A novel treatment for glioblastoma based on Taxol activation of PC1/3-depleted macrophages: evidence from a proteomic and functional study.

Tumor-associated macrophages contribute to tumor pathogenesis and represent an attractive therapeutic target. We report that the proprotein convertase PC1/3 inhibits the TLR4 Myd88-pathway induced in macrophages by the anti-cancer agent Taxol. Thus, PC1/3 knock-down in these cells exacerbates the TLR4 MyD88-dependent pathway triggered by Taxol. In PC1/3 knock-down macrophages, Taxol drives the secretion of pro-inflammatory cytokines, inhibits STAT3 signaling and counteracts tumor-supportive activities, thus inhibiting viability, growth and invasion of glioblastoma cells. Proteomic analyses indicate that their secretomes are characterized by a unique protein profile supporting a specific paracrine anti-tumoral effect. These findings unravel the potential value of a new therapeutic strategy combining PC1/3 inhibition and activation of the TLR4 MyD88-dependent pathway to switch intra-tumoral macrophages toward an anti-tumoral immunophenotype.