Endogenous Gastric-Resident Mesenchymal Stem Cells Contribute to Formation of Cancer Stroma and Progression of Gastric Cancer

BACKGROUND Carcinoma-associated fibroblasts (CAFs) contribute to carcinogenesis and cancer progression, although their origin and role remain unclear. We recently identified and investigated the in situ identity and implications of gastric submucosa-resident mesenchymal stem cells (GS-MSCs) in the progression of gastric carcinogenesis. METHODS We isolated GS-MSCs from gastric submucosa using hydrogel-supported organ culture and defined their identity. Isolated cells were assessed in vitro by immunophenotype and mesengenic multipotency. Reciprocal interactions between GS-MSCs and gastric cancer cells were evaluated. To determine the role of GS-MSCs, xenografts were constructed of gastric cancer cells admixed with or without GS-MSCs. RESULTS Isolated cells fulfilled MSCs requirements in regard to plastic adherence, stromal cell immunophenotype, and multipotency. We demonstrated a paracrine loop that gastric cancer cells enhanced the migration, proliferation, and differentiation of GS-MSCs; additionally, GS-MSCs promoted the proliferation of gastric cancer cell in vitro. Xenograft experiments showed that GS-MSCs significantly promoted cancer growth and angiogenesis. GS-MSCs that integrated into gastric cancer became not only CAFs but also rarely endothelial cells which contributed to the formation of cellular and vascular cancer stroma. CONCLUSIONS Endogenous GS-MSCs play an important role in gastric cancer progression.