The Impact of Endogenous Breast Cancer Resistance Protein on Human P-Glycoprotein-Mediated Transport Assays Using LLC-PK1 Cells Transfected With Human P-Glycoprotein

Calculation of an Apical Efflux Ratio from P-Glycoprotein (P-gp) In Vitro Transport Experiments Shows an Improved Correlation with In Vivo Cerebrospinal Fluid Measurements in Rats: Impact on P-gp Screening and Compound Optimization

“…LLC-PK1 cells were selected because they offer the advantage of consistently over-expressing human P-gp (allowing for high sensitivity and reproducibility) in a host cell line that is not of human origin (i.e., does not express endogenous human efflux transporters) (Kuteykin-Teplyakov et al, 2010). Whilst we cannot rule out the potential influence of endogenous porcine transporters in LLC-PK1 cells (Miyamoto et al, 2019), it is reasonable to expect that this is less of a concern than in more classically used cell lines such as Caco-2, which are of human origin and are known to endogenously express multiple human transporters at significant levels, including MRP2 and BCRP, in addition to P-gp.…”

Knockout of ABC transporters by CRISPR/Cas9 contributes to reliable and accurate transporter substrate identification for drug discovery

“…Because of a lack of human transporters in MDCK and LLC-PK1, human transporter genes are usually introduced into cells transiently or stably to explore drug transport. However, overexpression MDCK or LLC-PK1 cells always have a strong background signal from the endogenous nonhuman transporters ( Miyamoto et al, 2019 ; Crowe, 2021 ). This interferes with permeability and transporter studies, leading to less reliable data.…”