治疗耐药是治疗晚期结直肠癌（CRC）的首要问题。密蛋白在癌症中经常失调，其中几种蛋白正在作为新的治疗靶点和生物标志物进行研究。我们之前已经证明，结直肠癌中 Claudin-1 (CLDN1) 的表达可促进上皮间质转化、转移和抗失巢凋亡。在这里，我们假设 CLDN1 促进 CRC 中的癌症干细胞性和化疗耐药性。我们发现，CRC 中的高 CLDN1 表达与患者数据集中的癌症干性和化疗耐药信号通路相关，并且它在体外和体内促进化疗耐药。使用功能干细胞分析、蛋白质组学、生物物理结合分析和患者来源的类器官，我们发现 CLDN1 通过与肝配蛋白 A 型受体 2 (EPHA2) 直接相互作用，促进癌症干细胞特性，包括 CD44 表达、肿瘤启动潜力和化疗耐药性。 ）酪氨酸激酶。这种相互作用依赖于 CLDN1 PDZ 结合基序，通过抑制其降解来增加 EPHA2 蛋白表达，并增强下游 AKT 信号传导和 CD44 表达，以促进干性和化疗耐药性。这些结果表明 CLDN1 是药物干预和/或生物标志物开发的可行靶标。版权所有 © 2023。由 Elsevier B.V. 出版。

Therapy resistance is the primary problem in treating late-stage colorectal cancer (CRC). Claudins are frequently dysregulated in cancer, and several are being investigated as novel therapeutic targets and biomarkers. We have previously demonstrated that Claudin-1 (CLDN1) expression in CRC promotes epithelial-mesenchymal transition, metastasis, and resistance to anoikis. Here, we hypothesize that CLDN1 promotes cancer stemness and chemoresistance in CRC. We found that high CLDN1 expression in CRC is associated with cancer stemness and chemoresistance signaling pathways in patient datasets, and it promotes chemoresistance both in vitro and in vivo. Using functional stemness assays, proteomics, biophysical binding assays, and patient-derived organoids, we found that CLDN1 promotes properties of cancer stemness including CD44 expression, tumor-initiating potential, and chemoresistance through a direct interaction with ephrin type-A receptor 2 (EPHA2) tyrosine kinase. This interaction is dependent on the CLDN1 PDZ-binding motif, increases EPHA2 protein expression by inhibiting its degradation, and enhances downstream AKT signaling and CD44 expression to promote stemness and chemoresistance. These results suggest CLDN1 is a viable target for pharmacological intervention and/or biomarker development.Copyright © 2023. Published by Elsevier B.V.