Maria Paola Demichelis

Background: Adult diffuse gliomas represent one of the most aggressive types of brain tumors. Proton therapy offers a minimally invasive treatment option whose biological effectiveness may be enhanced through nuclear reactions involving boron atoms, leading to the emission of high-LET α-particles. In this study, we investigated the potential enhancement of radiation-induced damage of a novel boron-conjugated, ATP-competitive SRC kinase inhibitor, in the U-87 MG glioma cell line and its isogenic cell line stably expressing the IDH1 R132H mutation. Methods: Glioma cells were exposed to either proton or X-ray irradiation to assess whether any enhancement associated with this boron-delivery strategy was specific to proton interactions. Cell survival assays and analyses of DNA damage responses were conducted in both cell lines. Results: While no significant synergistic effects were observed in survival endpoints, differences emerged at the level of early DNA damage effects, with IDH1-mutant glioma cells displaying an enhanced acute response following combined treatment with proton irradiation. Conclusions: These findings support further pharmacological development of boron-based SRC-targeted strategies and underscore the importance of tailoring therapeutic approaches to specific glioma molecular subtypes.

Nanoparticles composed of inorganic boron-containing compounds represent a promising candidate as ¹⁰B carriers for BNCT. This study focuses on the synthesis, characterization, and assessment of the biological activity of composite nanomaterials based on boron carbide (B₄C). Boron carbide is a compelling alternative to borated molecules due to its high volumetric B content, prolonged retention in biological systems, and low toxicity. These attributes lead to a substantial accumulation of B in tissues, eliminating the need for isotopically enriched compounds. In our approach, B₄C nanoparticles were included in composite nanostructures with ultrasmall superparamagnetic nanoparticles (SPIONs), coated with poly (acrylic acid), and further functionalized with the fluorophore DiI. The successful internalization of these nanoparticles in HeLa cells was confirmed, and a significant uptake of ¹⁰B was observed. Micro-distribution studies were conducted using intracellular neutron autoradiography, providing valuable insights into the spatial distribution of the nanoparticles within cells. These findings strongly indicate that the developed nanomaterials hold significant promise as effective carriers for ¹⁰B in BNCT, showcasing their potential for advancing cancer treatment methodologies.

Aquaporins (AQPs) allow the diffusion of hydrogen peroxide (H₂O₂) and act as ROS scavenging systems, which are important for controlling the redox state of cells. Recently, cerium oxide nanoparticles were found to increase the water and H₂O₂ permeability by modulating AQPs. To further analyze the action of nanoparticles (NPs) on AQP, we examined the effect of the NPs presenting different core compositions (CeO₂, Gd₂O₃, Fe₃O₄, and TiO₂), hydrodynamic sizes, and surface functionalization. The NPs produced an increase in H₂O and H₂O₂ permeability as a general trend. The hydrodynamic sizes of the NPs in the range of 22–100 nm did not produce any significant effect. The chemical nature of the NPs’ core did not modify the effect and its intensity. On the other hand, the NPs’ functionalized surface plays a major role in influencing both water and H₂O₂ permeability. The results suggest that NPs can play a significant role in controlling oxidative stress in cells and might represent an innovative approach in the treatment of a number of pathologies associated with an increased oxidative status.

Inorganic nanoparticles of boron-rich compounds represent an attractive alternative to boron-containing molecules, such as boronophenylalanine or boranes, for BNCT applications. This work describes the synthesis and biological activity of multifunctional boron carbide nanoparticles stabilized with polyacrylic acid (PAA) and a gadolinium (Gd)-rich solid phase. A fluorophore (DiI) was included in the PAA functionalization, allowing the confocal microscopy imaging of the nanoparticles. Analysis of the interaction and activity of these fluorescent Gd-containing B₄C nanoparticles (FGdBNPs) with cultured cells was appraised using an innovative correlative microscopy approach combining intracellular neutron autoradiography, confocal, and SEM imaging. This new approach allows visualizing the cells, the FGdBNP, and the events deriving from the nuclear process in the same image. Quantification of ¹⁰B by neutron autoradiography in cells treated with FGdBNPs confirmed a significant accumulation of NPs with low levels of cellular toxicity. These results suggest that these NPs might represent a valuable tool for achieving a high boron concentration in tumoral cells.

Some aquaporins (AQPs) allow the diffusion of hydrogen peroxide (H₂O₂), the most abundant ROS, through the cell membranes. Therefore, the possibility of regulating the AQP-mediated permeability to H₂O₂, and thus ROS scavenging, appears particularly important for controlling the redox state of cells in physiological and pathophysiological conditions. Several compounds have been screened and characterized for this purpose. This study aimed to analyze the effect of cerium oxide nanoparticles (CNPs) presenting antioxidant activity on AQP functioning. HeLa cells express AQP3, 6, 8, and 11, able to facilitate H₂O₂. AQP3, 6, and 8 are expressed in the plasma membrane and intracellularly, while AQP11 resides only in intracellular structures. CNPs but not cerium ions treatment significantly increased the water and H₂O₂ permeability by interacting with AQP3, 6, and especially with AQP8. CNPs increased considerably the AQP-mediated water diffusion in cells with oxidative stress. Functional experiments with silenced HeLa cells revealed that CNPs increased the H₂O₂ diffusion mainly by modulating the AQP8 permeability but also the AQP3 and AQP6, even if to a lesser extent. Current findings suggest that CNPs represent a promising pharmaceutical agent that might potentially be used in numerous pathologies involving oxidative stress as tumors and neurodegenerative diseases.