The TRPS1 transcription factor: androgenic regulation in prostate cancer and high expression in breast cancer

TRPS1 mRNA is more highly expressed in androgen-dependent lymph node carcinoma of prostate-fast growing colony (LNCaP-FGC) compared with androgen-independent lymph node carcinoma of prostate-lymph node original (LNCaP-LNO) prostate cancer cell lines. Furthermore, TRPS1 mRNA expression is down-regulated by androgens in LNCaP-FGC cells, a process mediated by the androgen receptor (AR). Here, we present TRPS1 protein expression in human prostate cancer material derived from a panel of six androgen-dependent and eight androgen-independent human prostate cancer xenografts. TRPS1 protein is expressed in all androgen-dependent xenografts, which also express AR and prostate-specific antigen (PSA). Androgen withdrawal by castration resulted in an increase in TRPS1 protein in two androgen-dependent xenografts, indicating relieved repression by action of AR. TRPS1 protein is expressed in four androgen-independent xenografts and is low or absent in the other four androgen-independent xenografts. Androgen withdrawal by castration demonstrates that TRPS1 protein levels remain the same in 1 androgen-independent xenograft, most likely due to the lack of AR expression. These data show that TRPS1 protein expression is regulated by androgens via the AR in human prostate cancer xenografts. Analysis of TRPS1 mRNA expression in normal and tumour tissue of the prostate and 18 other human tissues, showed that TRPS1 had the highest mRNA expression levels in normal and tumour tissues of breast. In addition, high TRPS1 mRNA and protein expression levels were observed in four out of five human breast cancer cell lines. In conclusion, TRPS1 protein expression is down-regulated by androgens in human prostate cancer, and analysis of TRPS1 mRNA expression levels in several human tissues showed that the highest levels were observed in normal and tumour breast tissue.