Glioblastoma cell fate is differentially regulated by the microenvironments of the tumour bulk and infiltrative margin

Glioblastoma recurrence originates from invasive cells at the tumour margin that escape surgical debulking, but their biology remains poorly understood. Here we generated three somatic mouse models recapitulating the main glioblastoma driver mutations to characterise margin cells. We find that, regardless of genetics, tumours converge on a common set of neural-like cellular states. However, bulk and margin display distinct neurogenic patterns and immune microenvironments. The margin is immune-cold and preferentially follows developmental-like trajectories to produce astrocyte-like cells. In contrast, injury-like programmes dominate in the bulk, are associated with immune infiltration and generate lowly-proliferative injured neural progenitor-like (iNPCs) cells. In vivo label-retention approaches further demonstrate that iNPCs account for a significant proportion of dormant glioblastoma cells and are induced by interferon signalling within T-cell niches. These findings indicate that tumour region is a major determinant of glioblastoma cell fate and therapeutic vulnerabilities identified in bulk may not extend to the margin residuum.

Neuro-Oncology Clinical Debate: FDG PET to differentiate glioblastoma recurrence from treatment-related changes

The ability to accurately differentiate treatment related changes (i.e. pseudoprogression and radiation necrosis) from recurrent glioma remains a critical diagnostic problem in neuro-oncology. Because these entities are treated differently and have vastly different outcomes, accurate diagnosis is necessary to provide optimal patient care. In current practice, this diagnostic quandary commonly requires either serial imaging or histopathologic tissue confirmation. In this article, experts in the field debate the utility of 2-deoxy-2[ 18F]fluoro-D-glucose positron emission tomography (FDG PET) as an imaging tool to distinguish tumor recurrence from treatment-related changes in a patient with glioblastoma and progressive contrast enhancement on MR following chemoradiotherapy.

Novel weapon to conquer human glioblastoma: G-quadruplexes and neuro-inducers

Cancer cell reprogramming based on aptamers with antiproliferative properties in combination with small molecules that are used for conversion iPSCs into neurons represents a new approach to reduce the probability of glioblastoma recurrence and tumor resistance to therapy. In this research we tested several combinations of factors on whole cell cultures, derived from tumor tissue after surgical resection, and on cell cultures divided in CD133 enriched and depleted populations, as CD133 marker is believed to be characteristic for glioblastoma stem cells. We showed that CD133+ and CD133- cells have a different response to tested combinations of factors and CD133-positive cells are more stable and possess stemness properties. Thus, affecting these cells will lead to decrease of therapy resistance. Moreover, we found a combination of factors that is able to inhibit proliferation of both CD133+ and CD133- cells. Our results reveal a promising strategy to improve treatment of patients with glioblastoma.

Novel weapon to conquer human glioblastoma: G-quadruplexes and neuro-inducers

Cancer cell reprogramming based on aptamers with antiproliferative properties in combination with small molecules that are used for conversion iPSCs into neurons represents a new approach to reduce the probability of glioblastoma recurrence and tumor resistance to therapy. In this research we tested several combinations of factors on whole cell cultures, derived from tumor tissue after surgical resection, and on cell cultures divided in CD133 enriched and depleted populations, as CD133 marker is believed to be characteristic for glioblastoma stem cells. We showed that CD133+ and CD133- cells have a different response to tested combinations of factors and CD133-positive cells are more stable and possess stemness properties. Thus, affecting these cells will lead to decrease of therapy resistance. Moreover, we found a combination of factors that is able to inhibit proliferation of both CD133+ and CD133- cells. Our results reveal a promising strategy to improve treatment of patients with glioblastoma.

TBIO-21. Lnc-TALC PROMOTES O6-METHYLGUANINE-DNA METHYLTRANSFERASE EXPRESSION VIA REGULATING THE C-MET PATHWAY BY COMPETITIVELY BINDING WITH miR-20b-3p

Long noncoding RNAs (lncRNAs) have emerged as new regulatory molecules implicated in diverse biological processes, including therapeutic resistance. However, the mechanisms underlying lncRNA-mediated temozolomide (TMZ) resistance in glioblastoma (GBM) remain largely unknown. To illustrate the role of lncRNA in TMZ resistance, we induce TMZ resistant GBM cells, perform a lncRNA microarray of the parental and TMZ-resistant cells, and find an unreported lncRNA in GBM, lnc-TALC (temozolomide-associated lncRNA in glioblastoma recurrence), correlated with TMZ resistance via competitively binding miR-20b-3p to facilitate c-Met expression. A phosphorylated AKT/FOXO3 axis regulated lnc-TALC expression in TMZ-resistant GBM cells. Furthermore, lnc-TALC increased MGMT expression by mediating the acetylation of H3K9, H3K27 and H3K36 in MGMT promoter regions through the c-Met/Stat3/p300 axis. In clinical patients, lnc-TALC is required for TMZ resistance and GBM recurrence. Our results reveal that lnc-TALC in GBM could serve as a therapeutic target to overcome TMZ resistance, enhancing the clinical benefits of TMZ chemotherapy.