Soy isoflavones modulate azoxymethane-induced rat colon carcinogenesis exposed pre- and postnatally and inhibit growth of DLD-1 human colon adenocarcinoma cells by increasing the expression of estrogen receptor-beta

Delineating the role of nuclear receptors in colorectal cancer, a focused review

Colorectal cancer (CRC) stands as one of the most prevalent form of cancer globally, causing a significant number of deaths, surpassing 0.9 million in the year 2020. According to GLOBOCAN 2020, CRC ranks third in incidence and second in mortality in both males and females. Despite extensive studies over the years, there is still a need to establish novel therapeutic targets to enhance the patients' survival rate in CRC. Nuclear receptors (NRs) are ligand-activated transcription factors (TFs) that regulate numerous essential biological processes such as differentiation, development, physiology, reproduction, and cellular metabolism. Dysregulation and anomalous expression of different NRs has led to multiple alterations, such as impaired signaling cascades, mutations, and epigenetic changes, leading to various diseases, including cancer. It has been observed that differential expression of various NRs might lead to the initiation and progression of CRC, and are correlated with poor survival outcomes in CRC patients. Despite numerous studies on the mechanism and role of NRs in this cancer, it remains of significant scientific interest primarily due to the diverse functions that various NRs exhibit in regulating key hallmarks of this cancer. Thus, modulating the expression of NRs with their agonists and antagonists, based on their expression levels, holds an immense prospect in the diagnosis, prognosis, and therapeutical modalities of CRC. In this review, we primarily focus on the role and mechanism of NRs in the pathogenesis of CRC and emphasized the significance of targeting these NRs using a variety of agents, which may represent a novel and effective strategy for the prevention and treatment of this cancer.

Targeting the crosstalk between canonical Wnt/β-catenin and inflammatory signaling cascades: A novel strategy for cancer prevention and therapy

Emerging scientific evidence indicates that inflammation is a critical component of tumor promotion and progression. Most cancers originate from sites of chronic irritation, infections and inflammation, underscoring that the tumor microenvironment is largely orchestrated by inflammatory cells and pro-inflammatory molecules. These inflammatory components are intimately involved in neoplastic processes which foster proliferation, survival, invasion, and migration, making inflammation the primary target for cancer prevention and treatment. The influence of inflammation and the immune system on the progression and development of cancer has recently gained immense interest. The Wnt/β-catenin signaling pathway, an evolutionarily conserved signaling strategy, has a critical role in regulating tissue development. It has been implicated as a major player in cancer development and progression with its regulatory role on inflammatory cascades. Many naturally-occurring and small synthetic molecules endowed with inherent anti-inflammatory properties inhibit this aberrant signaling pathway, making them a promising class of compounds in the fight against inflammatory cancers. This article analyzes available scientific evidence and suggests a crosslink between Wnt/β-catenin signaling and inflammatory pathways in inflammatory cancers, especially breast, gastrointestinal, endometrial, and ovarian cancer. We also highlight emerging experimental findings that numerous anti-inflammatory synthetic and natural compounds target the crosslink between Wnt/β-catenin pathway and inflammatory cascades to achieve cancer prevention and intervention. Current challenges, limitations, and future directions of research are also discussed.

Animal Models of Colorectal Cancer: From Spontaneous to Genetically Engineered Models and Their Applications

Colorectal cancer is one of the most common gastrointestinal malignancies in humans, affecting approximately 1.8 million people worldwide. This disease has a major social impact and high treatment costs. Animal models allow us to understand and follow the colon cancer progression; thus, in vivo studies are essential to improve and discover new ways of prevention and treatment. Dietary natural products have been under investigation for better and natural prevention, envisioning to show their potential. This manuscript intends to provide the readers a review of rodent colorectal cancer models available in the literature, highlighting their advantages and disadvantages, as well as their potential in the evaluation of several drugs and natural compounds’ effects on colorectal cancer.

The Complex Puzzle of Interactions Among Functional Food, Gut Microbiota, and Colorectal Cancer

Colorectal cancer exerts a strong influence on the epidemiological panorama worldwide, and it is directly correlated to etiologic factors that are substantiated by genetic and environmental elements. This complex mixture of factors also has a relationship involving the structural dependence and composition of the gut microbiome, leading to a dysbacteriosis process that may evolve to serious modifications in the intestinal lining, eventually causing the development of a neoplasm. The gastrointestinal tract presents defense strategies and immunological properties that interfere in intestinal permeability, inhibiting the bacterial translocation, thus maintaining the integrity of intestinal homeostasis. The modulation of the intestinal microbiome and the extinction of risk factors associated with intestinal balance losses, especially of environmental factors, make cell and defense alterations impossible. This modulation may be conducted by means of functional foods in the diet, especially soluble fibers, polyunsaturated fatty acids, antioxidants and prebiotics that signal immunomodulatory effects in the intestinal microbiota, with preventive and therapeutic action for colorectal cancer. In summary, this review focuses on the importance of dietary modulation of the intestinal microbiota as an instrument for dysbacteriosis and, consequently, for the prevention of colorectal cancer, suggesting anticarcinogenic, and antiangiogenic properties. Among the intestinal modulating agents considered here are functional foods, especially flaxseed, oat and soy, composing a Bioactive Food Compound.

Fermented Ganjangs (Soy Sauce and Sesame Sauce) Attenuates Colonic Carcinogenesis in Azoxymethane/Dextran Sodium Sulfate-Treated C57BL/6J Mice

The effects of different ganjangs (also designated as kanjang), including acid-hydrolyzed soy sauce (AHSS), fermented soy sauce (FSS), and fermented sesame sauce (FSeS), on azoxymethane (AOM, 10 mg/kg)/dextran sulfate sodium (DSS, 2%)-induced colorectal carcinogenesis in C57BL/6J mice were studied. Low doses (4 mL/kg) of both FSeS and FSS significantly increased colon length, suppressed AOM/DSS-induced increases in colon weight/length ratios, and induced colorectal neoplasia compared with AHSS-treated and control mice. Fermented sauces, particularly low doses of FSeS and FSS, showed activity against AOM/DSS-induced colorectal carcinogenesis by abrogating serum and mRNA levels of tumor necrosis factor-α, interferon-γ, interleukin (IL)-6, and IL-17α as well as by reducing mRNA levels of inducible nitric oxide synthase and cyclooxygenase-2 in colon mucosa. FSeS significantly increased colonic p53 expression compared with other sauces. However, AHSS showed weak activity against AOM/DSS-induced colonic carcinogenesis. Overall, FSeS showed the strongest anticancer effect, followed by FSS and AHSS. Thus, fermentation with microorganisms rather than chemical processes is important, and raw materials are another factor influencing anticancer activity.

Dietary intake of flavonoid subclasses and risk of colorectal cancer: evidence from population studies

Objective

To systematically evaluate the relationship between flavonoids intake and colorectal cancer risk by conducting a meta-analysis.

Results

Our meta-analysis included 18 studies involving 16,917 colorectal cancer cases in 559,486 participants in relations to flavonoids intake during six to twenty-six years of follow-up. Our results indicated that specific flavonoid subclasses, such as procyanidins (OR = 0.75; 95% CI, 0.66–0.86) and isoflavones (OR = 0.87; 95% CI, 0.78–0.98), showed protective effects against colorectal cancer risk. There was no enough evidence indicating that increased consumption of total flavonoids were significantly associated with reduced risk of colorectal cancer (OR = 0.94, 95% CI, 0.81–1.09). There was no publication bias across studies.

Methods

We performed a systematic search of PubMed, Web of Science and the Cochrane Library databases for relevant articles before December 2015. A random-effects model was used to estimate summary odds ratios and 95% confidence intervals (CIs) for associations between flavonoids and colorectal cancer risk. We assessed heterogeneity among studies by the Cochran Q and I² statistics.

Conclusions

Our meta-analysis provides comprehensive evidence and partly supported the hypothesis that higher habitual intake of foods rich in procyanidins and isoflavones may potentially decrease colorectal cancer incidence. More prospective studies are warranted to verify this protective association.

Effects of Genistein and Synergistic Action in Combination with Tamoxifen on the HepG2 Human Hepatocellular Carcinoma Cell Line

Introduction: The flavonoids comprise a diverse group of polyphenolic compounds with antioxidant activity that is present in edible plants like soybeans and soy products. In vivo studies have concentrated on the effects of flavonoids on cancer and genistein (GE), a soy-derived isoflavone, has been reported to reduce prostate, colon, hepatic and breast adenocarcinoma risk. Tamoxifen (TAM) is an important drug for cancer treatment worldwide, which can induce apoptosis in various cancers, including examples in the liver, breast and ovaries. The aim of the present study was to evaluate the effects of GE and TAM, alone and in combination, on proliferation and apoptosis in the human hepatocellular carcinoma (HCC) HepG2 cell line. Materials and Methods: HepG 2 cells were treated with GE, TAM and GE/TAM and then MTT and flow cytometry assays were conducted to determine effects on viability and apoptosis, respectively. Results: GE and TAM inhibited cell proliferation and induced apoptosis in the HepG 2 cell lines. Discussion: Our findings clearly indicated that GE and TAM may exert inhibitory and apoptotic effects in liver cancer cells. Conclusion: GE and TAM can significantly inhibit growth of HCC cells and play a significant role in apoptosis.

Phyto-oestrogens and colorectal cancer risk: a systematic review and dose-response meta-analysis of observational studies

Epidemiological studies suggest that soya consumption as a source of phyto-oestrogens and isoflavones may be associated with a reduced risk of colorectal cancer. However, findings have not yet been synthesised for all groups of phyto-oestrogens. A meta-analysis was conducted to quantify the association between phyto-oestrogens and colorectal cancer risk. Relevant observational studies published up to June 2016 were identified by searching MEDLINE, EMBASE and Cochrane Library databases. Study-specific relative risks (RR) were pooled in both categorical and dose-response meta-analyses. Out of seventeen identified studies, sixteen were included in the meta-analysis. Comparing the highest with the lowest intake category, inverse associations for phyto-oestrogens overall and by subgroup were observed but were statistically significant in case-controls studies and not in cohort studies. The pooled RR in case-control studies were 0·76 (95 % CI 0·69, 0·84), 0·77 (95 % CI 0·69, 0·85) and 0·70 (95 % CI 0·56, 0·89) for phyto-oestrogens, isoflavones and lignans, respectively, whereas the corresponding pooled RR were 0·95 (95 % CI 0·85, 1·06), 0·94 (95 % CI 0·84, 1·05) and 1·00 (95 % CI 0·64, 1·57) in cohort studies. Dose-response analysis yielded an 8 % reduced risk of colorectal neoplasms for every 20 mg/d increase in isoflavones intake in Asians (pooled RR 0·92; 95 % CI 0·86, 0·97). A non-linear inverse association with colorectal cancer risk was found for lignans intake, but no association for circulating enterolactone concentrations was observed. Thus, study heterogeneity precludes a rigorous conclusion regarding an effect of high exposure to isoflavones on risk of colorectal cancer. Current evidence for an association with lignans exposure is limited. Further prospective studies, particularly evaluating lignans, are warranted to clarify the association between different phyto-oestrogens and colorectal cancer risk.

Chemoprevention of Colonic Aberrant Crypt Foci by Novel Schiff Based Dichlorido(4-Methoxy-2-{[2-(Piperazin-4-Ium-1-Yl)Ethyl]Iminomethyl}Phenolate)Cd Complex in Azoxymethane-Induced Colorectal Cancer in Rats

Schiff-based complexes as a source of cancer chemotherapeutic compounds have been subjected to the variety of anticancer studies. The in-vitro analysis confirmed the CdCl2(C14H21N3O2) complex possess cytotoxicity and apoptosis induction properties in colon cancer cells, so lead to investigate the inhibitory efficiency of the compound on colonic aberrant crypt foci (ACF). Five groups of adult male rats were used in this study: Vehicle, cancer control, positive control groups and the groups treated with 25 and 50 mg/kg of complex for 10 weeks. The rats in vehicle group were injected subcutaneously with 15 mg/kg of sterile normal saline once a week for 2 weeks and orally administered with 5% Tween-20 (5 ml/kg) for 10 weeks, other groups were injected subcutaneously with 15 mg/kg azoxymethane once a week for 2 weeks. The rats in positive groups were injected intra-peritoneally with 35 mg/kg 5-Flourouracil four times in a month. Administration of the complex suppressed total colonic ACF formation up to 73.4% (P < 0.05). The results also showed that treatment with the complex significantly reduced the level of malondialdehyde while increasing superoxide dismutase and catalase activities. Furthermore, the down-regulation of PCNA and Bcl2 and the up-regulation of Bax was confirmed by immunohistochemical staining.

Chemoprevention in gastrointestinal physiology and disease. Anti-inflammatory approaches for colorectal cancer chemoprevention

Colorectal cancer (CRC) is one of the most common human malignancies and a leading cause of cancer-related deaths in developed countries. Identifying effective preventive strategies aimed at inhibiting the development and progression of CRC is critical for reducing the incidence and mortality of this malignancy. The prevention of carcinogenesis by anti-inflammatory agents including nonsteroidal anti-inflammatory drugs (NSAIDs), selective cyclooxygenase-2 (COX-2) inhibitors, and natural products is an area of considerable interest and research. Numerous anti-inflammatory agents have been identified as potential CRC chemopreventive agents but vary in their mechanism of action. This review will discuss the molecular mechanisms being studied for the CRC chemopreventive activity of NSAIDs (i.e., aspirin, sulindac, and ibuprofen), COX-2 inhibitors (i.e., celecoxib), natural products (i.e., curcumin, resveratrol, EGCG, genistein, and baicalein), and metformin. A deeper understanding of how these anti-inflammatory agents inhibit CRC will provide insight into the development of potentially safer and more effective chemopreventive drugs.

Soy Saponins Meditate the Progression of Colon Cancer in Rats by Inhibiting the Activity of β -Glucuronidase and the Number of Aberrant Crypt Foci but Not Cyclooxygenase-2 Activity

Objective. The effect of extracted crude soybean saponins on preneoplastic lesions, aberrant crypt foci (ACF), and the related mechanism were investigated. Research Methods and Procedures. Rats were assigned into five groups according to different doses of extracted crude soybean saponins and received 1,2-dimethylhydrazine (DMH) injection in week 5. In week 15, all rats were sacrificed. The number of ACFs, the cyclooxygenase-2 (COX-2) protein expression, the level of prostaglandins E2 (PGE2), and the activity of β-glucuronidase were examined. Results. Results revealed that the consumption of extracted crude soybean saponins decreased the number of ACFs and the activity of β-glucuronidase in rats, while the expression of COX-2 protein and PGE2 level were not affected. Conclusions. Soybean saponins were effective in inhibiting colon cancer by downregulating the activity of β-glucuronidase in colonic mucosa but not the COX-2 protein expression and PGE2 level.

DNA methylation and histone modifications of Wnt genes by genistein during colon cancer development

This study aims to elucidate the epigenetic mechanisms by which genistein (GEN) maintains a normal level of WNT genes during colon cancer development. We have reported that soy protein isolate (SPI) and GEN repressed WNT signaling, correlating with the reduction of pre-neoplastic lesions in rat colon. We hypothesized that SPI and GEN induced epigenetic modifications on Sfrp2, Sfrp5 and Wnt5a genes, suppressing their gene expression induced by azoxymethane (AOM), a chemical carcinogen, to the similar level as that of pre-AOM period. We identified that in the post-AOM period, histone H3 acetylation (H3Ac) was downregulated by SPI and GEN at the promoter region of Sfrp2, Sfrp5 and Wnt5a, which paralleled with the reduced binding of RNA polymerase II. Nuclear level of histone deacetylase 3 was enhanced by SPI and GEN. The diets suppressed the trimethylation of histone H3 Lysine 9 (H3K9Me3) and the phosphorylation of histone H3 Serine 10 (H3S10P). Methylation of the specific region of Sfrp2, Sfrp5 and Wnt5a genes was increased by SPI and GEN, which was inversely correlated with the reduction of gene expression. Bisulfite sequencing further confirmed that dietary GEN induced DNA methylation at CpG island of the promoter region of Sfrp5. Importantly, this region includes a fragment that had decreased H3Ac. Here, we present a potential epigenetic mechanism by which dietary GEN controls the responses of WNT genes during carcinogen induction, which involves DNA methylation, histone modifications and their interactions at the regulatory region of gene.

Estrogen inhibits colon polyp formation by reducing angiogenesis in a carcinogen-induced rat model

Objective. To study the effects of estrogen on colon polyp formation, proliferation, and angiogenesis on a rat model of colon cancer induced by dimethylhydrazine (DMH). Methods. Thirty-six female ovariectomized (OVX) rats were randomly divided into 3 groups: (I) control group (administrated with vehicles weekly), (II) DMH group (administrated with DMH weekly), and (III) DMH + E2 group (administrated with DMH and 17β-estradiol weekly). The incidence, volumes, and multiplicity of colon polyps in each group were evaluated. The microvessel density (MVD), the expressions of Proliferating Cell Nuclear Antigen (PCNA), and the expressions of HIF-1 α and VEGF in polyps were detected in each group. Results. Estrogen reduced the multiplicity, volumes, and the PCNA expressions of DMH-induced colon polyps. The MVD in DMH + E2 group was significantly lower than that in DMH group. Estrogen treatment decreased the HIF-1 α and VEGF expressions at both mRNA and protein level. Conclusion. Estrogen replacement was protective for ovariectomized rats from DMH-induced carcinogenesis, and one of the mechanisms for this was due to estrogen's inhibitive effects on blood vessel formation by downregulating VEGF and HIF-1 α expressions.

Genistein, a soya isoflavone, prevents azoxymethane-induced up-regulation of WNT/β-catenin signalling and reduces colon pre-neoplasia in rats

The present study aimed to explore the role(s) of the soya isoflavone genistein (GEN) in preventing the development of colon pre-neoplasia, using Wingless/int (WNT)/β-catenin as a molecular marker of colon abnormality. Specifically, the effects on the WNT/β-catenin signalling pathway from GEN were examined by using an azoxymethane (AOM)-induced rat colon cancer model. Male Sprague-Dawley rats were fed a control (CTL), a soya protein isolate (SPI) or a GEN diet from gestation to 13 weeks of age. The first sampling was conducted at 7 weeks of age for pre-AOM analysis. The remaining rats were injected with AOM at 7 weeks of age. The descending colon was collected 6 weeks later for the evaluation of aberrant crypt foci (ACF), gene expression and nuclear protein accumulation. AOM injection induced aberrant nuclear accumulation of β-catenin in the CTL group but not in the SPI or GEN group. Moreover, the WNT target genes Cyclin D1 and c-Myc were repressed by SPI and GEN. Meanwhile, SPI and GEN suppressed the expression of WNT signalling genes including Wnt5a, Sfrp1, Sfrp2 and Sfrp5 to the similar level to that of the pre-AOM period. Rats fed SPI and GEN had a decreased number of total aberrant crypts. GEN feeding also resulted in a reduced number of ACF with N = 3 per foci. The reduction of WNT/β-catenin signalling was correlated with the decrease in total aberrant crypts. By testing WNT/β-catenin signalling as a biomarker of colon carcinogenic potential, we showed the novel role of GEN as a suppressor of carcinogen-induced WNT/β-catenin signalling in preventing the development of early colon neoplasia.

A comparative study of phytochemical composition of genetically and non-genetically modified soybean (Glycine max L.) and evaluation of antitumor activity

Colon cancer is one of the major causes of cancer mortality worldwide. The analysed feeds, containing non-genetically modified (GM) soybean and Roundup Ready soybean, showed a different polyphenolic content and lipophilic composition. Non-GM soybean extract possessed twice the polyphenolic content of GM soybean and the highest number of sterols. Among them, γ-sitosterol was found to be the major constituent. Methanolic extract of non-GM soybean extract was more potent than GM soybean extract against colon carcinoma cell line LoVo using MTT assay, while the second one showed a slightly higher anti-inflammatory activity. The findings add to epidemiological evidence for the therapeutic effects of soy foods in colorectal carcinoma.

Sorghum phenolics demonstrate estrogenic action and induce apoptosis in nonmalignant colonocytes

Evidence indicates sorghum may be protective against colon cancer; however, the mechanisms are unknown. Estrogen is believed to protect against colon cancer development by inducing apoptosis in damaged nonmalignant colonocytes. Three sorghum extracts (white, red, and black) were screened for estrogenic activity using cell models expressing estrogen receptor α (ER-α; MCF-7 breast cancer cells) and β [ER-β; nonmalignant young adult mouse colonocytes (YAMC)]. Black and white sorghum extracts had significant estrogenic activity mediated through both estrogen receptors at 1-5 and 5-10 μg/mL, respectively; but red sorghum did not. Activation of ER-β in YAMC reduced cell growth via induction of apoptosis. Only the black and red sorghums contained 3-deoxyanthocyanins; however, these compounds were non-estrogenic. Flavones with estrogenic properties, luteolin (0.41-2.12 mg/g) and apigenin (1.1-1.4 mg/g), and their O-methyl derivatives (0.70-0.95 mg/g) were detected in white and black sorghums, but not in the red sorghum. On the other hand, naringenin, a flavanone known to interfere with transcriptional activities of estrogen, was only detected in the red sorghum extract (as its 7-O-glycoside) at relatively high concentration (11.8 mg/g). Sorghum flavonoid composition has important implications on possible modes of chemoprotection by sorghum against colon carcinogenesis.

Phytochemicals and colorectal cancer prevention--myth or reality?

Chemoprevention of colorectal cancer has been the focus of intensive research for more than two decades. Epidemiological evidence has shown a small, but significant association between fruit and vegetable intake and a reduction in colorectal cancer risk. In vitro and animal data have also demonstrated that many dietary phytochemicals have potent chemopreventive activities. However, in humans, single-agent compounds have yielded conflicting results. A key concept is that dietary phytochemicals exert beneficial effects at low concentrations when working in synergy with each other. As the gut microflora evolved in an environment rich in dietary fiber and phytochemicals, the rapid shift towards a Western diet creates an environment in which the gut is more vulnerable to carcinogens, genetic alterations and inflammation. As enforcing dietary interventions on large populations is not realistic, we believe future chemopreventive work should focus on delivering phytochemical mixtures that target the multiple molecular events involved in colorectal carcinogenesis.

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.

Genistein attenuates WNT signaling by up-regulating sFRP2 in a human colon cancer cell line

Colorectal cancer (CRC) is a leading fatal carcinoma worldwide. Our goal was to investigate the effects of genistein on WNT signaling, which is involved in colon epithelial cell growth and apoptosis. Human colon cancer cell line DLD-1 was treated for four days with 75 μmol/L genistein. Decreased nuclear β-catenin and increased phospho- β-catenin accumulation was detected, showing a change in WNT signaling. Reverse transcriptase-polymerase chain reaction analysis showed increased sFRP2 (a WNT pathway antagonist) mRNA expression following the genistein treatment. Methylation selective polymerase chain reaction showed decreased methylation in two CpG islands of the sFRP2 gene following genistein treatment, similar to the effect of 5-aza-cytidine, a demethylation agent. We observed reduced DLD-1 cell viability and increased apoptosis with genistein treatment. Genistein inhibits β-catenin-mediated WNT signaling through increasing sFRP2 gene expression by demethylating its silenced promoter in colon cancer cell line DLD-1.

Inflammation-related signaling pathways implicating TGFβ are revealed in the expression profiling of MCF7 cell treated with fermented soybean, chungkookjang

Chungkookjang is a Korean fermented soybean containing microorganisms, proteinase, and diverse bioactive compounds, including a high concentration of isoflavones and peptides. Growth of breast cancer MCF7 cells decreased dependent on the concentration of fermented soybean extracts. The effect of fermented soybean on cellular gene expression was determined in a systematic manner comprehensively. DNA microarray analysis was performed using 25,804 probes. Ninety one genes whose expression levels were significantly changed were selected. TGFβI and Smad3 were upregulated. Downregulation of inflammation-related CSF2, CSF2RA, and CSF3 was found. Differential expression of chemokines CCL2, CCL3, CCL3L3, CXCL1, and CXCL2 were observed. Network analysis identified ERβ in the network. Based on the experimental results, taking fermented soybean might be helpful for preventing breast cancer by a mechanism activating TGFβ pathway and depressing inflammation.

Estrogen receptors in colorectal cancer: goalkeepers, strikers, or bystanders?

This perspective on Jin et al. (beginning on page 910 in this issue of the journal) discusses the importance of estrogen signaling in colorectal carcinogenesis, with a focus on estrogen receptor beta (ERbeta), which is the predominant ER in the colorectal epithelium. The importance of ERbeta in breast cancer is well described in the literature, and recent studies reveal that ERbeta functions similarly in colorectal cancer. The implications of this pathway include new possibilities to treat or prevent colorectal cancer with targeted endocrine drugs and the potential of ERbeta as a novel diagnostic tool.

Suppression of colonic aberrant crypt foci by soy isoflavones is dose-independent in dimethylhydrazine-treated rats

The potential of soy isoflavones (SIs) to reduce colon cancer has been investigated in animal models. These studies have found that outcomes are variable and depend on SI dose. The present study investigated dose-response effects of SIs on colon carcinogenesis in a chemically induced rat cancer model. Sprague-Dawley male rats were injected with 1,2-dimethylhydrazine (DMH) and were provided experimental diets that contained 0, 10, 50, 150, or 500 mg of SI aglycones/kg of diet for 12 weeks. Plasma concentrations of genistein, daidzein, and equol were determined using time-resolved fluoroimmunoassay. Plasma concentrations of these SIs tended to increase in a dose-dependent manner in DMH-treated rats. The numbers of aberrant crypt foci (ACF) and the expression of cyclooxygenase-2 (COX-2) proteins of colons were significantly decreased in the SI-fed groups compared with the control group; however, suppression was not dose-dependent. Furthermore, there were no significant correlations between plasma SI concentrations and ACF or COX-2 expression. Increased SI intake and increased plasma levels of SIs and metabolites were not associated with tissue levels of lipid peroxidation. We conclude that dietary supplementation of SIs suppresses DMH-induced ACF formation and COX-2 expression in a dose-independent manner.

Soy consumption and colorectal cancer risk in humans: a meta-analysis

The purpose of the present study was to determine the relationship between soy consumption and colorectal cancer risk in humans by conducting a meta-analysis of available epidemiologic studies. We systematically reviewed publications obtained through a Medline literature search and identified four cohort and seven case-control studies on soy and colorectal cancer risk that met the inclusion criteria. We extracted the risk estimate (hazard ratio, relative risk, or odds ratio) of the highest and the lowest reported categories of intake from each study and conducted this analysis using a random-effects model. Our analysis did not find that soy consumption was associated with colorectal cancer risk [combined risk estimate, 0.90; 95% confidence interval (95% CI), 0.79-1.03] nor did the separate analyses on colon cancer (combined risk estimate, 0.88; 95% CI, 0.74-1.06) and rectal cancer (combined risk estimate, 0.88; 95% CI, 0.67-1.14). However, when separately analyzed on the basis of gender, we found that soy was associated with an approximately 21% reduction in colorectal cancer risk in women (combined risk estimate, 0.79; 95% CI, 0.65-0.97; P = 0.026), but not in men (combined risk estimate, 1.10; 95% CI, 0.90-1.33). Thus, consumption of soy foods may be associated with a reduction in colorectal cancer risk in women, but not in men.

Dietary-induced ERbeta upregulation counteracts intestinal neoplasia development in intact male ApcMin/+ mice

Most sporadic colorectal cancers (CRCs) develop through the adenoma-carcinoma sequence pathway and are initiated by adenomatous polyposis coli (APC) gene mutations. Estrogen receptor beta (ERbeta) is recognized to progressively reduce its expression in adenomatous and carcinomatous tissues in humans. Moreover, ERbeta deficiency enhances small intestinal tumorigenesis in rodents. In the Apc(Min/+) mouse model, we evaluated intestinal polyp development and ERbeta expression plus other biological parameters influencing tumor growth (epithelial cell proliferation, apoptosis and migration) following the addition of a combination of the ERbeta-selective agonist silymarin (SIL) and/or lignin (LIG) to a high-fat/low-fiber diet. Forty-five Apc(Min/+) mice were divided in four groups: animals fed on the tumorigenic high-fat/low-fiber diet, the tumorigenic diet supplemented with SIL (0.02%) or purified LIG (6.24%) or SIL (0.005%) + LIG (6.24%). In these animals, we assessed polyp number and volume and their degree of dysplasia together with ERbeta messenger RNA (mRNA) and protein levels and epithelial cell proliferation, migration and apoptosis. The latter group of parameters was evaluated in normal and adenomatous mucosa and the results compared with those found in wild-type (WT) mice fed on the control diet. The addition of SIL or LIG to the diet and even more the specific combination of the two significantly counteracted intestinal tumorigenesis and increased ERbeta mRNA and protein levels. Cell proliferation and apoptosis were rebalanced and cell migration accelerated, restoring values similar to those observed in WT animals. Our results further support a protective effect of ERbeta in CRC suggesting the use of the combination of SIL-LIG as a potential approach against CRC development.

Isoflavonoids - an overview of their biological activities and potential health benefits

There are many biological activities attributed to isoflavonoids. The majority of them could be beneficial and some of them may be detrimental, depending on specific circumstances. Isoflavonoids play an important role in human nutrition as health promoting natural chemicals. They belong to plant secondary metabolites that mediate diverse biological functions through numerous pathways. They are structurally similar to estrogens, exerting both estrogenic and antiestrogenic properties in various tissues. The results of epidemiologic studies exploring the role of isoflavonoids in human health have been inconclusive. Some studies support the notion of a protective effect of their consumption in immunomodulation, cognition, risk reduction of certain cancers, cardiovascular and skin diseases, osteoporosis and obesity, as well as relief of menopausal symptoms. Other studies failed to demonstrate any effects.

Regulation of estrogen receptor beta activity and implications in health and disease

Together with the estrogen receptor (ER) alpha, estrogen receptor beta (ER beta ) mediates many of the physiological effects of estrogens. As ER beta is crucially involved in a variety of important physiological processes, its activity should be tightly regulated. ER beta regulation is achieved by hormone binding as well as by posttranslational modifications of the receptor. Furthermore, ER beta expression levels are under circadian control and can be regulated by DNA methylation of the ER beta promoter region. There are also a number of factors that can interfere with ER beta activity, such as phytoestrogens, endocrine disruptive chemicals, and growth factors. In this article, we outline different mechanisms of ER beta regulation and how they are implicated in various diseases. We also discuss how these insights might help to specifically target ER beta in drug design.