From the cyclooxygenase-2 inhibitor celecoxib to a novel class of 3-phosphoinositide-dependent protein kinase-1 inhibitors

J Zhu, JW Huang, PH Tseng, YT Yang, J Fowble… - Cancer research, 2004 - AACR
J Zhu, JW Huang, PH Tseng, YT Yang, J Fowble, CW Shiau, YJ Shaw, SK Kulp, CS Chen
Cancer research, 2004AACR
The blockade of Akt activation through the inhibition of 3-phosphoinositide-dependent
kinase-1 (PDK-1) represents a major signaling mechanism whereby celecoxib mediates
apoptosis. Celecoxib, however, is a weak PDK-1 inhibitor (IC50, 48 μm), requiring at least
30 μm to exhibit discernable effects on the growth of tumor cells in vitro. Here, we report the
structure-based optimization of celecoxib to develop PDK-1 inhibitors with greater potency in
enzyme inhibition and growth inhibition. Kinetics of PDK-1 inhibition by celecoxib with …
Abstract
The blockade of Akt activation through the inhibition of 3-phosphoinositide-dependent kinase-1 (PDK-1) represents a major signaling mechanism whereby celecoxib mediates apoptosis. Celecoxib, however, is a weak PDK-1 inhibitor (IC50, 48 μm), requiring at least 30 μm to exhibit discernable effects on the growth of tumor cells in vitro. Here, we report the structure-based optimization of celecoxib to develop PDK-1 inhibitors with greater potency in enzyme inhibition and growth inhibition. Kinetics of PDK-1 inhibition by celecoxib with respect to ATP suggest that celecoxib derivatives inhibit PDK-1 by competing with ATP for binding, a mechanism reminiscent to that of many kinase inhibitors. Structure-activity analysis together with molecular modeling was used to generate compounds that were tested for their potency in inhibiting PDK-1 kinase activity and in inducing apoptosis in PC-3 prostate cancer cells. Docking of potent compounds into the ATP-binding site of PDK-1 was performed for lead optimization, leading to two compounds, OSU-03012 and OSU-03013, with IC50 values in PDK-1 inhibition and apoptosis induction in the low μm range. Exposure of PC-3 cells to these agents led to Akt dephosphorylation and inhibition of p70 S6 kinase activity. Moreover, overexpression of constitutively active forms of PDK-1 and Akt partially protected OSU-03012-induced apoptosis. Screening in a panel of 60 cell lines and more extensive testing in PC-3 cells indicated that the mean concentration for total growth inhibition was ∼3 μm for both agents. Considering the conserved role of PDK-1/Akt signaling in promoting tumorigenesis, these celecoxib analogs are of translational relevance for cancer prevention and therapy.
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