by which MTX causes this complication have not been elucidated, the authors investigated the transmethylation status of the cerebrospinal fluid (CSF) in two children with ALL and LE to investigate the pathophysiology of that disorder.. The levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) were measured in the CSF of 2 children with ALL and LE, 7 children with ALL only who were undergoing presymptomatic administration of MTX, and 18 reference children in whom diagnostic lumbar puncture was indicated for other reasons. A sensitive, high performance liquid chromatography (HPLC) method was used with fluorescence detection.. The concentrations of SAM in the CSF were lower in the patients with ALL during treatment with MTX compared with the reference children. The SAM levels in the 2 patients with both ALL and LE were slightly lower than the levels in the 7 patients with ALL only. The SAH concentrations in the CSF were higher in the patients with ALL and LE compared with the patients with ALL only and the reference children. The mean concentration of SAH in the CSF was similar in the reference children to that found in the 7 patients with ALL only. The SAM-to-SAH ratios were lower in the 2 patients with ALL and LE and in the 7 patients with ALL only compared with the reference children. The ratios in the patients with ALL and LE were still lower than in those with ALL only, thus providing supporting evidence of hypomethylation in the 2 patients with ALL and LE.. The data suggest that the treatment of children with ALL using MTX causes subclinical hypomethylation and that progressive hypomethylation in the CNS, as evidenced in the 2 patients with ALL and LE, may be responsible for the demyelination in the LE induced by MTX.

Topics: Child; Chromatography, High Pressure Liquid; Dementia, Vascular; DNA Methylation; Female; Humans; Male; Precursor Cell Lymphoblastic Leukemia-Lymphoma; S-Adenosylhomocysteine; S-Adenosylmethionine

6-mercaptopurine (6MP) cytotoxicity is caused by thioguanine and methylthioinosine nucleotides. Thiopurine methylation occurs to a large extent in vivo and in vitro. In this reaction, S-adenosyl-L-methionine (AdoMet), produced from methionine and ATP, is converted into S-adenosyl-L-homocysteine (AdoHcy) which, in turn, is hydrolyzed into homocysteine. Remethylation of homocysteine into methionine is inhibited by methotrexate (MTX). In cultured lymphoblasts, AdoMet: AdoHcy ratio and DNA methylation decrease after incubation with 6MP. The aim of the present study was to investigate the influence of high-dose 6MP on the methylation capacity in children with acute lymphoblastic leukemia. Five patients received 4 courses with high-dose intravenous MTX (5' g.m-2 in 24 hr) immediately followed by high-dose 6MP (1300 mg.m-2 in 24 hr). Five control patients received high-dose MTX and oral 6MP (25 mg.m -2 daily for 8 weeks). Leucovorin rescue was started at 36 hr in both groups. In the intravenous 6MP group, 6-methylmercaptopurine, its riboside, and 6-methylmercapto-8-hydroxypurine were detectable in plasma in concentrations of 0.3-2.6 muM (6MP steady state levels: 11.6 muM). In red blood cells, mean methylthioinosine nucleotide levels were one third of those of ATP (13.1 nmol/10(8)). AdoHcy levels (10 pmol/10(8)) remained constant in both groups and AdoMet was not detectable ( < 20 pmol/10(8)). In both groups, plasma homocysteine increased and methionine decreased following administration of MTX. The delay in the recovery of methionine in the intravenous 6MP group after MTX infusion is probably the result of an increased demand on methyl groups during 6MP infusion.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Child; Erythrocytes; Homocysteine; Humans; Mercaptopurine; Methionine; Methotrexate; Methylation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Purine Nucleotides; S-Adenosylhomocysteine; S-Adenosylmethionine