Redox Mechanisms Involved in the Selective Activation of Nrf2-mediated Resistance Versus p53-dependent Apoptosis in Adenocarcinoma Cells

Abstract

We have investigated the role of reactive oxygen species and thiol-oxidizing agents in the induction of cell death and have shown that adenocarcinoma gastric (AGS) cells respond differently to the oxidative challenge according to the signaling pathways activated. In particular, apoptosis in AGS cells is induced via the mitochondrial pathway upon treatment with thiol-oxidizing agents, such as diamide. Apoptosis is associated with persistent oxidative damage, as evidenced by the increase in carbonylated proteins and the expression/activation of DNA damage-sensitive proteins histone H2A.X and DNA-dependent protein kinase. Resistance to hydrogen peroxide is instead associated with Keap1 oxidation and rapid translocation of Nrf2 into the nucleus. Sensitivity to diamide and resistance to hydrogen peroxide are correlated with GSH redox changes, with diamide severely increasing GSSG, and hydrogen peroxide transiently inducing protein-GSH mixed disulfides. We show that p53 is activated in response to diamide treatment by the oxidative induction of the Trx1/p38 MAPK signaling pathway. Similar results were obtained with another carcinoma cell line, CaCo2, indicating that these findings are not limited to AGS cells. Our data suggest that thiol-oxidizing agents could be exploited as inducers of apoptosis in tumor histotypes resistant to ROS-producing chemotherapeutics.

Expression of UDP-glucuronosyltransferase 1A, nuclear factor erythroid-E2-related factor 2 and Kelch-like ECH-associated protein 1 in colonic mucosa, adenoma and adenocarcinoma tissue

“…In this case, the imbalance may be caused by the upregulated expression of proteins that compete for the binding sites of Nrf2/Keap1, including sequestosome-1 and prorhymosin-α (20)(21)(22), which results in the slower degradation of Keap1 and the overexpression of Nrf2. It has been suggested that HNE modifies Keap1, allowing Nrf2 to enter the nucleus to take effect (23,24). Future cellular studies are required to elucidate the effects of abnormal regulation and expression of the Nrf2/Keap1 pathway on the development of cancer.…”

p38MAPK and ERK1/2 dictate cell death/survival response to different pro-oxidant stimuli via p53 and Nrf2 in neuroblastoma cells SH-SY5Y

“…Trx1 redox state was analyzed as previously described [14]. Briefly, cells were treated with cold TCA at final concentration of 10% for 30 min at 4 8C.…”

“…In this context, we have previously demonstrated that oxidative stress of different nature (ROS versus disulfide stress) can evocate opposite responses (cell death or survival), in the gastric adenocarcinoma cell line AGS, by means of the redox activation of specific signaling pathways [14]. In particular, we identified in the redox-dependent dissociation of Keap1/Nrf2 complex the event responsible for the resistance to ROS-mediated insults, and in the redox-activation of trx1/p38 MAPK /p53 signaling axis the pathway governing the induction of the apoptosis upon treatment with disulfide stressors (e.g., diamide).…”

“…In this scenario, the modulation of glutathione (GSH), which represents one of the major indicators of the intracellular redox environment, as well as the control on transcriptional activity of redox sensitive factors is emerging as possible strategies [12]. Among the transcription factors able to sense oxidative stress, the nuclear erythroid factor 2 (NE-F2)-related factor 2 (Nrf2) and p53 are well-characterized examples [14]. Besides the canonical Redox changes are often reported as causative of neoplastic transformation and chemoresistance, but are also exploited as clinical tools to selectively kill tumor cells.…”

Mechanisms of cellular adaptation to quantum dots – the role of glutathione and transcription factor EB

“…Nrf2 activation may occur via direct or indirect phosphorylation of Nrf2 itself or regulator proteins by MAPKs (Li and Kong 2009). Activation of MAPKs cascades in response to oxidative stress is well documented; however, the specific molecular mechanisms of Nrf2 activation remain unclear (Piccirillo et al 2009). One potential mechanism is the phosphorylation of Cul3, a Nrf2 binding protein by MAPKs (Rachakonda et al 2008).…”