B7-H4 expression is elevated in human U251 glioma stem-like cells and is inducible in monocytes cultured with U251 stem-like cell conditioned medium

Chin J Cancer. 2013 Dec;32(12):653-60. doi: 10.5732/cjc.012.10228. Epub 2013 Jan 18.

Abstract

Previous studies indicated that B7-H4, the youngest B7 family, negatively regulates T cell-mediated immunity and is significantly overexpressed in many human tumors. Tumor stem cells are purported to play a role in tumor renewal and resistance to radiation and chemotherapy. However, the link between B7-H4 and tumor stem cells is unclear. In this study, we investigated B7-H4 expression in the medium of human glioma U251 cell cultures. Immunofluorescence results showed that U251 cells cultured in serum-free medium (supplemented with 2% B27, 20 ng/mL epidermal growth factor, 20 ng/mL basic fibroblast growth factor) maintained stem-like cell characteristics, including expression of stem cell marker CD133 and the neural progenitor cell markers nestin and SOX2. In contrast, U251 cells cultured in serum-containing medium highly expressed differentiation marker glial fibrillary acidic protein. Flow cytometry analysis showed serum-free medium-cultured U251 cells expressed higher intracellular B7-H4 than serum-containing medium-cultured U251 cells (24%-35% vs. 8%-11%, P < 0.001). Immunofluorescence in purified monocytes from normal human peripheral blood mononuclear cells revealed moderate expression of B7-H4 after stimulation with conditioned medium from U251 cells cultured in serum-containing medium. Moreover, conditioned medium from U251 stem-like cells had a significant stimulation effect on B7-H4 expression compared with serum-containing conditioned medium (P < 0.01). Negative costimulatory molecule B7-H4 was preferentially expressed in U251 stem-like cells, and conditioned medium from these cells more effectively induced monocytes to express B7-H4 than conditioned medium from U251 cells cultured in the presence of serum. Our results show that U251 stem-like cells may play a more crucial role in tumor immunoloregulation with high expression of B7-H4.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AC133 Antigen
  • Antigens, CD / metabolism
  • Brain Neoplasms / metabolism*
  • Brain Neoplasms / pathology
  • Cell Line, Tumor
  • Cells, Cultured
  • Culture Media, Conditioned
  • Culture Media, Serum-Free
  • Gene Expression Regulation, Neoplastic
  • Glial Fibrillary Acidic Protein / metabolism
  • Glioma / metabolism*
  • Glioma / pathology
  • Glycoproteins / metabolism
  • Humans
  • Monocytes / cytology
  • Monocytes / metabolism*
  • Neoplastic Stem Cells / metabolism*
  • Neoplastic Stem Cells / pathology
  • Nestin / metabolism
  • Peptides / metabolism
  • SOXB1 Transcription Factors / metabolism
  • V-Set Domain-Containing T-Cell Activation Inhibitor 1 / metabolism*

Substances

  • AC133 Antigen
  • Antigens, CD
  • Culture Media, Conditioned
  • Culture Media, Serum-Free
  • Glial Fibrillary Acidic Protein
  • Glycoproteins
  • NES protein, human
  • Nestin
  • PROM1 protein, human
  • Peptides
  • SOX2 protein, human
  • SOXB1 Transcription Factors
  • V-Set Domain-Containing T-Cell Activation Inhibitor 1
  • VTCN1 protein, human