Efeito celular e perfil diagnóstico de peptídeo ligante à região promotora do gene PCA3 no câncer de próstata

Abstract

Prostate cancer (PCa) is the second leading cancer-related cause of death in men. The non-specificity of prostate-specific antigen in diagnosing the disease evidences the need for new markers. Prostate Cancer Gene 3 (PCA3) is expressed specifically in the prostate, being super expressed in PCa. Although used in clinical practice, its molecular control remains unknown. In this sense, we previously used Phage Display technology to select ligands to the promoter region of PCA3. In this study, we aimed to evaluate the cellular effect of phage particles expressing the recombinant peptide PCA3p4 in prostatic cell lines and its use as a diagnostic tool for PCa. Purified bacteriophages were used in the treatment of RWPE-1 (non-tumorigenic), LNCaP (hormone-responsive) and PC-3 (hormone-refractory) cell lines. Considering that it is a peptide that resembles a transcription factor, its ability to induce cell proliferation was evaluated by MTT in treatments for 24 and 48 hours in titers 105, 107 and 109. In addition, the profile of the peptide as a target of circulating antibodies for the diagnosis of PCa by ELISA was analyzed. After 24 hours, the phage titrated at 105 induced proliferation in LNCaP and PC-3, when compared to the control (p <0.05). After 48 hours, the proliferation was only verified on LNCAP with phage titrated at 107. For RWPE-1 the antiproliferative effect was observed in both treatments. For the assays with serum samples from patients, the peptide fused to the viral particle differentiated patients with PCa from those with Benign Prostatic Hyperplasia (p <0.05). In addition, the serological reactivity within the PCa group was higher in patients with advanced tumors (Gleason ≥7). Our results open new ways in elucidating the regulatory mechanisms that control the PCA3 gene, in order to design possible strategies for the treatment of PCa.