Immunobiological characterization of cancer stem cells isolated from glioblastoma patients.
OBJECTIVE
Cancer stem cells (CSC) have been isolated from human tumors, including glioblastoma multiforme (GBM). The aims of this study were the immunobiological characterization of GBM CSCs and the assessment of whether these cells represent suitable targets for immunotherapy.


METHODS
GBM CSC lines and their fetal bovine serum (FBS)-cultured non-CSC pair lines were generated and examined by flow cytometry for expression of known tumor antigens, MHC-I and MHC-II molecules, antigen-processing machinery components, and NKG2D ligands. In addition, immunogenicity and immunosuppression of such cell lines for autologous or allogeneic T lymphocytes were tested by cytokine secretion (ELISPOT) or proliferation (carboxyfluorescein diacetate succinimidyl ester) assays, respectively.


RESULTS
Both GBM CSC and FBS lines were weakly positive and negative for MHC-I, MHC-II, and NKG2D ligand molecules, respectively. Antigen-processing machinery molecules were also defective in both cell types. Upregulation of most molecules was induced by IFNs or 5-Aza deoxycytidine, although more efficiently in FBS than in CSCs. Patient T-cell responses, mediated by both TH1 and the TH2 subsets, against autologous CSC could be induced in vitro. In addition, CSC but not their paired FBS tumor lines inhibited T-cell proliferation of healthy donors. Notably, a differential gene signature that was confirmed at the protein levels for some immunologic-related molecules was also found between CSC and FBS lines.


CONCLUSIONS
These results indicate lower immunogenicity and higher suppressive activity of GBM CSC compared with FBS lines. The immunogenicity, however, could be rescued by immune modulation leading to anti-GBM T cell-mediated immune response.
Di Tomaso
Tiziano
T
Department of Pathology, San Raffaele Foundation Scientific Institute, Milan, Italy.
Mazzoleni
Stefania
S
Wang
Ena
E
Sovena
Gloria
G
Clavenna
Daniela
D
Franzin
Alberto
A
Mortini
Pietro
P
Ferrone
Soldano
S
Doglioni
Claudio
C
Marincola
Francesco M
FM
Galli
Rossella
R
Parmiani
Giorgio
G
Maccalli
Cristina
C
D017951:Antigen Presentation; D001932:Brain Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D020869:Gene Expression Profiling; D005909:Glioblastoma / Q000473:pathology*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D014411:Neoplastic Stem Cells / Q000473:pathology*; D013601:T-Lymphocytes / Q000276:immunology
D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II