R9-AR-PIP is a small peptide mimicking androgen receptor (AR) PIP-box that inhibit the PCNA/AR interaction, inhibits the expression of AR target genes, AR transcriptional activity and the growth of AR-expressing cells, binds to GFP-PCNA with Kd of 2.73 uM in MST assays.
R9-AR-PIP contains eight amino acid residues of the AR PIP-box sequence and nine arginine residues linked with two cystine residues.
R9-AR-PIP inhibited the growth of androgen-dependent LNCaP cells both in the absence and presence of DHT with an IC50 value of 8-10 uM.
R9-AR-PIP inhibits the expression of AR target genes and cell growth.
R9-AR-PIP inhibits AR occupancy at the androgen response element (ARE) in PSA and p21 genes, and expression of AR target genes, and induces cytotoxicity in AR-positive castration-resistant prostate cancer (CRPC) cells.
R9-AR-PIP also significantly inhibits transcriptional activity of AR-FL upon dihydrotestosterone stimulation and the constitutive activity of AR-V7.
R9-AR-PIP inhibits the ARE occupancy by AR-FL and AR-Vs in CCNA2 gene that encodes cyclin A2 and cyclin A2 expression.