RT Journal Article
SR Electronic
T1 Suppression of canine ABCB1 in MDCKII cells unmasks human ABCG2-mediated efflux of olaparib
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP jpet.118.250225
DO 10.1124/jpet.118.250225
A1 Yoo-Kyung Song
A1 Ji Eun Park
A1 Yunseok Oh
A1 Sungwoo Hyung
A1 Yoo-Seong Jeong
A1 Min-Soo Kim
A1 Wooin Lee
A1 Suk-Jae Chung
YR 2018
UL http://jpet.aspetjournals.org/content/early/2018/11/05/jpet.118.250225.abstract
AB Endogenous cABCB1 is expressed abundantly in MDCKII cells, and its presence often complicates the phenotyping of the transport process. Errors in estimating cER, as the result of the variable expression of cABCB1, were examined for the dual substrates of ABCB1 and ABCG2 in MDCKII cells expressing hABCG2. The mRNA and protein expression of cABCB1 was 60% and 55% lower, respectively, in MDCKII cells expressing hABCG2 compared to the values for the wild type, suggesting that the expression of endogenous cABCB1 became variable after the expression of hABCG2. To minimize the contribution of endogenous efflux, cABCB1 was suppressed kinetically (i.e., using verapamil as a selective inhibitor), or biochemically (i.e., transfecting short-hairpin RNA against cABCB1). Under these conditions of suppression, the cER values for irinotecan and topotecan, dual substrates of ABCB1 and ABCG2, were elevated by over 4-fold and 2-fold, respectively, in comparison to the values without the suppression. The cER of olaparib was similarly increased to 3- and 5-fold in MDCKII cells under the kinetic and biochemical suppression of cABCB1, respectively, suggesting that hABCG2-mediated efflux cannot be ruled out for olaparib. Since the substrate selectivity for ABCB1 and ABCG2 is considerably overlapped, the possibility of an inaccurate estimation of cER needs to be taken into consideration for the dual substrates in the case of the variable expression of cABCB1 in MDCKII cells.