The evaluation of p21 and p27 expression in HLA-DR negative AML patients

AML is a heterogeneous type of leukemia with a high variation in the biological features of the leukemic cells and disease outcomes. The biological features of the leukemic cells have a very close correlation with the disease outcomes. In this way, leukemic cells with higher levels of proliferation and lower levels of maturation undoubtedly would lead to poorer outcomes. Based on immunophenotyping, HLA-DR negative AMLs constitute an important category in AML classification. The majority of patients with this immunophenotype belong to APL subtype with PML-RARA fusion gene and the others are non-APL subtype without PML-RARA fusion gene. As disease outcome and cell biological features have a very close correlation, it is important to evaluate essential molecules involved in the biological processes of the leukemic cells which are helpful in the determination of disease outcome. Therefore in this study we evaluated the expression of p21 and p27 as two key molecules involved in the regulation of cell cycle, proliferation, maturation and apoptosis to determine whether there is any significant difference between these two subgroups of HLA-DR negative AMLs. We studied p21 and p27 mRNA levels by real-time RT-PCR in 41 primary HLA-DR negative AML samples, compared with normal bone marrow and peripheral blood cells. p21 expression was significantly higher in APL cases than non-APLs but there was no significant difference in p27 expression between APL and non-APL patients. According to our results, it seems that p21 can be considered as a critical gene involved in the determination of the levels of cell differentiation between these two subtypes.