Liquid tumor microenvironment enhances WNT signaling pathway of peritoneal metastasis of gastric cancer

Gastric cancer remains one of the most prevalent tumors worldwide and peritoneal metastasis is responsible for approximately 60% death in advanced gastric cancer patients. However, the underlying mechanism of peritoneal metastasis is poorly understood. We have established organoids derived from malignant ascites (MA) of gastric cancer patient and noticed that MA supernatant could strongly increase colony formation of organoids. We realized the interaction between exfoliated cancer cells (ECCs) and tumor microenvironment contributes to peritoneal metastasis. We designed a medium component control test which proved that exosomes derived from MA could not enhance the growth of organoids. Using western blotting assay as well as Immunofluorescence and confocal imaging, our data showed WNT signaling pathway is upregulated by high concentration of WNT ligands (wnt3a and wnt5a), which was verified by ELISA. Conversely, suppressing WNT signaling pathway diminishes the growth promoting function of MA supernatant. This result implicates WNT signaling pathway as a potential therapeutic target for peritoneal metastasis of gastric cancer.