Metabolic reprogramming of hypoxic tumour-associated macrophages through CSF-1R targeting favours treatment efficiency in colorectal cancers

Abstract

Tumor-associated macrophages participate in the complex network of support that favors tumor growth. Among the various strategies that have been developed to target these cells, blockade of the CSF-1R receptor is one of the most promising one. Here, we characterize the resulting state of human macrophages exposed to a CSF-1R kinase inhibitor. We find that CSF-1R receptor inhibition in human macrophages is able to impair cholesterol synthesis, fatty acid metabolism and hypoxia-driven expression of dihydropyrimidine dehydrogenase, an enzyme responsible for the 5-fluorouracil macrophage-mediated chemoresistance. We show that this inhibition of the CSF-1R receptor leads to a downregulation of the expression of SREBP2, a transcription factor that controls cholesterol and fatty acid synthesis. We also show that the inhibition of ERK1/2 phosphorylation resulting from targeting the CSF-1R receptor destabilizes the expression of HIF2 in hypoxia resulting in the downregulation of dihydropyrimidine dehydrogenase expression restoring the sensitivity to 5-fluorouracil in colorectal cancer. These results reveal the unexpected metabolic rewiring resulting from the CSF-1R receptor targeting of human macrophages in tumors.