Basal Myoepithelial Cells Research Articles

Abstract B59: Epithelial-mesenchymal interaction in cancer as potential target for anticancer therapy

Abstract Many results demonstrate that cancer cells need for their growth and spread through organism a specific microenvironment'the tumor stroma. Carcinomas represent highly complex tissue composed from cancer cells and stroma including fibroblasts producing extracellular matrix and bioactive substances, inflammatory cells and blood vessels. We focused our research on most abundant cell component of cancer stroma on cancer-associated fibroblasts. We isolated stromal fibroblasts from tumours originated from the squamous epithelium such as basal and squamous cell carcinoma, melanoma and skin metastasis of breast cancer. We expanded them and in vitro evaluated their biological effect on normal keratinocytes and breast cancer keratinocytes (EMG-3). The results were compared with control experiments using normal human dermal fibroblasts, 3T3 mouse fibroblasts, and 3T3 fibroblasts influenced by the fibroblasts prepared from the basal cell carcinoma. Our results demonstrated that expression of luminal marker keratin 8 was influenced only by cancer associated fibroblasts prepared from any tested tumors. In contrast, all tested types of fibroblasts showed a strong stimulatory effect on the expression of basal/myoepithelial marker keratin 14. Since keratin 14 is a marker of basal myoepithelial cells and keratin 8 is a marker of luminal cells, these double-positive cells can be considered for precursor cells with properties close to stem cells. Their presence in clinical samples indeed signals very poor prognosis in cancer-suffering patiens. In conclusion, our data indicate that cancer associated fibroblasts are able to influence the phenotype of a breast cancer cell line and this effect is based on a tumor type-unspecific mechanism. Citation Format: Pavol Szabo, Karel Smetana, Jr., Barbora Dvorankova, Ondrej Kodet, Hynek Strnad, Michal Kolar. Epithelial-mesenchymal interaction in cancer as potential target for anticancer therapy. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B59.

Somatic loss of p53 leads to stem/progenitor cell amplification in both mammary epithelial compartments, basal and luminal

Mammary epithelium comprises a layer of luminal cells and a basal myoepithelial cell layer. Both mammary epithelial compartments, basal and luminal, contain stem and progenitor cells, but only basal cells are capable of gland regeneration upon transplantation. Aberrant expansion of stem/progenitor cell populations is considered to contribute to breast tumorigenesis. Germline deletions of p53 in humans and mice confer a predisposition to tumors, and stem cell frequency is abnormally high in the mammary epithelium of p53-deficient mice. However, it is unknown whether stem/progenitor cell amplification occurs in both, basal and luminal cell populations in p53-deficient mammary tissue. We used a conditional gene deletion approach to study the role of p53 in stem/progenitor cells residing in the mammary luminal and basal layers. Using two- and three-dimensional cell culture assays, we showed that p53 loss led to the expansion of clonogenic stem/progenitor cells in both mammary epithelial cell layers. Moreover, following p53 deletion, luminal and basal stem/progenitor cells acquired a capacity for unlimited propagation in mammosphere culture. Furthermore, limiting dilution and serial transplantation assays revealed amplification and enhanced self-renewal in the basal regenerating cell population of p53-deficient mammary epithelium. Our data suggest that the increase in stem/progenitor cell activity may be, at least, partially mediated by the Notch pathway. Taken together, these results strongly indicate that p53 restricts the propagation and self-renewal of stem/progenitor cells in both layers of the mammary epithelium providing further insight into the impact of p53 loss in breast cancerogenesis.

Clinical significance of ERβ mRNA expression in ERα-negative and triple-negative breast cancers.

545 Background: Previously at the 2012 ASCO meeting, we reported significant ERβ mRNA expression in ERα-negative (ERα-) and triple negative breast cancers (TNBC). In this study, we analyzed its clinical outcome and correlation with other clinical parameters. Methods: A total of 141 cases consisted of 69 ERα- BC including 41 TNBC and 72 ERα+ BC were obtained from patients aged 29 to 97 years old between 2003 and 2010. Treatments included surgery, hormone, chemo- or radiotherapy, or any combinations. The follow-up period ranged from 1 to 132 months. ERβ mRNA was analyzed from formalin-fixed tumor tissues by RT-PCR. ERα, PR, Her-2, Ki-67, AIB-1, NFk/p65, p-c-jun, Ki-67, TIF-2, SRC-1, CK5/6 and p53 were tested by immunohistochemistry. The correlation was deemed significant if p value less than 0.05 from Chi-square. Overall survival (SVR) was defined from the date of diagnosis to last follow-up or death attributed to BC and was analyzed by the Kaplan-Meier curves and Wilcoxon rank sum. Results: Single or combination of ERβ isoform(s) was highly expressed in both ERα- and TNBC and ERβ2 was the most frequent (48.8%) and ERβ5, the least (30.2%). In contrast, ERβ5 was the most frequent in ERα+BC. Presence of all or any ERβ isoform was associated with significantly higher SVR in all cases, and in TNBC (ERβ total, Wilcoxon p = 0.0177, ERβ2, p= 0.0329), and also with negative LN (p< 0.0001). ERβ2 and ERβ5 were expressed in 63.2% and 30 %, respectively, in 20 patients died in 1 to 60 months. Over expression of AIB-1, NF-kB/p65 and TIF-2 was associated with ERβ1 and ERβ2 (p<0.05). Ki-67 + cells were mostly ERβ + BC than ERα+. ERα mRNA expression was up-regulated, and ERβ,down- regulated, with the ERα: ERβ+ ratio of 3-1000:1. There was no association between ERβ expression and the stage, age, tumor size, and postmenopausal status. Conclusions: Specific ERβ isoform appears to be a significant discriminating factor for SVR and negative node. ERβ2 is the predominant isoform in ERα- but ERβ5 in ERα+BC, suggesting a distinct role of ERβ isoform in ERα- and ERα+BC. ERβ isoform may be a selective therapeutic target in this cohort. ERβ+/ Ki-67+cells appear to be a sub-population of BC arising from basal-myoepithelial cells in this cohort.

Parity induces differentiation and reduces Wnt/Notch signaling ratio and proliferation potential of basal stem/progenitor cells isolated from mouse mammary epithelium

IntroductionEarly pregnancy has a strong protective effect against breast cancer in humans and rodents, but the underlying mechanism is unknown. Because breast cancers are thought to arise from specific cell subpopulations of mammary epithelia, we studied the effect of parity on the transcriptome and the differentiation/proliferation potential of specific luminal and basal mammary cells in mice.MethodsMammary epithelial cell subpopulations (luminal Sca1-, luminal Sca1+, basal stem/progenitor, and basal myoepithelial cells) were isolated by flow cytometry from parous and age-matched virgin mice and examined by using a combination of unbiased genomics, bioinformatics, in vitro colony formation, and in vivo limiting dilution transplantation assays. Specific findings were further investigated with immunohistochemistry in entire glands of parous and age-matched virgin mice.ResultsTranscriptome analysis revealed an upregulation of differentiation genes and a marked decrease in the Wnt/Notch signaling ratio in basal stem/progenitor cells of parous mice. Separate bioinformatics analyses showed reduced activity for the canonical Wnt transcription factor LEF1/TCF7 and increased activity for the Wnt repressor TCF3. This finding was specific for basal stem/progenitor cells and was associated with downregulation of potentially carcinogenic pathways and a reduction in the proliferation potential of this cell subpopulation in vitro and in vivo. As a possible mechanism for decreased Wnt signaling in basal stem/progenitor cells, we found a more than threefold reduction in the expression of the secreted Wnt ligand Wnt4 in total mammary cells from parous mice, which corresponded to a similar decrease in the proportion of Wnt4-secreting and estrogen/progesterone receptor-positive cells. Because recombinant Wnt4 rescued the proliferation defect of basal stem/progenitor cells in vitro, reduced Wnt4 secretion appears to be causally related to parity-induced alterations of basal stem/progenitor cell properties in mice.ConclusionsBy revealing that parity induces differentiation and downregulates the Wnt/Notch signaling ratio and the in vitro and in vivo proliferation potential of basal stem/progenitor cells in mice, our study sheds light on the long-term consequences of an early pregnancy. Furthermore, it opens the door to future studies assessing whether inhibitors of the Wnt pathway may be used to mimic the parity-induced protective effect against breast cancer.

Control of mammary myoepithelial cell contractile function by α3β1 integrin signalling

In the functionally differentiated mammary gland, basal myoepithelial cells contract to eject the milk produced by luminal epithelial cells from the body. We report that conditional deletion of a laminin receptor, α3β1 integrin, from myoepithelial cells leads to low rates of milk ejection due to a contractility defect but does not interfere with the integrity or functional differentiation of the mammary epithelium. In lactating mammary gland, in the absence of α3β1, focal adhesion kinase phosphorylation is impaired, the Rho/Rac balance is altered and myosin light-chain (MLC) phosphorylation is sustained. Cultured mammary myoepithelial cells depleted of α3β1 contract in response to oxytocin, but are unable to maintain the state of post-contractile relaxation. The expression of constitutively active Rac or its effector p21-activated kinase (PAK), or treatment with MLC kinase (MLCK) inhibitor, rescues the relaxation capacity of mutant cells, strongly suggesting that α3β1-mediated stimulation of the Rac/PAK pathway is required for the inhibition of MLCK activity, permitting completion of the myoepithelial cell contraction/relaxation cycle and successful lactation. This is the first study highlighting the impact of α3β1 integrin signalling on mammary gland function.

The mammary myoepithelial cell

Over the last few years, the discovery of basal-type mammary carcinomas and the association of the regenerative potential of the mammary epithelium with the basal myoepithelial cell population have attracted considerable attention to this second major mammary lineage. However, many questions concerning the role of basal myoepithelial cells in mammary morphogenesis, functional differentiation and disease remain unanswered. Here, we discuss the mechanisms that control the myoepithelial cell differentiation essential for their contractile function, summarize new data concerning the roles played by cell-extracellular matrix (ECM), intercellular and paracrine interactions in the regulation of various aspects of the mammary basal myoepithelial cell functional activity. Finally, we analyze the contribution of the basal myoepithelial cells to the regenerative potential of the mammary epithelium and tumorigenesis.

Cell blocks allow reliable evaluation of expression of basal (CK5/6) and luminal (CK8/18) cytokeratins and smooth muscle actin (SMA) in breast carcinoma

Gene expression studies have revealed several molecular subtypes of breast carcinoma with distinct clinical and biological behaviours. DNA microarray studies correlated with immunohistochemical profiling of breast carcinomas using cytokeratin (CK) markers, Her2/neu, oestrogen receptor (ER), and basal myoepithelial cell markers have identified five breast tumour subtypes: (i) luminal A (ER+; Her2/neu-), (ii) luminal B (ER+; Her2/neu+), (iii) Her2 overexpression (ER-; Her2/neu+), (iv) basal-like (ER-; Her2/neu-, CK5/6 and 14+), and (v) negative for all markers. Luminal carcinomas express cytokeratins in a luminal pattern (CK8/18), and the basal-like type expresses CK5/6 and CK14 or basal epithelial cell markers. CK5/6, CK8/18, and smooth muscle actin (SMA) expression were assessed in cell blocks and compared with expression in surgical specimens. Sixty-two cases of breast carcinoma diagnosed by fine needle aspiration cytology with cell blocks and available surgical specimens were included. Cell blocks containing at least 10 high-power fields each with at least 10 tumour cells and surgical specimens were immunostained for CK5/6, CK8/18 and SMA. Percentage sensitivity, specificity, positive predictive value, negative predictive value and accuracy were, respectively, 77, 100, 100, 92 and 94 for CK5/6; 98, 66, 96, 80 and 95 for CK8/18; and 92, 96, 85, 98 and 95 for SMA. The identification of CK5/6, CK8/18 and SMA by immunohistochemistry in cell blocks can be a reliable method that yields results close to those obtained in surgical specimens, and can contribute to the classification of breast carcinomas with luminal and basal expression patterns, providing helpful information in the choice of treatment and in the evaluation of prognostic and predictive factors.

Unusual anogenital apocrine tumor resembling mammary-like gland adenoma in male perineum: a case report

A rare case of an apocrine tumor in the male perineal region is reported. A dermal cystic lesion developed in the region between the anus and scrotum of a 74-year-old Japanese male. The cystic lesion, measuring 3.5 × 5.0 cm in size, was lined by columnar or flattened epithelium with occasional apocrine features and supported by a basal myoepithelium lining. A mural nodule, measuring 1 × 1.5 cm in size, protruded into the cystic space and consisted of a solid proliferation of tubular glands with prominent apocrine secretion and basal myoepithelial cells. Immunohistochemical examination showed that the luminal cells were partially positive for gross cystic disease fluid protein 15 and human milk fat globulin 1, and the basal myoepithelial cells were positive for alpha-smooth muscle actin and S-100 protein. Estrogen and progesterone hormone receptors were focally and weakly positive for luminal epithelium. Although no mammary-like glands were present in the dermis around the tumor, this unusual apocrine tumor has been suggested to be derived from male anogenital mammary-like glands and mimic a mammary-like gland adenoma in the male perineum.

Isolation of mouse mammary epithelial progenitor cells with basal characteristics from the Comma-Dβ cell line

A mouse mammary epithelial cell line with morphogenetic properties in vivo, Comma-Dβ, was used to isolate and to characterize mammary progenitor cells. We found that a homogeneous cell population expressing high surface levels of stem cell antigen 1 (Sca-1) was able to give rise in vivo to ductal and alveolar structures comprising luminal secretory and basal myoepithelial cells. Unlike the Sca-1 high, the Sca-1 neg/low cell population displayed a reduced morphogenetic potential. The Sca-1 high cells presented moderate CD24, high CD44 and α6 integrin surface levels, expressed basal cell markers p63, keratins 5 and 14, but no luminal and myoepithelial lineage markers. In culture, the Sca-1 high cells generated identical daughter cells that retained their in vivo developmental potential, indicating that these cells were maintained by self-renewal. Plated at clonogenic density in Matrigel, Sca-1 high cells formed spheroids that included luminal and myoepithelial cells. Thus, the isolated Sca-1 high basal cells possess several features of stem/progenitor cells, including specific markers, self-renewal capacity, and the ability to generate the two major mammary lineages, luminal and myoepithelial. These data provide evidence for the existence of basal-type mouse mammary progenitors able to participate in the morphogenetic processes characteristic of mammary gland development.

Développement de la glande mammaire : rôle des cellules basales myoépithéliales

Mammary epithelium is organized as a bilayer with a layer of luminal secretory cells and a layer of basal myoepithelial cells. To dissect the specific functions of these two major compartments of the mammary epithelium in mammary morphogenesis we have used genetically modified mice carrying transgenes or conditional alleles whose expression or ablation were cell-type specific. Basal cells are located in close proximity to mammary stroma and directly interact with the extracellular matrix (basement membrane) during all their lifespan. On the contrary, luminal secretory cells during early stages of the postnatal mammary development have only limited contacts with basement membrane and become exposed to the extracellular matrix only during late developmental stages at the end of pregnancy and in lactation. Consistently perturbation of beta1-integrin function specifically in the luminal layer of the mammary epithelium, did not interfere with mammary morphogenesis until the second part of pregnancy but led to impaired secretory differentiation and lactation. On the contrary, ablation of beta1-integrin gene in the basal mammary epithelial cells resulted in a more precocious phenotype: disorganized branching in young virgin animals and a complete arrest of lobuloalveolar development. Further, a constitutive activation of beta-catenin signaling due to expression of N-terminally truncated (stabilized) beta-catenin specifically in basal myoepithelial cells resulted in accelerated differentiation of luminal secretory cells in pregnancy, precocious postlactational involution, increased angiogenesis and development of mammary tumors. Altogether these data suggest that basal mammary epithelial cells can affect growth and differentiation of luminal secretory cells, have an impact on the epithelium-stroma relationships and, thereby, play an important role in the process of mammary morphogenesis and differentiation.

Myoepithelial Cells in the Control of Mammary Development and Tumorigenesis: Data From Genetically Modified Mice

Until recently, myoepithelial cells-the second major cell population in the mammary epithelium-were not considered to play an important role in the morphogenetic events during gland development. Mouse mutants with changes in the gene expression pattern characteristic of the basal myoepithelial cell layer have been generated and used to show that these cells influence the proliferation, survival and differentiation of luminal cells, modulate stromal-epithelial interactions and actively participate in mammary morphogenesis. Various cellular and molecular mechanisms may underlie the observed phenotypes. These include an unbalanced expression of matrix degrading metalloproteinases (MMPs) and their inhibitors, leading to changes in the composition and organization of the (extracellular matrix) ECM, the production of soluble growth factors affecting stromal and epithelial cell growth and differentiation and direct signaling through cell-cell contacts between the myoepithelial and luminal cell layers.

Targeted activation of β-catenin signaling in basal mammary epithelial cells affects mammary development and leads to hyperplasia

Wnt/beta-catenin signaling pathway is involved in the maintenance of the progenitor cell population in the skin, intestine and other tissues, and its aberrant activation caused by stabilization of beta-catenin contributes to tumorigenesis. In the mammary gland, constitutive activation of Wnt/beta-catenin signaling in luminal secretory cells results in precocious lobuloalveolar differentiation and induces adenocarcinomas, whereas the impact of this signaling pathway on the function of the second major mammary epithelial cell lineage, the basal myoepithelial cells, has not been analyzed. We have used the keratin (K) 5 promoter to target the expression of stabilized N-terminally truncated beta-catenin to the basal cell layer of mouse mammary epithelium. The transgenic mice presented an abnormal mammary phenotype: precocious lateral bud formation, increased proliferation and premature differentiation of luminal epithelium in pregnancy, persistent proliferation in lactation and accelerated involution. Precocious development in pregnancy was accompanied by increased Myc and cyclin D1 transcript levels, and a shift in p63 variant expression towards the DeltaNp63 form. The expression of ECM-degrading proteinases and their inhibitors was altered in pregnancy and involution. Nulliparous transgenic females developed mammary hyperplasia that comprised undifferentiated basal (K5/14-positive, K8- and alpha-smooth muscle-actin-negative) cells. Multiparous mice, in addition, developed invasive basal-type carcinomas. Thus, activation of beta-catenin signaling in basal mammary epithelial cells affects the entire process of mammary gland development and induces amplification of basal-type cells that lack lineage markers, presumably, a subpopulation of mammary progenitors able to give rise to tumors.

Written report of presented lectures: endocrine treatment and prevention of breast and gynaecological cancers: The scientific basis of endocrine prevention

The science of endocrine prevention is based on the cell and molecular biology of the mammary gland and the epidemiology surrounding the development of breast cancer. The major epithelial structures of the breast are the ducts and the lobules. Each lobule comprises two epithelial cell layers, luminal epithelial cells which differentiate under hormonal influences to produce milk during and after pregnancy and basal myoepithelial cells which contain smooth muscle actin and have contractile properties. Experiments where low numbers of tagged mouse epithelial cells are transplanted to the mammary fat pad suggest that the mammary gland can be derived from a single stem cell [1]. Some transplanted epithelial cells give rise to ducts only or lobular-like structures only indicating that there are committed progenitor cells for each of these structures [2]. A proportion of single epithelial cells (∼5%) when dissociated from the reduction mammoplasty tissue give rise to colonies which contain cells with markers for both luminal and myoepithelial cells suggesting a single progenitor for both cell types [3]. There is also evidence for a proliferating transit population of cells between the single precursor cell and differentiated luminal and myoepithelial cells. Luminal epithelial cells are of at least two types based on their oestrogen receptor (ER) status. The nucleus of approximately 20% of cells stains with antibodies to ER using immunocytochemical methods. These same cells also contain progesterone receptors (PR). However, the cells which express ER and PR are differentiated and rarely divide and it is probable that oestrogen and progesterone exert their proliferative effects by inducing paracrine growth factors which produce their proliferative effects on adjacent ER/PR-negative cells [4,5]. There is evidence that the separation between ER/PR-positive steroid hormone sensor cells and ER/PR-negative effector cells is reduced with age, indicating a transit population of ER/PR-positive proliferative cells which could potentially be targets for carcinogenesis. It is known that the numbers of ER/PR-positive proliferating cells are markedly increased in ER-positive breast cancers and moderately increased in hyperplasia of usual type and atypical ductal hyperplasia [6]. Thus, as the female ages, ER/PR-positive proliferating cells can be detected suggesting that these cells may be a target for malignancy and that this population of cells expands in ER-positive premalignant and malignant lesions. Rats treated with the carcinogen methylnitrosurea (MNU) show increased numbers of ER/PR-positive proliferating cells and this increase can be prevented by mimicking pregnancy with high-dose oestrogen and progesterone for 21 days before the administration of MNU [7]. The data outlined above suggest a model for the action of preventive endocrine therapy. Wellings and colleagues [8] and others suggest that breast cancer arises in a terminal duct/lobular unit. Under normal circumstances, these units comprise a series of progenitor cells which give rise to luminal (ER/PR-positive and -negative) and myoepithelial cells. The control of cell production of cell types is probably regulated by feedback to the progenitor cell from the ER/PR-positive sensor cell. Preventive endocrine therapy (e.g. Selective Oestrogen Receptor Modulators (SERMs) or ovarian ablation) given under these normal circumstances would reduce proliferation (and putatively) malignant transformation in ER-positive and ER-negative cells by a feedback mechanism, thus potentially suppressing all tumour types. However, if preventive endocrine therapy is given after the early stages of malignancy have developed, lesions with a predominant ER/PR-positive phenotype will be suppressed, whereas those with an ER-negative phenotype will not. In the National Surgical Adjuvant Breast and Bowel Project (NSABP) P1 tamoxifen prevention trial and the raloxifene prevention trial (MORE), only ER/PR-positive tumours were prevented suggesting that treatments were suppressing early malignancy rather that preventing it. Attempts to induce differentiation by, for example, mimicking pregnancy using chorionic gonadotrophin (HCG) or high-dose reproductive [9] steroids may be effective when lobules are normal, but relatively ineffective after the malignant process has been initiated since induction of differentiation in mammary tumours has proved to be difficult. Follow-up data of women given oophorectomy in their thirties or early forties for benign conditions and the results of P1 and MORE studies indicate that approximately one-half of tumours are prevented or suppressed. Elimination of the other half may require endocrine measures to be implemented at an earlier age.

Separated human breast epithelial and myoepithelial cells have different growth factor requirements in vitro but can reconstitute normal breast lobuloalveolar structure.

In order to investigate the specific factors controlling the growth of normal breast cell types, purified populations of human breast epithelial and myoepithelial cells from reduction mammoplasties were grown in primary culture in three defined media and their response to foetal calf serum (FCS), epidermal growth factor (EGF) and basic fibroblast growth factor (FGF2) measured using MTT growth assays. Epithelial and myoepithelial cells differed markedly in their growth requirements. Whereas epithelial cell survival was dependent on the presence of FCS, myoepithelial cell growth was dramatically inhibited by serum. EGF and FGF2 were mitogenic for epithelial cells but not myoepithelial cells, the addition of insulin being the only essential supplement required for myoepithelial cell growth. Heparin inhibited FGF2-stimulated epithelial cell growth but also basal myoepithelial cell proliferation and this inhibition could be overcome by the addition of EGF. Neutralizing antibodies to EGF also inhibited basal myoepithelial cell growth. This suggests the possibility of an autocrine role for a heparin-binding member of the EGF family in the growth of myoepithelial cells. Purified cells combined to form lobuloalveolar structures when incubated in a reconstituted basement membrane matrix (Matrigel) in the presence of EGF and FGF2.

Keratins (Kl6 and Kl7) as markers of keratinocyte hyperproliferation in psoriasis in vivo and in vitro

Keratinocyte differentiation in psoriasis was examined using a panel of monospecific monoclonal antibodies to keratins (K), including two recently developed monoclonal antibodies raised to carboxy terminal peptides of K6 (LL020) and K16 (LL025). Keratinocytes from normal skin, untreated psoriatic plaques and non-lesional psoriatic skin, were cultured using multiple in vitro systems. Time-lapse cinephotography was used to measure the intermitotic time of normal and psoriatic keratinocytes in both low calcium-defined and serum-containing media. The intermitotic time did not differ significantly between psoriatic and normal keratinocytes. Keratin expression of psoriatic and normal keratinocytes in vitro was examined by both gel electrophoresis and immunocytochemistry. K6, K16 and K17 were detected suprabasally in all culture systems in vitro, but only in interfollicular psoriatic epidermis in vivo, and not in normal skin. Small subpopulations of keratinocytes expressed simple epithelial keratins K7, K8, K18 and K19 in cultures on plastic substrates, but these keratins were absent in skin equivalents of normal or psoriatic skin. No psoriasis-specific pattern of differentiation was found in vitro. As the K6 peptide antibody reacted with basal cells of normal skin, probably due to K5 cross-reactivity, K16 expression determined by LL025 was found to be the most sensitive indicator of the psoriatic state of differentiation, and this antibody is recommended for future work on psoriasis. K17 had a distinct pattern of tissue distribution in normal skin: K17, but not K16, was present in basal myoepithelial cells in sweat glands, and the deep outer root sheath, but K17 distribution paralleled that of K16 in suprabasal psoriatic epidermis. As keratins K6, K16 and K17 are expressed in keratinocyte hyperproliferation, when high levels of certain cytokines are also expressed, the role of growth factors and regulatory nuclear transcription factors in the control of K6, K16 and K17 expression in psoriasis requires further study, in order to provide insight into the relationship between proliferation and differentiation.

Estrogen treatment of dunning tumors in castrated rats: Qualitative and quantitative morphology

Adult male rats bearing the Dunning R3327 prostatic carcinoma were randomized to the following treatments: intact controls, castration, and castration + estrogen. After a study period for 6 weeks the rats were killed and the tumors were analyzed morphometrically to determine the amount of epithelium, stroma, and connective tissue fibers in the tumors, and the nuclear size of large stromal cells. Cryostat sections were analyzed with immunohistochemistry using a panel of antibodies against cytokeratins, desmin, vimentin, fibronectin and collagens. Addition of estrogen to castration resulted in an inhibition of tumor growth. The expression of cytokeratin 14 (a marker for basal myoepithelial cells) was reduced, but the expression of cytokeratin 18 (a marker for the luminal epithelial cells) was unaffected by estrogen. The amounts of collagen I, III and fibronectin (plasma and cellular types) were increased in the stroma, and the nuclear size of large stromal cells was also increased by estrogen. It is concluded that castration + estrogen treatment has effects in the epithelium and stroma of Dunning tumors that are qualitatively and quantitatively different from the effects of castration alone.

Immunohistochemical characterization of epithelial cells in human lacrimal glands

Expression patterns of cytokeratins (CKs), actin, lactoferrin (Lf), lysozyme (Ly), vimentin, and S-100 protein were immunohistochemically examined in paraffin sections from eight normal major and accessory lacrimal glands (LGs). Luminal duct cells and a number of secretory cells stained with the antibodies (ABs) KL1 and Pkk1 (CK 7, 8, 17, 18), while basal duct and myoepithelial cells reacted with the AB 34 beta E12 (CK 5). Myoepithelial cells expressing CK 5 and actin were restricted to acini and intralobular ducts, and their number was greater in major LGs than accessory ones. Lf and Ly were found in 50%-75% of acini and intralobular ducts. Vimentin was absent in parenchyma of LGs. S-100 protein reaction was observed in a number of acinar and luminal duct cells of major LGs whereas epithelia of accessory LGs remained negative. Distribution patterns of CKs, Lf, and Ly in major and accessory LGs are identical. The difference with respect to the number of myoepithelial cells as well as S-100 protein reactivity between major and accessory LGs reactivity appeared to be relevant to the differences in their secretory mechanisms and local environment.

Immunohistochemical Localization of T Antigen-Like Substance in Benign Hyperplasia and Adenocarcinoma of the Prostate

Peanut agglutinin was used in a lectin-anti-lectin immunoperoxidase technique to assess the status of T antigen-like substance in histological sections of benign hyperplasia and adenocarcinoma of the prostate. Of 30 benign lesions 26 (86.7 per cent) had negative staining in the glandular epithelia and 4 showed uneven staining of the epithelial cells in a small proportion of the glands. Additionally, 15 of 30 benign lesions (50 per cent) had positive staining restricted to the basal myoepithelial cells in a variable proportion of the glands. All benign lesions demonstrated the presence of normal cryptic T antigen after neuraminidase digestion. Of 25 adenocarcinomas 14 (56 per cent) were positive and 7 (25 per cent) were negative for T antigen but demonstrated the presence of normal cryptic T antigen after neuraminidase digestion, and 4 (16 per cent) were negative for T and cryptic T antigens. Of 8 grade 1, 9 grade 2 and 8 grade 3 tumors, and 9 tumors from patients with bone metastases 3 (37.5 per cent), 8 (88.9 per cent), 7 (87.5 per cent) and 7 (77.8 per cent), respectively, were positive for T antigen or negative for T and cryptic T antigens.The results show a correlation between the status of T antigen-like substance and tumor grade as well as metastasis in patients with prostatic carcinoma.

Apocrine Cystadenoma

An apocrine cystadenoma was examined with the electron microscope. Two types of cells were identified: secretory cells and basal (myoepithelial) cells. The secretory cells showed abundant granules that had the features of lipid droplets. The lumen of the cyst contained fragments of cytoplasm that appeared to be detached from the apical portions of the secretory cells. This feature suggests an apocrine type of secretory mechanism involving decapitation of the apical parts of the cells. A merocrine type of secretion was also seen. The basal myoepithelial cells showed abundant cytoplasmic filaments, most of which appeared to be tonofilaments. These cells had fewer myofilaments than those seen in normal apocrine gland cells. Annulate lamellae were not seen in this case.