Comprehensive chemical proteomics analyses reveal that the new TRi-1 and TRi-2 compounds are more specific thioredoxin reductase 1 inhibitors than Auranofin

Anticancer drugs that target cellular antioxidant systems have recently attracted much attention. Auranofin (AF) is currently evaluated in several clinical trials as an anticancer agent and targets the cytosolic and mitochondrial forms of the selenoprotein thioredoxin reductase, Txnrd1 and Txnrd2. Recently, two novel Txnrd1 inhibitors (TRi-1 and TRi-2) have been developed that showed anticancer efficacy comparable to AF, but with lower mitochondrial toxicity. However, the cellular action mechanisms of these drugs have not yet been thoroughly studied. Here we used several proteomics analyses to determine the effects of AF, TRi-1 and TRi-2 when used at IC50 concentrations with the mouse B16 melanoma and LLC lung adenocarcinoma cells, as these are often used for preclinical mouse models in evaluation of anticancer drugs. The results demonstrate that TRi-1 and TRi-2 are more specific Txnrd1 inhibitors than AF and reveal additional AF-specific effects on the cellular proteome. Interestingly, AF triggered stronger Nrf2-driven antioxidant responses than the other two compounds. Furthermore, AF affected several additional proteins, including Gsk3a, Gsk3b, Mcmbp and Eefsec, implicating additional effects on glycogen metabolism, cellular differentiation, inflammatory pathways, DNA replication and selenoprotein synthesis processes. Our proteomics data should represent a resource for researchers interested in the multidimensional analysis of proteome changes associated with oxidative stress in general, and the effects of Txnrd inhibitors and AF protein targets in particular.

靶向细胞抗氧化系统的抗癌药物近年来受到广泛关注。金诺芬（Auranofin, AF）目前已在多项临床试验中作为抗癌药剂进行评估，其靶点为硒蛋白硫氧还蛋白还原酶的胞质亚型与线粒体亚型Txnrd1和Txnrd2。近期，研究人员开发了两种新型Txnrd1抑制剂（TRi-1与TRi-2），其抗癌疗效与AF相当，但线粒体毒性更低。然而，此类药物的细胞作用机制尚未得到充分阐明。本研究采用多种蛋白质组学分析方法，以AF、TRi-1、TRi-2在半数抑制浓度（IC50）下处理小鼠B16黑色素瘤细胞与LLC肺腺癌细胞——这两种细胞系常用于抗癌药物评估的临床前小鼠模型——以探究三者的细胞效应。研究结果显示，TRi-1与TRi-2相较于AF是特异性更强的Txnrd1抑制剂，并揭示了AF对细胞蛋白质组的特有调控效应。值得注意的是，相较于另外两种化合物，AF诱导的核因子E2相关因子2（nuclear factor erythroid 2-related factor 2, Nrf2）介导的抗氧化应答更为强烈。此外，AF还影响了包括Gsk3a、Gsk3b、Mcmbp与Eefsec在内的多种其他蛋白质，提示其对糖原代谢、细胞分化、炎症通路、DNA复制以及硒蛋白合成过程存在额外调控作用。本研究产生的蛋白质组学数据，可为关注氧化应激相关蛋白质组变化的多维度分析、以及Txnrd抑制剂与AF蛋白质靶点效应的研究人员提供参考资源。