BACKGROUND: Bmi-1 gene determines the proliferative capacity of normal and 
leukemia stem cells. Expression of Bmi-1 has been found in all types of myeloid 
leukemia cells in both humans and mice. This study aimed at assessing the effect 
of antisense Bmi-1 expression on K562 cells proliferation and p16 protein (p16) 
expression.
METHODS: A transcriptional repressor, Bmi-1 cDNA was cloned by reverse 
transcriptase polymerase chain reaction (RT-PCR) of its mRNA from K562 cells. A 
plasmid expressing antisense Bmi-1 mRNA was then constructed by reverse design 
of PCR primers and cloned to the plasmid pLNCX2; G418 was added to the medium 
after the plasmid was successfully introduced in K562 cells by 
lipofectin-mediated DNA transfection. The effects of the antisense expression on 
the proliferation of K562 cells were analyzed by using microculture tetrazolium 
and colony forming. Cell cycle was analyzed by using flow cytometry. The p16 
expression of K562 cells was observed by immunofluorescence histochemical stain.
RESULTS: K562 cells transfected with antisense Bmi-1 plasmid grew significantly 
slower than that of controls (the parental K562 and cells transfected with empty 
plasmid). The colony forming ability of antisense Bmi-1 plasmid transfected 
cells decreased significantly (P < 0.01) compared with controls. The p16 
expression of cells transfected with antisense Bmi-1 was upgraded more 
apparently than that of controls.
CONCLUSION: The antisense Bmi-1 gene can inhibit the growth of K562 cell and 
upgrade expression of p16 in K562 cells.