Detection and characterization of invasive circulating tumor cells derived from men with metastatic castration-resistant prostate cancer

Int J Cancer. 2014 May 15;134(10):2284-93. doi: 10.1002/ijc.28561. Epub 2014 Jan 2.


The Vitatex cell-adhesion matrix (CAM) platform allows for isolation of invasive circulating tumor cells (iCTCs). Here we sought to determine the utility of prostate-specific membrane antigen (PSMA) as a metastatic castration-resistant prostate cancer (mCRPC) iCTC biomarker, to identify solitary cells and clusters of iCTCs expressing either epithelial, mesenchymal, or stem cell markers, and to explore the feasibility of iCTC epigenomic analysis. CTCs were isolated and enumerated simultaneously using the Vitatex and CellSearch platforms in 23 men with mCRPC. CAM-avid iCTCs were identified as nucleated cells capable of CAM uptake, but without detectable expression of hematopoietic lineage (HL) markers including CD45. iCTCs were enumerated immunocytochemically (ICC) and by flow cytometry. Whole-genome methylation status was determined for iCTCs using the Illumina HumanMethylation27 BeadChip. Thirty-four samples were collected for iCTC analysis. A median of 27 (range 0-800) and 23 (range 2-390) iCTCs/mL were detected by ICC and flow, respectively. In a subset of 20 samples, a median of seven CTCs/mL (range 0-85) were detected by the CellSearch platform compared to 26 by the CAM platform. iCTC clusters were observed in 17% of samples. iCTCs expressing PSMA as well as markers of EMT and stemness were detectable. The iCTC methylation profile highly resembled mCRPC. More CTCs were recovered using the CAM platform than the CellSearch platform, and the CAM platform allowed for the detection of iCTC clusters, iCTCs expressing EMT and stem-cell markers, and characterization of the iCTC methylome. Correlation with clinical data in future studies may yield further insight into the functional significance of these findings.

Keywords: circulating tumor cells; epithelial to mesenchymal transition; prostate cancer.

MeSH terms

  • Antigens, Neoplasm / blood
  • Antigens, Surface / blood
  • Antineoplastic Agents / therapeutic use
  • Biomarkers, Tumor / blood
  • Biomarkers, Tumor / metabolism
  • Cell Adhesion Molecules / blood
  • Cell Count
  • Cell Line, Tumor
  • DNA Methylation
  • Docetaxel
  • Epithelial Cell Adhesion Molecule
  • Flow Cytometry
  • Glutamate Carboxypeptidase II / blood
  • Humans
  • Hyaluronan Receptors / metabolism
  • Immunohistochemistry
  • Leukocyte Common Antigens / metabolism
  • Male
  • Microscopy, Fluorescence
  • Neoplasm Metastasis
  • Neoplastic Cells, Circulating / drug effects
  • Neoplastic Cells, Circulating / metabolism
  • Neoplastic Cells, Circulating / pathology*
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms, Castration-Resistant / blood
  • Prostatic Neoplasms, Castration-Resistant / drug therapy
  • Prostatic Neoplasms, Castration-Resistant / pathology*
  • Taxoids / therapeutic use
  • Vimentin / metabolism


  • Antigens, Neoplasm
  • Antigens, Surface
  • Antineoplastic Agents
  • Biomarkers, Tumor
  • Cell Adhesion Molecules
  • Epithelial Cell Adhesion Molecule
  • Hyaluronan Receptors
  • Taxoids
  • Vimentin
  • Docetaxel
  • Leukocyte Common Antigens
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II
  • Prostate-Specific Antigen