TMIC-35. CROSSTALK BETWEEN TAMS AND GLIOBLASTOMA STEM-LIKE CELLS IN A HYPOXIC MICROENVIRONMENT INDUCES SENESCENCE ARREST AND ENHANCED RADIORESISTANCE

Abstract

Abstract Patients with glioblastoma (GBM) have an overall survival of 15 months. These catastrophic survival rates are correlated with systematic relapses that might arise from remaining glioblastoma stem cells (GSCs) left behind after treatments. Our goal was identifying whether radioresistance of GBM is caused by GSCs and how hypoxia and TAMs affect this process. First, we established a glioblastoma-brain cortical organoid (GBM-BCOs) to model human GBM. We co-cultured GFP-labeled GBM neurosphere with BCOs for 14 days and we observed that tumor take rate was 100% for all GBM neurosphere tested. Next, we evaluated whether hypoxia enhanced TAMs migration into GBM-BCOs. We incorporated THP-1 cells into GFP-GBM-BCOS for 14 days and incubated for 24 h under normoxic or hypoxic conditions. Hypoxia increased THP-1 cells influx into GBM-BCOs. Further, we investigated whether TAMs enhanced the enrichment of GSCs in GBM neurosphere and in GBM-BCOs. We found that, co-culture of THP-1 cells with GBM neurosphere or with GBM-BCOs system, enhanced CD133+ population after 72 h hypoxic condition. In addition, IF of GBM human tissue revealed increased of CD133+ and IBA1+ cells in peri-necrotic area compared to non-necrotic area and non-necrotic tumor. To examine whether TAMs enhanced the radioresistant phenotype and the quiescent population, we irradiated GBM neurosphere grown under hypoxic and normoxic conditions with different doses of γ-rays. After irradiation, these cells were co-cultured with TAMs for 72 h under normoxic and hypoxic conditions. MTT assay showed that TAMs enhanced the radioresistant phenotype promoted by hypoxia in GBM neurosphere and an increase in quiescent markers (γ-H2AX and IL-6) were found in our co-culture model after hypoxia exposure. These results indicate, not only hypoxic condition play a key role in the GSCs enrichment and radioresistance, but also crosstalk between TAMs and GSCs promote tumor oncogenesis and contribute to an ineffective anti-tumor response.