Periostin (PN) is mainly produced from stromal fibroblasts in cholangiocarcinoma (CCA) and shows strong impact in cancer promotion. This work aimed to investigate the mechanism that PN uses to drive CCA invasion. It was found that ITGα5β1 and α6β4 showed high expression in non-tumorigenic biliary epithelial cells and in almost all CCA cell lines. PN had preferential binding to CCA cells via ITGα5β1 and blocking this receptor by either neutralizing antibody or siITGα5 could attenuate PN-induced invasion. After PN-ITGα5β1 binding, intracellular pAKT was upregulated whereas there was no change in pERK. Moreover, PN could not activate AKT in condition of treatment with a PI3K inhibitor. These data provide evidence that PN-activated invasion of CCA cells is through the ITGα5β1/PI3K/AKT pathway. Strategies aimed to inhibit this pathway may, thus, provide therapeutic benefits.

Periostin (PN) (also known as osteoblast-specific factor OSF-2) is a protein that in humans is encoded by the POSTN gene and has been correlated with a reduced survival of cholangiocarcinoma (CCA) patients, with the well-known effect of inducing epithelial-to-mesenchymal transition (EMT). The present study investigated the effect of PN, through integrin (ITG)α5β1, in EMT-mediated CCA aggressiveness. The alterations in EMT-related gene and protein expression were investigated by real-time PCR, western blot analysis and zymogram. The effects of PN on migration and the level of TWIST-2 were assessed in CCA cells with and without siITGα5 transfection. PN was found to induce CCA cell migration and EMT features, including increments in Twist-related protein 2 (TWIST-2), zinc finger protein SNAI1 (SNAIL-1), α-smooth muscle actin (ASMA), vimentin (VIM) and matrix metallopeptidase 9 (MMP-9), and a reduction in cytokeratin 19 (CK-19) together with cytoplasmic translocation of E-cadherin (CDH-1). Additionally, PN markedly induced MMP-9 activity. TWIST-2 was significantly induced in PN-treated CCA cells; this effect was attenuated in the ITGα5β1-knockdown cells and corresponded to reduced migration of the cancer cells. These results indicated that PN induced CCA migration through ITGα5β1/TWIST-2-mediated EMT. Moreover, clinical samples from CCA patients showed that higher levels of TWIST-2 were significantly correlated with shorter survival time. In conclusion, the ITGα5β1-mediated TWIST-2 signaling pathway regulates PN-induced EMT in CCA progression, and TWIST-2 is a prognostic marker of poor survival in CCA patients.

No abstract