Abstract
Objective—To induce chemoresistance in a normal canine cell line through the transduction of the canine multidrug resistance 1 gene (mdr1).
Sample Population—Madin-Darby canine kidney (MDCK) epithelial cell line.
Procedures—The full-length canine mdr1 cDNA clone isolated in our laboratory was inserted into a Moloney murine leukemia virus–based vector to construct the retroviral vector, pLNC-cMDR1. After retroviral transduction of pLNC-cMDR1 into MDCK cells, the expression and function of the P-glycoprotein, a product of mdr1, were assessed by immunoblotting, measurement of rhodamine123 (Rh123) retention, and drug sensitivity assays.
Results—P-glycoprotein was strongly expressed in cells transduced with pLNC-cMDR1. This P-glycoprotein was fully functional, as demonstrated by the decreased Rh123 retention and the increased resistance to chemotherapeutic drugs. Measured as 50% inhibitory concentrations, resistance increased 59 times to vincristine and 25 times to doxorubicin in MDCK cells after transduction of pLNC-cMDR1.
Conclusions and Clinical Relevance—Transduction of canine mdr1 is an effective method for inducing chemoresistance in normal canine cells. This system may be applicable to the induction of drug resistance in hematopoietic cells.