Detachment-induced ETS1 drives anoikis resistance and metastasis through STX3-mediated PTEN ubiquitination in gastric cancer.

BACKGROUND: Anoikis resistance enables detached gastric cancer cells to survive during metastasis. However, the transcriptional mechanisms that sustain survival signaling under detachment stress remain incompletely understood. METHODS: Public transcriptomic and single-cell datasets, patient-derived gastric cancer tissues, and non-adherent culture models were used to evaluate detachment-associated molecular changes. Loss- and gain-of-function assays, apoptosis analysis, JC-1 staining, RNA-seq, CHX/MG132 assays, ubiquitination assays, CUT&Tag, luciferase reporter assays, IP-MS, rescue experiments, and lung colonization and peritoneal dissemination models were performed to define the underlying mechanism. RESULTS: Multi-omics analyses revealed that ETS1 was highly expressed in gastric cancer metastases and was induced by detachment stress. ETS1 promoted anoikis resistance and metastasis through PTEN ubiquitination, with PTEN knockdown restoring anoikis resistance and lung colonization after ETS1 depletion. Further mechanistic analysis showed that ETS1 bound to and activated the STX3 promoter. STX3 facilitated PTEN ubiquitination and destabilization, and this effect was markedly attenuated by depletion of the E3 ubiquitin ligase TRIM21. STX3 knockdown blocked ETS1-driven anoikis resistance and peritoneal dissemination. CONCLUSIONS: These findings identify a detachment-driven mechanism in which ETS1 transcriptionally activates STX3, which facilitates TRIM21-dependent PTEN ubiquitination and destabilization, thereby sustaining AKT signaling, anoikis resistance and gastric cancer metastasis.