Abstract 419: Periostin activates integrin alpha5/beta1 through AKT-dependent pathway in invasion of cholangiocarcinoma

Abstract

Abstract Cholangiocarcinoma (CCA), a cancer arising from bile duct epithelial cells, is a serious health problem in Thai people. It is a progressive tumor with high metastatic potency. Recently, our group has found that periostin, an extracellular matrix protein, mainly produced from stromal activated fibroblasts of CCA has strong impact to induce cancer cell invasion. This work aims to investigate specific integrins which are utilized by periostin to drive invasion of CCA cells. The activated intracellular signal transduction pathway is also explored. Seven Thai patients-derived CCA cell lines were investigated their integrin expression patterns by real time PCR. The results indicated high level of integrin alpha6 in almost all cell lines. In addition, integrin alpha5 was also detected in not only CCA cell lines but also in immortalized non-tumorigenic biliary epithelial cell. For beta subunit integrin, the result revealed high expression levels of integrins beta1 and beta4 in CCA and non-tumorigenic cells. These results implied high level of integrins alpha5/beta1 and alpha6/beta4 in CCA cells. Flow cytometry and immunocytochemistry analysis confirmed intact molecules of these 2 integrin receptors on the membrane of M213 CCA cell line. Cell adhesion on periostin-coated surface was significantly decreased after integrin alpha5/beta1, but not alpha6/beta4, was blocked with the corresponding neutralizing antibodies. This result indicated that CCA cells preferred to use integrin alpha5/beta1 to bind with periostin. Moreover, cells treated with a neutralizing antibody against integrin alpha5/beta1 showed attenuated effect of periostin-induced invasion as similar to cells exposed to siRNA against integrin alpha5. Furthermore, we found that integrin alpha5-knocked down cells had decreased level of intracellular pAKT compared to negative control cells after activation with periostin. Taken these results together, it is likely to say that periostin activates CCA invasion through integrin alpha5/beta1 and AKT-dependent signal transduction pathway. This study suggests fibroblast-derived periostin, the stromal cell-derived substance, in promotion of CCA progression. Importantly, the obtained data highlight the potential of using the mechanism underlying stroma-driven cancer progression as an alternative target in the treatment of CCA patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 419. doi:10.1158/1538-7445.AM2011-419