The effect of sulforaphane on histone deacetylase activity in keratinocytes: Differences between in vitro and in vivo analyses

Natural Compounds in Non-Melanoma Skin Cancer: Prevention and Treatment

The elevated occurrence of non-melanoma skin cancer (NMSC) and the adverse effects associated with available treatments adversely impact the quality of life in multiple dimensions. In connection with this, there is a necessity for alternative approaches characterized by increased tolerance and lower side effects. Natural compounds could be employed due to their safety profile and effectiveness for inflammatory and neoplastic skin diseases. These anti-cancer drugs are often derived from natural sources such as marine, zoonotic, and botanical origins. Natural compounds should exhibit anti-carcinogenic actions through various pathways, influencing apoptosis potentiation, cell proliferation inhibition, and metastasis suppression. This review provides an overview of natural compounds used in cancer chemotherapies, chemoprevention, and promotion of skin regeneration, including polyphenolic compounds, flavonoids, vitamins, alkaloids, terpenoids, isothiocyanates, cannabinoids, carotenoids, and ceramides.

Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents

The study of epigenetic translational modifications had drawn great interest for the last few decades. These processes play a vital role in many diseases and cancer is one of them. Histone acetyltransferase (HAT) and histone deacetylases (HDACs) are key enzymes involved in the acetylation and deacetylation of histones and ultimately in post-translational modifications. Cancer frequently exhibits epigenetic changes, particularly disruption in the expression and activity of HDACs. It includes the capacity to regulate proliferative signalling, circumvent growth inhibitors, escape cell death, enable replicative immortality, promote angiogenesis, stimulate invasion and metastasis, prevent immunological destruction, and genomic instability. The majority of tumours develop and spread as a result of HDAC dysregulation. As a result, HDAC inhibitors (HDACis) were developed, and they today stand as a very promising therapeutic approach. One of the most well-known and efficient therapies for practically all cancer types is chemotherapy. However, the efficiency and safety of treatment are constrained by higher toxicity. The same has been observed with the synthetic HDACi. Natural products, owing to many advantages over synthetic compounds for cancer treatment have always been a choice for therapy. Hence, naturally available molecules are of particular interest for HDAC inhibition and HDAC has drawn the attention of the research fraternity due to their potential to offer a diverse array of chemical structures and bioactive compounds. This diversity opens up new avenues for exploring less toxic HDAC inhibitors to reduce side effects associated with conventional synthetic inhibitors. The review presents comprehensive details on natural product HDACi, their mechanism of action and their biological effects. Moreover, this review provides a brief discussion on the structure activity relationship of selected natural HDAC inhibitors and their analogues which can guide future research to discover selective, more potent HDACi with minimal toxicity.

Anticancer properties of sulforaphane: current insights at the molecular level

Sulforaphane (SFN) is an isothiocyanate with multiple biomedical applications. Sulforaphane can be extracted from the plants of the genus Brassica. However, broccoli sprouts are the chief source of sulforaphane and are 20 to 50 times richer than mature broccoli as they contain 1,153 mg/100 g. SFN is a secondary metabolite that is produced as a result of the hydrolysis of glucoraphanin (a glucosinolate) by the enzyme myrosinase. This review paper aims to summarize and understand the mechanisms behind the anticancer potential of sulforaphane. The data was collected by searching PubMed/MedLine, Scopus, Web of Science, and Google Scholar. This paper concludes that sulforaphane provides cancer protection through the alteration of various epigenetic and non-epigenetic pathways. It is a potent anticancer phytochemical that is safe to consume with minimal side effects. However, there is still a need for further research regarding SFN and the development of a standard dose.

Phytochemicals as Immunomodulatory Agents in Melanoma

Cutaneous melanoma is an immunogenic highly heterogenic tumor characterized by poor outcomes when it is diagnosed late. Therefore, immunotherapy in combination with other anti-proliferative approaches is among the most effective weapons to control its growth and metastatic dissemination. Recently, a large amount of published reports indicate the interest of researchers and clinicians about plant secondary metabolites as potentially useful therapeutic tools due to their lower presence of side effects coupled with their high potency and efficacy. Published evidence was reported in most cases through in vitro studies but also, with a growing body of evidence, through in vivo investigations. Our aim was, therefore, to review the published studies focused on the most interesting phytochemicals whose immunomodulatory activities and/or mechanisms of actions were demonstrated and applied to melanoma models.

Targeting Class I Histone Deacetylases in Human Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is the most frequent subtype of uterine sarcoma that presents a poor prognosis, high rates of recurrence, and metastasis. Currently, the molecular mechanism of the origin and development of uLMS is unknown. Class I histone deacetylases (including HDAC1, 2, 3, and 8) are one of the major classes of the HDAC family and catalyze the removal of acetyl groups from lysine residues in histones and cellular proteins. Class I HDACs exhibit distinct cellular and subcellular expression patterns and are involved in many biological processes and diseases through diverse signaling pathways. However, the link between class I HDACs and uLMS is still being determined. In this study, we assessed the expression panel of Class I HDACs in uLMS and characterized the role and mechanism of class I HDACs in the pathogenesis of uLMS. Immunohistochemistry analysis revealed that HDAC1, 2, and 3 are aberrantly upregulated in uLMS tissues compared to adjacent myometrium. Immunoblot analysis demonstrated that the expression levels of HDAC 1, 2, and 3 exhibited a graded increase from normal and benign to malignant uterine tumor cells. Furthermore, inhibition of HDACs with Class I HDACs inhibitor (Tucidinostat) decreased the uLMS proliferation in a dose-dependent manner. Notably, gene set enrichment analysis of differentially expressed genes (DEGs) revealed that inhibition of HDACs with Tucidinostat altered several critical pathways. Moreover, multiple epigenetic analyses suggested that Tucidinostat may alter the transcriptome via reprogramming the oncogenic epigenome and inducing the changes in microRNA-target interaction in uLMS cells. In the parallel study, we also determined the effect of DL-sulforaphane on the uLMS. Our study demonstrated the relevance of class I HDACs proteins in the pathogenesis of malignant uLMS. Further understanding the role and mechanism of HDACs in uLMS may provide a promising and novel strategy for treating patients with this aggressive uterine cancer.

The recent advances of glucosinolates and their metabolites: Metabolism, physiological functions and potential application strategies

Glucosinolates and their metabolites from Brassicaceae plants have received widespread attention due to their anti-inflammatory effects. Glucosinolates occurs an "enterohepatic circulation" in the body, and the glucosinolates metabolism mainly happens in the intestine. Glucosinolates can be converted into isothiocyanates by intestinal bacteria, which are active substances with remarkable anti-inflammatory, anti-cancer, anti-obesity and neuroprotective properties. This biotransformation can greatly improve the bioactivities of glucosinolates. However, multiple factors in the environment can affect the biotransformation to isothiocyanates, including acidic pH, ferrous ions and thiocyanate-forming protein. The derivatives of glucosinolates under those conditions are usually nitriles and thiocyanates, which may impair the potential health benefits. In addition, isothiocyanates are extremely unstable because of an active sulfhydryl group, which limits their applications. This review mainly summarizes the classification, synthesis, absorption, metabolism, physiological functions and potential application strategies of glucosinolates and their metabolites.

Roles of Histone Acetylation Modifiers and Other Epigenetic Regulators in Vascular Calcification

Vascular calcification (VC) is characterized by calcium deposition inside arteries and is closely associated with the morbidity and mortality of atherosclerosis, chronic kidney disease, diabetes, and other cardiovascular diseases (CVDs). VC is now widely known to be an active process occurring in vascular smooth muscle cells (VSMCs) involving multiple mechanisms and factors. These mechanisms share features with the process of bone formation, since the phenotype switching from the contractile to the osteochondrogenic phenotype also occurs in VSMCs during VC. In addition, VC can be regulated by epigenetic factors, including DNA methylation, histone modification, and noncoding RNAs. Although VC is commonly observed in patients with chronic kidney disease and CVD, specific drugs for VC have not been developed. Thus, discovering novel therapeutic targets may be necessary. In this review, we summarize the current experimental evidence regarding the role of epigenetic regulators including histone deacetylases and propose the therapeutic implication of these regulators in the treatment of VC.

Sulforaphane metabolites cause apoptosis via microtubule disruption in cancer

Sulforaphane (SFN) inhibited growth in many cancers, but its half-life is 2 h in circulation. However, its metabolites, sulforaphane-cysteine (SFN-Cys) and sulforaphane-N-acetyl-cysteine (SFN-NAC) had longer half-lives and decreased the cell viability in both dose- and time-dependent manners in human prostate cancer. Flow cytometry assay revealed that these two SFN metabolites induced apoptosis with the features such as vacuolization, disappeared nuclear envelope, nuclear agglutination and fragmentation via transmission electron microscopy observation. Western blot showed that the sustained phosphorylation of ERK1/2 mediated by SFN metabolites caused activation and upregulation of cleaved Caspase 3 and downregulation of α-tubulin. High expression of α-tubulin was demonstrated to be positively correlated with cancer pathological grading. Both co-immunoprecipitation and immunofluorescence staining implicated the interaction between SFN metabolite-induced phosphorylated ERK1/2 and α-tubulin, and Caspase 3 cleavage assay showed that α-tubulin might be the substrate for cleaved Caspase 3. More, the SFN metabolite-mediated reduction of α-tubulin increased the depolymerization and instability of microtubules by microtubule polymerization assay. Reversely, microtubule-associated protein Stathmin-1 phosphorylation was increased via phosphorylated ERK1/2 and total Stathmin-1 was reduced, which might promote over-stability of microtubules. Immunofluorescence staining also showed that SFN metabolites induced the 'nest-like' structures of microtubule distribution resulting from the disrupted and aggregated microtubules, and abnormal nuclear division, suggesting that the disturbance of spindle formation and mitosis turned up. Thus, SFN-Cys and SFN-NAC triggered the dynamic imbalance of microtubules, microtubule disruption leading to cell apoptosis. These findings provided a novel insight into the chemotherapy of human prostate cancer.

Chemopreventive effects of some popular phytochemicals on human colon cancer: a review

The present review summarizes (1) the epidemiology and etiology of colon cancer, (2) generalized cancer chemoprotective mechanisms, and (3) the chemopreventive properties of some popular phytochemicals as well as some phytochemicals developed by our research group recently.

Anti-cancer effects of naturally derived compounds targeting histone deacetylase 6-related pathways

Alterations of the epigenetic machinery, affecting multiple biological functions, represent a major hallmark enabling the development of tumors. Among epigenetic regulatory proteins, histone deacetylase (HDAC)6 has emerged as an interesting potential therapeutic target towards a variety of diseases including cancer. Accordingly, this isoenzyme regulates many vital cellular regulatory processes and pathways essential to physiological homeostasis, as well as tumor multistep transformation involving initiation, promotion, progression and metastasis. In this review, we will consequently discuss the critical implications of HDAC6 in distinct mechanisms relevant to physiological and cancerous conditions, as well as the anticancer properties of synthetic, natural and natural-derived compounds through the modulation of HDAC6-related pathways.

Reversible Keap1 inhibitors are preferential pharmacological tools to modulate cellular mitophagy

Mitophagy orchestrates the autophagic degradation of dysfunctional mitochondria preventing their pathological accumulation and contributing to cellular homeostasis. We previously identified a novel chemical tool (hereafter referred to as PMI), which drives mitochondria into autophagy without collapsing their membrane potential (ΔΨ_m). PMI is an inhibitor of the protein-protein interaction (PPI) between the transcription factor Nrf2 and its negative regulator, Keap1 and is able to up-regulate the expression of autophagy-associated proteins, including p62/SQSTM1. Here we show that PMI promotes mitochondrial respiration, leading to a superoxide-dependent activation of mitophagy. Structurally distinct Keap1-Nrf2 PPI inhibitors promote mitochondrial turnover, while covalent Keap1 modifiers, including sulforaphane (SFN) and dimethyl fumarate (DMF), are unable to induce a similar response. Additionally, we demonstrate that SFN reverses the effects of PMI in co-treated cells by reducing the accumulation of p62 in mitochondria and subsequently limiting their autophagic degradation. This study highlights the unique features of Keap1-Nrf2 PPI inhibitors as inducers of mitophagy and their potential as pharmacological agents for the treatment of pathological conditions characterized by impaired mitochondrial quality control.

Natural Compound Histone Deacetylase Inhibitors (HDACi): Synergy with Inflammatory Signaling Pathway Modulators and Clinical Applications in Cancer

The remarkable complexity of cancer involving multiple mechanisms of action and specific organs led researchers Hanahan and Weinberg to distinguish biological capabilities acquired by cancer cells during the multistep development of human tumors to simplify its understanding. These characteristic hallmarks include the abilities to sustain proliferative signaling, evade growth suppressors, resist cell death, enable replicative immortality, induce angiogenesis, activate invasion and metastasis, avoid immune destruction, and deregulate cellular energetics. Furthermore, two important characteristics of tumor cells that facilitate the acquisition of emerging hallmarks are tumor-promoting inflammation and genome instability. To treat a multifactorial disease such as cancer, a combination treatment strategy seems to be the best approach. Here we focus on natural histone deacetylase inhibitors (HDACi), their clinical uses as well as synergies with modulators of the pro-inflammatory transcription factor signaling pathways.

Research progress on chemopreventive effects of phytochemicals on colorectal cancer and their mechanisms

Colorectal cancer (CRC) is a type of cancer with high morbidity and mortality rates worldwide and has become a global health problem. The conventional radiotherapy and chemotherapy regimen for CRC not only has a low cure rate but also causes side effects. Many studies have shown that adequate intake of fruits and vegetables in the diet may have a protective effect on CRC occurrence, possibly due to the special biological protective effect of the phytochemicals in these foods. Numerous in vitro and in vivo studies have demonstrated that phytochemicals play strong antioxidant, anti-inflammatory and anti-cancer roles by regulating specific signaling pathways and molecular markers to inhibit the occurrence and development of CRC. This review summarizes the progress on CRC prevention using the phytochemicals sulforaphane, curcumin and resveratrol, and elaborates on the specific underlying mechanisms. Thus, we believe that phytochemicals might provide a novel therapeutic approach for CRC prevention, but future clinical studies are needed to confirm the specific preventive effect of phytochemicals on cancer.

Epigenetic modifications of triterpenoid ursolic acid in activating Nrf2 and blocking cellular transformation of mouse epidermal cells

Ursolic acid (UA), a well-known natural triterpenoid found in abundance in blueberries, cranberries and apple peels, has been reported to possess many beneficial health effects. These effects include anticancer activity in various cancers, such as skin cancer. Skin cancer is the most common cancer in the world. Nuclear factor E2-related factor 2 (Nrf2) is a master regulator of antioxidative stress response with anticarcinogenic activity against UV- and chemical-induced tumor formation in the skin. Recent studies show that epigenetic modifications of Nrf2 play an important role in cancer prevention. However, the epigenetic impact of UA on Nrf2 signaling remains poorly understood in skin cancer. In this study, we investigated the epigenetic effects of UA on mouse epidermal JB6 P+ cells. UA inhibited cellular transformation by 12-O-tetradecanoylphorbol-13-acetate at a concentration at which the cytotoxicity was no more than 25%. Under this condition, UA induced the expression of the Nrf2-mediated detoxifying/antioxidant enzymes heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1 and UDP-glucuronosyltransferase 1A1. DNA methylation analysis revealed that UA demethylated the first 15 CpG sites of the Nrf2 promoter region, which correlated with the reexpression of Nrf2. Furthermore, UA reduced the expression of epigenetic modifying enzymes, including the DNA methyltransferases DNMT1 and DNMT3a and the histone deacetylases (HDACs) HDAC1, HDAC2, HDAC3 and HDAC8 (Class I) and HDAC6 and HDAC7 (Class II), and HDAC activity. Taken together, these results suggest that the epigenetic effects of the triterpenoid UA could potentially contribute to its beneficial effects, including the prevention of skin cancer.