The distribution of keratin type intermediate filaments in human breast cancer. An immunohistological study

Intermediate-sized Filament Proteins (Keratin, Vimentin, Desmin) in Metaplastic Carcinomas, Carcinosarcomas and Stromal Sarcomas of the Breast

The distribution of intermediate-filament (IF) proteins of the keratin, vimentin and desmin type in breast stromal sarcomas, carcinosarcomas, metaplastic carcinomas and phyllodes tumors has been compared using the avidin-biotin complex immunoperoxidase technique. Keratin reactivity was found in carcinomatous and pseudosarcomatous areas of all metaplastic carcinomas, in the cuboidal epithelial cells of carcinosarcomas and in the epithelial component of phyllodes tumors. Vimentin and desmin were detected in the sarcomatous portion of carcinosarcoma, focally in the stromal component of phyllodes tumors and not always in the stromal sarcomas. These data confirm that combined analysis of IF expression is a reliable and convincing way to differentiate stromal sarcomas, metaplastic carcinomas and carcinosarcomas in breast pathology.

Localization of CD44 and CD90 positive cells to the invasive front of breast tumors

BACKGROUND

A variety of markers have been proposed to identify breast cancer stem cells. Here, we used immunohistostaining and flow cytometry to analyze their interrelationships and to sort cells for tumorigenicity studies.

METHODS

Cytokeratin, CD44, and CD90 were localized to primary breast cancer and normal breast (NB) tissue by immunohistostaining and related to CD117 and CD133 expression by flow cytometry. Immunodeficient NOD.CB17-Prkdc(scid) /J and NOD.Cg-Prkdc(scid) Il2rg(tm1Wjl) /SzJ mice were used to test tumorigenicity of sorted CD90+ low-light scatter, CD90+ high-light scatter, and CD90(neg) tumor cells.

RESULTS

NB basal cells coexpressed CD44 and CD90. As cells transited luminally, CD44 was retained and downmodulated, and CD90 was lost and cytokeratin increased. In breast tumors, basal-like CD44+/CD90+ cells were localized to the tumor periphery, adjacent to CD90+ stroma. Like normal luminal cells, interior tumor cells were CD44+/CD90-. Immunophenotyping (CD44/CD90/CD117/CD133) of cytokeratin+ cells revealed no significant difference in expression between tumors and tumor-free breast. In both, CD133 was distributed approximately equally among CD44/CD90 subsets, whereas CD117 expression was highest in the basal-associated CD44+/CD90+ subset. Sorted CD90+ pleural effusion cells with lymphoid light scatter, 49% of which were CD44+, were uniquely tumorigenic in immunodeficient mice (100 cells/injection).

CONCLUSIONS

Our data demonstrate that all tumors contain a small population of CD44+/CD90+ cells, mimicking the phenotype of ductal-basal cells. These are localized to the tumor periphery, adjacent to CD90+ stroma. Among the nonhematopoietic, nonmesothelial cells found in metastatic pleural effusions, low-light scatter CD90+ cells are most potently tumorigenic, compared to high-scatter CD90+ cells and CD90- cells. © 2010 International Clinical Cytometry Society.

Intermediate vimentin filaments and their role in intracellular organelle distribution

Intermediate filaments (IF) represent one of three main cytoskeletal structures in most animal cells. The human IF protein family includes about 70 members divided into five main groups. The characteristic feature of IF is that in various cells and tissues they are formed by proteins of different groups. Structures of all IF proteins follow a unique scheme: a central alpha-helical part is flanked at the N and C ends by positively charged polypeptide chains devoid of a clear secondary structure. The central part is highly conserved for all proteins in all animals, whereas the N and C termini strongly differ both in size and amino acid composition. This review covers the broad spectrum of recent investigations of IF structure and diverse functions. Special attention is paid to the regulatory mechanisms of IF functions, mainly to phosphorylation by different protein kinases whose role is well studied. The review gives examples of hereditary diseases associated with mutations of some IF proteins, which point to an important physiological role of these cytoskeletal structures.

Cytokeratin expression in seminoma of the human testis

We studied cytokeratin (CK) expression immunohistochemically in 64 seminomas using a panel of commercially available antikeratin antibodies and tested for association of CK expression with patient age, tumor size, stage, and outcome. Seventeen embryonal carcinomas were compared with seminoma. CK7, CAM 5.2, AEI/AEIII, and wide-spectrum screening keratin (WSK) were positive in 41%, 30%, 36%, and 36% of the seminomas, respectively. CK20 and high-molecular-weight keratin (HMWK) were negative in all cases. CD30, placental alkaline phosphatase (PLAP), and epithelial membrane antigen (EMA) were positive in 6%, 100%, and 2% of cases, respectively. There were no differences in patient age, stage, tumor size, or outcome between CK-positive and CK-negative seminomas. CK7, CAM 5.2, AEI/AEIII, and WSK were positive in 100%, 88%, 94%, and 88% of embryonal carcinomas, respectively. CK20 and HMWK were negative in all cases. CD30, EMA, and PLAP were positive in 100%, 12%, and 76%, respectively. CKs are present in seminoma, and their presence is not associated with a difference in patient age, stage, or outcome. In cases such as small needle biopsy specimens, CK and CD30 stains may be useful in separating seminoma from embryonal carcinoma.

Differentiation pathways in primary invasive breast carcinoma as suggested by intermediate filament and biopathological marker expression

The expression of intermediate filament proteins (IFPs) in 65 primary breast carcinomas was analysed by a panel of specific antibodies. Results were integrated with the oestrogen and progesterone receptor (ER and PGR) status, Ki-67 marking, and epidermal growth factor receptor (EGFr) expression. Invasive breast carcinomas could be divided into three main groups: group 1 revealed positivity only for 'simple epithelial' cytokeratins (CKs 7, 8, 18, and 19); group 2 also stained with the antibodies K8.12 and 34 beta E12; while group 3 showed co-expression of CKs 14 and 17, vimentin, and alpha-smooth muscle actin. Group 3 consistently comprised tumours with the highest Ki-67 levels, EGFr positivity, and ER-PGR negative status. On the other hand, groups 1 and 2 usually exhibited a positive hormonal status, lower proliferative activity, and EGFr negativity. The results of this study indicate that the determination of IFPs can significantly contribute to the identification of groups of patients with different biopathological settings and possibly different clinical behaviour.

Intra-abdominal desmoplastic small cell tumor in an adolescent suggesting a neurogenic origin

A case of a desmoplastic small cell tumor of the large omentum associated with gross ascites that occurred in a male adolescent is reported. Light microscopic studies revealed that the tumor cells were small and epithelioid in nature with eosinophilic hyaline material located in the perinuclear area. They were surrounded by rich desmoplastic and myxoidal stromal bands. Immunohistochemical staining revealed globoid perinuclear positivity for desmin. Vimentin, cytokeratin (AE3, CaM 5.2), epithelial membrane antigen, tissue polypeptide antigen, neuron-specific enolase, chromogranin A, endocrine granule constituent and synaptophysin were also positive in the cytoplasm. Electron microscopy revealed whorled intermediate filaments and some dense core granules in the cytoplasm. Bundles of microtubules in the cytoplasmic process and occasional cell junctions of zonulae adherentes in the tumor cells were also observed. DNA analysis of the tumor cells showed the three-fold amplification of the N-myc gene. Although desmoplastic small cell tumors showed a heterogeneous pattern with immunohistochemical studies, it is suggested that the tumor may originate from neurogenic cells.

An immunohistochemical study of the breast using antibodies to basal and luminal keratins, alpha-smooth muscle actin, vimentin, collagen IV and laminin. Part I: Normal breast and benign proliferative lesions

The distribution of simple epithelial (K8/18/19) and basal (myoepithelial) (K5/14) keratins, alpha-smooth-muscle actin, vimentin, collagen IV and laminin in normal mammary glands and in benign proliferative lesions was studied using monoclonal antibodies (mAbs). These antibodies (Abs) identified myoepithelial cells and luminal cells specifically. In lesions with adenosis and papillomas, the two-layered formation resembled that of normal glands with a purely myoepithelial-epithelial differentiation. In scleradenotic lesions, the main cell was of myoepithelial immunophenotype with intermixed trabecular-tubular proliferations of simple-type epithelium. The sclerosis seems to be the result of an irregular basal lamina synthesis by the myoepithelial cells. In contrast to these lesions, epitheliosis represents a purely intraluminal cell proliferation of clearly simple epithelial immunophenotype and of cells with a basal keratin phenotype, lacking myoepithelial differentiation antigen actin. The basal keratin type epithelium may represent post-stem or intermediate cells developing into luminal epithelium. Epitheliosis appears to be a purely epithelial hyperplasia with striking similarity to the regeneration of normal breast epithelium. The different proliferative patterns may give an explanation for differences in potential cancer risks of patients with these lesions.

Differential antigen preservation during tissue autolysis

Immediate fixation or snap freezing of tissue is ordinarily done to maximize antigen preservation for immunocytochemistry; however, delay in tissue allocation or spontaneous lymph node infarction can render tissue suboptimal for immunostaining. To test the effects of tissue autolysis/necrosis on the preservation of various lymphoid, epithelial, and mesenchymal markers, two lymph nodes (one with reactive lymphoid hyperplasia and one with metastatic ductal breast carcinoma) were evaluated for immunocytochemically demonstrated antigen preservation at 0-, 4-, 8-, 12-, 24-, 48-, and 72-hour intervals of autolysis at 37 degrees C. All specimens were stained by frozen section and formalin-fixed paraffin section immunocytochemical reactions with antibodies against CLA (CD45), UCHL-1 (CD45RO), L-26, kappa, lambda, anti-epithelial keratins (AE-1 and AE-3), epithelial membrane antigen, and vimentin. Frozen sections were additionally stained for Leu-1 (CD5), Leu-2a (CD8), Leu-3a+b (CD4), Leu-4 (CD3), and Leu-14 (CD22). The most resilient lymphoid antigen preservation was observed with CLA and UCHL-1, both exhibiting immunoreactivity at 72 hours in both frozen and fixed preparations. L-26 showed similar reactivity in frozen sections, but detectable antigen was observed only up to 24 hours in formalin-fixed tissue. Leu-2a proved to be the most labile antigen, persisting for only 12 hours in frozen sections. The epithelial markers epithelial membrane antigen and AE-1 exhibited excellent antigenic preservation in both frozen and fixed preparations; AE-3 persisted well in frozen section but was not demonstrated in fixed tissue. Vimentin immunoreactivity was vastly superior in frozen, as compared with fixed, tissue sections. Most antigens showed remarkable preservation despite morphologic degradation; however, differential antigenic resilience was demonstrated. Knowledge of this variation in antigen decay is critical for evaluation of immunoperoxidase phenotypic studies of autolyzed or necrotic tissue.

Flow cytometry study of cytokeratin 18 expression according to tumor grade and deoxyribonucleic acid content in human bladder tumors

Cytokeratin 18 expression in transitional cells of 76 bladder tumors (11 grade 1, 33 grade 2 and 32 grade 3) and 10 normal biopsies was quantified by flow cytometry after immunolabeling with the anti-cytokeratin 18 monoclonal antibody RGE 53. Combined cytometric analysis of deoxyribonucleic acid content and cytokeratin 18 expression was conducted. Of 76 tumor biopsies 38 had a unimodal deoxyribonucleic acid profile with a deoxyribonucleic acid index close to 1.0, while the other 38 showed a bimodal profile: 1 peak with an index of 1.0 and a second peak with an index of greater than 1.0. The 11 grade 1 tumors belonged to the first group, whereas 10 of the 33 grade 2 and 28 of the 32 grade 3 tumors belonged to the second group. Antibody RGE 53 reacted with 4 per cent of the normal bladder cells (umbrella cells), 14 +/- 3 per cent of the cells from grade 1, 33 +/- 8 per cent from grade 2 and 56 +/- 10 per cent from grade 3 tumors. Analysis of cytokeratin 18 expression according to deoxyribonucleic acid content at the single cell level in tumors with a bimodal deoxyribonucleic acid profile showed that cytokeratin 18 was detected frequently in cells with a high deoxyribonucleic acid index but much less so in cells with an index of 1.0. Therefore, expression of cytokeratin 18 can be recognized as a marker of aggressiveness in bladder tumors, since it increases in parallel with tumor grade and cell deoxyribonucleic acid content.

Mucoepidermoid mammary carcinoma. Immunohistochemical and biochemical analyses of intermediate filaments

The histological features of mucoepidermoid mammary carcinomas (MMCs) are presented, and criteria for distinguishing these tumours from squamous epithelial metaplasia in other mammary carcinomas are considered. Immunohistochemical and gel-electrophoretic analyses of the intermediate-filament proteins in one MMC case revealed a complex pattern of cytokeratin polypeptide expression. The simple-epithelium-type cytokeratins 7, 8, 18, and 19 were detected mainly in nonsquamous (including mucinous) cells, while the stratified-epithelium-type cytokeratins 5, 6, 14, 16, and 17 were present in squamous cells. However, in both the nonsquamous and squamous regions of the tumour, cytokeratins of the "reverse" type were detected in individual cells. This pattern of single-cell heterogeneity with respect to cytokeratin polypeptide expression suggests that the mixed phenotype of this tumour is not caused by the clonal divergence of tumour cell types. Rather, histogenetically, a pluripotent stem cell with the ability to differentiate into squamous (epidermoid) or mucinous cells might be the starting-point of such a tumour and such differentiation processes may continue to occur during tumour growth. The present case also revealed that mucoepidermoid tumours are not necessarily of low malignancy; there are highly malignant forms with rapid metastasis.

Expression of the cytokeratin marker CAM 5.2 in cervical neoplasia

It has been suggested that cytokeratin CAM 5.2 is a useful marker to indicate malignant transformation and invasive potential in cervical neoplasia. In this study we examined normal ectocervical epithelium, endocervical squamous metaplasia, cervical intra-epithelial neoplasia (CIN) and invasive carcinoma by the indirect immunoperoxidase method using commercially available CAM 5.2. Positive staining was seen in 12 of 42 (28%) invasive carcinomas and in 2 of 26 specimens of CIN III. No positive staining was observed in any case of CIN II (22 specimens), CIN I (19), squamous metaplasia (21) or normal ectocervical epithelium (16). These results suggest that although CAM 5.2 expression is found in only 28% of cervical squamous carcinoma, it is highly specific for malignant transformation of cervical squamous epithelium. In view of its potential diagnostic value in doubtful cases of CIN III and squamous cell carcinoma, the specificity and sensitivity of CAM 5.2 expression in cervical neoplasia need to be examined in other laboratories under various processing schedules.

Structural distinctions among human breast epithelial cells revealed by the monclonal antikeratin antibodies AE1 and AE3

Two monoclonal antikeratin antibodies, AE1 and AE3, were used in indirect immunocytochemistry to examine keratin expression in normal, benign proliferative, and malignant human breast epithelium. Both antibodies reacted strongly with most luminal cells in ducts and acini of normal gland. While AE1 did not stain myoepithelium, AE3 recognized myoepithelial cells of ducts but not acini, implying a cytoskeletal difference between the myoepithelium of these two components. Moreover, the antibodies reacted differently with the myoepithelium of intracanalicular as compared with pericanalicular types of fibroadenomas. Tumour cells of infiltrating ductal carcinomas with a prominent intraductal component stained more homogeneously with AE1 and AE3 than those without intraductal growth. The results provide evidence for two phenotypes of myoepithelial cells and for the presence of cryptic keratin epitopes in human breast epithelial cells. The finding that neither AE1 nor AE3 is a universal detector of these cells has important clinical and experimental implications.

Distribution of keratin protein in normal prostate and prostatic tumors. An immunohistochemical study

Fifty cases (20 cases of benign hyperplasia, 30 cases of adenocarcinoma) of prostatic tissues were studied for expression of keratin. The basal cells were strongly and continuously positive in normal prostatic glands and in benign prostatic hyperplasia. The secretory cells and carcinoma cells were negative. The basal cells remained partially in intra-ductal carcinoma, revealing keratin positive cells in a spotty pattern. These findings may be useful in differential diagnosis between benign prostatic hyperplasia and carcinoma of the prostate.

An analysis of the sensitivity and specificity of the cytokeratin marker CAM 5.2 for epithelial tumours. Results of a study of 203 sarcomas, 50 carcinomas and 28 malignant melanomas

Two hundred and three sarcomas, 40 carcinomas, 10 carcinomas with spindle cell features, 27 malignant melanomas and one spindle cell melanoma were examined using CAM 5.2, a monoclonal antibody to cytokeratin. This antibody which was prepared against colorectal carcinoma cells and which identifies low molecular weight intermediate filament cytokeratin proteins is suitable for use in formalin fixed, paraffin embedded material. Seventeen of the 203 sarcomas showed positive staining. These included 15/21 synovial sarcomas, 1/5 epithelioid sarcomas and 1/18 malignant neural tumours. Five carcinosarcomas showed positive staining of their epithelial components but negative staining of their spindle cell components; three out of four pure spindle cell carcinomas stained positively; a metastasis from a spindle cell renal carcinoma was negative. A spindle cell thymoma also stained positively. Thirty-seven of the 40 carcinomas stained positively; the three negative carcinomas were a squamous cell carcinoma, a renal cell carcinoma and an oat cell carcinoma. All malignant melanomas were negative. These results are compared with those of other workers and the sensitivity and specificity of CAM 5.2 as an epithelial marker is assessed.

Immunohistochemical demonstration of cytokeratins in the human prostate

The behaviour of keratins in the human prostate is investigated immunohistochemically by polyclonal rabbit antibodies against keratins from human stratum corneum (kit from ORTHO/Heidelberg) and compared to the behaviour of prostatic acid phosphatase (PAP) and prostate-specific antigen (PSA). In normal glands and cribriform as well as adenomatous hyperplasia only basal cells contain keratin. The secretory epithelium is keratin-negative and in contrast to the basal cells PAP- as well as PSA-positive. In prostatic ducts and utriculus prostaticus keratin is demonstrable in basal cells and urothelium. As in normal glands, the light cylindric epithelium is keratin-negative and PAP- as well as PSA-positive. The cells in atrophic glands and postatrophic hyperplasia may contain keratin as well as PAP and PSA. Urothelial and squamous metaplasia are strongly keratin-positive. PAP and PSA are not found. The cylindric epithelium of the ejaculatory ducts contains keratin at many places. PAP and PSA are not demonstrable. The utriculus does not differ from normal prostatic glands immunohistochemically. This supports the view that the epithelium of the sinus urogenitalis is involved in the embryogenesis of normal prostatic glands and the utriculus as well. Urothelial and squamous metaplasia obviously arise from basal cells which share the same immunohistochemical features. Whether the cells in atrophic glands and postatrophic hyperplasia derive from basal cells or secretory epithelium cannot be decided. The keratin composition of the prostate should be further analyzed by keratin-specific monoclonal antibodies.

Keratin polypeptide distribution in benign and malignant breast tumors: subdivision of ductal carcinomas using monoclonal antibodies

Monoclonal antibodies which recognize one or only a few keratin polypeptides have been used to study the distribution of different keratins in benign and malignant breast lesions by immunocytochemical methods. Seven monoclonal antibodies which recognized either different keratin polypeptides by immunoblotting techniques, or identified different epithelial cell types in complex tissues were used. In two mastopathies and three fibroadenomas the antibody lu5 stained luminal cells as well as myoepithelial cells. In contrast the antibodies CK7, Troma 1, CK2 and KA4 labeled only luminal cells, whereas antibody CKB1 decorated only myoepithelial cells. All 15 ductal carcinomas showed a uniform staining of tumor cells with the antibodies Troma 1, CK2, KA4 and lu5. The antibody CK7 also stained all ductal carcinomas, but in two specimens the staining was heterogeneous. The antibody CKB1 decorated only the pre-existing myoepithelial cells in 11 of 12 ductal carcinomas but in the remaining specimen the tumor cells were also strongly positive. Tumor cells in lobular carcinomas were labeled by antibodies CK7, Troma 1, CK2, KA4, bu not by CKB1. The antibody CKS1 showed no staining of any of the benign and malignant breast lesions.

The immunohistochemical detection of lymph node metastases from infiltrating lobular carcinoma of the breast

Immunological markers improve specificity and accuracy of cell detection, therefore it is important to evaluate their usefulness in improving standard histological procedures. This study investigates whether immunocytochemical techniques increase the accuracy of detection, in axillary lymph nodes, of metastatic cells from infiltrating breast lobular carcinoma (ILC). Fifty cases of ILC reported to be node-negative were selected. New serial sections were cut from a total of 767 lymph nodes, stained with H&E and tested in immunoperoxidase (ABC procedure) with a conventional anti-Epithelial Membrane Antigen (EMA) serum, with a monoclonal raised against human milk fat globule membranes (HMFG-2) and with a monoclonal against 54 kd keratin. Metastases were detected immunocytochemically in 12 cases (24%); in five of these cases metastatic cells were also visible in serial H&E sections. Monoclonals offered no evident advantage over anti-EMA conventional antiserum. Immunocytochemical positivity alone is not sufficient evidence for metastatic invasion since macrophages occasionally appear EMA- and HMFG-2-positive (probably because of secondary incorporation of the antigen), and so an improvement in the accuracy of breast cancer metastatic cell detection in axillary lymph nodes requires a combined histo-immunological approach.

A monoclonal antibody CIBr17 recognizes a myoepithelium-specific antigen in human mammary gland

A murine monoclonal antibody (MAb) CIBr17, raised against the human breast carcinoma cell line PMC42, reacts specifically with myoepithelial cells in normal human breast. This IgGl antibody recognizes a approximately 110kDa glycoprotein that is expressed on the cell surface and junctional membranes of PMC42 monolayer cultures. The CIBr17 antigen is present in two major glycosylated forms with approximate pls of 5.2 and 5.5 respectively in PMC42 cells. The tissue specificity of CIBr17 was assessed on frozen sections of PLP-fixed tissues by means of a 4-layer immunoperoxidase technique. CIBr17 has reacted with a variety of epithelium-derived tissues and some smooth muscle cells. Within many epithelial tissues, CIBr17 has demonstrated specific staining of particular epithelial cell types. Within normal breast and most benign breast lesions, antibody CIBr17 stained only myoepithelial cells. No staining of luminal epithelium, basement membranes or stromal elements was observed. In sclerosing adenosis, CIBr17 stained areas of pronounced myoepithelial differentiation, while in duct epitheliosis variable staining of proliferating cells was observed. In breast carcinomas, CIBr17 demonstrated variable antigen expression. In most tumors, CIBr17 either did not stain any tumor cells or stained only a small number of tumor cells spread randomly throughout the tumor. In several ductal carcinomas, however, CIBr17 stained the majority of tumor cells.

Distinction of mesothelioma from adenocarcinoma. An immunohistochemical approach

The authors investigated the expression of keratin, carcinoembryonic antigen (CEA), and an epithelial marker derived from milk fat globule membranes in 12 mesotheliomas and 100 diverse adenocarcinomas with immunohistochemical methods. The authors employed a monoclonal antibody to keratin designated as AE1, as well as the following commercially available antisera: rabbit anti-whole human keratin, rabbit anti-CEA, and a monoclonal antibody to an epithelial factor designated as MFG-2. Expression of keratin was found in all the mesotheliomas and adenocarcinomas with antibody AE1 as well as with the rabbit antiserum; CEA was detectable in 65% of the adenocarcinomas but two mesotheliomas also reacted weakly. With antibody MFG-2, positive results were obtained in 85% of the adenocarcinomas and in none of the mesotheliomas. All of 64 (100%) breast-, lung- and ovary-derived adenocarcinomas immunostained positively with antibody MFG-2. This is of particular significance because pulmonary and ovarian adenocarcinoma frequently may be indistinguishable clinically and histologically from epithelial mesothelioma. The authors conclude that antikeratin antibodies are not useful in the distinction of adenocarcinoma from mesothelioma. Because of its greater sensitivity and specificity, MFG-2 is superior to CEA in this differential diagnosis.

Identification of basement membrane components and intermediate filaments in calcifying epithelial odontogenic tumors

An immunohistochemical technique was used on paraffin-embedded tissues of four cases of calcifying epithelial odontogenic tumors (CEOT). These studies were performed to gain an additional understanding of the nature of amyloid-like deposits in these tumors. For these studies antibodies to Type IV collagen, laminin, and the five classes of intermediate filament proteins were employed. In all of the tumors examined basement membrane components and intermediate filament proteins (cytokeratin) were demonstrated both in the epithelial tumor islands and within the extracellular amyloid-like deposits. Antibodies to vimentin intermediate filaments were localized only in the stromal fibroblasts. Limited proteolysis or the use of a chaotropic agent was required to express the antigenic determinants present. These studies substantiate the presence of basement membrane components in the amyloid-like deposits of CEOT. In addition, these extracellular deposits are shown to be heterogenous in composition by the immunohistochemical demonstration of cytokeratin intermediate filament proteins.

Malignant myoepithelioma (myoepithelial carcinoma) of the breast: an ultrastructural and immunocytochemical study

This report describes the light (LM) and electron microscopic (EM) features and the results of an indirect immunofluorescence study (IF), the latter using monoclonal and monospecific antibodies to cytoskeletal proteins, of a malignant, invasive and metastatic breast myoepithelioma. A 53-year-old female underwent mastectomy for a large necrotic mammary tumor that had invaded the overlying skin. By LM, the neoplasm was composed of interlacing bundles of large, elongated and interspersed stellate cells with acidophilic cytoplasm. The neoplastic cells displayed a moderate degree of anaplasia, high mitotic activity, and strong tendency for necrosis. Stromal desmoplasia was marked, especially toward the center of the neoplasm. By IF, the tumor cells revealed bright cytoplasmic fluorescence with antibodies to actin, prekeratin, and cytokeratin. A few scattered spindle cells, which stained with the anti-vimentin and anti-actin anti-bodies, most likely represented stromal myofibroblasts. The anti-desmin reaction was negative. By EM, the neoplasm was composed of variably differentiated, elongated and stellate myoepithelial cells connected by desmosomes, enveloped by remnants of basal lamina, and containing pinocytotic vesicles, a well-developed rough endoplasmic reticulum, large Golgi areas, aggregates of intermediate filaments that were often arranged in dense curvilinear bundles (tonofilaments), and bundles of microfilaments with fusiform, dense bodies. The combined LM, EM, and IF study of this mammary tumor establishes its myoepithelial origin and, thus, identifies it as myoepithelial carcinoma distinct from other spindle cell breast tumors. This neoplasms was locally invasive and cytologically malignant; moreover, its malignancy was further confirmed by the development of lung and pleural metastases.

Ultrastructural and immunohistochemical features of lobular carcinoma of the breast

Twenty cases of infiltrating lobular carcinoma (12 of classical type, five of trabecular type and three of alveolar type) and one case of lobular carcinoma in situ were studied by transmission electron microscopy. The in situ component in three of the infiltrating carcinomas was also studied. The ultrastructure of the tumour cells in the alveolar variant of infiltrating lobular carcinoma was the same as seen in the tumour cells of lobular carcinoma in situ. The tumour cells in infiltrating lobular carcinoma of the classical and trabecular types had more irregular nuclei and were more organelle- and filament-rich. Immunohistochemical staining for the presence of alpha-lactalbumin was proved in 19 per cent of the cases, casein 81 per cent, CEA in 65 per cent and prekeratin in 90 per cent. The light microscopic separation of some subgroups of infiltrating lobular carcinoma may be difficult, in particular the distinction between the classical and the trabecular variants. Unfortunately, our study shows that these distinctions cannot easily be made either by electron microscopy or by light microscopic immunohistochemistry with antibodies against prekeratin, CEA, casein and alpha-lactalbumin.

Antikeratin antibodies in tumor diagnosis. Distinction between seminoma and embryonal carcinoma

The authors investigated the presence and distribution of keratin in germ cell tumors using a rabbit-anti-keratin antiserum and a monoclonal antikeratin antibody--which is specific for keratin classes of 40, 50, and 56.5 kdaltons--by various immunohistochemical methods on frozen sections, alcohol-fixed, and formalin-fixed paraffin-embedded tissues. Thirty-four germ cell tumors were studied. These were the following: 18 seminomas, 10 embryonal carcinomas, 2 teratocarcinomas, 3 yolk sac tumors and 1 choriocarcinoma. All seminomas, including four poorly differentiated (so-called anaplastic seminomas), gave negative results, regardless of the method employed. Embryonal carcinoma, the epithelial component of the teratocarcinoma, the yolk sac tumors, and choriocarcinoma were at least focally positive for keratin. The monoclonal antibody provided a cleaner background and stronger staining than the rabbit-anti-total-human-epidermal-keratin antibody. Best results were obtained from fresh-frozen sections or alcohol-fixed, paraffin-embedded materials. Formalin-fixed, nonseminomatous tumors, when predigested with trypsin and incubated overnight with primary antibody, gave no false-negative results but staining was often focal. The authors' results agree with the reported absence of detectable keratin in primordial germ cells of the normal testis, and with prevailing concepts of the histogenesis of germ cell tumors. These results indicate that the presence or absence of keratin by immunocytochemical methods can be helpful in distinguishing seminoma from embryonal carcinoma.

Keratins in malignant mesotheliomas and pleural adenocarcinomas: comparative immunohistochemical analysis with polyclonal and monoclonal antibodies

The distribution of intra-cellular keratins was studied in normal pleural mesothelium, malignant mesotheliomas and adenocarcinomas. This study was performed on deparaffinized sections of tissue fixed in Bouin's solution by indirect immunofluorescence with a monoclonal antibody (KL1) and a conventional keratin antiserum (AKS). Discrepancies were detected using one antibody or the other. Cells from normal mesothelium and 18 cases of malignant mesotheliomas (papillary, tubulary, solid epithelial type) were strongly labelled only by KL1. The 2 cases of sarcomatoid type were negative with both antibodies. In contrast 5 metastatic adenocarcinomas and 5 lung adenocarcinomas were weakly positive or negative with both antibodies. These data confirm the presence of cytokeratins in epithelial differentiation process. Although a clear-cut distinction between mesotheliomas and adenocarcinomas was not possible using these keratin antibodies. Our data point out the importance of reactivity pattern of the antibody used in such investigations.

Normal rabbit Merkel cells do not express neurofilament proteins

Three hundred and five normal Merkel cells (MC) were studied in rabbit lip specimens by a double indirect immunofluorescence technique using both neurofilament (NF) antiserum and a monoclonal antibody to rabbit MC. NF proteins were not found to be expressed in MC. This suggests that MC are not neural cells and that NF-positive neuroendocrine carcinomas of the skin do not derive from MC.

Immunocytochemical demonstration of intermediate filaments in a granular cell ameloblastoma

The nature and location of intermediate filament proteins (IFP) may provide new insights into the origin and differentiation of neoplastic cells. An immunofluorescent study of these IFP in a case of a granular cell ameloblastoma revealed that all tumor cells contained the IFP keratin. Some granular cells, however, also contained the IFP vimentin, which is considered specific for mesenchymal tissues only. The implications of these observations are discussed. Study with monoclonal antibodies indicated the origin of the ameloblastoma from non-keratinized squamous epithelium. A comparison of the anti-keratin immunofluorescence pattern of the ameloblast-like cells in the present tumor with ameloblasts in the tooth germ revealed no similarities, indicating that despite some resemblance of the peripheral columnar cells to ameloblasts, these cells differ in other aspects.

Diagnostic value of intermediate filament antibodies in clinical cytology

Antibodies to intermediate filament (IF) proteins can distinguish the major tumour groups as shown by results with sectioned human material. In this study we evaluate the use of similar methods in the cytology of human tumors. Smears obtained from fine needle aspiration biopsies were investigated using well characterized antibodies, each specific for only one of the five types of intermediate filaments. Tumor cells of different carcinomas, thymomas, and the epithelial part of pulmonary blastomas were positive with antibodies recognizing cytokeratins. Tumor cells in non-muscle sarcomas, including lymphoma and Ewing's sarcoma, could be specifically identified with antibodies to vimentin. Tumor cells of muscle sarcomas were desmin-positive. Finally, tumor cells in pheochromocytoma and bronchus carcinoid were positive with antibodies specific for neurofilaments. Specimens were also examined in parallel using conventional cytochemical stains, such as May-Grünwald-Giemsa. In addition, in most cases sections of the tumor were examined both by histology and IF typing of frozen sections to confirm the diagnosis made on the cytologic specimens. The results show that IF typing is a valuable diagnostic aid in clinical cytology.

Esthesioneuroblastoma: ultrastructural, immunohistological and biochemical investigation of one case

A case of esthesioneuroblastoma, the pathological diagnosis of which almost always causes great difficulties, was investigated ultrastructurally, biochemically, and immunohistologically, using antibodies against the five known types of intermediate filaments [keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and neurofilaments]. The tumour cells did not react with antibodies against any of the five intermediate filament proteins. Ultrastructural investigations showed dense cored secretory granules in the cytoplasm and cell processes. Thus, immunohistology offers by "exclusion" a differential diagnosis to avoid often misdiagnosed tumours (undifferentiated carcinomas, embryonal rhabdomyosarcomas, and malignant lymphomas), since carcinomas react with antikeratin, embryonal rhabdomyosarcomas with antibodies to desmin and malignant lymphomas show immunofluorescence with antibodies to vimentin. The biological behaviour (age distribution, tendency to metastasize), the normal values of biochemical parameters, homovanillic acid and vanilmandelic acid (HVA, VMA), and the absence of neurofilaments distinguish this type of tumour from the peripheral sympathetic neuroblastoma.

Coexpression of keratin and vimentin filaments in adenoid cystic carcinomas of salivary glands

Six cases of adenoid cystic carcinoma of salivary glands have been examined with antibodies specific for either keratin or vimentin. Tumor cells in all six cases showed coexpression of keratin and vimentin.

Antibodies to intermediate filament proteins in the diagnosis and classification of human tumors

Immunohistochemistry of intermediate filaments (IF) is a new and important way to evaluate the epithelial, mesenchymal, muscular, glial, or neural differentiation in tumors. This is based on the stable cell-type-specific expression of IF proteins in normal and neoplastic tissues. Immunohistochemical studies with antibodies to intermediate filaments have also given new perspectives in the histogenesis and biologic nature of many tumors. This article reviews both the recent findings and the authors' experience in the use of intermediate filament antibodies in tumor diagnosis and classification.

The organization of intermediate filaments in normal human colonic epithelium and colonic carcinoma cells

A comparative ultrastructural study of the organization of intermediate filaments (tonofilaments) within normal colonic epithelium and colonic carcinoma cells was carried out. The pattern of development of the specialized intermediate filament (IF) network, occurring during the differentiation of normal colonic epithelial cells, was examined to allow a more complete comparison with tumour cells of different degrees of differentiation. Essentially the IF system becomes more organized as the cells differentiate, resulting in the formation of a three-dimensional network loosely surrounding the nucleus, extending through the sub-terminal web and basal cytoplasm, and inserting into lateral desmosomes. Another system of IFs also runs directly between lateral desmosomes, lying parallel to the plasma-membrane and desmosomal plaque, without inserting directly into the junction. Alterations in the organization of the IF system were seen in tumour cells with the type and extent being dependent upon their location and degree of differentiation. Cells within areas of the tumour where some degree of glandular structure was retained exhibited major alterations in their microfilament-containing structures. However, their IF system was essentially intact and lateral desmosomes were still present in similar numbers to those seen in normal, partially differentiated mid-crypt cells. Apolar tumour cells within areas of the tumour where a gross loss of cryptal architecture had occurred exhibited a striking disorganization of their IF system. No parallel bundles of interdesmosomal tonofilaments were present beneath the cell surface and the majority of the three-dimensional network appeared to have collapsed around the nucleus, although some extensions to randomly distributed surface desmosomes still occurred. It appears that this disorganization of the IF system is associated with a loss of cell polarity and may involve alterations in putative IF-associated proteins important in the interaction of IFs with surface desmosomes or other cytoskeletal elements. A study of this phenomenon may shed light on both the means of IF organization and assembly and their role in normal cells as well as the possible role of alterations in cytoskeletal elements in the expression or maintenance of the malignant phenotype.

Antibodies to intermediate filament proteins in the immunohistochemical identification of human tumours: an overview

Intermediate-sized filament proteins (IFP) are tissue specific in that antibodies to keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and the neurofilament proteins can distinguish between cells of epithelial and mesenchymal origin as well as of myogenic and neural origin respectively. Malignant cells retain their tissue-specific IFP, which makes it possible to use these antibodies in tumour diagnosis. Carcinomas are exclusively detected by antibodies to keratin. Monoclonal antibodies to keratin have allowed the differentiation between subgroups of epithelial tumours until now between adenocarcinomas and squamous cell carcinomas. Lymphomas, melanomas and several soft tissue tumours are distinctly recognized by antibodies to vimentin. On the other hand, rhabdomyosarcomas and leiomyosarcomas are positive for desmin, while astrocytomas give a strong reaction with GFAP antibodies. Thus, antibodies to IFP are useful tools for differential diagnosis in surgical pathology.

Mediastinal tumors: ultrastructural and immunohistochemical evaluation of intermediate filaments as diagnostic aids

The histogenesis of six mediastinal tumors was investigated ultrastructurally and immunohistochemically using monospecific antibodies against intermediate filament proteins. Four of the tumors, showing different appearances by light microscopy, displayed desmosomes and cytoplasmic tonofilaments, by electron microscopy, compatible with an epithelial thymoma. These cases also showed keratin positivity by immunofluorescence microscopy. One spindle cell tumor showed zonula adherens-type junctions, prominent collections of intermediate filaments, and abundant cytoplasmic neurosecretory granules consistent with a neuroendocrine tumor. In this tumor, neurofilaments could be demonstrated by immunofluorescence microscopy, a feature also consistent with a neuroendocrine tumor. One malignant tumor, lacking tonofilaments and desmosomes but showing a few primitive junctions, did not contain keratin but showed vimentin positivity. This suggests a mesenchymal origin and a diagnosis of primitive sarcoma. These cases illustrate the diagnostic usefulness of electron microscopy and immunohistochemical evaluation of intermediate filaments.

Presence of fibroblast-type intermediate filaments (vimentin) and absence of neurofilaments in pigmented nevi and malignant melanomas

The cytoskeletal intermediate filaments of pigmented nevi and malignant melanomas (nine cases of each) were evaluated using monospecific antibodies against intermediate filament proteins and immunofluorescence microscopy. Both pigmented nevi and cutaneous malignant melanomas showed only vimentin-type intermediate filaments, but not keratin, neurofilaments, desmin or glial fibrillary acidic protein. Thus, nevi and melanomas do not show neural characteristics in the cytoskeletal intermediate filament pattern although they appear to show other neural markers. Vimentin - content in melanomas versus keratin - content in carcinomas may be used as a differential diagnostic feature.

Intermediate filaments in malignant melanomas. Identification and use as marker in surgical pathology

Intermediate-sized filaments have been studied in human malignant melanomas and in normal melanocytes by immunofluorescence microscopy with antibodies directed against keratin, vimentin, desmin, neurofilament protein, and glial filament protein. Both human melanotic and amelanotic tumor cells and tumor metastases as well as normal melanocytes in human skin and in the rat eye contain exclusively intermediate filaments of the vimentin type. No reaction was seen with antibodies to keratin, desmin, neurofilaments, or glial filaments. These latter four antisera, however, gave strong reactions in epidermis and other epithelial tissues, muscle, or neural tissues, respectively. The results favor a mesenchymal character of melanocytes, although a neuroectodermal origin in an early developmental stage is possible. The finding that melanomas contain exclusively vimentin intermediate filaments may prove useful in differential diagnosis of melanomas from other tumor types.

Neuroendocrine carcinoma of the skin (Merkel cell carcinoma): ultrastructural and immunohistochemical demonstration of neurofilaments

In this study we characterized a skin tumor that grew in the temporal region of a 69-year-old woman. On the basis of tumor morphology, a metastasis from a small cell carcinoma of the lung was initially suggested, but X-ray and bronchoscopic studies were negative. The tumor recurred twice within a year, yet no tumors were found elsewhere in the body. Ultrastructurally, cytoplasmic organelles compatible with neuroendocrine storage granules and perinuclear aggregates of intermediate-sized (8-10 nm) filaments were found in many tumor cells. Indirect immunofluorescence microscopy revealed neurofilament-type intermediate filaments in the tumor cells but no keratin- or vimentin-type filaments. Our results further demonstrate neural properties of this tumor type, which is generally considered to have its origin from Merkel cells, the cutaneous neuroendocrine cells.

Malignant melanomas contain only the vimentin type of intermediate filaments

Six malignant melanomas have been examined for the type of intermediate filament they contain. All six cases showed positive staining of intermediate filaments with antibodies to vimentin, with cells containing large numbers of melanosomes being stained less strongly in general. The tumor cells did not react with antibodies to keratin, desmin, neurofilaments or glial fibrillary acidic protein. Thus typing of intermediate filaments can distinguish melanoma from undifferentiated carcinoma, but not from lymphoma or sarcoma. Since melanocytes are known to be vimentin positive, and since most of the samples we studied were from metastases, these results are a further indication that the intermediate filament type typical of the parental cell is retained in the metastases, as well as in the primaries of solid tumours. The implications of vimentin positivity for the histiogenesis of the melanocyte are also discussed.

Is renal cell (Grawitz) tumor a carcinosarcoma? Evidence from analysis of intermediate filament types

The expression of intermediate filament type was determined in 13 renal cell (Grawitz) tumors (10 primary renal tumors and 3 lymph node metastases). All of the tumors except one lymph node metastasis contained cells expressing vimentin intermediate filaments, generally a marker of mesodermally-derived tissues and their tumors, the sarcomas. In addition, the 10 primary renal tumors and two lymph node metastases contained cells expressing keratin proteins. Using a monoclonal antibody to keratins, specific for glandular epithelial cells, it has been shown that some of the tumor cells resemble adenocarcinomas, at least in this respect. Double immunofluorescence labeling demonstrated that some of the vimentin-containing cells contained keratin while others did not. Only occasional cells were found to contain keratin but not vimentin. However, one of the lymph node metastases was positive only for vimentin. Thus Grawitz tumor cells express intermediate filament types which are generally biological markers of both sarcomatous and carcinomatous tumors.

Monoclonal antibodies to desmin, the muscle-specific intermediate filament protein

A set of monoclonal antibodies to desmin has been isolated from a fusion of mouse myeloma cells with spleen cells from mice immunized with purified porcine desmin. Eleven group I antibodies recognized desmin in the immune blot, and using defined desmin fragments the epitope has been tentatively assigned as lying between residues 325 and 372. When cell lines were tested in immunofluorescence only the human line RD and hamster BHK-21 were positive. When tissue sections were used, skeletal, cardiac, visceral and some vascular smooth muscle cells were positive. Thus, the group I antibodies appear specific for desmin and do not recognize other intermediate filament proteins. Group II monoclonals recognized not only desmin in the immune blot but also other polypeptides. The epitope of this class is located between residues 70 and 280. In immunofluorescence on cell lines and tissues, the staining patterns of group II antibodies were more complicated and demonstrate that not only other intermediate filament proteins but also additional antigenic determinants are being recognized. The group I antibodies stain, as expected from their desmin specificity, rat and human rhabdomyosarcomas and thus appear to be useful reagents in pathology.

Immunocytochemical identification of epithelium-derived human tumors with antibodies to desmosomal plaque proteins

Epithelial cells contain desmosomes, special intercellular junctions providing sites of membrane attachment for intermediate-sized filaments of the cytokeratin type (tonofilaments). Such sites of anchorage of tonofilaments appear as dense plaques on the cytoplasmic side of the desmosomal membrane. We have isolated desmosome-enriched fractions from bovine snout epidermis and tongue mucosa and have characterized the major protein associated with the desmosomal plaque. This protein occurs in equimolar amounts of two polypeptides of Mr 250,000 (desmoplakin I) and Mr 215,000 (desmoplakin II) which are chemically and immunologically related. Antibodies raised against desmoplakins allow the identification and localization of this protein in epithelial cells grown in tissues or in vitro and show crossreaction in species as diverse as man, mouse, and chicken. Using immunolocalization at the light and electron microscope levels, we show that these antibodies bind specifically to desmosomal plaques. Antibodies to desmoplakins have been used successfully for detection of desmosomal proteins in a broad variety of epithelium-derived human tumors, including primary carcinomas and their metastases, irrespective of the morphology of the specific tumor. Nonepithelial tumors examined have been negative. We propose to use antibodies to desmoplakins and to cytokeratins in pathological diagnosis as two independent markers for the positive immunocytochemical identification and classification of epithelium derived tumors.

Intermediate filaments and their interaction with membranes. The desmosome-cytokeratin filament complex and epithelial differentiation

Intermediate-sized filaments represent a class of morphologically similar but biochemically and immunologically distinguishable cytoplasmic protein polymer structures. Five major filament types have been identified (cytokeratin, vimentin, desmin, neurofilament protein, glia filament protein) and antibodies to these proteins have been used for distinguishing different cell types and tumors derived therefrom. Epithelial and carcinoma cells are characterized by the presence of cytokeratin filaments and desmosomal elements identified by antibodies to certain high molecular weight proteins of desmosomal plaques. However, the specific pattern of cytokeratin polypeptides is different in different epithelia. The potential value of cell type identification by immunological reactions with antibodies to cytoskeletal proteins in tumor diagnosis is discussed.

The cytoskeleton in tumor cells

During the past few years several laboratories investigated the occurrence of cytoskeletal components in epithelial and mesenchymal cells by electron microscopy and/or immunocytochemical methods in a number of tumor types growing in vitro or in the body. Since it is well established that antibodies to different intermediate-sized filament proteins can distinguish cells and tissues of epithelial, mesenchymal, muscle, astrocytic and neural origin special attention has been paid to the behaviour of these filaments in neoplastic cells recently. While the organisation of the cytoskeleton in tumor cells growing in vitro is very variable, regularities relevant for the diagnosis and the determination of the histogenetic origin of tumors have been observed in tumor cells growing in the body. In general, ultrastructural and immunological features of intermediate filaments are maintained during neoplastic transformation in the body. Thus immunofluorescence microscopy with antibodies to cytoskeletal proteins is a powerful tool for the classification and differential diagnosis of tumors, especially for the distinction between epithelial and mesenchymal tumors, including metastases. The concept that presence of an excess of contractile proteins such as actin is an important prerequisite for the metastatic spread of malignant cells has not been unequivocally supported by more recent results. However, an accumulation of various types of intermediate filaments (e.g. prekeratin, vimentin, acidic glial fibrillar protein) has been shown in different tumor types. The further elucidation of this alteration could contribute to a better understanding of the molecular mechanisms of neoplastic cell transformation.

The expression of different intermediate-sized filaments in human salivary glands and their tumours

The intermediate-sized filaments can be divided into several groups which are characteristic of different types of tissues (e.g.: epithelial, mesenchymal, muscle, astrocytic and neural origin). Antibodies specific for some of these filament types have been used to analyse a group of salivary gland tumours. Prekeratin-positive cells were seen in the normal gland, cystadenolymphomas, mucoepidermoid tumours, and squamous cell carcinomas which are all tumours of epithelial origin. The pleomorphic adenomas showed the presence of some cells which appeared to contain both prekeratin and vimentin. The results are discussed with respect to their histogenetic implications.