Expression of CD133 in in vitro cultured glioma cells

Objective To discuss the CD133 phenotype correlating with glioma stem cells.Methods The expression of CD133 in glioma stem cell lines which were cultured in stem cell permissive serumfree medium was compared with that in conventional adherent glioma cell lines which were established in serum-containing medium.Reverse transcription-polymerase chain reaction (RT-PCR) and real-time quantitative PCR were performed to study the expression level of CD133 mRNA.Flow cytometry and immunofluorescent staining were done to study the protein expression.Confocal microscopy was adopted to study the subcellular localization of CD133 protein.Results CD133 mRNA and protein were distributed both in glioma stem cells and conventional adherent glioma cell lines.The glycosylated CD133-AC133 detected by AC133 antibody was only found in glioma stem cells cultured in serum-free medium and located on the cell membrane,and the proportion of positive cells was 31.8％-99.9％.The CD133 protein in the AC133 negative glioma stem cells and conventional adherent glioma cell lines was found intracellularly and located in the endoplasmic reticulum and/or Golgi apparatus,and the proportion of positive cells was 22.2％-88.6％.Conclusion Neither CD133 mRNA nor intracellular CD133 protein but AC133 phenotype on the cell membrane is closely correlated with glioma stem cells,but a group of AC133 negative glioma stem cells can also exist in serum-free medium. Key words: CD133; AC133; Glioma; Brain tumor stem cell