Department of Surgery, Ajou University School of Medicine, Suwon, Korea.
Cancer Biology Graduate Program, Ajou University Graduate School of Medicine, Suwon, Korea.
Cancer Res Treat. 2023 Jan;55(1):167-178. doi: 10.4143/crt.2022.094. Epub 2022 May 20.
Appropriate preclinical mouse models are needed to evaluate the response to immunotherapeutic agents. Immunocompetent mouse models have rarely been reported for gastric cancer. Thus, we investigated immunophenotypes and responses to immune checkpoint inhibitor (ICI) in immunocompetent mouse models using various murine gastric cancer cell lines.
We constructed subcutaneous syngeneic tumors with murine gastric cancer cell lines, YTN3 and YTN16, in C57BL/6J mice. Mice were intraperitoneally treated with IgG isotype control or an anti-programmed death-ligand 1 (PD-L1) neutralizing antibody. We used immunohistochemistry to evaluate the tumor-infiltrating immune cells of formalin-fixed paraffin-embedded mouse tumor tissues. We compared the protein and RNA expression between YTN3 and YTN16 cell lines using a mouse cytokine array and RNA sequencing.
The mouse tumors revealed distinct histological and molecular characteristics. YTN16 cells showed upregulation of genes and proteins related to immunosuppression, such as Ccl2 (CCL2) and Csf1 (M-CSF). Macrophages and exhausted T cells were more enriched in YTN16 tumors than in YTN3 tumors. Several YTN3 tumors were completely regressed by the PD-L1 inhibitor, whereas YTN16 tumors were unaffected. Although treatment with a PD-L1 inhibitor increased infiltration of T cells in both the tumors, the proportion of exhausted immune cells did not decrease in the non-responder group.
We confirmed the histological and molecular features of cancer cells with various responses to ICI. Our models can be used in preclinical research on ICI resistance mechanisms to enhance clinical efficacy.
需要适当的临床前小鼠模型来评估免疫治疗药物的反应。免疫功能正常的小鼠模型很少用于胃癌的研究。因此，我们使用各种小鼠胃癌细胞系研究了免疫功能正常的小鼠模型的免疫表型和对免疫检查点抑制剂（ICI）的反应。
我们在 C57BL/6J 小鼠中构建了具有小鼠胃癌细胞系 YTN3 和 YTN16 的皮下同源肿瘤。小鼠经腹腔内给予 IgG 同种型对照或抗程序性死亡配体 1（PD-L1）中和抗体治疗。我们使用免疫组织化学评估福尔马林固定石蜡包埋的小鼠肿瘤组织中的肿瘤浸润免疫细胞。我们使用小鼠细胞因子阵列和 RNA 测序比较了 YTN3 和 YTN16 细胞系之间的蛋白和 RNA 表达。
小鼠肿瘤显示出不同的组织学和分子特征。YTN16 细胞显示与免疫抑制相关的基因和蛋白上调，如 Ccl2（CCL2）和 Csf1（M-CSF）。与 YTN3 肿瘤相比，YTN16 肿瘤中富含更多的巨噬细胞和耗竭 T 细胞。几种 YTN3 肿瘤被 PD-L1 抑制剂完全消退，而 YTN16 肿瘤则不受影响。虽然 PD-L1 抑制剂治疗增加了两种肿瘤中 T 细胞的浸润，但在无反应组中耗竭免疫细胞的比例没有降低。
我们证实了对 ICI 具有不同反应的癌细胞的组织学和分子特征。我们的模型可用于 ICI 耐药机制的临床前研究，以提高临床疗效。
