GSE210101
BET inhibitors target the SCLC-N subtype of small-cell lung cancer by blocking NEUROD1 transactivation
Small cell lung cancer can be divided into several molecular subtypes based on the expression of four master transcription factors (ASCL1, NEUROD1, POU2F3, and YAP1). These master factors have not been directly druggable, and we hypothesized that targeting their transcriptional coactivator(s) could provide an alternative approach. Here, we identify that BET bromodomain proteins physically interact with NEUROD1 and function as transcriptional coactivators. Using CRISPR knockout and ChIP-seq, we demonstrate that NEUROD1 plays a critical role in defining the landscapes of BET bromodomain proteins in the SCLC genome. Targeting BET bromodomain proteins by BET inhibitors leads to broad suppression of the NEUROD1-target genes, especially those associated with superenhancers, and reduces SCLC growth in vitro and in vivo. LSAMP, a membrane protein in the IgLON family, was identified as one of the NEUROD1-target genes mediating BET inhibitor sensitivity in SCLC. Altogether, our study reveals that targeting transcriptional coactivators could be a novel approach to blocking the master transcription factors in SCLC for therapeutic purposes. The goals for this part of the study were: 1) to identify the NEUROD1 target genes in the SCLC-N subtype small cell lung cancer. To this end, we knocked out NEUROD1 in H446 cells (SCLC-N subtype) by CRISPR and assessed gene expression alterations in three knockout and three control clones. An integrated analysis of the RNA-seq data and the NEUROD1 ChIP-seq data was performed to identify the NEUROD1 target genes; 2) to assess how NEUROD1 knockout affects the response to JQ1 (a BET inhibitor). Overall design: Comparative gene expression profiling analysis of RNA-seq data was performed between H446 NEUROD1-KO derivatives (#297 cl. 12, cl. 15, and cl.2-1) and the control clones (NTgRNA cl.3, cl.10, and cl.13) following treatment of JQ1 (1µM; 24 hrs) or DMSO. Each sample had three biological replicates.