Inhibition of gap junctions as a novel treatment strategy for medulloblastoma

Abstract

The discovery of communicative cellular networks has reshaped our understanding of brain tumor biology. Despite the growing knowledge of Cx43-based GJ as key drivers of malignant intercellular connectivity in several malignant brain tumors, the significance of GJ in MB remains largely unknown. This thesis investigates whether MB harbors tumor networks mediated by Cx43-based GJs and explores their functional role. <br/> Using IF and WB, Cx43-based GJ expression was confirmed in non-WNT/non-SHH MB cell lines (Med8A and D283). MFA and TO were used as clinically-feasible pharmacological GJ-blockers. MFA and TO demonstrated reduced intercellular connectivity pharmacologically thus enhanced sensitivity to CCNU-mediated cytotoxicity, as shown through real-time imaging and flow cytometry. RNA sequencing revealed that the combination of MFA and CCNU disrupted cellular homeostasis by activating wound-healing mechanisms in Med8A cells. <br/> A Cx43 KO model, generated using CRISPR/Cas9, confirmed the pivotal role of Cx43 in maintaining intercellular connectivity and the pharmacological inhibition from MFA and TO. The absence of Cx43 resulted in fewer neighboring connections in Med8A cells, making them more vulnerable to CCNU treatment. <br/> These findings suggest that Cx43-based GJs contribute to MB tumor networks and may play a key role in mediating resistance to chemotherapy. Targeting these networks pharmacologically offers a potential strategy to enhance the efficacy of chemotherapeutic agents like CCNU in MBs.