RESUMO
BACKGROUND: Elevated NF-κB activity has been previously demonstrated in prostate cancer cell lines as hormone-independent or metastatic characteristics develop. We look at the effects of piperlongumine (PL), a biologically active alkaloid/amide present in piper longum plant, on the NF-κB pathway in androgen-independent prostate cancer cells. METHODS: NF-κB activity was evaluated using Luciferase reporter assays and Western blot analysis of p50 and p65 nuclear translocation. IL-6, IL-8, and MMP-9 levels were assessed using ELISA. Cellular adhesion and invasiveness properties of prostate cancer cells treated with PL were also assessed. RESULTS: NF-κB DNA-binding activity was directly down-regulated with increasing concentrations of PL, along with decreased nuclear translocation of p50 and p65 subunits. Expression of IL-6, IL-8, MMP-9, and ICAM-1 was attenuated, and a decrease of cell-to-matrix adhesion and invasiveness properties of prostate cancer cells were observed. CONCLUSIONS: PL-mediated inhibition of NF-κB activity decreases aggressive growth characteristics of prostate cancer cells in vitro.
Assuntos
Adenocarcinoma/patologia , Proliferação de Células/efeitos dos fármacos , Dioxolanos/farmacologia , NF-kappa B/antagonistas & inibidores , Extratos Vegetais/farmacologia , Neoplasias da Próstata/patologia , Adenocarcinoma/metabolismo , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Humanos , Técnicas In Vitro , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Masculino , Metaloproteinase 9 da Matriz/metabolismo , NF-kappa B/efeitos dos fármacos , NF-kappa B/metabolismo , Neoplasias da Próstata/metabolismoRESUMO
BACKGROUND: Androgen receptor (AR) signaling is regarded as the driving force in prostate carcinogenesis, and its modulation represents a logical target for prostate cancer (PC) prevention and treatment. Natural products are the most consistent source of small molecules for drug development. In this study, we investigate the functional impact of piperlongumine (PL), a naturally occurring alkaloid present in the Long pepper (Piper longum), on AR expression in PC cells and delineate its mechanism of action. METHODS: Expression and transcriptional activity of AR was examined by western blotting and luciferase reporter assay, respectively. CellTiter Blue assay was utilized to quantify cell proliferation. Reactive oxygen species (ROS) generation was examined by staining cells with a ROS indicator CM-H(2) DCFDA, followed by flow cytometry analysis. RESULTS: The results of our experiments demonstrate that PL rapidly reduces AR protein levels in PC cells via proteasome-mediated ROS-dependent mechanism. Moreover, PL effectively depletes a modified AR lacking the ligand-binding domain, shedding light on a new paradigm in the treatment approach to prostatic carcinoma that expresses mutated constitutively active AR. Importantly, PL effectively depletes AR in PC cells at low micromolar concentrations, while concurrently exerting a significant inhibitory effect on AR transcriptional activity and proliferation of PC cells. CONCLUSIONS: Our investigation demonstrates for the first time that PL induces rapid depletion of the AR in PC cells. As such, PL may afford novel opportunities for both prevention and treatment of prostatic malignancy.
Assuntos
Adenocarcinoma/tratamento farmacológico , Antineoplásicos/farmacologia , Dioxolanos/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Receptores Androgênicos/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Estresse Oxidativo/efeitos dos fármacos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores Androgênicos/genéticaRESUMO
Zinc accumulation is lost during prostate carcinogenesis. Recent studies reveal a strong association between prostate cancer progression and the downregulation of the zinc uptake transporters hZip1 and hZip3. The aim of this work was to assess the involvement of epigenetic processes in the disruption of zinc uptake homeostasis in prostate adenocarcinoma. In this report, we demonstrate an increase in hZip1 and hZip3 zinc transporters' expression and zinc uptake by the prostate cancer cells DU-145 and LNCaP in response to 5-aza-2'-deoxycytidine. This effect is due to demethylation of the promoter region of the activator protein (AP)-2alpha protein, which is crucial for hZip1 and hZip3 genes expression. Loss of AP-2alpha expression in DU-145 and LNCaP prostate cancer cells is due to hypermethylation of its promoter region. Similarly, we found higher AP-2alpha promoter methylation levels in clinical samples of early-stage prostate adenocarcinoma when compared with adjacent non-malignant prostate tissue. Taken together, our findings provide a better understanding of the epigenetic mechanisms that are involved in the loss of AP-2alpha protein in prostate cancer cells which lead to decreased cellular zinc uptake-a sine qua non of prostate cancer development.
