0 0 1 300 1716 University of Gothenburg 14 4 2012 14.0 Normal 0 false false false SV JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:SV;} Mutations leading to Ras gene activation are important contributors to myeloid leukemogenesis. Kras is one of three homologues of the Ras family, and oncogenic Kras is frequently found in monocytic forms of acute myeloid leukemia (AML), chronic myeloid leukemia (CML) and myeloproliferative diseases (MPD). Earlier studies show that excessive amounts of reactive oxygen species (ROS) are produced in Kras-mutated myeloid malignancies. Myeloid cells, including Kras-mutated leukemic cells, express the ROS-generating enzyme NOX2. Relatively little is known about the impact of ROS formation, in particular NOX2-derived ROS formation, on leukemogenesis. Mice where oncogenic Kras was induced in hematopoietic cells of LSL-KrasG12D and Mx1-Cre double transgenic mice with ensuing myeloproliferation were treated with a histamine H2-receptor selective NOX2 inhibitor, Nα -methyl histamine (NMH) to assess whether NOX2 is a feasible therapeutic target in Kras-driven leukemia. Spleens of diseased Kras mice were infiltrated with mature CD11b+Gr1+ myeloid cells that expressed NOX2 and produced ROS. The NOX2-dependent formation of ROS in CD11b+Gr1+ cells was inhibited by NMH. In vivo administration of NMH delayed the development of myeloproliferative disease and significantly prolonged survival of Kras mice (p=0.003). In contrast, treatment with NMH did not alter the survival of mice when Kras expression was induced in hematopoietic cells of NOX2-deficient mice that did not produce ROS (Nox2-/-, LSL-KrasG12D and Mx1-Cre triple transgenic mice). In Kras-mutated Nox+/+ mice, but not in Kras-mutated Nox-/- mice, the in vivo administration of NMH entailed diminished ROS levels and reduced oxidative stress as reflected by reduced DCFDA and anti-8 Hydroxyguanosine staining. We propose that NOX2-derived ROS in Kras-mutated hematopoetic cells mediate genomic instability that may contribute to the progression of leukemia. Strategies to target NOX2 should be further evaluated in Ras-mutated hematopoietic cancer. <!–EndFragment–>

Citation Format: Ebru Aydin, Alexander Hallner, Hanna Grauers Wiktorin, Anna Staffas, Kristoffer Hellstrand, Anna Martner. NOX2 inhibition reduces oxidative stress and prolongs survival of mice with Kras induced myeloproliferative disease [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 441.