Oxidative stress levels are correlated with P15 and P16 gene promoter methylation in myelodysplastic syndrome patients.

Oxidative stress and abnormal DNA methylation have been implicated in some types of cancer, namely in myelodysplastic syndromes (MDS). Since both mechanisms are observed in MDS patients, we analyzed the correlation of intracellular levels of peroxides, superoxide anion, and glutathione (GSH), as well as ratios of peroxides/GSH and superoxide/GSH, with the methylation status of P15 and P16 gene promoters in bone marrow leukocytes from MDS patients. Compared to controls, these patients had lower GSH content, higher peroxide levels, peroxides/GSH and superoxide/GSH ratios, as well as higher methylation frequency of P15 and P16 gene promoters. Moreover, patients with methylated P15 gene had higher oxidative stress levels than patients without methylation (peroxides: 460 ± 42 MIF vs 229 ± 25 MIF, p = 0.001; superoxide: 383 ± 48 MIF vs 243 ± 17 MIF, p = 0.022; peroxides/GSH: 2.50 ± 0.08 vs 1.04 ± 0.34, p < 0.001; superoxide/GSH: 1.76 ± 0.21 vs 1.31 ± 0.10, p = 0.007). Patients with methylated P16 and at least one methylated gene had higher peroxide levels as well as peroxides/GSH ratio than patients without methylation. Interestingly, oxidative stress levels allow the discrimination of patients without methylation from ones with methylated P15, methylated P16, or at least one methylated (P15 or P16) promoter. Taken together, these findings support the hypothesis that oxidative stress is correlated with P15 and P16 hypermethylation.

[Acute myelogenous leukemia presenting as diabetes insipidus]. / Diabetes insípida como forma de apresentação de leucemia mielóide aguda.

Central diabetes insipidus, is a syndrome characterized by the excretion of abnormally elevated volumes of diluted urine, due to the diminution of reabsorption of water in the collecting ducts, induced by the diminution of production of antidiuretic hormone. The involvement of the central nervous system in the leukaemia is frequent, but the association leukaemia/diabetes insipidus is rare. We describe a clinical case of a 40 years old female, whose first manifestation of leukaemia was diabetes insipidus; we discuss the difficulties of diagnosis, the particularities of the case and its evolution.