Prolonged copper depletion induces expression of antioxidants and triggers apoptosis in SH-SY5Y neuroblastoma cells

Abstract

SH-SY5Y neuroblastoma cells were cultured for up to three serial passages in the presence of the copper chelator triethylene tetramine (Trien). The copper-depleted neuroblastoma cell line obtained showed decreased activities of the copper enzymes Cu, Zn super-oxide dismutase and cytochrome c oxidase with concomitant increases in reactive oxygen species. Mitochondrial antioxidants (Mn superoxide dismutase and Bcl-2)were up-regulated. Overexpression and activation of p53 were early responses, leading to an increase in p21. Eventually, copper-depleted cells detached from the monolayer and underwent apoptosis. Activation of upstream caspase-9, but not caspase-8, suggested that apoptosis proceeds via a mitochondrial pathway, followed by caspase-3 activation. The addition of copper sulfate to the copper-depleted cells restored copper enzymes, normalized antioxidant levels and improved cell viability. We conclude that prolonged copper starvation in these replicating cells leads to mitochondrial damage and oxidative stress and ultimately, apoptosis.

Combined Effects of Treatment with Trientine, a Copper-Chelating Agent, and X-Irradiation on Tumor Growth in Transplantation Model of a Murine Fibrosarcoma

“…These results showed that trientine and X-irradiation interacted additively in inhibition of tumor growth under the conditions used in the present study. It has been shown that copper deficiency induces apoptosis in a variety of cells in vitro and in vivo [1,17,21,25,48]. We have shown that treatment with trientine induced apoptosis in tumor cells at an early stage of tumor development [15].…”

Triethylenetetramine Pharmacology and Its Clinical Applications

“…One recent report suggested that TETA could induce apoptosis in murine fibrosarcoma cells via the activation of the p38 MAPK pathway (13). Another report suggested that prolonged copper depletion via TETA chelation might induce expression of antioxidants and trigger apoptosis in neuroblastoma cells (81).…”

Trientine, a Copper-Chelating Agent, Induced Apoptosis in Murine Fibrosarcoma Cells by Activation of the p38 MAPK Pathway

“…Induction of apoptosis by trientine may reduce the radiation dose required to suppress tumor growth in radiation therapy, resulting in a decrease in occurrence of deleterious side effects of radiation, and provide clinical benefits for tumor treatments. Although it has been shown that Cu deficiency induces apoptosis in a variety of cells in vitro and in vivo [20,21,28,29], the pathway that induces apoptosis by Cu deficiency remains to be elucidated. In the course of our study on the mechanisms of induction of apoptosis by Cu deficiency, we found that p38 mitogen-activated protein kinase (MAPK) plays a role in the induction of apoptosis in murine fibrosarcoma.…”

“…Activation of p38 MAPK in response to several anticancer agents is necessary and, in some cases, sufficient, to induce apoptosis in a variety of cancer cell lines [8][9][10]25]. This is the first report of trientine inducing apoptosis by activation of p38 MAPK, although it has been shown that Cu deficiency induces apoptosis in a variety of cells in vitro and in vivo [20,21,28,29]. Furthermore, p38 MAPK has been reported to positively regulate several tumor suppressor pathways, such as replicative senescence and contact inhibition [12,14,19].…”