P01.06.B GLIOMA STEM CELLS REMODEL ASTROCYTES TO FACILITATE GBM PROGRESSION VIA EXOSOMAL ZNF16 ACTIVATED TGF-Β SIGNALING AXIS

Abstract BACKGROUND Tumor-associated astrocytes (TAAs) play crucial promoting roles during tissue remodeling of glioma stem cells (GSCs), however, molecular mechanisms regulating astrocytes transformation, as well as glioblastoma progression by TAAs have not been fully clarified. MATERIAL AND METHODS Normal human astrocytes (NHAs) were cultured in vitro and continuously treated with GSC-derived exosomes (GSC-exo). Cellular phenotypes of TAAs were analyzed, expression of TAAs associated markers TGF-β, CD44, and tenascin-C was assayed by Western blot. Bioinformatic prediction of upstream transcription factor of TGF-β was performed and validated by RT-PCR, dual-luciferase reporter assay. Cell-based assay of glioblastoma proliferation and chemo-resistance were performed through flow cytometric assay, Western blot and colony formation assay, respectively. A xenograft tumor model was applied to verify the role of exosomal ZNF16 activated TGF-β signaling axis in vivo. RESULTS Notably, under the influence of GSC-exo, NHAs undergo transformation into tumor-associated astrocytes (TAAs) within three days, expressing hallmark surface markers such as TGF-β, CD44, and Tenascin-C. The transcription factor zinc finger protein 16 (ZNF16) was directly bound to the TGF-β promoter region and enhanced TGF-β expression.This transformation was associated with upregulation of TGF-β in NHAs activated by GSCs exosomal ZNF16. TGF-β is a direct downstream target of ZNF16 in TAAs. Transformed TAAs exhibit morphological changes, enhanced proliferative and migrative capacities, as well as contributing to aggressiveness and chemo-resistance of glioblastoma. In vivo studies disclosed that targeting on GSC-exosomal ZNF16 or TGF-β can suppressive transformation of TAAs and inhibiting their tumor promoting role on glioblastoma progression. CONCLUSION Understanding the intricate mutual interactions between GSCs and astrocytes in glioblastoma microenvironment can shed light on new therapeutic strategy on disrupting GSCs-TAAs crosstalk against glioblastoma progression.