Fig. 2From: Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma modelIbrutinib disrupts brain endothelial integrity and inhibits ABC transporter function. Brain endothelial cell viability is not affected by ibrutinib treatment at varied doses (a). Dose-dependently, ibrutinib decreases brain endothelial cell–cell impedance, significantly 2 h after treatment seen with 5 and 10 µM with subsequent cell index plateau (*p < 0.05, **p < 0.005) (b). Bicellular junction protein ZO-1 and tricellular junction protein MarvelD2 was significantly decreased 2 h after 10 µM ibrutinib treatment (c). Junctional mRNA expression also decreased from 2 to 24 h after 10 µM treatment, without a washout period seen in tjp1 (ZO-1), MarvelD2 (tricellulin), Ocln (occludin), Cldn5 (claudin-5), Lsr (lipolysis stimulated lipoprotein receptor/angulin-1), and cldn3 (claudin-3) (d). High baseline BTK expression seen in both cytoplasm and nucleus of brain endothelial cells. Confirmatory immunostaining of ZO-1 expression demonstrated decreased tight junctional linear staining at 4 h, with rearrangement closer to baseline regarding adhesion expression by 24 h. (e). Silencing of BTK with siBTK results in decreased cell–cell impedance transiently and impaired tight junction gene expression (***p < 0.0005, ****p < 0.0001) (f, g). Ibrutinib dose-dependently inhibited Abcb1 function to increase rhodamine accumulation with higher FITC-H fluorescence measurement causing a shift of amplitude to the right, comparative to valspodar (ABCB1 inhibitor) treated cells (h). Monolayer endothelial cells treated with ibrutinib on transwells resulted in approximately 26% higher sodium fluorescein permeability compared with control treatment 24 h later (****p < 0.0001) (i)Back to article page