Mori Tomohiko, Doi Ryuichiro, Kida Atsushi, Nagai Kazuyuki, Kami Kazuhiro, Ito Daisuke, Toyoda Eiji, Kawaguchi Yoshiya, Uemoto Shinji
Department of Surgery, Division of Hepato-Biliary-Pancreatic Surgery and Transplantation, Kyoto University, Kyoto, Japan.
J Surg Res. 2007 Oct;142(2):281-6. doi: 10.1016/j.jss.2007.03.068. Epub 2007 Jul 19.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent inducer of apoptosis in a wide variety of tumor cells, while it has no toxicity for the majority of normal cells.Therefore, TRAIL may be a suitable agent for anticancer therapy. We previously reported that a number of pancreatic cancer cell lines show resistance to TRAIL-induced apoptosis via overexpression of XIAP and FLIP. The present study was conducted to further examine TRAIL-based therapeutic strategies by aiming to restore functional apoptotic pathways in resistant pancreatic cancer cells.
In various pancreatic cancer cell lines, TRAIL-induced apoptosis was evaluated in the presence or absence of an XIAP-inhibitor (Smac peptide). Second, TRAIL-induced apoptosis was evaluated in TRAIL-resistant AsPC-1 cells with or without FLIP antisense. Third, the combined effect of Smac peptide and FLIP antisense was tested, and the activation of apoptosis-related caspases and poly (ADP-ribose) polymerase was evaluated. Finally, TRAIL-induced apoptosis was evaluated in the presence or absence of FLIP antisense and an XIAP inhibitor (embelin).
Smac peptide enhanced TRAIL-induced apoptosis in a dose-dependent manner for several pancreatic cancer cell lines, but showed no effect on TRAIL-resistant AsPC-1 cells. Smac peptide alone had no influence on cell viability. TRAIL-induced apoptosis was restored in TRAIL-resistant AsPC-1 cells by exposure to FLIP antisense, which suppressed the expression of FLIP. The effect of TRAIL was augmented by the combination of FLIP antisense and Smac peptide. Similarly, TRAIL-induced apoptosis was restored by the combination of FLIP antisense and embelin. Activation of apoptotic caspases and cleavage of poly (ADP-ribose) polymerase was observed after sensitization of TRAIL-resistant pancreatic cancer cells.
Pancreatic cancer cells gain resistance to TRAIL-induced apoptosis via expression of the antiapoptotic proteins XIAP and FLIP. Smac peptide and FLIP antisense could restore the apoptotic effect of TRAIL. An XIAP inhibitor, embelin, enhanced the effect of TRAIL in the presence of FLIP antisense. These findings may provide useful information for the development of TRAIL-based therapeutic strategies by restoring functional apoptotic pathways in resistant pancreatic cancer cells. In addition, a low molecular weight XIAP inhibitor like embelin could be a lead compound for the development of effective XIAP inhibitors.
肿瘤坏死因子相关凋亡诱导配体（TRAIL）是多种肿瘤细胞凋亡的有效诱导剂，而对大多数正常细胞无毒性。因此，TRAIL可能是一种合适的抗癌治疗药物。我们之前报道过，一些胰腺癌细胞系通过XIAP和FLIP的过表达对TRAIL诱导的凋亡产生抗性。本研究旨在通过恢复抗性胰腺癌细胞中功能性凋亡途径，进一步研究基于TRAIL的治疗策略。
在各种胰腺癌细胞系中，在有或无XIAP抑制剂（Smac肽）的情况下评估TRAIL诱导的凋亡。其次，在有或无FLIP反义核酸的情况下，评估TRAIL对TRAIL抗性AsPC-1细胞诱导的凋亡。第三，测试Smac肽和FLIP反义核酸的联合作用，并评估凋亡相关半胱天冬酶和聚（ADP-核糖）聚合酶的激活情况。最后，在有或无FLIP反义核酸和XIAP抑制剂（紫铆因）的情况下，评估TRAIL诱导的凋亡。
Smac肽以剂量依赖方式增强了几种胰腺癌细胞系中TRAIL诱导的凋亡，但对TRAIL抗性AsPC-1细胞无影响。单独的Smac肽对细胞活力无影响。通过暴露于FLIP反义核酸抑制FLIP的表达，TRAIL抗性AsPC-1细胞中TRAIL诱导的凋亡得以恢复。FLIP反义核酸与Smac肽联合增强了TRAIL的作用。同样，FLIP反义核酸与紫铆因联合恢复了TRAIL诱导凋亡的作用。在TRAIL抗性胰腺癌细胞致敏后，观察到凋亡半胱天冬酶的激活和聚（ADP-核糖）聚合酶的裂解。
胰腺癌细胞通过抗凋亡蛋白XIAP和FLIP的表达对TRAIL诱导的凋亡产生抗性。Smac肽和FLIP反义核酸可恢复TRAIL的凋亡作用。XIAP抑制剂紫铆因在有FLIP反义核酸存在时增强了TRAIL的作用。这些发现可能为通过恢复抗性胰腺癌细胞中功能性凋亡途径来开发基于TRAIL的治疗策略提供有用信息。此外，像紫铆因这样的低分子量XIAP抑制剂可能是开发有效XIAP抑制剂的先导化合物。
