Background: Hematologic toxicity represents a major side effect of cytotoxic chemotherapy frequently preventing\nadequately dosed chemotherapy application and impeding therapeutic success. Transgenic (over)expression of\nchemotherapy resistance (CTX-R) genes in hematopoietic stem- and progenitor cells represents a potential strategy\nto overcome this problem. To apply this concept in the context of acute myeloid leukemia and myelodysplasia, we\nhave investigated the overexpression of the multidrug resistance 1 (MDR1) and the cytidine deaminase (CDD) gene\nconferring resistance to anthracyclines and cytarabine (Ara-C), the two most important drugs in the treatment of\nthese diseases.\nMethods: State-of-the-art, third generation, self-inactivating (SIN) lentiviral vectors were utilized to overexpress a\nhuman CDD-cDNA and a codon-optimized human MDR1-cDNA corrected for cryptic splice sites from a spleen\nfocus forming virus derived internal promoter. Studies were performed in myeloid 32D cells as well as primary\nlineage marker negative (linâË?â??) murine bone marrow cells and flow cytometric analysis of suspension cultures and\nclonogenic analysis of vector transduced cells following cytotoxic drug challenge were utilized as read outs.\nResults: Efficient chemoprotection of CDD and MDR1 transduced hematopoietic 32D as well as primary linâË?â?? cells\nwas proven in the context of Ara-C and anthracycline application. Both, CTX-R transduced 32D as well as primary\nhematopoietic cells displayed marked resistance at concentrations 5ââ?¬â??20 times the LD50 of non-transduced control\ncells. Moreover, simultaneous CDD/MDR1 gene transfer resulted in similar protection levels even when combined\nAra-C anthracycline treatment was applied. Furthermore, significant enrichment of transduced cells was observed\nupon cytotoxic drug administration.\nConclusions: Our data demonstrate efficient chemoprotection as well as enrichment of transduced cells in\nhematopoietic cell lines as well as primary murine hematopoietic progenitor cells following Ara-C and/or anthracycline\napplication, arguing for the efficacy as well as feasibility of our approach and warranting further evaluation of\nthis concept.
Loading....