Relationship Between CD56 Antigen Expression and Quantification of MDR1 Gene Expression in Patients with De Novo Acute Myeloid Leukemia(AML).

The expression of CD56 antigen and over-expression of the multidrug resistance gene 1 (MDR1) seems to confer the poor therapeutic outcome to AML. The aim of this study is to investigate the relationship between CD56 antigen expression and MDR1 gene expression in patients with de novo AML and explore the indicating effect of these two factors on clinical drug resistance.

A real-time quantitative reverse transcriptase polymerase chain reaction method was established for detecting MDR1 expression levels and a three-color flow cytometry analysis with CD45/SSC gating was used to examine CD56 antigen expression in 79 patients with de novo AML.

CD56 antigen was recorded in 19 out of 79 cases (24.1%) and particularly in those with M5 subtype and t(8;21) AML. Moreover, CD56 expression was significantly associated with unfavorable cytogenetic abnormalities (P< 0.05). Significantly higher percentage (57.1%, 4/7) of patients with t(8;21) demonstrated CD56 expression than those with favorable cytogenetic abnormalities (P< 0.05). CD56⁺ AML patients had higher incidence of splenohepatomegalia and level of lactate dehydrogenase than CD56^- patients (P< 0.05). The median expression level of MDR1 was statistically higher in CD56⁺ AML patients than that in CD56^- cases (P< 0.001) and 89.5% (17/19) CD56⁺ AML patients were found with high MDR1 expression. The CR rate in high MDR1 / CD56+ AML patients was significantly lower than that in low MDR1/ CD56^- cases. (58.8% vs 89.2%, P< 0.01).

There is a linear correlation between MDR1 and CD56 expression in AML. This relationship may explain why CD56 expression is related to a poor prognosis in AML. Therefore both with high MDR1 expression level and CD56 antigen expression can identify AML patients with unfavorable outcome.

No relevant conflicts of interest to declare.