Abstract 2967: Activity of G-quadruplex stabilizing small molecule that downregulates MYC and synergizes with Navitoclax in acute myeloid leukemia cells

Abstract

Abstract Acute Myeloid Leukemia (AML) is a malignancy of myeloid precursor cells that can occur when genomic changes alter expression of key genes, causing cells to resume an undifferentiated state and proliferate. Ongoing efforts have focused on developing therapies that specifically target the protein products of aberrantly expressed genes. However, many of the identified proteins are difficult to target because of structural challenges, protein overexpression, or mutations that confer resistance to therapy. A type of therapy that circumvents these issues is the use of small molecules that stabilize DNA secondary structures called G-quadruplexes, which are present in the promoters of many potential oncogenes, and have regulatory roles in their transcription. This study analyzes the activity of G-quadruplex stabilizing small molecule GQC-05 that has been shown to down-regulate MYC, which is commonly misregulated in AML. Treatment of MYC-expressing AML cell lines KG-1a, CMK and TF-1 with GQC-05 resulted in decreased expression of MYC mRNA and protein, with the effect more pronounced in KG-1a cells. GQC-05 treatment of the AML cells decreased cell viability, while increasing apoptosis and DNA damage. Combinational drug screening was performed to identify compounds that potentiated the anti-proliferative effects of GQC-05. Results from the screen identified the BCL-2 inhibitor Navitoclax as a compound that potentiated GQC-05 activity. Co-treatment with GQC-05 and Navitoclax showed synergistic effect on cell viability of AML cells as determined by Chou-Talalay analysis. Furthermore, co-treatment with Navitoclax did not affect the downregulation of MYC by GQC-05, but did increase apoptosis and DNA damage leading to rapid cytotoxicity. These results indicate that the G-quadruplex stabilizing small molecule GQC-05 may function more as a DNA damaging agent in AML cells and that combining GQC-05 with a Bcl-2/Bcl-XLinhibitor such as Navitoclax can result in increased cytotoxic activity. Citation Format: Justin J. Montoya, Megan A. Turnidge, Daniel H. Wai, David W. Lee, Apruvi Patel, Vijay Gokhale, Laurence J. Hurley, David O. Azorsa. Activity of G-quadruplex stabilizing small molecule that downregulates MYC and synergizes with Navitoclax in acute myeloid leukemia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2967.