RESUMEN
AIM: Protein tyrosine phosphatases receptor type D (PTPRD) is a tumour suppressor gene, and its epigenetic silencing is frequently found in glioblastoma. As aberrant deoxyribonucleic acid (DNA) methylation patterning has been shown to play a role in leukaemogenesis, we studied the promoter methylation, expression profiles and molecular functions of PTPRD in paediatric patients with acute myeloid leukaemia (AML). METHODS: Bone marrow specimens were obtained from 32 Chinese patients with a mean age of 7.2 years (range 1.1-16.5). PTPRD and methylation status were evaluated by real-time polymerase chain reaction (PCR) and methylation-specific PCR. Western blot and flow cytometry techniques were also used. RESULTS: PTPRD expression was decreased by promoter region methylation in six AML cells and methylated in 21 (65.6%) of the 32 samples. In addition, PTPRD expression could be induced by the DNA demethylating agent 5-aza-2'-deoxycytidine. Furthermore, functional studies showed that overexpression of PTPRD in AML cells inhibited cell proliferation and clonogenicity as well as inducing apoptosis. However, PTPRD knockdown increased cell proliferation. These effects were associated with downregulation of cyclin D1, c-myc and upregulation of Bax. CONCLUSION: The results of this study demonstrated that PTPRD was a potential tumour suppressor gene inactivated by DNA methylation in paediatric AML.