Biochemical and Biophysical Research Communications
Phenethyl isothiocyanate sensitizes glioma cells to TRAIL-induced apoptosis
Introduction
Glioblastoma multiforme (GBM; WHO grade IV) is the most common and most aggressive type of primary brain tumor with a high mortality rate. The median survival time of patients with GBM is less than 1 year even with multimodality therapy consisting of a combination of surgery, radiation and chemotherapy [1]. Therefore, finding new strategies to limit brain tumor has been the goal widespread research.
Many studies have founded that potential chemotherapeutic agent’s increase TRAIL death receptor expression, increasing cytotoxicity they have founded that in different types of cancer cells [2], [3]. In addition, cell death increase is caused by a synergistic apoptotic response from combination with TRAIL [3], [4], [5]. TRAIL binds to death receptors-4 and -5 (DR-4 and DR-5). This leads to the activation of caspase 8 and subsequent cleavage of BID, a BH3-only family member, causing mitochondrial dysfunction and apoptosis, the process of programmed cell death (PCD) [6]. TRAIL induces apoptosis in cancer cells without inducing apoptosis in normal cells. This indicates the potential for TRAIL to become a therapeutic agent in the treatment of cancer. Unfortunately, many cancer cells have resistance to TRAIL [7], [8] and novel agents are needed to overcome this resistance to improve TRAIL efficacy. Hence, understanding the regulation of TRAIL receptor activation could provide insight into increasing TRAIL-induced apoptosis in these TRAIL-resistant cells. Thus, we and others are currently seeking to identify TRAIL sensitizers capable of overcoming TRAIL resistance in cancer cells [9], [10].
Phenethyl isothiocyanate (PEITC) is one of the best studied members of isothiocyanates (ITC), a variety of edible cruciferous vegetables including broccoli, watercress, and cabbage, and have generated particular interest because of its remarkable chemopreventive activity.
In this study, we show that combined treatment with subtoxic doses of PEITC and TRAIL dramatically induces apoptosis in TRAIL-resistant glioma cells. The sensitizing effect of PEITC on TRAIL is associated with ROS generation and up-regulation of p53 protein levels. Our data suggests that both extrinsic and intrinsic pathways are involved in apoptosis induced by combined treatment with PEITC and TRAIL.
Section snippets
Reagents and antibodies
PEITC was purchased from LKT Laboratories (St. Paul, MN, USA). Soluble recombinant TRAIL was purchased from R&D Systems (Plymouth Meeting, PA, USA). The caspase inhibitors zDEVD-fmk (caspase-3 inhibitor), zLEHD-fmk (caspase-9 inhibitor) and zIETD-fmk (caspase-8 inhibitor) were purchased from Sigma–Aldrich (St. Louis, MO, USA). These caspase inhibitors were prepared and dissolved in dimethylsulfoxide (DMSO) and applied to the cells at 25 μM. 6-carboxy-2′,7′-dichlorofluorescein diacetate
Subtoxic doses of PEITC effectively sensitize human glioma cells to TRAIL-induced apoptosis
To assess the ability of PEITC to act as a sensitizer of malignant glioma cells to the apoptotic effects of TRAIL, we first examined the effect of TRAIL with and without PEITC on the viability of a number of different glioma cell lines. We found that U87MG, A172, and T98G cells were relatively resistant to TRAIL over a range of doses, whereas U343 cells were somewhat sensitive to TRAIL. PEITC alone induced a modest level of glioma cell death (<20%) at concentrations up to 5 μM. In contrast, the
Discussion
In the present study, we show for the first time that subtoxic doses of PEITC effectively sensitize different glioma cell lines to TRAIL-induced apoptosis. Accumulation of intercellular ROS leads to disruption of mitochondrial membrane potential, release of cytochrome c into the cytosol with subsequent activation of the caspase cascade, and finally to programmed cell death through apoptosis. Recently it has been suggested that oxidative stress has a pivotal role as a common mediator of
Conflict of interest
The authors state no conflict of interest.
Acknowledgments
We gratefully acknowledge Dr. Yong J. Lee, Department of Surgery, University of Pittsburgh, for critically reading the manuscript before submission. This study was supported by the Kosin University Research Fund in 2012 and Hanmi Pharm. Co., Ltd.
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2017, International Journal of Biochemistry and Cell BiologyCitation Excerpt :Given that TRAIL is known to trigger apoptosis through binding to its cell surface death receptors, DR4 and DR5, their expression levels may be critical in determining the intensity and/or duration of TRAIL-induced apoptotic signaling. Previously, we reported that the DR5-upregulating agents, gingerol (Lee et al., 2014a), shogaol (Hwang et al., 2015), digitoxin (Lee et al., 2014c), metformin (Park et al., 2016), and PEITC (Lee et al., 2014b), effectively stimulate TRAIL-mediated apoptosis in glioma cells and colorectal cancer cells. Consistent with these reports, we found that cyclopamine dramatically induces DR5, but not DR4, leading to sensitization to TRAIL-induced apoptosis in various gastric cancer cell lines.
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2015, Chinese Journal of Natural MedicinesHSP90 inhibitor NVP-AUY922 enhances TRAIL-induced apoptosis by suppressing the JAK2-STAT3-Mcl-1 signal transduction pathway in colorectal cancer cells
2015, Cellular SignallingCitation Excerpt :A relatively high proportion of tumor cell lines tested to date have been found to be sensitive to the cytotoxic effects of TRAIL, and there is evidence for the safety and potential efficacy of TRAIL therapy [4,7]. Recently, some groups have reported that combinations of TRAIL and potential chemotherapeutic agents can increase TRAIL-induced apoptosis in several types of solid tumor cells [8–12]. Heat shock protein (HSP90) functions as a molecular chaperone of oncoproteins, by which it regulates cellular homeostasis, cell survival, and transcriptional regulation [13,14].
PEITC induces apoptosis of Human Brain Glioblastoma GBM8401 Cells through the extrinsic- and intrinsic -signaling pathways
2015, Neurochemistry InternationalCitation Excerpt :Studies have disclosed the cell growth inhibitory effects of PEITC in human leukemia (Xu and Thornalley, 2000), lung cancer (von Weymarn et al., 2006), HeLa cervical cancer (Yu et al., 1998), HT-29 colon adenocarcinoma (Hu et al., 2003), pancreatic cancer (Nishikawa et al., 2004), and human prostate cancer PC-3 cells (Xu et al., 2005). In human glioma cells, PEITC inhibits the HIF-1α expression through inhibiting the Phosphoinositide 3-kinase (PI3K) and mitogen activated protein kinase (MAPK) signaling pathway, and reduces the hypoxia-induced secretion of vascular endothelial growth factor (VEGF) (Gupta et al., 2013); PEITC also promoted the actions of tumor necrosis factor-related apoptosis-induced ligand (TRAIL) through the upregulation of death receptor-5 (DR5) with ROS-induced-p53 and the downregulation of cell survival proteins (Lee et al., 2014). But the overview of mechanisms of PEITC-induced apoptosis of human brain glioblastoma cells has not been understood well.
Phenethyl isothiocyanate: A comprehensive review of anti-cancer mechanisms
2014, Biochimica et Biophysica Acta - Reviews on CancerCitation Excerpt :Using pre-clinical studies, improved outcomes were observed when the conventional agents, such as docetaxel, metformin, vinblastine, doxorubicin and HDAC inhibitors were combined with PEITC [102,165,197,198] (Table 4). PEITC treatment sensitized glioma cells to TRAIL via ROS generation [199]. Interestingly, cisplatin also showed synergism with PEITC in cervical and breast cancer cells, which was mediated by modulation of MAPkinases, NFkB and death receptors [200].