P-cadherin and cytokeratin 5: useful adjunct markers to distinguish basal-like ductal carcinomas in situ

Canine mammary tumors as a promising adjunct preclinical model for human breast cancer research: similarities, opportunities, and challenges

Despite significant progress in the field of human breast cancer research and treatment, there is a consistent increase in the incidence rate of 0.5 percent annually, posing challenges in the development of effective novel therapeutic strategies. The failure rate of drugs in clinical trials stands at approximately 95%, primarily attributed to the limitations and lack of reliability of existing preclinical models, such as mice, which do not mimic human tumor biology. This article examines the potential utility of canine mammary tumors as an adjunct preclinical model for investigating human breast cancer. Given the numerous similarities between canine and human breast cancer, canines present a promising alternative model. The discussion delves into the intricate molecular and clinical aspects of human breast cancer and canine mammary tumors, shedding light on the tumors' molecular profiles, identifying specific molecular markers, and the application of radiological imaging modalities. Furthermore, the manuscript addresses the current constraints of preclinical cancer studies, the benefits of using canines as models, and the obstacles linked to the canine mammary tumors model. By concentrating on these elements, this review aims to highlight the viability of canine models in enhancing our understanding and management of human breast cancer.

Breast cancer prognosis and P-cadherin expression: systematic review and study-level meta-analysis

OBJECTIVE

P-cadherin can act both as a tumour suppressor and an oncogene. The clinical prognostic value of P-cadherin overexpression in breast cancer (BC) remains unclear. We conducted a study-level meta-analysis to determine whether P-cadherin expression can help predict prognosis in BC.

METHODS

A systematic literature search was performed to review eligible studies and clarify the relationship between P-cadherin overexpression and overall survival (OS), disease-free survival (DFS), pathological features, molecular subtypes and molecular phenotypes in BC.

RESULTS

Thirty-one studies including 12 332 patients were included. P-cadherin overexpression was correlated with significantly worse OS (HR=1.77, p<0.00001) and DFS (HR=1.96, p<0.00001) than P-cadherin-negative. P-cadherin overexpression could lead to high histological grade (OR=3.33, p<0.00001) and lymph node metastasis (OR=1.62, p<0.00001). Moreover, P-cadherin overexpression was associated with low odds of the luminal A subtype and high odds of the human epidermal growth factor receptor-2 (HER2)-positive and triple-negative subtypes. P-cadherin expression led to low expression of oestrogen and progesterone receptor (OR=0.37 and OR=0.36, respectively, both p<0.00001) and high expression of HER2 (OR=2.31, p<0.00001), Ki-67 (OR=2.79, p<0.00001), epidermal growth factor receptor (OR=5.85, p<0.00001) and cytokeratin 5/6 (OR=6.79, p<0.00001).

CONCLUSIONS

P-cadherin was found to be associated with invasiveness and metastasis. P-cadherin expression can probably be a useful biomarker for predicting poor survival and may act as an independent prognostic predictor.

BR-BCSC Signature: The Cancer Stem Cell Profile Enriched in Brain Metastases that Predicts a Worse Prognosis in Lymph Node-Positive Breast Cancer

Brain metastases remain an unmet clinical need in breast oncology, being frequently found in HER2-overexpressing and triple-negative carcinomas. These tumors were reported to be highly cancer stem-like cell-enriched, suggesting that brain metastases probably arise by the seeding of cancer cells with stem features. Accordingly, we found that brain-tropic breast cancer cells show increased stem cell activity and tumorigenic capacity in the chick embryo choriallantoic membrane when compared to the parental cell line. These observations were supported by a significant increase in their stem cell frequency and by the enrichment for the breast cancer stem cell (BCSC) phenotype CD44⁺CD24^−/low. Based on this data, the expression of BCSC markers (CD44, CD49f, P-cadherin, EpCAM, and ALDH1) was determined and found to be significantly enriched in breast cancer brain metastases when compared to primary tumors. Therefore, a brain (BR)-BCSC signature was defined (3–5 BCSC markers), which showed to be associated with decreased brain metastases-free and overall survival. Interestingly, this signature significantly predicted a worse prognosis in lymph node-positive patients, acting as an independent prognostic factor. Thus, an enrichment of a BCSC signature was found in brain metastases, which can be used as a new prognostic factor in clinically challenging breast cancer patients.

Canine mammary tumors as a model for human disease

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

Breast cancer complexity: implications of intratumoral heterogeneity in clinical management

Generation of intratumoral phenotypic and genetic heterogeneity has been attributed to clonal evolution and cancer stem cells that together give rise to a tumor with complex ecosystems. Each ecosystem contains various tumor cell subpopulations and stromal entities, which, depending upon their composition, can influence survival, therapy responses, and global growth of the tumor. Despite recent advances in breast cancer management, the disease has not been completely eradicated as tumors recur despite initial response to treatment. In this review, using data from clinically relevant breast cancer models, we show that the fates of tumor stem cells/progenitor cells in the individual tumor ecosystems comprising a tumor are predetermined to follow a limited (unipotent) and/or unlimited (multipotent) path of differentiation which create conditions for active generation and maintenance of heterogeneity. The resultant dynamic systems respond differently to treatments, thus disrupting the delicate stability maintained in the heterogeneous tumor. This raises the question whether it is better then to preserve stability by preventing takeover by otherwise dormant ecosystems in the tumor following therapy. The ultimate strategy for personalized therapy would require serial assessments of the patient's tumor for biomarker validation during the entire course of treatment that is combined with their three-dimensional mapping to the tumor architecture and landscape.

P-cadherin: a useful biomarker for axillary-based breast cancer decisions in the clinical practice

Axillary lymph node metastases represent the most powerful breast cancer prognostic factor, dictating disease staging and clinical therapeutic decisions. Nonetheless, breast cancer patients with positive lymph nodes still exhibit a heterogeneous behavior regarding disease progression. Stem-like subpopulations of cancer cells show high migratory and metastatic capacity, thus we hypothesize that breast cancer stem cell markers evaluation in metastasized lymph nodes could provide a more accurate prediction of patient's prognosis. Therefore, the expression profile of P-cadherin, CD44, and CD49f, which have been already associated to stem cell properties in breast cancer, has been evaluated by immunohistochemistry in a series of 135 primary tumors and matched axillary lymph node metastases from 135 breast cancer patients. Taking in consideration the expression of the stem cell markers only in axillary nodes, P-cadherin was the only biomarker significantly associated with poor disease-free and overall patient's survival. Moreover, although a concordant expression between primary tumors and matched lymph nodes has been found in the majority of the cases, a small but significant percentage displayed divergent expression (18.2-26.2%). Remarkably, although CD44 and CD49f changes between primary tumors and lymph node metastasis did not impact survival, the cases that were positive for P-cadherin in lymph node metastases being negative in the primary tumor, presented the worst disease-free and overall survival of the whole series. Accordingly, negative cases for this marker in the lymph nodes with positive expression in the matched breast carcinoma demonstrated a better prognosis, which overlapped with tumors that were negative in both sites. P-cadherin and CD49f gain of expression was mainly found in triple-negative carcinomas. Our results indicate for the first time that the evaluation of P-cadherin expression in lymph node metastases is an important predictor of disease outcome, being a putative valuable marker for axillary-based breast cancer decisions in the clinical practice.

P-cadherin and the journey to cancer metastasis

P-cadherin is a classical cell-to-cell adhesion molecule with a homeostatic function in several normal tissues. However, its behaviour in the malignant setting is notably dependent on the cellular context. In some tumour models, such as melanoma and oral squamous cell carcinoma, P-cadherin acts as a tumour suppressor, since its absence is associated with a more aggressive cancer cell phenotype; nevertheless, the overexpression of this molecule is linked to significant tumour promoting effects in the breast, ovarian, prostate, endometrial, skin, gastric, pancreas and colon neoplasms. Herein, we review the role of P-cadherin in cancer cell invasion, as well as in loco-regional and distant metastatic dissemination. We focus in P-cadherin signalling pathways that are activated to induce invasion and metastasis, as well as cancer stem cell properties. The signalling network downstream of P-cadherin is notably dependent on the cellular and tissue context and includes the activation of integrin molecules, receptor tyrosine kinases, small molecule GTPases, EMT transcription factors, and crosstalk with other cadherin family members. As new oncogenic molecular pathways mediated by P-cadherin are uncovered, putative therapeutic options can be tested, which will allow for the targeting of invasion or metastatic disease, depending on the tumour model.

Steroid induction of therapy-resistant cytokeratin-5-positive cells in estrogen receptor-positive breast cancer through a BCL6-dependent mechanism

Therapy resistance remains a major problem in estrogen receptor-α (ERα)-positive breast cancer. A subgroup of ERα-positive breast cancer is characterized by mosaic presence of a minor population of ERα-negative cancer cells expressing the basal cytokeratin-5 (CK5). These CK5-positive cells are therapy resistant and have increased tumor-initiating potential. Although a series of reports document induction of the CK5-positive cells by progestins, it is unknown if other 3-ketosteroids share this ability. We now report that glucocorticoids and mineralocorticoids effectively expand the CK5-positive cell population. CK5-positive cells induced by 3-ketosteroids lacked ERα and progesterone receptors, expressed stem cell marker, CD44, and displayed increased clonogenicity in soft agar and broad drug-resistance in vitro and in vivo. Upregulation of CK5-positive cells by 3-ketosteroids required induction of the transcriptional repressor BCL6 based on suppression of BCL6 by two independent BCL6 small hairpin RNAs or by prolactin. Prolactin also suppressed 3-ketosteroid induction of CK5+ cells in T47D xenografts in vivo. Survival analysis with recursive partitioning in node-negative ERα-positive breast cancer using quantitative CK5 and BCL6 mRNA or protein expression data identified patients at high or low risk for tumor recurrence in two independent patient cohorts. The data provide a mechanism by which common pathophysiological or pharmacologic elevations in glucocorticoids or other 3-ketosteroids may adversely affect patients with mixed ERα+/CK5+ breast cancer. The observations further suggest a cooperative diagnostic utility of CK5 and BCL6 expression levels and justify exploring efficacy of inhibitors of BCL6 and 3-ketosteroid receptors for a subset of ERα-positive breast cancers.

Co-Expression of p16, Ki67 and COX-2 Is Associated with Basal Phenotype in High-Grade Ductal Carcinoma In Situ of the Breast

We assessed the co-expression of cell cycle-related biomarkers in a series of 121 consecutive cases of high-grade ductal carcinoma in situ (DCIS), pure or associated with invasive carcinoma, and their associations with the different immunoprofiles of DCIS. Cases were identified from the histopathology files of the Breast Pathology Laboratory, Federal University of Minas Gerais, Brazil, from 2003 to 2008. The expression of estrogen receptor, progesterone receptor, HER2 overexpression, cytokeratin 5, epidermal growth factor receptor 1, cyclooxygenase-2, p16 and Ki67 were assessed. Tumors were placed into five subgroups according to their immunohistochemical profile: luminal A, luminal B, HER2, basal-like and "not classified". We found that the basal phenotype was associated with a higher frequency of p16-positive cases (83%) and the luminal A phenotype showed a higher frequency of p16-negative cases (93%; p=0.000). The association of biomarkers p16(+)/Ki67(+)/COX2(+) was expressed in 02/06 cases (33.3%) of the basal phenotype but in only 01/70 cases (1.4%) of the luminal A phenotype (p=0.01). The co-expression of p16(+)/Ki67(+)/COX2(-) was associated with a basal phenotype (p=0.004). P16 expression, p16(+)/Ki67(+)/COX2(+) and p16(+)/Ki67(+)/COX2(-) co-expression showed significant associations with the basal phenotype and these profiles could be used to guide more aggressive treatment strategies in patients with high-grade DCIS.

Ductal carcinoma in situ of the breast: correlation between histopathological features and age of patients

Background

The histopathological subtype, nuclear grade and presence or absence of comedonecrosis are established as critical elements in the reporting of ductal carcinoma in situ (DCIS) of the breast. The aims of this study were to determine the frequencies of morphological subtypes of DCIS, nuclear grade and comedonecrosis; to compare the age of patients with the histopathological characteristics of DCIS, and to assess the agreement of grade between in situ and invasive components in DCIS cases that were associated with invasive carcinoma.

Methods

We evaluated a series of 403 cases of DCIS, pure or associated with invasive mammary carcinoma, consecutively identified from the histopathology files of the Breast Pathology Laboratory, Federal University of Minas Gerais, Brazil, from 2003 to 2008.

Results

DCIS displayed a single growth pattern in most cases (55.1%) and the solid subtype was the most common morphology (42.2% of the total). High-grade DCIS was identified in 293/403 cases (72.7%) and comedonecrosis was present in 222/403 cases (55%). Among DCIS with a single architectural pattern, high grade was more common in the solid subtype (151/168 cases, 89.9%; p < 0.001). Only 32% of tumours with a cribriform pattern had high nuclear grade. Comedonecrosis was more common in the solid morphology than in the cribriform, papillary and micropapillary subtypes (p < 0.001). Patients with high-grade DCIS were younger in relation to patients with low-grade DCIS (p = 0.027) and patients with tumours with comedonecrosis were also younger in comparison to patients with tumours without comedonecrosis (p = 0.003). Fair agreement was observed between in situ and invasive components with regard to grade (weighted kappa = 0.23).

Conclusions

The high nuclear grade and the presence of comedonecrosis were identified more frequently in younger patients and more often correlated with the solid pattern of DCIS.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_227

Aberrant P-cadherin expression is associated to aggressive feline mammary carcinomas

BACKGROUND

Cadherins are calcium-dependent cell-to-cell adhesion glycoproteins playing a critical role in the formation and maintenance of normal tissue architecture. In normal mammary gland, E-cadherin is expressed by luminal epithelial cells, while P-cadherin is restricted to myoepithelial cells. Changes in the expression of classical E- and P-cadherins have been observed in mammary lesions and related to mammary carcinogenesis. P-cadherin and E-cadherin expressions were studied in a series of feline normal mammary glands, hyperplastic/dysplastic lesions, benign and malignant tumours by immunohistochemistry and double-label immunofluorescence.

RESULTS

In normal tissue and in the majority of hyperplastic/dysplastic lesions and benign tumours, P-cadherin was restricted to myoepithelial cells, while 80% of the malignant tumours expressed P-cadherin in luminal epithelial cells. P-cadherin expression was significantly related to high histological grade of carcinomas (p <0.0001), tumour necrosis (p = 0.001), infiltrative growth (p = 0.0051), and presence of neoplastic emboli (p = 0.0401). Moreover, P-cadherin positive carcinomas had an eightfold likelihood of developing neoplastic emboli than negative tumours. Cadherins expression profile in high grade and in infiltrative tumours was similar, the majority expressing P-cadherin, regardless of E-cadherin expression status. The two cadherins were found to be co-expressed in carcinomas with aberrant P-cadherin expression and preserved E-cadherin.

CONCLUSIONS

The results demonstrate a relationship between P-cadherin expression and aggressive biological behaviour of feline mammary carcinomas, suggesting that P-cadherin may be considered an indicator of poor prognosis in this animal species. Moreover, it indicates that, in queens, the aberrant expression of P-cadherin is a better marker of mammary carcinomas aggressive behaviour than the reduction of E-cadherin expression. Further investigation with follow-up studies in feline species should be conducted in order to evaluate the prognostic value of P-cadherin expression in E-cadherin positive carcinomas.

The basal epithelial marker P-cadherin associates with breast cancer cell populations harboring a glycolytic and acid-resistant phenotype

Background

Cancer stem cells are hypoxia-resistant and present a preponderant glycolytic metabolism. These characteristics are also found in basal-like breast carcinomas (BLBC), which show increased expression of cancer stem cell markers.

Recently, we demonstrated that P-cadherin, a biomarker of BLBC and a poor prognostic factor in this disease, mediates stem-like properties and resistance to radiation therapy. Thus, the aim of the present study was to evaluate if P-cadherin expression was associated to breast cancer cell populations with an adapted phenotype to hypoxia.

Methods

Immunohistochemistry was performed to address the expression of P-cadherin, hypoxic, glycolytic and acid-resistance biomarkers in primary human breast carcinomas. In vitro studies were performed using basal-like breast cancer cell lines. qRT-PCR, FACS analysis, western blotting and confocal microscopy were used to assess the expression of P-cadherin after HIF-1α stabilization, achieved by CoCl₂ treatment. siRNA-mediated knockdown was used to silence the expression of several targets and qRT-PCR was employed to evaluate the effects of P-cadherin on HIF-1α signaling. P-cadherin high and low breast cancer cell populations were sorted by FACS and levels of GLUT1 and CAIX were assessed by FACS and western blotting. Mammosphere forming efficiency was used to determine the stem cell activity after specific siRNA-mediated knockdown, further confirmed by western blotting.

Results

We demonstrated that P-cadherin overexpression was significantly associated with the expression of HIF-1α, GLUT1, CAIX, MCT1 and CD147 in human breast carcinomas. In vitro, we showed that HIF-1α stabilization was accompanied by increased membrane expression of P-cadherin and that P-cadherin silencing led to a decrease of the mRNA levels of GLUT1 and CAIX. We also found that the cell fractions harboring high levels of P-cadherin were the same exhibiting more GLUT1 and CAIX expression. Finally, we showed that P-cadherin silencing significantly decreases the mammosphere forming efficiency in the same range as the silencing of HIF-1α, CAIX or GLUT1, validating that all these markers are being expressed by the same breast cancer stem cell population.

Conclusions

Our results establish a link between aberrant P-cadherin expression and hypoxic, glycolytic and acid-resistant breast cancer cells, suggesting a possible role for this marker in cancer cell metabolism.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-734) contains supplementary material, which is available to authorized users.

Differential sensitivities to lactate transport inhibitors of breast cancer cell lines

The tumour microenvironment is known to be acidic due to high glycolytic rates of tumour cells. Monocarboxylate transporters (MCTs) play a role in extracellular acidification, which is widely known to be involved in tumour progression. Recently, we have described the upregulation of MCT1 in breast carcinomas and its association with poor prognostic variables. Thus, we aimed to evaluate the effect of lactate transport inhibition in human breast cancer cell lines. The effects of α-cyano-4-hydroxycinnamate, quercetin and lonidamine on cell viability, metabolism, proliferation, apoptosis, migration and invasion were assessed in a panel of different breast cancer cell lines. MCT1, MCT4 and CD147 were differently expressed among the breast cancer cell lines and, as expected, different sensitivities were observed for the three inhibitors. Interestingly, in the most sensitive cell lines, lactate transport inhibition induced a decrease in cell proliferation, migration and invasion, as well as an increase in cell death. Results were validated by silencing MCT1 expression using siRNA. The results obtained here support targeting of lactate transport as a strategy to treat breast cancer, with a special emphasis on the basal-like subtype, which so far does not have a specific molecular therapy.

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.

CD44/CD24 as potential prognostic markers in node-positive invasive ductal breast cancer patients treated with adjuvant chemotherapy

The hypothesis on cancer stem cells assumes the existence of small subpopulation of cells that possess the ability to undergo self-renewal and can give rise to the diversity of differentiated cells that form the tumour. It has been accepted that CD44(+)/CD24(-/low) phenotype is one of the features characterizing breast cancer stem cells. The aim of our study was to assess (1) prognostic significance of CD44/CD24 expression as well as (2) a relation between the above-mentioned phenotype and breast cancer subtypes [based on estrogen (ER), progesterone receptors, human epidermal growth factor receptor 2 and Ki67 status] and expression of selected markers such as fascin, laminin-5 gamma-2 chain, cytokeratin (CK) 5/6 and 8/18, epidermal growth factor receptor (EGFR), smooth muscle actin, P-cadherin and lymphocytic infiltration in invasive ductal breast cancer patients (T ≥ 1, N ≥ 1, M0), who underwent mastectomy followed by chemotherapy (with taxanes and/or anthracyclines) or/and hormonotherapy. We noted that most cancers with CD44-/CD24- and CD44-/CD24+ phenotype were ER positive. The majority of CD44-/CD24-, CD44-/CD24+ and CD44+/CD24- tumours were characterized by CK5/6 and EGFR negativity. In univariate analysis we demonstrated that patients with pN1/pN2 and with CD44 +/CD24- carcinomas had significantly lower risk of progression or cancer-related death than those with pN3 or tumours characterised by other CD44/CD24 expression patterns. We also found 100 % DFS in 12 patients with CD44+/CD24-/CK5/6+/ER- phenotype. Other analysed parameters were insignificant. We conclude that tumours with immunophenotypes: CD44+/CD24- and CD44+/CD24-/CK5/6+/ER- might be more sensitive for chemotherapy based on taxanes and/or anthracyclines.

Immunohistochemical profile of high-grade ductal carcinoma in situ of the breast

OBJECTIVE

To determine the frequency of the immunohistochemical profiles of a series of high-grade ductal carcinoma in situ of the breast.

METHODS

One hundred and twenty-one cases of high-grade ductal carcinoma in situ, pure or associated with invasive mammary carcinoma, were identified from 2003 to 2008 and examined with immunohistochemistry for estrogen receptor, human epidermal growth factor receptor 2, cytokeratin 5, and epidermal growth factor receptor. The tumors were placed into five subgroups: luminal A, luminal B, HER2, basal-like, and "not classified".

RESULTS

The frequencies of the immunophenotypes of pure ductal carcinoma in situ were the following: luminal A (24/42 cases; 57.1%), luminal B (05/42 cases; 11.9%), HER2 (07/42 cases; 16.7%), basal-like phenotype (00/42 cases; 0%), and "not classified" (06/42 cases; 14.3%). The immunophenotypes of ductal carcinoma in situ associated with invasive carcinoma were the following: luminal A (46/79 cases; 58.2%), luminal B (10/79 cases; 12.7%), HER2 (06/79 cases; 7.6%), basal-like (06/79 cases; 7.6%), and "not classified" (11/79 cases; 13.9%). There was no significant difference in the immunophenotype frequencies between pure ductal carcinoma in situ and ductal carcinoma in situ associated with invasive carcinoma (p>0.05). High agreement was observed in immunophenotypes between both components (kappa=0.867).

CONCLUSION

The most common immunophenotype of pure ductal carcinoma in situ was luminal A, followed by HER2. The basal-like phenotype was observed only in ductal carcinoma in situ associated with invasive carcinoma, which had a similar phenotype.

Characteristics of basal cytokeratin expression in breast cancer

Breast cancer is recognised to be a heterogeneous disease and the second most common cause of morbidity and mortality worldwide in women. Basal-like breast cancer (BLBC) is associated with aggressive characteristics including development of recurrent disease and reduced survival. BLBC has been defined in some studies as tumours lacking both oestrogen receptor and progesterone receptor protein expression. Gene expression studies have shown that these tumours are also associated with expression of basal-type cytokeratins, the phenotypic patterns of basal cytokeratin expression in BLBC have not been widely studied. A well-characterised series of 995 invasive breast cancers with a long-term follow up were investigated using immunohistochemical staining for four basal cytokeratins (CK5, CK5/6, CK14 and CK17). The data were analysed using univariate and clustering analysis. As a result BLBC, as defined by negativity for ER and HER2 showed variable positivity for basal cytokeratin expression: 61.7 % CK5, 50.5 % CK5/6, 24.2 % CK14 and 23 % CK17. These characteristics were associated with poor outcome characteristics including high histological grade, mitosis, pleomorphism and tumour size >1.5 cm. CK5 positivity was more associated with ER(-), PgR(-), TN and double ER(-)PgR(-), than the other cytokeratins. Four different clusters of basal cytokeratin expression patterns were identified: (1) negativity for all basal cytokeratins, (2) CK5(+)/CK17(-), (3) CK5(-)/CK17(+) and (4) CK5(+)/CK17(+). These patterns of basal cytokeratin expression associated with differences in patient outcome, clusters 1 and 3 showed better outcomes than cluster 4 and 2, with cluster 2 having the poorest prognosis. In conclusion, four basal cytokeratin expression patterns were identified in human breast cancer using unsupervised clustering analysis and these patterns are associated with differences in patient outcome.

CCAAT/enhancer binding protein β (C/EBPβ) isoforms as transcriptional regulators of the pro-invasive CDH3/P-cadherin gene in human breast cancer cells

P-cadherin is a cell-cell adhesion molecule codified by the CDH3 gene, which expression is highly associated with undifferentiated cells in normal adult epithelial tissues, as well as with poorly differentiated carcinomas. In breast cancer, P-cadherin is frequently overexpressed in high-grade tumours and is a well-established indicator of aggressive tumour behaviour and poor patient prognosis. However, till now, the mechanisms controlling CDH3 gene activation have been poorly explored. Since we recently described the existence of several CCAAT/Enhancer Binding Protein β (C/EBPβ) transcription factor binding sites at the CDH3 promoter, the aim of this study was to assess if the distinct C/EBPβ isoforms were directly involved in the transcriptional activation of the CDH3 gene in breast cancer cells. DNA-protein interactions, mutation analysis and luciferase reporter assay studies have been performed. We demonstrated that C/EBPβ is co-expressed with P-cadherin in breast cancer cells and all the three isoforms function as transcriptional regulators of the CDH3 gene, directly interacting with specific regions of its promoter. Interestingly, this transcriptional activation was only reflected at the P-cadherin protein level concerning the LIP isoform. Taken together, our data show that CDH3 is a newly defined transcriptional target gene of C/EBPβ isoforms in breast cancer, and we also identified the binding sites that are relevant for this activation.

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.

Intraductal proliferative lesions of the breast-terminology and biology matter: premalignant lesions or preinvasive cancer?

Morphological criteria for the diagnosis of intraductal proliferative lesions of the breast have been an object of research and much controversy, and its terminology is rather confusing. Knowledge of the molecular aspects of this disease probably necessitates further research to clarify if these entities can be identified as breast cancer precursors or as a malignant preinvasive disease. These issues are of great interest not only for their biological implications, but also to the clinician who must understand the disease and direct therapies. Molecular studies have shown that epitheliosis (usual ductal hyperplasia) is not monoclonal, while malignant lesions (atypical ductal hyperplasia, flat epithelial atypia, low-grade and high-grade intraductal carcinoma) constantly show these characteristics. These malignant lesions, classified with a DIN grading system (ductal intraepithelial neoplasia), are not obligate precursors of invasive ductal carcinoma and do not represent different evolving grades in a linear model of cancerogenesis. Breast cancerogenesis probably has different pathways with different morphologic precursors.

Molecular insights on basal-like breast cancer

Molecular classification of breast cancer (BC) identified diverse subgroups that encompass distinct biological behavior and clinical implications, in particular in relation to prognosis, spread, and incidence of recurrence. Basal-like breast cancers (BLBC) compose up to 15% of BC and are characterized by lack of estrogen receptor (ER), progesterone receptor (PR), and HER-2 amplification with expression of basal cytokeratins 5/6, 14, 17, epidermal growth factor receptor (EGFR), and/or c-KIT. There is an overlap in definition between triple-negative BC and BLBC due to the triple-negative profile of BLBC. Also, most BRCA1-associated BCs are BLBC, triple negative, and express basal cytokeratins (5/6, 14, 17) and EGFR. There is a link between sporadic BLBC (occurring in women without germline BRCA1 mutations) with dysfunction of the BRCA1 pathway. Despite the molecular and clinical similarities, these subtypes respond differently to neoadjuvant therapy. BLBCs are associated with an aggressive phenotype, high histological grade, poor clinical behavior, and high rates of recurrences and/or metastasis. Their molecular features render these tumors especially refractory to anti-hormonal-based therapies and the overall prognosis of this subset remains poor. In this article, the molecular profile, genomic, and epigenetic characteristics as well as BRCA1 pathway dysfunction, clinicopathological behavior, and therapeutic options in BLBC are presented, with emphasis on the discordant findings in current literature.

Basal breast cancer: a complex and deadly molecular subtype

During the last decade, gene expression profiling of breast cancer has revealed the existence of five molecular subtypes and allowed the establishment of a new classification. The basal subtype, which represents 15-25% of cases, is characterized by an expression profile similar to that of myoepithelial normal mammary cells. Basal tumors are frequently assimilated to triple-negative (TN) breast cancers. They display epidemiological and clinico-pathological features distinct from other subtypes. Their pattern of relapse is characterized by frequent and early relapses and visceral locations. Despite a relative sensitivity to chemotherapy, the prognosis is poor. Recent characterization of their molecular features, such as the dysfunction of the BRCA1 pathway or the frequent expression of EGFR, provides opportunities for optimizing the systemic treatment. Several clinical trials dedicated to basal or TN tumors are testing cytotoxic agents and/or molecularly targeted therapies. This review summarizes the current state of knowledge of this aggressive and hard-to-treat subtype of breast cancer.

Basal phenotype breast cancer: implications for treatment and prognosis

Breast cancer is the most common malignancy in females. The origins and biology of breast carcinomas remain unclear. Cellular and molecular heterogeneity results in different distinct groups of tumors with different clinical behavior and prognosis. Gene expression profiling has delineated five molecular subtypes based on similarities in gene expression: luminal A, luminal B, HER2 overexpressing, normal-like and basal-like. Basal-like breast cancer (BLBC) lacks estrogen receptor, progesterone receptor and HER2 expression, and comprises myoepithelial cells. Specific features include high proliferative rate, rapid growth, early recurrence and decreased overall survival. BLBC is associated with ductal carcinoma in situ, BRCA1 mutation, brain and lung metastasis, and negative axillary lymph nodes. Currently, chemotherapy is the only therapeutic choice, but demonstrates poor outcomes. There is an overlap in definition between triple-negative breast cancer and BLBC due to the triple-negative profile of BLBC. Despite the molecular and clinical similarities, the two subtypes respond differently to neoadjuvant therapy. Although particular morphologic, genetic and clinical features of BLBC have been identified, a variety of definitions among studies accounts for the contradictory results reported. In this article the molecular morphological and histopathological profile, the clinical behavior and the therapeutic options of BLBC are presented, with emphasis on the discordant findings among studies.

Nottingham Prognostic Index in triple-negative breast cancer: a reliable prognostic tool?

BACKGROUND

A breast cancer prognostic tool should ideally be applicable to all types of invasive breast lesions. A number of studies have shown histopathological grade to be an independent prognostic factor in breast cancer, adding prognostic power to nodal stage and tumour size. The Nottingham Prognostic Index has been shown to accurately predict patient outcome in stratified groups with a follow-up period of 15 years after primary diagnosis of breast cancer. Clinically, breast tumours that lack the expression of Oestrogen Receptor, Progesterone Receptor and Human Epidermal growth factor Receptor 2 (HER2) are identified as presenting a "triple-negative" phenotype or as triple-negative breast cancers. These poor outcome tumours represent an easily recognisable prognostic group of breast cancer with aggressive behaviour that currently lack the benefit of available systemic therapy. There are conflicting results on the prevalence of lymph node metastasis at the time of diagnosis in triple-negative breast cancer patients but it is currently accepted that triple-negative breast cancer does not metastasize to axillary nodes and bones as frequently as the non-triple-negative carcinomas, favouring instead, a preferentially haematogenous spread. Hypothetically, this particular tumour dissemination pattern would impair the reliability of using Nottingham Prognostic Index as a tool for triple-negative breast cancer prognostication.

METHODS

The present study tested the effectiveness of the Nottingham Prognostic Index in stratifying breast cancer patients of different subtypes with special emphasis in a triple-negative breast cancer patient subset versus non- triple-negative breast cancer.

RESULTS

We demonstrated that besides the fact that TNBC disseminate to axillary lymph nodes as frequently as luminal or HER2 tumours, we also showed that TNBC are larger in size compared with other subtypes and almost all grade 3. Additionally, survival curves demonstrated that these prognostic factors are equally important to stratify different survival outcomes in non-TNBC as in TNBC. We also showed that the NPI retains the ability to stratify and predict survival of TNBC patients.

CONCLUSION

The importance of this study relies on the need of prognostication improvements on TNBC, showing, at a clinical standpoint, that Nottingham Prognostic Index is as a truthful prognostic tool in TNBC.

Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology

CONTEXT

Numerous immunohistochemical stains have been shown to exhibit exclusive or preferential positivity in breast myoepithelial cells relative to their luminal/epithelial counterparts. These myoepithelial markers provide invaluable assistance in accurately classifying breast proliferations, especially in core biopsies. Although numerous myoepithelial markers are available, they differ in their sensitivity, specificity, and ease of interpretation, which may be attributed, to a large extent, to the variable immunoreactivity of these markers in stromal cells including myofibroblasts, vessels, luminal/epithelial cells, and tumor cells.

OBJECTIVE

To review commonly used myoepithelial markers in breast pathology and a selection of diagnostic scenarios where they may be useful.

DATA SOURCES

The information outlined in this review article is based on our experiences with routine cases and a review of English-language articles published between 1987 and 2008.

CONCLUSIONS

To demonstrate the presence or absence of myoepithelial cells, a panel-based approach of 2 or more markers is recommended. Markers that most effectively combine sensitivity, specificity, and ease of interpretation include smooth muscle myosin heavy chains, calponin, p75, p63, P-cadherin, basal cytokeratins, maspin, and CD10. These markers, however, display varying cross-reactivity patterns and variably reduced expression in the myoepithelial cells bordering in situ carcinomas. The choice of a myoepithelial marker should be dependent on a combination of factors, including published evidence on its diagnostic utility, its availability, performance characteristics that have been achieved in a given laboratory, and the specific diagnostic scenario. When its use is deemed necessary, immunohistochemistry for myoepithelial cells in breast pathology is most effective when conceptualized as supplemental, rather than central to routine morphologic interpretation.

Molecular phenotypes of matched in situ and invasive components of breast carcinomas

The current system of pathologic classification of human breast cancers does not take into account the biologic determinants of prognosis, nor is there a consensus regarding the progression from in situ to invasive carcinoma. The present study compared the molecular phenotypes of in situ and invasive components of breast cancer in the same sample. We built a series of 189 in situ and invasive carcinomas using tissue microarrays and classified them according to their immunoprofiles regarding estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, epidermal growth factor receptor, cytokeratin 5, P-cadherin, and the antigen Ki-67 into luminal A and B, human epidermal growth factor receptor 2 overexpressing, and basal-like carcinomas. We also correlated the subgroups of carcinomas with some of the classical prognostic factors such as histologic grade, tumor size, and lymph node metastasis, as well as with the age of the patient at diagnosis. The overall concordance on the molecular phenotypes between in situ and invasive components was 94%. For the in situ component, 63% of the cases were luminal A; 15%, luminal B; 12%, human epidermal growth factor receptor 2 overexpressing; and 7%, basal-like. Regarding the invasive component, 61% of the cases were luminal A; 16%, luminal B; 12%, human epidermal growth factor receptor 2 overexpressing; and 8%, basal-like. The present study allowed the identification of different immunoprofiles of in situ and invasive breast carcinomas using a specific panel of biomarkers and showed that in most cases, there is a concordance between in situ and invasive component profiles, supporting the theory of parallel disease in breast tumorigenesis.

Breast carcinoma in Uganda: microscopic study and receptor profile of 45 cases

CONTEXT

Histologic and receptor data on breast carcinoma in Uganda are scarce. Estrogen receptor status is not routinely available. Breast cancer blocks from Uganda were studied in Montreal, Canada, and clinical correlations subsequently discussed in Kampala, Uganda.

OBJECTIVE

To correlate histologic features (tumor type, histologic grade), receptor profile (estrogen receptor, progesterone receptor, and HER2/neu), and age in Ugandan women.

DESIGN

Pathology reports for 2000-2004 from Nsambya Hospital, reporting invasive breast carcinoma, provided 45 microscopically confirmed cases.

RESULTS

Seventy-three percent of patients were 50 years or younger. Histologic types were invasive ductal carcinoma (78%) and "good" prognosis types (11%). Overall 40% were grade 3, but 48% of invasive ductal carcinomas were grade 3. Estrogen receptor was positive in 60% overall and in 51% of invasive ductal carcinomas. HER2/neu was overexpressed in 11%; 36% were "triple" negative (estrogen receptor, progesterone receptor, HER2/neu negative).

CONCLUSIONS

Breast carcinoma in Ugandan women presents at a younger age and is histologically and by receptor profile more aggressive than carcinoma in Caucasian women.

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

Breast cancer is a heterogeneous disease encompassing a variety of entities with distinct morphological features and clinical behaviors. Although morphology is often associated with the pattern of molecular aberrations in breast cancers, it is also clear that tumors of the same histological type show remarkably different clinical behavior. This is particularly true for 'basal-like cancer', which is an entity defined using gene expression analysis. The purpose of this article was to review the current state of knowledge of basal-like breast cancers, to discuss the relationship between basal-like and triple-negative breast cancers, and to clarify practical implications of these diagnoses for pathologists and oncologists.

P-cadherin expression as a prognostic biomarker in a 3992 case tissue microarray series of breast cancer

P-cadherin is a calcium-dependent cell-cell adhesion glycoprotein. P-cadherin expression is restricted to the myoepithelial cells in normal breast tissue, and aberrant staining has also been described in invasive tumors. Several small studies have reported P-cadherin as a marker of poor outcome in breast cancer patients but its prognostic significance in relation to other variables has not been established in a large series of breast cancers. A tissue microarray was constructed from 3992 cases of invasive breast carcinoma, and P-cadherin expression was evaluated using immunohistochemistry. Median follow-up was 12.5 years. The immunohistochemistry-based definitions of cancer subtypes were luminal (ER+ or PR+/HER2-), luminal/HER2+ (ER+ or PR+/HER2+), HER2+ (ER-/PR-/HER2+), and basal (ER-/PR-/HER2-/CK5/6+ or EGFR+). Clinical covariate and biomarker associations were assessed using contingency tables, and Pearson's χ(2) or Fisher's exact test. Survival associations were assessed using Kaplan-Meier plots, logrank and Breslow tests, and Cox proportional hazards regression analysis. P-cadherin was expressed in 34.8% (1290/3710, 50% cut point) of cases. P-cadherin staining was strongly associated with HER2+ and basal carcinoma subtypes (P<0.0005). P-cadherin-positive patients showed significantly poorer short-term (0-10 years) overall survival, disease-specific survival, distant relapse-free interval, and locoregional relapse-free interval in univariable models (P<0.05). In multivariable Cox models containing standard clinical covariates and cancer subtypes, P-cadherin did not show independent prognostic value. P-cadherin expression was positively associated with histological grade, chemotherapy, Ki-67, EGFR, CK5/6, p53, YB-1, and HER2 expression (P<0.002), and negatively associated with age at diagnosis, ER, PR, and Bcl-2 expression (P<0.0005). This study shows the value of P-cadherin as a marker of poor prognosis. The large sample size of this series clarifies contradictory findings of many smaller studies. P-cadherin positivity is associated with high-grade tumor subtypes and well-established markers of poor prognosis, and may represent a promising antibody therapeutic target.

Molecular subtyping of DCIS: heterogeneity of breast cancer reflected in pre-invasive disease

Background:

Molecular profiling has identified at least four subtypes of invasive breast carcinoma, which exhibit distinct clinical behaviour. There is good evidence now that DCIS represents the non-obligate precursor to invasive breast cancer and therefore it should be possible to identify similar molecular subtypes at this stage. In addition to a limited five-marker system to identify molecular subtypes in invasive breast cancer, it is evident that other biological molecules may identify distinct tumour subsets, though this has not been formally evaluated in DCIS.

Methods:

Tissue microarrays were constructed for 188 cases of DCIS. Immunohistochemistry was performed to examine the expression patterns of oestrogen receptor (ER), progesterone receptor (PR), Her2, EGFR, cytokeratin (CK) 5/6, CK14, CK17, CK18, β4-integrin, β6-integrin, p53, SMA, maspin, Bcl-2, topoisomerase IIα and P-cadherin. Hierarchical clustering analysis was undertaken to identify any natural groupings, and the findings were validated in an independent sample series.

Results:

Each of the intrinsic molecular subtypes described for invasive breast cancer can be identified in DCIS, though there are differences in the relative frequency of subgroups, in particular, the triple negative and basal-like phenotype is very uncommon in DCIS. Hierarchical cluster analysis identified three main subtypes of DCIS determined largely by ER, PR, Her2 and Bcl-2, and this classification is related to conventional prognostic indicators. These subtypes were confirmed in an analysis on independent series of DCIS cases.

Conclusion:

This study indicates that DCIS may be classified in a similar manner to invasive breast cancer, and determining the relative frequency of different subtypes in DCIS and invasive disease may shed light on factors determining disease progression. It also demonstrates a role for Bcl-2 in classifying DCIS, which has recently been identified in invasive breast cancer.

Monocarboxylate transporter 1 is up-regulated in basal-like breast carcinoma

AIMS

Monocarboxylate transporters (MCTs) have been considered promising targets for cancer therapy, since they facilitate lactate efflux in glycolytic tumours. However, their role in solid tumours is still poorly understood. Thus, the present work aimed to contribute to understanding the involvement of MCT1 and MCT4 in breast cancer progression as well as MCT regulation by CD147.

METHODS AND RESULTS

The expression of the membrane transporters MCT1 and MCT4 was analysed in a series of breast carcinomas (249 cases) and their clinicopathological significance investigated. Additionally, we analysed the significance of CD147 co-expression, as an important regulator of MCT expression and activity. MCT1 was significantly increased in breast carcinomas when compared with normal breast tissue and, importantly, both MCT1 and CD147 were associated with poor prognostic variables such as basal-like subtype and high grade tumours.

CONCLUSIONS

These results provide evidence for a prognostic value of MCT1 in breast carcinoma and support the exploitation of the complex MCT1/CD147 as a promising target for cancer therapy, especially in basal-like breast carcinoma.

Increased NOS2 predicts poor survival in estrogen receptor-negative breast cancer patients

Inducible nitric oxide synthase (NOS2) is involved in wound healing, angiogenesis, and carcinogenesis. NOS2 upregulation and increased nitric oxide (NO) production affect the redox state of cells and can induce protein, lipid, and DNA modifications. To investigate whether NOS2 levels influence survival of breast cancer patients, we examined NOS2 expression and its association with tumor markers and survival in 248 breast tumors. In multivariable survival analysis, increased NOS2 predicted inferior survival in women with estrogen receptor α-negative (ER-negative) tumors. Microdissected tumor epithelium from ER-negative tumors with high NOS2 had increased IL-8 and a gene expression signature characteristic of basal-like breast cancer with poor prognosis. In cell culture, NO only induced selected signature genes in ER-negative breast cancer cells. ER transgene expression in ER-negative cells inhibited NO-induced upregulation of the stem cell marker CD44 and other proteins encoded by signature genes, but not of IL-8. Exposure to NO also enhanced cell motility and invasion of ER-negative cells. Last, pathway analysis linked the tumor NOS2 gene signature to c-Myc activation. Thus, NOS2 is associated with a basal-like transcription pattern and poor survival of ER-negative patients.

Alterations in Vitamin D signalling and metabolic pathways in breast cancer progression: a study of VDR, CYP27B1 and CYP24A1 expression in benign and malignant breast lesions

Background

Breast cancer is a heterogeneous disease associated with different patient prognosis and responses to therapy. Vitamin D has been emerging as a potential treatment for cancer, as it has been demonstrated that it modulates proliferation, apoptosis, invasion and metastasis, among others. It acts mostly through the Vitamin D receptor (VDR) and the synthesis and degradation of this hormone are regulated by the enzymes CYP27B1 and CYP24A1, respectively. We aimed to study the expression of these three proteins by immunohistochemistry in a series of breast lesions.

Methods

We have used a cohort comprising normal breast, benign mammary lesions, carcinomas in situ and invasive carcinomas and assessed the expression of the VDR, CYP27B1 and CYP24A1 by immunohistochemistry.

Results

The results that we have obtained show that all proteins are expressed in the various breast tissues, although at different amounts. The VDR was frequently expressed in benign lesions (93.5%) and its levels of expression were diminished in invasive tumours (56.2%). Additionally, the VDR was strongly associated with the oestrogen receptor positivity in breast carcinomas. CYP27B1 expression is slightly lower in invasive carcinomas (44.6%) than in benign lesions (55.8%). In contrast, CYP24A1 expression was augmented in carcinomas (56.0% in in situ and 53.7% in invasive carcinomas) when compared with that in benign lesions (19.0%).

Conclusions

From this study, we conclude that there is a deregulation of the Vitamin D signalling and metabolic pathways in breast cancer, favouring tumour progression. Thus, during mammary malignant transformation, tumour cells lose their ability to synthesize the active form of Vitamin D and respond to VDR-mediated Vitamin D effects, while increasing their ability to degrade this hormone.

Biomarkers for Basal-like Breast Cancer

Initially recognized through microarray-based gene expression profiling, basal-like breast cancer, for which we lack effective targeted therapies, is an aggressive form of carcinoma with a predilection for younger women. With some success, immunohistochemical studies have attempted to reproduce the expression profile classification of breast cancer through identification of subtype-specific biomarkers. This review aims to present an in depth summary and analysis of the current status of basal-like breast cancer biomarker research. While a number of biomarkers show promise for future clinical application, the next logical step is a comprehensive investigation of all biomarkers against a gene expression profile gold standard for breast cancer subtype assignment.

Triple-negative/basal-like breast cancer: clinical, pathologic and molecular features

Review of the spectrum of breast cancer tumor subtypes, which include basal-like, triple-negative and BRCA1-positive tumors, suggest that they have overlapping clinical, pathologic and molecular features, which are different from endocrine responsive breast cancers. Although response to chemotherapy is high in the neoadjuvant setting, the overall prognosis of this subset of tumors remains poor. Gene-profiling studies of this heterogeneous subset have lead to a better understanding of the molecular pathology of these aggressive tumors and the identification of possible therapeutic targets. Ongoing clinical studies of newer targeted agents, along with optimal chemotherapy, portend an improved clinical outcome for patients with aggressive basal-like/triple-negative breast cancer in the future.

PIKing the right isoform: the emergent role of the p110beta subunit in breast cancer

Class IA phosphoinositide-3'-kinases (PI3Ks) regulate many cellular processes. Despite a clear implication of PI3K in cancer, the involvement of each of its isoforms namely p110alpha and p110beta in the development of breast cancer remains elusive. Until recently, the spotlight was given to the alpha subunit; however, the p110beta isoform has now emerged as an interesting target as well. In order to determine the importance of both these subunits in breast cancer, we aimed to study the expression of p110alpha and p110beta in a series of invasive breast carcinomas. We constructed tissue microarrays from 315 invasive breast carcinomas and performed immunohistochemistry for p110alpha and beta, correlating the expression patterns with clinicopathological parameters. Furthermore, overall survival was analysed through Kaplan-Meier survival curves and Cox regression. We found that p110 subunits are expressed in 23.8% of invasive breast carcinomas, of which 11.8% express p110alpha and 15.2% p110beta. The p110alpha positive tumours correlated with hormone receptor (HR) expression, and were not associated with overall survival. The membrane expression of p110beta was associated with worse prognosis. This was due to its link to HER2-overexpression, lower age of onset, higher grade, lymph node involvement, distant metastasis and was inversely associated with HR status. Furthermore, p110beta expression was associated with worse overall survival. Importantly our results indicate a role for the beta subunit in the development/progression of HER2-overexpressing tumours, highlighting possible therapeutic associations between HER2 and p110beta inhibitors.

Vessel density assessed by endoglin expression in breast carcinomas with different expression profiles

AIMS

To evaluate the relationship between microvessel density assessed by endoglin expression and the molecular subtypes of human invasive breast carcinomas and whether there is evidence to indicate that angiogenesis could be a putative target for therapy in specific subsets of breast cancer.

METHODS AND RESULTS

We studied a series of 161 breast carcinomas, but information was available on only 142 tumours. We correlated endoglin expression with distinct breast carcinoma subgroups classified according to immunohistochemical profiling. Additionally, we compared it with other biomarkers for the aggressive basal-like subset and with available histopathological data. Although the basal-like subtype has higher microvessel density, there are no significant differences with the other molecular subtypes of breast cancer.

CONCLUSIONS

This study found no significant differences in tumour vascularity in different molecular subtypes of breast cancer.

Basal-like breast carcinoma: from expression profiling to routine practice

CONTEXT

Advances in the understanding of the molecular and genetic mechanisms of breast cancer have led to realization of the heterogeneity of the disease and the promise of a new era of individualized management for patients with breast cancer. The advent and use of high-throughput molecular methods for the study of breast cancer have brought to the forefront the existence of the so-called basal-like breast cancers, which have been shown to have distinct biologic and clinical characteristics.

OBJECTIVE

To critically assess the clinicopathologic features of basal-like breast cancer, discuss the morphologic and immunophenotypic features of basal-like cancer, and explore the criteria that can be used to identify these tumors in routine practice.

DATA SOURCES

A Medline/PubMed search was conducted using the terms "basal-like," "(basal OR basaloid OR basal-like) AND breast cancer." All articles in English language were retrieved and critically reviewed.

CONCLUSIONS

Basal-like breast cancers constitute a distinct, yet heterogeneous, class of neoplasms associated with specific histologic features and poor prognosis despite high response rates to neoadjuvant chemotherapy. Basal-like breast cancers have features that recapitulate those of tumors arising in BRCA1 mutation carriers, and the majority of patients with BRCA1 germline mutations develop basal-like breast cancers. At the molecular level, basal-like cancers harbor a transcriptome that is distinct from that of hormone-receptor-positive or HER2-amplified tumors, being characterized by the expression of genes usually found in basal/myoepithelial cells of the breast. However, translating the new concepts about basal-like cancer into clinical practice has proven a Herculean task, given the lack of an internationally accepted definition for these tumors and for the method of identification in routine practice.

Expression of FOXA1 and GATA-3 in breast cancer: the prognostic significance in hormone receptor-negative tumours

Introduction

The expression of additional genes, other than oestrogen receptor (ER), may be important to the hormone-responsive phenotype of breast cancer. Microarray analyses have revealed that forkhead box A1 (FOXA1) and GATA binding protein 3 (GATA-3) are expressed in close association with ERα, both encoding for transcription factors with a potential involvement in the ERα-mediated action in breast cancer. The purpose of this study was to explore if the expression of FOXA1 and GATA-3 may provide an opportunity to stratify subsets of patients that could have better outcome, among the ERα-negative/poor prognosis breast cancer group.

Methods

We evaluate FOXA1 and GATA-3 expression in 249 breast carcinomas by immunohistochemistry, associating it with breast cancer molecular markers, clinicopathological features and patient's survival. The clinicopathological features and immunohistochemical markers of the tumours were compared using the chi-square test and ANOVA. Disease-free survival was analysed through Kaplan–Meier survival curves and Cox regression.

Results

FOXA1 expression was demonstrated in 42% of invasive carcinomas, while GATA-3 was detected in 48% of the cases. FOXA1 expression was inversely associated with tumour size, Nottingham Prognostic Index, histological grade, lymph vascular invasion, lymph node stage and human epidermal growth factor receptor-2 (HER-2) overexpression, while GATA-3 expression showed inverse association with histological grade and HER-2. Both FOXA1 and GATA-3 were directly associated with ERα and progesterone receptor. Among FOXA1-positive tumours, 83.1% are comprised in the luminal A subtype, similar to GATA-3 where 87.7% of positive tumours were classified within this molecular subtype. In the subset of ERα-negative patients, those who were FOXA1-negative had a 3.61-fold increased risk of breast cancer recurrence when compared with the FOXA1-positive.

Conclusions

FOXA1 was a significant predictor of good outcome in breast cancer, whereas GATA-3 was an important luminal marker. The expression of FOXA1 may be used for risk stratification among ERα-negative patients.

Salivary duct carcinoma in situ of the parotid gland

AIMS

To describe three cases of purely in situ salivary duct carcinoma, so as better to define the entity.

METHODS AND RESULTS

Three primary tumours of the parotid gland are presented, in each case composed of cysts and ducts and lined by high nuclear grade epithelial cells. All parts of each tumour were surrounded by a myoepithelial cell rim and there was no evidence of invasion. The tumour cells expressed immunohistochemical markers seen in invasive salivary duct carcinoma of usual (high-grade) type. In two cases the androgen receptor (AR) reaction was strong, but there was no immunohistochemical expression of HER2 protein or gene amplification by in situ hybridization. In the remaining case, fewer nuclei stained for AR, but both HER2 protein and gene amplification were demonstrated.

CONCLUSIONS

Salivary duct carcinoma in situ is morphologically similar to breast ductal carcinoma in situ and, although our cases are few, salivary duct carcinoma in situ can possibly be subdivided into luminal and non-luminal cell types, as can analogous mammary neoplasms. The present study cannot determine whether low-grade cribriform cystadenocarcinoma, architecturally similar but immunohistochemically different, is part of the spectrum of salivary duct carcinoma in situ, or whether it represents a separate entity.

EGFR/HER2 in breast cancer: a biological approach for molecular diagnosis and therapy

Novel cancer therapies have focused on specific molecular markers present in malignant tumors. The rationale of targeted therapy relies on the knowledge of molecular mechanisms involved in carcinogenesis and their influence in clinical outcome allied to a more specific and less toxic treatment. Activation of EGF receptor and HER2 is an important factor for initiation and progression of malignancies, including breast cancer where the status of HER2 is an essential step in the diagnostic workup; EGFR overexpression has been associated to the so-called basal-like breast carcinomas, which opens a new avenue for diagnosis and therapeutic approach in these tumors. This review will focus on mechanisms of HER2 and EGF receptor upregulation, the targeted therapies that are currently in use for these receptors, possible combined therapies, as well as the approach for molecular diagnosis from the pathologist's point of view.

Comparison of molecular phenotypes of ductal carcinoma in situ and invasive breast cancer

INTRODUCTION

At least four major categories of invasive breast cancer that are associated with different clinical outcomes have been identified by gene expression profiling: luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) and basal-like. However, the prevalence of these phenotypes among cases of ductal carcinoma in situ (DCIS) has not been previously evaluated in detail. The purpose of this study was to compare the prevalence of these distinct molecular subtypes among cases of DCIS and invasive breast cancer.

METHODS

We constructed tissue microarrays (TMAs) from breast cancers that developed in 2897 women enrolled in the Nurses' Health Study (1976 to 1996). TMA slides were immunostained for oestrogen receptor (ER), progesterone receptor (PR), HER2, cytokeratin 5/6 (CK5/6) and epidermal growth factor receptor (EGFR). Using these immunostain results, cases were grouped into molecularly defined subtypes.

RESULTS

The prevalence of the distinct molecular phenotypes differed significantly between DCIS (n = 272) and invasive breast cancers (n = 2249). The luminal A phenotype was significantly more frequent among invasive cancers (73.4%) than among DCIS lesions (62.5%) (p = 0.0002). In contrast, luminal B and HER2 molecular phenotypes were both more frequent among DCIS (13.2% and 13.6%, respectively) as compared with invasive tumours (5.2% and 5.7%, respectively) (p < 0.0001). The basal-like phenotype was more frequent among the invasive cancers (10.9%) than DCIS (7.7%), although this difference was not statistically significant (p = 0.15). High-grade DCIS and invasive tumours were more likely to be HER2 type and basal-like than low- or intermediate-grade lesions. Among invasive tumours, basal-like and HER2 type tumours were more likely to be more than 2 cm in size, high-grade and have nodal involvement compared with luminal A tumours.

CONCLUSION

The major molecular phenotypes previously identified among invasive breast cancers were also identified among cases of DCIS. However, the prevalence of the luminal A, luminal B and HER2 phenotypes differed significantly between DCIS and invasive breast cancers.

Integrated genomic and transcriptomic analysis of ductal carcinoma in situ of the breast

PURPOSE

To gain insight into genomic and transcriptomic subtypes of ductal carcinomas in situ of the breast (DCIS).

EXPERIMENTAL DESIGN

We did a combined phenotypic and genomic analysis of a series of 57 DCIS integrated with gene expression profile analysis for 26 of the 57 cases.

RESULTS

Thirty-two DCIS exhibited a luminal phenotype; 21 were ERBB2 positive, and 4 were ERBB2/estrogen receptor (ER) negative with 1 harboring a bona fide basal-like phenotype. Based on a CGH analysis, genomic types were identified in this series of DCIS with the 1q gain/16q loss combination observed in 3 luminal DCIS, the mixed amplifier pattern including all ERBB2, 12 luminal and 2 ERBB2(-)/ER(-) DCIS, and the complex copy number alteration profile encompassing 14 luminal and 1 ERBB2(-)/ER(-) DCIS. Eight cases (8 of 57; 14%) presented a TP53 mutation, all being amplifiers. Unsupervised analysis of gene expression profiles of 26 of the 57 DCIS showed that luminal and ERBB2-amplified, ER-negative cases clustered separately. We further investigated the effect of high and low copy number changes on gene expression. Strikingly, amplicons but also low copy number changes especially on 1q, 8q, and 16q in DCIS regulated the expression of a subset of genes in a very similar way to that recently described in invasive ductal carcinomas.

CONCLUSIONS

These combined approaches show that the molecular heterogeneity of breast ductal carcinomas exists already in in situ lesions and further indicate that DCIS and invasive ductal carcinomas share genomic alterations with a similar effect on gene expression profile.