Endogenous CXCL9 affects prognosis by regulating tumor‐infiltrating natural killer cells in intrahepatic cholangiocarcinoma

Abstract

CXCL9, an IFN-γ inducible chemokine, has been reported to play versatile roles in tumor-host interrelationships. However, little is known about its role in intrahepatic cholangiocarcinoma (iCCA). Here, we aimed to elucidate the prognostic and biological implications of CXCL9 in iCCA. Endogenous CXCL9 expression and the number of tumor-infiltrating lymphocytes were immunohistochemically assessed in resection specimens. These data were validated in mice treated by silencing CXCL9 with short hairpin RNA. In addition, the induction of endogenous CXCL9 and the effects of CXCL9 on tumor biological behaviors were evaluated in human cholangiocarcinoma cell lines. Immunohistochemical analyses revealed that high CXCL9 expression was closely correlated with prolonged postoperative survival and a large number of tumor-infiltrating natural killer (NK) cells. In fact, due to the trafficking of total and tumor necrosis factor-related apoptosis-inducing ligand-expressing NK cells into tumors, CXCL9-sufficient cells were less tumorigenic in the liver than CXCL9-deficient cells in mice. Although CXCL9 involvement in tumor growth and invasion abilities differed across cell lines, it did not exacerbate these abilities in CXCL9-expressing cell lines. We showed that CXCL9 was useful as a prognostic marker. Our findings also suggested that CXCL9 upregulation might offer a therapeutic strategy for treating CXCL9-expressing iCCA by augmenting anti-tumor immune surveillance. K E Y W O R D S CXCL9, intrahepatic cholangiocarcinoma, natural killer cell, tumor necrosis factor-related apoptosis-inducing ligand, tumor-infiltrating lymphocyte S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Fukuda Y, Asaoka T, Eguchi H, et al. Endogenous CXCL9 affects prognosis by regulating tumorinfiltrating natural killer cells in intrahepatic cholangiocarcinoma. Cancer Sci. 2020;111:323-333. https ://

Role of Chemokines in the Biology of Cholangiocarcinoma

“…CXCL9 has been identified as a tumor suppressor, because in 70 iCCA resection specimens high levels of CXCL9 were associated to a favorable postoperative survival. High CXCL9 also correlated with remarkable abundance of tumor-infiltrating NK cells [ 87 ]. The protective role of CXCL9 was confirmed in a mouse model of iCCA, in which CXCL9 knockdown led to greater tumor masses, affecting NK cell recruitment into tumor areas.…”

“…Moreover, exposure of CCA cells to CXCL9 did not modify either invasion or proliferation rate. These data suggest that boosting the CXCL9 system could represent a promising therapeutic approach, being involved in immunopotentiation [ 87 ].…”

Molecular and Immunological Characterization of Biliary Tract Cancers: A Paradigm Shift Towards a Personalized Medicine

“…On the contrary, NK cells are cytotoxic innate cells with the capacity to destroy tumor cells in an antigen-nonspecific manner [77], but less is known about the role of NK cells in CCA. However, in vitro and in vivo studies demonstrated that the endogenous iCCA CXCL9 correlates with the higher infiltrations of NK cells in the tumor zones [78] and that the biliary epithelium could present antigens to and activate NK T cells [79].…”

Tumor microenvironment in primary liver tumors: A challenging role of natural killer cells

“…The use of in vitro cytokine-activated NK cells in combination with cetuximab, the mAb against EGFR, has shown benefits in a higher antibody-dependent cellular cytotoxicity response against human iCCA cell lines such as HuCCT-1 and OZ[ 183 ]. Moreover, the multiple infusions of ex vivo -expanded human NK cells into iCCA xenograft mice (HuCCT-1 tumor-bearing nude mice) resulted in NK cell-mediated cytolytic response with inhibition of tumor growth[ 184 ].…”