Tumor-associated monocytes promote mesenchymal transformation through EGFR signaling in glioma

The role of brain immune compartments in glioma evolution remains elusive. We profiled immune cells in glioma microenvironment and the matched peripheral blood from 11 patients at a single-cell level. Notably, glioblastoma exhibits specific infiltration of certain blood-originated monocytes expressing EGFR ligands including EREG and AREG, coined as tumor-associated monocytes (TAMo). TAMo infiltration is mutually exclusive with EGFR alterations (P = 0.019), while co-occurring with mesenchymal subtype (P = 4.7x10-7) and marking worse prognosis (P = 0.004 and 0.032 in two independent cohorts). Evolutionary analysis of initial-recurrent glioma pairs and single-cell study of a multi-centric glioblastoma reveals remarkable association between elevated TAMo and glioma mesenchymal transformation. Further analysis identifies FOSL2 as a master regulator of TAMo. The roles of FOSL2-EREG/AREG-EGFR signaling axis in promoting glioma invasion were verified experimentally. Collectively, we have identified TAMo in tumor microenvironment and revealed its driving role in activating EGFR signaling to shape glioma evolution. The GB or peripheral blood cell suspension was loaded into Chromium microfluidic chips with 3’ (v3) chemistry and barcoded with a 10× Chromium Controller (10X Genomics). RNA from the barcoded cells was subsequently reverse-transcribed and sequencing libraries constructed with reagents from a Chromium Single Cell 3’ (v3) reagent kit (10X Genomics) according to the manufacturer’s recommendations. Sequencing was performed with Illumina (NovaSeq) according to the manufacturer’s recommendations (Illumina). ----- Authors state: We are currently unable to deposit the raw data due to privacy concerns, but will have the raw data available once we obtain permission from our institutions. Please contact the submitter directly regarding access to raw data on a case-by-case basis.