Piceatannol (PIC), a polyphenol presents in many vegetables and fruits including yellow passion fruit extract (PFE; Passiflora edulis), has anti-cancer activity, but its molecular targets are still poorly understood. The aims of this study were to investigate the molecular mechanistic actions of PIC in prostate cancer cell lines and to test if the extract from PFE rich in PIC can affect the growth of prostate cancer cells in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The PC-3, 22Rv1, LNCaP, and VCaP prostate cancer cells were exposed to PIC (10-40 μM), and cell viability, lactate measurement, Western blot, and flow cytometric analyses were performed. For an in vivo experiments, eight-week-old TRAMP mice (n = 10 per group each) received an aqueous extract of PFE containing 20 mg of PIC/kg or water (control group) by gavage for 4 or 10 weeks for further analyses. PIC treatment concentration- and time-dependently reduced viability of all cell lines tested. 22Rv1 and LNCaP cells treated with PIC did not exhibit any significant alteration in the intracellular accumulation of lactate. PIC treatment caused G0/G1 phase cell cycle arrest and induction of apoptosis in both LNCaP and 22Rv1 cells. PIC-treated cells exhibited altered protein levels of p53, p21, cyclin D1, and cyclin-dependent kinase 4 (cdk4). The short and long-term PFE treatments also affected p21, cyclin D1 and cdk4 and delayed disease progression in TRAMP, with a decreased incidence of preneoplastic lesions. In conclusion, PIC apparently does not alter glucose metabolism in prostate cancer cells, while cell cycle arrest and p53 modulation are likely important in anti-cancer effects of PIC alone or as a food matrix byproduct in prostate cancer cells, especially those with an androgen-dependent phenotype.

Jaboticaba is a Brazilian berry, which is rich in fibers and bioactive compounds and shows high antioxidant and antiproliferative activities. Prostate cancer (PCa) is the second most common type of cancer among men and its progression is influenced by androgens and inflammation. Previous studies reported the ability of the jaboticaba to modulate pathways involved in prostate diseases. The main objective of this study was to provide significant data about molecular targets of the jaboticaba peel extract (JPE) and its mechanisms of action in PCa cell lines with different androgenic status (LNCaP and PC-3). The results showed that JPE was able to decrease cell viability in both cell lines. LNCaP showed more sensitivity to JPE exposure, indicating the efficacy of the JPE treatment in terms of androgen responsiveness. JPE showed a distinct hormone dependent effect on the NF-κB signaling, with reduced NF-κB levels for LNCaP and increased NF-κB levels in PC-3 cells. Mechanisms related to cell death by apoptosis were stimulated after the JPE treatment, modulating B-cell lymphoma 2 and BAX for LNCaP and PC-3. Particularly for PC-3, the JPE treatment resulted in cytokine-cytokine receptor interaction activation mostly by up regulating pro-inflammatory, pro-angiogenic, immunostimulatory and immunosuppressive genes. Also, a set of genes related to angiogenesis and metastasis were down-regulated by JPE. In conclusion, JPE exerted an antitumor effect on PCa for both cell lines which can be enhanced if androgenic reliance is considered.