[PDF][PDF] Impeding macrophage entry into hypoxic tumor areas by Sema3A/Nrp1 signaling blockade inhibits angiogenesis and restores antitumor immunity

A Casazza, D Laoui, M Wenes, S Rizzolio, N Bassani… - Cancer cell, 2013 - cell.com
A Casazza, D Laoui, M Wenes, S Rizzolio, N Bassani, M Mambretti, S Deschoemaeker
Cancer cell, 2013cell.com
Recruitment of tumor-associated macrophages (TAMs) into avascular areas sustains tumor
progression; however, the underlying guidance mechanisms are unknown. Here, we report
that hypoxia-induced Semaphorin 3A (Sema3A) acts as an attractant for TAMs by triggering
vascular endothelial growth factor receptor 1 phosphorylation through the associated
holoreceptor, composed of Neuropilin-1 (Nrp1) and PlexinA1/PlexinA4. Importantly,
whereas Nrp1 levels are downregulated in the hypoxic environment, Sema3A continues to …
Summary
Recruitment of tumor-associated macrophages (TAMs) into avascular areas sustains tumor progression; however, the underlying guidance mechanisms are unknown. Here, we report that hypoxia-induced Semaphorin 3A (Sema3A) acts as an attractant for TAMs by triggering vascular endothelial growth factor receptor 1 phosphorylation through the associated holoreceptor, composed of Neuropilin-1 (Nrp1) and PlexinA1/PlexinA4. Importantly, whereas Nrp1 levels are downregulated in the hypoxic environment, Sema3A continues to regulate TAMs in an Nrp1-independent manner by eliciting PlexinA1/PlexinA4-mediated stop signals, which retain them inside the hypoxic niche. Consistently, gene deletion of Nrp1 in macrophages favors TAMs' entrapment in normoxic tumor regions, which abates their pro-angiogenic and immunosuppressive functions, hence inhibiting tumor growth and metastasis. This study shows that TAMs' heterogeneity depends on their localization, which is tightly controlled by Sema3A/Nrp1 signaling.
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