AKT/mTOR as Novel Targets of Polyphenol Piceatannol Possibly Contributing to Inhibition of Proliferation of Cultured Prostate Cancer Cells

Exploring the therapeutic potential of naturally occurring piceatannol in non-communicable diseases

Piceatannol is a naturally occurring hydroxylated resveratrol analogue that can be found in a variety of fruits and vegetables. It has been documented to have a wide range of beneficial effects, including anti-inflammatory, antioxidant, anti-aging, anti-allergic, antidiabetic, neuroprotective, cardioprotective, and chemopreventive properties. Piceatannol has significantly higher antioxidant activity than resveratrol. Piceatannol has been shown in preclinical studies to have the ability to inhibit or reduce the growth of cancers in various organs such as the brain, breast, lung, colon, cervical, liver, prostate, and skin. However, the bioavailability of Piceatannol is comparatively lower than resveratrol and other stilbenes. Several approaches have been reported in recent years to enhance its bioavailability and biological activity, and clinical trials are required to validate these findings. This review focuses on several aspects of natural stilbene Piceatannol, its chemistry, and its mechanism of action, and its promising therapeutic potential for the prevention and treatment of a wide variety of complex human diseases.

Autophagy activation by dietary piceatannol enhances the efficacy of immunogenic chemotherapy

Immunogenic cell death (ICD) promotes the immune antitumor response via releasing damage-associated molecular patterns (DAMPs) from dying tumor cells. The induction of autophagy improves the efficacy of multiple immunogenic chemotherapies. Here, we show that piceatannol, a dietary phenolic compound that is widely distributed in multiple fruits and vegetables such as grapes, blueberries, and mushrooms, induces autophagy and enhances oxaliplatin (OXA)-induced anticancer immune response. Specifically, piceatannol enhanced OXA-induced release of DAMPs, several key hallmarks of ICD including ATP release, cell surface exposure of calreticulin, and high-mobility group box 1 (HMGB1) release. Mechanistically, piceatannol promoted autophagy via activating TFEB/TFE3, two key transcription factors of the autophagy-lysosome pathway, and inhibiting autophagy attenuated piceatannol plus OXA-induced ATP release. Furthermore, piceatannol induced endoplasmic reticulum stress, which is critical for its role in enhancing OXA-induced cell surface exposure of calreticulin, another key hallmark of ICD. Consistently, the combination of piceatannol with OXA promoted the anticancer effects in immunocompetent mice. Taken together, our results indicate the importance and great potential of dietary piceatannol in cancer immunotherapy. Therefore, piceatannol may be used as an ICD enhancer that improves the efficacy of chemotherapeutics such as OXA in cancer treatment with minimized toxicity.

Chemotherapeutics activities of dietary phytoestrogens against prostate cancer: From observational to clinical studies

Prostate cancer remains one of the most frequent and deadliest malignancies in males, where the rate of disease progression is closely associated with the type of dietary intake, specifically Western-style diet. Indeed intake of the Asian diet, which contains abundant phytoestrogens, is inversely correlated with a higher risk of prostate cancer, suggesting a chemoprotective effect of phytoestrogen against cancer progression. Although the role of phytoestrogens in cancer treatment was well documented, their impact on prostate cancer is not well understood. Therefore, the present review discusses the possible chemopreventive effect of phytoestrogens, emphasizing their efficacy at the different stages of carcinogenesis. Furthermore, phytoestrogens provide a cytoprotective effect in conventional chemotherapy and enhance chemosensitivity to tumor cells, which have also been discussed. This compilation provides a solid basis for future research on phytoestrogens as a promising avenue for anticancer drug development and also recommends these beneficiary compounds in the daily diet to manage and prevent prostate cancer.

Piceatannol, a Structural Analog of Resveratrol, Is an Apoptosis Inducer and a Multidrug Resistance Modulator in HL-60 Human Acute Myeloid Leukemia Cells

Acute myeloid leukemia is characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells. Despite recent advances in the treatment of this disease, the prognosis and overall long-term survival for patients remain poor, which drives the search for new chemotherapeutics and treatment strategies. Piceatannol, a polyphenolic compound present in grapes and wine, appears to be a promising chemotherapeutic agent in the treatment of leukemia. The aim of the present study was to examine whether piceatannol induces autophagy and/or apoptosis in HL-60 human acute myeloid leukemia cells and whether HL-60 cells are able to acquire resistance to piceatannol toxicity. We found that piceatannol at the IC90 concentration of 14 µM did not induce autophagy in HL-60 cells. However, it induced caspase-dependent apoptosis characterized by phosphatidylserine externalization, disruption of the mitochondrial membrane potential, caspase-3 activation, internucleosomal DNA fragmentation, PARP1 cleavage, chromatin condensation, and fragmentation of cell nuclei. Our findings also imply that HL-60 cells are able to acquire resistance to piceatannol toxicity via mechanisms related to MRP1 activity. Our results suggest that the use of piceatannol as a potential chemotherapeutic agent may be associated with the risk of multidrug resistance, warranting its use in combination with other chemotherapeutic agents.

Systemic antioxidant and anti-inflammatory effects of yellow passion fruit bagasse extract during prostate cancer progression

We evaluated the impact of yellow passion fruit (Passiflora edulis sp.) bagasse extract (PFBE) administration in systemic oxidative and inflammatory parameters in vivo, considering prostate cancer progression in transgenic mice (TRAMP). Piceatannol, scirpusin-B, dicaffeoylquinic acid, citric acid, and (+)-catechin were identified in PFBE, and the extract showed high in vitro antioxidant capacity. Some alterations in systemic parameters were verified during prostate cancer progression, as the increase in ALT and MDA levels, and SOD and GPx activities in the plasma. In the liver, higher MDA, TNF-α, and NF-κB levels, and GR and GPx activities were verified. Compared to their respective controls, the short- and long-term PFBE administration reduced MDA levels in the liver and plasma. The long-term treatment increased the catalase activity in the plasma, while the short-term treatment increased the hepatic SOD and catalase activities. Still, a reduction in hepatic TNF-α and NF-κB levels was verified after long-term treatment. PRACTICAL APPLICATIONS: Prostate cancer progression is associated with changes in systemic redox status and inflammation markers. Moreover, the intake of polyphenols with antioxidant properties, besides delaying prostate carcinogenesis, may improve the systemic antioxidant defenses and inflammatory response. In vitro studies pointed to a promising antioxidant and anti-inflammatory potential of yellow passion fruit bagasse. However, in vivo studies are scarce. Our results provided information about in vivo impacts of PFBE oral consumption on antioxidant defense and inflammation, indicating its potential as an adjuvant during the initial steps of prostate cancer.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Overview of Cellular Mechanisms and Signaling Pathways of Piceatannol

Stilbenoids are a group of naturally occurring phenolic compounds found in various plant species. They share a common backbone structure known as stilbene. However, differences in the nature and position of substituents have made it possible to produce many derivatives. Piceatannol [PT], a hydroxylated derivative from resveratrol, exerts various biological activities ranging from cancer prevention, cardio- protection, neuro-protection, anti-diabetic, depigmentation and so on. Although positive results were obtained in most cell culture and animal studies, the relevant cellular and molecular mechanisms of cytokines and signaling pathway about their biological effects still unclear. Thus, in the current review, we focus on the latest findings of PT on cellular biology in order to better understand the underlying therapeutic mechanisms of PT among various diseases.

Piceatannol Inhibits P. acnes-Induced Keratinocyte Proliferation and Migration by Downregulating Oxidative Stress and the Inflammatory Response

The Cutibacterium acnes (also called Propionibacterium acnes, P. acnes)-induced proliferation and migration of keratinocytes contribute to acne vulgaris (AV), which is a common inflammatory skin disease that causes physical and psychological impairments. Piceatannol (3, 5, 3', 4'-tetrahydroxy-trans-stilbene, PCT) is naturally present in many human diets and plays antioxidant and anti-inflammatory roles that inhibit cell proliferation and migration. We aimed to analyse the functions and underlying mechanisms of PCT in P. acnes-stimulated keratinocytes. First, PCT showed no toxicity against the normal human keratinocyte cell line HaCaT but inhibited P. acnes-induced HaCaT cell proliferation. Next, PCT promoted the nuclear translocation and target gene transcription of the antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), thereafter decreasing intracellular reactive oxygen species (ROS) levels. In addition, PCT inhibited the nuclear translocation of p65 [a subunit of nuclear factor kappa B (NF-κB)] and the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interleukin-8 (IL-8). Finally, a transfection assay showed that PCT inhibited P. acnes-induced HaCaT cell proliferation and migration by activating the antioxidant Nrf2 pathway and inhibiting the inflammatory NF-κB pathway. Our data suggested that PCT alleviated P. acnes-induced HaCaT cell proliferation and migration through its antioxidant and anti-inflammatory roles, suggesting the potential of PCT to treat AV.

Prevention of Prostate Cancer in Transgenic Adenocarcinoma of the Mouse Prostate Mice by Yellow Passion Fruit Extract and Antiproliferative Effects of Its Bioactive Compound Piceatannol

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.

Piceatannol Suppresses the Proliferation and Induced Apoptosis of Osteosarcoma Cells Through PI3K/AKT/mTOR Pathway

Background

Piceatannol (PIC) is confirmed to inhibit the proliferation of various tumors, but its role in osteosarcoma still remains unknown. This study investigated the function of PIC in osteosarcoma, aiming to provide a research basis for osteosarcoma therapy.

Methods

Human osteosarcoma cells in this study were, respectively, treated with PIC at various concentrations (0, 20, 40, 80 μmol/L), PI3K/AKT/mTOR pathway inhibitor (LY294002), or pathway activator (740Y-P) plus PIC. Osteosarcoma cells were subcutaneously injected into nude mice to establish xenograft models, and PIC was intraperitoneally injected into models. The activity, proliferation, apoptosis and cell cycle of treated cells were determined by MTT test, colony formation assay or a flow cytometry. The expressions of PI3K/AKT/mTOR pathway-related proteins in cells and tumor tissues were measured by Western blot (WB) analysis.

Results

PIC (40 and 80 μmol/L) and LY294002 availably suppressed activity and proliferation and induced apoptosis of osteosarcoma cells. PIC observably increased the number of cells retarded in G2 phase, but decreased the cell percentages in G1 and S phases. Conversely, 740Y-P reversed the effects of PIC on osteosarcoma cells, which promoted cell activity and proliferation and restrained apoptosis. In xenograft models, the volume and weight of the tumors treated by PIC were visibly alleviated than those untreated. The PI3K/AKT/mTOR pathway was prominently inhibited in PIC-treated osteosarcoma cells and tumor tissues.

Conclusion

PIC suppresses the proliferation and induces apoptosis of osteosarcoma cells through regulating PI3K/AKT/mTOR pathway, which is expected to be the therapeutic of osteosarcoma.

Combinatorial Epigenetics Impact of Polyphenols and Phytochemicals in Cancer Prevention and Therapy

Polyphenols are potent micronutrients that can be found in large quantities in various food sources and spices. These compounds, also known as phenolics due to their phenolic structure, play a vital nutrient-based role in the prevention of various diseases such as diabetes, cardiovascular diseases, neurodegenerative diseases, liver disease, and cancers. However, the function of polyphenols in disease prevention and therapy depends on their dietary consumption and biological properties. According to American Cancer Society statistics, there will be an expected rise of 23.6 million new cancer cases by 2030. Due to the severity of the increased risk, it is important to evaluate various preventive measures associated with cancer. Relatively recently, numerous studies have indicated that various dietary polyphenols and phytochemicals possess properties of modifying epigenetic mechanisms that modulate gene expression resulting in regulation of cancer. These polyphenols and phytochemicals, when administrated in a dose-dependent and combinatorial-based manner, can have an enhanced effect on epigenetic changes, which play a crucial role in cancer prevention and therapy. Hence, this review will focus on the mechanisms of combined polyphenols and phytochemicals that can impact various epigenetic modifications such as DNA methylation and histone modifications as well as regulation of non-coding miRNAs expression for treatment and prevention of various types of cancer.

Progress to Improve Oral Bioavailability and Beneficial Effects of Resveratrol

Resveratrol (3,5,4'-trihydroxystilbene; RSV) is a natural nonflavonoid polyphenol present in many species of plants, particularly in grapes, blueberries, and peanuts. Several in vitro and in vivo studies have shown that in addition to antioxidant, anti-inflammatory, cardioprotective and neuroprotective actions, it exhibits antitumor properties. In mammalian models, RSV is extensively metabolized and rapidly eliminated and therefore it shows a poor bioavailability, in spite it of its lipophilic nature. During the past decade, in order to improve RSV low aqueous solubility, absorption, membrane transport, and its poor bioavailability, various methodological approaches and different synthetic derivatives have been developed. In this review, we will describe the strategies used to improve pharmacokinetic characteristics and then beneficial effects of RSV. These methodological approaches include RSV nanoencapsulation in lipid nanocarriers or liposomes, nanoemulsions, micelles, insertion into polymeric particles, solid dispersions, and nanocrystals. Moreover, the biological results obtained on several synthetic derivatives containing different substituents, such as methoxylic, hydroxylic groups, or halogens on the RSV aromatic rings, will be described. Results reported in the literature are encouraging but require additional in vivo studies, to support clinical applications.

Clinical characteristics, treatment outcomes and potential novel therapeutic options for patients with neuroendocrine carcinoma of the prostate

Background

Neuroendocrine carcinomas of the prostate (NEPCs) are rare tumors with poor prognosis. While platinum and etoposide-based chemotherapy regimens (PE) are commonly applied in first-line for advanced disease, evidence for second-line therapy and beyond is very limited.

Methods

Retrospective analysis of all patients with NEPCs including mixed differentiation with adenocarcinoma component and well differentiated neuroendocrine tumors (NETs, carcinoids) at two high-volume oncological centers between 12/2000 and 11/2017.

Results

Of 46 identified patients 39.1 % had a prior diagnosis of prostatic adenocarcinoma only, 43.5 % had a mixed differentiation at NEPC diagnosis, 67.4 % developed visceral metastases, 10.9 % showed paraneoplastic syndromes. Overall survival (OS) from NEPC diagnosis was 15.5 months, and significantly shorter in patients with a prior prostatic adenocarcinoma (5.4 vs. 32.7 months, p=0.005). 34 patients received palliative first-line systemic therapy with a median progression-free survival (PFS) of 6.6 months, mostly PE. Overall response rate (ORR) for PE was 48.1 %. 19 patients received second-line therapy, mostly with poor responses. Active regimens were topotecan (1 PR, 3 PD), enzalutamide (1 SD), abiraterone (1 SD), FOLFIRI (1 SD), and ipilimumab+nivolumab (1 PR). One patient with prostatic carcinoid was sequentially treated with octreotide, peptide receptor radionuclide therapy and everolimus, and survived for over 9 years.

Conclusions

EP in first-line shows notable ORR, however limited PFS. For second-line therapy, topotecan, FOLFIRI, enzalutamide, abiraterone and immune checkpoint blockade are treatment options. Prostatic carcinoids can be treated in analogy to well differentiated gastrointestinal NETs.

Epigenetic modifications by polyphenolic compounds alter gene expression in the hippocampus

In this study, we developed an experimental protocol leveraging enhanced reduced representation bisulphite sequencing to investigate methylation and gene expression patterns in the hippocampus in response to polyphenolic compounds. We report that the administration of a standardized bioavailable polyphenolic preparation (BDPP) differentially influences methylated cytosine patterns in introns, UTR and exons in hippocampal genes. We subsequently established that dietary BDPP-mediated changes in methylation influenced the transcriptional pattern of select genes that are involved in synaptic plasticity. In addition, we showed dietary BDPP mediated changes in the transcriptional pattern of genes associated with epigenetic modifications, including members of the DNA methyl transferase family (DNMTs) and the Ten-eleven translocation methylcytosine dioxygenases family (TETs). We then identified the specific brain bioavailable polyphenols effective in regulating the transcription of DNMTs, TETs and a subset of differentially methylated synaptic plasticity-associated genes. The study implicates the regulation of gene expression in the hippocampus by epigenetic mechanisms as a novel therapeutic target for dietary polyphenols.

Summary: The health benefits of dietary polyphenols may be due to their ability to change epigenetic marks in the brain. More studies will clarify how polyphenols from diet can improve mental health.

Dietary polyphenols promote resilience against sleep deprivation-induced cognitive impairment by activating protein translation

Previous evidence has suggested that dietary supplementation with a bioactive dietary polyphenol preparation (BDPP) rescues impairment of hippocampus-dependent memory in a mouse model of sleep deprivation (SD). In the current study, we extend our previous evidence and demonstrate that a mechanism by which dietary BDPP protects against SD-mediated cognitive impairment is via mechanisms that involve phosphorylation of the mammalian target of rapamycin complex 1 and its direct downstream targets, including the eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) and the ribosomal protein S6 kinase β-1 (p70S6K). In additional mechanistic studies in vitro, we identified the brain bioavailable phenolic metabolites derived from the metabolism of dietary BDPP that are responsible for the attenuation of SD-mediated memory impairments. On the basis of high-throughput bioavailability studies of brain bioavailable metabolites after dietary BDPP treatment, we found that select polyphenol metabolites [ e.g., cyanidin-3'- O-glucoside and 3-(3'-hydroxyphenyl) propionic acid] were able to rescue mTOR and p70S6K phosphorylation in primary cortico-hippocampal neuronal cultures, as well as rescue 4E-BP1 phosphorylation in response to treatment with 4EGI-1, a specific inhibitor of eIF4E-eIF4G interaction. Our findings reveal a previously unknown role for dietary polyphenols in the rescue of SD-mediated memory impairments via mechanisms involving the promotion of protein translation.-Frolinger, T., Smith, C., Cobo, C. F., Sims, S., Brathwaite, J., de Boer, S., Huang, J., Pasinetti, G. M. Dietary polyphenols promote resilience against sleep deprivation-induced cognitive impairment by activating protein translation.

Natural Polyphenols for Prevention and Treatment of Cancer

There is much epidemiological evidence that a diet rich in fruits and vegetables could lower the risk of certain cancers. The effect has been attributed, in part, to natural polyphenols. Besides, numerous studies have demonstrated that natural polyphenols could be used for the prevention and treatment of cancer. Potential mechanisms included antioxidant, anti-inflammation as well as the modulation of multiple molecular events involved in carcinogenesis. The current review summarized the anticancer efficacy of major polyphenol classes (flavonoids, phenolic acids, lignans and stilbenes) and discussed the potential mechanisms of action, which were based on epidemiological, in vitro, in vivo and clinical studies within the past five years.

A Comprehensive Review on the Chemotherapeutic Potential of Piceatannol for Cancer Treatment, with Mechanistic Insights

Cancer is a diverse class of diseases characterized by uncontrolled cell growth that constitutes the greatest cause of mortality and morbidity worldwide. Despite steady progress, the treatment modalities of cancer are still insufficient. Several new concepts have emerged for therapeutic intervention in malignant diseases with the goal of identifying specific targets and overcoming resistance against current cytotoxic therapies. Many studies have reported the remarkable and significant properties of dietary plant polyphenols such as curcumin, resveratrol, flavopiridol, indirubin, magnolol, piceatannol, parthenolide, epigallocatechin gallate, and cucurbitacin as anticancer agents known for their pleiotropic effects on cancer, immune cells, and inflammation. Piceatannol, an analogue and metabolite of resveratrol, is a natural stilbene commonly found in grape skins and wine. Compared to resveratrol, this molecule exhibits superior bioactivities as an inhibitor of COX-1/2 and the CSN-associated kinase. Piceatannol is thought to be a potent natural compound with many therapeutic effects, such as the prevention of hypercholesterolemia, arrhythmia, atherosclerosis, angiogenesis, and cardiovascular diseases. It also demonstrates vasorelaxation, antioxidant, and anticancer activities. This comprehensive review summarizes the current data regarding the mechanisms of action of piceatannol, its chemopreventive properties, and its possible therapeutic potential against various types of human cancer.

Novel application of brain-targeting polyphenol compounds in sleep deprivation-induced cognitive dysfunction

Sleep deprivation produces deficits in hippocampal synaptic plasticity and hippocampal-dependent memory storage. Recent evidence suggests that sleep deprivation disrupts memory consolidation through multiple mechanisms, including the down-regulation of the cAMP-response element-binding protein (CREB) and of mammalian target of rapamycin (mTOR) signaling. In this study, we tested the effects of a Bioactive Dietary Polyphenol Preparation (BDPP), comprised of grape seed polyphenol extract, Concord grape juice, and resveratrol, on the attenuation of sleep deprivation-induced cognitive impairment. We found that BDPP significantly improves sleep deprivation-induced contextual memory deficits, possibly through the activation of CREB and mTOR signaling pathways. We also identified brain-available polyphenol metabolites from BDPP, among which quercetin-3-O-glucuronide activates CREB signaling and malvidin-3-O-glucoside activates mTOR signaling. In combination, quercetin and malvidin-glucoside significantly attenuated sleep deprivation-induced cognitive impairment in -a mouse model of acute sleep deprivation. Our data suggests the feasibility of using select brain-targeting polyphenol compounds derived from BDPP as potential therapeutic agents in promoting resilience against sleep deprivation-induced cognitive dysfunction.

Piceatannol exhibits selective toxicity to multiple myeloma cells and influences the Wnt/ beta-catenin pathway

Aberrant activation of Wnt/β-catenin signaling promotes development and progression of various malignant neoplasms. Recent studies observed that the Wnt pathway is constitutively active in myeloma cells and promotes an exaggerated proliferation. Thus, the Wnt signaling pathway might be an attractive therapeutic target for multiple myeloma. In this study, we identified piceatannol as an inhibitor of the Wnt/β-catenin pathway and as a potent inducer of apoptosis in myeloma cells. Interestingly, healthy cells remained mainly unaffected. These results reveal a significant selective induction of apoptosis by piceatannol and suggest a significant in vivo effect against multiple myeloma.