Abstract P4-01-18: A discrete population of p63+/K5/14+ cells implicated in the pathogenesis of salivary gland-like tumors of the breast

Background: Salivary gland-like tumors are currently subdivided into those with and those without myoepithelial differentiation. Furthermore, they show a wide range of differentiation patterns including squamous differentiation. Many authors believe that the myoepithelial cell plays a major role in this context. However, currently little is known about the evolution and cellular differentiation of these tumors.

Material and Methods: For that reason, we performed an in situ Triple Immunofluorescence Lineage/Differentiation Tracing (isTILT) and qRT-PCR study of basal (K5/K14), glandular (K7/K8/18), and epidermal-specific squamous (K10) keratins, p63, and smooth muscle actin (SMA; myoepithelial marker) with the aim to trace different cell lineages and define their cellular hierarchy in tumors. We investigated 50 cases of salivary gland-like tumors of the breast (11 Adenoid-cystic carcinomas, 9 (adeno-)myoepithelial tumors, 8 adeno-squamous carcinomas including 12 syringomas of the nipple, 10 squamous cell carcinomas), and their corresponding counterparts. In 4 cases, the corresponding cell cultures were also analysed.

Results: All tumor types contained p63+/K5/14+ progenitor cells in varying frequencies from a few percent up to 15%. These tumor cells were found to differentiate to glandular (K8/18-positive) or to myoepithelial (SMA-positive) lineage specific cells; they were also shown to generate various heterologeous cell differentiations such as squamous and mesenchymal progenies. p63 was partly retained in the myoepithelial and squamous cells lineages but not in the glandular cells lineage. These data were corroborated by RNA-expression results. The corresponding counterpart tumors of the salivary/lacrimal glands were found to have identical cellular compositions.

Conclusions: Our findings clearly demonstrate that p63+/K5/14+ tumor cells in salivary gland-like tumors of the breast and in their counterparts are key players in tumor development and differentiation. They undergo a transition from their original p63+/K5/14+ precursor state to new p63+/K5/14+/SMA+ myoepithelial and/or p63+/K10+ squamous lineages, and/or to a K7+/K8/18+ glandular state, which can be pictured by isTILT-experiments and RNA-expression studies. Given the phenotypic similarity of p63+/K5/14+ tumor cells to physiological counterparts in the normal breast and salivary duct epithelium and considering the fact that these cells may give rise to a number of different progenies with specific differentiation lineages, we suggest that this cell and its physiological differentiation potential provides an important ontogenetic key to a better understanding of these tumors.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-18.

Abstract P5-03-04: The meaning and significance of p63+/K5/14+ somatic stem cells of the normal breast salivary gland epithelium

Background: Somatic breast stem cells are the focus of intensive efforts worldwide not only at elucidating their nature and properties but also at increasing our understanding of proliferative diseases of breast. Despite the many important advances on stem cells in other organs, substantial uncertainties regarding the identity of somatic breast stem cells still hinder further advances and a conceptual approach in the field of physiological epithelial regeneration and corresponding tumors.

Material and Methods: For that reason, we performed an in situ Triple Immunofluorescence Lineage/Differentiation Tracing (isTILT) and qRT-PCR study of formalin-fixed breast tissues. We used basal (K5/K14), glandular (K7/K8/18), and epidermal-specific squamous (K10) keratins, the stem cell marker p63, and smooth muscle actin (SMA; myoepithelial marker) with the aim to trace the two cell lineages and define their cellular hierarchy. We investigated 5 cases of the breast and 5 cases of the salivary gland tissues.

Results: First of all, the breast gland contains p63 and K5/14 co-expressing progenitor cells observed in small clusters of 2-3 cells at the interface between myoepithelial and luminal layer of breast ducts. Interestingly, p63 is not preserved in luminal cells, rather the glandular differentiation involves down-regulation of p63 with the emergence of K5/14-positive glandular progenitors and furthermore sequential modulation of keratins with a shift from basal keratins K5/14 to glandular keratins K8/18. In contrast, p63 was preserved and co-expressed with both K5/14 and myoepithelial markers such as SMA in the myoepithelial lineage. In contrast p63+/K5/14+ cells could not be found in terminal ducts-lobular units, rather these structures are characterized by K5/14+/K8/18+ intermediary and K8/18+ glandular cells. Interestingsly, the same cellular make up and principles were observed in striated and excretory ducts of salivary glands. In contrast, intercalated ducts and acini contained only K7+ glandular and p63+/SMA+/K5/14+ myoepithelial cells, but lacked K5/14+/K7+ intermediare cells.

Conclusion: Here, we localized for the first time a group of cells with this unique p63+/K5/14+ phenotype in the normal breast duct epithelium. Using isTILT experiments and qRNA analyses with p63 as a stem cell marker, we demonstrated these p63+/K5/14+ physiological progenitors residing at the interface of myoepithelial and luminal cells of the breast ducts. From our isTILT-findings, we suggest that in the glandular lineage of breast ducts, p63 is down-regulated with a sequential shift in keratin expression from basal keratins K5/14 to glandular keratins K7 and/or K8/18 as the cells mature. Interestingly terminal ducts-lolular units are devoid of p63+/K5/14+ progenitor cells. In salivary glands, these p63+/K5/14+ progenitors are found to sit in a basal position adjacent to the basement membrane of striated and excretory ducts. We conclude that p63+/K5/14+ progenitors and the glandular/myoepithelial lineage differentiation are tightly regulated and occur in defined contexts of tissue physiology.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-03-04.

Abstract P6-01-08: Keratin 5/14+ Progenitor Cell Concept of Breast Epithelium: Revisited

Background: The role of keratin (K) 5/14+ progenitor cells as precursor cells of the breast epithelium has been demonstrated both in culture and in situ. This cell model opens a new field in which distinct cell subtypes can be evaluated in terms of their functional state and describes how these cells may give rise to either benign or malignant tumors. Material and Methods: In this study, we used modern triple immunofluorescent labeling experiments to visualize directly different cell types and their functional status applying, as a reference, antibodies to basal (K5/14) and glandular (K8/18) keratins and a myoepithelial marker in combination with antibodies to ER-alpha, Ki67, BCL2 and c-kit in normal resting breast epithelium and in 30 cases of ductal neoplasia of low grade pathway and 8 cases of epithelial hyperplasia. Different cell types were quantitatively assayed. Immunolabeling results were supported with quantitative real time PCR.

Results: Basal and glandular keratins in the normal luminal breast epithelium were found to be expressed in highly specific sequential pattern from K5/14+progenitor cells to K8/18+ glandular cells. ER alpha, Ki67, c-kit and BCL2 were found differentially expressed in various subtypes of the breast epithelium, ER-alpha was expressed only in a subset of glandular cells thus subdividing the glandular lineage into ER-alphapositive and negative subcategories. The highest Ki67-proliferation was found in phenotypically glandular cells which are ER-alpha negative. BCL2 was characteristically co-expressed in glandular cells, whereas c-kit was detected mainly in earlier glandular cells. Benign epithelial hyperplasia showed a striking similarity to normal luminal breast epithelium. In terms of functional differentiation these cells disclosed the same ER-alpha, BCL2 and c-kit expression as that observed in normal epithelium. In contrast to UDH, all types of low-grade in-situ neoplasia of ductal type are characterized by expression of only glandular keratins 8/18. The tumour cells co-expressed ER-alpha, BCL2 and Ki67. On the other hand, c-Kit was not expressed in these lesions.

Discussion: From our data, it is evident that basal (K5/14) and glandular keratins (K8/18) are expressed in highly specific hierarchical patterns related to stage of glandular differentiation. This phenotypic hierarchy of cells is furthermore bound to a differential expression of ER, Ki67, c-kit and BCL2 in a very specific manner. Usual ductal hyperplasia disclosed a striking similarity to the resting glandular epithelium. In contrast, all types of low grade intraepithelial neoplasia not only retain the keratin patterns of their (normal) glandular counterpart but show the same functional differentiation with a positive expression of ER and BcL2 and lack of c-kit. This similarity indicates that these lesions may derive from more differentiated glandular cells of the lobular breast epithelium. The data presented here confirm that the K5/14+ progenitor cell concept provides important insight into the functional nature of normal breast epithelium and in proliferative diseases.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-01-08.

Abstract P6-01-07: New Concept of the Histogenesis of Salivary Gland-Like Tumors of the Breast as K5/14-Positive Progenitor Lesions

Background: As an exocrine gland, the breast can manifest tumors with similar morphological features as the salivary gland. Defining the cellular identity of such tumours is one of the keys to a better understanding how these tumors evolve and grow.

Material and Methods: We analyzed corresponding counterpart tumors such as pleomorphic adenoma, basal-cell adenoma, adenoid cystic carcinoma, adenosquamous carcinoma, and adenomyoepithelial tumors. With basal keratins, K5 and K14, as a reference, we have used antibodies against glandular keratins 8/18, myoepithelial markers (SMA, SMMHC, CD10) and functional markers such as Ki67 to investigate their expression in breast and salivary gland tumors. We used modern triple immunofluorescence labeling for simultaneously detecting these proteins in tumour cells with the obj ective to define different cell lineages and their differentiation status. The data were corroborated by real time PCR analysis of cRNAs for these proteins. Drawing parallels between tumors of the breast and salivary gland must help to unravel the nature of these lesions in these two organs. Results: All salivary gland tumors were found to contain progenitor cells with expression of basal keratins 5/14. They also showed an orderly sequential expression of basal keratins 5/14 and lineage specific proteins K8/18 for the glandular differentiation, myoepithelial markers for the myoepithelial differentiation, and K10 and vimentin for heterologeous squamous and mesenchymal differentiation, respectively, indicating the evolution of lineage specific cells from K5/14+ precursor cells. Normal breast and salivary gland epithelium showed striking similarities in their cellular composition, as both glands contain K5/14-positive progenitor cells which differentiate to glandular (K8/18+) or myoepithelial (SMA+;SMMHC+, CD10+) cells via intermediary cells, with a sequential expression of basal and lineage specific proteins. However, there are striking differences in the proliferative activity of different subtypes of cells — for instance, of precursor cells and differentiating glandular cells in both organs, which might be the source of differences in incidence of these tumors in both glands.

Discussion: In this study we show that: (i) with few exceptions, salivary gland-like tumours represent K5/14- positive tumors with a glandular and/or myoepithelial differentiation and/or with a heterologeous (for example squamous) differentiation; (ii) the corresponding counterpart tumors both of breast and salivary gland are identical. As the constituent cells of all these tumors mimic the cellular composition and differentiation capabilities of progenitor cells both of breast and salivary gland epithelium, we believe that these tumors may originate from immature, probably pluripotent K5/14+ progenitor cells. Differences in proliferative activity of the various subtypes of cells in both organs might be an explanation for their rather different incidences.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-01-07.

Protein tyrosine phosphatase kappa and SHP-1 are involved in the regulation of cell-cell contacts at adherens junctions in the exocrine pancreas

BACKGROUND

We have previously shown that cell contacts between pancreatic acinar cells dissociate early in pancreatitis and that this is a prerequisite for the development of pancreatic oedema. Here we studied the underlying mechanism.

METHODS

Employing experimental caerulein induced pancreatitis in vivo and isolated pancreatic acini ex vivo, in conjunction with protein chemistry, morphology, and electron microscopy, we determined whether cell contact regulation in the pancreas requires or involves: (1) changes in cadherin-catenin protein expression, (2) tyrosine phosphorylation of adhesion proteins, or (3) alterations in the actin cytoskeleton.

RESULTS

During initial cell-cell contact dissociation at adherens junctions, expression of adhesion proteins remained stable. At time points of dissociated adherens junctions, the cadherin-catenin complex was found to be tyrosine phosphorylated and internalised. The receptor type protein tyrosine phosphatase (PTP)kappa was constitutively associated with the cadherin-catenin complex at intact cell contacts whereas following the dissociation of adherens junctions, the internalised components of the cadherin-catenin complex were tyrosine phosphorylated and associated with the cytosolic PTP SHP-1. In isolated acini, inhibition of endogenous protein tyrosine phosphatases alone was sufficient to induce dissociation of adherens junctions analogous to that found with supramaximal caerulein stimulation. Dissociation of actin microfilaments had no effect on adherens junction integrity.

CONCLUSIONS

These data identify tyrosine phosphorylation as the key regulator for cell contacts at adherens junctions and suggest a definitive role for the protein tyrosine phosphatases PTPkappa and SHP-1 in the regulation, maintenance, and restitution of cell adhesions in a complex epithelial organ such as the pancreas.

Expression of alpha1-adrenergic receptor subtypes in heart cell culture

Three alpha1-AR subtypes have been cloned so far and are designated as alpha1a, alpha1b,, and alpha1d. Organ-specific distribution pattern and subtype-specific effects are known but not fully understood. To address a cell-type specific expression pattern in the heart we investigated expression pattern of alpha1-AR subtypes on RNA- and protein-level in heart tissue, cultured cardiomyocytes and non-myocytes of the rat. Each alpha1AR-subtype mRNA was present in neonatal and adult rat heart culture but the relative distribution pattern was significantly different. While the alpha1a-AR subtype is preferentially expressed in adult cardiomyocytes, the alpha1b-AR subtype was preferentially expressed in the non-myocyte cell fraction. The RT-PCR results were confirmed by Western-blotting (alpha1b) and immunocytochemical studies. Incubation with an alpha1-agonist (phenylephrine) for 72 h led to a significant reduction of the alpha1b-AR in neonatal heart cell culture on both mRNA and protein level. In contrast, incubation with an alpha1-antagonist (prazosin) induced a 1.6 fold upregulation of the alpha1a-AR mRNA without significant effects on radioligand binding and functional assay. The results indicate a distribution pattern of the alpha1-AR subtype which is specific for cell type and ontogeny of the rat heart and may be regulated by adrenergic agents.

Chlamydia pneumoniae DNA in non-coronary atherosclerotic plaques and circulating leukocytes

Earlier studies have associated atherosclerosis with Chlamydia pneumoniae infection. C. pneumoniae may circulate via monocytes and migrate into plaques by leukocyte infiltration; however, detection is difficult. We developed a novel polymerase chain reaction (PCR) method to test the hypothesis that C. pneumoniae DNA in circulating leukocytes is correlated with C. pneumoniae DNA in plaque material and that C. pneumoniae copy number is associated with disease severity. We obtained plaques from 130 patients who underwent surgery for carotid stenosis, aneurysm, or peripheral vascular disease. From 60 patients and 51 normal control subjects we also obtained circulating leukocytes. The C. pneumoniae 16 S rRNA gene was amplified with a highly specific quantitative PCR protocol relying on the TaqMan technology. Immunohistochemistry was performed with antibody against the C. pneumoniae outer membrane protein. C. pneumoniae DNA was present in 25% of atherosclerotic plaques and 20% of circulating leukocytes from patients. The copy number was not correlated with disease severity. C. pneumoniae DNA was more common in younger patients and smokers. C. pneumoniae antibody titers, C-reactive protein, fibrinogen, leukocyte count, cholesterol, and diabetes were not associated with C. pneumoniae DNA. Although immunostaining of plaque and PCR results were highly correlated, we found no relationship between C. pneumoniae DNA in plaques and that in circulating leukocytes. Finally, 13% of normal control subjects had positive leukocytes; however, their copy number was significantly lower than that of the patients. C. pneumoniae DNA is frequent in atherosclerotic plaques and is correlated with positive immunohistochemistry. C. pneumoniae DNA may also be found in circulating leukocytes; however, infected leukocytes and plaques do not coincide. Serology is unreliable in predicting C. pneumoniae DNA. Smoking increases the risk of harboring C. pneumoniae DNA. Our results do not suggest that either test for antibodies or C. pneumoniae DNA from leukocytes in blood is of value in predicting infected plaques.

Immunocytochemical visualization of transfected DNA in cultured cells

Nonviral transfection is one of the modern methods for the incorporation of foreign genes into cells. This process involves uptake of foreign genetic material by the cell and further trafficking through the cytoplasm to the nucleus. Elucidation of cytoplasmic pathways of transfection complexes can be useful to improve already existing gene delivery systems or to establish new systems. To monitor transfection complexes in the cell during transfection, we elaborated a method for the visualization of transfection complexes by introducing digoxigenin-labelled nucleotides into foreign DNA followed by detection of digoxigenin label with the use of antibodies directed against digoxigenin. This procedure allowed the visualization of DNA in transfection complexes and to monitor these complexes in cells during transfection.

Differential expression of protein kinase C isoforms in streptozotocin-induced diabetic rats

BACKGROUND

The cellular effects of hyperglycemia are mediated by protein kinase C (PKC). However, PKC consists of several distinct isoforms, and their contribution to the pathogenesis of diabetic complications in different organs is not clear. We investigated the expression and translocation of PKC isoforms alpha, betaI, betaII, delta, epsilon, and zeta in kidney, heart, and aorta from diabetic rats.

METHODS

Hyperglycemia was induced with streptozotocin (70 mg/kg) in the rat. After four weeks, PKC isoform expression was assessed by Western blot after tissue fractionation and by immunohistochemistry.

RESULTS

Streptozotocin increased blood glucose from 117.0 +/- 3.6 to 510.0 +/- 19.4 mg/dl (N = 8, P < 0.01) and induced albuminuria. PKC isoforms alpha, beta, delta, epsilon, and zeta were all detected in control animals. Western blot showed increased PKC alpha expression in kidney and heart (160% and 170%, respectively). PKC betaI, betaII, and delta expression was not influenced by hyperglycemia. PKC zeta was decreased in diabetic animals in both tissues by 60%. The membrane association of PKC alpha and PKC epsilon was increased; however, the relative amount of PKC in the particulate fraction was not influenced by hyperglycemia. Immunohistochemistry revealed a marked increase in PKC alpha immunoreactivity in renal glomeruli and interstitial capillaries, cardiac capillaries, and skeletal muscle, as well as in the endothelial cells of larger arteries. PKC beta showed a small decrease in the glomeruli. PKC epsilon was increased in renal tubules in diabetic rats but was decreased in the myocardium. PKC zeta was expressed in both myocardial and glomerular cells but was decreased during hyperglycemia. Our results demonstrate that PKC isoforms are differentially regulated in kidney and heart in diabetes. High glucose increases PKC alpha expression, whereas PKC zeta is down-regulated. The finding that PKC alpha is mostly increased in endothelial cells supports a role for PKC alpha in functional endothelial disturbances observed in diabetes.