Oncogenic
            RAS
            instructs morphological transformation of human epithelia via differential tissue mechanics

AbstractThe RAS proto-oncogene is a critical regulator of cell state, morphology and mechanics, and plays a key role in cancer progression. Here, by using a human epithelial model in vitro, we ask how morpho-mechanical changes driven by oncogenic RAS activation at the level of individual cells are collectively integrated to drive changes in tissue behaviour. We found that the uniform oncogenic expression of HRAS.V12 in confined epithelial monolayers causes reproducible changes in the structure and organization of the tissue, which acquires a transitory bilayered morphology. RAS-driven bilayering associates with reproducible layer-specific differences in cell-cell contractility and cell-matrix forces. These drive the initially flat tissues to form three-dimensional structures mimicking some of the behaviours seen in human cancers. Our findings establish a physical mechanism of cellular collectives through which uniform expression of RAS can be interpreted differently in different places of the same tissue to regulate its physiological and pathological morphology.

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CDO, A Robo-related Cell Surface Protein that Mediates Myogenic Differentiation

The Journal of Cell Biology ◽

10.1083/jcb.143.2.403 ◽

1998 ◽

Vol 143 (2) ◽

pp. 403-413 ◽

Cited By ~ 64

Author(s):

Jong-Sun Kang ◽

Philip J. Mulieri ◽

Cary Miller ◽

David A. Sassoon ◽

Robert S. Krauss

Keyword(s):

Axon Guidance ◽

Feedback Loop ◽

Myogenic Differentiation ◽

Surface Protein ◽

C2c12 Cells ◽

Morphological Transformation ◽

Oncogenic Ras ◽

Related Cell ◽

Fibronectin Type Iii ◽

Fibronectin Type

CDO, a member of the Ig/fibronectin type III repeat subfamily of transmembrane proteins that includes the axon guidance receptor Robo, was identified by virtue of its down-regulation by the ras oncogene. We report here that one prominent site of cdo mRNA expression during murine embryogenesis is the early myogenic compartment (newly formed somites, dermomyotome and myotome). CDO is expressed in proliferating and differentiating C2C12 myoblasts and in myoblast lines derived by treating 10T1/2 fibroblasts with 5-azacytidine, but not in parental 10T1/2 cells. Overexpression of CDO in C2C12 cells accelerates differentiation, while expression of secreted soluble extracellular regions of CDO inhibits this process. Oncogenic Ras is known to block differentiation of C2C12 cells via downregulation of MyoD. Reexpression of CDO in C2C12/Ras cells induces MyoD; conversely, MyoD induces CDO. Reexpression of either CDO or MyoD rescues differentiation of C2C12/Ras cells without altering anchorage-independent growth or morphological transformation. CDO and MyoD are therefore involved in a positive feedback loop that is central to the inverse relationship between cell differentiation and transformation. It is proposed that CDO mediates, at least in part, the effects of cell–cell interactions between muscle precursors that are critical in myogenesis.

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Oncogenic Ras Downregulates Rac Activity, Which Leads to Increased Rho Activity and Epithelial–Mesenchymal Transition

The Journal of Cell Biology ◽

10.1083/jcb.149.4.775 ◽

2000 ◽

Vol 149 (4) ◽

pp. 775-782 ◽

Cited By ~ 211

Author(s):

Gerben C.M. Zondag ◽

Eva E. Evers ◽

Jean P. ten Klooster ◽

Lennert Janssen ◽

Rob A. van der Kammen ◽

...

Keyword(s):

Epithelial Cells ◽

Epithelial Mesenchymal Transition ◽

Mdck Cells ◽

Ras Signaling ◽

Morphological Transformation ◽

Mesenchymal Transition ◽

Oncogenic Ras ◽

Epithelial Phenotype ◽

Rho Family ◽

Cytoskeletal Rearrangements

Proteins of the Rho family regulate cytoskeletal rearrangements in response to receptor stimulation and are involved in the establishment and maintenance of epithelial cell morphology. We recently showed that Rac is able to downregulate Rho activity and that the reciprocal balance between Rac and Rho activity is a major determinant of cellular morphology and motility in NIH3T3 fibroblasts. Using biochemical pull-down assays, we analyzed the effect of transient and sustained oncogenic Ras signaling on the activation state of Rac and Rho in epithelial MDCK cells. In contrast to the activation of Rac by growth factor-induced Ras signaling, we found that sustained signaling by oncogenic RasV12 permanently downregulates Rac activity, which leads to upregulation of Rho activity and epithelial–mesenchymal transition. Oncogenic Ras decreases Rac activity through sustained Raf/MAP kinase signaling, which causes transcriptional downregulation of Tiam1, an activator of Rac in epithelial cells. Reconstitution of Rac activity by expression of Tiam1 or RacV12 leads to downregulation of Rho activity and restores an epithelial phenotype in mesenchymal RasV12- or RafCAAX-transformed cells. The present data reveal a novel mechanism by which oncogenic Ras is able to interfere with the balance between Rac and Rho activity to achieve morphological transformation of epithelial cells.

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Differential tissue regulation of insulin-like growth factor binding proteins in experimental diabetes mellitus in the rat

Diabetes ◽

10.2337/diabetes.41.12.1511 ◽

1992 ◽

Vol 41 (12) ◽

pp. 1511-1519 ◽

Cited By ~ 9

Author(s):

M. C. Gelato ◽

D. Alexander ◽

K. Marsh

Keyword(s):

Diabetes Mellitus ◽

Growth Factor ◽

Binding Proteins ◽

Experimental Diabetes ◽

Insulin Like Growth Factor ◽

Experimental Diabetes Mellitus ◽

Factor Binding ◽

Differential Tissue

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Effects of Aging on the Morphology of Rubber-Brass Interfacial Layer

Tire Science and Technology ◽

10.2346/1.3555084 ◽

2011 ◽

Vol 39 (1) ◽

pp. 20-43 ◽

Cited By ~ 7

Author(s):

A. Ashirgade ◽

P. B. Harakuni ◽

W. J. Vanooij

Keyword(s):

Chemical Composition ◽

Interfacial Layer ◽

Secondary Ion Mass Spectrometry ◽

Morphological Changes ◽

Grazing Incidence ◽

Complex Nature ◽

Rubber Compound ◽

Tire Cord ◽

Morphological Transformation ◽

Adhesion Promoter

Abstract Adhesion between rubber compound and brass-plated steel tire cord is crucial in governing the overall performance of tires. The rubber-brass interfacial adhesion is influenced by the chemical composition and thickness of the interfacial layer. It has been shown that the interfacial layer consists mainly of sulfides and oxides of copper and zinc. This paper discusses the effect of changes in the chemical composition and the structure of the interfacial layers due to addition of adhesion promoter resins. Grazing incidence x-ray diffraction (GIXRD) experiments were run on sulfidized polished brass coupons previously bonded to five experimental rubber compounds. It was confirmed that heat and humidity conditions lead to physical and chemical changes of the rubber-steel tire cord interfacial layer, closely related to the degree of rubber-brass adhesion. Morphological transformation of the interfacial layer led to loss of adhesion after aging. The adhesion promoter resins inhibit unfavorable morphological changes in the interfacial layer, thus stabilizing it during aging and prolonging failure. Tire cord adhesion tests illustrated that the one-component resins improved adhesion after aging using a rubber compound with lower cobalt loading. Based on the acquired diffraction profiles, these resins were also found to impede crystallization of the sulfide layer after aging, leading to improved adhesion. Secondary ion mass spectrometry depth profiles and scanning electron microscopy micrographs strongly corroborated the findings from GIXRD. This interfacial analysis adds valuable information to our understanding of the complex nature of the rubber-brass bonding mechanism.

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