Abstract 3515: RRx-001: A double action systemically non-toxic epigenetic agent for cancer therapy

Abstract

RRx-001 (also known as ABDNAZ, 1-bromoacetyl-3,3-dinitroazetidine) is a novel aerospace-derived compound that demonstrated anticancer activity in the absence of systemic toxicities in a recent phase I clinical trial and is now in phase II studies. With a highly energetic heterocyclic scaffold, RRx-001 generates reactive oxygen species (ROS) and nitric oxide (NO), modulates intracellular redox status, and triggers caspase-independent apoptosis in cancer cells. Here we showed that RRx-001 as a single chemical entity regulates at least two epigenetic processes, histone acetylation and DNA demethylation. Specifically, RRx-001 at its therapeutic concentrations (0.5-5 μM) significantly decreased global DNA methylation, i.e., 5-methylcytosine levels, in SCC VII tumor cells as determined by ELISA. Consistently, treatment of SCC VII cells with 0.5-5 μM RRx-001 significantly decreased Dnmt1 and Dnmt3a protein expression in a dose- and time-dependent manner as determined by Western blots. In addition, global methylation profiling using Illumina Infinium HumanMethylation450 BeadChip® identified differentially methylated genes in SCC VII cells treated with 0.5, 2, and 5 μM RRx-001 compared to control cells. Of 111 genes demethylated by RRx-001 identified using GenomeStudio software, methylation levels of 3 genes (FAM20C, STON1-GTF2A1L and TRIAP1) were decreased by at least 2-fold across all three concentrations of RRx-001. Validation of these changes by pyrosequencing is underway. Pathway enrichment analysis by IPA suggested that RRx-001 demethylated genes involved in hepatic fibrosis, G protein signaling, leucine degradation and remodeling of epithelial adherens junctions. Moreover, RRx-001 at 2 μM significantly increased global acetylated histone H3 and H4 levels in SCC VII cells after 24 hour treatment as determined by a fluorometric assay, suggesting that RRx-001 regulates global acetylation in cancer cells. Western blot analysis also showed significant increases in acetylated histone H3 and H4 levels in SCC VII cells in a dose and time-dependent manner after RRx-001 treatment. Taken together, our results demonstrated that, in contrast to the traditional “one drug one target” paradigm, RRx-001 has multi(epi)target features, which contribute to its anticancer activity.

Citation Format: Hongjuan Zhao, Shoucheng Ning, Jan Scicinski, Bryan Oronsky, Susan Knox, Donna M. Peehl. RRx-001: A double action systemically non-toxic epigenetic agent for cancer therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3515. doi:10.1158/1538-7445.AM2015-3515