The K252a derivatives, inhibitors for the PAK/MLK kinase family selectively block the growth of RAS transformants

Cancer J. Jul-Aug 2002;8(4):328-36. doi: 10.1097/00130404-200207000-00009.


Background: Oncogenic RAS mutants such as v-Ha-RAS activate members of Rac/CDC42-dependent kinases (PAKs) and appear to contribute to the development of more than 30% of all human cancers. PAK1 activation is essential for oncogenic RAS transformation, and several chemical compounds that inhibit Tyr kinases essential for the RAS-induced activation of PAK1 strongly suppress RAS transformation either in cell culture or in vivo (nude mice). Although we have developed a cell-permeable PAK-specific peptide inhibitor called WR-PA18, so far no chemical (metabolically stable) compound has been developed that directly inhibits PAK1 in a highly selective manner. Thus, we have explored such a PAK1 inhibitor(s) among synthetic derivatives of an adenosine triphosphate antagonist.

Results: From the naturally occurring adenosine triphosphate antagonist K252a, we have developed two bulky derivatives, called CEP-1347 and KT D606 (a K252a dimer), which selectively inhibit PAKs or mixed-lineage kinases both in vitro and in cell culture and convert v-Ha-RAS-transformed NIH 3T3 cells to flat fibroblasts similar to the parental normal cells. Furthermore, these two K252a analogues suppress the proliferation of v-Ha-RAS transformants, but not the normal cells.

Conclusion: These bulky adenosine triphosphate antagonists derived from K252a or related indolocarbazole compounds such as staurosporine would be potentially useful for the treatment of RAS/ PAK1-induced cancers, once their anti-PAK1 activity is significantly potentiated by a few additional chemical modifications at the sugar ring suggested in this paper.

MeSH terms

  • 3T3 Cells
  • Adenosine Triphosphate / antagonists & inhibitors
  • Animals
  • Carbazoles / chemistry
  • Carbazoles / pharmacology*
  • Cell Division / drug effects*
  • Cell Line, Transformed
  • Cell Transformation, Neoplastic / drug effects
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology*
  • Genes, ras*
  • Indole Alkaloids
  • Indoles / chemistry
  • Indoles / pharmacology*
  • MAP Kinase Kinase Kinases / antagonists & inhibitors*
  • MAP Kinase Kinase Kinases / biosynthesis
  • Mice
  • Protein Kinase C / antagonists & inhibitors*
  • Protein Kinase C / biosynthesis
  • Protein Serine-Threonine Kinases / antagonists & inhibitors*
  • Staurosporine / chemistry


  • Carbazoles
  • Enzyme Inhibitors
  • Indole Alkaloids
  • Indoles
  • 3,9-bis((ethylthio)methyl)-K-252a
  • Adenosine Triphosphate
  • staurosporine aglycone
  • Protein Serine-Threonine Kinases
  • Protein Kinase C
  • MAP Kinase Kinase Kinases
  • mitogen-activated protein kinase kinase kinase 11
  • Staurosporine