Department of Microbiology and Immunology, Medical University of Silesia in Katowice, 41808 Zabrze, Poland.
Int J Oncol. 2011 Oct;39(4):771-9. doi: 10.3892/ijo.2011.1116. Epub 2011 Jul 6.
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an endogenous agent that induces apoptosis selectively in cancer cells. Soluble or expressed in immune cells, TRAIL plays an important role in the defense against tumour cells. The resistance of cancer cells to TRAIL immune surveillance is implicated in tumour development. Naturally occurring flavonoids can sensitize TRAIL-resistant cancer cells and augment their apoptotic activity. Fisetin, a dietary flavonol has cancer preventive properties. This study was designed to investigate the effect of fisetin on the TRAIL-induced apoptosis potential in prostate cancer cells. Prostate cancer cell lines represent an ideal model for research in chemoprevention. Cytotoxicity was measured by MTT and LDH assays. Apoptosis was detected using Αnnexin V-FITC by flow cytometry and fluorescence microscopy. Mito-chondrial membrane potential (ΔΨm) was evaluated using DePsipher staining by fluorescence microscopy. Death receptor (TRAIL-R1 and TRAIL-R2) expression was analysed by flow cytometry. Inhibition of NF-κB (p65) activation was confirmed with an ELISA-based TransAM NF-κB kit. Caspase-8 and caspase-3 activities were determined by colorimetric protease assays. Our study demonstrates that fisetin sensitizes the TRAIL-resistant androgen-dependent LNCaP and the androgen-independent DU145 and PC3 prostate cancer cells to TRAIL-induced death. Fisetin augmented TRAIL-mediated cytotoxicity and apoptosis in prostate cancer LNCaP cells by engaging the extrinsic (receptor-mediated) and intrinsic (mitochondrial) apoptotic pathways. Fisetin increased the expression of TRAIL-R1 and decreased the activity of NF-κB. Co-treatment of cancer cells with TRAIL and fisetin caused significant activation of caspase-8 and caspase-3 and disruption of ΔΨm. Our data indicate the usefulness of fisetin in prostate cancer chemoprevention through enhancement of TRAIL-mediated apoptosis.
肿瘤坏死因子相关凋亡诱导配体（TRAIL）是一种内源性物质，可选择性诱导癌细胞凋亡。TRAIL 以可溶性或免疫细胞表达形式存在，在肿瘤细胞免疫监视中发挥重要作用。癌细胞对 TRAIL 的免疫逃避与肿瘤的发生有关。天然存在的类黄酮可以使 TRAIL 耐药的癌细胞敏感，并增强其凋亡活性。漆黄素，一种饮食类黄酮，具有预防癌症的特性。本研究旨在探讨漆黄素对前列腺癌细胞中 TRAIL 诱导凋亡潜力的影响。前列腺癌细胞系是化学预防研究的理想模型。通过 MTT 和 LDH 测定法测量细胞毒性。通过流式细胞术和荧光显微镜检测 Annexin V-FITC 检测凋亡。通过荧光显微镜用 DePsipher 染色评估线粒体膜电位（ΔΨm）。通过流式细胞术分析死亡受体（TRAIL-R1 和 TRAIL-R2）的表达。使用基于 ELISA 的 TransAM NF-κB 试剂盒确认 NF-κB（p65）激活的抑制作用。通过比色蛋白酶测定法测定半胱天冬酶-8 和半胱天冬酶-3 的活性。我们的研究表明，漆黄素使 TRAIL 耐药的雄激素依赖性 LNCaP 和雄激素非依赖性 DU145 和 PC3 前列腺癌细胞对 TRAIL 诱导的死亡敏感。漆黄素通过激活外源性（受体介导）和内源性（线粒体）凋亡途径，增强 TRAIL 介导的前列腺癌细胞 LNCaP 中的细胞毒性和凋亡。漆黄素增加了 TRAIL-R1 的表达，降低了 NF-κB 的活性。TRAIL 和漆黄素共同处理癌细胞导致 caspase-8 和 caspase-3 的显著激活和ΔΨm 的破坏。我们的数据表明，通过增强 TRAIL 介导的凋亡，漆黄素在前列腺癌化学预防中具有重要作用。
