Abstract 1902: Potential role of DYRK family kinases in harmine-induced apoptosis in neuroblastoma

The purpose of this study was to determine the effect of the natural product Harmine in human neuroblastoma (NB). NB is an early childhood malignancy arising from the developing peripheral nervous system. In up to 25% of cases MYCN gene amplification is correlated to high tumor stage and poor patient prognosis. High stage NB relapses frequently in spite of multimodal therapy and is then virtually untreatable. There is a clear need for specific, novel therapeutics. Harmine is a tricyclic β-carboline alkaloid from the harmal plant with cytostatic and cytotoxic effects on tumor cells. It is capable of blocking the activity of mitogen activate protein kinase (MAPK) and the dual specificity tyrosine-phosphorylation-regulated kinase (DYRK) family proteins. These kinases inhibit apoptosis and encourage proliferation. Four human NB cell lines were used to study the effects of Harmine treatment: SK-N-BE(2)-C and KELLY (MYCN amplified) as well as SK-N-AS and SK-N-FI (MYCN single copy). Molecular interaction models of Harmine bound to DYRK family kinases were generated by computational docking using x-ray structures. The anti-cancer properties of Harmine were analyzed by real-time cell viability assays, in a dose-dependent manner, over a 72 hour period. The IC 50 values were 169.9, 170.8, and 791.7 μM for SK-N-BE(2)-C, KELLY, and SK-N-FI, respectively, after 72 hours. Apoptosis assays for caspase activation, PARP cleavage, and annexin V induction, were performed using Western blot and flow cytometry. NB cell line exposure to 100 μM Harmine resulted in caspase-3/7 and caspase 9 activation, PARP cleavage, and annexin V-positive stained cells as early as 24 hours after treatment, indicating apoptosis induction. These results led us to investigate the clinical correlations of DYRK family gene expression in NB tumors. The patient results support our hypothesis that Harmine induces NB cell death through a cellular mechanism that involves DYRK family kinases and triggers caspase-mediated apoptosis. Citation Format: Katie L. Uhl, Chad R. Schultz, Dirk Geerts, Andre S. Bachmann. Potential role of DYRK family kinases in harmine-induced apoptosis in neuroblastoma [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 1902.