NOS inhibition modulates immune polarization and improves radiation-induced tumor growth delay

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 NG-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 IFNg, 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

Molecular Mechanisms of Nitric Oxide in Cancer Progression, Signal Transduction, and Metabolism

Significance: Cancer is a complex disease, which not only involves the tumor but its microenvironment comprising different immune cells as well. Nitric oxide (NO) plays specific roles within tumor cells and the microenvironment and determines the rate of cancer progression, therapy efficacy, and patient prognosis.Recent Advances: Key understanding of the processes leading to dysregulated NO flux within the tumor microenvironment over the past decade has provided better understanding of the dichotomous role of NO in cancer and its importance in shaping the immune landscape. It is becoming increasingly evident that nitric oxide synthase 2 (NOS2)-mediated NO/reactive nitrogen oxide species (RNS) are heavily involved in cancer progression and metastasis in different types of tumor. More recent studies have found that NO from NOS2+ macrophages is required for cancer immunotherapy to be effective.Critical Issues: NO/RNS, unlike other molecules, are unique in their ability to target a plethora of oncogenic pathways during cancer progression. In this review, we subcategorize the different levels of NO produced by cells and shed light on the context-dependent temporal effects on cancer signaling and metabolic shift in the tumor microenvironment.Future Directions: Understanding the source of NO and its spaciotemporal profile within the tumor microenvironment could help improve efficacy of cancer immunotherapies by improving tumor infiltration of immune cells for better tumor clearance

Synthesis and chemical and biological comparison of nitroxyl- and nitric oxide-releasing diazeniumdiolate-based aspirin derivatives

none14openBasudhar D.; Bharadwaj G.; Cheng R.Y.; Jain S.; Shi S.; Heinecke J.L.; Holland R.J.; Ridnour L.A.; Caceres V.M.; Spadari-Bratfisch R.C.; Paolocci N.; Velazquez-Martinez C.A.; Wink D.A.; Miranda K.M.Basudhar, D.; Bharadwaj, G.; Cheng, R. Y.; Jain, S.; Shi, S.; Heinecke, J. L.; Holland, R. J.; Ridnour, L. A.; Caceres, V. M.; Spadari-Bratfisch, R. C.; Paolocci, N.; Velazquez-Martinez, C. A.; Wink, D. A.; Miranda, K. M