Molecular Apocrine Tumors Research Articles

Apocrine carcinoma of the breast: Review

Abstract Apocrine carcinoma of the breast is a rare subtype of breast carcinoma, which only presents as 4% among patients with breast cancer. The percentage varies based on the diagnostic criteria used by each institution to classify apocrine carcinoma. Several confusing terms used in previous studies, including apocrine ductal carcinoma in situ (ADCIS), apocrine morphology in lobular carcinoma in situ (Apocrine LCIS), apocrine-like invasive carcinoma, pure apocrine carcinoma, molecular apocrine tumors (MATs), and triple-negative apocrine carcinoma of the breast (TNAC). The treatment, prognosis, and molecular profiles are also diverse. Pure apocrine carcinoma has stricter criteria for diagnosis, requiring more than 90% of cells showing apocrine morphology and classic IHC characteristics of ER-negative, PR-negative, and AR-positive in at least 10% of tumor cell nuclei. Research related to prognosis is diverse due to the difficulty of unifying the diagnostic criteria. Current evidence of treatment is geared toward the use of neoadjuvant chemotherapy and anti-androgen therapy when AR is present, accompanied by other treatments if biomarkers are present, such as HER2, PI3K, or CDK4/6. This article focuses on clearly summarizing different subtypes and management of apocrine carcinoma of the breast.

Bc-GenExMiner 4.5: new mining module computes breast cancer differential gene expression analyses.

‘Breast cancer gene-expression miner’ (bc-GenExMiner) is a breast cancer–associated web portal (http://bcgenex.ico.unicancer.fr). Here, we describe the development of a new statistical mining module, which permits several differential gene expression analyses, i.e. ‘Expression’ module. Sixty-two breast cancer cohorts and one healthy breast cohort with their corresponding clinicopathological information are included in bc-GenExMiner v4.5 version. Analyses are based on microarray or RNAseq transcriptomic data. Thirty-nine differential gene expression analyses, grouped into 13 categories, according to clinicopathological and molecular characteristics (‘Targeted’ and ‘Exhaustive’) and gene expression (‘Customized’), have been developed. Output results are visualized in four forms of plots. This new statistical mining module offers, among other things, the possibility to compare gene expression in healthy (cancer-free), tumour-adjacent and tumour tissues at once and in three triple-negative breast cancer subtypes (i.e. C1: molecular apocrine tumours; C2: basal-like tumours infiltrated by immune suppressive cells and C3: basal-like tumours triggering an ineffective immune response). Several validation tests showed that bioinformatics process did not alter the pathobiological information contained in the source data. In this work, we developed and demonstrated that bc-GenExMiner ‘Expression’ module can be used for exploratory and validation purposes. Database URL: http://bcgenex.ico.unicancer.fr

Molecular apocrine tumours in EORTC 10994/BIG 1-00 phase III study: pathological response after neoadjuvant chemotherapy and clinical outcomes

BackgroundWe explored, within the EORTC10994 study, the outcomes for patients with molecular apocrine (MA) breast cancer, and defined immunohistochemistry (IHC) as androgen-receptor (AR) positive, oestrogen (ER) and progesterone (PR) negative. We also assessed the concordance between IHC and gene expression arrays (GEA) in the identification of MA cancers.MethodsCentrally assessed biopsies for AR, ER, PR, HER2 and Ki67 by IHC were classified into six subtypes: MA, triple-negative (TN) basal-like, luminal A, luminal B HER2 negative, luminal B HER2 positive and “other”. The two main objectives were the pCR rates and survival outcomes in the overall MA subtype (and further divided by HER2 status) and the remaining five subtypes.ResultsIHC subtyping was obtained in 846 eligible patients. Ninety-three (11%) tumours were classified as the MA subtype. Both IHC and GEA data were available for 64 patients. In this subset, IHC concordance was 88.3% in identifying MA tumours compared with GEA. Within the MA subtype, pCR was observed in 33.3% of the patients (95% CI: 29.4–43.9) and the 5-year recurrence-free interval was 59.2% (95% CI: 48.2–68.6). Patients with MA and TN basal-like tumours have lower survival outcomes.ConclusionsIrrespective of their HER2 status, the prognosis for MA tumours remains poor and adjuvant trials evaluating anti-androgens should be considered.

Apocrine lesions of the breast: part 2 of a two-part review. Invasive apocrine carcinoma, the molecular apocrine signature and utility of immunohistochemistry in the diagnosis of apocrine lesions of the breast

Pure apocrine carcinoma of the breast is rare and has been defined by using a combination of morphologic (apocrine morphology in >90% of tumour cells) and immunohistochemical criteria (oestrogen receptor...

Abstract P4-21-21: Her2 is not a cancer subtype but rather a driver found in all intrinsic subtypes and highly enriched in molecular apocrine tumors

Abstract Her2-enriched (Her2E) breast tumors defined by molecular profiling are discrepant from Her2-amplified tumors defined by clinical assessment – over half of all Her2-amplified tumors are not Her2E, while one-third of Her2E tumors are not Her2-amplified. We explored this discordance using genomic profiles of 4,000 breast tumors. We find clear support that Her2 amplification is a discrete cancer driver event and not a subtype, with little genomic impact other than in expression of genes on the amplicon. Many Her2-amplified tumors clearly belong to the basal, luminal A, or luminal B subtypes. After accounting for the Her2 amplicon, most tumors classified as Her2E appear to be molecular apocrine, expressing high levels of androgen receptor and low to moderate levels of ER. The high rate of Her2 amplification in this group (63%) suggests that additional growth drivers are required for molecular apocrine tumors. Her2 amplification is also a driver across subtypes of several non-breast tumor types. Her2 is amplified in 2% of 5,400 non-breast tumors, spanning 23 tumor types. The Her2 region in non-breast cancers shows a similar range of amplification and breadth of the amplicon, and a comparable rate of overexpression of genes within the amplicon for most Her2A tumors. These discoveries reveal therapeutic opportunities for combining anti-Her2 therapy with endocrine or anti-androgen agents for breast cancer, and for expanding anti-Her2 therapy to other tumor types. Citation Format: Daemen A, Manning G. Her2 is not a cancer subtype but rather a driver found in all intrinsic subtypes and highly enriched in molecular apocrine tumors [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-21.

Abstract P4-06-02: The mammary ducts create a favourable microenvironment for xenografting of luminal and molecular apocrine breast tumours

Abstract This abstract was not presented at the symposium.

The mammary ducts create a favourable microenvironment for xenografting of luminal and molecular apocrine breast tumours.

There is a paucity of models for hormone receptor-positive (HR+) breast cancer because of the difficulty of establishing xenografts from these tumours. We show that this obstacle can be overcome by injecting human tumour cells directly into the mammary ducts of immunodeficient mice. Tumours from 31 patients were infected overnight with a lentiviral vector expressing tdTomato and injected through the nipple into the mammary ducts of NOD-SCID-IL2RG-/- mice. Tumours formed in the mice in 77% of cases after the first injection (6/8 luminal A, 15/20 luminal B, and 3/3 molecular apocrine). Four luminal A and one molecular apocrine graft were tested in secondary and tertiary grafts: all were successfully passaged in secondary and 4/5 in tertiary grafts. None of the samples engrafted when injected subcutaneously. The morphology, oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), and Ki-67 profiles of the clinical samples were maintained in the tertiary grafts. We also show that the intraductal approach can be used to test the response to targeted therapy with fulvestrant and palbociclib, using a genetically defined ER+ model. We conclude that the mammary ducts create a microenvironment that is uniquely favourable to the survival and growth of tumours derived from mammary hormone-sensing cells. This approach opens the door to testing genomically targeted treatment of HR+ tumours in precision medicine programmes. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A phase II trial of abiraterone acetate plus prednisone in patients with triple-negative androgen receptor positive locally advanced or metastatic breast cancer (UCBG 12-1)

Several expression array studies identified molecular apocrine breast cancer (BC) as a subtype that expresses androgen receptor (AR) but not estrogen receptor α. We carried out a multicentre single-arm phase II trial in women with AR-positive, estrogen, progesterone receptor and HER2-negative (triple-negative) metastatic or inoperable locally advanced BC to assess the efficacy and safety of abiraterone acetate (AA) plus prednisone. Patients with a metastatic or locally advanced, centrally reviewed, triple-negative and AR-positive (≥10% by immunohistochemistry, IHC) BC were eligible. Any number of previous lines of chemotherapy was allowed. AA (1000 mg) was administered once a day with prednisone (5 mg) twice a day until disease progression or intolerance. The primary end point was clinical benefit rate (CBR) at 6 months defined as the proportion of patients presenting a complete response (CR), partial response (PR) or stable disease (SD) ≥6 months. Secondary end points were objective response rate (ORR), progression-free survival (PFS) and safety. One hundred and forty-six patients from 27 centres consented for IHC central review. Of the 138 patients with sufficient tissue available, 53 (37.6%) were AR-positive and triple-negative, and 34 of them were included from July 2013 to December 2014. Thirty patients were eligible and evaluable for the primary end point. The 6-month CBR was 20.0% [95% confidence interval (CI) 7.7%-38.6%], including 1 CR and 5 SD ≥6 months, 5 of them still being under treatment at the time of analysis (6.4+, 9.2+, 14.5+, 17.6+, 23.4+ months). The ORR was 6.7% (95% CI 0.8%-22.1%). The median PFS was 2.8 months (95% CI 1.7%-5.4%). Fatigue, hypertension, hypokalaemia and nausea were the most common drug-related adverse events; the majority of them being grade 1 or 2. AA plus prednisone treatment is beneficial for some patients with molecular apocrine tumours and five patients are still on treatment. NCT01842321.

Abstract P5-05-02: Expression of androgen receptor and FOXA1 in non metastatic poor prognosis HER2- negative breast cancer: Ancillary study from UNICANCER-PACS08 multicenter trial

Abstract Background Androgen receptor (AR) is expressed in 70-90% of estrogen receptor (ER) positive breast cancer but its expression in triple negative (TN) tumors is less frequent and extremely variable across studies, probably due to their heterogeneity. FOXA1 is essential for expression of 50% of ER-related genes and is a good prognostic factor in luminal tumors. Microarray studies identified the subgroup of molecular apocrine tumors (ER-, AR+) expressing luminal genes including FOXA1, for which pre-clinical data suggested that FOXA1 may direct AR to sites normally occupied by ER in luminal tumors, inducing an estrogen-like gene program stimulating proliferation. We aimed at precising AR expression-associated profiles among a prospective collection of HER2-negative, progesterone receptor (PR)-negative breast tumors. Patients and methods Expression of AR and FOXA1 were evaluated by immunohistochemistry on tissue microarrays in 762 patients enrolled in the PACS08 adjuvant randomized trial evaluating ixabepilone in patients with TN or ER+, PR-, HER2- poor prognosis breast cancer. Two observers evaluated independently AR and FOXA1 expressions. A tumor was considered as positive when at least 10% of the tumor cells were stained. Kappa coefficients were used to assess the agreement between the 2 observers. Categorical clinico-pathological characteristics according to AR and/or FOXA1 expression were compared using Chi-square test or Fisher's exact test when appropriate. Student's t-test and the One way Anova were used to compare continuous variable across patient groups. Results Evaluation of AR and FOXA1 expressions were highly reproducible with inter-observer Kappa coefficients of 0.96 and 0.90 respectively. Both AR and FOXA1 expressions were available in 592 cases, 38% of which were AR+ and 30% FOXA1+. The majority (59.6%) of the tumors was AR-/FOXA1-, 27.9% were AR+/FOXA1+. AR+/FOXA1+ tumors were more frequently: found in older patients (p<0.0001), multifocal (p = 0.02), lobular (p<0.0001), ER+ (p<0.0001), of lower nuclear grade (p<0.0001), and exhibited more in situ component (p = 0.0002), lympho-vascular invasion (p = 0.02) and node involvement (p<0.0001) than other subgroups. Among 487 TN and 136 ER+ tumors, 25.9% and 80.9% respectively were AR+. Among 468 TN and 134 ER+ tumors, 16.4% and 77.6% respectively were FOXA1+. In TN patients, both AR and FOXA1 expressions were available in 460 cases, 72.8% of which were AR-/FOXA1- and 15.2% AR+/FOXA1+. FOXA1+ tumors were more frequently of lobular histology (p = 0.02). AR+/FOXA1+ tumors were more frequently found in older patients (p = 0.0002), had lower nuclear grade (p<0.0001), showed more lympho-vascular invasion (p = 0.001) and more node involvement (p<0.0001). The follow-up is currently too short to report the prognostic value of these markers. Conclusions ER+ tumors were mainly AR+/FOXA1+. In this large series, 25.9% of TN tumors were AR+. AR+/FOXA1+ tumors represent 15.2% of TN tumors and seem to behave like luminal tumors (older patients, lobular histology, lower nuclear grade, node involvement). Anti-androgen therapies are currently under investigation in TN breast cancer; these results stimulate also consideration of FOXA1 as potential therapeutic target. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-05-02.

P53 in breast cancer subtypes and new insights into response to chemotherapy

Despite an obvious central role of p53 in the hallmarks of cancer, TP53 status is not yet used for the management of breast cancer. Recent findings may lead to reconsider the role of p53 in breast cancer.TP53 mutations are the most frequent genetic alterations in breast cancer, observed in 30% of breast carcinomas. Their distribution is highly linked to molecular tumor subtypes found in 26% of luminal tumors (17% of luminal A, 41% of luminal B), in 50% of HER2 amplified tumors, in 69% of molecular apocrine breast carcinomas and in 88% of basal-like carcinomas. The type of mutation is linked to the tumor subtype with higher frequency of base-pair substitutions in luminal tumors, whereas molecular apocrine and basal-like tumors present much higher frequency of complex mutations (deletions/insertions). The timing of TP53 mutation also depends on the tumor subtype, being the first important event in luminal tumors but occurring after PTEN loss in basal-like tumors.Regarding response to cytotoxic chemotherapy, the situation is far from the p53-dependent apoptosis paradigm with subsequent clinical response. We reported that TP53 mutated non inflammatory locally advanced breast carcinomas had a high rate of complete pathological response to dose-dense doxorubicin–cyclophosphamide chemotherapy, while TP53 wild-type (WT) tumors never achieved complete response. Using human breast cancer xenograft models, we suggested that this could be due to the induction of senescence in TP53 WT tumor cells. A recent work confirmed these findings in MMTV-Wnt1 mammary tumors, showing that growth arrest and senescent phenotype, not apoptosis, were induced in TP53 WT tumors following doxorubicin treatment, while lack of arrest in mutant tumors resulted in aberrant mitoses, cell death and a superior clinical response. Furthermore, in ER positive (ER(+)) breast tumors, it has been recently reported that ER represses the p53-mediated apoptotic response induced by DNA damage. Taken together, these data can help to better understand p53-mediated response to doxorubicin-based chemotherapy in breast cancer: in ER(+) TP53 WT breast cancers, ER-induced inhibition of p53 apoptotic response would lead preferentially to tumor cell senescence and subsequent resistance to treatment. Conversely, in ER negative (ER(−)) TP53 mutated breast cancers, accumulation of genetic abnormalities would lead to mitotic catastrophe and subsequent better response.In view of these recent results, p53 impact in breast cancer should be reconsidered.

Homeodomain-interacting Protein Kinase 1 (HIPK1) Expression in Breast Cancer Tissues

This study investigated the incidence and clinical significance of homeodomain-interacting protein kinase 1 expression in breast cancer patients. We investigated immunohistochemical homeodomain-interacting protein kinase 1 expression from tissue microarrays of 1032 patients. The association of homeodomain-interacting protein kinase 1 expression pattern, clinicopathologic factors and survival outcome was evaluated. Tumors with ≥10% stained cells were considered positive for homeodomain-interacting protein kinase 1. Non-cancerous breast tissue, pTis and pT1mic lesions did not show homeodomain-interacting protein kinase 1 expression at any sites. Of the 859 invasive tumors, 124 (14.4%) showed homeodomain-interacting protein kinase 1 expression with three different expression patterns: cytoplasmic (2.4%), nuclear (6.3%), and both cytoplasmic and nuclear (5.7%). Cytoplasmic homeodomain-interacting protein kinase 1-positive tumors showed distinctive features such as fewer nodal metastases, but were frequently Grade III, estrogen receptor-negative, progesterone receptor-negative, HER2-positive, highly proliferative and molecular apocrine tumors. No significant difference in clinicopathologic features was identified between negative and nuclear homeodomain-interacting protein kinase 1-positive tumors. Both cytoplasmic and nuclear HIPK1-positive tumors represent frequent small size, node negativity and moderately differentiated features. Survival was not significantly different by homeodomain-interacting protein kinase 1 expression patterns. Homeodomain-interacting protein kinase 1 expression was identified only in invasive breast cancer cells with three different patterns: cytoplasmic, nuclear, and both cytoplasmic and nuclear. Although the mechanism is not certain, the subcellular localization of HIPK1 expression is associated with tumor histopathologic characteristics and different functions.

Distinct tumor protein p53 mutants in breast cancer subgroups

Tumor protein p53 (TP53) is mutated in approximately 30% of breast cancers, but this frequency fluctuates widely between subclasses. We investigated the p53 mutation status in 572 breast tumors, classified into luminal, basal and molecular apocrine subgroups. As expected, the lowest mutation frequency was observed in luminal (26%), and the highest in basal (88%) tumors. Luminal tumors showed significantly higher frequency of substitutions (82 vs. 65%), notably A/T to G/C transitions (31 vs. 15%), whereas molecular apocrine and basal tumors presented much higher frequencies of complex mutations (deletions/insertions) (36 and 33%, respectively, vs. 18%). Accordingly, missense mutations were significantly more frequent in luminal tumors (75 vs. 54%), whereas basal tumors displayed significantly increased rates of TP53 truncations (43 vs. 25%), resulting in loss of function and/or expression. Interestingly, as basal tumors, molecular apocrine tumors presented with a high rate of complex mutations, but paradoxically, these were not associated with increased frequency of p53 truncation. As in luminal tumors, this could reflect a selective pressure for p53 gain of function, possibly through P63/P73 inactivation. Collectively, these observations point not only to different mechanisms of TP53 alterations, but also to different functional consequences in the different breast cancer subtypes.

Abstract 2922: Androgen receptor driven transcription in a subtype of estrogen receptor negative breast cancer is controlled by FoxA1

Abstract Breast cancer is a heterogeneous disease and several distinct subtypes exist based on differential gene expression patterns. Molecular apocrine tumors were recently identified as an additional subgroup, characterised as ERα- AR+, but with an expression profile that resembles ERα+ luminal breast cancer. Previously, we mapped global AR binding events in a cell line model of molecular apocrine breast cancer (termed MDA-MB-453 cells) using ChIP-seq. Our results suggested that these tumours are driven by AR through its interaction with critical ER cis-regulatory elements, resulting in a transcriptional programme reminiscent of ER-mediated transcription in luminal breast cancers. Additionally, we found that AR binding is a near-perfect subset of FoxA1 binding regions, a level of concordance never previously seen with a Nuclear Receptor. By silencing FoxA1 using specific siRNA, we observe dramatic changes in the gene expression profile of the cells (730 genes are differentially expressed) including many of the signature molecular apocrine genes. Furthermore, silencing of FoxA1 in these breast cancer cells results in altered AR binding to the chromatin (lost, conserved and de novo binding events are found) as has been previously seen in the prostate cancer cell line, LNCaP. We are investigating this phenomenon further using proteomics to discover new AR interacting proteins and histone mark ChIP-seq to understand the proteins and epigenetic events that may mediate the reprogrammed AR binding in the absence of FoxA1. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2922. doi:1538-7445.AM2012-2922

P3-05-01: Gene Profiling of Histopathologically Characterized Apocrine Breast Cancers.

Abstract Background Breast cancer is currently classified in 3 groups based on estrogen receptor alpha (ER) and human epidermal growth factor receptor 2 (HER2/ERBB2) gene expression: one basal-like (ER-ERBB2-), one HER2−enriched (ERBB2+) and one luminal (ER+). Yet, in transcriptome-based classifications, ER-ERBB2+ group partially overlaps with more recently defined ER-AR+ (androgen receptor positive) group. This type was named molecular apocrine, in reference to the histopathologically characterized apocrine carcinomas (H-Apo), in which a marked activation of AR signaling was demonstrated with a distinct proteomic signature. H-Apo tumors correspond to 1% of invasive breast carcinomas and are clearly morphological distinct from other AR+ tumors. However, no specific H-Apo transcriptome signature has been reported for this sub-group. In an effort to better characterize those tumors, we have performed a meta-analysis of genomic data, focusing on the ER- AR+ breast subset. Samples and Methods: Chips were from Affymetrix array generations HG-U133. 258 profiles were unpublished and 1145 were from published or in press data. Gene expression was carried out after GC-RMA normalization. Unsupervised hierarchical clustering and other statistical analysis were performed with R software. Results: 160 of the 1403 investigated tumors were ER-AR+. An unsupervised hierarchical clustering clearly identified a small subgroup of 14 closely tumors expressing high transcripts levels of PIP, HPGD, ACSM1, AR, SDR5A1, HS3DB1. This profile was very similar to the proteomic signature previously described for the H-Apo tumors. In addition, the pathology report, although available only for 4 of those14 tumors, described them as typical apocrine carcinomas. Taken together, these data suggested that this cluster was the H-Apo subgroup. Unexpectedly, when using the transcriptomic PAM50 classification, 13 were classified as Luminal and only 1 as HER2−enriched, although the 14 tumors were all ER-negative. CGH analysis with Agilent 244K chips was carried out with 25 ER- AR+ tumors, of which 5 were H-Apo carcinomas. Importantly, those 5 H-Apo tumors exhibited fewer DNA lesions than the other ER-AR+ apocrine tumors (17% copy number alterations in H-Apo group versus 41%, p=0.02). More CGH data are currently under investigations and will be discussed. Discussion: The histopathologically characterized apocrine carcinomas (H-Apo) display transcriptomic signs of active androgen metabolism and fewer DNA lesions than others molecular apocrine tumors. This could suggest that molecular apocrine and H-apocrine tumor derive from the same cell of origin, but that only H-Apo retains morphological apocrine features, possibly due to the presence of fewer genetic lesions. In any case, the prominent androgen signaling activation warrants functional assays of anti-androgen in these breast cancer subtypes. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-05-01.

P2-02-09: TP53 Mutation Patterns in Breast Cancer Subgroups.

Abstract Tumor protein 53 (TP53) is the most commonly altered gene in human cancers. In breast cancers, TP53 is mutated in approximately 30% of all cases, but this frequency fluctuates widely within the different molecular subclasses. Different types of mutations may be observed, such as substitutions (replacement of a nucleotide pair by another one), or complex mutations (deletions or insertions of one or more nucleotides). Mutation types may reflect mechanism of DNA lesion or DNA repair deficiencies. Furthermore, mutations can give rise to different effects such as truncating mutations leading to loss of function, or missense mutations often leading to dominant negative activity. Those mutation effects can be advantageous in tumorigenesis and thus can be subject to selective pressure. Here we classified 572 breast tumors in three groups, according to microarray data: luminal, basal and molecular apocrine. TP53 status was assessed by a yeast-based functional assay (FASAY) and cDNA sequencing. We then assessed whether any feature of TP53 mutations would be preferentially associated to a specific subtype of breast cancer. - In term of TP53 mutation frequencies, as expected, lowest frequency was observed in luminal subgroup (26%) and highest in basal (90%) and molecular apocrine (70%). Notably, much higher rate of TP53 mutations occurred in luminal B subgroup (41%) than in luminal A one (17%), suggesting that TP53 may be an important feature in progression from luminal A to B. - In term of mutations types, luminal tumors showed high frequency of substitutions, while molecular apocrine and basal presented increased rate of deletions and insertions, reflecting probably increased rate of DNA breaks. This suggests that same mutational events may occur in basal and molecular apocrine tumors. - In term of mutation effects, we found high frequency of missense mutations in luminal tumors (notably AT to GC) and much higher rate of truncating mutations in basal tumors. These observations point to an existence of different selection pressure in each of them, such as a strong pressure for P53 mutations with potential dominant negative inhibition of P73/P63 (recently shown to favor invasion), in luminal tumors. Collectively, these results point not only to different mechanisms of P53 gene inactivation, but also different functional consequences among the different breast cancer subclasses. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-02-09.

New insights into the role of androgen and oestrogen receptors in molecular apocrine breast tumours

Two recent studies on a rare androgen-dependent form of breast cancer have shed light on the biology of luminal tumours and reinforced the view that interfering with androgen signalling may have a place in the therapy of some forms of breast cancer.

Androgen receptor expression is significantly associated with better outcomes in estrogen receptor-positive breast cancers

BackgroundThe objective of the study was to evaluate the implications of androgen receptor (AR) in breast cancers. Patients and methodsWe investigated immunohistochemical AR expression from the tissue microarrays of 931 patients between 1999 and 2005, and analyzed demographics and outcomes using uni-/multivariate analyses. Tumors with ≥10% nuclear-stained cells were considered positive for AR. ResultsAR was expressed in 58.1% of patients. AR was significantly related to older age at diagnosis, smaller size, well-differentiated tumors, higher positivity of hormone receptors, non-triple-negative breast cancers (non-TNBCs), and lower proliferative index. In estrogen receptor (ER)-negative tumors, AR was distinctively associated with human epidermal growth factor receptor type 2 (HER2) overexpression. With a mean follow-up of 72.7 months, AR was positively related to survival in ER-positive but not in ER-negative tumors. In Cox’s models, AR was an independent prognostic factor for disease-free survival in ER-positive cancers. Interestingly, molecular apocrine tumors (ER negative and AR positive) with HER2 positive status showed trends of poorer outcome, but AR had no impact on survival in patients with TNBC. ConclusionsAR is significantly associated with favorable features in breast cancers and related to better outcomes in ER-positive not in ER-negative tumors. These results suggest that AR could be an additional marker for endocrine responsiveness in ER-positive cancers and a candidate for therapeutic targeting of ER-negative tumors.

Targeting Androgen Receptor in Estrogen Receptor-Negative Breast Cancer

Endocrine therapies for breast cancer that target the estrogen receptor (ER) are ineffective in the 25%-30% of cases that are ER negative (ER-). Androgen receptor (AR) is expressed in 60%-70% of breast tumors, independent of ER status. How androgens and AR regulate breast cancer growth remains largely unknown. We find that AR is enriched in ER- breast tumors that overexpress HER2. Through analysis of the AR cistrome and androgen-regulated gene expression in ER-/HER2+ breast cancers we find that AR mediates ligand-dependent activation of Wnt and HER2 signaling pathways through direct transcriptional induction of WNT7B and HER3. Specific targeting of AR, Wnt or HER2 signaling impairs androgen-stimulated tumor cell growth suggesting potential therapeutic approaches for ER-/HER2+ breast cancers.

Androgen receptor driven transcription in molecular apocrine breast cancer is mediated by FoxA1

Breast cancer is a heterogeneous disease and several distinct subtypes exist based on differential gene expression patterns. Molecular apocrine tumours were recently identified as an additional subgroup, characterised as oestrogen receptor negative and androgen receptor positive (ER- AR+), but with an expression profile resembling ER+ luminal breast cancer. One possible explanation for the apparent incongruity is that ER gene expression programmes could be recapitulated by AR. Using a cell line model of ER- AR+ molecular apocrine tumours (termed MDA-MB-453 cells), we map global AR binding events and find a binding profile that is similar to ER binding in breast cancer cells. We find that AR binding is a near-perfect subset of FoxA1 binding regions, a level of concordance never previously seen with a nuclear receptor. AR functionality is dependent on FoxA1, since silencing of FoxA1 inhibits AR binding, expression of the majority of the molecular apocrine gene signature and growth cell growth. These findings show that AR binds and regulates ER cis-regulatory elements in molecular apocrine tumours, resulting in a transcriptional programme reminiscent of ER-mediated transcription in luminal breast cancers.

Abstract P3-10-03: The Implication of Androgen Receptor Expression in Breast Cancers

Abstract Purpose: To evaluate the implication of androgen receptor (AR) expression in patients with breast cancer. Methods: Immunohistochemically AR expression was investigated in 931 invasive breast cancers prepared in tissue microarray blocks that were collected in between November 1999 and August 2005. The clinicopathological features, disease-free (DFS) and overall survival (OS) were analyzed using chi-square test, Kaplan-Meier methods, and Cox's models. Tumors with ≥10% nuclear-stained cells were considered to be positive for AR, estrogen receptor (ER), and progesterone receptor (PR) expression and 3+ with immunohistochemical staing or FISH + were considered positive for HER2 expression. Results: The positive expression of AR, ER, PR, and HER2 was 58.1%, 72.2%, 61.4%, and 24.7% of all patients, respectively. AR expression was significantly associated with an older age at diagnosis (p=0.007), smaller tumor size (P<0.001), well differentiation (P<0.001), higher hormone receptors expression (P<0.001), non-triple-negative breast cancers (non-TNBC) (P<0.001), and lower proliferation index (P<0.001). In ER-negative cancers, AR expression was associated with well differentiation, lower Ki-67 index, and distinctively HER2 overexpression. With median follow-up duration of 72.7 months, AR was significantly associated with better DFS (p=0.023) and OS (p=0.048) and the association was same in ER-positive cancers but was disappeared in ER-negative cancers. In Cox's models, AR expression was an independent prognostic factor for DFS (hazard ratio, 0.654; p=0.049), but it did not reach a statistical significance for OS (hazard ratio, 0.647; p=0.119) even in ER-positive tumors. Interestingly, tumors with molecular apocrine features (ER-negative, AR-positive, and HER2-positive) showed a trend of poorer outcome with AR expression, but there was no impact of AR expression on the survival in 156 patients with TNBC. Conclusions: AR expression is significantly associated with favorable clinicopathological features and better outcomes in ER-positive cancers but tumors with molecular apocrine features showed a trend of poorer outcome with AR expression. These results suggest that AR expression could be an additional marker for endocrine responsiveness in ER-positive tumors and a target molecule for the molecular apocrine tumors. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-03.