Melanoma Research Today is a free monthly online journal that collates and summarizes the latest research about Melanoma, including details on identification, causes, prevention, treatment. | ||||||||
|
Antitumor NK activation induced by the Toll-like receptor 3-TICAM-1 (TRIF) pathway in myeloid dendritic cells.Akazawa T, Ebihara T, Okuno M, Okuda Y, Shingai M, Tsujimura K, Takahashi T, Ikawa M, Okabe M, Inoue N, Okamoto-Tanaka M, Ishizaki H, Miyoshi J, Matsumoto M, Seya T Department of Immunology, Osaka Medical Center for Cancer, Nakamichi 1-3-2, Higashinari-ku, Osaka 537-8511, Japan. Myeloid dendritic cells (mDCs) recognize and respond to polyI:C, an analog of dsRNA, by endosomal Toll-like receptor (TLR) 3 and cytoplasmic receptors. Natural killer (NK) cells are activated in vivo by the administration of polyI:C to mice and in vivo are reciprocally activated by mDCs, although the molecular mechanisms are as yet undetermined. Here, we show that the TLR adaptor TICAM-1 (TRIF) participates in mDC-derived antitumor NK activation. In a syngeneic mouse tumor implant model (C57BL/6 vs. B16 melanoma with low H-2 expresser), i.p. administration of polyI:C led to the retardation of tumor growth, an effect relied on by NK activation. This NK-dependent tumor regression did not occur in TICAM-1(-/-) or IFNAR(-/-) mice, whereas a normal NK antitumor response was induced in PKR(-/-), MyD88(-/-), IFN-beta(-/-), and wild-type mice. IFNAR was a prerequisite for the induction of IFN-alpha/beta and TLR3. The lack of TICAM-1 did not affect IFN production but resulted in unresponsiveness to IL-12 production, mDC maturation, and polyI:C-mediated NK-antitumor activity. This NK activation required NK-mDC contact but not IL-12 function in in vivo transwell analysis. Implanted tumor growth in IFNAR(-/-) mice was retarded by adoptively transferring polyI:C-treated TICACM-1-positive mDCs but not TICAM-1(-/-) mDCs. Thus, TICAM-1 in mDCs critically facilitated mDC-NK contact and activation of antitumor NK, resulting in the regression of low MHC-expressing tumors. Published 3 January 2007 in Proc Natl Acad Sci U S A, 104(1): 252-7.
© 2004-2008 Melanoma Research Today. All Rights Reserved. |
| ||||||
