Although many studies have compared tumor fibroblasts (T-Fbs) and nontumor fibroblasts (N-Fbs), less is understood about the stromal contribution of metastatic lymph node fibroblasts (LN-Fbs) to the evolving microenvironment. Here, we explored the characteristics of LN-Fbs in esophageal squamous cell carcinoma (ESCC) and the interactions between fibroblasts and ESCC tumor cells in metastatic lymph nodes. Fibroblasts were isolated from tumor, nontumor and metastatic lymph node tissues from different patients with ESCC. Transcriptome sequencing was performed on the fibroblasts. Tumor growth and drug-resistance assays were carried out, and characteristics of T-Fbs, N-Fbs and LN-Fbs were determined. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to assay the culture medium of fibroblasts. The results demonstrated that fibroblasts derived from different tissues had different characteristics. Coculture with LN-Fbs conditioned medium inhibited ESCC tumor cell growth and induced chemoresistance in ESCC cells. LN-Fbs induced chemoresistance to cisplatin in ESCC cells by secreting PI16. Coculture with LN-Fbs conditioned medium decreased cisplatin-induced apoptosis in ESCC cells by regulating the p38 and JNK cell signaling pathways. Survival analyses showed that patients with high PI16 expression in Fbs of lymph nodes exhibited worse overall survival. We also examined PI16 expression in interstitial tissues in ESCC tumor samples of patients receiving platinum-based therapy postsurgery and found that high PI16 expression in tumor interstitial tissues was an independent prognostic factor for ESCC patients. In addition, an in vivo assay demonstrated that PI16 knockdown increased the sensitivity of ESCC cells to cisplatin. Our results suggest that fibroblasts in metastatic lymph nodes decrease apoptosis of ESCC cells via PI16, thereby providing a cisplatin-resistance niche and supporting ESCC tumor cells to survive in metastatic lymph nodes. PI16 is also a potential target for effectively blocking the chemoresistance niche signaling circuit in response to cisplatin.

尽管许多研究比较了肿瘤成纤维细胞 (T-Fbs) 和非肿瘤成纤维细胞 (N-Fbs)，但人们对转移性淋巴结成纤维细胞 (LN-Fbs) 对不断变化的微环境的基质贡献知之甚少。在这里，我们探讨了食管鳞状细胞癌（ESCC）中LN-Fb的特征以及转移淋巴结中成纤维细胞与ESCC肿瘤细胞之间的相互作用。从不同食管鳞癌患者的肿瘤、非肿瘤和转移性淋巴结组织中分离出成纤维细胞。对成纤维细胞进行转录组测序。进行肿瘤生长和耐药性测定，并确定 T-Fbs、N-Fbs 和 LN-Fbs 的特征。采用液相色谱-串联质谱法（LC-MS/MS）测定成纤维细胞的培养基。结果表明，来自不同组织的成纤维细胞具有不同的特性。与 LN-Fbs 条件培养基共培养可抑制 ESCC 肿瘤细胞的生长并诱导 ESCC 细胞的化疗耐药性。LN-Fbs 通过分泌 PI16 诱导 ESCC 细胞对顺铂产生化疗耐药性。与 LN-Fbs 条件培养基共培养可通过调节 p38 和 JNK 细胞信号通路减少顺铂诱导的 ESCC 细胞凋亡。生存分析显示，淋巴结 Fb 中 PI16 表达高的患者总体生存率较差。我们还检测了术后接受铂类治疗的患者的 ESCC 肿瘤样本中间质组织中 PI16 的表达，发现肿瘤间质组织中 PI16 的高表达是 ESCC 患者的独立预后因素。此外，体内测定表明，PI16 敲除增加了 ESCC 细胞对顺铂的敏感性。我们的结果表明，转移淋巴结中的成纤维细胞通过 PI16 减少 ESCC 细胞的凋亡，从而提供顺铂耐药生态位并支持 ESCC 肿瘤细胞在转移淋巴结中存活。PI16 也是有效阻断顺铂响应的化疗耐药位信号通路的潜在靶点。