2′,4′,6′-Tris(methoxymethoxy) chalcone attenuates hepatic stellate cell proliferation by a heme oxygenase-dependent pathway

Dihydroconiferyl Ferulate Isolated from Dendropanax morbiferus H.Lév. Suppresses Stemness of Breast Cancer Cells via Nuclear EGFR/c-Myc Signaling

Breast cancer is the leading cause of global cancer incidence and breast cancer stem cells (BCSCs) have been identified as the target to overcome breast cancer in patients. In this study, we purified a BCSC inhibitor from Dendropanax morbiferus H.Lév. leaves through several open column and high-performance liquid chromatography via activity-based purification. The purified cancer stem cell (CSC) inhibitor was identified as dihydroconiferyl ferulate using nuclear magnetic resonance and mass spectrometry. Dihydroconiferyl ferulate inhibited the proliferation and mammosphere formation of breast cancer cells and reduced the population of CD44^high/CD24^low cells. Dihydroconiferyl ferulate also induced apoptosis, inhibited the growth of mammospheres and reduced the level of total and nuclear EGFR protein. It suppressed the EGFR levels, the interaction of Stat3 with EGFR, and c-Myc protein levels. Our findings show that dihydroconiferyl ferulate reduced the level of nuclear epidermal growth factor receptor (EGFR) and induced apoptosis of BCSCs through nEGFR/Stat3-dependent c-Myc deregulation. Dihydroconiferyl ferulate exhibits potential as an anti-CSC agent through nEGFR/Stat3/c-Myc signaling.

Polyphenolic molecules targeting STAT3 pathway for the treatment of cancer

Cancer is accounted as the second-highest cause of morbidity and mortality throughout the world. Numerous preclinical and clinical investigations have consistently highlighted the role of natural polyphenolic compounds against various cancers. A plethora of potential bioactive polyphenolic molecules, primarily flavonoids, phenolic acids, lignans and stilbenes, have been explored from the natural sources for their chemopreventive and chemoprotective activities. Moreover, combinations of these polyphenols with current chemotherapeutic agents have also demonstrated their strong role against both progression and resistance of malignancies. Signal transducer and activator of transcription 3 (STAT3) is a ubiquitously-expressed signaling molecule in almost all body cells. Thousands of literatures have revealed that STAT3 plays significant roles in promoting the cellular proliferation, differentiation, cell cycle progression, metastasis, angiogenesis and immunosuppression as well as chemoresistance through the regulation of its downstream target genes such as Bcl-2, Bcl-xL, cyclin D1, c-Myc and survivin. For its key role in cancer development, researchers considered STAT3 as a major target for cancer therapy that mainly focuses on abrogating the expression (activation or phosphorylation) of STAT3 in tumor cells both directly and indirectly. Polyphenolic molecules have explicated their protective actions in malignant cells via targeting STAT3 both in vitro and in vivo. In this article, we reviewed how polyphenolic compounds as well as their combinations with other chemotherapeutic drugs inhibit cancer cells by targeting STAT3 signaling pathway.

Paeoniflorin modulates oxidative stress, inflammation and hepatic stellate cells activation to alleviate CCl4-induced hepatic fibrosis by upregulation of heme oxygenase-1 in mice

OBJECTIVES

The role of Paeoniflorin on hepatic fibrosis and the specific mechanisms has not yet been elucidated. Therefore, we explored whether Paeoniflorin exerted protective effects on carbon tetrachloride (CCl4)-induced hepatic fibrosis and the underlying mechanisms.

METHODS

A model of hepatic fibrosis was induced by intraperitoneally injecting with CCl4 (10% 5 μl/g) twice a week for 7 weeks. To explore the effects of Paeoniflorin, mice were treated with Paeoniflorin (100 mg/kg) by gavage once a day at 1 week after modeling until they were sacrificed.

KEY FINDINGS

Paeoniflorin remarkably improved liver function and histopathological changes of hepatic tissues in CCl4-induced liver injury. Besides, the serum MAO enzyme activity and hydroxyproline contents were notably decreased following the intervention of Paeoniflorin. The decreased expression of Vimentin, α-SMA, Col1a and Desmin manifested the inhibition of the hepatic stellate cells (HSCs) activation. Interestingly, Paeoniflorin intervention significantly upregulated the expression of heme oxygenase-1, and attenuated the inflammatory cytokines production as well as the CCl4-induced oxidative stress imbalance.

CONCLUSIONS

Paeoniflorin could effectively alleviate CCl4-induced hepatic fibrosis by upregulation of heme oxygenase-1, and it might be a new effective option for the comprehensive treatment of hepatic fibrosis.

A new chalcone derivative, 3-phenyl-1-(2,4,6-tris(methoxymethoxy)phenyl)prop-2-yn-1-one), inhibits phorbol ester-induced metastatic activity of colorectal cancer cells through upregulation of heme oxygenase-1

Chalcone (1,3-diphenyl-2-propen-1-one) derivatives exert anti-cancer activity by targeting key molecules that can lead to carcinogenesis. We synthesized the chalcone derivative 3-phenyl-1-(2,4,6-tris(methoxymethoxy)phenyl)prop-2-yn-1-one (KB-34) and previously reported its anti-inflammatory activity in macrophages. In this study, we examined the anti-metastatic activity of KB-34 against human colorectal cancer (CRC) cells and elucidated its underlying molecular mechanisms. KB-34 treatment significantly inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced migration, as well as the invasion and proliferation of CRC cells (HT-29 and SW620). TPA-induced activation of NF-κB was also markedly suppressed by KB-34 in HT-29 cells. KB-34 suppressed the expression of matrix metalloproteinase-7 (MMP-7) at both the mRNA and protein levels in TPA-stimulated CRC cells (HT-29 and SW620). We also demonstrated that induced heme oxygenase-1 (HO-1) expression in CRC cells (HT-29 and SW620) and HO-1 is required for KB-34-mediated suppression of the expression of MMP-7 in TPA-stimulated HT-29 cells. Additionally, the cyclin-dependent kinase inhibitor p21 was significantly induced by treatment with KB-34 in CRC cells (HT-29 and SW620). Knockdown of HO-1 prevented the induction of p21 expression by KB-34 in HT-29 cells. Furthermore, we also demonstrated that 5-fluorouracil (5-FU) together with KB-34 produced a significantly greater inhibition of growth and stimulation of apoptosis of HT-29 cells than did 5-FU alone. In conclusion, KB-34 inhibits the TPA-stimulated metastatic potential of HT-29 cells by induction of HO-1 and may be a promising anti-cancer agent in chemotherapeutic strategies for CRC.

3,5-Diethoxy-3'-Hydroxyresveratrol (DEHR) Ameliorates Liver Fibrosis via Caveolin-1 Activation in Hepatic Stellate Cells and in a Mouse Model of Bile Duct Ligation Injury

Hepatic stellate cells (HSCs) are involved in the pathogenesis of liver fibrosis. Resveratrol, 3,5,4′-trihydroxystilbene, is a dietary polyphenol found in natural food products. Here, we evaluated the anti-proliferative effects of a synthetic resveratrol derivative, 3,5-diethoxy-3′-hydroxyresveratrol (DEHR), on HSCs. Flow cytometry and Western blot analyses showed that DEHR induces apoptosis through the upregulation of cleaved caspase-3 and poly (ADP-ribose) polymerase expression and reduction in the level of an anti-apoptotic protein B-cell lymphoma 2 (Bcl2). As caveolin-1 (CAV1), a competitive inhibitor of heme oxygenase 1 (HO-1), is related to apoptotic proteins in hepatic cells, we focused on the role of CAV1 in DEHR-induced apoptosis in HSCs through Western blot analyses. Our results showed that the inhibitory effect of DEHR on cell viability was stronger in HO-1 siRNA-transfected cells but weakened in CAV1 siRNA-transfected cells. Collagen concentration was significantly reduced, whereas CAV1 expression increased after treatment of a bile duct ligation injury-induced liver fibrosis model with DEHR for four weeks. We confirmed that DEHR treatment significantly reduced fibrous hyperplasia around the central veins, using hematoxylin and eosin and Sirius red staining. DEHR ameliorates liver fibrosis in vitro and in vivo, possibly through a mechanism involving CAV1.

Molecular chemotherapeutic potential of butein: A concise review

Butein is a biologically active flavonoid isolated from the bark of Rhus verniciflua Stokes, which is known to have therapeutic potential against various cancers. Notably, butein inhibits cancer cell growth by inducing G₂/M phase arrest and apoptosis. Butein-induced G₂/M phase arrest is associated with increased phosphorylation of ataxia telangiectasia mutated (ATM) and Chk1/2, and consequently, with reduced cdc25C levels. In addition, butein-induced apoptosis is mediated through the activation of caspase-3, which is associated with changes in the expression of Bcl-2 and Bax proteins. Intriguingly, butein sensitizes cells to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis via ERK-mediated Sp1 activation, which promotes the transcription of specific death receptor 5. Butein also inhibits the migration and invasion of human cancer cells by suppressing nuclear factor-κB- and extracellular signal-regulated kinases 1/2-mediated expression of matrix metalloproteinase-9 and vascular endothelial growth factor. Additionally, butein downregulates the expression of human telomerase reverse transcriptase and causes a concomitant decrease in telomerase activity. These findings provide the basis for the pharmaceutical development of butein. The aim of this review is to provide an update on the mechanisms underlying the anticancer activity of butein, with a special focus on its effects on different cellular signaling cascades.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

Calanquinone A induces anti-glioblastoma activity through glutathione-involved DNA damage and AMPK activation

Glioblastoma, a highly malignant glioma, is resistant to both radiation and chemotherapy and is an intractable problem in clinical treatment. New therapeutic approaches are in urgent need. Calanquinone A, an herbal constituent, displayed anti-proliferative activity against glioblastoma cells, including A172, T98 and U87. Flow cytometric analysis showed an S phase arrest and a subsequent apoptosis to calanquinone A action. Further identification demonstrated a rapid increase of γH2A.X formation at S phase. The data together with comet tail formation and Chk1 activation indicated DNA damage response. N-acetyl cysteine (an antioxidant and a glutathione precursor) and exogenously applied glutathione, but not trolox (an antioxidant), completely abolished calanquinone A-induced effects. Immunofluorescence assay revealed that calanquinone A decreased the intracellular glutathione levels in both A172 and T98 cells. However, calanquinone A, by itself, did not conjugate glutathione. The data suggested that the decrease of cellular glutathione predominantly contributed to the anticancer mechanism. Furthermore, calanquinone A induced the activation of AMP-activated protein kinase (AMPK) and the inhibition of p70S6K activity. Rhodamine efflux assay showed that calanquinone A did not block efflux activity, indicating that calanquinone A was not a P-glycoprotein substrate. In summary, the data suggest that calanquinone A displays anti-glioblastoma activity through a decrease of cellular glutathione levels that subsequently induces DNA damage stress and AMPK activation, leading to cell cycle arrest at S-phase and apoptotic cell death. Furthermore, calanquinone A does not serve as a P-glycoprotein substrate, suggesting a potential for further development in anti-glioblastoma therapy.

Targeting the STAT3 signaling pathway in cancer: role of synthetic and natural inhibitors

Signal transducers and activators of transcription (STATs) comprise a family of cytoplasmic transcription factors that mediate intracellular signaling that is usually generated at cell surface receptors and thereby transmit it to the nucleus. Numerous studies have demonstrated constitutive activation of STAT3 in a wide variety of human tumors, including hematological malignancies (leukemias, lymphomas, and multiple myeloma) as well as diverse solid tumors (such as head and neck, breast, lung, gastric, hepatocellular, colorectal and prostate cancers). There is strong evidence to suggest that aberrant STAT3 signaling promotes initiation and progression of human cancers by either inhibiting apoptosis or inducing cell proliferation, angiogenesis, invasion, and metastasis. Suppression of STAT3 activation results in the induction of apoptosis in tumor cells, and accordingly its pharmacological modulation by tyrosine kinase inhibitors, antisense oligonucleotides, decoy nucleotides, dominant negative proteins, RNA interference and chemopreventive agents have been employed to suppress the proliferation of various human cancer cells in culture and tumorigenicity in vivo. However, the identification and development of novel drugs that can target deregulated STAT3 activation effectively remains an important scientific and clinical challenge. This review presents the evidence for critical roles of STAT3 in oncogenesis and discusses the potential for development of novel cancer therapies based on mechanistic understanding of STAT3 signaling cascade.

Butein inhibits ethanol-induced activation of liver stellate cells through TGF-β, NFκB, p38, and JNK signaling pathways and inhibition of oxidative stress

BACKGROUND

Butein has been reported to prevent and partly reverse liver fibrosis in vivo; however, the mechanisms of its action are poorly understood. We, therefore, aimed to determine the antifibrotic potential of butein.

METHODS

We assessed the influence of the incubation of hepatic stellate cells (HSCs) and hepatoma cells (HepG2) with butein on sensitivity to ethanol- or acetaldehyde-induced toxicity; the production of reactive oxygen species (ROS); the expression of markers of HSC activation, including smooth muscle α-actin (α-SMA) and procollagen I; and the production of transforming growth factor-β1 (TGF-β1), metalloproteinases-2 and -13 (MMP-2and MMP-13), and tissue inhibitors of metalloproteinases (TIMPs). The influence of butein on intracellular signals in HSCs; i.e., nuclear factor-κB (NFκB), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK) induced by ethanol was estimated.

RESULTS

Butein protected HSCs and HepG2 cells against ethanol toxicity by the inhibition of ethanol- or acetaldehyde-induced production of ROS when cells were incubated separately or in co-cultures; butein also inhibited HSC activation measured as the production of α-SMA and procollagen I. As well, butein downregulated ethanol- or acetaldehyde-induced HSC migration and the production of TGF-β, TIMP-1, and TIMP-2; decreased the activity of MMP-2; and increased the activity of MMP-13. In ethanol-induced HSCs, butein inhibited the activation of the p38 MAPK and JNK transduction pathways as well as significantly inhibiting the phosphorylation of NF κB inhibitor (IκB) and Smad3.

CONCLUSIONS

The results indicated that butein inhibited ethanol- and acetaldehyde-induced activation of HSCs at different levels, acting as an antioxidant and inhibitor of ethanol-induced MAPK, TGF-β, and NFκB/IκB transduction signaling; this result makes butein a promising agent for antifibrotic therapies.

Synthesis and theoretical calculations of carbazole substituted chalcone urea derivatives and studies their polyphenol oxidase enzyme activity

Synthesis of carbazole substituted chalcone urea derivatives and their polyphenol oxidase enzyme activity effects on the diphenolase activity of banana tyrosinase were evaluated. Tyrosinase has been purified from banana on an affinity gel comprised of Sepharose 4B-L-tyrosine-p-aminobenzoic acid. The results showed that most of the compounds (3,4,5a,5d-h) inhibited and some of them (5c,5i-l) activated the tyrosinase enzyme activity. The molecular calculations were performed using Gaussian software for the synthesized compounds to explain the experimental results.

Betulin, betulinic acid and butein are inhibitors of acetaldehyde-induced activation of liver stellate cells

Liver fibrosis has been reported to be inhibited in vivo by oleanolic and ursolic acids; however, the activity of other triterpenes like betulin and betulinic acid has not been examined. Butein has also been reported to prevent and partly reverse liver fibrosis in vivo, although its mechanism of action is poorly understood. Therefore, the aim of this study was to determine the antifibrotic potential of butein, betulin, and betulinic acid and examine their mechanisms of action in vitro. This study was conducted in rat stellate cells (HSCs) that were treated with acetaldehyde, which is the most reactive product of ethanol metabolism. Butein, betulin, and betulinic acid were preincubated with rat HSCs at non-toxic concentrations. Treatment effects were measured in regard to acetaldehyde-induced toxicity and cell migration, and several markers of HSC activation were evaluated, including smooth muscle α-actin (α-SMA) and procollagen I expression. In addition, changes in the release of reactive oxygen species (ROS) and cytokines such as tumor necrosis factor-α (TNF-α) and tumor growth factor-β1 (TGF-β1) and changes in the production of metalloproteinase-2 (MMP-2) and tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) were determined. In vitro, HSCs were protected against acetaldehyde-induced toxicity by betulin but not by betulinic acid and butein. However, butein, betulin, and betulinic acid inhibited the production of ROS by HSCs treated with acetaldehyde and inhibited their migration. Butein also inhibited acetaldehyde-induced TGF-β1 production. Butein, betulin, and betulinic acid down-regulated acetaldehyde-induced production of TIMP-1 and TIMP-2. Betulin decreased the acetaldehyde-induced activity of MMP-2, but butein and betulinic acid did not. The results indicated that butein, betulin, and betulinic acid inhibited the acetaldehyde-induced activation of HSCs. Each drug functioned in a different manner, whereby some were acting as either antioxidants or inhibitors of TIMPs expression and butein additionally acted as an inhibitor of TGF-β production.

Evaluation of new chalcone derivatives as polyphenol oxidase inhibitors

A newly series of 4-(phenylurenyl)chalcone (4a-j) and 4'-(phenylurenyl/thiourenyl)chalcone (9a-l) derivatives were synthesized and their inhibitory effects on the diphenolase activity of banana tyrosinase were evaluated. Tyrosinase has been purified from banana on an affinity gel comprised of Sepharose 4B-l-tyrosine-p-aminobenzoic acid. The result showed that 4a-j inhibited the PPO enzyme activity. Conversely, 9a-h and 9i-l showed activator effect on tyrosinase enzyme activity.

2',4',6'-Tris(methoxymethoxy) chalcone (TMMC) attenuates the severity of cerulein-induced acute pancreatitis and associated lung injury

Acute pancreatitis (AP) is an inflammatory disease involving acinar cell injury and rapid production and release of inflammatory cytokines, which play a dominant role in local pancreatic inflammation and systemic complications. 2',4',6'-Tris (methoxymethoxy) chalcone (TMMC), a synthetic chalcone derivative, displays potent anti-inflammatory effects. Therefore, we aimed to investigate whether TMMC might affect the severity of AP and pancreatitis-associated lung injury in mice. We used the cerulein hyperstimulation model of AP. Severity of pancreatitis was determined in cerulein-injected mice by histological analysis and neutrophil sequestration. The pretreatment of mice with TMMC reduced the severity of AP and pancreatitis-associated lung injury and inhibited several biochemical parameters (activity of amylase, lipase, trypsin, trypsinogen, and myeloperoxidase and production of proinflammatory cytokines). In addition, TMMC inhibited pancreatic acinar cell death and production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 by inhibiting NF-κB and extracellular signal-regulated protein kinase 1/2 (ERK1/2) activation. Neutralizing antibodies for TNF-α, IL-1β, and IL-6 inhibited cerulein-induced cell death in isolated pancreatic acinar cells. Moreover, pharmacological blockade of NF-κB/ERK1/2 reduced acinar cell death and production of TNF-α, IL-1β, and IL-6 in isolated pancreatic acinar cells. In addition, posttreatment of mice with TMMC showed reduced severity of AP and lung injury. Our results suggest that TMMC may reduce the complications associated with pancreatitis.

Butein inhibits the migration and invasion of SK-HEP-1 human hepatocarcinoma cells through suppressing the ERK, JNK, p38, and uPA signaling multiple pathways

Liver cancer is one of the most commonly diagnosed cancers and the leading cause of death in human populations. Butein, a tetrahydroxychalcone, has been shown to induce apoptosis in many human cancer cells, but the effects of butein on the migration and invasion of human liver cancer cells are not reported. Herein, we found that butein is effective in the suppression of migration and invasion in SK-HEP-1 human hepatocarcinoma cells by using the Matrigel cell migration assay and invasion system. The gelatin zymography assay indicated that butein inhibited the activity of matrix metalloproteinases 2 (MMP-2) and MMP-9. Western blotting analysis indicated that butein decreased the levels of MMP-2, -7, and -9, uPA, Ras, Rho A, ROCK1, ERK1/2, JNK1/2, p-p38, and p-c-Jun in SK-HEP-1 cells. Furthermore, butein inhibited the NF-κB binding activity in SK-HEP-1 cells by electrophoretic mobility shift assay. We also found that butein decreased the ERK, JNK, and p38 in SK-HEP-1 cells by in vitro kinase assay. In conclusion, this is the first study to demonstrate that butein might be a novel anticancer agent for the treatment of hepatocarcinoma through inhibiting migration and invasion.

Butein, a tetrahydroxychalcone, suppresses cancer-induced osteoclastogenesis through inhibition of receptor activator of nuclear factor-kappaB ligand signaling

Osteoclastogenesis is associated with aging and various age-related inflammatory chronic diseases, including cancer. Receptor activator of nuclear factor-kappaB (NF-κB) ligand (RANKL), a member of the tumor necrosis factor superfamily, has been implicated as a major mediator of bone resorption, suggesting that agents that can suppress RANKL signaling might inhibit osteoclastogenesis, a process closely linked to bone resorption. We therefore investigated whether butein, a tetrahydroxychalcone, could inhibit RANKL signaling and suppress osteoclastogenesis induced by RANKL or tumor cells. We found that human multiple myeloma cells (MM.1S and U266), breast tumor cells (MDA-MB-231) and prostate tumor cells (PC-3) induced differentiation of macrophages to osteoclasts, as indicated by tartrate-resistant acid phosphatase (TRAP)-positive cells, and that butein suppressed this process. The chalcone also suppressed the expression of RANKL by the tumor cells. We further found that butein suppressed RANKL-induced NF-κB activation and that this suppression correlated with the inhibition of IκBα kinase and suppression of phosphorylation and degradation of IκBα, an inhibitor of NF-κB. Finally, butein also suppressed the RANKL-induced differentiation of macrophages to osteoclasts in a dose-dependent and time-dependent manner. Collectively, our results indicate that butein suppresses the osteoclastogenesis induced by tumor cells and by RANKL, by suppression of the NF-κB activation pathway.

2',4',6'-Tris(methoxymethoxy) chalcone induces apoptosis by enhancing Fas-ligand in activated hepatic stellate cells

Suppression of hepatic stellate cell (HSC) activation and proliferation, and induction of apoptosis in activated HSCs have been proposed as therapeutic strategies for the treatment and prevention of the hepatic fibrosis. We previously showed that 2',4',6'-tris(methoxymethoxy) chalcone (TMMC), a synthesized chalcone derivative, inhibits platelet-derived growth factor-induced HSC proliferation at 5-20 μM. Here, we showed that TMMC induces apoptosis in activated HSCs at higher concentrations (30-50 μM), but is not cytotoxic to primary hepatocytes. Moreover, TMMC induces hyperacetylation of histone by inhibiting histone deacetylase (HDAC) in activated HSCs. Interestingly, TMMC treatment remarkably increased Fas-ligand (FasL) mRNA expression in a dose-dependent manner. Cycloheximide treatment reversed the induction of TMMC on apoptosis, indicating that de novo protein synthesis was required for TMMC-induced apoptosis in activated HSCs. In addition, FasL synthesis by TMMC is closely associated with maximal procaspase-3 proteolytic processing. In vivo, TMMC reduced activated HSCs in CCl(4)-intoxicated rats during liver injury recovery, as demonstrated by α-smooth muscle actin expression in rat liver. TMMC treatment also resulted in apoptosis, as demonstrated by cleavage of poly(ADP-ribose) polymerase in rat liver. In conclusion, TMMC may have therapeutic potential by inducing HSC apoptosis for the treatment of hepatic fibrosis.

Dietary chalcones with chemopreventive and chemotherapeutic potential

Chalcones are absorbed in the daily diet and appear to be promising cancer chemopreventive agents. Chalcones represent an important group of the polyphenolic family, which includes a large number of naturally occurring molecules. This family possesses an interesting spectrum of biological activities, including antioxidative, antibacterial, anti-inflammatory, anticancer, cytotoxic, and immunosuppressive potential. Compounds of this family have been shown to interfere with each step of carcinogenesis, including initiation, promotion and progression. Moreover, numerous compounds from the family of dietary chalcones appear to show activity against cancer cells, suggesting that these molecules or their derivatives may be considered as potential anticancer drugs. This review will focus primarily on prominent members of the chalcone family with an 1,3-diphenyl-2-propenon core structure. Specifically, the inhibitory effects of these compounds on the different steps of carcinogenesis that reveal interesting chemopreventive and chemotherapeutic potential will be discussed.

Suppression of signal transducer and activator of transcription 3 activation by butein inhibits growth of human hepatocellular carcinoma in vivo

PURPOSE

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide and the third cause of global cancer mortality. Increasing evidence suggest that STAT3 is a critical mediator of oncogenic signaling in HCC and controls the expression of several genes involved in proliferation, survival, metastasis, and angiogenesis. Thus, the novel agents that can suppress STAT3 activation have potential for both prevention and treatment of HCC.

EXPERIMENTAL DESIGN

The effect of butein on STAT3 activation, associated protein kinases, STAT3-regulated gene products, cellular proliferation, and apoptosis was investigated. The in vivo effect of butein on the growth of human HCC xenograft tumors in male athymic nu/nu mice was also examined.

RESULTS

We tested an agent, butein, for its ability to suppress STAT3 activation in HCC cells and nude mice model along with prospectively testing the hypothesis of STAT3 inhibition in a virtual predictive functional proteomics tumor pathway technology platform. We found that butein inhibited both constitutive and inducible STAT3 activation in HCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src and Janus-activated kinase 2. Butein inhibited proliferation and significantly potentiated the apoptotic effects of paclitaxel and doxorubicin in HCC cells. When administered intraperitoneally, butein inhibited the growth of human HCC xenograft tumors in male athymic nu/nu mice.

CONCLUSIONS

Overall, cumulative results from experimental and predictive studies suggest that butein exerts its antiproliferative and proapoptotic effects through suppression of STAT3 signaling in HCC both in vitro and in vivo.

Butein downregulates chemokine receptor CXCR4 expression and function through suppression of NF-κB activation in breast and pancreatic tumor cells

The CXC chemokine receptor-4 (CXCR4), a Gi protein-coupled receptor for the ligand CXCL12/stromal cell-derived factor-1α (SDF-1α), is known to be expressed in various tumors. This receptor mediates homing of tumor cells to specific organs that express the ligand CXCL12 for this receptor and plays an important role in tumor growth, invasion, metastasis, and angiogenesis. Thus, a priori, agents that can downregulate CXCR4/CXCL12 signaling cascade have potential against cancer metastasis. In this study, we report the identification of butein (3, 4, 2', 4'-tetrahydroxychalcone) as a novel regulator of CXCR4 expression and function. We found that butein downregulated the expression of CXCR4 in HER2-overexpressing breast cancer cells in a dose- and time-dependent manner. The decrease in CXCR4 expression induced by butein was not cell type-specific as the inhibition also occurred in pancreatic, prostate, multiple myeloma, head and neck, and hepatocellular cancer cell lines. When investigated for the molecular mechanism(s), it was found that the downregulation of CXCR4 was not due to proteolytic degradation but rather to transcriptional regulation as indicated by downregulation of mRNA expression, inhibition of NF-κB activation evident by both DNA binding, and reporter assays, and suppression of chromatin immunoprecipitation activity. Suppression of CXCR4 expression by butein correlated with the inhibition of CXCL12-induced migration and invasion of both breast and pancreatic cancer cells. Overall, our results demonstrate for the first time that butein is a novel inhibitor of CXCR4 expression and thus has a potential in suppressing metastasis of cancer.

Butein sensitizes human hepatoma cells to TRAIL-induced apoptosis via extracellular signal-regulated kinase/Sp1-dependent DR5 upregulation and NF-kappaB inactivation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cell death in various types of cancer cells but has little or no effect on normal cells. Human hepatoma cells are resistant to TRAIL-induced apoptosis. Although butein is known to mediate anticancer, anti-inflammatory, and antioxidant activities, little is known about the mechanism of butein in terms of TRAIL-induced apoptosis of human hepatoma cells. In this study, we determined that butein enhances TRAIL-induced apoptosis in hepatoma cells through upregulation of DR5. Luciferase analysis showed that a 5'-flanking region containing four Sp1-binding sites within the DR5 promoter was enhanced by butein (-305/-300). Electrophoretic mobility shift assays and chromatin immunoprecipitation studies were used to analyze the elevation of Sp1 binding to DR5 promoter sites by butein. Point mutations of the Sp1-binding site also attenuated promoter activity. Furthermore, pretreatment of the blocking chimeric antibody and small interfering RNA for DR5 significantly suppressed TRAIL-mediated apoptosis by butein in Hep3B cells. Butein also stimulated extracellular signal-regulated kinase (ERK) activation, and the ERK inhibitor PD98059 blocked butein-induced DR5 expression and suppressed binding of Sp1 to the DR5 promoter. Additionally, generation of reactive oxygen species had no effect on cell viability, although pretreatment with N-acetyl-l-cysteine or glutathione inhibited combined treatment-induced reactive oxygen species. Indeed, butein repressed the TRAIL-mediated activation of NF-kappaB and decreased its transcriptional activity. Our results suggest that butein could sensitize certain human hepatoma cells to TRAIL-induced apoptosis through stimulating its death signaling and by repressing the survival function in these cells.

Butein induces G(2)/M phase arrest and apoptosis in human hepatoma cancer cells through ROS generation

We investigated the molecular effects of 3,4,2',4'-tetrahydroxychalcone (butein) treatment in two human hepatoma cancer cell lines-HepG2 and Hep3B. Butein treatment inhibited cancer cell growth by inducing G(2)/M phase arrest and apoptosis. Butein-induced G(2)/M phase arrest was associated with increased ATM, Chk1, and Chk2 phosphorylations and reduced cdc25C levels. Additionally, butein treatment enhanced inactivated phospho-Cdc2 levels, reduced Cdc2 kinase activity, and generated reactive oxygen species (ROS) that was accompanied by JNK activation. The extent of butein-induced G(2)/M phase arrest significantly decreased following pretreatment with N-acetyl-l-cysteine or glutathione and following JNK phosphorylation reduction by SP600125. Both N-acetyl-l-cysteine and glutathione also decreased butein-mediated apoptosis. Taken together, these results imply a critical role of ROS and JNK in the anticancer effects of butein.

Transcriptional regulation of hepatic stellate cells

Hepatic stellate cell (HSC) activation is a process of cellular transdifferentiation in which, upon liver injury, the quiescent vitamin A storing perisinusoidal HSC is converted into a wound-healing myofibroblast and acquires potent pro-inflammatory and pro-fibrogenic activities. This remarkable phenotypic transformation is underpinned by changes in the expression of a vast number of genes. In this review we survey current knowledge of the transcription factors that either control HSC activation or which regulate specific fibrogenic functions of the activated HSC such as collagen expression, proliferation and resistance to apoptosis.

Butein suppresses constitutive and inducible signal transducer and activator of transcription (STAT) 3 activation and STAT3-regulated gene products through the induction of a protein tyrosine phosphatase SHP-1

The aim of the current study is to determine whether butein (3,4,2',4'-tetrahydroxychalcone) exhibits antiproliferative effects against tumor cells through suppression of the signal transducer and activator of transcription 3 (STAT3) activation pathway. We investigated the effects of butein on constitutive and inducible STAT3 activation, role of tyrosine kinases and phosphatases in STAT3 activation, STAT3-regulated gene products, and growth modulation of tumor cells. We found that this chalcone inhibited both constitutive and interleukin-6-inducible STAT3 activation in multiple myeloma (MM) cells. The suppression was mediated through the inhibition of activation of the upstream kinases c-Src, Janus-like kinase (JAK) 1, and JAK2. Vanadate treatment reversed the butein-induced down-regulation of STAT3 activation, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that butein induced the expression of the tyrosine phosphatase SHP-1 and deletion of SHP-1 gene by small interfering RNA abolished the ability of butein to inhibit STAT3 activation, suggesting the critical role of SHP-1 in the action of this chalcone. Butein down-regulated the expression of STAT3-regulated gene products such as Bcl-xL, Bcl-2, cyclin D1, and Mcl-1, and this led to the suppression of proliferation and induction of apoptosis. Consistent with these results, overexpression of constitutive active STAT3 significantly reduced the butein-induced apoptosis. Moreover, we found that butein significantly potentiated the apoptotic effects of thalidomide and Velcade in MM cells. Overall, these results suggest that butein is a novel blocker of STAT3 activation and thus may have potential in suppression of tumor cell proliferation and reversal of chemoresistance in MM cells.

Structure activity relationship studies of anti-inflammatory TMMC derivatives: 4-dimethylamino group on the B ring responsible for lowering the potency

We previously synthesized 2',4',6'-tris(methoxymethoxy)chalcone (TMMC) derivatives with various substituents on the A ring that showed potent anti-inflammatory effects by inhibiting NO production in RAW 264.7 cells. The 2'-hydroxy group on the A ring could elevate the electrophilicity of Michael addition of GSH and electron donating groups on the A ring could stabilize the GSH adduct by decreasing the acidity of the alpha-hydrogen. Using this interpretation, we tested various substituents on the B ring and established a proper balance between biological activity and the position of the electron donating or electron withdrawing groups on the B ring. In this case, the 2'-hydroxy group was excluded because it could cause the formation of GSSG through a phenoxy radical and can confuse the interpretation of the biological results. Chalcone derivatives without 2'-hydroxy are likely to deplete cellular GSH levels by a Michael addition process. Strong electron donating groups on the B ring, such as 4-dimethylamino group, gave the weakest inhibition of NO production. A 4-dimethyamino group on the B ring could decrease the stability of the GSH adduct by weakening the C-S bond strength through movement of an electron pair on nitrogen via an aromatic ring.

Genistein and phycocyanobilin may prevent hepatic fibrosis by suppressing proliferation and activation of hepatic stellate cells

Hepatic fibrosis reflects hepatotoxin-mediated activation of hepatic stellate cells, resulting in their proliferation and transformation to myofibroblasts that secrete collagen. This activation is suppressed by estrogen, an effect which explains the decreased risk for hepatic fibrosis enjoyed by premenopausal women and by postmenopausal women receiving hormone replacement therapy. Since stellate cells have been found to express the beta but not the alpha isoform of the estrogen receptor, it can be predicted that nutritional intakes of the soy isoflavone genistein - a selective agonist for ERbeta in the low nanomolar plasma concentrations achievable with these intakes - have potential for suppressing hepatic fibrosis, in both men and women. The antiproliferative impact of estrogen on stellate cells is mediated at least in part by suppression of NADPH oxidase activity; oxidant production by this enzyme complex plays a crucial role in stellate cell activation. Alternatively, it may be feasible to inhibit NADPH oxidase with phycocyanobilin (PCB), a biliverdin homolog found in spirulina that has recently been shown to inhibit the NADPH oxidase activity of human cell cultures in low micromolar concentrations. Joint administration of soy isoflavones and PCB in appropriate doses might have considerable potential for prevention of hepatic fibrosis in at-risk subjects.

A novel anticancer effect of butein: inhibition of invasion through the ERK1/2 and NF-kappa B signaling pathways in bladder cancer cells

There is increasing evidence that epithelial-mesenchymal transition (EMT) plays a critical role in cancer metastasis. Butein is a polyphenolic compound, which has been found to exhibit anti-proliferation effects on cancer cells. Here, we report that in addition to its function as an anti-proliferation agent, butein can inhibit migration and invasion through the ERK1/2 and NF-kappaB signaling pathways in human bladder cancer cells, and this inhibitory effect may be associated with reversal of EMT. These results were further confirmed by RNAi-mediated suppression of NF-kappaB, which partly reverses EMT and inhibits cell invasive ability in vitro. These results suggest a novel function of butein as an invasion inhibitor in bladder cancer.

Pharmacological and clinical aspects of heme oxygenase

This review is intended to stimulate interest in the effect of increased expression of heme oxygenase-1 (HO-1) protein and increased levels of HO activity on normal and pathological states. The HO system includes the heme catabolic pathway, comprising HO and biliverdin reductase, and the products of heme degradation, carbon monoxide (CO), iron, and biliverdin/bilirubin. The role of the HO system in diabetes, inflammation, heart disease, hypertension, neurological disorders, transplantation, endotoxemia and other pathologies is a burgeoning area of research. This review focuses on the clinical potential of increased levels of HO-1 protein and HO activity to ameliorate tissue injury. The use of pharmacological and genetic probes to manipulate HO, leading to new insights into the complex relationship of the HO system with biological and pathological phenomena under investigation, is reviewed. This information is critical in both drug development and the implementation of clinical approaches to moderate and to alleviate the numerous chronic disorders in humans affected by perturbations in the HO system.

2',4',6'-tris(methoxymethoxy) chalcone protects against trinitrobenzene sulfonic acid-induced colitis and blocks tumor necrosis factor-alpha-induced intestinal epithelial inflammation via heme oxygenase 1-dependent and independent pathways

2',4',6'-Tris(methoxymethoxy) chalcone (TMMC), a synthesized chalcone derivative, displays potent antiproliferative and anti-inflammatory effects in rat hepatic stellate cells and murine macrophages, respectively. Here we tested the hypothesis that TMMC could ameliorate diseases characterized by mucosal inflammation. Treatment of mice with TMMC significantly protected against trinitrobenzene sulfonic acid (TNBS)-induced colitis, as assessed by reductions in the weight loss, colonic damage and mucosal ulceration that together characterize this symptom. Moreover, TMMC suppressed the expression of intercellular adhesion molecule-1, interleukin 1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) in the mice treated with TNBS. Pretreatment of human intestinal epithelial HT-29 cells with TMMC also significantly inhibited the IL-8 and extracellular matrix metalloproteinase-7 levels induced by TNF-alpha. TMMC induced the expression of heme oxygenase 1 (HO-1) in HT-29 cells. TMMC increased extracellular signal-regulated kinase1/2 and p38 kinase phosphorylation levels, which led to the nuclear translocation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and consequently to HO-1 expression. TMMC inhibited TNF-alpha-induced nuclear factor kappaB (NF-kappaB) activation directly and indirectly. Interestingly, the latter is mediated by HO-1, which presumably blocks the TNF-alpha-induced nuclear translocation of NF-kappaB p65 without affecting I-kappaBalpha degradation. Moreover, we found that the different products of HO-1, carbon monoxide and bilirubin, exerted anti-inflammatory effects that were additive or synergistic in HT-29 cells stimulated with TNF-alpha. Thus, TMMC might serve to protect against intestinal inflammatory diseases.

Butein, a tetrahydroxychalcone, inhibits nuclear factor (NF)-kappaB and NF-kappaB-regulated gene expression through direct inhibition of IkappaBalpha kinase beta on cysteine 179 residue

Although butein (3,4,2',4'-tetrahydroxychalcone) is known to exhibit anti-inflammatory, anti-cancer, and anti-fibrogenic activities, very little is known about its mechanism of action. Because numerous effects modulated by butein can be linked to interference with the NF-kappaB pathway, we investigated in detail the effect of this chalcone on NF-kappaB activity. As examined by DNA binding, we found that butein suppressed tumor necrosis factor (TNF)-induced NF-kappaB activation in a dose- and time-dependent manner; suppressed the NF-kappaB activation induced by various inflammatory agents and carcinogens; and inhibited the NF-kappaB reporter activity induced by TNFR1, TRADD, TRAF2, NIK, TAK1/TAB1, and IKK-beta. We also found that butein blocked the phosphorylation and degradation of IkappaBalpha by inhibiting IkappaBalpha kinase (IKK) activation. We found the inactivation of IKK by butein was direct and involved cysteine residue 179. This correlated with the suppression of phosphorylation and the nuclear translocation of p65. In this study, butein also inhibited the expression of the NF-kappaB-regulated gene products involved in anti-apoptosis (IAP2, Bcl-2, and Bcl-xL), proliferation (cyclin D1 and c-Myc), and invasion (COX-2 and MMP-9). Suppression of these gene products correlated with enhancement of the apoptosis induced by TNF and chemotherapeutic agents; and inhibition of cytokine-induced cellular invasion. Overall, our results indicated that antitumor and anti-inflammatory activities previously assigned to butein may be mediated in part through the direct inhibition of IKK, leading to the suppression of the NF-kappaB activation pathway.