title: The Akt-inhibitor Erufosine induces apoptotic cell death in prostate cancer cells and increases the short term effects of ionizing radiation.
abstract: OBJECTIVE
  The phosphatidylinositol-3-kinase (PI3K)/Akt pathway is frequently deregulated in prostate cancer and associated with neoplastic transformation, malignant progression, and enhanced resistance to classical chemotherapy and radiotherapy. Thus, it is a promising target for therapeutic intervention. In the present study, the cytotoxic action of the Akt inhibitor Erufosine (ErPC3) was analyzed in prostate cancer cells and compared to the cytotoxicity of the PI3K inhibitor LY294002. Moreover, the efficacy of combined treatment with Akt inhibitors and ionizing radiation in prostate cancer cells was examined.
  
  
  METHODS
  Prostate cancer cell lines PC3, DU145, and LNCaP were treated with ErPC3 (1-100 µM), LY294002 (25-100 µM), irradiated (0-10 Gy), or subjected to combined treatments. Cell viability was determined by the WST-1 assay. Apoptosis induction was analyzed by flow cytometry after staining with propidium iodide in a hypotonic citrate buffer, and by Western blotting using antibodies against caspase-3 and its substrate PARP. Akt activity and regulation of the expression of Bcl-2 family members and key downstream effectors involved in apoptosis regulation were examined by Western blot analysis.
  
  
  RESULTS
  The Akt inhibitor ErPC3 exerted anti-neoplastic effects in prostate cancer cells, however with different potency. The anti-neoplastic action of ErPC3 was associated with reduced phosphoserine 473-Akt levels and induction of apoptosis. PC3 and LNCaP prostate cancer cells were also sensitive to treatment with the PI3K inhibitor LY294002. However, the ErPC3-sensitive PC3-cells were less susceptible to LY294002 than the ErPC3-refractory LNCaP cells. Although both cell lines were largely resistant to radiation-induced apoptosis, both cell lines showed higher levels of apoptotic cell death when ErPC3 was combined with radiotherapy.
  
  
  CONCLUSIONS
  Our data suggest that constitutive Akt activation and survival are controlled by different different molecular mechanisms in the two prostate cancer cell lines - one which is sensitive to the Akt-inhibitor ErPC3 and one which is more sensitive to the PI3K-inhibitor LY294002. Our findings underline the importance for the definition of predictive biomarkers that allow the selection patients that may benefit from the treatment with a specific signal transduction modifier.
authors.affiliation: Department of Radiation Oncology, University of Tübingen, Hoppe-Seyler-Straße 3, D-72076 Tübingen, Germany.
authors.forename: Justine
authors.initials: J
authors.lastname: Rudner
authors.forename: Carola-Ellen
authors.initials: CE
authors.lastname: Ruiner
authors.forename: René
authors.initials: R
authors.lastname: Handrick
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Eibl
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
authors.forename: Verena
authors.initials: V
authors.lastname: Jendrossek
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002867:Chromones / Q000008:administration & dosage; D006801:Humans; D008297:Male; D009025:Morpholines / Q000008:administration & dosage; D010755:Organophosphates / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use*; D011839:Radiation, Ionizing; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D009025:Morpholines; D010755:Organophosphates; D047428:Protein Kinase Inhibitors; D000644:Quaternary Ammonium Compounds; D011838:Radiation-Sensitizing Agents; C472787:erucylphospho-N,N,N-trimethylpropylammonium; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051057:Proto-Oncogene Proteins c-akt