Data-independent Proteomic Screen Identifies Novel Tamoxifen Agonist that Mediates Drug Resistance

A label-free quantitative variation of the recently developed data-independent shotgun proteomic method precursor acquisition independent from ion count (PAcIFIC) was used to identify novel proteins implicated in cancer progression and resistance. Specifically, this screen identified the pro-metastatic protein anterior gradient 2 (AGR2) as significantly up-regulated in tamoxifen-treated cells. Highlighting the need for direct proteome profiling methods like PAcIFIC, neither data-dependent gas-phase fractionation nor a transcriptomic screen detected AGR2 protein/transcript at significantly up-regulated levels. Further cell-based experiments using human cancer cell lines and in vivo xenografts confirmed the PAcIFIC hypothesis that AGR2 is up-regulated in MCF-7 cells post tamoxifen treatment and that it is implicated in drug resistance mediation.本研究采用新近开发的离子计数非依赖前体捕获（precursor acquisition independent from ion count, PAcIFIC）数据非依赖型鸟枪蛋白质组学方法的无标记定量变体，以筛选与癌症进展及耐药性相关的新型蛋白质。具体而言，本次筛选发现促转移蛋白前梯度蛋白2（anterior gradient 2, AGR2）在他莫昔芬处理的细胞中呈显著上调表达。这凸显了PAcIFIC这类直接蛋白质组谱分析方法的必要性——无论是数据依赖型气相分级分离技术，还是转录组筛选，均未检测到AGR2蛋白或转录本存在显著上调。后续通过人癌细胞系及体内异种移植模型开展的细胞实验，验证了PAcIFIC的相关假说：AGR2在他莫昔芬处理后的MCF-7细胞中表达上调，且其参与耐药性的介导过程。