title: Side population rather than CD133(+) cells distinguishes enriched tumorigenicity in hTERT-immortalized primary prostate cancer cells.
abstract: BACKGROUND
  Subpopulations of cancer cells with the capacity of generating solid tumors have been characterized. In various cancer types, including prostate cancer cells, a side population (SP) and CD133-expressing cells have been proposed as containing a population cancer cells with stem-like ability. Therefore the aim of this work was to determine, in prostate cancer cell lines, the frequency and tumorigenic potential of SP and CD133+ cells.
  
  
  RESULTS
  In vitro 2D colony-forming assay and sphere-forming assay, Flow cytometry analysis and magnetic cell sorting were utilized to sort CD133+, CD133- and Side population (SP) cells. Our findings indicate that CD44 and integrin α-6 are uniformly expressed in the hTERT cell lines; however, CD133 is expressed only in a small population (< 0.1%). FACS-sorted CD133+ and CD133- cells exhibited similar tumorigenicity in vitro and in vivo. Additionally, for the hTERT cells, SP rather than CD133 expression showed an 8-fold enhanced tumorigenic potential. The data suggest that SP cells, rather than those with CD133 marker, contain the rare population of CSC capable of producing prostate tumors.
  
  
  CONCLUSIONS
  Collectively, our data suggest that although CD133 is expressed only in a small population of hTERT-immortalized prostate cancer cells, it is not likely to be associated with stem cells, as CD133- and CD133+ cells exhibited similar tumorigenicity. However, SP isolated cells, appear to be enriched with tumorigenic stem-like cells capable of generating palpable tumors.
authors.affiliation: Department of Biology and Center for Cancer Research, Tuskegee University, Tuskegee, AL 36088, USA.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Zhou
authors.forename: Honghe
authors.initials: H
authors.lastname: Wang
authors.forename: Virginetta
authors.initials: V
authors.lastname: Cannon
authors.forename: Karen Marie
authors.initials: KM
authors.lastname: Wolcott
authors.forename: Hongbin
authors.initials: H
authors.lastname: Song
authors.forename: Clayton
authors.initials: C
authors.lastname: Yates
mesh_terms: D000071916:AC133 Antigen; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002449:Cell Aggregation; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002469:Cell Separation; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D011471:Prostatic Neoplasms; D058985:Side-Population Cells / Q000378:metabolism* / Q000473:pathology; D019098:Telomerase / Q000378:metabolism*
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse; C509186:TERT protein, human; D019098:Telomerase