Myoepithelial cells and basal lamina in poorly differentiated in situ duct carcinoma of the breast. An immunocytochemical study

Cancer Cell Invasion of Mammary Organoids with Basal-In Phenotype

This paper describes mammary organoids with a basal-in phenotype where the basement membrane is located on the interior surface of the organoid. A key materials consideration to induce this basal-in phenotype is the use of a minimal gel scaffold that the epithelial cells self-assemble around and encapsulate. When MDA-MB-231 breast cancer cells are co-cultured with epithelial cells from day 0 under these conditions, cells self-organize into patterns with distinct cancer cell populations both inside and at the periphery of the epithelial organoid. In another type of experiment, the robust formation of the basement membrane on the epithelial organoid interior enables convenient studies of MDA-MB-231 invasion in a tumor progression-relevant direction relative to epithelial cell-basement membrane positioning. That is, the study of cancer invasion through the epithelium first, followed by the basement membrane to the basal side, is realized in an experimentally convenient manner where the cancer cells are simply seeded on the outside of preformed organoids, and their invasion into the organoid is monitored. Interestingly, invasion is more prominent when tumor cells are added to day 7 organoids with less developed basement membranes compared to day 16 organoids with more defined ones.

Is it ductal carcinoma in situ with microinvasion or "Ductogenesis"? The role of myoepithelial cell markers

Mammary myoepithelial cells have been under-recognized for many years since they were considered less important in breast cancer tumorigenesis compared to luminal epithelial cells. However, in recent years with advances in genomics, cell biology, and research in breast cancer microenvironment, more emphasis has been placed on better understanding of the role that myoepithelial cells play in breast cancer progression. As the result, it has been recognized that the presence or absence of myoepithelial cells play a critical role in the assessment of tumor invasion in diagnostic breast pathology. In addition, advances in screening mammography and breast imaging has resulted in increased detection of ductal carcinoma in situ and consequently more diagnosis of ductal carcinoma in situ with microinvasion. In the present review, we discuss the characteristics of myoepithelial cells, their genomic markers and their role in the accurate diagnosis of ductal carcinoma in situ with microinvasion. We also share our experience with reporting of various morphologic features of ductal carcinoma in situ that may mimic microinvasion and introduce the term of ductogenesis.

Untapped "-omics": the microbial metagenome, estrobolome, and their influence on the development of breast cancer and response to treatment

With the advent of next generation sequencing technologies, there is an increasingly complex understanding of the role of gastrointestinal and local breast microbial dysbiosis in breast cancer. In this review, we summarize the current understanding of the microbiome's role in breast carcinogenesis, discussing modifiable risk factors that may affect breast cancer risk by inducing dysbiosis as well as recent sequencing data illustrating breast cancer subtype-specific differences in local breast tissue microbiota. We outline how the 'estrobolome,' the aggregate of estrogen-metabolizing enteric bacterial genes, may affect the risk of developing postmenopausal estrogen receptor-positive breast cancer. We also discuss the microbiome's potent capacity for anticancer therapy activation and deactivation, an important attribute of the gastrointestinal microbiome that has yet to be harnessed clinically.

Perturbed myoepithelial cell differentiation in BRCA mutation carriers and in ductal carcinoma in situ

Myoepithelial cells play key roles in normal mammary gland development and in limiting pre-invasive to invasive breast tumor progression, yet their differentiation and perturbation in ductal carcinoma in situ (DCIS) are poorly understood. Here, we investigated myoepithelial cells in normal breast tissues of BRCA1 and BRCA2 germline mutation carriers and in non-carrier controls, and in sporadic DCIS. We found that in the normal breast of non-carriers, myoepithelial cells frequently co-express the p63 and TCF7 transcription factors and that p63 and TCF7 show overlapping chromatin peaks associated with differentiated myoepithelium-specific genes. In contrast, in normal breast tissues of BRCA1 mutation carriers the frequency of p63⁺TCF7⁺ myoepithelial cells is significantly decreased and p63 and TCF7 chromatin peaks do not overlap. These myoepithelial perturbations in normal breast tissues of BRCA1 germline mutation carriers may play a role in their higher risk of breast cancer. The fraction of p63⁺TCF7⁺ myoepithelial cells is also significantly decreased in DCIS, which may be associated with invasive progression.

Molecular profiling of microinvasive breast cancer microenvironment progression

Background

Tumors develop by progression through a series of stages. Every cell of the tumor microenvironment is constantly changing in the flow of the cancer progression. It has become clear in recent years that stroma is essential for tumor maintenance and growth. Here, we aimed to give a chronological order of gene expression changes given in the dynamical framework of microinvasive breast cancer microenvironment.

Methods

RNA-seq was performed on seven microinvasive breast cancers. For each of them we microdissected seven different portions of the tumor, four related to the breast epithelium and three to the stroma. Breast epithelium was chronologically subdivided in normal breast epithelium (NBE), carcinoma in situ (CIS), emerging invasive fingers (EIF) and invasive breast cancer (IBC). For each of the breast epithelium subdivisions we collected the adjacent stroma (S): S-NBE, S-EIF and S-IBC.

Results

The overall differentially expressed genes (DEGs) in all the compartments were analysed and evaluated to understand the pathways involved in tumor progression. Then we analysed the DEGs of the epithelial and stromal portions in comparison with the normal portions. We observed that the stromal cells are necessary for the development and the maintenance of the tumor, especially in tumor progression. Moreover the most important genes involved in the main metabolic pathways were analysed and the communications within the different cell compartments were highlighted.

Conclusions

As a future perspective, a deeply study of the identified key genes, particularly in the stromal cells, will be crucial to develop an anticancer therapy that is undergoing a conversion from a cancer cell-centric strategy to a stroma-centric strategy, more genomically stable.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1936-x) contains supplementary material, which is available to authorized users.

Chemokine Signaling Facilitates Early-Stage Breast Cancer Survival and Invasion through Fibroblast-Dependent Mechanisms

Ductal carcinoma in situ (DCIS) is the most common form of breast cancer, with 50,000 cases diagnosed every year in the United States. Overtreatment and undertreatment remain significant clinical challenges in patient care. Identifying key mechanisms associated with DCIS progression could uncover new biomarkers to better predict patient prognosis and improve guided treatment. Chemokines are small soluble molecules that regulate cellular homing through molecular gradients. CCL2-mediated recruitment of CCR2⁺ macrophages are a well-established mechanism for metastatic progression. Although the CCL2/CCR2 pathway is a therapeutic target of interest, little is known about the role of CCR2 expression in breast cancer. Here, using a mammary intraductal injection (MIND) model to mimic DCIS formation, the role of CCR2 was explored in minimally invasive SUM225 and highly invasive DCIS.com breast cancer cells. CCR2 overexpression increased SUM225 breast cancer survival and invasion associated with accumulation of CCL2 expressing fibroblasts. CCR2-deficient DCIS.com breast cancer cells formed fewer invasive lesions with fewer CCL2⁺ fibroblasts. Cografting CCL2-deficient fibroblasts with DCIS.com breast cancer cells in the subrenal capsule model inhibited tumor invasion and survival associated with decreased expression of aldehyde dehydrogenase (ALDH1), a proinvasive factor, and decreased expression of HTRA2, a proapoptotic serine protease. Through data mining analysis, high expression of CCR2 and ALDH1 and low HTRA2 expression were correlated with poor prognosis of breast cancer patients.Implications: This study demonstrates that CCR2 overexpression in breast cancer drives early-stage breast cancer progression through stromal-dependent expression of CCL2 with important insight into prognosis and treatment of DCIS. Mol Cancer Res; 16(2); 296-308. ©2017 AACR.

Myoepithelial cells in canine mammary tumours

Mammary tumours are the most common neoplasms of female dogs. Compared to mammary tumours of humans and cats, myoepithelial (ME) cell involvement is common in canine mammary tumours (CMT) of any subtype. Since ME cell involvement in CMT influences both histogenetic tumour classification and prognosis, correct identification of ME cells is important. This review describes immunohistochemical methods for identification of canine mammary ME cells used in vivo. In addition, phenotypic and genotypic methods to isolate ME cells for in vitro studies to analyse tumour-suppressor protein production and gene expression are discussed. The contribution of ME cells to both histogenetic classifications and the prognosis of CMT is compared with other species and the potential use of ME cells as a method to identify carcinoma in situ is discussed.

Tyrosine kinase discoidin domain receptors DDR1 and DDR2 are coordinately deregulated in triple-negative breast cancer

Receptor kinases Discoidin Domain Receptors (DDRs) 1 and 2 are emerging as new therapeutic targets in breast cancer (BC). However, the expression of DDR proteins during BC progression and their association with BC subtypes remain poorly defined. Herein we report the first comprehensive immunohistochemical analyses of DDR protein expression in a wide range of breast tissues. DDR1 and DDR2 expression was investigated by immunohistochemistry in 218 samples of normal breast (n = 10), ductal carcinoma in situ (DCIS, n = 10), and invasive carcinomas (n = 198), arrayed in tissue microarrays with comprehensive clinical and follow-up information. Staining was evaluated for cell type, subcellular localization, percentage and intensity (scores 1-4), and association with disease subtype and outcome. In normal epithelium and DCIS, DDR1 was highly expressed, while DDR2 was negative in normal epithelium, and in DCIS it localized to cells at the epithelial-stromal interface. Of the 198 invasive carcinomas, DDR1 was high in 87 (44 %) and low in 103 (52 %), and DDR2 was high in 110 (56 %) and low in 87 (44 %). High DDR2 was associated with high tumor grade (P = 0.002), triple-negative subtype (TNBC) (P < 0.0001), and worse survival (P = 0.037). We discovered a novel concordant deregulation of DDR expression, with a DDR1(Low)/DDR2(High) profile significantly associated with TNBC, compared to luminal tumors (P = 0.012), and with worse overall survival. In conclusion, DDR2 upregulation occurs in DCIS, before stromal invasion, and may reflect epithelial-stromal cross-talk. A DDR1(Low)/DDR2(High) protein profile is associated with TNBC and may identify invasive carcinomas with worse prognosis.

Breast ductal carcinoma in situ presenting as recurrent non-puerperal mastitis: case report and literature review

Breast ductal carcinoma in situ (DCIS) is a preinvasive form of breast cancer. It typically presents as microcalcifications which are picked up on screening mammogram. We report an atypical case of breast DCIS presenting with recurrent non-puerperal mastitis with a normal mammogram and perform a literature review.

Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

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

CONCLUSIONS

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

Topographical, morphological and immunohistochemical characteristics of carcinoma in situ of the breast involving sclerosing adenosis. Two distinct topographical patterns and histological types of carcinoma in situ

AIM

To examine the histopathological features of 24 surgically resected carcinoma in situ (CIS) involving sclerosing adenosis (SA), with special reference to the topographical relationship between CIS and SA.

METHODS AND RESULTS

In 13 (54%) lesions, CIS was entirely surrounded by SA (type A) and in 11 (46%), CIS involved SA at least focally but was not confined to the SA area (type B). The mean size of CIS in type B (30.45 mm) was significantly larger than in type A (18.00 mm). The mean size of SA in type A (39.46 mm) was significantly larger than in type B (19.54 mm). Most type A CIS were non-high-grade, and the oestrogen receptor (ER)(+)/progesterone receptor (PgR)(+)/HER2(-) immunophenotype predominated. Most type B CIS were high-grade and six (54%) were ER(-)/PgR(-). Most type A were bcl-2(+)/p53(-) in both SA and CIS areas, but two (18%) apocrine ductal CIS of type B were bcl-2(-)/p53(+) in both SA and CIS areas. Expression of ER and cyclin D1 in SA was not different from that of SA unassociated with cancer.

CONCLUSIONS

Most CIS involving SA arises within SA and high-grade DCIS tends to grow beyond SA. Occasional CIS may arise outside SA and secondarily involve SA.

Microenvironmental influences that drive progression from benign breast disease to invasive breast cancer

Invasive breast cancer represents the endpoint of a developmental process that originates in the terminal duct lobular units and is believed to progress through stages of increasing proliferation, atypical hyperplasia, and carcinoma in situ before the cancer acquires invasive and metastatic capabilities. By comparison with invasive breast cancer, which has been studied extensively, the preceding stages of benign breast disease are more poorly understood. Much less is known about the molecular changes underlying benign breast disease development and progression, as well as the transition from in situ into invasive disease. Even less focus has been given to the specific role of stroma in this progression. The reasons for lack of knowledge about these lesions often come from their small size and limited sample availability. More challenges are posed by limitations of the models used to investigate the lesions preceding invasive breast cancer. However, recent studies have identified alterations in stromal cell function that may be critical for disease progression from benign disease to invasive cancer: key functions of myoepithelial cells that maintain tissue structure are lost, while tissue fibroblasts become activated to produce proteases that degrade the extracellular matrix and trigger the invasive cellular phenotype. Gene expression profiling of stromal alterations associated with disease progression has also identified key transcriptional changes that occur early in disease development. In this review, we will summarize recent studies showing how stromal factors can facilitate progression of ductal carcinoma in situ to invasive disease. We also suggest approaches to identify processes that control earlier stages of disease progression.

The role of the microenvironment in mammary gland development and cancer

The mammary gland is composed of a diverse array of cell types that form intricate interaction networks essential for its normal development and physiologic function. Abnormalities in these interactions play an important role throughout different stages of tumorigenesis. Branching ducts and alveoli are lined by an inner layer of secretory luminal epithelial cells that produce milk during lactation and are surrounded by contractile myoepithelial cells and basement membrane. The surrounding stroma comprised of extracellular matrix and various cell types including fibroblasts, endothelial cells, and infiltrating leukocytes not only provides a scaffold for the organ, but also regulates mammary epithelial cell function via paracrine, physical, and hormonal interactions. With rare exceptions breast tumors initiate in the epithelial compartment and in their initial phases are confined to the ducts but this barrier brakes down with invasive progression because of a combination of signals emitted by tumor epithelial and various stromal cells. In this article, we overview the importance of cellular interactions and microenvironmental signals in mammary gland development and cancer.

Calponin expression and myoepithelial cell differentiation in canine, feline and human mammary simple carcinomas

Calponin is a 34-kDa smooth muscle-specific protein that has been shown to be a highly sensitive marker of myoepithelial cells in canine, feline and human mammary tissue and tumours. The expression of calponin was studied in 15 canine, 32 feline and 28 human simple mammary carcinomas using a monoclonal mouse antihuman calponin antibody and the avidin-biotin peroxidase complex (ABC) immunohistochemical technique. Calponin expression was compared with the expression of cytokeratin 14, a marker of normal mammary myoepithelial cells in the three species. Four different types of calponin-positive cells were identified: (1) Type 1: cytokeratin-14-positive pre-existing myoepithelial cells forming a continuous layer with images of focal disruptions; (2) Type 2: cytokeratin-14-positive isolated nests of fusiform, polygonal or round cells without atypia; (3) Type 3: cytokeratin-14-positive atypical cells indistinguishable from non-reactive atypical cells, which should have never been detected in haematoxylin and eosin-stained sections and (4) Type 4: cytokeratin-14-negative stromal fusiform cells around the neoplastic growth or cell nests, identified as myofibroblasts. Calponin-negative and cytokeratin-14-positive atypical neoplastic cells were observed in three canine, 28 feline and two human carcinomas. The latter were indicative of altered expression of high-molecular-weight cytokeratins in luminal epithelial-type simple carcinomas. Our findings show that calponin is a good marker of myoepithelial cell differentiation in feline, human and, particularly, canine simple carcinomas. The high number (six out of 15) of canine tumours with type 3 cells points to the need of both introducing calponin examination in the routine diagnostic schedule and performing further studies on its prognostic significance.

Application of immunohistochemistry to breast lesions

CONTEXT

Immunohistochemistry has an expanding role in mammary pathology that has been facilitated by a growing list of available antibodies and a better understanding of biology.

OBJECTIVE

To explore the key role of immunohistochemistry in guiding adjuvant therapy decisions and sentinel node staging in breast cancer, as well as the role of immunohistochemistry as an aid to distinguishing usual ductal hyperplasia from atypical ductal hyperplasia/low-grade carcinoma in situ; subtyping a carcinoma as ductal or lobular, basal or luminal; ruling out microinvasion in extensive intraductal carcinoma; distinguishing invasive carcinoma from mimics; and establishing that a metastatic carcinoma of unknown primary site has originated in the breast.

DATA SOURCES

Current literature is reviewed, including clinical and pathologic journals.

CONCLUSIONS

As new, targeted treatments for breast cancer are developed, pathologists can expect additional immunohistochemistry applications in the future.

Squamous cell carcinoma in situ of the breast: a light microscopic and immunohistochemical study of a previously undescribed lesion

Three cases of squamous carcinoma in situ of the breast, one with an invasive component are described in women aged 35, 51, and 59 years. Two cases were detected by screening mammography. In 1 case, the squamous ductal carcinoma in situ was extensive. All cases showed obvious squamous features on standard hematoxylin and eosin sections. The in situ component of the lesions and the squamous differentiation were supported by immunohistochemistry. In 2 cases, the neoplastic cells showed actin positivity indicating myoepithelial cell differentiation. One case showed trilineage differentiation into luminal, squamous, and myoepithelial cells. These cases illustrate a variant of duct carcinoma in situ that has not been described in the current literature and provide insights into the dual epithelial-myoepithelial differentiation of some breast neoplasms.

Immunohistochemical staining of papillary breast lesions

The separation of ductal papilloma from intraductal papillary carcinoma of the breast on hematoxylin and eosin stained sections often presents diagnostic difficulty. Immunohistochemical staining is often employed in diagnosis, historically with smooth muscle actin (SMA). In this study, the staining characteristics of a panel of myoepithelial markers (calponin, p63, P-cadherin), were compared with SMA, and the epithelial expression of CD44s was assessed in 99 papillary lesions. SMA, calponin, and p63 demonstrated myoepithelial cells in 61%, 63%, and 65% of papillary lesions, respectively. However, specificity was quite variable. Calponin-stained stromal myofibroblasts (35% of cases), vessel pericytes (92%), and endothelial cells (69%), though each to a lesser degree than SMA. Calponin also showed cross reactivity with epithelium in 18% of cases. p63 was almost completely restricted to myoepithelial cell nuclei, and did not stain vascular smooth muscle or myofibroblasts. However, p63 stained the epithelial component in one papillary carcinoma, a basal layer of cells in 1 biphasic invasive carcinoma, and the cytoplasm in 1 case. P-cadherin stained both epithelial and myoepithelial cells. The epithelial expression of CD44s and did not distinguish papillomas from papillary carcinomas. Thus, P-cadherin and CD44s are not useful in the characterization of papillary lesions. Given increased specificity as compared with SMA, the combination of p63 and calponin is recommended for analysis of breast papillary lesions.

Sentinel lymph node biopsy in staging small (up to 15 mm) breast carcinomas. Results from a European multi-institutional study

Sentinel lymph node (SLN) biopsy has become the preferred method for the nodal staging of early breast cancer, but controversy exists regarding its universal use and consequences in small tumors. 2929 cases of breast carcinomas not larger than 15 mm and staged with SLN biopsy with or without axillary dissection were collected from the authors' institutions. The pathology of the SLNs included multilevel hematoxylin and eosin (HE) staining. Cytokeratin immunohistochemistry (IHC) was commonly used for cases negative with HE staining. Variables influencing SLN involvement and non-SLN involvement were studied with logistic regression. Factors that influenced SLN involvement included tumor size, multifocality, grade and age. Small tumors up to 4 mm (including in situ and microinvasive carcinomas) seem to have SLN involvement in less than 10%. Non-SLN metastases were associated with tumor grade, the ratio of involved SLNs and SLN involvement type. Isolated tumor cells were not likely to be associated with further nodal load, whereas micrometastases had some subsets with low risk of non-SLN involvement and subsets with higher proportion of further nodal spread. In situ and microinvasive carcinomas have a very low risk of SLN involvement, therefore, these tumors might not need SLN biopsy for staging, and this may be the approach used for very small invasive carcinomas. If an SLN is involved, isolated tumor cells are rarely if ever associated with non-SLN metastases, and subsets of micrometastatic SLN involvement may be approached similarly. With macrometastases the risk of non-SLN involvement increases, and further axillary treatment should be generally indicated.

Do myoepithelial cells hold the key for breast tumor progression?

Mammary myoepithelial cells have been a neglected facet of breast cancer biology, largely ignored since they have been considered to be less important for tumorigenesis than luminal epithelial cells from which most of breast carcinomas are thought to arise. In recent years as our knowledge of stem cell biology and the cellular microenvironment has been increasing, myoepithelial cells are slowly starting to gain more attention. Emerging data raise the hypothesis whether myoepithelial cells play a key role in breast tumor progression by regulating the in situ to invasive carcinoma transition and that myoepithelial cells are part of the mammary stem cell niche. Paracrine interactions between myoepithelial and luminal epithelial cells are known to be important for regulation of cell cycle progression, establishing epithelial cell polarity, and inhibiting cell migration and invasion. Based on these functions, normal mammary myoepithelial cells have been called "natural tumor suppressors." However, during tumor progression myoepithelial cells seem to loose these properties, and eventually this cell population diminishes as tumors become invasive. Better understanding of myoepithelial cell function and their role in tumor progression may lead to their exploitation for cancer therapeutic and preventative measures.

cDNA expression profiling reveals elevated gene expression in cell clusters overlying focally disrupted myoepithelial cell layers: implications for breast tumor invasion

BACKGROUND

Our previous studies revealed that a subset of mammary ductal carcinoma in situ (DCIS) contained focally disrupted myoepithelial (ME) cell layers that were predominantly overlain by estrogen receptor (ER) negative cells, which showed a substantially higher rate of cell proliferation and genetic alterations than adjacent ER positive cells within the same duct. This study attempted to assess whether these cells also had a different expression profile on tumor progression related genes.

DESIGN

Consecutive sections were made from frozen tissues of 30 DCIS with focally disrupted ME cell layers and associated ER negative cell clusters. ER negative and adjacent ER positive cells within the same duct were microdissected for RNA extraction and amplification. Amplified RNA was converted to biotin-labeled cDNAs and interrogated with 'Cancer PathwayFinder' arrays.

RESULTS

Cells within each or among ER negative clusters were immunohistochemically and morphologically similar, whereas they differed substantially from adjacent cells within the same duct. Of 20-paired informative ER negative and positive cells, 15 genes were differentially expressed. Of which, 11(73.3%) were higher in ER negative, 2 (13.3%) were higher in ER positive, and 2 (13.3%) were equal in these cells (p <0.01). Of 11 up-regulated genes in ER negative cells, 8 indirectly or directly promote proliferation and progression, and 3 promote apoptosis.

CONCLUSION

ER negative cell clusters showed a significantly higher expressing frequency of multiple tumor progression related genes than their adjacent ER positive counterparts, suggesting that they are likely to be biologically more aggressive and have a greater potential for invasion.

Ductal carcinoma in situ-like structures in metastatic breast carcinoma

In this report, we present two cases of axillary lymph node metastatic breast carcinoma with features mimicking ductal carcinoma in situ (DCIS): one was of the comedo-like type and the other was suggestive of the micropapillary type. In the first case, the primary tumor presented DCIS of the comedo type; however, in the second case, the primary tumor consisted only of the invasive ductal component. Immunohistochemistry against smooth muscle actin, S100-protein, CK5/6, CD10, P63, and 34betaE12 did not identify myoepithelial cells either in DICS of the first primary tumor or in both metastases. These features probably do not represent the true DCISs, but only mimic them. This observation suggests that a proportion of "primary DCIS" may constitute an invasive pseudo-DCIS carcinoma, and immunohistochemical identification of myoepithelial cells may be helpful in such cases.

The significance of focal myoepithelial cell layer disruptions in human breast tumor invasion: a paradigm shift from the "protease-centered" hypothesis

Human breast epithelium and the stroma are separated by a layer of myoepithelial (ME) cells and basement membrane, whose disruption is a prerequisite for tumor invasion. The dissolution of the basement membrane is traditionally attributed primarily to an over-production of proteolytic enzymes by the tumor or the surrounding stromal cells. The results from matrix metalloproteinase inhibitor clinical trials, however, suggest that this "protease-centered" hypothesis is inadequate to completely reflect the molecular mechanisms of tumor invasion. The causes and signs of ME cell layer disruption are currently under-explored. Our studies revealed that a subset of pre- and micro-invasive tumors contained focal disruptions in the ME cell layers. These disruptions were associated with immunohistochemical and genetic alterations in the overlying tumor cells, including the loss of estrogen receptor expression, a higher frequency of loss of heterozygosity, and a higher expression of cell cycle, angiogenesis, and invasion-related genes. Focal ME layer disruptions were also associated with a higher rate of epithelial proliferation and leukocyte infiltration. We propose the novel hypothesis that a localized death of ME cells and immunoreactions that accompany an external environmental insult or internal genetic alterations are triggering factors for ME layer disruptions, basement membrane degradation, and subsequent tumor progression and invasion.

Immunostaining patterns of myoepithelial cells in breast lesions: a comparison of CD10 and smooth muscle myosin heavy chain

BACKGROUND

Recent studies have reported CD10 expression in myoepithelial cells (MEC) of the breast, supporting its use as a marker to help distinguish invasive breast carcinoma (IC) from ductal carcinoma in situ (DCIS).

AIM

To compare the effectiveness of CD10 with smooth muscle myosin heavy chain (SMMHC) in the detection of MEC in benign and malignant breast lesions.

METHODS

Histological material from 25 patients with DCIS and 21 with IC were immunostained for CD10 and SMMHC. Staining was scored on a scale of 0 to 3+ (0, no staining; 3+, intense) and the staining distribution was documented as focal, partial, or circumferential.

RESULTS

Uniform, 3+ circumferential CD10 and SMMHC staining of MEC was seen in normal breast ducts and lobules, and in ducts and acini involved in sclerosing adenosis and apocrine metaplasia. In an analysis of total ducts involved by DCIS, 3+ circumferential staining was seen in 65 of 366 ducts (17.7%) stained for CD10 versus 190 of 396 ducts (48%) stained for SMMHC. MEC were not detected immunohistochemically in 116 of 366 ducts (31.7%) with anti-CD10 and 50 of 396 (12.7%) with anti-SMMHC. In contrast, all ICs were negative for both CD10 and SMMHC. Focal background staining of stromal myofibroblasts was seen with both CD10 and SMMHC, but CD10 showed a higher rate of non-specific staining of epithelial cells.

CONCLUSION

Although CD10 can aid in the distinction between IC and DCIS, SMMHC is a more sensitive and specific marker of MEC and shows less heterogeneity of immunostaining patterns.

Loss of types XV and XIX collagen precedes basement membrane invasion in ductal carcinoma of the female breast

Ductal and lobular carcinomas comprise most malignancies of the female breast and the morbidity and mortality associated with breast cancer. During the progression from in situ to invasive stages, tumour cells penetrate the epithelial and vascular basement membranes (BM) to realize full metastatic potential. While the definition of these structures has primarily resulted from analysis of laminin and type IV collagen, characterization of newly discovered BM/BM zone (BMZ) proteins will further elucidate the interactions between tumour cells and the host stroma. We have studied the expression of two non-fibrillar BMZ collagens, the type XV proteoglycan and collagen XIX, in breast cancer where a linear, well-formed BM becomes fragmented and even lost in the progression of epithelial malignancy. In the normal breast, types XV and XIX were found in all BMZ: epithelial, muscle, neural, endothelial, and fat. In in situ lesions, these two collagens, and particularly type XV, were often absent from the BM/BMZ displaying a continuous or just focally disrupted type IV/laminin staining pattern. In contrast, infiltrating ductal carcinomas showed only rare traces of laminin and collagen IV reactivity adjacent to the glands and tumour nests, and similarly there was little if any evidence of types XV and XIX collagen. All four molecules were, however, detected in the interstitium associated with some of the invasive carcinomas. The data suggest that types XV and XIX collagen are lost early in the development of invasive tumours, prior to penetration and eventual dissolution of the epithelial BM. Disappearance of these proteins from the BM/BMZ may signal remodelling of the extracellular matrix to promote tumour cell infiltration.

A subset of morphologically distinct mammary myoepithelial cells lacks corresponding immunophenotypic markers

INTRODUCTION

Immunostaining for smooth muscle actin (SMA) is commonly used to elucidate mammary myoepithelial (ME) cells, whose presence or absence is a reliable criterion for differentiating in situ and invasive carcinomas. However, some morphologically distinct ME cells fail to stain for SMA. This study intended to assess whether these SMA-negative cells also lack the expression of other ME cell markers.

METHODS

Hematoxylin/eosin and SMA immunostained sections from 175 breast cancer patients were examined. Three cases were found to harbor ducts that showed morphologically distinct ME cell layers, but showed no SMA immunostaining in at least one-third of the layer or the entire layer. Eight additional consecutive sections from each case were stained for SMA, using a black chromogen, and each was then re-stained for one of eight additional markers supposed to exclusively or preferentially stain ME cells, using a red chromogen. SMA-negative ME cells were re-examined for the expression of other markers.

RESULTS

SMA-negative ME cells in two cases also failed to display immunoreactivity for other markers, including calponin, CD10, smooth muscle myosin heavy chain, protease inhibitor 5 (maspin), Wilms' tumor-1, and cytokeratins 5, 14, and 17 (CK5, CK14, and CK17). However, in one case SMA-negative ME cells displayed immunoreactivities for maspin, CK5, CK14, and CK17. The distribution of these ME cells is independent of ductal size, length, and architecture.

CONCLUSIONS

A subset of morphologically identifiable ME cells lack the expression of nine corresponding immunophenotypic markers, suggesting that ME cells might also be subject to different normal and pathological alterations.

Immunohistochemical distinction of invasive from noninvasive breast lesions: a comparative study of p63 versus calponin and smooth muscle myosin heavy chain

Identification of myoepithelial cells using antibodies to cytoskeletal proteins, such as smooth muscle myosin heavy chain (SMM-HC) and calponin, can play an important role in distinguishing invasive carcinoma from its histologic mimics. However, antibodies to these proteins may also cross-react with stromal myofibroblasts and vascular smooth muscle cells. It has recently been demonstrated that myoepithelial cells express the nuclear protein, p63, a member of the p53 gene family. We compared the patterns of reactivity of antibodies with p63, calponin, and SMM-HC on 85 breast lesions, including 11 cases of sclerosing adenosis, 33 cases of ductal carcinoma in situ, including 10 that showed microinvasion, 6 cases of lobular carcinoma in situ, and 35 cases of infiltrating ductal carcinoma. All three antibodies were positive on the vast majority of myoepithelial cells in all cases. A small minority of cases showed focal gaps in the revealed myoepithelial cell layer, reflected in discontinuous positive immunostaining around noninvasive epithelial nests (including ductal carcinoma in situ). No case showed p63 expression by myofibroblasts or vascular smooth muscle cells, whereas myofibroblasts expressed, in 8% and 76% of cases, SMM-HC and calponin, respectively. Although no tumor cell reactivity was noted with antibodies to calponin or SMM-HC, tumor cells in 11% of cases showed at least focal p63 expression. And although antibodies to p63 offer excellent sensitivity and increased specificity for myoepithelial detection relative to antibodies to calponin and SMM-HC, they have the following diagnostic limitations: 1) they occasionally demonstrate an apparently discontinuous myoepithelial layer, particularly around ductal carcinoma in situ, and 2) they react with a small but significant subset of breast carcinoma tumor cells. p63 may represent a myoepithelial marker that can complement or replace SMM-HC and/or calponin in the analysis of difficult breast lesions.

Is p63 reliable in detecting microinvasion in ductal carcinoma in situ of the breast?

P63, a p53 homologue, is considered to be a marker of myoepithelial cells in breast tissue. This study was carried out to determine the sensitivity of p63 in detecting myoepithelial cells in DCIS and to compare the results obtained with smooth-muscle actin (1A4) in an attempt to verify the reliability of p63 as a possible marker of microinvasion in breast carcinoma. Fifteen DCIS of the breast were submitted to immunohistochemical analysis with anti-p63 and 1A4 antibodies and to a double immunolabeling study using p63 with 1A4. The double immunolabeling study showed that the same cells positive for p63 were also positive for 1A4. The three cases of DCIS with micro-invasion were negative for p63 and 1A4 in the foci of invasiveness. P63 staining was continuous in five of twelve cases of DCIS without microinvasion, being focal and discontinuous in 6 cases and completely negative in one case. Smooth-muscle actin staining was continuous in nine of twelve cases, including the five cases positive for p63. Smooth-muscle actin was focal and discontinuous in only two cases, which were also discontinuous for p63. The DCIS negative for p63 was also negative for 1A4. In conclusion, our results confirm the data of literature that p63 is a specific marker of myoepithelial cells in breast tissue. However, p63 is not as sensitive as 1A4 in staining myoepithelial cells and lack of p63 expression cannot be used as a reliable marker of invasiveness in ductal carcinoma in situ of the breast.

High basic fibroblast growth factor levels in nipple aspirate fluid are correlated with breast cancer

PURPOSE

The angiogenic basic fibroblast growth factor (bFGF) and vascular endothelial growth factor are important in malignant breast epithelial growth. Nipple aspirate fluid (NAF) is a physiologic fluid collected noninvasively that contains proteins secreted by the breast ductal epithelium and may contain markers of breast cancer. The purpose of this study was to determine whether high concentrations of bFGF and vascular endothelial growth factor in NAF would be associated with in situ and invasive breast cancer, and whether prostate-specific antigen, a marker in NAF associated with breast cancer, would improve our ability to determine which subjects had the disease.

METHODS

Both bivariate and multivariate analyses were performed to determine the effects of race, menopausal status, bFGF concentration, and prostate-specific antigen on cancer risk. Bivariate analysis was also performed to determine the relationship between vascular endothelial growth factor concentration and cancer risk.

RESULTS

Mean NAF bFGF levels were higher in women with breast cancer than in those without (19.2 vs 1.74 ng/g). Vascular endothelial growth factor was not associated with breast cancer. Race and menopausal status did not significantly affect the relationship between bFGF and cancer risk. bFGF, race, and menopausal status were each independent predictors of breast cancer, with bFGF being the most important. With knowledge of all three variables, the model was 89.9% sensitive and 69.0% specific in predicting which women had breast cancer. Adding prostate-specific antigen increased the sensitivity to 90.9% and the specificity to 83.3%. In subjects with NAF bFGF > 150 ng/g and prostate-specific antigen < 100 ng/g, 94.1% (32/34) of subjects had cancer. For women with NAF prostate-specific antigen > 100 ng/ g and bFGF < 150 ng/g, 90.5% were cancer free.

CONCLUSIONS

bFGF concentration in NAF is directly associated with breast cancer, regardless of race and menopausal status. NAF bFGF may prove helpful in the early detection of breast cancer.

Urokinase receptor-associated protein (uPARAP) is expressed in connection with malignant as well as benign lesions of the human breast and occurs in specific populations of stromal cells

The urokinase-type plasminogen activator (uPA) and the uPA receptor (uPAR) are key components in the plasminogen activation system, serving to promote specific events of extracellular matrix degradation in connection with tissue remodeling and cancer invasion. We recently described a new uPAR-associated protein (uPARAP), an internalization receptor that interacts with the pro-uPA:uPAR complex. In our study, we generated a specific polyclonal peptide antibody against human uPARAP and used it for the localization of uPARAP in different breast lesions. The affinity-purified antibodies specifically recognized uPARAP in Western blotting and gave a strong signal in immunohistochemistry. The immunohistochemic localization pattern was found to be identical to that of uPARAP mRNA as determined in parallel by in situ hybridization. uPARAP expression was then studied in both benign and malignant breast lesions. Whereas the normal breast tissue was uPARAP-negative, all benign lesions and ductal carcinoma in situ lesions showed immunoreactivity in fibroblast-like cells and myoepithelial cells associated with the lesion. In invasive carcinoma, uPARAP immunoreactivity was limited to tumor-associated mesenchymal cells. Double immunofluorescence analysis of invasive ductal carcinoma using antibodies against specific cell markers showed that uPARAP was localized in myofibroblasts and macrophages. No malignant cells, no endothelial cells and no vascular smooth muscle cells showed uPARAP immunoreactivity. We conclude that expression of uPARAP is associated with the abnormal breast and that expression appears in myofibroblasts, macrophages and myoepithelium. We suggest that uPARAP is involved in the clearance of the uPA:uPAR complex as well as other possible ligands during benign and malignant tissue remodeling.

Immunolocalization of the smooth muscle-specific protein calponin in complex and mixed tumors of the mammary gland of the dog: assessment of the morphogenetic role of the myoepithelium

The immunohistochemical expression of the smooth muscle-specific protein calponin was studied to assess the contribution of myoepithelial cells to the histogenesis of spindle cells of complex and mixed tumors of the mammary gland of the dog and the origin of cartilage and bone in mixed tumors. Formalin-fixed tissues from 55 benign and malignant tumors (49 also containing surrounding normal mammary gland) were evaluated. Periacinar and periductal myoepithelial cells of all the 49 normal mammary glands were diffusely stained by the anti-human calponin monoclonal antibody. Calponin was found in 53 (98%) of the tumors studied, reacting with the myoepithelium-like cells of 86% of benign tumors and their remnants in 85% of malignant tumors. Five different types of calponin-immunoreactive myoepithelial cells were identified: hypertrophic myoepithelial cells. fusiform cells, stellate myoepithelial cells, rounded (myoepithelial) cells, and chondroblasts. Differences in staining intensity and staining pattern among these five types of cells suggested a transition of myoepithelial cells to chondroblasts. Stromal myofibroblasts also showed calponin immunoreactivity, but they did not react with a cytokeratin 14 monoclonal antibody, which recognizes myoepithelial cells in mammary gland. Calponin appears to be a very sensitive marker of normal and neoplastic myoepithelium in the canine mammary gland, and its identification in different cell types of complex and mixed tumors of the mammary gland of the dog suggests a major histogenetic role for myoepithelial cells.

p63, a p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast

Myoepithelial cells (MCs) constitute the basal cell layer of normal mammary epithelia, and their identification is of particular diagnostic value because they are retained in most benign lesions while being lost in malignancy. Several MC immunocytochemical markers are currently available for diagnostic purposes, with special reference to smooth muscle-related antigens. p63 is a member of the p53 gene family, and its germline mutations are associated with severe mammary developmental defects in both rodents and humans. Different p63 isoforms have been identified, some of which (DeltaNp63) are preferentially expressed in the epithelial basal cells of different organs and have been considered as possible markers of stem cells/reserve cells. We investigated immunohistochemically 384 samples of normal and diseased human breast, including 300 invasive carcinomas, using four antibodies recognizing all p63 isoforms, or the DeltaNp63 isoforms. Twenty cytologic specimens were also investigated. Furthermore, snap-frozen tissue samples from three fibroadenomas and 10 invasive ductal carcinomas with their paired non-neoplastic tissues and three corresponding lymph node metastases were evaluated for the expression of p63 mRNA by RT-PCR. In normal breast tissue p63 immunoreactivity was confined to the nuclei of MCs. In all benign lesions p63-immunoreactive cells formed a continuous basal rim along the epithelial structures. Stromal cells, and in particular myofibroblasts, were consistently unreactive. Adenomyoepitheliomas showed nuclear staining in most neoplastic cells. A peripheral rim of p63-immunoreactive cells was retained surrounding lobular and ductal carcinoma in situ, although it was discontinuous as opposed to the normal structures. Invasive breast carcinomas were consistently devoid of nuclear p63 staining, with the exception of the two adenoid-cystic carcinomas, of the two ductal carcinomas with squamous metaplasia, and of 11 (4.6%) ductal carcinomas not otherwise specified, showing p63 immunoreactivity in a minor fraction (5-15%) of the neoplastic cells. In comparison with other MC markers, p63 was the most specific, being restricted exclusively to MCs, whereas antibodies to smooth muscle actin and, to a lesser extent, calponin also decorated stromal myofibroblasts. In the cytologic preparations p63 immunoreactivity was a consistent feature of "naked nuclei" and of a subset of cells surrounding benign epithelial clusters. RT-PCR experiments with primers specific for different p63 isoforms documented that normal tissues and fibroadenomas preferentially expressed the DeltaNp63 isoforms. Our study demonstrates that in normal and pathologic breast tissues MCs consistently express the DeltaNp63 isoforms. We suggest p63 as a reliable, highly specific, and sensitive MC marker in both histologic and cytologic preparations. Furthermore, because p63 immunoreactivity in adult epithelia is normally restricted to progenitor cells, it can be speculated that it might be a clue for the identification of the still elusive breast progenitor cells.

Lymphoepithelioma-like carcinoma of the breast: lack of evidence of Epstein-Barr virus infection

AIMS

Six cases of lymphoepithelioma-like carcinomas of the breast were studied in order to better define the morphology of this type of breast tumour and to see if these neoplastic lesions are related to Epstein-Barr virus (EBV) infection by analogy with histologically similar tumours located in other organs.

METHODS AND RESULTS

The cases were studied with immunohistochemistry using several antibodies and with in-situ hybridization method employing different types of nucleotides in four cases. The cases presented the distinctive morphology of the lymphoepithelioma-like carcinomas as seen in other organs. Specifically Rigaud and Schminke's patterns of growth were observed. In addition, at the edge of the neoplastic lesions, a lymphoepithelial lobulitis was seen. In-situ hybridization failed to reveal any positivity for EBV genome.

CONCLUSION

Lymphoepithelioma-like carcinoma is a specific type of breast tumour, but its relation to EBV has yet to be proven. The differential diagnosis with medullary carcinoma is discussed.

Differential Expression of Myoepithelial Markers in Salivary, Sweat and Mammary Glands

Myoepithelial cells (MECs) are contractile elements showing a combined epithelial and smooth muscle phenotype. Among the numerous immunohistochemical markers employed to detect MECs, smooth muscle actin (SMA) is the most widely used. Recently, other markers of smooth muscle differentiation have been demonstrated in MECs, such as calponin, heavy caldesmon (h-caldesmon), and smooth muscle myosin heavy chain (SMM-HC). In the present study normal salivary, mammary, and sweat glands have been studied with four markers of smooth muscle differentiation (SMA, calponin, h-caldesmon, and SMM-HC). The four markers were differentially expressed in the various types of glands. In parotid glands MECs mainly expressed calponin and caldesmon; in submandibular and in cutaneous apocrine and eccrine glands, MECs strongly expressed SMA, calponin, and caldesmon; in minor salivary glands all four markers were equally strongly expressed; and in mammary glands SMA, calponin, and SMM-HC were present both in periductal and periacinar MECs while caldesmon was present in periductal MECs only. In addition to MECs, SMA stained stromal myofibroblasts, sometimes hampering the identification of MECs. Among the other markers, calponin stained only rare stromal myofibroblasts, while caldesmon and SMM-HC were confined to MECs. In conclusion, these latter markers are very useful for identifying MECs. It is suggested that the differential expression of smooth muscle contractile proteins might reflect different functions of MECs in the various sites. Int J Surg Pathol 8(1):29-37, 2000