F-box only protein 8 (FBXO8) is a recently identified member of the F-box proteins, showcasing its novelty in this protein family. Extensive research has established FBXO8's role as a tumor suppressor in various cancers, including hepatocellular carcinoma, and colorectal cancer, Nevertheless, its functional, mechanistic, and prognostic roles in primary and metastatic breast cancer, particularly in different molecular subtypes of breast cancer, various stages, as well as its potential implications in immunotherapy, tumor microenvironment, and prognostic survival among breast cancer patients, remain unexplored. In this article, we employed a multi-dimensional investigation leveraging TCGA, TIMER, TISIDB, STRING, MEXPRESS, UALCAN, and cBioPortal databases to explore the underlying suppression mechanism of FBXO8 in breast cancer. FBXO8 negatively correlates with MYC, NOTCH, WNT and inflammatory signaling pathways in breast tumor microenvironment. Furthermore we conducted RT-PCR, western blot, cell proliferation, cell migration, and mRNA target gene RT-PCR analyses to elucidate the role of FBXO8 in breast cancer progression. Mechanistically, PTEN and FBXW7 expression were down-regulated and MYC, IL10, IL6, NOTCH1, WNT6 mRNA expressions were up-regulated in FBXO8 knockdown cell lines. c-MYC silenced cells showed an increase in FBXO8 protein level, which suggests a negative feedback loop between FBXO8 and c-MYC to control breast cancer metastasis. These findings illuminate the novel role of FBXO8 as a prognostic and therapeutic target across different molecular subtypes of breast cancer. Finally, through the utilization of virtual screening and Molecular Dynamics simulations, we successfully identified two FDA-approved medications, Ledipasvir and Paritaprevir, that demonstrated robust binding capabilities and interactions with FBXO8.

仅 F-box 蛋白 8 (FBXO8) 是最近鉴定的 F-box 蛋白成员，展示了其在该蛋白家族中的新颖性。广泛的研究已确定 FBXO8 在各种癌症（包括肝细胞癌和结直肠癌）中作为肿瘤抑制因子的作用，然而，其在原发性和转移性乳腺癌中的功能、机制和预后作用，特别是在乳腺癌的不同分子亚型、不同阶段中的功能、机制和预后作用及其对免疫治疗、肿瘤微环境和乳腺癌患者预后生存的潜在影响仍有待探索。在本文中，我们利用 TCGA、TIMER、TISIDB、STRING、MEXPRESS、UALCAN 和 cBioPortal 数据库进行多维度研究，探讨 FBXO8 在乳腺癌中的潜在抑制机制。FBXO8 与乳腺肿瘤微环境中的 MYC、NOTCH、WNT 和炎症信号通路呈负相关。此外，我们还进行了 RT-PCR、蛋白质印迹、细胞增殖、细胞迁移和 mRNA 靶基因 RT-PCR 分析，以阐明 FBXO8 在乳腺癌进展中的作用。从机制上讲，FBXO8敲低细胞系中PTEN和FBXW7表达下调，MYC、IL10、IL6、NOTCH1、WNT6 mRNA表达上调。c-MYC 沉默细胞显示 FBXO8 蛋白水平增加，这表明 FBXO8 和 c-MYC 之间存在控制乳腺癌转移的负反馈环。这些发现阐明了 FBXO8 作为乳腺癌不同分子亚型的预后和治疗靶点的新作用。最后，通过利用虚拟筛选和分子动力学模拟，我们成功鉴定了两种 FDA 批准的药物 Ledipasvir 和 Paritaprevir，它们表现出与 FBXO8 的强大结合能力和相互作用。