Upregulation of Fas and FasL in Taiwan cobra phospholipase A₂‐treated human neuroblastoma SK‐N‐SH cells through ROS‐ and Ca²⁺‐mediated p38 MAPK activation

Abstract

The aim of the present study is to elucidate the signaling pathway involved in death of human neuroblastoma SK-N-SH cells induced by Naja naja atra phospholipase A(2) (PLA(2)). Upon exposure to PLA(2), p38 MAPK activation, ERK inactivation, ROS generation, increase in intracellular Ca(2+) concentration, and upregulation of Fas and FasL were found in SK-N-SH cells. SB202190 (p38MAPK inhibitor) suppressed upregulation of Fas and FasL. N-Acetylcysteine (ROS scavenger) and BAPTA-AM (Ca(2+) chelator) abrogated p38 MAPK activation and upregulation of Fas and FasL expression, but restored phosphorylation of ERK. Activated ERK was found to attenuate p38 MAPK-mediated upregulation of Fas and FasL. Deprivation of catalytic activity could not diminish PLA(2)-induced cell death and Fas/FasL upregulation. Moreover, the cytotoxicity of arachidonic acid and lysophosphatidylcholine was not related to the expression of Fas and FasL. Taken together, our results indicate that PLA(2)-induced cell death is, in part, elicited by upregulation of Fas and FasL, which is regulated by Ca(2+)- and ROS-evoked p38 MAPK activation, and suggest that non-catalytic PLA(2) plays a role for the signaling pathway.

Ouabain‐induced changes in MAP kinase phosphorylation in primary culture of rat cerebellar cells

“…At the same time, a decrease in intracellular calcium cancelled ouabain's effects on p38 and JNK phosphorylation, allowing us to assume these processes to be calcium dependent. This corresponds to previously reported data …”

“…To determine the role of calcium we used Ca 2+ chelator BAPTA‐AM at a concentration of 10 μM which had been previously used in neurons . We showed that BAPTA‐AM did not cancel ouabain‐induced ERK1/2 phosphorylation increase, but instead caused an additional activating effect on ERK1/2 which corresponded well to earlier published data . This allows us to conclude that ouabain‐induced ERK1/2 phosphorylation is not calcium dependent.…”

“…45 We showed that BAPTA-AM did not cancel ouabain-induced ERK1/2 phosphorylation increase, but instead caused an additional activating effect on ERK1/2 which corresponded well to earlier published data. 58,59 This allows us to conclude that ouabain-induced ERK1/2 phosphorylation is not calcium dependent. At the same time, a decrease in intracellular calcium cancelled ouabain's effects on p38 and JNK phosphorylation, allowing us to assume these processes to be calcium dependent.…”

Antiproliferative and Apoptotic Effects ofSesbania grandifloraLeaves in Human Cancer Cells

“…It was reported that ROS could play a role in downregulating Bcl-2 [32] as well as in triggering the release of cytochrome C from the mitochondria into the cytoplasm along with Fas associated proteins recruitment and finally leading to the activation of caspase 3 and apoptosis [33–35]. In our present study, increased levels of ROS in the treatment group indicated that the apoptotic mode of cell death induced by the methanolic fraction of S. grandiflora is through the generation of ROS.…”

Role of reactive oxygen species in brucein D-mediated p38-mitogen-activated protein kinase and nuclear factor-κB signalling pathways in human pancreatic adenocarcinoma cells

“…Moreover, we have recently reported that BD induces apoptosis in pancreatic cancer cells by activating the phosphorylation of p38-mitogenactivated protein kinase (MAPK) (Lau et al, 2009). Although the function of ROS in the activation of p38-MAPK (Yi et al, 2004;Lee et al, 2008;Chen et al, 2009), and the regulation of NF-kB activity (Hayakawa et al, 2003;Fujioka et al, 2004), has been characterised in substances-induced apoptosis in various cancer cells, the involvement of ROS in BD-induced pancreatic cancer cell apoptosis is yet to be elucidated. Given that ROS have an important function in an array of biological responses and diverse signalling pathways, we hypothesised that BD activates pro-apoptotic pathways through the enhancement of ROS production and the inhibition of NF-kB activity in pancreatic cancer cells.…”