Expression of class III beta-tubulin in normal and neoplastic human tissues.

The class III beta-tubulin isotype is widely used as a neuronal marker in normal and neoplastic tissues. This isotype was, however, also immunodetected in certain tumours of non-neuronal origin such as squamous cell carcinoma. Using a newly described monoclonal antibody we compared the distribution of class III beta-tubulin in normal and neoplastic tissues. The TU-20 mouse monoclonal antibody was prepared against a conserved synthetic peptide from the C-terminus of the human class III beta-tubulin isotype, and its specificity was confirmed by immunoblotting, by competitive enzyme-linked immunosorbent assay and by immunofluorescence microscopy on cultured cells. In different cell lines of various origins the antibody reacted only with neuroblastoma Neuro-2a cells and with embryonal carcinoma P19 cells stimulated to neuronal differentiation by retinoic acid. Immunohistochemistry on formaldehyde-fixed paraffin-embedded normal human tissues revealed the presence of the class III beta-tubulin isotype in cell bodies and processes of neuronal cells in the peripheral and central nervous systems. In other tissues, this beta-tubulin isotype was not immunodetected. Class III beta-tubulin was found in all cases of ganglioneuroblastoma, ganglioneuroma, medulloblastoma, neuroblastoma, sympathoblastoma and in one case of teratoma. In contrast, no reactivity was detected in tumours of non-neuronal origin, including 32 cases of squamous cell carcinoma. The results indicate a specific TU-20 epitope expression exclusively in neuronal tissues. The antibody could thus be a useful tool for the probing of class III beta-tubulin functions in neurons as well as for immunohistochemical characterisation of tumours of neuronal origin.

Enrichment of tumor cells for cell kinetic analysis in human tumor biopsies using cytokeratin gating.

PURPOSE: To determine the feasibility of using cytokeratin antibodies to distinguish normal and malignant cells in human tumors using flow cytometry. The goal was ultimately to increase the accuracy of cell kinetic measurements on human tumor biopsies. MATERIAL AND METHODS: A panel of four antibodies was screened on a series of 48 tumors from two centres; 22 head and neck tumors (Amsterdam) and 26 esophagus carcinomas (Leuven). First, screening was carried out by immunohistochemistry on frozen sections to test intensity of staining and the fraction of cytokeratin-positive tumor cells. The antibody showing the most positive staining was then used for flow cytometry on the same tumor. RESULTS: The two broadest spectrum antibodies (AE1/AE3, E3/C4) showed overall the best results with immunohistochemical staining, being positive in over 95% of tumors. Good cell suspensions for DNA flow cytometry could be made from frozen material by a mechanical method, whereas enzymatic methods with trypsin or collagenase were judged failures in almost all cases. From fresh material, both collagenase and trypsin produced good suspensions for flow cytometry, although the fraction of tumor cells, judged by proportion aneuploid cells, was markedly higher for trypsin. Using the best cytokeratin antibody for each tumor, two parameter flow cytometry was done (cytokeratin versus DNA content). Enrichment of tumor cells was then tested by measuring the fraction of aneuploid cells (the presumed malignant population) of cytokeratin-positive cells versus all cells. An enrichment factor ranging between 0 (no enrichment) and 1 (perfect enrichment, tumor cells only) was then calculated. The average enrichment was 0.60 for head and neck tumors and 0.59 for esophagus tumors. CONCLUSIONS: We conclude that this method can substantially enrich the proportion of tumor cells in biopsies from carcinomas. Application of this method could significantly enhance accuracy of tumor cell kinetic measurements.

Cytokeratin 18 expression in squamous cell carcinoma of the head and neck.

Cytokeratin (CK) expression was studied in squamous cell carcinomas of different subsites in the head and neck by using cryostat sections from 27 head and neck squamous cell carcinomas (HNSCCs) and 6 cell lines established from HNSCC. All tissues were analyzed immunohistochemically with a panel of monospecific anti-keratin monoclonal antibodies. Most carcinomas recapitulated the expression pattern of keratins present in the basal layer of normal epithelium from the site of tumor origin. Regional differences in the expression of simple-epithelial type of keratins in stratified (pseudostratified) epithelia were to a large extent repeated in corresponding carcinomas. In the present study, localization of various keratins were surveyed and CK 18 specific monoclonal antibodies were specifically used to distinguish SCCs of the larynx or hypopharynx from SCCs of the oral cavity. CK 18 staining of almost all tumor cells was detected in 11 of 12 SCCs of the larynx and hypopharynx, but was only detected sporadically in 3 of 9 SCCs of the oral cavity. The present results show that CK 18 typing might be useful for distinguishing sites of origin of various HNSCCs. Findings also indicate that CK 18 expression in SCC might be modulated by microenvironmental factors.

Distribution of extracellular and cytoplasmic domains of the alpha 3 and alpha 6 integrin subunits in solid tumors.

Integrins play an important role in malignant transformation and the invasion of tumors. They mediate cell-cell and cell-matrix interactions and participate in transduction of signals across the plasma membrane, processes dependent on the extracellular and cytoplasmic domains of integrins. We studied a selection of solid tumors by immunohistochemistry using monoclonal antibodies (MAbs) against the extracellular domain and the cytoplasmic variants (A and B) of the alpha 3 and alpha 6 integrin subunits. The tissue-specific expression of ecto- and cyto-domains of alpha 3 and alpha 6 is maintained in a subset of breast, colon, kidney and parotid tumors. In a few breast tumors, there was a switch in variant expression in that alpha 6B was detected instead of alpha 6A in normal breast tissue. In many colon and parotid tumors, one of the variants of alpha 6 was missing, while both were detectable in the corresponding normal tissues. In contrast, coexpression of the alpha 6 variants was found in some kidney tumors, whereas only one of the variants was detected in the normal tissue. In a minority of colon and kidney tumors, the cyto-domains of alpha 3 and alpha 6 were undetectable and total absence of alpha 3 and alpha 6 was noted in a subset of breast, colon, kidney and parotid tumors. These observations show that expression of the integrin variants in tumors varies considerably and support the concept that changes in expression may contribute to malignant behavior.

Cytokeratin subtypes and involucrin in squamous cell carcinoma of the vulva. An immunohistochemical study of 41 cases.

BACKGROUND: Histologic grade seems to be of limited prognostic significance in patients with vulvar carcinoma. However, the study of cytokeratin expression is of potential interest because it allows a more precise evaluation of the degree of squamous differentiation. This study was conducted to investigate whether differences in cytokeratin expression exist between normal vulvar epithelium and vulvar carcinoma and whether these differences are prognostically significant. METHODS: The expression of several differentiation markers, i.e., cytokeratin (CK) 10, CK 13, and involucrin, was studied in samples of 41 vulvar carcinomas. The expression of CK 8, 10, 13, and 14 was compared with CK expression in normal vulvar epithelium and was correlated with tumor grade and tumor growth pattern. Tumor growth pattern was considered type A if infiltrating tumor cell nests showed a layer of small, basaloid cells bordering the surrounding mesenchymal tissue and was considered type B if this was not the case. Prognosis was based on whether disease recurred or not. RESULTS: Sixteen patients had disease recurrence. No prognostic significance of tumor grade was found. Tumor growth pattern was prognostically significant: in patients with a type A tumor, recurrence was observed less often than in patients with a type B tumor (P = 0.03). Cytokeratin 14, typical for basal cells of normal vulvar epithelium, was expressed in all tumors, whereas CK 8 was not expressed in any tumor. A relationship between tumor growth pattern and the concordant expression of differentiation markers was observed: in 55% of type A tumors and in none of type B tumors, concordant expression of CK 10, CK 13, and involucrin was found. CONCLUSION: The expression of differentiation markers in vulvar carcinoma is related strongly to the tumor growth pattern, and this pattern is prognostically significant.

Expression of cytokeratin 10, 13, and involucrin as prognostic factors in low stage squamous cell carcinoma of the uterine cervix.

BACKGROUND: The identification of pretreatment markers with predictive significance for the presence of lymph node metastases and treatment outcome in low stage cancer of the uterine cervix is clinically important. Because the presence of differentiation-related markers varies in this type of cancer, the authors investigated whether loss of these markers is related to a poor clinical course. METHODS: An indirect immunoperoxidase technique was applied to formalin fixed, paraffin embedded tissue sections of 80 patients with International Federation of Gynecology and Obstetrics Stage IB and IIA primary squamous cell cervical carcinomas for detection of expression of cytokeratin 10 and 13, and involucrin. Comparisons were made of the expression of each of these markers among 40 patients with regional node metastases and 40 age-matched patients with no lymph node metastases. Differences in the frequency of expression of these markers also were analyzed in relation to histopathologic characteristics, recurrence, and survival. RESULTS: Expression of cytokeratin 10, 13, and involucrin was found in 24, 64, and 53%, respectively, of all patients studied. The authors found no differences between patients with positive regional lymph nodes and those with negative lymph nodes. Expression of cytokeratin 13 and involucrin was associated with tumor grade (P = 0.01). No relationship was found between expression of the markers used and recurrence or survival in the entire group. Within the lymph node-positive group, however, the survival rate of patients with tumors with cytokeratin 13 expression was significantly higher than that of patients with tumors lacking cytokeratin 13 expression (P = 0.02). CONCLUSION: Expression of cytokeratin 10, 13, or involucrin in the primary tumor is of no predictive value with respect to the presence of regional lymph node metastases in low stage squamous cell cervical cancer. However, cytokeratin 13 expression appears to be of prognostic significance in patients with positive regional lymph nodes.

Monoclonal antibody M3 used in tissue polypeptide-specific antigen assay for the quantification of tissue polypeptide antigen recognizes keratin 18.

Recently, a new 'specific tissue polypeptide antigen (TPA)' test was introduced and designated tissue polypeptide-specific antigen (TPS); it is based on the monoclonal antibody (MAb) anti-TPS, M3. We have tested the specificity of this antibody by immunocyto- and immunohistochemistry, gel electrophoresis and immunoblotting. MAb M3 bound to intermediate filaments of epithelial cells and revealed a staining pattern identical to cytokeratin (CK) 18-specific MAb (DE-K18) on tissue sections of various human tissues. On immunoblots of proteins extracted from various epithelial cell lines, M3 reacted with a 45-kD protein corresponding to CK18, and on immunoblots of proteins isolated from MCF-7 culture fluid M3 stained three bands, 45, 33 and 29 kD. The same bands were stained with CK18-specific MAb, indicating that they represent CK18 and its degradation products. TPA, used as a tumor marker in clinical diagnoses and follow-up, was shown to be a degradation product of CK 8, 18 and 19. In contrast to TPA, MAb M3 did not stain CK8 and CK19 present on immunoblots.

Modulation of mammary carcinoma cell phenotype and keratin expression patterns by retinoic acid.

Immunohistochemical and biochemical procedures were used to study the influence of retinoic acid (RA) on cellular expression and distribution of cytokeratins (CKs) in feline mammary carcinoma cells. These cells were grown in vitro as established cell lines (K248C and K266) and in vivo as xenografts in athymic mice. The results were compared with the distribution of CKs in normal feline mammary gland and in a series of invasive mammary carcinomas previously probed with a panel of monoclonal antibodies specific for individual CKs. Coexpression of CKs of both major mammary gland cell types (myoepithelial cells, MECs, CKs 5/14 positive, and luminal epithelial cells, LECs CKs8/18 positive) by K248C and K266 cells, suggested a stem cell-like character of both cell lines. RA increased CK19 expression in both cell lines and CK19 was also present in tumors developed in nude mice from both RA untreated (CK19 negative) and RA-treated (CK19 positive) K248C and K266 cells. In addition, RA had cell line specific effects as well. RA treatment induced differentiation of K248C cells to more mature LEC-like cells and this change was accompanied by the loss of the MEC keratins CKs 5/14. Under the same culture conditions however, RA treatment did not induce morphological changes in the K266 cell line and the expression of CKs 5/14 was not significantly reduced. These findings suggest that the modulation of CK19 and CKs 5/14 expression observed in mammary carcinoma cells upon RA treatment might be regulated through different pathways.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: normal mammary tissue.

Normal canine mammary gland tissue was studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types, vimentin, desmin, and alpha-smooth muscle actin. Both ductal and alveolar luminal cells were immunoreactive with MoAbs recognizing respectively human keratins no. 7, 8, 18 and 19. In addition, some ductal luminal cells were labelled with a keratin 4 and a keratin 10 MoAb. Basal/myoepithelial cells were immunoreactive only with MoAbs directed against keratin 14, keratins 14 and 17, and alpha-smooth muscle actin. The vimentin MoAb merely labelled solitary loose intraluminal cells representing macro-phages or sloughed epithelial cells. These findings correspond largely to observations made in human breast tissue.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: benign mammary tumours and duct ectasias.

Duct ectasias (n = 2) and different types of benign canine mammary tumours (n = 19) were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types (K), alpha-smooth muscle actin, vimentin, and desmin. In the duct ectasias and in most tumours the epithelial structures revealed an inner and outer cell layer. The inner cell layer was characterized by labelling with K 7, 8, 18, 19 and mostly also with K 4 and/or K 10 MoAbs. The outer cell layer was almost invariably labelled by K 14, K 14 and 17, and a-smooth muscle actin MoAbs. The labelling patterns of both duct ectasias and tumours corresponded largely to the patterns observed in normal mammary gland tissue, although a more distinct heterogeneity was seen. Tumours histomorphologically assumed to be of a myoepithelial origin did not show immunohistochemical features of myoepithelial cells. The myoepithelial nature of the vast majority of spindle-shaped cells present in the adenomas of the complex type and in the fibroadenomas of the benign mixed type could not be confirmed immunohistochemically. These cells, however, unequivocally expressed vimentin, suggesting proliferation of stromal cells in these tumours, which in the fibroadenomas of the benign mixed type may show metaplasia to bone or cartilage. In the duct ectasias and in some tumours, a fraction of elongated stromal cells, probably representing myofibroblasts, was labelled with the alpha-smooth muscle actin MoAb.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: malignant mammary tumours.

Ten malignant canine mammary gland tumours and five metastases from three of these tumours were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against different human keratin types (K), alpha-smooth muscle actin, vimentin, and desmin. In all tumours the neoplastic epithelium was rather homogeneously labelled with the keratin MoAbs RCK 102 (K 5 and 8) and CAM 5.2 (K 8). The adenocarcinomas (n = 5), the solid carcinomas (n = 2), and the carcinosarcoma (n = 1) showed heterogeneous labelling with the MoAbs specific for luminal cell antigens in the normal canine mammary gland, i.e., K 18, K 7 and K 19 MoAbs. These cells were also immunoreactive with K 4 and K 10 MoAbs. The spindle cell carcinomas (n = 2), however, did not react with these MoAbs. All tumours except one adenocarcinoma were characterized by the absence of immunoreactive labelling with the alpha-smooth muscle actin MoAb. In the solid carcinomas this was associated with the absence of labelling with one or both basal cell specific keratin MoAbs, i.e., 8.7 (K 14 and 17) and RCK 107 (K 14), respectively. In contrast, the other malignant tumours showed marked labelling of neoplastic epithelium with these MoAbs. Another remarkable finding was the labelling of a limited to moderate number of neoplastic epithelial cells with the vimentin MoAb. The presence of such labelling patterns in canine mammary gland tumours may be indicative of malignancy. Metastatic tumour tissues had a labelling pattern largely similar to that of the primary tumour, although also loss of reactivity for some keratin MoAbs was seen.

Cytokeratins as markers of initial stages of squamous metaplasia in feline mammary carcinomas.

Expression of keratins (cytokeratins, CK) known to be suitable markers for different types of epithelial differentiation was analyzed in specimens of feline mammary tissue. A panel of specific anti-CK monoclonal antibodies (MAb) was used to determine CK distribution pattern in normal feline tissues (n = 3), and in benign (n = 18) and malignant (n = 20) feline mammary tumors. In selected tumors, the CK distribution pattern was also determined by biochemical methods. A MAb specific for alpha-smooth muscle actin was used to discriminate between myoepithelial cells and luminal epithelial cells. In normal mammary gland tissues, 6 MAb reacted exclusively, either with myoepithelial cells or with luminal epithelial cells. Luminal epithelial cells reacted with MAb specific for CK typical of simple epithelia, whereas myoepithelial cells reacted with MAb specific for CK in basal cells of stratified epithelia. A similar distribution of CK was detected in specimens from benign tumors, except that CK4 was not detected in normal mammary gland tissues and was detected in some ducts in specimens with adenosis. Almost all tumor cells in specimens from malignant tumors reacted with MAb specific for CK typical of simple epithelia. Concomitant expression of CK typical of stratified epithelia was detected in small or large subpopulations of tumor cells in 70% of carcinomas. Cytokeratins typical of basal cell layers and typical for suprabasal layers of inner stratified epithelia were detected. Cytokeratins typical of stratified epithelia were always found in areas of squamous metaplasia, but also were found in adenocarcinomal cells surrounding these areas.(ABSTRACT TRUNCATED AT 250 WORDS)

The expression of keratins, vimentin, neurofilament proteins, smooth muscle actin, neuron-specific enolase, and synaptophysin in tumors of the specific glands in the canine anal region.

Eight canine tumors originating from specific glandular structures in the anal region, as well as metastatic tumor tissue of two of these cases (case Nos. 7, 8), were immunohistochemically analyzed using various monoclonal antibodies (MoAbs) directed against human keratin types, vimentin, neurofilament proteins, and alpha-smooth muscle actin. These tumors also were stained for the broad-spectrum neuroendocrine markers neuron-specific enolase (NSE) and synaptophysin. In histologically normal canine anal structures, alpha-smooth muscle actin and NSE antibodies stained basally localized (probably myoepithelial) cells in the anal glands and the anal sac glands. NSE staining also was present in a limited number of luminal cells in both anal glands and anal sac glands. Synaptophysin labeling was not observed in any of these glandular structures. Histologically, the tumors were differentiated into well- and moderately differentiated perianal gland tumors (n = 5) and carcinomas without perianal gland differentiation (n = 3), corresponding to the so-called apocrine carcinomas of the anal region. Immunohistochemically, the perianal gland tumors could be differentiated from the carcinomas by marked differences in staining pattern with the various keratin MoAbs, particularly MoAbs directed against human keratin types 7 and 18. The keratin-staining characteristics of the carcinomas suggest a glandular luminal cell origin. Metastases of the carcinomas showed loss of some keratin-staining characteristics as compared with the primary tumor. Staining for NSE was only observed in solitary cells and small cell clusters in the carcinomas and their metastases, whereas the alpha-smooth muscle actin antibody did not react with the carcinoma cells. None of the tumors stained for neurofilament proteins or synaptophysin. An unequivocal neuroendocrine nature of the carcinomas could not be substantiated by our immunohistochemical study, although the presence of a population of neuroendocrine cells within these neoplasms seems likely. Because the immunohistochemical features of the carcinomas with respect to various keratin MoAbs and NSE are similar to those of the anal glands and the anal sac glands, both these glands might be considered as site of origin of these carcinomas.

Rhabdomyosarcomas in young pigs in a swine breeding farm: a morphologic and immunohistochemical study.

Within a 6-month-period, solitary or multiple tumors were observed in 25 young pigs in their first weeks of life in a swine breeding farm. The herd comprised approximately 100 animals, and affected pigs were observed in several litters. The number of affected littermates varied from one to three. Five animals, all from different litters and with a total of 11 tumors, were studied. Histologically the tumors were classified as undifferentiated sarcomas. Electron microscopic examination of the tumors (n = 3) revealed myogenic differentiation, characterized by the presence of numerous cytoplasmic filaments with longitudinal densities and cytoplasmic dense bodies. Immunohistochemically, all 11 tumors were labeled by vimentin and desmin antibodies. Two tumors from which frozen material was available were additionally labeled by a titin antibody but did not show immunoreactivity with antibodies directed against myosin and alpha-sarcomeric actin. The tumors were finally diagnosed as undifferentiated rhabdomyosarcomas. The high incidence of these tumors within a short period of time in multiple young animals in different litters indicates a common causative event. The clinical history suggests a genetic cause.

Immunohistochemistry with keratin monoclonal antibodies in canine tissues: urogenital tract, respiratory tract, (neuro-)endocrine tissues, choroid plexus and spinal cord.

Twelve oligo- or monospecific monoclonal antibodies (MoAbs) directed against human keratin types were used in an immunohistochemical study of the canine male and female urogenital tract, the respiratory tract, the adrenal gland, the (para-)thyroid gland, the choroid plexus and the spinal cord. The keratin MoAbs showed differences in staining patterns in the various epithelial tissues and the diverse epithelial cells. The kidney was characterized by a complex keratin staining pattern and the canine urothelium showed regional differences in keratin staining. Also in the female genital tract different keratin staining patterns were observed. Testicular and adrenal gland cells did not react with any of the keratin MoAbs. The keratin staining patterns in the various canine tissues showed, in addition to similarities, also distinct differences when compared to the staining patterns in corresponding tissues of other species, e.g. of man. These staining dissimilarities indicate that the reactivity patterns of the keratin MoAbs with restricted keratin immunoreactivity can not be always extrapolated from one species to another. Nevertheless, MoAbs directed against human keratin proteins can apparently be used to differentiate between various types of canine epithelia or epithelial compartments.

Keratin and vimentin distribution patterns in the epithelial structures of the canine anal region.

The intermediate filament labeling pattern of the epithelial structures of the canine anal region was studied with different polypeptide specific keratin monoclonal antibodies (MoAbs) and with a monoclonal and polyclonal vimentin antibody. The epithelial structures in this region could be discriminated and characterized by differences in their keratin staining pattern. The basal cells in the different epithelial structures showed a similar staining pattern characterized by reactivity with MoAbs staining keratins 5, 8, 14, and 17. Columnar epithelial cells showed a completely different phenotype mostly characterized by reactivity with MoAbs staining keratins 7, 5, 8, 18, and 19. A restricted number of differentiated perianal gland cells showed perinuclear vimentin staining. Myoepithelial cells did not stain for vimentin, but, as other basal cells, were positive for MoAbs staining keratins 5, 8, 14, and 17.

Immunohistochemistry with keratin and smooth muscle actin monoclonal antibodies in canine digestive tract and extramural glands.

The canine digestive system and its extramural glands (parotid gland, liver, pancreas) were immunohistochemically studied using a panel of twelve monoclonal antibodies (MoAbs) specific for human keratin proteins and for alpha-smooth muscle actin. Various epithelial tissues and cells were characterized by different keratin staining patterns. So, the epithelial lining of the upper alimentary tract was characterized by staining with the MoAb 6B10, specific for keratin-type (K) 4, and the absence of staining with the MoAbs directed against K 8 and 18 (CAM 5.2 and RGE 53, DE-K18 respectively), whereas the lower alimentary tract epithelium was not labeled by 6B10, but stained by the latter MoAbs. In the salivary glands the luminal and basal cells of the adenomeres as well as the different ductal structures could be immunohistochemically differentiated. The duct epithelium in liver and pancreas showed next to keratin staining characteristics in common with hepatocytes and exocrine pancreatic cells, additional staining by several keratin MoAbs. The keratin staining patterns in the canine tissues showed, in addition to similarities also distinct discrepancies when compared to the staining patterns in corresponding human tissues. Myoepithelial cells in salivary and oesophageal glands could be differentiated from other basally located epithelial cells by their exclusive immunoreactivity for alpha-smooth muscle actin. Canine pancreatic endocrine cells were not labeled by any of the keratin MoAbs. It is concluded that immunohistochemistry with polypeptide specific MoAbs specific for human keratin-types can be used to differentiate between different types of canine epithelial tissues and epithelial cells in the digestive tract. As a result such reagents may find their application in developmental biology and pathology of this species.

Patterns of expression of feline cytokeratins in healthy epithelia and mammary carcinoma cells.

Expression of keratins (cytokeratins, CK) in healthy feline epithelia and 2 established feline mammary carcinoma cell lines was examined immunohistochemically and by use of immunoblotting analysis. A panel of specific anti-CK monoclonal antibodies (MAb) identifying epitopes unique to individual keratins or shared by 2 (or 3) CK polypeptides was used. Besides already available anti-human CK MAb, this panel of MAb consisted of 9 newly generated anti-human CK MAb and 1 newly generated anti-feline CK MAb. Immunohistochemical analysis on normal epithelia revealed that most of the anti-human CK MAb and the anti-feline CK MAb reacted with both feline and human epithelia, with a comparable tissue distribution pattern. However, slight differences in CK tissue distribution pattern between human beings and cats were detected by one MAb. Immunoblotting analysis revealed that all anti-human CK MAb that were immunohistochemically reactive with feline tissues detected analogous CK in cats, indicating the presence of a number of common epitopes on human and feline CK. Two continuous cell lines derived from 2 distinct feline mammary adenocarcinomas, K248C and K266, were analyzed with respect to their CK phenotype. Although no difference in CK expression between the 2 cell lines was detected in vitro, a difference in CK phenotype was detected on subcutaneous transplantation of the 2 cell lines into nude mice. Although the K248C-induced adenocarcinomas maintained the same CK phenotype as observed in vitro, the CK pattern of the K266 heterotransplants, growing as adenosquamous carcinomas, changed with squamous differentiation. Our findings confirm the high degree of homology between mammalian CK, and on the basis of those findings, we suggest that CK proteins provide a set of markers valuable for the characterization of normal and neoplastic feline tissues and for studies of squamous metaplasia.

Keratin subtypes in carcinomas of the uterine cervix: implications for histogenesis and differential diagnosis.

Normal epithelia and carcinomas of the human uterine cervix were studied by monoclonal antibodies chain specific for cytokeratins 4, 8, 10, 13, 14, 18, and 19. Most cells in 13 examined squamous carcinomas revealed a cytokeratin phenotype detected in ectocervical basal cells and endocervical subcolumnar reserve cells: 8+, 14+, 18+, 19+, 4-, 10-, 13-. We propose that these two cell types are closely related or identical and that squamous carcinoma of the cervix originates in this cell type. In more differentiated tumor cells cytokeratins 4, 10, and 13, which are present in suprabasal layers of the normal ectocervical epithelium, were coexpressed with basal cell cytokeratins. Thus, contrary to previous beliefs, all cytokeratins detected in carcinomas were also present in normal epithelium of uterine cervix. The cytokeratin profile of cervical adenocarcinomas corresponded to that of columnar endocervical cells (8+, 18+, 19+), although two of the three adenocarcinomas also expressed cytokeratin 4, which in the normal endocervix was detected in scattered single columnar cells only. The new monoclonal antibody DE-K14, specific for cytokeratin 14, proved a specific marker of subcolumnar reserve cells in the endocervix. It was also the only one that reacted with all cervical squamous carcinomas but with none of the cervical adenocarcinomas and, as such, has a potential value for pathological differential diagnosis of cervical tumors.

Absence of differentiation-related expression of keratin 10 in early stages of vulvar squamous carcinoma.

Using specific monoclonal antibodies (DE-K10 and DE-SCK respectively), the expression of some differentiation-related epidermal keratins was studied in 38 human vulvar squamous carcinomas. In the epidermis, expression of keratin 10 (K10) strictly paralleled the extent of differentiation; it was absent in the basal layer, appeared in the first suprabasal layers and increased in concentration towards the granular layer. However, K10 was rarely detected (1 case out of 12) in early stages of vulvar squamous carcinomas (tumours less than 2 cm, clinical stage I) regardless of the tumour grade. In larger and more advanced tumours (greater than 2 cm, clinical stages II and III), K10 was detected in 21 out of 26 cases. Its expression appeared to be related to maturation of malignant keratinocytes, being preferentially detected in more-differentiated parts. Occasionally however, cells that did not show histological signs of keratinisation were also K10-positive. Modified stratum corneum keratins (recognized specifically by monoclonal antibody DE-SCK) were detected in the most keratinized areas (horn pearls and their close vicinity) of some K10-positive tumours, i.e., in a pattern close to their normal expression in terminally differentiated epidermal cells. These data suggest differences in the regulation of K10 expression during the differentiation processes in the normal keratinising squamous epithelium and in squamous carcinomas. While the normal pattern of vulvar epithelial differentiation is accompanied by an increasing expression of K10, malignant keratinocytes, also when these are histologically moderately or well differentiated, cease expressing this keratin in the early stages of tumour development.