OBJECTIVETo investigate the inhibitory effects of siRNA targeting BCSG1 gene expression in tumor transplants of human breast cancer cell line in nude mice.

METHODSFour-pairs of small interfering RNA sequences of BCSG1 were chemically synthesized and inserted into the plasmid expression vectors, and were then transfected into human breast carcinoma cell line MCF7 by liposome method. Plasmid vector with unrelated sequence was used as the vector control. Cells transfected with 4 siRNA sequences, control vector and naive FCF7 cells were transplanted into the nude mice. The tumor inhibition was analysised. Immunohistochemical SP method and semi-quantitative RT-PCR were adopted to detect the BCSG1 mRNA and protein expression, respectively. Breast tissue samples of human infiltrating ductal carcinoma, ductal hyperplasia and fibroadenoma were also used as the controls.

RESULTSThe inhibition rates of tumor growth in four BCSG1-siRNA transfected groups were remarkably higher than those of the vector control group and naive MCF7 cells (P<0.01). Compared with that of the vector control and naïve MCF7 cell group, there was a significant decrease of BCSG-1 protein expression in the four experimental groups by immuno-histochemistry staining (P<0.01). In addition, BCSG1 mRNA expression in the four groups transfected with BCSG1-siRNA were significantly less than that of the control vector group, naive MCF7 cell control group and human breast IDC (P<0.01).

CONCLUSIONBCSG1-siRNA down-regulates the expression of BCSG1 and inhibits effectively growth of the transplaned human breast cancer cell line in nude mice.