Increased levels of type VIII collagen in human brain tumours compared to normal brain tissue and non-neoplastic cerebral disorders

COL8A1 Predicts the Clinical Prognosis of Gastric Cancer and Is Related to Epithelial-Mesenchymal Transition

Background

Gastric cancer (GC) is the fifth most common malignant tumor and the third leading cause of cancer-related deaths. Because GC has the characteristics of high heterogeneity, unclear mechanism, limited treatment methods, and low five-year survival rate, it is necessary to find the prognostic biomarkers of GC and explore the mechanism of GC.

Methods

We first identified differentially expressed genes (DEGs) between gastric cancer and normal gastric cells through expression analysis. A protein-protein interaction (PPI) network was constructed to find tightly connected modules. We performed survival analysis on the DEGs in the modules to identify genes with prognostic significance. Gene set enrichment analysis (GSEA) was used to identify gene enrichment pathways. Finally, we used our own collected clinical samples of 119 gastric adenocarcinoma (STAD) tissues and 40 normal gastric tissues to perform immunohistochemical (IHC) staining to verify the differential expression of COL8A1 in STAD tissues and normal gastric tissues and its correlation with epithelial-mesenchymal transition- (EMT-) related factors.

Results

We identified 356 DEGs through differential expression analysis. Through PPI analysis and survival analysis, we determined that the collagen type VII alpha-1 chain (COL8A1) gene has prognostic significance. GSEA analysis showed that COL8A1 was significantly enriched in the EMT. IHC results showed that COL8A1 was upregulated in STAD tissues and could be used as an independent prognostic factor and was related to EMT.

Conclusion

This study shows that COL8A1 is related to the prognosis of GC patients and might affect the progress of GC through the EMT pathway. Therefore, COL8A1 may be a biomarker for predicting the prognosis of GC.

The role of network-forming collagens in cancer progression

Collagens are the main components of extracellular matrix in the tumor microenvironment. Both fibrillar and nonfibrillar collagens are involved in tumor progression. The nonfibrillar network-forming collagens such as type IV and type VIII collagens are frequently overexpressed in various types of human cancers, which promotes tumor cell proliferation, adhesion, invasion, metastasis and angiogenesis. Studies on the roles of these collagens have shed light on the mechanisms underpinning the effects of this protein family. Future research has to explicit the role of network-forming collagens with respect to cancer progression and treatment. Herein, we review the regulation of network-forming collagens expression in cancer; the roles of network-forming collagens in tumor invasion, metastasis and angiogenesis; and the clinical significance of network-forming collagens expression in cancer patients. This article is protected by copyright. All rights reserved.

Strategies to better treat glioblastoma: antiangiogenic agents and endothelial cell targeting agents

Glioblastoma multiforme (GBM) is the most prevalent and aggressive form of glioma, with poor prognosis and high mortality rates. As GBM is a highly vascularized cancer, antiangiogenic therapies to halt or minimize the rate of tumor growth are critical to improving treatment. In this review, antiangiogenic therapies, including small-molecule drugs, nucleic acids and proteins and peptides, are discussed. The authors further explore biomaterials that have been utilized to increase the bioavailability and bioactivity of antiangiogenic factors for better antitumor responses in GBM. Finally, the authors summarize the current status of biomaterial-based targeting moieties that target endothelial cells in GBM to more efficiently deliver therapeutics to these cells and avoid off-target cell or organ side effects.

Fabrication of Perfusable Vascular Channels and Capillaries in 3D Liver-like Tissue

Although various production methods for 3D vascularised tissues have been developed, constructing capillary-like structures branching from perfusable large channels remains difficult. This study describes a method to fabricate tube-shaped 3D liver-like tissue (tubular liver tissue) with large channels and capillary-like structures using a perfusion device. The perfusion device functions as an interface between the tissue and an external pump, as it has connectors equipped with anchors that hold the tissue in response to its shrinkage, which is accompanied by the self-organisation of capillary-like structures. Histological analysis revealed that perfusion via the large channel induced capillary formation around the channel and maintained proper tissue functions. Accompanied by structural examinations, global gene expression analysis supported this finding; specifically, genes involved in angiogenesis were enriched in the perfused condition. Furthermore, we confirmed the penetrability of the capillary-like structures by infusing India ink, as well as substance exchange by measuring the amounts of secreted albumin. These lines of evidence indicate that our method can be used to construct 3D tissues, which is useful for fields of in vitro tissue regeneration for drug development and regenerative medicine.

A transcriptional co-expression network-based approach to identify prognostic biomarkers in gastric carcinoma

Background

Gastric carcinoma is a very diverse disease. The progression of gastric carcinoma is influenced by complicated gene networks. This study aims to investigate the actual and potential prognostic biomarkers related to survival in gastric carcinoma patients to further our understanding of tumor biology.

Methods

A weighted gene co-expression network analysis was performed with a transcriptome dataset to identify networks and hub genes relevant to gastric carcinoma prognosis. Data was obtained from 300 primary gastric carcinomas (GSE62254). A validation dataset (GSE34942 and GSE15459) and TCGA dataset confirmed the results. Gene ontology, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and gene set enrichment analysis (GSEA) were performed to identify the clusters responsible for the biological processes and pathways of this disease.

Results

A brown transcriptional module enriched in the organizational process of the extracellular matrix was significantly correlated with overall survival (HR = 1.586, p = 0.005, 95% CI [1.149–2.189]) and disease-free survival (HR = 1.544, p = 0.008, 95% CI [1.119–2.131]). These observations were confirmed in the validation dataset (HR = 1.664, p = 0.006, 95% CI [1.155–2.398] in overall survival). Ten hub genes were identified and confirmed in the validation dataset from this brown module; five key biomarkers (COL8A1, FRMD6, TIMP2, CNRIP1 and GPR124 (ADGRA2)) were identified for further research in microsatellite instability (MSI) and epithelial-tomesenchymal transition (MSS/EMT) gastric carcinoma molecular subtypes. A high expression of these genes indicated a poor prognosis.

Conclusion

A transcriptional co-expression network-based approach was used to identify prognostic biomarkers in gastric carcinoma. This method may have potential for use in personalized therapies, however, large-scale randomized controlled clinical trials and replication experiments are needed before these key biomarkers can be applied clinically.

Identification of Potential Key Genes Associated With the Pathogenesis and Prognosis of Gastric Cancer Based on Integrated Bioinformatics Analysis

Background and Objective: Despite striking advances in multimodality management, gastric cancer (GC) remains the third cause of cancer mortality globally and identifying novel diagnostic and prognostic biomarkers is urgently demanded. The study aimed to identify potential key genes associated with the pathogenesis and prognosis of GC.

Methods: Differentially expressed genes between GC and normal gastric tissue samples were screened by an integrated analysis of multiple gene expression profile datasets. Key genes related to the pathogenesis and prognosis of GC were identified by employing protein–protein interaction network and Cox proportional hazards model analyses.

Results: We identified nine hub genes (TOP2A, COL1A1, COL1A2, NDC80, COL3A1, CDKN3, CEP55, TPX2, and TIMP1) which might be tightly correlated with the pathogenesis of GC. A prognostic gene signature consisted of CST2, AADAC, SERPINE1, COL8A1, SMPD3, ASPN, ITGBL1, MAP7D2, and PLEKHS1 was constructed with a good performance in predicting overall survivals.

Conclusion: The findings of this study would provide some directive significance for further investigating the diagnostic and prognostic biomarkers to facilitate the molecular targeting therapy of GC.

Co-expression Network Analysis Identified COL8A1 Is Associated with the Progression and Prognosis in Human Colon Adenocarcinoma

BACKGROUNDS AND AIMS

Human colon adenocarcinoma is one of the major causes of tumor-induced death worldwide. A complicated gene interconnection network significantly regulates its progression and prognosis. The aim of our study was to find hub genes associated with the progression and prognosis of colon adenocarcinoma and to illustrate the underlying mechanisms.

METHODS

A weighted gene co-expression network analysis was performed in our study to identify significant gene modules and hub genes associated with the TNM stage of colon adenocarcinoma (n = 441).

RESULTS

In the turquoise module of interest, 23 hub genes were initially selected, and 10 of them were identified as "real" hub genes with high connectivity in the protein-protein interaction network. In the terms of validation, COL8A1 had the highest correlation with clinical traits among all of the hub genes. Data obtained from the Oncomine and GEPIA databases showed a higher expression of COL8A1 in colon adenocarcinoma tissues compared with normal colon tissues. Kaplan-Meier survival curves showed that higher expression of COL8A1 resulted in a shorter overall survival time and disease-free survival time. Univariate and multivariate Cox proportional hazards analyses indicated that the COL8A1 expression was an independent prognostic factor for survival in colon adenocarcinoma patients. Finally, gene set enrichment analysis indicated that the gene sets associated with focal adhesion were significantly enriched in colon adenocarcinoma samples with COL8A1 highly expressed.

CONCLUSIONS

COL8A1 was identified and proved to be correlated with the progression and prognosis of human colon adenocarcinoma, probably through regulating focal adhesion-related pathways.

Enhanced expression of Vastatin inhibits angiogenesis and prolongs survival in murine orthotopic glioblastoma model

Background

Antiangiogenic therapies are considered promising for the treatment of glioblastoma (GB). The non-collagenous C-terminal globular NC1 domain of type VIII collagen a1 chain, Vastatin, is an endogenous antiangiogenic polypeptide. Sustained enhanced expression of Vastatin was shown to inhibit tumour growth and metastasis in murine hepatocellular carcinoma models. In this study, we further explored the efficacy of Vastatin in the treatment of GB xenografts.

Method

Treatment of Vastatin was carried out using a nanopolymer gene vector PEI600-CyD-Folate (H1). Antiangiogenic effect of Vastatin was tested in vitro by using co-culture system and conditioned medium. An orthotopic GB murine model was established to examine the in vivo therapeutic effect of Vastatin alone treatment and its combination with temozolomide.

Results

Vastatin gene transfection mediated by H1 could target tumour cells specifically and suppress the proliferation of microvessel endothelial cells (MECs) through a paracrine inhibition manner. Enhancing Vastatin expression by intracerebral injection of H1-Vastatin significantly prolonged animal survival from 48 to 75 days in GB murine model, which was comparable to the effect of Endostatin, the most studied endogenous antiangiogenic polypeptide. The diminished presence of CD34 positive cells in the GB xenografts suggested that Vastatin induced significant antiangiogenesis. Moreover, a synergistic effect in extending survival was detected when H1-Vastatin was administered with temozolomide (TMZ) in GB chemoresistant murine models.

Conclusion

Our results suggest, for the first time, that Vastatin is an antiangiogenic polypeptide with significant potential therapeutic benefit for GB. H1-Vastatin gene therapy may have important implications in re-sensitizing recurrent GB to standard chemotherapeutic agents.

Epigenetic regulation of matrix metalloproteinases and their collagen substrates in cancer

Our review covers the recent epigenetic data that are focused on matrix metalloproteinases (MMPs), their inhibitors (tissue inhibitors of MMPs; TIMPs) and collagen substrates. Twenty-four MMPs, four TIMPs and at least 28 collagen types are known in humans. The MMP activity regulates the functionality of multiple extracellular matrix proteins, cytokines, growth factors and cell signaling and adhesion receptors. Aberrantly enhanced MMP proteolysis affects multiple cell functions, including proliferation, migration and invasion. This aberrant MMP proteolysis is frequently recorded in cancer. Recent evidence, however, indicates that several MMPs function as tumor suppressors in cancer. Their inhibition could have pro-tumorigenic effects (making them anti-targets), counterbalancing the benefits of target inhibition and leading to adverse effects in cancer patients. The current epigenetic data suggest that there are distinct multi-layered epigenetic mechanisms that regulate MMPs, TIMPs and collagens. We show that in certain cancer types, epigenetic signatures of selected MMPs exhibit stem cell-like characteristics. Epigenetic mechanisms appear to play an especially important role in glioblastoma multiforme. Glioblastomas/gliomas synthesize de novo and then deposit collagens into the brain parenchyma. The collagen deposition, combined with an enhanced MMP activity in glioblastomas/gliomas, facilitates rapid invasion of tumor cells through the brain. It is tempting to hypothesize that the epigenetic mechanisms which control MMPs, TIMPs and collagens and, consequently, tumor cell invasion, represent promising drug targets and that in the near future these targets will be challenged pharmacologically.

Gene expression patterns related to vascular invasion and aggressive features in endometrial cancer

The presence of tumor cells entering vascular channels is a prognostic marker for many cancers, including endometrial carcinoma. Vascular invasion is considered to be an early step in the metastatic process and important for the progress of malignant tumors. Here, we investigated the gene expression patterns related to vascular involvement in 57 primary endometrial cancers, using DNA microarray and quantitative PCR techniques. A vascular invasion signature of 18 genes was significantly associated with patient survival and clinicopathological phenotype. Vascular involvement was also related to gene sets for epithelial-mesenchymal transition, wound response, endothelial cells, and vascular endothelial growth factor (VEGF) activity. With immunohistochemical validation, both collagen 8 and matrix metalloproteinase 3 (MMP3) were associated with vascular invasion, whereas ANGPTL4 and IL-8 were associated with patient survival. Our findings indicate that vascular involvement within primary tumors is associated with gene expression profiles related to angiogenesis and epithelial-mesenchymal transition. These data could contribute to an improved understanding of potential targets for metastatic spread and may provide clinically important information for better management of endometrial cancer.

siRNA-targeted COL8A1 inhibits proliferation, reduces invasion and enhances sensitivity to D-limonence treatment in hepatocarcinoma cells

The COL8A1 (collagen type VIII, alpha-1) gene, which encodes the alpha 1 chain of collagen, type VIII, may modulate migration, proliferation and adherence of various cells. Only very sparse information exists on COL8A1 expression in hepatocarcinoma. To investigate the possible role of COL8A1 in the mouse hepatocarcinoma cell line Hca-F with highly metastatic potential in the lymph nodes, we used an RNA interference (RNAi) approach to silence COL8A1 expression. The results showed that a small interfering RNA (siRNA) targeted against COL8A1 significantly impeded Hca-F cells proliferation and colony formation in soft agar. This reduction of COL8A1 expression also led to the decreased invasion of Hca-F cells dramatically in vitro. Furthermore, the downregulation of COL8A1 expression also sensitized cells to the action of D-limonene. These data together provide insights into the function of COL8A1 and suggest that COL8A1 might represent a new potential target for gene therapy in hepatocarcinoma.

Changes in the localization of collagens IV and VIII in corneas obtained from patients with posterior polymorphous corneal dystrophy

Posterior polymorphous corneal dystrophy (PPCD) is a hereditary bilateral disorder affecting primarily the endothelium and Descemet's membrane (DM). The aim of this study was to determine the changes in the presence and localization of the alpha1-alpha6 collagen IV chains and alpha1, alpha2 collagen VIII chains in Czech patients with PPCD. Twelve corneal buttons from ten PPCD patients who underwent corneal grafting, as well as eight unaffected corneas, were used. Enzymatic indirect immunohistochemistry was performed on cryosections using antibodies against the alpha1-alpha6 collagen IV chains and alpha1, alpha2 collagen VIII chains. The intensity of the signal was examined separately in the basal membrane of the epithelium (BME), stroma and DM. More than 50% of PPCD specimens exhibited positivity for alpha1 and alpha2 collagen IV chains in the BME and in the posterior stroma, while no staining was detected in these areas in control specimens. The signal for the alpha1 and alpha2 collagen IV chains was more intense in DM of PPCD corneas compared to controls and it was shifted from the stromal side (in control tissue) to the endothelial side of DM (in the patients). A less intensive signal in PPCD corneas for the alpha3 and alpha5 chains in DM and an accumulation of alpha3-alpha5 in the posterior stroma in diseased corneas were the only differences in staining for the alpha3-alpha6 collagen IV chains. The alpha1 collagen VIII chain was detected on both the endothelial and the stromal sides of DM in 90% of patients with PPCD, compared with the prevailing localization on the stromal side of DM in control corneas. A change in the localization of the alpha2 collagen VIII chain in DM from vertically striated features in control specimens to double line positivity in the DM of PPCD corneas and positive staining in the posterior collagenous layer of four patients were also detected. In three PPCD patients a fibrous pannus located under the BME, positive for alpha1-alpha3, alpha5 collagen IV chains and alpha1 collagen VIII chain, was observed. The increased expression of the alpha1, alpha2 collagen IV and alpha1 collagen VIII chains and the change in their localization in DM may contribute to the increased endothelial proliferative capacity observed in PPCD patients.

Targeted disruption of Col8a1 and Col8a2 genes in mice leads to anterior segment abnormalities in the eye

Collagen VIII is localized in subendothelial and subepithelial extracellular matrices. It is a major component of Descemet's membrane, a thick basement membrane under the corneal endothelium, where it forms a hexagonal lattice structure; a similar structure, albeit less extensive, may be formed in other basement membranes. We have examined the function of collagen VIII in mice by targeted inactivation of the genes encoding the two polypeptide subunits, Col8a1 and Col8a2. Analysis of these mice reveals no major structural defects in most organs, but demonstrates that type VIII collagen is required for normal anterior eye development, particularly the formation of a corneal stroma with the appropriate number of fibroblastic cell layers and Descemet's membrane of appropriate thickness. Complete lack of type VIII collagen leads to dysgenesis of the anterior segment of the eye: a globoid, keratoglobus-like protrusion of the anterior chamber with a thin corneal stroma. Descemet's membrane is markedly thinned. The corneal endothelial cells are enlarged and reduced in number, and show a decreased ability to proliferate in response to different growth factors in vitro. An important function of collagen VIII may therefore be to generate a peri- or subcellular matrix environment that permits or stimulates cell proliferation.

Type VIII collagen: heterotrimeric chain association

Two chains, alpha1(VIII) and alpha2(VIII), have been described for type VIII collagen. Early work suggested that these chains were present in a 2:1 ratio, although recent work has shown that homotrimers can form and predominate in some tissues. In order to address the question of whether the alpha1(VIII) and alpha2(VIII) chains could co-polymerise we made a shortened alpha1(VIII) chain and expressed this with full length alpha2(VIII) chain in an in vitro translation system supplemented with semi-permeabilised cells. Heterotrimers containing either two or one alpha2(VIII) were evident. Interestingly, a point mutation in the NC1 domain of the alpha1(VIII) chain abrogated trimer formation. In addition we were able to demonstrate chain association of the alpha1(X) chain of type X collagen with the shortened alpha1(VIII) chain. Variations in chain association were seen when altered ratios of message were used. These results demonstrate the importance of the NC1 domain in chain association and suggest that gene expression regulates the composition and function of type VIII collagen by varying chain composition.

Human macrophages synthesize type VIII collagen in vitro and in the atherosclerotic plaque

Type VIII collagen is a short-chain collagen that is present in increased amounts in atherosclerotic lesions. Although the physiological function of this matrix protein is unclear, recent data suggest an important role in tissue remodeling. Type VIII collagen in the atherosclerotic lesion is mainly derived from smooth muscle cells. We now show that macrophages in the atherosclerotic vessel wall and monocytes in adjacent mural thrombi also express type VIII collagen. We demonstrated this using a novel combined fluorescence technique that simultaneously stains, within the same tissue section, specific RNAs by in situ hybridization and proteins by indirect immunofluorescence. In culture, human monocyte/macrophages expressed type VIII collagen at all time points from 1 h to 3 wk after isolation. Western blotting and immunoprecipitation also revealed secretion of type VIII collagen into the medium of 14-day-old macrophages. Because this is the first report of secretion of a collagen by macrophages, we tested the effect of lipopolysaccharide (LPS) and interferon gamma, substances that stimulate macrophages to secrete lytic enzymes, on macrophage expression of type VIII collagen. LPS and interferon gamma decreased expression of type VIII collagen. By contrast, secretion of matrix metalloproteinase 1 (MMP 1) was increased, indicating a switch from a collagen-producing to a degradative phenotype. Double in situ hybridization studies of expression of type VIII collagen and MMP 1 in human coronary arteries showed that in regions important for plaque stability, the ratio of MMP 1 RNA to macrophage type VIII collagen RNA varies widely, indicating that the transition from one phenotype to the other that we observed in vitro may also occur in vivo.

The alpha1(VIII) and alpha2(VIII) chains of type VIII collagen can form stable homotrimeric molecules

Type VIII collagen is a short chain collagen. Two chains have been described, alpha1(VIII) and alpha2(VIII), but the chain composition of type VIII collagen is far from resolved. To address this question, we have expressed full-length alpha1(VIII) and alpha2(VIII) chains in an in vitro translation system supplemented with semipermeabilized cells. Both chains gave a translation product of approximately 80 kDa that could be shown to produce a chymotrypsin/trypsin-resistant product of approximately 60 kDa, indicating that both chains could form homotrimers. Hydroxylation of proline residues was a prerequisite for stable trimer formation. The melting temperature for the alpha1(VIII) homotrimer was 45 degreesC, whereas that for alpha2(VIII) was 42 degreesC. The ability of both chains of type VIII collagen to form stable triple helices suggests that there may be different forms of this collagen and that cells may modulate the chain composition in response to different biological conditions.

Collagen VIII is expressed by vascular smooth muscle cells in response to vascular injury

To identify genes involved in vascular remodeling, we applied differential mRNA display analysis to the rat carotid artery balloon injury model. One polymerase chain reaction product showing increased expression at days 2 to 14 after vascular injury was nearly identical to the mouse alpha 1 chain of type VIII collagen, a heterotrimeric short-chain collagen of uncertain function expressed by a limited number of cell types. By Northern analysis, expression of both chains of the type VIII collagen heterotrimer increased: collagen alpha 1 (VIII) mRNA expression was almost 4-fold higher than control by 7 days after vascular injury, and collagen alpha 2 (VIII) mRNA expression reached a maximum of almost 6-fold above baseline by 3 days after injury. By immunohistochemical analysis, type VIII collagen expression increased in the media and neointima in a localized pattern consistent with the distribution of activated dedifferentiated vascular smooth muscle cells (VSMCs). Cultured VSMCs expressed higher levels of type VIII collagen in response to serum and growth factors, notably platelet-derived growth factor (PDGF)-BB. VSMCs adhered significantly less to type VIII collagen than to type I collagen substrata and showed greater PDGF-BB-stimulated migration (by 2.2-fold) on type VIII collagen than on type I collagen. We hypothesize that increased expression of type VIII collagen by VSMCs after arterial injury may contribute to vascular remodeling through the promotion of VSMC migration.

Tumor infarction in mice by antibody-directed targeting of tissue factor to tumor vasculature

Selective occlusion of tumor vasculature was tested as a therapy for solid tumors in a mouse model. The formation of blood clots (thrombosis) within the tumor vessels was initiated by targeting the cell surface domain of human tissue factor, by means of a bispecific antibody, to an experimentally induced marker on tumor vascular endothelial cells. This truncated form of tissue factor (tTF) had limited ability to initiate thrombosis when free in the circulation, but became an effective and selective thrombogen when targeted to tumor endothelial cells. Intravenous administration of the antibody-tTF complex to mice with large neuroblastomas resulted in complete tumor regressions in 38 percent of the mice.

Type VIII collagen is a product of vascular smooth-muscle cells in development and disease

Type VIII collagen is a short-chain collagen with considerable similarity to type X collagen. We have generated chain-specific antibodies to the alpha 1 and alpha 2 chains of type VIII collagen, and used them as probes to examine the synthesis of type VIII collagen by vascular smooth muscle cells (VSMC). In addition, chain-specific oligonucleotides have been used in reverse transcriptase-PCR (RT-PCR) reactions with RNA extracted from cultured smooth muscle cells in culture and from freshly isolated vascular tissues. Radiolabelling of VSMC in culture and immunoprecipitation with chain-specific antibodies showed that both chains were expressed. Lower levels of type VIII collagen were found in adult VSMC than in neonatal VSMC. RT-PCR showed that both chains were expressed in tissues as well as cells in culture. The results indicate that type VIII collagen is a product of VSMC of normal adult vessels and is expressed at high levels by VSMC in vascular lesions.

Alternative RNA splicing of the hyaluronic acid receptor CD44 in the normal human brain and in brain tumors

The cell-surface receptor for hyaluronic acid, CD44, is expressed by both normal and malignant cells. Numerous CD44 isoforms have recently been identified that are derived by alternative ribonucleic acid splicing. The expression of some CD44 isoforms has been shown to be involved in tumor progression and metastatic spread in a rat carcinoma model and in human carcinomas. In the present study, CD44 isoform expression was evaluated by reverse transcriptase-polymerase chain reaction (PCR) analysis in frozen sections derived from three samples of normal brain tissue and from 40 brain tumors, including samples of glioblastoma multiforme, anaplastic astrocytoma, low-grade astrocytoma, cerebral primitive neuroectodermal tumor, medulloblastoma, metastatic colon carcinoma, and metastatic melanoma. Normal brain tissue adjacent to the tumors was also examined in 14 of 18 glioblastomas. In all normal brain and tumor samples, with the exception of metastases from colon carcinoma, PCR analysis demonstrated one prominent product that corresponded to the CD44H hematopoietic form of CD44. Metastases from colon carcinoma demonstrated two prominent PCR amplification products corresponding to CD44H and CD44R1. These results suggest that CD44H is the predominant isoform of this protein in normal human brain tissue and in human neuroectodermal tumors of varying degrees of malignancy. The ability of CD44H to mediate tumor cell motility and invasiveness (in contrast to CD44R1) suggests that the CD44 alternative splicing pattern of neuroectoderm-derived tumors may enhance their local biological aggressiveness and intracerebral spread. The lack of expression of larger molecular weight CD44 variants by primary brain tumors may also partially explain why these tumors rarely metastasize to distant sites.

Expression of type VII collagen, the major anchoring fibril component, in normal and neoplastic human nervous system

The distribution of type VII collagen was examined in the normal human nervous system, in brain tumour biopsies and in glioma cell lines by immunohistochemistry and western blotting. In normal tissue, positivity was observed beneath choroid plexus epithelial cells and around pineal gland and pituitary gland cell nests, while other brain regions and peripheral nerves were negative. Expression was preserved in most related tumours (choroid plexus papilloma, pineoblastoma, pituitary adenoma). Scattered abnormal vessels showed neo-expression of type VII collagen in about half of the astrocytic and ependymal tumours. Glioma cells in situ were consistently negative for type VII collagen, whereas the glioblastoma cell lines were positive. Our results suggest that anchoring fibrils or at least epitopes of their major structural component are present in normal and pathological cerebral structures, indicating a unique distribution of type VII collagen in the nervous system.

Human mast cells produce type VIII collagen in vivo

Mast cells are assuming importance not only in their familiar role in acute allergic and parasitic diseases but also in chronic inflammatory, immunologic and fibrotic states. The processes by which human extracellular matrices are influenced by mast cells have remained obscure. We report here the production of type VIII collagen by human mast cells. Mast cells representing each of the known phenotypes were identified in a variety of tissues using histochemical techniques, and monoclonal antibodies specific for tryptase, chymase, and c-kit. Mast cells in normal and pathologic tissues expressed type VIII collagen alpha-1 chain protein and mRNA, detected by immunohistochemistry using monoclonal and polyclonal antibodies, and non-isotopic oligonucleotide in situ hybridization using digoxigenin-labelled oligonucleotide probes based on the published human alpha-1 collagen VIII sequence. Perivascular location of type VIII collagen positive mast cells was a striking finding. The secretion of type VIII collagen by mast cells in vivo may contribute to angiogenesis, tissue remodelling, and fibrosis.

Expression of tenascin in human gliomas: its relation to histological malignancy, tumor dedifferentiation and angiogenesis

The immunohistochemical distribution of tenascin (TN), fibronectin (FN), and laminin (LN) was investigated in 56 human gliomas (8 astrocytomas, 15 anaplastic astrocytomas, and 33 glioblastomas) with regards to the histological degree of malignancy and the degree of tumor cell differentiation evaluated by the staining of glial fibrillary acidic protein (GFAP). In 8 anaplastic astrocytomas and 28 glioblastomas, TN was predominantly immunolocalized in the basement membrane zone of the proliferating tumor vessels; sections of all astrocytomas were negative for TN staining. FN was localized in the basement membrane zone of the vessels in all astrocytomas, 12 anaplastic astrocytomas, and 22 glioblastomas. In 7 anaplastic astrocytomas and 19 glioblastomas, both TN and FN were expressed to various degrees in the tumor vessels. However, most of the TN-positive vessels did not express FN, and most of the FN-positive vessels were negative for TN staining. Furthermore, in 6 anaplastic astrocytomas and 12 glioblastomas, either TN or FN, but not both, were expressed in any area on serial sections. Most of the tumor cells around TN-positive, FN-negative tumor vessels did not express GFAP. On the other hand, GFAP was present in most tumor cells around TN-negative, FN-positive vessels. LN was detected in all vascular and pial-glial basement membrane zone of the tissues examined. These findings indicate that the degree of histological malignancy and the degree of cell dedifferentiation of human gliomas correlate well with the expression of TN, but are inversely correlated with the expression of FN.(ABSTRACT TRUNCATED AT 250 WORDS)

Neoplastic association of enhanced type V collagen production in rat fibrosarcoma

Collagens present in the connective tissues of the extracellular matrix of fibrosarcoma were isolated and characterized. The fibrosarcoma was induced in rats by the administration of 3-methylcholanthrene. The results obtained were compared with normal muscle. An excess amount of type V collagen was found to be produced by the fibrosarcoma tissue compared to the normal muscle. Type V collagen from fibrosarcoma was characterized on the basis of solubility behavior in sodium chloride solutions, electrophoretic mobility on SDS-polyacrylamide gels, elution pattern of phosphocellulose chromatography and amino acid composition.

Cleavage of type VIII collagen by human neutrophil elastase

In this report, the susceptibility of type VIII collagen to human neutrophil elastase is compared to other extracellular matrix components. Type X collagen is degraded to specific fragments at a substrate to enzyme ratio of 5:1 after 20 h at room temperature, but type VIII collagen is almost completely degraded after only 4 h incubation at a substrate to enzyme ratio of 50:1 and partly degraded after only 15 min. Laminin, merosin and types I, III, IV and V collagen exhibit no susceptibility to neutrophil elastase under the latter conditions, while fibronectin is degraded.