对顺铂（DDP）化疗的耐药性是三阴性乳腺癌（TNBC）治疗的主要挑战。 Forkhead box O4 (FOXO4) 在 DDP 抗性细胞中经常下调。然而，目前尚不清楚 FOXO4 下调是否与 DDP 耐药有关。在这里，我们研究了FOXO4与TNBC中DDP耐药之间的关系。我们通过体外选择建立了DDP耐药细胞系MDA-MB-231/DDP和BT-549/DDP。 CCK-8 和集落形成分析分析了细胞生长。计算电阻指数。评估细胞自噬。蛋白质印迹和 qRT-PCR 测量蛋白质和基因表达。通过双荧光素酶报告基因测定法测定FOXO4和TGF-β1之间的结合。MDA-MB-231/DDP和BT-549/DDP细胞中FOXO4的表达显着降低。 FOXO4过表达增加了TNBC细胞对DDP的敏感性。 DDP耐药细胞中PI3K Ⅲ类和Beclin-1水平以及LC3-II/LC3-I比值显着升高。此外，DDP 抗性细胞的自噬通量增强。 3-MA通过抑制自噬增强TNBC细胞对DDP的敏感性。 FOXO4的过表达、3-MA治疗以及它们的组合显着降低了耐药指数。 FOXO4 直接靶向 TGF-β1。此外，TGF-β1敲低可抑制自噬并恢复DDP耐药细胞对DDP的敏感性。机制上，FOXO4通过调节自噬和TGF-β1影响TNBC对DDP的耐药性。FOXO4过表达与自噬抑制剂联合使用，可显着提高TNBC耐药细胞对DDP的敏感性。这些发现揭示了FOXO4在DDP敏感性中的作用和机制，并可能为TNBC疗法的开发提供证据。版权所有©2024。由Elsevier Inc.出版。

Resistance to chemotherapy containing cisplatin (DDP) is a main challenge in the treatment of triple-negative breast cancer (TNBC). Forkhead box O4 (FOXO4) is frequently downregulated in DDP-resistant cells. However, it is unclear whether FOXO4 down-regulation is related to DDP resistance. Here, we investigated the relationship between FOXO4 and DDP resistance in TNBC.We established the DDP-resistant cell lines MDA-MB-231/DDP and BT-549/DDP through in vitro selection. CCK-8 and colony formation assays analyzed cell growth. The resistance index was calculated. Cell autophagy was evaluated. Western blotting and qRT-PCR measured protein and gene expression. The binding between FOXO4 and TGF-β1 was determined by the dual-luciferase reporter assay.FOXO4 expression was significantly lower in MDA-MB-231/DDP and BT-549/DDP cells. FOXO4 overexpression increased the sensitivity of TNBC cells to DDP. The PI3K class Ⅲ and Beclin-1 levels and LC3-II/LC3-I ratio elevated significantly in DDP-resistant cells. Moreover, the autophagic flux was enhanced in DDP-resistant cells. 3-MA enhanced the sensitivity of TNBC cells to DDP by inhibiting autophagy. Overexpression of FOXO4, treatment with 3-MA, and their combination significantly reduced the drug resistance index. FOXO4 directly targeted TGF-β1. Additionally, TGF-β1 knockdown inhibited autophagy and restored the sensitivity of DDP-resistant cells to DDP. Mechanistically, FOXO4 affected TNBC resistance to DDP by regulating autophagy and TGF-β1.FOXO4 overexpression, in combination with autophagy inhibitors, can significantly improve the sensitivity of TNBC-resistant cells to DDP. These findings reveal the role and mechanism of FOXO4 in DDP sensitivity and may provide evidence for the development of TNBC therapies.Copyright © 2024. Published by Elsevier Inc.