Objective:To clone the promoter of human telomerase reverse transcriptase (hTERT)and investigate its selective effect on breast cancer cell

and to observe changes of breast cancer resistance protein(BCRP) mRNA

its protein expression and changes of drug resistance to doxorubicin with RNAi technology used in cell (MCF-7/ADR). Methods:Plasmids (pGenesil-CMV-shRNA

pGenesil-hTERT-shRNA)were recombined and transfected into telomerase-negative and-positive cells

hTERT promoter targeting was detected.RT-PCR

and Western-blot were applied to detect RNA and protein of different groups of cells. MTT was applied to analyze drug sensitivity. Results:Highly visible fluorescent was seen in telomerase-positive cells

which was stronger than that of telom-erase-negative cells.The results of RT-PCR

and Western-blot showed that the mRNA and protein expression of BCRP were inhibited ; MTT results showed that the drug sensitivity to doxorubicin was significantly increased

which was of significant difference as compared with the control group ( P<0.05 ) . Conclusion : hTERT promoter can targeting silence BCRP gene combined with RNAi technology and drug resistance to doxorubicin is reversed

which lays a solid experimental basis for the further development of tumor specific therapy in gene silencing.