Mesenchymal Stromal Cells Promote Tumor Progression in Fibrosarcoma and Gastric Cancer Cells

BACKGROUND: Extensive evidence has accumulated regarding the role of mesenchymal stromal cells (MSCs) in tumor progression, but the exact effects and mechanisms underlying this role remain unclear. We investigated the effects of MSC-associated tumor progression in MSC-sarcoma models and a gastric cancer metastatic model. METHODS: We conducted an in vitro growth kinetics assay and an in vivo tumor progression assay for sarcoma cells and gastric cancer cells in the presence or absence of MSCs. RESULTS: MSC-cocultured human fibrosarcoma cells (HT1080) showed accelerated growth compared with HT1080 alone (79- vs 37-fold change, p<.050). For HT1080, human MSC-coinjected tumors showed significantly greater and highly infiltrative growth compared to those of HT1080 alone (p=.035). For mouse fibrosarcoma cells (WEHI164), mouse MSC-coinjected tumors had greater volume than those of WEHI164 alone (p=.141). For rat sarcoma cells (RR1022), rat MSC-coinjected tumors exhibited greater volume and infiltrative growth than those of RR1022 alone (p=.050). For human gastric cancer cells (5FU), tumors of 5FU alone were compact, nodular in shape, and expansile with good demarcation and no definite lung metastatic nodules, whereas tumors grown in the presence of human MSCs showed highly desmoplastic and infiltrative growth and multiple lung metastasis. CONCLUSIONS: We observed morphological evidence for MSC-associated tumor progression of fibrosarcomas and gastric cancer cells.