title: Enrichment of human prostate cancer cells with tumor initiating properties in mouse and zebrafish xenografts by differential adhesion.
abstract: BACKGROUND
  Prostate tumor-initiating cells (TICs) have intrinsic resistance to current therapies. TICs are commonly isolated by cell sorting or dye exclusion, however, isolating TICs from limited primary prostate cancer (PCa) tissues is inherently inefficient. We adapted the collagen adherence feature to develop a combined immunophenotypic and time-of-adherence assay to identify human prostate TICs.
  
  
  METHODS
  PCa cells from multiple cell lines and primary tissues were allowed to adhere to several matrix molecules, and fractions of adherent cells were examined for their TIC properties.
  
  
  RESULTS
  Collagen I rapidly-adherent PCa cells have significantly higher clonogenic, migration, and invasion abilities, and initiated more tumor xenografts in mice when compared to slowly-adherent and no-adherent cells. To determine the relative frequency of TICs among PCa cell lines and primary PCa cells, we utilized zebrafish xenografts to define the tumor initiation potential of serial dilutions of rapidly-adherent α2β1(hi) /CD44(hi) cells compared to non-adherent cells with α2β1(low) /CD44(low) phenotype. Tumor initiation from rapidly-adherent α2β1(hi) /CD44(hi) TICs harboring the TMPRSS2:ERG fusion generated xenografts comprising of PCa cells expressing Erg, AMACR, and PSA. Moreover, PCa-cell dissemination was consistently observed in the immune-permissive zebrafish microenvironment from as-few-as 3 rapidly-adherent α2β1(hi) /CD44(hi) cells. In zebrafish xenografts, self-renewing prostate TICs comprise 0.02-0.9% of PC3 cells, 0.3-1.3% of DU145 cells, and 0.22-14.3% of primary prostate adenocarcinomas.
  
  
  CONCLUSIONS
  Zebrafish PCa xenografts were used to determine that the frequency of prostate TICs varies among PCa cell lines and primary PCa tissues. These data support a paradigm of utilizing zebrafish xenografts to evaluate novel therapies targeting TICs in prostate cancer.
authors.affiliation: Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.
authors.forename: Nitu
authors.initials: N
authors.lastname: Bansal
authors.forename: Stephani
authors.initials: S
authors.lastname: Davis
authors.forename: Irina
authors.initials: I
authors.lastname: Tereshchenko
authors.forename: Tulin
authors.initials: T
authors.lastname: Budak-Alpdogan
authors.forename: Hua
authors.initials: H
authors.lastname: Zhong
authors.forename: Mark N
authors.initials: MN
authors.lastname: Stein
authors.forename: Isaac Yi
authors.initials: IY
authors.lastname: Kim
authors.forename: Robert S
authors.initials: RS
authors.lastname: Dipaola
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Bertino
authors.forename: Hatem E
authors.initials: HE
authors.lastname: Sabaawy
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D024042:Collagen Type I / Q000378:metabolism; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D019998:Racemases and Epimerases / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D000071230:Transcriptional Regulator ERG; D023041:Xenograft Model Antitumor Assays / Q000379:methods*; D015027:Zebrafish
chemical_list: D024042:Collagen Type I; C072312:ERG protein, human; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D017430:Prostate-Specific Antigen; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase
keywords: prostate cancer stem cells; tumor-initiating cells; zebrafish