Hundreds of cytotoxic natural or synthetic lipidic compounds contain chiral alkynylcarbinol motifs, but the mechanism of action of those potential therapeutic agents remains unknown. Using a genetic screen in haploid human cells, we discovered that the enantiospecific cytotoxicity of numerous terminal alkynylcarbinols, including the highly cytotoxic dialkynylcarbinols, involves a bioactivation by HSD17B11, a short-chain dehydrogenase/reductase (SDR) known to oxidize the C-17 carbinol center of androstan-3-alpha,17-beta-diol to the corresponding ketone. A similar oxidation of dialkynylcarbinols generates dialkynylketones, that we characterize as highly protein-reactive electrophiles. We established that, once bioactivated in cells, the dialkynylcarbinols covalently modify several proteins involved in protein-quality control mechanisms, resulting in their lipoxidation on cysteines and lysines through Michael addition. For some proteins, this triggers their association to cellular membranes and results in endoplasmic reticulum stress, unfolded protein response activation, ubiquitin-proteasome system inhibition and cell death by apoptosis. Finally, as a proof-of-concept, we show that generic lipidic alkynylcarbinols can be devised to be bioactivated by other SDRs, including human RDH11 and HPGD/15-PGDH. Given that the SDR superfamily is one of the largest and most ubiquitous, this unique cytotoxic mechanism-of-action could be widely exploited to treat diseases, in particular cancer, through the design of tailored prodrugs.
数百种具有细胞毒性的天然或合成脂质化合物都含有手性炔基甲醇基团,但这些潜在治疗药物的作用机制仍不清楚。通过在单倍体人体细胞中进行基因筛选,我们发现包括高细胞毒性二炔基甲醇在内的多种末端炔基甲醇的对映体特异性细胞毒性涉及到 HSD17B11 的生物活化,HSD17B11 是一种短链脱氢酶/还原酶(SDR),已知可将雄甾烷-3-alpha,17-beta-二醇的 C-17 甲醇中心氧化为相应的酮。二炔基甲醇的类似氧化反应会生成二炔基酮,我们将其描述为具有高度蛋白质反应性的亲电体。我们发现,一旦在细胞中发生生物活化,二炔基甲醇就会对参与蛋白质质量控制机制的几种蛋白质进行共价修饰,从而通过迈克尔加成作用使半胱氨酸和赖氨酸发生脂氧化反应。对于某些蛋白质来说,这会引发它们与细胞膜的结合,导致内质网应激、未折叠蛋白反应激活、泛素-蛋白酶体系统抑制和细胞凋亡。最后,作为概念验证,我们展示了通用脂质炔烃醇可被其他 SDR(包括人类 RDH11 和 HPGD/15-PGDH)生物激活。鉴于 SDR 超家族是规模最大、最普遍的超家族之一,这种独特的细胞毒性作用机制可被广泛利用,通过设计量身定制的原药来治疗疾病,尤其是癌症。