Objective  To observe the effect on the proliferation of HepG2 cell by inhibiting the expression of BC047440 gene.   Methods  Small interferin

g RNAs for BC047440 gene were designed using Ambion software and synthesized. The recombinant plasmid pGenSil-1-BC047440-siRNA was constructed with the smRNAs and pGenSil-1. The vacant vector pGenSil-1 and pGenSil-1-BC047440-siRNA vector were transfected into HepG2 cells by Lipofectamine

TM

2000 and the positive clones were screened by G418

then identified by detecting green fluorescence. BC047440 mRNA expression was detected by realtime PCR. The cell proliferation rate was analysed by CCK-. The cell colony formation rate was measured by plate colony formation assay. The proliferaion-elated genes such as c-yc

bcl-

cyclin D

1

were detected by real-ime PCR.   Results  We obtained stable transfectants. Endogenous BC047440 expression could be efficiently down-egulated by transfection of siRNA BC047440 gene in cultured HepG2 cell

and the cell proliferation rate of HepG2 transfected with pGenSil-1-BC047440-siRNA vector  (PP

2

) was significantly inhibited as compared to that in untreated parental HepG2 cells (PP

0

) and in HepG2 transfected with vacant vector pGenSil-1 (PP

1

). The cell colony formation rate was statistically decreased in siRNA

which was respectively (8.42±0.82)% in PP

2

(39.31±5.39)%  in PP

1

and (40.96±3.21)% in PP

0

(P0.01). The expressions of c-myc gene were down-regulated in PP

2

as compared to those in PP

0

and PP

1

and the expression levels of c-myc gene in PP

2

was about 12/25 of that in PP

0

. There was no significant changes in other proliferation-related genes.   Conclusion  BC047440 siRNA could inhibit the cell proliferation of HepG2 cell and be used as a novel method to inhibit the proliferation of hepatoma carcinoma cell. Our study reveals the relationship between BC047440 and c-myc gene.