Novel agents for the prevention of breast cancer: targeting transcription factors and signal transduction pathways

Prognostic role of EGR1 in breast cancer: a systematic review

EGR1 (early growth response 1) is dysregulated in many cancers and exhibits both tumor suppressor and promoter activities, making it an appealing target for cancer therapy. Here, we used a systematic multiomics analysis to review the expression of EGR1 and its role in regulating clinical outcomes in breast cancer (BC). EGR1 expression, its promoter methylation, and protein expression pattern were assessed using various publicly available tools. COSMIC-based somatic mutations and cBioPortal-based copy number alterations were analyzed, and the prognostic roles of EGR1 in BC were determined using Prognoscan and Kaplan-Meier Plotter. We also used bc-GenEx-Miner to investigate the EGR1 co-expression profile. EGR1 was more often downregulated in BC tissues than in normal breast tissue, and its knockdown was positively correlated with poor survival. Low EGR1 expression levels were also associated with increased risk of ER+, PR+, and HER2-BCs. High positive correlations were observed among EGR1, DUSP1, FOS, FOSB, CYR61, and JUN mRNA expression in BC tissue. This systematic review suggested that EGR1 expression may serve as a prognostic marker for BC patients and that clinicopathological parameters influence its prognostic utility. In addition to EGR1, DUSP1, FOS, FOSB, CYR61, and JUN can jointly be considered prognostic indicators for BC.

Association of ApaI and TaqI polymorphisms in VDR Gene with Breast Cancer

Background:

Vitamin D inhibits cell proliferation via the vitamin D receptor (VDR), which may affect breast cancer risk. This study aimed to investigate the association of ApaI and TaqI polymorphisms of the VDR gene with breast cancer risk which followed by stratified analysis.

Materials and methods:

A case-control study was conducted on 150 breast cancer patients and 150 healthy controls. VDR ApaI and TaqI genotyping were performed by PCR-RFLP. Some demographic and pathologic features of patients were extracted from their archived files and then were analyzed by genotypes distributions.

Results:

For ApaI polymorphism, our data showed a significant difference between the patient and healthy groups for mutant allele carriers compared with those with AA genotype. Besides, statistical analysis showed that there was a significant association between the C allele and the increased risk of breast cancer. For TaqI polymorphism, statistical analysis revealed that there was a significant association between CC genotype and increased risk of breast cancer. Also, there was a significant association between the C allele and the increased risk of breast cancer. In a preliminary study, stratified analysis based on the size of tumor and lymph node metastasis revealed no significant association between two ApaI and TaqI variations and these parameters.

Conclusions:

Based on our results, the VDRApaI and TaqI variations could be considered as genetic risk factors for breast cancer. However, further studies with a larger sample size are required to obtain more accurate outcomes, especially in stratified analysis.

Topological alternate centrality measure capturing drug targets in the network of MAPK pathways

A new centrality of the nodes in the network is proposed called alternate centrality, which can isolate effective drug targets in the complex signalling network. Alternate centrality metric defined over the network substructure (four nodes - motifs). The nodes involving in alternative activation in the motifs gain in metric values. Targeting high alternative centrality nodes hypothesised to be destructive free to the network due to their alternative activation mechanism. Overlapping and crosstalk among the gene products in the conserved network of MAPK pathways selected for the study. In silico knock-out of high alternate centrality nodes causing rewiring in the network is investigated using MCF-7 breast cancer cell line-based data. Degree of top alternate centrality nodes lies between the degree of bridging and pagerank nodes. Node deletion of high alternate centrality on the centralities such as eccentricity, closeness, betweenness, stress, centroid and radiality causes low perturbation. The authors identified the following alternate centrality nodes ERK1, ERK2, MEKK2, MKK5, MKK4, MLK3, MLK2, MLK1, MEKK4, MEKK1, TAK1, P38alpha, ZAK, DLK, LZK, MLTKa/b and P38beta as efficient drug targets for breast cancer. Alternate centrality identifies effective drug targets and is free from intertwined biological processes and lethality.

Deciphering the roles of lncRNAs in breast development and disease

Breast cancer is the second leading cause of cancer related deaths in women. It is therefore important to understand the mechanisms underlying breast cancer development as well as raises the need for enhanced, non-invasive strategies for novel prognostic and diagnostic methods. The emergence of long non-coding RNAs (lncRNAs) as potential key players in neoplastic disease has received considerable attention over the past few years. This relatively new class of molecular regulators has been shown from ongoing research to act as critical players for key biological processes. Deregulated expression levels of lncRNAs have been observed in a number of cancers including breast cancer. Furthermore, lncRNAs have been linked to breast cancer initiation, progression, metastases and to limit sensitivity to certain targeted therapeutics. In this review we provide an update on the lncRNAs associated with breast cancer and mammary gland development and illustrate the versatility of such lncRNAs in gene control, differentiation and development both in normal physiological conditions and in diseased states. We also highlight the therapeutic and diagnostic potential of lncRNAs in cancer.

Canine mammary tumors as a model for human disease

Animal models for examining human breast cancer (HBC) carcinogenesis have been extensively studied and proposed. With the recent advent of immunotherapy, significant attention has been focused on the dog as a model for human cancer. Dogs develop mammary tumors and other cancer types spontaneously with an intact immune system, which exhibit a number of clinical and molecular similarities to HBC. In addition to the spontaneous tumor presentation, the clinical similarities between human and canine mammary tumors (CMT) include the age at onset, hormonal etiology and course of the diseases. Furthermore, factors that affect the disease outcome, including tumor size, stage and lymph node invasion, are similar in HBC and CMT. Similarly, the molecular characteristics of steroid receptor, epidermal growth factor, proliferation marker, metalloproteinase and cyclooxygenase expression, and the mutation of the p53 tumor suppressor gene in CMT, mimic HBC. Furthermore, ductal carcinomas in situ in human and canine mammary glands are particularly similar in their pathological, molecular and visual characteristics. These CMT characteristics and their similarities to HBC indicate that the dog could be an excellent model for the study of human disease. These similarities are discussed in detail in the present review, and are compared with the in vitro and other in vivo animal models available.

Association of vitamin D receptor gene polymorphisms with breast cancer risk in an Egyptian population

This study aimed to explore whether genetic polymorphisms in vitamin D receptor are correlated to the breast cancer prevalence in an Egyptian population. Polymerase chain reaction-restriction fragment polymorphism was used to genotype three frequently analyzed vitamin D receptor gene single-nucleotide polymorphisms (rs1544410, rs7975232, and rs731236) and were identified by sequencing analysis. This is the first study that recorded a new single-nucleotide polymorphism in ApaI genotype within an Egyptian population and was registered with the accession number KY859868. The authors found that TC in rs731236, and TG in KY859868 single-nucleotide polymorphism showed significant distribution differences with an increased risk of breast cancer ( p < 0.05, odds ratio = 3.71, 95% confidence interval: 1.04-13.28 and p < 0.001, odds ratio = 7.05, 95% confidence interval: 2.02-24, respectively) compared with the wild-type TT genotype carriers in both single-nucleotide polymorphisms. In addition, the distribution frequencies of haplotypes ACT, GTT, and ATT in the patients group were significant, where ATT haplotype was associated with the highest breast cancer risk among all other haplotypes in the patients group ( p = 0.0023, odds ratio = 1.72, 95% confidence interval: 1.24-2.437). In conclusion, vitamin D receptors ApaI and TaqI confer high breast cancer susceptibility, particularly in Egyptians females carrying haplotype ATT. However, further studies focusing on the vitamin D receptor variants and haplotypes effects on vitamin D and vitamin D receptor concentrations, activities, and functionalities are needed.

Lack of effect of the procarcinogenic 17β-estradiol on nutrient uptake by the MCF-7 breast cancer cell line

Breast cancer is one of the most frequent cancers in the population, especially in older women. Estrogen is known to be a key hormone in the development and progression of mammary carcinogenesis. In this study, we investigated if the procarcinogenic effect of 17β-estradiol (E2) in breast cancer MCF-7 cells is dependent on changes in glucose or folic acid cellular uptake. The effect of E2 on uptake of ³H-deoxy-d-glucose, ³H-folic acid, cell proliferation (3-thymidine incorporation assay), culture growth (sulforhodamine B assay), viability (lactate dehydrogenase activity assay), lactate production and migration capacity (injury assay) was evaluated. E2 (48h; 100nM) increased culture growth (16%), proliferation rate (24%), cellular viability (36%) and lactate production (38%). In contrast, E2 did not significantly affect the migration capacity of MCF-7 cells. The pro-proliferative, but not the cytoprotective effect of E2 was found to be ERβ-dependent. The polyphenols rutin and caffeic acid were not able to counteract the effect of E2 upon cell proliferation and viability. Uptake of ³H-deoxy-d-glucose was not affected by E2, either in the absence or presence of GLUT inhibitors (cytochalasin B plus phloridzin). Moreover, E2 did not change GLUT1 mRNA levels. Finally, ³H-folic acid uptake was also not affected by E2, both in the absence and presence of the RFC1 inhibitor, methotrexate. The pro-proliferative and cytoprotective effects of E2 are not dependent neither of stimulation of glucose cellular uptake (both GLUT and non-GLUT-mediated) nor of stimulation of folic acid uptake (both RFC1-and non-RFC1-mediated).

Identification of ApoA1, HPX and POTEE genes by omic analysis in breast cancer

Breast cancer is the most common cancer among women and accounts for 23% of all female types of cancers. It is well recognized that breast cancer represents a heterogeneous group of tumors, and the molecular events involved in the progression to cancer remain undetermined. Moreover, available prognostic and predictive markers are not sufficient for the accurate determination of the risk for many breast cancer patients. Thus, it is necessary to discover new molecular markers for accurate prediction of clinical outcome and individualized therapy. In the present study, we performed omics-based whole-genome trancriptomic and whole proteomic profiling with network and pathway analyses of breast tumors to identify gene expression patterns related to clinical outcome. A total of 20 samples from tumors and 14 normal appearing breast tissues were analyzed using both gene expression microarrays and LC-MS/MS. We identified 585 downregulated and 413 upregulated genes by gene expression microarrays. Among these genes, HPX, POTEE and ApoA1 were the most significant genes correlated with the proteomic profile. Our data revealed that these identified genes are closely related to breast cancer and may be involved in robust detection of disease progression.

Upregulated Myc expression in N-methyl nitrosourea (MNU)- induced rat mammary tumours

BACKGROUND

The most common incident cancer and cause of cancer-related deaths in women is breast cancer. The Myc gene is upregulated in many cancer types including breast cancer, and it is considered as a potential anti-cancer drug target. The present study was conducted to evaluate the Myc (gene and protein) expression pattern in an experimental mammary tumour model in rats.

MATERIALS AND METHODS

Thirty six Sprague Dawley rats were divided into: Experimental group (26 animals), which received the chemical carcinogen N-methyl nitrosourea (MNU) and a control group (10 animals), which received vehicle only. c-Myc oncoprotein and its mRNA expression pattern were evaluated using immunohistochemistry (IHC) and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), respectively, in normal rat mammary tissue and mammary tumours. The rat glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene was used as internal control for semi-quantitative RT-PCR.

RESULTS

Histopathological examination of mammary tissues and tumours from MNU treated animals revealed the presence of premalignant lesions, benign tumours, in situ carcinomas and invasive carcinomas. Immunohistochemical evaluation of tumour tissues showed upregulation and heterogeneous cellular localization of c-Myc oncoprotein. The expression levels of c-Myc oncoprotein were significantly elevated (75- 91%) in all the tumours. Semi-quantitative RT-PCR revealed increased expression of c-Myc mRNA in mammary tumours compared to normal mammary tissues.

CONCLUSIONS

Further large-scale investigation study is needed to adopt this experimental rat mammary tumour model as an in vivo model to study anti-cancer strategies directed against Myc or its downstream partners at the transcriptional or post-transcriptional level.

Pubertal bisphenol A exposure alters murine mammary stem cell function leading to early neoplasia in regenerated glands

Perinatal exposure to bisphenol A (BPA) has been shown to cause aberrant mammary gland morphogenesis and mammary neoplastic transformation. Yet, the underlying mechanism is poorly understood. We tested the hypothesis that mammary glands exposed to BPA during a susceptible window may lead to its susceptibility to tumorigenesis through a stem cell-mediated mechanism. We exposed 21-day-old Balb/c mice to BPA by gavage (25 μg/kg/d) during puberty for 3 weeks, and a subset of animals were further challenged with one oral dose (30 mg/kg) of 7,12-dimethylbenz(a)anthracene (DMBA) at 2 months of age. Primary mammary cells were isolated at 6 weeks, and 2 and 4 months of age for murine mammary stem cell (MaSC) quantification and function analysis. Pubertal exposure to the low-dose BPA increased lateral branches and hyperplasia in adult mammary glands and caused an acute increase of MaSC in 6-week-old glands and a delayed increase of luminal progenitors in 4-month-old adult gland. Most importantly, pubertal BPA exposure altered the function of MaSC from different age groups, causing early neoplastic lesions in their regenerated glands similar to those induced by DMBA exposure, which indicates that MaSCs are susceptible to BPA-induced transformation. Deep sequencing analysis on MaSC-enriched mammospheres identified a set of aberrantly expressed genes associated with early neoplastic lesions in patients with human breast cancer. Thus, our study for the first time shows that pubertal BPA exposure altered MaSC gene expression and function such that they induced early neoplastic transformation.

Chemoprevention of lung cancer: concepts and strategies

Lung cancer develops in a stepwise fashion, with an accumulation of molecular alterations progressing through preinvasive steps to invasive disease. This progression could be arrested or reversed through pharmacologic treatments, which are known as cancer chemoprevention. Preclinical and clinical findings relating to different classes of candidate chemopreventive agents provide support for this strategy as an active and promising approach for controlling this disease.

The role of master regulators in the metabolic/transcriptional coupling in breast carcinomas

Metabolic transformations have been reported as involved in neoplasms survival. This suggests a role of metabolic pathways as potential cancer pharmacological targets. Modulating tumor's energy production pathways may become a substantial research area for cancer treatment. The significant role of metabolic deregulation as inducing transcriptional instabilities and consequently whole-system failure, is thus of foremost importance. By using a data integration approach that combines experimental evidence for high-throughput genome wide gene expression, a non-equilibrium thermodynamics analysis, nonlinear correlation networks as well as database mining, we were able to outline the role that transcription factors MEF2C and MNDA may have as main master regulators in primary breast cancer phenomenology, as well as the possible interrelationship between malignancy and metabolic dysfunction. The present findings are supported by the analysis of 1191 whole genome gene expression experiments, as well as probabilistic inference of gene regulatory networks, and non-equilibrium thermodynamics of such data. Other evidence sources include pathway enrichment and gene set enrichment analyses, as well as motif comparison with a comprehensive gene regulatory network (of homologue genes) in Arabidopsis thaliana. Our key finding is that the non-equilibrium free energies provide a realistic description of transcription factor activation that when supplemented with gene regulatory networks made us able to find deregulated pathways. These analyses also suggest a novel potential role of transcription factor energetics at the onset of primary tumor development. Results are important in the molecular systems biology of cancer field, since deregulation and coupling mechanisms between metabolic activity and transcriptional regulation can be better understood by taking into account the way that master regulators respond to physicochemical constraints imposed by different phenotypic conditions.

Identification, synthesis, and biological evaluation of the metabolites of 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36), a promising rexinoid lead compound for the development of cancer chemotherapeutic and chemopreventive agents

Activation of the retinoid X receptor (RXR), which is involved in cell proliferation, differentiation, and apoptosis, is a strategy for cancer chemotherapy and chemoprevention, and 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36) (3) is among the few RXR ligands known. The presently reported studies of 3 include its binding to human plasma proteins, metabolic stability using human liver microsomes, metabolism by human liver microsomes and hepatocytes, and in vivo disposition in rat serum, liver, and mammary tissue. Compound 3 was 75% bound to human plasma proteins, and its metabolic stability was much greater than propranolol. One phase I metabolite was formed by human liver microsomes, seven phase I and II metabolites were formed by human hepatocytes, and five metabolites were detected in rat serum and liver after oral administration. The putative metabolites predicted using LC-MS-MS were synthesized to confirm their structures and to provide sufficient material for investigation of induction of RXRE transcriptional activity and inhibition of NFκB.

Association of FABP5 expression with poor survival in triple-negative breast cancer: implication for retinoic acid therapy

Recent studies using animal models suggest that expression of FABP5 drives the stimulation of cell growth observed in estrogen receptor (ER)-negative breast cancer cells on exposure to retinoic acid (RA). The purpose of this study was to investigate the clinicopathological significance of FABP5 in breast cancer and to evaluate FABP5 as a prognostic marker and a possible novel therapeutic target in breast cancer. Gene expression microarray analysis revealed a significant correlation between elevated FABP5 RNA levels and ER/progesterone receptor (PR)-negative status, high tumor grade, and poor prognosis. Tissue microarray analysis demonstrated similar correlations with cytoplasmic FABP5 protein. Based on multivariate proportional regression analysis, cytoplasmic FABP5 is a significant and independent prognostic marker of overall survival and recurrence-free survival in breast cancer. The effects of FABP5 on tumor growth appear to be mediated primarily through cytoplasmic FABP, because no correlation was found between nuclear FABP5 and ER/PR-negative status, recurrence, and survival. FABP5 knockdown in breast cancer cell lines demonstrates a correlation between FABP5 levels and growth response to RA. We propose a model whereby growth-promoting FABP5 competes with growth-inhibiting CRABP2 for RA, with retention of RA in the cytoplasm by FABP5 preventing the inhibition of tumor growth.

Gemini vitamin D analogues inhibit estrogen receptor-positive and estrogen receptor-negative mammary tumorigenesis without hypercalcemic toxicity

Numerous preclinical, epidemiologic, and clinical studies have suggested the benefits of vitamin D and its analogues for the prevention and treatment of cancer. However, the hypercalcemic effects have limited the use of 1alpha,25(OH)(2)D(3), the hormonally active form of vitamin D. To identify vitamin D analogues with better efficacy and low toxicity, we have tested >60 novel Gemini vitamin D analogues with a unique structure of two side chains for growth inhibition of breast cancer cells. Our initial studies found that some Gemini analogues are 5-15 times more active than 1alpha,25(OH)(2)D(3) in growth inhibition assay. In vivo experiments were designed to study the inhibitory effect of selected Gemini vitamin D analogues against mammary carcinogenesis by using (a) an N-methyl-N-nitrosourea-induced estrogen receptor (ER)-positive mammary tumor model and (b) an MCF10DCIS.com xenograft model of ER-negative mammary tumors. Among vitamin D analogues we tested, Gemini 0072 [1alpha,25-dihydroxy-20S-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] and Gemini 0097 [1alpha,25-dihydroxy-20R-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] administration inhibited by 60% the NMU-induced mammary tumor burden compared with the NMU-treated control group, but these compounds were devoid of hypercalcemia toxicity. In an ER-negative xenograft model, Gemini 0097 significantly suppressed tumor growth without hypercalcemia toxicity. We found that the inhibitory effect of Gemini 0097 was associated with an increased level of cyclin-dependent kinase inhibitor p21 and the insulin-like growth factor binding protein 3 in both ER-positive and ER-negative mammary tumors. Our results suggest that Gemini vitamin D analogues may be potent agents for the prevention and treatment of both ER-positive and ER-negative breast cancer without hypercalcemia toxicity.

Prevention of tumorigenesis in p53-null mammary epithelium by rexinoid bexarotene, tyrosine kinase inhibitor gefitinib, and celecoxib

The chemopreventive effects of three agents, rexinoid bexarotene, tyrosine kinase inhibitor gefitinib, and celecoxib, were tested on mammary tumor development arising in p53-null mammary epithelium. The rexinoid bexarotene was the most efficacious inhibitor as it reduced mammary tumor development by 75% in virgin mice and significantly delayed mean tumor development by 98 days in hormone-stimulated mice. The tyrosine kinase inhibitor gefitinib reduced mammary tumor incidence by 50% in virgin mice but did not significantly delay mean tumor latency in hormone-stimulated mice. Celecoxib did not reduce tumor incidence or mean tumor latency in either of the two models. The high doses of the rexinoid and the tyrosine kinase inhibitor did not affect the progression of tumors arising from the premalignant mammary outgrowth line, PN8a. A comparison of these agents with tamoxifen shows the superiority of tamoxifen in preventing tumor development in p53-null mammary cells. Similarly, a comparison of the results of the p53 model with other transgenic models in their response to the chemopreventive agents showed that mammary tumors arising from different oncogenic events will respond differently to the different agents.

The relevance of mouse models to understanding the development and progression of human breast cancer

Mouse modeling of human breast cancer has developed tremendously over the past ten years. Human breast cancer is characterized by enormous biological diversity and, collectively, the new models have come much closer to encompassing this diversity. They have provided a deeper understanding of the fundamental events that mediate the initiation, development, and progression of breast cancer, and they offer new opportunities to develop and test strategies to treat and, perhaps, even prevent the disease. This chapter reviews the historical development of mouse models of breast cancer and highlights some of their major strengths, weaknesses, and contributions.

Gene and protein expressions induced by 17beta-estradiol and parathion in cultured breast epithelial cells

Cancer of the breast is the most common form of malignant disease occurring among women of the western world and environmental substances seem to be involved in the etiology of this disease. Many studies have found an association between human cancer and exposure to agricultural pesticides and among them parathion, the organophosphorous pesticide used in agriculture to control mosquito plagues. The association between breast cancer and prolonged exposure to estrogens suggests that this hormone also may have a role in such process. However, the causative factors for breast carcinogenesis remain an enigma. The objective of this study was to determine the effects of 17beta-estradiol (E2) and parathion on cell transformation of human breast epithelial cells in vitro. The results of this study showed that parathion alone and in combination with E2 induced malignant transformation of an immortalized human breast epithelial cell line, MCF-10F, and the malignant feature was confirmed by anchorage independency and invasive capabilities. Parathion alone efficiently elevated the expression of EGFR, c-Kit, Trio, Rac 3, Rho-A, and mutant p53 proteins. Analysis of gene expression using commercially available human cell cycle array revealed transcriptional alterations in 22 out of a total of 96 genes. Among them, nine genes involved in the regulation of cell cycle were altered. These included cyclins (A1, A2, C, G1, G2, and H), cyclin-dependent kinases (CDKs), and minichromosome maintenance deficient (MCM). Results suggest that parathion has the potency to cause malignant transformation of breast epithelial cells through modulation of expression of cell cycle regulated genes.

Gene and protein expressions induced by 17beta-estradiol and parathion in cultured breast epithelial cells

Cancer of the breast is the most common form of malignant disease occurring among women of the western world and environmental substances seem to be involved in the etiology of this disease. Many studies have found an association between human cancer and exposure to agricultural pesticides and among them parathion, the organophosphorous pesticide used in agriculture to control mosquito plagues. The association between breast cancer and prolonged exposure to estrogens suggests that this hormone also may have a role in such process. However, the causative factors for breast carcinogenesis remain an enigma. The objective of this study was to determine the effects of 17beta-estradiol (E2) and parathion on cell transformation of human breast epithelial cells in vitro. The results of this study showed that parathion alone and in combination with E2 induced malignant transformation of an immortalized human breast epithelial cell line, MCF-10F, and the malignant feature was confirmed by anchorage independency and invasive capabilities. Parathion alone efficiently elevated the expression of EGFR, c-Kit, Trio, Rac 3, Rho-A, and mutant p53 proteins. Analysis of gene expression using commercially available human cell cycle array revealed transcriptional alterations in 22 out of a total of 96 genes. Among them, nine genes involved in the regulation of cell cycle were altered. These included cyclins (A1, A2, C, G1, G2, and H), cyclin-dependent kinases (CDKs), and minichromosome maintenance deficient (MCM). Results suggest that parathion has the potency to cause malignant transformation of breast epithelial cells through modulation of expression of cell cycle regulated genes.

Uterine leiomyomas express a molecular pattern that lowers retinoic acid exposure

OBJECTIVE

To analyze expression of the retinoic acid signaling pathway genes that are involved in retinol metabolism, transport, transcriptional activation, and transcriptional products in spontaneous human leiomyomas.

DESIGN

Laboratory study of human leiomyoma and patient-matched myometrial tissue.

PATIENT(S)

Eight women undergoing hysterectomy for symptomatic leiomyomas.

INTERVENTION(S)

Confirmation of an altered retinoic acid pathway analyzed by microarray, real time reverse transcription-polymerase chain reaction, Western blot, immunohistochemistry, and high-performance liquid chromatography (HPLC).

MAIN OUTCOME MEASURE(S)

Gene and protein expression.

RESULT(S)

Regardless of patient demographics and leiomyoma location and size, we found decreased expression of the major genes involved in retinoic acid pathway including alcohol dehydrogenase-1 (-3.97- +/- 0.03-fold), aldehyde dehydrogenase-1 (-3.1- +/- 0.07-fold), cellular retinol binding protein-1 (-2.62- +/- 0.04-fold), and cellular retinoic acid binding protein-1 (-2.42- +/- 0.20-fold). Cytochrome P450 (CYP 26A1), which is responsible for retinoic acid metabolism, was highly up-regulated in leiomyomas (+5.4- +/- 0.53-fold). Nuclear receptors demonstrated a complex pattern of under-expression (RARalpha, RARbeta, RXRalpha, RXRgamma) and over-expression (RARgamma, RXRbeta) at both the mRNA and protein level. Differences in protein amounts were confirmed by Western blot. Finally, a reduced amount of cellular ATRA and 9-cis retinoic acid was confirmed by HPLC in leiomyomas compared with myometrial tissues.

CONCLUSION(S)

Molecular alterations in the retinoic acid pathway of leiomyomata result in a decrease in retinoic acid exposure.

A novel gene STYK1/NOK is upregulated in estrogen receptor-alpha negative estrogen receptor-beta positive breast cancer cells following estrogen treatment

The human STYK1/NOK protein is approximately 30-35% similar to mouse fibroblast growth factor receptor 3 and a kinase homologue in D. melanogaster in the tyrosine protein kinase region. STYK1/NOK was identified as being up regulated in MDA-MB-231, an estrogen receptor-alpha negative breast cancer cell line, following 12 h of estrogen treatment at 1x10(-9) M. On further investigation of STYK1/NOK in estrogen treated cell line MDA-MB-231, STYK1/NOK was up regulated at 6 h post treatment when compared to untreated cells. We also investigated the expression levels of STYK1/NOK in other breast cancer cell lines MCF-7, MDA-MB-231, BT-549, and MDA-MB-435S using QRT-PCR. In addition, the analysis of message accumulation was increased with other synthetic estrogen response modifiers. We propose that the regulation of STYK1/NOK is achieved independent of ERalpha and suggests further investigation to the relevance of this kinase in breast cancer progression.

Expression profiling of rat mammary epithelial cells reveals candidate signaling pathways in dietary protection from mammary tumors

The role of diet in the prevention of breast cancer is widely accepted, yet little is known about how its biological effects mitigate susceptibility to this disease. Soy consumption is associated with reduced breast cancer risk in women, an effect largely attributed to the soy isoflavone genistein (Gen). We previously showed reduced incidence of chemically induced mammary tumors in young adult rats with lifetime dietary intake of soy protein isolate (SPI) than in those fed the control diet containing casein (Cas). To gain insight into signaling pathways underlying dietary tumor protection, we performed genome-wide expression profiling of mammary epithelial cells from young adult rats lifetime fed Cas, SPI, or Cas supplemented with Gen. We identified mammary epithelial genes regulated by SPI (79 total) and Gen (96 total) using Affymetrix rat 230A GeneChip arrays and found minimal overlap in gene expression patterns. We showed that the regulated transcripts functionally clustered in biochemical pathways involving metabolism, immune response, signal transduction, and ion transport. We confirmed the differential expression of Wnt (Wnt5a, Sfrp2) and Notch (Notch2, Hes1) signaling components by SPI and/or Gen using quantitative real-time PCR. Wnt pathway inhibition by Gen was supported by reduced cyclin D1 immunoreactivity in mammary ductal epithelium of Gen relative to Cas and SPI groups, despite comparable levels of membrane-localized E-cadherin and beta-catenin. Identification of distinct Gen and SPI responsive genes in mammary epithelial cells may define early events contributing to tumor protection by diet relevant to the prevention of breast and other types of cancer.

Integration of Rapid Signaling Events with Steroid Hormone Receptor Action in Breast and Prostate Cancer

Steroid hormone receptors (SRs) are ligand-activated transcription factors and sensors for growth factor-initiated signaling pathways in hormonally regulated tissues, such as the breast or prostate. Recent discoveries suggest that several protein kinases are rapidly activated in response to steroid hormone binding to cytoplasmic SRs. Induction of rapid signaling upon SR ligand binding ensures that receptors and coregulators are appropriately phosphorylated as part of optimal transcription complexes. Alternatively, SR-activated kinase cascades provide additional avenues for SR-regulated gene expression independent of SR nuclear action. We provide an overview of SR and signaling cross talk in breast and prostate cancers, using the human progesterone receptor (PR) and androgen receptor (AR) as models. Kinases are emerging as key mediators of SR action. Cross talk between SR and membrane-initiated signaling events suggests a mechanism for coordinate regulation of gene subsets by mitogenic stimuli in hormonally responsive normal tissues; such cross talk is suspected to contribute to cancer biology.

Estrogen deprivation for breast cancer prevention

Estrogen deprivation (ED) either as a result of a natural or artificial menopause or the use of aromatase inhibitors in postmenopausal women results in a reduction of the incidence of breast cancer. Two major clinical trials of this approach comparing anastrozole or exemestane with placebo are currently in progress to test their efficacy for prevention. Reduction of contralateral breast lesions by at least 50% compared with tamoxifen indicate this approach has promise. The target lesion within the breast for ED is not known but we argue that hyperplastic enlarged lobular units (HELUs) as well as more advanced lesions are good candidates. A major problem for ED is de novo or acquired resistance to its effectiveness. We discuss potential mechanisms of resistance including high concentrations of tissue estrogens, increase in growth factor, and signal transduction pathways within the epithelial cell and activation of paracrine pathways from breast adipocytes, macrophages and fibroblasts. It may be possible to increase effectiveness of ED by additional preventive agents or by lifestyle alterations.

A splice variant of CD99 increases motility and MMP-9 expression of human breast cancer cells through the AKT-, ERK-, and JNK-dependent AP-1 activation signaling pathways

The CD99 gene encodes two distinct transmembrane proteins by alternative splicing of its transcript. To examine the effects of two CD99 isoforms on the invasive phenotypes of breast cancer cells, MDA-MB-231 and MCF-7 human breast cancer cell lines were stably transfected with CD99 cDNAs encoding the major wild-type form (type I) or a minor splice variant (type II). As a result, expression of CD99 type II, but not type I, markedly elevated the motility, binding to fibronectin, MMP-9 expression, and invasiveness of MDA-MB-231 and MCF-7 breast cancer cells. In MDA-MB-435 breast cancer cells expressing both CD99 type I and type II, invasion-related cellular activities were inhibited by the transfection of small interfering RNA (siRNA) targeted to CD99 type II. Meanwhile, CD99 type II-induced MMP-9 expression in MDA-MB-231 cells was shown to be mediated by the binding of AP-1 factors to the MMP-9 gene promoter. Gel shift assay revealed that ligation of CD99 type II with antibody resulted in the binding of JunD to the AP-1 site of the MMP-9 promoter region. Initiation of CD99 type II signaling by antibody ligation increased expression of JunD and FosB AP-1 factors, along with phosphorylation of Src, Akt, p38 MAPK, ERK, and JNK. Knockdown of JunD and FosB by siRNA transfection abolished the positive effects of CD99 type II on the motility and MMP-9 expression of MDA-MB-231 cells. Increased expression of JunD and FosB as well as elevated cell motility and MMP-9 expression by CD99 type II ligation were also abrogated by inhibitors, dominant-negative forms, and siRNAs for Akt1, ERK1/2, and JNK1 but not for p38 MAPK. These results suggest that expression of a splice variant of CD99 contributes to the invasive ability of human breast cancer cells by up-regulating AP-1-mediated gene expression through the Akt-dependent ERK and JNK signaling pathways.

Lipopolysaccharide-induced cyclooxygenase-2 expression in human U937 macrophages is phosphatidic acid phosphohydrolase-1-dependent

Cyclooxygenase (COX) has two isoforms, COX-1 and -2, which catalyze the key step in the conversion of cellular arachidonic acid into prostaglandins. In recent years, interest in COX-2 has significantly increased since it has been a target for the development of specific non-steroidal anti-inflammatory drugs. We report that COX-2 expression is up-regulated in phorbol ester (phorbol myristate acetate, PMA)-differentiated human U937 macrophage-like cells stimulated with lipopolysaccharide (LPS), whereas COX-1 is not up-regulated. We show that the LPS-induced up-regulation of COX-2 depends on the activity of the Mg(+2)-dependent phosphatidic acid phosphohydrolase 1 (PAP-1). Inhibition of PAP-1 by bromoenol lactone, propranolol, or ethanol resulted in a decrease in LPS-induced COX-2 mRNA transcript production, COX-2 protein expression, and prostaglandin E(2) release from U937 macrophages. To ensure that these results did not arise because of PMA treatment of the U937 cells, similar experiments were conducted with the P388D(1) cell line, which does not require PMA differentiation. LPS increased the levels of endogenous cellular diacylglycerol (DAG) within 2 min of stimulation. This increase was observed to be sensitive to the PAP-1 inhibitors. Furthermore, phosphatidic acid phosphohydrolase activity assays showed that the bromoenol lactone-sensitive PAP-1 activity was translocated from the cytosolic fraction to the membrane fraction within 2 min of LPS exposure. Finally, DAG add-back experiments demonstrate that LPS-induced COX-2 expression is enhanced by the addition of exogenous DAG.

Estradiol stimulates the biosynthetic pathways of breast cancer cells: detection by metabolic flux analysis

Selective estrogen receptor (ER) modulators are highly successful breast cancer therapies, but they are not effective in patients with ER negative and selective estrogen receptor modulator (SERM)-resistant tumors. Understanding the mechanisms of estrogen-stimulated proliferation may provide a route to design estrogen-independent therapies that would be effective in these patients. In this study, metabolic flux analysis was used to determine the intracellular fluxes that are significantly affected by estradiol stimulation in MCF-7 breast cancer cells. Intracellular fluxes were calculated from nuclear magnetic resonance (NMR)-generated isotope enrichment data and extracellular metabolite fluxes, using a specific flux analysis algorithm. The metabolic pathway model used by the algorithm includes glycolysis, the tricarboxylic acid cycle (TCA cycle), the pentose phosphate pathway, glutamine catabolism, pyruvate carboxylase, and malic enzyme. The pathway model also incorporates mitochondrial compartmentalization and reversible trans-mitochondrial membrane reactions to more accurately describe the role of mitochondria in cancer cell proliferation. Flux results indicate that estradiol significantly increases carbon flow through the pentose phosphate pathway and increases glutamine consumption. In addition, intra-mitochondrial malic enzyme was found to be inactive and the malate-aspartate shuttle (MAS) was only minimally active. The inactivity of these enzymes indicates that glutamine is not oxidized within mitochondria, but is consumed primarily to provide biosynthetic precursors. The excretion of glutamine carbons from the mitochondria has the secondary effect of limiting nicotinamide adenine dinucleotide (NADH) recycle, resulting in NADH buildup in the cytosol and the excretion of lactate. The observed dependence of breast cancer cells on pentose phosphate pathway activity and glutamine consumption for estradiol-stimulated biosynthesis suggests that these pathways may be targets for estrogen-independent breast cancer therapies.

Major advances associated with hormone and growth factor regulation of mammary growth and lactation in dairy cows

In recent years, the number of researchers interested in mammary development and mammary function in dairy animals has declined. More importantly this cadre of workers has come to rely more than ever on scientists focused on and funded by breast cancer interests to provide fundamental mechanistic and basic cellular insights. Philosophically and practically this is a risky path to better understand, manipulate, and control a national resource as important as the dairy cow. The efficiency, resourcefulness, and dedication of dairy scientists have mirrored the actions of many dairy producers but there are limits. Many of the applications of research, use of bovine somatotropin, management of transition cows, estrus synchronization techniques, and so on, are based on decades-old scientific principles. Specific to dairy, do rodents or breast cancer cell lines adequately represent the dairy cow? Will these results inspire the next series of lactation-related dairy improvements? These are key unanswered questions. Study of the classic mammogenic and lactogenic hormones has served dairy scientists well. But there is an exciting, and bewildering universe of growth factors, transcription factors, receptors, intracellular signaling intermediates, and extracellular molecules that must ultimately interact to determine the size of the mature udder and the functional capacity of mammary gland in the lactating cow. We can only hope that enough scientific, fiscal, and resource scraps fall from the biomedical research banquet table to allow dairy-focused mammary gland research to continue.

Mechanisms of Disease: prediction and prevention of breast cancer--cellular and molecular interactions

Breast cancer is the most prevalent female cancer in the world and its incidence is increasing, largely because of the Western lifestyle. There is a need, not only to predict women who will develop the disease, but also to apply drug and lifestyle measures in order to prevent the disease. Current risk prediction models are based on combinations of risk factors and have good predictive but low discriminatory power. New risk prediction methods might come from examination of single nucleotide polymorphisms in several genes or from an increased knowledge of the molecular and cellular biology of the breast, particularly with respect to aberrant gene expression and protein synthesis. These methods might also determine new targets for preventive agents and lifestyle change. Many potential preventive measures are available and some have been successful. New approaches are required, however, not only to prevent the disease but to devise methods for their assessment that do not require very large and expensive clinical trials.

Expression and prognostic relevance of activated extracellular-regulated kinases (ERK1/2) in breast cancer

Extracellular-regulated kinases (ERK1, ERK2) play important roles in the malignant behaviour of breast cancer cells in vitro. In our present study, 148 clinical breast cancer samples (120 cases with follow-up data) were studied for the expression of ERK1, ERK2 and their phosphorylated forms p-ERK1 and p-ERK2 by immunoblotting, and p-ERK1/2 expression in corresponding paraffin sections was analysed by immunohistochemistry. The results were correlated with established clinical and histological prognostic parameters, follow-up data and expression of seven cell-cycle regulatory proteins as well as MMP1, MMP9, PAI-1 and AP-1 transcription factors, which had been analysed before. High p-ERK1 expression as determined by immunoblots correlated significantly with a low frequency of recurrences and infrequent fatal outcome (P=0.007 and 0.008) and was an independent indicator of long relapse-free and overall survival in multivariate analysis. By immunohistochemistry, strong p-ERK staining in tumour cells was associated with early stages (P=0.020), negative nodal status (P=0.003) and long recurrence-free survival (P=0.017). In contrast, expression of the unphosphorylated kinases ERK1 and ERK2 was not associated with clinical and histological prognostic parameters, except a positive correlation with oestrogen receptor status. Comparison with the expression of formerly analysed cell-cycle- and invasion-associated proteins corroborates our conclusion that activation of ERK1 and ERK2 is not associated with enhanced proliferation and invasion of mammary carcinomas.

Transgenic mouse models for the prevention of breast cancer

Breast cancer prevention research has made remarkable progress in the past decade. Much of this progress has come from clinical trials. However, in the future to test the many promising agents that are now available, pre-clinical models of breast cancer are needed. Such models are now available. Useful models include rat and mouse models, particularly, the genetically engineered mice (GEM). Many transgenic mouse models have been generated by manipulating growth factors and their receptors, cell cycle regulators, signal transduction pathways, cellular differentiation, oncogenes and tumor suppressor genes. The transgenes are induced to express in the mouse mammary glands under the control of various transgenic promoters, which have respective characteristics in expression pattern and other biological attributes. These models are providing invaluable insight on the molecular mechanisms of breast tumorigenesis. In this review, we discuss the relative relevance of the most commonly used transgenic mouse models for breast cancer prevention studies, and provide examples of how these transgenic models can be used to conduct cancer prevention research. Due to the multi-factor, multi-step nature of breast cancer, many factors should be incorporated into a valid prevention study. However, many barriers to progress must be overcome, including access to and availability of new cancer preventive drugs, and difficulties in conducting studies of combinations of preventive agents.

Resveratrol and estradiol exert disparate effects on cell migration, cell surface actin structures, and focal adhesion assembly in MDA-MB-231 human breast cancer cells

Resveratrol, a grape polyphenol, is thought to be a cancer preventive, yet its effects on metastatic breast cancer are relatively unknown. Since cancer cell invasion is dependent on cell migration, the chemotactic response of MDA-MB-231 metastatic human breast cancer cells to resveratrol, estradiol (E2), or epidermal growth factor (EGF) was investigated. Resveratrol decreased while E2 and EGF increased directed cell migration. Resveratrol may inhibit cell migration by altering the cytoskeleton. Resveratrol induced a rapid global array of filopodia and decreased focal adhesions and focal adhesion kinase (FAK) activity. E2 or EGF treatment did not affect filopodia extension but increased lamellipodia and associated focal adhesions that are integral for cell migration. Combined resveratrol and E2 treatment resulted in a filopodia and focal adhesion response similar to resveratrol alone. Combined resveratrol and EGF resulted in a lamellipodia and focal adhesion response similar to EGF alone. E2 and to a lesser extent resveratrol increased EGFR activity. The cytoskeletal changes and EGFR activity in response to E2 were blocked by EGFR1 inhibitor indicating that E2 may increase cell migration via crosstalk with EGFR signaling. These data suggest a promotional role for E2 in breast cancer cell migration but an antiestrogenic, preventative role for resveratrol.

Is iodine a gatekeeper of the integrity of the mammary gland?

This paper reviews evidence showing iodine as an antioxidant and antiproliferative agent contributing to the integrity of normal mammary gland. Seaweed is an important dietary component in Asian communities and a rich source of iodine in several chemical forms. The high consumption of this element (25 times more than in Occident) has been associated with the low incidence of benign and cancer breast disease in Japanese women. In animal and human studies, molecular iodine (I(2)) supplementation exerts a suppressive effect on the development and size of both benign and cancer neoplasias. This effect is accompanied by a significant reduction in cellular lipoperoxidation. Iodine, in addition to its incorporation into thyroid hormones, is bound into antiproliferative iodolipids in the thyroid called iodolactones, which may also play a role in the proliferative control of mammary gland. We propose that an I(2) supplement should be considered as an adjuvant in breast cancer therapy.

Designing a Randomized Phase I/II Prostate Cancer Chemoprevention Trial Using 1??-Hydroxy-24-Ethyl-Cholecalciferol, an Analogue of Vitamin D3

Prostate cancer continues to be a significant source of morbidity and mortality among older men. One possible means of reducing its impact on overall health and vitality is via cancer chemoprevention, both in the population that is unaffected but at some risk and in those who have undergone some form of curative therapy after the onset of the disease. Chemoprevention holds significant promise, but large phase III clinical trials evaluating chemopreventive agents in prostate cancer can require vast numbers of enrollees and require the commitment of significant financial resources and time before any therapeutic benefit may become apparent. One technique to shorten the time required for chemoprevention clinical trials is to use surrogate endpoint biomarkers in place of the currently used actual endpoints of cancer incidence or survival. The validation of such surrogate endpoint biomarkers will require small, well-designed phase I and/or II trials to accumulate data on the modulation of the surrogate biomarkers and the endpoints of cancer incidence or survival by the chemopreventive agent. Careful statistical correlation and clinical validation of the data will then allow us to justify the use such surrogates in place of the actual endpoint in large, randomized trials, potentially shortening trial duration, improving financial efficiency, and accelerating approval of the chemopreventive agent. To that end, we first review the theoretical construct of cancer chemoprevention trials with particular reference to prostate cancer. We thereafter describe the design of a small, randomized, double-blinded, placebo-controlled phase I/II clinical trial of an analogue of vitamin D, vitamin D5, which we believe could serve as a model for data accumulation on surrogate biomarkers and correlation with other clinical endpoints.