Dual action on promoter demethylation and chromatin by an isothiocyanate restored GSTP1 silenced in prostate cancer

Phytocompounds targeting epigenetic modulations: an assessment in cancer

For centuries, plants have been serving as sources of potential therapeutic agents. In recent years, there has been a growing interest in investigating the effects of plant-derived compounds on epigenetic processes, a novel and captivating Frontier in the field of epigenetics research. Epigenetic changes encompass modifications to DNA, histones, and microRNAs that can influence gene expression. Aberrant epigenetic changes can perturb key cellular processes, including cell cycle control, intercellular communication, DNA repair, inflammation, stress response, and apoptosis. Such disruptions can contribute to cancer development by altering the expression of genes involved in tumorigenesis. However, these modifications are reversible, offering a unique avenue for therapeutic intervention. Plant secondary compounds, including terpenes, phenolics, terpenoids, and sulfur-containing compounds are widely found in grains, vegetables, spices, fruits, and medicinal plants. Numerous plant-derived compounds have demonstrated the potential to target these abnormal epigenetic modifications, including apigenin (histone acetylation), berberine (DNA methylation), curcumin (histone acetylation and epi-miRs), genistein (histone acetylation and DNA methylation), lycopene (epi-miRs), quercetin (DNA methylation and epi-miRs), etc. This comprehensive review highlights these abnormal epigenetic alterations and discusses the promising efficacy of plant-derived compounds in mitigating these deleterious epigenetic signatures in human cancer. Furthermore, it addresses ongoing clinical investigations to evaluate the therapeutic potential of these phytocompounds in cancer treatment, along with their limitations and challenges.

Dietary Plant Metabolites Induced Epigenetic Modification as a Novel Strategy for the Management of Prostate Cancer

Prostate cancer is a widespread malignancy among men, with a substantial global impact on morbidity and mortality. Despite advances in conventional therapies, the need for innovative and less toxic treatments remains a priority. Emerging evidence suggests that dietary plant metabolites possess epigenetic-modifying properties, making them attractive candidates for prostate cancer treatment. The present work reviews the epigenetic effects of dietary plant metabolites in the context of prostate cancer therapy. We first outline the key epigenetic mechanisms involved in prostate cancer pathogenesis, including histone modifications, DNA methylation, and miRNA or Long Noncoding RNA (lncRNA) dysregulation. Next, we delve into the vast array of dietary plant metabolites that have demonstrated promising anti-cancer effects through epigenetic regulation. Resveratrol, minerals, isothiocyanates, curcumin, tea polyphenols, soy isoflavones and phytoestrogens, garlic compounds, anthocyanins, lycopene, and indoles are among the most extensively studied compounds. These plant-derived bioactive compounds have been shown to influence DNA methylation patterns, histone modifications, and microRNA expression, thereby altering the gene expression allied with prostate cancer progression, cell proliferation, and apoptosis. We also explore preclinical and clinical studies investigating the efficacy of dietary plant metabolites as standalone treatments or in combination with traditional treatments for people with prostate cancer. The present work highlights the potential of dietary plant metabolites as epigenetic modulators to treat prostate cancer. Continued research in this field may pave the way for personalized and precision medicine approaches, moving us closer to the goal of improved prostate cancer management.

Metabolo-epigenetic interplay provides targeted nutritional interventions in chronic diseases and ageing

Epigenetic modifications are chemical modifications that affect gene expression without altering DNA sequences. In particular, epigenetic chemical modifications can occur on histone proteins -mainly acetylation, methylation-, and on DNA and RNA molecules -mainly methylation-. Additional mechanisms, such as RNA-mediated regulation of gene expression and determinants of the genomic architecture can also affect gene expression. Importantly, depending on the cellular context and environment, epigenetic processes can drive developmental programs as well as functional plasticity. However, misbalanced epigenetic regulation can result in disease, particularly in the context of metabolic diseases, cancer, and ageing. Non-communicable chronic diseases (NCCD) and ageing share common features including altered metabolism, systemic meta-inflammation, dysfunctional immune system responses, and oxidative stress, among others. In this scenario, unbalanced diets, such as high sugar and high saturated fatty acids consumption, together with sedentary habits, are risk factors implicated in the development of NCCD and premature ageing. The nutritional and metabolic status of individuals interact with epigenetics at different levels. Thus, it is crucial to understand how we can modulate epigenetic marks through both lifestyle habits and targeted clinical interventions -including fasting mimicking diets, nutraceuticals, and bioactive compounds- which will contribute to restore the metabolic homeostasis in NCCD. Here, we first describe key metabolites from cellular metabolic pathways used as substrates to "write" the epigenetic marks; and cofactors that modulate the activity of the epigenetic enzymes; then, we briefly show how metabolic and epigenetic imbalances may result in disease; and, finally, we show several examples of nutritional interventions - diet based interventions, bioactive compounds, and nutraceuticals- and exercise to counteract epigenetic alterations.

Prospective Epigenetic Actions of Organo-Sulfur Compounds against Cancer: Perspectives and Molecular Mechanisms

Major epigenetic alterations, such as chromatin modifications, DNA methylation, and miRNA regulation, have gained greater attention and play significant roles in oncogenesis, representing a new paradigm in our understanding of cancer susceptibility. These epigenetic changes, particularly aberrant promoter hypermethylation, abnormal histone acetylation, and miRNA dysregulation, represent a set of epigenetic patterns that contribute to inappropriate gene silencing at every stage of cancer progression. Notably, the cancer epigenome possesses various HDACs and DNMTs, which participate in the histone modifications and DNA methylation. As a result, there is an unmet need for developing the epigenetic inhibitors against HDACs and DNMTs for cancer therapy. To date, several epigenetically active synthetic inhibitors of DNA methyltransferases and histone deacetylases have been developed. However, a growing body of research reports that most of these synthetic inhibitors have significant side effects and a narrow window of specificity for cancer cells. Targeting tumor epigenetics with phytocompounds that have the capacity to modulate abnormal DNA methylation, histone acetylation, and miRNAs expression is one of the evolving strategies for cancer prevention. Encouragingly, there are many bioactive phytochemicals, including organo-sulfur compounds that have been shown to alter the expression of key tumor suppressor genes, oncogenes, and oncogenic miRNAs through modulation of DNA methylation and histones in cancer. In addition to vitamins and microelements, dietary phytochemicals such as sulforaphane, PEITC, BITC, DADS, and allicin are among a growing list of naturally occurring anticancer agents that have been studied as an alternative strategy for cancer treatment and prevention. Moreover, these bioactive organo-sulfur compounds, either alone or in combination with other standard cancer drugs or phytochemicals, showed promising results against many cancers. Here, we particularly summarize and focus on the impact of specific organo-sulfur compounds on DNA methylation and histone modifications through targeting the expression of different DNMTs and HDACs that are of particular interest in cancer therapy and prevention.

Metronomic doses and drug schematic combination response tested within chambered coverslips for the treatment of breast cancer cells (JIMT-1)

Low-dose metronomic (LDM) chemotherapy is an alternative to conventional chemotherapy and is the most frequently used approach in low dose chemotherapy regimens. The selection of patients, drug dosages, and dosing intervals in LDM is empirical. In this study, we systematically examined the schedule-dependent interaction of drugs on a breast cancer cell line (BCC) cultured in chambered coverslips. The LDM studies were combined with cell staining in order to better characterize different cell states and cell death modes, including caspase-dependent apoptosis, caspase-independent cell death and autophagy-dependent cell death. Microscope images were examined using the Fiji Trainable Weka Segmentation plugin to analyse cell area in 7500 images showing different modes of cell death. Paclitaxel combined with LDM chemotherapy demonstrated a reduction in the area covered by live cells. In contrast, there was an induction of high levels of cell death due to caspase-dependent apoptosis.

Hydrogen Sulfide Biology and Its Role in Cancer

Hydrogen sulfide (H2S) is an endogenous biologically active gas produced in mammalian tissues. It plays a very critical role in many pathophysiological processes in the body. It can be endogenously produced through many enzymes analogous to the cysteine family, while the exogenous source may involve inorganic sulfide salts. H2S has recently been well investigated with regard to the onset of various carcinogenic diseases such as lung, breast, ovaries, colon cancer, and neurodegenerative disorders. H2S is considered an oncogenic gas, and a potential therapeutic target for treating and diagnosing cancers, due to its role in mediating the development of tumorigenesis. Here in this review, an in-detail up-to-date explanation of the potential role of H2S in different malignancies has been reported. The study summarizes the synthesis of H2S, its roles, signaling routes, expressions, and H2S release in various malignancies. Considering the critical importance of this active biological molecule, we believe this review in this esteemed journal will highlight the oncogenic role of H2S in the scientific community.

DNA Methylation of T Lymphocytes as a Therapeutic Target: Implications for Rheumatoid Arthritis Etiology

Rheumatoid arthritis (RA) is an autoimmune disease that can cause joint damage and disability. Epigenetic variation, especially DNA methylation, has been shown to be involved in almost all the stages of the pathology of RA, from autoantibody production to various self-effector T cells and the defects of protective T cells that can lead to chronic inflammation and erosion of bones and joints. Given the critical role of T cells in the pathology of RA, the regulatory functions of DNA methylation in T cell biology remain unclear. In this review, we elaborate on the relationship between RA pathogenesis and DNA methylation in the context of different T cell populations. We summarize the relevant methylation events in T cell development, differentiation, and T cell-related genes in disease prediction and drug efficacy. Understanding the epigenetic regulation of T cells has the potential to profoundly translate preclinical results into clinical practice and provide a framework for the development of novel, individualized RA therapeutics.

Development of human prostate cancer stem cells involves epigenomic alteration and PI3K/AKT pathway activation

Background

Human prostate cancer spheres endowed with stem cell properties have been obtained from androgen-dependent cell line LNCaP after exposure to an epigenomic modulator phenethyl isothiocynate (PEITC). Sphere cells can self-renew and grow with androgen, and also without androgen. Little is known about the signaling pathway and mechanism in the development of the stem cells in the spheres.

Methods

Expression of phosphoinositol-3 kinase (PI3K) pathway members and histone acetylation were quantified in the tumor spheres and LNCaP cells by western immunoblotting.

Results

The level of phosphorylated AKT was significantly increased in the sphere stem cells than the LNCaP cells at an average of 7.4 folds (range 5.8–10.7 folds), whereas the P27 level was elevated 5.4 folds (range 4.8–6.3 folds) (P < 0.05). The acetylation level on histone H3 lysine 9 was decreased.

Conclusions

PEITC appears to regulate the epigenome through histone acetylation and activate the PI3K/AKT pathway in the LNCaP cells. This mechanism may be responsible in part for the development of the prostate cancer stem cells.

Maternal Epigenetic Regulation Contributes to Prevention of Estrogen Receptor-negative Mammary Cancer with Broccoli Sprout Consumption

Cruciferous vegetables have been of special interest due to the rich presence of bioactive compounds such as sulforaphane which show promising potential on cancer prevention and therapy as an epigenetic dietary strategy. Abnormal epigenetic alteration as one of the primary contributors to tumor development is closely related to breast cancer initiation and progression. In the present study, we investigated the effect of dietary broccoli sprouts (BSp), a common cruciferous vegetable, on prevention of estrogen receptor (ER)-negative mammary tumors at three different temporal exposure windows using a spontaneous breast cancer mouse model. Our findings indicate that maternal BSp treatment exhibited profound inhibitory and preventive effects on mammary cancer formation in the nontreated mouse offspring. The BSp diet administered to adult mice also showed suppressive effects on mammary cancer but was not as profound as the maternal BSp preventive effects. Moreover, such protective effects were linked with differentially expressed tumor- and epigenetic-related genes, as well as altered global histone acetylation, DNA methylation, and DNA hydroxymethylation levels. We also found that the expression changes of tumor-related genes were associated with the levels of histone methylation of H3K4 and H3K9 in the gene promoter regions. In addition, BSp-enriched sulforaphane was shown to increase protein expression of tumor suppressor genes such as p16 and p53 and inhibit the protein levels of Bmi1, DNA methyltransferases, and histone deacetylases in ERα-negative breast cancer cell lines. Collectively, these results suggest that maternal exposure to key phytochemicals may contribute to ER-negative mammary tumor prevention in their offspring through epigenetic regulations.

Liposome Delivery of Natural STAT3 Inhibitors for the Treatment of Cancer

In the tumor microenvironment, cytokines, growth factors, and oncogenes mediate constitutive activation of the signal transducer and activator of transcription 3 (STAT3) signaling pathway in both cancer cells and infiltrating immune cells. STAT3 activation in cancer cells drives tumorigenic changes that allow for increased survival, proliferation, and resistance to apoptosis. The modulation of immune cells is more complicated and conflicting. STAT3 signaling drives the myeloid cell phenotype towards an immune suppressive state, which mediates T cell inhibition. On the other hand, STAT3 signaling in T cells leads to proliferation and T cell activity required for an anti-tumor response. Targeted delivery of STAT3 inhibitors to cancer cells and myeloid cells could therefore improve therapeutic outcomes. Many compounds that inhibit the STAT3 pathways for cancer treatment include peptide drugs, small molecule inhibitors, and natural compounds. However, natural compounds that inhibit STAT3 are often hydrophobic, which reduces their bioavailability and leads to unfavorable pharmacokinetics. This review focuses specifically on liposome-encapsulated natural STAT3 inhibitors and their ability to target cancer cells and myeloid cells to reduce tumor growth and decrease STAT3-mediated immune suppression. Many of these liposome formulations have led to profound tumor reduction and examples of combination formulations have been shown to eliminate tumors through immune modulation.

In Search of Panacea-Review of Recent Studies Concerning Nature-Derived Anticancer Agents

Cancers are one of the leading causes of deaths affecting millions of people around the world, therefore they are currently a major public health problem. The treatment of cancer is based on surgical resection, radiotherapy, chemotherapy or immunotherapy, much of which is often insufficient and cause serious, burdensome and undesirable side effects. For many years, assorted secondary metabolites derived from plants have been used as antitumor agents. Recently, researchers have discovered a large number of new natural substances which can effectively interfere with cancer cells’ metabolism. The most famous groups of these compounds are topoisomerase and mitotic inhibitors. The aim of the latest research is to characterize natural compounds found in many common foods, especially by means of their abilities to regulate cell cycle, growth and differentiation, as well as epigenetic modulation. In this paper, we focus on a review of recent discoveries regarding nature-derived anticancer agents.

Prenatal epigenetics diets play protective roles against environmental pollution

It is thought that germ cells and preimplantation embryos during development are most susceptible to endogenous and exogenous environmental factors because the epigenome in those cells is undergoing dramatic elimination and reconstruction. Exposure to environmental factors such as nutrition, climate, stress, pathogens, toxins, and even social behavior during gametogenesis and early embryogenesis has been shown to influence disease susceptibility in the offspring. Early-life epigenetic modifications, which determine the expression of genetic information stored in the genome, are viewed as one of the general mechanisms linking prenatal exposure and phenotypic changes later in life. From atmospheric pollution, endocrine-disrupting chemicals to heavy metals, research increasingly suggests that environmental pollutions have already produced significant consequences on human health. Moreover, mounting evidence now links such pollution to relevant modification in the epigenome. The epigenetics diet, referring to a class of bioactive dietary compounds such as isothiocyanates in broccoli, genistein in soybean, resveratrol in grape, epigallocatechin-3-gallate in green tea, and ascorbic acid in fruits, has been shown to modify the epigenome leading to beneficial health outcomes. This review will primarily focus on the causes and consequences of prenatal environment pollution exposure on the epigenome, and the potential protective role of the epigenetics diet, which could play a central role in neutralizing epigenomic aberrations against environmental pollutions.

The Role of Isothiocyanates as Cancer Chemo-Preventive, Chemo-Therapeutic and Anti-Melanoma Agents

Many studies have shown evidence in support of the beneficial effects of phytochemicals in preventing chronic diseases, including cancer. Among such phytochemicals, sulphur-containing compounds (e.g., isothiocyanates (ITCs)) have raised scientific interest by exerting unique chemo-preventive properties against cancer pathogenesis. ITCs are the major biologically active compounds capable of mediating the anticancer effect of cruciferous vegetables. Recently, many studies have shown that a higher intake of cruciferous vegetables is associated with reduced risk of developing various forms of cancers primarily due to a plurality of effects, including (i) metabolic activation and detoxification, (ii) inflammation, (iii) angiogenesis, (iv) metastasis and (v) regulation of the epigenetic machinery. In the context of human malignant melanoma, a number of studies suggest that ITCs can cause cell cycle growth arrest and also induce apoptosis in human malignant melanoma cells. On such basis, ITCs could serve as promising chemo-therapeutic agents that could be used in the clinical setting to potentiate the efficacy of existing therapies.

Histone Modifications as an Intersection Between Diet and Longevity

Histone modifications are key epigenetic regulators that control chromatin structure and gene transcription, thereby impacting on various important cellular phenotypes. Over the past decade, a growing number of studies have indicated that changes in various histone modifications have a significant influence on the aging process. Furthermore, it has been revealed that the abundance and localization of histone modifications are responsive to various environmental stimuli, such as diet, which can also affect gene expression and lifespan. This supports the notion that histone modifications can serve as a main cellular platform for signal integration. Hence, in this review we focus on the role of histone modifications during aging, report the data indicating that diet affects histone modification levels and explore the idea that histone modifications may function as an intersection through which diet regulates lifespan. A greater understanding of the epigenetic mechanisms that link environmental signals to longevity may provide new strategies for therapeutic intervention in age-related diseases and for promoting healthy aging.

Mitochondrion at the Crossroad Between Nutrients and Epigenome

Epigenetic profile is the link between the regulation of nuclear gene expression and the environment. The most important factors capable of significantly affecting the cellular environment are the amount and quality of nutrients available. Mitochondria are both involved in the production of some of the molecules capable of directly affecting the epigenome and have a critical role in the conversion of nutrients into usable energy. Carbohydrate and fats are converted into ATP, acetyl-CoA, SAM, and NADH. These high-energy substrates are, in turn, capable of driving the epigenetic profile. We describe substances capable of affecting this mechanism. On the other hand, nutritional interventions capable of reducing calories or significantly impairing the normal Acetyl-CoA production or the SAM-SAH ratio also impact chromatin methylation and histone modification, suggesting a critical role of mitochondria on nutrient-dependent epigenetic profile.

Phenethyl Isothiocyanate, a Dual Activator of Transcription Factors NRF2 and HSF1

Cruciferous vegetables are rich sources of glucosinolates which are the biogenic precursor molecules of isothiocyanates (ITCs). The relationship between the consumption of cruciferous vegetables and chemoprotection has been widely documented in epidemiological studies. Phenethyl isothiocyanate (PEITC) occurs as its glucosinolate precursor gluconasturtiin in the cruciferous vegetable watercress (Nasturtium officinale). PEITC has multiple biological effects, including activation of cytoprotective pathways, such as those mediated by the transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) and the transcription factor heat shock factor 1 (HSF1), and can cause changes in the epigenome. However, at high concentrations, PEITC leads to accumulation of reactive oxygen species and cytoskeletal changes, resulting in cytotoxicity. Underlying these activities is the sulfhydryl reactivity of PEITC with cysteine residues in its protein targets. This chemical reactivity highlights the critical importance of the dose of PEITC for achieving on-target selectivity, which should be carefully considered in the design of future clinical trials.

Food as Pharma? The Case of Glucosinolates

BACKGROUND

Glucosinolates (GLSs) are dietary plant secondary metabolites occurring in the order Brassicales with potential health effects, in particular as anti-carcinogenic compounds. GLSs are converted into a variety of breakdown products (BPs) upon plant tissue damage and by the gut microbiota. GLS biological activity is related to BPs rather than to GLSs themselves.

METHODS

we have reviewed the most recent scientific literature on the metabolic fate and the biological effect of GLSs with particular emphasis on the epidemiological evidence for health effect and evidence from clinical trials. An overview of potential molecular mechanisms underlying GLS biological effect is provided. The potential toxic or anti-nutritional effect has also been discussed.

RESULTS

Epidemiological and human in vivo evidence point towards a potential anti-cancer effect for sulforaphane, indole-3-carbinol and 3,3-diindolylmethane. A number of new human clinical trials are on-going and will likely shed further light on GLS protective effect towards cancer as well as other diseases. BPs biological effect is the results of a plurality of molecular mechanisms acting simultaneously which include modulation of xenobiotic metabolism, modulation of inflammation, regulation of apoptosis, cell cycle arrest, angiogenesis and metastasis and regulation of epigenetic events. BPs have been extensively investigated for their protective effect towards cancer but in recent years the interest also includes other diseases.

CONCLUSION

It appears that certain BPs may protect against and may even represent a therapeutic strategy against several forms of cancer. Whether this latter effect can be achieved through diet or supplements should be investigated more thoroughly.

Targeting DNA Methyltranferases in Urological Tumors

Urological cancers are a heterogeneous group of malignancies accounting for a considerable proportion of cancer-related morbidity and mortality worldwide. Aberrant epigenetic traits, especially altered DNA methylation patterns constitute a hallmark of these tumors. Nonetheless, these alterations are reversible, and several efforts have been carried out to design and test several epigenetic compounds that might reprogram tumor cell phenotype back to a normal state. Indeed, several DNMT inhibitors are currently under evaluation for therapeutic efficacy in clinical trials. This review highlights the critical role of DNA methylation in urological cancers and summarizes the available data on pre-clinical assays and clinical trials with DNMT inhibitors in bladder, kidney, prostate, and testicular germ cell cancers.

Fucoxanthin Elicits Epigenetic Modifications, Nrf2 Activation and Blocking Transformation in Mouse Skin JB6 P+ Cells

Nuclear factor erythroid-2-related factor-2 (Nrf2 or NFE2L2) is a master regulator of the anti-oxidative stress response, which is involved in the defense against many oxidative stress/inflammation-mediated diseases, including anticancer effects elicited by an increasing number of natural products. Our previous studies showed that the epigenetic modification of the Nrf2 gene plays a key role in restoring the expression of Nrf2. In this study, we aimed to investigate the epigenetic regulation of Nrf2 by astaxanthin (AST) and fucoxanthin (FX), carotenoids which are abundant in microalgae and seaweeds, in mouse skin epidermal JB6 P+ cells. FX induced the anti-oxidant response element (ARE)-luciferase and upregulated the mRNA and protein levels of Nrf2 and Nrf2 downstream genes in HepG2-C8 cells overexpressing the ARE-luciferase reporter. Both FX and AST decreased colony formation in 12-Otetradecanoylphorbol-13-acetate (TPA)-induced transformation of JB6 P+ cells. FX decreased the methylation of the Nrf2 promoter region in the JB6 P+ cells by the bisulfite conversion and pyrosequencing. Both FX and AST significantly reduced DNA methyltransferase (DNMT) activity but did not affect histone deacetylase (HDAC) activity in JB6 P+ cells. In summary, our results show that FX activates the Nrf2 signaling pathway, induces the epigenetic demethylation of CpG sites in Nrf2 and blocks the TPA-induced transformation of JB6 P+ cells, indicating the potential health-promoting effects of FX in skin cancer prevention.

Correction to: In Vitro-In Vivo Dose Response of Ursolic Acid, Sulforaphane, PEITC, and Curcumin in Cancer Prevention

The citation of the author name "Ah-Ng Tony Kong" in PubMed is not the author's preference. Instead of "Kong AT", the author prefers "Kong AN".

Establishment of prostate cancer spheres from a prostate cancer cell line after phenethyl isothiocyanate treatment and discovery of androgen-dependent reversible differentiation between sphere and neuroendocrine cells

Prostate cancer can transform from androgen-responsive to an androgen-independent phenotype. The mechanism responsible for the transformation remains unclear. We studied the effects of an epigenetic modulator, phenethyl isothiocyanate (PEITC), on the androgen-responsive LNCaP cells. After treatment with PEITC, floating spheres were formed with characteristics of prostate cancer stem cells (PCSC). These spheres were capable of self-renewal in media with and without androgen. They have been maintained in both types of media as long term cultures. Upon androgen deprivation, the adherent spheres differentiated to neuroendocrine cells (NEC) with decreased proliferation, expression of androgen receptor, and PSA. NEC reverse differentiated to spheres when androgen was replenished. The sphere cells expressed surface marker CD44 and had enhanced histone H3K4 acetylation, DNMT1 down-regulation and GSTP1 activation. We hypothesize that PEITC-mediated alteration in epigenomics of LNCaP cells may give rise to sphere cells, whereas reversible androgenomic alterations govern the shuttling between sphere PCSC and progeny NEC. Our findings identify unrecognized properties of prostate cancer sphere cells with multi-potential plasticity. This system will facilitate development of novel therapeutic agents and allow further exploration into epigenomics and androgenomics governing the transformation to hormone refractory prostate cancer.

In Vitro-In Vivo Dose Response of Ursolic Acid, Sulforaphane, PEITC, and Curcumin in Cancer Prevention

According to the National Center of Health Statistics, cancer was the culprit of nearly 600,000 deaths in 2016 in the USA. It is by far one of the most heterogeneous diseases to treat. Treatment for metastasized cancers remains a challenge despite modern diagnostics and treatment regimens. For this reason, alternative approaches are needed. Chemoprevention using dietary phytochemicals such as triterpenoids, isothiocyanates, and curcumin in the prevention of initiation and/or progression of cancer poses a promising alternative strategy. However, significant challenges exist in the extrapolation of in vitro cell culture data to in vivo efficacy in animal models and to humans. In this review, the dose at which these phytochemicals elicit a response in vitro and in vivo of a multitude of cellular signaling pathways will be reviewed highlighting Nrf2-mediated antioxidative stress, anti-inflammation, epigenetics, cytoprotection, differentiation, and growth inhibition. The in vitro-in vivo dose response of phytochemicals can vary due, in part, to the cell line/animal model used, the assay system of the biomarker used for the readout, chemical structure of the functional analog of the phytochemical, and the source of compounds used for the treatment study. While the dose response varies across different experimental designs, the chemopreventive efficacy appears to remain and demonstrate the therapeutic potential of triterpenoids, isothiocyanates, and curcumin in cancer prevention and in health in general.

Epigenetic reactivation of RASSF1A by phenethyl isothiocyanate (PEITC) and promotion of apoptosis in LNCaP cells

Epigenetic silencing of tumor suppressor genes is a phenomenon frequently observed in multiple cancers. Ras-association domain family 1 isoform A (RASSF1A) is a well-characterized tumor suppressor that belongs to the Ras-association domain family. Several studies have demonstrated that hypermethylation of the RASSF1A promoter is frequently observed in lung, prostate, and breast cancers. Phenethyl isothiocyanate (PEITC), a phytochemical abundant in cruciferous vegetables, possesses chemopreventive activities; however, its potential involvement in epigenetic mechanisms remains elusive. The present study aimed to examine the role of PEITC in the epigenetic reactivation of RASSF1A and the induction of apoptosis in LNCaP cells. LNCaP cells were treated for 5days with 0.01% DMSO, 2.5 or 5μM PETIC or 2.5μM azadeoxycytidine (5-Aza) with 0.5μM trichostatin A (TSA). We evaluated the effects of these treatments on CpG demethylation using methylation-specific polymerase chain reaction (MSP) and bisulfite genomic sequencing (BGS). CpG demethylation was significantly enhanced in cells treated with 5μM PEITC and 5-Aza+TSA; therefore, the latter treatment was used as a positive control in subsequent experiments. The decrease in RASSF1A promoter methylation correlated with an increase in expression of the RASSF1A gene in a dose-dependent manner. To confirm that promoter demethylation was mediated by DNA methyltransferases (DNMTs), we analyzed the expression levels of DNMTs and histone deacetylases (HDACs) at the gene and protein levels. PEITC reduced DNMT1, 3A and 3B protein levels in a dose-dependent manner, and 5μM PEITC significantly reduced DNMT3A and 3B protein levels. HDAC1, 2, 4 and 6 protein expression was also inhibited by 5μM PEITC. The combination of 5-Aza and TSA, a DNMT inhibitor and a HDAC inhibitor, respectively, was used as a positive control as this treatment significantly inhibited both HDACs and DNMTs. The function of RASSF1A reactivation in promoting apoptosis and inducing G2/M cell cycle arrest was analyzed using flow-cytometry analysis with Annexin V and propidium iodide (PI). Growth inhibition effect on LNCaP cells were investigated by colony formation assay. In addition, we analyzed p21, caspase-3 and 7, Bax, and Cyclin B1 protein levels. Flow-cytometry analysis of cells stained with PI alone demonstrated that 5μM PEITC promotes early apoptosis and G2/M cell cycle arrest. Flow cytometry analysis of cells stained with Annexin V and PI also demonstrated an increased proportion of cells in early apoptosis in cells treated with 5μM PEITC or 5-Aza with TSA. PEITC and efficiently inhibit colony numbers and total area. In addition, 5μM PEITC significantly enhanced p21, caspase-3, 7 and Bax levels and reduced Cyclin B1 expression compared with the control group. Collectively, the results of our study suggest that PEITC induces apoptosis in LNCaP cells potentially by reactivating RASSF1A via epigenetic mechanisms.

Phenethyl isothiocyanate (PEITC) suppresses prostate cancer cell invasion epigenetically through regulating microRNA-194

SCOPE

Tumor metastasis greatly contributes to the mortality of prostate cancer. The glucosinolate-derived phenethyl isothiocyanate (PEITC) has been widely documented to reduce the risk of prostate cancer by modulating multiple biologically relevant processes. Emerging evidence suggests that PEITC may exert its anti-cancer effects through epigenetic mechanisms including microRNAs. Altered levels of miRNA have been linked to tumor malignancy due to their capacity to regulate functional gene expression in carcinogenesis. Here, we assessed the effects of PEITC on miRNA expression which is related to PCa cell invasiveness.

METHODS AND RESULTS

Utilizing oligonucleotide microarray first identified the most affected miRNAs in LNCaP cells after PEITC treatment. Several top altered miRNAs were further validated using quantitative PCR. Interestingly, overexpression of miR-194 suppressed PC3 cell invasion in matrigel-coated Transwell chambers. Bone morphogenetic protein 1 (BMP1) was shown to be a direct target of miR-194. Downregulation of BMP1 by miR-194 or PEITC led to decreased expression of key oncogenic matrix metalloproteinases, MMP2 and MMP9. This in turn resulted in the suppression of tumor invasion.

CONCLUSION

Our results indicate that miR-194 downregulates the expression of oncogenic MMP2 and MMP9 by targeting BMP1, which suggests a potential new mechanistic target by which PEITC suppresses prostate cancer cell invasiveness.

Effects of Brassicaceae Isothiocyanates on Prostate Cancer

Despite the major progress made in the field of cancer biology, cancer is still one of the leading causes of mortality, and prostate cancer (PCa) is one of the most encountered malignancies among men. The effective management of this disease requires developing better anticancer agents with greater efficacy and fewer side effects. Nature is a large source for the development of chemotherapeutic agents, with more than 50% of current anticancer drugs being of natural origin. Isothiocyanates (ITCs) are degradation products from glucosinolates that are present in members of the family Brassicaceae. Although they are known for a variety of therapeutic effects, including antioxidant, immunostimulatory, anti-inflammatory, antiviral and antibacterial properties, nowadays, cell line and animal studies have additionally indicated the chemopreventive action without causing toxic side effects of ITCs. In this way, they can induce cell cycle arrest, activate apoptosis pathways, increase the sensitivity of resistant PCa to available chemodrugs, modulate epigenetic changes and downregulate activated signaling pathways, resulting in the inhibition of cell proliferation, progression and invasion-metastasis. The present review summarizes the chemopreventive role of ITCs with a particular emphasis on specific molecular targets and epigenetic alterations in in vitro and in vivo cancer animal models.

Dietary phytochemicals as epigenetic modifiers in cancer: Promise and challenges

The influence of diet and environment on human health has been known since ages. Plant-derived natural bioactive compounds (phytochemicals) have acquired an important role in human diet as potent antioxidants and cancer chemopreventive agents. In past few decades, the role of epigenetic alterations such as DNA methylation, histone modifications and non-coding RNAs in the regulation of mammalian genome have been comprehensively addressed. Although the effects of dietary phytochemicals on gene expression and signaling pathways have been widely studied in cancer, the impact of these dietary compounds on mammalian epigenome is rapidly emerging. The present review outlines the role of different epigenetic mechanisms in the regulation and maintenance of mammalian genome and focuses on the role of dietary phytochemicals as epigenetic modifiers in cancer. Above all, the review focuses on summarizing the progress made thus far in cancer chemoprevention with dietary phytochemicals, the heightened interest and challenges in the future.

Hypoacetylation, hypomethylation, and dephosphorylation of H2B histones and excessive histone deacetylase activity in DU-145 prostate cancer cells

Background

Hypoacetylation on histone H3 of human prostate cancer cells has been described. Little is known about the modifications of other histones from prostate cancer cells.

Methods

Histones were isolated from the prostate cancer cell line DU-145 and the non-malignant prostatic cell line RC170N/h. Post-translational modifications of histone H2B were determined by liquid chromatography-mass spectrometry (LC-MS)/MS.

Results

The histone H2B of the prostate cancer cell line DU-145 was found to have hypoacetylation, hypomethylation, and dephosphorylation as compared to the non-malignant prostatic cell line RC170N/h. H2B regained acetylation on multiple lysine residues, phosphorylation on Thr19, and methylation on Lys23 and Lys43 in the DU-145 cells after sodium butyrate treatment.

Conclusions

The histone H2B of DU-145 prostate cancer cells are hypoacetylated, hypomethylated, and dephosphorylated. Histone deacetylase inhibitor reversed this phenotype. Epigenetic agent may therefore be useful for prostate cancer therapy and worth further investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0233-x) contains supplementary material, which is available to authorized users.

Natural compound-derived epigenetic regulators targeting epigenetic readers, writers and erasers

Post-translational modifications can affect gene expression in a long-term manner without changes in the primary nucleotide sequence of the DNA. These epigenetic alterations involve dynamic processes that occur in histones, chromatin-associated proteins and DNA. In response to environmental stimuli, abnormal epigenetic alterations cause disorders in the cell cycle, apoptosis and other cellular processes and thus contribute to the incidence of diverse diseases, including cancers. In this review, we will summarize recent studies focusing on certain epigenetic readers, writers, and erasers associated with cancer development and how newly discovered natural compounds and their derivatives could interact with these targets. These advances provide insights into epigenetic alterations in cancers and the potential utility of these alterations as therapeutic targets for the future development of chemopreventive and chemotherapeutic drugs.

Polyphenols as Modulator of Oxidative Stress in Cancer Disease: New Therapeutic Strategies

Cancer onset and progression have been linked to oxidative stress by increasing DNA mutations or inducing DNA damage, genome instability, and cell proliferation and therefore antioxidant agents could interfere with carcinogenesis. It is well known that conventional radio-/chemotherapies influence tumour outcome through ROS modulation. Since these antitumour treatments have important side effects, the challenge is to develop new anticancer therapeutic strategies more effective and less toxic for patients. To this purpose, many natural polyphenols have emerged as very promising anticancer bioactive compounds. Beside their well-known antioxidant activities, several polyphenols target epigenetic processes involved in cancer development through the modulation of oxidative stress. An alternative strategy to the cytotoxic treatment is an approach leading to cytostasis through the induction of therapy-induced senescence. Many anticancer polyphenols cause cellular growth arrest through the induction of a ROS-dependent premature senescence and are considered promising antitumour therapeutic tools. Furthermore, one of the most innovative and interesting topics is the evaluation of efficacy of prooxidant therapies on cancer stem cells (CSCs). Several ROS inducers-polyphenols can impact CSCs metabolisms and self-renewal related pathways. Natural polyphenol roles, mainly in chemoprevention and cancer therapies, are described and discussed in the light of the current literature data.

Natural Compounds: DNA Methyltransferase Inhibitors in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a multistep process which is modulated by several endogenous and environmental factors. Epigenetic changes have been found to be equally responsible for OSCC as genetic changes. A plethora of genes showing hypermethylation have been discovered in OSCC. Since these changes are reversible, a lot of emphasis is on using the natural compounds for their ability to cause demethylation which could lead to reactivation of the inactivated tumor suppressor genes. This review encompasses the promoter hypermethylation of tumor suppressor genes in OSCC and its possible reversal using natural compounds. In addition, new compounds which could be screened for their demethylating ability have also been proposed.

Considering maternal dietary modulators for epigenetic regulation and programming of the fetal epigenome

Fetal life is characterized by a tremendous plasticity and ability to respond to various environmental and lifestyle factors, including maternal nutrition. Identification of the role of dietary factors that can modulate and reshape the cellular epigenome during development, including methyl group donors (e.g., folate, choline) and bioactive compounds (e.g., polyphenols) is of great importance; however, there is insufficient knowledge of a particular effect of each type of modulator and/or their combination on fetal life. To enhance the quality and safety of food products for proper fetal health and disease prevention in later life, a better understanding of the underlying mechanisms of dietary epigenetic modulators during the critical prenatal period is necessary. This review focuses on the influence of maternal dietary components on DNA methylation, histone modification, and microRNAs, and summarizes current knowledge of the effect and importance of dietary components on epigenetic mechanisms that control the proper expression of genetic information. Evidence reveals that some components in the maternal diet can directly or indirectly affect epigenetic mechanisms. Understanding the underlying mechanisms of how early-life nutritional environment affects the epigenome during development is of great importance for the successful prevention of adult chronic diseases through optimal maternal nutrition.

Epigenetic Regulation by Sulforaphane: Opportunities for Breast and Prostate Cancer Chemoprevention

Sulforaphane (SFN) is a phytochemical derived from cruciferous vegetables that has multiple molecular targets and anti-cancer properties. Researchers have demonstrated several chemopreventive benefits of SFN consumption, such as reductions in tumor growth, increases in cancer cell apoptosis, and disruption of signaling within tumor microenvironments both in vitro and in vivo. Emerging evidence indicates that SFN exerts several of its chemopreventive effects by altering epigenetic mechanisms. This review summarizes evidence of the impact of SFN on epigenetic events and how they relate to the chemopreventive effects of SFN observed in preclinical and clinical studies of breast and prostate cancers. Specific areas of focus include the role of SFN in the regulation of cell cycle, apoptosis, inflammation, antioxidant defense, and cancer cell signaling and their relationships to epigenetic mechanisms. Finally, remaining challenges and research needs for translating mechanistic work with SFN into human studies and clinical intervention trials are discussed.

The role dietary of bioactive compounds on the regulation of histone acetylases and deacetylases: a review

Nutrigenomics is an area of epigenomics that explores and defines the rapidly evolving field of diet-genome interactions. Lifestyle and diet can significantly influence epigenetic mechanisms, which cause heritable changes in gene expression without changes in DNA sequence. Nutrient-dependent epigenetic variations can significantly affect genome stability, mRNA and protein expression, and metabolic changes, which in turn influence food absorption and the activity of its constituents. Dietary bioactive compounds can affect epigenetic alterations, which are accumulated over time and are shown to be involved in the pathogenesis of age-related diseases such as diabetes, cancer, and cardiovascular disease. Histone acetylation is an epigenetic modification mediated by histone acetyl transferases (HATs) and histone deacetylases (HDACs) critically involved in regulating affinity binding between the histones and DNA backbone. The HDAC-mediated increase in histone affinity to DNA causes DNA condensation, preventing transcription, whereas HAT-acetylated chromatin is transcriptionally active. HDAC and HAT activities are reported to be associated with signal transduction, cell growth and death, as well as with the pathogenesis of various diseases. The aim of this review was to evaluate the role of diet and dietary bioactive compounds on the regulation of HATs and HDACs in epigenetic diseases. Dietary bioactive compounds such as genistein, phenylisothiocyanate, curcumin, resveratrol, indole-3-carbinol, and epigallocatechin-3-gallate can regulate HDAC and HAT activities and acetylation of histones and non-histone chromatin proteins, and their health benefits are thought to be attributed to these epigenetic mechanisms. The intake of dietary compounds that regulate epigenetic modifications can provide significant health effects and may prevent various pathological processes involved in the development of cancer and other life-threatening diseases.

Current Perspectives on Epigenetic Modifications by Dietary Chemopreventive and Herbal Phytochemicals

Studies during the last two decades have revealed the involvement of epigenetic modifications in the development of human cancer. It is now recognized that the interplay of DNA methylation, post-translational histone modification, and non-coding RNAs can interact with genetic defects to drive tumorigenesis. The early onset, reversibility, and dynamic nature of such epigenetic modifications enable them to be developed as promising cancer biomarkers and preventive/therapeutic targets. In addition to the recent approval of several epigenetic therapies in the treatment of human cancer, emerging studies have indicated that dietary phytochemicals might exert cancer chemopreventive effects by targeting epigenetic mechanisms. In this review, we will present the current understanding of the epigenetic alterations in carcinogenesis and highlight the potential of targeting these mechanisms to treat/prevent cancer. The latest findings, published in the past three years regarding the effects of dietary phytochemicals in modulating epigenetic mechanisms will also be discussed.

Dietary Glucosinolates Sulforaphane, Phenethyl Isothiocyanate, Indole-3-Carbinol/3,3'-Diindolylmethane: Anti-Oxidative Stress/Inflammation, Nrf2, Epigenetics/Epigenomics and In Vivo Cancer Chemopreventive Efficacy

Glucosinolates are a group of sulfur-containing glycosides found in many plant species, including cruciferous vegetables such as broccoli, cabbage, brussels sprouts, and cauliflower. Accumulating evidence increasingly supports the beneficial effects of dietary glucosinolates on overall health, including as potential anti-cancer agents, because of their role in the prevention of the initiation of carcinogenesis via the induction of cellular defense detoxifying/antioxidant enzymes and their epigenetic mechanisms, including modification of the CpG methylation of cancer-related genes, histone modification regulation and changes in the expression of miRNAs. In this context, the defense mechanism mediated by Nrf2-antioxidative stress and anti-inflammatory signaling pathways can contribute to cellular protection against oxidative stress and reactive metabolites of carcinogens. In this review, we summarize the cancer chemopreventive role of naturally occurring glucosinolate derivatives as inhibitors of carcinogenesis, with particular emphasis on specific molecular targets and epigenetic alterations in in vitro and in vivo human cancer animal models.

Epigenetic nutraceutical diets in Alzheimer's disease

There is growing support that environmental influences and individual genetic susceptibility may increase the incidence and accelerate the onset of Alzheimer's disease (AD). Epigenetic mechanisms encompass a complex regulatory network of modifications with considerable impact on health and disease risk. Abnormal epigenetic regulation is a hallmark in many pathological conditions including AD. It is well recognized that numerous bioactive dietary components mediate epigenetic modifications associated with the pathophysiology of several diseases. Although the influences of dietary factors on epigenetic regulation have been extensively investigated, only few studies have explored the effects of specific food components in regulating epigenetic patterns during neurodegeneration and AD. Epigenetic nutritional research has substantial potential for AD and may represent a window of opportunity to complement other interventions. Here, we provide a brief overview of the main mechanisms involved in AD, some of which may be epigenetically modulated by bioactive food.

Natural compounds in epigenetics: a current view

The successful treatment of many human diseases, including cancer, has come to be considered a major challenge, as patient response to therapy is difficult to predict. Recently, considerable efforts are being focused on the development of new tools to meet the growing demand for personalized medicine. With few exceptions, synthetic compounds have been unable to meet initial expectations for their clinical use. The last twenty years have been characterized by the failure of several drugs in advanced clinical development, possibly due to the insufficient understanding of molecular pathways underlying their mechanism of action. Although the biodiversity of compounds found in nature has been poorly explored until now, the field of naturally occurring drugs is rapidly expanding. Here, we review the current knowledge on the use of natural compounds with particular emphasis on those that display a chromatin remodeling effect coupled with anticancer action.

Cancer chemoprevention by traditional chinese herbal medicine and dietary phytochemicals: targeting nrf2-mediated oxidative stress/anti-inflammatory responses, epigenetics, and cancer stem cells

Excessive oxidative stress induced by reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive metabolites of carcinogens alters cellular homeostasis, leading to genetic/epigenetic changes, genomic instability, neoplastic transformation, and cancer initiation/progression. As a protective mechanism against oxidative stress, antioxidant/detoxifying enzymes reduce these reactive species and protect normal cells from endo-/exogenous oxidative damage. The transcription factor nuclear factor-erythroid 2 p45 (NF-E2)-related factor 2 (Nrf2), a master regulator of the antioxidative stress response, plays a critical role in the expression of many cytoprotective enzymes, including NAD(P)H:quinine oxidoreductase (NQO1), heme oxygenase-1 (HO-1), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST). Recent studies demonstrated that many dietary phytochemicals derived from various vegetables, fruits, spices, and herbal medicines induce Nrf2-mediated antioxidant/detoxifying enzymes, restore aberrant epigenetic alterations, and eliminate cancer stem cells (CSCs). The Nrf2-mediated antioxidant response prevents many age-related diseases, including cancer. Owing to their fundamental contribution to carcinogenesis, epigenetic modifications and CSCs are novel targets of dietary phytochemicals and traditional Chinese herbal medicine (TCHM). In this review, we summarize cancer chemoprevention by dietary phytochemicals, including TCHM, which have great potential as a safer and more effective strategy for preventing cancer.

Cancer chemoprevention: current state of the art

The aim of cancer chemoprevention is disruption or delay of the molecular pathways that lead to carcinogenesis. Chemopreventive blocking and/or suppressing agents disrupt the molecular mechanisms that drive carcinogenesis such as DNA damage by reactive oxygen species, increased signal transduction to NF-κB, epigenomic deregulation, and the epithelial mesenchymal transition that leads to metastatic progression. Numerous dietary phytochemicals have been observed to inhibit the initiation phase of carcinogenesis, and therefore are useful in primary chemoprevention. Moreover, phytochemicals are capable of interfering with the molecular mechanisms of metastasis. Likewise, numerous synthetic compounds are relevant and clinically viable as chemopreventive agents during the fundamental stages of carcinogenesis. While molecularly targeted anti-cancer therapies are in constant stages of development, superior patient outcomes are observed if carcinogenic processes are prevented altogether. This article reviews the role of chemopreventive compounds in inhibition of cancer initiation and their ability to reduce cancer progression.

Mitochondrial structure alteration in human prostate cancer cells upon initial interaction with a chemopreventive agent phenethyl isothiocyanate

Background

Phenethyl isothiocyanate (PEITC), present naturally in cruciferous vegetables, is a chemopreventive agent. It blocks initiation and post-initiation progression of carcinogenesis. Mechanism study in human prostate cancer cells revealed that PEITC is a dual inhibitor of aberrant DNA hypermethylation and histone deacetylases, reactivating silenced genes and regulating the androgen-mediated growth of tumor cells. The identity of the cellular organelle that initially interacts with PEITC has not been fully described.

Methods

Human prostate cancer LNCaP cells were exposed to PEITC and the effects on cellular fine structure examined by transmission electron microscopic studies. Alteration of mitochondrial membrane potential and cytochrome c release were evaluated as early events of apoptosis, and the TUNEL method for quantifying apoptotic cells. Mitochondria were isolated for determining their protein expression.

Results

Ultrastructural analyses have revealed condensed mitochondria and a perturbed mitochondrial cristae structure, which assumed a rounded and dilated shape within 4-hours of PEITC contact, and became more pronounced with longer PEITC exposure. They presented as the most prominent intracellular alterations in the early hours. Mitochondria structure alterations were demonstrated, for the first time, with the isothiocyanates. An increase in the number of smooth endoplasmic reticulum and vacuoles were also noted that is consistent with the presence of autophagy. Early events of apoptosis were detected, with cytochrome c released along with the appearance of mitochondrial alteration. Mitochondrial membrane potential was disrupted within 18 hours of PEITC exposure, preceding the appearance of apoptotic cells with DNA strand breaks. In parallel, the expression of the mitochondrial class III ß-tubulin in the outer membrane, which associates with the permeability transition pore, was significantly reduced as examined with isolated mitochondria.

Conclusion

Mitochondria may represent the organelle target of the isothiocyanates, indicating that the isothiocyanates may be mitochondria-interacting agents to inhibit carcinogenesis.

Phenethyl isothiocyanate and paclitaxel synergistically enhanced apoptosis and alpha-tubulin hyperacetylation in breast cancer cells

Combination of phenethyl isothiocyanate (PEITC) and paclitaxel (taxol) has been shown to work synergistically to increase apoptosis and cell cycle arrest in breast cancer cells. In this report, we further explored the mechanisms for the synergistic activity of PEITC and taxol in MCF7 and MDA-MB-231 (MB) breast cancer cell lines. By Western blotting analysis, treatment of MCF7 cells with both PEITC and taxol led to a 10.4-fold and 5.96-fold increase in specific acetylation of alpha-tubulin over single agent PEITC and taxol, respectively. This synergistic effect on acetylation of alpha-tubulin was also seen in MB cells. The combination of PEITC and taxol also reduced expressions of cell cycle regulator Cdk1, and anti-apoptotic protein bcl-2, enhanced expression of Bax and cleavage of PARP proteins. In conclusion, this study provided biochemical evidence for the mechanism of synergistic effect between the epigenetic agent PEITC and the chemotherapeutic agent taxol.

Health promoting effects of brassica-derived phytochemicals: from chemopreventive and anti-inflammatory activities to epigenetic regulation

A high intake of brassica vegetables may be associated with a decreased chronic disease risk. Health promoting effects of Brassicaceae have been partly attributed to glucosinolates and in particular to their hydrolyzation products including isothiocyanates. In vitro and in vivo studies suggest a chemopreventive activity of isothiocyanates through the redox-sensitive transcription factor Nrf2. Furthermore, studies in cultured cells, in laboratory rodents, and also in humans support an anti-inflammatory effect of brassica-derived phytochemicals. However, the underlying mechanisms of how these compounds mediate their health promoting effects are yet not fully understood. Recent findings suggest that brassica-derived compounds are regulators of epigenetic mechanisms. It has been shown that isothiocyanates may inhibit histone deacetylase transferases and DNA-methyltransferases in cultured cells. Only a few papers have dealt with the effect of brassica-derived compounds on epigenetic mechanisms in laboratory animals, whereas data in humans are currently lacking. The present review aims to summarize the current knowledge regarding the biological activities of brassica-derived phytochemicals regarding chemopreventive, anti-inflammatory, and epigenetic pathways.

Plant phytochemicals as epigenetic modulators: role in cancer chemoprevention

In recent years, "nutri-epigenetics," which focuses on the influence of dietary agents on epigenetic mechanism(s), has emerged as an exciting novel area in epigenetics research. Targeting of aberrant epigenetic modifications has gained considerable attention in cancer chemoprevention research because, unlike genetic changes, epigenetic alterations are reversible and occur during early carcinogenesis. Aberrant epigenetic mechanisms, such as promoter DNA methylation, histone modifications, and miRNA-mediated post-transcriptional alterations, can silence critical tumor suppressor genes, such as transcription factors, cell cycle regulators, nuclear receptors, signal transducers, and apoptosis-inducing and DNA repair gene products, and ultimately contribute to carcinogenesis. In an effort to identify and develop anticancer agents which cause minimal harm to normal cells while effectively killing cancer cells, a number of naturally occurring phytochemicals in food and medicinal plants have been investigated. This review highlights the potential role of plant-derived phytochemicals in targeting epigenetic alterations that occur during carcinogenesis, by modulating the activity or expression of DNA methyltransferases, histone modifying enzymes, and miRNAs. We present in detail the epigenetic mode of action of various phytochemicals and discuss their potential as safe and clinically useful chemopreventive strategies.

Phenethyl isothiocyanate inhibits androgen receptor-regulated transcriptional activity in prostate cancer cells through suppressing PCAF

SCOPE

Androgen receptor (AR) signaling is critical for all aspects of prostate growth and tumorigenesis. The glucosinolate-derived phenethyl isothiocyanate (PEITC) has recently been demonstrated to reduce the risk of prostate cancer (PCa) and inhibit PCa cell growth. We previously reported that p300/CBP-associated factor (PCAF), a co-regulator for AR, is upregulated in PCa cells through suppression of the mir-17 gene. Here, we assessed the effects of PEITC on PCAF expression and AR-regulated transcriptional activity in PCa cells.

METHODS AND RESULTS

Using AR-responsive LNCaP cells, we observed the inhibitory effects of PEITC on the dihydrotestosterone-stimulated AR transcriptional activity and cell growth of PCa cells. Interestingly, overexpression of PCAF attenuated the inhibitory effects of PEITC on dihydrotestosterone-stimulated AR transcriptional activity. Expression of PCAF was upregulated in PCa cells through suppression of miR-17. PEITC treatment significantly decreased PCAF expression and promoted transcription of miR-17 in LNCaP cells. Functional inhibition of miR-17 attenuated the suppression of PCAF in cells treated by PEITC.

CONCLUSION

Our results indicate that PEITC inhibits AR-regulated transcriptional activity and cell growth of PCa cells through miR-17-mediated suppression of PCAF, suggesting a new mechanism by which PEITC modulates PCa cell growth.

Epigenetic modifications by dietary phytochemicals: implications for personalized nutrition

In the last two decades, the study of epigenetic modification emerged as one of the major areas of cancer treatment targeted by dietary phytochemicals. Recent studies with various types of cancers revealed that the epigenetic modifications are associated with the food source corresponds to dietary phytochemicals. The dietary phytochemicals have been used in Asian countries for thousands of years to cure several diseases including cancer. They have been reported to modulate the several biological processes including histone modification, DNA methylation and non-coding microRNA expression. These events play a vital role in carcinogenesis. Various studies suggest that a number of dietary compounds present in vegetables, spices and other herbal products have epigenetic targets in cancer cells. Dietary phytochemicals have been reported to repair DNA damage by enhancing histone acetylation that helps to restrain cell death, and also alter DNA methylation. These phytochemicals are able to modulate epigenetic modifications and their targets to cure several cancers. Epigenetic aberrations dynamically contribute to cancer pathogenesis. Given the individualized traits of epigenetic biomarkers, the personalized nutrition will help us to prevent various types of cancer. In this review, we will discuss the effect of dietary phytochemicals on genetic and epigenetic modifications and how these modifications help to prevent various types of cancers and improve health outcomes.