Diallyl trisulfide-induced prostate cancer cell death is associated with Akt/PKB dephosphorylation mediated by P-p66shc

Abstract

PurposeP66Shc, an isoform of adaptor proteins, is known to mediate various signals including those leading to apoptosis or cell proliferation. Previously, we have shown that diallyl trisulfide (DATS)-induced prostate cancer cell death was mediated by increased ROS formation. In this study, we investigated the role of p66Shc protein and its serine 36 phosphorylation in DATS induced decrease in prostate cancer cell viability (PC-3).MethodsPC-3 prostate cancer cells were used in this study. Stable cell lines expressing p66ShcS36A or an empty vector have been obtained. Cell viability, concentration of ROS, changes in P-p66Shc and P-Akt and DNA damage were determined.ResultsWe observed that DATS treatment increased p66Shc phosphorylation at serine 36. Importantly, the phosphorylation was abolished by JNK inhibitor SP600125. Cells expressing plasmid-encoded variant of p66ShcS36A showed much higher resistance to DATS-induced cells death. In addition to that, we observed that DATS-induced ROS formation was completely abolished in cells expressing the p66ShcS36A variant. Interestingly, SP600125 proved to prevent DATS-induced Akt inactivation. In order to confirm that the observed effect is related to phosphorylation of p66Shc, we performed experiments on a stable cell line expressing p66ShcS36A. In such cells, DATS-induced Akt dephosphorylation was significantly reduced. On the other hand, hydrogen peroxide induced Akt activation in PC-3 cells, which was abrogated in cells expressing p66ShcS36A.ConclusionsOur results uncover a novel signaling pathway with p66Shc being indispensable for DATS-induced inactivation of Akt due to hypophosphorylation.

The Adaptor Proteins p66Shc and Grb2 Regulate the Activation of the GTPases ARF1 and ARF6 in Invasive Breast Cancer Cells

“…Interestingly, overexpression of p66Shc was shown to block the activation of both Ras and ERK1/2 following prolonged stimulation with EGF (15-60 min). Our findings also show that p66Shc can negatively regulate AKT phosphorylation, an effect previously described in a variety of cell types (55,56). This attenuation of AKT phosphorylation has been associated with the apoptotic properties of p66Shc (56), thus suggesting a possible role for p66Shc in mediating MDA-MB-231 cell survival.…”

A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

“…In contrast, a beneficial role played by H 2 S is its ability to combat oxidative stress. However, there are reports that, in some organisms, H 2 S stimulates rather than inhibits ROS production (4,5,43). The basis of these differences has not been resolved.…”

Diallyl trisulfide induces apoptosis in Jurkat cells by the modification of cysteine residues in thioredoxin

“…[2][3][4] We also reported that DATS induces apoptosis in human colon cell lines by oxidative modification of cysteine residues in β-tubulin into S-allyl cysteine residues; this modification causes cell cycle arrest at M-phase followed by apoptosis. 5,6) On the other hand, we also found that DATS induces apoptosis in human leukemic cells in a cell cycle independent manner; however, the molecular target(s) of DATS remains to be clarified.…”