7. Lien Nguyen, PhD

A key hallmark of cancer is ‘unlocking phenotypic plasticity,’ where cells gain the ability to evade or escape terminal differentiation. This hallmark is especially prominent in cancers of the nervous system, where progenitor cells rely on precise spatial and temporal cues to generate and maintain diverse cell types. Differentiation therapy, which reactivates endogenous differentiation programs, offers a promising and less toxic approach to cancer treatment. Particularly, tumor cell heterogeneity in neuroblastoma, a pediatric cancer originating from neural crest-derived progenitor cells, poses a major clinical challenge. Unlike adrenergic (ADRN) neuroblastoma cells, mesenchymal (MES) cells are resistant to chemotherapy and retinoid therapy, therefore significantly contributing to relapses and treatment failures. Previous research suggested that overexpression or activation of miR-124, a neurogenic microRNA with tumor suppressor activity, can induce differentiation in retinoic acid-resistant neuroblastoma cells. Leveraging our established screen for miRNA-modulatory small molecules, we validated PP121, a dual inhibitor of tyrosine and phosphoinositide kinases, as a robust inducer of miR-124. A combination of PP121 and BDNF-activating bufalin synergistically arrested proliferation, induced differentiation, and maintained the differentiated state of MES SK-N-AS cells for 8 weeks. RNA-seq and deconvolution analyses revealed a collapse of the ADRN core regulatory circuitry (CRC) and the emergence of novel CRCs associated with chromaffin cells and Schwann cell precursors. Using a similar protocol, we differentiated and maintained MES neuroblastoma GI-ME-N, SH-EP, KP-N-SI9s (MYCN non-amplified), and CHP-212 (MYCN amplified) cell lines, as well as glioblastoma LN-229 and U-251 cell lines, for over 16 weeks. In conclusion, our novel protocol offers a promising treatment for therapy-resistant cancers of the nervous system. Our ongoing research focuses on uncovering the epigenetic mechanisms driving differentiation and evaluating the efficacy of the drug combination in animal models.