Anticancer therapeutic potential of soy isoflavone, genistein

Genistein inhibits proliferation and functions of hypertrophic scar fibroblasts

Hypertrophic scarring is abnormal proliferation of dermal fibroblasts and excessive deposition of extracellular matrix. To date, despite many studies, treatments have not been satisfactory. Genistein, a potent, specific inhibitor of tyrosine protein kinases (TPKs), has been proved to inhibit many kinds of tumour and some fibrotic diseases. The purpose of this study was to investigate the effects of genistein on the proliferation and functions of hypertrophic scar fibroblasts (HSFBs) and the mechanism by which genistein inhibits TPK signal transduction. The first effect was observed by methyl-thiazol-diphenyl-tetrazolium assay and the second by [gamma-(32)p] adenosine triphosphate incorporation assay. The results demonstrated that genistein inhibits the proliferation and function of HSFBs and changes the TPK signal transduction pathway, which can provide an experimental basis for treating HS with genistein.

Black soybean promotes the formation of active components with antihepatoma activity in the fermentation product of Agaricus blazei

The antihepatoma activity and related active components in the fermentation products of Agaricus blazei (AB) cultured in the medium containing soybean (S) or black soybean (BS) were investigated. AB(BS)-pE and AB(S)-pE were the ethanolic extracts from the fermentation products of AB(BS) and AB(S), respectively. According to the IC 50 values, AB(BS)-pE (161.1 and 24.0 microg/mL for Hep 3B and Hep G2 cells, respectively) exhibited stronger cytotoxicities against hepatoma cells than AB(S)-pE (>200 and 99.9 microg/mL for Hep 3B and Hep G2 cells, respectively). AB(BS)-pE was separated by silica gel column chromatography and eluted with n-hexane/ethyl acetate/methanol gradient solvent system into 21 fractions. Fraction 3 [AB(BS)-pE-F3], eluted with n-hexane/ethyl acetate (97:3 and 19:1, v/v), was the most active fraction having inhibitory activity on the proliferation of Hep 3B and Hep G2 cells (IC 50 of 3.6 and 1.9 microg/mL, respectively). Three major compounds, compounds 1- 3, were further isolated from the AB(BS)-pE-F3 fraction by reversed-phase semipreparative high-performance liquid chromatography. Compounds 2 and 3 gave better antihepatoma activity than that of compound 1. The IC 50 values of compounds 2 and 3 were 2.8 and 4.5 microg/mL for Hep 3B cells and 1.4 and 2.0 microg/mL for Hep G2 cells, respectively. The structures of compounds 2 and 3 were identified by UV, IR, electron impact mass spectrometry, and (1)H and (13)C NMR to be blazeispirols A and C, respectively. Blazeispirols A and C existed in the mycelia but not in the broth and were more in AB(BS)-pE (49.9 +/- 8.9 and 14.2 +/- 2.4 mg/g, respectively) than AB(S)-pE (15.9 +/- 1.7 and 3.9 +/- 0.6 mg/g, respectively). Additionally, the result shows that the production of blazeispirols A and C was increased after cultivation in the medium containing black soybean on day 6 and reached the maximum on day 12, and the contents of blazeispirols A and C were negatively correlated with Hep 3B and Hep G2 cell viabilities ( r = -0.84 to -0.93, P < 0.01). It suggests that blazeispirols A and C could be used as biomarkers to produce the fermentation product of A. blazei with antihepatoma activity.

Combination of active specific immunotherapy or adoptive antibody or lymphocyte immunotherapy with chemotherapy in the treatment of cancer

Successful treatment of cancer patients with a combination of monoclonal antibodies (mAb) and chemotherapeutic drugs has spawned various other forms of additional combination therapies, including vaccines or adoptive lymphocyte transfer combined with chemotherapeutics. These therapies were effective against established tumors in animal models and showed promising results in initial clinical trials in cancer patients, awaiting testing in larger randomized controlled studies. Although combination between immunotherapy and chemotherapy has long been viewed as incompatible as chemotherapy, especially in high doses meant to increase anti-tumor efficacy, has induced immunosuppression, various mechanisms may explain the reported synergistic effects of the two types of therapies. Thus direct effects of chemotherapy on tumor or host environment, such as induction of tumor cell death, elimination of regulatory T cells, and/or enhancement of tumor cell sensitivity to lysis by CTL may account for enhancement of immunotherapy by chemotherapy. Furthermore, induction of lymphopenia by chemotherapy has increased the efficacy of adoptive lymphocyte transfer in cancer patients. On the other hand, immunotherapy may directly modulate the tumor's sensitivity to chemotherapy. Thus, anti-tumor mAb can increase the sensitivity of tumor cells to chemotherapeutic drugs and patients treated first with immunotherapy followed by chemotherapy showed higher clinical response rates than patients that had received chemotherapy alone. In conclusion, combination of active specific immunotherapy or adoptive mAb or lymphocyte immunotherapy with chemotherapy has great potential for the treatment of cancer patients which needs to be confirmed in larger controlled and randomized Phase III trials.

Tyrosine kinase-independent inhibition by genistein on spermatogenic T-type calcium channels attenuates mouse sperm motility and acrosome reaction

Although the protein tyrosine kinase (PTK) inhibitor, genistein, has been widely used to investigate the possible involvement of PTK during reproductive functions, it is unknown whether it modulates sperm calcium channel activity. In the present study, we recorded T-type calcium currents (I(Ca,T)) in mouse spermatogenic cells using whole-cell patch clamp and found that extracellular application of genistein reversibly decreased I(Ca,T) in a concentration-dependent manner (IC(50) approximately 22.7 microM). To determine whether TK activity is required for I(Ca,T) inhibition, we found that peroxovanadate, a tyrosine phosphatase inhibitor, was ineffective in preventing the inhibitory effect of genistein. Furthermore, intracellular perfusion of the cells with ATP-gamma-S also did not alter the inhibitory effect of genistein. To further reveal the direct inhibitory mechanism of genistein on I(Ca,T), we applied into the bath lavendustin A, a PTK inhibitor structurally unrelated to genistein, and found that the current amplitude remained unchanged. Moreover, daidzein, an inactive structural analog of genistein, robustly inhibited the currents. The inhibitory effect of genistein on T-type calcium channels was associated with a hyperpolarizing shift in the voltage-dependence of inactivation. Genistein was observed to decrease sperm motility and to significantly inhibit sperm acrosome reaction (AR) evoked by zona pellucida. Using transfected HEK293 cells system, only Cav3.1 and Cav3.2, instead of Cav3.3, channels were inhibited by genistein. Since T-type calcium channels are the key components in the male reproduction, such as in AR and sperm motility, our data suggest that this PTK-independent inhibition of genistein on I(Ca,T) might be involved in its anti-reproductive effects.

Isoflavone daidzein possesses no antioxidant activities in cell-free assays but induces the antioxidant enzyme catalase

Epidemiologic studies have shown that dietary intake of isoflavonones is associated with several properties beneficial to human health. It has been suggested that at least some of these effects are related to the antioxidant activity of isoflavonoids. We analyzed the antioxidant activity of the major isoflavones found in soybeans, but none of these compounds showed prominent antioxidant effects in cell-free assay systems (trolox equivalent antioxidant capacity assay and 2,2-diphenyl-1-picrylhydrazyl assay). Therefore, we examined the hypothesis that the antioxidative effects of isoflavones are caused indirectly by up-regulation of antioxidative enzymes, thereby lowering intracellular concentration of reactive oxygene species. Daidzein shows a significant induction of catalase promoter activity at 100 micromol/L in a reporter gene assay and at 200 micromol/L in Northern blot experiments. Another hypothesis for antioxidant effects caused by isoflavones is due to metabolism by intestinal bacteria. Analyzing the daidzein metabolites 3'-OH-daidzein and 6-OH-daidzein in our cell culture model, we found strong antioxidant effects (2,2-diphenyl-1-picrylhydrazyl and trolox equivalent antioxidant capacity assay). We conclude that isoflavone daidzein up-regulates the antioxidant enzyme catalase but shows only little antioxidant capacity per se. Antioxidant effects of this dietary isoflavonone may also be due to formation of the antioxidant metabolites 6-OH-daidzein and 3'-OH-daidzein.

Puma is a novel target of soy isoflavone genistein but is dispensable for genistein-induced cell fate determination

Here, we attempted to identify novel target genes of genistein in human A549 cells. Using analysis of proteins related to cell cycle and apoptotic pathways, we confirmed an elevated level of p53 accompanying p21 Waf1/Cip1 protein in genistein-treated or genistin-treated A549 and WI-38 cells, but not in HeLa cells. In addition, a p53-upregulated modulator of apoptosis (Puma) protein accumulated significantly in genistein-treated A549 and WI-38 cells, but not in genistin-treated or beta-estradiol-treated cells, though the growth of any ingredient-treated cells was severely inhibited. Intriguingly, the caspase-3 activity of genistein-treated A549 cells, in which Puma or p53 expression was knocked-down by RNA interference (RNAi), remained unaltered compared to that in cells transfected with irrelevant RNAi. These results raise a concern that molecular targets identified by powerful omic approaches may not necessarily represent key molecules responsible for given cellular phenotypes and thus must be verified by conclusive assays.

Effects of hormone therapy and dietary soy on myocardial ischemia/reperfusion injury in ovariectomized atherosclerotic monkeys

OBJECTIVE

Hormone therapy (HT) and dietary soy (Soy) inhibit myocardial ischemia/reperfusion (I/R) injury in nonatherosclerotic animals. The aim of this study was to determine their independent and interactive effects on I/R in monkeys previously fed an atherogenic diet for 15 months.

DESIGN

Ovariectomized atherosclerotic monkeys (n = 40) were divided into one of four dietary treatment groups: (1) casein as the protein source, (2) casein and added HT (the equivalent of 5 mug ethinyl estradiol + 1 mg norethindrone acetate daily), (3) Soy protein providing 141 mg total isoflavones daily, or (4) Soy + HT. After 12 months monkeys were anesthetized, and their left anterior descending coronary artery was occluded for 1 hour and reperfused for 4 hours. Infarct size was the percentage of the area at risk not staining with triphenyltetrazolium chloride. Additional measures were myocardial blood flow, stroke volume, coronary output, myeloperoxidase, and malondialdehyde.

RESULTS

There was an interactive negative effect of HT + Soy to increase infarct size from approximately 30% (in other groups) to 55% (P = 0.0004). Additionally, there were negative main effects of Soy on blood flow, coronary output, and stroke volume during I/R (all P values <0.05). There were no effects of treatment on either myeloperoxidase or malondialdehyde.

CONCLUSIONS

Neither HT nor Soy had beneficial effects, whereas their combination had harmful effects, on myocardial I/R injury in monkeys with preexisting atherosclerosis. The mechanism of this negative interaction remains unclear but may relate to Soy's negative effects on hemodynamics.

Comparative evaluation of cytotoxicity and antioxidative activity of 20 flavonoids

Flavonoids are common dietary components with many health benefits shown through epidemiological studies. However, the fact that flavonoids also act as pro-oxidants and mutagens makes the safety of flavonoids uncertain when used at higher doses. To give a preliminary evaluation on the correlation between beneficial and harmful effects of flavonoids, the antioxidative activity and cytotoxicity of 20 flavonoids from food and herbs were investigated in vitro. The results indicated that luteolin, hydroxygenkwanin, and kaempferol possessed significant dual properties, whereas flavokawain B, flavokawain C, cardamonin, and uvangoletin showed a marked cytotoxicity. The relationships between structure and antioxidant and cytotoxic activity are intensively discussed. In view of the toxicity, the intake of flavonoids in large amounts should not yet be encouraged.

Multi-targeted therapy of cancer by genistein

Soy isoflavones have been identified as dietary components having an important role in reducing the incidence of breast and prostate cancers in Asian countries. Genistein, the predominant isoflavone found in soy products, has been shown to inhibit the carcinogenesis in animal models. There is a growing body of experimental evidence showing that the inhibition of human cancer cell growth by genistein is mediated via the modulation of genes that are related to the control of cell cycle and apoptosis. It has been shown that genistein inhibits the activation of NF-kappaB and Akt signaling pathways, both of which are known to maintain a homeostatic balance between cell survival and apoptosis. Moreover, genistein antagonizes estrogen- and androgen-mediated signaling pathways in the processes of carcinogenesis. Furthermore, genistein has been found to have antioxidant properties, and shown to be a potent inhibitor of angiogenesis and metastasis. Taken together, both in vivo and in vitro studies have clearly shown that genistein, one of the major soy isoflavones is a promising agent for cancer chemoprevention and further suggest that it could be an adjunct to cancer therapy by virtue of its effects on reversing radioresistance and chemoresistance. In this review, we attempt to provide evidence for these preventive and therapeutic effects of genistein in a succinct manner highlighting comprehensive state-of-the-art knowledge regarding its multi-targeted biological and molecular effects in cancer cells.

Early life and adult exposure to isoflavones and breast cancer risk

Soy and red-clover isoflavones are commonly consumed within the diet or as a dietary supplement due to a range of presumed beneficial health benefits. These isoflavones are thought to protect against heart diseases as well as breast and other types of cancer. Isoflavones are structurally similar to estrogens and may act as estrogen agonists or antagonists by binding to estrogen receptors. Because of an increased use of isoflavones in processed foods and dietary supplements as well as the greater consumption of soy products, dietary intakes of isoflavones are increasing in children and adolescents in North America. Estrogens are a known component of numerous hormone related cancers including breast cancer. It is with these facts in mind that we review the existing epidemiological and experimental animal studies for a resolution to a proposed correlation between increased isoflavone consumption and breast cancer. There is conflicting evidence from epidemiological, intervention and experimental animal studies regarding the chemopreventing effects of soy isoflavones in breast cancer. Isoflavones are weak estrogens and their effect depends upon the dose, time of exposure and species involved. It would, therefore, not be safe to indisputably accept soy or red-clover as a source of isoflavone resource to prevent breast cancer.

Inhibition of Cell Proliferation and MAP Kinase and Akt Pathways in Oral Squamous cell Carcinoma by Genistein and Biochanin A

High morbidity and mortality associated with oral squamous cell carcinoma (OSCC) are largely attributable to late stage diagnosis. Despite significant advances in therapeutic strategies, the five-year survival rate for oral cancer remains at about 50%. A chemopreventive approach may be an effective alternative or adjunct to current therapies. Previous studies have shown anti-tumor effects of isoflavones in several cancers, including oral cancer. However, their mechanisms of action are still unclear. We hypothesized that isoflavones inhibit multiple signaling pathways implicated in oral carcinogenesis. To address our hypothesis, we investigated the effects of three isoflavone derivatives, genistein, biochanin A and daidzein, on SCC15 and SCC25 squamous cell carcinoma cell lines. In cell proliferation experiments, we found that genistein and biochanin A inhibited SCC15 and SCC25 cell growth with an IC50 of 50 μM. We also investigated the effect of isoflavones on ERK and Akt pathways. Our results, from western blot analysis, suggest that both genistein and biochanin A induced decreases in phosphorylation of ERK and Akt at treatment concentrations of 20, 50 and 100 μM. Taken together, our results clearly demonstrate a differential regulation of signaling pathways by various isoflavones in OSCC cell lines. Thus, tumor progression models can be utilized to study the preventive and therapeutic roles of isoflavones in oral cancer cell lines.

Cloning, expression, and characterization of two beta-glucosidases from isoflavone glycoside-hydrolyzing Bacillus subtilis natto

On the basis of the genomic sequence of Bacillus subtilis 168, two beta-glucosidase genes (bglH and yckE) from B. subtilis natto, which has been reported to have high isoflavone glucoside-hydrolyzing activity, were cloned and overexpressed in E. coli M15. The temperature for the optimal p-nitrophenyl-beta-D-glucoside hydrolyzing activity of both enzymes was between 37 and 45 degrees C, but BglH had a higher thermal stability than YckE. Both showed high activity at pH 6.0, but YckE was stable over a wider pH range than BglH. Recombinant BglH was inhibited 73%, 63%, and 43% by 1.0 mM Cd(2+), Fe(2+), or Cu(2+), respectively, while other divalent metal ions resulted in 0-23% inhibition, whereas YckE was inhibited by less than 20% by any of the divalent metal ions we tested. Among the substrate we used, BglH showed the highest affinity for genistin and YckE showed the highest affinity for p-nitrophenyl-beta-D-fructopyranoside. Both BglH and YckE hydrolyzed genistin and daidzin into their isoflavone aglycones, genistein and daidzein, but BglH was more efficient than YckE in isoflavone glucoside hydrolysis (20-fold higher kcat). Our results suggest that recombinant BglH may be applicable in the process of isoflavones deglycosylation.

Antileukemic activity of genistein, a major isoflavone present in soy products

Soy has been used in traditional medicine for the treatment of various diseases, including cancer. The isoflavones present in soy have been shown in animal models to have cancer-preventing activity. However, the therapeutic effects of isoflavones against cancer are still unclear. We have evaluated the in vitro and in vivo antileukemic activity of genistein (1), a major isoflavone present in soy. We observed that it produced a dose- and time-dependent antineoplastic activity against myeloid and lymphoid leukemic cell lines. In addition, genistein treatment of the leukemic cells reactivated tumor suppressor genes that were silenced by aberrant DNA methylation. A genistein-enriched diet produced a moderate, but significant, antileukemic effect in mice. The limited extent of this in vivo response may have been due to the rapid metabolic inactivation of genistein in mice. Due to the longer half-life of genistein in humans, a soy-enriched diet has the potential to produce plasma levels of this isoflavone in the range of the concentrations used in vitro that produced an antileukemic activity.

Apigenin inhibits HGF-promoted invasive growth and metastasis involving blocking PI3K/Akt pathway and beta 4 integrin function in MDA-MB-231 breast cancer cells

Hepatocyte growth factor (HGF) and its receptor, Met, known to control invasive growth program have recently been shown to play crucial roles in the survival of breast cancer patients. The diet-derived flavonoids have been reported to possess anti-invasion properties; however, knowledge on the pharmacological and molecular mechanisms in suppressing HGF/Met-mediated tumor invasion and metastasis is poorly understood. In our preliminary study, we use HGF as an invasive inducer to investigate the effect of flavonoids including apigenin, naringenin, genistein and kaempferol on HGF-dependent invasive growth of MDA-MB-231 human breast cancer cells. Results show that apigenin presents the most potent anti-migration and anti-invasion properties by Boyden chamber assay. Furthermore, apigenin represses the HGF-induced cell motility and scattering and inhibits the HGF-promoted cell migration and invasion in a dose-dependent manner. The effect of apigenin on HGF-induced signaling activation involving invasive growth was evaluated by immunoblotting analysis, it shows that apigenin blocks the HGF-induced Akt phosphorylation but not Met, ERK, and JNK phosphorylation. In addition to MDA-MB-231 cells, apigenin exhibits inhibitory effect on HGF-induced Akt phosphorylation in hepatoma SK-Hep1 cells and lung carcinoma A549 cells. By indirect immunofluorescence microscopy assay, apigenin inhibits the HGF-induced clustering of beta 4 integrin at actin-rich adhesive site and lamellipodia through PI3K-dependent manner. Treatment of apigenin inhibited HGF-stimulated integrin beta 4 function including cell-matrix adhesion and cell-endothelial cells adhesion in MDA-MB-231 cells. By Akt-siRNA transfection analysis, it confirmed that apigenin inhibited HGF-promoted invasive growth involving blocking PI3K/Akt pathway. Finally, we evaluated the effect of apigenin on HGF-promoted metastasis by lung colonization of tumor cells in nude mice and organ metastasis of tumor cells in chick embryo. By histological and gross examination of mouse lung and real-time PCR analysis of human alu in host tissues, it showed that apigenin, wortmannin, as well as anti-beta 4 antibody all inhibit HGF-promoted metastasis. These data support the inhibitory effect of apigenin on HGF-promoted invasive growth and metastasis involving blocking PI3K/Akt pathway and integrin beta 4 function.

Effects of the phytoestrogen genistein on some predictors of cardiovascular risk in osteopenic, postmenopausal women: a two-year randomized, double-blind, placebo-controlled study

CONTEXT

Genistein, a soy isoflavone, has received wide attention over the last few years because of its potential preventive role for cardiovascular disease.

OBJECTIVE

Our objective was to assess the effects of genistein administration (54 mg/d) on some predictors of cardiovascular risk in osteopenic, postmenopausal women.

DESIGN AND SETTING

We conducted a randomized, double-blind, placebo-controlled trial at three Italian university medical centers.

INTERVENTION

After a 4-wk stabilization on a standard isocaloric, fat-reduced diet, participants were randomly assigned to receive genistein (n = 198) or placebo (n = 191) daily for 24 months. Both intervention and placebo contained calcium and vitamin D(3).

OUTCOME MEASURES

Blood lipid profiles, fasting glucose and insulin, homeostasis model assessment for insulin resistance, fibrinogen, soluble intercellular adhesion molecule-1, soluble vascular cellular adhesion molecule-1, F2-isoprostanes, and osteoprotegerin at baseline and after 12 and 24 months of treatment were measured.

RESULTS

Compared with placebo, genistein significantly reduced fasting glucose and insulin as well as homeostasis model assessment for insulin resistance after both 12 and 24 months of treatment. By contrast, genistein administration did not affect blood lipid levels although fibrinogen, F2-isoprostanes, soluble intercellular adhesion molecule-1, and soluble vascular cellular adhesion molecule-1 decreased significantly compared with placebo after 24 months. Serum osteoprotegerin was higher in the genistein group compared with placebo. At 24 months, the genistein group showed no change in endometrial thickness compared with placebo. Most treatment-related adverse events were moderate and composed of gastrointestinal side effects [genistein, n = 37 (19%); placebo, n = 15 (8%)].

CONCLUSIONS

These results suggest that 54 mg genistein plus calcium, vitamin D(3), and a healthy diet was associated with favorable effects on both glycemic control and some cardiovascular risk markers in a cohort of osteopenic, postmenopausal women.

In vitro and in vivo molecular evidence of genistein action in augmenting the efficacy of cisplatin in pancreatic cancer

We recently reported the potential of genistein in augmenting gemcitabine-induced killing of pancreatic cancer (Banerjee, S. et al., Cancer Research 2005;65:9064-72). Since cis-diaminedichloroplatinum (II) (cisplatin) is widely used against solid tumors, we further investigated whether genistein pretreatment could be used as a novel strategy for cisplatin-induced killing of pancreatic cancer cells in vitro and enhanced antitumor activity in vivo. Our in vitro results showed that pretreatment of cells with genistein followed by cisplatin resulted in significant loss of cell viability and potentiated apoptosis irrespective of the metastatic ability of cells. Mechanistically, genistein augmented cisplatin induced killing by down regulating transcription factor-NF-kappaB and anti-apoptotic Akt expression. NF-kappaB was found upregulated when pancreatic cancer cells were exposed to cisplatin, suggesting the potential mechanism of acquired chemo-resistance. In addition, we also showed, for the first time, that genistein in combination with cisplatin is more effective antitumor agent in our orthotopic tumor model. But most importantly, our data also showed that a specific target, such as NF-kappaB, was inactivated in animal tumors treated with genistein and cisplatin. Immunohistochemical data showed reduced staining for phospho-p65, Bcl-xL and MMP-9 in treated tumors compared to control tumors, but the lowest activity was seen in the combination group. These results provide strong molecular in vivo evidence in support of our hypothesis that inactivation of the NF-kappaB signaling pathway by genistein results in the chemo-sensitization of pancreatic tumors to cisplatin, which is likely to be an important and novel strategy for the treatment of pancreatic cancer.

Genistein protects methylglyoxal-induced oxidative DNA damage and cell injury in human mononuclear cells

Methylglyoxal (MG) is a reactive dicarbonyl compound produced mainly from glycolytic intermediates in the cell and often found at high level in the blood from the diabetic patients. Glycation reactions of MG with amino acids can induce oxidative stress and free radical generation, leading to subsequent cytotoxicity and apoptosis. Recently, studies have demonstrated that high level MG may be the main cause of immune dysfunction in diabetic patients. Here, we examined the effects of genistein, an antioxidant isoflavone compound, on MG-induced effects in vitro and in human mononuclear cells. We first monitored DNA strand breakage to examine the effect of 12.5-100 microM genistein on the ROS generation and oxidative DNA damage induced in vitro by a 50 microM MG/lysine glycation reaction (3h). Our results revealed that genistein concentrations higher than 25 microM decreased the oxidative stress and DNA damage induced by 50 microM MG/lysine. In mononuclear cells, pretreatment with 8-16 microM genistein for 1h followed by co-incubation with genistein and 50 microM MG for an additional 36 h inhibited MG-induced reactive oxygen species (ROS) generation and apoptosis. Finally, animal model experiments showed that dietary genistein effectively blocks MG-induced apoptosis in mononuclear cells. These results collectively suggest that oxidative stress plays a role in MG-induced cell injury, and that genistein blocks these effects by virtue of its antioxidant properties, consequently preventing cell apoptosis.

Correlation of ZAP-70 expression in B cell leukemias to the ex vivo response to a combination of fludarabine/genistein

The role of ZAP-70 expression on the ex vivo response of blood cells from CLL and PLL patients to a combination of fludarabine, a purine analog, and genistein, a tyrosine kinase inhibitor was studied. Patient cells were studied for the expression of ZAP-70 mRNA and its relation to the induction of apoptosis in response to treatment with genistein 15-60 muM and/or fludarabine 3 muM. The combination of genistein and fludarabine resulted in a significantly increased induction of apoptosis relative to the fludarabine alone. The ex vivo patient cells with a high ZAP-70 expression underwent more apoptosis in response to genistein than did patient cells with a low ZAP-70 mRNA expression. In contrast, basal IL-10 mRNA expression correlated negatively with apoptosis induction in response to genistein (P < 0.01). These studies suggest that, in malignant B cells that express elevated levels of the ZAP-70 signaling molecule, genistein may inhibit the ZAP-70 tyrosine kinase activity, resulting in cell death. The ZAP-70 may serve as a target for therapy. In addition, these studies suggest that the IL-10 expression by malignant B cells may not only suppress anti-tumor T cell responses in vivo, but also promote the survival of malignant B cells despite treatment with chemotherapeutic agents.

Combined treatment of ionizing radiation with genistein on cervical cancer HeLa cells

The anticancer agent genistein inhibits cell growth of tumor cell lines from various malignancies. In our study, we investigated the effectiveness of combined treatment of ionizing radiation (IR) with genistein on cervical HeLa cells and its possible mechanism. It was found that the inhibitory rate in cells with combined treatment was significantly higher than that of the cells treated with IR or genistein alone. After treatments of IR (4 Gy) combined with genistein (40 micromol/L), the apoptotic index of the cells was significantly increased and the cells were arrested in the G2/M phase. Survivin mRNA expression increased after IR (4 Gy), while it significantly decreased after combined treatment. These findings indicated that genistein enhanced the radiosensitivity of cervical cancer HeLa cells, and the mechanisms for this action might include increase of apoptosis, decrease of survivin expression, and prolongation of cell cycle arrest.

Protective role of wogonin against lipopolysaccharide-induced angiogenesis via VEGFR-2, not VEGFR-1

Wogonin, one of flavonoid derived from particular plants, enriches the property of anti-inflammation. Inflammation-stimulated angiogenesis plays an important role in many pathological diseases, such as rheumatoid arthritis, atherosclerosis, and cancer. The aim of this study was to investigate the suppressive effect of wogonin on lipopolysaccharide (LPS)-induced angiogenesis in human umbilical endothelial cell (HUVEC) cultures. By cell differentiation assays, migration and tube formation activity under LPS treatment were evaluated. Besides, IL-6 neutralizing antibody was added to test the inhibitory effect in the phenotypic alteration. Western blot analysis, ELISA cytokine assay, and quantitative real time-PCR were performed for VEGF, IL-6, VEGF receptors, and IL-6 receptor gene expressions on HUVEC with wogonin treatment. Furthermore, in vivo chorioallantoic membrane (CAM) assay was applied to evaluate the percentage of new vessels formation. The results revealed that wogonin (10(-8)-10(-5) M) inhibited LPS-induced angiogenesis in a concentration-dependent manner. The mRNA and protein expressions of VEGF, VEGFR-2, IL-6, and sIL-6Ralpha were attenuated (P<0.05), but not VEGFR-1. In the LPS-induced CAM model, our data suggested that wogonin (10(-8)-10(-5) M) significantly decreased new vessel formation and vascular network (P<0.05). We conclude that wogonin suppresses both in vitro and in vivo LPS-induced angiogenesis, through VEGFR-2, but not VEGFR-1.

Hydrolysis of black soybean isoflavone glycosides by Bacillus subtilis natto

Hydrolysis of isoflavone glycosides by Bacillus subtilis natto NTU-18 in black soymilk is reported. At the concentration of 3-5% (w/v), black soymilk in flask cultures, the isoflavones, daidzin, and genistin were highly deglycosylated within 24 h. Deglycosylation of isoflavones was further carried out in a 7-l fermenter with 5% black soymilk. During the fermentation, viable cells increased from 10(3) to 10(9) CFU ml(-1) in 15 h, and the activity of beta-glucosidase appeared at 8 h after inoculation and reached a maximum (3.3 U/ml) at 12 h, then decreased rapidly. Deglycosylation of isoflavone glycosides was observed at the same period, the deglycosylation rate of daidzin and genistin at 24 h was 100 and 75%, respectively. It is significantly higher than the previous reports of fermentation with lactic acid bacteria. In accordance with the deglycosylation of isoflavone glycosides, the estrogenic activity of the 24 h fermented black soymilk for ERbeta estrogen receptor increased to threefold; meanwhile, the fermented broth activated ERalpha estrogen receptor to a less extent than ERbeta. These results suggest that this fermentation effectively hydrolyzed the glycosides from isoflavone in black soymilk and the fermented black soymilk has the potential to be applied to selective estrogen receptor modulator products.

Inhibitive effect of genistein on hypoxia-induced basic fibroblast growth factor expression in human retinal pigment epithelium cells

AIM

The time course changes of basic fibroblast growth factor (bFGF) expression induced by hypoxia and the effects of genistein on hypoxia-induced bFGF expression in the human retinal pigment epithelium (RPE) cells were studied.

METHODS

The bFGF mRNA expression was examined by reverse transcription polymerase chain reaction. The bFGF protein expression was detected by Western blot.

RESULTS

Hypoxia significantly increased bFGF mRNA expression. The maximal level detected at 24 h was approximately two times that at the start of treatment. With pretreatment of genistein (10, 20, 50, 100, and 200 microM) for 30 min, the elevated expression of bFGF mRNA was suppressed in a concentration-dependent manner. bFGF mRNA expression was reduced to 30.4% by 200 microM of genistein when compared with that untreated with genistein. Hypoxia treatment also remarkably increased the expression of bFGF protein. At 24 h after hypoxia, when the highest expression of bFGF protein was observed, it was approximately two times as much as that at the start of treatment. Genistein (10, 20, 50, 100, and 200 microM) could also suppress bFGF protein expression in a concentration-dependent manner. The highest suppression was observed when exposed to 200 microM of genistein, which was 43% of control.

CONCLUSIONS

These results suggested that suppression of bFGF expression in RPE cells might partly account for the inhibitive effect of genistein on retinal neovascularization in vivo.

Interactions of daidzin with intramolecular G-quadruplex

The potential interaction of daidzin, an ingredient of soy isoflavones, with human telomeric antiparallel G-quadruplex dAG(3)(T(2)AG(3))(3) was studied using ESI-MS, PAGE, CD and molecular simulation. Experimental studies indicated that daidzin molecules interacted with dAG(3)(T(2)AG(3))(3) and formed DNA-daidzin complex with the stoichiometric ratio of 1:1 and 1:2. The transition temperature of the G-quadruplex increased at higher ratio of daidzin to DNA. Under molecular crowding conditions the interactions between daidzin and the G-quadruplex become much stronger. Combining computational simulation and experimental results, it is demonstrated that the dAG(3)(T(2)AG(3))(3)/daidzin complex with a stoichiometric ratio of 1:1 is stabilized through the pi-pi conjugacy interactions and hydrogen bondings between daidzin and the bases of G-quadruplex. This work provides guidance not only on exploring the molecular anti-cancer mechanism of dietary isoflavones, but also searching small natural products as promising anticancer candidates that can inhibit telomerase activity.

Genistein induces glucose-regulated protein 78 in mammary tumor cells

Preliminary studies have shown that genistein modulates the expression of some heat shock proteins in mammary tumor cells. In this study, we investigated the effect of genistein pretreatment on the expression of glucose-regulated protein 78 (GRP78) in both estrogen receptor-positive (MCF-7) and -negative (MDA-MB-231) cells. Genistein increased the expression of GRP78 in a dose- and time-dependent manner and suppressed glucose uptake in both cell lines. However, induction of GRP78 by genistein appears not to be directly associated with inhibition of glucose uptake. Genistein treatment also made MDA-MB-231 cells more sensitive to doxorubicin, probably via increased GRP78 expression, but had no effect or even decreased drug sensitivity in MCF-7 cells. These results suggest that genistein may be exploited as an enhancer of chemotherapeutic agents in certain types of breast cancer.

Phenoxodiol: isoflavone analog with antineoplastic activity

Phenoxodiol, a synthetic analog of the plant isoflavone genistein, represents a new generation of oncology drugs acting as multiple signal transduction regulators. Phenoxodiol exerts its effect mainly by the induction of apoptosis through multiple mechanisms resulting in degradation of antiapoptotic proteins, with increased levels being linked to chemoresistance in tumor cells. Preclinical studies with this agent showed promising anticancer activity leading to a potential role in the treatment of a wide range of solid and hematologic cancers. Early clinical studies, especially in chemotherapy-resistant ovarian cancer, showed minimal toxicity with minor antitumor activity. Hormone-refractory prostate cancer is another promising area in which phenoxodiol is being actively tested. Studies are ongoing to define the optimal use of this novel anticancer agent.

Essiac and Flor-Essence herbal tonics stimulate the in vitro growth of human breast cancer cells

BACKGROUND

People diagnosed with cancer often self-administer complementary and alternative medicines (CAMs) to supplement their conventional treatments, improve health, or prevent recurrence. Flor-Essence and Essiac Herbal Tonics are commercially available complex mixtures of herbal extracts sold as dietary supplements and used by cancer patients based on anecdotal evidence that they can treat or prevent disease. In this study, we evaluated Flor-Essence and Essiac for their effects on the growth of human tumor cells in culture.

METHODS

The effect of Flor-Essence and Essiac((R)) herbal tonics on cell proliferation was tested in MCF-7, MDA-MB-436, MDA-MB-231, and T47D cancer cells isolated from human breast tumors. Estrogen receptor (ER) dependent activation of a luciferase reporter construct was tested in MCF-7 cells. Specific binding to the ER was tested using an ICI 182,780 competition assay.

RESULTS

Flor-Essence and Essiac herbal tonics at 1%, 2%, 4% and 8% stimulated cell proliferation relative to untreated controls in both estrogen receptor positive (MCF-7 and T47D) and estrogen receptor negative (MDA-MB-231 and MDA-MB-436) cell lines. Exposure to the tonics also produced a dose-dependent increase in ER dependent luciferase activity in MCF-7 cells. A 10(-7) M concentration of ICI 182,780 inhibited the induction of ER dependent luciferase activity by Flor-Essence and Essiac, but did not affect cell proliferation.

CONCLUSION

Flor-Essence and Essiac Herbal Tonics can stimulate the growth of human breast cancer cells through ER mediated as well as ER independent mechanisms of action.

Photoprotective effect of isoflavone genistein on ultraviolet B-induced pyrimidine dimer formation and PCNA expression in human reconstituted skin and its implications in dermatology and prevention of cutaneous carcinogenesis

Genistein, the most abundant isoflavone of the soy derived phytoestrogen compounds, is a potent antioxidant and inhibitor of tyrosine kinase. We previously reported the antiphotocarcinogenic effects of genistein in SKH-1 murine skin, including its capacity for scavenging reactive oxygen species, inhibiting photodynamic DNA damage and downregulating UVB(ultra violet B)-induced signal transduction cascades in carcinogenesis. In this study we elucidate genistein's photoprotective efficacy within the context of full thickness human reconstituted skin relative to acute challenges with ultraviolet-B irradiation. Skin samples were pre-treated with three concentrations of genistein (10, 20 and 50 microM) 1 h prior to UVB radiation at 20 and 60 mJ/cm2. Proliferating cell nuclear antigen (PCNA) and pyrimidine dimer (PD) expression profiles were localized using immunohistochemical analysis on paraffin embedded samples 6 and 12 h post UVB exposure. Genistein dose dependently preserved cutaneous proliferation and repair mechanics at 20 and 60 mJ/cm2, as evidenced by the preservation of proliferating cell populations with increasing genistein concentrations and noticeable paucity in PCNA immunoreactivity in the absence of genistein. Genistein inhibited UV-induced DNA damage, evaluated with PD immunohistochemical expression profiles, demonstrated an inverse relationship with increasing topical genistein concentrations. Irradiation at 20 and 60 mJ/cm2 substantially induced PD formation in the absence of genistein, and a dose dependent inhibition of UVB-induced PD formation was observed relative to increasing genistein concentrations. Collectively all genistein pre-treated samples demonstrated appreciable histologic architectural preservation when compared with untreated specimens. These findings represent a critical link between our animal and cell culture studies with those of human skin and represent the first characterization of the dynamic alterations of UV-induced DNA damage and proliferating cell populations relative to pretreatment with genistein in human reconstituted skin. The implications of our findings serve as compelling validation to our conclusions that genistein may serve as a potent chemopreventive agent against photocarcinogenesis.

Genistein decreases food intake, body weight, and fat pad weight and causes adipose tissue apoptosis in ovariectomized female mice

Genistein, an isoflavone in soybean products, has estrogenic activity and is used as a natural substitute for estrogen replacement therapy in postmenopausal women. Genistein was also shown to decrease fat pad weight in female mice. The primary objective of this study was to determine the effect of genistein on adipose tissue apoptosis in vitro and in vivo. 3T3-L1 preadipocytes and mature adipocytes were treated with 0, 1, 10, 100, and 400 micromol/L genistein and then assayed for apoptosis, whereas only mature adipocytes were assayed for viability. Mature adipocytes treated with genistein demonstrated a dose-related increase in apoptosis. Ovariectomized female mice (9 mo old) were given 0, 150, or 1,500 mg/kg genistein in the semipurified phytoestrogen-free casein-based diet for 3 wk (n=10). After mice were killed, body composition was determined by dual-energy X-ray absorptiometry analysis, and parametrial (PM), inguinal (ING), and retroperitoneal (RP) fat pads were weighed and assayed for apoptosis (% DNA fragmentation). Genistein (1500 mg/kg) reduced food intake (FI) by 14% (P<0.01) and body weight (BW) by 9% (P<0.01). Body composition was not significantly affected, but PM and ING weights were decreased 22% (P<0.05) and 19% (P<0.07), respectively, by 1,500 mg/kg genistein. Apoptosis in ING fat was increased 290% (P<0.05) by 1,500 mg/kg genistein. These findings show that oral genistein treatment can reduce BW, mobilize body fat, and induce apoptosis of adipose tissue in ovariectomized female mice. Thus, genistein may be useful in treating or preventing increased adiposity after menopause.

Synergistic effects of protein tyrosine kinase inhibitor genistein with camptothecins against three cell lines in vitro

Genistein, a natural isoflavone product has been shown to induce cellular death and increase the apoptotic cell death induced by several DNA-damaging stimuli. We have explored the combined effect of genistein and camptothecins against three cell lines, HeLa (cervical cancer), OAW-42 (ovarian cancer) and L929 (normal fibroblasts). Combined effect was estimated in 96-well plates using the SRB method and median-effect analysis. Addition of genistein synergistically increased the antiproliferative affect of camptothecins, inhibiting the camptothecin-induced G2/M arrest and increasing the apoptotic cell population. In HeLa cells, genistein inhibited CDK1 phosphorylation after irinotecan treatment. Thus, abrogation of the G2/M checkpoint control by genistein may be a useful maneuver to increase cytotoxicity of agents that damage DNA and inhibit cell-cycle progression in the G2/M boundary.

Nonpeptidic small-molecule inhibitor of Bcl-2 and Bcl-XL, (-)-Gossypol, enhances biological effect of genistein against BxPC-3 human pancreatic cancer cell line

OBJECTIVES

In pancreatic cancer, several important survival molecules such as EGFR, NF-kappaB, and Bcl-2 or Bcl-XL are highly activated. Thus, agents that inhibit NF-kappaB activation, together with agents that directly inhibit Bcl-2 or Bcl-XL protein function, may lead to enhanced cell killing. (-)-Gossypol, a natural polyphenolic compound isolated from cottonseeds, is a dual and potent small-molecule inhibitor of Bcl-2 and Bcl-XL proteins, with a Ki value in the 300-600 nM range for both proteins.

METHODS

: The BxPC-3 human pancreatic cell line was used in this study. (-)-Gossypol was dissolved in DMSO at 20 mmol/L as stock solution, and genistein was dissolved in 0.1 M Na2CO3 to make a 10 mM stock solution. For cell viability, apoptosis, and NF-kappaB studies, MTT assay, histone/DNA ELISA, and Electrophoretic Mobility Shift Assay (EMSA) were used, respectively. Coimmunoprecipitation experiments were designed to study Bcl-XL/Bim heterodimerization, and Western blots to study cytochrome c release.

RESULTS

(-)-Gossypol showed a concentration-dependent growth inhibition effect against BxPC-3 pancreatic cancer cell line and induced apoptosis with no effect on normal peripheral blood lymphocytes. Results from coimmunoprecipitation experiments indicate that the effect of (-)-gossypol is mediated, at least, in part via disrupting the heterodimerization of Bcl-XL with Bim in BxPC-3 pancreatic cancer cells. (-)-Gossypol completely disrupts Bcl-XL/Bim heterodimerization with no change in the total Bcl-XL or Bim protein, indicating that (-)-gossypol treatment does not affect the levels of Bcl-XL and Bim proteins. We have previously shown that genistein, a prominent soy isoflavone, transcriptionally down-regulates Bcl-2, Bcl-XL, VEGF, MMP-9, and uPAR via inhibiting NF-kappaB activity. In this study, genistein down-regulated NF-kappaB DNA binding activity and inhibited the growth of BxPC-3 pancreatic cancer cells. In addition, the combination of (-)-gossypol with genistein showed significantly greater growth inhibition compared with either agent alone.

CONCLUSION

From these results, we conclude that inhibition of NF-kappaB activity and direct inhibition of Bcl-2 or Bcl-XL function should serve as a novel strategy for pancreatic cancer therapy.

Genistein, a natural product from soy, is a potent inhibitor of transthyretin amyloidosis

The misfolding of transthyretin (TTR), including rate-limiting tetramer dissociation and partial monomer denaturation, is sufficient for TTR misassembly into amyloid and other abnormal quaternary structures associated with three amyloid diseases: senile systemic amyloidosis, familial amyloid polyneuropathy, and familial amyloid cardiomyopathy. Small molecules can bind to one or both of the unoccupied TTR thyroid hormone-binding sites, stabilizing the native tetramer more than the dissociative transition state, thereby raising the kinetic barrier for tetramer dissociation. Herein we demonstrate that genistein, the major isoflavone natural product in soy, works in this fashion and is an excellent inhibitor of transthyretin tetramer dissociation and amyloidogenesis, reducing acid-mediated fibril formation to <10% of that exhibited by TTR alone. Genistein also inhibits the amyloidogenesis of the most common familial amyloid polyneuropathy and familial amyloid cardiomyopathy mutations in TTR: V30M and V122I, respectively. Genistein additionally inhibits tetramer dissociation under physiological conditions thought to lead to slow amyloidogenesis in humans. Furthermore, this natural product exhibits highly selective binding to TTR in plasma over all of the other plasma proteins. Isothermal titration calorimetry shows that genistein binds to TTR with negative cooperativity (K(d1) = 40 nM, K(d2) = 1.4 microM). The benefits of using a nutraceutical such as genistein to treat orphan diseases such as the TTR amyloidoses include known oral bioavailability and safety data. It is conceivable that some patients could benefit from simply increasing their intake of soy products or supplements.

Current progress in the use of traditional medicines and nutraceuticals

Traditional medicines in the form of botanical dietary supplements and nutraceuticals have found a place in 21st century healthcare. They nonetheless all contain compounds that are foreign to humans (i.e. xenobiotics) and that are subject to the same pharmacological issues encountered by synthetic therapeutic agents. It is crucial therefore for all parties, the medical profession, investigative scientists, the regulatory agencies and the public, to understand the particular characteristics of botanicals and nutraceuticals and their potential for success and failure in preventing and confronting disease.