Fruit and vegetable intake in relation to risk of breast cancer in the Black Women's Health Study

The authors prospectively examined the relation of fruit and vegetable intake to breast cancer risk among 51,928 women aged 21-69 years at enrollment in 1995 in the Black Women's Health Study. Dietary intake was assessed by using a validated food frequency questionnaire. Cox proportional hazards models were used to estimate incidence rate ratios and 95% confidence intervals, adjusted for breast cancer risk factors. During 12 years of follow-up, there were 1,268 incident cases of breast cancer. Total fruit, total vegetable, and total fruit and vegetable intakes were not significantly associated with overall risk of breast cancer. However, total vegetable consumption was associated with a decreased risk of estrogen receptor-negative/progesterone receptor-negative breast cancer (incidence rate ratio = 0.57, 95% confidence interval: 0.38, 0.85, for ≥2 servings/day relative to <4/week; P(trend) = 0.02). In addition, there was some evidence of inverse associations with breast cancer risk overall for cruciferous vegetable intake (P(trend) = 0.06) and for carrot intake (P(trend) = 0.02). Study findings suggest that frequent consumption of vegetables is inversely associated with risk of estrogen receptor-negative/progesterone receptor-negative breast cancer, and that specific vegetables may be associated with a decreased risk of breast cancer overall.

Anti-inflammatory activity of natural dietary flavonoids

Over the past few decades, inflammation has been recognized as a major risk factor for various human diseases. Acute inflammation is short-term, self-limiting and it's easy for host defenses to return the body to homeostasis. Chronic inflammatory responses are predispose to a pathological progression of chronic illnesses characterized by infiltration of inflammatory cells, excessive production of cytokines, dysregulation of cellular signaling and loss of barrier function. Targeting reduction of chronic inflammation is a beneficial strategy to combat several human diseases. Flavonoids are widely present in the average diet in such foods as fruits and vegetables, and have been demonstrated to exhibit a broad spectrum of biological activities for human health including an anti-inflammatory property. Numerous studies have proposed that flavonoids act through a variety mechanisms to prevent and attenuate inflammatory responses and serve as possible cardioprotective, neuroprotective and chemopreventive agents. In this review, we summarize current knowledge and underlying mechanisms on anti-inflammatory activities of flavonoids and their implicated effects in the development of various chronic inflammatory diseases.

Differential protection among fractionated blueberry polyphenolic families against DA-, Abeta(42)- and LPS-induced decrements in Ca(2+) buffering in primary hippocampal cells

It has been postulated that at least part of the loss of cognitive function in aging may be the result of deficits in Ca(2+) recovery (CAR) and increased oxidative/inflammatory (OX/INF) stress signaling. However, previous research showed that aged animals supplemented with blueberry (BB) extract showed fewer deficits in CAR, as well as motor and cognitive functional deficits. A recent subsequent experiment has shown that DA- or Abeta(42)-induced deficits in CAR in primary hippocampal neuronal cells (HNC) were antagonized by BB extract, and (OX/INF) signaling was reduced. The present experiments assessed the most effective BB polyphenol fraction that could protect against OX/INF-induced deficits in CAR, ROS generation, or viability. HNCs treated with BB extract, BB fractions (e.g., proanthocyanidin, PAC), or control medium were exposed to dopamine (DA, 0.1 mM), amyloid beta (Abeta(42), 25 muM) or lipopolysaccharide (LPS, 1 microg/mL). The results indicated that the degree of protection against deficits in CAR varied as a function of the stressor and was generally greater against Abeta(42) and LPS than DA. The whole BB, anthocyanin (ANTH), and PRE-C18 fractions offered the greatest protection, whereas chlorogenic acid offered the lowest protection. Protective capabilities of the various fractions against ROS depended upon the stressor, where the BB extract and the combined PAC (high and low molecular weight) fraction offered the best protection against LPS and Abeta(42) but were less effective against DA-induced ROS. The high and low molecular weight PACs and the ANTH fractions enhanced ROS production regardless of the stressor used, and this reflected increased activation of stress signals (e.g., P38 MAPK). The viability data indicated that the whole BB and combined PAC fraction showed greater protective effects against the stressors than the more fractionated polyphenolic components. Thus, these results suggest that, except for a few instances, the lesser the polyphenolic fractionation, the greater the effects, especially with respect to prevention of ROS and stress signal generation and viability.

Structure, function, regulation and polymorphism and the clinical significance of human cytochrome P450 1A2

Human CYP1A2 is one of the major CYPs in human liver and metabolizes a number of clinical drugs (e.g., clozapine, tacrine, tizanidine, and theophylline; n > 110), a number of procarcinogens (e.g., benzo[a]pyrene and aromatic amines), and several important endogenous compounds (e.g., steroids). CYP1A2 is subject to reversible and/or irreversible inhibition by a number of drugs, natural substances, and other compounds. The CYP1A gene cluster has been mapped on to chromosome 15q24.1, with close link between CYP1A1 and 1A2 sharing a common 5'-flanking region. The human CYP1A2 gene spans almost 7.8 kb comprising seven exons and six introns and codes a 515-residue protein with a molecular mass of 58,294 Da. The recently resolved CYP1A2 structure has a relatively compact, planar active site cavity that is highly adapted for the size and shape of its substrates. The architecture of the active site of 1A2 is characterized by multiple residues on helices F and I that constitutes two parallel substrate binding platforms on either side of the cavity. A large interindividual variability in the expression and activity of CYP1A2 has been observed, which is largely caused by genetic, epigenetic and environmental factors (e.g., smoking). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. Induction or inhibition of CYP1A2 may provide partial explanation for some clinical drug interactions. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of them have been associated with altered drug clearance and response and disease susceptibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.

The cytotoxic effect of Bowman-Birk isoinhibitors, IBB1 and IBBD2, from soybean (Glycine max) on HT29 human colorectal cancer cells is related to their intrinsic ability to inhibit serine proteases

Bowman-Birk inhibitors (BBI) from soybean and related proteins are naturally occurring protease inhibitors with potential health-promoting properties within the gastrointestinal tract. In this work, we have investigated the effects of soybean BBI proteins on HT29 colon adenocarcinoma cells, compared with non-malignant colonic fibroblast CCD-18Co cells. Two major soybean isoinhibitors, IBB1 and IBBD2, showing considerable amino acid sequence divergence within their inhibitory domains, were purified in order to examine their functional properties, including their individual effects on the proliferation of HT29 colon cancer cells. IBB1 inhibited both trypsin and chymotrypsin whereas IBBD2 inhibited trypsin only. Despite showing significant differences in their enzyme inhibitory properties, the median inhibitory concentration values determined for IBB1 and IBBD2 on HT29 cell growth were not significantly different (39.9+/-2.3 and 48.3+/-3.5 microM, respectively). The cell cycle distribution pattern of HT29 colon cancer cells was affected by BBI treatment in a dose-dependent manner, with cells becoming blocked in the G0-G1 phase. Chemically inactive soybean BBI had a weak but non-significant effect on the proliferation of HT29 cells. The anti-proliferative properties of BBI isoinhibitors from soybean reveal that both trypsin- and chymotrypsin-like proteases involved in carcinogenesis should be considered as potential targets of BBI-like proteins.

On the natural chemoprevention of cancer

Cancer is a complex disease to treat and the treatments have not progressed significantly in the last few years. Alternative strategies such as chemoprevention are being investigated. Proof of concept of chemoprevention has been shown with the non-steroidal anti-inflammatory drugs (NSAIDs); however there is significantly more interest in plant and naturally available compounds for chemoprevention. A number of different naturally occurring chemical compounds are reviewed here for their potential benefits and the pathways which they may target, in particular the polyamine pathway.

Angiogenesis as a potential target of pharmaconutrients in cancer therapy

PURPOSE OF REVIEW

The aim of this review is to provide insight into tumor angiogenesis inhibition by pharmaconutrients through description of the most relevant and recent findings in cancer research.

RECENT FINDINGS

Cancer growth needs oxygen and nutrients supplied through blood vessels to the tumor site. New vessel formation named angiogenesis can be prevented to avoid cancer invasion. Epidemiological studies suggested that specific food intakes could decrease incidence of many cancers. Recently, scientists were interested in the potential antitumor effects of nutrients because of their safety and general acceptance. Many excellent publications demonstrated that a large class of natural compounds including pharmaconutrients exhibits antitumoral activities in selected cancer types. This review focuses on the antiangiogenic role of natural products in cancer treatment, used alone or in combination with conventional chemotherapy.

SUMMARY

There is strong evidence that natural diets influence cancer development by modulating signaling pathways. Our goal is to highlight the specific impact of specific nutrients in the modulation of vascular network leading to tumor angiogenesis inhibition.

Polyphenolic compounds from Salvia species protect cellular DNA from oxidation and stimulate DNA repair in cultured human cells

DNA damage can lead to carcinogenesis if replication proceeds without proper repair. This study evaluated the effects of the water extracts of three Salvia sp., Salvia officinalis (SO), Salvia fruticosa (SF), and Salvia lavandulifolia (SL), and of the major phenolic constituents, rosmarinic acid (RA) and luteolin-7-glucoside (L-7-G), on DNA protection in Caco-2 and HeLa cells exposed to oxidative agents and on DNA repair in Caco-2 cells. The comet assay was used to measure DNA damage and repair capacity. The final concentration of each sage extract was 50 microg/mL, and concentrations of RA and L-7-G were 50 and 20 microM, respectively. After a short incubation (2 h), L-7-G protected DNA in Caco-2 cells from damage induced by H(2)O(2) (75 microM); also, after a long incubation (24 h), SF, RA, and L-7-G had protective effects in Caco-2 cells. In HeLa cells, SO, SF, and RA protected against damage induced by H(2)O(2) after 24 h of incubation. Assays of DNA repair show that SO, SF, and L-7-G increased the rate of DNA repair (rejoining of strand breaks) in Caco-2 cells treated with H(2)O(2). The incision activity of a Caco-2 cell extract on a DNA substrate containing specific damage (8-oxoGua) was also measured to evaluate effects on base excision repair (BER) activity. Preincubation for 24 h with SO and L-7-G had a BER inductive effect, increasing incision activity in Caco-2 cells. In conclusion, SO, SF, and the isolated compounds (RA and L-7-G) demonstrated chemopreventive activity by protecting cells against oxidative DNA damage and stimulating DNA repair (SO, SF, and L-7-G).

Inhibitory effect of magnolol on TPA-induced skin inflammation and tumor promotion in mice

Magnolol has been reported to have an anti-inflammatory and antitumor effect in vitro and in vivo. Herein, we report the investigation of the inhibitory effects of magnolol on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in mouse skin. We found that the topical application of magnolol effectively inhibited the transcriptional activation of iNOS and COX-2 mRNA and proteins in mouse skin stimulated by TPA. Pretreatment with magnolol resulted in the reduction of TPA-induced nuclear translocation of the nuclear factor-kappaB (NFkappaB) subunit and DNA binding by blocking the phosphorylation of IkappaBalpha and p65 and subsequent degradation of IkappaBalpha. In addition, magnolol can suppress TPA-induced activation of extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K)/Akt, which are upstream of NFkappaB. Moreover, magnolol significantly inhibited 7,12-dimethylbene[a]anthracene (DMBA)/TPA-induced skin tumor formation by reducing the tumor multiplicity, tumor incidence, and tumor size of papillomas at 20 weeks. All these results revealed that magnolol is an effective antitumor agent and that its inhibitory effect is through the down-regulation of inflammatory iNOS and COX-2 gene expression in mouse skin, suggesting that magnolol is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

gamma-Tocotrienol modulates the paracrine secretion of VEGF induced by cobalt(II) chloride via ERK signaling pathway in gastric adenocarcinoma SGC-7901 cell line

Hypoxia is a common characteristic feature of solid tumors, and carcinoma cells are known to secrete many growth factors. These growth factors, such as vascular endothelial growth factor (VEGF), play a major role in the regulation of tumor angiogenesis and metastasis. In this study, the effect of gamma-tocotrienol, a natural product commonly found in palm oil and rice bran, on the accumulation of HIF-1alpha protein and the paracrine secretion of VEGF in human gastric adenocarcinoma SGC-7901 cell line induced by cobalt(II) chloride (as a hypoxia mimic) was investigated. These results showed that cobalt(II) chloride induced the high expression of VEGF in SGC-7901 cells at dose of 150 micromol/L for 24h. Both basal level and cobalt(II) chloride-induced HIF-1alpha protein accumulation and VEGF paracrine secretion were inhibited in SGC-7901 cells treated with gamma-tocotrienol at 60 micromol/L treatment for 24 h. U0126, a MEK1/2 inhibitor, decreased the expression of HIF-1alpha protein and the paracrine secretion of VEGF under normoxic and hypoxic conditions. In this study, gamma-tocotrienol also significantly inhibited the hypoxia-stimulated expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2). The mechanism seems to involve in inhibiting hypoxia-mediated activation of p-ERK1/2, it leads to a marked decrease in hypoxia-induced HIF-1alpha protein accumulation and VEGF secretion. These data suggest that HIF-1alpha/VEGF could be a promising target for gamma-tocotrienol in an effective method of chemoprevention and chemotherapy in human gastric cancer.

Effect of the dibenzylbutyrolactone lignan (-)-hinokinin on doxorubicin and methyl methanesulfonate clastogenicity in V79 Chinese hamster lung fibroblasts

The dibenzylbutyrolactone lignan (-)-hinokinin (HK) was obtained by partial synthesis from (-)-cubebin, isolated from the dry seeds of the pepper, Piper cubeba. In view of the trypanocidal activity of HK and its potential as a lead compound for drug development, evaluation of its possible genotoxic activity is required. We have tested HK for possible genotoxicity and evaluated the compound's effect on the activity of the clastogens doxorubicin (DXR) and methyl methanesulfonate (MMS) in the micronucleus (MN) assay with Chinese hamster lung fibroblast V79 cells. HK alone did not induce MN, at concentrations up to 128microM. In combined treatments, HK reduced the frequency of MN induced by MMS. With respect to DXR, HK exerted a protective effect at lower concentrations, but at higher concentrations it potentiated DXR clastogenicity.

Sulforaphane- and phenethyl isothiocyanate-induced inhibition of aflatoxin B1-mediated genotoxicity in human hepatocytes: role of GSTM1 genotype and CYP3A4 gene expression

Primary cultures of human hepatocytes were used to investigate whether the dietary isothiocyanates, sulforaphane (SFN), and phenethyl isothiocyanate (PEITC) can reduce DNA adduct formation of the hepatocarcinogen aflatoxin B(1) (AFB). Following 48 h of pretreatment, 10 and 50 microM SFN greatly decreased AFB-DNA adduct levels, whereas 25muM PEITC decreased AFB-DNA adducts in some but not all hepatocyte preparations. Microarray and quantitative reverse transcriptase (RT)-PCR analyses of gene expression in SFN and PEITC-treated hepatocytes demonstrated that SFN greatly decreased cytochrome P450 (CYP) 3A4 mRNA but did not induce the expression of either glutathione S-transferase (GST) M1 or GSTT1. The protective effects of SFN required pretreatment; cotreatment of hepatocytes with SFN and AFB in the absence of pretreatment had no effect on AFB-DNA adduct formation. When AFB-DNA adduct formation was evaluated by GST genotype, the presence of one or two functional alleles of GSTM1 was associated with a 75% reduction in AFB-DNA adducts, compared with GSTM1 null. In conclusion, these results demonstrate that the inhibition of AFB-DNA adduct formation by SFN is dependent on changes in gene expression rather than direct inhibition of catalytic activity. Transcriptional repression of genes involved in AFB bioactivation (CYP3A4 and CYP1A2), but not transcriptional activation of GSTs, may be responsible for the protective effects of SFN. Although GSTM1 expression was not induced by SFN, the presence of a functional GSTM1 allele can afford substantial protection against AFB-DNA damage in human liver. The downregulation of CYP3A4 by SFN may have important implications for drug interactions.

Targeting the autophagy pathway for cancer chemoprevention

Autophagy is crucial for maintaining cellular homeostasis, coping with metabolic stress, and limiting oxidative damage. Several autophagy-deficient or knockout models show increased tumor incidence, implicating autophagy as a tumor suppressor. Autophagy is involved in multiple processes that may curb transformation, including the control of oncogene-induced senescence (OIS), which can limit progression to full malignancy, and efficient antigen presentation, which is crucial for immune cell recognition and elimination of nascent cancer cells. Activation of the autophagy pathway may therefore hold promise as a chemoprevention strategy. Caloric restriction, bioactive dietary compounds, or specific pharmacological activators of the autophagy pathway are all possible avenues to explore in harnessing the autophagy pathway in cancer prevention.

4beta-Hydroxywithanolide E from Physalis peruviana (golden berry) inhibits growth of human lung cancer cells through DNA damage, apoptosis and G2/M arrest

Background

The crude extract of the fruit bearing plant, Physalis peruviana (golden berry), demonstrated anti-hepatoma and anti-inflammatory activities. However, the cellular mechanism involved in this process is still unknown.

Methods

Herein, we isolated the main pure compound, 4β-Hydroxywithanolide (4βHWE) derived from golden berries, and investigated its antiproliferative effect on a human lung cancer cell line (H1299) using survival, cell cycle, and apoptosis analyses. An alkaline comet-nuclear extract (NE) assay was used to evaluate the DNA damage due to the drug.

Results

It was shown that DNA damage was significantly induced by 1, 5, and 10 μg/mL 4βHWE for 2 h in a dose-dependent manner (p < 0.005). A trypan blue exclusion assay showed that the proliferation of cells was inhibited by 4βHWE in both dose- and time-dependent manners (p < 0.05 and 0.001 for 24 and 48 h, respectively). The half maximal inhibitory concentrations (IC₅₀) of 4βHWE in H1299 cells for 24 and 48 h were 0.6 and 0.71 μg/mL, respectively, suggesting it could be a potential therapeutic agent against lung cancer. In a flow cytometric analysis, 4βHWE produced cell cycle perturbation in the form of sub-G₁ accumulation and slight arrest at the G₂/M phase with 1 μg/mL for 12 and 24 h, respectively. Using flow cytometric and annexin V/propidium iodide immunofluorescence double-staining techniques, these phenomena were proven to be apoptosis and complete G₂/M arrest for H1299 cells treated with 5 μg/mL for 24 h.

Conclusions

In this study, we demonstrated that golden berry-derived 4βHWE is a potential DNA-damaging and chemotherapeutic agent against lung cancer.

Covalent inhibition of bacterial quorum sensing

Chemical coordination of gene expression among bacteria as a function of population density is regulated by a mechanism known as 'quorum sensing' (QS). QS in Pseudomonas aeruginosa, an opportunistic pathogen that causes disease in immunocompromised patients, is mediated by binding of the transcriptional activator, LasR, to its ligand, 3-oxo-C(12)-HSL, leading to population-wide secretion of virulence factors and biofilm formation. We have targeted QS in P. aeruginosa with a set of electrophilic probes designed to covalently bind Cys79 in the LasR binding pocket, leading to specific inhibition of QS-regulated gene expression and concomitant reduction of virulence factor secretion and biofilm formation. This first example of covalent modification of a QS receptor provides a new tool to study molecular mechanisms of bacterial group behavior and could lead to new strategies for targeting bacterial virulence.

Anti-inflammatory agents as cancer therapeutics

Cancer prevention sometimes referred to as tertiary prevention or chemoprevention makes use of specific xenobiotics or drugs to prevent, delay, or retard the development of cancer. Over the last two decades or so cancer prevention has made significant strides. For example, prevention of lung cancer through smoking cessation; cervical cancer prevention through regular Pap smear tests; colon cancer prevention through screening colonoscopy; and prostate cancer reductions by prostate-specific antigen measurements in conjunction with regular prostate examinations. The seminal epidemiological observation that nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and other cancers has provided the impetus to develop novel chemoprevention approaches against cancer. To that end, a number of "designer drugs" have been synthesized that are in different stages of development, evaluation, and deployment. Some include the cyclooxygenase-2-specific inhibitors (coxibs), nitric oxide-releasing NSAIDs (NO-NSAIDs and NONO-NSAIDs), hydrogen sulfide-releasing NSAIDs, modulators of the lipoxygenase pathway, prostanoid receptor blockers, and chemokine receptor antagonists. In addition to these novel agents, there are also a host of naturally occurring compounds/micronutrients that have chemopreventive properties. This chapter reviews these classes of compounds, their utility and mechanism(s) of action against the background of mediators that link inflammation and cancer.

Differential apoptotic response of human cancer cells to organoselenium compounds

PURPOSE

Selenium (Se) compounds are well known to inhibit cell proliferation and induce cell death in human cancer cells. Respective chemical forms of Se are intracellularly metabolized via complicated pathways, which target distinct molecules and exhibit varying degrees of anti-carcinogenicity in different cancer types; however, the precise mechanisms by which Se activates apoptosis remain poorly understood.

METHODS

The effects of Se compounds, Se-methylselenocysteine (MSC), selenomethionine (SeMet), and selenite on cell proliferation, apoptosis and its pathway in established human carcinoma cell lines (HSC-3, -4, A549, and MCF-7) were investigated. Cancer cells were treated with each Se compound during different periods. Cell apoptosis, caspase activity and ER stress markers were analyzed by flow cytometric or immunoblotting analysis, respectively.

RESULTS

We examined four cell lines for their sensitivity to MSC and SeMet in comparison with selenite. SeMet increased apoptotic cells in p53-positive A549 cells, whereas MSC increased apoptotic cells in p53-mutated HSC-3 cells. High activities of caspase-3, -8 and -9 were observed during apoptosis, and a pan-caspase inhibitor, z-VAD-fmk, rescued the cell viability of HSC-3 cells exposed to MSC. In addition, the occurrence of endoplasmic reticulum (ER) stress was suggested by the observation that levels of phosphorylated eIF2alpha and caspase-12 activity are increased in Se-treated cells. Selenite and MSC were accompanied with the concurrent reduction of phosphorylated Akt levels, and the inhibitory effects of these Se compounds on vascular endothelial growth factor expression were observed with identical patterns.

CONCLUSION

The present findings demonstrate that Se-induced apoptosis in carcinoma cells is basically a caspase-dependent process involving complicated mechanisms. Activation of both the intrinsic apoptotic pathway and ER stress pathway plays a major and concurrent role, while p53 activation seems to have only a functional role in SeMet.

Rosmanol potently inhibits lipopolysaccharide-induced iNOS and COX-2 expression through downregulating MAPK, NF-kappaB, STAT3 and C/EBP signaling pathways

Rosmanol is a natural polyphenol from the herb rosemary (Rosmarinus officinalis L.) with high antioxidant activity. In this study, we investigated the inhibitory effects of rosmanol on the induction of NO synthase (NOS) and COX-2 in RAW 264.7 cells induced by lipopolysaccharide (LPS). Rosmanol markedly inhibited LPS-stimulated iNOS and COX-2 protein and gene expression, as well as the downstream products, NO and PGE2. Treatment with rosmanol also reduced translocation of the nuclear factor-kappaB (NF-kappaB) subunits by prevention of the degradation and phosphorylation of inhibitor kappaB (IkappaB). Western blot analysis showed that rosmanol significantly inhibited translocation and phosphorylation of NF-kappaB, signal transducer and activator of transcription-3 (STAT3), and the protein expression of C/EBPbeta and C/EBPdelta. We also found that rosmanol suppressed LPS-induced phosphorylation of ERK1/2, p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling. Our results demonstrate that rosmanol downregulates inflammatory iNOS and COX-2 gene expression by inhibiting the activation of NF-kappaB and STAT3 through interfering with the activation of PI3K/Akt and MAPK signaling. Taken together, rosmanol might contribute to the potent anti-inflammatory effect of rosemary and may have potential to be developed into an effective anti-inflammatory agent.

Dietary tricin suppresses inflammation-related colon carcinogenesis in male Crj: CD-1 mice

The flavone 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin) present in rice, oats, barley, and wheat exhibits antigrowth activity in several human cancer cell lines and anti-inflammatory potential. However, the chemopreventive activity has not yet been elucidated in preclinical animal models of colorectal cancer. This study was designed to determine whether dietary tricin exerts inflammation-associated colon carcinogenesis induced by azoxymethane and dextran sulfate sodium in mice. Male Crj: CD-1 mice were initiated with a single i.p. injection of azoxymethane (10 mg/kg body weight) and followed by a 1-week exposure to dextran sulfate sodium (1.5%, w/v) in drinking water to induce colonic neoplasms. They were then given the experimental diet containing 50 or 250 ppm tricin. The experiment was terminated at week 18 to determine the chemopreventive efficacy of tricin. In addition, the effects of dietary tricin on the expression of several inflammatory cytokines, including tumor necrosis factor (TNF)-alpha, were assayed. The development of colonic adenomas and adenocarcinomas was significantly reduced by feeding with 50 and 250 ppm tricin, respectively. Dietary tricin also significantly reduced the proliferation of adenocarcinoma cells as well as the numbers of mitoses/anaphase bridging in adenocarcinoma cells. The dietary administration with tricin significantly inhibited the expression of TNF-alpha in the nonlesional cypts. Our findings that dietary tricin inhibits inflammation-related mouse colon carcinogenesis by suppressing the expression of TNF-alpha in the nonlesional cyrpts and the proliferation of adenocarcinomas suggest a potential use of tricin for clinical trials of colorectal cancer chemoprevention.

Modulation of inflammatory genes by natural dietary bioactive compounds

Several epidemiologic studies have shown that chronic inflammation predisposes individuals to various types of cancer. Many cancers arise from sites of infection, chronic irritation, and inflammation. Conversely, an oncogenic change induces an inflammatory microenvironment that promotes the development of tumors. Natural bioactive compounds in dietary plant products including fruits, vegetables, grains, legumes, tea, and wine are claimed to help prevent cancer, degenerative diseases, and chronic and acute inflammation. Modern methods in cell and molecular biology allow us to understand the interactions of different natural bioactive compounds with basic mechanisms of inflammatory response. The molecular pathways of this cancer-related inflammation are now unraveled. Natural bioactive compounds exert anti-inflammatory activity by modulating pro-inflammatory gene expressions have shown promising chemopreventive activity. This review summarizes current knowledge on natural bioactive compounds that act through the signaling pathways and modulate inflammatory gene expressions, thus providing evidence for these substances in cancer chemopreventive action.

Pterostilbene inhibited tumor invasion via suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells

Pterostilbene, a natural dimethylated analog of resveratrol, is known to have diverse pharmacologic activities including anticancer, anti-inflammation, antioxidant, apoptosis, anti-proliferation and analgesic potential. However, the effects of pterostilbene in preventing invasion of cancer cells have not been studied. Here, we report our finding that pterostilbene significantly suppressed 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced invasion, migration and metastasis of human hepatoma cells (HepG(2) cells). Increase in the enzyme activity, protein and messenger RNA levels of matrix metalloproteinase (MMP)-9 were observed in TPA-treated HepG(2) cells, and these were blocked by pterostilbene. In addition, pterostilbene can inhibit TPA-induced expression of vascular endothelial growth factor, epidermal growth factor and epidermal growth factor receptor. Transient transfection experiments also showed that pterostilbene strongly inhibited TPA-stimulated nuclear factor kappa B (NF-kappaB) and activator protein-1 (AP-1)-dependent transcriptional activity in HepG(2) cells. Moreover, pterostilbene can suppress TPA-induced activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, c-Jun N-terminal kinases 1/2 and phosphatidylinositol 3-kinase/Akt and protein kinase C that are upstream of NF-kappaB and AP-1. Significant therapeutic effects were further demonstrated in vivo by treating nude mice with pterostilbene (50 and 250 mg/kg intraperitoneally) after inoculation with HepG(2) cells into the tail vein. Presented data reveal that pterostilbene is a novel, effective, anti-metastatic agent that functions by downregulating MMP-9 gene expression.