Basal-like and triple-negative breast cancers: a critical review with an emphasis on the implications for pathologists and oncologists

Therapeutic potential of histamine H₄ receptor agonists in triple-negative human breast cancer experimental model

BACKGROUND AND PURPOSE

The presence of the histamine H₄ receptor (H₄R) was previously reported in benign and malignant lesions and cell lines derived from the human mammary gland. The aim of this work was to evaluate the effects of H₄R ligands on the survival, tumour growth rate and metastatic capacity of breast cancer in an experimental model.

EXPERIMENTAL APPROACH

Xenograft tumours of the highly invasive human breast cancer cell line MDA-MB-231 were established in immune deficient nude mice. The following H₄R agonists were employed: histamine (5 mg kg⁻¹), clozapine (1 mg kg⁻¹) and the experimental compound JNJ28610244 (10 mg kg⁻¹).

RESULTS

Data indicate that developed tumours were highly undifferentiated, expressed H₄R and exhibited high levels of histamine content and proliferation marker (PCNA) while displaying low apoptosis. Mice of the untreated group displayed a median survival of 60 days and a tumour doubling time of 7.4 ± 0.6 days. A significant decrease in tumour growth evidenced by an augment of the tumour doubling time was observed in the H₄R agonist groups (13.1 ± 1.2, P < 0.01 in histamine group; 15.1 ± 1.1, P < 0.001 in clozapine group; 10.8 ± 0.7, P < 0.01 in JNJ28610244 group). This effect was associated with a decrease in the PCNA expression levels, and also reduced intratumoural vessels in histamine and clozapine treated mice. Histamine significantly increased median survival (78 days; Log rank Mantel-Cox Test, P = 0.0025; Gehan-Breslow-Wilcoxon Test, P = 0.0158) and tumoural apoptosis.

CONCLUSIONS AND IMPLICATIONS

Histamine through the H₄R exhibits a crucial role in tumour progression. Therefore, H₄R ligands offer a novel therapeutic potential as adjuvants for breast cancer treatment.

Bioinformatic analysis reveals a pattern of STAT3-associated gene expression specific to basal-like breast cancers in human tumors

Signal transducer and activator of transcription 3 (STAT3), a latent transcription factor associated with inflammatory signaling and innate and adaptive immune responses, is known to be aberrantly activated in a wide variety of cancers. In vitro analysis of STAT3 in human cancer cell lines has elucidated a number of specific targets associated with poor prognosis in breast cancer. However, to date, no comparison of cancer subtype and gene expression associated with STAT3 signaling in human patients has been reported. In silico analysis of human breast cancer microarray and reverse-phase protein array data was performed to identify expression patterns associated with STAT3 in basal-like and luminal breast cancers. Results indicate clearly identifiable STAT3-regulated signatures common to basal-like breast cancers but not to luminal A or luminal B cancers. Furthermore, these differentially expressed genes are associated with immune signaling and inflammation, a known phenotype of basal-like cancers. These findings demonstrate a distinct role for STAT3 signaling in basal breast cancers, and underscore the importance of considering subtype-specific molecular pathways that contribute to tissue-specific cancers.

Gene Expression Analysis Reveals Distinct Pathways of Resistance to Bevacizumab in Xenograft Models of Human ER-Positive Breast Cancer

Bevacizumab, the recombinant antibody targeting vascular endothelial growth factor (VEGF), improves progression-free but not overall survival in metastatic breast cancer. To seek further insights in resistance mechanisms to bevacizumab at the molecular level, we developed VEGF and non-VEGF-driven ER-positive MCF7-derived xenograft models allowing comparison of tumor response at different timepoints. VEGF gene (MV165) overexpressing xenografts were initially sensitive to bevacizumab, but eventually acquired resistance. In contrast, parental MCF7 cells derived tumors were de novo insensitive to bevacizumab. Microarray analysis with qRT-PCR validation revealed that Follistatin (FST) and NOTCH were the top signaling pathways associated with resistance in VEGF-driven tumors (P<0.05). Based on the presence of VEGF, treatment with bevacizumab resulted in altered patterns of metagenes and PAM50 gene expression. In VEGF-driven model after short and long-term bevacizumab treatments, a change in the intrinsic subtype (luminal to myoepithelial/basal-like) was observed in association with increased expression of genes implicated with cancer stem cell phenotype (P<0.05). Our results show that the presence or absence of VEGF expression affects the response to bevacizumab therapy and gene pathways. In particular, long-term bevacizumab treatment shifts the cancer cells to a more aggressive myoepithelial/basal subtype in VEGF-expressing model, but not in non-VEGF model. These findings could shed light on variable results to anti-VEGF therapy in patients and emphasize the importance of patient stratification based on the VEGF expression. Our data strongly suggest consideration of patient subgroups for treatment and designing novel combinatory therapies in the clinical setting.

Complexities of androgen receptor signalling in breast cancer

While the clinical benefit of androgen-based therapeutics in breast cancer has been known since the 1940s, we have only recently begun to fully understand the mechanisms of androgen action in breast cancer. Androgen signalling pathways can have either beneficial or deleterious effects in breast cancer depending on the breast cancer subtype and intracellular context. This review discusses our current knowledge of androgen signalling in breast cancer, including the relationship between serum androgens and breast cancer risk, the prognostic significance of androgen receptor (AR) expression in different breast cancer subtypes and the downstream molecular pathways mediating androgen action in breast cancer cells. Intracrine androgen metabolism has also been discussed and proposed as a potential mechanism that may explain some of the reported differences regarding dichotomous androgen actions in breast cancers. A better understanding of AR signalling in this disease is critical given the current resurgence in interest in utilising contemporary AR-directed therapies for breast cancer and the need for biomarkers that will accurately predict clinical response.

VGLL1 expression is associated with a triple-negative basal-like phenotype in breast cancer

Vestigial-like 1 (VGLL1) is a poorly characterized gene encoding a transcriptional co-activator structurally homologous to TAZ and YAP that modulates the Hippo pathway in Drosophila. In this study, we examined the expression of VGLL1 and its intronic miRNA, miR-934, in breast cancer. VGLL1 and miR-934 expression miRNA profiling was carried out on frozen samples of grade 3 invasive ductal carcinomas. VGLL1 protein was also examined in 433 sporadic and BRCA1-associated breast carcinomas on tissue microarrays. RNA-seq data from The Cancer Genome Atlas (TCGA) was used to confirm differences in VGLL1 and miR-934 expression in different breast cancer subtypes, and to correlate their expression with that of other genes and miRNAs. Of 28 miRNAs differentially expressed in estrogen receptor (ER)-positive and ER-negative grade 3 breast carcinomas, miR-934 was most strongly upregulated in ER-negative carcinomas, and its expression was correlated with that of VGLL1. Nuclear VGLL1 expression was observed in 13% of sporadic breast carcinomas, and while VGLL1 was only occasionally found in luminal A (0.70%) and B (5.60%) carcinomas, it was often expressed in HER2-positive (17%), triple-negative (TN) breast carcinomas (>40%) and BRCA1-associated TN carcinomas (>50%). These findings were confirmed in the TCGA dataset, which revealed positive associations with luminal progenitor genes (GABRP, SLC6A14, FOXC1, PROM1, and BBOX1) and strong negative correlations with ER-associated genes (ESR1, C6ORF211, GATA3, and FOXA1). Moreover, VGLL1 expression was associated with reduced overall survival. In conclusion, VGLL1 and miR-934 are mainly expressed in sporadic and BRCA1-associated TN basal-like breast carcinomas, and their coordinated expression, at least partially mediated by the direct modulation of ESR1, might be involved in the maintenance of a luminal progenitor phenotype.

Axl receptor tyrosine kinase expression in breast cancer

AIMS

Triple-negative breast cancer comprises a clinically aggressive group of invasive carcinomas. We examined a published gene expression screen of a panel of breast cancer cell lines to identify a potential triple-negative breast cancer-specific gene signature, and attempted to verify our findings by performing immunohistochemical analysis on tissue microarrays containing a large cohort of invasive breast carcinomas.

METHODS

The microarray dataset for a panel of human breast cancer cell lines was interrogated for triple-negative breast cancer-specific genes. Membranous immunohistochemical expression of the protein product of the AXL gene was assessed semiquantitatively in 569 invasive breast carcinomas grouped according to molecular subgroup by immunohistochemistry.

RESULTS

AXL was significantly upregulated in triple-negative/basal B cell lines compared with luminal or basal A cell lines. No significant difference was observed in the level of immunohistochemical expression of Axl protein between triple-negative breast cancers and other molecular subgroups (p=0.257). Axl expression was significantly associated with lymphovascular invasion (LVI) in all subgroups combined (p=0.033), and within the luminal A (p=0.002) and triple-negative breast cancer subgroups (p=0.026).

CONCLUSIONS

Despite preferential upregulation of AXL in triple-negative/basal B cell lines, analysis of Axl protein expression in a large series of patients' breast tumours revealed no association between Axl expression and triple-negative breast cancer or other subtype. The association of Axl expression with LVI supports previous work that implicates Axl as a promoter of invasiveness in breast cancer cell lines. Further studies are necessary to explore whether Axl expression of individual breast cancer tumours can be clinically useful.

Molecular classification of breast cancer

Breast cancer is a complex, multifaceted disease encompassing a great variety of entities that show considerable variation in clinical, morphological and molecular attributes. Traditional classifications including histological assessment and clinical staging are used to guide patient management. In recent years, there has been exponential progress in molecular analysis with profound implications for our understanding of breast cancer biology and, hence, classification. There are now genome-based frameworks for the molecular categorisation of breast cancer including the development of prognostic and predictive signatures that potentially allow individualisation of treatment. Here we review the current state of the molecular classifications of in situ and invasive breast cancer including special subtypes. Future perspectives are also provided.

Prognostic evaluation of feline mammary carcinomas: a review of the literature

A large number of studies have investigated feline mammary tumors in an attempt to identify prognostic markers and generate comparative analyses with human breast cancer. Nevertheless, a retrospective base of assessments and the lack of standardization in methodology and study design have caused weakness in study results, making comparison difficult. We examined feline mammary tumor publications and evaluated postulated prognostic parameters according to the recently published "Recommended Guidelines for the Conduct and Evaluation of Prognostic Studies in Veterinary Oncology." Using these criteria, we determined with statistically significant reliability that prognostic parameters for feline mammary tumors are tumor grading and lymph node/lymphovascular invasion. Furthermore, tumor subtype, size, and staging are worthy of further standardized investigation. We present statistical significance for each studied parameter as well as its relevance to disease progression and survival. Our evaluation suggests that marker expression (ie, Ki67, HER2, ER) may provide relevant information applicable for therapeutic predictions; however, consensus efforts and protocol standardization are needed. We identify and discuss major points of concern--such as sample preservation and selection, standardization of immunohistochemical protocols, and evaluation of results--to provide support for subsequent reliable analyses.

Patient-derived xenografts of triple-negative breast cancer reproduce molecular features of patient tumors and respond to mTOR inhibition

INTRODUCTION

Triple-negative breast cancer (TNBC) is aggressive and lacks targeted therapies. Phosphatidylinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathways are frequently activated in TNBC patient tumors at the genome, gene expression and protein levels, and mTOR inhibitors have been shown to inhibit growth in TNBC cell lines. We describe a panel of patient-derived xenografts representing multiple TNBC subtypes and use them to test preclinical drug efficacy of two mTOR inhibitors, sirolimus (rapamycin) and temsirolimus (CCI-779).

METHODS

We generated a panel of seven patient-derived orthotopic xenografts from six primary TNBC tumors and one metastasis. Patient tumors and corresponding xenografts were compared by histology, immunohistochemistry, array comparative genomic hybridization (aCGH) and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) sequencing; TNBC subtypes were determined. Using a previously published logistic regression approach, we generated a rapamycin response signature from Connectivity Map gene expression data and used it to predict rapamycin sensitivity in 1,401 human breast cancers of different intrinsic subtypes, prompting in vivo testing of mTOR inhibitors and doxorubicin in our TNBC xenografts.

RESULTS

Patient-derived xenografts recapitulated histology, biomarker expression and global genomic features of patient tumors. Two primary tumors had PIK3CA coding mutations, and five of six primary tumors showed flanking intron single nucleotide polymorphisms (SNPs) with conservation of sequence variations between primary tumors and xenografts, even on subsequent xenograft passages. Gene expression profiling showed that our models represent at least four of six TNBC subtypes. The rapamycin response signature predicted sensitivity for 94% of basal-like breast cancers in a large dataset. Drug testing of mTOR inhibitors in our xenografts showed 77 to 99% growth inhibition, significantly more than doxorubicin; protein phosphorylation studies indicated constitutive activation of the mTOR pathway that decreased with treatment. However, no tumor was completely eradicated.

CONCLUSIONS

A panel of patient-derived xenograft models covering a spectrum of TNBC subtypes was generated that histologically and genomically matched original patient tumors. Consistent with in silico predictions, mTOR inhibitor testing in our TNBC xenografts showed significant tumor growth inhibition in all, suggesting that mTOR inhibitors can be effective in TNBC, but will require use with additional therapies, warranting investigation of optimal drug combinations.

Luminal subtypes predict improved survival following central nervous system metastasis in patients with surgically managed metastatic breast carcinoma

CONTEXT

Metastatic breast cancer to the central nervous system (CNS) is second only to lung cancer metastasis to the CNS in frequency. Patients with triple-negative primary breast cancer and those with human epidermal growth factor receptor 2 (HER2)-positive primary breast cancer are at an increased risk for metastasis. Very little is known about predictive or prognostic variables once patients develop CNS metastases. Currently, therapeutic options are limited, with surgery generally offered primarily to those with solitary lesions.

OBJECTIVES

To determine the influence of molecular subtypes of metastatic breast cancer on survival from the time of CNS metastasis and to aid in the prognostic stratification of these patients.

DESIGN

We identified 59 cases of metastatic breast cancer to the CNS and analyzed them for various demographic and clinicopathologic parameters. Tumors were categorized into molecular subtypes using immunohistochemical methods: luminal A [estrogen receptor (ER⁺)/Ki67low], luminal B (ER⁺/Ki67 high), intrinsic HER2 (ER⁻/HER2⁺), and triple-negative. Survival after CNS metastasis for each group was plotted using a Kaplan-Meier curve, and multivariate analysis was performed.

RESULTS

Patients with metastases from luminal tumors had a statistically significant survival advantage when compared with those of the triple-negative phenotype. Importantly, survival among patients with luminal A and luminal B tumors was not significantly different. Similarly, patient's age, histologic grade, and number of lesions did not contribute to determining outcomes.

CONCLUSIONS

Estrogen receptor positivity (ie, luminal phenotype) of tumors appears to determine outcomes after development of metastases. In contrast, proliferation rate had little or no effect on the long-term survival. Understanding the biology of metastases can help stratify patients into prognostically meaningful categories and tailor treatment regimens for individual patients.

Expression of cancer stem cell markers in basal and penta-negative breast carcinomas--a study of a series of triple-negative tumors

PURPOSE

Breast cancer is a heterogeneous disease. Immunohistochemistry has given rise to triple-negative carcinoma (TNC). Concomitantly, biological origins of neoplasia and its heterogeneity has been strongly debated in cancer stem cells (CSC) theme. This study investigates the prevalence of basal (BCC) and penta-negative carcinomas (5NC) in TNC and establishes associations with CSC (CD44CD24).

MATERIALS AND METHODS

94 TNC were tested for CK5/6, HER1, CD44 and CD24, evaluated by a simple immunohistochemistry score and correlated with clinicopathological and survival data.

RESULTS

BCC had higher tumor grades than 5NC (p=0.004). CD44 negativity (p=0.007) and CD44(-)CD24(+) phenotype (p=0.013) were associated with less vascular invasion amongst TNC. CD44 expression was associated with BCC (p=0.007). CD44(-)CD24(-/low) phenotype was associated with 5NC. None of the variables were associated with clinical outcome.

CONCLUSION

BCC and 5NC are closely related tumor subtypes. CD44(-)CD24(-/low) phenotype was associated with 5NC and CD44(-)CD24(+) phenotype was associated with vascular invasion. These results require histogenetic confirmation in larger studies.

A conceptual and methodological framework for investigating etiologic heterogeneity

Cancer has traditionally been studied using the disease site of origin as the organizing framework. However, recent advances in molecular genetics have begun to challenge this taxonomy, as detailed molecular profiling of tumors has led to discoveries of subsets of tumors that have profiles that possess distinct clinical and biological characteristics. This is increasingly leading to research that seeks to investigate whether these subtypes of tumors have distinct etiologies. However, research in this field has been opportunistic and anecdotal, typically involving the comparison of distributions of individual risk factors between tumors classified on the basis of candidate tumor characteristics. The purpose of this article is to place this area of investigation within a more general conceptual and analytic framework, with a view to providing more efficient and practical strategies for designing and analyzing epidemiologic studies to investigate etiologic heterogeneity. We propose a formal definition of etiologic heterogeneity and show how classifications of tumor subtypes with larger etiologic heterogeneities inevitably possess greater disease risk predictability overall. We outline analytic strategies for estimating the degree of etiologic heterogeneity among a set of subtypes and for choosing subtypes that optimize the heterogeneity, and we discuss technical challenges that require further methodologic research. We illustrate the ideas by using a pooled case-control study of breast cancer classified by expression patterns of genes known to define distinct tumor subtypes.

Molecular classification of metaplastic carcinoma using surrogate immunohistochemical staining

OBJECTIVE

The purpose of this study is to investigate molecular subtyping and its implications on metaplastic carcinoma according to surrogate immunohistochemical (IHC) staining.

METHODS

Following tissue microarray analysis of 34 cases of metaplastic carcinoma, IHC staining for cytokeratin (CK) 5/6, epidermal growth factor receptor (EGFR), claudin-3, claudin-4, claudin-7, E-cadherin, STAT-1, androgen receptor and GGT was performed and classified into basal-like, molecular apocrine, claudin-low, immune-related, mixed and null types.

RESULTS

Among the 34 cases of metaplastic carcinoma, 13 were of the basal-like type (35.2%), 9 of the mixed type (26.5%), 8 of the null type (23.5%), 3 of the claudin-low type (8.8%), and 1 was of the molecular apocrine type (2.9%). Depending on the cell type, there were differences between molecular subtypes, with the matrix-producing type occupying the largest proportion in the basal-like, null and mixed types. The spindle cell type represented the largest proportion in the claudin-low and molecular apocrine types, and the squamous cell type characterized the largest proportion in the basal-like type.

CONCLUSION

Following molecular subtyping of metaplastic carcinomas using surrogate IHC markers, the largest number of cases was of the basal-like type, followed by the mixed, null, claudin-low and molecular apocrine types. There were differences between molecular subtypes according to the cell type.

The potential role of nanotechnology in therapeutic approaches for triple negative breast cancer

Triple Negative Breast Cancer, TNBC, a highly aggressive and metastatic type of breast cancer, is characterized by loss of expression of the estrogen receptor (ER), progesterone receptor (PR), and a lack of overexpression of the human epidermal growth factor receptor 2 (HER2). It is a heterogeneous group of tumors with diverse histology, molecular uniqueness and response to treatment. Unfortunately, TNBC patients do not benefit from current anti-HER2 or hormone positive targeted breast cancer treatments; consequently, these patients rely primarily on chemotherapy. However, the 5-year survival rate for woman with metastatic TNBC is less than 30%. As a result of ineffective treatments, TNBC tumors often progress to metastatic lesions in the brain and lung. Brain metastases of invasive breast cancer are associated with 1 and 2 year survival rate of 20% and <2% respectively. Because the only current systemic treatment for TNBC is chemotherapy, alternative targeted therapies are urgently needed to improve the prognosis for TNBC patients. This review is focused on opportunities for developing new approaches for filling the current void in an effective treatment for TNBC patients.

Canine mammary tumors: a review and consensus of standard guidelines on epithelial and myoepithelial phenotype markers, HER2, and hormone receptor assessment using immunohistochemistry

Although there have been several studies on the use of immunohistochemical biomarkers of canine mammary tumors (CMTs), the results are difficult to compare. This article provides guidelines on the most useful immunohistochemical markers to standardize their use and understand how outcomes are measured, thus ensuring reproducibility of results. We have reviewed the biomarkers of canine mammary epithelial and myoepithelial cells and identified those biomarkers that are most useful and those biomarkers for invasion and lymph node micrometastatic disease. A 10% threshold for positive reaction for most of these markers is recommended. Guidelines on immunolabeling for HER2, estrogen receptors (ERs), and progesterone receptors (PRs) are provided along with the specific recommendations for interpretation of the results for each of these biomarkers in CMTs. Only 3+ HER2-positive tumors should be considered positive, as found in human breast cancer. The lack of any known response to adjuvant endocrine therapy of ER- and PR-positive CMTs prevents the use of the biological positive/negative threshold used in human breast cancer. Immunohistochemistry results of ER and PR in CMTs should be reported as the sum of the percentage of positive cells and the intensity of immunolabeling (Allred score). Incorporation of these recommendations in future studies, either prospective or retrospective, will provide a mechanism for the direct comparison of studies and will help to determine whether these biomarkers have prognostic significance. Finally, these biomarkers may ascertain the most appropriate treatment(s) for canine malignant mammary neoplasms.

Roles of p53 and p16 in triple-negative breast cancer

SUMMARY p53 and p16 are both tumor suppressors. This article summarizes the current investigation status on their roles and interaction in triple-negative breast cancer (TNBC) to explore their potential as prognostic, predictive and therapeutic targets. There is significant evidence implicating that p53 mutation as a driver plays an important role in tumorigenesis and progression of TNBC. p53 mutations are more frequently observed in TNBCs compared with ER-positive breast cancers. The presence of a p53 mutation is associated with poorer prognosis in TNBC patients. The status of p53 protein expression divides TNBCs into two biologically distinct subgroups (p53-positive vs p53-negative); p53-positive tumors have more aggressive behavior. p53 has clinical prognostic utility and is a promising target candidate for directed therapy for TNBC patients. p16 appears to play a significant role in tumorigenesis of TNBC through the Rb/p16 dysfunction pathway. A high level of p16 protein expression is associated with aggressive behavior and tumor proliferation of TNBC. The status of p16 expression may have potential predictive value for TNBC response to chemotherapy; further investigation is needed to support the proposal. p16 expression has been strongly correlated with p53 expression in TNBC, suggesting interactions between the two mutations in tumorigenesis. It has been proposed that the two tumor suppressors appear to be involved in early events of TNBC formation with subsequent interplay resulting in their mutual inactivation and, ultimately, leading to a proliferative environment.

A survey of immunohistochemical biomarkers for basal-like breast cancer against a gene expression profile gold standard

Gene expression profiling of breast cancer delineates a particularly aggressive subtype referred to as 'basal-like', which comprises ∼15% of all breast cancers, afflicts younger women and is refractory to endocrine and anti-HER2 therapies. Immunohistochemical surrogate definitions for basal-like breast cancer, such as the clinical ER/PR/HER2 triple-negative phenotype and models incorporating positive expression for CK5 (CK5/6) and/or EGFR are heavily cited. However, many additional biomarkers for basal-like breast cancer have been described in the literature. A parallel comparison of 46 proposed immunohistochemical biomarkers of basal-like breast cancer was performed against a gene expression profile gold standard on a tissue microarray containing 42 basal-like and 80 non-basal-like breast cancer cases. Ki67 and PPH3 were the most sensitive biomarkers (both 92%) positively expressed in the basal-like subtype, whereas CK14, IMP3 and NGFR were the most specific (100%). Among biomarkers surveyed, loss of INPP4B (a negative regulator of phosphatidylinositol signaling) was 61% sensitive and 99% specific with the highest odds ratio (OR) at 108, indicating the strongest association with basal-like breast cancer. Expression of nestin, a common marker of neural progenitor cells that is also associated with the triple-negative/basal-like phenotype and poor breast cancer prognosis, possessed the second highest OR at 29 among the 46 biomarkers surveyed, as well as 54% sensitivity and 96% specificity. As a positively expressed biomarker, nestin possesses technical advantages over INPP4B that make it a more ideal biomarker for identification of basal-like breast cancer. The comprehensive immunohistochemical biomarker survey presented in this study is a necessary step for determining an optimized surrogate immunopanel that best defines basal-like breast cancer in a practical and clinically accessible way.

Adherence to treatment guidelines and survival in triple-negative breast cancer: a retrospective multi-center cohort study with 9,156 patients

Background

Triple-negative breast cancer (TNBC) remains a challenging topic for clinical oncologists. This study sought to evaluate TNBC versus other breast cancer subtypes with respect to survival parameters. We evaluated possible differences in survival in TNBC by age and by the extent to which evidence-based treatment guidelines were adhered.

Methods

This German retrospective multi-center cohort study included 9156 patients with primary breast cancer recruited from 1992 to 2008.

Results

The rates of guideline adherence are significantly lower in TNBC compared to non-TNBC subtypes. These lower rates of guideline adherence can be observed in all age groups and are most pronounced in the >65 subgroup [<50 (20.9% vs. 42.0%), 50–64 (25.1% vs. 51.1%), and >65 (38.4% vs. 74.6%)]. In TNBC patients of all age groups, disease-free survival and overall survival were associated with an improvement by 100% guideline-adherent adjuvant treatment compared to non-adherence. Furthermore, TNBC patients of all ages had similar outcome parameters if 100% guideline-adherent adjuvant treatment was applied.

Conclusion

The rates of guideline-adherent treatment were significantly lower in TNBC, even though guideline adherence was strongly associated with improved survival. In the case of 100% guideline-adherent treatment, no difference in survival was observed over all the age groups examined, even in the group of >65-year-old TNBC patients.

14-3-3σ stabilizes a complex of soluble actin and intermediate filament to enable breast tumor invasion

The protein 14-3-3σ (stratifin) is frequently described as a tumor suppressor silenced in about 80% of breast tumors. Intriguingly, we show that 14-3-3σ expression, which in normal breast is localized to the myoepithelial cells, tracks with malignant phenotype in two models of basal-like breast cancer progression, and in patients, it is associated with basal-like subtype and poor clinical outcome. We characterized a mechanism by which 14-3-3σ guides breast tumor invasion by integrating cytoskeletal dynamics: it stabilizes a complex of solubilized actin and intermediate filaments to maintain a pool of "bioavailable" complexes for polarized assembly during migration. We show that formation of the actin/cytokeratin/14-3-3σ complex and cellular migration are regulated by PKCζ-dependent phosphorylation, a finding that could form the basis for intervention in aggressive breast carcinomas expressing 14-3-3σ. Our data suggest that the biology of this protein is important in cellular movement and is contingent on breast cancer subtype.

Dysregulation of the epigenome in triple-negative breast cancers: basal-like and claudin-low breast cancers express aberrant DNA hypermethylation

A subset of human breast cancer cell lines exhibits aberrant DNA hypermethylation that is characterized by hyperactivity of the DNA methyltransferase enzymes, overexpression of DNMT3b, and concurrent methylation-dependent silencing of numerous epigenetic biomarker genes. The objective of this study was to determine if this aberrant DNA hypermethylation (i) is found in primary breast cancers, (ii) is associated with specific breast cancer molecular subtypes, and (iii) influences patient outcomes. Analysis of epigenetic biomarker genes (CDH1, CEACAM6, CST6, ESR1, GNA11, MUC1, MYB, SCNN1A, and TFF3) identified a gene expression signature characterized by reduced expression levels or loss of expression among a cohort of primary breast cancers. The breast cancers that express this gene expression signature are enriched for triple-negative subtypes - basal-like and claudin-low breast cancers. Methylation analysis of primary breast cancers showed extensive promoter hypermethylation of epigenetic biomarker genes among triple-negative breast cancers, compared to other breast cancer subclasses where promoter hypermethylation events were less frequent. Furthermore, triple-negative breast cancers either did not express or expressed significantly reduced levels of protein corresponding to methylation-sensitive biomarker gene products. Together, these findings suggest strongly that loss of epigenetic biomarker gene expression is frequently associated with gene promoter hypermethylation events. We propose that aberrant DNA hypermethylation is a common characteristic of triple-negative breast cancers and may represent a fundamental biological property of basal-like and claudin-low breast cancers. Kaplan-Meier analysis of relapse-free survival revealed a survival disadvantage for patients with breast cancers that exhibit aberrant DNA hypermethylation. Identification of this distinguishing trait among triple-negative breast cancers forms the basis for development of new rational therapies that target the epigenome in patients with basal-like and claudin-low breast cancers.

Feline mammary basal-like adenocarcinomas: a potential model for human triple-negative breast cancer (TNBC) with basal-like subtype

Background

Breast cancer is one of the leading causes of cancer deaths. Triple-negative breast cancer (TNBC), an immunophenotype defined by the absence of immunolabeling for estrogen receptor (ER), progesterone receptor (PR) and HER2 protein, has a highly aggressive behavior. A subpopulation of TNBCs exhibit a basal-like morphology with immunohistochemical positivity for cytokeratins 5/6 (CK5/6) and/or epidermal growth factor receptor (EGFR), and have a high incidence of BRCA (breast cancer susceptibility) mutations. Feline mammary adenocarcinomas (FMAs) are highly malignant and share a similar basal-like subtype. The purpose of this study was to classify FMAs according to the current human classification of breast cancer that includes evaluation of ER, PR and HER2 status and expression of basal CK 5/6 and EGFR. Furthermore, we selected triple negative, basal-like FMAs to screen for BRCA mutations similar to those described in human TNBC.

Methods

Twenty four FMAs were classified according to the current human histologic breast cancer classification including immunohistochemistry (IHC) for ER, PR HER2, CK5/6 and EGFR. Genetic alteration and loss of heterozygosity of BRCA1 and BRCA2 genes were analyzed in triple negative, basal-like FMAs.

Results

IHC for ER, PR and HER2 identified 14 of the 24 (58%) FMAs as a triple negative. Furthermore, 11of these 14 (79%) triple negative FMAs had a basal-like subtype. However, no genetic abnormalities were detected in BRCA1 and BRCA2 by direct sequencing and loss of heterozygosity analysis.

Conclusion

FMAs are highly aggressive neoplasms that are commonly triple negative and exhibit a basal-like morphology. This is similar to human TNBC that are also commonly classified as a basal-like subtype. While sequencing of a select number of triple negative, basal-like FMAs and testing for loss of heterozygosity of BRCA1 and BRCA2 did not identify mutations similar to those described in human TNBC, further in-depth evaluation is required to elucidate a potential role of BRCA in the tumorigenesis of triple negative, basal-like FMAs. The strong similarities in clinical behavior, morphology and IHC phenotype suggest that triple negative, basal-like FMAs may be a suitable spontaneous animal model for studying novel therapeutic approaches against human basal-like TNBC.

The identification of a small but significant subset of patients still targetable with anti-HER2 inhibitors when affected by triple negative breast carcinoma

PURPOSE

Triple (ER-, PR-, HER2-) negative breast carcinoma lack targeted therapies, making this group of tumors difficult to treat. By definition, the lack of HER2 expression means a case scoring 0 or 1+ after immunophenotypical analysis and makes the patients avoiding therapeutical chances with anti-HER2 inhibitors. We sought to recruit from a group of triple negative breast carcinoma, patients eligible for effective personalized targeted therapy with anti-HER therapies on the basis of their HER2 gene status.

METHODS

135 patients diagnosed with IHC triple negative breast carcinoma were studied. Whole tissue sections were used for in situ hybridization analysis.

RESULTS

8/100 (8 %) of ductal-type triple negative breast carcinoma presented Her-2/neu gene amplification versus 2/35 (5.7 %) non-ductal triple negative breast carcinoma. Three cases showed a ratio 2.5. One case showed Her-2/neu heterogeneous gene amplification, ratio 2.3. The other six showed from 7 to 8 absolute Her-2/neu gene copy number. Two cases staged pT1c, and eight cases staged pT2. Eight cases graded G3 and two cases G2.

CONCLUSION

(1) Eight percentage of ductal and 5.7 % non-ductal-type triple negative breast carcinoma present Her-2/neu gene amplification, (2) the standard diagnostic flowchart "do not FISH in 0-1+ (HER2-) breast carcinoma" should be replaced by "do FISH in triple (ER-, PR-, HER2-) negative breast carcinoma," to avoid loss of therapeutical chances in a cohort of such a patients, (3) we demonstrated the identification of a small but significant subset of patients targetable with anti-HER2 inhibitors, giving patients affected by (ex)triple negative breast carcinoma new personalized therapeutical chances.

Breast cancer classification by proteomic technologies: current state of knowledge

Breast cancer is traditionally considered as a heterogeneous disease. Molecular profiling of breast cancer by gene expression studies has provided us an important tool to discriminate a number of subtypes. These breast cancer subtypes have been shown to be associated with clinical outcome and treatment response. In order to elucidate the functional consequences of altered gene expressions related to each breast cancer subtype, proteomic technologies can provide further insight by identifying quantitative differences at the protein level. In recent years, proteomic technologies have matured to an extent that they can provide proteome-wide expressions in different clinical materials. This technology can be applied for the identification of proteins or protein profiles to further refine breast cancer subtypes or for discovery of novel protein biomarkers pointing towards metastatic potential or therapy resistance in a specific subtype. In this review, we summarize the current state of knowledge of proteomic research on molecular breast cancer classification and discuss important aspects of the potential usefulness of proteomics for discovery of breast cancer-associated protein biomarkers in the clinic.

Succinate dehydrogenase expression in breast cancer

The aim of this study was to investigate succinate dehydrogenase (SDH) expression in breast cancer according to breast cancer molecular subtype using immunohistochemistry and to assess the clinical implications of SDH expression. Immunohistochemical staining for ER, PR, HER-2, Ki-67, HIF-1α, SDHA, and SDHB was performed on tissue microarrays of 721 breast cancers. According to the immunohistochemistry results for ER, PR, HER-2, and Ki-67 and fluorescence in situ hybridization (FISH) results for HER-2, breast cancer molecular subtypes were classified into luminal A, luminal B, HER-2, and triple-negative breast cancer (TNBC). HER-2 subtype breast cancers most frequently showed high-level expression of SDHA in tumor cells, while the luminal A subtype most frequently showed low or negative expression of SDHA in tumor cells (P = 0.032). Stromal SDHB expression rate was highest in HER-2 subtype and lowest in TNBC (P < 0.001). SDHA-negative breast cancers were associated with younger age at diagnosis (P = 0.012), and SDHB-negative breast cancers with lower histologic grade (P = 0.044) and lower Ki-67 labeling index (LI) (P = 0.046). Tumor phenotypes according to the SDH status were SDHA(+)/SDHB(+) > SDHA(-)/SDHB(-) > SDHA(-)/SDHB(+) > SDHA(+)/SDHB(-) in order of frequency. The stromal phenotypes were SDHA(-)/SDHB(-) > SDHA(+)/SDHB(+) > SDHA(-)/SDHB(+) > SDHA(+)/SDHB(-). In conclusion, loss of SDHA or SDHB expression was observed in about 3% of breast cancers in this study. Low SDH expression status in breast tumor cells was associated with younger age at diagnosis and low-grade histology.

Comparison of basal-like triple-negative breast cancer defined by morphology, immunohistochemistry and transcriptional profiles

Basal-like invasive breast cancer is an important clinical group because of its association with a triple-negative phenotype defined by the lack of expression of estrogen, progesterone and human epidermal growth factor receptors 2, relative lack of therapeutic options and poor prognosis. However, depending on the method used to define these lesions, morphological assessment, immunohistochemical markers or gene expression, a different set of tumors is captured. The aim of this study was to investigate the consequences of using different methodological approaches to define basal-like lesions among triple-negative breast carcinomas with regard to their clinicopathological features and patient outcome. The cohort consisted of 142 invasive breast cancers with a triple-negative receptor status. First, each was reviewed histologically and those with morphological basal-like features were characterized as 'Path-Basal'. Second, the 'Core Basal' immunohistochemical lesions, defined as cytokeratin 5/6 and/or epidermal growth factor receptor 1 positive, within the triple-negative breast cancers were identified, and third their classification based on gene expression profiling was retrieved and those in the molecular 'PAM50 basal-like' subtype recorded. A total of 116 basal-like breast cancers were identified among the 142 triple-negative breast cancers by at least one of these three classifications (80%), but only 13 samples were defined as basal-like with all three methods. None of these 13 tumors were associated with lymphovascular invasion. The 34 morphological 'Path-Basal' lesions were significantly associated with a lack of nodal metastases. Comparing the estimates of death in the three classifications, the highest risk of death was seen for the 'Core Basal' group. In this study, we highlight that the definition of basal-like breast cancer based on different methodologies varies significantly and does not identify the same lesions. This incomplete overlap of cases emphasizes the need for consistent or new approaches to improve precise identification.

Associations between the Expression of Mucins (MUC1, MUC2, MUC5AC, and MUC6) and Clinicopathologic Parameters of Human Breast Ductal Carcinomas

PURPOSE

Mucins are members of the glycoprotein family expressed in benign and malignant epithelial cells. The aim of this study is to evaluate the relationships between the expression of mucins in breast ductal carcinoma and clinicopathologic parameters.

METHODS

We constructed tumor microarrays based on 240 cases of invasive ductal carcinoma and 40 cases of ductal carcinoma in situ (DCIS) using formalin fixed, paraffin embedded tissues. We examined the expressions of MUC1, MUC2, MUC5AC, and MUC6 by immunohistochemistry.

RESULTS

MUC1 demonstrated cytoplasmic, membranous, apical, and combinative expressions. Other mucins demonstrated cytoplasmic expression. In invasive ductal carcinoma, MUC1, MUC2, MUC5AC, and MUC6 were expressed in 93.6%, 6.2%, 4.8%, and 12.4% of cases, respectively; these rates were slightly, but not significantly, higher than observed in cases of DCIS. MUC1 expression was associated with estrogen receptor (ER) expression and negative MUC1 expression was associated with triple negativity. MUC6 expression was correlated with higher histologic grade, lymphatic invasion, lymph node metastasis, and HER2 positivity. No associations with any other clinicopathologic parameters were observed.

CONCLUSION

Most invasive ductal carcinomas of the breast express MUC1, and this expression is associated with ER expression. MUC6 expression is correlated with some clinicopathologic parameters that are indicators of poor prognosis. To evaluate the role of MUC6 as a potential biomarker, further studies are warranted.

Chemotherapeutic Potential of 2-[Piperidinoethoxyphenyl]-3-Phenyl-2H-Benzo(b)pyran in Estrogen Receptor- Negative Breast Cancer Cells: Action via Prevention of EGFR Activation and Combined Inhibition of PI-3-K/Akt/FOXO and MEK/Erk/AP-1 Pathways

Inhibition of epidermal growth factor receptor (EGFR) signaling is considered to be a promising treatment strategy for estrogen receptor (ER)-negative breast tumors. We have investigated here the anti-breast cancer properties of a novel anti-proliferative benzopyran compound namely, 2-[piperidinoethoxyphenyl]-3-phenyl-2H-benzo(b)pyran (CDRI-85/287) in ER- negative and EGFR- overexpressing breast cancer cells. The benzopyran compound selectively inhibited the EGF-induced growth of MDA-MB 231 cells and ER-negative primary breast cancer cell culture. The compound significantly reduced tumor growth in xenograft of MDA-MB 231 cells in nude mice. The compound displayed better binding affinity for EGFR than inhibitor AG1478 as demonstrated by molecular docking studies. CDRI-85/287 significantly inhibited the activation of EGFR and downstream effectors MEK/Erk and PI-3-K/Akt. Subsequent inhibition of AP-1 promoter activity resulted in decreased transcription activation and expression of c-fos and c-jun. Dephosphorylation of downstream effectors FOXO-3a and NF-κB led to increased expression of p27 and decreased expression of cyclin D1 which was responsible for decreased phosphorylation of Rb and prevented the transcription of E2F- dependent genes involved in cell cycle progression from G1/S phase. The compound induced apoptosis via mitochondrial pathway and it also inhibited EGF-induced invasion of MDA-MB 231 cells as evidenced by decreased activity of MMP-9 and expression of CTGF. These results indicate that benzopyran compound CDRI-85/287 could constitute a powerful new chemotherapeutic agent against ER-negative and EGFR over-expressing breast tumors.

Neural crest transcription factor Sox10 is preferentially expressed in triple-negative and metaplastic breast carcinomas

The transcription factor Sox10 mediates the differentiation of neural crest-derived cells, and Sox10 labeling by immunohistochemistry (IHC) is used clinically primarily to support the diagnosis of melanoma. Sox10 expression by IHC has been previously documented in benign breast myoepithelial cells but not in breast carcinomas. Here, we report the first systematic study of Sox10 expression in invasive ductal carcinomas subclassified by IHC-defined molecular subtype (100 cases), as well as in 24 cases of ductal carcinoma in situ and 44 mammary fibroepithelial neoplasms. Tissue microarrays containing 168 primary breast tumors were subjected to IHC for Sox10. The extent of nuclear Sox10 labeling was scored by percentage labeling as follows: 0 (0%), 1+ (1%-25%), 2+ (25%-50%), 3+ (50%-75%), and 4+ (>75%). Overall, 40 (40%) of 100 invasive breast carcinomas demonstrated Sox10 immunoreactivity, which was seen primarily in the basal-like, unclassified triple-negative, and metaplastic carcinomas. Sox10 labeling was seen in 66% (38/58) of the basal-like, unclassified triple-negative, and metaplastic carcinomas as compared with 5% (2/42) of the luminal A, luminal B, and Her-2 carcinomas (P < .00001). Sox10 labeling was seen in 1 (4%) of 24 cases of ductal carcinoma in situ, which was negative for estrogen receptor/progesterone receptor. No labeling was seen in the stromal component of phyllodes tumors or fibroadenomas. These findings show that breast carcinoma must be considered in the differential diagnosis of melanoma for an S100-positive, Sox10-positive metastatic malignant neoplasm. Sox10 expression in the basal-like, unclassified triple-negative, and metaplastic carcinomas types supports the concept that these neoplasms show myoepithelial differentiation.

Immunohistochemical profile and morphology in triple - negative breast cancers

BACKGROUND AND PURPOSE

Triple Negative Breast Cancer (TNBC) is defined by a lack of expression of the steroid hormone receptors (oestrogen and progesterone), and the human epidermal growth factor receptor-2 (HER-2). It is characterized by distinct molecular, histological and clinical features. It is a high risk breast cancer that lacks the benefit of a specific therapy. Our study was aimed at pathologically illustrating triple-negative breast carcinoma and at evaluating the expression of the Epidermal Growth Factor Receptor (EGFR) ,cytokeratin 5/6 (CK 5/6) and Ki-67 among triple-negative breast cancer cases. Further, we aimed to probe whether triple-negative phenotype could be a surrogate marker for the basal phenotype and to correlate the expression of the basal markers (CK 5/6 and EGFR) with the clinico-pathological prognostic parameters.

METHODS

The expression of EGFR, CK 5/6 and Ki-67 were studied by immunohistochemistry (IHC) in 50 triple-negative breast cancer cases.

STATISTICAL ANALYSIS

A statistical analysis was implemented by using the SPSS version 20.0. The Chi-square test was conducted to assess the relationship between the immunohistochemical markers and other variables. The Fischer exact test was used when the expected cell counts were less than 5.

RESULTS

The women with triple-negative breast cancer were younger, with the adverse pathological characteristics of a high tumour grade, tumour necrosis, frequent nodal metastases and high proliferation. 37 (74%) of the 50 triple-negative breast carcinomas showed the expression of the basal markers (EGFR and /or CK 5/6). We observed a statistically significant association between the basal marker expression and the presence of tumour necrosis.

CONCLUSION

The triple-negative breast cancers in our population harbour adverse pathobiological features and a five marker immunohistochemical panel can be reliably used to define the basal-like cancers. The "Triple-negative" status cannot be used as a surrogate for the "basal marker expression".

Specific siRNA targeting receptor for advanced glycation end products (RAGE) decreases proliferation in human breast cancer cell lines

Receptor for Advanced Glycation End Products (RAGE) is an oncogenic trans-membranous receptor overexpressed in various human cancers. However, the role of RAGE in breast cancer development and proliferation is still unclear. In this study, we demonstrated that RAGE expression levels are correlated to the degree of severity of breast cancer. Furthermore, there is a decrease in the proliferation of all sub-types of breast cancer, MCF-7, SK-Br-3 and MDA-MB-231, as a result of the effect of RAGE siRNA. RAGE siRNA arrested cells in the G1 phase and inhibited DNA synthesis (p < 0.05). Moreover, qRT-PCR and Western Blot results demonstrated that RAGE siRNA decreases the expression of transcriptional factor NF-κB p65 as well as the expression of cell proliferation markers PCNA and cyclinD1. RAGE and RAGE ligands can thus be considered as possible targets for breast cancer management and therapy.

Genomic classifications and radiotherapy for breast cancer

The current therapeutic strategy in breast cancer rests on standard prognostic factors such as size, histological grade, nodal and hormone receptor status. However, over the last decade, a new form of molecular classification has emerged to complement the classical clinico-pathological staging. Models based on tumour genome have been developped to help predict the risk of relapse, and are currently being evaluated. This improved risk stratification tool would enable the identification of patients who would benefit from systemic as well as local treatments. This paper aims to give an overview of the radiobiological implications in particular of this new classification, by looking at on the one hand, predictors of local relaspe, and on the other hand, the modulation in radiotherapy according to molecular type.

Clinicopathological significance of ERCC1 expression in breast cancer

The excision repair cross-complementation 1 (ERCC1) enzyme plays an essential role in the nucleotide excision repair pathway and is associated with resistance to platinum-based chemotherapy in different types of cancer. The aim of the present study was to evaluate the clinicopathological significance of ERCC1 expression in breast cancer patients. We analyzed the immunohistochemical expression of ERCC1 in a tissue microarray from 135 primary breast carcinomas and correlated the immunohistochemical findings with clinicopathological factors and outcome data. ERCC1 expression analysis was available for 109 cases. In this group, 58 (53.2%) were positive for ERCC1. ERCC1-positive expression was correlated with smaller tumor size (P=0.007) and with positivity for estrogen receptor (P=0.040), but no correlation was found with other clinicopathological features. Although not statistically significant, triple negative breast cancers were more frequently negative for ERCC1 (61.5% of the cases) compared to the non-triple negative breast cancer cases (41.5%). In conclusion, ERCC1 expression correlated significantly with favorable prognostic factors, such as smaller tumor size and ER-positivity, suggesting a possible role for ERCC1 as a predictive and/or prognostic marker in breast cancer.

Molecular alterations in metaplastic breast carcinoma

Metaplastic carcinoma of the breast is a rare and heterogeneous subtype of breast carcinoma with a generally poor outcome, and few therapeutic options once disease recurs or progresses. Metaplastic carcinomas of the breast are usually of a larger size at diagnosis, with less frequent nodal metastasis compared with invasive ductal carcinoma no special type, and lack hormone and HER2 receptor expression. Recent research has revealed some potentially actionable genetic changes in a subset of these rare tumours. However, ongoing efforts to further characterise the genetic basis and the molecular alterations underlying the distinctive morphological and clinical characteristics of these tumours are needed in order to identify new targets for treatment. This review will describe the theories of pathogenesis of metaplastic breast carcinoma, and highlight genetic changes and potential therapeutic targets in this generally poor prognosis malignancy.

Molecular pathology of breast cancer: what a pathologist needs to know

Pathologists are now more than ever "diagnostic oncologists" and serve a critical role as clinical consultants on the biology of disease. In the last decade and a half, molecular information has transformed our thinking about the biologic diversity of breast cancers and redirected the way clinical treatment decisions are made. A basic understanding of the current molecular classification of breast cancers and the biologic pathways from precursors to invasive disease is key to both informing diagnostic practice and serving as clinical consultants. In addition, both single-marker and panel-based molecular tests are currently being utilized in breast cancer tissue to predict the benefit of specific therapies such as HER2-targeted biologic therapy and chemotherapy. Familiarity with the current issues involving these molecular tests as well as the pathologist's role in ensuring appropriate tissue handling, tissue selection, and results interpretation and correlation are paramount to providing optimal patient care.

Molecular Pathology of the Breast

Information focuses on molecular pathology of breast cancer. Presented are clinical features of breast cancer, detailed discussion of histology and molecular pathology for invasive ductal carcinoma, invasive lobular carcinoma, other subtypes of invasive breast cancer, and breast cancer progression and precursors. Phenotypes and genotypes of breast cancer are presented, along with the role of biomarkers, gene profiling, and hormone receptors. Targeted therapies and prognostic indicators are presented with practical applications of molecular pathology for the surgical pathologist.

Proteomic profiling of triple-negative breast carcinomas in combination with a three-tier orthogonal technology approach identifies Mage-A4 as potential therapeutic target in estrogen receptor negative breast cancer

Breast cancer is a very heterogeneous disease, encompassing several intrinsic subtypes with various morphological and molecular features, natural history and response to therapy. Currently, molecular targeted therapies are available for estrogen receptor (ER)(-) and human epidermal growth factor receptor 2 (Her2)-positive breast tumors. However, a significant proportion of primary breast cancers are negative for ER, progesterone receptor (PgR), and Her2, comprising the triple negative breast cancer (TNBC) group. Women with TNBC have a poor prognosis because of the aggressive nature of these tumors and current lack of suitable targeted therapies. As a consequence, the identification of novel relevant protein targets for this group of patients is of great importance. Using a systematic two dimensional (2D) gel-based proteomic profiling strategy, applied to the analysis of fresh TNBC tissue biopsies, in combination with a three-tier orthogonal technology (two dimensional PAGE/silver staining coupled with MS, two dimensional Western blotting, and immunohistochemistry) approach, we aimed to identify targetable protein markers that were present in a significant fraction of samples and that could define therapy-amenable sub-groups of TNBCs. We present here our results, including a large cumulative database of proteins based on the analysis of 78 TNBCs, and the identification and validation of one specific protein, Mage-A4, which was expressed in a significant fraction of TNBC and Her2-positive/ER negative lesions. The high level expression of Mage-A4 in the tumors studied allowed the detection of the protein in the tumor interstitial fluids as well as in sera. The existence of immunotherapeutics approaches specifically targeting this protein, or Mage-A protein family members, and the fact that we were able to detect its presence in serum suggest novel management options for TNBC and human epidermal growth factor receptor 2 positive/estrogen receptor negative patients bearing Mage-A4 positive tumors.

Predictors of pathologic complete response after standard neoadjuvant chemotherapy in triple-negative breast carcinoma

The objective of this study was to identify predictors of pathologic complete response and tumor volume reduction in triple-negative breast carcinomas. Consecutive cases of 101 triple-negative carcinomas within the last 3 years treated with standard neoadjuvant chemotherapy were identified. However, 56 cases with sufficient material available (for tissue microarray construction) in the pretherapy core biopsy tissue blocks formed the basis of this study. The pretherapy tumor core biopsy slides were examined for various morphologic features including tumor grade. The tumors were immunohistochemically examined for basal phenotype markers (CK5, CK14, CK17, epidermal growth factor receptor), cell adhesion marker E-cadherin, and proliferation marker Ki-67. The overall rate of pathologic complete response was 34% (19 of 56). Neither any morphologic feature nor any basal marker reactivity predicted for pathologic complete response or >50% tumor volume reduction. Ki-67 proliferation index also failed as a predictive marker. Reduced E-cadherin expression (defined as H score ≤200) was initially seen in 47% of cases with pathologic complete response and in only 6% of cases that failed to achieve pathologic complete response (P=0.001); however, in additional 20 cases from a separate validation set, no such difference was identified. Basal marker reactivity in triple-negative breast carcinomas does not predict pathologic complete response after neoadjuvant chemotherapy. As vast majority of triple-negative tumors are highly proliferative, Ki-67 proliferation index appears to have negligible clinical value in predicting pathologic complete response. E-cadherin expression as a predictor of pathologic complete response in triple-negative tumors should be further assessed on larger number of cases.

Mutation analysis of BRCA1, BRCA2, PALB2 and BRD7 in a hospital-based series of German patients with triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive form of breast carcinoma with a poor prognosis. Recent evidence suggests that some patients with TNBC harbour germ-line mutations in DNA repair genes which may render their tumours susceptible to novel therapies such as treatment with PARP inhibitors. In the present study, we have investigated a hospital-based series of 40 German patients with TNBC for the presence of germ-line mutations in BRCA1, BRCA2, PALB2, and BRD7 genes. Microfluidic array PCR and next-generation sequencing was used for BRCA1 and BRCA2 analysis while conventional high-resolution melting and Sanger sequencing was applied to study the coding regions of PALB2 and BRD7, respectively. Truncating mutations in BRCA1 were found in six patients, and truncating mutations in BRCA2 and PALB2 were detected in one patient each, whereas no truncating mutation was identified in BRD7. One patient was a double heterozygote for the PALB2 mutation, c.758insT, and a BRCA1 mutation, c.927delA. Our results confirm in a hospital-based setting that a substantial proportion of German TNBC patients (17.5%) harbour germ-line mutations in genes involved in homology-directed DNA repair, with a preponderance of BRCA1 mutations. Triple-negative breast cancer should be considered as an additional criterion for future genetic counselling and diagnostic sequencing.

Thymosin beta 15A (TMSB15A) is a predictor of chemotherapy response in triple-negative breast cancer

Background:

Biomarkers predictive of pathological complete response (pCR) to neoadjuvant chemotherapy (NACT) of breast cancer are urgently needed.

Methods:

Using a training/validation approach for detection of predictive biomarkers in HER2-negative breast cancer, pre-therapeutic core biopsies from four independent cohorts were investigated: Gene array data were analysed in fresh frozen samples of two cohorts (n=86 and n=55). Quantitative reverse transcription polymerase chain reaction (qRT–PCR) was performed in formalin-fixed, paraffin-embedded (FFPE) samples from two neoadjuvant phase III trials (GeparTrio, n=212, and GeparQuattro, n=383).

Results:

A strong predictive capacity of thymosin beta 15 (TMSB15A) gene expression was evident in both fresh frozen cohorts (P<0.0001; P<0.0042). In the GeparTrio FFPE training cohort, a significant linear correlation between TMSB15A expression and pCR was apparent in triple-negative breast cancer (TNBC) (n=61, P=0.040). A cutoff point was then defined that divided TNBC into a low and a high expression group (pCR rate 16.0% vs 47.2%). Both linear correlation of TMSB15A mRNA levels (P=0.017) and the pre-defined cutoff point were validated in 134 TNBC from GeparQuattro (pCR rate 36.8% vs 17.0%, P=0.020). No significant predictive capacity was observed in luminal carcinomas from GeparTrio and GeparQuattro.

Conclusion:

In TNBC, TMSB15A gene expression analysis might help to select patients with a high chance for pCR after NACT.

Participation in adjuvant clinical breast cancer trials: does study participation improve survival compared to guideline adherent adjuvant treatment? A retrospective multi-centre cohort study of 9,433 patients

Adjuvant clinical trials (CTs) usually compare a standard treatment regime versus an innovative new substance or regimen. Participation in CT however, is available for only few patients and exclusion criteria are usually very strict. Therefore we used an unselected patient cohort to investigate the following questions:

MATERIAL AND METHODS

This German retrospective multi-centre cohort study included 9433 patients with primary breast cancer recruited from 1992 to 2008.

RESULTS

One thousand two hundred and fifty-five (13.3%) patients participated in adjuvant clinical trials (PA) and 8178 (86.7%) did not (NPA). RFS was higher among participants (PA) than among non-participants (NPA) [p=0.006], but differences in overall survival (OAS) were not significant [p=0.15]. When stratified for guideline adherence, the outcome was not different for guideline conform NPA [RFS: p=0.88] [OAS: p=0.37] compared to PA. Survival parameters however, were significantly poorer in non-guideline conform PA [RFS: p<0.001] [OAS: p<0.001] and non-guideline conform NPA [RFS: p<0.001] [OAS: p<0.001] as compared to guideline adherent PA.

DISCUSSION

There is a strong association between guideline adherence in adjuvant treatment in BC and survival. PA in clinical trials tended to higher survival rates, but only if guideline-adherent treatment was applied. Patients who do not have access to clinical trials may profit substantially from guideline-adherent adjuvant treatment.

Cancer stem cell marker Bmi-1 expression is associated with basal-like phenotype and poor survival in breast cancer

BACKGROUND

The purpose of present study was to examine the expression of cancer stem cell marker Bmi-1 in breast cancer tissue and to evaluate the clinical implication of Bmi-1 expression for these patients.

METHODS

A total of 171 breast cancer patients who received surgical treatment in our hospital were enrolled in this study. Bmi-1 expression in breast cancer tissue was assayed by immunohistochemistry. Statistical analyses were applied to test the relationship between expression of Bmi-1 and clinicopathologic features and patient survival. The relationship between Bmi-1 and the basal-like phenotype of breast cancer also was analyzed in this study.

RESULTS

Positive Bmi-1 expression was detected in 89 of 171 (52%) invasive breast cancers patients. The Bmi-1 status was significantly correlated to histological grade III (p = 0.001) and basal-like phenotype (p < 0.001). The 5 year overall survival of the patients with Bmi-1-positive and -negative cancers were 78 and 91.9%, respectively (p = 0.03). Histological grade (p = 0.046) and Bmi-1 status (p = 0.012) were detected as the independent prognostic factors in the Cox regression test.

CONCLUSIONS

Bmi-1 status is an independent prognostic factor, which also is associated with tumor histological grade and basal-like phenotype. The high proportions of positive Bmi-1 expression in basal-like breast cancer may be related to the high aggressiveness behavior of this subtype of breast cancer.

Protein expression changes during human triple negative breast cancer cell line progression to lymph node metastasis in a xenografted model in nude mice

Triple negative breast cancers (TNBC) lacking hormone receptors and HER-2 amplification are very aggressive tumors. Since relevant differences between primary tumors and metastases could arise during tumor progression as evidenced by phenotypic discordances reported for hormonal receptors or HER-2 expression, in this analysis we studied changes that occurred in our TNBC model IIB-BR-G throughout the development of IIB-BR-G-_MTS6 metastasis to the lymph nodes (LN) in nude mice, using an antibody-based protein array to characterize their expression profile. We also analyzed their growth kinetics, migration, invasiveness and cytoskeleton structure in vitro and in vivo.

In vitro IIB-BR-G-_MTS6 cells grew slower but showed higher anchorage independent growth. In vivo IIB-BR-G-_MTS6 tumors grew significantly faster and showed a 100% incidence of LN metastasis after s.c. inoculation, although no metastasis was observed for IIB-BR-G. CCL3, IL1β, CXCL1, CSF2, CSF3, IGFBP1, IL1α, IL6, IL8, CCL20, PLAUR, PlGF and VEGF were strongly upregulated in IIB-BR-G-_MTS6 while CCL4, ICAM3, CXCL12, TNFRSF18, FIGF were the most downregulated proteins in the metastatic cell line. IIB-BR-G-_MTS6 protein expression profile could reflect a higher NFκB activation in these cells. In vitro, IIB-BR-G displayed higher migration but IIB-BR-G-_MTS6 had more elevated matrigel invasion ability. In agreement with that observation, IIB-BR-G-_MTS6 had an upregulated expression of MMP1, MMP9, MMP13, PLAUR and HGF. IIB-BR-G-_MTS6 tumors presented also higher local lymphatic invasion than IIB-BR-G but similar lymphatic vessel densities. VEGFC and VEGFA/B expression were higher both in vitro and in vivo for IIB-BR-G-_MTS6. IIB-BR-G-_MTS6 expressed more vimentin than IB-BR-G cells, which was mainly localized in the cellular extremities and both cell lines are E-cadherin negative.

Our results suggest that IIB-BR-G-_MTS6 cells have acquired a pronounced epithelial-to-mesenchymal transition phenotype. Protein expression changes observed between primary tumor-derived IIB-BR-G and metastatic IIB-BR-G-_MTS6 TNBC cells suggest potential targets involved in the control of metastasis.

Cancer stem cell marker Bmi-1 expression is associated with basal-like phenotype and poor survival in breast cancer

BACKGROUND

The purpose of present study was to examine the expression of cancer stem cell marker Bmi-1 in breast cancer tissue and to evaluate the clinical implication of Bmi-1 expression for these patients.

METHODS

A total of 171 breast cancer patients who received surgical treatment in our hospital were enrolled in this study. Bmi-1 expression in breast cancer tissue was assayed by immunohistochemistry. Statistical analyses were applied to test the relationship between expression of Bmi-1 and clinicopathologic features and patient survival. The relationship between Bmi-1 and the basal-like phenotype of breast cancer also was analyzed in this study.

RESULTS

Positive Bmi-1 expression was detected in 89 of 171 (52%) invasive breast cancers patients. The Bmi-1 status was significantly correlated to histological grade III (p = 0.001) and basal-like phenotype (p < 0.001). The 5 year overall survival of the patients with Bmi-1-positive and -negative cancers were 78 and 91.9%, respectively (p = 0.03). Histological grade (p = 0.046) and Bmi-1 status (p = 0.012) were detected as the independent prognostic factors in the Cox regression test.

CONCLUSIONS

Bmi-1 status is an independent prognostic factor, which also is associated with tumor histological grade and basal-like phenotype. The high proportions of positive Bmi-1 expression in basal-like breast cancer may be related to the high aggressiveness behavior of this subtype of breast cancer.

Metaplastic and medullary mammary carcinomas do not express mammaglobin

Mammaglobin A (MG-A) is purportedly useful for detecting metastatic carcinomas suspected to be of breast origin and has been advocated as a useful marker of micrometastasis in sentinel lymph nodes and minimal residual tumor in bone marrow. Little is known about its expression frequency in histologic subtypes of breast cancer. Excisional biopsy specimens from 1,079 untreated invasive mammary carcinomas were evaluated for immunohistochemical expression of MG-A. In addition to estrogen (ER) and progesterone receptors (PR) and HER2, staining for p63 and HLA-DR was used to further characterize histologic subtypes. Of the carcinomas, 36 were classified as metaplastic (based on morphologic features, ER-/PR-/HER2-, p63+), 38 as medullary (ER-/PR-/HER2-, HLA-DR+), and 1,005 as ductal, no special type (NST). All metaplastic and medullary carcinomas were negative for MG-A. Of 1,005 ductal carcinomas, NST, 492 (49.0%) were MG-A+, 62.0% with a reaction in fewer than 25% of the cells. MG-A immunohistochemical studies failed to detect all medullary and metaplastic cancers and more than 50% of ductal carcinomas, NST. In two thirds of MG-A+ ductal carcinomas, the reaction was only focal and usually in a minority of cells. These findings suggest that MG-A has limited value in identifying the mammary origin of carcinomas, particularly in small biopsy specimens used to detect metastasis or minimal residual disease.