Monoclonal antibodies specific for subsets of epidermal keratins: biochemical and immunocytochemical characterization--applications in pathology and cell culture

A novel magnetic bead-based assay with high sensitivity and selectivity for analysis of telomerase in exfoliated cells from patients with bladder and colon cancer

Telomerase activity is elevated in more than 85% of cancer cells and absent in most of the normal cells and thus represents a potential cancer biomarker. We report its measurement in colon and bladder cancer cells captured using antibody-coated magnetic beads. The cells are lysed and telomerase activity is detected using a biosensor assay that employs an oligonucleotide containing the telomerase recognition sequence also covalently coupled to magnetic beads. Telomerase activity is measured by the incorporation of multiple biotinylated nucleotides at the 3'-end of the oligonucleotide strands during elongation which are then reacted with streptavidin-conjugated horseradish peroxidase. A luminescent signal is generated when hydrogen peroxidase is added in the presence of luminol and a signal enhancer. LOD experiments confirm sensitivity down to ten cancer cell equivalents. The telomerase assay reliably identified patient samples considered by an independent pathological review to contain cancer cells. Samples from normal healthy volunteers were all telomerase negative. The assay, which is amenable to automation, demonstrated high sensitivity and specificity in a small clinical cohort, making it of potential benefit as a first line assay for detection and monitoring of colon and bladder cancer.

The phenotypic spectrum of basal-like breast cancers: a critical appraisal

There are 2 well-recognized cell populations lining the mammary duct system: the epithelial cells lining the lumen and the myoepithelial cells surrounding them. The mammary stem cell, a putative third cell type, has not yet been well characterized. It is not established whether the putative stem cell expresses the full complement, a subset, or none of the markers of normal epithelial and/or myoepithelial cells. However, it is likely that they would have distinctive markers of their own; whether these are retained or lost in their neoplastic progeny is unknown. All 3 cell types may theoretically undergo malignant transformation. Until recently, however, nearly all attention has been focused on carcinomas of epithelial derivation/differentiation. The advent of oligonucleotide and cDNA microarrays has facilitated gene expression profiling of breast cancers, revealing molecular subclasses that may be prognostically relevant. One such subclass, the basal-like breast carcinomas, has been found in numerous independent datasets to be associated with a comparatively worse overall and disease-free survival. These cancers show expression of molecules characteristic of the normal myoepithelial cell, such as basal cytokeratins, and reduced expression of estrogen receptor-related and Erb-B2-related genes and proteins. The classifier genes that formed the basis for the delineation of basal-like carcinomas were derived from datasets that were composed predominantly of ductal type cancers. Therefore, the clinical significance of a basal-like gene expression or immunohistochemical profile in the other breast cancer subtypes is presently unknown. Herein, we evaluate in detail the current state of knowledge on the pathologic features of breast carcinomas classified as basal-like by immunohistochemical and/or gene expression profiling criteria, with an emphasis on their full phenotypic spectrum and also previously underemphasized areas of heterogeneity and ambiguity where present. There seems to be a phenotypic and biologic spectrum of basal-like or myoepithelial-type carcinomas, just as there is a wide range among tumors of luminal epithelial derivation/differentiation. It is critical to promote lucid morphologic definitions of the molecular subtypes, if this information is intended for use in targeted therapies and patient management.

Ultrastructure and three-dimensional imaging of epimyoepithelial islands in benign lymphoepithelial lesions

Benign lymphoepithelial lesions of the salivary glands associated with Sjögren's syndrome are characterized by extensive infiltration of lymphoid cells, atrophy of acini and the presence of so-called epimyoepithelial islands. This report describes ultrastructural and three-dimensional reconstructive studies of epimyoepithelial islands performed at Tokyo Women's Medical College. Ultrastructural examination showed that these islands are composed mainly of epithelial cells containing intermediate filaments and/or tonofilament bundles, scattered lymphocytes and plasma cells. Myoepithelium-like cells containing myofilaments were sometimes found in the peripheral portion of the myoepithelial islands. Also, mitotic figures were rarely found in these islands. Three-dimensional reconstructive study revealed that the epimyoepithelial islands are not isolated cell clusters but are continuous hypertrophic duct-like structures. These results suggest that the epimyoepithelial islands are derived from proliferating duct epithelial cells, especially those of large peripheral ducts.

Expression of human cytokeratin 14 in normal, premalignant and malignant oral tissue following isolation by plaque differential hybridisation

Differences in gene transcription between RNA samples extracted from oral normal and squamous cell carcinoma (SCC) tissue were examined using the technique of cDNA library differential plaque screening. A differentially expressed transcript was selected on the basis of it being under-expressed in the cancer tissue and was identified, using DNA sequencing, as cytokeratin 14. The level of cytokeratin 14 transcription in RNA samples extracted from a range of oral SCC and normal tissue, as well as "white patch" lesions, was then investigated. Cytokeratin 14 appeared to be significantly under-expressed in oral cancer specimens studied compared to normal and white-patch tissue (P < 0.01). The trend for higher levels of cytokeratin 14 transcription in the dysplastic "white patch" samples compared to that observed for the malignant tissue (P < 0.05) suggests that the decrease in cytokeratin 14 transcription is a late event in the carcinogenic pathway.

CHILD Syndrome: Lack of Expression of Epidermal Differentiation Markers in Lesional Ichthyotic Skin

Congenital hemidysplasia with ichthyosiform erythroderma and limb defects (CHILD) syndrome is a rare genetic disorder. The epidermal abnormalities associated with the unilateral ichthyosis have previously been examined only by morphology. In order to describe these abnormalities more completely we analyzed the expression of markers of epidermal differentiation (keratins and filaggrin), grew keratinocytes in culture, and correlated the results with ultrastructural features. Expression of all differentiation markers was significantly reduced or absent, whereas keratins K5 and K14 and keratins K6 and K16 were strongly expressed in lesional epidermis, suggesting that basal cell keratin expression was not down-regulated as in normal epidermis and that lesional keratinocytes mature via an abnormal pathway. When removed from the tissue and grown in culture, keratinocytes from lesional and non-lesional biopsies had similar phase microscopic morphology as well as keratin and profilaggrin expression, in contrast to the extreme differences in vivo. Lesional keratinocytes also had similar contents of keratin filaments and keratohyalin, but showed abnormal accumulation of intercellular vesicles and debris and altered cell-cell and cell-substratum interaction. Comparison of the results in tissue and in culture suggests that systemic or dermal factors influence the abnormal structural protein expression and ichthyosiform epidermal differentiation seen in CHILD syndrome, but that lesional keratinocytes maintain abnormalities in the secretion and accumulation of extracellular material in vitro similar to the lesional tissue in vivo.

Changes in cytokeratin expression in gingiva during inflammation

Cytokeratins represent specific markers of certain pathways of epithelial differentiation. The purpose of this study was to describe the alterations of cytokeratin pattern and topographical distribution of individual cytokeratins in inflamed gingiva. Five healthy and 15 inflammatory samples of human gingiva were studied. From each biopsy, cryostat sections allowed histological staining, immunofluorescence microscopy using a battery of monoclonal antibodies to cytokeratins, and gel electrophoresis. The results show marked differences in cytokeratin expression by healthy epithelia as compared with inflamed gingiva: in suprabasal cell layers there were reductions or disappearance of cytokeratins 1, 2 and 10, 11--specific for terminal differentiation--and increased expression of cytokeratins 4 and 13, as well as--in basal and parabasal cell layers--expression of cytokeratin 19. These alterations might represent an adaptation of involved epithelia to the alterations brought about by the inflammatory process.

Prenatal development of human major salivary glands and immunohistochemical detection of keratins using monoclonal antibodies

The major salivary glands were examined from 69 human fetuses ranging from 10 to 40 weeks of gestation. Prenatal growth curves of developing salivary glands could be established by histological scoring, and development was divided into the early developmental stage (EDS) from 10 to 18 weeks, early intermediate developmental stage (EIDS) from 19 to 24 weeks, late intermediate developmental stage (LIDS) from 15 to 32 weeks, late developmental stage (LDS) from 33 to 40 weeks. Characteristic morphogenesis and cytodifferentiation occurred in glandular duct cells during the period of EIDS and LIDS. In the LDS, acini and ducts of the salivary glands histologically developed into a mature state similar to adult glands. Immunohistochemical staining with monoclonal antibodies (MoAbs) PKK1, KL1, K8.12, K8.13, K4.62, RPN 1160, 1162, 1163, 1164, and 1165 was performed. During the fetal period, keratin expression as revealed by MoAbs PKK1, KL1, K8.12 was well established, and the staining pattern for each of these antibodies was comparable. Other antibodies showed rare or negative staining except K8.13 which had a diffuse, non-specific staining pattern. Accordingly, the proliferation and cytodifferentiation of fetal stage keratin staining in ductal cells as revealed by MoAbs PKK1, KL1, and K8.12 showed a heterogenic distribution in both luminal and basal cells. It is a characteristic finding that the cytodifferentiation of ductal luminal cells precedes ductal basal cells. Ductal basal cells stained with MoAb K8.12 and show heterogeneity of keratin distribution continuously until the full term of gestation. The keratin staining of oral epithelium was also examined to compare with distribution of salivary gland ductal cells and oral epithelial cells. In the present study, the developmental sequence of salivary gland cells and the immunohistochemical properties of keratin proteins in these cells were described in relation to the histogenesis of salivary gland tumours.

Expression of keratin 5 as a distinctive feature of epithelial and biphasic mesotheliomas. An immunohistochemical study using monoclonal antibody AE14

In previous biochemical analyses, keratin 5 (Mr 58,000) has been detected in most mesotheliomas with epithelial component but not in pulmonary adenocarcinomas (Blobel et al., Am J Pathol 121: 235-247, 1985). In the present study, we have characterized a monoclonal antibody, AE14, as being selectively specific for keratin 5 (apart from the reactivity with certain hair proteins) as shown by immunoblotting of gel-electrophoretically separated proteins from various tissues. Immunohistochemical screening of a variety of normal human tissues, using immunoperoxidase microscopy on cryostat sections, revealed the binding of this antibody to the basal, immature cells of stratified squamous epithelia, to basal cells of pseudostratified epithelia, to some myoepithelial cells, thymic reticulum cells, certain pancreatic duct cells, as well as a variable subpopulation of mesothelial cells of the pleura and the peritoneum. In 12/13 epithelial and biphasic mesotheliomas of the pleura, heterogeneous but extended staining with antibody AE14 was seen whereas 21 pulmonary adenocarcinomas were negative or, in six of these cases, showed staining of only a few cells. Among carcinomas from other sites, colonic adenocarcinomas and renal cell carcinomas were negative whereas limited staining was found in some pancreatic adenocarcinomas. It is suggested that antibody AE14 may be useful, as a defined polypeptide-specific reagent, in the histologic distinction between mesotheliomas and most adenocarcinomas. Furthermore, the expression patterns of keratin 5 as detected by antibody AE14 in various normal and malignant epithelial tissues are discussed, particularly their relation to processes of squamous metaplasia and their indication of phenotypic tumor heterogeneity.

Multiple expression of keratins, vimentin, and S-100 protein in pleomorphic salivary adenomas

Immunohistochemical staining for S-100 protein and the intermediate filaments keratin and vimentin, was made in 41 salivary adenomas. In pleomorphic adenomas, great heterogeneity in the staining, as well as multiple and co-expressions of these proteins were found in the outer tumor cells of tubulo-ductal structures and modified myoepithelial cells, but not in the luminal tumor cells. All the outer tumor cells stained for S-100 protein, 97% for K8.12 keratin and 85% for vimentin. Of these cells, 29% showed multiple expression of K8.12 keratin, vimentin, and S-100 protein, and 17% showed co-expression of K8.12 and S-100 protein. Modified and neoplastic myoepithelial cells showed similar expressions of these proteins to those of outer tumor cells; myoepithelioma cells displayed the most complicated pattern, being positive for KL1, PKK1, and K8.12 keratins, vimentin and S-100 protein. In luminal tumor cells there was a heterogeneous expression of KL1 and PKK1 in 82%, and of KL1, PKK1, and K8.12 in only 14.7%. Based on the immunohistochemical findings obtained with different monoclonal antibodies in pleomorphic salivary adenomas, outer tumor cells may be derived from ductal basal cells and luminal tumor cells from intercalated duct cells.

Unusual patterns of keratin expression in the overlying epidermis of patients with dermatofibromas: biochemical alterations in the epidermis as a consequence of dermal tumors

Dermatofibromas are frequently associated with acanthosis of the overlying epidermis. Using monospecific antisera and cRNA probes, we have examined the pattern of expression of keratin and keratin mRNA in the affected epidermis of patients with these dermal tumors. Our studies reveal several abnormalities in keratin expression within the thickened areas of overlying epidermis. In two of 15 patients, we detected K6 and K16, keratins which are frequently associated with epidermal diseases of hyperproliferation but are not present in normal epidermis. In both cases, K6 and K16 were found in suprabasal layers, similar to that seen for psoriasis and squamous cell carcinomas. Expression of K6 and K16 in skin samples from patients with dermatofibromas seemed to be dependent upon how near was the tumor to the overlying epidermis, and possibly upon the degree of cellularity within the tumor mass. A second aberration in keratin expression, and one which did not appear to be linked to K6/K16 expression, was the altered expression of the basal epidermal keratin K14. Expression of this keratin and its mRNA was variable, often extending into multiple suprabasal layers and including both basal-like and squamous-like cells. In contrast to the expression of K6/K16, aberrant expression of K14 was a relatively frequent event, occurring in greater than 70% of the dermatofibroma skin samples examined. These observations provide the first biochemical evidence in support of previous morphologic studies, indicating that alterations in epidermal differentiation can occur as a consequence of dermal skin tumors.

Expression of membrane glycoproteins in normal keratinocytes and squamous carcinoma cell lines

Con A acceptor glycoproteins were analyzed by 2D-PAGE and 125I-Con A overlay in three squamous carcinoma cell lines and compared with those in the simian virus (SV40)-transformed keratinocyte cell line SVK-14 and in normal keratinocytes. The majority of the glycoproteins identified by this technique were expressed at similar levels in all of the cells examined, independent of the culture conditions used. A cell surface glycoprotein gp34 (MW 34 kDa, pI 5.1) was increased in the tumor cells compared with normal keratinocytes and expression varied with the culture density. Another glycoprotein, gp21 (MW 21 kDa, pI 6.3), was found to be increased in expression in normal keratinocytes and stratified hyperconfluent cultures of squamous carcinoma cell lines. This paper describes the potential of this technique to identify membrane glycoproteins which may be expressed as a function of proliferation or differentiation.

Heterogeneity of keratin expression in epithelial tumor cells of adenolymphoma in paraffin sections

Immunohistochemical expressions of keratin polypeptides detected by monoclonal antibodies were described in tumor cells of adenolymphoma, and the possibility of intercalated duct and ductal basal cells in the salivary glands being the progenitors was discussed. Basal cells in the tumor showed positive staining for keratin nos. 8, 13, 16, 18 and 19 detecting for monoclonal keratin antibodies (PKK 1, K 4.62, K 8.12, K 8.13), columnar tumor cells displayed strongly positive reactions with RPN 1164 and K4.62 suggesting keratin nos. 8 and 19. Great heterogeneity of distribution for keratin polypeptides was displayed by epithelial cells of adenolymphoma. Intercalated duct cells of normal salivary glands reacted with RPN 1164, RPN 1165, K 4.62 and K 8.13 monoclonal antibodies, which indicates the presence of keratins 8 and 19; and ductal basal cells reacted with PKK 1, K 4.62 and K 8.12, suggesting nos. 8, 13, 16, 18 and 19 keratins. Distribution of involucrin was variable in tumor epithelium of adenolymphoma, and was negative in the normal gland. The immunohistochemical distribution of keratin types between basal tumor cells of adenolymphoma and ductal basal cells of the normal salivary gland was compared.

Coexpression of keratin and vimentin in salivary pleomorphic adenomas

The coexpression of keratin and vimentin is described in 45 pleomorphic adenomas using an immunoperoxidase MAb method. Histopathologically, the outer layer of tubuloductal structures and peripheral tumor cells in solid masses, including modified or neoplastic myoepithelial cells, showed positive staining with monoclonal keratin antibody K8.12 and vimentin. This staining was found in the ratio of 10/26 (38.5%) in tubuloductal structures, 2/7 (28.6%) in peripheral tumor cells and 8/12 (66.7%) in modified myoepithelial cells. Concomitant staining of other keratin antibodies (PKK1, KL1) and vimentin did not exist. In addition, the ductal basal cells of normal salivary glands showed positive K8.12 labelling. The histogenesis of pleomorphic adenoma is discussed in relation to the differentiation of either ductal basal cells or ductal luminal cells from a single stem cell origin or the direct transformation of ductal basal cells to outer tumor cells and/or modified myoepithelial cells, both coexpressing K8.12 and vimentin.

Immunohistochemical expression of MAM-3 and MAM-6 antigens in salivary gland tumours

MAM-3 and MAM-6 antigens of human milk fat globule membrane were detected immunohistochemically in 93 cases of salivary gland tumours as well as in normal glands. The antigens were visualized in 10% formalin-fixed paraffin sections. MAM-3 (MoAbs 115G3, 67D11) antigen was distributed in intercalated and striated duct cells of the normal salivary glands, and in luminal tumour cells and squamous metaplastic cells of pleomorphic adenomas. In pleomorphic adenomas the frequency of positive staining with MoAb 67D11 (54/67; 80.6%) was higher than that with MoAb 115G3 (36/67; 53.7%). MAM-6 (MoAbs 115D8, 115F5) antigen was expressed in luminal and lateral borders of serous acinar cells and ductal of the normal glands, and also in luminal borders of tubulo-ductal and glandular structures of salivary gland tumours. Ductal basal cells were characterized by existence of positive staining for MAM-6 antigen, in adenolymphomas MAM-6 antigen was restricted to the basal tumour cells. Some mucous cells of mucoepidermoid tumours were stained specifically with MoAb 115G3, and epidermoid cells of mucoepidermoid carcinomas manifested MAM-6 antigen staining. Immunohistochemical localization of MAM-6 antigen resembled that of epithelial membrane antigen (EMA) detected with MoAb.

Expression of low molecular weight cytokeratin proteins in laryngeal dysplasia

In twenty-three cases of laryngeal dysplasia frozen mucosal strips were examined with four monoclonal and one polyclonal keratin antibody. The expression of specific keratin polypeptides was studied in different degrees of dysplasia with regard to the subunits expressed in normal and carcinomatous laryngeal epithelium in the same patient. An alteration in the expression of the subunits of cytokeratin in favour of low molecular weight polypeptides takes place in the transformation of normal epithelium to squamous cell carcinoma. This alteration seems to occur at an early stage and is present already in mild dysplasia. The results suggest that with a suitable antibody dysplastic laryngeal epithelium can be distinguished from normal epithelium, and also on some cases, mild dysplasia from more severe degrees of dysplasia. CAM 5.2, which identifies lower molecular weight cytokeratin proteins (50, 43 and 38 kD), is such an antibody, and can be a valuable diagnostic aid in the histological interpretation of laryngeal dysplasia.

Immunohistochemical analyses of autoimmune sialadenitis in man

The immunoreactivity pattern for different monoclonal antibodies to cytokeratins and to vimentin in epimyoepithelial islands typical for glands of patients with Sjögren's syndrome has been compared with that of normal parotid gland tissue. Two types of epithelial island cells were observed: one had an intermediate filament protein pattern similar to that of ordinary duct epithelial cells of normal parotid gland. The other had an intermediate filament protein pattern typical of myoepithelial and/or basal duct cells in normal glands. Thus, we conclude that the islands are composed of a mixed population of gland cells on the basis of their content of cytokeratins or of cytokeratins and vimentin. These cells might originate from pluripotential reserve cells or from ordinary duct, myoepithelial and/or basal duct cells which may have undergone metaplasia.

Use of monospecific antisera and cRNA probes to localize the major changes in keratin expression during normal and abnormal epidermal differentiation

We report here the isolation and characterization of three antisera, each of which is specific for a single keratin from one of the three different pairs (K1/K10, K14/K5, K16/K6) that are differentially expressed in normal human epidermis and in epidermal diseases of hyperproliferation. We have used these antisera in conjunction with monospecific cRNA probes for epidermal keratin mRNAs to investigate pathways of differentiation in human epidermis and epidermal diseases in vivo and in epidermal cells cultured from normal skin and from squamous cell carcinomas in vitro. Specifically, our results suggest that: (a) the basal-specific keratin mRNAs are down-regulated upon commitment to terminal differentiation, but their encoded proteins are stable, and can be detected throughout the spinous layers; (b) the hyperproliferation-associated keratin mRNAs are expressed at a low level throughout normal epidermis when their encoded proteins are not expressed, but are synthesized at high levels in the suprabasal layers of hyperproliferating epidermis, coincident with the induced expression of the hyperproliferation-associated keratins in these cells; and (c) concomitantly with the induction of the hyperproliferation-associated keratins in the suprabasal layers of the epidermis is the down-regulation of the expression of the terminal differentiation-specific keratins. These data have important implications for our understanding of normal epidermal differentiation and the deviations from this process in the course of epidermal diseases of hyperproliferation.

Characterization of cytoskeletal proteins in basal cells of human parotid salivary gland ducts

From previous immunofluorescent, immunohistochemical and ultrastructural studies, myoepithelial cells have been reported to be absent from the striated and excretory ducts of human salivary gland. Yet recently, certain anti-cytokeratin monoclonal antibodies which specifically label the myoepithelium of salivary gland acini and intercalated ducts have also been found to stain basally situated cells in both striated and excretory ducts. In this study, we have used eight samples of normal human parotid gland (methacarn-fixed and frozen sections) to establish if basal cells of striated and excretory ducts have the cytoskeletal protein complement (actin and cytokeratins) of myoepithelial cells. Using a muscle-specific actin, HHF35, not only is the myoepithelium of acini and intercalated ducts stained in all cases, but stellate and spindle shaped cells are also detected all along the inter- and intralobular striated ducts in four of the eight examples. With double-labeled frozen sections and fluorescent microscopy, the actin-specific probe, phalloidin, and the myoepithelial-selective anti-cytokeratin 14 antibody, 312C8-1, confirm that the striated duct does have a population of basal cells with the cytoskeletal protein make-up of myoepithelium. The monoclonal antibody 8.12 (specific for cytokeratin 13 and 16) also stains some basal cells of striated and excretory ducts, as well as luminal cells of ducts at all levels, but does not label the myoepithelium of acini and intercalated ducts. Both the anti-cytokeratin antibodies and the actin-detecting mechanisms reveal that the basal cell population of striated and excretory ducts is more heterogeneous, and likely functionally more complex, than has been realized previously. Such findings are not in agreement with certain aspects of current theories of the histogenesis of salivary gland tumours.

Cytoskeletal components of lymphoid organs. I. Synthesis of cytokeratins 8 and 18 and desmin in subpopulations of extrafollicular reticulum cells of human lymph nodes, tonsils, and spleen

Using light and electron microscopic immunolocalization with antibodies to cytoskeletal proteins, we have characterized the nonlymphoid cells of various human lymphoid organs (lymph nodes, tonsils, spleen). In all these tissues, the lymphoid follicles contain a three-dimensional meshwork of "dendritic reticulum cells" which are characterized by the presence of desmosomal junctions, as demonstrated by positive punctate staining with antibodies to the desmosome-specific proteins desmoplakin I and desmoglein, and by intermediate-sized filaments (IFs) of the vimentin type only. In contrast, the extrafollicular regions are characterized by an extended meshwork of other types of reticulum cells, which also contain vimentin IFs but lack desmosomal proteins. In addition, a considerable, although variable proportion of these extrafollicular reticulum cells forms IFs containing cytokeratins 8 and 18 and/or desmin-containing IFs. The occurrence of cytokeratins 8 and 18 in lymph nodes has also been shown by gel electrophoresis and immunoblotting. Results of double-label immunolocalization indicate that some of the extrafollicular reticulum cells coexpress all three kinds of IF protein. A large proportion of these cells also synthesizes another marker of myogenic differentiation, i.e., the isoform of alpha-actin specific for smooth muscle. This proportion includes some cells that are negative for desmin. Comparison of the distribution of cells expressing cytokeratins and/or desmin with that of reticulum cells showing strong alkaline phosphatase activity (as a marker for the so-called "fiber-associated (fibroblastic) reticulum cells") suggests that the former represent a subset of the latter. The biological meaning of these different patterns of expression in reticulum cells and of the resulting cell-type heterogeneity as well as possible implications of these observations for tumor diagnosis, notably of lymph-node metastases and lymphomas, are discussed.

Keratin protein identification in dimethylbenzanthracene-induced hamster cheek-pouch squamous cell carcinomas

Individual keratin proteins were identified in 10 DMBA induced squamous cell carcinomas (SCC) of the hamster cheek pouch. SDS-polyacrylamide gel electrophoresis of water-insoluble cytoskeletal extracts from the tumor tissue demonstrated alterations in the protein distribution normal for the site. Immunoblot analysis with a broad spectrum polyclonal antikeratin antiserum identified the keratins in the preparations and confirmed changes in their distribution in the tumor preparations. The major keratin species for all the tumor tissues ranged in molecular weight from 45 to 57kd. The normal tissues had keratins with molecular weights from 45 to 73kd. The absence of high molecular weight keratins was a prominent feature in all the cancers. The histologic appearance of the tumors was varied but the distribution of the keratins was not correlated with the various histologies. The results demonstrate that changes in keratin gene expression occur in DMBA-induced cheek-pouch carcinomas but the precise alterations in the keratin proteins from those seen normally are not predictable.

Analysis of differentiation antigens on normal and carcinogen-altered rat epithelial cells in vivo and in culture

Two murine monoclonal antibodies, 3BG8 and 9BG8, which were raised against a rat tracheal squamous-cell-carcinoma cell line, recognize cell-surface antigens on normal rat squamous epithelium (skin, esophagus, vagina, and cornea) as well as on carcinogen-exposed, immortalized, rat tracheal epithelial cells. Monoclonal antibody 3BG8 binds to a 115-kilodalton cell-surface protein on undifferentiated basal cells of the epithelium, while the binding of the other antibody, 9BG8, occurs in both differentiated and undifferentiated populations of normal squamous epithelium and squamous cell carcinomas. Undifferentiated tracheal carcinomas bound only the 3BG8 antibody. No binding of either antibody was detected on normal tracheal mucociliary epithelium. Only under conditions that induce squamous differentiation of rat tracheal epithelium was binding of 3BG8 and 9BG8 detected. For reasons which are not clear at present, 9BG8 dramatically inhibits the growth of normal tracheal and esophageal cells in primary culture, whereas only 3BG8 affects the growth of carcinogen-altered tracheal cell lines. Based on antigen characterization and distribution, it is concluded that the 3BG8 and 9BG8 epitopes are localized on differentiation antigens which differ from others that have been previously described.

Potential applications of anti-keratin antibodies in oral diagnosis

Recent progress in understanding the biology of keratins together with the development of monoclonal antibodies to individual keratin proteins provide the foundation for studying keratin expression in normal and pathological oral epithelia. Areas of oral pathology in which the examination of epithelial keratin profiles may yield information of potential diagnostic value are discussed. Examples of altered keratin expression in epithelial dysplasia, oral cancer and odontogenic cysts and tumours are presented. Immunocytochemical demonstration of individual keratins can clarify the composition of complex epithelia and may help to establish epithelial lineage or indicate progression changes in tumours. Some problems in the application and interpretation of keratin immunocytochemistry are also considered.

Biological studies of ten human squamous carcinoma cell lines: an overview

Ten cell lines established from surgical specimens of human squamous carcinomas of the tongue and larynx have been investigated with respect to their motility, ultrastructure, karyotypes, certain biochemical features, interaction with normal epithelial and stromal elements and capacity to infiltrate three-dimensional organoid systems. All the cell lines have maintained several morphological and biochemical characteristics indicating a common origin, although the extent to which each line displays this heritage is variable. The phenotypes of each of the individual cell lines are, however, notably stable. Data are provided for epithelial surface markers (including epidermal growth factor, EGF) and for the synthesis and release of prostaglandins and proteases which may be involved in invasive mechanisms. Encounters between the cell lines and organoid substrata (embryonic chick heart spheroids, human amnion, chick chorioallantoic membrane) are described: the results indicate a scale of invasiveness ranging from lack of penetration to full-thickness infiltration by cells showing various distinctive growth patterns. Correlation between in vitro and in vivo findings is discussed, and it is suggested that the biological heterogeneity of the lines may reflect inherent properties of the original carcinoma cell populations which are more distinctly expressed in vitro.

The identification of myoepithelial cells in human salivary glands. A review and comparison of light microscopical methods

Myoepithelial cells have frequently been implicated in salivary gland tumour histogenesis. A major problem has been the reliable identification of these cells at the light microscopical level, both in tumours and in normal salivary glands. Many methods have been advocated, often with comparatively little evaluation in normal human tissue and with limited comparison between techniques. This paper reviews the application of histological staining techniques, enzyme histochemistry and immunocytochemistry with antibodies to actin, myosin and keratins. The only reliable method was immunocytochemistry with an antibody to smooth muscle myosin, with immunofluorescence on frozen tissue and immunoenzyme labelling on methacarn-fixed/paraffin-processed material. Formalin fixation did not permit successful staining. Monoclonal antibodies to specific keratin polypeptides may prove to be a useful label of myoepithelial cells but at the present time the available cytokeratin antibodies preferentially stain duct cell populations.

A new marker of terminal differentiation in keratinizing epithelia

Using the well-differentiated human squamous carcinoma cell line LICR-LON-HN-5 as an immunogen we have produced a monoclonal antibody (32a) that reacts with the keratohyalin granular layer of the normal epidermis. We present here results showing the distribution of the epitope recognized by this antibody in human tissues in vivo and in vitro, as demonstrated using immuno cytochemical staining techniques at the light and ultrastructural levels. Expression of the determinant first appears at 18 weeks of fetal development, localized in cells associated with the hair germ. In hyperplastic epidermis the staining pattern is altered, apparently linked with a switch from orthokeratotic to parakeratotic keratinization. In primary squamous cell carcinomas and in xenografts formed by the squamous carcinoma cell line LICR-LON-HN-5 the keratinized elements are stained. Poorly differentiated tumours are not stained, indicating that antibody may be useful as a marker of terminal differentiation in vivo. When grown on collagen gels both human epidermal keratinocytes and the squamous carcinoma cell line show staining of the more differentiated cells which appears to be associated with the keratinohyalin granules, indicating that this antibody may be of value in studies aimed at the control of squamous differentiation.

Epimyoepithelial' islands in lymphoepithelial lesions. An immunocytochemical study

A panel of antibodies has been used in an immunoenzyme study in an attempt to characterize the cell types found in the 'epimyoepithelial' islands of lymphoepithelial lesions. Myoepithelial cells, which can be specifically stained with an anti-smooth muscle antibody were not found. The majority of cells stained with anti-prekeratin, suggesting a duct cell differentiation. A subpopulation of duct cells stainable with a monoclonal antikeratin (16a), previously described as occupying a basal location in normal salivary gland ducts, was clearly demonstrated. It is suggested that these cells may be important in the epithelial proliferation in these islands. The hyaline material within and surrounding the epithelial islands was positive for type IV collagen and therefore consists of basement membrane material.

Pleomorphic adenomas, adenoid cystic carcinomas and adenolymphomas of salivary glands analysed by a monoclonal antibody against myoepithelial/basal cells. An immunohistochemical study

Myoepithelial and basal cells were identified by a monoclonal antibody raised against keratin. This antibody (CK B1) which detects myoepithelial cells in normal salivary glands, labels spindle shaped and polygonal cells in pleomorphic adenomas. Most cells in adenoid cystic carcinomas and some basal cells in adenolymphomas were also positive for this antibody. The oncocytic epithelium of adenolymphoma was negative. An inverse reaction was seen with an antibody against cytokeratin 18. The antibody CK B1 seems to be of interest for the detection of myoepithelial/basal cells in salivary glands and salivary gland tumours.

The biochemical and immunocytochemical characterisation of an antigen on the membrane of basal cells of the epidermis

A murine monoclonal antibody, LICR-LON-23.10, which had been raised against a well-differentiated squamous cell carcinoma cell line (LICR-LON-HN5), recognises an antigen which is present on the membrane of basal cells of the epidermis. The tissue distribution of the antigen, as defined using immunohistochemical techniques, suggests that it is expressed preferentially on cells which are adjacent to a basement membrane. In squamous cell carcinomas, the antigen is expressed uniformly on undifferentiated cells, but in areas of keratinisation, the antigen is absent. The antigen recognised by the antibody was characterised as being a pair of glycoproteins with molecular masses of 120 and 135 daltons. The antibody was used for flow-cytometric analyses of epidermal keratinocyte preparations. Together with other basal cell markers, this antibody may be useful in the characterisation of the epidermal basal cell population as well as in broadening our understanding of the interaction between epithelial cell populations and their relationship with basement-membrane components.