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A more recent version of this article appeared on February 1, 2008
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Submitted on February 28, 2007
Revised on September 26, 2007
Accepted on November 5, 2007
Expression through a Rac1-dependent NF-
B Pathway


*Stem Cell Research Center, Korea Research Institute of Bioscience and Biotechnology, Yusong, Daejon 305-333, Republic of Korea;
Daedeok Valley Integrated Bio-resources Center and
Department of Biochemistry, Chungnam National University, Daejon 305-764, Republic of Korea; ||Department of Anatomy, Inje University College of Medicine, Pusan 614-735, Republic of Korea
Monitoring Editor: John Cleveland
Interleukin-18 (IL-18) plays pivotal roles in linking inflammatory immune responses and tumor progression and metastasis, yet the manner in which this occurs remains to be sufficiently clarified. Here we report that hypoxia induces the transcription and secretion of IL-18, which subsequently induces the expression of hypoxia-inducible factor-1
(HIF-1
). Mechanistically, IL-18 induces HIF-1
through the activity of the GTPase Rac1, which inducibly associates with the IL-18 receptor
(IL-18R
) subunit, via a PI3K-AKT-NF-
B-dependent pathway. Importantly, the knockdown of the IL-18R
subunit inhibited IL-18-driven tumor cell metastasis. Collectively, these findings demonstrate a feed-forward pathway in HIF-1
-mediated tumor progression, in which the induction of IL-18 by hypoxia or inflammatory cells augments the expression of both HIF-1
and tumor cell metastasis."
These authors contributed equally to this work.
Address correspondence to:
Inpyo Choi (ipchoi{at}kribb.re.kr)