Dietary phytochemicals, HDAC inhibition, and DNA damage/repair defects in cancer cells

Synergistic strategies: histone deacetylase inhibitors and platinum-based drugs in cancer therapy

INTRODUCTION

The synergistic combination of histone deacetylase inhibitors and platinum-based medicines represents a promising therapeutic strategy to efficacy and overcome drug resistance in cancer therapy, necessitating a comprehensive understanding on their molecular interactions and clinical potential.

AREAS COVERED

The objective of presented review is to investigate the molecular pathways of platinum medicines and HDAC inhibitors. A comprehensive literature review from 2011 to 2024 was conducted across multiple databases like MEDLINE, PubMed, Google Scholar, Science Direct, Scopus and official websites of ClinicalTrial.gov to explore publications on HDAC inhibitors, platinum drugs, and combination cancer therapies, revealing preliminary evidence of innovative treatment strategies involving HDAC inhibitors and platinum chemotherapeutics. Several new platinum (IV) complexes, with HDAC inhibitory moieties and better cytotoxicity profiles than conventional platinum drugs, are also reviewed here.

EXPERT OPINION

The above combination has great potential in cancer treatment, however managing toxicity, dosage regimens, and patient selection biomarkers are problematic. More selective HDAC inhibitors and innovative delivery techniques are potential areas for future research. An adaptation toward changing cancer therapeutic landscapes, highlights combining HDAC inhibitors with platinum-based medicines serves as a new concept for personalized medicine, however, a deeper research is still needed at this time.

Synergistic Mechanisms of Selected Polyphenols in Overcoming Chemoresistance and Enhancing Chemosensitivity in Colorectal Cancer

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. Despite significant advances in medical treatment, chemotherapy as monotherapy can lead to substantial side effects and chemoresistance. This underscores the need for therapeutic approaches that are not only pharmacologically safe but also modulate multiple potent signaling pathways and sensitize cancer cells to overcome resistance to standard drugs. In recent years, scientists have been searching for natural compounds that can be used as chemosensitizers in addition to conventional medications for the synergistic treatment of CRC. Polyphenols represent a diverse group of natural compounds that can target multiple signaling pathways in cancer cells to induce anti-cancer effects. Additionally, polyphenols have been shown to work synergistically with chemotherapeutics and other natural compounds in cancer cells. This review aims to provide a comprehensive insight into the synergistic mechanisms of selected polyphenols as chemosensitizers in CRC cells. Further research and clinical trials are warranted to fully harness the synergistic mechanisms of selected polyphenols combined with chemotherapy or natural compounds in improving cancer treatment outcomes.

Advances in targeting histone deacetylase for treatment of solid tumors

Histone deacetylase (HDAC) serves as a critical molecular regulator in the pathobiology of various malignancies and have garnered attention as a viable target for therapeutic intervention. A variety of HDAC inhibitors (HDACis) have been developed to target HDACs. Many preclinical studies have conclusively demonstrated the antitumor effects of HDACis, whether used as monotherapy or in combination treatments. On this basis, researchers have conducted various clinical studies to evaluate the potential of selective and pan-HDACis in clinical settings. In our work, we extensively summarized and organized current clinical trials, providing a comprehensive overview of the current clinical advancements in targeting HDAC therapy. Furthermore, we engaged in discussions about several clinical trials that did not yield positive outcomes, analyzing the factors that led to their lack of anticipated therapeutic effectiveness. Apart from the experimental design factors, issues such as toxicological side effects, tumor heterogeneity, and unexpected off-target effects also contributed to these less-than-expected results. These challenges have naturally become significant barriers to the application of HDACis. Despite these challenges, we believe that advancements in HDACi research and improvements in combination therapies will pave the way or lead to a broad and hopeful future in the treatment of solid tumors.

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Histone Acyl Code in Precision Oncology: Mechanistic Insights from Dietary and Metabolic Factors

Cancer etiology involves complex interactions between genetic and non-genetic factors, with epigenetic mechanisms serving as key regulators at multiple stages of pathogenesis. Poor dietary habits contribute to cancer predisposition by impacting DNA methylation patterns, non-coding RNA expression, and histone epigenetic landscapes. Histone post-translational modifications (PTMs), including acyl marks, act as a molecular code and play a crucial role in translating changes in cellular metabolism into enduring patterns of gene expression. As cancer cells undergo metabolic reprogramming to support rapid growth and proliferation, nuanced roles have emerged for dietary- and metabolism-derived histone acylation changes in cancer progression. Specific types and mechanisms of histone acylation, beyond the standard acetylation marks, shed light on how dietary metabolites reshape the gut microbiome, influencing the dynamics of histone acyl repertoires. Given the reversible nature of histone PTMs, the corresponding acyl readers, writers, and erasers are discussed in this review in the context of cancer prevention and treatment. The evolving 'acyl code' provides for improved biomarker assessment and clinical validation in cancer diagnosis and prognosis.

Antineoplastic activity of plant-derived compounds mediated through inhibition of histone deacetylase: a review

In the combat of treating cancer recent therapeutic approaches are focused towards enzymatic targets as they occupy a pivotal participation in the cascade of oncogenesis and malignancy. There are several enzymes that modulate the epigenetic pathways and chromatin structure related to cancer mutation. Among several epigenetic mechanisms such as methylation, phosphorylation, and sumoylation, acetylation status of histones is crucial and is governed by counteracting enzymes like histone acetyl transferase (HAT) and histone deacetylases (HDAC) which have contradictory effects on the histone acetylation. HDAC inhibition induces chromatin relaxation which forms euchromatin and thereby initiates the expression of certain transcription factors attributed with apoptosis, which are mostly correlated with the expression of the p21 gene and acetylation of H3 and H4 histones. Most of the synthetic and natural HDAC inhibitors elicit antineoplastic effect through activation of various apoptotic pathways and promoting cell cycle arrest at various phases. Due to their promising chemo preventive action and low cytotoxicity against normal host cells, bioactive substances like flavonoids, alkaloids, and polyphenolic compounds from plants have recently gained importance. Even though all bioactive compounds mentioned have an HDAC inhibitory action, some of them have a direct effect and others enhance the effects of the standard well known HDAC inhibitors. In this review, the action of plant derived compounds against histone deacetylases in a variety of in vitro cancer cell lines and in vivo animal models are articulated.

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.

An antioxidant ameliorates allergic airway inflammation by inhibiting HDAC 1 via HIF-1α/VEGF axis suppression in mice

Histone deacetylase inhibitors (HDACi) are novel class of drugs as they are involved in post translational modification of several proteins involved in signaling pathways related to asthma. HDACi have been reported to elicit protective effects on asthma but the signaling pathways associated with it have not been investigated much. Recently, we have demonstrated that intranasal administrations of Pan-HDAC inhibitors, sodium butyrate and curcumin, which have effectively reduced asthma severity via HDAC1 inhibition in Ovalbumin induced mouse model. Present study aimed to investigate possible pathways by which curcumin and sodium butyrate may minimize asthma pathogenesis via HDAC 1 inhibition. Balb/c mice were exposed (sensitized and challenged) with Ovalbumin to establish allergic asthma model followed by pretreatment of curcumin (5 mg/kg) and sodium butyrate (50 mg/kg) through intranasal route. Effects of curcumin and sodium butyrate on HIF-1α/VEGF signaling through activation of PI3K/Akt axis has been investigated using protein expressions followed by chromatin immunoprecipitation of BCL2 and CCL2 against HDAC1. Molecular docking analysis was also performed to investigate effects of curcumin and butyrate on mucus hypersecretion, goblet cell hyperplasia and airway hyperresponsiveness. Augmented expressions of HDAC-1, HIF-1α, VEGF, p-Akt and p-PI3K were observed in asthmatic group which was suppressed in both the treatments. NRF-2 level was significantly restored by curcumin and butyrate treatments. Protein expressions of p-p38, IL-5 and mRNA expressions of GATA-3 were also reduced in curcumin and butyrate treatment groups. Our findings suggest that curcumin and sodium butyrate may attenuate airway inflammation via down regulation of p-Akt/p-PI3K/HIF-1α/VEGF axis.

Thymoquinone, piperine, and sorafenib combinations attenuate liver and breast cancers progression: epigenetic and molecular docking approaches

BACKGROUND

Traditional herbal medicine has been used for centuries to cure many pathological disorders, including cancer. Thymoquinone (TQ) and piperine (PIP) are major bioactive constituents of the black seed (Nigella sativa) and black pepper (Piper nigrum), respectively. The current study aimed to explore the potential chemo-modulatory effects, mechanisms of action, molecular targets, and binding interactions after TQ and PIP treatments and their combination with sorafenib (SOR) against human triple-negative breast cancer (MDA-MB-231) and liver cancer (HepG2) cells.

METHODS

We determined drug cytotoxicity by MTT assay, cell cycle, and death mechanism by flow cytometry. Besides, the potential effect of TQ, PIP, and SOR treatment on genome methylation and acetylation by determination of DNA methyltransferase (DNMT3B), histone deacetylase (HDAC3) and miRNA-29c expression levels. Finally, a molecular docking study was performed to propose potential mechanisms of action and binding affinity of TQ, PIP, and SOR with DNMT3B and HDAC3.

RESULTS

Collectively, our data show that combinations of TQ and/or PIP with SOR have significantly enhanced the SOR anti-proliferative and cytotoxic effects depending on the dose and cell line by enhancing G2/M phase arrest, inducing apoptosis, downregulation of DNMT3B and HDAC3 expression and upregulation of the tumor suppressor, miRNA-29c. Finally, the molecular docking study has identified strong interactions between SOR, PIP, and TQ with DNMT3B and HDAC3, inhibiting their normal oncogenic activities and leading to growth arrest and cell death.

CONCLUSION

This study reported TQ and PIP as enhancers of the antiproliferative and cytotoxic effects of SOR and addressed the mechanisms, and identified molecular targets involved in their action.

Current Status of Obesity: Protective Role of Catechins

Obesity is a growing health concern in today's society. Current estimates indicate that obesity occurs in both adults and young people. Recent research also found that the Hispanic population in the U.S. is 1.9 times more likely to be overweight as compared to their non-Hispanic population. Obesity is a multifactorial disease that has a variety of causes. All current treatment options incorporate dietary changes aimed at establishing a negative energy balance. According to current scientific research, multiple factors are involved with the development of obesity, including genetic, biochemical, psychological, environmental, behavioral, and socio-demographic factors. The people who suffer from obesity are far more likely to suffer serious health problems, such as stroke, diabetes, lung disease, bone and joint disease, cancer, heart disease, neurological disorders, and poor mental health. Studies indicate that multiple cellular changes are implicated in the progression of obesity, mitochondrial dysfunction, deregulated microRNAs, inflammatory changes, hormonal deregulation, and others. This article highlights the role that oxidative stress plays in obesity and current obesity-prevention techniques with an emphasis on the impact of catechins to prevent and treat obesity.

Phytochemicals as Chemo-Preventive Agents and Signaling Molecule Modulators: Current Role in Cancer Therapeutics and Inflammation

Cancer is one of the deadliest non communicable diseases. Numerous anticancer medications have been developed to target the molecular pathways driving cancer. However, there has been no discernible increase in the overall survival rate in cancer patients. Therefore, innovative chemo-preventive techniques and agents are required to supplement standard cancer treatments and boost their efficacy. Fruits and vegetables should be tapped into as a source of compounds that can serve as cancer therapy. Phytochemicals play an important role as sources of new medication in cancer treatment. Some synthetic and natural chemicals are effective for cancer chemoprevention, i.e., the use of exogenous medicine to inhibit or impede tumor development. They help regulate molecular pathways linked to the development and spread of cancer. They can enhance antioxidant status, inactivating carcinogens, suppressing proliferation, inducing cell cycle arrest and death, and regulating the immune system. While focusing on four main categories of plant-based anticancer agents, i.e., epipodophyllotoxin, camptothecin derivatives, taxane diterpenoids, and vinca alkaloids and their mode of action, we review the anticancer effects of phytochemicals, like quercetin, curcumin, piperine, epigallocatechin gallate (EGCG), and gingerol. We examine the different signaling pathways associated with cancer and how inflammation as a key mechanism is linked to cancer growth.

Anti‑inflammatory effects of Nypa fruticans Wurmb via NF‑κB and MAPK signaling pathways in macrophages

The inflammatory defense response of macrophages is a natural protective reaction in the immune system. Antioxidant and anti-inflammatory activities are closely related. In addition, the cell signaling pathway regulating inflammation is associated with MAPK and NF-κB signaling pathway phosphorylation. The present study aimed to evaluate whether the ethyl acetate fraction from N. fruticans (ENF) has a modulatory role in the MAPK signaling pathway and inhibition of the IκB/NF-κB signaling pathways, including translocation of NF-κB p65. Antioxidant and anti-inflammatory activities are closely related. In addition, the cell signaling pathway regulating inflammation is associated with MAPK and NF-κB signaling pathway phosphorylation. The results revealed that ENF exhibited antioxidant capacity, attenuated the cytokine levels and blocked nitric oxide production. ENF downregulated cyclooxygenase-2 and inducible nitric oxide synthase expression. We hypothesized that ENF treatment alleviated the various proinflammatory mediators via IκB phosphorylation and transcription of NF-κB compared with the untreated control. In conclusion, the present study demonstrated that the inhibitory effect of ENF treatment was attributed to the inhibition of MAPK and Akt/IκB/NF-κB signaling pathways.

BRD9 Inhibition by Natural Polyphenols Targets DNA Damage/Repair and Apoptosis in Human Colon Cancer Cells

Epigenetic mechanisms play an important role in the etiology of colorectal cancer (CRC) and other malignancies due, in part, to deregulated bromodomain (BRD) functions. Inhibitors of the bromodomain and extraterminal (BET) family have entered into clinical trials as anticancer agents, and interest has grown in other acetyl 'reader' proteins as therapeutic targets, including non-BET member bromodomain-containing protein 9 (BRD9). We report here that overexpression of BRD9 is associated with poor prognosis in CRC patients, and that siRNA-mediated knockdown of BRD9 decreased cell viability and activated apoptosis in human colon cancer cells, coincident with increased DNA damage. Seeking natural compounds as BRD9 antagonists, molecular docking in silico identified several polyphenols such as Epigallocatechin-3-gallate (EGCG), Equol, Quercetin, and Aspalathin, with favorable binding energies, supported by BROMOscan^® (DiscoverX) and isothermal titration calorimetry experiments. Polyphenols mimicked BRD9 knockdown and iBRD9 treatment in reducing colon cancer cell viability, inhibiting colony formation, and enhancing DNA damage and apoptosis. Normal colonic epithelial cells were unaffected, signifying cancer-specific effects. These findings suggest that natural polyphenols recognize and target BRD9 for inhibition, and might serve as useful lead compounds for bromodomain therapeutics in the clinical setting.

GC/MS characterization and computational kinome-wide screening of pomegranate fruit extract identifies key phytochemicals interacting to CDK kinases implicated in acute myeloid leukemia cells

Punica granatum (Pomegranate fruit) and its constituents are proven effective against various cancer types. However, a kinome-wide screening for the active phytochemicals against kinases is not reported. This study aims in validating pomegranate fruit extract (PFE) against acute myeloid leukemia (AML) cells, and computationally identifying the phytochemicals interacting with active kinases. PFE was made with Soxhlet extractor using absolute ethanol. Gas-chromatography-mass spectroscopy (GC-MS) for phytochemical identification and MTT assay for cytotoxicity in AML (THP-1, TF-1 and HL-60) cells were performed. Apoptosis, CDK5 and CDK8 were assessed with flow cytometry. Kinase profiling was performed using In silico kinome screening. GC-MS analysis revealed 38 bioactive phytochemicals in PFE including pyrazoles, aldehydes, phenols, esters, pyranosides, and octadecadienoic acids. The extract inhibited the AML cell proliferations with GI₅₀ values of 195.5 μg/ml, 289.1 μg/ml, and 353.5 μg/ml in THP-1, THP-1, and HL-60 cells, respectively. PFE also exhibited a dose-responsive increase in apoptotic cell populations when treated to the AML cells. Computational screening and modeling predicted three critical constituents, viz., Deoxyartemisinin, 3-Methyl-3-phenyl-3H-indazole, and 8-fluoro-5,6-dimethoxy-3,4-dihydro-2H-naphthalen-1-one of pomegranate extract to interact mainly with cyclin-dependent kinases, including CDK5 and CDK8. Proteinand ligand docking predicted binding energies, and binding pose for top candidate lead molecules. In vitro assay exhibited the anticancer properties of PFE in AML cells. Computational kinome screening predicted top three PFE constituents targeting CDKs which may be responsible for the demonstrated anticancer efficacy of the extract against AML. This hypothesis further aligned with observed efficacy of PFE to inhibit CDK5 and CDK8 in all AML cells tested. PRACTICAL APPLICATIONS: Though Punica granatum (Pomegranate fruit) and its constituents are proven effective against various cancer types, a kinome-wide screening for the active phytochemicals against kinases is not reported. In this study, we have conducted GC/MS characterization of the active phytochemicals of PFE and have performed a kinome-wide screening for all the 38 identified compounds toward 310 active kinases commonly expressed in cancers. These observations warrant isolation and further evaluation of these phytochemicals or their analogues as effective CDK inhibitors against AML proliferation. Further, the computational methods used in this study will throw light on literature for new options of kinome panel screening of active phytochemicals or small molecules.

Redox signaling, mitochondrial metabolism, epigenetics and redox active phytochemicals

Biological redox signaling plays an important role in many diseases. Redox signaling involves reductive and oxidative mechanisms. Oxidative stress occurs when reductive mechanism underwhelms oxidative challenges. Cellular oxidative stress occurs when reactive oxygen/nitrogen species (RO/NS) exceed the cellular reductive/antioxidant capacity. Endogenously produced RO/NS from mitochondrial metabolic citric-acid-cycle coupled with electron-transport-chain or exogenous stimuli trigger cellular signaling events leading to homeostatic response or pathological damage. Recent evidence suggests that RO/NS also modulate epigenetic machinery driving gene expression. RO/NS affect DNA methylation/demethylation, histone acetylation/deacetylation or histone methylation/demethylation. Many health beneficial phytochemicals possess redox capability that counteract RO/NS either by directly scavenging the radicals or via inductive mechanism of cellular defense antioxidant/reductive enzymes. Amazingly, these phytochemicals also possess epigenetic modifying ability. This review summarizes the latest advances on the interactions between redox signaling, mitochondrial metabolism, epigenetics and redox active phytochemicals and the future challenges of integrating these events in human health.

Oxidative stress-mediated beta cell death and dysfunction as a target for diabetes management

The biggest drawback of a current diabetes therapy is the treatment of the consequences not the cause of the disease. Regardless of the diabetes type, preservation and recovery of functional pancreatic beta cells stands as the biggest challenge in the treatment of diabetes. Free radicals and oxidative stress are among the major mediators of autoimmune destruction of beta cells in type 1 diabetes (T1D) or beta cell malfunction and death provoked by glucotoxicity and insulin resistance in type 2 diabetes (T2D). Additionally, oxidative stress reduces functionality of beta cells in T2D by stimulating their de-/trans-differentiation through the loss of transcription factors critical for beta cell development, maturity and regeneration. This review summarizes up to date clarified redox-related mechanisms involved in regulating beta cell identity and death, underlining similarities and differences between T1D and T2D. The protective effects of natural antioxidants on the oxidative stress-induced beta cell failure were also discussed. Considering that oxidative stress affects epigenetic regulatory mechanisms involved in the regulation of pancreatic beta cell survival and insulin secretion, this review highlighted huge potential of epigenetic therapy. Special attention was paid on application of the state-of-the-art CRISPR/Cas9 technology, based on targeted epigenome editing with the purpose of changing the differentiation state of different cell types, making them insulin-producing with ability to attenuate diabetes. Clarification of the above-mentioned mechanisms could provide better insight into diabetes etiology and pathogenesis, which would allow development of novel, potentially more efficient therapeutic strategies for the prevention or reversion of beta cell loss.

Molecular Targets of Natural Compounds with Anti-Cancer Properties

Cancer is the second leading cause of death in humans. Despite rapid developments in diagnostic methods and therapies, metastasis and resistance to administrated drugs are the main obstacles to successful treatment. Therefore, the main challenge should be the diagnosis and design of optimal therapeutic strategies for patients to increase their chances of responding positively to treatment and increase their life expectancy. In many types of cancer, a deregulation of multiple pathways has been found. This includes disturbances in cellular metabolism, cell cycle, apoptosis, angiogenesis, or epigenetic modifications. Additionally, signals received from the microenvironment may significantly contribute to cancer development. Chemical agents obtained from natural sources seem to be very attractive alternatives to synthetic compounds. They can exhibit similar anti-cancer potential, usually with reduced side effects. It was reported that natural compounds obtained from fruits and vegetables, e.g., polyphenols, flavonoids, stilbenes, carotenoids and acetogenins, might be effective against cancer cells in vitro and in vivo. Several published results indicate the activity of natural compounds on protein expression by its influence on transcription factors. They could also be involved in alterations in cellular response, cell signaling and epigenetic modifications. Such natural components could be used in our diet for anti-cancer protection. In this review, the activities of natural compounds, including anti-cancer properties, are described. The influence of natural agents on cancer cell metabolism, proliferation, signal transduction and epigenetic modifications is highlighted.

Roles of Therapeutic Bioactive Compounds in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is due to poor prognosis and lack of availability of effective treatment. Novel therapeutic strategies will be the fine tuning of intracellular ROS signaling to effectively deprive cells of ROS-induced tumor-promoting events. This review discusses the generation of ROS, the major signaling their modulation in therapeutics. We explore some of the major pathways involved in HCC, which include the VEGF, MAPK/ERK, mTOR, FGF, and Ser/Thr kinase pathways. In this review, we study cornerstone on natural bioactive compounds with their effect on hepatocarcinomas. Furthermore, we focus on oxidative stress and FDA-approved signaling pathway inhibitors, along with chemotherapy and radiotherapy enhancers which with early evidence of success. While more in vivo testing is required to confirm the findings presented here, our findings will aid future nonclinical, preclinical, and clinical studies with these compounds, as well as inspire medicinal chemistry scientists to conduct appropriate research on this promising natural compound and their derivatives.

Role of mismatch repair in aging

A common feature of aging is the accumulation of genetic damage throughout life. DNA damage can lead to genomic instability. Many diseases associated with premature aging are a result of increased accumulation of DNA damage. In order to minimize these damages, organisms have evolved a complex network of DNA repair mechanisms, including mismatch repair (MMR). In this review, we detail the effects of MMR on genomic instability and its role in aging emphasizing on the association between MMR and the other hallmarks of aging, serving to drive or amplify these mechanisms. These hallmarks include telomere attrition, epigenetic alterations, mitochondrial dysfunction, altered nutrient sensing and cell senescence. The close relationship between MMR and these markers may provide prevention and treatment strategies, to reduce the incidence of age-related diseases and promote the healthy aging of human beings.

Apoptotic mechanisms of gastric cancer cells induced by isolated erinacine S through epigenetic histone H3 methylation of FasL and TRAIL

Erinacine S, the new bioactive diterpenoid compound isolated from the ethanol extract of the mycelia of Hericium erinaceus, displays great health-promoting properties. However, the effects of erinacine S on inductive apoptosis in cancer cells such as gastric cancer and its molecular mechanisms remain unclear. Our results demonstrated that erinacine S treatment significantly induces cell apoptosis with increased ROS production in gastric cancer cells, but not in normal cells. Significantly, erinacine S also showed its inhibitory effects on tumor growth in an in vivo xenograft mouse model. Furthermore, immunohistochemical analyses revealed that erinacine S treatment significantly increases the FasL and TRAIL protein, whereas it decreases the levels of PCNA and cyclin D1 in the gastric cancer xenograft mice. Consistently, in AGS cells, erinacine S treatment not only triggers the activation of extrinsic apoptosis pathways (TRAIL, Fas-L and caspase-8, -9, -3), but it also suppresses the expression of the anti-apoptotic molecules Bcl-2 and Bcl-XL in a time-dependent manner. In addition, erinacine S also causes cell cycle G1 arrest by the inactivation of CDKs/cyclins. Moreover, our data revealed that activation of the ROS-derived and AKT/FAK/PAK1 pathways is involved in the erinacine S-mediated transcriptional activation of Fas-L and TRAIL through H3K4 trimethylation on their promoters. Together, this study sheds light on the anticancer effects of erinacine S on gastric cancer and its molecular mechanism in vitro and in vivo.

Differential effects of cisplatin combined with the flavonoid apigenin on HepG2, Hep3B, and Huh7 liver cancer cell lines

The potential of apigenin (APG) to enhance cisplatin's (CDDP) chemotherapeutic efficacy was investigated in HepG2, Hep3B, and Huh7 liver cancer cell lines. The presence of 20 μM APG sensitized all cell lines to CDDP treatment (degree of sensitization based on the MTT assay: HepG2>Huh7>Hep3B). As reflected by sister chromatid exchange levels, the degree of genetic instability as well as DNA repair by homologous recombination differed among cell lines. CDDP and 20 μM APG cotreatment exhibited a synergistic genotoxic effect on Hep3B cells and a less than additive effect on HepG2 and Huh7 cells. Cell cycle delays were noticed during the first mitotic division in Hep3B and Huh7 cells and the second mitotic division in HepG2 cells. CDDP and CDDP + APG treatments reduced the clonogenic capacity of all cell lines; however, there was a discordance in drug sensitivity compared with the MMT assay. Furthermore, a senescence-like phenotype was induced, especially in Hep3B and Huh7 cells. Unlike CDDP monotherapy, the combined treatment exhibited a significant anti-invasive and anti-migratory action in all cancer cell lines. The fact that the three liver cancer cell lines responded differently, yet positively, to CDDP + APG cotreatment could be attributed to variations they present in gene expression. Complex mechanisms seem to influence cellular responses and cell fate.

Deacetylase Plus Bromodomain Inhibition Downregulates ERCC2 and Suppresses the Growth of Metastatic Colon Cancer Cells

There is growing evidence that DNA repair factors have clinical value for cancer treatment. Nucleotide excision repair (NER) proteins, including excision repair cross-complementation group 2 (ERCC2), play a critical role in maintaining genome integrity. Here, we examined ERCC2 expression following epigenetic combination drug treatment. Attention was drawn to ERCC2 for three reasons. First, from online databases, colorectal cancer (CRC) patients exhibited significantly reduced survival when ERCC2 was overexpressed in colon tumors. Second, ERCC2 was the most highly downregulated RNA transcript in human colon cancer cells, plus Ercc2 in rat tumors, after treatment with the histone deacetylase 3 (HDAC3) inhibitor sulforaphane (SFN) plus JQ1, which is an inhibitor of the bromodomain and extraterminal domain (BET) family. Third, as reported here, RNA-sequencing of polyposis in rat colon (Pirc) polyps following treatment of rats with JQ1 plus 6-methylsulfinylhexyl isothiocyanate (6-SFN) identified Ercc2 as the most highly downregulated gene. The current work also defined promising second-generation epigenetic drug combinations with enhanced synergy and efficacy, especially in metastasis-lineage colon cancer cells cultured as 3D spheroids and xenografts. This investigation adds to the growing interest in combination approaches that target epigenetic 'readers', 'writers', and 'erasers' that are deregulated in cancer and other pathologies, providing new avenues for precision oncology and cancer interception.

Metabolic Reprogramming by Reduced Calorie Intake or Pharmacological Caloric Restriction Mimetics for Improved Cancer Immunotherapy

Caloric restriction and fasting have been known for a long time for their health- and life-span promoting effects, with coherent observations in multiple model organisms as well as epidemiological and clinical studies. This holds particularly true for cancer. The health-promoting effects of caloric restriction and fasting are mediated at least partly through their cellular effects-chiefly autophagy induction-rather than reduced calorie intake per se. Interestingly, caloric restriction has a differential impact on cancer and healthy cells, due to the atypical metabolic profile of malignant tumors. Caloric restriction mimetics are non-toxic compounds able to mimic the biochemical and physiological effects of caloric restriction including autophagy induction. Caloric restriction and its mimetics induce autophagy to improve the efficacy of some cancer treatments that induce immunogenic cell death (ICD), a type of cellular demise that eventually elicits adaptive antitumor immunity. Caloric restriction and its mimetics also enhance the therapeutic efficacy of chemo-immunotherapies combining ICD-inducing agents with immune checkpoint inhibitors targeting PD-1. Collectively, preclinical data encourage the application of caloric restriction and its mimetics as an adjuvant to immunotherapies. This recommendation is subject to confirmation in additional experimental settings and in clinical trials. In this work, we review the preclinical and clinical evidence in favor of such therapeutic interventions before listing ongoing clinical trials that will shed some light on this subject.

Targeting Epigenetic 'Readers' with Natural Compounds for Cancer Interception

Natural compounds from diverse sources, including botanicals and commonly consumed foods and beverages, exert beneficial health effects via mechanisms that impact the epigenome and gene expression during disease pathogenesis. By targeting the so-called epigenetic 'readers', 'writers', and 'erasers', dietary phytochemicals can reverse abnormal epigenome signatures in cancer cells and preneoplastic stages. Thus, such agents provide avenues for cancer interception via prevention or treatment/therapeutic strategies. To date, much of the focus on dietary agents has been directed towards writers (e.g., histone acetyltransferases) and erasers (e.g., histone deacetylases), with less attention given to epigenetic readers (e.g., BRD proteins). The drug JQ1 was developed as a prototype epigenetic reader inhibitor, selectively targeting members of the bromodomain and extraterminal domain (BET) family, such as BRD4. Clinical trials with JQ1 as a single agent, or in combination with standard of care therapy, revealed antitumor efficacy but not without toxicity or resistance. In pursuit of second-generation epigenetic reader inhibitors, attention has shifted to natural sources, including dietary agents that might be repurposed as 'JQ1-like' bioactives. This review summarizes the current status of nascent research activity focused on natural compounds as inhibitors of BET and other epigenetic 'reader' proteins, with a perspective on future directions and opportunities.

Fluorescence Detection of Type III Secretion Using a Glu-CyFur Reporter System in Citrobacter rodentium

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea worldwide. EPEC and the closely related murine model of EPEC infection, Citrobacter rodentium, utilize a type III secretion system (T3SS) to propagate the infection. Since the T3SS is not essential for the bacteria to survive or propagate, inhibiting the virulence factor with a therapeutic would treat the infection without causing harm to commensal bacteria. Studying inhibitors of the T3SS usually requires a BSL-2 laboratory designation and eukaryotic host cells while not indicating the mechanism of inhibition. We have designed a BSL-1 assay using the murine model C. rodentium that does not require mammalian cell culture. This CPG2-reporter assay allows for more rapid analysis of secretion efficiency than Western blotting and is sensitive enough to differentiate between partial and total inhibition of the T3SS. Here we present our method and the results of a small collection of compounds we have screened, including known T3SS inhibitors EGCG, regacin, and aurodox and related quorum sensing inhibitors tannic acid and ellagic acid. We have further characterized EGCG as a T3SS inhibitor and established its IC₅₀ of 1.8 ± 0.4 μM. We also establish tannic acid as a potent inhibitor of the T3SS with an IC₅₀ of 0.65 ± 0.09 μM.

Dual mTOR/DNA-PK Inhibitor CC-115 Induces Cell Death in Melanoma Cells and Has Radiosensitizing Potential

CC-115 is a dual inhibitor of the mechanistic target of rapamycin (mTOR) kinase and the DNA-dependent protein kinase (DNA-PK) that is currently being studied in phase I/II clinical trials. DNA-PK is essential for the repair of DNA-double strand breaks (DSB). Radiotherapy is frequently used in the palliative treatment of metastatic melanoma patients and induces DSBs. Melanoma cell lines and healthy-donor skin fibroblast cell lines were treated with CC‑115 and ionizing irradiation (IR). Apoptosis, necrosis, and cell cycle distribution were analyzed. Colony forming assays were conducted to study radiosensitizing effects. Immunofluorescence microscopy was performed to determine the activity of homologous recombination (HR). In most of the malign cell lines, an increasing concentration of CC-115 resulted in increased cell death. Furthermore, strong cytotoxic effects were only observed in malignant cell lines. Regarding clonogenicity, all cell lines displayed decreased survival fractions during combined inhibitor and IR treatment and supra-additive effects of the combination were observable in 5 out of 9 melanoma cell lines. CC-115 showed radiosensitizing potential in 7 out of 9 melanoma cell lines, but not in healthy skin fibroblasts. Based on our data CC-115 treatment could be a promising approach for patients with metastatic melanoma, particularly in the combination with radiotherapy.

Novel regulator role of CIL-102 in the epigenetic modification of TNFR1/TRAIL to induce cell apoptosis in human gastric cancer

CIL-102 (1-[4-(furo [2,3-b]quinolin-4-ylamino)phenyl]ethanone) is a major active agent and an alkaloid derivative of Camptotheca acuminata, which has valuable biological properties, including anti-tumorigenic activity. However, the molecular mechanisms of CIL-102 related to inductive apoptosis in human gastric cancer remain unclear. By using diphenyltetrazolium bromide (MTT), annexin-V-fluorescein-isothiocyanate (FITC)/propidium iodide staining and a 2',7' -dichlorofluorescin diacetate (DCFDA), a Fluo-3 fluorescence staining assay, the cell death and cell viability in gastric cancer cells and an in vivo xenograft mouse model, with or without the addition of CIL-102, were measured, respectively. Furthermore, signaling pathways and apoptotic molecules were also detected by western blots and an immunohistochemical assay. Our results demonstrated that CIL-102 treatment significantly induced the cell apoptosis of gastric cancer cells, along with increased ROS production and increased intracellular Ca2+ levels. In addition, through the inactivation of CDK1/cyclin B1, CIL-102 treatment induced the cell cycle G2/M arrest of gastric cancer cells. Moreover, our data revealed that multiple signaling pathways were involved in the H3K4 trimethylation of TNFR1 and TRAIL proteins by CIL-102, including ROS-derived and JNK/mTOR/p300 pathways in gastric cancer AGS cells. The CIL-102 treatment also consistently inhibited tumor growth and increased tumor apoptosis, as measured by TUNEL assay in an in vivo xenograft mouse model. An immunohistochemical analysis revealed that the upregulation of the TNFR1 and TRAIL proteins and the downregulation of PCNA and CDK1 proteins were found in the CIL-102-treated gastric cancer xenograft mouse model, compared to that of the saline control. Together, this study sheds light on the novel mechanism associated with CIL-102 for inducing gastric cancer apoptosis.

Caloric restriction mimetics for the treatment of cardiovascular diseases

Caloric restriction mimetics (CRMs) are emerging as potential therapeutic agents for the treatment of cardiovascular diseases. CRMs include natural and synthetic compounds able to inhibit protein acetyltransferases, to interfere with acetyl coenzyme A biosynthesis, or to activate (de)acetyltransferase proteins. These modifications mimic the effects of caloric restriction, which is associated with the activation of autophagy. Previous evidence demonstrated the ability of CRMs to ameliorate cardiac function and reduce cardiac hypertrophy and maladaptive remodelling in animal models of ageing, mechanical overload, chronic myocardial ischaemia, and in genetic and metabolic cardiomyopathies. In addition, CRMs were found to reduce acute ischaemia-reperfusion injury. In many cases, these beneficial effects of CRMs appeared to be mediated by autophagy activation. In the present review, we discuss the relevant literature about the role of different CRMs in animal models of cardiac diseases, emphasizing the molecular mechanisms underlying the beneficial effects of these compounds and their potential future clinical application.

CANCER EPIGENETICS AND THE ROLE OF DIETARY ELEMENTS

Cancer has been a fatal disease since many decades. Over the time, it is presented in multiple ways and is a matter of consideration as accounts for the high rate of mortality. The aim of the current review was to focus on the genetics, epigenetics factors and role of medicinal plants for the cure of this inimical disease. Related articles available in English language (2002-2018) were reviewed with help of different database, including PubMed, Springer Link, Medline, Google Scholar and ScienceDirect. In order to ensure credibility and accuracy of data only those articles were considered which are published in indexed journals i.e. Web of Science and Scopus. This project was conducted at the Department of Pharmacy, Government College University, Faisalabad, Pakistan from 02-01-2019 to 28-02-2019. The genetic machinery is vibrantly involved in the interpretation of the signals and is observed to be affected by various dietary factors. A sequence of modified activities is observed with use of these dietary elements. However, the modification is reviewed through the histone acetyltransferase (HAT), histone deacetylase (HDAC) and DNA methyl transferase (DNMTs), effecting the expression of gene. These modified genes, in turn then express the signals in multiple reformed ways. Different dietary elements that are used such as polyphenol, alkaloid and flavonoids are effective against cancer. The progression of disease involves genetics and epigenetics due to amplification, translocation and mutation during gene expression. Though, many studies have been conducted elaborating the role of plants and their ingredients which play a part in inhibition of cancerous cells by blockade of cell cycle and apoptosis; more in-depth investigations are still required to identify the new drug target and novel therapeutic modalities.

Gallic acid, a phenolic acid, hinders the progression of prostate cancer by inhibition of histone deacetylase 1 and 2 expression

Gallic acid (GA) is known to possess diverse biological activities, including anticancer. Histone deacetylase (HDACs) are controlled by tumor suppressor gene transcription and are overexpressed in various tumors, resulting in tumor development, progression and poor prognosis. This study aims to demonstrate the effect of GA on inhibition of prostate cancer (PCa) progression by modulating the expression of HDAC1 and 2 in PCa cells. To prove our research rationale, we used diverse experimental methods. GA decreased the cell viability of only PCa cell lines and not normal cells (contrary to another HDAC inhibitor, suberoylanilide hydroxamic acid) and also inhibited colony and tumor spheroid formation. Exposure to GA decreased the mitochondrial membrane potential (ΔΨm), increased the number of apoptotic cells and induced DNA fragmentation. Western blot analysis revealed down-regulated expression of HDAC1 and 2, leading to up-regulation of acetyl-p53 expression at the protein level, subsequent to down-regulating the expression of cell-cycle-related genes, i.e., proliferating cell nuclear antigen (PCNA), Cyclin D1 and E1, up-regulating the expression of cell cycle arrest gene p21 and regulating the expression of apoptosis intrinsic pathway-related genes, such as Bax, Bcl-2, cleaved Caspase-3 and poly (ADP-ribose) polymerase 1 in both PCa cell lines. Furthermore, oral administration of GA for 8 weeks on PC-3 cells-derived tumor xenograft mice model decreases the tumor size, damages the tumor structure and down-regulates the expression of HDAC1 and 2 and PCNA in tumor mass, as confirmed by histological analysis. These results indicated that GA may hinder the PCa progression by inhibiting HDAC1 and 2 expression, thereby demonstrating the potential of GA to be used as HDACs inhibitor and anti-PCa therapeutics.

Genoprotective activities of plant natural substances in cancer and chemopreventive strategies in the context of 3P medicine

Severe durable changes may occur to the DNA structure caused by exogenous and endogenous risk factors initiating the process of carcinogenesis. By evidence, a large portion of malignancies have been demonstrated as being preventable. Moreover, the targeted prevention of cancer onset is possible, due to unique properties of plant bioactive compounds. Although genoprotective effects of phytochemicals have been well documented, there is an evident lack of articles which would systematically present the spectrum of anticancer effects by phytochemicals, plant extracts, and plant-derived diet applicable to stratified patient groups at the level of targeted primary (cancer development) and secondary (cancer progression and metastatic disease) prevention. Consequently, clinical implementation of knowledge accumulated in the area is still highly restricted. To stimulate coherent co-development of the dedicated plant bioactive compound investigation on one hand and comprehensive cancer preventive strategies on the other hand, the current paper highlights and deeply analyses relevant evidence available in the area. Key molecular mechanisms are presented to detail genoprotective and anticancer activities of plants and phytochemicals. Clinical implementation is discussed. Based on the presented evidence, advanced chemopreventive strategies in the context of 3P medicine are considered.

Targeting epigenetics in cancer: therapeutic potential of flavonoids

Irrespective of sex and age, cancer is the leading cause of mortality around the globe. Therapeutic incompliance, unwanted effects, and economic burdens imparted by cancer treatments, are primary health challenges. The heritable features in gene expression that are propagated through cell division and contribute to cellular identity without a change in DNA sequence are considered epigenetic characteristics and agents that could interfere with these features and are regarded as potential therapeutic targets. The genetic modification accounts for the recurrence and uncontrolled changes in the physiology of cancer cells. This review focuses on plant-derived flavonoids as a therapeutic tool for cancer, attributed to their ability for epigenetic regulation of cancer pathogenesis. The epigenetic mechanisms of various classes of flavonoids including flavonols, flavones, isoflavones, flavanones, flavan-3-ols, and anthocyanidins, such as cyanidin, delphinidin, and pelargonidin, are discussed. The outstanding results of preclinical studies encourage researchers to design several clinical trials on various flavonoids to ascertain their clinical strength in the treatment of different cancers. The results of such studies will define the clinical fate of these agents in future.

Resveratrol decreases cell apoptosis through inhibiting DNA damage in bronchial epithelial cells

One of the major risk factors for asthma development is exposure to environmental allergens. House dust mites (HDM) can induce DNA damage, resulting in asthma. Resveratrol (RES) produced by several plants, has anti‑apoptotic properties and may affect a variety of biological processes. The aim of the present study was to investigate the protective role of RES against apoptosis in bronchial epithelial cells. C57BL/6J mice treated with HDM exhibited high levels of cell apoptosis, while RES significantly reversed this process. Induced DNA damage was more severe in the HDM group vs. the HDM combined with RES group. This result was confirmed by immunostaining and western blot analysis of the protein expression of the DNA damage‑related gene γH2AX, which was highly induced by HDM. In addition, treatment with RES protected bronchial epithelial cells exposed to HDM from DNA damage. RES decreases reactive oxygen species levels to inhibit oxidative DNA damage in bronchial epithelial cells. Furthermore, compared with the HDM group, induced cell apoptosis could be attenuated by RES in the group of combined treatment with RES and HDM. A DNA repair inhibitor augmented DNA damage and apoptosis in bronchial epithelial cells, whereas RES significantly attenuated cell apoptosis through inhibiting DNA damage.

Antitumoral effects of [6]-gingerol [(S)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-3-decanone] in sarcoma 180 cells through cytogenetic mechanisms

BACKGROUND

[6]-Gingerol [(S)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-3-decanone] is a phenolic substance reported for several ethnopharmacological usage by virtue of its antioxidant, antiemetic, anti-inflammatory and anticancer properties. This study assessed the antitumoral effects of [6]-Gingerol in primary cells of Sarcoma 180 as well as in peripheral blood lymphocytes of mice.

METHODS

The effect of [6]-Gingerol was assessed by applying cytogenetic biomarkers as indicative of genotoxicity, mutagenicity and apoptosis. Ascitic liquid cells were treated with [6]-Gingerol at concentrations of 21.33, 42.66 and 85.33 μM and subjected to the cytotoxicity assays using Trypan blue test and the comet assay, as well as the cytokinesis-block micronucleus assay. Doxorubicin (6 μM) and hydrogen peroxide (85.33 μM) were used as positive controls.

RESULTS

[6]-Gingerol, especially at concentrations of 42.66 and 85.33 μM, showed notable cytotoxicity in Sarcoma 180 cells by reducing cell viability and cell division rates via induction of apoptosis. Genotoxicity at the concentrations used was punctuated by the increase in the index and frequency of DNA damage in tested groups. [6]-Gingerol, at all concentrations tested, did not induce significant aneugenic and/or clastogenic effects. It did, however, induced other nuclear abnormalities, such as nucleoplasmic bridges, nuclear buds and apoptosis. The genotoxic effects observed in the cotreatment with H₂O₂ (challenge assay) employing neoplastic and healthy cells, indicated that [6]-Gingerol may induce oxidative stress.

CONCLUSIONS

Observations suggest that [6]-Gingerol may be a candidate for pharmaceutical antitumoral formulations due to its cytotoxicity and to mechanisms associated with genetic instability generated by nuclear alterations especially by apoptosis.

Targeting the DNA damage response (DDR) by natural compounds

Natural compounds (NC) are an important source of anticancer drugs. The genomic DNA of tumor cells is a major target of conventional anticancer therapeutics (cAT). DNA damage elicits a complex stress response programme termed DNA damage response (DDR), with the PI3-like kinase ATM and ATR being the key regulators. Since the DDR coordinates mechanisms of DNA repair and apoptosis, hence regulating the balance between death and survival, it is an attractive target of novel anticancer strategies. The aim of the study was to identify natural compounds derived from endophytic fungi, lichens, marine sponges or plants that interfere with mechanisms of the DDR. To this end, the cytotoxic and DDR modulating potency of 296 natural compounds, used alone or in combination with the cAT cisplatin (Cis) and doxorubicin (Doxo) was investigated by fluorescence-based analysis of the ATM/ATR-catalyzed S139 phosphorylation of histone 2AX (γH2AX), a surrogate marker of DNA damage-triggered DDR. After initial screening, a total of ten natural compounds were identified that were toxic in pancreatic carcinoma cells and activated the DDR on their own and/or promoted the DDR if used in combination with cAT. Their mode of action was shown to be independent of drug transport mechanisms. Based on their chemical structures, DDR modulatory activity and published data we suggest the marine NC 5-epi-nakijiquinone Q and 5-epi-ilimaquinone as well as the fungal compound secalonic acid F as most promising NC-based drug candidates for future synthesis of DDR-modulating chemical derivatives and their preclinical in vitro and in vivo testing.

Abilities of β-Estradiol to interact with chemotherapeutic drugs, signal transduction inhibitors and nutraceuticals and alter the proliferation of pancreatic cancer cells

Improving the effects of chemotherapy and reducing the side effects are important goals in cancer research. Various approaches have been examined to enhance the effectiveness of chemotherapy. For example, signal transduction inhibitors or hormonal based approaches have been included with chemo- or radio-therapy. MIA-PaCa-2 and BxPC-3 pancreatic ductal adenocarcinoma (PDAC) cells both express the estrogen receptor (ER). The effects of β-estradiol on the growth of PDAC cells has not been examined yet the ER is expressed in PDAC cells. We have examined the effects of combining β-estradiol with chemotherapeutic drugs, signal transcription inhibitors, natural products and nutraceuticals on PDAC. In most cases, inclusion of β-estradiol with chemotherapeutic drugs increased chemosensitivity. These results indicate some approaches involving β-estradiol which may be used to increase the effectiveness of chemotherapeutic and other drugs on the growth of PDAC.

Comparison between tumors in plants and human beings: Mechanisms of tumor development and therapy with secondary plant metabolites

BACKGROUND

Human tumors are still a major threat to human health and plant tumors negatively affect agricultural yields. Both areas of research are developing largely independent of each other. Treatment of both plant and human tumors remains unsatisfactory and novel therapy options are urgently needed.

HYPOTHESIS

The concept of this paper is to compare cellular and molecular mechanisms of tumor development in plants and human beings and to explore possibilities to develop novel treatment strategies based on bioactive secondary plant metabolites. The interdisciplinary discourse may unravel commonalities and differences in the biology of plant and human tumors as basis for rational drug development.

RESULTS

Plant tumors and galls develop upon infection by bacteria (e.g. Agrobacterium tumefaciens and A. vitis, which harbor oncogenic T-DNA) and by insects (e.g. gall wasps, aphids). Plant tumors are benign, i.e. they usually do not ultimately kill their host, but they can lead to considerable economic damage due to reduced crop yields of cultivated plants. Human tumors develop by biological carcinogenesis (i.e. viruses and other infectious agents), chemical carcinogenesis (anthropogenic and non-anthropogenic environmental toxic xenobiotics) and physical carcinogenesis (radioactivity, UV-radiation). The majority of human tumors are malignant with lethal outcome. Although treatments for both plant and human tumors are available (antibiotics and apathogenic bacterial strains for plant tumors, cytostatic drugs for human tumors), treatment successes are non-satisfactory, because of drug resistance and the severe adverse side effects. In human beings, attacks by microbes are repelled by cellular immunity (i.e. innate and acquired immune systems). Plants instead display chemical defense mechanisms, whereby constitutively expressed phytoanticipin compounds compare to the innate human immune system, the acquired human immune system compares to phytoalexins, which are induced by appropriate biotic or abiotic stressors. Some chemical weapons of this armory of secondary metabolites are also active against plant galls. There is a mutual co-evolution between plant defense and animals/human beings, which was sometimes referred to as animal plant warfare. As a consequence, hepatic phase I-III metabolization and excretion developed in animals and human beings to detoxify harmful phytochemicals. On the other hand, plants invented "pro-drugs" during evolution, which are activated and toxified in animals by this hepatic biotransformation system. Recent efforts focus on phytochemicals that specifically target tumor-related mechanisms and proteins, e.g. angiogenic or metastatic inhibitors, stimulators of the immune system to improve anti-tumor immunity, specific cell death or cancer stem cell inhibitors, inhibitors of DNA damage and epigenomic deregulation, specific inhibitors of driver genes of carcinogenesis (e.g. oncogenes), inhibitors of multidrug resistance (i.e. ABC transporter efflux inhibitors), secondary metabolites against plant tumors.

CONCLUSION

The exploitation of bioactive secondary metabolites to treat plant or human tumors bears a tremendous therapeutic potential. Although there are fundamental differences between human and plant tumors, either isolated phytochemicals and their (semi)synthetic derivatives or chemically defined and standardized plant extracts may offer new therapy options to decrease human tumor incidence and mortality as well as to increase agricultural yields by fighting crown galls.

Induction Apoptosis of Erinacine A in Human Colorectal Cancer Cells Involving the Expression of TNFR, Fas, and Fas Ligand via the JNK/p300/p50 Signaling Pathway With Histone Acetylation

Erinacine A, which is one of the major bioactive diterpenoid compounds extracted from cultured mycelia of H. erinaceus, displays great antitumorigenic activity. However, the molecular mechanisms underlying erinacine A inducing cancer cell apoptosis in colorectal cancer (CRC) remain unclear. This study found that treatment with erinacine A not only triggers the activation of extrinsic apoptosis pathways (TNFR, Fas, FasL, and caspases) but also suppresses the expression of antiapoptotic molecules Bcl-2 and Bcl-XL via a time-dependent manner in DLD-1 cells. Furthermore, phosphorylation of Jun N-terminus kinase (JNK1/2), NFκB p50, and p300 is involved in erinacine A–induced cancer cell apoptosis. Inhibition of these signaling pathways by kinase inhibitors blocks erinacine A–induced transcriptional activation implicates histone H3K9K14ac (Acetyl Lys9/Lys14) of the TNFR, Fas, and FasL as promoters. Moreover, histochemical and immunohistochemical analyses revealed that erinacine A treatment significantly induced the TNFR, Fas, and FasL levels in the in vivo xenograft mouse model. Together, these results demonstrated an increase in the cellular transcriptional levels of TNFR, Fas, and FasL by erinacine A induction to cell apoptosis via the activation of the JNK, p300, and NFκB p50 signaling modules, thereby providing a new mechanism for erinacine A treatment in vitro and in vivo.

A novel DNA repair inhibitor, diallyl disulfide (DADS), impairs DNA resection during DNA double-strand break repair by reducing Sae2 and Exo1 levels

Combining natural products with chemotherapy and/or radiotherapy may increase the efficacy of cancer treatment. It has been hypothesized that natural products may inhibit DNA repair and sensitize cancer cells to DNA damage-based cancer therapy. However, the molecular mechanisms underlying these activities remain unclear. In this study, we found that diallyl disulfide (DADS), an organosulfur compound, increased the sensitivity of yeast cells to DNA damage and has potential for development as an adjuvant drug for DNA damage-based cancer therapy. We induced HO endonuclease to generate a specific DNA double-strand break (DSB) by adding galactose to yeast and used this system to study how DADS affects DNA repair. In this study, we found that DADS inhibited DNA repair in single-strand annealing (SSA) system and sensitized SSA cells to a single DSB. DADS impaired DNA repair by inhibiting the protein levels of the DNA resection-related proteins Sae2 and Exo1. We also found that the recruitment of MRX and the Mec1-Ddc2 complex to a DSB was prevented by DADS. This result suggests that DADS counteracts G2/M DNA damage checkpoint activation in a Mec1 (ATR)- and Tel1 (ATM)-dependent manner. Only by elucidating the molecular mechanisms by which DADS influences DNA repair will we be able to discover new adjuvant drugs to improve chemotherapy and/or radiotherapy.

Polyphenols enhance the activity of alkylating agents in leukaemia cell lines

Polyphenols have been shown to sensitize solid tumours to alkylating agents such as cisplatin, and induce apoptosis and/or cell-cycle arrest. Here, we assess the effects of five polyphenols alone and in combination with three alkylating agents: cisplatin, cyclophosphamide and chlorambucil in lymphoid and myeloid leukaemia cells lines, and non-tumour control cells. In lymphoid leukaemia cell lines there was a synergistic reduction in ATP and glutathione levels, an induction of cell cycle arrest, DNA damage and apoptosis when quercetin, apigenin, emodin and rhein were combined with cisplatin and cyclophosphamide; and when apigenin and rhein were combined with chlorambucil. In myeloid leukaemia cells quercetin, apigenin and emodin showed a similar synergistic effect with all alkylating agents; however antagonistic effects were observed with some or all alkylating agents when combined with emodin, rhein and cis-stilbene. All synergistic effects were associated with reduced glutathione levels, DNA damage and apoptosis; whilst during antagonism the reverse effects were observed. The combination of alkylating agents, particularly cisplatin with polyphenols could be promising for the treatment of lymphoid leukaemias, with apigenin showing the greatest effects. Likewise in myeloid cells apigenin also synergised the action of all alkylating agents, suggesting that apigenin may also be beneficial in myeloid leukaemias.

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.

Pelargonidin reduces the TPA induced transformation of mouse epidermal cells -potential involvement of Nrf2 promoter demethylation

Pelargonidin, a well-known natural anthocyanidin found in berries strawberries, blueberries, red radishes and other natural foods, has been found to possess health beneficial effects including anti-cancer effect. Herein, we investigated the effect of pelargonidin on cellular transformation in mouse skin epidermal JB6 (JB6 P+) cells induced by tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Pelargonidin treatment significantly decreased colony formation and suppressed cell viability of JB6 P+ cells. Pelargonidin also induced the anti-oxidant response element (ARE)-luciferase activation in HepG2-C8 cells overexpressing the ARE-luciferase reporter. Knockdown of nuclear factor E2-related factor 2 (Nrf2) in shNrf2 JB6 P+ cells enhanced TPA-induced colony formation and attenuated pelargonidin's blocking effect. Pelargonidin reduced the protein levels of genes encoding methyltransferases (DNMTs) and histone deacetylases (HDACs). Importantly, pelargonidin decreased the DNA methylation in the Nrf2 promoter region of JB6 P+ cells and increased Nrf2 downstream target genes expression, such as NAD(P)H/quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), involved in cellular protection. In summary, our results showed that pelargonidin blocks TPA-induced cell transformation. The possible molecular mechanisms of its potential anti-cancer effects against neoplastic transformation may be attributed to its activation of Nrf2-ARE signaling pathway and its cytoprotective effect.

Thioether-based 2-aminobenzamide derivatives: Novel HDAC inhibitors with potent in vitro and in vivo antitumor activity

Previously, we focused on a series of 2-aminobenzamide-based histone deacetylase (HDAC) inhibitors, compound 9 of which displayed potent HDAC inhibitory activity against HDAC1 and HDAC2, and moderate anti-proliferative activity against several cancer cell lines. In the current study, we have designed and synthesized a series of novel HDAC inhibitors based on thioether moiety with 9 as a lead compound. Representative compounds12 g and 12 h showed apparently potent anti-proliferative activities against five solid cancer cell lines: A549, HCT116, Hela, A375 and SMMC7721, and low cytotoxicity against NIH 3T3 normal cells. Especially, 12 g and 12 h also revealed potent HDAC inhibitory activity against HDAC1, 2 and 3. In addition, the two compounds could arrest cell cycle in G2/M phase and promote cell apoptosis. Moreover, they showed extended inhibition of colony formation and effectively blocked cell migration towards A549 cancer cells. Furthermore, 12 g and 12 h possessed better pharmacokinetic properties than the lead compound 9. Benefiting from these results, we also explored 12 g and 12 h in the A549 xenografts model for in vivo antitumor activity. The in vivo experiment indicated that 12 g and 12 h could evidently augment antitumor activity (TGI = 56.9% and 62.7% respectively).

Targeting the unfolded protein response in head and neck and oral cavity cancers

Many FDA-approved anti-cancer therapies, targeted toward a wide array of molecular targets and signaling networks, have been demonstrated to activate the unfolded protein response (UPR). Despite a critical role for UPR signaling in the apoptotic execution of cancer cells by many of these compounds, the authors are currently unaware of any instance whereby a cancer drug was developed with the UPR as the intended target. With the essential role of the UPR as a driving force in the genesis and maintenance of the malignant phenotype, a great number of pre-clinical studies have surged into the medical literature describing the ability of dozens of compounds to induce UPR signaling in a myriad of cancer models. The focus of the current work is to review the literature and explore the role of the UPR as a mediator of chemotherapy-induced cell death in squamous cell carcinomas of the head and neck (HNSCC) and oral cavity (OCSCC), with an emphasis on preclinical studies.

Effective and new potent drug combination: Histone deacetylase and Wnt/β-catenin pathway inhibitors in lung carcinoma cells

Lung cancer is the most commonly diagnosed cancer worldwide with a high mortality rate. In this study, the therapeutic effect of combination valproic acid and niclosamide was investigated on human lung cancer cell line. The effects of the compounds alone and combination therapy on cell viability were determined by sulforhodamine B and adenosine 5'-triphosphate viability assays. Flow cytometry was used to determine the cell death mechanism and DNA damage levels responsible for the cytotoxic effects of combination therapy. The presence of apoptosis in cells was supported by fluorescence microscopy and also by using inhibitors of the apoptotic signaling pathway. The increase in cellular reactive oxygen species (ROS) level in combination therapy was determined by H2DCFDA staining. The effect of N-acetyl-l-cysteine combination on ROS increase was investigated on cell viability. In addition, the expression levels of the proteins associated with epigenetic regulation and cell death were analyzed by Western blotting and gene expression levels were determined using real-time quantitative polymerase chain reaction.It was observed that the combination therapy showed a cytotoxic effect on the A549 lung cancer cells compared to the individual use of the inhibitors. The absence of this effect on normal lung cells revealed the presence of a selective toxic effect. When the mechanism of cytotoxicity is examined, it has been observed that combination therapy initiates the activation of tumor necrosis receptors and causes apoptosis by activated caspase. It was also observed that this extrinsic apoptotic pathway was activated on the mitochondrial pathway. In addition, ER stress and mitochondrial membrane potential loss associated with increased ROS levels induce cell death. When the data in this study were evaluated, combination therapy caused a dramatic decrease in cell viability by inducing the extrinsic apoptotic pathway in lung cancer cell line. Therefore, it was concluded that it can be used as an effective and new treatment option for lung cancer.