Objective   To investigate the transcriptional regulatory effects of Bmi-1

a member of polycomb group

on stemness-associated genes in cancer and embryonic stem cells (CSCs and ESCs).    Methods   Eukaryotic expression vectors pCI-GFP-mbmi and pCI-GFP-hbmi were constructed and then transiently transfected into mouse ESCs

CCE cells and human glioma cell line

U87 cells respectively. Semi-quantitative RT-PCR was used to detect mRNA expressions of stemness factors

such as Oct-4

Nanog

c-Myc

Klf4 and Sox2 in CCE cells

and expressions of Bmi-1

Oct-4

Nanog

c-Myc

CD133 and Nestin in U87 cells. Clone formation assay was used to elucidate the potential to form self-renewal clones of CCE cells.    Results   Overexpression of Bmi-1 in CCE cells up-regulated the expression of Nanog. The expressions of other stemness factors such as Oct-4

Sox2 and Klf4 had no significant change. U87 cells transiently transfected with Bmi-1 promoted the expression of Oct-4 and Nestin. The expression level of c-Myc was reduced in the 2 kinds of cells. Overexpression of Bmi-1 promoted the formation of self-renewal clones in CCE cells.    Conclusion   Bmi-1 is involved in the transcriptional regulation of stemness-associated genes in CSCs and ESCs.