Hypoxic and Acidic Tumor Microenvironment-Driven AVL9 Promotes Chemoresistance of Pancreatic Ductal Adenocarcinoma via the AVL9-IκBα-SKP1 Complex.

BACKGROUND & AIMS: Gemcitabine combined with albumin-paclitaxel (AG) is a crucial therapeutic option for pancreatic ductal adenocarcinoma (PDAC). However, the response to chemotherapy is relatively poor, with rapid development of resistance. The aim of this study was to explore the mechanism of resistance to AG and to develop strategies that can sensitize the AG regimen.

METHODS: We used organoid models, patient-derived xenografts, and genetically engineered mouse models in our study. Chromatin immunoprecipitation, double luciferase assay, co-immunoprecipitation, and far-western blotting analysis were performed to investigate the mechanism. The AVL9 inhibitors were identified through protein structure analysis and molecular docking analysis, and their efficacy was verified in patient-derived xenografts, patient-derived organoids-based xenograft, and KPC models.

RESULTS: Through multistrategy screening, we identified AVL9 as a key target for AG resistance in PDAC. Its tumor-promoting effects were confirmed in our clinical cohorts. Mechanistically, HIF-1α, a hypoxia-related transcription factor, drives the expression of AVL9. AVL9 acts as a scaffold that facilitates the binding of IκBα to SKP1, leading to enhanced ubiquitination and degradation of IκBα, which further activates the nuclear factor-κB pathway. The potential AVL9-targeting inhibitor, Edotecarin, was shown to reverse AG chemo-resistance in PDAC.

CONCLUSION: AVL9 expression is driven by HIF-1α in PDAC. The physical interaction of AVL9, IκBα, and SKP1 provides a novel molecular mechanism for the abnormal activation of the nuclear factor-κB pathway. Therefore, the AVL9-targeting drug Edotecarin could be a promising therapeutic strategy for sensitizing PDAC to AG.