title: Stat3 activity in melanoma cells affects migration of immune effector cells and nitric oxide-mediated antitumor effects.
abstract: Infiltration of immune effector cells in tumors is critical for antitumor immune responses. However, what regulates immune cell infiltration of tumors remains to be identified. Stat3 is constitutively activated with high frequency in diverse cancers, promoting tumor cell growth and survival. Blocking Stat3 signaling in tumors in vivo results in tumor growth inhibition that involves killing of nontransfected tumor cells and infiltration of immune effector cells, suggesting that Stat3 activity in tumor cells might affect immune cell recruitment. However, dying tumor cells can also attract immune cells. In this study, we show in isogenic murine melanomas that natural Stat3 activity is associated with tumor growth and reduction of T cell infiltration. Blocking Stat3 signaling in the melanoma cells containing high Stat3 activity results in expression of multiple chemoattractants, leading to increased migration of lymphocytes, NK cells, neutrophils, and macrophages. In addition, blocking Stat3 triggers tumor cells to produce soluble factors capable of activating macrophage production of NO in vitro and in vivo. TNF-alpha and IFN-beta, which are secreted by Stat3-inhibited tumor cells, are able to activate macrophage NO production, whereas neutralizing TNF-alpha in the tumor supernatant from Stat3-blocked tumor cells abrogates nitrite production. Moreover, interrupting Stat3 signaling in tumor cells leads to macrophage-mediated, nitrite-dependent cytostatic activity against nontransduced tumor cells. These results suggest that tumor Stat3 activity affects recruitment of diverse immune effectors and it can be manipulated to activate the effector phase of innate immune responses.
authors.affiliation: H. Lee Moffitt Cancer Center and Research Institute and Department of Oncology, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
authors.forename: Lyudmila
authors.initials: L
authors.lastname: Burdelya
authors.forename: Maciej
authors.initials: M
authors.lastname: Kujawski
authors.forename: Guilian
authors.initials: G
authors.lastname: Niu
authors.forename: Bin
authors.initials: B
authors.lastname: Zhong
authors.forename: Tianhong
authors.initials: T
authors.lastname: Wang
authors.forename: Shumin
authors.initials: S
authors.lastname: Zhang
authors.forename: Marcin
authors.initials: M
authors.lastname: Kortylewski
authors.forename: Kenneth
authors.initials: K
authors.lastname: Shain
authors.forename: Heidi
authors.initials: H
authors.lastname: Kay
authors.forename: Julie
authors.initials: J
authors.lastname: Djeu
authors.forename: William
authors.initials: W
authors.lastname: Dalton
authors.forename: Drew
authors.initials: D
authors.lastname: Pardoll
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.forename: Hua
authors.initials: H
authors.lastname: Yu
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002630:Chemotactic Factors / Q000235:genetics; D002633:Chemotaxis / Q000276:immunology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D007113:Immunity, Innate; D008264:Macrophages / Q000378:metabolism; D008546:Melanoma, Experimental / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology; D009569:Nitric Oxide / Q000096:biosynthesis; D050796:STAT3 Transcription Factor; D013601:T-Lymphocytes / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D002630:Chemotactic Factors; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D009569:Nitric Oxide