Comparison of two functional flow cytometric assays to assess P-gp activity in acute leukemia.

Abstract

One of the possible causes of treatment failure in acute leukemia is the emergence of multidrug resistance caused by P-glycoprotein (P-gp) overexpression. We compared a flow cytometric assay using JC-1 with a technique using rhodamine 123 (rho123) to evaluate the P-gp function in acute leukemia. Samples from 50 acute leukemia patients were analyzed by both functional assays. The P-gp expression was assessed by an immunological flow cytometric test and the association between the P-gp status and the clinical outcome was evaluated. Of all samples, 28% showed a reversible JC-1 efflux and 36% scored positive for the rho123 assay. In two cases, the leukemic blasts showed a reversible JC-1 efflux whereas they were negative for rho123. These patients had blast cells with a very low P-gp activity. Six samples scored positive for the rho123 assay but were negative for the JC-1 test. Five of these samples did not express P-glycoprotein and were considered false positive. We found a strong correlation between the JC-1 and the rho123 test (R(s)=0.59, p<0.0001) and the JC-1 and the immunological assay (R(s)=0.29, P=0.05). There was also an association between the JC-1 status and the clinical outcome of adult patients (chi2=6.30, P=0.04). In conclusion, we recommend the JC-1 assay to study the P-gp activity in acute leukemia because it is more specific and less labor intensive than conventional functional flow cytometric tests using rhodamine 123. In addition, the JC-1 assay can be used to identify adult patients with an increased risk for adverse clinical outcome.

• Authors: Katrien Swerts, Barbara de Moerloose, Catharina Dhooge, Lucien Noens, Geneviève Laureys, Yves Benoit, Jan Philippé
• Journal: Leukemia & lymphoma (Leuk Lymphoma) Vol. 45 Issue 11 Pg. 2221-8 (Nov 2004) ISSN: 1042-8194 [Print] United States
• PMID: 15512810 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 1
• Benzimidazoles
• Carbocyanines
• Fluorescent Dyes
• Rhodamine 123
• 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 1 (metabolism)
• Adult
• Benzimidazoles (pharmacology)
• Carbocyanines (pharmacology)
• Child
• Drug Resistance, Neoplasm
• Female
• Flow Cytometry (methods)
• Fluorescent Dyes (pharmacology)
• Humans
• K562 Cells
• Leukemia (metabolism)
• Leukemia, Myeloid, Acute (drug therapy, metabolism)
• Male
• Precursor Cell Lymphoblastic Leukemia-Lymphoma (drug therapy, metabolism)
• Rhodamine 123 (pharmacology)
• Risk
• Treatment Outcome