In vitro Evaluation of ABCB1 After Exposure to Prednisolone and Enrofloxacin in Two Canine Lymphoid Cell Lines: A Pilot Study

Multidrug resistance (MDR), a common cause of chemotherapeutic failure, is associated with the expression of P-glycoprotein (P-gp), encoded for by ABCB1, the multidrug resistance gene. Our purpose was to determine whether ABCB1 expression is expressed after exposure of two canine lymphoid cell lines to prednisolone or enrofloxacin. Two established lymphoid cell lines (GL-1, 17-71) were cultured for 14 days, during which cell lines were exposed to drug concentrations equivalent to clinically relevant doses of either prednisolone or enrofloxacin. RNA was extracted from cultured cells and RT-PCR was performed to evaluate ABCB1 expression. No ABCB1 expression was detected in either lymphoid cell line with exposure to prednisolone or enrofloxacin. The ABCB1 gene does not appear to be upregulated using these drugs in these cell lines in the time frame examined. Pretreatment with corticosteroids prior to chemotherapeutic administration may not induce ABCB1 drug resistance in canine lymphoid cells as has been reported.