CD44+ cancer stem-like cells in EBV-associated nasopharyngeal carcinoma

PLoS One. 2012;7(12):e52426. doi: 10.1371/journal.pone.0052426. Epub 2012 Dec 21.

Abstract

Nasopharyngeal carcinoma (NPC) is a unique EBV-associated epithelial malignancy, showing highly invasive and metastatic phenotype. Despite increasing evidence demonstrating the critical role of cancer stem-like cells (CSCs) in the maintenance and progression of tumors in a variety of malignancies, the existence and properties of CSC in EBV-associated NPC are largely unknown. Our study aims to elucidate the presence and role of CSCs in the pathogenesis of this malignant disease. Sphere-forming cells were isolated from an EBV-positive NPC cell line C666-1 and its tumor-initiating properties were confirmed by in vitro and in vivo assays. In these spheroids, up-regulation of multiple stem cell markers were found. By flow cytometry, we demonstrated that both CD44 and SOX2 were overexpressed in a majority of sphere-forming C666-1 cells. The CD44+SOX2+ cells was detected in a minor population in EBV-positive xenografts and primary tumors and considered as potential CSC in NPC. Notably, the isolated CD44+ NPC cells were resistant to chemotherapeutic agents and with higher spheroid formation efficiency, showing CSC properties. On the other hand, microarray analysis has revealed a number of differentially expressed genes involved in transcription regulation (e.g. FOXN4, GLI1), immune response (CCR7, IL8) and transmembrane transport (e.g. ABCC3, ABCC11) in the spheroids. Among these genes, increased expression of CCR7 in CD44+ CSCs was confirmed in NPC xenografts and primary tumors. Importantly, blocking of CCR7 abolished the sphere-forming ability of C666-1 in vitro. Expression of CCR7 was associated with recurrent disease and distant metastasis. The current study defined the specific properties of a CSC subpopulation in EBV-associated NPC. Our findings provided new insights into developing effective therapies targeting on CSCs, thereby potentiating treatment efficacy for NPC patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers, Tumor / metabolism
  • Carcinoma
  • Cell Membrane / metabolism
  • Cell Proliferation
  • Cell Transformation, Neoplastic / pathology
  • Clone Cells
  • Drug Resistance, Neoplasm
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Herpesvirus 4, Human / physiology*
  • Humans
  • Hyaluronan Receptors / metabolism*
  • Immunohistochemistry
  • Male
  • Mice
  • Mice, Nude
  • Middle Aged
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / genetics
  • Nasopharyngeal Neoplasms / pathology*
  • Nasopharyngeal Neoplasms / virology*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology*
  • Neutralization Tests
  • Receptors, CCR7 / metabolism
  • SOXB1 Transcription Factors / metabolism
  • Spheroids, Cellular / metabolism
  • Spheroids, Cellular / pathology
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays

Substances

  • Biomarkers, Tumor
  • CCR7 protein, human
  • Hyaluronan Receptors
  • Receptors, CCR7
  • SOXB1 Transcription Factors

Grant support

The study was supported by the Research Grants Council of Hong Kong (GRF: Grant No. 470321, 471610, 471211, 471709; GRF: Grant No. CUHK8/CRF/11R; AoE/M-06/08) and Research Grant Council (GRF776608M; GRF777809M). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.