Cell surface glycoproteins and malignant transformation (original) (raw)
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Different cyclic changes in the surface membrane of normal and malignant transformed cells
Experimental Cell Research, 1974
Transformed fibroblasts in interphase and normal fibroblasts in mitosis were agglutinated by Con A and the lectin from wheat germ, whereas normal fibrob!asts in interphase and transformed fibroblasts in mitosis were not agglutinated by these lectins. The percentage of fluorescent cells at non-saturation concentrations of fluorescent ConA was also higher with transformed interphase and normal mitotic cells, than with normal interphase and transformed mitotic cells. Under the same conditions, a similar number of radioactively labeled ConA molecules were bound to normal and transformed cells in interphase and mitosis. Our results indicate different cyclic changes in the surface membrane of normal and transformed fibroblasts, so that regarding interaction with these lectins, normal mitotic cells resemble transformed interphase cells and transformed mitotic resemble normal interphase cells. The data suggest that there is a reversed cyclic change in the mobility of specific surface membrane sites in normal and transformed cells.
Cell transformation: the role of oncogenes and factors
Mutagenesis, 1986
An attempt is made to draw together diverse areas of biological research which have recently converged and opened up new experimental approaches to understanding the nature of cancer. In particular, the powerful techniques of molecular biology have been brought to bear on tissue culture systems. The case is made for the continued use of cell transformation in vitro as a real and useful model for cancer development. The hallmark of all cancer cells is loss of control over the cell cycle and the cellular elements involved, growth factors, growth factor receptors and signal transducers have been identified and in some instances shown to be encoded in cellular oncogenes. Moreover, as the molecular mechanisms underlying cell growth control are unravelled, those aspects involved in neoplastic change will be identified and this will lead to the development of definitive short-term tests for the detection of chemical carcinogens.
Modulation of Cell Surface Glycocalyx: Studies on Large, External, Transformation-Sensitive Protein
Annals of the New York Academy of Sciences, 1978
Cold Spring Harbor. New York I I 724 O n c of the distinctive features of cancer cells in vivo is their antisocial behavior in a sea of well-organized normal cells. The symptonis o f such ahnormality include cell division at the wrong time and in the wrong place. penetration to neighboring tissues, travel in the circulation, which should normally be confined to only a few cell types, and adhesion to forbidden tissues. Numerous factors contribute to the antisocial behavior of cancer cells. O n e of them agreed upon by many investigators, is the alteration in the cell surface. Among the alterations on the cell surface that can potentially contribute to the antisocial behavior of cancer cells are changes in composition of the lipid bilayer, in glycolipids, in glycocalyceal components, in topographic structure, and in the motile properties of the cell surface. Each of these aspects is being intensively investigated. The current status of this field has recently been reviewed.'-4 Among numerous alterations in cancer cells, a reduction in one of the cell surface components seems to warrant further investigation, because it may be relevant to the antisocial behavior of cancerous cells. This component is thc large, external. transformation-sensitive (LETS) protein. LETS protein was first detected in fibroblasts by a variety of techniques and has since been termed as band I ,5 galactoprotein a,6 fibronectin,' zeta,' and cell surface protein, CSP.9 It is a glycoprotein with a molecular weight of 220-250,000 daltons. I t is significantly reduced in many virally transformed fibroblasts (for review. see Rcferences 3 and 4). LETS protein was first partially purified by Yamada and Weston' from chick embryo fibroblasts by mild urea extraction. The addition of such purified LETS protein restores the normal morphology of transformed cells.lO.ll 11 has also been suggested by Ruoslahti and Vaherilz that LETS protein is closely related t o a plasma protein. cold-insoluble g l~b u l i n. '~"~ It is likely that cold-insoluble globulin in the blood circulation is the modified shedding product of cell surface LETS protein. Around the spring of 1974 in Dr. J. M. Buchanan's laboratory a t Massachusetts Institute of Technology (MIT), we found that thrombin, a highly specific protease responsible for blood clotting, is a potent mitogen for cultured *Supported by grants from the National Cancer Institute, the Muscular Dystrophy Association. the American Heart Association (Nassau County. New York Chapter
Cell transformation: the role of oncogenes and growth factors
An attempt is made to draw together diverse areas of biological research which have recently converged and opened up new experimental approaches to understanding the nature of cancer. In particular, the powerful techniques of molecular biology have been brought to bear on tissue culture systems. The case is made for the continued use of cell transformation in vitro as a real and useful model for cancer development. The hallmark of all cancer cells is loss of control over the cell cycle and the cellular elements involved, growth factors, growth factor receptors and signal transducers have been identified and in some instances shown to be encoded in cellular oncogenes. Moreover, as the molecular mechanisms underlying cell growth control are unravelled, those aspects involved in neoplastic change will be identified and this will lead to the development of definitive short-term tests for the detection of chemical carcinogens.
Proceedings of the National Academy of Sciences, 1976
The distribution on the cell surface of the large external LETS protein that is transformation sensitive of normal, transformed and tumorigenic cells was examined by immunofluorescent staining. A correlation was established between the expression of fibril-like LETS protein and the oncogenic capabilities of a series of adenovirus-transformed cell lines. In cells expressing a transformed phenotype in vitro, LETS protein is only detected in cell-cell contact areas, wheras in "untransformed" cells LETS protein is distributed over the cell surface. Transformed cells capable of inducing invasive tumors, and the cells of established tumor lines, have low or undetectable levels of LETS protein, as measured by this method. The results indicate that LETS protein has a role in cell-cell adhesion and that reduced expression of this protein at the cell surface is related to the oncogenic phenotype. This relationship has been established for experimentally induced and spontaneous tumors.
Detection of the large external transformation-sensitive protein on some epithelial cells
Experimental Cell Research, 1977
The large, external, transform&ion-sensitive (LETS) protein is detected on the surface of epitbeiial cells. Whereas fibroblasts build a massive network of fibrillar LETS protein in one-week-old confluent culture, epithelial cells do not. This observation may be useful for distinguishing epithelial cells from fibroblasts. When rat liver epitbelial cells are continuously passaged in culture, surface LETS protein undergoes a significant alteration first from fibrillar organization to patchlike, then to complete absence.