Effects of E-cadherin transfection on gene expression of a gallbladder carcinoma cell line: repression of MTS1/S100A4 gene expression

E-cadherin is important in cell-to-cell adhesion and controls cell polarity and tissue morphology. Loss of E-cadherin expression occurs in various human tumors and is the first step in cancer invasion and metastasis. We demonstrate that the exogenous expression of E-cadherin transfected into G-415 GB cells not only increases cell-to-cell adhesion but also reduces in vitro cell proliferation, motility and invasion. Our aim was to determine what genes are most affected by the exogenous expression of E-cadherin in GB cancer cells. We analyzed gene expression pertaining to cell proliferation, motility and invasion. Conventional RT-PCR was performed for these genes; quantitative RT-PCR was carried out on genes exhibiting altered expression. Conventional RT-PCR revealed that E-cadherin transfection suppressed expression of mts1 mRNA and increased that of c-myc and MT1-MMP. In quantitative RT-PCR analysis, levels of c-myc and MT1-MMP mRNA were elevated by to 2.56- and 2.22-fold, respectively, in the E-cadherin transfectant, whereas mts-1 was 7.14-fold suppressed compared to parental cells. These results indicated that expression of mts1 mRNA was most affected by E-cadherin transfection. Immunocytochemical analysis of transfectant and parental cells demonstrated an inverse correlation in E-cadherin and mts1 expression. Immunohistochemical analysis of 37 GB cancer specimens confirmed this observation in vivo. Loss of E-cadherin expression followed by expression of the mts1 gene may be an important event for increasing cell proliferation, motility and invasion activity in the progression of GB cancer.

Sinus histiocytosis with massive lymphadenopathy and Langerhans cell histiocytosis express the cellular adhesion molecule CD31

Context.-We investigated expression of the adhesion molecule CD31 in sinus histiocytosis with massive lymphadenopathy (SHML) and Langerhans cell histiocytosis (LCH) because (1) SHML and LCH cells express a variety of cellular adhesion molecules and (2) SHML has been characterized as a reactive histiocytic proliferation, and tissue macrophages (histiocytes) are known to express CD31. Objective.-The purpose of this study was to determine whether SHML and LCH cells express CD31 and whether dual staining with CD31 and S100 facilitates diagnosis of these disease states. Methods.-Formalin-fixed, paraffin-embedded archival tissues were immunohistochemically stained via the labeled streptavidin-biotin method using antibodies against CD31 and S100 protein after heat-induced epitope retrieval. Archival tissues included SHML (n = 2), LCH (n = 10), malignant melanoma (n = 5), sinus hyperplasia (n = 4), granulomas (n = 4), granular cell tumor (n = 6), and normal skin (n = 4). Results.-Normal Langerhans cells in the epidermis were CD31(-)/S100(+); neoplastic Langerhans cells in LCH were CD31(+)/S100(+). Histiocytes in granulomas and in sinus hyperplasia were CD31(+)/S100(-); abnormal histiocytes in SHML were CD31(+)/S100(+). S100(+) tumors (malignant melanoma and granular cell tumor) were CD31(-). Conclusions.-The spectrum of cell types that express CD31 is expanded to include SHML and LCH. We speculate that up-regulation of CD31 in neoplastic Langerhans cells contributes to the migratory capability of LCH cells. CD31 may be a useful nonlysosomal marker of macrophages and their neoplastic counterparts (true histiocytic sarcomas). An immunohistochemical staining panel that includes CD31 and S100 facilitates the diagnosis of SHML and LCH.

Calcyclin (S100A6) regulates pulmonary fibroblast proliferation, morphology, and cytoskeletal organization in vitro

Calcyclin (S100A6) is a member of the S100A family of calcium binding proteins. While the precise function of calcyclin is unknown, calcyclin expression is associated with cell proliferation and calcyclin is expressed in several types of cancer phenotypes. In the present study, the functional role of calcyclin was further elucidated in pulmonary fibroblasts. Antisense S100A6 RNA expression inhibited serum and mechanical strain-induced fibroblast proliferation. This attenuated proliferative response was accompanied by a flattened, spread cell morphology, and disruption of tropomyosin labeled microfilaments. Changes in cytoskeletal organization did not correspond with a decrease in tropomyosin levels. These observations suggest a role for calcyclin in modulating calcium dependent signaling events that regulate progression through the cell cycle. J. Cell. Biochem. 88: 848-854, 2003.

Hepatosplenic alpha beta T-cell lymphoma: a report of an S100-positive case

Hepatosplenic T-cell lymphoma is an uncommon neoplasm characterized by a lymphoid infiltrate within the sinusoids of the liver, spleen, and bone marrow, without significant nodal involvement. The majority of cases express the gammadelta T-cell receptor and are associated with an isochromosome 7q cytogenetic abnormality. Recently, a small number of cases have been reported that express the alphabeta T-cell receptor. Here, we report our findings of a case of an S100-positive hepatosplenic alphabeta T-cell lymphoma in a 20-year-old woman who presented with pancytopenia and hepatosplenomegaly. The case adds to the growing literature of hepatosplenic alphabeta T-cell lymphomas.

Connexin immunoreactivity in glial cells of the rat retina

The rat retina contains two types of macroglial cells, Müller cells, radial glial cells that are the principal macroglial cells of vertebrate retinas, and astrocytes associated with the surface vasculature. In addition to the often-described gap-junctional coupling between astrocytes, coupling also occurs between astrocytes and Müller cells. Immunohistochemistry and confocal microscopy were used to identify connexins in the retinas of pigmented rats. Several antibodies directed against connexin43 stained astrocytes, identified using antibodies directed against glial fibrillary acidic protein (GFAP). In addition, two connexin43 antibodies stained Müller cells, identified with antibodies directed against S100 or glutamine synthetase. Connexin30-immunoreactive puncta were confined to the vitreal surface of the retina and colocalized with GFAP-immunoreactive astrocyte processes. Connexin45 immunoreactivity was associated with both astrocytes and Müller cells. We conclude that retinal glial cells express multiple connexins, and the patterns of immunostaining that we observe in this study are consistent with the expression of connexins30, -43, and possibly -45 by astrocytes and the expression of connexins43 and -45 by Müller cells. As gap-junction channels may be formed by both homotypic and heterotypic hemichannels, and the hemichannels may themselves be homomeric or heteromeric, there exists a multitude of possible gap-junction channels that could underlie the homotypic coupling between retinal astrocytes and the heterotypic coupling between astrocytes and Müller cells.

Gastric cancers overexpress S100A calcium-binding proteins

Serial analysis of gene expression provides quantitative and comprehensive expression profiling in a given cell population. In our efforts to define the genes overexpressed in carcinoma of the stomach, we performed serial analysis of gene expression analyses on dissected neoplastic and normal gastric epithelia. We identified 91,334 expressed tags, including 26,633 that were unique. The 20 most up-regulated genes (P < 0.01) in gastric cancer (GC) compared with normal gastric epithelia included several keratins that are specific for epithelial cells such as keratin 6A, 13, and 17. Interestingly, five calcium-binding proteins (S100A2, S100A7, S100A8, S100A9, and S100A10) were overexpressed. Quantitative real-time PCR on primary GC samples demonstrated overexpression of S100A2 in 18 of 20 tumors (90%). The other calcium-binding proteins were overexpressed in 25-45% of the GC samples that we studied. Our results indicate that S100A proteins may be important for gastric tumorigenesis. Additional investigations are required to elucidate the biological role of calcium-binding proteins in cancer.

[Expression of human S100 protein and preparation of specific antiserum for S100 and establishment of a quantitative measurement for S100 protein in CSF specimens of patients with Creutzfeldt Jakob disease]

OBJECTIVE

To establish a method that can quantitatively detect S100 protein in CSF, and evaluate the possibility in diagnosis of Creutzfeldt-Jakob disease (CJD).

METHODS

S100 gene was amplified by PCR from a commercially supplied human brain cDNA library. After verified by sequence analysis, the full length of S100 DNA was subcloned into a (GST) expression vector Pgex-2T, and the expression of GST-S100 fusion protein was induced. Rabbits were immunized with the purified GST-S100 fusion protein, and the antiserum raised against S100 protein was collected and further evaluated. Using biotin-avidin system, a sandwich ELISA was established for quantitatively determining S100 protein, and further, used in screening for S100 protein in CSF and serum samples.

RESULTS

SDS-PAGE assays yielded a roughly 35,000 GST-S100 fusion protein. Using the established method, three CSF samples from probable CJD patients (14-3-3 protein positive in CSF) showed higher concentration of S100 protein (higher than 2.900 microg/L), whereas other CSF samples collected from patients with other CNS diseases showed lower concentration of S100 (less than 0.180 microg/L).Moreover, the sera S100 proteins from all the collected samples showed distinct individual difference.

CONCLUSIONS

The established method can be used in determining S100 protein in CSF quantitatively. The feasibility and significance of S100 protein in CSF for diagnosis of CJD should be further considered with more CSF samples.

Expression of S100A4, E-cadherin, alpha- and beta-catenin in breast cancer biopsies

In 66 breast cancer biopsies, the expression of the Ca(2+)-binding protein S100A4, E-cadherin, alpha- and beta-catenin was examined by immunohistochemistry, and the results were related to clinical and pathological parameters. High levels of S100A4 were found to significantly correlate with histological grade (P=0.030) and loss of oestrogen receptor (P=0.046), but not to the time interval between surgery and development of distant metastasis (P=0.51) or to patient survival (P=0.89). Loss of E-cadherin expression, associated with altered cell-cell adhesion, showed a highly significant association to overall survival (P=0.020) and metastasis-free period (P=0.0052). In multivariate analysis, only lymph node involvement was a more significant predictor of patient demise. No association was found between expression of S100A4 and any single member of the cadherin-catenin complex, but a trend (P=0.053) towards reduced expression of one or several of these proteins and S100A4 immunoreactivity was observed. In conclusion, although our results suggest an association between S100A4 expression and an aggressive tumour phenotype, no relationship to overall survival was found. Deregulation of E-cadherin expression, however, was of high prognostic significance.

Extracellular S100A4 stimulates the migration rate of astrocytic tumor cells by modifying the organization of their actin cytoskeleton

In previous studies, we have shown that numbers of S100 calcium-binding proteins (including S100A4) are expressed differentially in astrocytic tumors according to their levels of malignancy. S100A4 is involved in tumor progression, cell migration and metastasis. This protein is able to play extracellular roles such as neuritogenic and angiogenic activities. The present study aims to investigate the possible role played by extracellular S100A4 in the in vitro migration of astrocytic tumor cells. The speed and rate of migration of living cells were measured using computer-assisted videomicroscopy. In parallel, we also analyzed the effects of extracellular S100A4 on the organization of the actin cytoskeleton and the expression of a number of its molecular regulators. These included small Rho-GTPases (RhoA, Rac1 and Cdc42) and some of their direct effectors (mDia and N-WASP), and also actin-binding proteins such as profilin and alpha-actinin. Our data demonstrate the influence of S100A4 on astrocytic tumor cells with respect to these different aspects. Indeed, we show that extracellular S100A4 treatments decrease both the amount of polymerized F-actin and the levels of expression of RhoA, mDia and profilin. While a decrease in the Cdc42 and N-WASP expression was also observed, the Rac1 expression remained unchanged. All these activities, which result in the stimulation of cell motility, contribute to the understanding of the extracellular role of S100A4.

Expression of collagen type II, S100B, S100A2 and osteocalcin in chondroblastoma and chondromyxoid fibroma

Chondroblastoma and chondromyxoid fibroma (CMF) has been investigated in numerous histological studies, but its biological nature and histogenetic origin are still a matter of debate. We evaluated the expression of type II collagen, S100A2, S100B, and osteocalcin to study the matrix biochemistry and phenotype of the neoplastic cells in these tumors. Immunohistochemically, the expression of type II collagen was diffuse in 15 cases (75%) among total 20 chondroblastomas and 12 (85.7%) among total 14 CMFs. The expression of S100B was also diffuse in all cases (100%) of chondroblastomas and 12 cases (85.7%) of CMFs. We were able to obtain the expression of S100A2, focally. The expression of osteocalcin was focally noted in 18 cases (90%) of chondroblastomas and 8 cases (57.1%) of CMFs. In conclusion, our data support that chondroblastoma and CMF are a distinct tumor entity with the basic expression of chondroid markers. But these tumors also show histologic diversity with focal co-expression of osteoid markers.

Calgranulins S100A8 and S100A9 are negatively regulated by glucocorticoids in a c-Fos-dependent manner and overexpressed throughout skin carcinogenesis

The two calgranulins S100A8 and S100A9 were found to be differentially expressed at sites of acute and chronic inflammation. Here we have employed the phorbol ester-induced multistage skin carcinogenesis protocol in mice to determine the expression of both genes in inflamed skin and in skin tumors. We show that expression is coordinately induced by the phorbol ester TPA in epithelial cells as well as infiltrating leukocytes. By comparing S100A8 and S100A9 mRNA levels in wild type and c-Fos deficient mice (c-fos(-/-)) we found that expression is negatively regulated by c-Fos/AP-1. Glucocorticoids, which exhibit potent anti-inflammatory and anti-tumor promoting activities repressed TPA-mediated S100A8 and S100A9 induction in wild type, but not in c-fos(-/-) mice, thus identifying both genes as the first examples of AP-1 target genes whose repression of TPA-induced transcription by glucocorticoids depends on c-Fos. Finally, we show that enhanced expression is not restricted to the initial TPA-induced inflammatory response but is observed at all stages of skin carcinogenesis. These data identify S100A8 and S100A9 as novel, tumor-associated genes and may point to an as yet unrecognized function of both genes in the development of epithelial skin tumors.

Astrocytic activation and delayed infarct expansion after permanent focal ischemia in rats. Part I: enhanced astrocytic synthesis of s-100beta in the periinfarct area precedes delayed infarct expansion

An astrocytic protein S-100beta enhances the expression of inducible nitric oxide synthase in cultured astrocytes at micromolar concentrations, leading to nitric oxide-mediated death of cocultured neurons. The present study examined whether S-100beta production by reactive astrocytes accumulating within the periinfarct area was related to delayed expansion of infarct volume after permanent middle cerebral artery occlusion in the rat. After rapid increases during the initial 24 hours, the increase of infarct volume then decelerated while maintaining the increasing tendency until 168 hours in this model, attaining a significant difference compared with that at 24 hours. In the periinfarct area, the number of reactive astrocytes expressing both S-100 and glial fibrillary acidic protein, the tissue level of S-100beta as measured by the sandwich enzyme-linked immunosolvent assay method using anti-S-100beta monoclonal antibody, and the number of terminal deoxynucleotidyl transferase-mediated 2;-deoxyuridine 5;-triphosphate-biotin nick end labeling-positive cells were significantly increased preceding the delayed expansion of infarct volume. The CSF concentration of S-100beta showed a biphasic increase, presumably reflecting the immediate release from astrocytes within the ischemic core and the subsequent production in reactive astrocytes within the periinfarct area. These results show for the first time that the enhanced synthesis of S-100beta by reactive astrocytes participates in the inflammatory responses within the periinfarct area, which may be related to the occurrence of delayed infarct expansion as a major component of the cytokine network.

Prognostic significance of S100A4 expression in gallbladder cancer

The calcium-binding protein S100A4 has been characterized as a metastasis-inducing molecule, and regulates cell motility and invasiveness of cancer cells. In order to clarify the significance of the expression of S100A4 as a prognostic factor in gallbladder cancer, S100A4 expression in resected gallbladder cancers were examined using an immunohistochemical staining technique. The relationship between S100A4 expression and clinicopathological factors including prognosis were evaluated. Twenty-five of 60 cases (42%) demonstrated positive staining for S100A4. There was no statistically significant association between S100A4 and histological grade, T, N, M factor, presence of stone, or stage. Kaplan-Meier method showed the 5-year survival rate of the group staining positive for S100A4 (31.5%) to be statistically poorer than that of the group staining negative for S100A4 (78.2%). Also in T2 cases, the 5-year survival rate of the group staining positive for S100A4 (57.1%) was statistically poorer than that of the group staining negative for S100A4 (83.3%). On univariate analysis, positive staining for S100A4 was a significant prognostic factor, and the hazard ratio was 4.05. On multivariate analysis, positive staining for S100A4 is also a significant predictor of prognosis second to T factor. These results indicate that positive staining for S100A4 is useful in assessing the prognosis of patients with gallbladder cancer as well as TNM factors.

Immunohistochemical study of the expression of S-100 protein, epithelial membrane antigen, cytokeratin and carcinoembryonic antigen in thyroid lesions

The diagnosis of papillary carcinoma of the thyroid is based on the two morphological features that best characterize this tumor, the papillae and the nuclear changes. However, both the architectural and cytological hallmarks may be encountered in other conditions such as multinodular goiter, Grave's disease, thyroiditis and hyperplastic areas of follicular neoplasms and thus produce problems in the histopathological interpretation. The distinction of these lesions from papillary carcinoma has important implications for clinical management. Thus the availability of supportive diagnostic evidence would be helpful. In the present study we compared the immunoreactivity for S-100 protein, epithelial membrane antigen (EMA), cytokeratin (Ck) and carcynoembryonic antigen (CEA) in different thyroid pathologies. We conclude that the strong expression of S-100 protein, in combination with EMA expression, is of value in identifying papillary neoplasia and distinguishing it from papillary hyperplasia.

Expression and prognostic significance of S100A2 protein in squamous cell carcinoma of the esophagus

The purpose of this study was to evaluate the expression of S100A2 Ca2+-binding protein and its prognostic significance in the management of squamous cell carcinoma of the esophagus. Changes in cytosolic Ca2+ concentration control a wide range of cellular responses including cellular apoptosis. Intracellular S100 Ca2+-binding proteins are key molecules in transducing Ca2+ signaling. Among these, S100A2 has recently attracted major interest due to its stable expression in normal epithelia and down-regulation in some tumors. As a candidate tumor suppressor, expression of S100A2 has been proposed as a valuable prognostic marker in different tumors. We examined the clinical significance of S100A2 expression in 116 resected specimens of esophageal squamous cell carcinomas (ESCC) using immunohistochemistry. S100A2 was positive in 49 cases (42.2%) and its expression was significantly higher in large (p=0.01) and well differentiated tumors (p=0.013). Lymph node-positive tumors had a lower expression of S100A2 protein in comparison to the corresponding lymph node negative equivalents in each of the T stages, but the difference was statistically significant (p=0.041) only for the T1b tumors. S100A2 status became an independent predictor of patient survival (p=0.026) in lymph node-negative cases but not in node-positive cases. Evaluation of S100A2 protein expression may play an important role in the management of ESCC. The node-negative ESCC patients without S100A2 expression might be a high-risk group with poor survival and will need further attention to design appropriate adjuvant therapy.

Utility of immunostaining for S-100 protein subunits in gonadal sex cord-stromal tumors, with emphasis on the large-cell calcifying Sertoli cell tumor of the testis

This study concerns the immunohistochemical localization of S-100 alpha, S-100 beta, and whole brain S-100 (wbS-100) in testicular large-cell calcifying Sertoli cell tumor (LCCSCT). We examined 8 LCCSCTs (7 benign and 1 malignant), 6 Sertoli cell tumors not otherwise specified (SCTs-NOS), 6 Leydig cell tumors (LCTs), 5 ovarian Sertoli-Leydig cell tumors (SLCTs), and 7 gonadoblastomas (GBLs). The 8 LCCSCTs showed immunoreactivity for S-100 alpha, S-100 beta, and wbS-100. Five of the 6 LCTs and the Leydig cell components in the ovarian SLCTs stained positively for S-100 alpha and wbS-100 but were negative for S-100 beta. SCTs-NOS and the Sertoli cell components in the SLCTs occasionally showed focal and weak/moderate positivity for S-100 alpha, S-100 beta, and wbS-100. Sex cord cells of the GBLs were positive for S-100 beta and wbS-100 and negative for S-100 alpha. Germ cell elements of the GBLs were negative for S-100 alpha, S-100 beta, and wbS-100. In nonneoplastic testicular parenchyma adjacent to the above-mentioned tumors, there was S-100 alpha reactivity in Leydig cells, rete testis, and a few Sertoli cells. S-100 beta reactivity was seen in a few Sertoli cells, Schwann cells, and some endothelial cells. WbS-100 reactivity was present in Leydig cells, a few Sertoli cells, rete testis, Schwann cells, and some endothelial cells. The results indicate that S-100 alpha and S-100 beta can potentially be used as immunohistochemical markers for LCCSCT, especially when differentiating it from LCT, which may mimic LCCSCT on routine histopathology. Although the biological significance of both S-100 subunits expression in LCCSCT remains unknown, these notable calcium-binding proteins may be associated with the characteristic calcification in LCCSCT through regulation of calcium levels in the tumor cells.

Restricted expression of calcium-binding protein S100A5 in human kidney

Reverse transcription--polymerase chain reaction (RT-PCR) identified the expression of calcium-binding protein S100A5 in the noncancerous parts of resected samples from renal cell carcinoma (RCC) patients (n = 7) but not in the carcinoma lesions. Rabbit anti-S100A5 antibody immunohistochemically detected the antigen in the thick ascending limb of Henle, distal convoluted tubule, and collecting duct system. No apparent immunopositivity was observed in the glomerulus, proximal tubules, interstitial cells, or RCC cells. Thus, it was suggested that S100A5 protein plays an inherent functional role to the post-thick ascending limb of Henle portion in the nephron. Further, the carcinomas tested were originated probably not in the S100A5-positive distal epithelium but in the -negative epithelium of proximal tubules. Then, total RNA was extracted by phenol/chloroform from 1 ml urine of healthy volunteers, and S100A5 was amplified by RT-PCR from all samples (n = 12), indicating that the transcript of S100A5 is detectable even in the cells released into urine.

Cytologic features of clear cell sarcoma (malignant melanoma) of soft parts: a study of fine-needle aspirates and exfoliative specimens

We describe the cytologic features of clear cell sarcoma of soft tissue (CCS) in 11 fine-needle aspiration biopsy (FNAB) specimens and 6 exfoliative specimens from 11 patients. In 3 patients, FNAB was the initial method of tumor evaluation. In 6 of 11 cases, immunostaining with S-100 or HMB-45 was evaluated. Electron microscopic evaluation was performed in 1 case. Both the FNAB and exfoliative specimens varied in overall cellularity, although reproducible cytologic features were identified. A significant diagnostic pitfall, namely the potential of CCS to form microacinar structures mimicking adenocarcinoma, is described with particular reference to CCS metastatic to regional lymph nodes. A rare case of the granular cell variant of CCS is illustrated as well. Owing to the rarity of CCS, the diagnosis on cytologic smears is extremely difficult and is aided substantially by pertinent clinical data. The diagnosis can be made conclusively by

S-100 protein+ dendritic cells and CD34+ dendritic interstitial cells in thyroid lesions

Dendritic cells (DCs) are antigen-presenting cells and mature from precursor CD34+ stromal cells (dendritic interstitial cells [DICs]) or monocytes. The aim of the present study was to gain insight into the local immune response to various thyroid lesions. We investigated, immunohistochemically, the presence of S-100+ DCs and CD34+ DICs in 13 papillary carcinomas, 10 follicular carcinomas, 7 follicular adenomas, 1 Hurthle cell carcinoma, 1 Hurthle cell adenoma, 2 medullary carcinomas, 6 undifferentiated carcinomas, and 3 nodular goiters. Dense infiltrates of S-100+ DCs were noted in the majority of papillary carcinomas (mean: 66.4), while moderate infiltrates were observed in follicular adenomas (mean: 23.3), follicular carcinomas (mean: 23.5), and undifferentiated carcinomas (mean: 31.6). The remaining lesions showed slight infiltrates of scattered DCs. DICs were noted exclusively in neoplastic lesions, specifically at the periphery and within the tumor capsule. The increased number of DCs in papillary carcinomas is possibly correlated with their good prognosis. The specific distribution of DICs suggests a possible contribution to growth regulation of thyroid neoplasms.

Identification of dendritic cells in aortic atherosclerotic lesions in rats with diet-induced hypercholesterolaemia

We have previously identified dendritic cells (DCs) in the intima of human large arteries. These vascular DCs are common in atherosclerotic lesions but their immature forms are also present in normal arterial intima. Pathophysiological studies on vascular DCs are limited because they have only been studied in human specimens obtained at operation or post-mortem. The aim of the current study was to determine whether DCs participate in the development of atherosclerotic lesions in hypercholesterolemic rats. Male Wistar rats were divided into a control (n=13) and experimental cohort (n=48). The experimental animals were fed an atherogenic diet and 1% saline, while the controls were fed standard rat cubes and water. The aortas were obtained from both groups at 10, 20, and 30 weeks following commencement of the diet. An en face immunohistochemical technique, routine section immunohistochemistry, and transmission electron microscopy were used to detect the presence of DCs in the aortas. Examination of the aortas showed that S100+ cells with dendritic cell morphology were present in the aortic intima of hypercholesterolemic rats. The S100+ DCs displayed immunopositivity for OX-62 and MHC Class II antibodies. Within various types of atherosclerotic lesions, these cells were clustered throughout the intima but were especially prominent around arterial branch-points where they co-localized with various cell types, including T-cells and macrophages. Ultrastructural analysis confirmed the presence of cells with characteristics typical of DCs. These features included the presence of a well-developed tubulovesicular system, dendritic processes, and a lack of secondary lysosomes and phagosomes. This study establishes the presence of DCs in the aortic intima of rats with diet-induced atherosclerosis. The presence of DCs in this model of experimental atherogenesis could provide a new approach to investigating the function of DCs and may help clarify the immune-inflammatory mechanisms underlying atherosclerosis.

The Ca2+-binding S100A2 protein is differentially expressed in epithelial tissue of glandular or squamous origin

It has been previously shown that S100A2 is downregulated in tumor cells. The level of immunohistochemical S100A2 expression was therefore characterized in 424 normal and tumoral (benign and malignant) tissues of various origins, but mostly epithelial (with either glandular, squamous, respiratory or urothelial differentiation). We also investigated whether S100A2 could be co-localized with cytokeratin K14, an intermediate filament protein expressed in basal proliferative keratinocytes. Our data show that S100A2 has a low level of expression in non-epithelial tissue. In epithelial tissue S100A2 expression decreases remarkably in the tumors when compared to the normal specimens, and was correlated with the level of keratin K14. This decrease in S100A2 staining from normal to cancer cases is more pronounced in glandular than in squamous epithelial tissue. In addition, the patterns of S100A2 staining also differ between glandular and squamous tissue. These data suggest distinct functional roles for S100A2 in epithelial tissue of squamous or glandular origins.

Molecular characterization and tissue distribution of a novel member of the S100 family of EF-hand proteins

We have isolated from a human prostate cDNA library a cDNA encoding a novel member of the S100 family of EF-hand proteins. The encoded 99-amino acid protein, designated S100Z, is capable of interacting with another member of the family, S100P. S100Z cDNA was cloned into a bacterial expression system, and the S100Z protein was purified to homogeneity from bacterial lysates by a combination of hydrophobic column and gel-filtration chromatography. Direct amino acid sequencing of the 20 N-terminal amino acids confirmed that the sequence of the recombinant protein is identical to the sequence deduced from the cDNA. Low-resolution structural data have been obtained using circular dichroism and fluorescence spectroscopies, and equilibrium analytical centrifugation. These results show that S100Z is a dimeric, predominantly alpha-helical protein. Addition of calcium to a solution of S100Z changes the fluorescence intensity of the protein, indicating that S100Z is capable of binding calcium ions. Analysis of the calcium-binding isotherm indicates the existence of two calcium-binding sites with apparent affinities on the order of 5 x 10(6) and 10(2) M(-1). Binding of calcium results in conformational changes and exposure of hydrophobic surfaces on the protein. Using a PCR-based assay, we have detected differences in the expression level of S100Z mRNA in various tissues. The highest levels were found in spleen and leukocytes. S100Z gene expression appears to be deregulated in some tumor tissues, compared to expression in their normal counterparts.

Diminished expression of S100A2, a putative tumor suppressor, at early stage of human lung carcinogenesis

To identify and understand early events in lung carcinogenesis, we used a cDNA array to screen for genes that are expressed differentially in normal human bronchial epithelial (NHBE) cells and a tumorigenic cell line (1170-I) derived from immortalized HBE cells after exposure to cigarette smoke condensate in vivo. Among these genes, we have identified the S100A2 gene, which encodes a nuclear calcium-binding protein, as being down-regulated in the 1170-I cells. Because this gene has been implicated as a tumor suppressor in breast cancer, we examined its potential role as a tumor suppressor in lung carcinogenesis. Levels of S100A2 transcript and protein, which were high in NHBE cells, decreased by up to 50% in immortalized HBE cells (BEAS-2B and 1799) and to low to nearly undetectable levels in transformed (1198) and tumorigenic (1170-I) HBE cells. Furthermore, S100A2 mRNA and protein were undetectable in 8 and expressed at a reduced level in 3 of 11 non-small cell lung cancer (NSCLC) cell lines. Positive immunohistochemical staining of S100A2 was detected in the majority (75-83%) of normal and hyperplastic lung tissues, whereas it was detected in <10% of metaplastic lung tissues, squamous cell carcinoma, and adenocarcinoma. Treatment of 1170-I HBE and NSCLC cells with 5-aza-2'-deoxycytidine resulted in partial restoration of S100A2 expression in seven of eight cell lines. Indeed, CpG methylation was detected in the promoter region of the S100A2 gene. Our results suggest that S100A2 expression is suppressed early during lung carcinogenesis, possibly by hypermethylation of its promoter, and that its loss may be a contributing factor in lung cancer development or a biomarker of early changes in this process.

The role of activated astrocytes and of the neurotrophic cytokine S100B in the pathogenesis of Alzheimer's disease

Activated astrocytes, overexpressing the neurotrophic signaling molecule S100beta, are invariant components of the Abeta plaques of Alzheimer's disease. Even early, nonfibrillar amyloid deposits in Alzheimer's disease contain such astrocytes, and the numbers and degree of activation of these wax and wane with the subsequent neuritic pathology of plaque evolution. Astrocytic overexpression of S100B in the neuritic plaques of Alzheimer's disease correlates with the degree of neuritic pathology in Abeta plaques in this disease, suggesting a pathogenic role for S100B's neurotrophic properties in the evolution of these lesions. Astrocytic overexpression of S100B, in turn, is promoted by high levels of interleukin-1 (IL-1), originating from activated microglia that are also constant components of Abeta plaques in Alzheimer's disease. Similar patterns of astrocyte activation, S100B overexpression, microglial activation, and IL-1 overexpression are seen in conditions that confer risk for Alzheimer's disease (aging, head trauma, Down's syndrome), in conditions that predispose to accelerated appearance of Alzheimer-like neuropathologic changes (chronic epilepsy, HIV infection), and in animal models of Alzheimer's disease. These cells and molecules are an important components of a cytokine cycle of molecular and cellular cascades that may drive disease progression in Alzheimer's disease.