"Decoy" of androgen-responsive element induces apoptosis in LNCaP cells

BACKGROUND. In an androgen-dependent manner, the androgen receptor (AR) bin ds to the androgen-responsive element (ARE) in the regulatory region of tar get genes. We hypothesize that an "ARE decoy," a double-stranded oligonucle otide containing the same DNA sequence as ARE, can inhibit prostatic prolif eration by competitive inhibition of AR transcriptional activity. METHODS. We synthesized a 23-mer ARE decoy based on the deduced ARE sequenc e at the promoter region of the human prostate-specific antigen (PSA) gene. The nuclear extract was prepared from LNCaP cells, and DNA-protein interac tions were examined by gel shift assay. Then the antiandrogen effect of the ARE decoy was studied in LNCaP cells transfected with the ARE decoy by lip ofection. After 24-hr incubation with 10(-9) M dihydrotestosterone (DHT), i nduction of apoptosis was examined by DNA fragmentation. RESULTS. The gel shift assay demonstrated specific binding of the ARE decoy to the LNCaP nuclear protein which is most likely AR. The transfection exp eriment showed DNA fragmentation in the ARE decoy-transfected cells despite the presence of DHT, though not in the cells transfected with the control decoy. CONCLUSIONS. The ARE decoy had an antiandrogen effect and induced apoptosis in LNCaP cells. This ARE decoy may become a potential therapeutic tool for prostate cancers when combined with a highly efficient transfection method . (C) 1999 Wiley-Liss, Inc.