越来越多的证据表明，FBXW7在食管鳞状细胞癌（ESCC）中具有高频突变的现象。然而，FBXW7的功能，尤其是突变的作用尚不清楚。本研究旨在探究FBXW7功能丧失和潜在机制在ESCC中的重要性。采用免疫荧光技术澄清FBXW7在ESCC细胞中的定位和主要形式。对ESCC组织的Sanger测序进行FBXW7突变探索。进行增殖、集落、侵袭和迁移的实验，以检验FBXW7在ESCC细胞中的功能作用，包括体内外。使用实时PCR、免疫印迹、GST-pulldown、LC-MS/MS和共同免疫沉淀法，探究FBXW7功能失活在ESCC细胞中作用的分子机制。采用免疫组化染色法探究ESCC组织中FBXW7和MAP4的表达情况。在ESCC细胞中，主要的FBXW7形式是细胞质中的β转录本。FBXW7的功能失活导致MAPK信号通路的激活，并上调下游的MMP3和VEGFA，从而增强了肿瘤的增殖、侵袭和迁移。在筛选的五种突变形式中，S327X（X表示截短突变）具有类似FBXW7缺失的效应，导致FBXW7在ESCC细胞中失活。另外三个点突变形式S382F、D400N和R425C削弱了但没有消除FBXW7的功能。另一个截短突变形式S598X位于WD40结构域之外，在ESCC细胞中只引起微弱的FBXW7削弱。值得注意的是，MAP4被鉴定为FBXW7的潜在靶标。MAP4的苏氨酸T521被CHEK1磷酸化，发挥了FBXW7相关降解系统中的关键作用。免疫组化染色表明，FBXW7失活与ESCC患者的肿瘤分期和生存时间较短有关。单因素和多因素Cox比例风险回归分析表明，高FBXW7和低MAP4是独立的预后指标和前瞻性更长的生存。此外，联合治疗方案包括MK-8353抑制ERK磷酸化和贝伐单抗抑制VEGFA，在体内抑制FBXW7失活的异种移植瘤的生长。本研究提供了证据，表明FBXW7功能丧失促进了ESCC通过MAP4过度表达和ERK磷酸化，并且这种新的FBXW7/MAP4/ERK轴可能是ESCC治疗的有效靶点。©2023年。作者（们）。

Increasing evidence suggests that FBXW7 has a high frequency of mutations in esophageal squamous cell carcinoma (ESCC). However, the function of FBXW7, especially the mutations, is not clear. This study was designed to investigate the functional significance of FBXW7 loss of function and underlying mechanism in ESCC.Immunofluorescence was applied to clarify the localization and main isoform of FBXW7 in ESCC cells. Sanger sequencing were performed to explore mutations of FBXW7 in ESCC tissues. Proliferation, colony, invasion and migration assays were performed to examine the functional roles of FBXW7 in ESCC cells in vitro and in vivo. Real-time RT-PCR, immunoblotting, GST-pulldown, LC-MS/MS and co-immunoprecipitation assay were used to explore the molecular mechanism underlying the actions of FBXW7 functional inactivation in ESCC cells. Immunohistochemical staining were used to explore the expression of FBXW7 and MAP4 in ESCC tissues.The main FBXW7 isoform in ESCC cells was the β transcript in the cytoplasm. Functional inactivation of FBXW7 led to activation of the MAPK signaling pathway and upregulation of the downstream MMP3 and VEGFA, which enhanced tumor proliferation cell invasion and migration. Among the five mutation forms screened, S327X (X means truncated mutation) had an effect similar to the FBXW7 deficiency and led to the inactivation of FBXW7 in ESCC cells. Three other point mutations, S382F, D400N and R425C, attenuated but did not eliminate FBXW7 function. The other truncating mutation, S598X, which was located outside of the WD40 domain, revealed a tiny attenuation of FBXW7 in ESCC cells. Notably, MAP4 was identified as a potential target of FBXW7. The threonine T521 of MAP4, which was phosphorylated by CHEK1, played a key role in the FBXW7-related degradation system. Immunohistochemical staining indicated that FBXW7 loss of function was associated with tumor stage and shorter survival of patients with ESCC. Univariate and multivariate Cox proportional hazards regression analyses showed that high FBXW7 and low MAP4 was an independent prognostic indicator and prospective longer survival. Moreover, a combination regimen that included MK-8353 to inhibit the phosphorylation of ERK and bevacizumab to inhibit VEGFA produced potent inhibitory effects on the growth of FBXW7 inactivation xenograft tumors in vivo.This study provided evidence that FBXW7 loss of function promoted ESCC via MAP4 overexpression and ERK phosphorylation, and this novel FBXW7/MAP4/ERK axis may be an efficient target for ESCC treatment.© 2023. The Author(s).