Rapid induction of P-glycoprotein mRNA and protein expression by cytarabine in HL-60 cells.

Abstract

BACKGROUND: Overexpression of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and glutathione-S-transferase pi (GSTpi) is associated with drug resistance in acute myeloid leukemia (AML). The short-term effects of drug exposure on their expression levels were investigated. MATERIALS AND METHODS: HL-60 cells and drug-resistant sublines were cultured with or without daunorubicin (DNR) and cytarabine (Ara-C). At several time-points the expression levels of P-gp, BCRP and GSTpi were determined. RESULTS: After exposure to Ara-C, P-gp mRNA rapidly increased in all the cell lines. P-gp protein was detected in the sensitive cells after 8 h exposure to Ara-C. GSTpi mRNA increased in the resistant cells, but no change in BCRP mRNA was observed. Exposure to DNR revealed rapidly increased P-gp and GSTpi mRNA in the resistant cells. CONCLUSION: Ara-C rapidly increases P-gp mRNA and protein expression in sensitive and resistant cells, and GSTpi mRNA in resistant cells, in vitro. This may be of clinical importance during AML induction chemotherapy.