C5a receptor enhances hepatocellular carcinoma cell invasiveness via activating ERK1/2-mediated epithelial-mesenchymal transition.

C5a and its receptor, C5a receptor (C5aR), play critical roles in tumor progression. However, mechanisms of C5a-C5aR axis in hepatocellular carcinoma (HCC) cell invasiveness are not fully elucidated. In this study, we found that C5aR expression was highly expressed in HCC cell lines and tumor tissues, and associated with capsular invasion, tumor stage and some epithelial-mesenchymal transition (EMT)-related markers. Activation of C5aR by C5a promoted HCC cell invasion and migration, whereas depletion of C5aR expression significantly impaired C5a-stimulated invasion and migration. Furthermore, we found that C5aR induced EMT in HCC cells, through downregulation of E-cadherin and Claudin-1 expression, and upregulation of Snail expression. Finally, we demonstrated that C5aR stimulated activation of ERK1/2, and ERK1/2 pathway was involved in C5aR-mediated EMT, cell invasion and migration of HCC cells. Thus, our data suggest that C5aR stimulates cell invasion and migration via ERK1/2-mediated EMT in HCC cells, and implicate that blocking C5aR expression has therapeutic promise to inhibit HCC invasiveness.