PCI-24781 (CRA-024781) can inhibit HDAC1, HDAC2, HDAC3, HDAC6, HDAC8 and HDAC10 with Ki of 7 nM, 19 nM, 8.2 nM, 17 nM, 280 nM, 24 nM. PCI-24781 can inhibit multidrug-resistant sarcoma cell lines in dose-dependent accumulation of acetylated histone, p21 and poly(ADP-ribose)polymerase (PARP) cleavage products. PCI-24781 can inhibit sarcoma cell lines with IC50 of 0.43 to 2.7 nM. PCI-24781 reverses drug resistance in all four multidrug-resistant sarcoma cell lines.
In vivo
PCI-24781 [50 mg/kg/day] and control solutions were administered to BK5.erbB2 mice for 4 weeks. Treatment of BK5.erbB2 mice with PCI-24781 for 1 month prevented 79% of GBCa cases from progression and showed a clinical effect in 47% of cases. Treatment with PCI-24781 resulted in decreased expression of Muc4, an intramembrane ligand for ErbB2, in BTC cells. PCI-24781 had more effects on growth inhibition of BTC cells than SAHA. PCI-24781 effectively inhibited the growth of gemcitabine-resistant cells.