Previously, we have synthesized a novel
cyclin-dependent kinase (CDK) inhibitor, 2-[1,1'
biphenyl]-4-yl-N-[5-(1,1-dioxo-1λ(6) -isothiazolidin-2-yl)-1H-indazol-3-yl]
acetamide (BAI) and reported its anti-
cancer activity in
head and neck cancer cells. In this study, we further evaluated the effect of BAI on growth of various human
cancer cell lines, including A549 (
nonsmall cell lung cancer), HCT116 (colon), and Caki (kidney). Profoundly, results of XTT and clonogenic assays demonstrated that BAI at nanomolar concentrations (20-60 nM) inhibited growth of A549, HCT116, and Caki cells, suggesting the anti-
cancer potency. We show that BAI induced a dose-dependent apoptotic cell death in these human
cancer cells, as measured by fluorescence-activated cell sorting (FACS). Interestingly, further biochemical analysis showed that treatment with BAI at 20 nM induced apoptosis in A549 cells in association with activation of
caspases, cleavage of
phospholipase C-γ1 (PLC-γ1), and inhibition of Akt in A549 cells. Importantly, pharmacological inhibition study revealed that pretreatment with
z-VAD-fmk, a pan
caspase inhibitor strongly blocked the BAI-induced apoptosis in A549 cells. Transfection analysis with Akt
cDNA encoding constitutively active Akt further addressed the significance of Akt inhibition in the BAI-induced apoptosis in A549 cells. Notably, disruption of the PI3K/Akt pathway by
LY294002, a PI3K/Akt inhibitor potentiated apoptosis in A549 cells by BAI at a subcytotoxic concentration. These findings collectively suggest that BAI potently inhibits growth of A549, HCT116, and Caki cells, and that the BAI-induced apoptosis in A549 cells is associated with activation of
caspases, and inhibition of Akt.