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

Gene expression profiling of NMU-induced rat mammary tumors: cross species comparison with human breast cancer

Breast cancer is a complex genetic disease characterized by the accumulation of multiple molecular alterations. The NMU breast cancer model induced in the rat is used for the study of mammary carcinogenesis because it closely mimics human breast disease. To assess the validity of this model from a more global molecular perspective, and also to devise a general technique to compare animal profiles with human microarray studies, we have characterized 25 NMU-induced mammary tumors and 11 normal glands using a combination of immunohistochemical and microarray analyses. The rat mammary carcinomas were classified as non-invasive, ER-positive ductal carcinomas with a composition of differentiated epithelial and myoepithelial cell lineages. Gene expression profiles generated using rat Affymetrix arrays containing 15,866 genes demonstrated that the rat mammary tumors are homogeneous and that H-ras mutations did not confer a unique molecular signature. We compared the resulting rat profiles with those obtained from a human dataset by merging the raw microarray data, using an approach that involves a combination of cross-species and cross-platform analysis. Using this novel strategy, we demonstrate the ability of 2305 rat orthologs to recapitulate the classification of human tumors derived from human Affymetrix arrays. The gene expression profiles of the NMU-induced primary tumors were most similar to ER-positive, low to intermediate grade breast cancer. Our technique provides a means to correlate gene expression data from animal models of cancer to human cancer and disease states.

p63 overexpression associates with poor prognosis in head and neck squamous cell carcinoma

p63 belongs to a protein family that includes 2 structurally related proteins, p53 and p73. The aim of this study was to investigate the biologic role of p63 in oral tumorigenesis and its possible role as prognostic marker in oral cancer. Ninety-four cases of oral squamous cell carcinoma and 10 cases of normal mucosa were analyzed for p63 expression by immunohistochemistry. Normal oral mucosa showed a basal and parabasal expression of p63. Five (5.3%) cases of oral cancer showed less than 10% of positive tumor cells; in 33 (35.1%) cases the positive tumor cells comprised between 10% and less than 30%, in 36 (38.3%) cases the positive tumor cells comprised between 30% and less than 50%, and in 20 (21.3%) cases the positive tumor cells were more than 50%. There was also a statistically significant correlation between p63 expression and tumor differentiation: p63 expression was amplified in poorly differentiated tumors (P < .05). When analyzed for prognostic significance, patients with perineural infiltration had poorer survival rates than the group with no perineural infiltration (P < .05) and patients with increased p63 expression had poorer survival rates than the group with reduced p63 expression (P < .05). The statistical analysis showed no significant correlation between p63 expression, sex, age, tumor size, staging, recurrence, and metastasis. Cases with diffuse p63 expression were more aggressive and poorly differentiated and related to a poorer prognosis. These data suggest that p63 expression may be useful to identify cases of oral squamous cell carcinoma with more aggressive and invasive phenotype providing novel diagnostic and prognostic information on individual patient survival with oral cancers.

Metaplastic breast carcinomas: are they of myoepithelial differentiation?: immunohistochemical profile of the sarcomatoid subtype using novel myoepithelial markers

We investigated 20 spindle cell (sarcomatoid) metaplastic carcinomas (MCs) without squamous differentiation. In addition, five high-grade phyllodes tumors were assessed for comparison. Our immunohistochemical antibody panel included pan-cytokeratin (CK), low molecular weight CK (CK8/18), four basal cell type CKs (34betaE12, CK5/6, CK14, and CK17), vimentin antibodies, as well as antibodies to established (SMA, CD10, p63, S-100, maspin, calponin, GFAP, SM-myosin), and novel (CD29, 14-3-3sigma) myoepithelial markers. Sixteen of the 20 tumors (80%) expressed at least two markers of the combination CD10/p63/SMA. S-100 detected 1 case negative for CD10/p63/SMA and 3 cases that only expressed one marker of this combination. While 18 MCs (90%) were positive for CD29, 14-3-3sigma (11 cases) and maspin (9 cases) were observed in 55% and 45%, respectively. Antibodies to pan-CK and the basal cell type CKs were strongly reactive in 12 tumors (60%), but in 6 cases (30%) positivity for these markers was weak and only focal; 2 MCs showed no positivity for CK. The stromal component of all phyllodes tumors was positive for vimentin, whereas all other investigated markers were absent except for focal p63 and CD10 expression in 1 case each. Our findings convincingly show a myoepithelial immunophenotype in sarcomatoid MCs, which is demonstrated by the presence of basal cell type CKs and the combination of the established myoepithelial markers CD10, p63, SMA, and S-100. We conclude that tumors with weak or even absent CK expression should only be diagnosed as primary sarcomas of the breast after exclusion of a myoepithelial immunophenotype. CD29 and 14-3-3sigma represent valuable novel myoepithelial markers in these diagnostically difficult cases.

Expression profiles of p63, p53, survivin, and hTERT in skin tumors

BACKGROUND

p63 is a p53 homolog and a marker expressed in replicating keratinocytes. Survivin is a recently characterized inhibitor of apoptosis protein that is abundantly expressed in most solid and hematologic malignancies. Telomerase reverse transcriptase (TERT) is the major determinant of human telomerase activity, and its expression is indicative of unlimited replication. We herein evaluated the expression profiles of p63, p53, survivin, and hTERT in usual skin cancers, including squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) and putative preneoplastic epidermal lesions, including actinic keratosis (AK), Bowen's disease, and porokeratosis.

METHODS

Immunohistochemistry using antibodies against p63, p53, survivin, and hTERT was performed. Semi-quantitative evaluation (-, +, 2+, 3+) was carried out.

RESULTS

BCCs showed diffuse p63 expression and SCCs heterogeneous p63 expression with negativity in terminally differentiated squamous cells. All preneoplastic epidermal lesions showed p63 expression in all cell layers. p53 was found in seven of 10 cases of BCCs, all 10 cases of SCCs, and nine of 10 cases of Bowen's disease. AK and porokeratosis revealed focal to moderate p53 expression. Survivin was found in eight of 10 cases of SCCs and eight of 10 cases of Bowen's disease. Six of 10 cases of BCCs revealed weak survivin positivity. AK and porokeratosis showed survivin expression confined to the basal layer. hTERT expression was found in most cases of skin cancers and preneoplastic lesions.

CONCLUSIONS

p63 expression may be a marker of basal/progenitor cells and a diagnostic marker in skin tumors. p63 expression is not related to p53 expression in these tumors. This study points to a putative role of survivin and hTERT in the development of certain skin cancers. In addition, our data support the concept of porokeratosis being a premalignant condition.

Down-regulation of the tumor suppressor protein 14-3-3sigma is a sporadic event in cancer of the breast

14-3-3 proteins comprise a family of highly conserved and broadly expressed multifunctional regulatory proteins that are involved in various cellular processes such as cell cycle progression, cell growth, differentiation, and apoptosis. Transcriptional expression of the sigma isoform of 14-3-3 is frequently impaired in human cancers, including carcinomas of the breast, which has led to the suggestion that this protein might be involved in the neoplastic transformation of breast epithelial cells. Here we report on the analysis of 14-3-3sigma expression in primary breast tumors using a proteomic approach complemented by immunohistochemical analysis by means of specific antibodies against this isoform. We show that the levels of expression of 14-3-3sigma were similar in non-malignant breast epithelial tissue and matched malignant tissue with only sporadic loss of expression observed in 3 of the 68 tumors examined. Moreover we show that 14-3-3sigma immunoreactivity was restricted to epithelial cells and significantly stronger in the myoepithelial cells that line the mammary ducts and lobules. The lack of expression of 14-3-3sigma in the three breast carcinomas was not associated with high levels of expression of the dominant-negative transcriptional regulator DeltaNp63 or with increased expression of estrogen-responsive finger protein, a ubiquitin-protein ligase (E3) that targets 14-3-3sigma for proteolysis. Validation of the results was performed retrospectively on an independent clinical tumor sample set using a tissue microarray containing 65 primary tumors. Our data suggest that, contrary to what was previously thought, loss of expression of 14-3-3sigma protein is not a frequent event in breast tumorigenesis.

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.

Expression of p63 in primary cutaneous adnexal neoplasms and adenocarcinoma metastatic to the skin

p63, a recently identified homologue of the p53 gene, has been reported to be essential in the development of epithelia and is mainly expressed by basal and myoepithelial cells. The purpose of this study was to investigate the pattern of p63 expression in cutaneous adnexal neoplasms and to assess its possible value in the differential diagnosis of primary cutaneous neoplasms vs adenocarcinomas metastatic to the skin. Immunohistochemical analysis for p63 was performed on formalin-fixed, paraffin-embedded archival tissue from 20 benign adnexal tumors, 10 malignant adnexal tumors and 14 adenocarcinomas metastatic to the skin. The expression of p63 was evaluated in epidermal cells, skin appendages and metastatic tumor cells. p63 was consistently expressed in the basal and suprabasal cells of epidermis and cutaneous appendages, including the basal/myoepithelial cells of sweat glands. Out of 20 benign adnexal tumors, 13 (65%) showed strong (score 3) p63 expression; the remaining seven (35%) cases had score 2. All primary cutaneous carcinomas, including adenocarcinomas, expressed p63. In contrast, none of the metastatic adenocarcinomas to the skin was positive for p63 (P<0.001). Based on our findings, analysis of p63 expression may help in the differential diagnosis of primary vs metastatic cutaneous adenocarcinomas.

The transactivating isoforms of p63 are overexpressed in high-grade follicular lymphomas independent of the occurrence ofp63 gene amplification

p63 is a p53-related gene mapping to 3q28 that codes for multiple mRNA transcripts with (TA-p63) or without (DeltaN-p63) transactivating effects on genes that promote cell differentiation and apoptosis. We analysed p63 alterations by immunohistochemistry, quantitative real-time RT-PCR and FISH in a series of 45 follicular lymphomas (FL). None of the tumours showed immunoreactivity for the p40 antibody, which recognizes only the truncated isoforms of p63, or DeltaN-p63 mRNA expression. Immunoreactivity for the 4A4 antibody, which recognizes both the transactivating and the truncated p63 isoforms, was found in 5 +/- 5.5%, 6.85 +/- 4.88% and 33.2 +/- 22.31% of grade I, II and III FL cells, respectively (p < 0.0001). Quantitative RT-PCR analysis showed that all cases but one had TA-p63 mRNA levels higher than non-neoplastic lymphocytes, and that TA-p63 mRNA expression correlated significantly (r = 0.9194, p < 0.0001) with the prevalence of p63 immunoreactivity. FISH extra signals for the p63 gene were found in seven (23.3%) of the 30 cases analysed (0/6 grade I, 2/15 grade II and 5/9 grade III; p = 0.01937). Further hybridizations showed a pattern highly suggestive of chromosome 3 polysomy in six cases. One of these cases also bore extra copies of the p63 and bcl-6 genes. Co-localization of p63 and IgH signals was found in one case. No association between the prevalence of p63 immunoreactivity and extra p63 gene signals was detectable when the cases were dichotomized according to a p63 immunoreactivity threshold of 10%. Our data suggest that TA-p63 is overexpressed in high-grade FL, possibly independent of the occurrence of gene abnormalities, and that it may be involved in the highly complex mechanism of regulation of apoptosis of FL cells.

Maintenance of cell type diversification in the human breast

Recent genome-wide expression analysis of breast cancer has brought new life to the classical idea of tumors as caricatures of the process of tissue renewal as envisioned by Pierce and Speers (Cancer Res 1988;48:1996-2004) more than a decade ago. The search for a cancer founder cell or different cancer founder cells is only possible if a hierarchy of differentiation has been established for the particular tissue in question. In the human breast, the luminal epithelial and myoepithelial lineages have been characterized extensively in situ by increasingly elaborate panel of markers, and methods to isolate, culture, and clone different subpopulations have improved dramatically. Comparisons have been made with the mouse mammary gland in physiological three-dimensional culture assays of morphogenesis, and the plasticity of breast epithelial cells has been challenged by immortalization and transformation. As a result of these efforts, several candidate progenitor cells have been proposed independently of each other, and some of their features have been compared. This research has all been done to better understand breast tissue homeostasis, cell-type diversification in general and breast cancer evolution in particular. The present review discusses the current approaches to address these issues and the measures taken to unravel and maintain cell type diversification for further investigation.

Comparison of p63 and p73 expression in benign and malignant salivary gland lesions

BACKGROUND

The p63 and p73 genes are members of the p53 family and play an important role in stem cell identity and cellular differentiation and are expressed in basal and myoepithelial cells. In this study, we examined the expression of p63 and p73 in 50 various benign salivary gland lesions and 45 malignant salivary gland tumors.

METHODS

The 95 salivary gland tumors were selected from the archives of the Department of Pathology and Laboratory Medicine at the Hospital of the University of Pennsylvania. Sectioned formalin-fixed paraffin-embedded tissue cut at 3 mum was immunostained with antibodies that recognize all isozymes of p63 and p73 and evaluated with respect to percentage of positive cells and localization.

RESULTS

In benign lesions, p63 and p73 nuclear reactivity was seen in 46 (92%) of 50 and 47 (94%) of 50 cases, respectively. In malignant tumors, p63 and p73 were seen in 34 (76%) of 45 and 40 (89%) of 45 cases, respectively. A significant difference between p63 and p73 positivity was only seen in adenoid cystic carcinomas (p = .006). Also, p73 was found in tumors with minimal basal/myoepithelial differentiation.

CONCLUSIONS

Hence, p63 and p73 expression is retained in both benign and malignant salivary gland tumors with basaloid or myoepithelial differentiation. Hence, p63 seems to be a more specific marker of myoepithelial differentiation than p73.

[P63 protein in the diagnosis of breast tubular carcinoma]

AIMS

To study and compare the expression of p63 protein and smooth muscle actin in breast tubular carcinoma (TC) and its main differential diagnoses, radial scar (RS)/complex sclerosing lesion (CSL).

MATERIALS AND METHODS

Immunohistochemistry techniques were used to search for p63 protein and smooth muscle actin antibodies in 10 patients with TC and fifteen with RS/CSL.

RESULTS

Myoepythelial cells were diffusely positive for both actin and p63 protein with a cytoplasmic (actin) or nuclear (p63) pattern in all patients with RS/CSL. Inversely, all TC were negative for p63. Actin antibodies failed to label myoepithelial cells in TC, but both vessels and stromal myoblasts were actin-positive, creating difficult interpretation situations. By contrast, p63 was consistently negative in these structures.

CONCLUSION

For the differential diagnosis between TG and CR/LSC, smooth muscle actin and p63 protein demonstrate equivalent sensitivity for the detection of myoepithelial cells. However, the nuclear pattern of p63 labeling gives a "cleaner" stain. In addition, p63 enables distinction between myoepithelial cells and myofibroblasts/vascular smooth muscle cells, offering increased specificity.

Expression of ATM, p53, and the MRE11-Rad50-NBS1 complex in myoepithelial cells from benign and malignant proliferations of the breast

AIMS

To analyse the expression of proteins involved in DNA double strand break detection and repair in the luminal and myoepithelial compartments of benign breast lesions and malignant breast tumours with myoepithelial differentiation.

METHODS

Expression of the ataxia telangiectasia (ATM) and p53 proteins was immunohistochemically evaluated in 18 benign and malignant myoepithelial tumours of the breast. Fifteen benign breast lesions with prominent myoepithelial compartment were also evaluated for these proteins, in addition to those in the MRE11-Rad50-NBS1 (MRN) complex, and the expression profiles were compared with those seen in eight independent non-cancer (normal breast) samples and in the surrounding normal tissues of the benign and malignant tumours examined.

RESULTS

ATM expression was higher in the myoepithelial compartment of three of 15 benign breast lesions and lower in the luminal compartment of eight of these lesions compared with that found in the corresponding normal tissue compartments. Malignant myoepithelial tumours overexpressed ATM in one of 18 cases. p53 was consistently negative in benign lesions and was overexpressed in eight of 18 malignant tumours. In benign breast lesions, expression of the MRN complex was significantly more reduced in myoepithelial cells (up to 73%) than in luminal cells (up to 40%) (p=0.0005).

CONCLUSIONS

Malignant myoepithelial tumours rarely overexpress ATM but are frequently positive for p53. In benign breast lesions, expression of the MRN complex was more frequently reduced in the myoepithelial than in the luminal epithelial compartment, suggesting different DNA repair capabilities in these two cell types.

p63 Expression in Breast Cancer

p63, a member of the p53 gene family, is involved in cellular differentiation and is expressed in the nuclei of myoepithelial cells of normal breast ducts and lobules. Although p63 has been reported in metaplastic carcinomas of the breast, its expression pattern in breast carcinomas and sarcomas has not been fully characterized, and its potential diagnostic utility has not been defined. In this study, we determined p63 expression in a large number of breast carcinomas, including metaplastic carcinomas, and in Phyllodes tumors and sarcomas. We examined 189 invasive breast carcinomas, including 15 metaplastic carcinomas, as well as 10 Phyllodes tumors, and 5 pure sarcomas of the breast for pattern and intensity of p63 staining using an anti-p63 antibody (clone 4A4, Neomarkers). p63 was strongly expressed in 13 of 15 metaplastic carcinomas (86.7%). p63 was positive in all the metaplastic carcinomas with spindle cell and/or squamous differentiation (12 of 12), and in 1 of 3 metaplastic carcinomas with cartilage foci. In stark contrast, only 1 of 174 (0.6%) nonmetaplastic invasive carcinomas was positive for p63. All Phyllodes tumors and sarcomas were consistently negative for p63 expression. The sensitivity and specificity of p63 as a diagnostic marker for metaplastic carcinoma was 86.7% and 99.4%, respectively. We propose the inclusion of p63 as part of the diagnostic workup of challenging spindle cell tumors of the breast as a highly specific marker for metaplastic carcinomas.

P63-driven nuclear accumulation of beta-catenin is not a frequent event in human neoplasms

deltaN-p63 isoforms may act as oncogenes owing to their ability to bind to p53-reporter genes without inciting their transcription, thus blocking the p53-driven cell cycle arrest and apoptosis. A novel mechanism linking p63 and Wnt pathways has recently been proposed. Briefly, in vitro studies using squamous cell carcinoma cell lines have suggested that deltaN-p63 may block the phosphorylation of beta-catenin, leading to its nuclear accumulation and triggering beta-catenin-responsive transcription of genes related to proliferation and oncogenic biological behavior. To test this new mechanism, the coexpression of deltaN-p63 and beta-catenin was evaluated in a large cohort of human neoplasms. Two serial sections of TARP-4 multi-tumor tissue microarray, composed of 51 normal tissue cores and 400 human neoplasms [breast (n = 75), colon (n = 75), lung (n = 75), prostate (n = 75) and ovary (n = 50) neoplasms, melanoma (n = 25), and glioblastoma (n = 25)] were subjected to immunohistochemistry with deltaN-p63 and beta-catenin monoclonal antibodies. p63 nuclear expression and beta-catenin membranous, cytoplasmic, membranous + cytoplasmic, and nuclear localization were evaluated. deltaN-p63 expression and beta-catenin nuclear localization were found in 92.6% and 0% of squamous cell carcinomas, 8.9% and 0% of breast carcinomas, 13.8% and 0% of lung adenocarcinomas, 1.4% and 23.2% of colon adenocarcinomas, 0% and 4.8% of prostate adenocarcinomas, 11.1% and 5% of ovary carcinomas, 9.0% and 9.1% of malignant melanomas, and 12.5% and 40.0% of glioblastomas, respectively. No statistically significant association between deltaN-p63 and nuclear beta-catenin expression was found for all tumors. At variance with squamous cell carcinoma cell lines, p63-driven nuclear accumulation of beta-catenin is an unusual phenomenon in human neoplasms. Caution should be exercised when translating the results of studies performed on cell lines to human neoplasms.

CDX-2 Homeobox Gene Product Expression in Neuroendocrine Tumors

CDX-2 is a homeobox gene product essential for intestinal development and differentiation. It can be used as a specific marker of colorectal adenocarcinomas and other tumors with intestinal differentiation, but little is known about its expression in endocrine and neuroendocrine (NE) cells and NE primary and metastatic tumors. Using the Cdx-2-88 monoclonal antibody, we evaluated CDX-2 expression in routine samples of 20 normal endocrine/NE tissues and of 299 samples of well-differentiated NE tumors (WDNET) and high-grade NE carcinomas (NEC) from different sites. For 17 cases, we examined primary and corresponding metastatic lesions. We also examined 8 cytologic samples of liver metastases derived from 4 ileal WDNETs, 1 lung WDNET, and 3 pancreatic endocrine tumors. CDX-2 mRNA expression with RT-PCR technique on frozen material was evaluated in 5 WDNETs. CDX-2 was expressed in normal NE cells of the intestine and gastric fundus. High CDX-2 expression was seen in all ileal and appendiceal WDNET, while low levels were seen in WDNETs from stomach, duodenum, and rectum; no reactivity was seen in other WDNETs. Low levels of CDX-2 expression were seen in one third of nonfunctioning pancreatic WDNET where it was more frequently observed in cases with metastatic disease (P = 0.002). CDX-2 was identified in all cytologic specimens of metastatic ileal WDNETs. CDX-2 mRNA analysis confirmed immunohistochemical results. CDX-2 was expressed at high levels in 81% of intestinal NEC. Unexpectedly, variable levels of expression of CDX-2 were seen also in 39% of NEC of other sites, without any relation with the site of origin. This reactivity frequently overlapped TTF-1 expression, suggesting deregulated expression of homeobox genes in NEC. The restricted pattern of CDX-2 expression may have diagnostic value in the identification of the primary site of a metastatic WDNET. Conversely, a limited diagnostic role is suggested for CDX-2 in NEC because of its frequent expression in nongastrointestinal tumors.

Modulation of notch signaling elicits signature tumors and inhibits hras1-induced oncogenesis in the mouse mammary epithelium

Deregulation of Notch signaling, which normally affects a broad spectrum of cell fates, has been implicated in various neoplastic conditions. Here we describe a transgenic mouse model, which demonstrates that expression of a constitutively active form of the Notch1 receptor in the mammary epithelium induces the rapid development of pregnancy/lactation-dependent neoplasms that consistently exhibit a characteristic histopathological pattern. These signature tumors retain the ability to respond to apoptotic stimuli and regress on initiation of mammary gland involution, but eventually appear to progress in subsequent pregnancies to nonregressing malignant adenocarcinomas. Additionally, we present evidence indicating that cyclin D1 is an in vivo target of Notch signals in the mammary glands and demonstrate that we can effectively inhibit Hras1-driven, cyclin D1-dependent mammary oncogenesis by transgenic expression of the Notch antagonist Deltex.

Current Practical Applications of Diagnostic Immunohistochemistry in Breast Pathology

In recent years, immunohistochemistry has assumed an increasingly prominent role in diagnostic breast pathology. Immunohistochemistry is now frequently used in the evaluation of many epithelial proliferations of the breast. Common applications include the use of myoepithelial markers to evaluate for stromal invasion, E-cadherin to distinguish between ductal and lobular neoplasia, high molecular weight cytokeratins to differentiate usual ductal hyperplasia from ductal carcinoma in situ, immunohistochemical profiles to characterize site of origin of metastatic carcinomas, and cytokeratin stains to detect metastases in sentinel lymph nodes. Recent advances, practical considerations, and potential pitfalls in the use of immunohistochemistry in these five diagnostic categories are discussed herein.

Critical role of p63 in the development of a normal esophageal and tracheobronchial epithelium

The trachea and esophagus originate from the foregut endoderm during early embryonic development. Their epithelia undergo a series of changes involving the differentiation of stem cells into unique cell types and ultimately forming the mature epithelia. In this study, we monitored the expression of p63 in the esophagus and the trachea during development and examined in detail morphogenesis in p63(-/-) mice. At embryonic day 15.5 (E15.5), the esophageal and tracheobronchial epithelia contain two to three layers of cells; however, only the progenitor cells express p63. These progenitor cells differentiate first into ciliated cells (p63(-)/beta-tubulin IV(+)) and after birth into mature basal cells (p63(+)/K14(+)/K5(+)/BS-I-B4(+)). In the adult pseudostratified, columnar tracheal epithelium, K14(+)/K5(+)/BS-I-B4(+) basal cells stain most intensely for p63, whereas ciliated and mucosecretory cells are negative. In stratified squamous esophageal epithelium and during squamous metaplasia in the trachea, cells in the basal layer stain strongest for p63, whereas p63 staining declines progressively in transient amplifying and squamous differentiated cells. Generally, p63 expression is restricted to human squamous cell carcinomas, and adenocarcinomas and Barrett's metaplasia do not stain for p63. Examination of morphogenesis in newborn p63(-/-) mice showed an abnormal persistence of ciliated cells in the esophagus. Significantly, in both tissues, lack of p63 expression results in the development of a highly ordered, columnar ciliated epithelium deficient in basal cells. These observations indicate that p63 plays a critical role in the development of normal esophageal and tracheobronchial epithelia and appears to control the commitment of early stem cells into basal cell progeny and the maintenance of basal cells.

Telomerase expression and proliferative activity suggest a stem cell role for thyroid solid cell nests

Solid cell nests of the human thyroid gland are composed of main cells and C cells. In order to investigate the putative stem cell nature of the role for solid cell nests, we evaluated the histological features, and the immunohistochemical expression of p63, bcl-2, telomerase catalytic subunit, and two proliferative markers (Ki-67 and minichromosome maintenance protein 2), in a series of 24 cases of solid cell nests. Proliferative indices were determined in (a) solid cell nests, (b) thyroid follicular cells in the vicinity of solid cell nests within a low-power field, and (c) distant thyroid tissue, at a distance of at least three low-power fields from solid cell nests. In 15 cases of solid cell nests (62.5%), mixed follicles were observed; papillary formations were observed in four cases (16.6%), and ciliated cells were observed in the lining of microcysts associated with two cases (8.3%). Salivary gland-type tissue, cartilage islands, adipose and fibrous tissues, and small nerves were also associated with some cases of solid cell nests. We observed that the main cells of the solid cell nests express consistently telomerase, although at lower levels than p63, and show strong cytoplasmic immunoreactivity for bcl-2, which is associated with an increased differentiation potential. We also observed that despite their relative low proliferative index, main cells of the solid cell nests display higher proliferation than follicular cells in the vicinity and follicular cells in more distant thyroid tissue. We conclude that main cells of the solid cell nests apparently harbor the minimal properties of a stem cell phenotype (capacity for both self-renewal, conferred by telomerase activity, and differentiation to one or more than one type of specialized cells, given by the high expression of p63 and bcl-2) and may thus represent a pool of stem cells of the adult thyroid.

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.

Myoepithelial markers are expressed in at least 29% of oestrogen receptor negative invasive breast carcinoma

Around 20% of invasive breast carcinoma are oestrogen receptor alpha (ER) negative. Theoretically, this negativity could be either due to the result of downregulation of ER expression in the tumour cells, or the result of the tumour being derived from or differentiating towards cells which normally lack that expression. Normal basal, including myoepithelial, cells of the breast are ERnegative. CD10, smooth muscle actin and S100 are markers of these basal cells that can be used for their demonstration in routinely processed sections. This study was aimed at comparing the incidence of positivity for three myoepithelial markers in ER-negative and ER-positive invasive breast carcinoma. We have examined sections of 117 cases of breast carcinoma, including 77 ER-negative and 40 ER-positive cases, for the expression of CD10, smooth muscle actin and S100, using the avidin-biotin complex immunoperoxidase technique. A tumour was considered positive if more than 10% of the tumour cells were positively stained. In all, 36 (47%) ER-negative tumours were positive for one or more of these myoepithelial markers. The percentage of positively stained tumour cells varied between 30 and 100%. Of the 40 ER-positive tumours, only three (8%) were positive; two for S100 and one for actin, with none being positive for CD10. If cases stained only with S100 are excluded, as some of these may represent luminal differentiation, definite myoepithelial differentiation seems to be present in 29% (22/77) of ER-negative tumours as compared with 2.5% (1/40) of ER-positive tumours; a difference which is highly significant (P<0.001). It is suggested that at least 29% of ER-negative invasive breast carcinomas may be derived from or differentiating along the direction of basal nonconventional luminal epithelial breast cells that normally lack the expression of ER but totally or partially express various myoepithelial markers. Such tumours might need a different therapeutic approach.

Association of increased estrogen receptor beta2 expression with parity-induced alterations in the rat mammary gland

In this study, we investigated the cellular and molecular events involved in parity-related alterations in mammary gland (MG) proliferation and differentiation. Rat MGs were removed on day 9 of either first (nulliparous), second (primiparous) or third (multiparous) pregnancy. Expression of steroid hormone receptors along with cellular biomarkers of proliferation and differentiation were quantified in all MG tissue compartments by immunohistochemistry. Wnt-4 (a Wingless-like morphogenic gene involved in MG development), ERbeta and ERbeta2 mRNA were evaluated by RT-PCR analysis. Serum levels of mammotrophic hormones were measured. In comparison to nulliparous and primiparous rats, multiparous animals exhibited decreased luminal cell proliferation and PR levels, whereas alpha-lactalbumin, ERalpha, ERbeta and ERbeta2 expression were increased. In myoepithelial cells, while parity induced a decrease in proliferative activity, subsequent pregnancies and lactations lead to an increased state of differentiation. Our results showed that at least two periods of pregnancy and lactation were necessary to modify the studied parameters. The lower proliferative activity and higher differentiation state of the multiparous MG are associated with both a decreased PR expression and increased ERalpha and ERbeta expression. Since ERbeta and/or ERbeta2 isoform expression was related to parity history, results suggest that the decreased proliferative activity and PR expression observed in the MG of multiparous animals may be associated with overexpression of ERbeta and/or the ERbeta2 isoform, thereby antagonizing the proliferative effects associated with ERalpha.

Alterations of beta-catenin pathway in non-melanoma skin tumors: loss of alpha-ABC nuclear reactivity correlates with the presence of beta-catenin gene mutation

To determine the role of beta-catenin pathway in human skin carcinogenesis, 135 non-melanoma skin tumors were analyzed for beta-catenin expression and gene mutations. Intense nucleo-cytoplasmic immunoreactivity for C terminus beta-catenin antibodies was observed in all pilomatricomas and in single cases of trichoepithelioma and squamous cell carcinoma showing peculiar signs of matrical differentiation. Moderate increase of beta-catenin nuclear staining was detected in a significant proportion of basal cell carcinomas, Bowen disease, spiroadenomas, and occasionally also in squamous cell carcinomas, but in these neoplasms only a limited fraction of tumor cells accumulated beta-catenin. Molecular analysis revealed that beta-catenin gene mutations are a peculiar feature of skin tumors with matrical differentiation and correlate with a pattern of intense and diffuse beta-catenin nuclear expression. In contrast, adenomatous polyposis coli (APC) and AXIN2 mutations were not involved in skin tumorigenesis. Analysis of Wnt pathway revealed that TCF-1 and MITF-M were selectively induced in the tumor types harboring beta-catenin mutations, indicating that a Wnt/beta-catenin pathway involving TCF-1 and MITF-M is activated in these tumors. Interestingly, high expression levels of TCF-3 were found in basal cell carcinomas and spiroadenomas. TCF-3 is reported to act as a negative modulator of beta-catenin degradation pathway. Thus, the moderate increase of beta-catenin nuclear staining detected in these tumor types might, at least in part, be due to a TCF-3-dependent mechanism. Finally, we found that the presence of beta-catenin mutations significantly correlated with loss of nuclear immunoreactivity for an antibody raised against the N terminus of beta-catenin (alphaABC). Thus, a combined analysis with C terminus-beta-catenin antibodies and alphaABC Ab may represent a powerful investigative approach for the detection of beta-catenin structural alterations.

Cutaneous myoepithelioma: a clinicopathologic and immunohistochemical study of 14 cases

Analogous to mixed tumors of salivary glands (" pleomorphic adenomas" ), cutaneous mixed tumors (" chondroid syringomas" ) contain a ductal (epithelial) component and a variably prominent myoepithelial component. Tumors showing purely myoepithelial differentiation (myoepitheliomas) have only recently been recognized to arise in the dermis, and to date very few cases have been described. To characterize these tumors further, 14 cutaneous myoepithelial tumors were retrieved from the authors' consult files. Eleven patients were male and 3 were female; their median age was 22.5 years (range, 10 to 63 years), and 7 patients were between 10 and 20 years old. Tumor size ranged from 0.5 to 2.5 cm (mean, 1.1 cm). Most tumors arose on the extremities: 6 on the upper limbs, 6 on the lower limbs, and 1 each on the back and nose. Ten tumors were limited to the dermis, and 5 also extended into superficial subcutis. Thirteen tumors were myoepitheliomas (lacking ductal differentiation), and 1 tumor was a myoepithelial carcinoma (exhibiting severe cytological atypia and a high mitotic rate). Histologically, 7 tumors were solid, composed of ovoid to spindled, histiocytoid, or epithelioid cells with no significant stroma, and 7 were predominantly lobulated, with cords or nests of epithelioid, plasmacytoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. One tumor was composed solely of plasmacytoid (hyaline) cells, and 1 exhibited extensive adipocytic differentiation. Among the 13 myoepitheliomas, mitoses ranged from 0 to 6 per 10 high-power fields (HPFs) (mean, 1.5); 8 tumors contained no mitoses. The myoepithelial carcinoma had 39 mitoses per 10 HPFs. By immunohistochemistry, all cases were reactive for epithelial markers (keratins and/or epithelial membrane antigen [EMA]); 13 of 14 (93%) expressed S-100 protein, 10 of 11 expressed (91%) calponin, 11 of 14 (79%) expressed EMA, 9 of 14 (64%) expressed keratins, 8 of 14 (57%) expressed smooth muscle actin, 7 of 14 (50%) expressed glial fibrillary acidic protein, 3 of 11 (27%) expressed p63, and 1 of 6 (17%) expressed desmin. All 5 cases without keratin staining were diffusely positive for EMA, and all of these cases showed a solid growth pattern. Follow-up was available for 8 patients (median follow-up, 40 months; range, 6 months to 9 years); 3 tumors (38%) recurred locally, and 1 tumor (13%) also metastasized to the lymph nodes. The case that resulted in recurrence and metastasis had the highest mitotic rate (6 per 10 HPFs) of the cytologically benign tumors. Follow-up information was not available for the myoepithelial carcinoma. This study suggests that approximately 50% of cutaneous myoepitheliomas are distinctive lesions composed of a solid proliferation of cells with abundant eosinophilic syncytial cytoplasm, which often lack immunostaining for keratin, whereas the remainder demonstrate focally reticular architecture and myxoid stroma or plasmacytoid cells, similar to their counterparts in salivary gland and soft tissue. Whereas most cutaneous myoepitheliomas behave in a benign fashion, there is apparently a significant risk for local recurrence but a low metastatic potential.

Histopathology of primary breast cancer 2003

The histologic and immunophenotypic characterisation of primary breast carcinoma admittedly is a finite and imperfect source of information for an ideal prognostic and predictive evaluation, and for tailoring the most appropriate adjuvant intervention for each individual patient. Complementary data coming from molecular profiling assays hopefully will significantly add to our current skills in predicting the future. Undoubtedly, however, the traditional morphological and immunohistochemical features are the faithful mirror of the differential expression of hundreds of genes, which may therefore be safely and consistently evaluated even by simple histologic examination and immunohistochemical assays. What is nowadays especially needed is to improve our skills and technical means for assuring accuracy and reproducibility of the morphological and immunohistochemical findings.

Isolation and characterization of functional mammary gland stem cells

Significant advances in the stem-cell biology of several tissues, including the mammary gland, have occurred over the past several years. Recent progress on stem-cell fate determination, molecular markers, signalling pathways and niche interactions in haematopoietic, neuronal and muscle tissue may provide parallel insight into the biology of mammary epithelial stem cells. Taking advantage of approaches similar to those employed to isolate and characterize haematopoietic and epidermal stem cells, we have identified a mammary epithelial cell population with several stem/progenitor cell qualities. In this article, we review some recent data on mammary epithelial stem/progenitor cells in genetically engineered mouse models. We also discuss several potential molecular markers, including stem-cell antigen-1 (Sca-1), which may be useful for both the isolation of functional mammary epithelial stem/progenitor cells and the analysis of tumour aetiology and phenotype in genetically engineered mouse models. In different transgenic mammary tumour models, Sca-1 expression levels, as well as several other putative markers of progenitors including keratin-6, possess dramatically altered expression profiles. These data suggest that the heterogeneity of mouse models of breast cancer may partially reflect the selection or expansion of different progenitors.

Salivary-type neoplasms of the breast and lung

Salivary-type tumors occur in multiple sites in the human body, likely related to a basic structural homology between exocrine glands in these different anatomic areas. This paper reviews these salivary gland tumor types in breast tissue and lung. Salivary-type tumors of both breast and lung are relatively uncommon in comparison to their salivary gland counterparts. This may be attributable in part to lack of familiarity with these tumors in extra-salivary sites, and in part to histologic overlap with other primary and metastatic tumor types. Recognition of these entities is improving as the clinical and pathologic features are better delineated, and tumors are more accurately classified. Prediction of malignant behavior is not always possible in these unusual sites. In some instances, such as adenoid cystic carcinoma, behavior is known to differ considerably from that of analogous primary salivary gland tumors and in other instances there are simply too few reported cases to allow for adequate prognostication. In fact, more recent papers discuss the need to consider a spectrum encompassing benign and malignant lesions, in both breast and lung. Of course, some entities show clear-cut evidence of malignancy with documented potential for metastasis, others show bland features and well-reported benign behavior, and the less well-defined entities reside between these two extremes. The molecular pathology of salivary gland tumors has been reasonably well investigated in that location; however; there are few molecular studies devoted to salivary-type tumors of the breast and lung. This represents a potential area for future growth in further clarifying these tumors and their behavior.

The role of p63 and deltaNp63 (p40) protein expression and gene amplification in esophageal carcinogenesis

p63, a member of the p53 gene family, is known to encode functionally antagonistic protein isoforms. Although transactivating protein isoforms display p53-like functions, deltaNp63 isoforms act toward p53 in a dominant negative way. Using immunohistochemistry, we examined the expression of pan-p63 and deltaNp63 in 50 esophageal squamous cell carcinomas (SCCs) as well as in squamous low-grade intraepithelial neoplasias (S-LGINs; n = 4) and high-grade intraepithelial neoplasias (S-HGINs; n = 18). Additionally, 50 esophageal adenocarcinomas (ADCs) that arose in Barrett's esophagus (BE) as well as adjacent specialized metaplastic epithelium (SE; n = 41), low-grade intraepithelial neoplasias (B-LGINs; n = 27), and high-grade intraepithelial neoplasias (B-HGINs; n = 21) in BE were investigated. Furthermore, p63 gene amplification was determined by fluorescent differential polymerase chain reaction in a subset of 10 SCCs and 10 ADCs. Whereas in normal esophageal epithelium, expression of pan-p63 is invariably restricted to the basal cell layer, in 100% of S-LGINs, 94.4% of S-HGINs, and 88.0% of SCCs, expression of p63 was found in >75% of the cells. Concerning BE, only in a small subset of SEs (7.3%), B-LGINs (14.8%), B-HGINs (14.3%) and ADCs (16.0%) was a weak p63 protein expression (<10% positive cells) detectable, whereas the rest of the samples were completely negative. Expression of deltaNp63 was identical to expression of pan-p63 in the vast majority of samples. p63 gene amplification was found in 2 of 10 (20.0%) investigated SCCs and in 1 of 10 (10.0%) ADCs. In summary, strong expression of p63, especially its deltaNp63 isoforms, is a frequent finding in esophageal precancerous and cancerous squamous lesions, whereas this is not the case in carcinogenesis of BE. p63 gene amplification is an infrequent finding in esophageal SCCs and ADCs and does not correlate with protein overexpression.

Myoepithelial tumors of soft tissue: a clinicopathologic and immunohistochemical study of 101 cases with evaluation of prognostic parameters

Myoepitheliomas and mixed tumors were only recently recognized to occur primarily in soft tissue, and only small case numbers have been described. To characterize these tumors further and to evaluate prognostic parameters, 101 myoepithelial tumors of soft tissue were retrieved from the authors' consult files. Hematoxylin and eosin sections were reexamined, immunohistochemistry was performed, and clinical details were obtained from referring physicians. Fifty-three patients were male and 48 female (mean age 38 years; range 3-83 years). Tumor size ranged from 0.7 to 20 cm (mean 4.7 cm). Most tumors arose in the extremities and limb girdles: 41 in the lower limbs, 35 in the upper limbs, 15 in the head and neck, and 10 in the trunk. Fifty-four tumors were situated in subcutis and 37 in deep soft tissue (depth unstated in 10). Most cases were grossly well circumscribed; 43 showed microscopically infiltrative margins. Histologically, most tumors were lobulated, composed of cords or nests of epithelioid, ovoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. Eight cases showed a predominantly solid proliferation of spindled or plasmacytoid cells; 17 demonstrated ductular differentiation (mixed tumors). Cartilage was present in 6 cases, 6 contained bone, and 4 others contained both. Mitoses ranged from 0 to 68 per 10 high power fields (mean 4.7 per 10 high power fields). Tumors with benign cytomorphology or mild cytologic atypia (low-grade) were classified as myoepithelioma or mixed tumor, whereas tumors with moderate to severe atypia (high-grade) were classified as myoepithelial carcinoma (epithelioid or spindled cells with vesicular or coarse chromatin, prominent, often large nucleoli, or nuclear pleomorphism) or malignant mixed tumor (cytologically malignant cartilage or bone). Sixty-one cases were myoepitheliomas or mixed tumors, and 40 were myoepithelial carcinomas or malignant mixed tumors. By immunohistochemistry, all cases with available material were reactive for epithelial markers (keratins and/or epithelial membrane antigen): 90 of 97 (93%) expressed keratins (most often AE1/AE3 or PAN-K), 84 of 97 (87%) S-100 protein, 44 of 51 (86%) calponin, 52 of 83 (63%) epithelial membrane antigen, 40 of 87 (46%) glial fibrillary acidic protein, 27 of 75 (36%) smooth muscle actin, 15 of 66 (23%) p63, and 7 of 51 (14%) desmin. Follow-up was available for 64 patients. Among 33 cases with benign or low-grade cytology (mean follow-up 36 months; range 4-168 months), 6 recurred locally (18%) and none metastasized. No clinical or histologic features correlated with recurrence. Among 31 cytologically malignant cases (mean follow-up 50 months; range 4-252 months), 13 recurred locally (42%) and 10 metastasized (32%); so far, 4 patients have died of metastatic tumor. This study expands the spectrum of myoepithelial tumors of soft tissue to include myoepithelial carcinomas and malignant mixed tumors, which pursue an aggressive clinical course. Although the majority of morphologically benign or low-grade myoepithelial neoplasms of soft tissue behave in a benign fashion, there is an approximate 20% risk for local recurrence.

Basal cells of second trimester fetal breasts: immunohistochemical study of myoepithelial precursors

The molecular characterization of human mammary myoepithelial cells is incomplete, hindering our understanding of its importance in breast physiology and pathology. Because data on the precursors of this cell lineage remain scarce and often contradictory, basal epithelial cells of second trimester fetal breasts were studied by light microscopy (LM) and immunohistochemistry (IHC). Up to 20 wk of gestational age, the mammary rudiments only comprised roundish primary outgrowths, "primary buds," more likely to represent immature nipples than true mammary tissue. At 21 wk secondary outgrowths, "projections," extended from enlarged primary buds into well-vascularized layers of dense mesenchyme. Basal projection cells had a partial myoepithelial-like phenotype: they reacted with CD29, CD49f, CD104, keratin 14, vimentin, S100beta protein, and p63; furthermore, many became positive for keratin 17, alpha-smooth muscle actin, and CD10 (but not for keratin 19) between wk 21 and 25. The continuous basement membrane associated with the fetal mammary rudiments was strongly positive for collagens type IV and VII, and for laminin 5. Consistently strong and basally polarized staining for hemidesmosomal components suggested that although incompletely differentiated, most second trimester myoepithelial precursors might already mediate local epithelial-mesenchymal interactions, i.e., complex signaling pathways which are crucial for both orderly growth during development and maintenance of homeostasis during adult life. Because they are likely implicated in the phenomenon of menstrual cycle-related growth spurts in the adult resting breast, the strategically positioned cells of the myoepithelial lineage might constitute critical protagonists in defective epithelial-mesenchymal signaling associated with cancer progression.

Aberrant P-cadherin expression: is it associated with estrogen-independent growth in breast cancer?

Breast carcinomas represent a heterogeneous group of tumors, with a diverse biologic behavior, outcome, and response to therapy. Recent studies have demonstrated that alterations in the expression of adhesion molecules in cancer cells are related to aggressiveness and poor prognosis. The aim of our study was to investigate the expression of P-cadherin in breast carcinomas and correlate it with estrogen receptor (ER) status. We selected 73 ductal carcinomas in situ (DCIS) and 149 invasive carcinomas of the breast, and assessed the expression of P-cadherin as well as other biologic markers. P-cadherin expression showed a strong inverse correlation with ER expression in both types of breast carcinoma (in situ and invasive). P-cadherin-positive and ER-negative tumors were related to a higher histologic grade, a high proliferation rate, and expression of c-erbB-2. We demonstrated that P-cadherin identifies a subgroup of breast carcinomas that lacks ER expression, and correlates with higher proliferation rates and other predictors of aggressive behavior. We believe that these tumors represent an advanced step in cancer progression, and our data support the hypothesis that an estrogen-independent pathway regulates P-cadherin expression.

p63: a novel myoepithelial cell marker in canine mammary tissues

Several immunohistochemical markers have been used to demonstrate the presence of myoepithelial cells in order to determine their role in the histogenesis of mammary tumors. p63, a recently characterized p53 homologue, is consistently expressed in myoepithelial cells of the human breast; however, no assessment of its immunoreactivity has been reported so far in canine mammary tissues. We investigated p63 immunohistochemical expression, as a novel myoepithelial cell nuclear marker, in 81 samples of normal (n = 2), hyperplastic (n = 11), and neoplastic (n = 68) canine mammary tissues. Myoepithelial phenotype was confirmed by using complementary monoclonal antibodies: alpha-smooth muscle actin, cytokeratin 14, cytokeratin AE1/AE3, and vimentin. p63 expression was observed in 91.4% (74/81) of the samples evaluated. Normal mammary glands, mammary hyperplasias, and benign tumors showed 100% immunoreactivity, with p63 expression restricted to myoepithelial cell nuclei. In general, benign mixed tumors showed a basal cell compartment immunoreactive to p63, with a gradual decrease of its expression during myoepithelial transformation. p63 expression was found in 72% of malignant tumors, allowing myoepithelial or basal cell identification in spindle-cell carcinomas (2/2), tubulopapillary carcinomas (8/9), solid carcinomas (7/10), and carcinosarcomas (1/3). The osteosarcoma analyzed was p63 negative. In our series, stromal components were consistently nonreactive to p63. In conclusion, the present study reveals p63 as a sensitive and highly specific marker of myoepithelial cells in canine mammary tissues, and the authors suggest p63 as an additional marker for defining myoepithelial histogenesis.

Salivary gland-like tumours of the breast: surgical and molecular pathology

Breast glands and salivary glands are tubulo-acinar exocrine glands that can manifest as tumours with similar morphological features, but that differ in incidence and clinical behaviour depending on whether they are primary in breast or salivary glands. Salivary gland-like tumours of the breast are of two types: tumours with myoepithelial differentiation and those devoid of myoepithelial differentiation. The first and more numerous group comprises a spectrum of lesions ranging from "bona fide" benign (such as benign myoepithelioma and pleomorphic adenoma), to low grade malignant (such as adenoid cystic carcinoma, low grade adenosquamous carcinoma, and adenomyoepithelioma), to high grade malignant lesions (malignant myoepithelioma). The second group comprises lesions that have only recently been recognised, such as acinic cell carcinoma, oncocytic carcinoma of the breast, and the rare mucoepidermoid carcinoma.

Distribution of p63, a novel myoepithelial marker, in fine-needle aspiration biopsies of the breast: an analysis of 82 samples

BACKGROUND

The presence of myoepithelial cells (MECs) in fine-needle aspiration biopsies (FNAB) of the breast constitute an important criterion used to diagnose benign breast lesions. However, MECs sometimes have a distorted cytomorphology, and most of the previously evaluated myoepithelial markers do not have satisfactory sensitivity and specificity. p63, a recently characterized p53 homolog, is a nuclear transcription factor that is expressed in basal cells of multilayered epithelia and myoepithelial cells of the breast. The authors analyzed the immunocytochemical distribution of p63 in a series of 82 breast FNABs (30 benign lesions and 52 malignant breast lesions).

METHODS

Eighty-two archival, Papanicolaou-stained smears of breast lesions were retrieved from the files of the authors' institutions. Immunocytochemistry was performed according to the streptavidin-biotin-peroxidase complex technique using the antibody 4A4 (against all p63 isoforms). Two pathologists evaluated the distribution of p63 positive cells. Only nuclear reactivity was considered specific.

RESULTS

In benign lesions, p63 decorated the nuclei of MECs in all samples. p63 also stained naked nuclei in fibroadenomas. In malignant lesions, p63 was positive in MECs overlying malignant cell clusters in all 8 samples of ductal carcinoma in situ (DCIS), in 9 of 16 samples of pure invasive carcinomas (IC), and in 16 of 20 samples that contained both DCIS and IC. In 18 samples (36%), a variable population of p63 positive, malignant cells was observed. p63 failed to decorate stromal, neural, adipocytic, and smooth muscle cells in all samples.

CONCLUSIONS

p63 is a reliable nuclear marker of MECs in breast aspirates. Regardless of the fact that variable proportions of p63 positive, malignant cells were observed in 36% of breast carcinoma aspirates, p63 may be a useful adjunct antibody to confirm the presence of MECs in FNABs of benign breast lesions.

Immunohistochemical demonstration of 14-3-3 sigma protein in normal human tissues and lung cancers, and the preponderance of its strong expression in epithelial cells of squamous cell lineage

In order to confirm 14-3-3 sigma (sigma) protein distribution in human tissues, immunohistochemistry was performed using various paraffin-embedded human tissues. In normal human tissues, the strongest immunoreactivity for 14-3-3sigma protein was observed in squamous epithelia at various sites, followed by basal cells of the trachea, bronchus and basal or myoepithelial cells of various glands. Moderate to weak 14-3-3sigma immunoreactivity was seen in the epithelial cells of the alimentary tract, gall bladder, urinary tract and endometrium. In the lung, 14-3-3sigma immunoreactivity was also observed in hyperplastic type II alveolar cells and metaplastic squamous cells. Immunohistochemical study using non-small-cell lung cancers revealed that 14-3-3sigma immunoreactivity was stronger in squamous cell carcinomas than in adenocarcinomas. The present study revealed that 14-3-3sigma expression was exclusively present in various epithelial cells and had a tendency to be stronger in cells destined for squamous epithelium or differentiating toward squamous cells in human normal and neoplastic cells.

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Smooth muscle cell differentiation in mammary stromo-epithelial lesions with evidence of a dual origin: stromal myofibroblasts and myoepithelial cells

AIMS

We investigated the origin of myoid cells in benign stromo-epithelial lesions of the breast in order to ascertain their myoepithelial or myofibroblastic origin.

METHODS AND RESULTS

We selected 22 stromo-epithelial lesions of the breast and reviewed their morphological features at haematoxylin-eosin (H&E) level. The lesions were classified as fibrous stromo-epithelial lesions (without evidence of myoid differentiation at H&E level) (13 cases), type 1 myoid stromo-epithelial lesions (myoid cells directly merging with the myoepithelial layer) (three cases), type 2 myoid stromo-epithelial lesions (bundles of myoid cells unrelated to the glands) (six cases). All cases were studied immunohistochemically and myoid stromo-epithelial lesions were also studied with electron microscopy. The myoid component in two out of three cases of type 1 myoid lesions showed immunohistochemically co-expression of smooth muscle and myoepithelial markers. In contrast, the remainder showed immunohistochemical results identical to those found in type 2 myoid lesions (positivity with SMA, desmin, calponin, CD34 and bcl2 and negativity with cytokeratin 14 and p63). Ultrastructural study confirmed the presence of cells with myoepithelial features in type 1 myoid lesions and of cells with myofibroblastic features in type 2 myoid lesions.

CONCLUSIONS

Myoid cell differentiation is common in stromo-epithelial lesions of the breast, and is evident in H&E sections in up to 40% of cases. In addition, the origin of myoid cells is myofibroblastic in most cases, but in some cases, cells present immunohistochemical and ultrastructural evidence of myoepithelial origin.

p63 and TTF-1 immunostaining. A useful marker panel for distinguishing small cell carcinoma of lung from poorly differentiated squamous cell carcinoma of lung

We studied the usefulness of p63 and thyroid transcription factor-1 (TTF-1) immunostains for differentiating poorly differentiated squamous cell carcinoma (PDSCC) from small cell lung carcinoma (SCLC). We used monoclonal antibodies reactive to p63 or TTF-1 to stain 4-microns-thick sections from 30 formalin-fixed, paraffin-embedded lung biopsy and resection specimens and 7 alcohol-fixed, formalin-postfixed, paraffin-embedded cell blocks from lung fine-needle aspirations (FNAs). For p63, we used a streptavidin-biotin kit, diaminobenzidine as the chromogen, and a hematoxylin counterstain. We used automated immunostaining for TTF-1. The 37 cases included 23 SCLCs, 13 PDSCCs, and 1 carcinoma initially diagnosed as PDSCC. All 23 SCLCs were negative or, rarely, equivocal for p63; 20 (87%) of 23 were TTF-1+; nuclear staining ranged from strong and/or frequent to weak and/or uncommon. All 13 PDSCCs were TTF-1-/p63+ with intense staining of 50% to 100% of tumor cells. One case originally diagnosed as PDSCC was TTF-1+/p63-, suggestive of SCLC; after morphologic reexamination and immunostaining for neuroendocrine markers, it was reclassified as intermediate-type SCLC. TTF-1 immunostaining showed equal or increased sensitivity in alcohol-fixed cytologic cell block samples compared with formalin-fixed biopsy material; in 1 SCLC case, the biopsy specimen was TTF-1-; however, the FNA cell block stained positively. p63 and TTF-1 appear to be useful for differentiating SCLC from lung PDSCC in formalin-fixed and alcohol-fixed, formalin-postfixed material.

Ectopic breast tissue as a possible cause of false-positive axillary sentinel lymph node biopsies

Epithelial inclusions representing ectopic breast tissue are uncommonly seen in axillary lymph nodes. The extensive histopathologic examination of axillary sentinel lymph nodes of patients with breast carcinoma may increase the chances to encounter tiny foci of ectopic breast tissue, which may be misinterpreted as (micro)metastatic disease and lead to unwarranted completion of axillary dissection and to inaccurate staging and improper adjuvant treatments for the patients. Here we report on seven cases of ectopic breast tissue in axillary sentinel lymph nodes. In three cases there were coexistent micrometastases, and in the remaining cases the ectopic tissue was not associated with metastatic disease. The ectopic breast tissue showed remarkably varied morphologic features, including apocrine metaplasia and proliferative changes indistinguishable from those occurring in sclerosing adenosis and florid epithelial hyperplasia of the breast. A peripheral layer of myoepithelial cells was consistently detected in the ectopic glands and ducts. Besides awareness and purely morphologic criteria, a false-positive identification of these inclusions as metastatic carcinoma may be avoided by the use of immunohistochemical reactions for the localization of specific markers of the myoepithelial cell component, which is associated with the ectopic breast tissue.

p63 expression in normal, hyperplastic and malignant breast tissues

BACKGROUND

p63 is a homologue of the p53 tumor suppressor gene and its protein is selectively expressed in the basal cells of a variety of epithelial tissues. It has recently been confirmed that p63 is expressed in the basal cells of normal prostate glands but not in prostatic carcinomas. Whether expression of p63 in breast correlates with tumor progression is the focus of this study.

METHODS

Forty cases, which all contained normal breast tissue, ductal hyperplasia, ductal carcinoma in situ and invasive ductal carcinoma in the same patient were included in this investigation using an indirect immunohistochemical method and double staining.

RESULTS

p63 was exclusively expressed in the myoepithelial cells of normal breast, partially expressed in ductal hyperplasia, rarely expressed in carcinoma in situ and not expressed in invasive carcinomas.

CONCLUSION

The results suggest an association between loss of p63 expression and progression of breast ductal carcinoma. p63 immunostaining might be of assistance for distinguishing invasive ductal carcinoma from ductal carcinoma in situ or rare questionable ductal hyperplastic lesions, leading to correct therapy clinically.

Novel and classic myoepithelial/stem cell markers in metaplastic carcinomas of the breast

Metaplastic carcinomas of the breast (MCBs) are unusual neoplasms characterized by an admixture of glandular epithelial components, which frequently exhibit features of squamous differentiation, and mesenchymal malignant components. Regardless of the presence of myoepithelial features in MCB, no consensus concerning their putative histogenesis has yet been achieved. Recently, novel putative myoepithelial markers have been developed, including p63, maspin, and P-cadherin. We assessed the expression of these myoepithelial markers in MCBs and compared their expression with classic myoepithelial markers. Immunohistochemistry using the streptavidin-biotin-peroxidase complex technique with antibodies raised against p63, maspin, P-cadherin, actin (clones CGA7, 1A4 and HHF35), cytokeratin 14 (Ck14), and vimentin was performed on 16 MCBs (7 matrix-producing MCBs, 6 adenosquamous MCBs, and 3 MCBs with heterologous elements). In healthy breast lobules and ducts adjacent to the tumors, myoepithelial cells showed distinctive and consistent immunoreactivity for p63, maspin, P-cadherin, actin, S-100 protein, and Ck14. Matrix-producing MCBs were positive for maspin in all cases, for p63 in 4 of 7 cases, and for P-cadherin in 4 of 7 cases. Adenosquamous MCB showed immunoreactivity for p63, maspin, and P-cadherin in 5 of 6 cases. All novel myoepithelial markers and Ck14 decorated squamous cell islands. MCBs with heterologous elements were positive for p63 in 1 case, for maspin in all 3 cases, and for P-cadherin in 2 cases. All cases showed at least one of the novel myoepithelial markers. Eleven of 16 cases were positive for actin. Eleven of 14 cases reacted with Ck14, and all cases that stained for S-100 protein (9 of 9) and vimentin (13 of 13) were also positive. Based on our findings, the balance of probabilities favors that MCBs may have a basal or myoepithelial cell histogenesis and differentiation.

The relationship between p63 and p53 expression in normal and neoplastic breast tissue

CONTEXT

p63 is a recently described p53 homologue. Despite structural homology, they have different activities.

OBJECTIVES

To obtain new insights into the role of p63 in normal and neoplastic breast tissue and to verify the possible association between p63 and p53 in breast carcinomas.

DESIGN

Immunohistochemistry in 85 breast carcinomas using p63, smooth muscle actin (1A4), p53, estrogen receptor, and progesterone receptor. The p63-positive cases were submitted to a double-immunolabeling study using p63 with 1A4, cytokeratin 7, and 34betaE12. Clinical data were retrieved from medical files.

RESULTS

p63, like 1A4, stained a single and continuous layer surrounding normal breast ductal and alveolar epithelium. In carcinomas, p53 was expressed in 21.17% of carcinomas, whereas p63 was expressed only in poorly differentiated ductal carcinomas (11.76% of cases). p63-positive cells coexpressed 1A4 and 34betaE12, but not cytokeratin 7. Expression of p63 correlated with pathologic staging, tumor size, histologic grading, nodal metastasis, and estrogen receptor negativity.

CONCLUSIONS

p63 is a specific myoepithelial cell marker in normal breast tissue and is expressed in a minority of breast carcinomas, being seen only in grade III ductal carcinomas. In ductal carcinomas, malignant p63-positive cells have an immunophenotype similar to that of myoepithelial cells, suggesting that these cells originate from a primary progenitor cell that underwent divergent differentiation to ductal and myoepithelial cells during clonal expansion. Our study argues against a direct role in mammary tumorigenesis. However, p53 is rarely coexpressed with p63, suggesting that p63 could act indirectly as an oncogene by inhibiting p53. This hypothesis could also explain why p63 correlated with several other indicators of poor prognosis.

P63 is expressed in basal and myoepithelial cells of human normal and tumor salivary gland tissues

p63 is essential for epithelial cell survival and may function as an oncogene. We examined by immunohistochemistry p63 expression in human normal and tumor salivary gland tissues. In normal salivary glands, p63 was expressed in the nuclei of myoepithelial and basal duct cells. Among 68 representative salivary gland tumors, 63 displayed p63 reactivity. In all tumor types differentiated towards luminal and myoepithelial lineages (pleomorphic adenomas, basal cell adenomas, adenoid cystic carcinomas, and epithelial-myoepithelial carcinomas), p63 was expressed in myoepithelial cells, whereas luminal cells were always negative. Similarly, in mucoepidermoid carcinomas, basal, intermediate, and squamous cells expressed p63, in contrast to luminal mucous cells. p63 reactivity was also restricted to basal cells in Warthin tumors and oncocytomas. Myoepitheliomas and myoepithelial carcinomas all expressed p63. The only five negative tumors were three of four acinar cell carcinomas and two of three adenocarcinomas. In conclusion, p63 is expressed in the nuclei of normal human salivary gland myoepithelial and basal duct cells. p63 expression is retained in the modified myoepithelial and basal cells of human salivary gland tumors, which suggests a role for p63 in oncogenesis of these complex tumors.

p63 expression in normal human epidermis and epidermal appendages and their tumors

BACKGROUND

p63, a member of the p53 gene family, is expressed in basal cells of several different organs.

METHODS

The immunoreactivity of p63 was examined in normal human epidermis and epidermal appendages and their tumors, and compared with proliferative activity as evaluated by Ki-67.

RESULTS

In normal skin, p63 expression was seen in basal/suprabasal cells of the epidermis, outer root sheath and hair matrix cells of the hair follicle, seboblast situated in the outermost layer of sebaceous glands, and outer layer cells of the ductal portion and myoepithelial cells of the secretory portion of the sweat glands. p63 expression was confined to the cells forming a continuous basal rim along the normal epithelial structure. In tumors, p63 expression resembled that in normal tissue in that tumor components originating from p63-positive cells were constantly positive for p63. In normal and tumor tissues, not all p63-positive cells were positive for Ki-67.

CONCLUSIONS

p63 expression may be a marker of basal/progenitor cells in tumors of epidermis and epidermal appendages, and may be a diagnostic marker of these tumors.

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.