Clinical Response to Traditional Chinese Herbs Containing Realgar (As(2)S(2)) is Related to DNA Methylation Patterns in Bone Marrow DNA from Patients with Myelodysplastic Syndrome with Multilineage Dysplasia

PURPOSE: DNA methylation is known to play an important role in myelodysplastic syndrome (MDS). We previously showed that Chinese herbs (CHs) containing realgar (As(2)S(2)) were effective at treating MDS with multilineage dysplasia (MDS–MLD). We tested whether the response to CH treatment was related to changes in DNA methylation in MDS–MLD. PATIENTS AND METHODS: First, the Illumina methylation 850K array BeadChip assay was used to assess the pretreatment methylation status in bone marrow cells from eight MDS–MLD patients and 3 healthy donors. The eight MDS–MLD patients were then treated with CHs for six months, the arsenic concentration was measured following treatment. The patients were subsequently divided into “effective” and “ineffective” treatment response groups and the DNA methylation patterns of the two groups were compared. Finally, the BeadChip data were validated by pyrosequencing. RESULTS: Five of the eight MDS–MLD patients showed hematological improvement (effective-treatment group), while three showed disease progression (ineffective-treatment group) (positive response rate: 62.5%). The arsenic concentrations in the patients ranged from 26.60 to 64.16 μg/L (median 48.4 μg/L) and were not significantly different between the two groups (p = 0.27). Compared with the healthy controls, three genes were hypomethylated and 110 were hypermethylated in the ineffective-treatment group. However, in the group showing hematological improvement, 102 genes were markedly hypomethylated and 87 hypermethylated. The effective-treatment group had a higher proportion of hypomethylated sites than the ineffective-treatment group (53.9% vs 2.6%, respectively; chi-square test) (p < 0.0001). Two hypermethylated and two hypomethylated genes were selected for validation by pyrosequencing (all p < 0.05). CONCLUSION: MDS–MLD patients may present different DNA methylation subtypes. CHs containing realgar may be effective for treating MDS–MLD patients with the hypomethylation subtype.