Effects of Different Doses of Curcumin on Apoptosis, Mitochondrial Oxidative Stress and Calcium Ion Influx in DBRG Glioblastoma Cells

Abstract

Transient Receptor Potential (TRP) channels superfamily has mostly calcium ion (Ca2+) permeable non-selective cation channels. Transient receptor potential melastatin subfamily 2 (TRPM2) is widely expressed in central nervous system. Intracellular Ca2+ concentration ([Ca2+]i) may change depend on TRPM2 and TRPM8 activations from extracellular liquid to cytosol. Curcumin as natural antioxidant shows phenolic structure, synthesized by Curcuma longa L. (Indian saffron, turmeric), has powerful non-enzymatically antioxidant effects. Low dose curcumin treatment can decrease calcium signaling via TRPM2 channel inhibition and prevent elevation of [Ca2+]i levels. Hence, we investigated effects of four different concentrations (5, 10, 25 and 50 µM) of curcumin on apoptosis and cell viability (MTT), reactive oxygen species (ROS) production, mitochondrial membrane potential levels, caspase 3 and caspase 9 values in DBRG glioblastoma cells. We found that curcumin reduces cell viability by concentration dependent manner. It was also observed that curcumin induces apoptosis via caspase 3 and 9 related pathways. However, it was not found any direct relationship between the effect of increased concentrations of curcumin and inhibition or activation of TRPM2 mediated Ca2+ signaling in the DBTRG cells. The [Ca2+]i concentration was lower in 5 µM group as compare to control group. Curcumin acted important role on decrease of mitochondrial membrane potential and intracellular ROS production in the cells. Moreover, curcumin treatment markedly supported GSH concentration levels in the cells. In conclusion, it was firstly assessed the effects of different doses of curcumin on TRPM2 mediated calcium signaling and interaction with various apoptosis parameters in DBTRG glioblastoma cells.