OBJECTIVETo reverse the multidrug resistant (MDR) phenotype of human breast carcinoma cells by small hairpin RNA (shRNA) technique targeting hypoxia-inducible factor (HIF)-1alpha gene.

METHODSSmall hairpin RNA (shRNA) eukaryotic expression vector targeting HIF-1alpha gene, named pSilencer-HIF, was constructed and transfected into MCF-7/ADR human breast cancer cells by liposome technique. Tumor cell livability (TCL) and Rhodamine 123 efflux assay were used to monitor the biological changes of the transfected cells. The mRNA and protein expression of HIF-1alpha and mdr-1 were investigated by RT-PCR and Western blot.

RESULTSThe successful construction of pSilencer-HIF plasmid was confirmed by DNA sequencing. HIF-1alpha mRNA and protein levels were significantly decreased in MCF-7/ADR cells after the transfection and there was a direct correlation between HIF-1alpha and mdr-1 expression. By comparing the cells transfected with control vector and the MCF-7/ADR cells transfected with pSilencer-HIF, a reduced TCL from 76% to 43%, and an increased Rhodamine 123 fluorescence intensity from 22.0% to 86.6% were observed.

CONCLUSIONSpSilencer-HIF-1alpha has been successfully constructed. The inhibition of HIF-1alpha expression through shRNA technique can significantly reverse the multidrug resistance phenotype of MCF-7/ADR cells.