Bone marrow-derived stromal cells are associated with gastric cancer progression

Background: The aim of this study was to clarify the role of bone marrow-derived stromal cells (BM-SCs) expressing CD271 in the development of gastric cancer. Methods: The effect of human BM-SCs on the proliferation and motility of six gastric cancer cell lines, OCUM-2M, OCUM-2MD3, OCUM-12, KATO-III, NUGC-3, and MKN-74, was examined. CD271 expression levels in BM-SCs were analysed by flow cytometry. We also generated a gastric tumour model by orthotopic inoculation of OCUM-2MLN cells in mice that had received transplantation of bone marrow from the CAG-EGFP mice. The correlation between the clinicopathological features of 279 primary gastric carcinomas and CD271 expression in tumour stroma was examined by immunohistochemistry. Results: Numerous BM-SCs infiltrated the gastric tumour microenvironment; CD271 expression was found in similar to 25% of BM-SCs. Conditioned medium from BM-SCs significantly increased the proliferation of gastric cancer cell lines. Furthermore, conditioned medium from gastric cancer cells significantly increased the number of BM-SCs, whereas migration of OCUM-12 and NUGC-3 cells was significantly increased by conditioned medium from BM-SCs. CD271 expression in stromal cells was significantly associated with macroscopic type-4 cancers, diffuse-type tumours, and tumour invasion depth. The overall survival of patients (n = 279) with CD271-positive stromal cells was significantly worse compared with that of patients with CD271-negative stromal cells. This is the first report of the significance of BM-SCs in gastric cancer progression. Conclusions: Bone marrow-derived stromal cells might have an important role in gastric cancer progression, and CD271-positive BM-SCs might be a useful prognostic factor for gastric cancer patients.