OBJECTIVETo investigate the inhibitory effect on MTA1 gene by MTA1 short hairpin RNA (shRNA), downstream regulation of expression of ERa and invasion of human breast cancer cells.

METHODSRecombinant plasmid pGenesil-1/MTA1 was constructed and transfected into human breast cancer cell lines MDA-MB-231 and MCF-7. Fluorescence microscopy was used to evaluate the efficacy of transfection. The transcription expression of MTA1 and MMP-9 gene were determined by reverse transcription-polymerase chain reaction (RT-PCR), the protein expression of ERalpha and MMP-9 were determined by immunohistochemical and western blot. The invasion ability was evaluated by Boyden chamber invasive assay.

RESULTSRecombinant plasmid pGenesil-1/MTA1 was constructed and transfected into MDA-MB-231 (82.5%) and MCF-7 (78.2%) successfully. After the transfection, MTA1 mRNA was suppressed in both cell lines (80.2% and 58.7%). The expression of ERalpha protein became positive in transfected MDA-MB-231 cell, and the expression of MMP-9 mRNA were down-regulated. The invasion ability was decreased (27.2% +/- 2.1)% compared with (76.3% +/- 2.4%), (P < 0.05). In contrast, transfected MCF-7 cells failed to show significant difference in the expression of ERalpha and MMP-9, without change of the invasion ability (P > 0.05).

CONCLUSIONSRNA interference can effectively suppress the expression of MTA1 in human breast cancer cells. An induction of ERalpha protein and suppression of MMP-9 may be related to the decrease of tumor cell invasive ability. RNA interference involving MTA1 gene may provide an effective anti-cancer gene therapy.