GATA-3 and the regulation of the mammary luminal cell fate

ZNF503/Zpo2 drives aggressive breast cancer progression by down-regulation of GATA3 expression

The transcription factor GATA3 is the master regulator that drives mammary luminal epithelial cell differentiation and maintains mammary gland homeostasis. Loss of GATA3 is associated with aggressive breast cancer development. We have identified ZNF503/ZEPPO2 zinc-finger elbow-related proline domain protein 2 (ZPO2) as a transcriptional repressor of GATA3 expression and transcriptional activity that induces mammary epithelial cell proliferation and breast cancer development. We show that ZPO2 is recruited to GATA3 promoter in association with ZBTB32 (Repressor of GATA, ROG) and that ZBTB32 is essential for down-regulation of GATA3 via ZPO2. Through this modulation of GATA3 activity, ZPO2 promotes aggressive breast cancer development. Our data provide insight into a mechanism of GATA3 regulation, and identify ZPO2 as a possible candidate gene for future diagnostic and therapeutic strategies.

GATA3 expression and its relationship with clinicopathological parameters in invasive breast carcinomas

GATA3, as a transcription factor, is associated with estrogen receptor (ER) expression and necessary for luminal cell differentiation in mammary glands. Association of GATA3 expression with clinicopathological parameters, molecular subtypes of tumors, disease free survival (DFS) and overall survival (OS) for breast carcinoma patients were evaluated in this study. We immunohistochemically stained GATA3, CK5/6, EGFR, CK14 and vimentin on tissue microarray blocks of 457 invasive breast carcinomas. Tumors are sub-classified as luminal A, luminal B, HER2 expressing, basal-like and null type according to their hormonal status with cerbB2, CK 5/6 and EGFR expressions. Follow-up data for 254 cases were obtained. 215/457 (47%) tumors were GATA3 positive. GATA3 expression was inversely correlated with mitotic count (p<0.0001), nuclear grade (p=0.001), histological grade (p=0.001), tumor necrosis (p=0.001), stromal lymphocytic response (p<0.01), nipple invasion (p=0.01), metastasis (p=0.03), vimentin (p=0.0003), EGFR (p=0.015) and CK14 (p=0.001) expressions; and directly associated with ER (p<0.0001) and progesterone receptor (PR) (p<0.0001) expressions. Luminal A carcinomas had the highest frequency for GATA-3 (140/245), however basal-like carcinomas had the lowest (1/42) (p<0.0001). None of the medullary and metaplastic carcinomas expressed GATA3. GATA3 was associated with good DFS and OS (p=0.001 and p=0.0009) and was an independent prognostic factor for OS. GATA3 expression, regardless of the subtype, may have a prognostic significance for breast carcinomas through its ability to promote the differentiation of luminal progenitor cells.

Pubertal Mammary Gland Development: Elucidation of In Vivo Morphogenesis Using Murine Models

During the past 25 years, the combination of increasingly sophisticated gene targeting technology with transplantation techniques has allowed researchers to address a wide array of questions about postnatal mammary gland development. These in turn have significantly contributed to our knowledge of other branched epithelial structures. This review chapter highlights a selection of the mouse models exhibiting a pubertal mammary gland phenotype with a focus on how they have contributed to our overall understanding of in vivo mammary morphogenesis. We discuss mouse models that have enabled us to assign functions to particular genes and proteins and, more importantly, have determined when and where these factors are required for completion of ductal outgrowth and branch patterning. The reason for the success of the mouse mammary gland model is undoubtedly the suitability of the postnatal mammary gland to experimental manipulation. The gland itself is very amenable to investigation and the combination of genetic modification with accessibility to the tissue has allowed an impressive number of studies to inform biology. Excision of the rudimentary epithelial structure postnatally allows genetically modified tissue to be readily transplanted into wild type stroma or vice versa, and has thus defined the contribution of each compartment to particular phenotypes. Similarly, whole gland transplantation has been used to definitively discern local effects from indirect systemic effects of various growth factors and hormones. While appreciative of the power of these tools and techniques, we are also cognizant of some of their limitations, and we discuss some shortcomings and future strategies that can overcome them.

MiR-573 inhibits prostate cancer metastasis by regulating epithelial-mesenchymal transition

The metastastic cascade is a complex process that is regulated at multiple levels in prostate cancer (PCa). Recent evidence suggests that microRNAs (miRNAs) are involved in PCa metastasis and hold great promise as therapeutic targets. In this study, we found that miR-573 expression is significantly lower in metastatic tissues than matched primary PCa. Its downregulation is correlated with high Gleason score and cancer-related mortality of PCa patients (P = 0.041, Kaplan-Meier analysis). Through gain- and loss-of function experiments, we demonstrated that miR-573 inhibits PCa cell migration, invasion and TGF-β1-induced epithelial-mesenchymal transition (EMT) in vitro and lung metastasis in vivo. Mechanistically, miR573 directly targets the fibroblast growth factor receptor 1 (FGFR1) gene. Knockdown of FGFR1 phenocopies the effects of miR-573 expression on PCa cell invasion, whereas overexpression of FGFR1 partially attenuates the functions of miR-573. Consequently, miR-573 modulates the activation of FGFR1-downstream signaling in response to fibroblast growth factor 2 (FGF2). Importantly, we showed that GATA3 directly increases miR-573 expression, and thus down-regulates FGFR1 expression, EMT and invasion of PCa cells in a miR-573-dependent manner, supporting the involvement of GATA3, miR-573 and FGFR1 in controlling the EMT process during PCa metastasis. Altogether, our findings demonstrate a novel mechanism by which miR-573 modulates EMT and metastasis of PCa cells, and suggest miR-573 as a potential biomarker and/or therapeutic target for PCa management.

Gain- and Loss-of-Function Mutations in the Breast Cancer Gene GATA3 Result in Differential Drug Sensitivity

Patterns of somatic mutations in cancer genes provide information about their functional role in tumourigenesis, and thus indicate their potential for therapeutic exploitation. Yet, the classical distinction between oncogene and tumour suppressor may not always apply. For instance, TP53 has been simultaneously associated with tumour suppressing and promoting activities. Here, we uncover a similar phenomenon for GATA3, a frequently mutated, yet poorly understood, breast cancer gene. We identify two functional classes of frameshift mutations that are associated with distinct expression profiles in tumours, differential disease-free patient survival and gain- and loss-of-function activities in a cell line model. Furthermore, we find an estrogen receptor-independent synthetic lethal interaction between a GATA3 frameshift mutant with an extended C-terminus and the histone methyltransferases G9A and GLP, indicating perturbed epigenetic regulation. Our findings reveal important insights into mutant GATA3 function and breast cancer, provide the first potential therapeutic strategy and suggest that dual tumour suppressive and oncogenic activities are more widespread than previously appreciated.

Cancer is a disease caused by genetic mutations. Mutation patterns are often indicative of a gene’s function as either tumour promoting or tumour suppressive. Here we describe the frequently mutated, but poorly studied, breast cancer gene GATA3 as a rare exception: We discover that two different functional classes of mutations in this gene can lead to either gain- or loss-of-function activities. The most common type of mutations, resulting in an unusually extended protein, is associated with differential gene expression and decreased disease-free survival. This mutant, in contrast to other mutations or the non-mutated protein, renders cells specifically vulnerable to inhibitors of two chromatin-modifying enzymes, the histone methyltransferases G9A and GLP. Our findings shed light on the functional consequences of frequent GATA3 mutations in breast cancer and represent a first lead toward personalised therapy for a large subgroup of breast cancer patients.

GATA3 Expression Is a Poor Prognostic Factor in Soft Tissue Sarcomas

OBJECTIVE

Recent studies have investigated the significance of GATA3 expression in patients with various malignant tumors. However, no previous studies have evaluated the clinicopathological importance of GATA3 expression in soft tissue sarcomas (STS) patients.

METHODS

We evaluated GATA3 expression in 76 STS cases using immunohistochemical analysis, and statistically compared clinicopathological characteristics between GATA3-positive and GATA3-negative cases.

RESULT

GATA3-positive expression was significantly associated with a higher mitotic count (P < 0.0001). Disease-free survival (DFS) of GATA3-positive cases was significantly shorter than that of cases without GATA3 expression (P = 0.0104). Overall survival (OS) of GATA3-positive cases was significantly shorter than that of cases without GATA3 expression (P = 0.0006). GATA3-positive expression was significantly associated with shorter DFS in both univariate analysis (hazard ratio [HR], 2.719; P = 0.012) and multivariate analysis (HR, 2.711; P = 0.014). GATA3-positive expression was also significantly associated with worse OS in both univariate analysis (HR, 5.730; P = 0.0007) and multivariate analysis (HR, 5.789; P = 0.0008).

CONCLUSION

These results indicate that GATA3 is an independent prognostic factor and suggest that evaluation of GATA3 expression might enable more effective clinical follow-up using prognostic stratification of STS patients.

Endosalpingiosis of Axillary Lymph Nodes: A Rare Histopathologic Pitfall with Clinical Relevance for Breast Cancer Staging

Establishment of accurate axillary lymph node status is of essential importance in determining both prognosis and the potential need for adjuvant therapy in patients with invasive breast cancer. Axillary lymph node heterotopias can in some cases result in overdiagnosis of metastatic disease. Nodal endosalpingiosis is perhaps the least commonly reported type of axially lymph node heterotopia. We herein illustrate a case in which second opinion pathologic interpretation combined with ancillary immunohistochemical studies allowed for a specific diagnosis of axillary nodal müllerian-type inclusions, confirming ypN0 staging and resulting in appropriate disease management and prognostication.

S100A8/A9 is associated with estrogen receptor loss in breast cancer

S100A8 and S100A9 are calcium-binding proteins that are secreted primarily by granulocytes and monocytes, and are upregulated during the inflammatory response. S100A8 and S100A9 have been identified to be expressed by epithelial cells involved in malignancy. In the present study, the transcriptional levels of S100A8 and S100A9 were investigated in various subtypes of breast cancer (BC), and the correlation with estrogen receptor 1 (ESR1) and GATA binding protein 3 (GATA3) gene expression was evaluated using microarray datasets. The expression of S100A8 and S100A9 in BC cells was assessed by reverse transcription-polymerase chain reaction (RT-PCR). The regulation of ESR1 and GATA3 by administration of recombinant S100A8/A9 was examined in the BC MCF-7 cell line using quantitative (q)PCR. The association between S100A8 and S100A9 and overall survival (OS) was investigated in GeneChip® data of BC. The expression levels of S100A8 and S100A9 were higher in human epidermal growth factor receptor 2 (Her2)-amplified and basal-like BC. The messenger (m)RNA levels of S100A8 and S100A9 were inversely correlated with ESR1 and GATA3 expression. S100A8/A9 induced a 10-fold decrease in the mRNA levels of ESR1 in MCF-7 cells. Poor OS was associated with high expression levels of S100A9, but not with high expression levels of S100A8 in BC. In conclusion, strong expression and secretion of S100A8/A9 may be associated with the loss of estrogen receptor in BC, and may be involved in the poor prognosis of Her2+/basal-like subtypes of BC.

The role of GATA3 in breast carcinomas: a review

GATA3 is a zinc-binding transcription factor that regulates the differentiation of many human tissue types, including the mammary gland. In surgical pathology, immunohistochemistry for GATA3 is largely used to support urothelial or breast origin in a carcinoma of unknown origin. GATA3 is sensitive but not entirely specific in this setting. Although GATA3 labeling is highest in estrogen receptor-positive carcinomas, it also labels estrogen receptor-negative carcinomas and thus has particular diagnostic utility in the setting of triple-negative breast carcinomas, which are typically negative for other mammary-specific markers.

GATA-binding protein 3 enhances the utility of gross cystic disease fluid protein-15 and mammaglobin A in triple-negative breast cancer by immunohistochemistry

AIMS

We have demonstrated previously that gross cystic disease fluid protein-15 (GCDFP-15) and mammaglobin A (MAM) are of limited utility in triple-negative breast cancer (TNBC). GATA-binding protein 3 (GATA-3) is an emerging breast-associated immunohistochemical (IHC) marker with limited data in TNBC. Here, we examined GATA-3 expression in TNBC in comparison with GCDFP-15 and MAM.

METHODS AND RESULTS

We studied GATA-3, GCDFP-15 and MAM IHC expression in 62 primary and 68 metastatic TNBCs. In primary TNBCs, GATA-3 staining was observed in 25 cases (40%), including 16 cases that were negative for GCDFP-15 and MAM. In metastatic TNBCs, GATA-3 staining was observed in 30 cases (44%), including 16 cases that were negative for GCDFP-15 and MAM. The expression frequency of any of the markers was 56% in primary and 62% in metastatic TNBCs. However, when focal staining was excluded, the expression frequency of any marker dropped to 31% and 44%, respectively.

CONCLUSION

GATA-3 is expressed at a higher frequency by IHC in TNBC compared to GCDFP-15 and MAM, although the tissue specificity of the latter markers may be superior. When evaluating a triple-negative tumour, including GATA-3 in a panel of markers may increase the diagnostic accuracy for tissue origin in the appropriate clinical setting.

New and emerging factors in tumorigenesis: an overview

This article provides an overview of the genes and cellular processes that have emerged recently as new key factors in tumorigenesis. We review these in the context of three broad categories. First, genome-scale sequencing studies have revealed a set of frequently mutated genes in cancer. Genes that are mutated in >5% of all cancers across tissue types are discussed, with a highlighted focus on the two most frequently mutated genes, TP53 and PIK3CA. Second, the mechanisms of resistance to targeted therapy are reviewed. These include acquired resistance under targeted therapy selection owing to mutations and amplification of genes in the same or parallel signaling pathways. Importantly, sequencing of primary tumors has revealed that therapy-resistant clones already exist prior to targeted therapy, demonstrating that tumor heterogeneity in primary tumors confers a mechanism for inherent therapy resistance. Third, “metastasis-specific genes”, or rather lack thereof, are discussed. While many genes have been shown to be capable of promoting metastasis in experimental systems, no common genetic alterations have been identified specific to metastatic lesions. Rather, the same gene mutations frequently found in primary tumors are also found prevalent in metastases, suggesting that the genes that drive tumorigenesis may also drive metastasis. In this light, an emerging view of metastatic progression is discussed. Collectively, these recent advances in cancer research have refined our knowledge on cancer etiology and progression but also present challenges that will require innovative new approaches to treat and manage cancer.

KAT6A, a chromatin modifier from the 8p11-p12 amplicon is a candidate oncogene in luminal breast cancer

The chromosome 8p11-p12 amplicon is present in 12% to 15% of breast cancers, resulting in an increase in copy number and expression of several chromatin modifiers in these tumors, including KAT6A. Previous analyses in SUM-52 breast cancer cells showed amplification and overexpression of KAT6A, and subsequent RNAi screening identified KAT6A as a potential driving oncogene. KAT6A is a histone acetyltransferase previously identified as a fusion partner with CREB binding protein in acute myeloid leukemia. Knockdown of KAT6A in SUM-52 cells, a luminal breast cancer cell line harboring the amplicon, resulted in reduced growth rate compared to non-silencing controls and profound loss of clonogenic capacity both in mono-layer and in soft agar. The normal cell line MCF10A, however, did not exhibit slower growth with knockdown of KAT6A. SUM-52 cells with KAT6A knockdown formed fewer mammospheres in culture compared to controls, suggesting a possible role for KAT6A in self-renewal. Previous data from our laboratory identified FGFR2 as a driving oncogene in SUM-52 cells. The colony forming efficiency of SUM-52 KAT6A knockdown cells in the presence of FGFR inhibition was significantly reduced compared to cells with KAT6A knockdown only. These data suggest that KAT6A may be a novel oncogene in breast cancers bearing the 8p11-p12 amplicon. While there are other putative oncogenes in the amplicon, the identification of KAT6A as a driving oncogene suggests that chromatin-modifying enzymes are a key class of oncogenes in these cancers, and play an important role in the selection of this amplicon in luminal B breast cancers.

Hormone-sensing mammary epithelial progenitors: emerging identity and hormonal regulation

The hormone-sensing mammary epithelial cell (HS-MEC-expressing oestrogen receptor-alpha (ERα) and progesterone receptor (PGR)) is often represented as being terminally differentiated and lacking significant progenitor activity after puberty. Therefore while able to profoundly influence the proliferation and function of other MEC populations, HS-MECs are purported not to respond to sex hormone signals by engaging in significant cell proliferation during adulthood. This is a convenient and practical simplification that overshadows the sublime, and potentially critical, phenotypic plasticity found within the adult HS-MEC population. This concept is exemplified by the large proportion (~80 %) of human breast cancers expressing PGR and/or ERα, demonstrating that HS-MECs clearly proliferate in the context of breast cancer. Understanding how HS-MEC proliferation and differentiation is driven could be key to unraveling the mechanisms behind uncontrolled HS-MEC proliferation associated with ERα- and/or PGR-positive breast cancers. Herein we review evidence for the existence of a HS-MEC progenitor and the emerging plasticity of the HS-MEC population in general. This is followed by an analysis of hormones other than oestrogen and progesterone that are able to influence HS-MEC proliferation and differentiation: androgens, prolactin and transforming growth factor-beta1.

Inferring regulatory element landscapes and transcription factor networks from cancer methylomes

Recent studies indicate that DNA methylation can be used to identify transcriptional enhancers, but no systematic approach has been developed for genome-wide identification and analysis of enhancers based on DNA methylation. We describe ELMER (Enhancer Linking by Methylation/Expression Relationships), an R-based tool that uses DNA methylation to identify enhancers and correlates enhancer state with expression of nearby genes to identify transcriptional targets. Transcription factor motif analysis of enhancers is coupled with expression analysis of transcription factors to infer upstream regulators. Using ELMER, we investigated more than 2,000 tumor samples from The Cancer Genome Atlas. We identified networks regulated by known cancer drivers such as GATA3 and FOXA1 (breast cancer), SOX17 and FOXA2 (endometrial cancer), and NFE2L2, SOX2, and TP63 (squamous cell lung cancer). We also identified novel networks with prognostic associations, including RUNX1 in kidney cancer. We propose ELMER as a powerful new paradigm for understanding the cis-regulatory interface between cancer-associated transcription factors and their functional target genes.

RARRES3 suppresses breast cancer lung metastasis by regulating adhesion and differentiation

In estrogen receptor-negative breast cancer patients, metastatic relapse usually occurs in the lung and is responsible for the fatal outcome of the disease. Thus, a better understanding of the biology of metastasis is needed. In particular, biomarkers to identify patients that are at risk of lung metastasis could open the avenue for new therapeutic opportunities. Here we characterize the biological activity of RARRES3, a new metastasis suppressor gene whose reduced expression in the primary breast tumors identifies a subgroup of patients more likely to develop lung metastasis. We show that RARRES3 downregulation engages metastasis-initiating capabilities by facilitating adhesion of the tumor cells to the lung parenchyma. In addition, impaired tumor cell differentiation due to the loss of RARRES3 phospholipase A1/A2 activity also contributes to lung metastasis. Our results establish RARRES3 downregulation as a potential biomarker to identify patients at high risk of lung metastasis who might benefit from a differentiation treatment in the adjuvant programme.

Progesterone receptor activation downregulates GATA3 by transcriptional repression and increased protein turnover promoting breast tumor growth

Introduction

The transcription factor GATA3 is involved in mammary gland development and is crucial for the maintenance of the differentiated status of luminal epithelial cells. The role of GATA3 in breast cancer as a tumor suppressor has been established, although insights into the mechanism of GATA3 expression loss are still required.

Methods

Chromatin immunoprecipitation assays were conducted to study progestin modulation of recruitment of transcription factors to GATA3 promoter. We performed western blot and reverse RT-qPCR experiments to explore progestin regulation of GATA3 protein and mRNA expression respectively. Confocal microscopy and in vitro phosphorylation studies were conducted to examine progestin capacity to induce GATA3 serine phosphorylation in its 308 residue. GATA3 participation in progestin-induced breast cancer growth was addressed in in vitro proliferation and in vivo tumor growth experiments.

Results

In this study, we demonstrate that progestin-activated progesterone receptor (PR) reduces GATA3 expression through regulation at the transcriptional and post-translational levels in breast cancer cells. In the former mechanism, the histone methyltransferase enhancer of zeste homolog 2 is co-recruited with activated PR to a putative progesterone response element in the GATA3 proximal promoter, increasing H3K27me3 levels and inducing chromatin compaction, resulting in decreased GATA3 mRNA levels. This transcriptional regulation is coupled with increased GATA3 protein turnover through progestin-induced GATA3 phosphorylation at serine 308 followed by 26S proteasome-mediated degradation. Both molecular mechanisms converge to accomplish decreased GATA3 expression levels in breast cancer cells upon PR activation. In addition, we demonstrated that decreased GATA3 levels are required for progestin-induced upregulation of cyclin A2, which mediates the G1 to S phase transition of the cell cycle and was reported to be associated with poor prognosis in breast cancer. Finally, we showed that downregulation of GATA3 is required for progestin stimulation of both in vitro cell proliferation and in vivo tumor growth.

Conclusions

In the present study, we reveal that progestin-induced PR activation leads to loss of GATA3 expression in breast cancer cells through transcriptional and post-translational regulation. Importantly, we demonstrate that GATA3 downregulation is required for progestin-induced upregulation of cyclin A2 and for progestin-induced in vitro and in vivo breast cancer cell growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0491-x) contains supplementary material, which is available to authorized users.

Absent, small or homeotic 2-like protein (ASH2L) enhances the transcription of the estrogen receptor α gene through GATA-binding protein 3 (GATA3)

ASH2L is a component of MLL complexes that confer H3K4 trimethylation. The ASH2L gene is located at 8q11-12, which is often amplified in breast cancers. We found that increased ASH2L expression, which can result from gene amplification, is often correlated with increased ERα expression in both breast cancer cell lines and primary breast cancers. Forced expression of ASH2L induced ERα expression in mammary epithelial cells, whereas depletion of ASH2L suppressed ERα expression in breast cancer cells. To understand the mechanism by which ASH2L regulates ERα expression, we identified GATA3 as the binding protein of ASH2L. ASH2L was shown to potentiate the transcriptional activity of GATA3. ASH2L was recruited to the enhancer of the ERα gene through GATA3 to promote ERα transcription. This study established that ASH2L enhances ERα expression as a coactivator of GATA3 in breast cancers.

Estrogen receptor coregulators and pioneer factors: the orchestrators of mammary gland cell fate and development

The steroid hormone, 17β-estradiol (E2), plays critical role in various cellular processes such as cell proliferation, differentiation, migration and apoptosis, and is essential for reproduction and mammary gland development. E2 actions are mediated by two classical nuclear hormone receptors, estrogen receptor α and β (ERs). The activity of ERs depends on the coordinated activity of ligand binding, post-translational modifications (PTMs), and importantly the interaction with their partner proteins called “coregulators.” Because coregulators are proved to be crucial for ER transcriptional activity, and majority of breast cancers are ERα positive, an increased interest in the field has led to the identification of a large number of coregulators. In the last decade, gene knockout studies using mouse models provided impetus to our further understanding of the role of these coregulators in mammary gland development. Several coregulators appear to be critical for terminal end bud (TEB) formation, ductal branching and alveologenesis during mammary gland development. The emerging studies support that, coregulators along with the other ER partner proteins called “pioneer factors” together contribute significantly to E2 signaling and mammary cell fate. This review discusses emerging themes in coregulator and pioneer factor mediated action on ER functions, in particular their role in mammary gland cell fate and development.

Family-specific, novel, deleterious germline variants provide a rich resource to identify genetic predispositions for BRCAx familial breast cancer

Background

Genetic predisposition is the primary risk factor for familial breast cancer. For the majority of familial breast cancer, however, the genetic predispositions remain unknown. All newly identified predispositions occur rarely in disease population, and the unknown genetic predispositions are estimated to reach up to total thousands. Family unit is the basic structure of genetics. Because it is an autosomal dominant disease, individuals with a history of familial breast cancer must carry the same genetic predisposition across generations. Therefore, focusing on the cases in lineages of familial breast cancer, rather than pooled cases in disease population, is expected to provide high probability to identify the genetic predisposition for each family.

Methods

In this study, we tested genetic predispositions by analyzing the family-specific variants in familial breast cancer. Using exome sequencing, we analyzed three families and 22 probands with BRCAx (BRCA-negative) familial breast cancer.

Results

We observed the presence of family-specific, novel, deleterious germline variants in each family. Of the germline variants identified, many were shared between the disease-affected family members of the same family but not found in different families, which have their own specific variants. Certain variants are putative deleterious genetic predispositions damaging functionally important genes involved in DNA replication and damaging repair, tumor suppression, signal transduction, and phosphorylation.

Conclusions

Our study demonstrates that the predispositions for many BRCAx familial breast cancer families can lie in each disease family. The application of a family-focused approach has the potential to detect many new predispositions.

Global analysis of ZNF217 chromatin occupancy in the breast cancer cell genome reveals an association with ERalpha

BACKGROUND

The ZNF217 gene, encoding a C2H2 zinc finger protein, is located at 20q13 and found amplified and overexpressed in greater than 20% of breast tumors. Current studies indicate ZNF217 drives tumorigenesis, yet the regulatory mechanisms of ZNF217 are largely unknown. Because ZNF217 associates with chromatin modifying enzymes, we postulate that ZNF217 functions to regulate specific gene signaling networks. Here, we present a large-scale functional genomic analysis of ZNF217, which provides insights into the regulatory role of ZNF217 in MCF7 breast cancer cells.

RESULTS

ChIP-seq analysis reveals that the majority of ZNF217 binding sites are located at distal regulatory regions associated with the chromatin marks H3K27ac and H3K4me1. Analysis of ChIP-seq transcription factor binding sites shows clustering of ZNF217 with FOXA1, GATA3 and ERalpha binding sites, supported by the enrichment of corresponding motifs for the ERalpha-associated cis-regulatory sequences. ERalpha expression highly correlates with ZNF217 in lysates from breast tumors (n = 15), and ERalpha co-precipitates ZNF217 and its binding partner CtBP2 from nuclear extracts. Transcriptome profiling following ZNF217 depletion identifies differentially expressed genes co-bound by ZNF217 and ERalpha; gene ontology suggests a role for ZNF217-ERalpha in expression programs associated with ER+ breast cancer studies found in the Molecular Signature Database. Data-mining of expression data from breast cancer patients correlates ZNF217 with reduced overall survival.

CONCLUSIONS

Our genome-wide ZNF217 data suggests a functional role for ZNF217 at ERalpha target genes. Future studies will investigate whether ZNF217 expression contributes to aberrant ERalpha regulatory events in ER+ breast cancer and hormone resistance.

JARID1B is a luminal lineage-driving oncogene in breast cancer

Recurrent mutations in histone-modifying enzymes imply key roles in tumorigenesis, yet their functional relevance is largely unknown. Here, we show that JARID1B, encoding a histone H3 lysine 4 (H3K4) demethylase, is frequently amplified and overexpressed in luminal breast tumors and a somatic mutation in a basal-like breast cancer results in the gain of unique chromatin binding and luminal expression and splicing patterns. Downregulation of JARID1B in luminal cells induces basal genes expression and growth arrest, which is rescued by TGFβ pathway inhibitors. Integrated JARID1B chromatin binding, H3K4 methylation, and expression profiles suggest a key function for JARID1B in luminal cell-specific expression programs. High luminal JARID1B activity is associated with poor outcome in patients with hormone receptor-positive breast tumors.

Nuclear CSPP1 expression defined subtypes of basal-like breast cancer

BACKGROUND

The multi-exon CSPP1 gene, encoding for centrosome and microtubule-associated proteins involved in ciliogenesis and cell division, is a candidate oncogene in luminal breast cancer but expression of CSPP1 proteins remained unexplored.

METHODS

CSPP1 gene and protein expression was examined in normal mammary tissue, human breast cancer cell lines, and primary breast cancer biopsies from two patient cohorts. Cell type and epitope-dependent subcellular-specific CSPP1 staining pattern in normal mammary gland epithelium and cancer biopsies were correlated to molecular and clinical parameters.

RESULTS

A novel, nuclear localised CSPP1 isoform was exclusively detected in luminal epithelial cells, whereas cytoplasmic CSPP-L was generally expressed in normal mammary epithelium. Luminal cell-related nuclear CSPP1 expression was preserved in type-matched cell lines and carcinomas, and correlated to gene copy number and mRNA expression. In contrast, basal-like carcinomas displayed generally lower CSPP1 mRNA expression. Yet, a subgroup of basal-like breast carcinomas depicted nuclear CSPP1 expression, displayed luminal traits, and differed from nuclear CSPP1 devoid counterparts in expression of eight genes. Eight-gene signature defined groups of basal-like tumours from an independent cohort showed significant differences in survival.

CONCLUSIONS

Differential expression of a nuclear CSPP1 isoform identified biologically and clinically distinct subgroups of basal-like breast carcinoma.

p130Cas alters the differentiation potential of mammary luminal progenitors by deregulating c-Kit activity

It has recently been proposed that defective differentiation of mammary luminal progenitors predisposes to basal-like breast cancer. However, the molecular and cellular mechanisms involved are still unclear. Here, we describe that the adaptor protein p130Cas is a crucial regulator of mouse mammary epithelial cell (MMEC) differentiation. Using a transgenic mouse model, we show that forced p130Cas overexpression in the luminal progenitor cell compartment results in the expansion of luminal cells, which aberrantly display basal cell features and reduced differentiation in response to lactogenic stimuli. Interestingly, MMECs overexpressing p130Cas exhibit hyperactivation of the tyrosine kinase receptor c-Kit. In addition, we demonstrate that the constitutive c-Kit activation alone mimics p130Cas overexpression, whereas c-Kit downregulation is sufficient to re-establish proper differentiation of p130Cas overexpressing cells. Overall, our data indicate that high levels of p130Cas, via abnormal c-Kit activation, promote mammary luminal cell plasticity, thus providing the conditions for the development of basal-like breast cancer. Consistently, p130Cas is overexpressed in human triple-negative breast cancer, further suggesting that p130Cas upregulation may be a priming event for the onset of basal-like breast cancer.

Unraveling the regulatory connections between two controllers of breast cancer cell fate

Estrogen receptor alpha (ERα) expression is critical for breast cancer classification, high ERα expression being associated with better prognosis. ERα levels strongly correlate with that of GATA binding protein 3 (GATA3), a major regulator of ERα expression. However, the mechanistic details of ERα-GATA3 regulation remain incompletely understood. Here we combine mathematical modeling with perturbation experiments to unravel the nature of regulatory connections in the ERα-GATA3 network. Through cell population-average, single-cell and single-nucleus measurements, we show that the cross-regulation between ERα and GATA3 amounts to overall negative feedback. Further, mathematical modeling reveals that GATA3 positively regulates its own expression and that ERα autoregulation is most likely absent. Lastly, we show that the two cross-regulatory connections in the ERα-GATA3 negative feedback network decrease the noise in ERα or GATA3 expression. This may ensure robust cell fate maintenance in the face of intracellular and environmental fluctuations, contributing to tissue homeostasis in normal conditions, but also to the maintenance of pathogenic states during cancer progression.

Low trichorhinophalangeal syndrome 1 gene transcript levels in basal-like breast cancer associate with mesenchymal-to-epithelial transition

OBJECTIVE

To investigate trichorhinophalangeal syndrome 1 gene (TRPS-1) expression patterns in different subtypes of breast cancer and its correlations with other genes and survival using microarray data sets.

METHODS

The transcripts of TRPS-1 and its role in survival in breast cancer were analyzed using published microarray data sets#x02014;Netherlands Cancer Institute (NKI) cohort and Wang cohort.

RESULTS

TRPS-1 expression was lower in basal-like breast cancer. The mRNA levels of TRPS-1 negatively correlated with Slug (Pearson correlation coefficient=-0.1366, P=0.0189 in NKI data set and Pearson correlation coefficient=-0.1571, P=0.0078 in Wang data set), FOXC1 (Pearson correlation coefficient=-0.1211, P=0.0376 in NKI data set and Pearson correlation coefficient=-0.1709, P=0.0037 in Wang data set), and CXCL1 (Pearson correlation coefficient=-0.1197, P=0.0399 in NKI data set and Pearson correlation coefficient=-0.3436, P<0.0001 in Wang data set), but positively correlated with BRCA1 (Pearson correlation coefficient=0.1728, P=0.0029 in NKI data set and Pearson correlation coefficient=0.1805, P=0.0022 in Wang data set). Low TRPS-1 expression associated with poor overall survival (hazard ratio 1.79, 95% CI of ratio 0.9894 to 3.238, P=0.054) and relapse-free survival (hazard ratio 1.913, 95% CI of ratio 1.159 to 3.156, P<0.05). The low TRPS-1 mRNA levels predicted poor outcome in breast cancer patients by the 70-gene signature.

CONCLUSION

The strong expression of TRPS-1 may serve as a good prognostic marker in breast cancer.

GATA3 transcription factor abrogates Smad4 transcription factor-mediated fascin overexpression, invadopodium formation, and breast cancer cell invasion

Transforming growth factor β (TGFβ) is a potent and context-dependent regulator of tumor progression. TGFβ promotes the lung metastasis of basal-like (but not the luminal-like) breast cancer. Here, we demonstrated that fascin, a pro-metastasis actin bundling protein, was a direct target of the canonical TGFβ-Smad4 signaling pathway in basal-like breast cancer cells. TGFβ and Smad4 induced fascin overexpression by directly binding to a Smad binding element on the fascin promoter. We identified GATA3, a transcription factor crucial for mammary gland morphogenesis and luminal differentiation, as a negative regulator of TGFβ- and Smad4-induced fascin overexpression. When ectopically expressed in basal-like breast cancer cells, GATA-3 abrogated TGFβ- and Smad4-mediated overexpression of fascin and other TGFβ response genes, invadopodium formation, cell migration, and invasion, suggesting suppression of the canonical TGFβ-Smad signaling axis. Mechanistically, GATA3 abrogated the canonical TGFβ-Smad signaling by abolishing interactions between Smad4 and its DNA binding elements, potentially through physical interactions between the N-terminal of GATA3 and Smad3/4 proteins. Our findings provide mechanistic insight into how TGFβ-mediated cell motility and invasiveness are differentially regulated in breast cancer.

Mechanisms that link the oncogenic epithelial-mesenchymal transition to suppression of anoikis

The oncogenic epithelial-mesenchymal transition (EMT) contributes to tumor progression in various context-dependent ways, including increased metastatic potential, expansion of cancer stem cell subpopulations, chemo-resistance and disease recurrence. One of the hallmarks of EMT is resistance of tumor cells to anoikis. This resistance contributes to metastasis and is a defining property not only of EMT but also of cancer stem cells. Here, we review the mechanistic coupling between EMT and resistance to anoikis. The discussion focuses on several key aspects. First, we provide an update on new pathways that lead from the loss of E-cadherin to anoikis resistance. We then discuss the relevance of transcription factors that are crucial in wound healing in the context of oncogenic EMT. Next, we explore the consequences of the breakdown of cell-polarity complexes upon anoikis sensitivity, through the Hippo, Wnt and transforming growth factor β (TGF-β) pathways, emphasizing points of crossregulation. Finally, we summarize the direct regulation of cell survival genes through EMT-inducing transcription factors, and the roles of the tyrosine kinases focal adhesion kinase (FAK) and TrkB neurotrophin receptor in EMT-related regulation of anoikis. Emerging from these studies are unifying principles that will lead to improvements in cancer therapy by reprogramming sensitivity of anoikis.

GATA-3 is down-regulated in patients with clear cell renal carcinoma

BACKGROUND

GATA-3 is a transcription factor involved in human growth and development. Recent studies found its association with breast cancer, however, its expression profile in renal cell carcinoma (RCC) has not been investigated.

MATERIAL AND METHOD

The study included 35 patients submitted to radical nephrectomy with confirmed pathological diagnosis of RCC. Normal control kidney tissues were obtained from 25 living kidney donors and tissues were biopsied before implantation. The majority of RCC samples were diagnosed as clear cell renal cell carcinoma (94.3%) except for 1 case of papillary RCC and 1 case of collecting duct carcinoma. GATA-3 expression was evaluated by quantitative PCR and Western blotting (WB) in RCC samples and normal kidneys respectively, immunohistochemical staining was performed as well. Meanwhile, the GATA-3 expression in two cancer cell lines (786-O, ACHN) and normal kidney epithelial cells (HK-2) was detected by PCR and WB. In addition, renal cancer cells and HK-2 cells were cultivated and detected by confocal microscopy for the exact intra-cellular localization of GATA-3.

RESULTS

Data showed a significant down-regulation of GATA-3 expression present in neoplastic tissues compared with normal tissues; similarly, GATA-3 was significantly attenuated in all renal cancer cell lines compared with normal HK-2 cells. Confocal displayed a strong cytoplasmic immno-fluorescence activity of GATA-3 with peri-nuclear zone in HK-2, whereas the intensity in cancer cells was markedly weaker than that of HK-2.

CONCLUSIONS

In summary, our present study clarifies that the aberrant expression profile of GATA-3 in human RCC is possibly involved with tumorigenesis, and the complicated mechanism is worthy of further investigation.

Transcription factor interplay in T helper cell differentiation

The differentiation of CD4 helper T cells into specialized effector lineages has provided a powerful model for understanding immune cell differentiation. Distinct lineages have been defined by differential expression of signature cytokines and the lineage-specifying transcription factors necessary and sufficient for their production. The traditional paradigm of differentiation towards Th1 and Th2 subtypes driven by T-bet and GATA3, respectively, has been extended to incorporate additional T cell lineages and transcriptional regulators. Technological advances have expanded our view of these lineage-specifying transcription factors to the whole genome and revealed unexpected interplay between them. From these data, it is becoming clear that lineage specification is more complex and plastic than previous models might have suggested. Here, we present an overview of the different forms of transcription factor interplay that have been identified and how T cell phenotypes arise as a product of this interplay within complex regulatory networks. We also suggest experimental strategies that will provide further insight into the mechanisms that underlie T cell lineage specification and plasticity.

GATA3 expression in breast carcinoma: utility in triple-negative, sarcomatoid, and metastatic carcinomas

GATA3 plays an integral role in breast luminal cell differentiation and is implicated in breast cancer progression. GATA3 immunohistochemistry is a useful marker of breast cancer; however, its use in specific subtypes is unclear. Here, we evaluate GATA3 expression in 86 invasive ductal carcinomas including triple-negative, Her-2, and luminal subtypes, in addition to 13 metaplastic carcinomas and in 34 fibroepithelial neoplasms. In addition, we report GATA3 expression in matched primary and metastatic breast carcinomas in 30 patients with known estrogen receptor (ER), progesterone receptor (PR), and Her-2 status, including 5 with ER and/or PR loss from primary to metastasis. Tissue microarrays containing 5 to 10 cores per tumor were stained for GATA3, scored as follows: 0 (0-5%), 1+ (6%-25%), 2+ (26%-50%), 3+ (51%-75%), and 4+ (>75%). GATA3 labeling was seen in 67% (66/99) of primary ductal carcinomas including 43% of triple-negative and 54% of metaplastic carcinomas. In contrast, stromal GATA3 labeling was seen in only 1 fibroepithelial neoplasm. GATA3 labeling was seen in 90% (27/30) of primary breast carcinomas in the paired cohort, including 67% of triple-negative carcinomas. GATA3 labeling was overwhelmingly maintained in paired metastases. Notably, GATA3 was maintained in all "luminal loss" metastases, which showed ER and/or PR loss. In conclusion, GATA3 expression is maintained between matched primary and metastatic carcinomas including ER-negative cases. GATA3 can be particularly useful as a marker for metastatic breast carcinoma, especially triple-negative and metaplastic carcinomas, which lack specific markers of mammary origin. Finally, GATA3 labeling may help distinguish metaplastic carcinoma from malignant phyllodes tumors.

Master regulators of FGFR2 signalling and breast cancer risk

The fibroblast growth factor receptor 2 (FGFR2) locus has been consistently identified as a breast cancer risk locus in independent genome-wide association studies. However, the molecular mechanisms underlying FGFR2-mediated risk are still unknown. Using model systems we show that FGFR2-regulated genes are preferentially linked to breast cancer risk loci in expression quantitative trait loci analysis, supporting the concept that risk genes cluster in pathways. Using a network derived from 2,000 transcriptional profiles we identify SPDEF, ERα, FOXA1, GATA3 and PTTG1 as master regulators of fibroblast growth factor receptor 2 signalling, and show that ERα occupancy responds to fibroblast growth factor receptor 2 signalling. Our results indicate that ERα, FOXA1 and GATA3 contribute to the regulation of breast cancer susceptibility genes, which is consistent with the effects of anti-oestrogen treatment in breast cancer prevention, and suggest that fibroblast growth factor receptor 2 signalling has an important role in mediating breast cancer risk.

Utility of GATA3 immunohistochemistry in differentiating urothelial carcinoma from prostate adenocarcinoma and squamous cell carcinomas of the uterine cervix, anus, and lung

Distinguishing invasive high-grade urothelial carcinoma (UC) from other carcinomas occurring in the genitourinary tract may be difficult. The differential diagnosis includes high-grade prostatic adenocarcinoma, spread from an anal squamous cell carcinoma (SCC), or spread from a uterine cervical SCC. In terms of metastatic UC, the most common problem is differentiating spread of UC to the lung from a primary pulmonary SCC. Immunohistochemical analysis (IHC) for GATA binding protein 3 (GATA3), thrombomodulin (THROMBO), and uroplakin III was performed on a tissue microarray (TMA) containing 35 cases of invasive high-grade UC. GATA3 IHC was also performed on TMAs containing 38 high-grade (Gleason score ≥8) prostatic adenocarcinomas, representative tissue sections from 15 invasive anal SCCs, representative tissue sections from 19 invasive cervical SCCs, and TMAs with 12 invasive cervical carcinomas of the cervix [SCC (n=10), SCC with neuroendocrine features (n=1), and adenosquamous carcinoma (n=1)]. In addition, GATA3 IHC was performed on representative tissue sections from 15 pulmonary UC metastases and a TMA with 25 SCCs of the lung and 5 pulmonary non-small cell carcinomas with squamous features. GATA3, THROMBO, and uroplakin III were positive in 28 (80%), 22 (63%), and 21 (60%) cases of high-grade UC, respectively. All cases of GATA3-positive staining were nonfocal; 25 (89%) cases demonstrated moderate to strong staining, and 3 (11%) demonstrated weak staining. Of the 7 cases that failed to express GATA3, 5 were positive for THROMBO and/or uroplakin III, whereas 2 were negative for all 3 markers. None of the 38 high-grade prostatic adenocarcinomas was positive for GATA3. Weak GATA3 staining was present in occasional basal cells of benign prostate glands, in a few benign atrophic glands, and in urothelial metaplasia. Of the 15 cases of anal SCCs, 2 (7%) cases showed focal weak staining, and 1 (3%) showed focal moderate staining. Weak staining was also rarely observed in the benign anal squamous epithelium. Of the 31 uterine cervical carcinomas, 6 (19%) showed weak GATA3 staining (3 nonfocal and 3 focal), and 2 (6%) demonstrated focal moderate staining. Twelve (80%) of the metastatic UCs to the lung were positive for GATA3, with 11 cases showing diffuse moderate or strong staining and 1 case showing focal moderate staining. None of the pulmonary SCCs or non-small cell carcinomas with squamous features was GATA3 positive. GATA3 IHC is a sensitive marker for UC, and positive staining in UC is typically nonfocal and moderate or strong in intensity. GATA3 is also highly specific in excluding high-grade prostate adenocarcinoma. Although some cervical and anal SCCs can be GATA3 positive, unlike in UC, staining is more commonly focal and weak. GATA3 is also a useful maker when diagnosing metastatic UC to the lung.

Clinicopathological analysis of GATA3-positive breast cancers with special reference to response to neoadjuvant chemotherapy

BACKGROUND

The aim of this study was to investigate the clinicopathological characteristics of GATA binding protein 3 (GATA3)-positive breast cancers as well as the association of GATA3 expression with response to chemotherapy.

PATIENTS AND METHODS

Tumor specimens obtained before neoadjuvant chemotherapy [paclitaxel followed by 5-fluorouracil/epirubicin/cyclophosphamide)] from breast cancer patients (n = 130) were subjected to immunohistochemical and mutational analysis of GATA3 and DNA microarray gene expression analysis for intrinsic subtyping.

RESULTS

Seventy-four tumors (57%) were immunohistochemically positive for GATA3. GATA3-positive tumors were significantly more likely to be lobular cancer, estrogen receptor (ER)-positive, progesterone receptor (PgR)-positive, Ki67-negative, and luminal A tumors. Somatic mutations were found in only three tumors. Pathological complete response (pCR) was observed in 8 (11%) GATA3-positive tumors and in 22 (39%) GATA3-negative tumors. multivariate analysis showed that tumor size, human epidermal growth factor receptor 2 (her2), and gata3 were independent predictors of pcr.

CONCLUSIONS

GATA3-positive breast cancers showed luminal differentiation characterized by high ER expression and were mostly classified as luminal-type tumors following intrinsic subtyping. Interestingly, GATA3 was an independent predictor of response to chemotherapy, suggesting that GATA3 might be clinically useful as a predictor of a poor response to chemotherapy.

Cooperating transcription factors mediate the function of estrogen receptor

Estrogen receptor (ER) is a hormone-regulated transcription factor that controls cell division and differentiation in the ovary, breast, and uterus. The expression of ER is a common feature of the majority of breast cancers, which is used as a therapeutic target. Recent genetic studies have shown that ER binding occurs in regions distant to the promoters of estrogen target genes. These studies have also demonstrated that ER binding is accompanied with the binding of other transcription factors, which regulate the function of ER and response to anti-estrogen therapies. In this review, we explain how these factors influence the interaction of ER to chromatin and their cooperation for ER transcriptional activity. Moreover, we describe how the expression of these factors dictates the response to anti-estrogen therapies. Finally, we discuss how cytoplasmatic signaling pathways may modulate the function of ER and its cooperating transcription factors.

Cell type-specific binding patterns reveal that TCF7L2 can be tethered to the genome by association with GATA3

Background

The TCF7L2 transcription factor is linked to a variety of human diseases, including type 2 diabetes and cancer. One mechanism by which TCF7L2 could influence expression of genes involved in diverse diseases is by binding to distinct regulatory regions in different tissues. To test this hypothesis, we performed ChIP-seq for TCF7L2 in six human cell lines.

Results

We identified 116,000 non-redundant TCF7L2 binding sites, with only 1,864 sites common to the six cell lines. Using ChIP-seq, we showed that many genomic regions that are marked by both H3K4me1 and H3K27Ac are also bound by TCF7L2, suggesting that TCF7L2 plays a critical role in enhancer activity. Bioinformatic analysis of the cell type-specific TCF7L2 binding sites revealed enrichment for multiple transcription factors, including HNF4alpha and FOXA2 motifs in HepG2 cells and the GATA3 motif in MCF7 cells. ChIP-seq analysis revealed that TCF7L2 co-localizes with HNF4alpha and FOXA2 in HepG2 cells and with GATA3 in MCF7 cells. Interestingly, in MCF7 cells the TCF7L2 motif is enriched in most TCF7L2 sites but is not enriched in the sites bound by both GATA3 and TCF7L2. This analysis suggested that GATA3 might tether TCF7L2 to the genome at these sites. To test this hypothesis, we depleted GATA3 in MCF7 cells and showed that TCF7L2 binding was lost at a subset of sites. RNA-seq analysis suggested that TCF7L2 represses transcription when tethered to the genome via GATA3.

Conclusions

Our studies demonstrate a novel relationship between GATA3 and TCF7L2, and reveal important insights into TCF7L2-mediated gene regulation.

Reprogramming non-mammary and cancer cells in the developing mouse mammary gland

The capacity of any portion of the murine mammary gland to produce a complete functional mammary outgrowth upon transplantation to an epithelium-divested fat pad is unaffected by the age or reproductive history of the donor. Likewise, through serial transplantations, no loss of potency is detected when compared to similar transplantations of the youngest mammary tissue tested. This demonstrates that stem cell activity is maintained intact throughout the lifetime of the animal despite aging and the repeated expansion and depletion of the mammary epithelium through multiple rounds of pregnancy, lactation and involution. These facts support the contention that mammary stem cells reside in protected tissue locales (niches), where their reproductive potency remains essentially unchanged through life. Disruption of the tissue, to produce dispersed cells results in the desecration of the protection afforded by the "niche" and leads to a reduced capacity of dispersed epithelial cells (in terms of the number transplanted) to recapitulate complete functional mammary structures. Our studies demonstrate that during the reformation of mammary stem cell niches by dispersed epithelial cells in the context of the intact epithelium-free mammary stroma, non-mammary cells, including mouse and human cancer cells, may be sequestered and reprogrammed to perform mammary epithelial cell functions including those ascribed to mammary stem/progenitor cells.

Biological and prognostic associations of miR-205 and let-7b in breast cancer revealed by in situ hybridization analysis of micro-RNA expression in arrays of archival tumour tissue

Micro-RNAs (miRNAs) are frequently dysregulated in a range of human malignancies, many have been shown to act either as tumour supressors or oncogenes and several have been implicated in breast cancer. However, breast cancer is a diverse disease and little is known about the relationships between miRNA expression, clinical outcome and tumour subtype. We used locked nucleic acid probe in situ hybridization (LNA-ISH) to visualize, in tissue micro-arrays (TMAs) of 2919 formalin-fixed paraffin-embedded (FFPE) archival breast tumours, the expression of two key miRNAs that are frequently lost in a range of solid malignancies, let-7b and miR-205. These miRNAs were also quantified by quantitative reverse transcription PCR in cores of FFPE tissue from 40 of these cases, demonstrating that LNA-ISH is semi-quantitative. The tumours in the TMAs were assigned to subtypes based on their immunohistochemical (IHC) staining with ER, PR, HER2, CK5/6 and EGFR. let-7b expression was shown to be associated with luminal tumours and to have an independent significant positive prognostic value in this group. miR-205 is associated with tumours of ductal morphology and is of significant positive prognostic value within these tumours. We propose that the expression of miR-205 may contribute to ductal tumour morphology.

Cell polarity, epithelial-mesenchymal transition, and cell-fate decision gene expression in ductal carcinoma in situ

Loss of epithelial cell identity and acquisition of mesenchymal features are early events in the neoplastic transformation of mammary cells. We investigated the pattern of expression of a selected panel of genes associated with cell polarity and apical junction complex or involved in TGF-β-mediated epithelial-mesenchymal transition and cell-fate decision in a series of DCIS and corresponding patient-matched normal tissue. Additionally, we compared DCIS gene profile with that of atypical ductal hyperplasia (ADH) from the same patient. Statistical analysis identified a “core” of genes differentially expressed in both precursors with respect to the corresponding normal tissue mainly associated with a terminally differentiated luminal estrogen-dependent phenotype, in agreement with the model according to which ER-positive invasive breast cancer derives from ER-positive progenitor cells, and with an autocrine production of estrogens through androgens conversion. Although preliminary, present findings provide transcriptomic confirmation that, at least for the panel of genes considered in present study, ADH and DCIS are part of a tumorigenic multistep process and strongly arise the necessity for the regulation, maybe using aromatase inhibitors, of the intratumoral and/or circulating concentration of biologically active androgens in DCIS patients to timely hamper abnormal estrogens production and block estrogen-induced cell proliferation.

ERα, microRNAs, and the epithelial-mesenchymal transition in breast cancer

The most common form of breast cancer, luminal A, is estrogen receptor α (ERα)-positive and epithelial, but nevertheless can metastasize. The process of epithelial-mesenchymal transition (EMT) is probably the first step in the metastasis of epithelial cancers. We discuss the characteristics of EMT, including factors that induce EMT, and the relationship of EMT to cancer stem cells (CSCs). Estrogen/ERα signaling maintains an epithelial phenotype and suppresses EMT. An overview of microRNAs in breast cancer is presented, including how microRNA biogenesis is altered in cancer and regulated by ERα. We also discuss the role of the miR-200 family in opposing EMT. Finally, we discuss specific microRNAs that target ERα and regulate EMT in breast cancer, and the role of these microRNAs in breast cancer progression.

Expression and relevance of TRPS-1: a new GATA transcription factor in breast cancer

GATA transcription factor family members have been found to play a critical role in the differentiation of many tissue types. For example, GATA-3 has been found to be highly correlated with estrogen receptor α (ER) expression and is emerging as one of the "master regulators" in breast ductal epithelial cell differentiation. Recently, we discovered another GATA family member highly prevalent in breast cancer called the trichorhinophalangeal syndrome-1 gene (TRPS-1). Using a quantitative immunohistochemistry (qIHC) approach, we found that TRPS-1 was significantly correlated with ER, PR, GATA-3, as well as HER2 expression. However, TRPS-1 was also found to be expressed in a high proportion of ER(-) ductal epithelial breast cancers (BCs), indicating that it may act as a ductal epithelial cell-specific transcription factor regulating cell fate at some point in the epithelial cell differentiation pathway. In keeping with this hypothesis, we found that TRPS-1 protein expression in BC above a certain threshold using qIHC correlated with markedly improved overall survival. Cox proportional hazards analysis found that both TRPS-1 and ER expression above critical threshold equally predicted for improved survival. Thus, TRPS-1 may be a powerful new positive prognostic marker in BC, and further IHC studies, as well as examination of its molecular function in ductal epithelial cell differentiation in the breast, are warranted. In this regard, data on the role of TRPS-1 in the differentiation of cells from mesenchymal precursors in other tissues, such as kidney metanephric mesenchymal cells, columnar chondrocytes, and osteoblasts, in mouse models may be useful. Indeed, these studies have found that TRPS-1 is a critical regulator of mesenchymal-to-epithelial cell transition. In the mammary gland, the restricted expression of TRPS-1 in human, mouse, and rat ductal epithelial cells suggests that it may also play a similar role during ductal luminal progenitor/stem cell differentiation. We present a model of TRPS-1 action in which it may act upstream of GATA-3 and ER on an earlier ductal epithelial progenitor cell or mammary stem cell during mammary gland development and also helps prevent reversion of ER(+) BC cells back into mesenchymal-like cells. This model predicts that BCs with low or no TRPS-1 expression may inherently be much less differentiated and more aggressive tumors with less favorable prognosis.

Breast cancer expression of YKL-40 correlates with tumour grade, poor differentiation, and other cancer markers

Background:

Serum levels of a secreted glycoprotein YKL-40 are elevated in patients with a wide range of cancers including breast, colorectal, and ovarian cancers. Furthermore, these increased levels correlate with poorer survival of cancer patients, suggesting that serum levels of YKL-40 might be a prognostic biomarker. However, the tissue expression of YKL-40 and its relationship with clinical outcomes and other potential markers are poorly understood.

Methods:

Tissue samples from invasive breast cancers, breast ductal carcinoma in situ (DCIS), and cancer-free reduction mammoplasty were enrolled. YKL-40 expression was measured using immunohistochemistry and evaluated by a semi-quantification assay. Statistical analyses explored the relationship of YKL-40 with clinical outcome and other breast cancer biomarkers.

Results:

Breast ductal carcinoma in situ expressed low and moderate levels of YKL-40. In the subset of 203 patients with invasive cancer, YKL-40 levels were positively correlated with tumour grade (P<0.0001) and Her2/neu (P<0.01), but negatively correlated with oestrogen (P<0.0001) and progesterone receptor (P<0.0001). YKL-40 levels were inversely correlated with expressions of GATA3 (P=0.0137) and E-cadherin (P=0.0417).

Conclusion:

These data demonstrate that expression levels of YKL-40 are associated with tumour grade, poor differentiation, and other breast cancer markers, highlighting that tissue levels of YKL-40 serve as a valuable biomarker for breast cancer diagnosis and prognosis.

Coordinate regulation of GATA-3 and Th2 cytokine gene expression by the RNA-binding protein HuR

The posttranscriptional mechanisms whereby RNA-binding proteins (RBPs) regulate T cell differentiation remain unclear. RBPs can coordinately regulate the expression of functionally related genes via binding to shared regulatory sequences, such as the adenylate-uridylate-rich elements (AREs) present in the 3' untranslated region (UTR) of mRNA. The RBP HuR posttranscriptionally regulates IL-4, IL-13, and other Th2 cell-restricted transcripts. We hypothesized that the ARE-bearing GATA-3 gene, a critical regulator of Th2 polarization, is under HuR control as part of its coordinate posttranscriptional regulation of the Th2 program. We report that in parallel with stimulus-induced increase in GATA-3 mRNA and protein levels, GATA-3 mRNA half-life is increased after restimulation in the human T cell line Jurkat, in human memory and Th2 cells, and in murine Th2-skewed cells. We demonstrate by immunoprecipitation of ribonucleoprotein complexes that HuR associates with the GATA-3 endogenous transcript in human T cells and found, using biotin pulldown assay, that HuR specifically interacts with its 3'UTR. Using both loss-of-function and gain-of-function approaches in vitro and in animal models, we show that HuR is a critical mediator of stimulus-induced increase in GATA-3 mRNA and protein expression and that it positively influences GATA-3 mRNA turnover, in parallel with selective promotion of Th2 cytokine overexpression. These results suggest that HuR-driven posttranscriptional control plays a significant role in T cell development and effector function in both murine and human systems. A better understanding of HuR-mediated control of Th2 polarization may have utility in altering allergic airway inflammation in human asthmatic patients.

RANKL/RANK-beyond bones

Receptor-activator of NF-κB ligand (TNFSF11, also known as RANKL, OPGL, TRANCE, and ODF) and its tumor necrosis factor (TNF)-family receptor RANK are essential regulators of bone remodeling, lymph node formation, establishment of the thymic microenvironment, mammary gland development during pregnancy, and bone metastasis in cancer. We have recently also reported that the RANKL/RANK system controls the incidence and onset of sex hormone, progestin-driven breast cancer. RANKL and RANK are also expressed in the central nervous systems where they play an essential role in body temperature regulation. RANKL activates brain regions involved in thermoregulation and induces fever via the COX2-PGE(2)/EP3R pathway. Moreover, female mice with a RANK gene deleted in neurons and astrocytes exhibit increased basal body temperature, suggesting that the RANKL/RANK system also controls physiological thermoregulation in females under the control of sex hormones. This review will summarize the recently emerging role of the RANKL/RANK signaling axis in mammary gland development, cancer metastasis, hormone-derived breast cancer development, and thermal regulation. Furthermore, we will highlight the striking therapeutic potential of this pathway and provide a molecular rationale for consideration of targeting RANKL/RANK in diseases such as breast cancer.

The Notch ligand Jagged2 promotes lung adenocarcinoma metastasis through a miR-200-dependent pathway in mice

Epithelial tumor cells transit to a mesenchymal state in response to extracellular cues, in a process known as epithelial-to-mesenchymal transition (EMT). The precise nature of these cues has not been fully defined, an important issue given that EMT is an early event in tumor metastasis. Here, we have found that a population of metastasis-prone mouse lung adenocarcinoma cells expresses Notch and Notch ligands and that the Notch ligand Jagged2 promotes metastasis. Mechanistically, Jagged2 was found to promote metastasis by increasing the expression of GATA-binding (Gata) factors, which suppressed expression of the microRNA-200 (miR-200) family of microRNAs that target the transcriptional repressors that drive EMT and thereby induced EMT. Reciprocally, miR-200 inhibited expression of Gata3, which reversed EMT and abrogated metastasis, suggesting that Gata3 and miR-200 are mutually inhibitory and have opposing effects on EMT and metastasis. Consistent with this, high levels of Gata3 expression correlated with EMT in primary tumors from 2 cohorts of lung adenocarcinoma patients. These findings reveal what we believe to be a novel Jagged2/miR-200-dependent pathway that mediates lung adenocarcinoma EMT and metastasis in mice and may have implications for the treatment of human epithelial tumors.

Plant development: early events in lateral root initiation

How are the lateral root founder cells specified in the pericycle to initiate lateral root development? An Aux/IAA28 signaling module activates transcription factor GATA23 to control founder cell identity.

Prolactin-induced mouse mammary carcinomas model estrogen resistant luminal breast cancer

Introduction

Tumors that express estrogen receptor alpha (ERα+) comprise 75% of breast cancers in women. While treatments directed against this receptor have successfully lowered mortality rates, many primary tumors initially or later exhibit resistance. The paucity of murine models of this "luminal" tumor subtype has hindered studies of factors that promote their pathogenesis and modulate responsiveness to estrogen-directed therapeutics. Since epidemiologic studies closely link prolactin and the development of ERα+ tumors in women, we examined characteristics of the aggressive ERα+ and ERα- carcinomas which develop in response to mammary prolactin in a murine transgenic model (neu-related lipocalin- prolactin (NRL-PRL)). To evaluate their relationship to clinical tumors, we determined phenotypic relationships among these carcinomas, other murine models of breast cancer, and features of luminal tumors in women.

Methods

We examined a panel of prolactin-induced tumors for characteristics relevant to clinical tumors: histotype, ERα/progesterone receptor (PR) expression and estrogen responsiveness, Activating Protein 1 (AP-1) components, and phosphorylation of signal transducer and activator of transcription 5 (Stat5), extracellular signal regulated kinase (ERK) 1/2 and AKT. We compared levels of transcripts in the ERα-associated "luminal" signature that defines this subtype of tumors in women and transcripts enriched in various mammary epithelial lineages to other well-studied genetically modified murine models of breast cancer. Finally, we used microarray analyses to compare prolactin-induced ERα+ and ERα- tumors, and examined responsiveness to estrogen and the anti-estrogen, Faslodex, in vivo.

Results

Prolactin-induced carcinomas were markedly diverse with respect to histotype, ERα/PR expression, and activated signaling cascades. They constituted a heterogeneous, but distinct group of murine mammary tumors, with molecular features of the luminal subtype of human breast cancer. In contrast to morphologically normal and hyperplastic structures in NRL-PRL females, carcinomas were insensitive to ERα-mediated signals. These tumors were distinct from mouse mammary tumor virus (MMTV)-neu tumors, and contained elevated transcripts for factors associated with luminal/alveolar expansion and differentiation, suggesting that they arose from physiologic targets of prolactin. These features were shared by ERα+ and ERα- tumors, suggesting a common origin, although the former exhibited transcript profiles reflecting greater differentiation.

Conclusions

Our studies demonstrate that prolactin can promote diverse carcinomas in mice, many of which resemble luminal breast cancers, providing a novel experimental model to examine the pathogenesis, progression and treatment responsiveness of this tumor subtype.