SPARC induces M2 polarization of macrophages to promote proliferation, migration, and angiogenesis of cholangiocarcinoma cells.

Cholangiocarcinoma (CCA) is a disease that includes a variety of epithelial neoplasms characterized by the differentiation of cholangiocytes. M2 polarization is imperative to the development of CCA cells. In this study, we investigated the influence of secreted protein acidic and rich in cysteine (SPARC) on M2 polarization and CCA cell growth. We found that the SPARC level was amplified in M2-polarized macrophages and TAMs. In addition, the downregulation of SPARC prevented the M2 polarization of macrophages. Silencing SPARC inhibited the M2 macrophage-mediated effects on the proliferation, migration, and angiogenesis of CCA cells. Additionally, SPARC knockdown blocked the M2 polarization of macrophages by inhibiting the PI3K/AKT signaling. Moreover, an activator of PI3K signaling repressed the effect of SPARC knockdown on the M2 macrophage-induced elevation of proliferation, migration, and angiogenesis in CCA cells. In conclusion, SPARC contributes to the M2 polarization of macrophages to promote proliferation, migration, and angiogenesis of CCA cells, which provides new insight into the treatment of CCA.