Macrophages increase the resistance of pancreatic adenocarcinoma cells to gemcitabine by upregulating cytidine deaminase.

Tumor-associated macrophages play a central role in tumor progression and metastasis. Macrophages can also promote the resistance of malignant cells to chemotherapy by stimulating the upregulation of cytidine deaminase, an intracellular enzyme that catabolizes the active form of gemcitabine. Targeting macrophage-dependent chemoresistance may reduce tumor-associated morbidity and mortality.