Journal Article

Complex effects of Ras proto-oncogenes in tumorigenesis

Roberto Diaz, Lluis Lopez-Barcons, Daniel Ahn, Antonio Garcia-Espana, Andrew Yoon, Jeremy Matthews, Ramon Mangues, Roman Perez-Soler and Angel Pellicer

in Carcinogenesis

Volume 25, issue 4, pages 535-539
Published in print April 2004 | ISSN: 0143-3334
Published online April 2004 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgh026
Complex effects of Ras proto-oncogenes in tumorigenesis

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Ras proteins have been found mutated in about one-third of human tumors. In vitro, Ras has been shown to regulate distinct and contradictory effects, such as cellular proliferation and apoptosis. Nonetheless, the effects that the wild-type protein elicits in tumorigenesis are poorly understood. Depending on the type of tissue, Ras proto-oncogenes appear to either promote or inhibit the tumor phenotype. In this report, we treated wild-type and N-ras knockout mice with 3-methylcholanthrene (MCA) to induce fibrosarcomas and found that MCA is more carcinogenic in wild-type mice than in knockout mice. After injecting different doses of a tumorigenic cell line, the wild-type mice exhibited a shorter latency of tumor development than the knockouts, indicating that there are N-ras-dependent differences in the stromal cells. Likewise, we have analyzed B-cell lymphomas induced by either N-methylnitrosourea or by the N-ras oncogene in mice that over-express the N-ras proto-oncogene and found that the over-expression of wild-type N-ras is able to increase the incidence of these lymphomas. Considered together, our results indicate that Ras proto-oncogenes can enhance or inhibit the malignant phenotype in vivo in different systems.

Keywords: GTP, guanosine triphosphate; MCA, 3-methylcholanthrene; MMTV-LTR, mammary murine tumor virus-long terminal repeat; MNU, N-methylnitrosourea

Journal Article.  3794 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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