Mitochondrial complex I inhibition remodels the PDAC fibrotic microenvironment via LOXL2 suppression to potentiate chemo-immunotherapy

Abstract

Purpose

Pancreatic ductal adenocarcinoma (PDAC) exhibits a highly desmoplastic tumor microenvironment that contributes to therapeutic resistance. Cancer-associated fibroblasts (CAFs) are major drivers of extracellular matrix deposition. Considering CAF heterogeneity and plasticity, metabolic modulation may represent an alternative strategy to regulate stromal function. This study investigated whether targeting mitochondrial metabolism could attenuate CAF-mediated fibrosis and improve therapeutic responses in PDAC.

Methods

The effects of carboxyamidotriazole orotate (CTO), an oxidative phosphorylation inhibitor, were evaluated in vitro and in PDAC mouse models. LOXL2 expression, collagen deposition, and fibrosis-related gene signatures were analyzed using molecular and histological approaches. Combination treatments with anti-PD-1 therapy and gemcitabine were further assessed.

Results

CTO treatment reduced LOXL2 expression and downregulated collagen deposition-associated gene signatures in CAFs. In vivo, CTO attenuated stromal fibrosis and altered tumor microenvironmental features. Combination of CTO with anti-PD-1 therapy induced a pronounced anti-fibrotic phenotype. Integration of CTO into gemcitabine-based chemo-immunotherapy was associated with improved therapeutic responses and stromal remodeling.

Conclusion

Mitochondrial metabolic inhibition represents a feasible strategy to modulate CAF-mediated fibrosis in PDAC. CTO-mediated stromal reprogramming may enhance responses to chemo- and immunotherapy, providing a translational rationale for metabolism-based combination strategies.