Chemical Proteomics Reveals Ferrochelatase as a Common Off-target of Kinase Inhibitors
Chemical Proteomics Reveals Ferrochelatase as a Common Off-target of Kinase Inhibitors
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DOI：
10.1021/acschembio.5b01063
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发表时间：
2016-05-01
影响因子：
4
通讯作者：
Kuster, Bernhard
中科院分区：
文献类型：
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作者：
Klaeger, Susan;Gohlke, Bjoern;Kuster, Bernhard
许多蛋白激酶是肿瘤学中有效的药物靶标，因为它们是信号转导途径的关键组分。临床激酶抑制剂的数量正在增加，但这些分子通常表现出多药理学，可能引起预期的毒性作用。因此，需要对化合物的靶向空间进行全面评估，以便更好地了解其生物效应。酶亚铁螯合酶（FECH）催化原卟啉IX转化为血红素，最近发现是BRAF抑制剂维罗非尼的脱靶点，这可能解释了黑色素瘤患者中与该药物相关的光毒性。这就提出了一个问题，即FECH结合是否是激酶抑制剂的一个更普遍的特征。为了解决这个问题，我们应用了一种使用kinobeads的化学蛋白质组学方法来评估226种临床激酶抑制剂结合FECH的能力。令人惊讶的是，对于所有测试的化合物中的29种，检测到低或亚微摩尔FECH结合，并且等温剂量响应测量证实了细胞中的靶结合。我们还表明，Vemurafenib，Linsitinib，Neratinib和MK-2461可降低K562细胞中的血红素水平，验证了药物结合导致FECH活性丧失。进一步的生物化学和对接实验确定了FECH中的原卟啉口袋作为一个主要的药物结合位点。由于FECH活性的遗传丢失导致人类的光敏性，我们的数据强烈表明激酶抑制剂对FECH的抑制是触发患者光敏性的分子机制。因此，我们建议，FECH测定一般应是激酶抑制剂开发的临床前分子毒理学包的一部分。
Many protein kinases are valid drug targets in oncology because they are key components of signal transduction pathways. The number of clinical kinase inhibitors is on the rise, but these molecules often exhibit polypharmacology, potentially eliciting desired and toxic effects. Therefore, a comprehensive assessment of a compound's target space is desirable for a better understanding of its biological effects. The enzyme ferrochelatase (FECH) catalyzes the conversion of protoporphyrin IX into heme and was recently found to be an off-target of the BRAF inhibitor Vemurafenib, likely explaining the phototoxicity associated with this drug in melanoma patients. This raises the question of whether FECH binding is a more general feature of kinase inhibitors. To address this, we applied a chemical proteomics approach using kinobeads to evaluate 226 clinical kinase inhibitors for their ability to bind FECH. Surprisingly, low or submicromolar FECH binding was detected for 29 of all compounds tested and isothermal dose response measurements confirmed target engagement in cells. We also show that Vemurafenib, Linsitinib, Neratinib, and MK-2461 reduce heme levels in K562 cells, verifying that drug binding leads to a loss of FECH activity. Further biochemical and docking experiments identified the protoporphyrin pocket in FECH as one major drug binding site. Since the genetic loss of FECH activity leads to photosensitivity in humans, our data strongly suggest that FECH inhibition by kinase inhibitors is the molecular mechanism triggering photosensitivity in patients. We therefore suggest that a FECH assay should generally be part of the preclinical molecular toxicology package for the development of kinase inhibitors.