Abstract LB-041: Targeting AKT2 and ERK decline the drug/radiation resistance in neuroblastoma

Abstract

Abstract Introduction: Neuroblastoma is highly heterogeneous, containing cancer cells with very different molecular characteristics. Activation of distinct signal transduction pathways can induce neuroblastoma cells to transform cells with neuronal, chromaffin, or schwannian phenotypes, further supporting the existence of cancer stem cells. We previously demonstrated that AKT2 plays critical roles in regulation of neuroblastoma tumorigenesis. Here we hypotheize that targeting AKT2 would block the signal transduction pathways enhanced in drug/radiation resistant neuroblastoma cancer stem cells. Methods: We generated cisplatin (CDDP) resistant and radiation (Rad) resistant neuroblastoma cells under the treatment or irradiation with a concentration of IC 50 of CDDP and 137Cs irradiator respectively. Cell viability was assessed with CCK-8 kit daily. Extreme limiting dilution analysis (ELDA) was performed for quantification of tumor sphere formation. Immunoblotting detected the expression of stem cell markers CD133, Sox2, ALDH, ALDH, Nestin, Oct4 and Nanog, as well as survival signaling pathway key molecules AKT2, MAPK and P38 MAPK. Results: We founded that two important cell proliferation and survival signaling pathways mTOR, downstream of AKT2 and MAPK enhanced in CDDP-resistant and Rad-resistant neuroblastoma cells. Blocking these two pathways with chemical inhibitors, CCT128930, AKT2 selective inhibitor and PD98059, MEK inhibitor decreased cell proliferation, angiogenesis, cell migration and soft agar conoly growth in these resistant cells. We further demonstrated that these resistant cells showed higher capacity of sphere-forming with increased expression of stem cell markers CD133, Sox2, ALDH, ALDH, Nestin, Oct4 and Nanog. Improtantly, the sphere formation of these resistant cells is sensitive to the inhibitors of AKT2 and MAPK. Conclusion: Our results suggest that selected CDDP-resistant and radiation-resistant neuroblastoma cells might serve as an useful tool to improve understanding of the molecular mechanisms of therapeutic resistance and develop more effective novel treatment strategies, and further to reaching better clinical outcomes of patients with neuroblastoma. Citation Format: Kwang Woon Kim, Dai Chung, Jingbo Qiao, Julia Kim, Camille Poewers, Hernan Correa, Kyungho Park, Sora Lee. Targeting AKT2 and ERK decline the drug/radiation resistance in neuroblastoma [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 LB-041.