title: Single-cell analysis of circulating tumor cells identifies cumulative expression patterns of EMT-related genes in metastatic prostate cancer.
abstract: BACKGROUND
  Prostate tumors shed circulating tumor cells (CTCs) into the blood stream. Increased evidence shows that CTCs are often present in metastatic prostate cancer and can be alternative sources for disease profiling and prognostication. Here we postulate that CTCs expressing genes related to epithelial-mesenchymal transition (EMT) are strong predictors of metastatic prostate cancer.
  
  
  METHODS
  A microfiltration system was used to trap CTCs from peripheral blood based on size selection of large epithelial-like cells without CD45 leukocyte marker. These cells individually retrieved with a micromanipulator device were assessed for cell membrane physical properties using atomic force microscopy. Additionally, 38 CTCs from eight prostate cancer patients were used to determine expression profiles of 84 EMT-related and reference genes using a microfluidics-based PCR system.
  
  
  RESULTS
  Increased cell elasticity and membrane smoothness were found in CTCs compared to noncancerous cells, highlighting their potential invasiveness and mobility in the peripheral circulation. Despite heterogeneous expression patterns of individual CTCs, genes that promote mesenchymal transitioning into a more malignant state, including IGF1, IGF2, EGFR, FOXP3, and TGFB3, were commonly observed in these cells. An additional subset of EMT-related genes (e.g., PTPRN2, ALDH1, ESR2, and WNT5A) were expressed in CTCs of castration-resistant cancer, but less frequently in castration-sensitive cancer.
  
  
  CONCLUSIONS
  The study suggests that an incremental expression of EMT-related genes in CTCs is associated with metastatic castration-resistant cancer. Although CTCs represent a group of highly heterogeneous cells, their unique EMT-related gene signatures provide a new opportunity for personalized treatments with targeted inhibitors in advanced prostate cancer patients.
authors.affiliation: Department of Molecular Medicine, Cancer Therapy and Research Center, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
authors.forename: Chun-Liang
authors.initials: CL
authors.lastname: Chen
authors.forename: Devalingam
authors.initials: D
authors.lastname: Mahalingam
authors.forename: Pawel
authors.initials: P
authors.lastname: Osmulski
authors.forename: Rohit R
authors.initials: RR
authors.lastname: Jadhav
authors.forename: Chiou-Miin
authors.initials: CM
authors.lastname: Wang
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Leach
authors.forename: Tien-Cheng
authors.initials: TC
authors.lastname: Chang
authors.forename: Steven D
authors.initials: SD
authors.lastname: Weitman
authors.forename: Addanki Pratap
authors.initials: AP
authors.lastname: Kumar
authors.forename: Luzhe
authors.initials: L
authors.lastname: Sun
authors.forename: Maria E
authors.initials: ME
authors.lastname: Gaczynska
authors.forename: Ian M
authors.initials: IM
authors.lastname: Thompson
authors.forename: Tim Hui-Ming
authors.initials: TH
authors.lastname: Huang
mesh_terms: D045744:Cell Line, Tumor; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism / Q000473:pathology; D008297:Male; D046210:Microfluidic Analytical Techniques; D018625:Microscopy, Atomic Force; D009376:Neoplasms, Hormone-Dependent / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D009360:Neoplastic Cells, Circulating / Q000378:metabolism* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059010:Single-Cell Analysis / Q000379:methods
chemical_list: D004273:DNA, Neoplasm