Project description:Transition between differentiation states in development occurs swift but the mechanisms leading to epigenetic and transcriptional reprogramming are poorly understood. The pediatric cancer neuroblastoma includes adrenergic (ADRN) and mesenchymal (MES) tumor cell types, which differ in phenotype, super-enhancers (SEs) and core regulatory circuitries. These cell types can spontaneously interconvert, but the mechanism remains largely unknown. Here, we unravel how a NOTCH3 intracellular domain reprogrammed the ADRN transcriptional landscape towards a MES state. A transcriptional feed-forward circuitry of NOTCH-family transcription factors amplifies the NOTCH signaling levels, explaining the swift transition between two semi-stable cellular states. This transition induces genome-wide remodeling of the H3K27ac landscape and a switch from ADRN SEs to MES SEs. Once established, the NOTCH feed-forward loop maintains the induced MES state. In vivo reprogramming of ADRN cells shows that MES and ADRN cells are equally oncogenic. Our results elucidate a swift transdifferentiation between two semi-stable epigenetic cellular states.
Project description:Gastric cancer (GC) stem cells (GCSCs) are characterized as high level of ALDH activity, however, the mechanisms of maintenance of high ALDH activity and stemness in GCSCs are largely unknown. Here, we report that KDM4C, a H3K9me2/3-demethylase, epigenetically regulates ALDH1A3 by histone demethylation and forms a feed-forward loop with ALDH1A3 to supports GS stemness. Ectopic expression of both KDM4C and ALDH1A3 promotes the properties of GCSCs, including spherogenecity, self-renewal, CD44 expression and ALDH activity; knockdown of anyone abolished the effect of each other. KDM4C directly binds to the promoter of ALDH1A3, leads to histone demethylation, thereby promoting ALDH1A3 transcription. Upregulated ALDH1A3 in turn transcriptionally upregulates KDM4C. Simultaneous inhibition of KDM4C and ALDH1A3 synergistically sensitizes GC sphere-derived cells to traditional chemotherapeutic drugs. The finding that upregulated ALDH1A3 promotes its own transcription via KDM4C-mediated epigenetic modification represents an important feed-forward mechanism for GCSCs to maintain stemness and promote tumourigenesis and our work thus suggests a novel therapeutic strategy for eradicating human GCSCs. To investigate the mechanisms underlying KDM4C promoting CG stemness, we identified the differentially expressed proteins (DEPs) between KDM4C-overexpressing and control AGS cells by iTRAQ-based quantitative proteomic analysis.
Project description:This SuperSeries is composed of the following subset Series: GSE29182: Identification of active microRNA/transcription factor feed-forward loops during human adipogenesis (mRNA) GSE29185: Identification of active microRNA/transcription factor feed-forward loops during human adipogenesis (miRNA) Refer to individual Series