OBJECTIVETo construct a RNA interference expression vector targeting human telomerase reverse transcriptase gene (hTERT) gene and investigate its effects on telomerase activity and proliferation in breast cancer cells in vitro.

METHODSThe shRNA sequences targeting hTERT gene were designed and recombined into pSuper-retro-puro vector. The breast cancer cell lines MCF-7 and MDA-MB231 were transfected with the recombined vector, and the telomerase activity of the cells was tested by telomerase repeat sequence amplification-enzyme linked immunosorbent assay (TRAP-ELISA). The proliferation of the transfected cells was assessed using MTT and soft-agar clone formation assays.

RESULTSThe recombinant plasmids pSuper-retro-puro-TERT RNAi#1 and #2 were successfully constructed as confirmed by enzymatic digestion and DNA sequencing. The telomerase activity in the transfected breast cancer cells were down-regulated significantly as compared with that in negative control cells (Plt;0.005). The transfection resulted in significant inhibition of the proliferation of both MCF-7 and MDA-MB231 cells as detected by MTT assay (Plt;0.05) and soft agar clone formation assay (Plt;0.001).

CONCLUSIONTransfection with the recombinant plasmid containing the shRNA targeting hTERT gene can down-regulate telomerase activity and inhibit proliferation of breast cancer cells in vitro, suggesting the potential of gene therapy targeting telomerase in the treatment of breast cancer.