Forced Expression of CXCL10 Prevents Liver Metastasis of Colon Carcinoma Cells by the Recruitment of Natural Killer Cells

CXC chemokine ligand 10 (CXCL10) is a CXC chemokine family protein that transmits signals by binding to its specific receptor, CXCR3. CXCL10 is also known as an interferon-gamma-inducible chemokine involved in various biological phenomena, including chemotaxis of natural killer (NK) cells and cytotoxic T lymphocytes, that suppress tumor growth and inhibition of angiogenesis. In this study, we examined the effects of forced expression of CXCLIO in a murine colon carcinoma cell line (CT26) on growth and metastasis in syngeneic mice. We first established CT26 cells that were stably expressing murine CXCL10 (CT26/CXCL10) and compared their growth with their parental CT26 cells in vitro and in vivo. The in vitro growth of the CT26/CXCL10 and CT26 cells was comparable, whereas the in vivo growth of the CT26/CXCL10 cells in the skin was strongly suppressed. Liver metastasis of the CT26/CXCL10 cells was also significantly suppressed after intra-splenic implantation. Removal of NK cells by the administration of anti-asialo GM1 antibody canceled the suppression of subcutaneous growth and liver metastasis of CT26/CXCL10 cells. Immunofluorescence clearly showed that abundant NKp46-positive NK cells were recruited into the liver metastatic lesions of the CT26/CXCL10 cells, consistent with specific NK cell migration towards the culture supernatant from the CT26/CXCL10 cells in the chemotaxis assay using transwells. These findings indicate that CXCL10 prevents in vivo growth and metastasis of colon carcinoma cells by recruiting NK cells, suggesting that forced expression of CXCL10 in the colon tumors by gene delivery should lead to a favorable clinical outcome.

CXC趋化因子配体10（CXCL10）是一种CXC趋化因子家族蛋白，它通过与其特异性受体CXCR3结合来传递信号。CXCL10也被称为一种γ-干扰素诱导的趋化因子，参与多种生物学现象，包括自然杀伤（NK）细胞和细胞毒性T淋巴细胞的趋化作用，这些作用可抑制肿瘤生长和血管生成。在本研究中，我们检测了在小鼠结肠癌细胞系（CT26）中强制表达CXCL10对同基因小鼠生长和转移的影响。我们首先建立了稳定表达小鼠CXCL10的CT26细胞（CT26/CXCL10），并在体外和体内比较了它们与亲本CT26细胞的生长情况。CT26/CXCL10细胞和CT26细胞的体外生长情况相当，然而CT26/CXCL10细胞在皮肤内的体内生长受到强烈抑制。脾内植入后，CT26/CXCL10细胞的肝转移也显著受到抑制。通过给予抗去唾液酸GM1抗体去除NK细胞，消除了对CT26/CXCL10细胞皮下生长和肝转移的抑制作用。免疫荧光清楚地显示，大量NKp46阳性的NK细胞被招募到CT26/CXCL10细胞的肝转移病灶中，这与在使用Transwell小室进行的趋化实验中NK细胞朝着CT26/CXCL10细胞的培养上清液特异性迁移是一致的。这些发现表明，CXCL10通过招募NK细胞来阻止结肠癌细胞的体内生长和转移，这提示通过基因传递在结肠肿瘤中强制表达CXCL10应该会带来良好的临床结果。