The ABCG2 transporter is an efficient Hoechst 33342 efflux pump and is preferentially expressed by immature human hematopoietic progenitors

• Published in: Blood Vol. 99; no. 2; pp. 507 - 512
• Main Authors: Scharenberg, Christian W., Harkey, Michael A., Torok-Storb, Beverly
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 15.01.2002; The Americain Society of Hematology
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; ATP Binding Cassette Transporter, Subfamily B, Member 1 - genetics; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters - metabolism; Benzimidazoles - metabolism; Biological and medical sciences; Biological Transport - drug effects; Bone Marrow Cells - classification; Bone Marrow Cells - metabolism; Bone marrow, stem cells transplantation. Graft versus host reaction; Cell differentiation, maturation, development, hematopoiesis; Cell Line - drug effects; Cell Line - metabolism; Cell physiology; Coloring Agents - metabolism; DNA, Complementary - genetics; DNA-Binding Proteins - metabolism; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Hematopoiesis - genetics; Hematopoietic Stem Cells - metabolism; Kidney - cytology; Lung Neoplasms - pathology; Medical sciences; Microscopy, Fluorescence; Molecular and cellular biology; Multidrug Resistance-Associated Proteins; MutS Homolog 3 Protein; Neoplasm Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Tumor Cells, Cultured - metabolism; Human; Cell culture; Dyes; Cell function; Stem cell; Hematopoietic cell; Cell differentiation; Pump; Ripening; Hematopoiesis; Established cell line; Fluorescent compound; Immaturity; Progenitor cell
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V99.2.507

A promising and increasingly exploited property of hematopoietic stem cells is their ability to efflux the fluorescent dye Hoechst 33342. The Hoechst-negative cells are isolated by fluorescence-activated cell sorting as a so-called side “population” (SP) of bone marrow. This SP from bone marrow, as well as other tissues, is reported to contain immature stem cells with considerable plasticity. Some cell lines also efflux Hoechst and generate SP profiles. Reverse transcription–polymerase chain reaction (RT-PCR) and efflux inhibition studies with the lung carcinoma cell line, A549, implicated the ABCG2 transporter as a Hoechst efflux pump. Furthermore, it is shown that transient expression of ABCG2 generates a robust SP phenotype in human embryonic kidney (HEK293) cells. The results allow the conclusion thatABCG2 is a potent Hoechst efflux pump. Semiquantitative RT-PCR was used to characterize the developmental pattern of expression of ABCG2 in hematopoiesis. It is expressed at relatively high levels in putative hematopoietic stem cells (isolated as SP, 34+/38− or 34+/KDR+populations) and drops sharply in committed progenitors (34+/38+, 34+/33+, or 34+/10+). Expression remains low in most maturing populations, but rises again in natural killer cells and erythroblasts. Comparison of messenger RNA (mRNA) levels for the 3 major multidrug-resistant efflux pumps, MDR1,MRP1, and ABCG2, in bone marrow SP cells reveals that ABCG2 is the predominant form in these cells. These data suggest that ABCG2 contributes significantly to the generation of the SP phenotype in hematopoietic stem cells. Furthermore, the sharp down-regulation of ABCG2 at the stage of lineage commitment suggests that this gene may play an important role in the unique physiology of the pluripotent stem cell.