Distribution of vitamin B12 R-binder in lung tumors. Implications for cell differentiation

Expression of vitamin B12 R-binder, a specific binding protein for vitamin B12, was studied immunohistochemically in normal lung tissues and 107 lung tumors of various types. In normal tissues, vitamin B12 R-binder (R-binder) expression was restricted to the mucous cells of bronchial or bronchiolar epithelium and submucosal glands as well as to nonciliated bronchiolar (Clara) cells. Among lung carcinomas, 38% of squamous cell carcinomas, 42% of adenocarcinomas and 23% of large cell carcinomas showed positive staining for R-binder whereas small cell carcinomas did not. These findings offer the possibility that a majority of the histologic types of lung carcinoma have common histogenetical characteristics with mucous or Clara cells. Of the bronchial gland tumors, R-binder could be detected in a mucoepidermoid carcinoma but not in adenoid cystic carcinomas. Epithelial components in both pulmonary blastomas and hamartomas showed a reactivity for R-binder, suggesting that these tumors contained components composed of cells with bronchiolar cell differentiation. The immunohistochemical examination of lung tumors, using anti-R-binder antibody, may have some implications in the cell differentiation of lung tumors.     

Expression of surfactant associated protein-A and Clara cell 10 kilodalton mRNA in neoplastic and non-neoplastic human lung tissue as detected by in situ hybridization.

Two markers for the progenitor cells of peripheral airways and their tumors are the 10 kilodalton (kd) Clara cell protein and the major surfactant associated protein-A (SP-A). We used the RNA-RNA in situ hybridization technique to study expression of the genes encoding these proteins at the cellular level in 19 pairs of non-neoplastic and neoplastic tissues from resected human lungs. Our results show that in non-neoplastic lung tissue, the Clara 10 kd protein gene was expressed in nonciliated cells of both bronchial and bronchiolar epithelium, indicating that, in contrast to previous assumptions, cells with Clara cell-like differentiation in humans may not be restricted to bronchiolar cells. The incidence of Clara 10 kd protein gene expression, as detected in lung carcinomas (1 out of 19 cases positive) was less than expected based on previous ultrastructural reports. The SP-A gene was strongly expressed in normal alveolar type II cells in non-neoplastic lung and, at higher levels, in hyperplastic cells. In addition, SP-A mRNA expression was observed in scattered bronchial and bronchiolar epithelial cells in 40% of the airways examined. Five out of 17 lung tumors, all of which were adenocarcinomas, were positive for SP-A expression, albeit generally less intense than type II cells. This expression was seen in carcinomas with papillolepidic as well as solid and glandular growth patterns. Our findings provide new insights into the peripheral airway cell differentiation.     

Incomplete expression of epithelial-mesenchymal transition markers in idiopathic pulmonary fibrosis

The hypothesis that epithelial-mesenchymal transition (EMT) contributes to the formation of fibroblast foci (FF), which are the histological hallmark and the site of active disease progression of Idiopathic Pulmonary Fibrosis (IPF), has not yet received a conclusive demonstration. Cells undergoing EMT lose epithelial features and acquire mesenchymal markers and morphology. Cadherin expression switch (from E to N) is one of the first events in EMT.We investigated the immunohistochemical expression of E- and N-cadherin, vimentin, fibronectin, laminin-5-γ2, α-smooth muscle actin, and fibroblast-specific protein-1 involved in EMT in 20 IPF lung biopsies, focusing on metaplastic squamous cells of bronchial basal origin, positive for laminin-5-γ2 and ΔNp63/p40, that cover FF. The results were compared with organizing pneumonia, reactive squamous cell metaplasia of bronchiolar epithelia, and squamous cell carcinoma.Bronchiolar basal metaplastic cells in IPF partially lost E-cadherin and expressed vimentin and fibronectin. Hyperplastic pneumocytes in IPF and controls coexpressed E-cadherin and N-cadherin, and were weakly positive for lam5-γ2. Reactive squamous cell metaplasia did not show any mesenchymal markers. Squamous cell carcinoma only expressed lam5-γ2.In IPF lungs, we observed two epithelial cell populations with a different expression profile of markers involved in EMT. Although neither hyperplastic pneumocytes nor bronchial basal cells showed evidence of complete EMT, only the latter seem to be specific for UIP and might have a role in its development.     

hnRNP B1 expression in benign and malignant lung disease

Evidence is accumulating to suggest that hnRNP B1 expression may be a useful tool in the early diagnosis of lung cancer. This study examined the immunohistochemical expression of hnRNP B1 in archived sections of resected lung cancers and compared the patterns of expression with those seen in similar archived sections of non-neoplastic lung. Particular attention was paid to the expression of hnRNP B1 in the benign bronchial cells in both cases, to establish if overexpression of this protein in respiratory epithelial cells is specific for malignancy. Nineteen cases of different types of non-small cell carcinoma were examined (eight squamous cell, six adenocarcinomas, two carcinosarcomas, two undifferentiated large cell carcinomas, and one mucoepidermoid carcinoma) and compared with sections from 16 open lung biopsies (three cases of cryptogenic fibrosing alveolitis, two cases of sarcoidosis, two cases of organizing pneumonia, and one case each of tuberculosis, extrinsic allergic alveolitis, non-specific interstitial pneumonitis, pneumocystis pneumonia, aspergilloma, respiratory bronchiolitis-interstitial lung disease, mineral dust disease, Sj?gren's syndrome and systemic sclerosis vascular variant). All the tumours showed positive staining, with the vast majority, 16/19 (84%), showing strong diffuse nuclear staining. The background cells of these cases showed positive staining in alveolar macrophages, lymph node germinal centres, bronchial mucous glands, and bronchial epithelial cells. No significant difference was seen in the percentage of positive bronchial epithelial cells in bronchi adjacent to the tumour compared with the resection margins. In the benign lung cases, positive bronchial epithelial cells were seen in a small percentage, 3/16 (18%), of cases, but the majority of cases showed no or very focal staining. The levels of expression between benign epithelial cells of malignant cases, compared with benign, showed a significant difference when the staining was assessed in percentage of positive nuclei (p = 0.001, Fisher's exact test). The results confirm that hnRNP B1 is widely expressed in a range of lung carcinomas; that expression is seen in benign bronchial epithelial cells and inflammatory cells; and that expression in background bronchial epithelial cells appears to be higher in malignant than in benign lung disease. It is feasible that this biomarker may be of use in the detection of early lung cancer, provided that levels of expression can be accurately quantified.     

P63 in pulmonary epithelium,pulmonary squamous neoplasms,and other pulmonary tumors

p63 is a p53-homologous nuclear protein that appears to play a crucial role in regulation of stem cell commitment in squamous and other epithelia. In this study, p63 expression was examined in benign lung and in neoplasms of pulmonary origin. Eighty sections from routinely fixed and processed archival bronchoscopic biopsy or lobectomy specimens were pretreated with citric acid (pH 6.0) for antigen retrieval, then incubated overnight with anti-p63 monoclonal antibody 4A4. Slides were stained using a streptavidin-biotin kit and diaminobenzidine as chromagen, and were counterstained with hematoxylin. In normal lung, p63 intensely stained nuclei of bronchial reserve cells but did not stain ciliated cells, alveolar epithelial cells, or nonepithelial cells. The lower strata of squamous metaplastic bronchial epithelium stained positively. All squamous-cell carcinomas stained positively (n = 30). In some well-differentiated carcinomas, staining was found at the periphery of tumor nests but was negative in central zones showing squamous maturation. Poorly differentiated carcinomas showed very high proportions (80% to 100%) of p63-positive nuclei. All small-cell carcinomas were p63 negative (n = 9). Staining of bronchioloalveolar carcinomas (n = 7) and adenocarcinomas (n = 23) was variable: some tumors showed no detectable staining, others showed heterogeneously positive staining. Adenosquamous carcinomas (n = 5) displayed a unique basalar staining pattern. Carcinoid tumors were almost entirely negative (n = 5). We conclude that p63 is expressed in benign bronchial stem cells, in neoplastic cells with either squamous differentiation or squamous differentiating potential, and in a subpopulation of adenocarcinomas. p63 immunostaining may also aid in some histopathologic distinctions, such as in small biopsies where the differential diagnosis is poorly differentiated squamous carcinoma versus small-cell carcinoma. A stem cell biology-based classification system for squamous carcinomas is proposed.     

Immunolocalization of glycodelin in human adenocarcinoma of the lung, squamous cell carcinoma of the lung and lung metastases of colonic adenocarcinoma

Glycodelin (Gd), which is localized in cells of bronchial epithelium, type II pneumocytes and alveolar macrophages in rats and humans, plays an important role in the pulmonary immune response in asthmatic inflammation. In this study, sections of paraffin-embedded tumor adjacent lung tissue and sections of adenocarcinoma of the lung, squamous cell carcinoma of the lung and metastases of colonic adenocarcinoma were investigated for the distribution and expression of Gd using a polyclonal anti-Gd antibody. Glycodelin protein is located in the cytoplasm of bronchial epithelial cells, pneumocytes and alveolar macrophages. Furthermore, Gd is expressed in adenocarcinoma and squamous cell carcinoma of the lung as well as in lung metastases of colonic adenocarcinoma. Densitometric analyses showed a significantly increased expression of glycodelin protein in cancer tissue compared to tumor adjacent lung tissue. The Gd protein level was 1.7–2.6-fold increased in lung carcinoma compared to tumor adjacent lung tissue. The Gd protein level did not differ from each other between the investigated types of cancer tissue. Because these data validate the recent findings of Gd mRNA expression, it may be concluded that glycodelin plays an important role in the pathogenesis of lung cancer and lung metastases.     

Immunohistochemical expression of aminopeptidase N (CD13) in human lung squamous cell carcinomas, with special reference to Bestatin adjuvant therapy

Bestatin, a specific inhibitor of aminopeptidase N (CD13), has been reported to prolong survival time in patients with completely resected stage I lung squamous cell carcinoma. Considering the antitumor mechanism of Bestatin, it is interesting to know whether CD13 is expressed in human lung squamous cell carcinoma. The immunohistochemical expression of CD13 was examined in human lung carcinoma and the question of whether CD13 was immunohistochemically expressed in the interstitial tissue was investigated, mainly in the fibroblasts and blood vessels, surrounding the tumor nests of various kinds of non-small cell lung cancers, especially of squamous cell carcinomas. In Japanese squamous cell carcinoma of the lung, 38 (61.3%) out of 62 cancers were positively stained in the same manner on immunohistochemistry for CD13. The area of interstitial tissue positively stained for CD13 varied depending on the case. To confirm the cell nature of the interstitial tissue with CD13 positivity, double immunohistochemistry using CD34 and alpha-smooth muscle actin was performed. Double immunohistochemistry showed that the majority of CD13-positive cells were slender fibroblastic cells around the blood vessels and some endothelial cells.     

Laminin and type VII collagen distribution in different types of human lung carcinoma: correlation with expression of keratins 14, 16, 17 and 18

The expression patterns of basement membrane components and keratin intermediate filament proteins were studied in normal human bronchial epithelium and 56 lung carcinomas using monoclonal antibodies to laminin, type VII collagen and the individual keratins 14, 16, 17 and 18. In normal lung, laminin and type VII collagen were present between the epithelium and the lamina propria of bronchi and bronchioles. Keratin 14 was expressed in the basal cells, keratin 17 in the basal and some suprabasal cells and keratin 18 in the columnar cells of the bronchi and bronchioles. Keratin 16 was not present in normal bronchial epithelium. Laminin was found in all subtypes of lung carcinoma, but type VII collagen was present only in squamous cell carcinomas, where it showed a reduction in expression with decreasing differentiation. Type VII collagen was not identified in adenocarcinomas, small cell carcinomas or carcinoids. Antibodies to basal cell keratins 14 and 17 also displayed positivity only in squamous cell carcinomas, although no correlation with the degree of differentiation could be observed. Keratin 16 appeared to be a marker of the squamous phenotype, rather than of hyperproliferation. The keratin 18 marker for columnar epithelial cells showed a reaction pattern opposite to that of the basal cell keratins, being extensively present in adenocarcinomas, small cell carcinomas and carcinoids, with less expression in squamous cell carcinomas. This study shows a correlation between the presence of type VII collagen and the basal cell keratins 14 and 17, and a negative correlation between these components and keratin 18. These findings are likely to be useful in identifying lung cancer subtypes.     

Overexpression of aryl hydrocarbon receptor in human lung carcinomas

Exposure to polycylic aromatic hydrocarbons (PAH) has been associated with increased risk of lung cancer. Aryl hydrocarbon receptor (AhR) is known to play an essential role in PAH-induced toxicity. The objectives of this study were to identify and evaluate AhR expression in normal human lung tissues and in lung carcinomas. AhR protein and mRNA levels in human lung cell lines were evaluated with immunoblot and quantitative real-time RT-PCR assays, respectively. AhR protein expression was high in cytosol homogenates of adenocarcinoma (AD) cell lines and AhR mRNA levels corresponded well with AhR protein levels in these cell lines. AhR expression in human lung tissues and carcinomas were examined by means of immunohistochemical staining method. In normal lung tissues, immunostaining was found in the cytosol of bronchiolar epithelial cells. AhR immunostaining was more intense in AD than in squamous cell carcinomas. When AhR expression was compared with noral bronchiolar epithelial cells and neoplastic cells in the same specimens, the neoplastic cells, especially those of AD, demonstrated an increased staining. The upregulation of AhR mRNA expression was also demonstrated among 2 of 4 paired tissues with the quantitative real-time RT-PCR assay. Our data indicated that AhR expression was upregulated in lung AD and suggested that AhR and its expression might play an important role in the development of lung AD.     

Immunohistochemical study of lung adenocarcinoma using monoclonal antibody for 60-kilodalton antigen in type II pneumocytes and nonciliated bronchiolar epithelial cells. Comparison with two antisurfactant apoprotein antibodies

Monoclonal antibody KP16D3 was produced by immunizing mice with monkey bronchoalveolar lavage. KP16D3 revealed the immunohistochemical reactivity in the cytoplasm of some nonciliated bronchiolar epithelial cells and type II pneumocytes and thereby recognized specifically a protein with an apparent molecular weight of 60 kD with the use of Western blotting and immunoaffinity column chromatography followed by SDS-PAGE. Examination of 76 primary and 4 metastatic lung carcinomas in primary lung carcinoma KP16D3 showed immunohistochemical positivity only to mucin-nonproducing papillary adenocarcinoma (27/28) and bronchioloalveolar carcinoma (2/2), except for one case of large cell carcinoma. All other primary lung carcinomas such as squamous cell carcinoma, acinar adenocarcinoma, and small cell carcinoma had negative results. From these findings, KP16D3 seems to be an effective immunohistochemical marker of mucin-nonproducing papillary adenocarcinoma and bronchioloalveolar carcinoma of the lung and it appears to be useful to investigate both the histogenesis and functional expression of primary lung adenocarcinoma.     

Expression of occludin,a tight-junction-associated protein,in human lung carcinomas

Occludin is a tight-junction-associated transmembrane protein, and previous observations suggested that occludin might play a crucial role in the formation and maintenance of organized tubular structures. Based on these observations, we explored the possible role of occludin immunostaining in the diagnosis of lung carcinomas. A total of 68 lung carcinomas and surrounding normal lung tissues were studied. A formalin-fixed, paraffin-embedded section from each tumor was stained with a new anti-occludin monoclonal antibody raised in our laboratory. In normal lung tissues, the anti-occludin antibody strongly stained the apicoluminal borders of the bronchial/bronchiolar epithelia and bronchial glands as a dot or short line. The antibody also stained the intercellular borders of alveolar epithelia. In cancer cells that faced lumina of all adenocarcinomas, regardless of grade, including bronchioloalveolar carcinomas, occludin showed an expression pattern identical to that of the normal bronchial and alveolar epithelia. Occludin reactivity was not noted in any cases of squamous cell carcinoma, large cell carcinoma, small cell carcinoma, or large cell neuroendocrine carcinoma. The results of the present study suggest that occludin can serve as an immunohistochemical indicator of the true glandular differentiation that forms tubulo-papillary structures in human lung carcinoma tissues.     

Altered expression of adhesion molecules and epithelial-mesenchymal transition in silica-induced rat lung carcinogenesis

Loss of the epithelial phenotype and disruption of adhesion molecules is a hallmark in the epithelial-mesenchymal transition (EMT) reported in several types of cancer. Most of the studies about the relevance of adhesion and junction molecules in lung cancer have been performed using established tumors or in vitro models. The sequential molecular events leading to EMT during lung cancer progression are still not well understood. We have used a rat model for multistep lung carcinogenesis to study the status of adherens and tight junction proteins and mesenchymal markers during EMT. After silica-induced chronic inflammation, rats sequentially develop epithelial hyperplasia, preneoplastic lesions, and tumors such as adenocarcinomas and squamous cell carcinomas. In comparison with normal and hyperplastic bronchiolar epithelium and with hyperplastic alveolar type II cells, the expression levels of E-cadherin, alpha-catenin and beta-catenin were significantly reduced in adenomatoid preneoplastic lesions and in late tumors. The loss of E-cadherin in tumors was associated with its promoter hypermethylation. alpha- and beta-catenin dysregulation lead to cytoplasmic accumulation in some carcinomas. No nuclear beta-catenin localization was found at any stage of any preneoplastic or neoplastic lesion. Zonula occludens protein-1 was markedly decreased in 66% of adenocarcinomas and in 100% squamous cell carcinomas. The mesenchymal-associated proteins N-cadherin and vimentin were analyzed as markers for EMT. N-cadherin was de novo expressed in 32% of adenocarcinomas and 33% of squamous cell carcinomas. Vimentin-positive tumor cells were found in 35% of adenocarcinomas and 88% of squamous cell carcinomas. Mesenchymal markers were absent in precursor lesions, both hyperplastic and adenomatoid. The present results show that silica-induced rat lung carcinogenesis is a good model to study EMT in vivo, and also provide in vivo evidence suggesting that the changes in cell-cell adhesion molecules are an early event in lung carcinogenesis, while EMT occurs at a later stage.     

Expression and localization of thrombomodulin in preneoplastic bronchial lesions and in lung cancer

Thrombomodulin (TM) is an endothelial surface glycoprotein that acts as a natural anticoagulant. It inhibits thrombin and accelerates the activation of the anticoagulant protein C. TM has been detected in dermal keratinocytes, where it is associated with terminal differentiation. It can also be detected in various types of squamous malignant neoplasms and in malignancies of endothelial and mesothelial origin, such as Kaposi's sarcoma or malignant mesothelioma, but is absent in pulmonary adenocarcinomas (AC). Seventy-two lung tumour specimens [33 squamous cell carcinomas (SQCC), 23 AC, 1 large cell carcinoma, 8 small cell lung cancers (SCLC) and 7 multidifferentiated tumours (MT)] were analysed immunohistochemically by staining with an anti-TM antibody in order to assess TM expression. All of the SQCC stained positively for TM. In contrast, only 9 AC and 4 MT and none of the SCLC showed positive anti-TM staining. Seven hyperplastic bronchial epithelial specimens and eight preneoplastic bronchial lesions (five cases of moderate dysplasia, two cases of severe dysplasia and one case of carcinoma in situ) were used as controls.Normal or hyperplastic areas of bronchial epithelium revealed no positive reaction. However, a distinct positive anti-TM staining pattern related to the degree of keratiniziation of dysplastic lesions was seen. The present results suggest that anti-TM immunostaining is a useful marker for squamous cell carcinoma in the differential diagnosis of pulmonary carcinoma, also indicating keratinocyte differentiation in dysplastic bronchial epithelium.     

OV-TL 12/30 (keratin 7 antibody) is a marker of glandular differentiation in lung cancer

The immunoreactivity of OV-TL 12/30, a monoclonal antibody to keratin 7 was investigated on paraffin-embedded human lung cancer tissues of 61 patients. A modified AEC-immunoperoxidase method with pepsin pre-digestion was used. In normal lung tissue keratin 7 was found in bronchial and bronchiolar epithelium, pneumocytes and compound glands. Squamous metaplasia of the bronchial tree was negative. All 24 squamous cell carcinomas were negative irrespective of grade of differentiation. All differentiation grades of 20 adenocarcinomas including bronchioalveolar carcinomas were positive. Since six large cell anaplastic carcinomas did not react with keratin 7 antibody these tumours are considered to be of squamous cell rather than adenocarcinomatous origin. Small cell anaplastic carcinomas were negative in 10 of 11 cases. Our study demonstrates that this keratin 7 antibody is useful in differentiating between squamous cell carcinoma and adenocarcinoma of the lung and it may be particularly useful in making the correct diagnosis in small lung biopsy specimens.