Abstract: Objective To evaluate the relationship between liver cell type A receptor (EphA) expression and androgen receptor (AR) signaling in androgen- dependent prostate cancer cells. Methods RT- PCR and Western blot assay were used to determine mRNA and protein levels of EphA3 and AR in prostate cancer LNCaP and 22Rv1 cells, respectively. The variations of EphA3, AR and prostate specific antigen (PSA) expressions were also measured in these cells after dihydrotestosterone (DHT) treatment for 48 h. The constructed EphA3-Luc (-789-+146) luciferase reporter plasmid was co-transfected with pcDNA3.1（+） -AR or siAR in 22Rv1 cells to analyze the effects of different AR expression levels on EphA3 transcription activity. Results The expression pattern of EphA3 was similar to AR, showing a lower level in prostate stromal cell line WPMY-1 and a higher level in prostate cancer cell lines LNCaP and 22Rv1. When stimulated with 10 nmol/L DHT, the expression levels of AR, PSA and EphA3 were significantly increased in 22Rv1 cells, and the protein levels of these genes were also increased in LNCaP cells. Moreover, AR expression levels markedly influenced the activity of EphA3 promoter. Conclusion AR up-regulates EphA3 expression by increasing the activity of EphA3 promoter.

Key words: EphA3, dihydrotestosterone, receptors, androgen, prostatic neoplasms, regulation