Expression of P-gp in acute myeloid leukemia and the reversal function of As(2)O(3) on drug resistance

To study the expression of P-glycoprotein (P-gp) and the reversal function of As(2)O(3), the active ingredient of arsenic, on drug resistance in acute myeloid leukemia (AML) patients, P-gp and cluster of differentiation 34 (CD34) were examined in primary mononuclear and resistant cells, with or without As(2)O(3). In addition, multidrug resistance gene 1 (MDR1) mRNA expression was investigated in K562/D cells and AML patients. In total, 28.6% of newly-treated (NT) patients and 59.1% of relapsed/refractory (RR) patients were P-gp(function)(+), and 31.7% of NT patients and 59.1% of RR patients were CD34(+). The positivity rate of P-gp(function) and CD34(+) expression in the RR group were significantly higher compared with that in the NT group (P<0.05). In addition, higher CD34(+), P-gp(expression)(+) and P-gp(function)(+) values were observed in older patients compared with younger patients. MDR1 expression was downregulated in certain patients following treatment with AS(2)O(3). In the present study, the overexpression of P-gp was the primary cause of drug resistance in the AML patients, and MDR1 expression was downregulated by As(2)O(3) in primary leukemia and drug-resistant cells.