Gene therapy for thioguanine-resistant human leukemia.
The feasibility of using retroviral gene therapy to overcome drug resistance was assessed by determining the efficiency by which a retrovirus containing the human HGPRT gene could sensitize hypoxanthine-guanine phosphoribosyltransferase (HGPRT) negative human promyelocytic leukemia cells to 6-thioguanine. A single three-hour exposure at a virus to cell ratio of 6 X 2:1 restored sensitivity to 70(+/- 18)% of the clonogenic cells. The efficacy varied as a function of virus concentration and duration of viral exposure; the time allowed for integration and expression between one and five days post-infection had little effect. Cells successfully sensitized contained a proviral insert and expressed HGPRT activity that ranged from 1 to 92% of that in the wild-type cells. The mutation rate of the inserted gene varied from the same as that of the endogenous HGPRT gene to 200-fold greater in different clones. Failure of sensitization following viral exposure was associated with absence of an integrated provirus, and clonogenic cells failing to be sensitized by one virus exposure were sensitized with approximately the same efficiency by a second viral exposure. These results demonstrate the feasibility of transferring a drug sensitivity gene to a human leukemia cell line.
D002460:Cell Line; D004351:Drug Resistance; D005786:Gene Expression Regulation; D005818:Genetic Engineering; D005822:Genetic Vectors; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D066298:In Vitro Techniques; D015470:Leukemia, Myeloid, Acute / Q000628:therapy*; D012190:Retroviridae / Q000235:genetics; D013866:Thioguanine / Q000494:pharmacology; D013997:Time Factors
D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine