title: Retrovirus-mediated gene expression in hematopoietic cells correlates inversely with growth factor stimulation.
abstract: Cells of the hematopoetic system, especially hematopoietic progenitor and stem cells, are perceived as ideal targets for human gene therapy. In this report, the stability of retrovirus-mediated gene expression driven by three different potent promoters has been examined in purified human CD34+ cells. The promoters, murine stem cell virus (MSCV) long terminal repeat (LTR) and pgk, show gene expression in 10 times more hematopoietic colonies derived from CD34+ cells than the commonly used Moloney murine leukemia virus (Mo-MLV) LTR. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis, however, demonstrates that the levels of gene expression in retrovirus-transduced cells decrease with time in long-term bone marrow cultures and in suspension cultures containing hematopoietic growth factors. Removal of hematopoietic growth factors from the suspension culture medium was associated with a decrease in cell proliferation and differentiation, but with stable gene expression. Retrovirus-mediated gene expression is, therefore, inversely related to proliferation and differentiation of the transduced CD34+ cells. These observations may have implications in future design and implementation of human gene therapy protocols.
authors.affiliation: Cancer Center, University of California-San Diego, La Jolla 92093-0671, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lu
authors.forename: N
authors.initials: N
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Maruyama
authors.forename: R G
authors.initials: RG
authors.lastname: Hawley
authors.forename: A D
authors.initials: AD
authors.lastname: Ho
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001853:Bone Marrow; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000235:genetics; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000166:cytology; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D051379:Mice; D008979:Moloney murine leukemia virus / Q000235:genetics; D015513:Oncogene Proteins / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011518:Proto-Oncogene Proteins; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012190:Retroviridae / Q000235:genetics*
chemical_list: D018952:Antigens, CD34; D016298:Hematopoietic Cell Growth Factors; D018398:Homeodomain Proteins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; C487378:Tlx1 protein, mouse; C071250:TLX1 protein, human; D017853:Phosphotransferases (Alcohol Group Acceptor); C046331:phosphoglucokinase