Zwijnenburg, D. A. | bioRxiv Science

bioRxiv2021

An immature subset of neuroblastoma cells synthesizes retinoic acid and depends on this metabolite

Neuroblastoma is a pediatric tumor of the adrenergic sympathetic lineage. Most high risk neuroblastoma go in complete clinical remission by chemotherapy, which is subsequently complemented by retinoic acid (RA) maintenance therapy. However, by unresolved mechanisms most tumors ultimately relapse as therapy-resistant disease. Neuroblastoma cell lines were recently found to include, besides lineage committed adrenergic (ADRN) tumor cells, also immature mesenchymal (MES) tumor cells. Here, we report that MES-type cells synthesize RA and require this metabolite for proliferation and motility. MES cells are even resistant to RA in vitro. MES cells appear to resemble Schwann Cell Precursors (SCP), which are motile precursors of the adrenergic lineage. MES and SCP cells express shared RA-synthesis and RA-target genes. Endogenous RA synthesis and RA resistance thus stem from normal programs of lineage precursors that are maintained in an immature tumor cell fraction. These cells are fully malignant in orthotopic patient-derived xenograft models and may mediate development of drug-resistant relapses.

cancer biology↗

bioRxiv2020

Modulation of macrophage inflammatory function through selective inhibition of the epigenetic reader protein SP140

Speckled 140 KDa (SP140) is a nuclear body protein, mainly expressed in immune cells, which contains multiple domains suggestive of an epigenetic reader function; namely a bromodomain, a PHD domain and a SAND domain. Single nucleotide polymorphisms and epigenetic modifications in the SP140 locus have been linked to autoimmune and inflammatory diseases including Crohns disease (CD). However, little is known about the cellular function of SP140; this is due in part to the fact that, unlike for other many other epigenetic proteins, no small molecule inhibitors have been available to investigate the biological role of SP140. We report the discovery of the first small molecule SP140 inhibitor (GSK761) and utilize this to elucidate SP140 function in innate immune cells. We show that SP140 is highly expressed in CD68+ CD mucosal macrophages and in in vitro-generated inflammatory macrophages. SP140 inhibition through GSK761 reduced monocyte differentiation into inflammatory macrophages and lipopolysaccharide (LPS)-induced inflammatory activation, whilst inducing the generation of CD206+ regulatory macrophages that mark anti-TNF remission induction in CD patients. ChIP-seq analyses revealed that SP140 preferentially occupies transcriptional start sites (TSS) in inflammatory macrophages, with enrichment at gene loci encoding pro-inflammatory cytokines/chemokines and inflammatory pathways. GSK761 specifically reduced SP140 binding and thereby expression of SP140-dependent downstream inflammatory genes. Notably, in CD14+ macrophages isolated from CD intestinal-mucosa, GSK761 inhibited the spontaneous expression of cytokines, including TNF. Together, this study identifies SP140 as a druggable epigenetic reader and therapeutic target for CD.

immunology↗