High CCL7 expression is associated with migration, invasion and bone metastasis of non-small cell lung cancer cells

Distant metastasis is the main cause of death for non-small cell lung cancer (NSCLC) patients, with the bone as a more frequent metastatic site. The expression of various chemokines and their receptors may contribute to the predilection of organ specific metastasis. In this study, we demonstrated that CC chemokine ligand 7 (CCL7) and its receptors CCR1, CCR2 and CCR3 were up-regulated markedly in lung cancer bone metastasis. In addition, CCL7 promoted migration and invasion of lung cancer cells in a dose-dependent pattern but played an insignificant role in cell proliferation mainly through CCR3. Finally, we identified a cohort of critical downstream genes of CCL7 related to cancer metastasis using Illumina deep mRNA sequencing. These findings may help better understand the molecular aspects of bone metastasis in lung cancer, and prefigure a potential clinical value for the prevention of bone recurrences.