Breast cancer molecular class ERBB2: preponderance of tumors with apocrine differentiation and expression of basal phenotype markers CK5, CK5/6, and EGFR

Relationship of Tubule Formation, Indian File Pattern and Apocrine Change With Estrogen and Progesterone Receptors and HER2 Immunostaining

Objectives: In breast carcinomas, histomorphological features like low-grade and lobular differentiation are associated with estrogen receptor (ER) and progesterone receptor (PR) expression. Apocrine carcinoma is associated with human epidermal growth factor receptor 2 (HER2) positivity. Studies have not emphasized the association between other histological features like tubule formation, Indian file pattern and apocrine change (which may be found in all grades of tumors or as a part of a mixed pattern of no special type) and immunohistochemistry (IHC). The study was designed to find the association between these morphological factors and ER, PR and HER2 status.

Materials and methods: The presence or absence of tubule formation, Indian file pattern and apocrine change was correlated with ER, PR and HER2 expression in core biopsies of 102 invasive breast carcinomas.

Statistical analysis: Fisher exact test with median unbiased odds ratio was used.

Results: Tubule formation and/or Indian file pattern were significantly associated with ER in all tumors (P-value <0.001), as well as separately for grade II, grade III, HER2-negative and HER2-positive tumors. Comparable results were obtained for their association with PR. Apocrine change was significantly associated with HER2 in all tumors (P-value <0.001), as well as separately for grade III, ER-positive and ER-negative tumors.

Conclusion: These histomorphological patterns are modest predictors of IHC status in breast carcinomas, even in tumors of higher grade. Knowledge of these morphological correlates of ER, PR and HER2 in breast cancer may serve as an aid in the quality management of breast carcinoma reporting.

Histopathologic features of breast cancer in Li-Fraumeni syndrome

Breast cancer is the most common malignancy in female patients with Li-Fraumeni syndrome (LFS), a rare autosomal dominant hereditary syndrome characterized by germline TP53 mutations. Recent studies have shown that the majority of these tumors are estrogen receptor (ER) positive with frequent HER2 co-expression. However, the morphologic features of these tumors have not been as well studied as other germline-associated breast cancers. We evaluated the pathologic features of 27 invasive and in situ carcinomas from patients with known germline TP53 mutations collected through the Li-Fraumeni Consortium. Overall, 60% of cases were HER2 positive and 44% showed ER co-expression. Most DCIS was high nuclear grade with central necrosis and associated periductal fibrosis and lymphocytic response. Invasive carcinomas were mostly of ductal type (NOS), modified Scarff-Bloom-Richardson (mSBR) high grade, with marked nuclear atypia and high mitotic rate. Prominent tumor infiltrating lymphocytes, syncytial growth pattern, or pushing borders were not seen in these tumors. High p53 IHC expression was seen in tumors from individuals with germline TP53 missense mutations whereas little or no protein expression (<1% nuclear expression, null pattern) was seen in tumors from carriers of non-missense mutations. In this study, we report in detail the morphologic features of invasive and in situ carcinomas in LFS. We found that these tumors share features with cancers harboring somatic TP53 mutations but are distinct from BRCA-associated breast cancers.

Androgen receptor expression is useful to predict the therapeutic effect in HER2-positive breast carcinoma

PURPOSE

Although HER2-positive (HER2+) invasive breast carcinomas (BC) have a different clinical therapeutic responsiveness according to estrogen and progesterone receptor expression, the relationship with androgen receptors (AR), which are the same family of steroid hormones, is poorly understood. We investigated the relationship between AR expression in HER2 BCs and therapeutic responsiveness and prognosis in this study.

METHODS

We evaluated patients with HER2 (H) + invasive BC undergoing surgery after neoadjuvant chemotherapy (± HER2-targeted therapies) from 2007-2017, classified as hormone receptor-positive (Allred score: 2-8) (luminal B: LH) and receptor-negative groups (Allred: score 0) (non-luminal: NLH). AR expression was assessed by immunostaining pre-neoadjuvant chemotherapy biopsy specimens, positive with Allred score ≥ 4. The pathological complete response, disease-free survival, and overall survival rates were compared between AR-positive and AR-negative groups.

RESULTS

We classified 82 patients with HER2 + invasive BC into LH (n = 45, 54.9%) and NLH groups (n = 37, 45.1%), and AR + was observed in 43 patients (52.4%) (LH: 23, 51.1%; NLH: 20, 54.1%; p = 0.79). Quasi-pathological complete response was observed in 40 patients (48.8%) (LH: 18, 40%; NLH: 22, 59.5%; p = 0.08) overall, and in 31 AR + patients (72.1%) (LH: 15, 34.9%; NLH: 16, 37.2%), significantly higher than in the AR - group for both subgroups (p < 0.001). Regarding prognosis, disease-free survival was relatively better in the AR + group in all HER2 + BCs (p = 0.085), and overall survival was significantly better in the AR + group for NLH (p = 0.029).

CONCLUSIONS

High AR expression may be a useful predictor of therapeutic effects and prognosis in both subgroups of HER2 + BCs.

Genomic profiling of pleomorphic and florid lobular carcinoma in situ reveals highly recurrent ERBB2 and ERRB3 alterations

Pleomorphic LCIS (P-LCIS) and florid LCIS (F-LCIS) are morphologic variants distinguished from classic LCIS by marked nuclear pleomorphism and/or an expansile growth pattern with or without necrosis. Given the rarity of these LCIS variants, little data exist regarding their molecular pathogenesis, natural history, and optimal management. The purpose of this study was to genomically profile LCIS variants to gain further insight into their biology. Nineteen cases of pure LCIS variants (17 P-LCIS, 2 F-LCIS) diagnosed on core needle biopsy at our institution from 2006 to 2017 were included, five of which were upgraded to invasive cancer at excision. Macrodissected lesions were analyzed by a hybrid-capture next generation sequencing assay that surveyed exonic sequences of 447 genes for mutations and copy number variations (CNVs) and 191 regions across 60 genes for structural rearrangements. LCIS variants were all confirmed as E-cadherin negative by immunohistochemistry. Receptor profiles among the 17 P-LCIS cases included HR+/HER2- (nine cases), HR+/HER2+ (three cases), HR-/HER2+ (two cases), and HR-/HER2- (three cases). The two F-LCIS cases were HR+/HER2- and HR+/HER2+. All LCIS variants had genetic alterations consistent with a lobular phenotype including 1q gain (16 cases), 16q loss (18 cases), and CDH1 mutations (18 cases). Highly recurrent ERBB2 alterations were noted including mutations (13 cases) and amplifications (six cases). Other significant alterations included mutations in PIK3CA (six cases), RUNX1 (four cases), ERBB3 (four cases), and CBFB (three cases), as well as amplification of CCND1 (five cases). A TP53 mutation was identified in one case of HR-/HER2+ P-LCIS with signet ring cell features that lacked 1q gain and 16q loss. P-LCIS and F-LCIS contain genetic alterations characteristic of lobular neoplasia; however, these LCIS variants are distinguished from classical LCIS reported in the literature by their highly recurrent ERBB2 alterations.

Noninvasive Papillary Basal-like Urothelial Carcinoma: A Subgroup of Urothelial Carcinomas With Immunohistochemical Features of Basal Urothelial Cells Associated With a High Rate of Recurrence and Progression

BACKGROUND

We investigated the clinical and pathologic significance of a subgroup of noninvasive papillary urothelial carcinomas (UCs) expressing reactivity to urothelial basal cell markers.

DESIGN

In total, 302 consecutive cases of noninvasive papillary UC were evaluated immunohistochemically with cytokeratin 5 (CK5)/CD44. Any UC that was reactive for greater than 25% thickness of the urothelium was designated as basal-like urothelial carcinoma (BUC); remaining UC cases were designated as non-BUC. The follow-up period was up to 3 years. Historical review of UC was extended for up to 3 retrospective years.

RESULTS

Among 302 noninvasive UC, BUC was identified in 33 of 256 (12.9%) low-grade UC and 8 of 46 (17%) high-grade UC (P=0.041). Immunoreactivity for CD44 was similar to that of CK5, but displayed weaker and more diffuse staining. CK20 was reactive in 9 cases, primarily high-grade BUC. Other basal cell markers (34bE12, p63, bcl2, and EP4) were found to be neither sensitive nor specific in detecting UC with high CK5 expression. In comparison with non-BUC, BUC was associated with increased multifocality, larger tumor size, higher recurrence rate, and more frequent upgrading and stage progression. In the follow-up period of 3 years, distant metastasis occurred in 6 cases of which 5 were in the BUC subgroup.

CONCLUSIONS

Our results showed that noninvasive papillary BUC represents a small subset associated with increased risk of tumor recurrence and progression. The aggressive behavior is likely associated with basal-like features of BUC, as seen in carcinomas with basal cell features in other body sites.

Expression of high affinity folate receptor in breast cancer brain metastasis

High affinity folate receptor (HFR) can be overexpressed in breast cancer and is associated with poor prognosis, however the expression in breast cancer brain metastases (BCBM) is unknown. The aim of this study was to analyze the rate of HFR expression in BCBM and its role in the prognosis of this high-risk cohort. We analyzed 19 brain metastasis (BM) and 13 primary tumors (PT) from a total of 25 patients. HFR status was assessed by immunohistochemistry. Median follow-up was 4.2 years (range 0.6-18.5). HFR was positive in 4/19 BM (21.1%) and in 1/13 PT (7.7%). Positive samples had low H-scores (range 1-50). 56% of patients had apocrine differentiation. OS was similar between patients with positive HFR (median OS 48 months) and negative HFR (median OS 69 months) (P = 0.25); and between patients with apocrine differentiation (median OS 63 months) and those without apocrine differentiation (median OS 69 months) (P = 0.49). To the best of our knowledge, this is the first analysis of HFR expression in BCBM. While previous studies associated the presence of HFR with worse prognosis; in our cohort HFR was positive in only 21.1% of BM with low levels of positivity. Neither HFR nor apocrine features had impact in OS.

Cytokeratin 5/6 fingerprinting in HER2-positive tumors identifies a poor prognosis and trastuzumab-resistant basal-HER2 subtype of breast cancer

There is an urgent need to refine the prognostic taxonomy of HER2+ breast carcinomas and develop easy-to-use, clinic-based prediction algorithms to distinguish between good- and poor-responders to trastuzumab-based therapy. Building on earlier studies suggesting that HER2+ tumors enriched with molecular and morpho-immunohistochemical features classically ascribed to basal-like tumors are highly aggressive and refractory to trastuzumab, we investigated the prognostic and predictive value of the basal-HER2+ phenotype in HER2-overexpressing tumors. Our retrospective cohort study of a consecutive series of 152 HER2+ primary invasive ductal breast carcinomas first confirmed the existence of a distinct subgroup co-expressing HER2 protein and basal cytokeratin markers CK5/6, the so-called basal-HER2+ phenotype. Basal-HER2+ phenotype (≥10% of cells showing positive CK5/6 staining), but not estrogen receptor status, was significantly associated with inferior overall survival by univariate analysis and predicted worsened disease free survival after accounting for strong prognostic variables such as tumor size at diagnosis in stepwise multivariate analysis. In the sub-cohort of HER2+ patients treated with trastuzumab-based adjuvant/neoadjuvant therapy, basal-HER2+ phenotype was found to be the sole independent prognostic marker for a significantly inferior time to treatment failure in multivariate analysis. A CK5/6-based immunohistochemical fingerprint may provide a simple, rapid, and accurate method for re-classifying women diagnosed with HER2+ breast cancer in a manner that can improve prognosis and therapeutic planning in patients with clinically aggressive basal-HER2+ tumors who are not likely to benefit from trastuzumab-based therapy.

Breast cancer subtypes: morphologic and biologic characterization

Advances in basic science, technology and translational research have created a revolution in breast cancer diagnosis and therapy. Researchers' discoveries of genes defining variability in response to therapy and heterogeneity in clinical presentations and tumor biology are the foundation of the path to personalized medicine. The success of personalized breast cancer care depends on access to pertinent clinical information and risk factors, optimal imaging findings, well-established morphologic features, and traditional and contemporary prognostic/predictive testing. The integration of these entities provides an opportunity to identify patients who can benefit from specific therapies, and demonstrates the link between breast cancer subtypes and their association with different tumor biology. It is critical to recognize specific types of breast cancer in individual patients and design optimal personalized therapy. This article will highlight the roles of morphologic features and established tumor biomarkers on patient outcome.

Invasive urothelial carcinoma exhibiting basal cell immunohistochemical markers: A variant of urothelial carcinoma associated with aggressive features

We characterize invasive urothelial carcinoma (UC) exhibiting urothelial basal cell immunohistochemical markers. Consecutive invasive UCs were immunostained with CK20 and urothelial basal cell markers, cytokeratin 5 (CK5)/CD44. Immunostaining for CK5 and CD44 was scored as follows: positive for staining of more than 25% thickness of the epithelial nest or epithelium and low for lesser immunoreactivity. Invasive urothelial carcinoma (UC) exhibiting positive CK5/CD44 staining was designated as basal-like UC (BUC). In this study, of 251 invasive UC (pT1 in 57% and pT2-4 in 43%), BUC accounted for 40% of cases (accounting for most pT2-4 UC) and often presented as non-papillary UC without previous history of UC. In addition, BUC exhibited uniform nuclei with lesser degree of atypia than non BUC and decreased or negative cytokeratin 20 reactivity. Nested and microcystic variants of UC immunohistochemically stained as BUCs. Invasive non-BUCs were often papillary with marked cytologic atypia and pleomorphism, and accounted for most pT1 UC. The rates of perivesical invasion, lymph node and distant metastases were higher for BUC than non-BUC. All nine cases with absent/minimal residual in situ UC in 102 radical cystectomy specimens were from invasive non-BUC. BUC is distinguished from non-BUC due to this aggressive behavior, distinct immunohistochemical profile, and predominant non-papillary architecture. Our findings are consistent with recent studies identifying a subtype of muscle-invasive UC with molecular expression of basal cell and luminal cell molecular profiles. Our study further supports categorizing invasive UCs into these subtypes with different biological behaviors, possibly contributing to better therapeutic strategies.

How to identify patients with increased risk of breast cancer relapse?

A cohort of 362 breast cancer patients had subtype classification accomplished using 4 immunohistochemical markers: luminal A (ER or PR positive, HER2 negative, Ki-67<14%), luminal B (ER or PR positive, HER2 negative, Ki-67≥14%), luminal HER2 (ER or PR positive, HER2 positive), HER2 enriched (ER or PR negative, HER2 positive) or triple negative (ER, PR, and HER2 negative). Multivariable Cox analysis was used to determine the risk of local (LR) or distant (DR) relapse associated with the intrinsic subtypes, adjusting for standard clinicopathologic factors. There have been a total of 124 recurrences. Triple-negative patients were associated with increased risk of LR. Luminal B subtype showed statistical tendency (P=0.053) to LR. For patients undergoing breast conservation surgery, luminal B and HER2-enriched subtypes demonstrated an increased risk to LR, and this was statistically significant on multivariable analysis. After mastectomy, there was no statistical difference between subtypes of LR or DR on multivariable analysis. Luminal A tumors are associated with a low risk of LR or DR. Despite the existence of gene expression profiling, in the current study we demonstrate that analysis of 4 immunohistochemical markers is equally effective and less expensive alternative to identify higher recurrence risk patients.

Site-specific metabolic phenotypes in metastatic breast cancer

Background

The purpose of this study was to examine the expression of metabolism-related proteins according to metastatic site in metastatic breast cancer and to assess the implication of site-specific differential expression.

Methods

A tissue microarray containing 162 cases of metastatic breast cancer (52 lung metastasis, 47 bone metastasis, 39 brain metastasis, and 24 liver metastasis) was constructed. It was subject to immunohistochemical staining of the following proteins: Glycolysis-related: Glut-1, hexolinase II, carbonic anhydrase (CA) IX, and monocarboxylate transporter (MCT) 4; glutaminolysis-related: glutaminase (GLS) 1, glutamate dehydrogenase (GDH), and amino acid transporter (ASCT) 2; mitochondrial metabolism-related: ATP synthase, succinate dehydrogenase (SDH)A, and SDHB; and serine/glycine metabolism related: phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase (PSAT), phosphoserine phosphatase (PSPH), glycine decarboxylase (GLDC), and serine hydroxymethyltransferase (SHMT).

Results

The expression levels of glycolysis-related-proteins (Glut-1, hexokinase II, CAIX, and MCT4) differed according to metastatic site, with higher expression seen in the brain and lower expression in the bone and liver (p < 0.001, 0.001, 0.009, and <0.001, respectively). Differences in metabolic phenotype were analyzed according to metastasis site. Glycolysis type was most frequently encountered in the brain and lung (p < 0.001). In univariate analysis, the factors associated with shorter overall survival were CAIX positivity (p = 0.044), PSPH positivity (p = 0.045), and SHMT1 positivity (p = 0.002), as well as serine/glycine type (p = 0.041).

Conclusions

Differences in metabolic features according to metastatic site were seen in metastatic breast cancer, with the glycolysis phenotype found predominantly in the brain and lung and the non-glycolysis phenotype in the bone and liver.

Metabolic differences in estrogen receptor-negative breast cancer based on androgen receptor status

This study investigated the relationship between steroid hormone receptor signaling and cellular metabolism in tumorigenesis by examining the expression of metabolic proteins with respect to androgen receptor (AR) and human epidermal growth factor receptor-2 (HER-2) status in estrogen receptor-negative (ER-) breast cancer. ER- breast cancer cases (n = 334) were selected from a microarray analysis, including those that were AR+ and AR- (n = 127 and 207, respectively) and HER-2+ and HER-2- (n = 140 and 194, respectively). The expression of proteins involved in glycolysis, glutaminolysis, and mitochondrial and intermediary (i.e., serine/glycine) metabolism was determined by immunohistochemistry and correlated with AR and HER-2 status. The expression of several proteins involved in glycolysis, glutaminolysis, and serine/glycine metabolism was higher (p < 0.01) in the AR- than in the AR+ group. In the former, the expression of the glycolytic protein carbonic anhydrase (CA)IX was associated with a shorter disease-free survival period (p = 0.029) and overall survival rate (p = 0.001). In a multivariate Cox analysis, immunoreactivity for CAIX (hazard ratio 15.89, 95 % confidence interval (CI) 1.820-131.6; p = 0.010) was an independent factor in predicting the survival of the AR+ group. In conclusion, differential expression patterns of metabolism-related proteins were noted in ER- breast cancer according to AR status. These findings highlight the link between hormone receptor signaling and metabolic pathways whose dysregulation could underlie breast tumorigenesis.

Two histopathologically different diseases: hormone receptor-positive and hormone receptor-negative tumors in HER2-positive breast cancer

The clinical behavior of human epidermal growth factor 2 (HER2)-positive breast cancer, including pathologic complete response rate and pattern of relapse and metastasis, differs substantially according to hormone receptor (HR) status. We investigated various histopathologic features of HER2-positive breast cancer and their correlation with HR status. We retrospectively analyzed tumors of 450 HER2-positive breast cancer patients treated with chemotherapy and 1 year of trastuzumab. HR-/HER2+ tumors showed higher nuclear grade, less tubule formation, higher histologic grade, frequent apocrine features, diffuse and abundant lymphocytic infiltration, strong HER2 immunohistochemical staining (3+), higher average HER2 copy number and HER2/CEP17 ratio, the absence of HER2 genetic heterogeneity, and greater p53 expression than HR+/HER2+ tumors. An inverse correlation was observed between estrogen receptor or progesterone receptor Allred score and average HER2 copy number or HER2/CEP17 ratio. The percentage of ductal carcinoma in situ (DCIS) within the tumor was negatively correlated with ER Allred score, but positively correlated with average HER2 copy number and HER2/CEP17 ratio. Pathologic tumor size and DCIS percentage also showed a significant inverse correlation. Ratio of metastatic to total examined lymph node number was significantly correlated with average HER2 copy number and HER2/CEP17 ratio. High pT stage (hazard ratio, 2.370; p = 0.027), the presence of lymphovascular invasion (hazard ratio, 2.806; p = 0.005), and HR negativity (hazard ratio, 2.202; 1.074-4.513; p = 0.031) were found to be independent prognostic indicators of poor disease-free survival. In conclusion, HR+/HER2+ and HR-/HER2+ breast cancer showed distinct histopathologic features that may be relevant to their distinct clinical behavior.

The androgen receptor as a surrogate marker for molecular apocrine breast cancer subtyping

The Androgen Receptor (AR) is a potential prognostic marker and therapeutic target in breast cancer. We evaluated AR protein expression in high-risk breast cancer treated in the adjuvant setting. Tumors were subtyped into luminal (ER+/PgR±/AR±), molecular apocrine (MAC, [ER-/PgR-/AR+]) and hormone receptor negative carcinomas (HR-negative, [ER-/PgR-/AR-]). Subtyping was evaluated with respect to prognosis and to taxane therapy. High histologic grade (p < 0.001) and increased proliferation (p = 0.001) more often appeared in MAC and HR-negative than in luminal tumors. Patients with MAC had outcome comparable to the luminal group, while patients with HR-negative disease had increased risk for relapse and death. MAC outcome was favorable upon taxane-containing treatment; this remained significant upon multivariate analysis for overall survival (HR 0.31, 95%CI 0.13-0.74, interaction p = 0.035) and as a trend for time to relapse (p = 0.15). In conclusion, AR-related subtyping of breast cancer may be prognostic and serve for selecting optimal treatment combinations.

Cutaneous and mammary apocrine carcinomas have different immunoprofiles

Often the distinction of cutaneous apocrine carcinoma from metastatic mammary apocrine carcinoma to the skin can be a diagnostic dilemma because both tumors share similar histologic features and have overlapping immunohistochemical profile. We compared the expression of adipophilin, cytokeratin 5/6, p63, GATA3, mammaglobin, androgen receptor, estrogen receptor, progesterone receptor, and HER2 by immunohistochemistry in 14 cutaneous apocrine carcinomas (11 primary tumors, 3 metastases) and 26 primary apocrine carcinomas of the breast. Whereas focal adipophilin staining was seen in 36% (5/14) of cutaneous apocrine carcinoma, strong and diffuse adipophilin staining was seen in 88% (22/25) of mammary apocrine carcinoma (P = .0013). Differences in estrogen receptor and progesterone receptor expression were also statistically significant (P = .018 and .043). Androgen receptor was strongly positive in all cutaneous and mammary cases. Although there was no significant difference in the frequency of expression of cytokeratin 5/6, p63, HER2, GATA3, and mammaglobin in cutaneous apocrine carcinoma versus mammary apocrine carcinoma, strong and diffuse cytokeratin 5/6 and/or mammaglobin expression were seen only in cutaneous apocrine carcinoma. In conclusion, cutaneous apocrine carcinoma is likely adipophilin- ER+ PR+/- HER2- and can exhibit strong and diffuse cytokeratin 5/6 and/or mammaglobin expression. On the contrary, a mammary apocrine carcinoma is likely adipophilin+ ER- PR- and often exhibit 3+ HER2 with corresponding HER2 gene amplification. A panel of adipophilin, ER, PR, HER2, cytokeratin 5/6, and mammaglobin may be helpful in distinguishing cutaneous apocrine carcinoma from mammary apocrine carcinoma.

The clinicopathologic features of molecular apocrine breast cancer

BACKGROUND

To elucidate the clinicopathologic features and their implications on the immunohistochemistry in cases of molecular apocrine breast cancer (MABC).

METHODS

Immunohistochemical (IHC) staining for estrogen receptor (ER), human epidermal growth factor receptor 2 (HER-2), cytokeratin (CK) 5/6, epidermal growth factor receptor (EGFR), androgen receptor (AR), gamma-glutamyltrasferase 1 (GGT1) and Ki-67 was performed on tissue microarray breast cancer samples from 204 patients. Phenotypes of breast cancer were divided based on the IHC status of ER, AR and GGT1 into the following: luminal type, ER positive and AR and/or GGT1 positive; basal type, ER, AR, and GGT1 negative; non-basal type, ER positive and AR and GGT1 negative; and MABC type, ER negative and AR and/or GGT1 positive.

RESULTS

In our series of patients (n=204), there were 26 cases of MABC. Besides, there were 18, 60, and 100 cases of luminal type, basal type and non-basal type, respectively. The MABC demonstrated apocrine histology and a higher prevalence of HER-2 positivity than other phenotypes. With the basal type, the MABC manifested a more frequent expression of CK5/6 and EGFR and a higher Ki-67 index than other phenotypes (p<0.001). There were no significant differences in patient prognosis between the phenotypes of breast cancer.

CONCLUSIONS

MABC are distinguishable from other phenotypes based on the apocrine histology and a higher expression rate of HER-2.

Update on the molecular profile of the MDA-MB-453 cell line as a model for apocrine breast carcinoma studies

Apocrine carcinoma of the breast has recently been refined through gene expression profiling. Due to various pathological studies, we compared the results with the MDA-MB-453 breast cancer cell line, a proposed model for apocrine breast carcinoma. The MDA-MB-453 cell line is androgen receptor-positive and `triple-negative' in respect to estrogen receptor-α, progesterone receptor and the Her-2/neu protein expression. Cytogenetic analysis of the cell line revealed a hypertriploid clone characterized by extensive numerical and structural abnormalities including loss of the 9p.21 locus (P16-INK4a gene), also evidenced by the lack of p16(INK4A) protein expression in Western blot analysis and immunocytochemistry assays. Gains of chromosomes 7 and 17 without underlying EGFR, HER-2/neu, and TOP2A gene amplification were also observed. A mutation in the K-RAS gene (Gly13Asp GGC>GAC) was identified in the cell line, which was not observed in the six patient samples of apocrine breast carcinomas examined. Similarly, constitutive activation of the MAPK/ERK signaling pathway and deregulation of cell cycle proteins (p16-/pRb-/cyclin D1+ phenotype) with exceedingly high proliferation observed in the MDA-MB-453 cell line were not found in the tissue samples. In conclusion, the MDA-MB-453 cell line shares certain features with apocrine breast carcinoma but differs from patient tissues with regard to various significant characteristics, limiting the value of this cell line as a model for human apocrine breast carcinoma investigations. In contrast to the cell line, EGFR-positive apocrine carcinomas do not harbor K-RAS gene mutations, rendering these tumors amenable to targeted therapy with EGFR inhibitors.

Classical-type invasive lobular carcinoma with HER2 overexpression: clinical, histologic, and hormone receptor characteristics

The majority of invasive lobular carcinomas (ILCs) express estrogen receptor (ER) and progesterone receptor (PR) but lack ERBB2 (HER2) amplification. HER2 overexpression is traditionally considered to occur in the pleomorphic variant of ILCs. We describe 12 cases of classical-type ILCs with HER2 overexpression in a 3-year period. All tumors displayed the characteristic morphologic features of classical ILC with uniform cells and discohesive growth patterns. The lobular phenotype was confirmed by the absence of E-cadherin staining. Multiple variables regarding clinical, histologic, and hormone receptor characteristics of tumors were evaluated and compared with a set of HER2- classical ILCs. The study identified 2 main pathologic features associated with HER2 overexpression in classical type ILC: histiocytoid morphologic features and absence of PR expression. ER is still expressed in HER2+ classical ILCs, although the level of expression is significantly reduced compared with the HER2- cases. The implications of the findings are discussed.

Relationship between molecular subtype of invasive breast carcinoma and expression of gross cystic disease fluid protein 15 and mammaglobin

We investigated the expression of gross cystic disease fluid protein 15 (GCDFP) and mammaglobin (MGB) by immunohistochemical analysis in 71 invasive breast carcinomas (IBCs) subtyped into luminal (A and B), HER2, basal-like carcinoma (BLC), and unclassified triple-negative carcinoma (UTNC) by established surrogate immunohistochemical profiles. GCDFP and MGB were less likely to be expressed in BLC than in HER2 cancers (P = .000021 and P = .013, respectively) or luminal cancers (P = .00002 and P = .00008, respectively). However, the difference in GCDFP or MGB expression between HER2 and luminal cancers was not significant (P = 1.0 and P = .671, respectively). Our results suggest that luminal cancers demonstrate similar degrees of apocrine differentiation as HER2 cancers. Most BLCs and UTNCs are negative for MGB and GCDFP. Correlation with clinical findings may be needed to exclude the possibility of a metastasis to the breast when BLCs or UTNCs are encountered in a limited sample such as a core biopsy sample.

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

BACKGROUND

The objective of the study was to evaluate the implications of androgen receptor (AR) in breast cancers.

PATIENTS AND METHODS

We 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.

RESULTS

AR 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.

CONCLUSIONS

AR 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.