MRTF- A Decreases the Anti-Tumor Effect of Tamoxifen on MCF-7 Human Breast Cancer Cells

Myocardin-related transcription factors A (MRTF-A) is a myocardin-related transcription factor that has been found strongly activated CarG box - containing genes through its direct binding to serum response factor (SRF). In the present study, the MRTF-A expression vector was constructed. The MTT assay showed that transfection of MRTF-A could significantly decrease the anti-tumor effect of tamoxifen on MCF-7 human breast cancer cells. The bioinformatics analysis found that the CarG element existed in the promoter region of COMT gene of many familiar vertebrates, including of human, rhesus macaque, chimpanzee, etc. The results of RT-PCR assay further showed that MRTF-A could enhance the transcription level of COMT. These results are the first to indicate that COMT might be a target gene which could be regulated by MRTF-A/SRF, and such transactivation event might be involved in the process of tamoxifen resistance.