The role of a ginseng saponin metabolite as a DNA methyltransferase inhibitor in colorectal cancer cells

Natural bioactive compounds targeting DNA methyltransferase enzymes in cancer: Mechanisms insights and efficiencies

The regulation of gene expression is fundamental to health and life and is essentially carried out at the promoter region of the DNA of each gene. Depending on the molecular context, this region may be accessible or non-accessible (possibility of integration of RNA polymerase or not at this region). Among enzymes that control this process, DNA methyltransferase enzymes (DNMTs), are responsible for DNA demethylation at the CpG islands, particularly at the promoter regions, to regulate transcription. The aberrant activity of these enzymes, i.e. their abnormal expression or activity, can result in the repression or overactivation of gene expression. Consequently, this can generate cellular dysregulation leading to instability and tumor development. Several reports highlighted the involvement of DNMTs in human cancers. The inhibition or activation of DNMTs is a promising therapeutic approach in many human cancers. In the present work, we provide a comprehensive and critical summary of natural bioactive molecules as primary inhibitors of DNMTs in human cancers. The active compounds hold the potential to be developed as anti-cancer epidrugs targeting DNMTs.

A New Frontier in Studying Dietary Phytochemicals in Cancer and in Health: Metabolic and Epigenetic Reprogramming

Metabolic rewiring and epigenetic reprogramming are closely inter-related, and mutually regulate each other to control cell growth in cancer initiation, promotion, progression, and metastasis. Epigenetics plays a crucial role in regulating normal cellular functions as well as pathological conditions in many diseases, including cancer. Conversely, certain mitochondrial metabolites are considered as essential cofactors and regulators of epigenetic mechanisms. Furthermore, dysregulation of metabolism promotes tumor cell growth and reprograms the cells to produce metabolites and bioenergy needed to support cancer cell proliferation. Hence, metabolic reprogramming which alters the metabolites/epigenetic cofactors, would drive the epigenetic landscape, including DNA methylation and histone modification, that could lead to cancer initiation, promotion, and progression. Recognizing the diverse array of benefits of phytochemicals, they are gaining increasing interest in cancer interception and treatment. One of the significant mechanisms of cancer interception and treatment by phytochemicals is reprogramming of the key metabolic pathways and remodeling of cancer epigenetics. This review focuses on the metabolic remodeling and epigenetics reprogramming in cancer and investigates the potential mechanisms by which phytochemicals can mitigate cancer.

Research progress of ginseng in the treatment of gastrointestinal cancers

Cancer has become one of the major causes of human death. Several anticancer drugs are available; howeve their use and efficacy are limited by the toxic side effects and drug resistance caused by their continuous application. Many natural products have antitumor effects with low toxicity and fewer adverse effects. Moreover, they play an important role in enhancing the cytotoxicity of chemotherapeutic agents, reducing toxic side effects, and reversing chemoresistance. Consequently, natural drugs are being applied as potential therapeutic options in the field of antitumor treatment. As natural medicinal plants, some components of ginseng have been shown to have excellent efficacy and a good safety profile for cancer treatment. The pharmacological activities and possible mechanisms of action of ginseng have been identified. Its broad range of pharmacological activities includes antitumor, antibacterial, anti-inflammatory, antioxidant, anti-stress, anti-fibrotic, central nervous system modulating, cardioprotective, and immune-enhancing effects. Numerous studies have also shown that throuth multiple pathways, ginseng and its active ingredients exert antitumor effects on gastrointestinal (GI) tract tumors, such as esophageal, gastric, colorectal, liver, and pancreatic cancers. Herein, we introduced the main components of ginseng, including ginsenosides, polysaccharides, and sterols, etc., and reviewed the mechanism of action and research progress of ginseng in the treatment of various GI tumors. Futhermore, the pathways of action of the main components of ginseng are discussed in depth to promote the clinical development and application of ginseng in the field of anti-GI tumors.

Therapeutic effects of ginseng and ginsenosides on colorectal cancer

Colorectal cancer (CRC) is among the most common malignant diseases with high morbidity and mortality rates. Ginseng and its major extracts, ginsenosides, have been used in medical fields for thousands of years. In particular, their huge anti-cancer potential has drawn a great deal of attention in recent years. There is a large body of evidence that has shown that ginseng and its extracts could significantly inhibit tumor development and progression by suppressing cell proliferation, tumor growth, invasion and metastasis, inducing tumor cell apoptosis, regulating tumor-associated immune responses, and improving the therapeutic effect of chemotherapy. Notably, different subtypes of ginsenosides, even those extracted from the same ginseng, have exhibited distinct anti-cancer functions through different mechanisms. Over the past few years, a large number of studies have focused on how ginseng or various ginsenosides influence CRC development. Therefore, the roles and the potential of ginseng and ginsenosides in the treatment of CRC are summarized in this review. In addition, the biochemical properties of ginseng and ginsenosides are also briefly described.

Targeting Epigenetic Regulatory Enzymes for Cancer Therapeutics: Novel Small-Molecule Epidrug Development

Dysregulation of the epigenetic enzyme-mediated transcription of oncogenes or tumor suppressor genes is closely associated with the occurrence, progression, and prognosis of tumors. Based on the reversibility of epigenetic mechanisms, small-molecule compounds that target epigenetic regulation have become promising therapeutics. These compounds target epigenetic regulatory enzymes, including DNA methylases, histone modifiers (methylation and acetylation), enzymes that specifically recognize post-translational modifications, chromatin-remodeling enzymes, and post-transcriptional regulators. Few compounds have been used in clinical trials and exhibit certain therapeutic effects. Herein, we summarize the classification and therapeutic roles of compounds that target epigenetic regulatory enzymes in cancer treatment. Finally, we highlight how the natural compounds berberine and ginsenosides can target epigenetic regulatory enzymes to treat cancer.

Functional Mechanism of Ginsenoside Compound K on Tumor Growth and Metastasis

Ginsenosides, as the most important constituents of ginseng, have been extensively investigated in cancer chemoprevention and therapeutics. Among the ginsenosides, Compound K (CK), a rare protopanaxadiol type of ginsenoside, has been most broadly used for cancer treatment due to its high anticancer bioactivity. However, the functional mechanism of CK in cancer is not well known. This review describes the structure, transformation and pharmacological activity of CK and discusses the functional mechanisms of CK and its metabolites, which regulate signaling pathways related to tumor growth and metastasis. CK inhibits tumor growth by inducing tumor apoptosis and tumor cell differentiation, regulates the tumor microenvironment by suppressing tumor angiogenesis-related proteins, and downregulates the roles of immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs). There is currently much research on the potential development of CK as a new strategy when administered alone or in combination with other compounds.

Administration of red ginseng regulates microRNA expression in a mouse model of endometriosis

OBJECTIVE

Red ginseng (RG) exerts anti-inflammatory, anti-proliferative, and immunomodulatory effects on endometriosis through the regulation of microRNA (miRNA) expression. It may also ameliorate endometriosis by affecting the expression of multiple miRNAs simultaneously, rather than acting on a single miRNA at a given time. Since studies on the overall effects of RG on endometriosis via the regulation of miRNA expression are lacking, the current study aimed to explore the global effect of RG on miRNA expression in a mouse model of endometriosis.

METHODS

To establish the mouse model, the uterine horn of donor mice was implanted into the lateral side of the recipients' peritoneum, followed by vehicle or RG treatment for 8 weeks.

RESULTS

To confirm the effects of RG on the established mouse model, the size of the implanted uterus was measured; it was found to be lower in mice from the RG group than in mice from the control group. miRNA expression profiles in the implanted uterus of the mouse model of endometriosis after vehicle or RG administration were analyzed using microarray technology. Thereafter, seven candidate miRNAs and 125 candidate genes (miRNA targets) were identified through a bioinformatics analysis.

CONCLUSION

The present findings suggest that RG regulates the expression of multiple miRNAs and mRNAs, thereby alleviating endometriosis in a mouse model of the disease.

Anticancer mechanisms of phytochemical compounds: focusing on epigenetic targets

It has recently been proven that epigenetic dysregulation is importantly involved in cell transformation and therefore induces cancerous diseases. The development of molecules called epidrugs, which target specifically different epigenetic modifications to restore cellular memory and therefore the treatment, became a real challenge currently. Currently, bioactive compounds of medicinal plants as epidrugs have been can identified and explored in cancer therapy. Indeed, these molecules can target specifically different epigenetic modulators including DNMT, HDAC, HAT, and HMT. Moreover, some compounds exhibit stochastic epigenetic actions on different pathways regulating cell memory. In this work, pharmacodynamic actions of natural epidrugs belonging to cannabinoids, carotenoids, chalcones, fatty acids, lignans, polysaccharides, saponins, secoiridoids, steroids, tannins, tanshinones, and other chemical classes we reported and highlighted. In this review, the effects of several natural bioactive compounds of epigenetic medications on cancerous diseases were highlighted. Numerous active molecules belonging to different chemical classes such as cannabinoids, carotenoids, fatty acids, lignans, polysaccharides, saponins, secoiridoids, steroids, tannins, and tanshinones are discussed in this review.

Inhibition of DNA methylation derepresses PPARγ and attenuates pulmonary fibrosis

BACKGROUND AND PURPOSE

Development of pulmonary fibrosis is associated with altered DNA methylation modifications of fibrogenic gene expressions; however, their causal relationships and the underlying mechanisms remain unclear. This study investigates the critical role of DNA methylation aberration-associated suppression of PPARγ (peroxisome proliferator-activated receptor-gamma) in pulmonary fibrosis.

EXPERIMENTAL APPROACH

Expressions of PPARγ and bioactive DNA methyltranferases, and PPARγ promoter methylation status were examined from fibrotic lungs of idiopathic pulmonary fibrosis (IPF) patients and bleomycin (Blm)-treated mice. DNA demethylating agent 5-Aza-2'-deoxycytidine (5aza) and glycyrrhizic acid (GA) derived from medicinal plant were assessed for their PPARγ derepression and anti-pulmonary fibrosis activities. PPARγ knockout mice were created to determine the critical role of PPARγ in the protections.

KEY RESULTS

Lung PPARγ expressions were markedly suppressed in IPF patients and Blm mice, accompanied by increased methyltransferase (DNMT) 1/DNMT3a and PPARγ promoter hypermethylation. Administrations of 5aza and GA similarly demethylated PPARγ promoter, recovered the PPARγ loss and alleviated the fibrotic lung pathologies, including structural alterations and adverse expressions of fibrotic mediators and inflammatory cytokines. In cultured lung fibroblast and alveolar epithelial cells, GA alleviated the fibrotic PPARγ suppression in a gain of DNMT-sensitive manner, and in PPARγ knockout mice, the anti-fibrotic effects of 5aza and GA were significantly reduced, suggesting that PPARγ is a critical mediator of epigenetic pulmonary fibrogenesis.

CONCLUSION AND IMPLICATIONS

Aberrant DNMT1/3a elevations and the resultant PPARγ suppression contribute significantly to the development of pulmonary fibrosis, and strategies targeting DNMT/PPARγ axis by synthetic or natural small compounds might benefit patients with pulmonary fibrotic disorders.

Nanocarriers in the Enhancement of Therapeutic Efficacy of Natural Drugs

Abstract Since time immemorial, plant derived natural products have been used for the treatment of various human diseases before the intervention of modern medicine. The basis of modern medicine is still being inspired from traditional medicine and therapies. However, despite their tremendous therapeutic potential, these natural drugs often have poor bioavailability, metabolic instability, and aqueous insolubility. These factors greatly impede a natural drug’s commercialization potential as a mainstream medicine. Therefore, the development of nanocarrier drug delivery systems is indispensable in overcoming the various constraints of the bottlenecks which occur with natural drugs. Of particular interest in this review are four plant materials endogenous to China with the common names of barrenwort or horny goat weed (Epimedium), Shu Di Huang (Rehmannia glutinosa, RG), ginseng (Panax ginseng), and Dong Quai or female ginseng (Angelica sinensis, AS), each having been scientifically investigated for a wide range of therapeutic uses as has been originally discovered from the long history of traditional usage and anecdotal information by local population groups in Asia. The integration of natural drugs from the East and nanocarrier drug delivery systems developed from the West is paving the way towards further accurate and efficient medicine therapy. We further discuss the potential benefits of these plants and the enhancement of their therapeutic efficacy by nanotechnology intervention.

Sanjie Yiliu Formula Inhibits Colorectal Cancer Growth by Suppression of Proliferation and Induction of Apoptosis

Colorectal cancer (CRC) is one of the most common malignancies worldwide. As current therapies toward CRC, including chemotherapy and radiotherapy, pose limitations, such as multidrug resistance (MDR) as well as the intrinsic and potential cytotoxic effects, necessitating to find more effective treatment options with fewer side effects, traditional Chinese medicine (TCM) has an advantage in complementary therapies. In the present study, 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assays), trypan blue staining, colony formation, 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining, cell cycle determination, and Annexin V-FITC/PI staining were used to examine the efficacy of Sanjie Yiliu Formula (SJYLF) against CRC proliferation and to investigate its underlying molecular mechanisms through protein expression of various proapoptotic factors by quantitative polymerase chain reaction (q-PCR) and Western blotting. This four-herb-TCM SJYLF can be suggested as one of the decoctions clinically effective in late-stage cancer treatment. Our results suggest that SJYLF robustly decreased the viability of only CRC cell lines (HCT-8, SW-480, HT-29, and DLD-1) and not the normal human kidney cells (HK-2). Moreover, SJYLF significantly suppressed proliferation and induced apoptosis in HCT-8 and downregulated cyclin D1, CDK4, and BCL-2, while Bax expression was upregulated at both mRNA and protein expression levels.

Epigenetics/epigenomics of triterpenoids in cancer prevention and in health

Triterpenoids are a powerful group of phytochemicals derived from plant foods and herbs. Many reports have shown that they possess chemopreventive and chemotherapeutic effects not only in cell lines and animal models but also in clinical trials. Because epigenetic changes could potentially occur in the early stages of carcinogenesis preceding genetic mutations, epigenetics are considered promising targets in early interventions against cancer using epigenetic bioactive substances. The biological properties of triterpenoids in cancer prevention and in health have multiple mechanisms, including antioxidant and anti-inflammatory activities, cell cycle regulation, as well as epigenetic/epigenomic regulation. In this review, we will discuss and summarize the latest advances in the study of the pharmacological effects of triterpenoids in cancer chemoprevention and in health, including the epigenetic machinery.

Ginsenoside Rh2 Suppresses Breast Cancer Cell Proliferation by Epigenetically Regulating the Long Noncoding RNA C3orf67-AS1

Ginsenoside Rh2, a major bioactive ingredient abundant in red ginseng, has an antiproliferative effect on various cancer cells. In this study, we report a novel long noncoding RNA, C3orf67-AS1, which was identified as being hypermethylated at a CpG site of the promoter by Rh2 in MCF-7 cancer cells. Rh2-induced hypermethylation was responsible for the lower gene expression; the expression was recovered following treatment with a methyltransferase inhibitor, 5-aza-2^'-deoxycytidine. When C3orf67-AS1 was downregulated by a siRNA, the cell growth rate was decreased, demonstrating the RNA's oncogenic activity. Accordingly, breast cancer patients showed a lower methylation and higher expression level of C3orf67-AS1. Within 800 kb flanking C3orf67-AS1 on the chromosome, eight genes were found, and four genes including C3orf67 (the sense strand gene of C3orf67-AS1) were downregulated by Rh2. In particular, C3orf67 was downregulated when C3orf67-AS1 was suppressed by a siRNA; however, the expression of C3orf67-AS1 was not affected by C3orf67. Taken together, this study identifies a novel noncoding RNA, C3orf67-AS1, of which the expression could be suppressed by Rh2 via promoter methylation, thereby mediating the anti-proliferative effect of the ginsenoside.

Paris saponin VII extracted from trillium tschonoskii suppresses proliferation and induces apoptosis of human colorectal cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Saponins of many herbs could inhibit the growth of colorectal cancer cells. In the study, we investigated the effects of Paris saponin Ⅶ (PSⅦ), and elucidated its mechanism in colorectal carcinoma cells and a xenograft mouse model.

MATERIALS AND METHODS

HT-29 and HCT-116 cells were treated with different concentrations of PSⅦ (0-100 μM). The effects of PSⅦ on HCT-116 cells were assessed using a microarray. Then, apoptotic cells were detected by flow cytometric analysis and apoptosis related protein expression was evaluated by Western blot. A xenograft model of nude mice was used to assess the effect of PSⅦ in vivo.

RESULTS

MTT assay showed the IC₅₀ values of PSⅦ for growth inhibition of HT-29 and HCT-116 cells were 1.02 ± 0.05 μM and 3.50 ± 0.79 μM respectively. Edu assay demonstrated that PSⅦ effectively suppressed the growth of HT-29 and HCT-116 cells. Treatment with 0-3 μM PSⅦ not only triggered apoptosis, but also activated caspase-3 and caspase-9 of HT-29 and HCT-116 cells in a concentration dependent manner. In parallel to the alterations, Bax and Cyto-c expression increased while Bcl-2 decreased. In nude mice, PSⅦ reduced the tumor size and induced the apoptosis of tumor cells. PSVII could suppress IL-6-induced phosphorylation of STAT3 in vitro and blocked STAT3 phosphorylation in vivo.

CONCLUSION

Our results suggest that PSVII suppressed the activation of IL-6/STAT3 pathway, consequently suppressed the growth and proliferation and triggered the apoptosis of CRC cells. These findings indicate that PSⅦ might be an effective tumouristatic agent for the treatment of colorectal cancer.

Landscape of tumor suppressor long noncoding RNAs in breast cancer

BACKGROUND

The landscape and biological functions of tumor suppressor long noncoding RNAs in breast cancer are still unknown.

METHODS

Data from whole transcriptome sequencing of 33 breast specimens in the Harbin Medical University Cancer Center cohort and The Cancer Genome Atlas was applied to identify and validate the landscape of tumor suppressor long noncoding RNAs, which was further validated by The Cancer Genome Atlas pancancer data including 33 cancer types and 12,839 patients. Next, the expression model, prognostic roles, potential biological functions and epigenetic regulation of tumor suppressor long noncoding RNAs were investigated and validated in the breast cancer and pancancer cohorts. Finally, EPB41L4A-AS2 was selected to validate our novel finding, and the tumor suppressive roles of EPB41L4A-AS2 in breast cancer were examined.

RESULTS

We identified and validated the landscape of tumor suppressor long noncoding RNAs in breast cancer. The expression of the identified long noncoding RNAs was downregulated in cancer tissue samples compared with normal tissue samples, and these long noncoding RNAs correlated with a favorable prognosis in breast cancer patients and the patients in the pancancer cohort. Multiple carcinogenesis-associated biological functions were predicted to be regulated negatively by these long noncoding RNAs. Moreover, these long noncoding RNAs were transcriptionally regulated by epigenetic modification, including DNA methylation and histone methylation modification. Finally, EPB41L4A-AS2 inhibited breast cancer cell proliferation, migration and invasion and induced cell apoptosis in vitro. Mechanistically, EPB41L4A-AS2, acting at least in part as a tumor suppressor, upregulated tumor suppressor gene expression. Moreover, ZNF217 recruited EZH2 to the EPB41L4A-AS2 locus and suppressed the expression of EPB41L4A-AS2 by epigenetically increasing H3K27me3 enrichment.

CONCLUSIONS

This work enlarges the functional landscape of known long noncoding RNAs in human cancer and provides novel insights into the suppressive roles of these long noncoding RNAs.

The ginsenoside metabolite compound K inhibits growth, migration and stemness of glioblastoma cells

Glioblastoma (GBM) is the most aggressive and malignant form of primary brain cancer. Despite recent advances in cancer treatment, it remains a substantially incurable disease. Accordingly, more effective GBM therapeutic options are urgently required. In the present study, we investigated the anticancer effect of a ginsenoside metabolite, compound K (CK), against GBM cells. CK significantly inhibited not only growth, but also metastatic ability of U87MG and U373MG cells. CK arrested cell cycle progression at the G0/G1 phase with a decrease in the expression levels of cyclin D1 and cyclin D3 in both cell types. CK also induced apoptosis in GBM cells through nuclear condensation, an increase in ROS generation, mitochondrial membrane potential depolarization, and activation of caspase-3, caspase-9 and poly(ADP-ribose) polymerase (PARP). Furthermore, CK inhibited phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway, contributing to the antiproliferative and apoptotic effects. Moreover, CK suppressed the self-renewal capacity as well as the invasiveness of U87MG and U373MG GBM stem-like cells (GSCs) by inducing a reduction in the expression of GSC markers, such as CD133, Nanog, Oct4 and Sox2. Taken together, our findings suggest that CK may potentially be useful for GBM treatment.

Demographic and medication characteristics of traditional Chinese medicine users among colorectal cancer survivors: A nationwide database study in Taiwan

Chinese herbal product (CHP) is the major type of traditional Chinese medicine (TCM) and widely used to relief the symptom of colorectal cancer. The aim of the study was to analyze the utilization of CHP for treating patients with colorectal cancer in Taiwan. The usage of CHP, frequency of services, and prescription pattern for colorectal cancer were analyzed from a randomly sampled cohort of 1 million beneficiaries from the National Health Insurance Research Database. The odds ratios for utilization of CHP were estimated with logistic regression model. 2846 patients were newly diagnosed as colorectal cancer during 1998–2008 in the million cohort in Taiwan. 42.7% (n = 1214) of them used CHP. Colorectal cancer was the most common diagnosis coded by TCM doctor, followed by symptoms, signs, and ill-defined conditions. Costusroot and Amomum Six Gentlemen Decoction (香砂六君子湯 xiāng shā liù jūn zǐ tāng) was the most frequently prescribed formula for treating colorectal cancer. Among the top 10 most frequently prescribed CHP for treating colorectal cancer, six containing Ginseng Radix (人參, ​Panax ginseng) and two containing Astragali Radix (黃耆, Astragalus membranaceus), which are reported to have potential beneficial synergistic effects on colorectal cancer cells. CHP containing Ginseng Radix or Astragali Radix are the most frequently prescribed for colorectal cancer and their effects should be taken into account by healthcare providers.

Anticancer Activities of Protopanaxadiol- and Protopanaxatriol-Type Ginsenosides and Their Metabolites

Recently, most anticancer drugs are derived from natural resources such as marine, microbial, and botanical sources, but the low success rates of chemotherapies and the development of multidrug resistance emphasize the importance of discovering new compounds that are both safe and effective against cancer. Ginseng types, including Asian ginseng, American ginseng, and notoginseng, have been used traditionally to treat various diseases, due to their immunomodulatory, neuroprotective, antioxidative, and antitumor activities. Accumulating reports have shown that ginsenosides, the major active component of ginseng, were helpful for tumor treatment. 20(S)-Protopanaxadiol (PDS) and 20(S)-protopanaxatriol saponins (PTS) are two characteristic types of triterpenoid saponins in ginsenosides. PTS holds capacity to interfere with crucial metabolism, while PDS could affect cell cycle distribution and prodeath signaling. This review aims at providing an overview of PTS and PDS, as well as their metabolites, regarding their different anticancer effects with the proposal that these compounds might be potent additions to the current chemotherapeutic strategy against cancer.

Trillium tschonoskii steroidal saponins suppress the growth of colorectal Cancer cells in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Saponins of many herbs are known to possess anti-cancer effect.

AIM OF THE STUDY

The present study aimed to investigate the growth inhibitory effect of Trillium tschonoskii steroidal saponins in a mouse model of colitis-associated colorectal cancer and a human colorectal cancer cell line HT-29, and isolate some major constituents and evaluate their anti-tumor activity.

MATERIALS AND METHODS

Forty male ICR mice were administered with 1, 2-dimethyl-hydrazine (DMH) and dextran sodium sulfate (DSS). Ten mice were given no further treatment, the rest were administered with different doses of TTS (5, 10, 20mg/kg) orally, every three days from the 9th week to the 20th week.

RESULTS

TTS effectively protected ICR mice against DMH/DSS-induced tumorigenesis. The incidence of tumor development was 90% (9/10) in the mice treated with DMH/DSS, but that was reduced to 50% (5/10), 40% (4/10), and 20% (2/10), respectively, in the mice treated with 5%, 10%, and 20% of TTS. Results of Ki-67 staining, TUNEL assay and caspase-3 activity assay revealed that TTS moderately decreased abnormal proliferation and increased apoptosis of colonic epithelial cells. It inhibited the growth and triggered the apoptosis of HT-29 cells, partly through suppressing mitogen-actived protein kinases (MAPKs) and triggering mitochondrial-mediated apoptotic pathway. Three compounds, namely, Paris saponin VII, polyphylloside III and Paris saponin VI, were important active compounds in TTS.

CONCLUSION

These data suggest that TTS has a potential role in clinical prevention and treatment for colorectal cancer.

Ginsenoside Rg3 induces apoptosis in human multiple myeloma cells via the activation of Bcl-2-associated X protein

Ginsenoside Rg3 is one of the main constituents isolated from Panax ginseng, and exhibits cytotoxic effects against cancer cells. The present study aimed to investigate the effects of ginsenoside Rg3 on human multiple myeloma cells, and determine the underlying molecular mechanisms. The cells were exposed to ginsenoside Rg3 at various concentrations (0‑80 µM) for 48 h. A subsequent cell proliferation assay demonstrated that treatment with ginsenoside Rg3 resulted in a dose‑dependent inhibition of the proliferation of U266 and RPMI8226 cells. Furthermore, exposure to ginsenoside Rg3 led to a marked increase in the rate of apoptosis in the U266 cells, coupled with increased caspase‑3 activity. The ginsenoside Rg3‑treated cells also exhibited an elevation in the expression of B‑cell lymphoma 2‑associated X protein (Bax), a pro‑apoptotic protein. Notably, knockdown of Bax protected the U266 cells from Rg3‑induced apoptosis. Overall, these findings suggested that ginsenoside Rg3 induced apoptosis in multiple myeloma cells, at least partially, through upregulation of the expression of Bax.

β-elemene inhibited expression of DNA methyltransferase 1 through activation of ERK1/2 and AMPKα signalling pathways in human lung cancer cells: the role of Sp1

β-elemene, a compound derived from Rhizoma zedoariae, is a promising new plant-derived drug with broad-spectrum anticancer activity. However, the underlying mechanism by which this agent inhibits human lung cancer cell growth has not been well elucidated. In this study, we showed that β-elemene inhibits human non-small cell lung carcinoma (NSCLC) cell growth, and increased phosphorylation of ERK1/2, Akt and AMPKα. Moreover, β-elemene inhibited expression of DNA methyltransferase 1 (DNMT1), which was not observed in the presence of the specific inhibitors of ERK (PD98059) or AMPK (compound C). Overexpression of DNMT1 reversed the effect of β-elemene on cell growth. Interestingly, metformin not only reversed the effect of β-elemene on phosphorylation of Akt but also strengthened the β-elemene-reduced DNMT1. In addition, β-elemene suppressed Sp1 protein expression, which was eliminated by either ERK1/2 or AMPK inhibitor. Conversely, overexpression of Sp1 antagonized the effect of β-elemene on DNMT1 protein expression and cell growth. Taken together, our results show that β-elemene inhibits NSCLC cell growth via ERK1/2- and AMPKα-mediated inhibition of transcription factor Sp1, followed by reduction in DNMT1 protein expression. Metformin augments the effect of β-elemene by blockade of Akt signalling and additively inhibition of DNMT1 protein expression. The reciprocal ERK1/2 and AMPKα signalling pathways contribute to the overall responses of β-elemene. This study reveals a potential novel mechanism by which β-elemene inhibits growth of NSCLC cells.

Current Perspectives on Epigenetic Modifications by Dietary Chemopreventive and Herbal Phytochemicals

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

Paris saponin VII inhibits growth of colorectal cancer cells through Ras signaling pathway

Dysregulation of the Ras signaling pathway plays a key role in the progression of colorectal cancer. When bound to GTP, Ras is activated and stimulates several downstream effectors' pathways, including the Raf/MEK/ERK kinase cascade, the PI3-kinase/AKT/mTor pathway, and the Ral GTPase pathway. Saponins extracted from Liliaceae family herbs have strong antitumor activities with low toxicity. In this study, Paris saponin VII (PSVII), isolated from Trillium tschonoskii Maxim., was evaluated on human colorectal cancer cells (HT-29 and SW-620), a mouse model of colitis associated colorectal cancer (CACC) and a murine model of xenograft tumor. It was found that PSVII inhibited colorectal cancer cell growth in a concentration-dependent manner. The IC50 values of PSVII for growth inhibition of HT-29 and SW-620 cells were 1.02 ± 0.05 μM and 4.90 ± 0.23 μM. It could induce cell apoptosis, together with cell cycle arrest in G1 phase, and trigger apoptosis in a caspase-3-dependent manner. PSVII-induced growth inhibitory effect was associated with disturbance of MAPK pathway by down-regulating MEK1/2, ERK1/2 phosphorylation, and suppression of AKT pathway by reducing AKT and GSK-3β phosphorylation. In the CACC mouse model, PSVII protected mice from intestinal toxicities and carcinogenesis induced by 1,2-dimethylhydrazine (DMH) and dextran sodium sulfate (DSS). In the model of xenograft tumor, PSVII remarkably decreased the xenograft tumor size and triggered the apoptosis of tumor cells. Both in vitro and in vivo study showed that PSVII inhibited Ras activity. Taken together, PSVII might be a potential therapeutic reagent for colorectal cancer through targeting Ras signaling pathway.

Compound K, a metabolite of ginseng saponin, inhibits colorectal cancer cell growth and induces apoptosis through inhibition of histone deacetylase activity

In this study, we investigated the molecular mechanisms underlying the anti-proliferative effects of Compound K, with specific reference to histone modification. Exposure of HT-29 human colon cancer cells to Compound K resulted in time-dependent inhibition of histone deacetylase (HDAC) activity, mRNA and protein expression. Compound K treatment induced unmethylation of the RUNX3 promoter region such as TSA treatment and an accumulation of acetylated histones H3 and H4 within the total cellular chromatin, resulting in an enhanced ability of these histones to bind to the promoter sequences of the tumor suppressor gene Runt-related transcription factor 3 (RUNX3). Treatment of cells with Compound K increased the mRNA and protein expression of RUNX3, as well as p21, a downstream target of RUNX3. These alterations were consistent with cell cycle arrest at the G0/G1 phases and induction of apoptosis. Our results provide new insights into the mechanisms of Compound K action in human colorectal cancer cells and suggest that HDAC inhibition presents a novel approach to prevent or treat colorectal cancer.