Genistein inhibits tumor invasion by suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells
- Shulhn-Der Wang†5,
- Bor-Chyuan Chen2,
- Shung-Te Kao†3, 4,
- Ching-Ju Liu2 and
- Chia-Chou Yeh1, 2Email author
© Wang et al.; licensee BioMed Central Ltd. 2014
Received: 26 February 2013
Accepted: 15 January 2014
Published: 16 January 2014
Genistein (Gen) exhibits anti-mutagenic and anti-metastatic activities in hepatoma cell lines. Gen has suppressive effects on tumor growth and angiogenesis in nude mice. Gen suppresses the enzymatic activity of matrix metalloproteinase (MMP)-9; however, the mechanism underlying its anti-invasive activity on hepatocellular carcinoma (HCC) cells is unclear.
In this study, the possible mechanisms underlying Gen-mediated reduction of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced cell invasion and inhibition of secreted and cytosolic MMP-9 production in human hepatoma cells (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2) were investigated.
Gen suppressed MMP-9 transcription by inhibiting activator protein (AP)-1 and nuclear factor-κ B (NF-κB) activity. Gen suppressed TPA-induced AP-1 activity through inhibitory phosphorylation of extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and TPA-stimulated inhibition of NF-κB nuclear translocation through IκB inhibitory signaling pathways. Moreover, Gen suppressed TPA-induced activation of ERK/phosphatidylinositol 3-kinase/Akt upstream of NF-κB and AP-1.
Gen and its inhibition of multiple signal transduction pathways can control the invasiveness and metastatic potential of HCC.
KeywordsGenistein TPA Matrix metalloproteinase 9 Tumor invasion Nuclear factor-κB Activator protein 1
Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most frequent cause of cancer-related mortality worldwide, with 6,000,000 new cases diagnosed annually [1, 2]. HCC is prevalent in Sub-Saharan Africa and Southeast Asia, including Taiwan. HCC is associated with various risk factors, including chronic infection with hepatitis B or C viruses, environmental carcinogens, chronic alcohol abuse, and non-alcoholic fatty liver disease [2, 3]. HCC is a hypervascular tumor, commonly involving venous invasion, and HCC often progresses to intra- and extra-hepatic metastases . Invasion and metastasis of cancer cells are the primary causes of cancer deaths, which are complicated processes involving proteolytic enzymes that participate in the degradation of environmental barriers such as the extracellular matrix and basement membrane. Among these enzymes, the matrix metalloproteinases (MMPs), which comprise a family of zinc-dependent endopeptidases, are intimately involved in the invasion and metastasis of various tumor cells [5, 6]. The MMP family is involved in extracellular matrix degradation and is also associated with malignancy and metastasis. The MMP-9 gene is strongly expressed in invasive HCC , and the MMP-9 protein content in HCC is greater than in the surrounding liver parenchyma. Therefore, MMP-9 may be used as a marker for the invasiveness and metastatic potential of HCC . The activity of MMP-9 is tightly controlled, with regulation occurring primarily at the transcriptional level . The MMP-9 promoter is highly conserved and contains multiple functional elements, including nuclear factor-κB (NF-κB) and activator protein (AP)-1 elements [8–10].
12-O-Tetradecanoylphorbol-13-acetate (TPA) is one of the most widely used agents for studying the mechanisms of carcinogenesis . TPA exhibits numerous biological effects by altering gene expression, a process that involves activation of protein kinase C (PKC) . In addition to carcinogenesis, TPA induces MMP-9 expression via PKC-dependent activation of the Ras/extracellular signal-regulated protein kinase (ERK) signaling pathway, thus increasing the invasiveness of cell lines . Previous reports have demonstrated that TPA-activated NF-κB and AP-1 activities, and increased MMP-9 expression in response to NF-κB activation, are associated with tumor metastasis .
Genistein (Gen; 5,7,4′-trihydroxyisoflavone), a soybean-derived isoflavone, has been identified as a potential cause for the low incidence of certain types of tumors, such as lung , breast, gastric, colon, and prostate cancers, and HCC [9, 15–19]. Gen is also a principal chemopreventive component of soy and exerts a wide array of chemopreventive activities in each stage of multistep carcinogenesis [20, 21]. Previous studies [20, 22] showed that Gen is a promising agent for inhibiting the metastatic potential of HCC. Gen may affect HCC progression as a result of its effects on cell cycle progression and apoptosis [16, 22]; however, there are no reports on the mechanism of the inhibitory effects of Gen on TPA-induced invasion and MMP-9 expression. Herein, we demonstrate that the suppression of TPA-induced MMP-9 activity by Gen occurs via disruption of NF-κB and AP-1 signaling pathways in HepG2 cells.
Genistein (Sigma Chemical Co., St. Louis, MO, USA) was dissolved in 0.1 M Na2CO3 to create a 10-mM stock solution. TPA (Sigma-Aldrich, St. Louis, MO) was prepared in phosphate-buffered saline (PBS; 137 mM NaCl, 1.4 mM KH2PO4, 4.3 mM Na2HPO4, 2.7 mM KCl, pH 7.2). For analysis of the signaling pathways involved in TPA-induced DNA-binding of AP-1 and NF-κB, we also treated HepG2 cells with the p38 inhibitor SB203580 (SB), the MEK/ERK inhibitor PD98059 (PD), the JNK inhibitor JNKI, the IKK inhibitor BMS (AKTI), LY294002 (LY, an Akt inhibitor) and bisindolylmaleimide (GF, GF109203X, a PKC inhibitor) were purchased from Sigma-Aldrich to block these pathways.
Cell culture and TPA treatment
Human hepatoma cell lines (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2) were maintained in Dulbecco’s modified Eagle medium (DMEM; Life Technologies, Gaithersburg, MD, USA) and supplemented with 10% fetal bovine serum (FBS; HyClone, Logan, UT, USA). The cells were transiently transfected with 5 μg of plasmid DNA using SuperFect transfection reagent (Qiagen, Valencia, CA, USA). TPA (Sigma-Aldrich) was prepared in PBS (137 mM NaCl, 1.4 mM KH2PO4, 4.3 mM Na2HPO4, and 2.7 mM KCl, pH 7.2). HepG2, Huh-7, HA22T, and BNL CL2 cells were cultured in 25-cm2 flasks at 37°C. The flasks were immediately capped and sealed with parafilm to minimize evaporation. Cell growth was measured using a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. HepG2 cells were resuspended with 100 μL in 96-well plates and cultured with or without 80 μM TPA and Gen, incubated for 24 h, then 20 μL MTT was added to each well and incubated at 37°C for 4 h. The supernatant was removed, 200 μL dimethyl sulfoxide (DMSO) was added to each well to solubilize the formazan product, and the absorbance was measured at 470 nm using a microplate reader (Sigma).
Wound healing assay
Hepatoma cell lines were grown to 90% confluence in a 6-well plate at 37ºC in a 5% CO2 incubator. A wound was created by scratching cells with a sterile 200 μL pipette tip, then the cells were washed twice with PBS to remove floating cells and added to serum-free medium. Photos of the wound were obtained via microscopy under 100× magnification.
Cell invasion was assessed using Matrigel-coated film inserts (8-μm pore size) fit into 24-well invasion chambers (Becton-Dickinson Bioscience, Franklin Lakes, NJ, USA). HepG2 cells (5 × 104) were suspended in 200 μL of DMEM and added to the upper compartment of an invasion chamber in the presence or absence of 80 μM TPA; DMEM (500 μL) was added to the lower chamber. The chambers were incubated at 37ºC in a 5% CO2 atmosphere. The filter inserts were removed after a 24-h incubation period, and cells on the upper surfaces of the filters were removed with cotton swabs. Cells on the lower surfaces of the filters were stained with crystal violet, and the number of cells was determined with the use of a microscope. Final values were calculated as the mean of the total number of cells from 3 filters.
Gelatin zymography was used for determination of expression and activities of MMP-9 in TPA-treated (with or without Gen) human HepG2 cells. HepG2 cells were seeded in 100-mm plates using serum-free medium and pretreated with TPA and different concentrations of Gen. After incubation for 24 h, the conditioned media were collected and quantification of the protein concentrations was performed using the Bio-Rad protein assay (Bio-Rad Laboratories, Inc., Hercules, CA, USA). Culture supernatants were subjected to electrophoresis on gelatin substrate gels (10% sodium dodoecyl sulfate [SDS]-polyacrylamide gels containing 1 mg/mL gelatin). Subsequently, the gels were treated with 2.5% Triton X-100 for 30 min, followed by incubation for 24 h at 37°C in a buffer containing 100 mM Tris–HCl, pH 7.4, 0.15 M NaCl, and 15 mM CaCl2. The gels were stained with Coomassie Blue R-250 and then destained with water until emergence of clear zones that indicated proteolytic activity against a blue background.
Wild-type sequences were obtained for NF-κB (GGAATTCCCC) and AP-1 (TGAGTCA) sites. Reporter plasmids (pNF-κB-Luc and pAP-1-Luc) were purchased from Stratagene (La Jolla, CA, USA). Plasmid DNAs were prepared with a Qiagen Plasmid Midi Kit (Qiagen). The MMP-9-Luc plasmid was kindly provided by Dr. C.K. Glass . Hepatoma cell lines were treated with 80 μM TPA for 8 h, and luciferase activity was determined as previously described . Briefly, HepG2 cells in each well were washed with PBS and at lysed with 50 μL of passive lysis buffer (Promega, Madison, WI, USA) at various time points after treatment. Lysates were transferred to 96-well white plates and substrate was added (Promega) to assess the luciferase activity with a microplate reader (Synergy HT, Bio-Tek, Winooski, VT, USA). Relative luciferase activity was calculated by dividing relative luciferase units of MMP-9, NF-κB, or AP-1 reporter plasmid-transfected cells by the relative luciferase units of pGL3-basic–transfected cells.
Preparation of nuclear extracts and electrophoretic mobility shift assay
HepG2 cells were treated with 80 μM TPA and 10–40 μM Gen. Nuclear extracts were prepared as described previously . Briefly, cells were stimulated, harvested by centrifugation, washed twice with cold PBS, and then nuclear extracts were prepared using NE-PER reagent (Pierce, Rockford, IL, USA), according to the manufacturer’s instructions. Biotin-labeled complementary oligonucleotides corresponding to NF-κB and AP-1 binding sites were annealed. Biotinylated electrophoretic mobility shift assays (EMSAs) were performed as previously described , and gels were transferred to nylon membranes after electrophoresis. Membranes were blocked in solution and detected with alkaline phosphatase-conjugated streptavidin (Chemicon, Australia) followed by chemiluminescence (Roche, Germany).
Western blot analysis
Hepatoma cells were treated with 80 μM TPA and 10–40 μM Gen and lysed in 250 μL of sample buffer (62.5 mM Tris–HCl, 2% SDS, 10% glycerol, 50 mM dithiothreitol, and 0.1% bromophenol blue, pH 6.8). We also collected the supernatants from cultures treated with 80 μM TPA and Gen. The supernatants were concentrated 40-fold with a Minicon filter (Millipore, Billerica, MA, USA) with a 15-kDa cutoff pore diameter. Protein concentrations were determined with a BCA Protein Assay Kit (Pierce, Rockford, IL, USA). To investigate the different cell fractions, the cells were scraped into 2 mL of buffer A (20 mmol/L Tris HCl, pH 7.5, 0.25 mol/L sucrose, 10 mmol/L EGTA, 2 mmol/L EDTA, 20 μg/mL leupeptin, 10 μg/mL aprotinin, and 200 μmol/L phenylsulfonyl fluoride) at 4°C and were sonicated and separated into cytosolic fraction and membrane fraction as described previously . The cytoplasmic extracts (cytosol) were prepared using Cytoplasmic Extraction Reagent (Pierce), according to the manufacturer’s instructions. For translocation of p65, the protein concentrations of p65 in cytoplasmic extracts and nuclear extracts were detected by western blotting. Proteins (10 μg for cell lysates; 40 μg for supernatants) were separated using 10% SDS-polyacrylamide gel electrophoresis, and protein bands were transferred electrophoretically to nitrocellulose membranes. Membranes were probed with polyclonal antibodies against p65, MMP-9, epidermal growth factor receptor (EGFR), PKCα, PKCβ, PKCγ, Akt, phosphatidylinositide kinase 3 (PI3K), IκB-α, phosphorylated IκB-α, c-Jun N-terminal kinase (JNK), phosphorylated JNK, p38, phosphorylated p38, extracellular signal-related kinase (ERK), phosphorylated ERK, and β-actin (Cell Signaling Technology, Beverly, MA, USA). Bound antibodies were detected with peroxidase-conjugated anti-rabbit antibodies followed by chemiluminescence (ECL System; Amersham, Buckinghamshire, UK) and autoradiographic exposure. The intensities of gel bands were calculated with a Gel-Pro Analyzer.
One-way analysis of variance (ANOVA) was used to determine whether mean values differed significantly (p < 0.05). If the means were significantly different, a Tukey-Kramer post-hoc multiple group comparison test was used to compare individual groups. Data are shown as mean ± standard error of the mean (SEM).
Gen inhibited TPA-induced invasion and migration in human hepatoma cells
HepG2 cells were also treated with TPA and Gen in an invasion chamber to assess the effects of Gen on TPA-induced cell invasion. We also examined the migration of the other 3 cell lines (Figure 1B). The migration of human hepatoma cell lines (Huh-7 and HA22T) was induced by TPA incubation and inhibited by treatment with Gen at 20 μM. However, liver cells (BNL CL2) were not affected by TPA incubation and treatment with Gen at 20 μM.
Effect of Gen on TPA-induced MMP-9 expression and activity
Effect of Gen on TPA-activated transcription of MM-9, NF-κB, and AP-1 promoters
To determine whether the transcriptional activities of MMP-9, NF-κB, and AP-1 are regulated by TPA, we examined the promoter activity of the NF-κB and AP-1 genes using luciferase assays. The cells were treated with TPA (with or without Gen) for 16 h, and promoter activity was measured by luciferase assay. Figure 4A shows that the MMP-9 promoter was increased approximately 4-fold by TPA in HepG2 cells relative to the control MMP-9 promoter-transfected cells, and the activated promoter was suppressed by Gen in a dose-dependent manner and significantly suppressed at concentrations ≥10 μM. Figure 4B shows that the AP-1 promoter increased approximately 4-fold over the activity in AP-1–transfected cells in response to TPA, which was also inhibited by Gen in a dose-dependent manner and significantly suppressed at concentrations ≥10 μM. As shown in Figure 4C, the NF-κB promoter activity was increased approximately 2.7-fold over that in NF-κB–transfected cells in response to TPA, and this was inhibited by Gen in a dose -dependent manner and significantly suppressed at concentrations ≥20 μM.
Inhibitory effect of Gen on TPA-induced activation of MAPKs, PI3K, Akt, and PKC
Epidemiologic studies have demonstrated that the consumption of fruits and vegetables can reduce the risk of several types of human cancers . Approximately 70% of the drugs used for cancer treatment are derived from or based on natural products [29, 30]. A number of phytochemicals can inhibit tumor metastasis and cell invasion via suppression of MMP gene expression and enzymatic activity. For example, curcumin interferes with the activity of MMP-9, reducing degradation of the extracellular matrix, which forms the basis of the angiogenic switch . Hesperidin suppresses TPA-induced MMP-9 transcription by inhibiting NF-κB activity , and pterostilbene inhibits TPA-stimulated NF-κB and AP-1 transcriptional activities . Gen is a small, biologically active flavonoid that is abundant in soy. Gen is best known for its ability to inhibit cancer progression and metastasis. Consumption of Gen in the diet has been linked to decreased rates of metastatic cancer in a number of population-based studies . In HCC, Gen has anti-mutagenic activity  and induces apoptosis . In the present study, we showed for the first time that Gen suppresses TPA-induced cell invasive activity and MMP-9 expression by reducing tumor migration and invasion of HCC.
Several stimulators increase the expression of MMP-9 via various signaling pathways and result in increased invasiveness in cell lines. Specifically, TPA-induced MMP-9 expression has been studied extensively in HCC cells [14, 27, 36]. These studies suggest that TPA-induced MMP-9 expression in HepG2 cells occurs by activating phosphorylation of MAPK, IκB, and Akt signaling pathways. These pathways activate the transcription factors NF-κB and AP-1. We previously reported that NF-κB and AP-1 are activated in TPA-induced MMP-9 expression via IκB and MAPK pathways in HCC cells . Another report showed that NF-κB and AP-1 were activated following TPA-induced MMP-9 activation though extracellular signal-regulated MAPK and PI3K/Akt [27, 37]. The present study showed that Gen effectively suppressed TPA-induced MMP-9 gene expression by suppressing the MAPK/AP-1 and PI3K/AKT/NF-κB cascades, with consequent suppression of tumor migration and invasion of human hepatoma HepG2 cells.
EGFR autocrine/paracrine pathways contribute to a number of processes that are important in the development and progression of cancer, including cell proliferation, apoptosis, angiogenesis, and metastatic spread. High expression of EGFR has been observed in numerous human tumors, including lung, colon, breast, head and neck, ovarian, bladder, and liver cancers, and has been shown to correlate with advanced tumor stage and poor clinical prognosis [38–40]. The EGFR signaling pathway is associated with metastatic properties, including cell motility, adhesion, and invasion in vitro[41, 42]. EGFR activates intracellular signaling cascades, including Ras/Raf/MEK/ERK and PI3K/Akt, and subsequently controls proliferation, migration, and apoptosis . Activation of NF-κB and AP-1 is centrally involved in the induction of the MMP-9 gene associated with the invasion and metastasis of tumor cells by different agents, including TPA and growth factors, such as EGF [27, 44, 45]. There is a report that TPA induces EGFR expression in HepG2 cells . Thus, the regulation of NF-κB and AP-1, downstream of the PI3K/Akt and MAPK pathways, might be involved in Gen suppression of TPA-induced MMP-9 expression and invasion in HepG2 cells.
In conclusion, we provided evidence that Gen promotes anti-invasive and anti-metastatic effects against TPA-mediated metastasis via downregulation of MMP-9 and EGFR and subsequent suppression of NF-κB and AP-1 transcription factors though inhibition of MAPK, IκB, and PI3K/Akt signaling pathways. Therefore, we conclude that MMP-9 inhibitory activity of Gen and its inhibition of multiple signal transduction pathways suggest its therapeutic potential for controlling the invasiveness and metastasis of HCC.
c-Jun N-terminal kinase
Extracellular signal-regulated protein kinase
Electrophoretic mobility shift assay
Mitogen-activated protein kinase
SB203580 P38 inhibitor
PD98059 MEK/ERK inhibitor
This work was supported by grants (NSC98-2320-B-303-002) from the National Science Council and (DTCRD98 -12) from the Buddhist Dalin Tzu Chi General Hospital, Taiwan.
- Schmitz HC, Weishaupt D, Borel N, Padberg B, Bfirki K: The use of ultrasound and computed tomography for the diagnosis of a squamous cell carcinoma of the oesophago-cardial region of the stomach in a rhesus monkey. Lab Anim. 2004, 38 (1): 92-97.View ArticlePubMedGoogle Scholar
- Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D: Global cancer statistics. CA Cancer J Clin. 2011, 61 (2): 69-90.View ArticlePubMedGoogle Scholar
- Farazi PA, DePinho RA: Hepatocellular carcinoma pathogenesis: from genes to environment. Nat Rev Cancer. 2006, 6 (9): 674-687.View ArticlePubMedGoogle Scholar
- Monvoisin A, Neaud V, De Ledinghen V, Dubuisson L, Balabaud C, Bioulac-Sage P, Desmouliere A, Rosenbaum J: Direct evidence that hepatocyte growth factor-induced invasion of hepatocellular carcinoma cells is mediated by urokinase. J Hepatol. 1999, 30 (3): 511-518.View ArticlePubMedGoogle Scholar
- Stamenkovic I: Matrix metalloproteinases in tumor invasion and metastasis. Semin Cancer Biol. 2000, 10 (6): 415-433.View ArticlePubMedGoogle Scholar
- Torzilli PA, Bourne JW, Cigler T, Vincent CT: A new paradigm for mechanobiological mechanisms in tumor metastasis. Semin Cancer Biol. 2012, 22 (5–6): 385-395.View ArticlePubMedPubMed CentralGoogle Scholar
- Arii S, Mise M, Harada T, Furutani M, Ishigami S, Niwano M, Mizumoto M, Fukumoto M, Imamura M: Overexpression of matrix metalloproteinase 9 gene in hepatocellular carcinoma with invasive potential. Hepatology. 1996, 24 (2): 316-322.View ArticlePubMedGoogle Scholar
- Sato H, Seiki M: Regulatory mechanism of 92 kDa type IV collagenase gene expression which is associated with invasiveness of tumor cells. Oncogene. 1993, 8 (2): 395-405.PubMedGoogle Scholar
- Lee EJ, Kim DI, Kim WJ, Moon SK: Naringin inhibits matrix metalloproteinase-9 expression and AKT phosphorylation in tumor necrosis factor-alpha-induced vascular smooth muscle cells. Mol Nutr Food Res. 2009, 53 (12): 1582-1591.View ArticlePubMedGoogle Scholar
- Freise C, Ruehl M, Erben U, Neumann U, Seehofer D, Kim KY, Trowitzsch-Kienast W, Stroh T, Zeitz M, Somasundaram R: A hepatoprotective Lindera obtusiloba extract suppresses growth and attenuates insulin like growth factor-1 receptor signaling and NF-kappaB activity in human liver cancer cell lines. BMC Complement Altern Med. 2011, 11: 39-View ArticlePubMedPubMed CentralGoogle Scholar
- Furstenberger G, Berry DL, Sorg B, Marks F: Skin tumor promotion by phorbol esters is a two-stage process. Proc Natl Acad Sci U S A. 1981, 78 (12): 7722-7726.View ArticlePubMedPubMed CentralGoogle Scholar
- Barry OP, Kazanietz MG: Protein kinase C isozymes, novel phorbol ester receptors and cancer chemotherapy. Curr Pharm Des. 2001, 7 (17): 1725-1744.View ArticlePubMedGoogle Scholar
- Liu JF, Crepin M, Liu JM, Barritault D, Ledoux D: FGF-2 and TPA induce matrix metalloproteinase-9 secretion in MCF-7 cells through PKC activation of the Ras/ERK pathway. Biochem Biophys Res Commun. 2002, 293 (4): 1174-1182.View ArticlePubMedGoogle Scholar
- Lee KH, Yeh MH, Kao ST, Hung CM, Liu CJ, Huang YY, Yeh CC: The inhibitory effect of hesperidin on tumor cell invasiveness occurs via suppression of activator protein 1 and nuclear factor-kappaB in human hepatocellular carcinoma cells. Toxicol Lett. 2010, 194 (1–2): 42-49.View ArticlePubMedGoogle Scholar
- Tategu M, Arauchi T, Tanaka R, Nakagawa H, Yoshida K: Puma is a novel target of soy isoflavone genistein but is dispensable for genistein-induced cell fate determination. Mol Nutr Food Res. 2008, 52 (4): 439-446.View ArticlePubMedGoogle Scholar
- Gu Y, Zhu CF, Iwamoto H, Chen JS: Genistein inhibits invasive potential of human hepatocellular carcinoma by altering cell cycle, apoptosis, and angiogenesis. World J Gastroenterol. 2005, 11 (41): 6512-6517.View ArticlePubMedPubMed CentralGoogle Scholar
- Cui HB, Na XL, Song DF, Liu Y: Blocking effects of genistein on cell proliferation and possible mechanism in human gastric carcinoma. World J Gastroenterol. 2005, 11 (1): 69-72.View ArticlePubMedPubMed CentralGoogle Scholar
- Qi W, Weber CR, Wasland K, Savkovic SD: Genistein inhibits proliferation of colon cancer cells by attenuating a negative effect of epidermal growth factor on tumor suppressor FOXO3 activity. BMC Cancer. 2011, 11: 219-View ArticlePubMedPubMed CentralGoogle Scholar
- Chiyomaru T, Yamamura S, Zaman MS, Majid S, Deng G, Shahryari V, Saini S, Hirata H, Ueno K, Chang I, Tanaka Y, Tabatabai ZL, Enokida H, Nakagawa M, Dahiya R: Genistein suppresses prostate cancer growth through inhibition of oncogenic MicroRNA-151. PLoS One. 2012, 7 (8): e43812-View ArticlePubMedPubMed CentralGoogle Scholar
- Park OJ, Surh Y-J: Chemopreventive potential of epigallocatechin gallate and genistein: evidence from epidemiological and laboratory studies. Toxicol Lett. 2004, 150 (1): 43-56.View ArticlePubMedGoogle Scholar
- Jerome-Morais A, Diamond AM, Wright ME: Dietary supplements and human health: for better or for worse?. Mol Nutr Food Res. 2011, 55 (1): 122-135.View ArticlePubMedGoogle Scholar
- Gu Y, Zhu CF, Dai YL, Zhong Q, Sun B: Inhibitory effects of genistein on metastasis of human hepatocellular carcinoma. World J Gastroenterol. 2009, 15 (39): 4952-4957.View ArticlePubMedPubMed CentralGoogle Scholar
- Ricote M, Li AC, Willson TM, Kelly CJ, Glass CK: The peroxisome proliferator-activated receptor-gamma is a negative regulator of macrophage activation. Nature. 1998, 391 (6662): 79-82.View ArticlePubMedGoogle Scholar
- Yeh CC, Lin CC, Wang SD, Hung CM, Yeh MH, Liu CJ, Kao ST: Protective and immunomodulatory effect of Gingyo-san in a murine model of acute lung inflammation. J Ethnopharmacol. 2007, 111 (2): 418-426.View ArticlePubMedGoogle Scholar
- Mullin JM, Soler AP, Laughlin KV, Kampherstein JA, Russo LM, Saladik DT, George K, Shurina RD, O’Brien TG: Chronic exposure of LLC-PK1 epithelia to the phorbol ester TPA produces polyp-like foci with leaky tight junctions and altered protein kinase C-alpha expression and localization. Exp Cell Res. 1996, 227 (1): 12-22.View ArticlePubMedGoogle Scholar
- Kajanne R, Miettinen P, Mehlem A, Leivonen SK, Birrer M, Foschi M, Kahari VM, Leppa S: EGF-R regulates MMP function in fibroblasts through MAPK and AP-1 pathways. J Cell Physiol. 2007, 212 (2): 489-497.View ArticlePubMedGoogle Scholar
- Pan MH, Chiou YS, Chen WJ, Wang JM, Badmaev V, Ho CT: Pterostilbene inhibited tumor invasion via suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells. Carcinogenesis. 2009, 30 (7): 1234-1242.View ArticlePubMedGoogle Scholar
- Pan MH, Ho CT: Chemopreventive effects of natural dietary compounds on cancer development. Chem Soc Rev. 2008, 37 (11): 2558-2574.View ArticlePubMedGoogle Scholar
- Newman DJ, Cragg GM, Holbeck S, Sausville EA: Natural products and derivatives as leads to cell cycle pathway targets in cancer chemotherapy. Curr Cancer Drug Targets. 2002, 2 (4): 279-308.View ArticlePubMedGoogle Scholar
- Yeh CC, Yang JI, Lee JC, Tseng CN, Chan YC, Hseu YC, Tang JY, Chuang LY, Huang HW, Chang FR, Chang HW: Anti-proliferative effect of methanolic extract of Gracilaria tenuistipitata on oral cancer cells involves apoptosis, DNA damage, and oxidative stress. BMC Complement Altern Med. 2012, 12: 142-View ArticlePubMedPubMed CentralGoogle Scholar
- Chen LX, He YJ, Zhao SZ, Wu JG, Wang JT, Zhu LM, Lin TT, Sun BC, Li XR: Inhibition of tumor growth and vasculogenic mimicry by curcumin through down-regulation of the EphA2/PI3K/MMP pathway in a murine choroidal melanoma model. Cancer Biol Ther. 2011, 11 (2): 229-235.View ArticlePubMedGoogle Scholar
- Yeh MH, Kao ST, Hung CM, Liu CJ, Lee KH, Yeh CC: Hesperidin inhibited acetaldehyde-induced matrix metalloproteinase-9 gene expression in human hepatocellular carcinoma cells. Toxicol Lett. 2009, 184 (3): 204-210.View ArticlePubMedGoogle Scholar
- Pavese JM, Farmer RL, Bergan RC: Inhibition of cancer cell invasion and metastasis by genistein. Cancer Metastasis Rev. 2010, 29 (3): 465-482.View ArticlePubMedPubMed CentralGoogle Scholar
- Lepri SR, Luiz RC, Zanelatto LC, da Silva PB, Sartori D, Ribeiro LR, Mantovani MS: Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells. Cytotechnology. 2013, 65 (2): 213-222.View ArticlePubMedGoogle Scholar
- Fang SC, Hsu CL, Lin HT, Yen GC: Anticancer effects of flavonoid derivatives isolated from Millettia reticulata Benth in SK-Hep-1 human hepatocellular carcinoma cells. J Agric Food Chem. 2010, 58 (2): 814-820.View ArticlePubMedGoogle Scholar
- Hah N, Lee ST: An absolute role of the PKC-dependent NF-kappaB activation for induction of MMP-9 in hepatocellular carcinoma cells. Biochem Biophys Res Commun. 2003, 305 (2): 428-433.View ArticlePubMedGoogle Scholar
- Chien YC, Sheu MJ, Wu CH, Lin WH, Chen YY, Cheng PL, Cheng HC: A Chinese herbal formula “Gan-Lu-Yin” suppresses vascular smooth muscle cell migration by inhibiting matrix metalloproteinase-2/9 through the PI3K/AKT and ERK signaling pathways. BMC Complement Altern Med. 2012, 12: 137-View ArticlePubMedPubMed CentralGoogle Scholar
- Ito Y, Takeda T, Sakon M, Tsujimoto M, Higashiyama S, Noda K, Miyoshi E, Monden M, Matsuura N: Expression and clinical significance of erb-B receptor family in hepatocellular carcinoma. Br J Cancer. 2001, 84 (10): 1377-1383.View ArticlePubMedPubMed CentralGoogle Scholar
- Abbaoui B, Riedl KM, Ralston RA, Thomas-Ahner JM, Schwartz SJ, Clinton SK, Mortazavi A: Inhibition of bladder cancer by broccoli isothiocyanates sulforaphane and erucin: characterization, metabolism, and interconversion. Mol Nutr Food Res. 2012, 56 (11): 1675-1687.View ArticlePubMedGoogle Scholar
- Qiu P, Guan H, Dong P, Guo S, Zheng J, Li S, Chen Y, Ho CT, Pan MH, McClements DJ, Xiao H: The inhibitory effects of 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone on human colon cancer cells. Mol Nutr Food Res. 2011, 55 (10): 1523-1532.View ArticlePubMedPubMed CentralGoogle Scholar
- Woodburn JR: The epidermal growth factor receptor and its inhibition in cancer therapy. Pharmacol Ther. 1999, 82 (2–3): 241-250.View ArticlePubMedGoogle Scholar
- Sun Q, Prasad R, Rosenthal E, Katiyar SK: Grape seed proanthocyanidins inhibit the invasive potential of head and neck cutaneous squamous cell carcinoma cells by targeting EGFR expression and epithelial-to-mesenchymal transition. BMC Complement Altern Med. 2011, 11: 134-View ArticlePubMedPubMed CentralGoogle Scholar
- Hwang MK, Bode AM, Byun S, Song NR, Lee HJ, Lee KW, Dong Z: Cocarcinogenic effect of capsaicin involves activation of EGFR signaling but not TRPV1. Cancer Res. 2010, 70 (17): 6859-6869.View ArticlePubMedGoogle Scholar
- Ueno Y, Sakurai H, Matsuo M, Choo MK, Koizumi K, Saiki I: Selective inhibition of TNF-alpha-induced activation of mitogen-activated protein kinases and metastatic activities by gefitinib. Br J Cancer. 2005, 92 (9): 1690-1695.View ArticlePubMedPubMed CentralGoogle Scholar
- Hwang YP, Yun HJ, Choi JH, Han EH, Kim HG, Song GY, Kwon KI, Jeong TC, Jeong HG: Suppression of EGF-induced tumor cell migration and matrix metalloproteinase-9 expression by capsaicin via the inhibition of EGFR-mediated FAK/Akt, PKC/Raf/ERK, p38 MAPK, and AP-1 signaling. Mol Nutr Food Res. 2011, 55 (4): 594-605.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1472-6882/14/26/prepub
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.