The cell death response to the ROS inducer, cobalt chloride, in neuroblastoma cell lines according to p53 status

Abstract

Abstract. Cobalt chloride (CoCl 2 ), a hypoxia-mimetic agent, induces reactive oxygen species (ROS) generation, leading to cell death. Divergent data have been reported concerning p53 implication in this apoptotic mechanism. In this study, we studied cobalt-induced cell death in neuroblastoma cell lines carrying wild-type (WT) p53 ( SHSY5Y) and a mutated DNA-binding domain p53 [SKNBE(2c)]. CoCl 2 induced an upregulation of p53, p21 and PUMA expression in WT cells but not in SKNBE(2c). In SHSY5Y cells, p53 serine-15 phosphorylation appeared early (6 h) in the mitochondria, and also in the nucleus after 12 h. In contrast, in SKNBE(2c) cells, the slight nuclear signal disappeared with CoCl 2 treatment. In SHSY5Y cells, a mitochondrial pathway dependent on caspases [collapse of mitochondrial transmembrane potential (∆Ψ mt ), caspase 3 and 9 activation], was activated in a time-dependent manner. SKNBE(2c) cells exhibited a delay in the cell death executive phase linked to a caspase-independent pathway, involving apoptosis inducing factor nuclear translocation, but also an autophagic process attested by LC3-II expression and cathepsin-B activation. The downregulation of p53 in SHSY5Y cells by siRNA induced a cell death pathway related to the one observed in SKNBE(2c) cells. Finally, CoCl 2 induced time-dependent canonical p53 mitochondrial apoptosis in the WT p53 cell line, and caspase-independent cell death in cells with a mutated or KO p53.

Kv3.4 is modulated by HIF-1α to protect SH-SY5Y cells against oxidative stress-induced neural cell death

“…Therefore we believed down-regulated Kv3.4 is involved in the cytoprotection induced by a low CoCl 2 concentration. On the other hand, a high CoCl 2 concentration (500 μM) prompts cell death in the SH-SY5Y cells 43 , and in our scheme, it is because ROS generated by a high concentration of CoCl 2 may overcome the cytoprotective effect of downregulated Kv3.4. According to our hypothesis, inhibiting Kv3.4 would alter the response of SH-SY5Y cells to MPP + treatment.…”

Orexins Protect Neuronal Cell Cultures Against Hypoxic Stress: an Involvement of Akt Signaling

“…Mitochondria act as O 2 sensors by increasing the generation of ROS during hypoxia, and cobalt chloride mimics this response by inducing ROS generation (Chandel et al 1998; Stenger et al 2011). To confirm that orexins protect cortical neurons from the cobalt chloride toxicity, we measured oxidative stress level in rat cortical neurons using CM-H 2 TMRos, a ROS-sensitive probe, in the presence or absence of cobalt chloride (100 μM), treated with orexins at concentrations at which we observed the highest peptides responses, i.e., 0.1 μM for orexin A and 0.01 μM for orexin B.…”

Oxygen regulates molecular mechanisms of cancer progression and metastasis

“…A critical role of p53 in apoptosis upon oxidative stress is implied by the functional redundancy of p53; certain mutations in p53 are tolerated due to activation of alternate mechanisms. Functional p53 induces a caspase-dependent apoptotic response while mutantp53 induces caspase-independent, AIF-dependent response in neuroblastoma cells under hypoxia-mimetic agent CoCl 2 [191]. Functional p53 is also reported to induce AIF through caspase 2 [192].…”