Bile acids influence the growth, oestrogen receptor and oestrogen-regulated proteins of MCF-7 human breast cancer cells

Association between cholelithiasis, cholecystectomy, and risk of breast and gynecological cancers: Evidence from meta-analysis and Mendelian randomization study

BACKGROUND

Observational studies have shown that cholelithiasis and cholecystectomy are associated with the risk of breast cancer (BC) and gynecological cancers, but whether these relationships are causal has not been established and remains controversial.

METHODS

Our study began with a meta-analysis that synthesized data from prior observational studies to examine the association between cholelithiasis, cholecystectomy, and the risk of BC and gynecological cancers. Subsequently, a two-sample Mendelian randomization (MR) analysis was conducted utilizing genetic variant data to investigate the potential causal relationship between cholelithiasis, cholecystectomy, and the aforementioned cancers.

RESULTS

The results of the meta-analysis demonstrated a significant association between cholecystectomy and the risk of BC (risk ratio [RR] = 1.04, 95% confidence interval [CI]: 1.01-1.06, p = 0.002) and endometrial cancer (EC) (RR = 1.26, 95% CI: 1.02-1.56, p = 0.031). Conversely, no significant association was observed between cholelithiasis and the risk of BC, EC, and ovarian cancer. The MR analysis revealed no discernible causal connection between cholelithiasis and overall BC (p = 0.053), as well as BC subtypes (including estrogen receptor-positive/negative). Similarly, there was no causal effect of cholecystectomy on BC risk (p = 0.399) and its subtypes. Furthermore, no causal associations were identified between cholelithiasis, cholecystectomy, and the risk of gynecological cancers (ovarian, endometrial, and cervical cancer [CC]) (all p > 0.05).

CONCLUSION

This study does not support a causal link between cholelithiasis and cholecystectomy and an increased risk of female cancers such as breast, endometrial, ovarian, and CC.

FXR Agonism with Bile Acid Mimetic Reduces Pre-Clinical Triple-Negative Breast Cancer Burden

Bariatric surgery is associated with improved outcomes for several cancers, including breast cancer (BC), although the mechanisms mediating this protection are unknown. We hypothesized that elevated bile acid pools detected after bariatric surgery may be factors that contribute to improved BC outcomes. Patients with greater expression of the bile acid receptor FXR displayed improved survival in specific aggressive BC subtypes. FXR is a nuclear hormone receptor activated by primary bile acids. Therefore, we posited that activating FXR using an established FDA-approved agonist would induce anticancer effects. Using in vivo and in vitro approaches, we determined the anti-tumor potential of bile acid receptor agonism. Indeed, FXR agonism by the bile acid mimetic known commercially as Ocaliva ("OCA"), or Obeticholic acid (INT-747), significantly reduced BC progression and overall tumor burden in a pre-clinical model. The transcriptomic analysis of tumors in mice subjected to OCA treatment revealed differential gene expression patterns compared to vehicle controls. Notably, there was a significant down-regulation of the oncogenic transcription factor MAX (MYC-associated factor X), which interacts with the oncogene MYC. Gene set enrichment analysis (GSEA) further demonstrated a statistically significant downregulation of the Hallmark MYC-related gene set (MYC Target V1) following OCA treatment. In human and murine BC analyses in vitro, agonism of FXR significantly and dose-dependently inhibited proliferation, migration, and viability. In contrast, the synthetic agonism of another common bile acid receptor, the G protein-coupled bile acid receptor TGR5 (GPBAR1) which is mainly activated by secondary bile acids, failed to significantly alter cancer cell dynamics. In conclusion, agonism of FXR by primary bile acid memetic OCA yields potent anti-tumor effects potentially through inhibition of proliferation and migration and reduced cell viability. These findings suggest that FXR is a tumor suppressor gene with a high potential for use in personalized therapeutic strategies for individuals with BC.

The anticancer activity of bile acids in drug discovery and development

Bile acids (BAs) constitute essential components of cholesterol metabolites that are synthesized in the liver, stored in the gallbladder, and excreted into the intestine through the biliary system. They play a crucial role in nutrient absorption, lipid and glucose regulation, and the maintenance of metabolic homeostasis. In additional, BAs have demonstrated the ability to attenuate disease progression such as diabetes, metabolic disorders, heart disease, and respiratory ailments. Intriguingly, recent research has offered exciting evidence to unveil their potential antitumor properties against various cancer cell types including tamoxifen-resistant breast cancer, oral squamous cell carcinoma, cholangiocarcinoma, gastric cancer, colon cancer, hepatocellular carcinoma, prostate cancer, gallbladder cancer, neuroblastoma, and others. Up to date, multiple laboratories have synthesized novel BA derivatives to develop potential drug candidates. These derivatives have exhibited the capacity to induce cell death in individual cancer cell types and display promising anti-tumor activities. This review extensively elucidates the anticancer activity of natural BAs and synthetic derivatives in cancer cells, their associated signaling pathways, and therapeutic strategies. Understanding of BAs and their derivatives activities and action mechanisms will evidently assist anticancer drug discovery and devise novel treatment.

Examining the Impact of Cholecystectomy on Tumor Recurrence in Breast Cancer Patients

Previous studies have found that bile acids influence the growth of breast cancer cells in vitro, suggesting that naturally occurring bile acids may also influence the growth of human breast cancer cells. Cholecystectomy alters modulation of bile acid metabolites, and therefore postcholecystectomy women could be at an increased risk of cancer development and recurrence. This study examined the breast cancer outcome in women who underwent cholecystectomy as compared to those with intact gallbladder. Ninety-three patients diagnosed with Stage I-III invasive mammary carcinoma in 2014 were retrospectively identified and patient demographics, treatment, and outcomes were collected and statistically analyzed. Results revealed 36% of patients who underwent cholecystectomy had recurrence compared to 25% recurrence in patients with intact gallbladders (p = .30). Forty-six percent of cholecystectomy patients were deceased, and 23% of those with intact gallbladder were deceased (p = .024). The effect of cholecystectomy on bile acid modulation and breast cancer recurrence requires further investigation.

The role of bile acids in carcinogenesis

Bile acids are soluble derivatives of cholesterol produced in the liver that subsequently undergo bacterial transformation yielding a diverse array of metabolites. The bulk of bile acid synthesis takes place in the liver yielding primary bile acids; however, other tissues have also the capacity to generate bile acids (e.g. ovaries). Hepatic bile acids are then transported to bile and are subsequently released into the intestines. In the large intestine, a fraction of primary bile acids is converted to secondary bile acids by gut bacteria. The majority of the intestinal bile acids undergo reuptake and return to the liver. A small fraction of secondary and primary bile acids remains in the circulation and exert receptor-mediated and pure chemical effects (e.g. acidic bile in oesophageal cancer) on cancer cells. In this review, we assess how changes to bile acid biosynthesis, bile acid flux and local bile acid concentration modulate the behavior of different cancers. Here, we present in-depth the involvement of bile acids in oesophageal, gastric, hepatocellular, pancreatic, colorectal, breast, prostate, ovarian cancer. Previous studies often used bile acids in supraphysiological concentration, sometimes in concentrations 1000 times higher than the highest reported tissue or serum concentrations likely eliciting unspecific effects, a practice that we advocate against in this review. Furthermore, we show that, although bile acids were classically considered as pro-carcinogenic agents (e.g. oesophageal cancer), the dogma that switch, as lower concentrations of bile acids that correspond to their serum or tissue reference concentration possess anticancer activity in a subset of cancers. Differences in the response of cancers to bile acids lie in the differential expression of bile acid receptors between cancers (e.g. FXR vs. TGR5). UDCA, a bile acid that is sold as a generic medication against cholestasis or biliary surge, and its conjugates were identified with almost purely anticancer features suggesting a possibility for drug repurposing. Taken together, bile acids were considered as tumor inducers or tumor promoter molecules; nevertheless, in certain cancers, like breast cancer, bile acids in their reference concentrations may act as tumor suppressors suggesting a Janus-faced nature of bile acids in carcinogenesis.

Predicting dynamic response to neoadjuvant chemotherapy in breast cancer: a novel metabolomics approach

Neoadjuvant chemotherapy (NACT) outcomes vary according to breast cancer (BC) subtype. Since pathologic complete response is one of the most important target endpoints of NACT, further investigation of NACT outcomes in BC is crucial. Thus, identifying sensitive and specific predictors of treatment response for each phenotype would enable early detection of chemoresistance and residual disease, decreasing exposures to ineffective therapies and enhancing overall survival rates. We used liquid chromatography−high‐resolution mass spectrometry (LC‐HRMS)‐based untargeted metabolomics to detect molecular changes in plasma of three different BC subtypes following the same NACT regimen, with the aim of searching for potential predictors of response. The metabolomics data set was analyzed by combining univariate and multivariate statistical strategies. By using ANOVA–simultaneous component analysis (ASCA), we were able to determine the prognostic value of potential biomarker candidates of response to NACT in the triple‐negative (TN) subtype. Higher concentrations of docosahexaenoic acid and secondary bile acids were found at basal and presurgery samples, respectively, in the responders group. In addition, the glycohyocholic and glycodeoxycholic acids were able to classify TN patients according to response to treatment and overall survival with an area under the curve model > 0.77. In relation to luminal B (LB) and HER2+ subjects, it should be noted that significant differences were related to time and individual factors. Specifically, tryptophan was identified to be decreased over time in HER2+ patients, whereas LysoPE (22:6) appeared to be increased, but could not be associated with response to NACT. Therefore, the combination of untargeted‐based metabolomics along with longitudinal statistical approaches may represent a very useful tool for the improvement of treatment and in administering a more personalized BC follow‐up in the clinical practice.

A pseudo-targeted metabolomics study based on serum bile acids profiling for the differential diagnosis of benign and malignant breast lesions

INTRODUCTION

Breast cancer (BC) has become the most commonly diagnosed cancer worldwide. It is very critical for the differential diagnosis between BC and benign breast diseases (BBD). The characteristics of serum bile acids (BAs) profiling in patients with BBD and BC was elucidated so that potential biomarkers could be find out for the differential diagnosis of BC and BBD.

METHODS

A pseudo-targeted approach was used to perform BAs metabolomics analysis in serum of 29 patients with BBD and 47 patients with BC by ultra-high performance liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Partial least squares-discriminant analysis (PLS-DA) was used to establish a differential diagnostic model for BC, and the receiver operating characteristic (ROC) curve and logistic regression analysis were used to screen out bile acids as biomarkers for the differential diagnosis of BC and BBD.

RESULTS

The serum BAs profile in BC group was quite different from that in BBD group. Compared with the BBD group, BC group had higher level of chenodeoxycholic acid (CDCA), while they had lower levels of dihydroxy tauro-conjugated BA (Tdi-1) and sulfated dihydroxy glyco-conjugated BA (Gdi-S-1). The sensitivity and specificity of PLS-DA model for patients classification were 100% and 92.3%, respectively. The combined biomarker, CDCA and Tdi-1, had high efficacy for the differential diagnosis (area under the curve was 0.954, 95% CI: 0.880-1.000) of BC. Besides, the performance was superior to traditional biomarkers in the differential diagnosis of BC with or without comorbidities.

CONCLUSION

The profile of serum BAs in women with BC was quite different from that in patients with BBD. Serum BAs profiling analysis could be used as an effective tool for the differential diagnosis of BC and BBD.

Microbiome Assisted Tumor Microenvironment: Emerging Target of Breast Cancer

The microbiome assisted tumor microenvironment (TME) supports the tumors by modulating multiple mechanisms. Recent studies reported that microbiome dysbiosis is the main culprit of immune suppressive phenotypes of TME. Further, it has been documented that immune suppressive stimulate metastatic phenotype in TME via modulating signaling pathways, cell differentiation, and innate immune response. This review aims at providing comprehensive developments in microbiome and breast TME interface. The combination of microbiome and breast cancer, breast TME and microbiome or microbial dysbiosis, microbiome and risk of breast cancer, microbiome and phytochemicals or anticancer drugs were as used keywords to retrieve literature from PubMed, Google scholar, Scopus, Web of Science from 2015 onwards. Based on the literature, we presented the impact of TME assisted microbiome dysbiosis and estrobolome in breast cancer risk, drug resistance, and antitumor immunity. We have discussed the influence of antibiotics on the breast microbiome. we also presented the possible dietary phytochemicals that target microbiome dysbiosis to restore the tumor suppression immune environment in breast TME. We presented the microbiome as a possible marker for breast cancer diagnosis. This study will help in the identification of microbiome as a novel target and diagnostic markers and phytochemicals and microbiome metabolites for breast cancer treatment.

Human Plasma Metabolomics for Biomarker Discovery: Targeting the Molecular Subtypes in Breast Cancer

Simple Summary

Breast cancer is the leading cause of female cancer-related deaths worldwide. New technologies with enhanced sensitivity and specificity for early diagnosis and tailored monitoring are in critical demand. Thus, metabolomics appears to be a growing tool in order to detect molecular differences between distinct groups. In this case, an untargeted analytical approach was used to identify metabolomics differences between molecular subtypes of breast cancer in comparison with healthy matched controls. Footprints for each breast cancer subtype provided diagnostic capacities with an area under the receiver-operating characteristic curve above 0.85, which suggests that our results may represent a major advance towards the improvement of personalized medicine and precise targeted therapies for the various breast cancer phenotypes. To validate these molecular profiling as potential therapeutic strategies for the different breast cancer subtypes, further analysis and larger cohorts would be necessary in the near future.

Abstract

Purpose: The aim of this study is to identify differential metabolomic signatures in plasma samples of distinct subtypes of breast cancer patients that could be used in clinical practice as diagnostic biomarkers for these molecular phenotypes and to provide a more individualized and accurate therapeutic procedure. Methods: Untargeted LC-HRMS metabolomics approach in positive and negative electrospray ionization mode was used to analyze plasma samples from LA, LB, HER2+ and TN breast cancer patients and healthy controls in order to determine specific metabolomic profiles through univariate and multivariate statistical data analysis. Results: We tentatively identified altered metabolites displaying concentration variations among the four breast cancer molecular subtypes. We found a biomarker panel of 5 candidates in LA, 7 in LB, 5 in HER2 and 3 in TN that were able to discriminate each breast cancer subtype with a false discovery range corrected p-value < 0.05 and a fold-change cutoff value > 1.3. The model clinical value was evaluated with the AUROC, providing diagnostic capacities above 0.85. Conclusion: Our study identifies metabolic profiling differences in molecular phenotypes of breast cancer. This may represent a key step towards therapy improvement in personalized medicine and prioritization of tailored therapeutic intervention strategies.

Concentration-dependent effects of sodium cholate and deoxycholate bile salts on breast cancer cells proliferation and survival

Bile acids (BAs) are bioactive molecules that have potential therapeutic interest and their derived salts are used in several pharmaceutical systems. BAs have been associated with tumorigenesis of several tissues including the mammary tissue. Therefore, it is crucial to characterize their effects on cancer cells. The objective of this work was to analyse the molecular and cellular effects of the bile salts sodium cholate and sodium deoxycholate on epithelial breast cancer cell lines. Bile salts (BSs) effects over breast cancer cells viability and proliferation were assessed by MTS and BrdU assays, respectively. Activation of cell signaling mediators was determined by immunobloting. Microscopy was used to analyze cell migration, and cellular and nuclear morphology. Interference of membrane fluidity was studied by generalized polarization and fluorescence anisotropy. BSs preparations were characterized by transmission electron microscopy and dynamic light scattering. Sodium cholate and sodium deoxycholate had dual effects on cell viability, increasing it at the lower concentrations assessed and decreasing it at the highest ones. The increase of cell viability was associated with the promotion of AKT phosphorylation and cyclin D1 expression. High concentrations of bile salts induced apoptosis as well as sustained activation of p38 and AKT. In addition, they affected cell membrane fluidity but not significant effects on cell migration were observed. In conclusion, bile salts have concentration-dependent effects on breast cancer cells, promoting cell proliferation at physiological levels and being cytotoxic at supraphysiological ones. Their effects were associated with the activation of kinases involved in cell signalling.

The nuclear translocation of transketolase inhibits the farnesoid receptor expression by promoting the binding of HDAC3 to FXR promoter in hepatocellular carcinoma cell lines

Transketolase (TKT), which is a metabolic enzyme in the nonoxidative phase of the pentose phosphate pathway (PPP), plays an important role in providing cancer cells with raw materials for macromolecular biosynthesis. The ectopic expression of TKT in hepatocellular carcinoma (HCC) was reported previously. However, the role of TKT in the initiation of liver cancer is still obscure. In our previous study, we found that TKT deficiency protects the liver from DNA damage by increasing levels of ribose 5-phosphate and nucleotides. What’s more interesting is that we found TKT deficiency reduced bile acids and loss of TKT promoted the farnesoid receptor (FXR) expression. We further showed that TKT translocated into the nucleus of HCC cell lines through interacting with the signal transducer and activator of transcription 1 (STAT1), and then the complex inhibited FXR expression by promoting the binding of histone deacetylase 3 (HDAC3) to FXR promoter.

From the Table to the Tumor: The Role of Mediterranean and Western Dietary Patterns in Shifting Microbial-Mediated Signaling to Impact Breast Cancer Risk

Diet is a modifiable component of lifestyle that could influence breast cancer development. The Mediterranean dietary pattern is considered one of the healthiest of all dietary patterns. Adherence to the Mediterranean diet protects against diabetes, cardiovascular disease, and cancer. Reported consumption of a Mediterranean diet pattern was associated with lower breast cancer risk for women with all subtypes of breast cancer, and a Western diet pattern was associated with greater risk. In this review, we contrast the available epidemiological breast cancer data, comparing the impact of consuming a Mediterranean diet to the Western diet. Furthermore, we will review the preclinical data highlighting the anticancer molecular mechanism of Mediterranean diet consumption in both cancer prevention and therapeutic outcomes. Diet composition is a major constituent shaping the gut microbiome. Distinct patterns of gut microbiota composition are associated with the habitual consumption of animal fats, high-fiber diets, and vegetable-based diets. We will review the impact of Mediterranean diet on the gut microbiome and inflammation. Outside of the gut, we recently demonstrated that Mediterranean diet consumption led to distinct microbiota shifts in the mammary gland tissue, suggesting possible anticancer effects by diet on breast-specific microbiome. Taken together, these data support the anti-breast-cancer impact of Mediterranean diet consumption.

Liver- and Microbiome-derived Bile Acids Accumulate in Human Breast Tumors and Inhibit Growth and Improve Patient Survival

PURPOSE

Metabolomics is a discovery tool for novel associations of metabolites with disease. Here, we interrogated the metabolome of human breast tumors to describe metabolites whose accumulation affects tumor biology.

EXPERIMENTAL DESIGN

We applied large-scale metabolomics followed by absolute quantification and machine learning-based feature selection using LASSO to identify metabolites that show a robust association with tumor biology and disease outcome. Key observations were validated with the analysis of an independent dataset and cell culture experiments.

RESULTS

LASSO-based feature selection revealed an association of tumor glycochenodeoxycholate levels with improved breast cancer survival, which was confirmed using a Cox proportional hazards model. Absolute quantification of four bile acids, including glycochenodeoxycholate and microbiome-derived deoxycholate, corroborated the accumulation of bile acids in breast tumors. Levels of glycochenodeoxycholate and other bile acids showed an inverse association with the proliferation score in tumors and the expression of cell-cycle and G₂-M checkpoint genes, which was corroborated with cell culture experiments. Moreover, tumor levels of these bile acids markedly correlated with metabolites in the steroid metabolism pathway and increased expression of key genes in this pathway, suggesting that bile acids may interfere with hormonal pathways in the breast. Finally, a proteome analysis identified the complement and coagulation cascade as being upregulated in glycochenodeoxycholate-high tumors.

CONCLUSIONS

We describe the unexpected accumulation of liver- and microbiome-derived bile acids in breast tumors. Tumors with increased bile acids show decreased proliferation, thus fall into a good prognosis category, and exhibit significant changes in steroid metabolism.

Cervical Cancer, Different Treatments and Importance of Bile Acids as Therapeutic Agents in This Disease

Cervical cancer can be cured, because it has a long preinvasive period. Early diagnosis and treatment of cervical cancer at women are crucial for reducing of rate mortality. Today, there are many methods for detecting premalignant lesions and one of them is a conventional Papanicolaou test. Cervical cancer develops through a series of changes in the epithelium called cervical intraepithelial neoplasia (CIN). The biological and genetic characteristics of the cells at cancer in situ are irreversibly altered and abnormal cells have the potential to metastasize to others anatomical regions. Infection with human Papillomavirus, which is transmitted sexually, is considered the main cause and represent the necessary, but not the only factor for the development of cervical cancer. Types of high risk human Papillomavirus are often associated with invasive cervical cancer. The carcinogenic types of HPV 16 and 18 are responsible for 70% of cervical cancer and about 50% of CIN 3. Primary prevention of cervical cancer is aimed at reducing incidence, control of causes and risk factors. In this scientific work, in addition to explaining the various treatments necessary for the treatment of cervical carcinoma, we were discussed about the anticancer effects of the synthetic derivative of ursodeoxycholic acid, such as HS-1183, and synthetic derivatives of chenodeoxycholic acid such as HS-1199 and HS-1200. Also, the effects of bile acid complexes with metals such as platinum, zinc, nickel, and copper were considered in the effective treatment of cervical cancer. KEY POINTS • Lymphogenic spreading of cervical cancer occurs relatively early in the regional lymph nodes, while this sort of progression of cervical cancer is rarer in the juxtaregional (paraaortic), mediastinal and supraclavicular nodes. Clinically proven supraclavicular metastases are not a rarity. In stages IIb and IIIa with metastases in paraaortal nodes occur a 20% metastases at the neck lymph nodes. Hematogenic metastases are relatively rare and occur in the posterior phase. Distant metastases are detected in the lungs and liver. Preinvasive and microinvasive stages of cervical cancer are without symptoms. With deeper invasion of the strome, certain clinical symptoms such as prolonged menstruation, increased vaginal secretions, vaginal bleeding between the two periods, contact bleeding (after coitus), unilateral pelvic pain with spreading in hip joint (infiltration of the pelvic nerve plexus), dysuric disturbance, anemia, islet of the lower extremities. In order to diagnose the level spreading of primary lesion of cervical cancer most commonly are used the supplemental searches such as cytoscopy, rectoscopy, urography, irigography, lung and bone radiography, scintigraphy of the liver, kidney and bone, lymphography, CT (MR) of abdomen and pelvis, as well as laboratory analysis. Surgical treatment consists of transvaginal hysterectomy, transabdominal removal of the uterus (via laparotomy), bilateral adenectomy (removal of the ovaries and the fallopian tubes), upper and middle third of the vagina and lymphonodectomy of the regional lymph nodes. The most commonly used radiotherapy, intracavitary brachytherapy, manual afterloading technique and remote afterloading techniques. The synthetic derivatives of ursodeoxycholic acid and chenodeoxycholic acid such as HS-1183, HS-1199, and HS-1200 are used to treat cervical cancer. These derivatives of chenodeoxycholic acid and ursodeoxycholic acid are capable of inhibiting cell proliferation and inducing apoptosis in SiHa human cells of cervix. Platinum compounds are used as catalysts in cervical cancer therapy. Clinical use of platinum complexes for which the bile acids bind is based on the desire to achieve the death of tumor cells and the spectrum of drug activity in the treatment of cervical cancer. Bisursodeoxycholate (ethylenediamine) platinum (II) [Pt(UDC)2(en)] is characterized by important cytotoxicity against HeLa cervical carcinoma cells and this effect already being clearly detectable after 24 h.

Consumption of Mediterranean versus Western Diet Leads to Distinct Mammary Gland Microbiome Populations

Recent identification of a mammary gland-specific microbiome led to studies investigating bacteria populations in breast cancer. Malignant breast tumors have lower Lactobacillus abundance compared with benign lesions, implicating Lactobacillus as a negative regulator of breast cancer. Diet is a main determinant of gut microbial diversity. Whether diet affects breast microbiome populations is unknown. In a non-human primate model, we found that consumption of a Western or Mediterranean diet modulated mammary gland microbiota and metabolite profiles. Mediterranean diet consumption led to increased mammary gland Lactobacillus abundance compared with Western diet-fed monkeys. Moreover, mammary glands from Mediterranean diet-fed monkeys had higher levels of bile acid metabolites and increased bacterial-processed bioactive compounds. These data suggest that diet directly influences microbiome populations outside the intestinal tract in distal sites such as the mammary gland. Our study demonstrates that diet affects the mammary gland microbiome, establishing an alternative mechanistic pathway for breast cancer prevention.

Development of cholate conjugated hybrid polymeric micelles for FXR receptor mediated effective site-specific delivery of paclitaxel

The aim of the present study was to explore the tumor targeting potential of a cholic acid (CA) conjugated polymeric micelle system for the effective delivery of paclitaxel (PTX).

Farnesoid X receptor alpha: a molecular link between bile acids and steroid signaling?

Bile acids are cholesterol metabolites that have been extensively studied in recent decades. In addition to having ancestral roles in digestion and fat solubilization, bile acids have recently been described as signaling molecules involved in many physiological functions, such as glucose and energy metabolisms. These signaling pathways involve the activation of the nuclear receptor farnesoid X receptor (FXRα) or of the G protein-coupled receptor TGR5. In this review, we will focus on the emerging role of FXRα, suggesting important functions for the receptor in steroid metabolism. It has been described that FXRα is expressed in the adrenal glands and testes, where it seems to control steroid production. FXRα also participates in steroid catabolism in the liver and interferes with the steroid signaling pathways in target tissues via crosstalk with steroid receptors. In this review, we discuss the potential impacts of bile acid (BA), through its interactions with steroid metabolism, on glucose metabolism, sexual function, and prostate and breast cancers. Although several of the published reports rely on in vitro studies, they highlight the need to understand the interactions that may affect health. This effect is important because BA levels are increased in several pathophysiological conditions related to liver injuries. Additionally, BA receptors are targeted clinically using therapeutics to treat liver diseases, diabetes, and cancers.

Bile acids affect the growth of human cholangiocarcinoma via NF-kB pathway

We observed that free bile acids (CA, DCA, and CDCA) inhibited the growth of cholangiocarcinoma cells by promoting cell apoptosis, while the conjugated bile acids (GCA, GDCA, and GCDCA) stimulated cell growth. Consistently, we found that GDCA stimulated tumor growth and CDCA decreased tumor growth in xenografted mice. Further, the phosphorylated IkB was downregulated by free bile acids, and was upregulated by the conjugated bile acids. IL-6 and COX-2 were decreased by the free bile acids and increased by the conjugated bile acids. Collectively, these results suggest that the bile acids regulate the growth of cholangiocarcinoma by modulating NF-kB pathway.

Huaier aqueous extract suppresses human breast cancer cell proliferation through inhibition of estrogen receptor α signaling

Estrogen receptor α (ERα) has been reported to play a critical role in promoting the growth of breast tumor cells. In the present study, we explored the effect of Huaier extract on estrogen receptor α signaling in breast cancer cell lines. Our data demonstrated that Huaier extract effectively inhibited the proliferation of the MCF-7, T47D and ZR-75-1 human breast cancer cell lines. For the mechanism analysis, we demonstrated that Huaier extract significantly reduced the mRNA and protein levels of ERα in all three ERα-positive cell lines. The downregulation of ERα protein levels was correlated with activation of the proteasomes. We demonstrated that Huaier extract markedly decreased the expression of both ERα and its downstream genes, inhibited the estrogen-stimulated proliferation and reversed the estrogen-induced activation of the nuclear factor κB (NFκB) pathway. Our study provides evidence that Huaier extract is a novel estrogen receptor modulator and is a promising drug for the prevention and treatment of ERα-positive human breast cancers.

In-vitro screening of the antiestrogenic activity of chemicals

BACKGROUND

Many chemicals have the potential to interfere with the endocrine systems of humans and wildlife, leading to adverse health effects. In the tiered testing strategies developed for regulatory hazard assessment, in-vitro screens could serve for prioritisation of compounds and for guiding subsequent testing.

OBJECTIVE

To describe in-vitro assays to detect antiestrogenic activity of chemicals.

METHODS

Antiestrogenicity was considered in this review as any inhibition or reduction of estrogen-induced processes due to interference with the normal functioning of the estrogen receptor pathway. Accordingly, in-vitro screening assays for antiestrogenicity have to consider all the possible mechanisms by which this inhibition may occur. Such assays include binding assays, cell proliferation assays, reporter gene assays, and gene activation/protein production assays.

RESULTS/CONCLUSIONS

While binding assays appear to be of limited value in assessing antiestrogenicity, assays using differentiated cells with metabolic competence and a varied receptor/regulatory factor equipment have the capability to detect various modes of antiestrogenic action.

Oestrogen and the enigmatic male predominance of gastric cancer

Gastric cancer is the second most common cause of cancer death worldwide, and annually it causes over 150,000 deaths in Europe and 700,000 deaths globally. The incidence of gastric cancer shows an enigmatic male dominance with a male-to-female ratio of about 2:1. This sex ratio cannot be entirely attributed to the differences in the prevalence of known risk factors between the sexes. This review focuses on the potential role of oestrogen in explaining the male predominance in gastric cancer. Some data argue in favour of sex hormonal influence. Women with a longer fertility life and those on hormone replacement therapy seem to have a decreased risk of gastric cancer, and men who have been treated with oestrogen for prostate cancer have a decreased risk. Use of tamoxifen in women seems to increase their risk of gastric cancer. Animal studies indicate that oestrogen may offer protection against the development of this cancer as for example ovariectomised mice are at an increased risk, whilst administration of female sex hormones decreases the incidence of gastric cancer. Oestrogen may exert its effect by acting on oestrogen receptors (ERs). Both ERalpha, ERbeta and the latest discovered ERbetacx have been identified in gastric tissue. The biological means behind this is not yet clear but various mechanisms have been suggested. There are indications that oestrogen may lead to an increased expression of trefoil factor proteins, which protect mucous epithelia or inhibit the expression of c-erb-2 oncogene.

Farnesol, a mevalonate pathway intermediate, stimulates MCF-7 breast cancer cell growth through farnesoid-X-receptor-mediated estrogen receptor activation

Farnesoid X receptor (FXR) is a metabolic nuclear receptor expressed in the liver and traditionally considered as a bile acid sensor. Yet, FXR has been recently demonstrated in other tissues and cells, such as the kidneys, the adrenals, and arterial smooth muscle cells. Immunohistochemical data reported in this study point to the expression of FXR in human breast cancer. In addition, FXR expression was also found by Western blotting and immunofluorescence microscopy in breast-cancer-derived cell lines MCF-7 (estrogen receptor [ER]-positive) and MDA-MB-231 (ER-negative). The FXR activator farnesol, a mevalonate pathway intermediate, exerts a mitogenic effect on MCF-7 cells. The growth stimulation is completely suppressed by antiestrogens. In contrast, MDA-MB-231 cells appear farnesol-insensitive, suggesting an involvement of ER in farnesol mitogenicity. In accordance with this interpretation, farnesol induces in MCF-7 cells a decrease of ER level, consistent with a phenomenon of receptor downregulation. Farnesol also increases progesterone receptor (PgR) expression in MCF-7 cells and stimulates ER-mediated gene transactivation in MVLN cells (MCF-7 cells stably transfected with an ER reporter gene). Of note, both effects of farnesol on ER expression and activity are completely suppressed by antiestrogens. In addition, farnesol-induced PgR is markedly reduced by FXR gene silencing (siRNA), demonstrating the involvement of FXR in the estrogenic effects of farnesol. Finally, coimmunoprecipitation experiments (FXR immunoprecipitation followed by Western blot analysis of ER in the immunoprecipitate) produced definite evidence that FXR interacts with ER. Altogether, these observations reveal the hitherto unreported presence of FXR in breast cancer and show that the latter receptor functionally interacts with ER. The occurrence of such a crosstalk calls for some caution regarding the pharmacological use of FXR agonists.

Glycochenodeoxycholate (GCDC) inhibits cytokine induced iNOS expression in rat hepatocytes

BACKGROUND

Although the accumulation of hydrophobic bile acid (e.g., glycine conjugated chenodeoxycholic acid, GCDC) is considered to be an important factor contributing to cholestatic liver dysfunction, its pathogenesis is poorly understood. The purpose of this study was to examine the effect of the bile salt GCDC on the regulation of iNOS expression, a key immune modulator during liver inflammation.

MATERIALS AND METHODS

GCDC significantly decreased cytokine-stimulated iNOS promoter activity, and both iNOS mRNA and protein expression. GCDC decreased iNOS promoter activity by preventing IkappaB degradation and inhibiting NF-kappaB DNA-binding activity. To explore the role of iNOS in bile salt induced apoptosis, we also examined the effect of NO on caspase-3 activity.

RESULTS

GCDC strongly induced caspase-3 activity, and this increase was abrogated by both exogenous NO exposure and endogenous NO synthesis. Furthermore, adenoviral iNOS (AdiNOS) pre-treatment decreased acute cholestatic-induced liver injury in a rat bile duct ligation model.

CONCLUSIONS

These findings indicate a novel signaling pathway where potentially toxic bile salts down-regulate hepatic iNOS expression. This blockade of the iNOS mediated antiapoptotic phenotype may have important implications in certain liver disorders.

The Farnesoid X Receptor Is Expressed in Breast Cancer and Regulates Apoptosis and Aromatase Expression

Bile acids are present at high concentrations in breast cysts and in the plasma of postmenopausal women with breast cancer. The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that regulates bile acid homeostasis. FXR was detected in normal and tumor breast tissue, with a high level of expression in ductal epithelial cells of normal breast and infiltrating ductal carcinoma cells. FXR was also present in the human breast carcinoma cells, MCF-7 and MDA-MB-468. Activation of FXR by high concentrations of ligands induced MCF-7 and MDA-MB-468 apoptosis. At lower concentrations that had no direct effect on viability, the FXR agonist GW4064 induced expression of mRNA for the FXR target genes, small heterodimer partner (SHP), intestinal bile acid binding protein, and multidrug resistance-associated protein 2 (MRP-2), and repressed the expression of the SHP target gene aromatase. In contrast to MRP-2, mRNA for the breast cancer target genes MDR-3, MRP-1, and solute carrier transporter 7A5 were decreased. Although multidrug resistance transporters were regulated and are known FXR target genes, GW4064 had no effect on the cell death induced by the anticancer drug paclitaxel. Our findings show for the first time that FXR is expressed in breast cancer tissue and has multiple properties that could be used for the treatment of breast cancer.

Plasma deoxycholic acid concentration is elevated in postmenopausal women with newly diagnosed breast cancer

OBJECTIVE

High concentrations of plasma deoxycholic acid (DCA) are found in human breast cyst fluid and it has been hypothesised that this may be related to risk of breast cancer. The aim of this pilot study was to ascertain whether plasma bile acid concentrations were greater in women with breast cancer.

DESIGN

A case-control study comparing postmenopausal women with breast cancer with healthy controls was conducted.

SUBJECTS

Twenty Caucasian postmenopausal breast cancer patients were recruited at the time of diagnosis together with 20 healthy controls matched for age and body mass index. Exclusion criteria included any treatment for breast cancer, use of hormone replacement therapy in the last 12 months, diabetes mellitus, a history of liver or gall bladder disease or abnormal liver function.

MEASUREMENTS

Fasting plasma bile acid concentrations were determined by gas-liquid chromatography/mass spectrometry.

RESULTS

The mean plasma DCA concentration was 52% higher (P=0.012) in patients with breast cancer compared with controls.

CONCLUSION

These results support the hypothesis that DCA may be involved in the aetiology of breast cancer.

Acute effects of dietary fat composition on postprandial plasma bile acid and cholecystokinin concentrations in healthy premenopausal women

Bile acids derived from intestinal bacterial metabolism and transported to the breast in plasma may influence risk of breast cancer. The purpose of the present study was to test the hypothesis that fatty acid chain length and degree of unsaturation differ with regard to their influence on the postprandial release of cholecystokinin (CCK) and the subsequent increase in plasma bile acid concentrations that occur following a meal. A randomized crossover design was used to compare five high-fat test meals (50 g fat) with a low-fat test meal (15 g) on plasma bile acid and CCK concentrations in eighteen healthy premenopausal women. The high-fat meals were enriched in oleate or palmitate, or linoleate or medium-chain triacylglycerols (MCT) or a blend of oleate and long-chain n-3 fatty acids. The postprandial increase in plasma CCK concentration was lower on the MCT meal compared with all meals and was greater following the linoleate compared with the low-fat meal. Plasma bile acid concentrations increased 2-3-fold postprandially but the increase was lower following the MCT meal compared with the other meals and was greater on the linoleate meal compared with the low-fat meal. The postprandial increases in plasma chenodeoxycholic acid concentration showed a trend to rise with increasing unsaturation of the test meal. In conclusion, meals rich in linoleate are a potent stimulus for CCK release and lead to prolonged elevations of plasma bile acids and meals containing MCT inhibit CCK release and the subsequent increase in plasma bile acid concentrations.

The role of bile acids in carcinogenesis

Bile acids play a role in colorectal carcinogenesis as evidenced by epidemiological and experimental studies. Some bile acids stimulate growth of normal colonic and adenoma cells, but not of colorectal cancer cells. Moreover, bile acids stimulate invasion of colorectal cancer cells, at least in vitro. One possible mechanism of action is bile acid-induced DNA binding and transactivation of the activator protein-1 (AP-1) by co-operate activation of extracellular signal-regulated kinases (ERKs) and PKC signaling. In the present paper, we review the mechanisms by which bile acids influence carcinogenesis.

Aspects of the biology of regeneration and repair in the human gastrointestinal tract

The main pathways of epithelial differentiation in the intestine, Paneth, mucous, endocrine and columnar cell lineages are well recognized. However, in abnormal circumstances, for example in mucosal ulceration, a cell lineage with features distinct from these emerges, which has often been dismissed in the past as 'pyloric' metaplasia, because of its morphological resemblance to the pyloric mucosa in the stomach. However, we can conclude that this cell lineage has a defined phenotype unique in gastrointestinal epithelia, has a histogenesis that resembles that of Brunner's glands, but acquires a proliferative organization similar to that of the gastric gland. It expresses several peptides of particular interest, including epidermal growth factor, the trefoil peptides TFF1, TFF2, TFF3, lysozyme and PSTI. The presence of this lineage also appears to cause altered gene expression in adjacent indigenous cell lineages. We propose that this cell lineage is induced in gastrointestinal stem cells as a result of chronic mucosal ulceration, and plays an important part in ulcer healing; it should therefore be added to the repertoire of gastrointestinal stem cells.

Effect of bile acids and estradiol on thymidine incorporation into DNA in MCF-7 and MCF-10A breast cell lines

Bile acid conjugates are found in human breast cyst fluid in average concentrations about 50-fold greater than those in blood. Because epidemiologic studies have linked colon and breast cancer and aberrant bile acid profiles are associated with colon cancer risk, we decided to study the influence of bile acid conjugates (glycochenodeoxycholic acid, glycodeoxycholic acid, glycocholic acid, and glycolithocholic acid) on thymidine incorporation into DNA in cancer (MCF-7) and noncancer (MCF-10A) human mammary cell lines. The two lines responded differently. In MCF-7, bile acids, except for glycolithocholic acid, stimulated thymidine incorporation. Estradiol caused even greater stimulation, an effect that was not influenced further by the addition of bile acids. Bile acids suppressed incorporation in MCF-10A cells. Estradiol at 1 nM had no effect, but 10 nM estradiol was stimulatory. In most cases bile acids appeared to diminish the incorporations observed with estradiol alone, but not significantly. The relevance of these studies to the possible impact of bile acids on the course of fibrocystic disease of the breast would require further investigation.

Trefoil peptides

There is a growing body of evidence supporting the hypothesis that members of the trefoil peptide family are involved actively in maintaining the integrity of the gastrointestinal mucosa and facilitating its repair. To date, three trefoil peptides are known in man: pS2, ITF and SP. Each is a secretory peptide expressed in specific compartments throughout the gut, in patterns that appear generally to be conserved between mammalian species. Ulceration, whether due to common pathological processes or experimentally induced, results in altered local expression of trefoil peptides. In diverse chronic ulcerative conditions in man, glandular structures develop within the mucosa, derived from the UACL. These UACL glands express three trefoil peptides, EGF and lysozyme, all potentially able to contribute to the healing process. In fact local goblet and endocrine cell types may also be recruited to secrete pS2 into the local environment. In experimental ulcers, in rate stomach or intestinal resection margins, there is also accentuation of trefoil peptide expression at the margins and in the poorly differentiated mucous cells extending out presumably in attempts to restore epithelial integrity. Several trefoil peptides have been expressed as 'recombinant' proteins in bacterial, baculoviral or yeast systems, and these procedures have allowed some of the biological properties of these peptides to be determined. In vitro, rITF, hITF and hSP are motogens, able to promote migration of epithelial cells. In vivo, rITF and hSP are able to prevent much of the gastric damage effect by a single dose of indomethacin, when given systemically. There is synergy between EGF and rITF both in vitro and in vivo, which may allow the development of new peptide therapies for ulceration that will maximize repair and minimize cell proliferation.

The E-screen assay: a comparison of different MCF7 cell stocks

MCF7 human breast cancer cells have been studied extensively as a model for hormonal effects on breast cancer cell growth and specific protein synthesis. Because the proliferative effect of natural estrogen is considered the hallmark of estrogen action, it was proposed that this property be used to determine whether a substance is an estrogen. The E-screen assay, developed for this purpose, is based on the ability of MCF7 cells to proliferate in the presence of estrogens. The aim of our study was to characterize the response of four MCF7 cell stocks (BUS, ATCC, BB, and BB104) and determine which of them performed best in the E-screen test. The four stocks assayed were distinguishable by their biological behavior. In the absence of estrogen, MCF7 BUS cells stopped proliferating and accumulated in the G0/G1 phase of the cell cycle; estrogen receptors increased, progesterone receptors decreased, and small amounts of pS2 protein were secreted. Of all the MCF7 stocks tested, MCF7 BUS cells showed the highest proliferative response to estradiol-17 beta: cell yields increased up to sixfold over those of nontreated cells in a 144-hr period. The differences between estrogen-supplemented and nonsupplemented MCF7 BUS cells were due mostly to G0/G1 proliferative arrest mediated by charcoal dextran-stripped serum. MCF7 BUS cell stocks and others showing a similar proliferative pattern should be chosen for use in the E-screen test, or whenever a proliferative effect of estrogen is to be demonstrated.

Expression of the trefoil peptides pS2 and human spasmolytic polypeptide (hSP) in Barrett's metaplasia and the native oesophageal epithelium: delineation of epithelial phenotype

The distribution of the two trefoil peptides pS2 and human spasmolytic polypeptide (hSP) and their mRNAs was investigated in 90 selected oesophageal biopsies, 23 of which contained epithelium with wholly gastric cardiac-type morphology, 52 specialized (intestinal)-type metaplasia, and 15 non-metaplastic oesophageal epithelium. No fundic-type epithelium was represented. The cardiac-type epithelium resembled true gastric antral epithelium, with hSP and pS2 mRNA localization to the superficial/foveolar compartment and hSP mRNA alone in deeper glands. The pattern of peptide distribution was broadly in line with the mRNA, but hSP peptide was generally not demonstrable in the surface epithelium. pS2 immunostaining was diffusely cytoplasmic, whereas in specialized-type mucosa it was aggregated and cytoplasmic. hSP mRNA was demonstrable in surface epithelium of incomplete- but not complete-type intestinal (specialized) metaplasia. Deep glands with morphological features of pyloric glands/ulcer-associated cell lineage (UACL) typically contained only hSP peptide and its mRNA. In three biopsies containing specialized epithelium, small foci morphologically identical to true small intestinal surface epithelium were seen in which only pS2 mRNA and peptide were found and then only in rare goblet cells. Neither squamous epithelium nor oesophageal glands contained demonstrable pS2/hSP mRNA or peptide. The function of these proteins in the metaplastic mucosa of Barrett's oesophagus is unknown but they may reflect an epithelium responding to repeated insult. Their localization facilitates definition of the disparate epithelium types seen in this portion of the gut, with both native gastric and intestinal epithelia, and may help to pinpoint high-risk epithelium in Barrett's oesophagus, a potentially preneoplastic condition.

Prognostic value of Cathepsin D expression in breast cancer: immunohistochemical assessment and correlation with radiometric assay

BACKGROUND

The prognostic significance of Cathepsin D and optimal methodologies to measure Cathepsin D in breast cancers are controversial.

PATIENTS AND METHODS

Quantitative (immunoradiometric) and semiquantitative (immunohistochemical) assays for Cathepsin D expression were compared using 25 breast carcinomas. Immunohistochemical Cathepsin D results were derived using 3 different anti-Cathepsin D antibodies and significant associations between immunohistochemical and radiometric Cathepsin D data were observed for each reagent. Immunohistochemical analysis of Cathepsin D expression was performed on nearly 500 fixed-embedded archival breast cancers with long-term patient follow-up using 2 anti-Cathepsin D antibodies (CDR2-11/23, IC11).

RESULTS

The immunohistochemical reagents recognized generally overlapping subsets of Cathepsin D positive tumors (correlation co-efficient 0.54; p = 0.00016). Correlations between Cathepsin D data and clinical, histologic or biologic features differed for each antibody. For the node-negative patient subset, Cathepsin D immunopositivity correlated with erbB-2 and stress-response protein 27 overexpression but not survival. Cathepsin D positivity was associated with subsequent distant metastasis and estrogen receptor positivity in node positive patients. Univariate analysis of all patients suggested that Cathepsin D immunopositivity may be predictive of a reduced metastasis-free but not overall survival. Multivariate analysis, however, failed to confirm an independent prognostic value for Cathepsin D in breast cancer patients.

CONCLUSIONS

These data do not confirm an independent prognostic significance for Cathepsin D using immunohistochemical methods on breast cancers.

Breast-gut connection: origin of chenodeoxycholic acid in breast cyst fluid

The notion that a breast-gut connection might modulate the microenvironment of breast tissue was supported by the finding that breast cyst fluid contains bile acids that are characteristically found in the intestines. To establish that the gut, rather than circulating steroid precursors, is the source of bile acids in breast cyst fluid, we gave two patients deuterium-labelled chenodeoxycholic acid (three 200 mg doses by mouth), starting 9 days before aspiration of breast cysts. The chenodeoxycholic acid concentration of seven samples of aspirated cyst fluid ranged from 42 to 94 mumol/L. The corresponding serum concentrations of chenodeoxycholic acid on the same day were 0.8 and 2.9 mumol/L, of which the labelled compound comprised 13.0% (0.38 mumol/L) and 28.2% (0.23 mumol/L). The deuterated chenodeoxycholic acid concentrations in cyst fluid were 0.79 and 1.26 mumol/L in two samples from patient 1 and 3.22 mumol/L in patient 2; these values are equivalent to 11-17% of the serum concentrations [corrected]. This study shows that intestinal bile acids rapidly gain access to cyst fluid. Further studies should investigate the mechanisms that govern the exchange processes and the maintenance of the high cyst fluid to plasma concentration gradients, and the biological half-lives of individual constituents.

Steroid receptors, pS2 and cathepsin D in early clinically node-negative breast cancer

Four oestrogen-regulated proteins of reported prognostic value, oestrogen receptor (ER), progesterone receptor (PR), pS2 and cathepsin D (Cat D), have been quantified by immunoassays, and the latter studied by immunohistochemistry (IHC) in primary tumours from clinically node-negative early breast cancer patients, entered into a trial of breast conservation therapy in which all the patients received adjuvant tamoxifen. ER, PR and pS2 significantly co-correlated but none correlated with Cat D. ER, PR and pS2, but not Cat D, were significantly associated with tumour size and grade, although Cat D tended to show an inverse relationship with the latter. Cat D (radioimmunoassay) in pmol/mg significantly correlated with the IHC score for Cat D in carcinoma cells as well as the number of Cat D-expressing macrophages. At a median follow-up of only 16 months, recurrence was significantly more common in patients with tumours having negative status for ER, PR and pS2 but was not associated with Cat D status.

Glycochenodeoxycholate-induced lethal hepatocellular injury in rat hepatocytes. Role of ATP depletion and cytosolic free calcium

Chenodeoxycholate is toxic to hepatocytes, and accumulation of chenodeoxycholate in the liver during cholestasis may potentiate hepatocellular injury. However, the mechanism of hepatocellular injury by chenodeoxycholate remains obscure. Our aim was to determine the mechanism of cytotoxicity by chenodeoxycholate in rat hepatocytes. At a concentration of 250 microM, glycochenodeoxycholate was more toxic than either chenodeoxycholate or taurochenodeoxycholate. Cellular ATP was 86% depleted within 30 min after addition of glycochenodeoxycholate. Fructose, a glycolytic substrate, maintained ATP concentrations at 50% of the initial value and protected against glycochenodeoxycholate cytotoxicity. ATP depletion in the absence of a glycolytic substrate suggested impairment of mitochondrial function. Indeed, glycochenodeoxycholate inhibited state 3 respiration in digitonin-permeabilized cells in a dose-dependent manner. After ATP depletion, a sustained rise in cytosolic free calcium (Cai2+) was observed. Removal of extracellular Ca2+ abolished the rise in Cai2+, decreased cellular proteolysis, and protected against cell killing by glycochenodeoxycholate. The results suggest that glycochenodeoxycholate cytotoxicity results from ATP depletion followed by a subsequent rise in Cai2+. The rise in Cai2+ leads to an increase in calcium-dependent degradative proteolysis and, ultimately, cell death. We conclude that glycochenodeoxycholate causes a bioenergetic form of lethal cell injury dependent on ATP depletion analogous to the lethal cell injury of anoxia.

Potentiation of butyrate-induced differentiation in human colon tumor cells by deoxycholate

Human colon adenocarcinoma cells, treated with deoxycholate for 24 h prior to exposure to 1 mM butyrate, exhibited dose-dependent increases in the activities of three markers of colonic differentiation (alkaline phosphatase, lactase and CEA). Treatment with deoxycholate alone, for 24 h or longer, did not increase the secretion of CEA or the activities of either of the brush border-associated enzyme activities. Increases in differentiation markers were found to be bile acid-specific. Pretreatment with either dehydrocholic acid or cholic acid, even at cytotoxic concentrations, led to no significant butyrate-induced increases in brush-border associated hydrolase activities. The addition of a bacterial superoxide dismutase decreased the short-term cytotoxicity of deoxycholate and increased the maturation-potentiating effects of the bile acid in HCT-116 DO cells. The results of these studies demonstrate that bile acids, which are commonly thought to have tumor promoting activities in vivo, may also have physiological effects which serve to limit carcinogenic processes in the human colon by potentiating tumor cell differentiation.

Oestrogen and progesterone receptors in colorectal cancer and human colonic cancer cell lines

Receptors for oestrogen (ER) and progesterone (PR) were assayed in tissue from 17 patients with colorectal cancer and five colonic cancer cell lines using enzyme immunoassays. ERs and PRs were detected in 15 and 17 cancers respectively, although the levels detected were low: median (range) ER 1.3 (0-11.3) and PR 3.9 (0.3-10.2) fmol per mg protein. These values were not significantly different from median (range) levels of ER (1.1 (0.6-3.0) fmol/mg) and PR (1.9 (0.5-3.2) fmol/mg) detected in normal mucosa. There were significant positive correlations between the levels of ER and PR for cancer tissue (tau = 0.56, P < 0.005; r(log transform) = 0.68, P < 0.003; n = 17) but not for mucosa, and between levels of ER in cancer tissue and mucosa (tau = 0.55, P < 0.05; r(log transform) = 0.70, P < 0.025; n = 10) but not between the corresponding PR values. In maintenance media, which contained phenol red and unstripped fetal calf serum, the median (range) concentration of ER was 1.9 (1.2-10.4) fmol/mg and that for PR 24.3 (9.1-63.2) fmol/mg in the five cell lines studied (HT-29, LS174T, SW620, LoVo, COLO 320DM). The addition of oestradiol (10 nmol/l) to phenol red-free medium containing 5 per cent dextran-coated charcoal-treated fetal calf serum had little effect on the concentration of ERs or PRs in SW620, LoVo and COLO 320DM cells after 7 days' culture. It is concluded that ERs and PRs are expressed in malignant and normal colonic mucosa. ERs appear to be a feature of the colonic mucosa rather than the malignant process, but in carcinoma may regulate synthesis of PRs, suggesting a degree of oestrogen responsiveness.