Tumours can evade the immune system by suppressing the activity of immune cells within the tumour microenvironment (TME), with cytotoxic CD8⁺ T cells being a key target for immunosuppression. A study in Cell Metabolism has now identified a mechanism by which fibroblast growth factor 21 (FGF21) promotes tumour growth via inhibition of CD8⁺ T cell activity.

Activated CD8⁺ T cells were treated with conditioned media from multiple different tumour cell lines (TCM) or from a normal control cell line. T cells treated with TCM showed a substantial reduction in the production of molecules such as IFNγ and granzyme B, as compared with T cells treated with control media. This finding indicated that T cell function was being suppressed by secreted factors from the tumours. Using proteomic analysis, the researchers identified FGF21 as a consistently upregulated factor in TCM compared with control media. Tumour samples from patients with colon cancer similarly showed increased expression of FGF21 compared with healthy tissue samples from the same individuals.

肿瘤可以通过抑制肿瘤微环境（TME）内免疫细胞的活性来逃避免疫系统，其中细胞毒性CD8 ⁺ T细胞是免疫抑制的关键目标。 《细胞代谢》中的一项研究现已确定成纤维细胞生长因子 21 (FGF21) 通过抑制 CD8 ⁺ T 细胞活性来促进肿瘤生长的机制。

用来自多种不同肿瘤细胞系 (TCM) 或正常对照细胞系的条件培养基处理激活的 CD8 ⁺ T 细胞。与用对照培养基处理的 T 细胞相比，用 TCM 处理的 T 细胞显示出 IFNγ 和颗粒酶 B 等分子的产生显着减少。这一发现表明 T 细胞功能受到肿瘤分泌因子的抑制。通过蛋白质组学分析，研究人员发现与对照培养基相比，FGF21 是中药中持续上调的因子。与来自同一个体的健康组织样本相比，来自结肠癌患者的肿瘤样本同样显示出 FGF21 表达增加。