SATB2 promotes EMT-like, invasive, and endothelial tube-promoting phenotypes with the involvement of ZEB1 in 8305C anaplastic thyroid cancer cells

Anaplastic thyroid cancer (ATC) exhibits marked dedifferentiation, rapid invasion, and limited therapeutic responsiveness. This study investigated associations between SATB2, ZEB1, EMT-like changes, invasion, short-term vemurafenib response, and endothelial tube-promoting activity in 8305C cells as an in vitro proof-of-concept model. SATB2 was overexpressed or silenced, followed by reciprocal ZEB1 manipulation to assess its contribution to SATB2-associated phenotypes. Expression was assessed by quantitative real-time PCR, Western blotting, and immunofluorescence. ChIP-qPCR examined SATB2 enrichment at a selected ZEB1 promoter region. Transwell assays assessed invasion, and Western blotting evaluated EMT- and angiogenesis-associated proteins. Short-term vemurafenib responses were measured using CCK-8 concentration–response assays. Supernatant VEGFA concentrations were determined by ELISA, and conditioned media were tested in HUVEC tube-formation assays. SATB2 manipulation produced concordant changes in ZEB1 mRNA and protein expression. ChIP-qPCR demonstrated significant SATB2 enrichment at the examined ZEB1 promoter region relative to IgG, indicating association without establishing direct transcriptional activation. SATB2 overexpression increased invasion, decreased E-cadherin, and increased Vimentin, VEGFA, and PDGF-BB expression; silencing produced opposite changes. SATB2 overexpression shifted the short-term vemurafenib concentration-response curve toward a higher IC50, whereas silencing shifted it toward a lower IC50. Reciprocal ZEB1 manipulation attenuated molecular and functional changes associated with SATB2 gain- or loss-of-function, supporting ZEB1 involvement. Conditioned medium from SATB2-overexpressing cells promoted HUVEC tube formation, which was attenuated by ZEB1 silencing. In 8305C cells, SATB2 was associated with ZEB1 expression, EMT-like remodeling, invasion, altered short-term vemurafenib response, and endothelial tube-promoting activity. Reciprocal ZEB1 manipulation supports its involvement in these phenotypes, but ChIP-qPCR does not establish direct SATB2-mediated transcriptional activation of ZEB1. Findings are limited to a single ATC cell-line model and require validation in additional experimental models.