酪氨酸基黑色素合成异质性调节黑色素瘤细胞的肺和脑特异性浸润微环境

选取6个B16黑色素瘤细胞样本进行转录组测序分析。饮食中酪氨酸对调节黑色素瘤进展已经得到广泛认可。然而，酪氨酸基黑色素合成是否对黑色素瘤的肺和脑特异性浸润有贡献，仍然是未知的。此外，如何通过干预黑色素瘤细胞的酪氨酸酶活性和免疫细胞功能来抑制多器官转移，需要进行设计和验证。本研究采用来自患者的黑色素瘤细胞和B16小鼠黑色素瘤细胞，对肿瘤和多器官中的酪氨酸含量变化进行了监测，并检测了来自多器官的黑色素瘤细胞的酪氨酸基黑色素合成能力。另外，我们还采用RNA-seq、流式细胞术、实时PCR和组合转移小鼠模型来分析器官特异性浸润并设计治疗策略。具有酪氨酸酶高活性和对酪氨酸利用敏感性的B16黑色素瘤细胞（Tyr-H细胞）容易在肺中浸润，而没有上述特征的B16黑色素瘤细胞（Tyr-L细胞）在脑中增殖。机理上，Tyr-H细胞通过高分泌的CXCL1和CXCL2，以及过量的黑色素体积累诱导肺转移结构和细胞死亡。Tyr-L细胞在脑中进展时增强了肿瘤浸润的巨噬细胞PD-L1表达。因此，通过干预酪氨酸酶活性（2-乙氧基苯酰胺或氢醌），以及对吞噬作用（GSK343）或趋化作用（SB225002）的抑制剂来抑制器官特异性浸润，并显著提高了免疫检查点阻断（PD1抗体）治疗的黑色素瘤小鼠的生存率。黑色素瘤细胞在利用酪氨酸方面的异质性与器官特异性浸润有关，为制定对抗黑色素瘤并预防其转移的策略提供了基础。

Six B16 melanoma cell samples were selected for transcriptome sequencing analysis in this study. Dietary tyrosine has been widely recognized to regulate melanoma progression. However, whether tyrosine-based melanin synthesis contributes to the lung- and brain-specific infiltration of melanoma remains unknown. Furthermore, how to suppress multiple organ metastasis by intervening in the tyrosinase activity of melanoma cells and the function of immune cells requires further design and validation. In this study, patient-derived melanoma cells and B16 mouse melanoma cells were used to monitor the changes in tyrosine content in tumors and multiple organs, and to detect the tyrosine-based melanin synthesis capacity of melanoma cells derived from multiple organs. Additionally, RNA-seq, flow cytometry, real-time PCR, and a combinatorial metastatic mouse model were employed to analyze organ-specific infiltration and design therapeutic strategies. B16 melanoma cells with high tyrosinase activity and sensitivity to tyrosine utilization (designated Tyr-H cells) readily infiltrate the lungs, while B16 melanoma cells lacking these features (designated Tyr-L cells) proliferate in the brain. Mechanistically, Tyr-H cells induce pulmonary metastatic niches and cell death via highly secreted CXCL1 and CXCL2, as well as excessive melanosome accumulation. When progressing in the brain, Tyr-L cells enhance PD-L1 expression on tumor-infiltrating macrophages. Accordingly, inhibiting organ-specific infiltration by intervening in tyrosinase activity (using 2-ethoxybenzamide or hydroquinone) and employing inhibitors of phagocytosis (GSK343) or chemotaxis (SB225002) significantly improved the survival rate of melanoma-bearing mice treated with immune checkpoint blockade ("anti-PD-1 antibody"). The heterogeneity of tyrosine utilization in melanoma cells is associated with organ-specific infiltration, providing a foundation for developing strategies to combat melanoma and prevent its metastasis.