NKX-3.1 interacts with prostate-derived Ets factor and regulates the activity of the PSA promoter.

The NKX-3.1 homeobox gene maps to human chromosome 8p21, a region that undergoes frequent loss of heterozygosity in prostate tumors. Loss of Nkx-3.1 function in mice leads to epithelial overgrowth. To further elucidate the molecular basis of NKX-3.1 function, a genetic screen for proteins that interact with NKX-3.1 was performed. Prostate-derived Ets factor (PDEF) was identified as a potential partner of NKX-3.1. Coimmunoprecipitation analyses demonstrated that NKX-3.1 and PDEF are physically associated in prostate epithelial cells. Cotransfection analyses demonstrated that NKX-3.1 can abolish the transcriptional activation function of PDEF on the prostate-specific antigen (PSA) promoter. These data identify PSA as a target gene for NKX-3.1 and provide new insights into the function of this candidate tumor suppressor.