Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a newly identified biological agent has shown promising antitumor effects in a wide range of cancers. However, gastric cancer cells are less sensitive than other cancer cells to TRAIL-induced apoptosis. Here, we combined TRAIL with bortezomib, a proteasomal inhibitor to induce apoptosis in three gastric cancer cell lines.

Methods

After the cells were treated with TRAIL and/or bortezomib, the cell viability, apoptosis and cell cycle distribution were examined. The levels of death receptors and the mitochondrial membrane potential were also detected. The expression of apoptosis-associated proteins was determined by Western blot.

Bortezomib at low concentration significantly (P < 0.05) enhanced the cytotoxic effect of TRAIL by enhancing apoptosis as well as cell cycle arrest at G2/M phase. The enhancement of efficiency of TRAIL by bortezomib involved up-regulation of death receptor 4 and 5, as well as reduction of the mitochondrial membrane potential. Further study showed that combined treatment with TRAIL and bortezomib down-regulated anti-apoptotic protein cIAP-1, and over expression of cIAP-1 significantly (P < 0.05) reduced the synergistic effect between TRAIL and bortezomib.

Bortezomib synergizes TRAIL-induced apoptosis in human gastric cancer cells. The synergistic effect between these two drugs is associated with up-regulation of death receptors and down-regulation of cIAP-1. The combination of TRAIL and bortezomib might be an effective regimen for the treatment of advanced gastric cancer.

PMID: 20393880 [PubMed - as supplied by publisher] Source: National Library of Medicine.