DHFR-CD双耐药基因增强转基因小鼠对大剂量化疗毒性的抵御能力

Protection against toxicity of high dose chemotherapy in mice transfected with double-mutant dihydrofolate reductase-cytidine deaminase gene

AIM: To explore the feasibility of transferring dihydrofolate reductase- (DHFR) gene and cytidine deaminase (CD) fusion gene into mouse bone marrow (BM) cells to induce resistance to high dose methotrexate (MTX) and cytosine arabinoside (Ara-C), and to improve the tolerance of myelosuppression following combination chemotherapy. METHODS: Human double-mutant DHFR-CD fusion gene was transferred into mouse BM cells by retroviral vector Granu-locyte-macrophage colony-forming unit (CFU-GM) assay was performed for retrovirally infected and drug treated mouse BM cells. DNA was extracted from mouse BM, and the expression of drug resistant genes was examined by PCR. RESULTS: Drug resistant colonies were formed by donor mouse BM cells co-cultured with the retrovirus producing cells, as well as the BM cells from recipient mice transplanted with the fusion gene transfected BM cells (CFU- GM of donor mice was 14%, X2= 42.55, P<0.01; CFU-GM of recipient mice was 20%, X2= 44.26, P<0.01). The drug resistance to both MTX and Ara-C was also increased in the recipient mice. The survival rate of gene transferred mice was significantly higher compared with the control mice X2= 7.42, P<0.01. Expression of the DHFR-CD fusion gene in the transfected mice was confirmed by PCR. CONCLUSION: Double drug resistant genes can be integrated and expressed in mouse bone marrow cells; furthermore, they can increase the drug resistance to MTX and Ara-C.