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    Immunofluorescent distribution of basement membrane components laminin and collagen type IV was studied in 51 rat colon tumors induced by 1, 2-dimethylhydrazine. In normal colonic mucosa, adenomas and carcinomas in situ continuous basement membranes were present, while in adenocarcinomas they were altered to different extents. An uncoordinated loss, or dissociation, of the two markers studied was found: the degree of collagen type IV loss was often much higher than that of laminin in the same tumor. These data suggest that a reliable determination of cancer invasion by monitoring basement membrane alteration requires the use of several basement membrane markers.
    1,2-Dimethylhydrazine
    Type IV collagen
    Citations (9)
    AIM:To study the expression and significance of laminin in human colorectal carcinoma.METHODS:Using the monoclonal antibody to laminin and streptavidin-peroxidase immunohistochemical method, the expression of laminin in 63 cases of human colorectal carcinoma tissues was determined.RESULTS:In normal marge intestinal mucosa adjacent to carcinoma, laminin was largely restricted to basement membrane in continuous linear pattern. In contrast, human colorectal carcinomas exhibited a progressive loss of an intact basement membrane that was correlated with decreasing differentiation degree.Well and moderately differentiated tumors exhibited a thin basement membrane with intermittent disruptions, and poorly differentiated tumors exhibited no areas of intact basement membrane. An association was found between lack of basement membrane laminin immunohistochemical staining in colorectal carcinoma and poorly differentiated tumor (P < 0.01).CONCLUSION:Immunohistochemical staining for laminin could provide a very useful indexfor the determination of the differentiation degree of colorectal carcinoma.
    Type IV collagen
    Citations (3)
    De novo formation of laminin-positive basement membranes was found to be a distinct morphologic feature of diethylnitrosamine/phenobarbital-induced hepatocellular carcinomas of the rat. The first appearance of extracellularly located laminin occurred in the pre-neoplastic liver lesions (corresponding to neoplastic nodules), and this feature became successively more prominent during the course of hepatocellular carcinoma development. Most groups of tumor cells were surrounded by laminin-positive basement membrane material. The laminin-positive material was also deposited along the sinusoids, a location where no laminin was seen in normal rat liver. The amount of extractable laminin from hepatocellular carcinomas was significantly higher (approximately 100 ng per mg tissue) than that of normal liver tissue (less than 20 ng per mg). In vitro experiments demonstrated that normal and pre-neoplastic rat hepatocytes had the capacity to lay down basement membrane-like material. This occurred, however, only when the hepatocytes were cocultured with certain feeder cells or when grown in the presence of their conditioned media. These results indicate that during experimental hepatocarcinogenesis in the rat some as yet undefined humoral factor(s) might influence the hepatocytes to turn on genes encoding the basement membrane components and further stimulate the assembly and deposition of basement membranes.
    Citations (33)
    Distribution of type IV collagen and laminin in the gingival capillary basement membrane from streptozotocin-induced diabetic rats was investigated using immunoelectron microscopy. Both type IV collagen and laminin were found throughout the basement membrane. Quantitative analysis revealed that the immunoreactive area for laminin did not change with age, and the width of laminin deposition remained constant, even when diabetes was induced in the animals. However, the immunoreactive area for type IV collagen thickened with age. Further, the width of type IV collagen in the basement membrane increased markedly 36 weeks after diabetes was induced. It was concluded that the thickening of the gingival capillary basement membrane in experimentally induced diabetic rats was due an increase of type IV collagen deposition.
    Type IV collagen
    Immunoelectron microscopy
    Lamina densa
    Citations (3)
    The developmental localization patterns of collagen type IV alpha1-5 chains, laminin-1, laminin-5, and laminin alpha2 chain were analyzed in the embryonic mouse eye using isoform specific antibodies and immunofluorescence microscopy. Laminin-1 isoform and alpha1-2(IV) were ubiquitously expressed along the ocular surface basement membranes at a very early stage of eye development. Alpha3-5(IV) were first detected at later stages of development, and exhibited a variable distribution pattern along the ocular surface basement membrane. In contrast, expression of the laminin alpha2 chain was restricted to the conjunctival basement membrane, and was first detected during the same developmental period in which keratin K4-positive, differentiated conjunctival epithelial cells were observed. Although laminin-5 was uniformly expressed along the adult ocular surface basement membrane, during embryogenesis it was first incorporated into the conjunctival basement membrane structure. These data suggest that some of the laminin isoforms, including laminin alpha2 and laminin-5, may play a role in the formation of a conjunctival-type basement membrane. The temporal relationship between the localization of these molecules to the conjunctival basement membrane and the appearance of differentiated conjunctival epithelial cells suggests a role for external influence on the differentiation pathways of ocular surface epithelium.
    Type IV collagen
    Background: Laminins are components of the extracellular matrix that mediate cell adhesion, growth, migration, proliferation and differentiation. Basement membrane (BM) laminins, in particular, may play a role in enhancing carcinoma cell motility. Aim: To evaluate the distribution pattern of laminin in basal cell carcinoma (BCC), as regards the basement membrane, cellular cytoplasm, peritumoral lacunae and surface epithelium and to correlate laminin distribution with different variants of BCC. Patients and Methods: Skin biopsy specimens were obtained from 21 BCC patients for routine histopathological and immunohistochemical study. Laminin was evaluated qualitatively and semiquantitatively using monoclonal mouse antihuman antibody (Dako‐Laminin, 4C7. Code No: MO638, which reacts with the terminal globular domain of the α5 chain) Results: The majority of BCC cases showed patchy cytoplasmic distribution of laminin. The BM expression of laminin, in most cases, was well defined, fine and linear with irregular areas of thickening. Staining intensity was moderate in differentiated and mixed variants, weak in superficial spreading and absent in morpheic types. Conclusion: Cytoplasmic and basement membrane laminin is important in the pathogenesis and invasion of BCC. Most laminin was in basement membrane zone (BMZ), and the more differentiated the tumor, the more cytoplasmic and BM staining it expressed.
    Type IV collagen
    Basal (medicine)
    The abilities of 4 established human pancreatic tumor cell lines (PANC-1, CAPAN-1, AsPc-1, and BxPc-3) to synthesize and to maintain laminin-containing basement membranes when grown in the nude mouse have been examined and compared with synthesis of the glycoprotein laminin by these tumor cells when grown in culture. Immunohistochemical visualization of basement membrane integrity within the transplanted tumors employed a monoclonal antibody specific for human laminin to clearly distinguish between human tumor-produced laminin and murine basement membranes. This technique demonstrated strikingly different degrees of basement membrane formation and laminin distribution for the 4 biologically diverse pancreatic tumors. Basement membranes were present within the differentiated, less invasive tumors, whereas structure basement membranes were absent in the poorly differentiated, invasive tumors. Regardless of their propensity to produce basement membranes in vivo, all 4 pancreatic tumor cell lines continued to synthesize laminin in culture, as was determined by immunologic assays. The most invasive cell line, AsPc-1, released large quantities of soluble laminin into conditioned culture medium. The less invasive, well-differentiated tumor cells did not release laminin into the medium, but they retained the laminin produced by them within the cell layer. The combination of in vivo and in vitro studies indicates that the extent of basement membrane loss by these human pancreatic tumors is not due to an inherent inability of the tumor cells to synthesize the structural component laminin.
    Citations (11)
    Objective: To observe the changes of extracellular matrix in type Ⅱ cells and thickness of basement membrane beneath type Ⅱ cells in old rats. Methods: Inmmunocytochemistry and image analysis were used to measure the relative contents of laminin and fibronectin in type Ⅱ cells in young (1 2 months), adult (8 9 months) and old (25 28 months) rats. Results: There were less laminin, more fibronectin in type Ⅱ cells and thicker basement membrane beneath type Ⅱ cells in old rats. Conclusion: These results suggest the altered metabolism of extracellular matrix from type Ⅱ cells in old rats, which may result in abnormal recovery of alveoli after being injured.
    Type IV collagen
    Matrix (chemical analysis)
    Citations (0)