Abstract B29: ASIC1 impacts Notch signaling pathway in the neuronal differentiation of neuroblatoma

Abstract

Abstract Background: Neuroblastoma arises when neuroblasts of the sympathetic nervous system fail to undergo proper differentiation. The Notch signaling pathway is critical for cell fate determination or function. In neurons, it has been shown that up regulation of Notch activity either inhibited neurite extension or caused retraction of neurites. Conversely, inhibition of Notch1 signaling facilitated neurite extension [1]. Acid-sensing ion channels (ASICs) are a family of proton-gated cation channels. Recent studies have suggested their role in synaptic plasticity, learning and memory. A good correlation has been found between ASIC1a expression and spine density [2] suggesting that ASIC1a plays an important role in spine morphogenesis, maintenance and remodeling. The underlying mechanism however remains elusive. We hypothesize that ASIC1 regulates neurite growth through Notch signaling in neuroblastoma. Methods: 1) We employed proteomic approach and pathway analysis to examine changes in Notch signaling by ASIC gene deletion. 2) We used quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot to determine changes of expression levels of Notch1 and its target genes in cerebral cortex by ASIC1 deletion and in primary cultures of cortical neurons by ASIC1a inhibition or knockdown. 3) We determined the effects of ASIC1a on neurite growth in a mouse neuroblastoma cell line, NS20Y cells by down regulating ASIC1a expression with shRNA or inhibiting ASIC1a function with PcTX, a specific pharmacological inhibitor. 4) We determined the effects of DAPT, a Notch signal inhibitor on neuronal differentiation in NS20Y cells. Results: 1) ASIC1a-/- mice showed significantly reduced expression of Notch1 protein and its target genes such as Hey2 and Survivin. 2) Down regulation of ASIC1a in NS20Y cells with shRNA inhibits CPT-cAMP induced neurite growth, while over expression of ASIC1a promotes its growth. 3) Down regulation of ASIC1 by shRNA increased Notch1 and its target gene Survivin in NS20Y cells. 4) DAPT, an inhibitor of Notch significantly protects inhibition of CPT-cAMP induced neurite extension by down-regulation of ASIC1 in NS20Y cells. Conclusion: These data indicate that Notch1 signaling may be required for ASIC1 mediated change in neurite growth and neuronal differentiation of neuroblastoma. Promoting neural differentiation of neuroblastoma in vitro provides insight into potential clinical applications in the treatment of patients with neuroblastoma (This work is supported by R01NS066027, NIMHD S21MD000101, and U54NS08932) Citation Format: Mingli Liu, Koichi Inoue, An Zhou, Zhigang Xiong. ASIC1 impacts Notch signaling pathway in the neuronal differentiation of neuroblatoma. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B29.