Curcumin inhibits oxidative stress-induced TRPM2 channel activation, calcium ion entry and apoptosis values in SH-SY5Y neuroblastoma cells: Involvement of transfection procedure.

Transient Receptor Potential (TRP) channels are mostly Ca²⁺ permeable cation channels. Transient Receptor Potential Melastatin-like 2 (TRPM2) is expressed in neurological tissues such as brain, dorsal root ganglia (DRG) neurons, hippocampus and also liver, heart and kidney. The SH-SY5Y cells are mostly used as a cellular model of neurodegenerative diseases, Alzheimer's and Parkinson's diseases. Curcumin, shows phenolic structure, synthesized by Curcuma longa L. (turmeric), has powerful non-enzymatically antioxidant effects compared with Vitamin E. Hence, we aimed to investigate that effects of curcumin on TRPM2 cation channel currents using the whole-cell Patch-Clamp method, Ca²⁺ signaling, apoptosis and cell viability (MTT) assays, reactive oxygen species (ROS) production, mitochondrial membrane potential levels, caspase 3 and caspase 9 activities in TRPM2 transfected SH-SY5Y neuroblastoma cells. For this aim, we designed four experimental groups named; control, curcumin, transfected and transfected + curcumin groups. Cytosolic free calcium concentrations were higher in transfected group compared with curcumin and transfected + curcumin group. Moreover, these data examined with whole-cell Patch-Clamp recordings of single cells in all groups. ROS levels were significantly higher in transfected group than in transfected + curcumin group. Apoptosis levels in transfected + curcumin group were lower than in transfected group. Procaspase 9 and procaspase 3 levels measured by western blotting and caspase 3 and caspase 9 levels by spectrophotometric methods show that TRPM2 transfected cells are more tended to apoptosis. In conclusion, curcumin strongly induces modulator effects on TRPM2-mediated Ca²⁺ influx caused by ROS and caspase 3 and 9 processes in SH-SY5Y neuroblastoma cells.