title: Manipulation of radiation-induced bystander effect in prostate adenocarcinoma by dose and tumor differentiation grade: in vitro study.
abstract: OBJECTIVE
  This in vitro study evaluated the ability of prostate adenocarcinoma (ADC) cells to induce radiation-induced bystander effect (RIBE) exploring the factors that may be responsible and affect its intensity. The idea was to mimic a strong, clinically applicable RIBE that could lead to the development of innovative approaches in modern radiotherapy of prostate cancer, especially for those patients with hormone-refractory ADC in which radiotherapy might have a limited role.
  
  
  METHODS
  Two human prostate cancer cell lines of different differentiation, PC-3 and DU-145, have been irradiated using wide range of doses to obtain radiation-conditioned medium (RCM), which was used to treat the unirradiated cells and to evaluate the cytokines level. Using a trypan blue dye exclusion method, cell growth was assessed.
  
  
  RESULTS
  Prostate ADC cells were able to induce RIBE; intensity depended on dose and cell differentiation. RIBE intensity of DU-145 was not correlated with the cytokines level, while for PC-3 Interleukin-6 (IL-6) correlates with strongest RIBE induced by 20 Gy.
  
  
  CONCLUSIONS
  RIBE can be manipulated by modifying radiation dose and depends on cell differentiation status. IL-6 correlates with RIBE after exposure of PC-3 to a very high dose of radiation, thus indicates its possible involvement in bystander signaling.
authors.affiliation: "La Sapienza" University, Sant' Andrea Hospital, Radiation Oncology , Rome , Italy.
authors.forename: Slavisa
authors.initials: S
authors.lastname: Tubin
authors.forename: Maurizio
authors.initials: M
authors.lastname: Valeriani
authors.forename: Gerardo
authors.initials: G
authors.lastname: Salerno
authors.forename: Stefano
authors.initials: S
authors.lastname: Bracci
authors.forename: Antonella
authors.initials: A
authors.lastname: Stoppacciaro
authors.forename: Patrizia
authors.initials: P
authors.lastname: Cardelli
authors.forename: Mattia Falchetto
authors.initials: MF
authors.lastname: Osti
authors.forename: Vitaliana
authors.initials: V
authors.lastname: De Sanctis
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Minniti
authors.forename: Riccardo
authors.initials: R
authors.lastname: Maurizi Enrici
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D024201:Bystander Effect / Q000528:radiation effects*; D002454:Cell Differentiation / Q000528:radiation effects*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D011471:Prostatic Neoplasms / Q000473:pathology*
chemical_list: D016207:Cytokines
keywords: Bystander effect; adenocarcinoma; prostate