p53 regulates ceramide formation by neutral sphingomyelinase through reactive oxygen species in human glioma cells

Neutral Sphingomyelinase-3 Is a DNA Damage and Nongenotoxic Stress-Regulated Gene That Is Deregulated in Human Malignancies

“…A large body of evidence has implicated nSMases and nSMase-derived ceramide as important modulators of the cellular response not only to TNF-a but also to genotoxic agents such as g-radiation and Adriamycin (12,(31)(32)(33). nSMase3 is a new member of the neutral sphingomyelinase family, and before this report, its role in cell growth modulation and apoptosis was not known.…”

“…In addition to TNF-a, nSMase2 is also activated by oxidative stress (29) and seems to be involved in inducing growth arrest in MCF-7 human breast cancer cells (30). Furthermore, nSMase activity is enhanced by ionizing radiation (15,31), the DNAdamaging agents Adriamycin, daunorubicin, and etoposide (12,32,33), hypoxia (34), and UV radiation (35), although the relative contribution of specific nSMase enzymes in mediating the response to these stressors remains unclear. The creation of nSMase1 À/À and nSMase2 À/À mice has provided some insights into the functions of these enzymes (36,37); however, more studies are needed to fully examine the independent effects of each in cellular stress-induced ceramide generation and their role in tumorigenesis.…”

2-Methoxyestradiol-induced apoptosis in human leukemia cells proceeds through a reactive oxygen species and Akt-dependent process

“…It has recently been reported that ROS formation is intimately involved in 2ME apoptosis in certain human leukemia cells through an SOD-related process (Huang et al, 2000). In this study, we employed three antioxidants, for example, TBAP, a cell permeable SOD mimetic, catalase, and sodium formate, which primarily act on O 2 À , H 2 O 2 , and OH Á , respectively, to investigate the involvement of individual ROS species in 2-ME-mediated apoptosis as well as (Huang et al, 2000;Sawada et al, 2001), but also various perturbations in survival signaling pathways. They also indicate that Akt downregulation represents a critical signaling event that operates downstream of 2-ME-mediated oxidative injury to trigger mitochondrial injury, alterations in other signaling and survival proteins, and engagement of the apoptotic caspase cascade.…”

“…HE and DCFH-DA have been shown to be 2ME-induced apoptosis in human leukemia cells N Gao et al relatively specific for O 2 À and H 2 O 2 , respectively (Sawada et al, 2001). O 2 À is able to oxidize HE to yield ethidium, and H 2 O 2 is able to oxidize DCFH to the fluorescent DCF.…”

DNA damage-inducing agents elicit γ-secretase activation mediated by oxidative stress

“…Intracellular ROS level was measured using carboxy-H 2 DCFDA (DCFDA) fluorescence according to the previous report. 38 Briefly, cells grown in 12-well plates were treated with DDIA, and cells were then incubated for 15 min with the ROS/RNS-sensitive fluorophore DCFDA (5 mg/ml). The cells were then immediately washed with PBS, detached, and counted.…”