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Downregulation of DcR3 sensitizes hepatocellular carcinoma cells to TRAIL-induced apoptosis

Authors Liang CJ, Xu YC, Li GM, Zhao TJ, Xia F, Li GQ, Zhang D, Wu JX

Received 10 November 2016

Accepted for publication 5 December 2016

Published 18 January 2017 Volume 2017:10 Pages 417—428

DOI https://doi.org/10.2147/OTT.S127202

Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Amy Norman

Peer reviewer comments 2

Editor who approved publication: Dr William Cho

Chaojie Liang,* Yingchen Xu,* Guangming Li, Tuanjie Zhao, Feng Xia, Guanqun Li, Dongxin Zhang, Jixiang Wu

Department of General Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, People’s Republic of China

*These authors contributed equally to this work

Abstract: Decoy receptor 3 (DcR3) has been recently described as an antiapoptosis and prometastasis factor since it can competitively bind to FasL, TL1A, and LIGHT, and it is highly expressed in many malignant tumors. Downregulation of DcR3 can promote tumor cell apoptosis and inhibit metastasis. A previous study demonstrated that reduction of DcR3 could induce tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis in pancreatic cancer cells. However, whether such an effect is seen in hepatocellular carcinoma (HCC) remains to be explored. This study was designed to investigate the sensitivity of HCC cells to TRAIL after silencing DcR3, and this was done by evaluating the expression of DcR3 in HCC cells and the effect on TRAIL-mediated apoptosis after downregulation of DcR3. Our data showed that DcR3 was highly expressed in HepG2, BEL-7402, Hep3B, Huh-7, MHCC97H, and SMCC7721 cell lines compared with normal liver cell line LO-2. Both HepG2 and BEL-7402 were tolerant to TRAIL-mediated apoptosis, and the tolerance was negatively correlated to the expression of DcR3. Silencing of DcR3 with shRNA and treatment with TRAIL induced obvious apoptosis in HepG2 and BEL-7402, with more cancer cells found in the G1 phase. SiDcR3 combined with TRAIL could induce activation of caspases-3, -8, and -9, raise the expression of the apoptotic protein Bax, and reduce the expression of antiapoptotic proteins (Bcl-2, Mcl-1, Bcl-XL, IAP-2, and survivin). Caspase-8 inhibitor Ac-IETD-CHO significantly decreased the activation of caspase cascade, indicating that the extrinsic pathway may have a vital role in the apoptotic events induced by SiDcR3/TRAIL. Furthermore, our results showed that the TRAIL death receptor 5 (DR5) was upregulated and that DR5 neutralizing antibody abrogated the effect of SiDcR3. Our results demonstrated that downregulation of DcR3 could enhance TRAIL-mediated apoptosis in HCC through the death receptor pathway. In the future, this might be useful as a clinical treatment method of liver cancer.

Keywords: apoptosis, DcR3, TRAIL, HCC, DR5, caspase-8

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