In vitro study | BMS-599626 Hydrochloride inhibits the proliferation of tumor cells that are dependent on HER1/HER2 signaling.BMS-599626 Hydrochloride (0.03-8 μM; 1 huors) results in the inhibition of receptor autophosphorylation, as well as MAPK phosphorylation, with IC 50 s of 0.3 and 0.22 μM, respectively, in Sal2 cells which express a CD8HER2 fusion protein. BMS-599626 Hydrochloride abrogates HER1 and HER2 signaling and inhibited the proliferation of tumor cell lines that are dependent on these receptors, with IC 50 s in the range of 0.24 to 1 μM.In GEO cells, HER1 phosphorylation is stimulated by treatment with EGF and is inhibited by BMS-599626 Hydrochloride (IC 50 =0. 75 μM).There is also nearly complete inhibition of EGF-dependent MAPK (0. 8 μM) but only partial inhibition of AKT signaling.The latter likely reflects the activation of AKT by multiple upstream signals.Treatment of N87 cells with BMS-599626 Hydrochloride leads to the inhibition of HER2 (0. 38 μM), which is expressed to a high level because of gene amplification, as well as MAPK and AKT phosphorylation (0.35 μM for both). At the molecular level, in HN-5 cells the agent (BMS-599626 Hydrochloride) inhibits the expression of pEGFR, pHER2, cyclins D and E, pRb, pAkt, pMAPK, pCDK1 and 2, CDK 6, and Ku70 proteins. BMS-599626 Hydrochloride also induced accumulation of cells in the G1 cell cycle phase, inhibited cell growth, enhanced radiosensitivity, and prolonged the presence of γ-H AX foci up to 24 h after radiation. |