title: Frequent detection and immunophenotyping of prostate-derived cell clusters in the peripheral blood of prostate cancer patients.
abstract: BACKGROUND
  Recent scientific studies have failed to determine parameters for the assessment of prostate cancer aggressiveness. The present study deals with the detection of blood-borne cancer cells based on polymerase chain reaction (PCR) and cell enrichment methods. The contradictory results reported in the literature have called into question the clinical usefulness of this diagnostic method in the preoperative staging of clinically localized prostate cancer.
  
  
  METHODS
  We established a combined method of density gradient centrifugation and immunomagnetic separation using epithelium-specific antibodies, i.e. cytokeratins, to isolate prostate-derived circulating cells from the peripheral blood of patients with prostate cancer. Isolated cells were characterized by DNA staining and immunocytochemistry using antibodies for the detection of prostate-specific antigen (PSA), proliferation-associated proteins (MIB-1, H1 and H3) and apoptosis-associated proteins (M30, c-FasR).
  
  
  RESULTS
  We applied these methods to 68 prostate cancer patients and were able to isolate cell clusters in 98%. Immunophenotypic and morphological characterization of PSA-positive prostate-derived cell clusters found in the peripheral blood of prostate cancer patients showed two main populations: 1) in 35% of the investigated prostate cancer patients we detected rounded cell aggregates of probable cancer cells expressing proliferation-associated proteins and lacking apoptosis-associated protein expression; 2) in all cases there was a high frequency of circulating dysmorphic cell clusters positive for apoptosis-associated protein expression.
  
  
  CONCLUSIONS
  Our results demonstrate the existence of at least two different types of blood-borne prostate-derived circulating cell clusters. Of these, only the less frequent, round, small cell clusters harbor features that are probably necessary for the cells to survive for metastatic spread.
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, University of Münster, Münster, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schmidt
authors.forename: G
authors.initials: G
authors.lastname: De Angelis
authors.forename: O
authors.initials: O
authors.lastname: Bettendorf
authors.forename: E
authors.initials: E
authors.lastname: Eltze
authors.forename: A
authors.initials: A
authors.lastname: Semjonow
authors.forename: G
authors.initials: G
authors.lastname: Knichwitz
authors.forename: B
authors.initials: B
authors.lastname: Brandt
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D001773:Blood Cells / Q000166:cytology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping / Q000379:methods*; D007633:Keratins / Q000378:metabolism; D008297:Male; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D016133:Polymerase Chain Reaction; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D007633:Keratins; D004247:DNA; D017430:Prostate-Specific Antigen