P-021 - Cordycepin sensitizes TRAIL-mediated apoptosis through p38 MAPK-dependent and AMPK-independent signaling pathways in human gastric carcinoma AGS cells

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Basic Science
Gastric Cancer
Presenter C. Park
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors C. Park1, Y.H. Yoo2, M.H. Han1, S.H. Hong1, Y.H. Choi3
  • 1Dongeui University College of Natural Sciences and Human Ecology, Busan/KR
  • 2Dong-A University College of Medicine and Mitochondria Hub Regulation Center, Busan/KR
  • 3Dongeui University, Busan/KR

Abstract

Introduction

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily. It has been shown that TRAIL is an attractive target for cancer therapy due to its ability to selectively induce apoptosis in cancer cells, without causing significant toxicity in normal tissues. However, several cancer cells have acquired potent resistance to TRAIL-induced cell death by unknown mechanisms. The fungal drug cordycepin (3'-deoxyadenosine) is the major bioactive substance produced by Cordyceps militaris, a traditional medicinal mushroom, and induces cytotoxicity in a variety of cancer cell lines. However, the molecular mechanisms of cordycepin triggers TRAIL-induced cell death in cancer cells have not been clearly elucidated yet. Here, we investigated the ability of cordycepin to sensitize TRAIL-mediated apoptosis in human gastric carcinoma AGS cells.

Methods

The inhibition of cell growth was evaluated by MTT assays, and the apoptosis was determined by the DAPI staining, DNA fragmentation and flow cytometry. JC-1 fluorescence probe was used to examine the mitochondria membrane potential (MMP, Δ&psgr;m). The protein levels and caspases activity were measured using Western blot analyses and colorimetric assay, respectively.

Results

In this study, we show that cordycepin sensitized TRAIL-resistant AGS cells to TRAIL-mediated apoptosis, compared with either agent alone. The induction of apoptotic cell death by combined treatment with cordycepin and TRAIL was connected with a down-regulation of cellular FLICE-inhibitory proteins (cFLIP(L) and cFLIP(S)), total Bid, Bcl-2, X-linked inhibitor of apoptosis protein (XIAP), cIAP-1 and cIAP-2. Combined treatment with cordycepin and TRAIL also induced the proteolytic activation of caspases (-3, -8 and -9), and degradation of caspase-3 substrate proteins, such as poly(ADP-ribose) polymerase (PARP) and ß-catenin. Interestingly, cordycepin treatment triggered phosphorylation of p38 mitogen-activated protein kinase (MAPK) and AMP-activated protein kinase (AMPK). Pretreatment with SB203580, an inhibitor of p38 MAPK, resulted in a significant inhibition of apoptosis induced by combined treatment with cordycepin and TRAIL; however, compound C, a specific inhibitor of AMPK, had no effects.

Conclusion

The present results show that cordycepin enhances TRAIL-mediated apoptosis in AGS cells via p38 MAPK-dependent and AMPK-independent signaling pathways, indicating that combined treatment of TRAIL-resistant AGS cells with TRAIL and cordycepin may offer an effective therapeutic strategy. [This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2014R1A1A1008460 & 2012046358)].