The diterpenoid ester ingenol mebutate (IngMeb) is the active ingredient in the topical drug Picato, a first-in-class treatment for the precancerous skin condition actinic keratosis. IngMeb is proposed to exert its therapeutic effects through a dual mode of action involving (i) induction of cell death that is associated with mitochondrial dysfunction followed by (ii) stimulation of a local inflammatory response, at least partially driven by protein kinase C (PKC) activation. Although this therapeutic model has been well characterized, the complete set of molecular targets responsible for mediating IngMeb activity remains ill-defined. Here, we have synthesized a photoreactive, clickable analogue of IngMeb and used this probe in quantitative proteomic experiments to map several protein targets of IngMeb in human cancer cell lines and primary human keratinocytes. Prominent among these targets was the mitochondrial carnitine-acylcarnitine translocase SLC25A20, which we show is inhibited in cells by IngMeb and the more stable analogue ingenol disoxate (IngDsx), but not by the canonical PKC agonist 12-O-tetradecanoylphorbol-13-acetate (TPA). SLC25A20 blockade by IngMeb and IngDsx leads to a buildup of cellular acylcarnitines and blockade of fatty acid oxidation (FAO), pointing to a possible mechanism for IngMeb-mediated perturbations in mitochondrial function.

中文翻译：

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化学蛋白质组学鉴定SLC25A20为光化性角化病药物中丁香酚类的功能靶标

二萜酸酯丁二醇甲磺酸丁酸酯（IngMeb）是局部用药Picato中的活性成分，Picato是针对癌前皮肤病性光化性角化病的一流治疗药物。提议IngMeb通过双重作用方式发挥其治疗作用，该双重作用方式包括（i）诱导与线粒体功能障碍有关的细胞死亡，然后（ii）刺激至少部分由蛋白激酶C（PKC）驱动的局部炎症反应）激活。尽管已经很好地表征了这种治疗模型，但负责介导IngMeb活性的完整分子靶标集仍然不清楚。在这里，我们合成了光反应性，可点击的IngMeb类似物，并在定量蛋白质组学实验中使用了该探针，以绘制IngMeb在人类癌细胞系和原代人角质形成细胞中的几种蛋白质靶标。这些靶标中最显着的是线粒体肉碱-酰基肉碱转位酶SLC25A20，我们证明了它在细胞中受到IngMeb和更稳定的类似豆蔻二氧萘酸酯（IngDsx）的抑制，但不受规范的PKC激动剂12-O-十四烷酰基佛波醇-13-乙酸酯（TPA）。IngMeb和IngDsx对SLC25A20的阻滞导致细胞酰基肉碱的积累和脂肪酸氧化（FAO）的阻滞，这表明IngMeb介导的线粒体功能紊乱的可能机制。