title: Targeting Cdc42 with the small molecule drug AZA197 suppresses primary colon cancer growth and prolongs survival in a preclinical mouse xenograft model by downregulation of PAK1 activity.
abstract: BACKGROUND
  Rho GTPases play important roles in cytoskeleton organization, cell cycle progression and are key regulators of tumor progression. Strategies to modulate increased Rho GTPase activities during cancer progression could have therapeutic potential.
  
  
  METHODS
  We report here the characterization of a Cdc42-selective small-molecule inhibitor AZA197 for the treatment of colon cancer that was developed based on structural information known from previously developed compounds affecting Rho GTPase activation. We investigated the effects of AZA197 treatment on RhoA, Rac1 and Cdc42 activities and associated molecular mechanisms in colon cancer cells in vitro. Therapeutic effects of AZA197 were examined in vivo using a xenograft mouse model of SW620 human colon cancer cells. After treatment, tumors were excised and processed for Ki-67 staining, TUNEL assays and Western blotting to evaluate proliferative and apoptotic effects induced by AZA197.
  
  
  RESULTS
  In SW620 and HT-29 human colon cancer cells, AZA197 demonstrated selectivity for Cdc42 without inhibition of Rac1 or RhoA GTPases from the same family. AZA197 suppressed colon cancer cell proliferation, cell migration and invasion and increased apoptosis associated with down-regulation of the PAK1 and ERK signaling pathways in vitro. Furthermore, systemic AZA197 treatment reduced tumor growth in vivo and significantly increased mouse survival in SW620 tumor xenografts. Ki-67 staining and tissue TUNEL assays showed that both inhibition of cell proliferation and induction of apoptosis associated with reduced PAK/ERK activation contributed to the AZA197-induced therapeutic effects in vivo.
  
  
  CONCLUSIONS
  These data indicate the therapeutic potential of the small-molecule inhibitor AZA197 based on targeting Cdc42 GTPase activity to modulate colorectal cancer growth.
authors.affiliation: Laboratory for Molecular Cellular Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Waehringerstrasse 13, A-1090 Vienna, Austria. dietmar.abraham@meduniwien.ac.at.
authors.forename: Karin
authors.initials: K
authors.lastname: Zins
authors.forename: Sandun
authors.initials: S
authors.lastname: Gunawardhana
authors.forename: Trevor
authors.initials: T
authors.lastname: Lucas
authors.forename: Dietmar
authors.initials: D
authors.lastname: Abraham
authors.forename: Seyedhossein
authors.initials: S
authors.lastname: Aharinejad
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000473:pathology*; D015536:Down-Regulation / Q000187:drug effects*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D058990:Molecular Targeted Therapy; D009361:Neoplasm Invasiveness; D011485:Protein Binding / Q000187:drug effects; D011743:Pyrimidines / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D016019:Survival Analysis; D023041:Xenograft Model Antitumor Assays; D020764:cdc42 GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054462:p21-Activated Kinases / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D007211:Indoles; C000589260:N2-(4-diethylamino-1-methylbutyl)-N4-(2-(1H-indol-3-yl)ethyl)-6-methylpyrimidine-2,4-diamine; D011743:Pyrimidines; D054852:Small Molecule Libraries; D007770:L-Lactate Dehydrogenase; D054462:p21-Activated Kinases; D020764:cdc42 GTP-Binding Protein