Suppression of ras oncogene-mediated transformation

Schäfer, Reinhold

doi:10.1007/bfb0031031

Cited by 7 publications

(3 citation statements)

References 275 publications

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“…Membrane ruffling is found to be increased in many ras-transformed cells (4,43) and is required for the mitogenic activity of Ras (30). Likewise, in our cell model, the increased ruffling of the transfected cells can be attributed to their increased Ras activity, since Ras has been shown to mediate the effects of the Rac GTPase, which regulates actin reorganization to form membrane ruffles (48). Ras signaling through the Rho and Rac GTPases may therefore account for the reduced adherence of the transformed cells, manifested in both the rounded shape and the increased ruffling.…”

Section: Resultsmentioning

confidence: 65%

“…most investigations of Ras signaling effects on the cytoskeleton have used fibroblasts (44,45,48), although it has been shown that the effects of Ras and its downstream effectors can be different in epithelial cells than in fibroblasts (47). This initial characterization of the normal and ras-transfected NRK-52E cell model is, therefore, highly valuable for the study of Ras signaling involving downstream elements and the cytoskeleton, and the role of Ras in tumorigenesis in the kidney and in the pathophysiological processes leading to renal dysfunction.…”

Section: Resultsmentioning

confidence: 99%

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H-ras-transformed NRK-52E renal epithelial cells have altered growth, morphology, and cytoskeletal structure that correlates with renal cell carcinoma in vivo

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Tanzer

Phelps

et al. 1999

In Vitro Cell.Dev.Biol.-Animal

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We studied the effect of the ras oncogene on the growth kinetics, morphology, cytoskeletal structure, and tumorigenicity of the widely used NRK-52E rat kidney epithelial cell line and two H-ras oncogene-transformed cell lines, H/1.2-NRK-52E (H/1.2) and H/6.1-NRK-52E (H/6.1). Population doubling times of NRK-52E, H/1.2, and H/6.1 cells were 28, 26, and 24 h, respectively, with the transformed cells reaching higher saturation densities than the parent cells. NRK-52E cells had typical epithelial morphology with growth in colonies. H/1.2 and H/6.1 cell colonies were more closely packed, highly condensed, and had increased plasma membrane ruffling compared to parent cell colonies. NRK-52E cells showed microfilament, microtubule, and intermediate filament networks typical of epithelial cells, while H/1.2 and H/6.1 cells showed altered cytoskeleton architecture, with decreased stress fibers and increased microtubule and intermediate filament staining at the microtubule organizing center. H/1.2 and H/6.1 cells proliferated in an in vitro soft agar transformation assay, indicating anchorage-independence, and rapidly formed tumors in vivo with characteristics of renal cell carcinoma, including mixed populations of sarcomatoid, granular, and clear cells. H/6.1 cells consistently showed more extensive alterations of growth kinetics, morphology, and cytoskeleton than H/1.2 cells, and formed tumors of a more aggressive phenotype. These data suggest that analysis of renal cell characteristics in vitro may have potential in predicting tumor behavior in vivo, and significantly contribute to the utility of these cell lines as in vitro models for examining renal epithelial cell biology and the role of the ras proto-oncogene in signal transduction involving the cytoskeleton.

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Section: Resultsmentioning

confidence: 65%

Section: Resultsmentioning

confidence: 99%

H-ras-transformed NRK-52E renal epithelial cells have altered growth, morphology, and cytoskeletal structure that correlates with renal cell carcinoma in vivo

Best

Tanzer

Phelps

et al. 1999

In Vitro Cell.Dev.Biol.-Animal

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“…In addition, the expression of protein kinase C family isoforms is abrogated after activation of oncogenic HRAS ( Geiges et al, 1995 ), and some downregulated genes have been described with as yet unknown function, e.g., the 322 gene ( Lin et al, 1995 ). Several of those genes were shown to be reexpressed in the revertant cell lines derived from HRAS -transformed fibroblasts (for review see Schäfer, 1994 ). Therefore, the reversible functional loss of these gene activities may be causally involved in the process of neoplastic transformation.…”

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confidence: 99%

Growth-inhibitory Activity and Downregulation of the Class II Tumor-suppressor Gene H-rev107 in Tumor Cell Lines and Experimental Tumors

Sers

Emmenegger

Husmann

et al. 1997

The Journal of Cell Biology

107

101

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The H-rev107 gene is a new class II tumor suppressor, as defined by its reversible downregulation and growth-inhibiting capacity in HRAS transformed cell lines. Overexpression of the H-rev107 cDNA in HRAS-transformed ANR4 hepatoma cells or in FE-8 fibroblasts resulted in 75% reduction of colony formation. Cell populations of H-rev107 transfectants showed an attenuated tumor formation in nude mice. Cells explanted from tumors or maintained in cell culture for an extended period of time no longer exhibited detectable levels of the H-rev107 protein, suggesting strong selection against H-rev107 expression in vitro and in vivo. Expression of the truncated form of H-rev107 lacking the COOH-terminal membrane associated domain of 25 amino acids, had a weaker inhibitory effect on proliferation in vitro and was unable to attenuate tumor growth in nude mice. The H-rev107 mRNA is expressed in most adult rat tissues, and immunohistochemical analysis showed expression of the protein in differentiated epithelial cells of stomach, of colon and small intestine, in kidney, bladder, esophagus, and in tracheal and bronchial epithelium. H-rev107 gene transcription is downregulated in rat cell lines derived from liver, kidney, and pancreatic tumors and also in experimental mammary tumors expressing a RAS transgene. In colon carcinoma cell lines only minute amounts of protein were detectable. Thus, downregulation of H-rev107 expression may occur at the level of mRNA or protein.

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Partial restoration of pre‐transformation levels of lysyl oxidase and transin mRNAs in phenotypic ras revertants

Oberhuber

Seliger

Schäfer

1995

Molecular Carcinogenesis

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Neoplastic transformation mediated by ras oncogenes is associated with deregulated expression of genes encoding, for example, various proteases, lysyl oxidase, and smooth-muscle alpha-actin. To define the role of these genes in the initiation or maintenance of the ras-transformed state, we compared their steady-state mRNA levels in two different sets of preneoplastic fibroblast lines, ras-transformed clones, and phenotypic revertants derived from them. Compared with the preneoplastic fibroblasts, the ras-transformed derivatives exhibited elevated levels of cathepsin L (major excreted protein), transin (stromelysin I, matrix metalloproteinase-3), and collagenase I (matrix metalloproteinase-1) mRNA but undetectable levels of lysyl oxidase mRNA. Partial restoration of lysyl oxidase transcription was observed in four of five phenotypic revertants derived from rat FE-8 and NIHpEJcl3 cells. The elevated levels of transin mRNA found in NIHpEJcl3 cells were diminished to the pretransformation level in interferon revertants but were not reduced in phenotypic rat FE-8 revertants expressing a high level of the ras oncoprotein. High steady-state levels of collagenase I mRNA were dependent on ras expression but were not closely associated with the transformed phenotype. High levels of cathepsin L mRNA were associated with neither high ras expression nor neoplastic transformation. The downregulation of smooth-muscle alpha-actin, characteristic of transformed cell lines, was not reversible in phenotypic revertants.

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Suppression of ras oncogene-mediated transformation

Cited by 7 publications

References 275 publications

H-ras-transformed NRK-52E renal epithelial cells have altered growth, morphology, and cytoskeletal structure that correlates with renal cell carcinoma in vivo

H-ras-transformed NRK-52E renal epithelial cells have altered growth, morphology, and cytoskeletal structure that correlates with renal cell carcinoma in vivo

Growth-inhibitory Activity and Downregulation of the Class II Tumor-suppressor Gene H-rev107 in Tumor Cell Lines and Experimental Tumors

Partial restoration of pre‐transformation levels of lysyl oxidase and transin mRNAs in phenotypic ras revertants

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