Celastrol is a triterpene phytochemical known to possess anti‑inflammatory, antioxidant and anticancer properties. The present study investigated the effects of celastrol on tumor necrosis factor‑related apoptosis‑inducing ligand receptor 2 (TRAIL‑R2)‑mediated apoptosis and cytotoxicity in human renal cell carcinoma (RCC) cells when administered in combination with lexatumumab, a human monoclonal agonistic antibody that specifically recognizes TRAIL‑R2. Cytotoxicity was determined by colorimetric assays of cell viability using cell counting kit‑8. The activation of caspases was assessed by quantitative colorimetric assays using caspase‑specific kits. Celastrol significantly enhanced lexatumumab‑induced apoptosis and cytotoxicity in RCC cells. An enhanced effect was also achieved when the duration of treatment with lexatumumab and celastrol was reduced from 24 to 6 h. The expression of TRAIL‑R2 was also remarkably increased by celastrol. Combined treatment with lexatumumab and celastrol significantly triggered activation of the caspase cascade, including caspase‑8, ‑9, ‑6, and ‑3, downstream molecules of death receptors. Furthermore, the cytotoxicity induced by that combination was significantly suppressed by the DR5:Fc chimeric protein, as well as specific inhibitors of caspase‑8, ‑9, ‑6 and ‑3. Taken together, these results indicated that celastrol enhances both TRAIL‑R2‑mediated apoptosis and cytotoxicity by upregulating TRAIL‑R2 and activating the caspase cascade, indicating the possibility of using it in combination with lexatumumab as an innovative therapeutic strategy for treating RCC.

中文翻译：

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Celastrol 以 caspase 依赖性方式增强 TRAIL-R2 介导的人肾细胞癌细胞凋亡和细胞毒性。

雷公藤红素是一种三萜植物化学物质，具有抗炎、抗氧化和抗癌特性。本研究调查了雷公藤红醇与人单克隆激动剂 lexatumumab 联合用药时对人肾细胞癌 (RCC) 细胞中肿瘤坏死因子相关凋亡诱导配体受体 2 (TRAIL-R2) 介导的细胞凋亡和细胞毒性的影响。特异性识别 TRAIL-R2 的抗体。使用细胞计数试剂盒 8 通过比色法测定细胞活力来确定细胞毒性。使用 caspase 特异性试剂盒通过定量比色测定来评估 caspase 的激活。Celastrol 显着增强 lexatumumab 诱导的 RCC 细胞凋亡和细胞毒性。当 lexatumumab 和雷公藤红醇的治疗持续时间从 24 小时缩短至 6 小时时，也取得了增强的效果。雷公藤红素也显着增加了 TRAIL-R2 的表达。lexatumumab 和雷公藤红素联合治疗显着触发了 caspase 级联的激活，包括死亡受体下游分子 caspase-8、-9、-6 和 -3。此外，DR5:Fc 嵌合蛋白以及 caspase-8、-9、-6 和 -3 的特异性抑制剂显着抑制了该组合诱导的细胞毒性。总而言之，这些结果表明雷公藤红素通过上调 TRAIL-R2 和激活 caspase 级联来增强 TRAIL-R2 介导的细胞凋亡和细胞毒性，表明将其与 lexatumumab 联合使用作为治疗 RCC 的创新治疗策略的可能性。