Expression of the neural cell adhesion molecule CD56 is not associated with P-glycoprotein overexpression in core-binding factor acute myeloid leukemia

Acute myeloid leukemia (AML) with rearrangement of the core-binding factor (CBF) α or β subunit gene has a favorable prognosis, but CD56 expression in CBFα-AML is associated with short disease-free survival. A proposed mechanism is overexpression of the multidrug resistance (MDR) protein P-glycoprotein (Pgp). CD56 expression, Pgp expression and function, and expression of the additional MDR proteins multidrug resistance protein-1 (MRP-1), lung resistance protein (LRP) and breast cancer resistance protein (BCRP) were studied in pretreatment blasts from 25 CBF-AML patients. CD56 expression was frequent in CBFα but rare in CBFβ, and Pgp expression and function were frequent in both subtypes. CD56 expression did not correlate with Pgp expression or function, nor with expression of the other MDR proteins. Treatment failure associated with CD56 expression in CBFα-AML is not likely attributable to Pgp.