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

Abstract

In an androgen-dependent manner, the androgen receptor (AR) binds to the androgen-responsive element (ARE) in the regulatory region of target genes. We hypothesize that an "ARE decoy, " a double-stranded oligonucleotide containing the same DNA sequence as ARE, can inhibit prostatic proliferation by competitive inhibition of AR transcriptional activity. We synthesized a 23-mer ARE decoy based on the deduced ARE sequence at the promoter region of the human prostate-specific antigen (PSA) gene. The nuclear extract was prepared from LNCaP cells, and DNA-protein interactions 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 lipofection. After 24-hr incubation with 10(-9) M dihydrotestosterone (DHT), induction of apoptosis was examined by DNA fragmentation. The gel shift assay demonstrated specific binding of the ARE decoy to the LNCaP nuclear protein which is most likely AR. The transfection experiment showed DNA fragmentation in the ARE decoy-transfected cells despite the presence of DHT, though not in the cells transfected with the control decoy. 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.