The microenvironment such as cancer associated fibroblasts (CAFs) was reported to be involved in progression of intrahepatic cholangiocarcinoma (ICC). Nintedanib (BIBF1120) is a tyrosine kinase inhibitor of PDGFR, FGFR and VEGFR which is approved for idiopathic pulmonary fibrosis. And nintedanib was reported to suppress liver fibrosis in mouse through the suppression of hepatic stellate cells activation (Ozturk Akcora B, et al. Sci Rep. 2017 Mar 14;7:44545). Therefore, we hypothesized that nintedanib can inhibit the activity of CAFs of ICC. The purpose of this study is to clarify the effect of CAFs on ICC and develop a new therapy for ICC targeted to CAFs.
CAFs were established from surgically resected ICC tissues. The effect of nintedanib on proliferation and expression of alpha smooth muscle actin (αSMA) of CAFs was examined. The effect of CAF-CM (conditioned medium of CAFs) and nintedanib-CAF-CM (CM of CAFs treated with nintedanib) on proliferation and invasion of ICC cell lines (HuCCT1, RBE) was examined. The humoral factors of CAF-CM and nintedanib-CAF-CM were analyzed using cytokine array and ELISA. The effect of nintedanib and gemsitabine (GEM) treatment on xenograft model co-implanted with HuCCT1 and CAFs was examined in vivo.
Nintedanib(1µM) suppressed the proliferation of CAFs and expression of αSMA in CAFs. CAF-CM significantly promoted the proliferation and invasion of ICC cell lines. But in nintedanib-CAF-CM, all of those cancer promoting effects were cancelled. In cytokine array and ELISA of CAF-CMs, expression of IL-6, IL-8, VEGF, VCAM1, and Osteopontin were suppressed in nintedanib-CAF-CM compared with CAF-CM. HuCCT1 + CAFs xenograft was increased more than HuCCT1 alone in vivo. Combination treatment with nintedanib (30mg/kg) and GEM (50mg/kg) inhibited HuCCT1 + CAFs xenograft growth than nintedanib or GEM alone in vivo. The xenograft treated with nintedanib and GEM showed reduction of both αSMA-positive staining in stroma and proportion of Ki-67 positive ICC cells.
Nintedanib suppressed CAFs activity and the production of cancer-promoting cytokines produced by CAFs. Combination therapy with nintedanib and GEM may be a new promising therapy to overcome refractory ICC.
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All authors have declared no conflicts of interest.