Abstract
Recently, we have reported that N2Yc, a Moloney-based retrovirus vector expressing the Yc isoform of rat glutathione S-transferase (GST-Yc), conferred resistance to alkylating agents in mouse NIH-3T3 fibroblasts. In this report, we address the feasibility of using rat GST-Yc somatic gene transfer to confer chemoprotection to the hematopoietic system. Human chronic myelogenous leukemia K-562 cells were efficiently transduced with the N2Yc retrovirus vector and showed a significant increase in the 50% inhibitory concentration of chlorambucil (3.2- to 3.3-fold), mechlorethamine (4.7- to 5.3-fold), and melphalan (2.1- to 2.2-fold). In addition, primary murine clonogenic hematopoietic progenitor cells transduced with the N2Yc vector were significantly more resistant to alkylating agents in vitro than cells transduced with the antisense N2revYc vector. The survival of Yc-transduced hematopoietic colonies at 400 nM mechlorethamine and 4 μM chlorambucil was 39.4% and 42.6%, respectively, compared to 27.2% and 30.4% for N2revYc-transduced cells. Future experiments will determine the level of chemoprotection achievable in vivo following transplantation of N2Yc-transduced hematopoietic cells in mice.
Overview summary
Retrovirus-mediated gene transfer of rat GST-Yc was shown recently to confer alkylating drug resistance in mouse NIH-3T3 fibroblasts. However, the effect of GST-Yc retroviral transduction on the sensitivity to alkylating agents was found to be of variable magnitude in different cell lines, possibly in relation to differences in endogenous glutathione (GSH), in total glutathione S-transferase (GST) levels, or in the pattern of GST isoforms expression. Given the potential applicability of the chemoprotection mediated by GST-Yc to the gene therapy of cancer, the present report examines the ability of retrovirus-mediated transduction of rat GST-Yc to confer resistance to alkylating agents in hematopoietic cells. Transduction with a GST-Yc retrovirus was found to confer in vitro alkylator resistance in K-562 chronic myelogenous leukemia cells and in clonogenic primary mouse hematopoietic progenitor cells.
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