Abstract 507: Nitrogen oxides-derived immunotherapy: Revealing cryptic melanoma-specific immune targets

Abstract

Abstract Nitrogen oxides (NOx) can exert their relevant biological functions through two reversible molecular modifications: a) direct interaction with metals (nitrosation), and b) by interacting with thiols (s-nitrosylation); or irreversible modifications of aromatic amino acid residues such as tyrosine or phenylalanine (nitration). Any of these modifications have been demonstrated to affect the biological fate of the modified molecule or alter their functions. We have previously shown that these NOx-derived changes will trigger a myriad of modifications at the genetic, epigenetic and post-translational level in tumor cells resulting in a robust and effective therapeutic immune response against cancer cells. However, the molecular mechanisms and immune-related tumor targets remain elusive. Thus, we hypothesize that NOx-derived protein modifications (i.e., Tyrosine nitration) will differentially prime the immune system with otherwise subdominant antigens (cryptic) making them immune visible and triggering an effective anti-tumor immune response. We have tested this hypothesis using the well-characterized B16-C57BL/6 syngeneic and poorly immunogenic melanoma mouse model. NOx-modified and non-modified B16-F0 melanoma cell lysates were used to immunize naïve C57BL/6. Post-immunized sera was screened against SDS-PAGE resolved untreated B16-F0 lysates and human protein library micro array for differential recognition of immune cross-reactive of novel mouse and human melanoma targets by the mouse IgG fraction. Our results demonstrated the highly significant (p <0.0001) IgG-associated immune recognition of five cross-reactive novel melanoma targets (in relative affinity decreasing order): 1) Golgi reassembly stacking protein 1 (GORASP1), 2) ArfGAP w/GTPase domain-ankyrin repeat and PH domain 1 (AGAP1), 3) Microtubule-associated protein tau (MAPT), 4) Mitochondrial ribosomal protein L46 (MRPL46), and 5) Protocadherin beta 6 (PCDHB6). Currently, we are evaluating the significance and functional activity of the identified targets and their isolated/purified specific immune effector (IgG) counterparts. In addition, we are characterizing the potential molecular and immunological mechanisms that might lead to the use of these novel melanoma-specific immune targets as diagnostic/prognostic and/or immunotherapeutic tools. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 507. doi:1538-7445.AM2012-507