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

BACKGROUND Children with acute lymphoblastic leukemia (ALL) often suffer from toxicity of chemotherapeutic drugs such as Methotrexate (MTX). Previously, we reported that 20% of patients receiving high-dose MTX developed oral mucositis. MTX inhibits folate metabolism, which is essential for DNA methylation. We hypothesize that MTX inhibits DNA methylation, which results into adverse effects. We studied DNA methylation markers during high-dose methotrexate treatment in pediatric acute lymphoblastic leukemia (ALL) in relation to developing oral mucositis. MATERIALS & METHODS S-Adenosyl-Methionine (SAM) and S-Adenosyl-Homocysteine (SAH) levels and LINE1 DNA methylation were measured prospectively before and after high-dose methotrexate (HD-MTX 4 x 5g/m2) therapy in 82 children with ALL. Methotrexate-induced oral mucositis was registered prospectively. Oral mucositis (grade ≥ 3 National Cancer Institute Criteria) was used as clinical endpoint. RESULTS SAM levels decreased significantly during methotrexate therapy (-16.1 nmol/L (-144.0 - +46.0), p<0.001), while SAH levels and the SAM:SAH ratio did not change significantly. LINE1 DNA methylation (+1.4% (-1.1 - +6.5), p