Macrophage infiltration promotes invasiveness of breast cancer cells via activating long non-coding RNA UCA1.

There is now considerable evidence supporting the view that macrophage infiltration is playing a critical role in the proliferation and progression of breast cancer but the underlying molecular mechanisms remain largely unknown. To this end, using long non-coding RNA (lncRNA) expression profiling, we examined changes in lncRNA expression in breast cancer cells treated with conditioned medium (CM) from cultured human THP-1 macrophages. We found that treatment with macrophage CM induced the expression of numerous lncRNAs, including urothelial cancer associated 1 (UCA1). Knockdown of UCA1 using shRNA inhibited AKT phosphorylation and abolished invasiveness of tumor cells induced by macrophage CM. Consistent with these results; we further showed that UCA1 level was significantly enhanced in human primary breast tumors and correlated with advanced clinical stage, supporting its role in promoting carcinogenesis and progression of breast cancer. Together, these results suggest that macrophage could promote invasiveness of breast cancer cells by enhancing expression of lncRNA UCA1.