IMMUNEPOTENT CRP increases intracellular calcium through ER-calcium channels, leading to ROS production and cell death in breast cancer and leukemic cell lines

IMMUNEPOTENT CRP (ICRP) is an immunotherapy that induces cell death in cancer cell lines. However, the molecular mechanisms of death are not completely elucidated. Here, we evaluated the implication of intracellular Ca(2+) augmentation in the cell death induced by ICRP on T-ALL and breast cancer cell lines. Cell death induction and the molecular characteristics of cell death were evaluated in T-ALL and breast cancer cell lines by assessing autophagosome formation, ROS production, loss of mitochondrial membrane potential, ER stress and intracellular Ca(2+ )levels. We assessed the involvement of extracellular Ca(2+), and the implication of the ER-receptors, IP(3)R and RyR, in the cell death induced by ICRP, by using an extracellular calcium chelator and pharmacological inhibitors. Our results show that ICRP increases intracellular Ca(2+) levels as the first step of the cell death mechanism that provokes ROS production and loss of mitochondrial membrane potential. In addition, blocking the IP(3) and ryanodine receptors inhibited ER-Ca(2+ )release, ROS production and ICRP-induced cell death. Taken together our results demonstrate that ICRP triggers intracellular Ca(2+)-increase leading to different regulated cell death modalities in T-ALL and breast cancer cell lines. See also Figure 1(Fig. 1).