title: NOS Inhibition Modulates Immune Polarization and Improves Radiation-Induced Tumor Growth Delay.
abstract: Nitric oxide synthases (NOS) are important mediators of progrowth signaling in tumor cells, as they regulate angiogenesis, immune response, and immune-mediated wound healing. Ionizing radiation (IR) is also an immune modulator and inducer of wound response. We hypothesized that radiation therapeutic efficacy could be improved by targeting NOS following tumor irradiation. Herein, we show enhanced radiation-induced (10 Gy) tumor growth delay in a syngeneic model (C3H) but not immunosuppressed (Nu/Nu) squamous cell carcinoma tumor-bearing mice treated post-IR with the constitutive NOS inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME). These results suggest a requirement of T cells for improved radiation tumor response. In support of this observation, tumor irradiation induced a rapid increase in the immunosuppressive Th2 cytokine IL10, which was abated by post-IR administration of L-NAME. In vivo suppression of IL10 using an antisense IL10 morpholino also extended the tumor growth delay induced by radiation in a manner similar to L-NAME. Further examination of this mechanism in cultured Jurkat T cells revealed L-NAME suppression of IR-induced IL10 expression, which reaccumulated in the presence of exogenous NO donor. In addition to L-NAME, the guanylyl cyclase inhibitors ODQ and thrombospondin-1 also abated IR-induced IL10 expression in Jurkat T cells and ANA-1 macrophages, which further suggests that the immunosuppressive effects involve eNOS. Moreover, cytotoxic Th1 cytokines, including IL2, IL12p40, and IFNγ, as well as activated CD8(+) T cells were elevated in tumors receiving post-IR L-NAME. Together, these results suggest that post-IR NOS inhibition improves radiation tumor response via Th1 immune polarization within the tumor microenvironment.
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland. ridnourl@mail.nih.gov.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Ridnour
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Robert Y S
authors.initials: RY
authors.lastname: Cheng
authors.affiliation: Cancer Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Weiss
authors.affiliation: Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Sukhbir
authors.initials: S
authors.lastname: Kaur
authors.affiliation: Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: David R
authors.initials: DR
authors.lastname: Soto-Pantoja
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Debashree
authors.initials: D
authors.lastname: Basudhar
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Heinecke
authors.affiliation: Cancer Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland.
authors.forename: C Andrew
authors.initials: CA
authors.lastname: Stewart
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: William
authors.initials: W
authors.lastname: DeGraff
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Anastasia L
authors.initials: AL
authors.lastname: Sowers
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Angela
authors.initials: A
authors.lastname: Thetford
authors.affiliation: Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: Aparna H
authors.initials: AH
authors.lastname: Kesarwala
authors.affiliation: Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: David D
authors.initials: DD
authors.lastname: Roberts
authors.affiliation: Cancer Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland.
authors.forename: Howard A
authors.initials: HA
authors.lastname: Young
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: James B
authors.initials: JB
authors.lastname: Mitchell
authors.affiliation: Cancer Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Trinchieri
authors.affiliation: Cancer Inflammation Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Wiltrout
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland.
authors.forename: David A
authors.initials: DA
authors.lastname: Wink
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011836:Radiation Tolerance / Q000187:drug effects*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D011838:Radiation-Sensitizing Agents; D019001:Nitric Oxide Synthase