title: Molecular targeting of prostate cancer cells by a triple drug combination down-regulates integrin driven adhesion processes, delays cell cycle progression and interferes with the cdk-cyclin axis.
abstract: BACKGROUND
  Single drug use has not achieved satisfactory results in the treatment of prostate cancer, despite application of increasingly widespread targeted therapeutics. In the present study, the combined impact of the mammalian target of rapamycin (mTOR)-inhibitor RAD001, the dual EGFr and VGEFr tyrosine kinase inhibitor AEE788 and the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on prostate cancer growth and adhesion in vitro was investigated.
  
  
  METHODS
  PC-3, DU-145 and LNCaP cells were treated with RAD001, AEE788 or VPA or with a RAD-AEE-VPA combination. Tumor cell growth, cell cycle progression and cell cycle regulating proteins were then investigated by MTT-assay, flow cytometry and western blotting, respectively. Furthermore, tumor cell adhesion to vascular endothelium or to immobilized extracellular matrix proteins as well as migratory properties of the cells was evaluated, and integrin α and β subtypes were analyzed. Finally, effects of drug treatment on cell signaling pathways were determined.
  
  
  RESULTS
  All drugs, separately applied, reduced tumor cell adhesion, migration and growth. A much stronger anti-cancer effect was evoked by the triple drug combination. Particularly, cdk1, 2 and 4 and cyclin B were reduced, whereas p27 was elevated. In addition, simultaneous application of RAD001, AEE788 and VPA altered the membranous, cytoplasmic and gene expression pattern of various integrin α and β subtypes, reduced integrin-linked kinase (ILK) and deactivated focal adhesion kinase (FAK). Signaling analysis revealed that EGFr and the downstream target Akt, as well as p70S6k was distinctly modified in the presence of the drug combination.
  
  
  CONCLUSIONS
  Simultaneous targeting of several key proteins in prostate cancer cells provides an advantage over targeting a single pathway. Since strong anti-tumor properties became evident with respect to cell growth and adhesion dynamics, the triple drug combination might provide progress in the treatment of advanced prostate cancer.
authors.affiliation: Department of Urology, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Wedel
authors.forename: Lukasz
authors.initials: L
authors.lastname: Hudak
authors.forename: Jens-Michael
authors.initials: JM
authors.lastname: Seibel
authors.forename: Jasmina
authors.initials: J
authors.lastname: Makarević
authors.forename: Eva
authors.initials: E
authors.lastname: Juengel
authors.forename: Igor
authors.initials: I
authors.lastname: Tsaur
authors.forename: Ana
authors.initials: A
authors.lastname: Waaga-Gasser
authors.forename: Axel
authors.initials: A
authors.lastname: Haferkamp
authors.forename: Roman A
authors.initials: RA
authors.lastname: Blaheta
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects*; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D000068338:Everolimus; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D008297:Male; D058990:Molecular Targeted Therapy; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011687:Purines / Q000008:administration & dosage; D015398:Signal Transduction; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives; D014635:Valproic Acid / Q000008:administration & dosage
chemical_list: D016213:Cyclins; D016023:Integrins; D011687:Purines; D014635:Valproic Acid; D000068338:Everolimus; D018844:Cyclin-Dependent Kinases; C489254:AEE 788; D020123:Sirolimus