Abstract 5583: Small molecule mediated restoration of PAX3 inhibits malignant features in neuroblastoma cells

Abstract Neuroblastoma is the most common extracranial childhood tumor diagnosed in the first year of life. A complete molecular understanding of neuroblastoma is necessary to identify novel therapeutic targets for their management, particularly for high-risk groups. Many transcription factors play an essential role during development, and their expression is restricted to specific cells/tissues after development is completed. PAX3 belongs to the paired box family of transcription factors involved in various cellular processes like cellular proliferation, migration, lineage specificity, and differentiation. Reexpression of PAX3 is reported in various childhood tumors, including neuroblastoma; however, its role in tumor development is contradicting. Here, we investigated the contribution of PAX3 in neuroblastoma in a panel of neuroblastoma cell lines and identified a PAX3-targeted small molecule activator that can alter tumorigenic phenotypes. Specifically, we have analyzed the PAX3 mRNA, protein, subcellular localization, and its isoform expression in various neuroblastoma cell lines and correlated the results with their tumorigenic potential. Our results showed that most of the PAX3 expressed in these cells are PAX3a/b isoforms that lack PAX3’s transactivation domain. Further, we have observed the depletion of PAX3a/b isoforms could not alter the malignant properties of neuroblastoma cells. Interestingly, the ectopic PAX3 expression in the absence of PAX3a/b isoform in these cells inhibited malignant phenotypes including growth, colony formation and migration potentials. Furthermore, we have identified potential small molecule PAX3 activators from our previous small molecule screening. PAX3 activators effectively inhibited in vitro malignant properties of neuroblastoma cell lines. Our results revealed that tumor inhibitory properties of transcriptionally active PAX3 and its reactivation using small molecules have great potential in inhibiting neuroblastoma development. Citation Format: Abinayaselvi Murugan, Sowndharyalatha Balasubramanian, Narenkumar Muralidharan, Ann Mary Alappat Sanjive, Prabhuraj Andiperumal Raj, Mathivanan Jothi. Small molecule mediated restoration of PAX3 inhibits malignant features in neuroblastoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5583.