In vitro stimulation of calcium overload and apoptosis by sonodynamic therapy combined with hematoporphyrin monomethyl ether in C6 glioma cells

Abstract

The present study investigated enhancement of apoptosis induction and the mechanisms underlying calcium overload on C6 glioma cells in vitro, stimulated by low-level ultrasound in combination with hematoporphyrin monomethyl ether (HMME). The optimum frequency of ultrasound was determined by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The apoptotic rate, reactive oxygen species concentration and decreased mitochondrial membrane potential (MMP) were analyzed by flow cytometry. Morphological changes were detected by a transmission electron microscope, and the concentration of intracellular Ca2+, [Ca2+]i, was detected by a confocal laser scanning microscope. In addition, the release of cytochrome c (cyt-c) was measured by western blot analysis. The results revealed that an increased apoptotic effect was induced by sonodynamic therapy (SDT), and this was found to correlate with the overloaded [Ca2+]i, derived from the intra- and extracellular sources in the early apoptotic process. The results also revealed an increased level of ROS production, a decreased MMP and an increased release of cyt-c. The present study indicated that low-level ultrasound in combination with HMME improved the apoptotic effect in C6 glioma cells. The overloaded [Ca2+]i was involved in the mechanism by which apoptosis was stimulated and enhanced by SDT.

Sonodynamic Therapy for the Treatment of Intracranial Gliomas

“…Moreover, the addition of calcium chelators tempered all the results, strengthening the idea that calcium increase is a key element in the induction of SDT-mediated apoptosis [ 69 ]. These findings were confirmed by later studies that contributed to strengthen the correlation between calcium surge and apoptosis in C6 glioma cell lines [ 40 , 41 ] treated with HMME-SDT.…”

“…Furthermore, SDT could promote calcium ion overload on the mitochondrial membrane and induce apoptosis of target cells by promoting cytochrome-c release and reducing the electric potential of the membrane itself [ 40 , 41 ].…”

“…Hematoporphyrin monomethyl ether (HMME) is a porphyrin-based compound, originally employed as photosensitizer; its high selectivity for tumor cells, among which gliomas, rapid removal and low toxicity make it suitable for SDT [ 41 , 70 , 86 , 87 ].…”

Manipulation of Mitophagy by “All-in-One” nanosensitizer augments sonodynamic glioma therapy

“…Our previous works on SDT have shown its anti-neoplastic effects on various cancers with great potential [13,14]. Studies also demonstrate significant therapeutic effects of SDT on glioma cells in vitro [15,16], while rarely focus on orthotopic gliomas.…”

Zinc Oxide Nanocrystals and High-Energy Shock Waves: A New Synergy for the Treatment of Cancer Cells

“…Further investigations about the mechanism of the observed synergy and cell death are required. In particular, dedicated quantitative and qualitative analysis could be performed to explain the synergy, such as gene expression to better understand the molecular mechanism (Foglietta et al, 2015), the evaluation of morphological modifications with a direct observation through fluorescence microscopy and transmission electron microscopy (Dai et al, 2014;Defour et al, 2014) and several other tests to observe typical SW and ZnO nanoparticles related damages (Izadifar et al, 2017;Garino et al, 2019b). Moreover, the electric stimulation consequences could be measured, as suggested by other authors (Marino et al, 2018(Marino et al, , 2019.…”