The human MDR1 gene encodes a multispecific drug transporter, P- glycoprotein (Pgp), that prevents drug accumulation in resistant cells. Overexpression of MDR1 is sufficient for conferring multidrug resistance on otherwise normal cells. This suggests that MDR1 might be used in gene therapy to protect hematopoietic cells against chemotherapy-related myelotoxicity. Of 164 cancer- related gene therapy trials currently in force, nine incorporate the concept of hematopoietic cell chemoprotection; six of these use the MDR1 gene. Another application of MDR1 is to use it as an in vivo selectable marker to enhance the expression of linked foreign genes in transfected or virally transduced cells. Mouse experiments indicate that MDR1 can be chemoprotective and selectable in vivo, but attempts to use MDR1 as a chemoprotective agent in human gene therapy trials have, so far, been disappointing. Evidence will be provided suggesting that the reason for its poor in vivo performance in humans is that MDR1 is a stringent selectable marker that requires very high levels of P-glycoprotein, the MDR1 gene product, to mediate survival of transduced cells. Indeed, the most significant barriers to successful gene therapy with MDR1 appear to be transduction efficiency and gene expression--i.e., the number of cells that can be transduced and that can express high enough levels of MDR1 to survive selection. We hypothesize that MDR1 will serve as an effective in vivo selectable marker or chemoprotective gene only if the problem of stringency can be overcome.
Four specific aims are designed to test this hypothesis and to develop the optimal strategy for overcoming selection stringency: 1) Determine if MDR1 selection stringency can be overcome by maximizing gene transduction efficiency and gene expression levels with state-of- the-art gene therapy tools. 2) Determine if selection stringency can be overcome by using mutant versions of MDR1/Pgp as the selectable marker. 3) Determine if selection stringency can be overcome by using a two-step selection strategy. 4) Determine if MDR1 can confer an in vivo survival advantage on human hematopoietic cells. Building on results in Specific Aims 1-3, this aim will use primary human hematopoietic progenitors to study the survival of MDR1-transduced cells in NOD/SCID and SCID- hu mouse model systems.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA071866-06
Application #
6376295
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1996-07-01
Project End
2003-06-30
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
6
Fiscal Year
2001
Total Cost
$292,244
Indirect Cost
Name
City of Hope/Beckman Research Institute
Department
Type
DUNS #
City
Duarte
State
CA
Country
United States
Zip Code
91010
Ai, Cuiwei; Todorov, Ivan; Slovak, Marilyn L et al. (2007) Human marrow-derived mesodermal progenitor cells generate insulin-secreting islet-like clusters in vivo. Stem Cells Dev 16:757-70
Chan, Carmel T; Metz, Marianne Z; Kane, Susan E (2005) Differential sensitivities of trastuzumab (Herceptin)-resistant human breast cancer cells to phosphoinositide-3 kinase (PI-3K) and epidermal growth factor receptor (EGFR) kinase inhibitors. Breast Cancer Res Treat 91:187-201
Coleman, Aaron B; Metz, Marianne Z; Donohue, Cecile A et al. (2002) Chemosensitization by fibroblast growth factor-2 is not dependent upon proliferation, S-phase accumulation, or p53 status. Biochem Pharmacol 64:1111-23
Shih, Chu-chih; DiGiusto, David; Mamelak, Adam et al. (2002) Hematopoietic potential of neural stem cells: plasticity versus heterogeneity. Leuk Lymphoma 43:2263-8
Shih, C C; Weng, Y; Mamelak, A et al. (2001) Identification of a candidate human neurohematopoietic stem-cell population. Blood 98:2412-22
Kane, S E; Matsumoto, L; Metz, M Z et al. (2001) MDR1 bicistronic vectors: analysis of selection stringency, amplified gene expression, and vector stability in cell lines. Biochem Pharmacol 62:693-704
Shih, C C; Hu, J; Arber, D et al. (2000) Transplantation and growth characteristics of human fetal lymph node in immunodeficient mice. Exp Hematol 28:1046-53
Shih, C C; DiGiusto, D; Forman, S J (2000) Ex vivo expansion of transplantable human hematopoietic stem cells: where do we stand in the year 2000? J Hematother Stem Cell Res 9:621-8
Shih, C C; Hu, M C; Hu, J et al. (2000) A secreted and LIF-mediated stromal cell-derived activity that promotes ex vivo expansion of human hematopoietic stem cells. Blood 95:1957-66
Coleman, A B; Momand, J; Kane, S E (2000) Basic fibroblast growth factor sensitizes NIH 3T3 cells to apoptosis induced by cisplatin. Mol Pharmacol 57:324-33

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