Human pancreatic cancer contains a side population expressing cancer stem cell-associated and prognostic genes

PLoS One. 2013 Sep 17;8(9):e73968. doi: 10.1371/journal.pone.0073968. eCollection 2013.


In many types of cancers, a side population (SP) has been identified based on high efflux capacity, thereby enriching for chemoresistant cells as well as for candidate cancer stem cells (CSC). Here, we explored whether human pancreatic ductal adenocarcinoma (PDAC) contains a SP, and whether its gene expression profile is associated with chemoresistance, CSC and prognosis. After dispersion into single cells and incubation with Hoechst dye, we analyzed human PDAC resections specimens using flow cytometry (FACS). We identified a SP and main population (MP) in all human PDAC resection specimens (n = 52) analyzed, but detected immune (CD45(+)) and endothelial (CD31(+)) cells in this fraction together with tumor cells. The SP and MP cells, or more purified fractions depleted from CD31(+)/CD45(+) cells (pSP and pMP), were sorted by FACS and subjected to whole-genome expression analysis. This revealed upregulation of genes associated with therapy resistance and of markers identified before in putative pancreatic CSC. pSP gene signatures of 32 or 10 up- or downregulated genes were developed and tested for discriminatory competence between pSP and pMP in different sets of PDAC samples. The prognostic value of the pSP genes was validated in a large independent series of PDAC patients (n = 78) using nCounter analysis of expression (in tumor versus surrounding pancreatic tissue) and Cox regression for disease-free and overall survival. Of these genes, expression levels of ABCB1 and CXCR4 were correlated with worse patient survival. Thus, our study for the first time demonstrates that human PDAC contains a SP. This tumor subpopulation may represent a valuable therapeutic target given its chemoresistance- and CSC-associated gene expression characteristics with potential prognostic value.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma, Pancreatic Ductal / genetics*
  • Carcinoma, Pancreatic Ductal / metabolism
  • Carcinoma, Pancreatic Ductal / mortality
  • Case-Control Studies
  • Female
  • Gene Expression Profiling
  • Humans
  • Immunophenotyping
  • Male
  • Middle Aged
  • Neoplastic Stem Cells / metabolism*
  • Pancreatic Neoplasms / genetics*
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / mortality
  • Prognosis
  • Receptors, CXCR4 / genetics
  • Receptors, CXCR4 / metabolism
  • Side-Population Cells / metabolism*


  • ABCB1 protein, human
  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Receptors, CXCR4

Grant support

The study is supported by the Fund for Scientific Research Flanders (FWO ASP-08-00379; 3M080177). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.