Penta-O-galloyl-beta-D-glucose inhibits the invasion of mouse melanoma by suppressing metalloproteinase-9 through down-regulation of activator protein-1

Pentagalloyl Glucose: A Review of Anticancer Properties, Molecular Targets, Mechanisms of Action, Pharmacokinetics, and Safety Profile

Pentagalloyl glucose (PGG) is a natural hydrolyzable gallotannin abundant in various plants and herbs. It has a broad range of biological activities, specifically anticancer activities, and numerous molecular targets. Despite multiple studies available on the pharmacological action of PGG, the molecular mechanisms underlying the anticancer effects of PGG are unclear. Here, we have critically reviewed the natural sources of PGG, its anticancer properties, and underlying mechanisms of action. We found that multiple natural sources of PGG are available, and the existing production technology is sufficient to produce large quantities of the required product. Three plants (or their parts) with maximum PGG content were Rhus chinensis Mill, Bouea macrophylla seed, and Mangifera indica kernel. PGG acts on multiple molecular targets and signaling pathways associated with the hallmarks of cancer to inhibit growth, angiogenesis, and metastasis of several cancers. Moreover, PGG can enhance the efficacy of chemotherapy and radiotherapy by modulating various cancer-associated pathways. Therefore, PGG can be used for treating different human cancers; nevertheless, the data on the pharmacokinetics and safety profile of PGG are limited, and further studies are essential to define the clinical use of PGG in cancer therapies.

Penta-O-Galloyl-β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells

Natural molecules have promising perspectives as adjuvants to chemotherapies against cancer. Pistacia chinensis subsp. Integerrima (hereafter, Pistacia integerrima) traditionally known for medicinal values in respiratory disorders was tested for anti-lung cancer properties. The extract prepared from Pistacia integerrima (PI) selectively impaired the viability of lung cancer cells, A549 and NCI-H460, compared to non-cancer cells. At non-lethal concentrations, PI mitigated colony-forming, spheroid formations and metastatic properties of lung cancer cells. As a step toward identifying the phytomolecule that is imparting the anti-lung cancer properties in PI, we subjected the extract to extensive characterization through UPLC/QToF-MS and further validated the findings with UHPLC. The gallotannin, penta-O-galloyl-β-D-glucose (PGG), among others, was identified through UPLC/QToF-MS. PGG exhibits potential chemopreventive effects against various cancer types. However, a defined mechanism of action of PGG in restricting lung cancer progression is still unexplored. Bioactivity-guided column fractionations enabled the determination of PGG as the major phytochemical that governed PI-mediated AMPK-ULK1-dependent autophagy and apoptosis, albeit independent of intracellular ROS activation. Interestingly, the autophagy flux when inhibited restored the cell viability even in the presence of PI. The study further delineated that PI and PGG activated ERK and inhibited STAT3 to trigger apoptosis through caspase-3 and PARP 1 pathways. Collectively, the finding demonstrates that plant extract, PGG, in the PI extract effectively combats lung cancer progression through autophagic cell death by altering ERK/AMPK-ULK1/STAT3 signaling axes. The study proposes PGG as a potential AMPK activator and STAT3 inhibitor that can be exploited further in developing adjuvant chemotherapeutics against lung cancer.

Pentagalloyl Glucose and Its Functional Role in Vascular Health: Biomechanics and Drug-Delivery Characteristics

Pentagalloyl glucose (PGG) is an elastin-stabilizing polyphenolic compound that has significant biomedical benefits, such as being a free radical sink, an anti-inflammatory agent, anti-diabetic agent, enzymatic resistant properties, etc. This review article focuses on the important benefits of PGG on vascular health, including its role in tissue mechanics, the different modes of pharmacological administration (e.g., oral, intravenous and endovascular route, intraperitoneal route, subcutaneous route, and nanoparticle based delivery and microbubble-based delivery), and its potential therapeutic role in vascular diseases such as abdominal aortic aneurysms (AAA). In particular, the use of PGG for AAA suppression and prevention has been demonstrated to be effective only in the calcium chloride rat AAA model. Therefore, in this critical review we address the challenges that lie ahead for the clinical translation of PGG as an AAA growth suppressor.

Water extract of Galla Rhois with steaming process enhances apoptotic cell death in human colon cancer cells

Background

Galla Rhois has been considered to have medicinal properties against diarrhea, excessive sweating, bleeding, and chronic cough in Asian countries. Gallotannins, which are Galla Rhois-derived tannins, have been reported to possess biological and pharmacological activities, especially anticancer activity. In this study, we evaluated the effect of steaming at a temperature over 120 °C on the chemical constituents and biological activities of the water extract of Galla Rhois (GRE).

Methods

GRE was steamed at a temperature over 120 °C (AGRE), and its specific constituents were analyzed; the results were validated using a high-performance liquid chromatography–diode array detector system. To evaluate the anticancer effect of GRE and AGRE, cell viability assay, cell cycle analysis, and Western blot analysis were performed in HCT116 human colon cancer cells.

Results

Steaming markedly increased the contents of gallic acid and ellagic acid in GRE, and GRE or AGRE treatment reduced the viability of HCT116 cells. Notably, the steaming process enhanced the growth inhibitory effect of GRE in cancer cells. AGRE induced apoptosis through the activation of caspase-3, caspase-8, and caspase-9. Additionally, AGRE regulated the activation of mitogen-activated protein kinases including extracellular signal-regulated kinase, p38, and c-Jun NH2-terminal kinase, whereas GRE did not. However, both GRE and AGRE inhibited the activation of AKT.

Conclusion

Compared with GRE, AGRE is more potent in its ability to induce apoptosis in HCT116 cells; therefore, we suggest that the steaming process may be useful as a feasible method for improving the anticancer effect of GRE.

Dietary polyphenols in prevention and treatment of prostate cancer

Prostate cancer is the most prevalent disease affecting males in many Western countries, with an estimated 29,480 deaths in 2014 in the US alone. Incidence rates for prostate cancer deaths have been decreasing since the early 1990s in men of all races/ethnicities, though they remain about 60% higher in African Americans than in any other group. The relationship between dietary polyphenols and the prevention of prostate cancer has been examined previously. Although results are sometimes inconsistent and variable, there is a general agreement that polyphenols hold great promise for the future management of prostate cancer. Various dietary components, including polyphenols, have been shown to possess anti-cancer properties. Generally considered as non-toxic, dietary polyphenols act as key modulators of signaling pathways and are therefore considered ideal chemopreventive agents. Besides possessing various anti-tumor properties, dietary polyphenols also contribute to epigenetic changes associated with the fate of cancer cells and have emerged as potential drugs for therapeutic intervention. Polyphenols have also been shown to affect post-translational modifications and microRNA expressions. This article provides a systematic review of the health benefits of selected dietary polyphenols in prostate cancer, especially focusing on the subclasses of polyphenols, which have a great effect on disease prevention and treatment.

Hinokitiol, a tropolone derivative, inhibits mouse melanoma (B16-F10) cell migration and in vivo tumor formation

Invasion and metastasis are the major causes of treatment failure in patients with cancer. Hinokitiol, a natural bioactive compound found in Chamacyparis taiwanensis, has been used in hair tonics, cosmetics, and food as an antimicrobial agent. In this study, we investigated the effects and possible mechanisms of action of hinokitiol on migration by the metastatic melanoma cell line, B16-F10, in which matrix metalloproteinase-1 (MMP-1) is found to be highly- expressed. Treatment with hinokitiol revealed a concentration-dependent inhibition of migration of B16-F10 melanoma cells. Hinokitiol appeared to achieve this effect by reducing the expression of MMP-1 and by suppressing the phosphorylation of mitogen- activated protein kinase (MAPK) signaling molecules such as extracellular signal-regulated kinase (ERK) 1/2, p38 MAPK and c-Jun N-terminal kinases (JNK). On the other hand, hinokitiol treatment reversed IκB-α degradation and inhibited the phosphorylation of p65 nuclear factor kappa B (NF-κB) and cJun in B16-F10 cells. In addition, hinokitiol suppressed the translocation of p65 NF-κB from the cytosol to the nucleus, suggesting reduced NF-κB activation. Consistent with these in vitro findings, our in vivo study demonstrated that hinokitiol treatment significantly reduced the total number of mouse lung metastatic nodules and improved histological alterations in B16-F10 injected C57BL/6 mice. These findings suggest that treatment of B16-F10 cells with hinokitiol significantly inhibits metastasis, possibly by blocking MMP-1 activation, MAPK signaling pathways and inhibition of the transcription factors, NF-κB and c-Jun, involved in cancer cell migration. These results may accelerate the development of novel therapeutic agents for the treatment of malignant cancers.

Biological and biomedical functions of Penta-O-galloyl-D-glucose and its derivatives

Penta-O-galloyl-D-glucose (PGG) is a simple hydrolysable tannin in plants. PGG exists in two anomeric forms, α-PGG and β-PGG. While β-PGG can be found in a wide variety of plants, α-PGG is rather rare in nature. Numerous studies with β-PGG revealed a wide variety of biological activities, such as anti-microbial and anti-cancer functions. Until recently, studies with α-PGG were limited by the lack of its availability. Since the development of an efficient chemical synthesis of the compound, several investigations have revealed its anti-diabetic, anti-cancer, and anti-platelet-coagulation functions. Based on structure-activity-relationship (SAR) studies with α-PGG, a variety of α-PGG-related novel compounds were synthesized and some of them have been shown to possess promising therapeutic activities. In this review, the authors will survey and evaluate the biological functions of PGG with a focus on α-PGG and its derivatives.

Reactive oxygen species-mediated activation of JNK and down-regulation of DAXX are critically involved in penta-O-galloyl-beta-d-glucose-induced apoptosis in chronic myeloid leukemia K562 cells

Although 1,2,3,4,6-penta-O-galloyl-beta-d-glucose (PGG) was well known to have antitumor activities in breast, prostate, kidney, liver cancers and HL-60 leukemia via regulation of caspase 3, p53, S-phase kinase-associated protein 2 (Skp2) and insulin receptor signaling, the underlying mechanism of PGG-induced apoptosis linked with reactive oxygen species (ROS) mediated c-Jun N-terminal kinase (JNK) and DAXX was never elucidated in chronic myeloid leukemia (CML) K562 cells until now. Herein PGG significantly decreased the viability of CML cell lines such as K562 and KBM-5 without hurting normal peripheral blood lymphocytes (PBLs). PGG increased the number of TUNEL-positive cells and the sub-G1 cell population as well as activated caspase cascades including caspase-8, -9 and -3 in K562 cells. Interestingly, a significant activation of JNK by PGG was observed by MULTIPLEX assay and Western blotting. Conversely, JNK inhibitor D-JNKi suppressed the cleavages of caspase 3 and PARP induced by PGG in K562 cells. Also, PGG dramatically enhanced generation of ROS and reduced the expression of death-domain-associated protein (DAXX). Of note, ROS inhibitor acetyl-L-cysteine (NAC) reversed JNK-dependent apoptosis and DAXX inhibition induced by PGG. Overall, these findings suggest that ROS-dependent JNK activation and DAXX downregulation are critically involved in PGG-induced apoptosis in K562 cells.

Tannic acid down-regulates the angiotensin type 1 receptor through a MAPK-dependent mechanism

In the present study, we investigated the effects of tannic acid (TA), a hydrolysable polyphenol, on angiotensin type 1 receptor (AT1R) expression in continuously passaged rat liver epithelial cells. Under normal conditions, exposure of cells to TA resulted in the down-regulation of AT1R-specific binding in concentrations ranging from 12.5-100 μg/ml (7.34-58.78 μm) over a time period of 2-24 h with no change in receptor affinity to angiotensin II (AngII). The inhibitory effect of TA on AT1R was specific and reversible. In TA-treated cells, we observed a significant reduction in AngII-mediated intracellular calcium signaling, a finding consistent with receptor down-regulation. Under similar conditions, TA down-regulated AT1R mRNA expression without changing the rate of mRNA degradation, suggesting that TA's effect is mediated through transcriptional inhibition. Cells expressing recombinant AT1R without the native promoter show no change in receptor expression, whereas a pCAT reporter construct possessing the rat AT1R promoter was significantly reduced in activity. Furthermore, TA induced the phosphorylation of MAPK p42/p44. Pretreatment of the cells with a MAPK kinase (MEK)-specific inhibitor PD98059 prevented TA-induced MAPK phosphorylation and down-regulation of the AT1R. Moreover, there was no reduction in AngII-mediated intracellular calcium release upon MEK inhibition, suggesting that TA's observed inhibitory effect is mediated through MEK/MAPK signaling. Our findings demonstrate, for the first time, that TA inhibits AT1R gene expression and cellular response, suggesting the observed protective effects of dietary polyphenols on cardiovascular conditions may be, in part, through inhibition of AT1R expression.

Hamamelitannin from witch hazel (Hamamelis virginiana) displays specific cytotoxic activity against colon cancer cells

Hamamelis virginiana (witch hazel) bark is a rich source of condensed and hydrolyzable tannins reported to exert a protective action against colon cancer. The present study characterizes different witch hazel tannins as selective cytotoxic agents against colon cancer. To cover the structural diversity of the tannins that occur in H. virginiana bark, the hydrolyzable tannins, hamamelitannin and pentagalloylglucose, together with a proanthocyanidin-rich fraction (F800H4) were selected for the study. Treatment with these compounds reduced tumor viability and induced apoptosis, necrosis, and S-phase arrest in the cell cycle of HT29 cells, with hamamelitannin being the most efficient. Owing to polyphenol-mediated H(2)O(2) formation in the incubation media, the antiproliferative effect was determined in the presence and absence of catalase to rule out any such interference. The presence of catalase significantly changed the IC(50) only for F800H4. Furthermore, at concentrations that inhibit the growth of HT29 cells by 50%, hamamelitannin had no harmful effects on NCM460 normal colonocytes, whereas pentagalloylglucose inhibited both cancerous and normal cell growth. Using the TNPTM assay, we identified a highly reactive phenolic position in hamamelitannin, which may explain its efficacy at inhibiting colon cancer growth.

The genome-wide expression profile of 1,2,3,4,6-penta-O-galloyl-β-D-glucose-treated MDA-MB-231 breast cancer cells: molecular target on cancer metabolism

1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG), a polyphenolic compound isolated from Rhus chinensis Mill. PGG has been known to have anti-tumor, anti-angiogenic and anti-diabetic activities. The present study revealed another underlying molecular target of PGG in MDA-MB-231 breast cancer cells by using Illumina Human Ref-8 expression BeadChip assay. Through the Beadstudio v3 micro assay program to compare the identified genes expressed in PGG-treated MDA-MB-231 cells with untreated control, we found several unique genes that are closely associated with pyruvate metabolism, glycolysis/gluconeogenesis and tyrosine metabolism, including PC, ACSS2, ACACA, ACYP2, ALDH3B1, FBP1, PRMT2 and COMT. Consistent with microarray data, real-time RT-PCR confirmed the significant down-regulation of these genes at mRNA level in PGG-treated MDA-MB-231 cells. Our findings suggest the potential of PGG as anticancer agent for breast cancer cells by targeting cancer metabolism genes.

Conformation of the tridimensional structure of 1,2,3,4,6-pentagalloyl-β-D-glucopyranose (PGG) by (1)H NMR, NOESY and theoretical study and membrane interaction in a simulated phospholipid bilayer: a first insight

1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG) is a polyphenolic compound found in substantial amounts in a number of medicinal herbs. We report (i) its conformational analysis by solution NMR and molecular dynamics calculation and (ii) theoretical study of its interaction with a model membrane bilayer. The galloyl groups B and E appear to play important roles in the interaction with the phospholipid bilayer.

Rhus chinensis and Galla Chinensis--folklore to modern evidence: review

The species Rhus chinensis Mill. (Anacardiaceae) is an important representative of the genus Rhus, which contains over 250 individual species found in temperate and tropical regions worldwide. Rhus chinensis has long been used by folk medicine practitioners in Asia. Leaves, roots, stem, bark, fruit and particularly the galls on Rhus chinensis leaves, Galla chinensis, are recognized to have preventative and therapeutic effects on different ailments (such as diarrhea, dysentery, rectal and intestinal cancer, diabetes mellitus, sepsis, oral diseases and inflammation). However, it is critical to separate evidence from anecdote. Fortunately, recent scientific research has revealed that Rhus chinensis compounds possess strong antiviral, antibacterial, anticancer, hepatoprotective, antidiarrheal and antioxidant activities. Moreover, compounds isolated from the stem of Rhus chinensis significantly suppressed HIV-1 activity in vitro. Compounds from this plant were also found to inhibit enamel demineralization in vitro and enhance remineralization of dental enamel with fluoride. This review highlights claims from traditional and tribal medicinal lore and makes a contemporary summary of phytochemical, biological and pharmacological findings on this plant material. It aims to show that the pharmaceutical potential of this plant deserves closer attention.

Pentagalloylglucose downregulates cofilin1 and inhibits HSV-1 infection

To investigate the anti-herpesvirus mechanism of pentagalloylglucose (PGG), we compared the proteomic changes between herpes simplex virus type 1 (HSV-1) infected MRC-5 cells with or without PGG-treatment, and between non-infected MRC-5 cells with or without PGG-treatment by 2-DE and MS-based analysis. Differentially expressed cellular proteins were mainly involved with actin cytoskeleton regulation. Significantly, PGG can down-regulate cofilin1, a key regulator of actin cytoskeleton dynamics. PGG can inhibit HSV-1-induced rearrangements of actin cytoskeleton which is important for infectivity. Furthermore, cofilin1 knockdown by siRNA also inhibited the HSV-1-induced actin-skeleton rearrangements. Both PGG-treatment and cofilin1 knockdown can reduce HSV-1 DNA, mRNA, protein synthesis and virus yields. Altogether, the results suggested that down-regulating cofilin1 plays a role in PGG inhibiting HSV-1 infection. PGG may be a promising anti-herpesvirus agent for drug development.

Penta-O-galloyl-beta-D-glucose induces G1 arrest and DNA replicative S-phase arrest independently of cyclin-dependent kinase inhibitor 1A, cyclin-dependent kinase inhibitor 1B and P53 in human breast cancer cells and is orally active against triple negative xenograft growth

Introduction

Natural herbal compounds with novel actions different from existing breast cancer (BCa) treatment modalities are attractive for improving therapeutic efficacy and safety. We have recently shown that penta-1,2,3,4,6-O-galloyl-β-D-glucose (PGG) induced S-phase arrest in prostate cancer (PCa) cells through inhibiting DNA replicative synthesis and G₁ arrest, in addition to inducing cell death at higher levels of exposure. We and others have shown that PGG through intraperitoneal (i.p.) injection exerts a strong in vivo growth suppression of human PCa xenograft models in athymic nude mice. This study aims to test the hypothesis that the novel targeting actions of PGG are applicable to BCa cells, especially those lacking proven drugable targets.

Methods

Mono-layer cell culture models of p53-wild type estrogen receptor (ER)-dependent MCF-7 BCa cells and p53-mutant ER-/progesterone receptor (PR)- and Her2-regular (triple-negative) MDA-MB-231 BCa were exposed to PGG for a comprehensive investigation of cellular consequences and molecular targets/mediators. To test the in vivo efficacy, female athymic mice inoculated with MDA-MB-231 xenograft were treated with 20 mg PGG/kg body weight by daily gavage starting 4 days after cancer cell inoculation.

Results

Exposure to PGG induced S-phase arrest in both cell lines as indicated by the lack of 5-bromo2'-deoxy-uridine (BrdU) incorporation into S-phase cells as well as G₁ arrest. Higher levels of PGG induced more caspase-mediated apoptosis in MCF-7, in strong association with induction of P53 Ser¹⁵ phosphorylation, than in MDA-MB-231 cells. The cell cycle arrests were achieved without an induction of cyclin dependent kinase (CDK) inhibitory proteins P21^Cip1 and P27^Kip1. PGG treatment led to decreased cyclin D1 in both cell lines and over-expressing cyclin D1 attenuated G₁ arrest and hastened S arrest. In serum-starvation synchronized MCF-7 cells, down-regulation of cyclin D1 was associated with de-phosphorylation of retinoblastoma (Rb) protein by PGG shortly before G₁-S transition. In vivo, oral administration of PGG led to a greater than 60% inhibition of MDA-MB231 xenograft growth without adverse effect on host body weight.

Conclusions

Our in vitro and in vivo data support PGG as a potential drug candidate for breast cancer with novel targeting actions, especially for a triple negative BCa xenograft model.

Antimetastatic activity of MONCPT in preclinical melanoma mice model

Previous study demonstrated that MONCPT, a topoisomerase I inhibitor, exhibited potent anti-proliferation and anti-angiogenesis activity in vitro and in vivo. In this study, we report the efficacy of MONCPT against the development of melanoma metastasis by an intravenous injection of green fluorescent protein-transfected mice melanoma carcinoma (B16F10-GFP) cells in C57BL/6 mice. MONCPT (2.0, 5.0 and 12.5 mg/kg/2 days) markedly decreased B16F10-GFP pulmonary metastases by 12.8%, 53.1% and 76.3%, respectively; whereas higher doses of MONCPT (31.0 mg/kg/2 days) significantly inhibited the tumor growth of B16F10 xenograft model. In the in vitro experiment, MONCPT suppressed the B16F10-GFP cell invasion and migration without affecting cell survival. Further studies demonstrated that MONCPT decreased the secretion of matrix metalloproteinase (MMP)-9 and VEGF, and reduced the protein expression of HIF-1α as well as the phosphorylation level of ERK in B16F10-GFP cells. These in vivo and in vitro results indicate that MONCPT possesses both the potent antimetastatic ability and the tumor growth-inhibition activity, and the dual function promises MONCPT as a potential therapeutic agent for tumor metastasis and tumor growth of melanoma carcinoma.

Anti-cancer, anti-diabetic and other pharmacologic and biological activities of penta-galloyl-glucose

1, 2, 3, 4, 6-penta-O-galloyl-beta-D-glucose (PGG) is a polyphenolic compound highly enriched in a number of medicinal herbals. Several in vitro and a handful of in vivo studies have shown that PGG exhibits multiple biological activities which implicate a great potential for PGG in the therapy and prevention of several major diseases including cancer and diabetes. Chemically and functionally, PGG appears to be distinct from its constituent gallic acid or tea polyphenols. For anti-cancer activity, three published in vivo preclinical cancer model studies with PGG support promising efficacy to selectively inhibit malignancy without host toxicity. Potential mechanisms include anti-angiogenesis; anti-proliferative actions through inhibition of DNA replicative synthesis, S-phase arrest, and G(1) arrest; induction of apoptosis; anti-inflammation; and anti-oxidation. Putative molecular targets include p53, Stat3, Cox-2, VEGFR1, AP-1, SP-1, Nrf-2, and MMP-9. For anti-diabetic activity, PGG and analogues appear to improve glucose uptake. However, very little is known about the absorption, pharmacokinetics, and metabolism of PGG, or its toxicity profile. The lack of a large quantity of highly pure PGG has been a bottleneck limiting in vivo validation of cancer preventive and therapeutic efficacies in clinically relevant models.

Ursolic acid inhibits IL-1beta or TNF-alpha-induced C6 glioma invasion through suppressing the association ZIP/p62 with PKC-zeta and downregulating the MMP-9 expression

Ursolic acid (UA), a constant constituent of Rosmarinus officinalis extracts, is a triterpenoid compound which has been shown to have antioxidant and anticarcinogenic properties. In the present study, we found that UA was able to reduce interleukin-1 beta (IL-1beta) or tumor necrosis-alpha (TNF-alpha)-induced rat C6 glioma cell invasion, which was examined by a reconstituted basement membrane in a set of transwell chambers. However, the inhibitory effect of UA did not influence cell proliferation or cause cell cytotoxity. The results analyzed by zymography assay and Western blotting revealed that the activity and expression of matrix metalloproteinase-9 (MMP-9) was eliminated by UA in a dose-dependent manner. Because MMP-9 is the target gene of the transcription factor nuclear factor-kappaB (NF-kappaB), we further investigated the effect of UA on the activity of NF-kappaB. As expected, UA upregulated the levels of IkappaBalpha (IkappaBalpha) and attenuated the nuclear translocation of p65. Furthermore, UA suppressed the IL-1beta or TNF-alpha-induced activation of protein kinase C-zeta (PKC-zeta). Our data showed UA potently inhibited the association of ZIP/p62 and PKC-zeta. Taken together, we demonstrated that UA could efficiently inhibit the interaction of ZIP/p62 and PKC-zeta. It also further suppressed the activation of NF-kappaB and downregulation of the MMP-9 protein, which in turn contributed to its inhibitory effects on IL-1beta or TNF-alpha-induced C6 glioma cell invasion. These results all showcase the potential UA has in the chemoprevention and treatment of cancer metastasis and invasion.

Penta-O-galloyl-beta-D-glucose suppresses prostate cancer bone metastasis by transcriptionally repressing EGF-induced MMP-9 expression

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of cancer-related death of men in the United States. Epidermal growth factor (EGF) generated from bone tissue contributes to prostate cancer metastasis through stimulating matrix metalloproteinase (MMP) secretions from prostate cancer cells. In this study, in vitro invasion assay was performed by incubating penta-O-galloyl-beta-D-glucose (5GG) at various concentrations with 2 x 10(4) PC-3 cells for 48 h. The anti-invasive and cytotoxic effects of 5GG were found and evaluated on the human androgen-independent prostate cancer PC-3 cell line by MTT assays and Western blot analyses. 5GG inhibited the EGF-induced cell invasiveness and MMP-9 expression in a dose- and time-dependent manner by reducing the MMP-9 transcriptional activity. To explore the mechanisms for the 5GG-mediated regulation of MMP-9, we further examined the effects of 5GG on transcription factors, including NF-kappaB, AP-1, and mitogen-activated protein kinase (MAPK) activities. The results showed that 5GG suppressed the EGF-induced NF-kappaB nuclear translocation and also abrogated the EGF-induced activation of c-jun N-terminal kinase (JNK), an upstream modulator of NF-kappaB. Moreover, we showed that 5GG reduced EGFR expression through the proteasome pathway. These results suggest that 5GG may exert at least part of its anti-invasive effect in androgen-independent prostate cancer by controlling MMP-9 expression through the suppression of the EGFR/JNK pathway. Finally, 5GG suppresses invasion and tumorigenesis in nude mice treatment with intratibia injection of PC-3 cells. These in vitro and in vivo results suggest that 5GG may be a therapeutic candidate for the treatment of advanced prostate cancer.

JunB is a repressor of MMP-9 transcription in depolarized rat brain neurons

Matrix Metalloproteinase-9 (MMP-9) is an extracellularly operating enzyme involved in the synaptic plasticity, hippocampal-dependent long term memory and neurodegeneration. Previous studies have shown its upregulation following seizure-evoking stimuli. Herein, we show that in the rat brain, MMP-9 mRNA expression in response to pentylenetetrazole-evoked neuronal depolarization is transient. Furthermore, we demonstrate that in the rat hippocampus neuronal activation strongly induces JunB expression, simultaneously leading to an accumulation of JunB/FosB complexes onto the -88/-80 bp site of the rat MMP-9 gene promoter in vivo. Surprisingly, manipulations with JunB expression levels in activated neurons revealed its moderate repressive action onto MMP-9 gene expression. Therefore, our study documents the active repressive influence of AP-1 onto MMP-9 transcriptional regulation by the engagement of JunB.

Carvedilol, a pharmacological antioxidant, inhibits neointimal matrix metalloproteinase-2 and -9 in experimental atherosclerosis

Matrix metalloproteinase (MMP) is critical to the progression of atherosclerosis and neointima hyperplasia after vascular injury. We investigated the effects of carvedilol, a pharmacological antioxidant with alpha- and beta-adrenergic blocking activity, on MMP-2 and MMP-9 expression. Vascular injury was induced with the balloon catheters on abdominal aortas of high-cholesterol-fed rabbits. On Day 21, there was significant aortic neointima formation with increased oxidative DNA damage by immunostaining with 8-hydroxy-2'-deoxyguanosine and enhanced MMP-2 and MMP-9 expressions by Western blotting, which were significantly reduced by oral administration of carvedilol (20 mg/kg/day) or probucol (100 mg/kg/day). Vascular expression (by Western blot), activity (by gelatin zymography), and mRNA levels of MMP-2 and MMP-9 were also reduced by carvedilol or probucol. Besides, pretreatment with carvedilol or probucol but not propranolol, a beta-blocker, or prazocin, an alpha-blocker, inhibited tumor necrosis factor-alpha-stimulated expressions and activities of MMP-2 and MMP-9 in human aortic smooth muscle cells. On electrophoretic mobility-shift assay, carvedilol inhibited the binding activities of activator protein-1 and specific protein-1, two major transcription factors for MMP promoter regions. Accordingly, carvedilol, a pharmacological antioxidant, inhibited in vivo and in vitro expression of MMP-2 and MMP-9 properly by modulating the redox-related pathways, suggesting its potential clinical implications.

Filamin A-mediated down-regulation of the exchange factor Ras-GRF1 correlates with decreased matrix metalloproteinase-9 expression in human melanoma cells

The actin-binding protein filamin A (FLNa) is associated with diverse cellular processes such as cell motility and signaling through its scaffolding properties. Here we examine the effect of FLNa on the regulation of signaling pathways that control the expression of matrix metalloproteinases (MMPs). The lack of FLNa in human M2 melanoma cells was associated with constitutive and phorbol ester-induced expression and secretion of active MMP-9 in the absence of MMP-2 up-regulation. M2 cells displayed stronger MMP-9 production and activity than their M2A7 counterparts where FLNa had been stably reintroduced. Using an MMP-9 promoter construct (pMMP-9-Luc), in vitro kinase assays, and genetic and pharmacological approaches, we demonstrate that FLNa mediated transcriptional down-regulation of pMMP-9-Luc by suppressing the constitutive hyperactivity of the Ras/MAPK extracellular signal-regulated kinase (ERK) cascade. Experimental evidence indicated that this phenomenon was associated with destabilization and ubiquitylation of Ras-GRF1, a guanine nucleotide exchange factor that activates H-Ras by facilitating the release of GDP. Ectopic expression of Ras-GRF1 was accompanied by ERK activation and elevated levels of MMP-9 in M2A7 cells, whereas a catalytically inactive dominant negative Ras-GRF1, which prevented ERK activation, reduced MMP-9 expression in M2 cells. Our results indicate that expression of FLNa regulates constitutive activation of the Ras/ERK pathway partly through a Ras-GRF1 mechanism to modulate the production of MMP-9.

Pentagalloylglucose inhibits estrogen receptor alpha by lysosome-dependent depletion and modulates ErbB/PI3K/Akt pathway in human breast cancer MCF-7 cells

Estrogens and estrogen receptors (ER) play important roles in estrogen-dependent and ER-positive breast cancer development. Inhibitors against estrogen biosynthesis or anti-estrogens have been used in breast cancer treatment for many years. The aim of this study was to determine whether pentagalloylglucose (5GG) has inhibitory effects on ER function. In the present study, we found that 5GG significantly reduced the growth of estrogen-responsive human breast cancer MCF-7 cells, and suppressed the phosphorylation and protein level of estrogen receptor alpha (ERalpha). Interestingly, 5GG decreased ERalpha protein levels by promoting the degradation of ERalpha protein in the lysosome. The ERalpha can be activated through a ligand-dependent and/or a ligand-independent pathway. The activated Akt kinase was shown to directly phosphorylate ERalpha at its serine residues and cause ligand independent activation. Our results showed that 5GG might inhibit the phosphatidylinositol 3-kinase (PI3K)/Akt pathway either through directly inhibiting Akt kinase activity or through inhibiting phosphorylation of the upstream receptor tyrosine kinases. The depletion of ErbB family receptors, including epidermal growth factor receptor (EGFR), ErbB2, and ErbB3, was also observed. 5GG treatment also led to a dose-dependent decrease in the expression of the estrogen-activated cyclin D1 expression. These findings suggested that 5GG might be a useful chemopreventive or therapeutic agent for hormone-dependent breast cancer through suppressing the functions of ERalpha by lysosome-dependent depletion and modulating the ErbB/PI3K/Akt pathway.

Collagenase-3 (MMP-13) expression in cutaneous malignant melanoma

BACKGROUND

Matrix metalloproteases (MMPs), enzymes with the ability to degrade the extracellular matrix, play an important role in tissue invasion by cutaneous malignant melanoma (CMM). One specific MMP, collagenase-3 (MMP-13), is thought to have a key function in the activation of MMP.

AIMS

To evaluate the expression of MMP-13 in CMM and assess its possible relationship to clinical and pathological parameters.

METHODS

MMP-13 expression was analyzed in 51 paraffin-embedded tumor samples from patients with invasive CMM, ten samples from in situ melanomas, and in eight samples from benign lesions (three dermal melanocytic nevi, three compound melanocytic nevi and two atypical melanocytic nevi) using immunohistochemical techniques. The median follow-up period in patients with invasive CMM was 50 months.

RESULTS

Benign lesions were consistently negative for MMP-13, whereas three of the ten in situ melanomas (30%) and 23 of the 51 invasive CMMs (45%) showed positive immunostaining for MMP-13. The percentage of MMP-13-positive tumors correlated significantly and positively with the mitotic index (p=0.002) in invasive CMM. However, our results did not show any significant association between tumoral MMP-13 expression and relapse-free survival in patients with invasive CMM.

CONCLUSIONS

MMP-13 appears to be a factor associated with tumor aggressiveness in CMM. It seems to eliminate an important barrier not only against tumoral invasion but also against proliferation.

In Vitro Antiviral Activity of 1,2,3,4,6-Penta-O-galloyl-.BETA.-D-glucose against Hepatitis B Virus

This study examined the antiviral activity of the root of Paeonia lactiflora PALL. Among the solvent fractions of the crude drug, the ethyl acetate fraction showed anti-hepatitis B virus (HBV) activity (IC50, 8.1 microg/ml) in an HBV-producing HepG2.2.15 cell culture system. The active anti-HBV principle was isolated and identified as 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) from the crude drug by activity-guided fractionation. PGG isolated from P. lactiflora was examined for the inhibition of HBV multiplication by measurement of HBV DNA and hepatitis B surface antigen (HBsAg) levels in the extracellular medium of HepG2.2.15 cells after 8-d treatment. PGG decreased the level of extracellular HBV (IC50, 1.0 microg/ml) in a dose-dependent manner. PGG also reduced the HBsAg level by 25% at a concentration of 4 microg/ml. The gallate structure of PGG may play a critical role in the inhibition of anti-HBV activity. These results suggest that PGG could be a candidate for developing an anti-HBV agent.

Transcriptional profiling of a mouse model for Lafora disease reveals dysregulation of genes involved in the expression and modification of proteins

Lafora's progressive myoclonus epilepsy (Lafora disease: LD) is caused by mutations in the EPM2A or NHLRC1 gene, but cellular mechanisms of the pathogenesis remain unclear. In an attempt to understand and elucidate the disease pathway, we have investigated the global gene expression profile in a mouse model for LD that developed a phenotype similar to that observed in human patients, including presence of Lafora bodies, neurodegeneration and profound neurological disturbances. We found 62 differentially expressed genes in the Epm2a knockout mice brains. These genes encode factors involved in protein catabolism, phosphatase, transcription factors, and molecules involved in protein translation, and homeostasis. The two largest functional groups of mRNAs that showed altered expression were predicted to be involved in post-translational modification of proteins and transcriptional regulation, suggesting that defects in protein activity and/or turnover may be the key trigger in the pathophysiology of LD. Furthermore we show that changes in gene expression are not limited to brain and are seen in other organs that develop Lafora bodies. Our study may provide valuable insights into the pathophysiology of LD and may aid in developing potential therapeutic targets.

Farnesyltransferase inhibitor SCH-66336 downregulates secretion of matrix proteinases and inhibits carcinoma cell migration

The ras oncogenes are among those most frequently found in human cancers. Blocking Ras farnesylation is a promising strategy for arresting cancer growth. Ras activates several signaling pathways with key roles in cellular proliferation, invasion, metastasis and angiogenesis. Furthermore, proteolytic activities of matrix proteinases such as urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) are regulated by Ras isoforms. Thus, we investigated the effects of SCH-66336, a farnesyltransferase inhibitor, on secretion of components of the plasminogen activation system as well as on the gelatinases MMP-2 and MMP-9, which play pivotal roles in matrix remodeling. SCH-66336 up to 5 microM did not significantly alter the viability of prostate (PC-3) and renal (Caki-1) cancer cells incubated in serum-depleted medium. SCH-66336 partly inhibited the processing of H-Ras, while levels of mature N-Ras and K-Ras remained unaffected. Under these noncytotoxic conditions, uPA and tPA levels were lowered in culture medium but raised in cell lysates, suggesting inhibition of trafficking pathways. In contrast, SCH-66336 had no effect on uPAR expression or on secreted PAI-1 levels. As expected, the reduction of uPA and tPA activities by SCH-66336 inhibited the conversion of plasminogen to plasmin by about 25% in PC-3 cells. SCH-66336 also inhibited the levels of secreted pro-MMP-2 and pro-MMP-9 as well as the release of their inhibitors TIMP-1 and TIMP-2. SCH-66336 decreased both the adhesion and even more so the migration of PC-3 cells on gelatin. Thus, SCH-66336 inhibited farnesylation in both cancer cell types, and H-Ras functions should be reduced by the drug. In addition, the lower levels of secreted proteinases in the presence of SCH-66336 suggest that reduced matrix remodeling and cell migration should occur in treated tumors.

Carnosol inhibits the invasion of B16/F10 mouse melanoma cells by suppressing metalloproteinase-9 through down-regulating nuclear factor-kappaB and c-Jun

Carnosol, a constant constituent of Rosmarinus officinalis extracts, is a phenolic diterpene shown to have antioxidant and anticarcinogen properties. In our studies, carnosol inhibited the invasion of highly metastatic mouse melanoma B16/F10 cells in vitro. First, the antimetastatic potentials of carnosol were examined by soft agar colony formation assay. Second, carnosol dose-dependently inhibited B16/F10 cell migration and invasion by in vitro transwell assay. Third, the decreasing activity of metalloproteinase was observed by zymographic assay. The result revealed that the treatment of carnosol could diminish the activity of MMP-9 more than MMP-2. Next, we analyzed the amounts of MMP-9 and MMP-2 proteins in the cells. The data indicated MMP-9 protein was also suppressed by carnosol in the same manner. In accordance with the above data, the results of reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed a reduced level of MMP-9 mRNA. Furthermore, carnosol significantly inhibited the tyrosine phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, AKT, p38, JNK and inhibition of activation of transcription factors NFkappa-B and c-Jun. These results lead us to conclude that carnosol could restrict the invasive ability of B16/F10 mouse melanoma cells by reducing MMP-9 expression and activity through suppressing (ERK) 1/2, AKT, p38, and JNK signaling pathway and inhibition of NF-kappaB and AP-1 binding activity. Taken together, these results indicate that carnosol targets MMP-mediated cellular events in cancer cells and provides a new mechanism for its anticancer activity.

Inhibitory effect of emodin on tumor invasion through suppression of activator protein-1 and nuclear factor-kappaB

3-Methyl-1,6,8-trihydroxyanthraquinone (emodin) is an active component from the rhizome of Rheum palmatum, a widely used traditional Chinese herb. In this study, we found that emodin significantly inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced in vitro invasion of human cancer cells including HSC5 and MDA-MB-231 cells. Matrix metalloproteinases (MMPs) are known to be associated with cancer invasion. Zymographic analysis showed that emodin suppressed TPA-induced MMP-9 activity in a concentration-dependent manner. We further demonstrated that emodin reduced the transcriptional activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), two important nuclear transcription factors involved in MMP-9 expression. Emodin suppressed the phosphorylation of two mitogen-activated protein kinases, extracellular signal-regulated protein kinase and c-Jun N-terminal kinase, but not p38 kinase, leading to reduced c-Jun phosphorylation and AP-1 DNA-binding. Moreover, emodin inhibited TPA-induced degradation of inhibitor of kappaBalpha, nuclear translocation of p65, and NF-kappaB DNA-binding activity. Taken together, these results suggest that emodin inhibits the invasiveness of human cancer cells by suppressing MMP-9 expression through inhibiting AP-1 and NF-kappaB signaling pathways.

Induction of G1 arrest and apoptosis in human jurkat T cells by pentagalloylglucose through inhibiting proteasome activity and elevating p27Kip1, p21Cip1/WAF1, and Bax proteins

Pentagalloylglucose, which is found in many medicinal plants, can arrest the cell cycle at G(1) phase through down-regulation of cyclin-dependent kinases 2 and 4 and up-regulation of the cyclin-dependent kinase inhibitors p27(Kip1) and p21(Cip1/WAF1) in human breast cancer cells. Pentagalloylglucose also induces apoptosis in human leukemic cells. However, the mechanisms by which pentagalloylglucose induces these effects is unclear. We now show that pentagalloylglucose inhibits the activities of purified 20 and 26 S proteasomes in vitro, the 26 S proteasome in Jurkat T cell lysates, and chymotrypsin-like activity of the 26 S proteasome in intact Jurkat T cells. The turnover of p27(Kip1) and p21(Cip1/WAF1), which is necessary for cell cycle progression mediated by proteasome degradation, was disrupted by treatment of human Jurkat T cells with pentagalloylglucose. This was shown by cycloheximide treatment and in vivo pulse-chase labeling experiments, and this effect correlated with the arrest of proliferation of Jurkat T cells at G(1). Inhibition of the proteasome by pentagalloylglucose and by the proteasome inhibitor MG132 caused accumulation of ubiquitin-tagged proteins in Jurkat T cells. The addition of pentagalloylglucose to Jurkat T cells enhanced the stability of the proteasome substrate Bax and increased cytochrome c release and apoptosis. Our findings suggest a mechanism for the effect of pentagalloylglucose on the cell cycle in human leukemic cells: that pentagalloylglucose down-regulates proteasome-mediated pathways because it is a proteasome inhibitor.

Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 activity by 1,2,3,4,6-Penta-O-galloyl-β-D-glucose in murine macrophage cells

Activated macrophages express inducible isoforms of nitric oxide synthase (iNOS) and cyclooxygenase (COX-2), and produce excessive amounts of nitric oxide (NO) and prostaglandin E2 (PGE2), which play key roles in the processes of inflammation and carcinogenesis. The root of Paeonia lactiflora Pall., and the root cortex of Paeonia suffruticosa Andr., are important Chinese crude drugs used in many traditional prescriptions. 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) is a major bioactive constituent of both crude drugs. PGG has been shown to possess potent anti-oxidant, anti-mutagenic, anti-proliferative and anti-invasive effects. In this study, we examined the inhibitory effects of 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG) isolated from the root of Paeonia lactiflora Pall. on the COX-2 and iNOS activity in LPS-activated Raw 264.7 cells, COX-1 in HEL cells. To investigate the structure-activity relationships of gallate and gallic acid for the inhibition of iNOS and COX-2 activity, we also examined (-)-epigallocatechin gallate (EGCG), gallic acid, and gallacetophenone. The results of the present study indicated that PGG, EGCG, and gallacetophenone treatment except gallic acid significantly inhibited LPS-induced NO production in LPS-activated macrophages. All of the four compounds significantly inhibited COX-2 activity in LPS-activated macrophages. Among the four compounds examined, PGG revealed the most potent in both iNOS (IC50 approximately 18 microg/mL) and COX-2 inhibitory activity (PGE2: IC50 approximately 8 microg/mL and PGD2: IC50 approximately 12 microg/mL), respectively. Although further studies are needed to elucidate the molecular mechanisms and structure-activity relationship by which PGG exerts its inhibitory actions, our results suggest that PGG might be a candidate for developing anti-inflammatory and cancer chemopreventive agents.