Meejeong Kim , Jae Hoon Jeong
The treatment of Glioblastoma Multiforme (GBM), a highly malignant brain tumor, is critically hindered by the ineffectiveness of current modalities such as surgery, radiation and chemotherapy. These traditional methods fail to completely remove the tumor mass and lack the ability to discriminate between cancerous and normal brain cells, often resulting in collateral damage to healthy tissue and recurrence of the disease. This underscores an urgent necessity to develop novel therapeutic strategies that can target tumor cells with precision, offering hope for improved survival rates and quality of life for GBM patients. This study investigates targeted therapy, focusing on the Integrated Stress Response (ISR) that cancer cells harness to survive hypoxic stress. Specifically, it demonstrates that Eukaryotic Translation Initiation Factor 2 Alpha Kinase 1 (EIF2AK1), which encodes Heme-Regulated Inhibitor (HRI) kinase, is activated under hypoxia and co-expressed with the glioma stem cell marker Sex Determining Region Y-box 2 (SOX2), which specifically happens in glioma cells, increasing the targeted accuracy of the repurposing drug. This correlation, indicating hypoxia-driven stemness, is confirmed at both the genetic level and through Gene Set Enrichment Analysis (GSEA). Furthermore, GSEA in spatial transcriptomics shows hypoxia-induced glycolysis, disrupting the tumor microenvironment and causing necrotic cell death. Stemness phenotype is induced in the peripheral cells due to the unfavourable hypoxic environment. Hemin, an HRI inhibitor, has been repurposed to inhibit ISR and mitigate hypoxia. Treatment with hemin on the Uppsala 87 Malignant Glioma (U87 MG) cell line resulted in IC50 values of 23.50 μM and 52.46 μM at 24 and 48 hours, respectively, surpassing Temozolomide's efficacy. A decrease in HRI expression after the hemin treatment suggests the and ISR activity and, potentially, hypoxia. This would reverse the unfavourable microenvironment so that the stemness phenotype doesn’t spread. Potentially, invasiveness and recurrences of GBM in clinic situation would decrease, thus potentially improving patient prognosis. The therapeutic potential of hemin is enhanced by its ability to kill glioma cells directly and accurately in the glioma cell in original Tumor Microenvironment (TME) when cells are proliferating with adequate oxygen. Therefore, this study demonstrates the therapeutic potential of repurposing hemin, an HRI inhibitor, to precisely target hypoxia-induced glioma stem cells in glioblastomas, disrupting the aggressive TME to potentially improve patient prognosis.