3-3--dihexyl-2-2--oxacarbocyanine and Leukemia

The expression and activity of P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP1) were analyzed in 178 leukemia samples. Rhodamine-123 (Rho-123) and DiOC(2) were used as substrate to evaluate efflux pump activity. Chronic myeloid leukemia (CML) exhibited a higher percentage of positivity using Rho-123 than DiOC(2) (p=0.000) as compared to other types of leukemia. Moreover, Rho-123 was able to detected Pgp positive cells in a higher proportion of samples than DiOC(2) samples (p=0.004). Similarly, MRP1 positive cells were best detected by Rho-123 as opposed to DiOC(2) (p=0.003). The co-functionality of Rho-123 and DiOC(2) was observed in 26 out of 105 (24.8%) leukemic samples. Co-expression between Pgp and MRP1 was detected in 30 out of 56 (53.6%) samples. As a whole, when the same samples were analyzed, Rho-123 was able to detect Pgp positive cells in a higher proportion of samples than DiOC(2) (p=0.000). Similarly, MRP1 positive cells were best detected by Rho-123 as opposed to DiOC(2) (p=0.007). Our results support the idea that Rho-123 is the substrate of choice for leukemic cells.

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Carbocyanines; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flow Cytometry; Fluorescent Dyes; Humans; Leukemia; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Leukemia, Promyelocytic, Acute; Multidrug Resistance-Associated Proteins; Phenotype; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Rhodamine 123; Tumor Cells, Cultured

Early during apoptosis, there is a reduction in mitochondrial transmembrane potential (MTP) and externalization of phosphatidylserine (PS) in cell membrane prior to eventual cell death. Flow cytometric detection techniques targeting these changes, reduction of DiOC(6)(3) uptake upon the collapse of MTP and annexin V binding to PS have been successfully used to detect apoptotic cells. These methods have given comparable results when cell lines were used. We compared the two different techniques, DiOC(6)(3) uptake and Annexin V-propidium iodide co-labeling in the quantification of cytarabine, vincristine and daunorubicin induced apoptosis on three leukemia cell lines (HL-60, CEM, U937), and bone marrow blasts from 26 children with acute myeloid leukemia, 14 with T cell acute lymphoblastic leukemia. Anti-Fas-induced apoptosis in culture-grown peripheral blood T lymphocytes on 18 samples from 9 children with non-malignant conditions were also studied by these techniques. Our results showed that there is a correlation (P < 0. 05) between the apoptosis rates measured by these two techniques for drug-induced apoptosis in myeloid and lymphoid blasts, and for anti-Fas mAb-induced apoptosis in T lymphocytes. This data suggests that reduction of the MTP and PS externalization may be common to many apoptotic pathways and techniques targeting either of these changes may be used in quantification of apoptosis in different clinical samples.

Topics: Annexin A5; Antibiotics, Antineoplastic; Antimetabolites, Antineoplastic; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Apoptosis; Carbocyanines; Child; Cytarabine; Daunorubicin; Flow Cytometry; Fluorescent Dyes; HL-60 Cells; Humans; Indicators and Reagents; Leukemia; Propidium; T-Lymphocytes; Tumor Cells, Cultured; U937 Cells; Vincristine