Fetal programming of colon cancer in adult rats: correlations with altered neonatal growth trajectory, circulating IGF-I and IGF binding proteins, and testosterone

Maternal Consumption of a Low-Isoflavone Soy Protein Isolate Diet Accelerates Chemically Induced Hepatic Carcinogenesis in Male Rat Offspring

It has been reported that maternal nutrition determines the offspring's susceptibility to chronic diseases including cancer. Here, we investigated the effects of maternal diets differing in protein source on diethylnitrosamine (DEN)-induced hepatocarcinogenesis in adult rat offspring. Dams were fed a casein (CAS) diet or a low-isoflavone soy protein isolate (SPI) diet for two weeks before mating and throughout pregnancy and lactation. Offspring were weaned to and fed a chow diet throughout the study. From four weeks of age, hepatocellular carcinomas (HCC) were induced by intraperitoneal injection of DEN once a week for 14 weeks. The SPI/DEN group exhibited higher mortality rate, tumor multiplicity, and HCC incidence compared with the CAS/DEN group. Accordingly, altered cholesterol metabolism and increases in liver damage and angiogenesis were observed in the SPI/DEN group. The SPI/DEN group had a significant induction of the nuclear factor-κB-mediated anti-apoptotic pathway, as measured by increased phosphorylation of IκB kinase β, which may lead to the survival of precancerous hepatocytes. In conclusion, maternal consumption of a low-isoflavone soy protein isolate diet accelerated chemically induced hepatocarcinogenesis in male rat offspring in the present study, suggesting that maternal dietary protein source may be involved in DEN-induced hepatocarcinogenesis in adult offspring.

Early Life and Postnatal Western Diet Feeding and Susceptibility to Chemically Induced Colonic Aberrant Crypt Foci in Male Rats Offspring

The modifying effects of a Western diet (WD) during early life on the susceptibility to colon carcinogenesis induced by dimethylhydrazine (DMH) were examined in male rats as later adults. Three groups were studied: a lifetime control diet-fed group, a test group fed WD since pregnancy from dams until postnatal day (PND) 42, and a group fed WD at adulthood. At PND 70, all groups received the carcinogen DMH and were euthanized 10 wk later. Colonic aberrant crypt foci (ACF) were scored (number and crypt multiplicity) and the altered pattern of β-catenin expression was evaluated in the colonic lesions. ACF multiplicity (≥4 crypts) was significantly higher in the group fed WD at early life than in the group fed the control diet. ACF number, crypt multiplicity, and the number of high-grade dysplastic lesions were significantly higher in the group fed WD at adulthood than in the groupfed the control diet. The number of lesions with altered β-catenin expression was higher in the groups receiving WD at early life or at adulthood than in the lifetime control-diet-fed group. These findings indicate that WD exposure at early life increased the susceptibility to colon carcinogenesis at adulthood.

Dietary phenolics against colorectal cancer--From promising preclinical results to poor translation into clinical trials: Pitfalls and future needs

Colorectal cancer (CRC) remains a major cause of cancer death worldwide. Over 70% of CRC cases are sporadic and related to lifestyle. Epidemiological studies inversely correlate CRC incidence with the intake of fruits and vegetables but not with their phenolic content. Preclinical studies using in vitro (cell lines) and animal models of CRC have reported anticancer effects for dietary phenolics through the regulation of different markers and signaling pathways. Herein, we review and contrast the evidence between preclinical studies and clinical trials (patients with CRC or at risk, familial adenopolyposis or aberrant crypt foci) investigating the protective effects of curcumin, resveratrol, isoflavones, green tea extracts (epigallocatechin gallate), black raspberry powder (anthocyanins and ellagitannins), bilberry extract (anthocyanins), ginger extracts (gingerol derivatives), and pomegranate extracts (ellagitannins and ellagic acid). To date, curcumin is the most promising polyphenol as possible future adjuvant in CRC management. Overall, the clinical evidence of dietary phenolics against CRC is still weak and the amounts needed to exert some effects largely exceed common dietary doses. We discuss here the possible reasons behind the gap between preclinical and clinical research (inconsistence of results, lack of clinical endpoints, etc.), and provide an outlook and a roadmap to approach this topic.

The intrauterine and nursing period is a window of susceptibility for development of obesity and intestinal tumorigenesis by a high fat diet in Min/+ mice as adults

We studied how obesogenic conditions during various life periods affected obesity and intestinal tumorigenesis in adult C57BL/6J-Min (multiple intestinal neoplasia)/+ mice. The mice were given a 10% fat diet throughout life (negative control) or a 45% fat diet in utero, during nursing, during both in utero and nursing, during adult life, or during their whole life-span, and terminated at 11 weeks for tumorigenesis (Min/+) or 23 weeks for obesogenic effect (wild-type). Body weight at 11 weeks was increased after a 45% fat diet during nursing, during both in utero and nursing, and throughout life, but had normalized at 23 weeks. In the glucose tolerance test, the early exposure to a 45% fat diet in utero, during nursing, or during both in utero and nursing, did not affect blood glucose, whereas a 45% fat diet given to adults or throughout life did. However, a 45% fat diet during nursing or during in utero and nursing increased the number of small intestinal tumors. So did exposures to a 45% fat diet in adult life or throughout life, but without increasing the tumor numbers further. The intrauterine and nursing period is a window of susceptibility for dietary fat-induced obesity and intestinal tumor development.

Cytosolic malic enzyme 1 (ME1) mediates high fat diet-induced adiposity, endocrine profile, and gastrointestinal tract proliferation-associated biomarkers in male mice

BACKGROUND

Obesity and associated hormonal disturbances are risk factors for colon cancer. Cytosolic Malic Enzyme (ME1) generates NADPH used for lipogenesis in gastrointestinal (GI), liver and adipose tissues. We have reported that inclusion of soy protein isolate (SPI) in the diet lowered body fat content and colon tumor incidence of rats fed AIN-93G diet, while others have demonstrated SPI inhibition of rat hepatic ME1 expression. The present study examined the individual and combined effects of dietary SPI and absence of ME1 on: 1) serum concentrations of hormones implicated in colon cancer development, 2) expression of lipogenic and proliferation-associated genes in the mouse colon and small intestine, and 3) liver and adipose expression of lipogenic and adipocytokine genes that may contribute to colon cancer predisposition.

METHODS

Weanling wild type (WT) and ME1 null (MOD-1) male mice were fed high-fat (HF), iso-caloric diets containing either casein (CAS) or SPI as sole protein source for 5 wks. Somatic growth, serum hormone and glucose levels, liver and adipose tissue weights, GI tissue parameters, and gene expression were evaluated.

RESULTS

The MOD-1 genotype and SPI-HF diet resulted in decreases in: body and retroperitoneal fat weights, serum insulin, serum leptin, leptin/adiponectin ratio, adipocyte size, colon mTOR and cyclin D1 mRNA abundance, and jejunum FASN mRNA abundance, when compared to WT mice fed CAS-HF. Regardless of diet, MOD-1 mice had reductions in liver weight, liver steatosis, and colon crypt depth, and increases in adipose tissue expression of IRS1 and IRS2, compared to WT mice. SPI-HF diet reduced ME1 gene expression only in retroperitoneal fat.

CONCLUSIONS

Data suggest that the pharmacological targeting of ME1 or the inclusion of soy protein in the diet may provide avenues to reduce obesity and its associated pro-tumorigenic endocrine environment and improve insulin sensitivity, potentially disrupting the obesity-colon cancer connection.

The maternal womb: a novel target for cancer prevention in the era of the obesity pandemic?

The dramatic rise in worldwide prevalence of obesity has necessitated the search for more efficacious antiobesity strategies to counter the increased cancer risks in overweight and obese individuals. The mechanistic pathways linking obesity status with adult chronic diseases such as cancer remain incompletely understood. A growing body of evidence suggests that novel approaches and interventional agents to disrupt the feed-forward cycle of maternal to offspring obesity transfer that is initiated in utero will be important for stemming both the obesity pandemic and the associated increase in cancer incidence. The convergence of multiple research areas including those encompassing the insulin and insulin-like growth factor systems, epigenetics, and stem cell biology is providing insights into the potential for cancer prevention in adult offspring previously exposed to the intrauterine environment of overweight/obese mothers. Here, we review the current state of this nascent research field, with a focus on three major cancers, namely breast, colorectal, and liver, and suggest some possible future directions to optimize its impact for the health of future generations.

Androgen receptor polyglutamine repeat number: models of selection and disease susceptibility

Variation in polyglutamine repeat number in the androgen receptor (AR CAGn) is negatively correlated with the transcription of androgen-responsive genes and is associated with susceptibility to an extensive list of human disease. Only a small portion of the heritability for many of these diseases is explained by conventional SNP-based genome-wide association studies, and the forces shaping AR CAGn among humans remains largely unexplored. Here, we propose evolutionary models for understanding selection at the AR CAG locus, namely balancing selection, sexual conflict, accumulation-selection, and antagonistic pleiotropy. We evaluate these models by examining AR CAGn-linked susceptibility to eight extensively studied diseases representing the diverse physiological roles of androgens, and consider the costs of these diseases by their frequency and fitness effects. Five diseases could contribute to the distribution of AR CAGn observed among contemporary human populations. With support for disease susceptibilities associated with long and short AR CAGn, balancing selection provides a useful model for studying selection at this locus. Gender-specific differences AR CAGn health effects also support this locus as a candidate for sexual conflict over repeat number. Accompanied by the accumulation of AR CAGn in humans, these models help explain the distribution of repeat number in contemporary human populations.

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.

Early life environment and developmental immunotoxicity in inflammatory dysfunction and disease

Components of the innate immune system such as macrophages and dendritic cells are instrumental in determining the fate of immune responses and are, also, among the most sensitive targets of early life environmental alterations including developmental immunotoxicity (DIT). DIT can impede innate immune cell maturation, disrupt tissue microenvironment, alter immune responses to infectious challenges, and disrupt regulatory responses. Dysregulation of inflammation, such as that observed with DIT, has been linked with an increased risk of chronic inflammatory diseases in both children and adults. In this review, we discuss the relationship between early-life risk factors for innate immune modulation and promotion of dysregulated inflammation associated with chronic inflammatory disease. The health risks from DIT-associated inflammation may extend beyond primary immune dysfunction to include an elevated risk of several later-life, inflammatory-mediated diseases that target a wide range of physiological systems and organs. For this reason, determination of innate immune status should be an integral part of drug and chemical safety evaluation.

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.

Soy protein diet alters expression of hepatic genes regulating fatty acid and thyroid hormone metabolism in the male rat

We hypothesized that consumption of soy protein isolate (SPI) or the soy isoflavone genistein (GEN) would modulate mRNA expression of genes underlying lipid and thyroid hormone metabolism in livers and small intestines of young adult male Sprague-Dawley rats. Early pregnant rat dams were placed on AIN-93G diets containing casein (CAS, control protein), SPI, or CAS+GEN. Litters were weaned to the same diet as their dam. SPI-fed (but not GEN-fed) male rats of 48 days of age had significant reductions in body weight, abdominal fat pad weight and hepatic content of lipid droplets and triglycerides. Hepatic peroxisome proliferator-activated receptor α (Ppara) transcripts were elevated with SPI but not GEN diet. Hepatic pyruvate dehydrogenase kinase-4 (Pdk4) and cytochrome P450 4A10 (Cyp4a10) mRNA abundance was reduced with SPI; the SPI effect on Cyp4a10 was recapitulated by GEN diet. SPI (but not GEN) suppressed Pdk4 and 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) mRNA abundance in duodenum. Liver iodothyronine deiodinase types 1 and 2 (Dio1 and Dio2) mRNA levels were increased with SPI diet; the effect on Dio2, but not Dio1 mRNAs, also was observed with GEN. SPI and GEN increased hepatic types 1 and 2 iodothyronine deiodinase (D1 and D2) activities. Effects of SPI and GEN on the above gene expression may contribute to the observed reductions in body and adipose tissue weight and liver lipid content in this model. Identification of the regulation, by genistein and soy protein, of iodothyronine deiodinase synthesis has potential applications for treatment and prevention of fatty liver disease and obesity.

Lack of efficacy of blueberry in nutritional prevention of azoxymethane-initiated cancers of rat small intestine and colon

Background

Blueberries may lower relative risk for cancers of the gastrointestinal tract. Previous work indicated an inhibitory effect of consumed blueberry (BB) on formation of aberrant crypt foci (ACF) in colons of male Fisher F344 rats (inbred strain). However, effects of BB on colon tumors and in both genders are unknown.

Methods

We examined efficacy of BB in inhibition of azoxymethane (AOM)-induced colon ACF and intestine tumors in male and female Sprague-Dawley rats (outbred strain). Pregnant rats were fed a diet with or without 10% BB powder; progeny were weaned to the same diet as their dam and received AOM as young adults.

Results

Male and female rats on control diet had similar numbers of ACF at 6 weeks after AOM administration. BB increased (P < 0.05) ACF numbers within the distal colon of female but not male rats. There was a significant (P < 0.05) diet by gender interaction with respect to total colon ACF number. Colon and duodenum tumor incidences were less in females than males at 17 weeks after AOM. BB tended (0.1 > P > 0.05) to reduce overall gastrointestinal tract tumor incidence in males, however, tumor incidence in females was unaffected (P > 0.1) by BB. There was a tendency (0.1 > P > 0.05) for fewer adenocarcinomas (relative to total of adenomatous polyps plus adenocarcinomas) in colons of female than male tumor-bearing rats; in small intestine, this gender difference was significant (P < 0.05). BB favored (P < 0.05) fewer adenocarcinomas and more adenomatous polyps (as a proportion of total tumor number) in female rat small intestine.

Conclusion

Results did not indicate robust cancer-preventive effects of BB. Blueberry influenced ACF occurrence in distal colon and tumor progression in duodenum, in gender-specific fashion. Data indicate the potential for slowing tumor progression (adenomatous polyp to adenocarcinoma) by BB.

Early soy exposure via maternal diet regulates rat mammary epithelial differentiation by paracrine signaling from stromal adipocytes

Diet-mediated changes in transcriptional programs that promote the early differentiation of the mammary gland may lead to reduced breast cancer risk. The disparity in adult breast cancer incidence between Asian women and Western counterparts is attributed partly to high soy food intake. Here, we conducted genome-wide profiling of mammary tissues of weanling rats exposed to soy protein isolate (SPI) or control casein (CAS) via maternal diet to evaluate the contribution of early exposure on mammary gene expression. Of the identified 18 up- and 39 downregulated genes with SPI relative to CAS, a subset was associated with lipid metabolic pathways, consistent with reduced mammary adipocyte size and suggesting stromal adipocyte-specific genomic changes. Female offspring of rats fed SPI tended to have fewer terminal end buds (P = 0.06) and had significantly lower body weight and abdominal fat mass. To demonstrate the functional consequence of SPI-mediated adipocyte metabolic changes on neighboring mammary epithelium, the expression of in vivo regulated genes in 3T3-L1 adipocytes treated with soy isoflavone genistein and effects of the resultant conditioned medium (CM) on the differentiation of HC11 mammary epithelial cells were evaluated by quantitative RT-PCR and/or Western immunoblots. In differentiated 3T3-L1, genistein decreased fatty acid synthase and stearoyl-CoA desaturase and increased hydroxysteroid 11-beta dehydrogenase 1 expression. CM from genistein-treated adipocytes had higher adiponectin levels and augmented prolactin-induced, glucocorticoid-regulated beta-casein levels. These findings suggest that soy-associated components, by targeting mammary adipocytes, alter paracrine signaling to enhance mammary epithelial differentiation, with important implications for the prevention of breast cancer associated with obesity and obesity-related diseases.

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

We studied the effects of lifetime exposure to dietary soy isoflavones in an azoxymethane (AOM)-induced rat colon cancer model. Male pups born to Sprague-Dawley rats exposed (including during pregnancy and lactation) to soy isoflavones at either no (0 mg = control), low (40 mg), or high (1000 mg) doses/kg diet were weaned and continued receiving their respective parental diets until the end of the study. Weaned rats received 2 subcutaneous injections (15 mg/kg body weight) of AOM 1 wk apart. After 26 wk, rats were killed and the coordinates of colon aberrant crypt foci (ACF) and tumors were determined. Expression of estrogen receptor (ER)-beta was assessed in rat colon tumors and in DLD-1 human colon adenocarcinoma cells exposed to soy isoflavones. Compared with the control, soy isoflavones did not affect incidences or multiplicities of colon ACF or tumors. Low-dose soy isoflavones decreased tumor burden and size compared with the control (P < 0.05). Expression of ERbeta increased in colon tumors of soy isoflavone-treated groups compared with the control. Soy isoflavones dose-dependently arrested the growth of DLD-1 cells and at subcytotoxic levels increased the expression of ERbeta. Our results suggest that pre- and postnatal exposure to dietary soy isoflavones suppresses the growth of colon tumors in male rats. The overexpression of ERbeta in both rat colon tumors and DLD-1 cells caused by soy isoflavones suggests that ERbeta is a critical mediator in mitigating its cancer-preventive effects.

Diet and epigenetics in colon cancer

Over the past few years, evidence has accumulated indicating that apart from genetic alterations, epigenetic alterations, through e.g. aberrant promoter methylation, play a major role in the initiation and progression of colorectal cancer (CRC). Even in the hereditary colon cancer syndromes, in which the susceptibility is inherited dominantly, cancer develops only as the result of the progressive accumulation of genetic and epigenetic alterations. Diet can both prevent and induce colon carcinogenesis, for instance, through epigenetic changes, which regulate the homeostasis of the intestinal mucosa. Food-derived compounds are constantly present in the intestine and may shift cellular balance toward harmful outcomes, such as increased susceptibility to mutations. There is strong evidence that a major component of cancer risk may involve epigenetic changes in normal cells that increase the probability of cancer after genetic mutation. The recognition of epigenetic changes as a driving force in colorectal neoplasia would open new areas of research in disease epidemiology, risk assessment, and treatment, especially in mutation carriers who already have an inherited predisposition to cancer.