Calcium overload induces C6 rat glioma cell apoptosis in sonodynamic therapy

Abstract

Purpose: Our aim was to study calcium overload-induced apoptosis and its relation to reactive oxygen species (ROS) in rat C6 glioma cells after sonodynamic treatment (SDT).

Materials and methods: Hematoporphyrin monomethyl ether (HMME) was used as the sonosensitizer. The concentration of intracellular Ca²⁺ ([Ca²⁺]_i) was measured by fluorometry. Apoptosis and necrosis rates were evaluated by a flow cytometry. Moreover, sarcoplasmic reticulum Ca²⁺ -ATPase (SERCA₂), cytochrome c (cyto-c) and cleaved caspase-3 were investigated by immunoblotting.

Results: Our study indicated that [Ca^{2 +}]_i and ROS increased in cells of SDT group, the apoptosis rate, quantity of cyto-c and cleaved caspase-3 markedly increased after SDT. Furthermore, N-Acetyl-L-cysteine (NAC) or 1,2-bisethane-N,N,N′,N′-tetraacetic acid tetrakis ester (BAPTA-AM) could decrease the apoptosis rate, the release of cyto-c and cleaved caspase-3 in SDT group, SERCA₂ degradation was found in SDT group and could also be prevented by the addition of NAC.

Conclusions: Our results show that HMME-SDT can induce C6 cell death through both necrosis and apoptosis. ROS in C6 cells play a decisive role in HMME-SDT-induced cell death. The endoplasmic reticulum (ER) may be a major target of HMME-SDT, ROS can induce SERCA₂ degradation, causing the elevation of [Ca²⁺]_i.

Keywords::

• Sonodynamic treatment (SDT)
• hematoporphyrin monomethyl ether (HMME)
• intracellular Ca²⁺
• C6 glioma cells
• reactive oxygen species (ROS)

Acknowledgements

This work was supported by National Nature Science Fund (81072079), Technological Key Research Projects of Heilongjiang province (GC10C304-1) and the bureau of Education of Heilongjiang province fund (11551212).

Declaration of interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.