The Influence of Basal Phenotype on the Metastatic Pattern of Breast Cancer

NR2F1 Is a Barrier to Dissemination of Early-Stage Breast Cancer Cells

Cancer cells can disseminate during very early and sometimes asymptomatic stages of tumor progression. Though biological barriers to tumorigenesis have been identified and characterized, the mechanisms that limit early dissemination remain largely unknown. We report here that the orphan nuclear receptor nuclear receptor subfamily 2, group F, member 1 (NR2F1)/COUP-TF1 serves as a barrier to early dissemination. NR2F1 expression was decreased in patient ductal carcinoma in situ (DCIS) samples. High-resolution intravital imaging of HER2+ early-stage cancer cells revealed that loss of function of NR2F1 increased in vivo dissemination and was accompanied by decreased E-cadherin expression, activation of wingless-type MMTV integration site family, member 1 (WNT)-dependent β-catenin signaling, disorganized laminin 5 deposition, and increased expression of epithelial-mesenchymal transition (EMT) genes such as twist basic helix-loop-helix transcription factor 1 (TWIST1), zinc finger E-box binding homeobox 1 (ZEB1), and paired related homeobox 1 (PRRX1). Furthermore, downregulation of NR2F1 promoted a hybrid luminal/basal phenotype. NR2F1 expression was positively regulated by p38α signaling and repressed by HER2 and WNT4 pathways. Finally, early cancer cells with NR2F1LOW/PRRX1HIGH staining were observed in DCIS samples. Together, these findings reveal the existence of an inhibitory mechanism of dissemination regulated by NR2F1 in early-stage breast cancer cells.

SIGNIFICANCE

During early stages of breast cancer progression, HER2-mediated suppression of NR2F1 promotes dissemination by inducing EMT and a hybrid luminal/basal-like program.

Psoralen-loaded polymeric lipid nanoparticles combined with paclitaxel for the treatment of triple-negative breast cancer

Background: Chemotherapeutic drugs are associated with toxic effects. Metastasis is the leading cause of death in breast cancer patients. Aim: To evaluate the antitumor effect of paclitaxel (PTX) combined with psoralen-loaded polymeric lipid nanoparticles (PSO-PLNs) in triple-negative breast cancer. Methods: After treatment of samples, cell viability, apoptosis, migration, invasion, expression of proteins in the IRAK1/NF-κB/FAK signal pathway, biodistribution and pathological characteristics were detected. Results: Compared with the control group, the PTX + PSO-PLNs group showed increased apoptosis and reduced migration, invasion and expression of phosphorylated IRAK1 and NF-κB, with significant inhibition of tumor growth and lung metastases and no obvious toxicity. Conclusion: Combined administration of PTX and PSO-PLNs exerted a synergistic effect and significantly inhibited the growth and metastasis of triple-negative breast cancer.

Molecular mediators of breast cancer metastasis

Breast cancer has the highest incidence rate of malignancy in women worldwide. A major clinical challenge faced by patients with breast cancer treated by conventional therapies is frequent relapse. This relapse has been attributed to the cancer stem cell (CSC) population that resides within the tumor and possess stemness properties. Breast CSCs are generated when breast cancer cells undergo epithelial-mesenchymal transition resulting in aggressive, highly metastatic, and invasive phenotypes that exhibit resistance towards chemotherapeutics. Metastasis, a phenomenon that aids in the migration of breast CSCs, occurs through any of three different routes: hematogenous, lymphatic, and transcoelomic. Hematogenous dissemination of breast CSCs leads to metastasis towards distant unrelated organs like lungs, liver, bone, and brain causing secondary tumor generation. Activation of metastasis genes or silencing of metastasis suppressor genes often leads to the advancement of metastasis. This review focuses on various genes and molecular factors that have been implicated to regulate organ-specific breast cancer metastasis by defying the available therapeutic interventions.

Dynamic and subtype-specific interactions between tumour burden and prognosis in breast cancer

We investigated the relationship between the prognostic importance of anatomic tumour burden and subtypes of breast cancer using data from the Korean Breast Cancer Registry Database. In HR+/HER2+ and HR−/HER2−tumours, an increase in T stage profoundly increased the hazard of death, while the presence of lymph node metastasis was more important in HR+/HER2+ and HR−/HER2+ tumours among 131,178 patients with stage I–III breast cancer. The patterns of increasing mortality risk and tumour growth (per centimetre) and metastatic nodes (per node) were examined in 67,038 patients with a tumour diameter ≤ 7 cm and < 8 metastatic nodes. HR+/HER2− and HR−/HER2− tumours showed a persistent increase in mortality risk with an increase in tumour diameter, while the effect was modest in HER2+ tumours. Conversely, an increased number of metastatic nodes was accompanied by a persistently increased risk in HR−/HER2+ tumours, while the effect was minimal for HR−/HER2− tumours with > 3 or 4 nodes. The interactions between the prognostic significance of anatomic tumour burden and subtypes were significant. The prognostic relevance of the anatomic tumour burden was non-linear and highly dependent on the subtypes of breast cancer.

Risk factors for breast cancer brain metastases: a systematic review

Background: Brain metastasis (BM) is an increasingly common and devastating complication of breast cancer (BC).

Methods: A systematic literature search of EMBASE and MEDLINE was conducted to elucidate the current state of knowledge on known and novel prognostic factors associated with 1) the risk for BCBM and 2) the time to brain metastases (TTBM).

Results: A total of 96 studies involving institutional records from 28 countries were identified. Of these, 69 studies reported risk factors of BCBM, 46 factors associated with the TTBM and twenty studies examined variables for both outcomes. Young age, estrogen receptor negativity (ER-), overexpression of human epidermal factor (HER2+), and higher presenting stage, histological grade, tumor size, Ki67 labeling index and nodal involvement were consistently found to be independent risk factors of BCBM. Of these, triple-negative BC (TNBC) subtype, ER-, higher presenting histological grade, tumor size, and nodal involvement were also reported to associate with shorter TTBM. In contrast, young age, hormone receptor negative (HR-) status, higher presenting stage, nodal involvement and development of liver metastasis were the most important risk factors for BM in HER2-positive patients.

Conclusions: The study provides a comprehensive and individual evaluation of the risk factors that could support the design of screening tools and interventional trials for early detection of BCBM.

Novel immunohistochemistry-based signatures to predict metastatic site of triple-negative breast cancers

BACKGROUND

Although distant metastasis (DM) in breast cancer (BC) is the most lethal form of recurrence and the most common underlying cause of cancer related deaths, the outcome following the development of DM is related to the site of metastasis. Triple negative BC (TNBC) is an aggressive form of BC characterised by early recurrences and high mortality. Athough multiple variables can be used to predict the risk of metastasis, few markers can predict the specific site of metastasis. This study aimed at identifying a biomarker signature to predict particular sites of DM in TNBC.

METHODS

A clinically annotated series of 322 TNBC were immunohistochemically stained with 133 biomarkers relevant to BC, to develop multibiomarker models for predicting metastasis to the bone, liver, lung and brain. Patients who experienced metastasis to each site were compared with those who did not, by gradually filtering the biomarker set via a two-tailed t-test and Cox univariate analyses. Biomarker combinations were finally ranked based on statistical significance, and evaluated in multivariable analyses.

RESULTS

Our final models were able to stratify TNBC patients into high risk groups that showed over 5, 6, 7 and 8 times higher risk of developing metastasis to the bone, liver, lung and brain, respectively, than low-risk subgroups. These models for predicting site-specific metastasis retained significance following adjustment for tumour size, patient age and chemotherapy status.

CONCLUSIONS

Our novel IHC-based biomarkers signatures, when assessed in primary TNBC tumours, enable prediction of specific sites of metastasis, and potentially unravel biomarkers previously unknown in site tropism.

Migration of breast cancer cell lines in response to pulmonary laminin 332

Because tumor cell motility is a requirement for metastasis, we hypothesized that lung tissue harbors substances that induce tumor cell migration. MCF-7 breast carcinoma cells exposed to small airway epithelial cells and conditioned medium exhibited dose-dependent tumor cell migration. Among the extracellular matrix proteins in the conditioned medium identified by mass spectrometry, laminin 332 (LM332) had the greatest contribution to the migration of MCF-7 cells. Immunoblotting and immunohistochemistry for LM332-specific chains identified LM332 in the lung and in pulmonary epithelial cells. Antibodies to either LM332 or its integrin receptor inhibited MCF-7 motility, and knockdown of LM332 chains also reduced its migration-inducing activity. Taken together, these findings implicate LM332 as a component of lung tissue that can induce motility in breast carcinoma cells that have been transported to lung during metastasis. Earlier studies on LM332 in tumor progression have examined LM332 expression in tumor cells. This investigation, in comparison, provides evidence that the tumor promoting potential of LM332 may originate in the lung microenvironment rather than in tumor cells alone. Furthermore, this study provides evidence that the motility-inducing properties of the microenvironment can reside in epithelial cells. The findings raise the possibility that LM332 plays a role in the pulmonary metastases of breast carcinoma and may provide a target for antimetastasis therapy.

TBS and BMD at the end of AI-therapy: A prospective study of the B-ABLE cohort

INTRODUCTION

Patients with breast cancer under aromatase inhibitor (AI) treatment often develop osteoporosis and their average bone loss rate is twice that of natural reduction during menopause, increasing fracture risk. As the current diagnostic technique based on bone mineral density (BMD) provides no information on bone quality, the Trabecular Bone Score (TBS) has been proposed to reflect bone microarchitecture status. The present study was designed to assess prospective changes in TBS and lumbar spine (LS) BMD in postmenopausal women with breast cancer at completion of AI treatment.

METHODS

B-ABLE is a prospective cohort of 735 women with breast cancer treated with AIs according to American Society of Clinical Oncology recommendations: 5years of AI starting within 6weeks post-surgery or 1month after the last cycle of chemotherapy (5y-AI group), or switching to an AI to complete 5-year therapy after 2-3years of tamoxifen (pTMX-AI group). Patients with osteoporosis were treated with oral bisphosphonates (BP). TBS and LS-BMD changes at completion of AI therapy were evaluated by Student t-test for paired samples. Pearson correlation coefficients were computed for correlations between LS-BMD and TBS.

RESULTS

AI treatment was completed by 277 women. Of these, 70 (25.3%) were allocated to BP therapy. The non-BP-treated patients (74.7%) showed significant decreases in TBS (-2.94% in pTMX-AI and -2.93% in 5y-AI groups) and in LS-BMD (-4.14% in pTMX-AI and -2.28% in 5y-AI groups) at the end of AI treatment. In BP-treated patients, TBS remained stable at the end of AI treatment, whereas LS-BMD showed significant increases (+2.30% in pTMX-AI and +5.33% in 5y-AI groups). Moderate associations between TBS and LS-BMD values at baseline and at the end of AI treatment (r=0.4; P<0.001) were observed. At the end of treatment, changes in spine BMD and TBS were weakly correlated (r=0.1, P<0.01).

CONCLUSIONS

AI therapy induces significant decreases in TBS, comparable to BMD loss. BP-treated patients maintained TBS values, whereas BMD increased. AI treatment leads to deterioration of bone microarchitecture, which seems to be attenuated by BP therapy.

Causas de muerte por cáncer de mama en Colombia

<p>Objetivo Revisar las causas directas de muerte por cáncer de mama en Colombia según datos de los certificados de defunción en el año 2008.Material y Métodos Se revisaron las causas directas de muerte en pacientes cuyo código de causa básica de defunción fue el de tumor maligno de la mama según el   registro de defunciones del Departamento Nacional de Estadística de Colombia (DANE) en el año 2008. Se evalúa su distribución por código de diagnóstico de la causa directa de muerte, grupos de edad, nivel educativo, estado civil, seguridad social y sitio de defunción.Resultados Las principales causas directas de muerte en mujeres fueron insuficiencia o falla respiratoria, paro cardiorespiratorio, falla orgánica múltiple o multisistémica, cáncer de seno y cáncer de mama metastásico. La mayoría de las muertes tuvieron el código C509 y se presentaron en mayores de 50 años. En hombres la causa más frecuente fue la falla respiratoria. Conclusiones Las principales denominaciones anotadas en los registros de defunción como causa directa de muerte por cáncer de mama fueron insuficiencia, paro respiratorio y paro cardiorespiratorio. Sin embargo, se evidencia que esto surge por problemas en el registro al no ceñirse a la Clasificación internacional de enfermedades (CIE-10). Se requiere mejorar la calidad de los registros de defunción para aprovechar la información que aporta este documento.</p>

Differential expression of immunohistochemical markers in primary lung and breast cancers enriched for triple-negative tumours

AIMS

In breast cancer patients presenting with a lung lesion, the distinction between lung and breast origin is clinically important. Lung and breast cancers are both CK7(+) /CK20(-) , so additional immunohistochemical markers are needed.

METHODS AND RESULTS

We examined the expression of oestrogen receptor (ER), progesterone receptor (PR), thyroid transcription factor-1 (TTF-1), gross cystic disease fluid protein-15 (GCDFP-15), p63 and Wilms' tumour 1 (WT1) in a series of tissue microarrays comprising 266 non-small-cell lung cancers and 837 primary breast cancers enriched for triple-negative tumours (TNBC). Staining for ER, PR, TTF-1 and GCDFP-15 was present in 63%, 49%, 0% and 25% of breast and 6%, 9%, 59% and 1% of lung cancers, respectively. Strong staining for p63 was present in 63 (97%) lung squamous cell carcinomas and only eight (9%) TNBC. WT1 nuclear staining was rare; however, cytoplasmic staining was identified in 49 (40%) TNBC and 10 (5%) lung cancers. Cluster analysis segregated TNBC from lung cancers with TTF-1 and/or p63 staining favouring lung origin, and GCDFP-15 or WT1 staining favouring breast origin. Cancers negative for all four markers (17%) were 60% breast and 40% lung origin.

CONCLUSION

An immunohistochemical panel incorporating ER, TTF-1, GCDFP-15, p63 and WT1 can help to distinguish lung cancer from metastatic breast cancer, including TNBC.

β-catenin regulates c-Myc and CDKN1A expression in breast cancer cells

We previously reported that the Wnt pathway is preferentially activated in basal-like breast cancer. However, the mechanisms by which the Wnt pathway regulates down-stream targets in basal-like breast cancer, and the biological significance of this regulation, are poorly understood. In this study, we found that c-Myc is highly expressed in the basal-like subtype by microarray analyses and immunohistochemical staining. After silencing β-catenin using siRNA, c-Myc expression was decreased in non-basal-like breast cancer cells. In contrast, c-Myc mRNA and protein expression were up-regulated in the basal-like breast cancer cell lines. Decreased c-Myc promoter activity was observed after inhibiting β-catenin by siRNA in non-basal-like breast cancer cells; however, inhibition of β-catenin or over-expression of dominant-negative LEF1 had no effect on c-Myc promoter activity in basal-like breast cancer cell lines. In addition, CDKN1A mRNA and p21 protein expression were significantly increased in all breast cancer cell lines upon β-catenin silencing. Interestingly, inhibiting β-catenin expression alone did not induce apoptosis in breast cancer cell lines despite c-Myc regulation, but we observed a modest increase of cells in the G1 phase of the cell cycle and decrease of cells in S phase upon β-catenin silencing. Our findings suggest that the regulation of c-Myc in breast cancer cells is dependent on the molecular subtype, and that β-catenin-mediated regulation of c-Myc and p21 may control the balance of cell death and proliferation in breast cancer.

GABA(A) receptor pi (GABRP) stimulates basal-like breast cancer cell migration through activation of extracellular-regulated kinase 1/2 (ERK1/2)

Breast cancer is a heterogeneous disease comprised of distinct subtypes predictive of patient outcome. Tumors of the basal-like subtype have a poor prognosis due to inherent aggressiveness and the lack of targeted therapeutics. Basal-like tumors typically lack estrogen receptor-α, progesterone receptor and HER2/ERBB2, or in other words they are triple negative (TN). Continued evaluation of basal-like breast cancer (BLBC) biology is essential to identify novel therapeutic targets. Expression of the pi subunit of the GABA(A) receptor (GABRP) is associated with the BLBC/TN subtype, and herein, we reveal its expression also correlates with metastases to the brain and poorer patient outcome. GABRP expression in breast cancer cell lines also demonstrates a significant correlation with the basal-like subtype suggesting that GABRP functions in the initiation and/or progression of basal-like tumors. To address this postulate, we stably silenced GABRP in two BLBC cell lines, HCC1187 and HCC70 cells. Decreased GABRP reduces in vitro tumorigenic potential and migration concurrent with alterations in the cytoskeleton, specifically diminished cellular protrusions and expression of the BLBC-associated cytokeratins, KRT5, KRT6B, KRT14, and KRT17. Silencing GABRP also decreases phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) in both cell lines and selective inhibition of ERK1/2 similarly decreases the basal-like cytokeratins as well as migration. Combined, these data reveal a GABRP-ERK1/2-cytokeratin axis that maintains the migratory phenotype of basal-like breast cancer. GABRP is a component of a cell surface receptor, thus, these findings suggest that targeting this new signaling axis may have therapeutic potential in BLBC.

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.

Basal-like breast cancer: update on clinicopathologic, immunohistochemical, and molecular features

CONTEXT

Basal-like breast carcinoma (BLBC) is a distinct molecular subtype of breast carcinoma identified through gene expression profiling studies.

OBJECTIVE

To provide the clinical background, the histologic profile, and the immunohistochemical profile of these tumors and discuss the current knowledge of their molecular signature and their implications on targeted molecular therapy.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

Basal-like breast carcinomas are aggressive tumors with poor prognosis. Lack of targeted therapy makes their treatment a challenging task. Traditional chemotherapy is still associated with a high risk of relapse and death in a high percentage of patients. Platinum-based chemotherapy has been considered as a candidate for the treatment of BLBCs owing to their BRCA1 phenotype. Approximately 22% of patients treated with single-agent cisplatin show pathologic complete response, which is a comparable rate to that seen with nonplatinum agents. Antiangiogenic agents have been promising, but their currently demonstrated limited response is considered disappointing. Additionally, epidermal growth factor receptor was not shown to be a helpful target for BLBC. A recent study has shown that BLBC appears to be especially sensitive to MEK inhibitors, making it a promising therapeutic possibility. The list of new targets is still evolving and the "magic" therapeutic target is yet to be discovered.

Clinicopathologic features, patterns of recurrence, and survival among women with triple-negative breast cancer in the National Comprehensive Cancer Network

BACKGROUND

The objective of this study was to describe clinicopathologic features, patterns of recurrence, and survival according to breast cancer subtype with a focus on triple-negative tumors.

METHODS

In total, 15,204 women were evaluated who presented to National Comprehensive Cancer Network centers with stage I through III breast cancer between January 2000 and December 2006. Tumors were classified as positive for estrogen receptor (ER) and/or progesterone receptor (PR) (hormone receptor [HR]-positive) and negative for human epidermal growth factor receptor 2 (HER2); positive for HER2 and any ER or PR status (HER2-positive); or negative for ER, PR, and HER2 (triple-negative).

RESULTS

Subtype distribution was triple-negative in 17% of women (n = 2569), HER2-positive in 17% of women (n = 2602), and HR-positive/HER2-negative in 66% of women (n = 10,033). The triple-negative subtype was more frequent in African Americans compared with Caucasians (adjusted odds ratio, 1.98; P < .0001). Premenopausal women, but not postmenopausal women, with high body mass index had an increased likelihood of having the triple-negative subtype (P = .02). Women with triple-negative cancers were less likely to present on the basis of an abnormal screening mammogram (29% vs 48%; P < .0001) and were more likely to present with higher tumor classification, but they were less likely to have lymph node involvement. Relative to HR-positive/HER2-negative tumors, triple-negative tumors were associated with a greater risk of brain or lung metastases; and women with triple-negative tumors had worse breast cancer-specific and overall survival, even after adjusting for age, disease stage, race, tumor grade, and receipt of adjuvant chemotherapy (overall survival: adjusted hazard ratio, 2.72; 95% confidence interval, 2.39-3.10; P < .0001). The difference in the risk of death by subtype was most dramatic within the first 2 years after diagnosis (overall survival for 0-2 years: OR, 6.10; 95% confidence interval, 4.81-7.74).

CONCLUSIONS

Triple-negative tumors were associated with unique risk factors and worse outcomes compared with HR-positive/HER2-negative tumors.

Therapeutic potential of PARP inhibitors for metastatic breast cancer

Increasing understanding of the cellular aberrations inherent to cancer cells has allowed the development of therapies to target biological pathways, an important step towards individualization of breast cancer therapy. The clinical development of poly(ADP-ribose) polymerase (PARP) inhibitors, with their novel and selective mechanism of action, are an example of this strategy. PARP plays a key role in DNA repair mechanisms, particularly the base excision repair pathway. Initially developed as inhibitors able to enhance the cytotoxicity of radiation and certain DNA-damaging agents, they have more recently been shown to have single-agent activity in certain tumors. Inhibition of PARP in a DNA repair-defective tumor can lead to gross genomic instability and cell death by exploiting the paradigm of synthetic lethality. Several studies have evaluated the role of PARP inhibitors for treatment of breast cancer, particularly in the context of BRCA-mutated and triple-negative breast cancers. In addition, inhibition of PARPs repair functions for chemotherapy-induced DNA lesions has been shown to potentiate the effect of some chemotherapy regimens. This article discusses the current understanding of PARP inhibition as a treatment for metastatic breast cancer, evidence from clinical trials and addresses its future implications.

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.

'Omic approaches to preventing or managing metastatic breast cancer

Early detection of metastasis-prone breast cancers and characterization of residual metastatic cancers are important in efforts to improve management of breast cancer. Applications of genome-scale molecular analysis technologies are making these complementary approaches possible by revealing molecular features uniquely associated with metastatic disease. Assays that reveal these molecular features will facilitate development of anatomic, histological and blood-based strategies that may enable detection prior to metastatic spread. Knowledge of these features also will guide development of therapeutic strategies that can be applied when metastatic disease burden is low, thereby increasing the probability of a curative response.

MYC and Breast Cancer

MYC is a key regulator of cell growth, proliferation, metabolism, differentiation, and apoptosis. MYC deregulation contributes to breast cancer development and progression and is associated with poor outcomes. Multiple mechanisms are involved in MYC deregulation in breast cancer, including gene amplification, transcriptional regulation, and mRNA and protein stabilization, which correlate with loss of tumor suppressors and activation of oncogenic pathways. The heterogeneity in breast cancer is increasingly recognized. Breast cancer has been classified into 5 or more subtypes based on gene expression profiles, and each subtype has distinct biological features and clinical outcomes. Among these subtypes, basal-like tumor is associated with a poor prognosis and has a lack of therapeutic targets. MYC is overexpressed in the basal-like subtype and may serve as a target for this aggressive subtype of breast cancer. Tumor suppressor BRCA1 inhibits MYC's transcriptional and transforming activity. Loss of BRCA1 with MYC overexpression leads to the development of breast cancer-especially, basal-like breast cancer. As a downstream effector of estrogen receptor and epidermal growth factor receptor family pathways, MYC may contribute to resistance to adjuvant therapy. Targeting MYC-regulated pathways in combination with inhibitors of other oncogenic pathways may provide a promising therapeutic strategy for breast cancer, the basal-like subtype in particular.

Insulin-like growth factor-dependent proliferation and survival of triple-negative breast cancer cells: implications for therapy

Triple-negative breast cancers have a poor prognosis and are not amenable to endocrine- or HER2-targeted therapies. The prevailing view is that targeting the insulin-like growth factor (IGF) signal transduction pathway will not be beneficial for triple-negative breast cancers because their growth is not IGF-responsive. The present study investigates the importance of IGFs in the proliferation and survival of triple-negative breast cancer cells. Estrogen and progesterone receptors, HER2, type I IGF, and insulin receptors were measured by Western transfer analysis. The effects of IGF-1 on proliferation were assessed by DNA quantitation and on cell survival by poly (ADP-ribose) polymerase cleavage. The effect of IGF-1 on phosphorylation of the IGF receptors, Akt and mitogen-activated protein kinase, was measured by Western transfer analysis. Seven cell lines were identified as models of triple-negative breast cancer and shown to express IGF receptors at levels similar to those present in estrogen-responsive cell lines known to respond to IGFs. IGF-1 increased the proliferation and cell survival of all triple-negative cell lines. Proliferation was attenuated after reduction of type I IGF receptor expression. Cells that express higher levels of receptor were more sensitive to subnanomolar IGF-1 concentrations, but the magnitude of the effects was not correlated simply with the absolute amount or phosphorylation of the IGF receptors, Akt or mitogen-activated protein kinase. These results show that IGFs stimulate cell proliferation and promote cell survival in triple-negative breast cancer cells and warrant investigation of the IGF signal transduction pathway as a therapeutic target for the treatment of triple-negative breast cancer.

A subset of breast cancer predisposes to brain metastasis

This study evaluated the expression of biological markers of breast cancers with brain metastases. Eighteen paired tumors were assessed, with 42 non-brain-metastasizing breast cancers that were stained with ER, PR, HER2, CK5/6, p63, and Ki67, and were also classified into intrinsic subtypes. The expression patterns between the breast tumors with brain metastases were compared to the brain metastases and the controls. Breast cancers with brain metastases were of higher grade and showed higher incidence of lymph node metastases at initial diagnosis and higher EGFR, p63, and Ki67 expression. In the group of breast cancers with brain metastases, the brain metastases showed higher HER2, CK5/6, and Ki67 expression compared to the breast primaries. There was also a higher incidence of basal subtype and a lower incidence of luminal subtype. When tumors metastasized, changes in hormonal receptor (22%) and HER2 (6%) status were observed. We concluded that breast cancers with higher grade, lymph node involvement at diagnosis, high EGFR, p63, and Ki67 expression, and of basal subtype were at higher risk for brain metastases, and that both hormonal receptors and HER2 status may change in brain metastases.

Management options in triple-negative breast cancer

Notorious for its poor prognosis and aggressive nature, triple-negative breast cancer (TNBC) is a heterogeneous disease entity. The nature of its biological specificity, which is similar to basal-like cancers, tumors arising in BRCA1 mutation carriers, and claudin-low cancers, is currently being explored in hopes of finding the targets for novel biologics and chemotherapeutic agents. In this review, we aim to give a broad overview of the disease's nomenclature and epidemiology, as well as the basic mechanisms of emerging targeted therapies and their performance in clinical trials to date.

Expression of endoplasmic reticulum stress proteins is a candidate marker of brain metastasis in both ErbB-2+ and ErbB-2- primary breast tumors

The increasing incidence of breast cancer brain metastasis in patients with otherwise well-controlled systemic cancer is a key challenge in cancer research. It is necessary to understand the properties of brain-tropic tumor cells to identify patients at risk for brain metastasis. Here we attempt to identify functional phenotypes that might enhance brain metastasis. To obtain an accurate classification of brain metastasis proteins, we mapped organ-specific brain metastasis gene expression signatures onto an experimental protein-protein interaction network based on brain metastatic cells. Thirty-seven proteins were differentially expressed between brain metastases and non-brain metastases. Analysis of metastatic tissues, the use of bioinformatic approaches, and the characterization of protein expression in tumors with or without metastasis identified candidate markers. A multivariate analysis based on stepwise logistic regression revealed GRP94, FN14, and inhibin as the best combination to discriminate between brain and non-brain metastases (ROC AUC = 0.85, 95% CI = 0.73 to 0.96 for the combination of the three proteins). These markers substantially improve the discrimination of brain metastasis compared with ErbB-2 alone (AUC = 0.76, 95% CI = 0.60 to 0.93). Furthermore, GRP94 was a better negative marker (LR = 0.16) than ErbB-2 (LR = 0.42). We conclude that, in breast carcinomas, certain proteins associated with the endoplasmic reticulum stress phenotype are candidate markers of brain metastasis.

Lymphatic and blood vessels in basal and triple-negative breast cancers: characteristics and prognostic significance

Basal and triple-negative breast cancer phenotypes are characterised by unfavourable biological behaviour and outcome. Although certain studies have examined their pathological and molecular profile, the vascular characteristics of lymphatic and blood vessels have not been examined. Immunohistochemical staining with podoplanin, CD34 and CD31 was used to examine lymphatic and microvessel density, as well as vascular invasion in 197 basal-like and in 99 triple-negative breast tumours and compared against 200 non-basal and 334 non-triple-negative cases. All specimens were lymph node negative. Vascular invasion was identified as blood or lymphatic vascular invasion by the differential expression of markers. All measurements were correlated with clinicopathological features and prognosis. No significant difference was detected between the basal and triple-negative groups in terms of lymphatic or microvessel density or vascular invasion. However, both the basal and the triple-negative groups showed significantly higher microvessel density than did the non-basal and non-triple-negative groups (P=0.017 and P<0.001, respectively). Unlike microvessel density, no significant difference was detected in lymphatic density between the basal or triple-negative groups compared with their respective controls. Interestingly, vascular invasion, almost entirely lymphatic invasion, was detected in 27% of the basal and in 26% of the triple-negative groups with no significant difference in comparison with control groups. In both basal and triple negatives, vascular invasion was associated with poorer survival by univariate and multivariate analyses. The 20-year overall survival rate in basal-like tumours was 55% in vascular invasion-positive cases compared with 73% in vascular invasion-negative tumours (P=0.012), and 46% in triple-negative vascular invasion-positive compared with 79% in vascular invasion-negative tumours (P=0.001). Basal-like vs non-basal-like and triple-negative vs non-triple-negative tumours have similar vascular characteristics in terms of lymphatic vessel density and vascular invasion but higher microvessel density, suggesting that such groups may preferentially benefit from anti-angiogenic therapy. Vascular invasion was, in all phenotypes, almost entirely lymphatic vessel invasion and could stratify basal-like and triple-negative phenotypes into distinct prognostic groups.

Current strategy for triple-negative breast cancer: appropriate combination of surgery, radiation, and chemotherapy

Triple-negative breast cancer (TNBC) often grows rapidly and has poor outcomes, with a high recurrence rate and a short interval between recurrence and death. New molecular-targeted therapies are being developed, but cannot be used at present. Other strategies for the management of TNBC are needed. TNBC is characterized by an expanding growth pattern without extensive intraductal spread and is a good candidate for breast-conserving therapy (BCT) with sufficient margins. The local recurrence rate after BCT is not high as those of other subtypes of breast cancer. In contrast, the regional recurrence rate is higher in TNBC than in other subtypes. Sentinel node biopsy and axillary resection should therefore be performed with the upmost caution. Radiation therapy has been shown to be useful for the management of TNBC. Radiation therapy of the chest wall after mastectomy and the regional area as well as the breast after breast-conserving surgery should be considered. Chemotherapy is the only systemic treatment available for TNBC. In our hospital, a combination of cyclophosphamide, epirubicin, and 5-fluorouracil (FEC) followed by docetaxel (DTX) or DTX followed by FEC has been used to treat tumors more than 2 cm in diameter or node-positive breast cancer. Neoadjuvant chemotherapy with these regimens has produced pathological complete response (pCR) rates higher than 20% in patients with TNBC, regardless of the specific order of agents. Tumors tend to shrink towards their center and can be a good indication for BCT. After 3 years, a pCR is associated with good outcomes, whereas a non-pCR sometimes results in distant recurrence, even when residual tumor is minimal. Patients should be closely observed during neoadjuvant chemotherapy. If there is any evidence of tumor progression, the chemotherapeutic regimen should be modified or surgery performed, without losing the opportunity to administer potentially effective treatment. Several studies indicate that neoadjuvant chemotherapy with platinum-based regimens is effective for TNBC and is thus an important treatment option. We have used regimens combining epirubicin and cyclophosphamide (EC) to treat tumors 1-2 cm in diameter without node metastasis, and 2 of 21 patients presented with distant metastases (disease-free interval, 2 and 5 years). We have not used systemic therapy to treat tumors 1 cm or less in diameter without node metastasis, and all 8 patients are alive without recurrence for more than 4 years. After distant recurrence in patients with TNBC, the same chemotherapeutic agents as those used for other subtypes of breast cancer are recommended, but the response is often disappointing, leading to poor outcomes. TNBC presents with different clinical features from other subtypes. The treatment strategy should be selected according to the characteristics of the specific subtype of breast cancer.

Minireview: Basal-like breast cancer: from molecular profiles to targeted therapies

The classification of breast cancer into molecular subtypes with distinctive gene expression signatures that predict treatment response and prognosis has ushered in a new era of personalized medicine for this remarkably heterogeneous and deadly disease. Basal-like breast cancer (BLBC) is a particularly aggressive molecular subtype defined by a robust cluster of genes expressed by epithelial cells in the basal or outer layer of the adult mammary gland. BLBC is a major clinical challenge because these tumors are prevalent in young woman, often relapsing rapidly. Additionally, most (but not all) basal-like tumors lack expression of steroid hormone receptors (estrogen receptor and progesterone receptor) and human epidermal growth factor receptor 2, limiting targeted therapeutic options for these predominantly triple-negative breast cancers. This minireview will focus on new insights into the molecular etiology of these poor-prognosis tumors that underlie their intrinsic genomic instability, deregulated cell proliferation and apoptosis, and invasive tumor biology. We will also review ongoing efforts to translate these fundamental insights into improved therapies for women with BLBC.

[Patient follow-up after treatment for breast cancer]

Patient follow-up after treatment for a breast cancer is based on the local recurrence risk. Annual mammography remains the main point of this follow-up and tumor markers detection has still no interest. Absence of benefit of an intensive clinical, biological and radiological surveillance has been proved for a long time but expert recommendations still are a subject of discussion although they knew no evolution for more than 10 years. Evolution of those follow-up modalities will depend on the future indications of MRI and PET. About distant recurrence, a better knowledge of the risk is now possible thanks to the tumor biological profile study. Nevertheless, intensification of follow-up for some kind of high-risk tumors will have interest only if we can propose a therapeutic alternative in metastatic situation.

Triple-negative or HER2-positive status predicts higher rates of locoregional recurrence in node-positive breast cancer patients after mastectomy

PURPOSE

To evaluate the prognostic value of determining estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) expression in node-positive breast cancer patients treated with mastectomy.

METHODS AND MATERIALS

The records of 835 node-positive breast cancer patients who had undergone mastectomy between January 2000 and December 2004 were analyzed retrospectively. Of these, 764 patients (91.5%) received chemotherapy; 68 of 398 patients (20.9%) with T1-2N1 disease and 352 of 437 patients (80.5%) with T3-4 or N2-3 disease received postoperative radiotherapy. Patients were classified into four subgroups according to hormone receptor (Rec+ or Rec-) and HER2 expression profiles: Rec-/HER2- (triple negative; n = 141), Rec-/HER2+ (n = 99), Rec+/HER2+ (n = 157), and Rec+/HER2- (n = 438). The endpoints were the duration of locoregional recurrence-free survival, distant metastasis-free survival, disease-free survival, and overall survival.

RESULTS

Patients with triple-negative, Rec-/HER2+, and Rec+/HER2+ expression profiles had a significantly lower 5-year locoregional recurrence-free survival than those with Rec+/HER2- profiles (86.5% vs. 93.6%, p = 0.002). Compared with those with Rec+/HER2+ and Rec+/HER2- profiles, patients with Rec-/HER2- and Rec-/HER2+ profiles had significantly lower 5-year distant metastasis-free survival (69.1% vs. 78.5%, p = 0.000), lower disease-free survival (66.6% vs. 75.6%, p = 0.000), and lower overall survival (71.4% vs. 84.2%, p = 0.000). Triple-negative or Rec-/HER2+ breast cancers had an increased likelihood of relapse and death within the first 3 years after treatment.

CONCLUSIONS

Triple-negative and HER2-positive profiles are useful markers of prognosis for locoregional recurrence and survival in node-positive breast cancer patients treated with mastectomy.

Triple negative breast cancer: outcome correlation with immunohistochemical detection of basal markers

We earlier evaluated the relationship of 653 triple negative breast cancers (TNBC) with basal immunophenotypic expression by using antibodies to basal cytokeratins (CK5/6, CK14, CK17, 34betaE12), p63, smooth muscle actin (SMA), epidermal growth factor receptor, and CD117, and found that a triple panel of CK14, 34betaE12 and epidermal growth factor receptor determined 84% of our cases to be basal-like. Women with basal-like TNBC tended to be younger (P=0.04), have histologically higher-grade tumors (P=0.047), with positive nodal status (P=0.047), than those whose tumors were nonbasal-like. Using univariate Cox regression analysis, tumor size (P=0.003), histologic grade (P=0.006), and nodal status (P=0.017) were significant factors for disease-free survival (DFS) among TNBC, whereas age (P=0.004), tumor size (P=0.001), histologic grade (P<0.001), nodal status (P=0.011), lymphovascular invasion (P=0.032), and pushing borders (P=0.042) were important for overall survival (OS). On multivariate analysis, age was statistically significant for both DFS and OS (P=0.033, 0.001 respectively), whereas histologic grade was important for OS (P<0.001). Kaplan Meier curves showed CK17 positivity to impact adversely on DFS (P=0.003) and OS (P=0.014), whereas CD117 positive staining was accompanied by diminished OS (P=0.036). SMA expression in TNBC however, revealed a trend for improved DFS (P=0.05). Our findings indicate that basal-like TNBC are associated with adverse clinicopathologic parameters, and that individual biologic markers of CK17, CD117, and SMA have prognostic implications on survival. Possibilities exist for future targeted therapy for this challenging group of breast cancers.

HER3 and downstream pathways are involved in colonization of brain metastases from breast cancer

INTRODUCTION

Metastases to the brain from breast cancer have a high mortality, and basal-like breast cancers have a propensity for brain metastases. However, the mechanisms that allow cells to colonize the brain are unclear.

METHODS

We used morphology, immunohistochemistry, gene expression and somatic mutation profiling to analyze 39 matched pairs of primary breast cancers and brain metastases, 22 unmatched brain metastases of breast cancer, 11 non-breast brain metastases and 6 autopsy cases of patients with breast cancer metastases to multiple sites, including the brain.

RESULTS

Most brain metastases were triple negative and basal-like. The brain metastases over-expressed one or more members of the HER family and in particular HER3 was significantly over-expressed relative to matched primary tumors. Brain metastases from breast and other primary sites, and metastases to multiple organs in the autopsied cases, also contained somatic mutations in EGFR, HRAS, KRAS, NRAS or PIK3CA. This paralleled the frequent activation of AKT and MAPK pathways. In particular, activation of the MAPK pathway was increased in the brain metastases compared to the primary tumors.

CONCLUSIONS

Deregulated HER family receptors, particularly HER3, and their downstream pathways are implicated in colonization of brain metastasis. The need for HER family receptors to dimerize for activation suggests that tumors may be susceptible to combinations of anti-HER family inhibitors, and may even be effective in the absence of HER2 amplification (that is, in triple negative/basal cancers). However, the presence of activating mutations in PIK3CA, HRAS, KRAS and NRAS suggests the necessity for also specifically targeting downstream molecules.

Increased Incidence of Visceral Metastases in Scottish Patients With BRCA1/2-Defective Ovarian Cancer: An Extension of the Ovarian BRCAness Phenotype

Purpose

To compare the frequency of visceral relapse of BRCA1/2-deficient ovarian cancer to that of nonhereditary controls.

Patients and Methods

All patients diagnosed in Scotland with epithelial ovarian cancer (EOC) or primary peritoneal cancer (PPC) and a germline BRCA1/2 mutation were identified. Those with previous malignancy were excluded. Each remaining patient who experienced relapse was matched with two nonhereditary controls.

Results

Seventy-nine patients with EOC/PPC and germline BRCA1/2 mutations were identified. Fifteen had inadequate clinical data, two had carcinosarcoma, 27 had previous breast cancer, and 16 were in remission. Of the remaining 19 patients who were BRCA1/2 deficient, 14 patients (74%) developed visceral metastases compared with six (16%) of 38 patients in the control group. The percentages of liver, lung, and splenic metastases were 53%, 32%, and 32%, respectively, in the patients compared with 5%, 3%, and 5%, respectively, in the controls. When events occurring outside the matched follow-up period were omitted, the percentages of visceral, liver, lung, and splenic metastases were 58%, 42%, 16%, and 32% in the patients compared with 5%, 0%, 0%, and 3% in controls (P < .001, P < .001, P = .066, and P = .011, respectively). In an independent validation set, the corresponding percentages of visceral, liver, lung, and splenic metastases were 63%, 46%, 13%, and 17% in the patients compared with 11%, 4%, 2%, and 2% in controls (P < .001, P < .001, P = .153, and P = .052, respectively).

Conclusion

Although sporadic EOC commonly remains confined to the peritoneum, BRCA1/2-deficient ovarian cancer frequently metastasizes to viscera. These data extend the ovarian BRCAness phenotype, imply BRCA1/2-deficient ovarian cancer is biologically distinct, and suggest that patients with visceral metastases should be considered for BRCA1/2 sequencing.

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.

The role of intra-cerebrospinal fluid treatment and prophylaxis in patients with solid tumors

Metastasis to the central nervous system (CNS), including neoplastic meningitis (NM), is a devastating complication of systemic cancer. With the improved survival of cancer patients, the incidence of CNS metastasis is rising, especially among those with breast or lung carcinoma. New therapies that effectively treat these primary tumors outside of the CNS have underscored the significance of CNS metastases; they have become a significant clinical issue and a therapeutic challenge. This review discusses clinical situations in which treatment or chemoprophylaxis of CNS metastases and NM from breast or lung cancer may play an important role. Potential clinical trials to assess these assumptions also will be proposed.

Prognostic value of Dicer expression in human breast cancers and association with the mesenchymal phenotype

BACKGROUND

Dicer, a ribonuclease, is the key enzyme required for the biogenesis of microRNAs and small interfering RNAs and is essential for both mammalian development and cell differentiation. Recent evidence indicates that Dicer may also be involved in tumourigenesis. However, no studies have examined the clinical significance of Dicer at both the RNA and the protein levels in breast cancer.

METHODS

In this study, the biological and prognostic value of Dicer expression was assessed in breast cancer cell lines, breast cancer progression cellular models, and in two well-characterised sets of breast carcinoma samples obtained from patients with long-term follow-up using tissue microarrays and quantitative reverse transcription-PCR.

RESULTS

We have found that Dicer protein expression is significantly associated with hormone receptor status and cancer subtype in breast tumours (ER P=0.008; PR P=0.019; cancer subtype P=0.023, luminal A P=0.0174). Dicer mRNA expression appeared to have an independent prognostic impact in metastatic disease (hazard ratio=3.36, P=0.0032). In the breast cancer cell lines, lower Dicer expression was found in cells harbouring a mesenchymal phenotype and in metastatic bone derivatives of a breast cancer cell line. These findings suggest that the downregulation of Dicer expression may be related to the metastatic spread of tumours.

CONCLUSION

Assessment of Dicer expression may facilitate prediction of distant metastases for patients suffering from 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.

Triple-negative/basal-like breast cancer: review

Breast cancer comprises a heterogeneous group of diseases that vary in morphology, biology, behaviour and response to therapy. Triple-negative (TN) breast cancer is a subtype of tumours with aggressive clinical behaviour which currently lacks effective targeted therapies. The majority of TN breast cancers possess a basal phenotype and show varying degrees of basal marker expression (basal-like tumours). The importance of recognising these tumours came to light largely as the result of global gene expression profiling studies that categorised breast cancer into distinct molecular classes. These studies showed that basal-like tumours are molecularly different from hormone receptors and HER2 positive tumours. Although both TN and basal-like tumours share many molecular and morphological features, equating both tumour classes may be misleading. A better understanding of the molecular and histopathological features of TN and basal-like cancers is of paramount importance, in particular for unravelling the heterogeneous nature of these tumour subgroups and for the identification of prognostic biomarkers, ideal systemic therapy regimens and novel therapeutic targets for these aggressive tumours. In this review, we discuss the difference between TN and basal-like tumours, pathological and clinical features of basal-like cancer and hence explore the criteria that can be used to identify these tumours in routine practice.

"New" molecular taxonomy in breast cancer

Advances in the analysis of expression profiles, using genomic techniques, have revealed the high heterogeneity present in breast cancers. These approaches have served to identify different breast cancer subgroups with specific molecular characteristics that could sub-classify these tumours as carcinomas expressing hormone receptors, denominated Luminal subtype, and tumours with negative expression of hormone receptors, the Basal and HER2+ phenotypes. Therefore, during recent years, identification of markers characteristic of each subtype has been the focus of many research groups. All of these breast tumour subtypes probably have specific clinical and morphological features; however, this hypothesis needs to be confirmed by analysing more homogenous series. Although this "new" classification has limitations, it could be useful in the clinical practice, allowing not only a more accurate prognosis in breast cancer patients but also a selective treatment for each predefined subtype.

Triple-negative breast cancer: risk factors to potential targets

Triple-negative breast cancer has recently been recognized as an important subgroup of breast cancer with a distinct outcome and therapeutic approach when compared with other subgroups of breast cancer. Triple-negative breast cancer comprises primarily, but not exclusively, a molecularly distinct subtype of breast cancer, the basal-like subtype. We do not yet have an assay to identify basal-like breast cancer in clinical samples, so triple-negative breast cancer has become a commonly used proxy for this subtype. The molecular biology and pathophysiology of triple-negative breast cancer are not completely understood, but understanding is improving rapidly with the advent of sophisticated molecular biology platforms. Moreover, the established risk factors of breast cancer as a whole may not apply to this unique subgroup of patients. Finally, because triple-negative breast cancer is defined by the absence of a target, there are currently limitations to using a tailored therapeutic approach, leaving conventional cytotoxic therapies as the mainstay. Active preclinical and clinical research programs focus on defining the clinical behavior, delineating the risk factors, and more completely understanding the molecular biology of triple-negative breast cancer to improve prevention, optimize conventional agents, and unveil novel therapeutic targets. This CCR focus article will review the current state of the art on triple-negative breast cancer.

[Basal and myoepithelial phenotype of metastatic mammary carcinomas. A prognostic factor in the palliative situation?]

AIMS

The aim of the present study was to evaluate the prognostic impact of basal and myoepithelial phenotype in breast carcinomas (BBC and MBC) in the palliative situation.

METHODS

Paraffin-embedded material from 244 primary breast carcinomas of patients with subsequent metastatic disease was stained immunohistochemically for CK 5/6, CK14, smooth-muscle actin, p63, estrogen receptor and progesterone receptor. BBC was defined as positive for CK5/6 and/or CK14 and MBC as positive for SMA and/or p63. Clinical and pathological data were available for all patients and follow-up data for 96.3% (range 5 days-151 months).

RESULTS

Until the end of the follow-up period 90.2% of patients died and 6.1% are still alive. Of the tumours 28.7% could be classified as BBC and 8.2% as MBC. Kaplan Meier analysis revealed a trend for reduced survival after first diagnosis of metastasis (OASM) for BBC and MBC. Differences in survival were significant for BBC (log-rank =5.0; p=0.025), but not for MBC. CK5/6+ and CK14+ double positive tumours (n=18; 7.4%) were identified as a subgroup of BBC associated with reduced OASM (log-rank=8,6; p=0.003). This subgroup, but not BBC or MBC was an independent negative prognostic factor in a multivariate analysis including age, typing, tumour size, grading, axillary nodes, HR, Her2/neu, site of first metastasis and disease-free interval.

CONCLUSION

The association of BBC and MBC with reduced OASM in metastatic breast carcinomas is not independent from established prognostic factors. CK5/6+ CK14+ double positive tumours may be a subgroup of BBC with particularly unfavourable outcome.

Establishment and quantitative imaging of a 3D lung organotypic model of mammary tumor outgrowth

The lung is the second most common site of metastatic spread in breast cancer and experimental evidence has been provided in many systems for the importance of an organ-specific microenvironment in the development of metastasis. To better understand the interaction between tumor and host cells in this important secondary site, we have developed a 3D in vitro organotypic model of breast tumor metastatic growth in the lung. In our model, cells isolated from mouse lungs are placed in a collagen sponge to serve as a scaffold and co-cultured with a green fluorescent protein-labeled polyoma virus middle T antigen (PyVT) mammary tumor cell line. Analysis of the co-culture system was performed using flow cytometry to determine the relative constitution of the co-cultures over time. This analysis determined that the cultures consisted of viable lung and breast cancer cells over a 5-day period. Confocal microscopy was then used to perform live cell imaging of the co-cultures over time. Our studies determined that host lung cells influence the ability of tumor cells to grow, as the presence of lung parenchyma positively affected the proliferation of the mammary tumor cells in culture. In summary, we have developed a novel in vitro model of breast tumor cells in a common metastatic site that can be used to study tumor/host interactions in an important microenvironment.