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Biomedical subjects

R F Cerra

Publications and source records attributed to R F Cerra.

11 recordsLinked to original sources
PubMed1990

Changes associated with metastasis in B16-F1 melanoma cells surviving heat.

Metastasis to distant sites is mediated by various receptors on the surface of tumor cells. B16-F1 melanomas surviving 43.5 degrees C heat in vitro for 15 minutes and cultured for 10 days bind significantly increased amounts of the basement membrane protein laminin. Motility of heat-resistant B16-F1 cells in vitro toward the chemoattractant laminin is significantly increased. The increased expression of putative laminin receptors may be associated with increased metastasis of melanomas after subcurative hyperthermia.

Cell Survival↗
PubMed1989

Organ-specific chemotactic factors present in lung extracellular matrix.

The preferential colonization of a distant organ by a circulating tumor cell (organ specific metastasis) may be regulated by chemotactic factors present within the extracellular matrix of the host organ. Organ-specific extracellular matrix was prepared from murine kidney and lung by high salt extraction and DNAase/RNAase digestion. A soluble protein fraction (S2) from each of the matricies was obtained by 4 M guanidine extraction and was tested for organ-specific chemotactic activity in a modified Boyden chamber. The lung colonizing B16-F10 and B16-BL6 tumor cell lines demonstrated organ-specific motility only toward the lung extract. The low metastasizing B16 parental line and liver colonizing B16-L4b line showed no preference for either lung or kidney. The lung activity resolves into five fractions by gel filtration chromatography, with the highest activity eluting at Mr approximately 71,000. Chemotactic factors present in lung extracellular matrix may regulate the preferential colonization of an organ by stimulating the migration of tumor cells in a specific manner. These factors may be released during the degradation of the extracellular matrix.

Cell Line↗
PubMed1986

Secretion of a cytoplasmic lectin from Xenopus laevis skin.

The skin of Xenopus laevis contains a soluble beta-galactoside-binding lectin with a approximately 16,000-mol-wt subunit. It resembles similar lectins purified from a variety of tissues from other vertebrates, and differs from two other soluble X. laevis lectins from oocytes and serum that bind alpha-galactosides. The skin lectin is concentrated in the cytoplasm of granular gland and mucous gland cells, as demonstrated by immunohistochemistry with the electron microscope. Upon injection with epinephrine, there is massive secretion of the cytoplasmic lectin from the granular gland cells.

Amino Acids↗
PubMed1985

Three soluble rat beta-galactoside-binding lectins.

Both immature and adult rat lungs contain three prominent soluble beta-galactoside-binding proteins with subunit Mr approximately 14,500, 18,000, and 29,000 rather than only the one noted previously. They are readily resolved by ion-exchange chromatography, and antibodies raised against them show little cross-reaction. The three proteins were also found in immature heart, skeletal muscle, and liver, but only the protein with subunit Mr approximately 14,500 was found in these tissues in young adults.

Aging↗
PubMed1984

Endogenous mammalian lectin localized extracellularly in lung elastic fibers.

An affinity-purified antibody preparation raised against a beta-galactoside-binding lectin from bovine lung was used to localize a similar lectin in rat lung by immunofluorescence and by electron microscopy after on-grid staining visualized with colloidal gold conjugated second antibody. The endogenous mammalian lectin was found in smooth muscle cells and squamous alveolar epithelial (type I) cells and was concentrated extracellularly in elastic fibers of pulmonary parenchyma and blood vessels. The extracellular localization of this lectin suggests that it, like others, functions by interaction with extracellular glycoconjugates.

Animals↗
PubMed1984

Localization of soluble endogenous lectins and their ligands at specific extracellular sites.

Soluble lectins of chicken, rat, frog, and the cellular slime mold, Dictyostelium discoideum, were purified and specific antibodies raised against these proteins were used to immunohistochemically localize the lectins in and around the tissues in which they were synthesized. Within cells, some of these soluble lectins (chicken-lactose-lectin-II in intestinal goblet cells, discoidin II in prespore cells) appear to be concentrated within vesicles whereas others (e.g., rat beta-galactoside lectin in pulmonary alveolar and smooth muscle cells) appear to be free in the cytoplasm. All of these lectins are eventually secreted to extracellular sites in developing or adult tissues. The sites include mucin (chicken-lactose-lectin-II in intestine); developing extracellular matrix (chicken-lactose-lectin-I in muscle; Xenopus laevis lectin in blastula stage embryos); slime (discoidin I); developing spore coat (discoidin II); and a specialized extracellular matrix, elastic fibers (rat beta-galactoside lectin in lung). In cases where this has been studied in detail (discoidin I, discoidin II, and chicken-lactose-lectin-II), the lectin is associated with a complementary extracellular ligand, at least transiently. Lectin-ligand interactions presumably confer specialized properties in these particular extracellular domains.

Animals↗
PubMed1982

Membrane-associated actin from the microvillar membranes of ascites tumor cells.

A membrane fraction (MF2) has been purified from isolated microvilli of the MAT-C1 subline of the 13762 rat mammary ascites adenocarcinoma under conditions which cause F-actin depolymerization. This membrane preparation contains actin as a major component, although no filamentous structures are observed by transmission electron microscopy. Membranes were extracted with a Triton X-100-containing actin-stabilizing buffer (S buffer) or actin-destabilizing buffer (D buffer). In D buffer greater than 90% of metabolically labeled protein and glycoprotein was extracted, and 80-90% of these labeled species was extracted in S buffer. When S buffer extracts of MF2 were fractionated by either gel filtration on Sepharose 6 B or rate-zonal sucrose density gradient centrifugation, most of the actin was found to be intermediate in size between G- and F-actin. In D buffer most of the MF2 actin behaved as G-actin. Extraction and gel filtration of intact microvilli in S buffer also showed the presence of the intermediate form of actin, indicating that it did not arise during membrane preparation. When [35S]methionine-labeled G-actin from ascites cells was added to S buffer extracts of MF2 and chromatographed, all of the radioactivity chromatographed as G-actin, indicating that the intermediate form of actin did not result from an association of G-actin molecules during extraction or chromatography. The results of this study suggest that the microvillar membrane fraction is enriched in an intermediate form of actin smaller than F-actin and larger than G-actin.

Actins↗
PubMed1980

alpha-Actinin-containing branched microvilli isolated from an ascites adenocarcinoma.

Microvilli, slender projections approximately 0.1 micrometer in diameter which occur on the surfaces of many cell types, are bounded by plasma membrane except at the site of attachment to the cell body and contain microfilament bundle cores. The presence of both microfilaments and plasma membrane suggests the use of microbilli for investigations of membrane cytoskeleton interactions. Immunofluorescence studies with anti-alpha-actinin have suggested that alpha-actinin is concentrated at the tips of intestinal brush border microvilli and might link actin microfilaments and the plasma membrane. However, this idea was disputed by later immunofluorescence and electrophoresis studies. To investigate the components and organization of microvilli from a less highly differentiated cell type, we have used an ascites sub-line (MAT-Cl) of a rat mammary tumour, the 13762 mammary adenocarcinoma, whose microvilli are high branched. Becaused such unusual structures may provide an understanding of cell-surface assemblies important in determining cell morphology, we have developed a procedure for isolating the branched microvilli and have shown that they contain significant quantities of alpha-actinin.

Actinin↗
PubMedDate not supplied

Chemotactic activity present in liver extracellular matrix.

A selective pattern of metastasis, not accountable by a simple mechanical trapping mechanism, is exhibited by many primary tumors and appears to be controlled by properties of both the tumor cell and the host organ. This organotropism may be regulated, in part, by the migration of an invading tumor cell toward chemotactic factors present in the extracellular matrix which may be released as a result of proteolytic digestion. To test this hypothesis we have examined 4 M guanidine extracts of liver extracellular matrix, prepared by high salt extraction, for organ-specific chemotactic activity. The murine cell lines B16-L4b and M5076, which preferentially metastasize to the liver in an experimental metastasis model, demonstrated preferential motility toward the liver matrix extract while the lung-colonizing lines B16, B16-F10 and B16-BL6 did not. The liver specific chemotactic activity eluted as four fractions of Mr much less than 250,000, Mr approximately 245,000, Mr approximately 120,000 and Mr approximately 30,000 by gel filtration chromatography.

Animals↗