title: In vivo effects of myeloablative alkylator therapy on survival and differentiation of MGMTP140K-transduced human G-CSF-mobilized peripheral blood cells.
abstract: High-intensity alkylator-based chemotherapy is required to eradicate tumors expressing high levels of O6-methylguanine DNA methyltransferase (MGMT). This treatment, however, can lead to life-threatening myelosuppression. We investigated a gene therapy strategy to protect human granulocyte colony-stimulating factor-mobilized peripheral blood CD34+ cells (MPB) from a high-intensity alkylator-based regimen. We transduced MPB with an oncoretroviral vector that coexpresses MGMT(P140K) and the enhanced green fluorescent protein (EGFP) (n = 5 donors). At 4 weeks posttransplantation into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice, cohorts were not treated or were treated with low- or high-intensity alkylating chemotherapy. In the high-intensity-treated cohort, it was necessary to infuse NOD/SCID bone marrow (BM) to alleviate hematopoietic toxicity. At 8 weeks posttreatment, human CD45+ cells in the BM of mice treated with either regimen were EGFP+ and contained MGMT-specific DNA repair activity. In cohorts receiving low-intensity therapy, both primitive and mature hematopoietic cells were present in the BM. Although B-lymphoid and myeloid cells were resistant to in vivo drug treatment in cohorts that received high-intensity therapy, no human CD34+ cells or B-cell precursors were detected. These data suggest that improved strategies to optimize repair of DNA damage in primitive human hematopoietic cells are needed when using high-intensity anti-cancer therapy.
authors.affiliation: Herman B. Wells Center for Pediatric Research, Department of Pediatrics, The Riley Hospital for Children, 1044 West Walnut Street R4 468, Indianapolis, IN 46202-5525, USA.
authors.forename: Shanbao
authors.initials: S
authors.lastname: Cai
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Hartwell
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Cooper
authors.forename: Beth E
authors.initials: BE
authors.lastname: Juliar
authors.forename: Emi
authors.initials: E
authors.lastname: Kreklau
authors.forename: Rafat
authors.initials: R
authors.lastname: Abonour
authors.forename: W Scott
authors.initials: WS
authors.lastname: Goebel
authors.forename: Karen E
authors.initials: KE
authors.lastname: Pollok
mesh_terms: D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000009:adverse effects*; D001773:Blood Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D002330:Carmustine / Q000009:adverse effects*; D002454:Cell Differentiation; D002470:Cell Survival / Q000187:drug effects; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics* / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D016511:Severe Combined Immunodeficiency / Q000188:drug therapy; D014161:Transduction, Genetic; D023041:Xenograft Model Antitumor Assays
chemical_list: D018906:Antineoplastic Agents, Alkylating; D016179:Granulocyte Colony-Stimulating Factor; D049452:Green Fluorescent Proteins; D019853:O(6)-Methylguanine-DNA Methyltransferase; D002330:Carmustine