Biphasic effect of daidzein on cell growth of human colon cancer cells

Soy-derived isoflavones as chemo-preventive agents targeting multiple signalling pathways for cancer prevention and therapy

The chemopreventive and chemotherapeutic properties of soy and soy-derived compounds, especially isoflavones, have been extensively studied in recent years. However, in contrast to their anticancer effects, such as cell growth inhibition, cell cycle arrest and apoptosis induction, isoflavones have also been found to promote the growth of cancer cells. Therefore, the aim of this comprehensive review article is to present the current state of knowledge regarding the molecular mechanisms by which soy-derived isoflavones target multiple cellular signalling pathways in cancer cells. Our findings indicate that soy-derived isoflavones act as, among other things, potent modulators of HOX transcript antisense RNA (HOTAIR)/SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), vascular endothelial growth factor (VEGF)/C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor type 4 (CXCR4), 17-β-oestradiol (E2)/oestrogen receptor-α (ERα)/neuroglobin (NGB) and sonic hedgehog signalling pathways, epigenetic modulatory agents (i.a. miR-155, miR-34a and miR-10a-5p) and cancer stem cells and epithelial-to-mesenchymal transition inhibitors. The paper also discusses the latest epidemiological studies and clinical trials and provides an insight into recent extensive research on the chemo-preventive and therapeutic potential of soy-derived isoflavones.

Anticancer Effects of Washed-Dehydrated Solar Salt Doenjang on Colon Cancer-Induced C57BL/6 Mice

This study researched the mineral composition of Korean washed-dehydrated solar salt (WDS) without bittern. It also evaluated the anticancer effects of doenjang (WDSD) prepared using WDS on azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon cancer in C57BL/6 mice. The mineral composition of WDS showed lower Mg (11.71 ± 1.89 g/kg) and S (9.77 ± 2.88 g/kg) contents, and it was confirmed that mice in the WDSD group (AOM/DSS+WDSD) displayed significantly lower weight loss, colon length reduction, and tumor formation compared with the control (Con) group. In addition, pathologically, it was confirmed that the extent of epithelial cell damage and inflammation in the colon tissue of the WDSD group was restored to a state similar to that of the Nor group. Besides, WDSD regulated the protein expression of apoptosis (Bcl-2-associated X protein [Bax], B cell lymphoma-2 [Bcl-2], B cell lymphoma-extra large [Bcl-xL], and caspase 9, caspase 3), and p53, p21, and proinflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α), thereby inducing the apoptosis and cell cycle arrest of cancer cells and suppressing inflammation. In addition, the intestinal microbiota of the mice treated with WDSD were more diverse, with an abundance of Bifidobacterium, a lactic acid bacterium beneficial to colon health, was also a greater presence of Faecalibaculum, which showed antitumor effects. These results indicate that solar salts and their different processing methods affect their functional health-promoting properties. In addition, the inhibitory effect on colon cancer was further enhanced when doenjang was prepared with WDS with low Mg and S content.

Unveiling the Pharmacological and Nanotechnological Facets of Daidzein: Present State-of-the-Art and Future Perspectives

Herbal drugs have been attracting much scientific interest in the last few decades and nowadays, phytoconstituents-based research is in progress to disclose their unidentified medicinal potential. Daidzein (DAI) is the natural phytoestrogen isoflavone derived primarily from leguminous plants, such as the soybean and mung bean, and its IUPAC name is 4',7-dihydroxyisoflavone. This compound has received great attention as a fascinating pharmacophore with remarkable potential for the therapeutic management of several diseases. Certain pharmacokinetic properties of DAI such as less aqueous solubility, low permeability, and poor bioavailability are major obstacles restricting the therapeutic applications. In this review, distinctive physicochemical characteristics and pharmacokinetics of DAI has been elucidated. The pharmacological applications in treatment of several disorders like oxidative stress, cancer, obesity, cardiovascular, neuroprotective, diabetes, ovariectomy, anxiety, and inflammation with their mechanism of action are explained. Furthermore, this review article comprehensively focuses to provide up-to-date information about nanotechnology-based formulations which have been investigated for DAI in preceding years which includes polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carrier, polymer-lipid nanoparticles, nanocomplexes, polymeric micelles, nanoemulsion, nanosuspension, liposomes, and self-microemulsifying drug delivery systems.

Daidzein Induces Intrinsic Pathway of Apoptosis along with ER α/β Ratio Alteration and ROS Production

Background:

Low risk of breast cancer is observed among females consuming a moderate quantity of soy throughout their life. The present study was conducted to evaluate the anticancer potential of Daidzein, one of the major Isoflavones in soy using Human breast cancer cells MCF-7.

Methods:

MCF-7 were subjected to various doses of Daidzein treatment to determine the IC50 value. Onset of apoptosis was ascertained by AnnexinV assay and caspase 3/7 activity post treatment. Expression of pro-apoptotic protein Bax and anti-apoptotic protein Bcl2 was also assessed to further confirm apoptotic mode of cell death. ROS production post treatment with Daidzein was assessed to ascertain the apoptosis via intrinsic pathway. Expression of ER α and ER β was evaluated by western blot analysis.

Results:

Human breast cancer cells MCF-7 were found to be sensitive to Daidzein treatment, with an IC₅₀ value of 50µM. Increased percentage of treated cells stained with Annexin V confirmed apoptosis mediated cell death. Activity of Caspase 3/7 activity was found to be 1.4-fold higher in Daidzein treated cells than control cells, confirming apoptosis. Daidzein caused over expression of Bax and down-regulated expression of Bcl2. There has been an outburst of ROS in Daidzein treated cells indicating that Daidzein induces apoptosis via intrinsic pathway. A decrease in the expression of ER α and increase in levels of ER β has been observed which are conducive indicator of apoptosis.

Conclusions:

In conclusion, the present study suggests that Daidzein induces apoptosis in MCF-7 cells by mitochondrial pathway along with lowering the ratio of ER α/β and an outburst of Reactive Oxygen Species(ROS).

Biphasic Dose-Response Induced by Phytochemicals: Experimental Evidence

Many phytochemicals demonstrate nonmonotonic dose/concentration-response termed biphasic dose-response and are considered to be hormetic compounds, i.e., they induce biologically opposite effects at different doses. In numerous articles the hormetic nature of phytochemicals is declared, however, no experimental evidence is provided. Our aim was to present the overview of the reports in which phytochemical-induced biphasic dose-response is experimentally proven. Hence, we included in the current review only articles in which the reversal of response between low and high doses/concentrations of phytochemicals for a single endpoint was documented. The majority of data on biphasic dose-response have been found for phytoestrogens; other reports described these types of effects for resveratrol, sulforaphane, and natural compounds from various chemical classes such as isoquinoline alkaloid berberine, polyacetylenes falcarinol and falcarindiol, prenylated pterocarpan glyceollin1, naphthoquinones plumbagin and naphazarin, and panaxatriol saponins. The prevailing part of the studies presented in the current review was performed on cell cultures. The most common endpoint tested was a proliferation of tumor and non-cancerous cells. Very few experiments demonstrating biphasic dose-response induced by phytochemicals were carried out on animal models. Data on the biphasic dose-response of various endpoints to phytochemicals may have a potential therapeutic or preventive implication.

Cellular and molecular alterations induced by low‑dose fisetin in human chronic myeloid leukemia cells

The present study aimed to evaluate the cellular and molecular effects of low concentrations of the flavonoid, fisetin, on K562 human chronic myeloid leukemia cells, in the context of both potential anti-proliferative and anti-metastatic effects. Thiazolyl blue tetrazolium bromide assay, Trypan blue exclusion assay, Annexin V/propidium iodide test, cell cycle analysis, Transwell migration and invasion assays, the fluorescence staining of β-catenin and F-actin as well as reverse transcription-quantitative polymerase chain reaction were performed to achieve the research goal. Furthermore, the nature of the interaction between fisetin and arsenic trioxide in the K562 cells was analyzed according to the Chou-Talalay median-effect method. We found that low concentrations of fisetin had not only a negligible effect on the viability and apoptosis of the K562 cells, but also modulated the mRNA levels of selected metastatic-related markers, accompanied by an increase in the migratory and invasive properties of these cancer cells. Although some markers of cell death were significantly elevated in response to fisetin treatment, these were counterbalanced through anti-apoptotic and pro-survival signals. With decreasing concentrations of fisetin and arsenic trioxide, the antagonistic interactions between the 2 agents increased. On the whole, the findings of this study suggest that careful consideration should be taken when advising cancer patients to take fisetin as a dietary supplement and when considering fisetin as a potential candidate for the treatment of chronic myeloid leukemia. Further more detailed studies are required to confirm our findings.

Preparation and Pharmacokinetic Study of Daidzein Long-Circulating Liposomes

In this study, daidzein long-circulating liposomes (DLCL) were prepared using the ultrasonication and lipid film-hydration method. The optimized preparation conditions by the orthogonal design was as follows: 55 to 40 for the molar ratio of soybean phosphatidylcholine (SPC) to cholesterol, 1 to 10 for the mass ratio of daidzein to total lipid (SPC and cholesterol) (w:w), the indicated concentration of 5% DSPE-mPEG2000 (w:w), 50 °C for the hydration temperature, and 24 min for the ultrasonic time. Under these conditions, the encapsulation efficiency and drug loading of DLCL were 85.3 ± 3.6% and 8.2 ± 1.4%, respectively. The complete release times of DLCL in the medium of pH 1.2 and pH 6.9 increased by four- and twofold of that of free drugs, respectively. After rats were orally administered, a single dose of daidzein (30 mg/kg) and DLCL (containing equal dose of daidzein), respectively, and the MRT_0-t (mean residence time, which is the time required for the elimination of 63.2% of drug in the body), t_1/2 (the elimination half-life, which is the time required to halve the plasma drug concentration of the terminal phase), and AUC_0-t (the area under the plasma drug concentration-time curve, which represents the total absorption after a single dose and reflects the drug absorption degree) of daidzein in DLCL group, increased by 1.6-, 1.8- and 2.5-fold as compared with those in the free group daidzein. Our results indicated that DLCL could not only reduce the first-pass effect of daidzein to promote its oral absorption, but also prolong its mean resident time to achieve the slow-release effect.

Safety evaluation of Semen Sojae Preparatum based on simultaneous LC-ESI-MS/MS quantification of aflatoxin B1 , B2 , G1 , G2 and M1

Semen Sojae Preparatum (SSP) is one of the most widely used traditional Chinese medicines, and is also a functional food. However, contamination with aflatoxins may occur in the fermentation process. To evaluate its safety, an accurate and rapid LC-ESI-MS/MS analytical method was developed and validated for the simultaneous determination of AFB₁ , AFB₂ , AFG₁ , AFG₂ and AFM₁ in SSP. After a simple ultrasonic extraction of SSP samples, chromatographic separation was achieved on an Agilent Zorbax SB-C₁₈ column (2.1 × 50 mm, 3.5 μm) with a flow rate of 0.50 mL/min. The gradient elution program was performed using a mobile phase consisting of water and acetonitrile, both containing 0.1% formic acid. Detection of five aflatoxins was based on triple quadrupole mass spectrometry using a multiple reaction monitoring mode with an electrospray ionization source. SSP is likely to be contaminated by aflatoxins in the processes of fermentation, storage, transportation and usage, and it is necessary to strictly monitor it. Artemisia annua L. and Morus alba L. may inhibit the production and growth of AFB₁ - and AFB₂ -producing fungi, which has a certain detoxification effect on contamination with aflatoxins in SSP.

The cytotoxic and genotoxic effects of daidzein on MIA PaCa-2 human pancreatic carcinoma cells and HT-29 human colon cancer cells

Daidzein (DZ) has anti-inflammatory and antioxidant effects, as well as the dose-dependent inhibition effect on cancer cells. In this study, the cytotoxic and genotoxic effects of DZ on HT-29 (human colorectal adenocarcinoma cells) and MIA PaCa-2 (human pancreatic cancer cells) cell lines were determined using the XTT method and Comet assay, respectively. IC₅₀ concentrations of DZ were found to be 200 µM in both MIA PaCa-2 and HT-29 cells treated with DZ for 48 hours (h). When the cells were treated with 200 μM of DZ for 48 h, DNA damage was observed in both cell lines. DNA tail length (TL), tail moment (TM), and tail intensity (TI) increased more in MIA PaCa-2 cells treated with 200 μM of DZ than those in the control cell (untreated MIA PaCa-2 cell) group (p < 0.01). However, only DNA-TI and DNA-TM exhibited higher increases in HT-29 cells treated with 200 μM of DZ than those in the control cell (untreated HT-29 cell) group (p < 0.01). This shows that DZ has cytotoxic and genotoxic effects on both cell lines. The observed genotoxic effects of DZ still need to be confirmed in additional future studies.

Simultaneous high-performance liquid chromatography with diode array detection and time-of-flight mass spectrometric confirmation of the ten bioactive compounds in Semen Sojae Preparatum

Semen Sojae Preparatum is one of the most widely used traditional Chinese medicines. A reliable and accurate high-performance liquid chromatography with diode array detection method has been developed and validated for the quantitative determination of the ten bioactive compounds contained in Semen Sojae Preparatum. The samples were first extracted by pressurized liquid extraction using 80% ethanol at 100°C for 15 min and three static extraction cycles. Chromatographic separation was conducted on a C18 column using a mobile phase consisting of water and acetonitrile under gradient elution, and the detection wavelength was set at 210 nm. The samples were further analyzed on a high-performance liquid chromatography with time-of-flight mass spectrometry system to confirm the determination results. All the ten analytes were well separated, and the calibration curves showed good linearity. The intra- and interday precisions were evaluated in terms of relative standard deviation values within the ranges of 0.20-1.43% and 0.40-4.78%, respectively. The recoveries for the ten analytes were all in the ranges of 96.2-104.3%, with relative standard deviation values < 3.85%. The established high-performance liquid chromatography method could serve as a reliable and accurate method for the quality evaluation of Semen Sojae Preparatum from different origins.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

Raman microspectroscopy for probing the impact of a dietary antioxidant on human breast cancer cells

Breast cancer is the second most common type of cancer worldwide and the most frequent among women, being the fifth cause of death from neoplastic disease. Since this is an oxidative-stress related neoplasia, it is largely preventable. A dietary isoflavone abundant in soybean - daidzein - is currently being investigated owing to its chemopreventive and/or chemotherapeutic properties towards the human MDA-MB-231 (metastatic, estrogen-unresponsive) and MCF-7 (estrogen-responsive) breast cancer cell lines. Biological assays for evaluation of antitumour and anti-invasive activities were combined with state-of-the-art vibrational microspectroscopy techniques. At 50 and 100 μM concentrations and 48 h incubation time, daidzein was found to induce a marked decrease in cell viability (ca. 50%) for MDA-MB-231 and MCF-7 cells (respectively ca. 50% and 42%) and 40% inhibition of cell migration. MicroRaman analysis of fixed cells upon exposure to this isoflavone unveiled its metabolic impact on both cell lines. Multivariate data analysis (unsupervised PCA) led to a clear discrimination between the control and DAID-exposed cells, with distinctive effects on their biochemical profile, particularly regarding DNA, lipids and protein components, in a cell-dependent way. This is the first reported study on the impact of dietary antioxidants on cancer cells by microRaman techniques.

Unraveling the mechanisms involved in zearalenone-mediated toxicity in permanent fish cell cultures

The world-wide occurrence of zearalenone (ZEN) as a contaminant in feed for farm animals and fish requires the evaluation of toxicity mechanisms of action of ZEN. The present study investigates possible metabolization of ZEN in fish cell lines suggesting that mainly glucuronidation takes place. It demonstrates that concentrations up to 20,000 ng ml(-1) ZEN are capable of influencing cell viability in permanent fish cell cultures in a dose-response manner with different response patterns between the five tested cell lines, whereby lysosomes appeared to be the main target of ZEN. ZEN toxicity is often discussed in the context of oxidative stress. Our study shows a biphasic response of the cell lines when reactive oxygen species (ROS) production is monitored. Damage in cells was observed by measuring lipid peroxidation, DNA strand breaks, and alterations of intracellular glutathione levels. Metabolization of ZEN, especially at concentrations above 7500 ng ml(-1) ZEN, does not prevent cytotoxicity. ZEN as an estrogenic compound may involve processes mediated by binding to estrogen receptors (ER). Since one cell line showed no detectable expression of ER, an ER-mediated pathway seems to be unlikely in these cells. This confirms a lysosomal pathway as a main target of ZEN in fish cells.

O-desmethylangolensin inhibits the proliferation of human breast cancer MCF-7 cells by inducing apoptosis and promoting cell cycle arrest

The aim of the present study was to investigate the anticancer effect of O-desmethylangolensin (O-DMA) by assessing cell proliferation, apoptosis and cell cycle distribution, as well as exploring the mechanisms underlying these effects in breast carcinoma MCF-7 cells. The cells were exposed to O-DMA (5–200 μM) for 24, 48 and 72 h. The results revealed that cell proliferation was significantly inhibited in a dose-dependent manner following treatment for 48 and 72 h, but not after 24 h, and resulted in the significant induction of apoptosis and the promotion of cell cycle arrest at the G₁/S and G₂/M phases. To elucidate these effects of O-DMA, the expression levels of cell cycle regulators were measured in the cells exposed to O-DMA at 150 μM for 72 h. Of the G₁/S phase-related proteins, O-DMA modulated the cyclin-dependent kinases (CDKs), with a decrease in CDK2 and CDK4 and an increase in CDK6, and downregulated cyclin D and E. With respect to the G₂/M-related proteins, O-DMA caused a reduction in CDK1, together with a slight increase in cyclin A and B. In addition, O-DMA downregulated p21^Cip1 and p27^Kip1, but not p16^INK4a and p15^INK4b, and interacted with the CDK6-cyclin D and CDK1-cyclin B complexes. In conclusion, these results indicate for the first time that the regulation of the CDK4/6-cyclin D and CDK1-cyclin B complexes may participate in the anticancer activity pathway of O-DMA in MCF-7 cells.

Equol enhances tamoxifen's anti-tumor activity by induction of caspase-mediated apoptosis in MCF-7 breast cancer cells

BACKGROUND

Soy phytoestrogens, such as daidzein and its metabolite equol, have been proposed to be responsible for the low breast cancer rate in Asian women. Since the majority of estrogen receptor positive breast cancer patients are treated with tamoxifen, the basic objective of this study is to determine whether equol enhances tamoxifen's anti-tumor effect, and to identify the molecular mechanisms involved.

METHODS

For this purpose, we examined the individual and combined effects of equol and tamoxifen on the estrogen-dependent MCF-7 breast cancer cells using viability assays, annexin-V/PI staining, cell cycle and western blot analysis.

RESULTS

We found that equol (>50 μM) and 4-hydroxy-tamoxifen (4-OHT; >100 nM) significantly reduced the MCF-7 cell viability. Furthermore, the combination of equol (100 μM) and 4-OHT (10 μM) induced apoptosis more effectively than each compound alone. Subsequent treatment of MCF-7 cells with the pan-caspase inhibitor Z-VAD-FMK inhibited equol- and 4-OHT-mediated apoptosis, which was accompanied by PARP and α-fodrin cleavage, indicating that apoptosis is mainly caspase-mediated. These compounds also induced a marked reduction in the bcl-2:bax ratio, which was accompanied by caspase-9 and caspase-7 activation and cytochrome-c release to the cytosol. Taken together, these data support the notion that the combination of equol and tamoxifen activates the intrinsic apoptotic pathway more efficiently than each compound alone.

CONCLUSIONS

Consequently, equol may be used therapeutically in combination treatments and clinical studies to enhance tamoxifen's effect by providing additional protection against estrogen-responsive breast cancers.

Antiproliferative activity of daidzein and genistein may be related to ERα/c-erbB-2 expression in human breast cancer cells

In this study, we investigated the antiproliferative activity of the isoflavones daidzein and genistein in three breast cancer cell lines with different patterns of estrogen receptor (ER) and c‑erbB‑2 protein expression (ERα‑positive MCF‑7 cells, c‑erbB‑2‑positive SK‑BR‑3 cells and ERα/c‑erbB‑2‑positive ZR‑75‑1). After treatment at various concentrations (1‑200 µM for 72 h), the effect of daidzein and genistein on the proliferation of different cell types varied; these effects were found to be associated with ERα and c‑erbB‑2 expression. Daidzein and genistein exhibited biphasic effects (stimulatory or inhibitory) on proliferation and ERα expression in MCF‑7 cells. Although 1 µM daidzein significantly stimulated cell growth, ERα expression was unaffected. However, genistein showed marked increases in proliferation and ERα expression after exposure to <10 µM genistein. Notably, the inhibition of cell proliferation by 200 µM genistein was greater compared to that by daidzein at the same concentration. Daidzein and genistein significantly inhibited proliferation of SK‑BR‑3 and ZR‑75‑1 cells in a dose‑dependent manner. In addition, ERα and c‑erbB‑2 expression was reduced by daidzein and genistein in both SK‑BR‑3 and ZR‑75‑1 cells in a dose‑dependent manner. However, the effect of genistein was greater compared to that of daidzein. In conclusion, the isoflavones daidzein and genistein showed anti‑breast cancer activity, which was associated with expression of the ERα and c‑erbB‑2 receptors.

Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses

For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.

Comparative effect of genistein and daidzein on the expression of MCP-1, eNOS, and cell adhesion molecules in TNF-α-stimulated HUVECs

We compared the effects of genistein and daidzein on the expression of chemokines, cell adhesion molecules (CAMs), and endothelial nitric oxide synthase (eNOS) in tumor necrosis factor (TNF)-α-stimulated human umbilical vascular endothelial cells (HUVECs). TNF-α exposure significantly increased expression of monocyte chemoattractant protein (MCP)-1, vascular adhesion molecule (VCAM)-1, and intercellular adhesion molecule-1. Genistein significantly decreased MCP-1 and VCAM-1 production in a dose-dependent manner, whereas CAM expression was not significantly lowered by genistein treatment. However, daidzein slightly decreased MCP-1 production. The effects of genistein and daidzein on MCP-1 secretion coincided with mRNA expression. Pre-treatment with either genistein or daidzein elevated eNOS expression and nitric oxide production disturbed by TNF-α exposure. A low concentration of isoflavones significantly inhibited nuclear factor (NF)κB activation, whereas a high dose slightly ameliorated these inhibitive effects. These results suggest that genistein had a stronger effect on MCP-1 and eNOS expression than that of daidzein. Additionally, NFκB transactivation might be partially related to the down-regulation of these mRNAs in TNF-α-stimulated HUVECs.

Risks and benefits of dietary isoflavones for cancer

A high intake of fruits and vegetables is associated with a lower risk of cancer. In this context, considerable attention is paid to Asian populations who consume high amounts of soy and soy-derived isoflavones, and have a lower risk for several cancer types such as breast and prostate cancers than populations in Western countries. Hence, interest focuses on soyfoods, soy products, and soy ingredients such as isoflavones with regard to their possible beneficial effects that were observed in numerous experiments and studies. The outcomes of the studies are not always conclusive, are often contradictory depending on the experimental conditions, and are, therefore, difficult to interpret. Isoflavone research revealed not only beneficial but also adverse effects, for instance, on the reproductive system. This is also the case with tumor-promoting effects on, for example, breast tissue. Isoflavone extracts and supplements are often used for the treatment of menopausal symptoms and for the prevention of age-associated conditions such as cardiovascular diseases and osteoporosis in postmenopausal women. In relation to this, questions about the effectiveness and safety of isoflavones have to be clarified. Moreover, there are concerns about the maternal consumption of isoflavones due to the development of leukemia in infants. In contrast, men may benefit from the intake of isoflavones with regard to reducing the risk of prostate cancer. Therefore, this review examines the risks but also the benefits of isoflavones with regard to various kinds of cancer, which can be derived from animal and human studies as well as from in vitro experiments.

Soy-derived isoflavones inhibit HeLa cell growth by inducing apoptosis

Isoflavones are among the major bioactive compounds found in a wide variety of plant-derived foods, especially in soybeans and soy-based foods. In this study, the effect of a soy-derived isoflavone mixture (designated as SI-I, containing 71% daidzein, 14.3% genistein and 14.7% glycitein) on HeLa cells and its mechanism were investigated. SI-I in concentration range 5-80 μg/ml significantly reduced the survival rate of HeLa cells by MTT assay, whereas showed no side effect on that of L929 cells. After HeLa cells were exposed to 10, 20 and 40 μg/ml SI-I for 4 days, typical apoptotic morphological changes, including nuclear fragmentation, cytoplasm shrinkage and decrease of cell volume, were observed by fluorescence microscope and CLSM, respectively. FCM analysis revealed that the percentages of early apoptotic cells with lost Δψm increased by 2.27, 2.74 and 4.05 folds respectively, compared with control. The results showed that SI-I inhibited HeLa cell growth through inducing apoptosis via the mitochondrial pathway and comparisons with reported data indicated that synergistic effect existed between the isoflavone species contained in SI-I. It is proposed that natural soy-derived isoflavones are potential candidates as chemotherapeutic agents against human cervical cancer.

Potential health-modulating effects of isoflavones and metabolites via activation of PPAR and AhR

Isoflavones have multiple actions on cell functions. The most prominent one is the activation of estrogen receptors. Other functions are often overlooked, but are equally important and explain the beneficial health effects of isoflavones. Isoflavones are potent dual PPARα/γ agonists and exert anti-inflammatory activity, which may contribute to the prevention of metabolic syndrome, atherosclerosis and various other inflammatory diseases. Some isoflavones are potent aryl hydrocarbon receptor (AhR) agonists and induce cell cycle arrest, chemoprevention and modulate xenobiotic metabolism. This review discusses effects mediated by the activation of AhR and PPARs and casts a light on the concerted action of isoflavones.

Genistein and daidzein prevent low potassium-dependent apoptosis of cerebellar granule cells

We have investigated the ability of certain dietary flavonoids, known to exert beneficial effects on the central nervous system, to affect neuronal apoptosis. We used cerebellar granule cells undergoing apoptosis due to potassium deprivation in a serum-free medium in either the absence or presence of the flavonoids genistein and daidzein, which are present in soy, and of catechin and epicatechin, which are present in cocoa. These compounds were used in a blood dietary concentration range. We found that genistein and daidzein, but not catechin and epicatechin, prevented apoptosis, with cell survival measured 24h after the induction of apoptosis being higher than that of the same cells incubated in flavonoid free medium (80% and 40%, respectively); there was no effect in control cells. A detailed investigation of the effect of these compounds on certain mitochondrial events that occur in cells en route to apoptosis showed that genistein and daidzein prevented the impairment of glucose oxidation and mitochondrial coupling, reduced cytochrome c release, and prevented both impairment of the adenine nucleotide translocator and opening of the mitochondrial permeability transition pore. Interestingly, genistein and daidzein were found to reduce the levels of reactive oxygen species, which are elevated in cerebellar granule cell apoptosis. These findings strongly suggest that the prevention of apoptosis depends mainly on the antioxidant properties of genistein and daidzein. This could lead to the development of a flavonoid-based therapy in neuropathies.

Isoflavones are safe compounds for therapeutical applications - evaluation of in vitro data

Isoflavone-rich food and food supplements have gained increasing popularity also in the Western world. Their weak estrogenic effect has been considered as a potential risk, although all epidemiological studies and clinical trials show a significant cancer protection and decreased risk of cardiovascular diseases. In vitro data suggest that the concerted action of the isoflavones and their metabolites show antiproliferative behaviour, reduce angiogenesis, reduce tumor progression and exert antiinflammatory effects. For the evaluation of the biological effects, special emphasis has to be put on the concerted action between the isoflavones and their metabolites. For instance, while isolated genistein shows some growth promoting effect at low concentrations, the metabolite equol or soy extract show growth retardation as well as higher concentrations of genistein do. The isoflavones have multiple affinities to other members of the steroid hormone receptor superfamily. The beneficial effect on metabolic diseases and weight reduction by isoflavone consumption can be partly explained by its affinity for the PPAR family. In light of the in vitro experiments, together with the epidemiological observations and the clinical experience, isoflavones can be considered as safe compounds and their consumption as food and food supplements has to be promoted.

Multi-functional sample preparation procedure for measuring phytoestrogens in milk, cereals, and baby-food by liquid-chromatography tandem mass spectrometry with subsequent determination of their estrogenic activity using transcriptomic assay

A method dedicated to the determination of a multiple range of phytoestrogens as endocrine disruptor compounds in infant food products was developed, with as double objective the specific measurement of 13 parameters and the evaluation of the estrogenic potency associated to this quantitative profile. A combined enzymatic and acidic chemical hydrolysis followed by a double purification on two successive C(18) and SiOH Solid Phase Extraction cartridges permitted to efficiently purify milk, cereals and baby-food samples while eliminating naturally occurring estrogen hormones. A specific liquid chromatography-tandem mass spectrometric measurement authorised unambiguous identification and quantification of the target compounds. The proposed methodology was fully validated and applied to a set of around 30 real samples, demonstrating the presence of phytoestrogens at levels globally ranging from several microgkg(-1) (ppb) to several tens mgkg(-1) (ppm). The prepared sample extracts were proven to be suitable and compatible with the evaluation of their induced biological transcriptional activity on MCF-7 cell lines. Because permitting to cope with difficult issues such as low-dose and mixture effects, this proposed methodology may appear of particular interest for further exposure assessment studies and hazard characterisation investigations related to this class of endocrine disruptor compounds.

Equol induces apoptosis through cytochrome c-mediated caspases cascade in human breast cancer MDA-MB-453 cells

This study investigated the role of the caspase activation cascade in extrinsic and intrinsic apoptosis induced by equol in human breast cancer MDA-MB cells. First, the antiproliferative effect of equol was determined in cells treated with 1-100 microM equol for 24, 48, and 72h. Equol significantly inhibited cell proliferation in a dose-dependent manner (p<0.05). Exposure to 50 or 100 microM equol for 72h strongly promoted apoptosis. Under the same conditions, remarkable cytochrome c release was observed. Subsequently, caspase-9, which acts in mitochondria-mediated apoptosis, was cleaved by equol at high concentrations, but caspase-8 activation of receptor-mediated apoptosis was not observed. At both equol concentrations, the caspase-8 and -9 activity assays showed similar patterns. In addition, equol treatment activated caspase-3, which is downstream from caspase-9, and this was accompanied by the cleavage of capase-6 and -7. Activation of these caspases leads to increased activation of PARP, lamin, and ICAD. This study suggests that equol induces the intrinsic pathway of apoptosis via caspase-9 and cytochrome c, independent of caspase-8, in human breast cancer MDA-MB-453 cells.

Daidzein causes cell cycle arrest at the G1 and G2/M phases in human breast cancer MCF-7 and MDA-MB-453 cells

We examined the mechanisms by which daidzein inhibits the growth of breast cancer cells. First, we investigated its antiproliferative effects in MCF-7 and MDA-MB-453 cells exposed to 1-100 microM daidzein for 24, 48, or 72 h. Daidzein significantly inhibited cell proliferation in a dose- and time-dependent manner (p<0.05) and resulted in significant cell cycle arrest in the G1 and G2/M phases after 72 h of treatment at concentrations over 5 and 10 microM in MCF-7 and MDA-MB-453 cells, respectively (p<0.05). In addition, daidzein caused the accumulation of cells in sub-G0 phase in a dose-dependent manner in MDA-MB-453 (p<0.05), but not MCF-7, cells. As another biomarker of apoptosis induction, caspase-9 activity was significantly increased by daidzein in both cells. To investigate the effects of daidzein on the proteins regulating cell cycle arrest, cells were treated with 100 microM daidzein for 72 h. Similar changes in the expression of regulatory proteins were detected in both cells. Daidzein treatment resulted in decreases in cyclin D, CDK2, and CDK4, whereas the expression of CDK6 and cyclin E was unchanged. The protein expression of CDK1 related to the G2/M phase decreased markedly with daidzein treatment, whereas slight expression of cyclins A and B occurred. Daidzein treatment increased the expression of the CDK inhibitors p21(Cip1) and p57(Kip2), but not that of p27(Kip1). Thus, daidzein exerts its anticancer effects in human breast cancer cells via cell cycle arrest at the G1 and G2/M phases.

Glycitein activates extracellular signal-regulated kinase via vascular endothelial growth factor receptor signaling in nontumorigenic (RWPE-1) prostate epithelial cells

Increased consumption of soy is associated with a decreased risk for prostate cancer; however, the specific cellular mechanisms responsible for this anticancer activity are unknown. Dietary modulation of signaling cascades controlling cellular growth, proliferation and differentiation has emerged as a potential chemopreventive mechanism. The present study examined the effects of four soy isoflavones (genistein, daidzein, glycitein and equol) on extracellularsignal-regulated kinase (ERK1/2) activity in a nontumorigenic prostate epithelial cell line (RWPE-1). All four isoflavones (10 micromol/L) significantly increased ERK1/2 activity in RWPE-1 cells, as determined by immunoblotting. Isoflavone-induced ERK1/2 activation was rapid and sustained for approximately 2 h posttreatment. Glycitein, the most potent activator of ERK1/2, decreased RWPE-1 cell proliferation by 40% (P<.01). Glycitein-induced ERK1/2 activation was dependent, in part, on tyrosine kinase activity associated with vascular endothelial growth factor receptor (VEGFR). The presence of both VEGFR1 and VEGFR2 in the RWPE-1 cell line was confirmed by immunocytochemistry. Treatment of RWPE-1 cells with VEGF(165) resulted in transient ERK1/2 activation and increased cellular proliferation. The ability of isoflavones to modulate ERK1/2 signaling cascade via VEGFR signaling in the prostate may be responsible, in part, for the anticancer activity of soy.

Isolation of six isoflavones from Semen sojae praeparatum by preparative HPLC

A method for the isolation of six isoflavones (genistein, genistin, daidzein, daidzin, glycitein and glycitin) with high purity from Semen sojae praeparatum, a famous traditional Chinese medicine, by preparative HPLC is described.

Estrogenic and antioxidant effects of a phytoestrogen daidzein on ovarian germ cells in embryonic chickens

The estrogenic and antioxidant effects of the phytoestrogen daidzein (DAI) on germ cell proliferation were evaluated by a chicken ovarian germ-somatic cell coculture model. Ovarian cells were dispersed from 18-day-old embryos, cultured in serum-free McCoy's 5A medium and challenged with DAI alone or in combinations with estrogen receptor antagonist tamoxifen for 48 h. The number of germ cells was counted and the proliferating cells were identified by immunocytochemistry of proliferating cell nuclear antigen (PCNA). The labeling index (LI) was determined for germ cells. Results showed that DAI significantly increased the number of germ cells (P<0.05) and this stimulating effect was inhibited by tamoxifen in a dose-dependent manner. Furthermore, PCNA-LI of germ cells displayed similar changes with the number of germ cells. To estimate the antioxidant action of DAI, ovarian cells were exposed to the reactive oxygen species (ROS)-producing system hypoxanthine/xanthine oxidase (HX/XO). The changes of superoxide dismutase (SOD) activity and glutathione (GSH) level were measured for estimation of the antioxidant status. Ovarian cells were severely damaged by free radicals and this deteriorating effect could be prevented by DAI. Moreover, HX/XO-induced decrease in SOD activity and GSH level was restored by DAI (P<0.05). These results indicated that DAI promoted proliferation of cultured ovarian germ cells by estrogenic action and attenuated ROS-induced toxicity by antioxidant action in embryonic chickens.

Genistein inhibits insulin-like growth factor-I receptor signaling in HT-29 human colon cancer cells: a possible mechanism of the growth inhibitory effect of Genistein

Genistein, a soy isoflavone, has attracted much attention for its chemopreventive properties. Overexpression and constitutive activation of receptor tyrosine kinases are frequent events in human cancer. Because genistein has previously been reported to decrease HT-29 cell growth, the present study compared the effects of genistein with daidzein on the protein levels of the members of the ErbB receptor family and insulin-like growth factor-I (IGF-I) receptor (IGF-IR). HT-29 cells were cultured in serum-free medium, with 0, 25, 50, or 100 micromol/L genistein, daidzein, and/or 10 nmol/L IGF-I. DNA synthesis was estimated by 5-bromo-2'-deoxyuridine incorporation. Apoptotic cells were analyzed by annexin-V staining followed by flow cytometry. Genistein inhibited viable HT-29 cell numbers, in a dose-dependent manner, whereas daidzein had no effect on cell growth. The decrease in cell growth caused by genistein was due to decreased DNA synthesis and apoptosis induction. Immunoblot analysis showed that neither genistein nor daidzein decreased the protein levels of either of the epidermal growth factor receptors, ErbB2 or ErbB3. Genistein did, however, decrease the IGF-IR protein levels, whereas daidzein had no effect. Genistein did not change the protein levels of insulin-receptor substrate-1 (IRS-1), the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K), or Akt. Immunoprecipitation/western blot analyses revealed that genistein decreased IGF-I-stimulated phosphorylation of IGF-IR and IRS-1, recruitment of p85 to IGF-IR, and phosphorylation of Akt. These results suggest that inhibition of cell proliferation and induction of apoptosis by genistein are mediated, at least in part, by its ability to inhibit IGF-IR signaling and the PI3K/Akt pathway.

Genistein modulates prostate epithelial cell proliferation via estrogen- and extracellular signal-regulated kinase-dependent pathways

Epidemiological evidence suggests that consumption of soy is associated with a decreased risk for prostate cancer. Genistein, the most abundant isoflavone present in soy, is thought to be responsible, in part, for these anticancer effects. The present study examined the effects of genistein on cellular proliferation, extracellular signal-regulated kinase (ERK1/2) activity and apoptosis in a nontumorigenic human prostate epithelial cell line (RWPE-1). Low concentrations of genistein (0-12.5 micromol/L) significantly increased cell proliferation and ERK1/2 activity (P<.01) in RWPE-1 cells, while higher concentrations (50 and 100 micromol/L) of genistein significantly inhibited cell proliferation and ERK1/2 activity (P<.001). A similar biphasic effect of genistein on MEK1 activity, an ERK1/2 kinase, was also observed. Pretreatment of cells with a MEK1 inhibitor (PD 098059) significantly blocked genistein-induced proliferation and ERK1/2 activity (P<.01). In addition, treatment of cells with ICI 182,780, a pure antiestrogen, inhibited genistein-induced RWPE-1 proliferation and ERK1/2 signaling. Taken together, these results suggest that genistein modulates RWPE-1 cell proliferation and signal transduction via an estrogen-dependent pathway involving ERK1/2 activation.

Comprehensive analysis of the effect of phytoestrogen, daidzein, on a testicular cell line, using mRNA and protein expression profile

In this study, we examined the effects of exposure to phytoestrogen (daidzein), 17beta-estradiol (E2), diethylstilbestrol (DES) and staurosporin on the TM4 testicular cell line, using comprehensive analysis, such as cDNA microarray and two-dimension polyacrylamide gel electropholesis (2D-PAGE) analysis, and we demonstrated if these toxicogenomic analyses could classify the chemical compounds. First, RNA was extracted from TM4 cells that had been treated with daidzein (80 microM), DES, E2 (40 microM) and stauroporin (100 nM) for 30 min. We performed cDNA microarray analysis, and the expression ratio data thus obtained were then analyzed using hierarchical clustering. This hierarchical clustering showed that daidzein exposure induced a different effect on gene expression change from that of E2, DES and staurosporin. Next, protein extracted from TM4 cells also underwent cDNA microarray analysis for 3 h. We performed 2D-PAGE analysis, and the spot intensity ratio data thus obtained were analyzed using hierarchical clustering. As with cDNA microarray, the hierarchical clustering of protein spot ratios showed that daidzein exposure induced a different effect on gene expression change from that of the other substances. In conclusion, we have demonstrated for the first time that classification of these chemicals can be performed by clustering analysis, using data from cDNA microarray and 2D-PAGE analyses, and that exposure to daidzein induces effects different from those of E2, DES and staurosporin.