确保建立一个成熟的小鼠模型对于识别和验证免疫肿瘤学新的治疗靶点至关重要。C57BL/6小鼠是任何动物最全面特征的免疫系统之一，为免疫肿瘤学发现提供了强大的平台。在B6129SF1杂交小鼠中使用TBP3743（小鼠厌氧链霉菌甲状腺癌[ATC]）细胞建立了一个原位肿瘤模型，该模型在肿瘤免疫学方面相对于C57BL/6纯系小鼠的数据有限。本研究旨在建立一个新的原位ATC模型，重点描述该模型中的肿瘤微环境和免疫特性。通过在C57BL/6小鼠中进行体内连续通过实现了适应性的TBP3743细胞生成。随后，通过甲状腺内注射建立以下原位肿瘤模型：注射原始TBP3743细胞的B6129SF1小鼠（原始/129）、注射适应性细胞的B6129SF1小鼠（适应/129）和注射适应性细胞的C57BL/6小鼠（适应/B6）。在体外，适应性TBP3743细胞经历了去分化，但其细胞形态、存活率和迁移/浸润潜力与原始细胞相当。适应/129中的Ki-67阳性细胞比原始/129多。原位肿瘤的RNA测序数据显示，相比原始/129，适应/129表现出增强的致癌特性。相反，适应/B6中的原位肿瘤较小，Ki-67阳性细胞比适应/129小。然而，适应/B6和适应/129中的肿瘤致癌特性相似。与适应/129相比，适应/B6中富集了与免疫相关的通路。原位肿瘤的流式细胞术分析显示，适应/B6中细胞毒性CD8+ T细胞和单核-髓源性抑制细胞的比例高于适应/129。适应/B6中的CD8+和CD4+细胞比例与人类ATC类似，但在原始/B6中比例微小。在C57BL/6小鼠中建立了一个新的原位ATC肿瘤模型。与原始B6129SF1小鼠模型相比，新模型表现出更具侵袭性的肿瘤细胞行为和强烈的免疫反应。我们期望这个新模型有助于理解肿瘤微环境，并为药物开发提供平台。

Securing a well-established mouse model is important in identifying and validating new therapeutic targets for immuno-oncology. The C57BL/6 mouse is one of the most fully characterised immune system of any animal and provides powerful platform for immuno-oncology discovery. An orthotopic tumor model has been established using TBP3743 (murine anaplastic thyroid cancer [ATC]) cells in B6129SF1 hybrid mice, this model has limited data on tumor immunology than C57BL/6 inbred mice. This study aimed to establish a novel orthotopic ATC model in C57BL/6 mice and characterize the tumor microenvironment focusing immunity in the model.Adapted TBP3743 cells were generated via in vivo serial passaging in C57BL/6 mice. Subsequently, the following orthotopic tumor models were established via intrathyroidal injection: B6129SF1 mice injected with original TBP3743 cells (original/129), B6129SF1 mice injected with adapted cells (adapted/129), and C57BL/6 mice injected with adapted cells (adapted/B6).The adapted TBP3743 cells de-differentiated but exhibited cell morphology, viability, and migration/invasion potential comparable with those of original cells in vitro. The adapted/129 contained a higher Ki-67+ cell fraction than the original/129. RNA sequencing data of orthotopic tumors revealed enhanced oncogenic properties in the adapted/129 compared with those in the original/129. In contrast, the orthotopic tumors grown in the adapted/B6 were smaller, with a lower Ki-67+ cell fraction than those in the adapted/129. However, the oncogenic properties of the tumors within the adapted/B6 and adapted/129 were similar. Immune-related pathways were enriched in the adapted/B6 compared with those in the adapted/129. Flow cytometric analysis of the orthotopic tumors revealed higher cytotoxic CD8+ T cell and monocytic-myeloid-derived suppressor cell fractions in the adapted/B6 compared with the adapted/129. The estimated CD8+ and CD4+ cell fractions in the adapted/B6 were similar to those in human ATCs but negligible in the original/B6.A novel orthotopic tumor model of ATC was established in C57BL/6 mice. Compared with the original B6129SF1 murine model, the novel model exhibited more aggressive tumor cell behaviours and strong immune responses. We expect that this novel model contributes to the understanding tumor microenvironment and provides the platform for drug development.Copyright © 2023 Xu, Shin, Kim, Ha, Won, Kim, Park, Parangi, Cho and Lee.