人表皮生长因子受体2阳性（HER2）乳腺癌（BC）约占所有乳腺癌的五分之一，具有高度侵袭性、复发率高和预后不良的特点。多项研究表明，生长因子受体结合蛋白 7 (GRB7) 可能是肿瘤诊断和预后的潜在治疗靶点。然而，GRB7在HER2 BC中的作用及其潜在机制尚未完全阐明。本研究旨在探讨GRB7在HER2 BC中的生物学功能和调控机制。利用TCGA、GEO和CancerSEA数据库进行生物信息学分析，评估GRB7的临床意义。采用RT定量PCR、蛋白质印迹和免疫荧光来评估GRB7在BC细胞系和组织中的表达。采用MTT、EdU、集落形成、伤口愈合、Transwell和异种移植实验来探讨GRB7在HER2 BC中的生物学功能。 SK-BR-3细胞转染GRB7 siRNA后，进行RNA测序来分析与GRB7相关的信号通路。采用染色质免疫沉淀分析（ChIP）和荧光素酶报告基因检测来阐明GRB7在HER2 BC中的潜在分子调控机制。GRB7显着上调，并且与BC，尤其是HER2 BC中的不良预后相关。 GRB7 的过表达增加了 HER2  BC 细胞的增殖、迁移、侵袭和集落形成，而 GRB7 的缺失在 HER2  BC 细胞中具有相反的作用并抑制异种移植物生长。 ChIP-PCR和荧​​光素酶报告基因检测显示TCF12直接结合GRB7基因的启动子以促进其转录。 GRB7 通过与 Notch1 相互作用激活 Wnt/β-catenin 通路和其他信号传导（即 AKT、ERK），促进 HER2  BC 上皮间质转化 (EMT) 进展。此外，强迫GRB7过度表达激活Wnt/β-catenin促进EMT进展，并部分挽救TCF12沉默诱导的HER2 BC增殖、迁移和侵袭的抑制。我们的工作阐明了GRB7在HER2 BC中的致癌作用，这可以作为预后指标和有希望的治疗目标。© 2024。作者。

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC), which accounts for approximately one-fifth of all BCs, are highly invasive with a high rate of recurrence and a poor prognosis. Several studies have shown that growth factor receptor-bound protein 7 (GRB7) might be a potential therapeutic target for tumor diagnosis and prognosis. Nevertheless, the role of GRB7 in HER2+ BC and its underlying mechanisms have not been fully elucidated. The aim of this study was to investigate the biological function and regulatory mechanism of GRB7 in HER2+ BC.Bioinformatics analysis was performed using the TCGA, GEO and CancerSEA databases to evaluate the clinical significance of GRB7. RT quantitative PCR, western blot and immunofluorescence were conducted to assess the expression of GRB7 in BC cell lines and tissues. MTT, EdU, colony formation, wound healing, transwell, and xenograft assays were adopted to explore the biological function of GRB7 in HER2+ BC. RNA sequencing was performed to analyze the signaling pathways associated with GRB7 in SK-BR-3 cells after the cells were transfected with GRB7 siRNA. Chromatin immunoprecipitation analysis (ChIP) and luciferase reporter assay were employed to elucidate the potential molecular regulatory mechanisms of GRB7 in HER2+ BC.GRB7 was markedly upregulated and associated with poor prognosis in BC, especially in HER2+ BC. Overexpression of GRB7 increased the proliferation, migration, invasion, and colony formation of HER2+ BC cells, while depletion of GRB7 had the opposite effects in HER2+ BC cells and inhibited xenograft growth. ChIP-PCR and luciferase reporter assay revealed that TCF12 directly bound to the promoter of the GRB7 gene to promote its transcription. GRB7 facilitated HER2+ BC epithelial-mesenchymal transition (EMT) progression by interacting with Notch1 to activate Wnt/β-catenin pathways and other signaling (i.e., AKT, ERK). Moreover, forced GRB7 overexpression activated Wnt/β-catenin to promote EMT progression, and partially rescued the inhibition of HER2+ BC proliferation, migration and invasion induced by TCF12 silencing.Our work elucidates the oncogenic role of GRB7 in HER2+ BC, which could serve as a prognostic indicator and promising therapeutic target.© 2024. The Author(s).