Phenotypic switching is an emerging driver of cancer treatment resistance, yet early signals regulating this process remain unclear. Here, using longitudinal single-cell RNA sequencing, we mapped diff Show more
Phenotypic switching is an emerging driver of cancer treatment resistance, yet early signals regulating this process remain unclear. Here, using longitudinal single-cell RNA sequencing, we mapped differentiation trajectories in the LTL331 prostate adenocarcinoma patient-derived xenograft (PDX) model undergoing neuroendocrine prostate cancer (NEPC) transformation post castration. Our analyses identified a key differentiation node marked by epithelial-mesenchymal transition (EMT) and repressor element-1 silencing transcription factor (REST) downregulation driven by the CXCR4-LASP1-G9a-SNAIL axis. Mechanistically, CXCR4 activation promotes nuclear translocation of LASP1 that links G9a and SNAIL via SH3/proline-rich motif and LIM/SNAG domain interactions, enabling SNAIL-mediated REST repression via promoter E-box motifs. Inhibition of CXCR4 or G9a reversed LTL331R NEPC cells toward a luminal androgen receptor-active phenotype. CXCR4-targeted radioligands enabled both imaging and inhibition of NEPC tumors in vivo. These findings highlight the CXCR4-LASP1-G9a-SNAIL axis as a key regulator of epigenetic and transcriptional reprogramming in NEPC transdifferentiation and support its therapeutic targeting in aggressive NEPC. Show less
The regulation of cell migration is essential to animal development and physiology. Heparan sulfate proteoglycans shape the interactions of morphogens and guidance cues with their respective receptors Show more
The regulation of cell migration is essential to animal development and physiology. Heparan sulfate proteoglycans shape the interactions of morphogens and guidance cues with their respective receptors to elicit appropriate cellular responses. Heparan sulfate proteoglycans consist of a protein core with attached heparan sulfate glycosaminoglycan chains, which are synthesized by glycosyltransferases of the exostosin (EXT) family. Abnormal HS chain synthesis results in pleiotropic consequences, including abnormal development and tumor formation. In humans, mutations in either of the exostosin genes EXT1 and EXT2 lead to osteosarcomas or multiple exostoses. Complete loss of any of the exostosin glycosyltransferases in mouse, fish, flies and worms leads to drastic morphogenetic defects and embryonic lethality. Here we identify and study previously unavailable viable hypomorphic mutations in the two C. elegans exostosin glycosyltransferases genes, rib-1 and rib-2. These partial loss-of-function mutations lead to a severe reduction of HS levels and result in profound but specific developmental defects, including abnormal cell and axonal migrations. We find that the expression pattern of the HS copolymerase is dynamic during embryonic and larval morphogenesis, and is sustained throughout life in specific cell types, consistent with HSPGs playing both developmental and post-developmental roles. Cell-type specific expression of the HS copolymerase shows that HS elongation is required in both the migrating neuron and neighboring cells to coordinate migration guidance. Our findings provide insights into general principles underlying HSPG function in development. Show less