Table 2_Gut microbe Terrisporobacter promotes papillary thyroid carcinoma progression by upregulating the NTRK1 oncogene and fostering an immunosuppressive tumor microenvironment.docx

Growing evidence suggests a link between the gut microbiome and papillary thyroid carcinoma (PTC), but the causal relationships and the impact on the tumor immune microenvironment (TME) are poorly understood. This study aimed to elucidate the causal role of specific gut microbes in PTC and uncover the underlying immunological and molecular mechanisms. We employed a multi-stage design, beginning with a two-sample Mendelian randomization (MR) analysis using large-scale GWAS data to infer causality. Findings were then validated in 450 PTC patients from The Cancer Genome Atlas (TCGA) by analyzing correlations between microbial abundance, gene expression, immune cell infiltration, and survival. Finally, the core mechanism was confirmed through extensive in vitro experiments with PTC cell lines. Our MR analysis identified a causal association between a genetically predicted higher abundance of the genus Terrisporobacter and an increased risk of PTC (Odds Ratio [OR] = 2.06, 95% Confidence Interval [CI]: 1.34-3.16). In the TCGA cohort, higher intratumoral signals of Terrisporobacter was significantly correlated with an immunosuppressive TME, characterized by increased infiltration of M2 macrophages (ρ = 0.25, p < 0.001) and decreased CD8+ T cells (ρ = -0.19, p = 0.008). Mechanistically, Terrisporobacter abundance was also strongly associated with the upregulation of the oncogene NTRK1 (ρ = 0.35, p < 0.001), which independently predicted poorer overall survival (Hazard Ratio [HR] = 2.15, p = 0.004). In vitro experiments confirmed that supernatant from Terrisporobacter culture not only upregulated NTRK1 expression and promoted PTC cell proliferation but also enhanced invasion and induced cell de-differentiation. Importantly, pharmacological inhibition of TRK signaling reversed the bacteria-induced aggressive phenotype. Our integrated analysis provides robust, multi-layered evidence for a causal role of Terrisporobacter in promoting PTC progression. We define a novel gut-thyroid axis where Terrisporobacter contributes to PTC development by upregulating the NTRK1 oncogene and shaping a pro-tumorigenic, immunosuppressive microenvironment. These findings reveal a new dimension of host-microbe interaction in thyroid cancer and highlight the TME as a key downstream target of microbial influence.

越来越多的证据表明肠道微生物组（gut microbiome）与甲状腺乳头状癌（papillary thyroid carcinoma, PTC）之间存在关联，但二者的因果关系以及肠道菌群对肿瘤免疫微环境（tumor immune microenvironment, TME）的影响尚未明确。本研究旨在阐明特定肠道微生物在PTC发生发展中的因果作用，并揭示其潜在的免疫学与分子机制。本研究采用多阶段研究设计：首先利用大规模全基因组关联研究（Genome-Wide Association Study, GWAS）数据开展两样本孟德尔随机化（Mendelian randomization, MR）分析以推断因果关联；随后从癌症基因组图谱（The Cancer Genome Atlas, TCGA）数据库中纳入450例PTC患者，通过分析微生物丰度、基因表达、免疫细胞浸润与患者生存的相关性对上述研究发现进行验证；最后通过PTC细胞系的大量体外（in vitro）实验证实核心机制。本研究的MR分析显示，遗传预测的Terrisporobacter属丰度升高与PTC风险增加存在因果关联（比值比[Odds Ratio, OR]=2.06，95%置信区间[Confidence Interval, CI]：1.34~3.16）。在TCGA队列中，瘤内Terrisporobacter信号强度升高与免疫抑制型TME显著相关，表现为M2型巨噬细胞（M2 macrophages）浸润增加（ρ=0.25，P<0.001）以及CD8阳性T细胞（CD8+ T cells）浸润减少（ρ=-0.19，P=0.008）。从机制层面来看，Terrisporobacter丰度还与癌基因NTRK1（oncogene NTRK1）的上调呈强相关性（ρ=0.35，P<0.001），而NTRK1高表达可独立预测患者总生存期较差（风险比[Hazard Ratio, HR]=2.15，P=0.004）。体外实验证实，Terrisporobacter培养上清不仅可上调NTRK1表达、促进PTC细胞增殖，还能增强细胞侵袭能力并诱导细胞去分化（cell de-differentiation）。值得注意的是，对TRK信号通路（TRK signaling）进行药理学抑制可逆转细菌诱导的肿瘤侵袭表型。本研究的整合分析为Terrisporobacter在促进PTC进展中的因果作用提供了可靠的多维度证据。我们提出了一条全新的肠-甲状腺轴（gut-thyroid axis）通路：Terrisporobacter通过上调癌基因NTRK1的表达，并塑造促肿瘤发生的免疫抑制微环境，从而参与PTC的发生发展。本研究揭示了宿主-微生物互作在甲状腺癌中的全新维度，并强调TME是微生物调控下游效应的关键靶点。