TRIM29 promotes pancreatic cancer MVI via IκBα K48-ubiquitination and NF-κB activation in CXCL5⁺ epithelial cells.

PURPOSE: To investigate the mechanisms underlying the interaction and influence between microvascular invasion (MVI), which contributes to metastasis and poor prognosis of pancreatic ductal adenocarcinoma (PDAC), and tumor microenvironment. METHODS: This study employed an integrative multi-omics approach, combining spatial proteomics (multiplex immunofluorescence), transcriptome sequencing, and single-cell RNA sequencing (scRNA-seq) to profile MVI⁺ and MVI⁻ PDAC samples. The functional role of key genes was validated through in vitro and in vivo assays (migration, invasion, xenograft models). Molecular mechanisms were dissected using Co-IP, ubiquitination assays, and ChIP-qPCR. RESULTS: The epithelial-mesenchymal transition (EMT) process was significantly activated in MVI⁺ tumors, with EMT-positive cells located spatially closer to microvessels. scRNA-seq identified a distinct epithelial subpopulation characterized by CXCL5 that exhibited a strong EMT phenotype and was enriched in MVI⁺ samples. Mechanistically, the transcription factor ZBTB7B was found to directly promote TRIM29 transcription. TRIM29 directly binds to IκBα via its BB2 domain and catalyzes its K48-linked ubiquitination and proteasomal degradation. This event relieves the inhibition of the NF-κB signaling pathway, leading to its activation and the subsequent induction of EMT, ultimately enhancing the invasive and metastatic capabilities of pancreatic cancer cells. Clinical correlation analysis revealed a significant negative correlation between TRIM29 and IκBα protein levels, and high TRIM29, low IκBα, and high CXCL5⁺EMT levels were all associated with poor prognosis. CONCLUSION: This study reveals the critical role of the ZBTB7B-TRIM29-IκBα-NF-κB signaling axis in promoting EMT in CXCL5-marked pancreatic cancer cells surrounding MVI, establishing TRIM29 as a potential therapeutic target for inhibiting early metastasis of PDAC. CLINICAL RELEVANCE: This study provides deep insights into the biology of MVI, a crucial prognostic indicator in pancreatic cancer. TRIM29 expression could serve as a potential biomarker for predicting tumor aggressiveness and patient outcome. More importantly, targeting TRIM29’s E3 ligase activity or its interaction with IκBα represents a promising novel therapeutic strategy to inhibit early metastasis and improve the resectability of pancreatic cancer.