Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Br J Pharmacol. 2011 Nov;164(5):1433-44. doi: 10.1111/j.1476-5381.2011.01419.x.
Methyl jasmonate (MJ) is a plant stress hormone with selective cytotoxic anti-cancer activities. The TNF-related apoptosis-inducing ligand (TRAIL) death pathway is an attractive target for cancer therapy. Although TRAIL receptors are specifically expressed in primary cancer cells and cancer cell lines, many types of cancer cells remain resistant to TRAIL-induced cytotoxicity. Here we have assessed a possible synergy between MJ and TRAIL cytotoxicity in colorectal cancer (CRC) cell lines.
CRC cell lines were pre-incubated with sub-cytotoxic concentrations of MJ followed by TRAIL administration. Cell death was determined by XTT assay and microscopy. Cytochrome c release, caspase cleavage, TRAIL-associated factors, X-linked inhibitor of apoptosis (XIAP) and survivin protein levels were detected by immunoblotting. Survivin transcription was examined by RT-PCR.
Pre-treatment with MJ resulted in increased TRAIL-induced apoptotic cell death, increased cytochrome c release and caspase cleavage. TNFRSF10A, TNFRSF10B, TNFRSF10D, Fas-associated death domain and cellular FLICE-like inhibitory protein remained unchanged during MJ-induced TRAIL sensitization, whereas MJ induced a significant decrease in survivin protein levels. Overexpression of survivin prevented MJ-induced TRAIL cytotoxicity, implying a role for survivin in MJ-induced TRAIL sensitization. MJ decreased survivin mRNA indicating that MJ may affect survivin transcription. In a β-catenin/transcription factor (TCF)-dependent luciferase activity assay, MJ decreased TCF-dependent transcriptional activity.
MJ, at sub-cytotoxic levels, sensitized CRC cells to TRAIL-induced apoptosis. Thus, combinations of MJ and TRAIL, both selective anti-cancer agents, have potential as novel treatments for CRC.
茉莉酸甲酯（MJ）是一种植物应激激素，具有选择性细胞毒性抗癌活性。肿瘤坏死因子相关凋亡诱导配体（TRAIL）死亡途径是癌症治疗的一个有吸引力的靶点。尽管 TRAIL 受体特异性表达于原发性癌细胞和癌细胞系中，但许多类型的癌细胞仍然对 TRAIL 诱导的细胞毒性具有抗性。在这里，我们评估了 MJ 和 TRAIL 细胞毒性在结直肠癌（CRC）细胞系中的协同作用。
CRC 细胞系先用亚细胞毒性浓度的 MJ 孵育，然后再用 TRAIL 处理。用 XTT 测定法和显微镜观察细胞死亡。通过免疫印迹检测细胞色素 c 释放、半胱天冬酶切割、TRAIL 相关因子、X 连锁凋亡抑制蛋白（XIAP）和生存素蛋白水平。通过 RT-PCR 检测生存素转录。
MJ 预处理导致 TRAIL 诱导的凋亡细胞死亡增加、细胞色素 c 释放和半胱天冬酶切割增加。TNFRSF10A、TNFRSF10B、TNFRSF10D、Fas 相关死亡结构域和细胞 FLICE 样抑制蛋白在 MJ 诱导的 TRAIL 增敏过程中保持不变，而 MJ 诱导生存素蛋白水平显著降低。生存素的过表达可阻止 MJ 诱导的 TRAIL 细胞毒性，表明生存素在 MJ 诱导的 TRAIL 增敏中起作用。MJ 降低了生存素 mRNA，表明 MJ 可能影响生存素转录。在β-连环蛋白/转录因子（TCF）依赖性荧光素酶活性测定中，MJ 降低了 TCF 依赖性转录活性。
亚细胞毒性浓度的 MJ 使 CRC 细胞对 TRAIL 诱导的凋亡敏感。因此，MJ 和 TRAIL 的联合应用，作为两种选择性抗癌药物，具有作为 CRC 新型治疗方法的潜力。
