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Proc Natl Acad Sci U S A. 2010 Apr 6;107(14):6436-41. doi: 10.1073/pnas.0912827107. Epub 2010 Mar 22.

xCT deficiency accelerates chemically induced tumorigenesis.

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1
Laboratory for Innate Cellular Immunity and Laboratory for Immunogenetics, RIKEN Research Center for Allergy and Immunology, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.

Abstract

During the course of inflammation and its resolution, macrophages are exposed to various cytotoxic materials, including reactive oxygen species. Thus, macrophages require a protective machinery against oxidative stress to survive at the inflammatory site. Here, we showed that xCT, a component of transport system x(c)(-), was significantly up-regulated in activated infiltrating cells, including macrophages and neutrophils at the inflammatory site. System x(c)(-) mediates the uptake of extracellular L-cystine and is consequently responsible for maintenance of intracellular glutathione levels. We established a loss-of-function mouse mutant line of xCT by N-ethyl-N-nitrosourea mutagenesis. Macrophages from xCT(mu/mu) mice showed cell death in association with the excessive release of high mobility group box chromosomal protein 1 upon stimulation with LPS, suggesting that xCT deficiency causes unremitting inflammation because of the impaired survival of activated macrophages at the inflammatory site. Subcutaneous injection of 3-methylcholanthrene (3-MCA) induced the generation of fibrosarcoma in association with inflammation. When 3-MCA was injected s.c. into mice, xCT mRNA was up-regulated in situ. In xCT(mu/mu) mice, inflammatory cytokines (such as IL-1beta and TNFalpha) were overexpressed, and the generation of 3-MCA-induced fibrosarcoma was accelerated. These results clearly indicate that the defect of the protective system against oxidative stress impaired survival of activated macrophages and subsequently enhanced tumorigenecity.

PMID:
20308543
PMCID:
PMC2852021
DOI:
10.1073/pnas.0912827107
[Indexed for MEDLINE]
Free PMC Article
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