The novel compensatory reciprocal interplay between neutrophils and monocytes drives cancer progression

Myeloid cells comprise the majority of immune cells in tumors, contributing to tumor growth and therapeutic resistance. Incomplete understanding of myeloid cells response to tumor driver mutation and therapeutic intervention impedes effective therapeutic design. Here, by leveraging CRISPR/Cas9-based genomic editing, we generated a mouse model that is deficient of all monocyte chemoattractant proteins (MCP). Using this strain, we effectively abolished monocyte infiltration in glioblastoma (GBM) and hepatocellular carcinoma (HCC) murine models, which were enriched for monocytes or neutrophils, respectively. Remarkably, eliminating monocyte chemoattraction invokes a significant compensatory neutrophil influx in GBM, but not in HCC. Single-cell RNA sequencing revealed that intratumoral neutrophils promoted proneural-to-mesenchymal transition in GBM, and supported tumor aggression by facilitating hypoxia response via TNF production. Importantly, genetic or pharmacological inhibiting neutrophil in HCC or qMCP-KO GBM extended the survival of tumor-bearing mice. Our findings emphasize the importance of targeting both monocytes and neutrophils simultaneously for cancer immunotherapy. In BriefEliminating monocyte chemoattraction invokes compensatory neutrophil influx in tumor, and vice versa, rendering current myeloid-targeted therapies ineffective. Using genetic and pharmacological approaches combined with novel mouse models of GBM and HCC, we provide credence advocating for combinational therapies aiming at inhibiting both monocytes and neutrophils simultaneously. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=153 SRC="FIGDIR/small/500690v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@bbbae5org.highwire.dtl.DTLVardef@eb3eecorg.highwire.dtl.DTLVardef@702696org.highwire.dtl.DTLVardef@f54734_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights* Blocking monocyte chemoattraction results in increased neutrophil infiltration. * Increased neutrophil recruitment induces GBM PN to MES transition. * Inhibiting neutrophil infiltration in monocyte-deficient tumors improves mouse GBM survival. * Blocking neutrophil, but not monocyte, infiltration in HCC prolongs mouse survival.