Treatment of Glioblastoma tumors using photoactivated chemotherapy

Glioblastoma multiforme (GBM) is highly aggressive and difficult to treat, necessitating the development of new therapies. Photoactivated chemotherapy (PACT) has emerged as a promising method, where biologically active compounds are “caged” into inactive prodrugs, and re-activated by visible light irradiation at the tumor site, potentially offering more patient-friendly treatments without compromising antitumor efficacy. In this study, we investigated the activity of a series of ruthenium-based PACT compounds [1](PF6)2-[3](PF6)2 in U-87MG glioblastoma cells, a common in vitro model for glioblastoma, and the safety of these compounds in SH-SY5Y cells, which is a recognized model for healthy neurons. The action of these compounds was compared to that of Donepezil, a known acetylcholinesterase inhibitor used in the treatment of brain disorders. Promising light-activated anticancer activity was observed in U-87MG cells for [3](PF6)2 while the two other compounds were inactive([1](PF6)2) or non-activated ([2](PF6)2). In non-cancerous SH-SY5Y cells the light-activated complexes surprisingly enhanced cell proliferation in a manner similar to Donepezil. While significantly higher amounts of Ru were found in SH-SY5Y cells upon green light irradiation, in particular for [3](PF6)2, this cell proliferation effect was independent from ruthenium cellular uptake. Given the importance of Ca2+ levels for the normal function of neurons, we also examined Ca2+ accumulation upon treatment with ruthenium and light. Increased Ca2+ uptake was found in cells treated with inactivated [1](PF6)2 , [2](PF6)2 , or with green light only. Upon treatment with [3](PF6)2 intracellular Ca2+ content was not changed in the dark but it significantly increased upon light activation, without observable sign of cell death. The structure-dependent action of the ruthenium compounds on Ca2+ homeostasis suggested a docking studies with the NMDA, serotonin, and AMPA receptors, which all act on calcium levels. Docking revealed that [3](PF6)2 interacts with the NMDA receptor, which might be responsible for the enhanced Ca2+ uptake upon light activation in SH-SY5Y cells. Overall, although [3](PF6)2 was phototoxic to U-87MG cells, the combination of this prodrug and green light irradiation enhanced the survival of neuronal-like cells and increased intracellular Ca2+ levels, probably via interaction with the NMDA receptor. These findings highlight the potential of ruthenium-based PACT prodrugs in treating glioblastoma cells while maintaining the viability of nearby, healthy neuronal cells