MEIS1 functions as a potential AR negative regulator.

The androgen receptor (AR) plays critical roles in human prostate carcinoma progression and transformation. However, the activation of AR is regulated by co-regulators. MEIS1 protein, the homeodomain transcription factor, exhibited a decreased level in poor-prognosis prostate tumors. In this study, we investigated a potential interaction between MEIS1 and AR. We found that overexpression of MEIS1 inhibited the AR transcriptional activity and reduced the expression of AR target gene. A potential protein–protein interaction between AR and MEIS1 was identified by the immunoprecipitation and GST pull-down assays. Furthermore, MEIS1 modulated AR cytoplasm/nucleus translocation and the recruitment to androgen response element in prostate specific antigen ( PSA ) gene promoter sequences. In addition, MEIS1 promoted the recruitment of NCoR and SMRT in the presence of R1881. Finally, MEIS1 inhibited the proliferation and anchor-independent growth of LNCaP cells. Taken together, our data suggests that MEIS1 functions as a novel AR co-repressor. [ABSTRACT FROM AUTHOR]