Novel Small Molecule Inhibitors of 3-Phosphoinositide-dependent Kinase-1*

The phosphoinositide 3-kinase/3-phosphoinositide-dependent kinase 1 (PDK1)/Akt signaling pathway plays a key role in cancer cell growth, survival, and tumor angiogenesis and represents a promising target for anticancer drugs. Here, we describe three potent PDK1 inhibitors, BX-795, BX-912, and BX-320 (IC50 = 11–30 nm) and their initial biological characterization. The inhibitors blocked PDK1/Akt signaling in tumor cells and inhibited the anchorage-dependent growth of a variety of tumor cell lines in culture or induced apoptosis. A number of cancer cell lines with elevated Akt activity were >30-fold more sensitive to growth inhibition by PDK1 inhibitors in soft agar than on tissue culture plastic, consistent with the cell survival function of the PDK1/Akt signaling pathway, which is particularly important for unattached cells. BX-320 inhibited the growth of LOX melanoma tumors in the lungs of nude mice after injection of tumor cells into the tail vein. The effect of BX-320 on cancer cell growth in vitro and in vivo indicates that PDK1 inhibitors may have clinical utility as anticancer agents.

[1]  Michael Koutsilieris,et al.  The Akt pathway: molecular targets for anti-cancer drug development. , 2004, Current cancer drug targets.

[2]  M. Andjelkovic,et al.  Insulin-stimulated Protein Kinase B Phosphorylation on Ser-473 Is Independent of Its Activity and Occurs through a Staurosporine-insensitive Kinase* , 2001, The Journal of Biological Chemistry.

[3]  D. Alessi,et al.  Further evidence that 3‐phosphoinositide‐dependent protein kinase‐1 (PDK1) is required for the stability and phosphorylation of protein kinase C (PKC) isoforms , 2000, FEBS letters.

[4]  P. Cohen,et al.  Mechanism of activation of protein kinase B by insulin and IGF‐1. , 1996, The EMBO journal.

[5]  G. Thomas,et al.  Ribosomal S6 kinase signaling and the control of translation. , 1999, Experimental cell research.

[6]  M. Noble,et al.  Structure-based design of 2-arylamino-4-cyclohexylmethyl-5-nitroso-6-aminopyrimidine inhibitors of cyclin-dependent kinases 1 and 2. , 2003, Bioorganic & medicinal chemistry letters.

[7]  Philip R. Cohen,et al.  Protein kinase C isotypes controlled by phosphoinositide 3-kinase through the protein kinase PDK1. , 1998, Science.

[8]  N. C. Price,et al.  Binding of phosphatidylinositol 3,4,5-trisphosphate to the pleckstrin homology domain of protein kinase B induces a conformational change. , 2003, The Biochemical journal.

[9]  J. Woodgett,et al.  Unravelling the activation mechanisms of protein kinase B/Akt , 2003, FEBS letters.

[10]  Brian A. Hemmings,et al.  Protein Kinase B Localization and Activation Differentially Affect S6 Kinase 1 Activity and Eukaryotic Translation Initiation Factor 4E-Binding Protein 1 Phosphorylation , 1999, Molecular and Cellular Biology.

[11]  A. Casamayor,et al.  PDK1 acquires PDK2 activity in the presence of a synthetic peptide derived from the carboxyl terminus of PRK2 , 1999, Current Biology.

[12]  J. Downward.  PI 3-kinase, Akt and cell survival. , 2004, Seminars in cell & developmental biology.

[13]  B. Hemmings,et al.  Identification of a PKB/Akt Hydrophobic Motif Ser-473 Kinase as DNA-dependent Protein Kinase*♦ , 2004, Journal of Biological Chemistry.

[14]  D. Rawlings,et al.  Protein Kinase C βII Regulates Akt Phosphorylation on Ser-473 in a Cell Type- and Stimulus-specific Fashion*♦ , 2004, Journal of Biological Chemistry.

[15]  I. Shiojima,et al.  Role of Akt Signaling in Vascular Homeostasis and Angiogenesis , 2002, Circulation research.

[16]  S. Dedhar,et al.  Regulation of Protein Kinase B/Akt-Serine 473 Phosphorylation by Integrin-linked Kinase , 2001, The Journal of Biological Chemistry.

[17]  R. Parsons,et al.  PTEN: life as a tumor suppressor. , 2001, Experimental cell research.

[18]  M. Simons,et al.  Regulation of protein kinase B/Akt activity and Ser473 phosphorylation by protein kinase Cα in endothelial cells , 2004 .

[19]  S. Liou,et al.  Randomized phase II study of multiple dose levels of CCI-779, a novel mammalian target of rapamycin kinase inhibitor, in patients with advanced refractory renal cell carcinoma. , 2004, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[20]  D. V. van Aalten,et al.  PDK1, the master regulator of AGC kinase signal transduction. , 2004, Seminars in cell & developmental biology.

[21]  David Komander,et al.  High resolution crystal structure of the human PDK1 catalytic domain defines the regulatory phosphopeptide docking site , 2002, The EMBO journal.

[22]  A. Toker.  PDK-1 and protein kinase C phosphorylation. , 2003, Methods in molecular biology.

[23]  Stephen Green,et al.  Cyclin-dependent kinase 4 inhibitors as a treatment for cancer. Part 1: identification and optimisation of substituted 4,6-bis anilino pyrimidines. , 2003, Bioorganic & medicinal chemistry letters.

[24]  G. Mills,et al.  The PTEN/MMAC1/TEP tumor suppressor gene decreases cell growth and induces apoptosis and anoikis in breast cancer cells , 1999, Oncogene.

[25]  P. Cohen,et al.  Characterization of a 3-phosphoinositide-dependent protein kinase which phosphorylates and activates protein kinase Bα , 1997, Current Biology.

[26]  D. Stokoe,et al.  Inhibition of PDK-1 activity causes a reduction in cell proliferation and survival , 2000, Current Biology.

[27]  A. Toker,et al.  3'-phosphoinositide-dependent kinase-1 (PDK-1) in PI 3-kinase signaling. , 2002, Frontiers in bioscience : a journal and virtual library.

[28]  D. Alessi,et al.  Evidence That 3-Phosphoinositide-dependent Protein Kinase-1 Mediates Phosphorylation of p70 S6 Kinase in Vivoat Thr-412 as well as Thr-252* , 1999, The Journal of Biological Chemistry.

[29]  B. Hemmings,et al.  Structure, regulation and function of PKB/AKT--a major therapeutic target. , 2004, Biochimica et biophysica acta.

[30]  William R Sellers,et al.  The biology and clinical relevance of the PTEN tumor suppressor pathway. , 2004, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[31]  K. Inoki,et al.  TSC2: filling the GAP in the mTOR signaling pathway. , 2004, Trends in biochemical sciences.

[32]  B. Calabretta,et al.  Transformation of hematopoietic cells by BCR/ABL requires activation of a PI‐3k/Akt‐dependent pathway , 1997, The EMBO journal.

[33]  T. Tsuruo,et al.  Interference with PDK1-Akt survival signaling pathway by UCN-01 (7-hydroxystaurosporine) , 2002, Oncogene.

[34]  A. Newton,et al.  Akt/Protein Kinase B Is Regulated by Autophosphorylation at the Hypothetical PDK-2 Site* , 2000, The Journal of Biological Chemistry.

[35]  A. Newton,et al.  Regulation of protein kinase C ζ by PI 3-kinase and PDK-1 , 1998, Current Biology.

[36]  P. Cohen,et al.  The role of 3-phosphoinositide-dependent protein kinase 1 in activating AGC kinases defined in embryonic stem cells , 2000, Current Biology.

[37]  Asim Khwaja,et al.  Matrix adhesion and Ras transformation both activate a phosphoinositide 3‐OH kinase and protein kinase B/Akt cellular survival pathway , 1997, The EMBO journal.

[38]  M. Andjelkovic,et al.  Phosphorylation and activation of p70s6k by PDK1. , 1998, Science.

[39]  Dario R. Alessi,et al.  3-Phosphoinositide-dependent protein kinase 1 (PDK1) phosphorylates and activates the p70 S6 kinase in vivo and in vitro , 1998, Current Biology.