title: Silencing of SOCS1 in macrophages suppresses tumor  development by enhancing antitumor inflammation.
abstract: Inflammation has been shown to contribute to both tumor development and antitumor immunity. However, conditions determining these opposing effects are not well understood. Suppressor of cytokine signaling 1 (SOCS1) has been shown to play an important role in regulating inflammation and tumor development. It has been reported that silencing of SOCS1 gene in dendritic cells potentiates antitumor immunity, while SOCS1-deficiency in whole organs except for T and B cells enhances inflammation-mediated colon tumor development. To determine which types of cells are important for the suppression of tumor development by SOCS1-deficiency, we employed the conditional knockout strategy. SOCS1 gene was deleted in macrophages and neutrophils by crossing SOCS1-flox/flox mice with LysM-cre mice. Resulting conditional knockout (cKO) mice showed enhanced sensitivity to endotoxin shock. SOCS1-cKO mice survived much longer than wild-type mice after B16 melanoma transplantation. Colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) plus dextran sulfate sodium (DSS) was also reduced in SOCS1-cKO mice. SOCS1-deficiency in monocytic cells enhanced tumor-killing activity of macrophages and tumor-specific cytotoxic T cell activity. These results suggest that inflammation induced by SOCS1-deficiency in monocytes potentiates antitumor immune responses rather than tumor-promoting inflammation.
authors.affiliation: Division of Molecular and Cellular Immunology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Toranoshin
authors.initials: T
authors.lastname: Ayada
authors.forename: Ichiko
authors.initials: I
authors.lastname: Kinjyo
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Hiwatashi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yoshida
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Okada
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D019175:DNA Methylation; D004195:Disease Models, Animal; D007249:Inflammation / Q000235:genetics / Q000276:immunology*; D053208:Kaplan-Meier Estimate; D008264:Macrophages / Q000276:immunology*; D008546:Melanoma, Experimental / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000172:deficiency* / Q000235:genetics; D016019:Survival Analysis; D023041:Xenograft Model Antitumor Assays
chemical_list: C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins