Selective HDAC1/HDAC2 Inhibitors Induce Neuroblastoma Differentiation

•Designed a complex gene expression signature for neuroblastoma differentiation•Screened a diversity-oriented synthesis library for signature induction•Identified a class I HDAC inhibitor (HDAC1 > 2 > 3) as a differentiating agent•Demonstrated in vitro efficacy of HDAC1/2 inhibitor + cisRA combination treatment

SummaryWhile cytotoxic chemotherapy remains the hallmark of cancer treatment, intensive regimens fall short in many malignancies, including high-risk neuroblastoma. One alternative strategy is to therapeutically promote tumor differentiation. We created a gene expression signature to measure neuroblast maturation, adapted it to a high-throughput platform, and screened a diversity oriented synthesis-generated small-molecule library for differentiation inducers. We identified BRD8430, containing a nine-membered lactam, an ortho-amino anilide functionality, and three chiral centers, as a selective class I histone deacetylase (HDAC) inhibitor (HDAC1 > 2 > 3). Further investigation demonstrated that selective HDAC1/HDAC2 inhibition using compounds or RNA interference induced differentiation and decreased viability in neuroblastoma cell lines. Combined treatment with 13-cis retinoic acid augmented these effects and enhanced activation of retinoic acid signaling. Therefore, by applying a chemical genomic screening approach, we identified selective HDAC1/HDAC2 inhibition as a strategy to induce neuroblastoma differentiation.