Hypoxia-induced LAMB2-enriched extracellular vesicles promote peritoneal metastasis in gastric cancer via the ROCK1-CAV1-Rab11 axis.

Peritoneal metastasis is one of the most common risk factors contributing to the poor prognosis of gastric cancer. We previously reported that extracellular vesicles from gastric cancer cells could facilitate peritoneal metastasis. However, their impact on gastric cancer-induced peritoneal metastasis under hypoxic conditions remains unclear. This study aims to elucidate how hypoxia-resistant gastric cancer cell-derived extracellular vesicles affect the peritoneal metastasis of normoxic gastric cancer cells. Proteomic analysis revealed elevated levels of Caveolin1 and Laminin β2 in hypoxia-resistant gastric cancer cells and their corresponding extracellular vesicles. Importantly, Caveolin1 was found to play a central role in mediating Laminin β2 sorting into extracellular vesicles derived from hypoxia-resistant gastric cancer cells, and subsequently, extracellular vesicle-associated Laminin β2 promoted peritoneal metastasis in normoxic gastric cancer cells by activating the AKT pathway. Further investigation confirmed that Caveolin1 activation by Rho-related Coiled-coil kinase 1-mediated phosphorylation of Y14 residue is a key factor facilitating Laminin β2 sorting into extracellular vesicles. Moreover, Y14 phosphorylated- Caveolin1 enhanced Laminin β2 sorting by activating Rab11. Finally, our study demonstrated that a combined assessment of plasma extracellular vesicle-associated Caveolin1 and extracellular vesicle-associated Laminin β2 could provide an accurate predictive tool for peritoneal metastasis occurrence in gastric cancer.