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

• Published in: Ai zheng 2013-12, Vol.32 (12), p.653-660
• Main Authors: Mo, Lian-Jie, Ye, Hong-Xing, Mao, Ying, Yao, Yu, Zhang, Jian-Min
• Format: Article
• Language: English
• Subjects: 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; Original; Peptides - metabolism; SOXB1 Transcription Factors - metabolism; U251细胞; V-Set Domain-Containing T-Cell Activation Inhibitor 1 - metabolism; 外周血单核细胞; 无血清培养基; 条件培养基; 碱性成纤维细胞生长因子; 肿瘤干细胞; 脑胶质瘤; 诱导
• ISSN: 1000-467X; 1944-446X
• DOI: 10.5732/cjc.012.10228

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 BT-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 BT-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.