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Multidrug resistance in acute leukemia: a conserved physiologic function
Abstract:
Native resistance to conventional chemotherapy remains an important cause of treatment failure in the adult acute leukemias. Delineation of cellular mechanisms of drug resistance therefore represents a prerequisite to the development of more effective treatment strategies. The multidrug resistance (MDR) phenotype represents one such mechanism of resistance with direct clinical relevance. This phenotype occurs normally in certain mammalian tissues, and is detectable in tumor cell lines selected for resistance to naturally occurring antineoplastics. The mdr1 gene or its glycoprotein product, P-glycoprotein, is detected with high frequency in secondary acute myeloid leukemia (AML) and poor-risk subsets of acute lymphoblastic leukemia. In prospective studies in AML, MDR overexpression is an independent determinant of response to treatment and overall survival with conventional-dose induction regimens. Investigations of mdr1 regulation in normal hematopoietic elements has shown a pattern which corresponds to its regulation in acute leukemia, explaining the linkage of mdr1 to specific cellular phenotypes. Therapeutic trials are now in progress to test the ability of various MDR-reversal agents to restore chemotherapy sensitivity in high-risk acute leukemias.
Insights
Multidrug resistance (MDR) is a key factor in acute leukemia treatment failure. Overexpression of the mdr1 gene and P-glycoprotein in leukemia cells predicts poor response to chemotherapy.
Area of Science:
- Hematology
- Molecular Biology
- Oncology
Background:
- Chemotherapy resistance is a major challenge in treating adult acute leukemias.
- Understanding drug resistance mechanisms is crucial for developing better therapies.
- The multidrug resistance (MDR) phenotype is a clinically relevant mechanism of resistance.
Purpose of the Study:
- To investigate the role of multidrug resistance (MDR) in acute leukemias.
- To explore the expression of the mdr1 gene and P-glycoprotein in different acute leukemia subtypes.
- To determine the prognostic significance of MDR in acute myeloid leukemia (AML).
Main Methods:
- Analysis of mdr1 gene and P-glycoprotein expression in leukemia cells.
- Prospective studies in AML patients treated with conventional chemotherapy.
- Investigation of mdr1 regulation in normal hematopoietic cells.
Main Results:
- MDR phenotype is frequently detected in secondary AML and poor-risk acute lymphoblastic leukemia.
- MDR overexpression is an independent predictor of treatment response and survival in AML.
- mdr1 gene regulation in leukemia mirrors its regulation in normal hematopoietic cells.
Conclusions:
- MDR is a significant factor contributing to treatment failure in acute leukemias.
- The mdr1 gene and P-glycoprotein are important biomarkers for predicting outcomes in AML.
- Therapeutic strategies targeting MDR reversal are under investigation for high-risk leukemias.