FBXO7 通过靶向 TMED10 进行泛素介导的降解和激活 wnt 信号传导来促进 T-ALL 的化疗耐药性 Free

Acute T-cell lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy derived from T-lineage progenitor cells, accounting for 15–20% of ALL cases. While intensive chemotherapy and hematopoietic stem cell transplantation have improved remission rates, relapse and chemoresistance remain major clinical obstacles. Aberrant Wnt/β-catenin signaling has been implicated in T-ALL pathogenesis and therapy resistance. However, the mechanisms regulating Wnt protein trafficking in T-ALL are poorly understood.

The COPII vesicle complex mediates the transport of secreted proteins, including Wnt ligands, from the endoplasmic reticulum (ER) to the Golgi. TMED10, a transmembrane protein and COPII component, is involved in protein sorting and secretion. Using co-immunoprecipitation and live-cell imaging, we confirmed that TMED10 physically interacts with Wnt proteins and functions as a cargo receptor to facilitate their ER-to-Golgi transport via COPII vesicles. TMED10 colocalizes with Wnt proteins at ER exit sites and facilitates their transport to the Golgi. We then performed quantitative proteomics following TMED10 immunoprecipitation and identified FBXO7, an F-box–containing E3 ubiquitin ligase, as a putative regulator of TMED10 turnover. Co-immunoprecipitation and ubiquitination assays confirmed that FBXO7 physically interacts with TMED10 and mediates its K48-linked polyubiquitination, targeting it for proteasomal degradation. RNAi-mediated knockdown of FBXO7 in multiple T-ALL cell lines led to the accumulation of TMED10 protein, reduced Wnt secretion, and suppression of β-catenin nuclear translocation and transcriptional activity, as confirmed by TOPFlash reporter assays and immunoblotting for active β-catenin. Conversely, FBXO7 overexpression reduced TMED10 levels, enhanced Wnt signaling, and upregulated the expression of drug-resistance–associated genes such as MDR1, ABCG2, and BCL2.

Functional assays demonstrated that FBXO7 knockdown reduced T-ALL cell proliferation, impaired clonogenic potential, and induced apoptosis in vitro. Limiting dilution assays further confirmed a reduction in leukemia-initiating cell frequency upon FBXO7 inhibition. Rescue experiments in FBXO7-silenced cells showed that TMED10 re-expression reversed the suppression of Wnt signaling, supporting the mechanistic link between TMED10 degradation and pathway activation.

Bioinformatic analysis of public T-ALL datasets (GSE26713, GSE13159) revealed that FBXO7 is significantly upregulated in relapsed and refractory T-ALL patient samples and its high expression correlates with poor overall survival. In a cohort of relapsed T-ALL patients from our clinical center, elevated FBXO7 protein levels were confirmed by immunohistochemistry and correlated with increased β-catenin activity. In xenograft mouse models, FBXO7 knockdown significantly delayed leukemia progression, reduced splenic and bone marrow infiltration by human CD7⁺ T-ALL cells, and prolonged survival. Flow cytometry showed a marked reduction in CD34⁺/CD7⁺ leukemia stem-like populations following FBXO7 silencing. Furthermore, ex vivo treatment of patient-derived T-ALL cells with an FBXO7-targeted shRNA or CRISPR/Cas9 approach suppressed Wnt target gene expression and restored sensitivity to chemotherapeutic agents such as vincristine and dexamethasone. These effects were not observed in control cells or those lacking TMED10, confirming the specificity of the FBXO7–TMED10–Wnt axis in mediating chemoresistance.

In summary, our study identifies a novel mechanism of Wnt pathway activation in T-ALL, whereby FBXO7 promotes the ubiquitin-dependent degradation of TMED10, facilitating Wnt ligand secretion and downstream oncogenic signaling. These findings position FBXO7 as a potential biomarker of high-risk, chemoresistant T-ALL and a therapeutic target to overcome relapse. Targeting the FBXO7–TMED10–Wnt signaling axis may provide a new avenue for eradicating leukemia-initiating cells and improving long-term outcomes in T-ALL patients.