Idelalisib down-regulates integrin-induced AKT phosphorylation.

<p>(A) Overlay histograms depict the mean AKT phosphorylation (pAKT) fluorescence intensity of CD19+ CLL cells in a representative case. The solid grey histogram depicts pAKT staining of CLL cells in co-culture with HMEC-1 without idelalisib and the black line histogram depicts of CLL cells in co-culture with HMEC-1 in presence of 5 μM idelalisib. AKT phosphorylation was analyzed in CLL cells after 1 hour and 24 hours of co-culture with HMEC-1 either in presence or absence of idelalisib. pAKT was evaluated by flow cytometry in CD19⁺ CLL cells gated from 4 different patients. (B) CLL cells were cultured in medium alone and in co-culture with HMEC-1, either in presence or absence of idelalisib for 1 hour or 24 hours. The bar diagrams represent the mean ± SEM of pAKT positive cells (%) (n=4, p<0.05). (C) Displayed are immunoblots from 3 representative CLL cell samples cultured alone or in co-cultured with HMEC-1 in presence or absence of idelalisib for 24 hours. Lysates were probed with antibodies to pAKT (S473) and actin. (D) CLL cells were stimulated or no stimulated with anti-VLA4 mAbs (clone 19H8) in the presence or absence of idelalisib. Displayed are the means ± SEM from 5 different patients (*p<0.05). The immunoblots on the right hand side depict AKT activation in 3 representative CLL samples stimulated with anti-VLA4 in presence or absence of idelalisib.