G-CSF and G-CSFR are highly expressed in human gastric and colon cancers and promote carcinoma cell proliferation and migration

Background: Granulocyte colony-stimulating factor (G-CSF) is a pro-inflammatory cytokine that stimulates myeloid stem cell maturation, proliferation, and migration into circulation. Despite being a known growth factor, the impact of G-CSF on solid tumours has not been well examined. G-CSF receptor (G-CSFR) is expressed by some tumours, and thus the aim of this study was to examine the expression and impact of G-CSF and G-CSFR on gastrointestinal tumours. Methods: In this study, G-CSF expression was examined in human gastric and colon tumours and by tumour-derived stromal myofibroblasts and carcinoma cells. G-CSFR expression was examined on carcinoma cells isolated from human tissues. The effects of G-CSF on gastric and colon carcinoma cell proliferation, migration, and signalling were examined. Results: G-CSFR was highly expressed in 90% of human gastric and colon carcinomas. G-CSF was also found to be highly produced by stromal myofibroblasts and carcinoma cells. Exposure of carcinoma cells to G-CSF led to increased proliferation and migration, and expansion of a sub-population of carcinoma cells expressing stem-like markers. These processes were dependent on ERK1/2 and RSK1 phosphorylation. Conclusions: These data suggest that the G-CSF/R axis promotes gastric and colorectal cancer development and suggest they are potential tumour targets.