Glioblastoma and the Blood-Brain Barrier: Insights into Barrier Integrity and Tumour-Endothelial Interactions
Author
Jespersen, Stefan Holmgård
Term
4. term
Publication year
2025
Pages
40
Abstract
Glioblastoma (GBM) is an aggressive brain tumor whose treatment is often limited by the blood–brain barrier (BBB) and the tumor-associated blood–brain tumor barrier (BBTB), which restrict drug entry. Although GBM is frequently assumed to disrupt BBB integrity, this study tested whether tumor cells can instead reinforce the barrier. An in vitro co-culture model was established using primary porcine brain capillary endothelial cells with either the long-established U87 GBM cell line, a low-passage patient-derived GBM line (T10), or primary porcine astrocytes as a non-malignant reference. Barrier function was evaluated by transendothelial electrical resistance (TEER), and markers of barrier integrity (Claudin-5 and ZO-1) and regulatory proteins (MFSD2A and CD93) were quantified at mRNA and protein levels. Tunicamycin and metoclopramide were used to inhibit MFSD2A and CD93, respectively, to probe mechanisms. Across nine days of co-culture, T10 produced the strongest barrier reinforcement, with higher TEER and Claudin-5 expression than U87 and astrocytes. This effect persisted despite single-target inhibition of MFSD2A or CD93, suggesting redundant tumor-derived pro-barrier signaling. Discrepancies between mRNA and protein responses after metoclopramide point to possible post-transcriptional regulation or biological variation. The modest effects of astrocytes support a GBM-specific phenomenon. Overall, these findings challenge the notion that GBM universally compromises the BBB and indicate that reinforced BBTB function may contribute to therapeutic resistance, underscoring the need for transient, controlled barrier modulation to improve drug delivery without long-term BBB compromise.
Glioblastom (GBM) er en aggressiv hjernetumor, hvor behandling ofte hindres af blod–hjerne-barrieren (BBB) og den tumorassocierede variant (BBTB), som begrænser lægemiddelpassage. Det antages ofte, at GBM svækker BBB, men dette projekt undersøgte i stedet, om tumorceller kan forstærke barrieren. Der blev opbygget in vitro-samkulturer med primære porcine hjernens kapillærendotelceller sammen med enten den etablerede GBM-cellelinje U87, en lav-passager patientafledt GBM-cellelinje (T10) eller primære porcine astrocytter som ikke-malign reference. Barrierefunktionen blev målt med transendotelial elektrisk modstand (TEER), og markører relateret til barriereintegritet (Claudin-5 og ZO-1) samt regulerende proteiner (MFSD2A og CD93) blev kvantificeret på mRNA- og proteinniveau. Tunicamycin og metoclopramid blev anvendt til at hæmme henholdsvis MFSD2A og CD93 for at belyse mekanismer. Over ni dages samkultur gav T10 den tydeligste barriereforstærkning med højere TEER og Claudin-5-udtryk end U87 og astrocytter. Effekten bestod trods enkeltvis hæmning af MFSD2A eller CD93, hvilket peger på redundante, tumorafledte pro-barrieresignalveje. Uoverensstemmelser mellem mRNA- og proteinrespons efter metoclopramid indikerer mulig posttranskriptionel regulering eller biologisk variation. De beskedne effekter af astrocytter understøtter, at fundene er GBM-specifikke. Samlet udfordrer resultaterne antagelsen om, at GBM altid kompromitterer BBB, og peger på, at forstærket BBTB kan bidrage til behandlingsresistens, hvilket fremhæver behovet for strategier til midlertidig, kontrolleret barriere-modulation for at forbedre lægemiddellevering uden varig skade på BBB.
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