芹菜素抑制黑色素瘤和宿主树突状细胞中的 PD-L1 表达，从而产生协同治疗效果。

BACKGROUND: The PD-L1/PD-1 pathway blockade-mediated immune therapy has shown promising efficacy in the treatment of multiple cancers including melanoma. The present study investigated the effects of the flavonoid apigenin on the PD-L1 expression and the tumorigenesis of melanoma. METHODS: The influence of flavonoids on melanoma cell growth and apoptosis was investigated using cell proliferation and flow cytometric analyses. The differential IFN-γ-induced PD-L1 expression and STAT1 activation were examined in curcumin and apigenin-treated melanoma cells using immunoblotting or immunofluorescence assays. The effects of flavonoid treatment on melanoma sensitivity towards T cells were investigated using Jurkat cell killing, cytotoxicity, cell viability, and IL-2 secretion assays. Melanoma xenograft mouse model was used to assess the impact of flavonoids on tumorigenesis in vivo. Human peripheral blood mononuclear cells were used to examine the influence of flavonoids on PD-L1 expression in dendritic cells and cytotoxicity of cocultured cytokine-induced killer cells by cell killing assays. RESULTS: Curcumin and apigenin showed growth-suppressive and pro-apoptotic effects on melanoma cells. The IFN-γ-induced PD-L1 upregulation was significantly inhibited by flavonoids, especially apigenin, with correlated reductions in STAT1 phosphorylation. Apigenin-treated A375 cells exhibited increased sensitivity towards T cell-mediated killing. Apigenin also strongly inhibited A375 melanoma xenograft growth in vivo, with enhanced T cell infiltration into tumor tissues. PD-L1 expression in dendritic cells was reduced by apigenin, which potentiated the cytotoxicity of cocultured cytokine-induced killer cells against melanoma cells. CONCLUSIONS: Apigenin restricted melanoma growth through multiple mechanisms, among which its suppression of PD-L1 expression exerted a dual effect via regulating both tumor and antigen presenting cells. Our findings provide novel insights into the anticancer effects of apigenin and might have potential clinical implications.

背景：PD-L1/PD-1 通路阻断介导的免疫疗法在包括黑色素瘤在内的多种癌症的治疗中显示出有希望的疗效。本研究探讨了类黄酮芹菜素对 PD-L1 表达和黑色素瘤发生的影响。

方法：使用细胞增殖和流式细胞术分析研究类黄酮对黑色素瘤细胞生长和凋亡的影响。使用免疫印迹或免疫荧光测定法研究姜黄素和芹菜素处理的黑色素瘤细胞中 IFN-γ 诱导的 PD-L1 表达和 STAT1 激活的差异。使用 Jurkat 细胞杀伤、细胞毒性、细胞活力和 IL-2 分泌测定法研究类黄酮处理对黑色素瘤细胞对 T 细胞敏感性的影响。使用黑色素瘤异种移植小鼠模型评估类黄酮对体内肿瘤发生的影响。使用人外周血单核细胞通过细胞杀伤测定法研究类黄酮对树突状细胞中 PD-L1 表达和共培养细胞因子诱导的杀伤细胞的细胞毒性的影响。

结果：姜黄素和芹菜素对黑色素瘤细胞表现出生长抑制和促凋亡作用。IFN-γ 诱导的 PD-L1 上调被类黄酮显著抑制，特别是芹菜素，伴有 STAT1 磷酸化的相关减少。芹菜素处理的 A375 细胞对 T 细胞介导的杀伤表现出更高的敏感性。芹菜素还强烈抑制体内 A375 黑色素瘤异种移植的生长，增强 T 细胞浸润到肿瘤组织中。芹菜素降低了树突状细胞中的 PD-L1 表达，增强了共培养细胞因子诱导的杀伤细胞对黑色素瘤细胞的细胞毒性。

结论：芹菜素通过多种机制限制黑色素瘤的生长，其中通过调节肿瘤和抗原呈递细胞来抑制 PD-L1 表达发挥双重作用。我们的发现为芹菜素的抗癌作用提供了新的见解，并可能具有潜在的临床意义。