TTN-AS1 delivered by gastric cancer cell–derived exosome induces gastric cancer progression through in vivo and in vitro studies

Extracellular communication within the tumor microenvironment exerts critical functions in tumor progression. Moreover, exosomes are capable of packaging into long non-coding RNAs (lncRNAs) to regulate extracellular communication. We tried to discuss the role of exosomal lncRNA TTN-AS1 and its molecular mechanism on gastric cancer (GC) progression. Bioinformatics analysis depicted increased TTN-AS1 in GC which shared correlation with poor prognosis. Clinical tissue and cellular experiments also confirmed the elevation of TTN-AS1 in GC tissues and cells. GC cell (AGS)–derived Exo could be uptake by NCI-N87 cells to induce malignant features of GC cells. Functionally, TTN-AS1 could upregulate ZEB1 expression by binding to miR-499a-5p. In addition, in vitro experiments demonstrated that ZEB1 targeted and activated CDX2 transcription and promoted CDX2 expression; silencing CDX2 inhibited malignant phenotypes of AGS and NCI-N87 cells. Furthermore, Exo-TTN-AS1 promoted GC cell growth and migration by promoting CDX2 expression. Exosomal TTN-AS1 from GC cells could also promote metastasis of GC in vivo. In conclusion, our findings provided evidence describing that exosomes derived from GC cells transferred TTN-AS1 to GC cells, which aggravate GC through the miR-499a-5p/ZEB1/CDX2 axis. Graphical Abstract 1. Exo derived from GC cells promotes the growth and metastasis of GC cells by carrying TTN-AS1. 2. TTN-AS1 acts as a ceRNA to adsorb miR-499a-5p to regulate the expression of ZEB1. 3. ZEB1 targets and activates CDX2 transcription. 4. GC cell-derived Exo-TTN-AS1 enhances the growth and metastasis of GC cell xenografts in vivo.