Chemotherapeutic drug efflux via the P-glycoprotein (P-gp) transporter encoded by the MDR1/ABCB1 gene is a significant cause of drug resistance in numerous malignancies, including acute leukemias, especially in older patients with acute myeloid leukemia (AML).
MDR1/P-gp overexpression is frequently observed in hematological malignancies, especially in acute leukemia, and has been reported to correlate with poor prognosis in acute myeloid leukemia (AML).
Clinical resistance to chemotherapy in acute myeloid leukemia (AML) is associated with the expression of the multidrug resistance (MDR) proteins P-glycoprotein, encoded by the MDR1/ABCB1 gene, multidrug resistant-related protein (MRP/ABCC1), the lung resistance-related protein (LRP), or major vault protein (MVP), and the breast cancer resistance protein (BCRP/ABCG2).
The authors conclude that isolated 3435C>T ABCB1 SNP is not a major factor of the genetic susceptibility to adult AML, and that genotyping of this polymorphism does not allow predicting P-gp expression or activity in AML cells.
Delineation of the adverse prognostic power of MDR1 in adult acute myeloid leukemia (AML) raised hopes that pharmacologic blockade of P-gp would improve the outcome of conventional cytotoxic therapy, perhaps more so than in any other human malignancy.
Expression of the multidrug resistance proteins P-glycoprotein, encoded by the MDR1 gene, multidrug resistance-associated protein (MRP1) and the lung resistance-related protein or major vault protein (LRP/MVP) is associated with clinical resistance to chemotherapy in acute myeloid leukemia (AML).
The best characterized resistance mechanism in adult acute myeloid leukemia (AML) is the one mediated by the MDR1 gene which has been shown to be associated with poor outcome.
In two multidrug resistant (MDR) sublines of the HL-60 human acute myeloid leukemia (AML) cell line which overexpress MRP but not P-glycoprotein, the assay detects elevated levels of MRP mRNA (4- to 8-fold) relative to the drug-sensitive parental cells (designated HL-60/W).