Abstract 5768: Intrahepatic cholangiocarcinoma cells can be converted into functional hepatocytes by inhibition of Wnt signaling pathway
Authors: Toshiaki Nakaoka, Yoshimasa Saito, Toshihide Muramatsu, Hidenori Ojima, Yae Kanai, Yuko Sugiyama, Masaki Kimura, Takanori Kanai, Toshiro Sato, Hidetsugu Saito
Journal: Cancer Research (2017)

Abstract Background and Aim: Intrahepatic cholangiocarcinoma (IHCC) is the second most prevalent malignancy in the liver, and is one of the most aggressive malignancies characterized by a poor prognosis. It is believed that IHCC is an epithelial cell malignancy arising from cholangiocytes composing the intrahepatic bile ducts. However, patients with viral hepatitis develop IHCC, suggesting that IHCC is derived from transformed hepatocytes. Indeed, recent studies have revealed that IHCC can arise from Notch-mediated conversion of hepatocytes in mice. The new 3D culture system called organoid culture has been developed, which allows long-term expansion of Lgr5-positive stem cells. To clarify whether IHCC cells harbor the potency of conversion into functional hepatocytes, we established organoids derived from human IHCC and cultured them in different culture conditions. Methods: We established organoids derived from human IHCC and cultured these organoids with expansion medium (EM) containing R-spondin 1. Conversion of IHCC cells into hepatocytes was conducted by organoid culture with differentiation medium (DM) containing BMP7, DAPT, FGF19 and dexamethasone. Results: Gene set enrichment analysis (GSEA) showed that genes associated with hepatocyte differentiation signature were significantly enriched in IHCC organoids cultured with DM compared with those cultured with EM. IHCC organoids cultured with DM induced up-regulation of hepatocyte markers albumin, HNF4a and CYP3A4, and acquired mature hepatocyte functions including albumin secretion, bile acid production and increased CYP3A4 activity. Removal of R-spondin 1, a ligand of Wnt signaling pathway, from EM enhanced hepatocyte differentiation. IHCC organoids cultured with DM significantly reduced the malignant potential in vitro and in vivo compared with those cultured with EM. Further studies using thioacetamide (TAA)-induced IHCC model mice showed that TAA-induced inflammation in the liver promoted recruited macrophages to secrete Wnt3a. Conclusions: These findings indicated that IHCC cells can be converted into functional hepatocytes by inhibition of Wnt signaling pathway. Activation of Wnt signaling pathway by recruited macrophages may play a critical role in the malignant transformation of hepatocytes into IHCC, which could be an important therapeutic target for IHCC. Citation Format: Toshiaki Nakaoka, Yoshimasa Saito, Toshihide Muramatsu, Hidenori Ojima, Yae Kanai, Yuko Sugiyama, Masaki Kimura, Takanori Kanai, Toshiro Sato, Hidetsugu Saito. Intrahepatic cholangiocarcinoma cells can be converted into functional hepatocytes by inhibition of Wnt signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5768. doi:10.1158/1538-7445.AM2017-5768