OBJECTIVETo investigate the effect of all transretinoicacid(ATRA) combined with decitabine (5-Aza-2'-deoxycytidine;DAC) on DNA methylation and gene expression of p16INK4a (p16) and retinoic acid receptor β (RARβ), and to explore their combined anti neoplastic effect on U937 cells and newly diagnose delder acute myeloid leukemia(AML) patients.

METHODSThe expression levels of p16 and RARβ were determined by qRT-PCR and Western blot. Methylation-specific PCR was used to analyze their methylation status. WST-1 and flow cytometry were performed to detect growth inhibition, differentiation, apoptosis and cell cycle of U937 cells respectively.

RESULTSThe expression p16 and RARβ was down-regulated by promoter hypermethylation in newly diagnose delder AML patients and U937 cells. Combination treatment of ATRA and DAC induced DNA hypomethylation as well as gene expression of p16 and RARβ, which contributed to the growth inhibition, differentiation, apoptosis and cell cycle arrest of U937 cells. In addition for elder AML patients intolerable to standard chemotherapy, the combination regimen of ATRA and DAC showed antineoplastic activity accompamied by up-regulation of p16 and RARβ expression and decrease of bone marrow blast, moreover the parients showed good tolerence to the reginen.

CONCLUSIONThe regimen of ATRA combined with DAC as the combination therapeutic strategy for inducing differentiation and demethylation possesses the anti-AML potency, and contributes to optimizing the therapeutic strategy for elder AML patients and promoting the clinical prognosis.