artepillin-c and Prostatic-Neoplasms

Propolis, a resinous substance produced by honeybees, possesses various biological actions including anticancer activity towards tumor cells. Recently, the ethanol extract of Brazilian green propolis has been shown to induce autophagy, which is known to be induced in treatment of cancer cells with anticancer drugs, leading to cancer cell survival and decreased sensitivity to anticancer agents. In this study, we aimed to identify autophagy-inducing components of the propolis and elucidated the reciprocal relationship between anticancer cytotoxicity and protective autophagy in prostate cancer CWR22Rv1 cells. Among eight cinnamic acid derivatives [chlorogenic acid, p-coumaric acid, caffeic acid, 3,4-caffeoylquinic acid, artepillin C (ArtC), baccharin, drupanin and caffeic acid phenethyl ester] in propolis, only ArtC showed high autophagy-inducing activity accompanying LC3-II upregulation. ArtC was also induced apoptosis as revealed by DNA fragmentation and increases in cleaved caspase-3 and poly ADP-ribose polymerase. The apoptosis induced by ArtC was exacerbated by cotreatment with autophagy inhibitors (chloroquine, wortmannin and U0126). The cotreatment further induced necroptosis accompanying increased expression of receptor-interacting serine/threonine protein kinases 1 and 3. These data indicate that cytotoxicity of ArtC to the prostate cancer cells is dampened by induced autophagy, but is markedly augmented by inhibition of autophagy. Therefore, the combination of ArtC and autophagy inhibitors may be a novel complementary-alternative treatment for prostate cancer.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Autophagy; Cell Line; Cinnamates; Dose-Response Relationship, Drug; Drug Synergism; Humans; Male; Phenylpropionates; Phytotherapy; Propolis; Prostatic Neoplasms; Treatment Outcome

Naturally occurring phenolic compounds have been shown to sensitize prostate cancer cells to tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. TRAIL is a potent stimulator of apoptosis in cancer cells and an important immune effector molecule in the surveillance and elimination of developing tumours. However, many cancer cells are resistant to TRAIL-mediated death. In this study, we aimed to determine the mechanisms by which TRAIL resistance can be overcome in prostate cancer cells by 3,5-diprenyl-4-hydroxycinnamic acid (artepillin C). Artepillin C is a bioactive component of Brazilian green propolis that possesses antitumour and chemopreventive activities. TRAIL-resistant LNCaP prostate cancer cells were treated with TRAIL and artepillin C. Cytotoxicity was measured by MTT and lactate dehydrogenase (LDH) assays. Apoptosis was detected using Annexin V-FITC staining by flow cytometry and fluorescence microscopy. Death receptor (DR) (TRAIL-R1/DR4 and TRAIL-R2/DR5) expression was analyzed using flow cytometry. Mitochondrial membrane potential (∆ψm) was evaluated using DePsipher staining by fluorescence micro-scopy. The inhibition of NF-κB (p65) activation was confirmed with the ELISA-based TransAM NF-κB kit. Caspase-8 and caspase-3 activities were determined by colorimetric protease assays. The results showed that artepillin C sensitized the TRAIL-resistant LNCaP cells by engaging the extrinsic (receptor-mediated) and intrinsic (mitochondrial) apoptotic pathways. Artepillin C increased the expression of TRAIL-R2 and decreased the activity of NF-κB. Co-treatment with TRAIL and artepillin C induced the significant activation of caspase-8 and caspase-3, as well as the disruption of ∆ψm. These findings show that prostate cancer cells can be sensitized to TRAIL-mediated immunoprevention by artepillin C and confirm the role of phenolic compounds in prostate cancer immunochemoprevention.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Caspase 3; Caspase 8; Cell Line, Tumor; Humans; Male; Membrane Potential, Mitochondrial; Mitochondria; NF-kappa B; Nucleic Acid Synthesis Inhibitors; Phenylpropionates; Prostatic Neoplasms; Receptors, Death Domain; Receptors, TNF-Related Apoptosis-Inducing Ligand; TNF-Related Apoptosis-Inducing Ligand