Abcb1a (P-glycoprotein) limits brain exposure of the anticancer drug candidate seliciclib in vivo in adult mice

Erdő F, Nagy I, Tóth B, Bui A, Molnár É, Tímár Z, Magnan R, Krajcsi P.

Brain Res Bull. 2017 Jun;132:232-236. doi: 10.1016/j.brainresbull.2017.06.013. Epub 2017 Jun 16.
PMID: 28629814


Seliciclib displayed limited brain exposure in vivo in adult rats with mature blood-brain barrier (BBB). Selicilib was shown to be a specific substrate of human ABCB1 in vitro. To demonstrate that ABCB1/Abcb1 can limit brain exposure in vivo in mice we are showing that seliciclib is a substrate of mouse Abcb1a, the murine ABCB1 ortholog expressed in the BBB as LLC-PK-Abcb1a cells displayed an efflux ratio (ER) of 15.31±3.54 versus an ER of 1.44±0.10 in LLC-PK1-mock cells. Additionally, in the presence of LY335979, an ABCB1/Abcb1a specific inhibitor, the observed ER for seliciclib in the LLC-PK1-mMdr1a cells decreased to 1.05±0.25. To demonstrate in vivo relevance of seliciclib transport by Abcb1a mouse brain microdialysis experiments were carried out that showed that the AUCbrain/AUCblood ratio of 0.143 in anesthetized mice increased about two-fold to 0.279 in the presence of PSC833 another ABCB1/Abcb1a specific inhibitor. PSC833 also increased the brain exposure (AUCbrain) of seliciclib close to 2-fold (136 vs 242) in awake mice. In sum, Abcb1a significantly decreases seliciclib permeability in vitro and is partly responsible for limited brain exposure of seliciclib in vivo in mice.

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