TGF-β Receptor Inhibitors Target the CD44high/Id1high Glioma-Initiating Cell Population in Human Glioblastoma

SummaryGlioma-initiating cells (GICs), also called glioma stem cells, are responsible for tumor initiation, relapse, and therapeutic resistance. Here, we show that TGF-β inhibitors, currently under clinical development, target the GIC compartment in human glioblastoma (GBM) patients. Using patient-derived specimens, we have determined the gene responses to TGF-β inhibition, which include inhibitors of DNA-binding protein (Id)-1 and -3 transcription factors. We have identified a cell population enriched for GICs that expresses high levels of CD44 and Id1 and tend to be located in a perivascular niche. The inhibition of the TGF-β pathway decreases the CD44high/Id1high GIC population through the repression of Id1 and Id3 levels, therefore inhibiting the capacity of cells to initiate tumors. High CD44 and Id1 levels confer poor prognosis in GBM patients.

► The inhibition of the TGF-β pathway induces the repression of Id1 and Id3 in GBM
► CD44 and Id1 are markers of GICs and confer poor prognosis in GBM
► TGF-β inhibitors target CD44high/Id1high GICs through the repression of Id1 and Id3
► TGF-β inhibitors prevent tumor initiation