Abstract:Objective
To discuss the effect on cell apoptosis and Bax/Bcl2 gene expression of nude mice model with implanted human breast cancer cells by applying RNAi technique to silence signal transducers and activators of transcription 3 (STAT3)gene.
Methods MCF7 breast cancer cells were implanted under the skin of female nude mice. After the tumors grew to a definite size,the mice were randomly divided into three groups:saline control group(A), empty plasmid group(B), the experimental group(C). The tumors were respectively injected with saline, empty plasmid with psilencer1.0U6, and recombined plasmid with psilencer1.0U6stat3siRNA . When the growth of group A animals reached the sufficient size,all of the animals were killed, the tumors were taken out, their size and weight were measured,immunohistochemical(IHC) analysis was done, and protein expression of STAT3, Bax and Bcl2 gene in tumors were examined by Western blot.
Results The size and weight of tumors in group C were significantly lower than group A and group B. (P<0.01). Immunohistochemical analysis and microscopic examination showed that there was a large area of cytoclasis and signs of cell apoptosis in the center of tumors of group C, and the STAT3 Immunohistochemistry result of the center was negative but that of the border area was positive; there were no such phenomena in group A and group B. The results of Western blot analysis showed that protein expressions of STAT3 gene in group C were significantly lower than those in group A and group B (P<0.01)， but there were no significant differences between group A and group B（P>0.05）, and protein expressions ofBax gene in tumor of group C were significantly higher than those in group A and group B (P<0.05)，but there were no significant differences between group A and group B （P>0.05）.The protein expressions of Bcl2 gene in all groups showed no significant differences (P>0.05).
Conclusions Silencing STAT3 gene can decrease STAT3 gene expressions , increase Bax gene expressions , induce cell apoptosis and suppress the tumor growth in the human breast carcinoma model by the RNAi technology .