Departments of Medicine (Oncology) (J.S., E.A., E.L.S.) and Biochemistry (L.U.N.), Albert Einstein College of Medicine and the Einstein Cancer Center, Bronx, New York.
Departments of Medicine (Oncology) (J.S., E.A., E.L.S.) and Biochemistry (L.U.N.), Albert Einstein College of Medicine and the Einstein Cancer Center, Bronx, New York
Mol Pharmacol. 2019 Jan;95(1):127-138. doi: 10.1124/mol.118.113118. Epub 2018 Nov 8.
Lysosomes degrade cellular proteins and organelles and regulate cell signaling by providing a surface for the formation of critical protein complexes, notably molecular target of rapamycin (mTOR) complex 1 (mTORC1). Striking differences in the lysosomes of cancer versus normal cells suggest that they could be targets for drug development. Although the lysomotropic drugs chloroquine (CQ) and hydroxychloroquine (HCQ) have been widely investigated, studies have focused on their ability to inhibit autophagy. We synthesized a novel compound, called EAD1, which is structurally related to CQ but is a 14-fold more potent inhibitor of cell proliferation. Here we find that EAD1 causes rapid relocation, membrane permeabilization (LMP), and deacidification of lysosomes, and it induces apoptosis and irreversibly blocks proliferation of human lung cancer H460, H520, H1299, HCC827, and H1703 cells. EAD1 causes dissociation of mTOR from lysosomes and increases mTOR's perinuclear versus cytoplasmic localization, changes previously shown to inactivate mTORC1. The effect on mTOR was not seen with HCQ, even at >10-fold greater concentrations. Phosphorylation of a downstream target of mTORC1, ribosomal protein S6, was inhibited by EAD1. Although EAD1 also inhibited autophagy, it retained full antiproliferative activity in autophagy-deficient H1650 lung cancer cells, which have a biallelic deletion of Atg7, and in H460 Atg7-knockout cells. As Atg7 is critical for the canonical autophagy pathway, it is likely that inhibition of autophagy is not how EAD1 inhibits cell proliferation. Further studies are needed to determine the relationship of LMP to mTORC1 disruption and their relative contributions to drug-induced cell death. These studies support the lysosome as an underexplored target for new drug development.
溶酶体降解细胞蛋白质和细胞器，并通过提供形成关键蛋白质复合物的表面来调节细胞信号转导，特别是雷帕霉素靶蛋白（mTOR）复合物 1（mTORC1）。癌症与正常细胞的溶酶体存在显著差异，这表明它们可能成为药物开发的靶点。虽然溶酶体靶向药物氯喹（CQ）和羟氯喹（HCQ）已被广泛研究，但研究重点一直是它们抑制自噬的能力。我们合成了一种新型化合物，称为 EAD1，它与 CQ 在结构上相关，但对细胞增殖的抑制作用强 14 倍。在这里，我们发现 EAD1 导致溶酶体快速重定位、膜通透性（LMP）和去酸化，并诱导凋亡并不可逆地阻断人肺癌 H460、H520、H1299、HCC827 和 H1703 细胞的增殖。EAD1 导致 mTOR 从溶酶体解离，并增加 mTOR 的核周相对于细胞质定位，这一变化以前被证明可使 mTORC1 失活。即使 HCQ 的浓度高出 10 倍，也未观察到对 mTOR 的影响。EAD1 抑制 mTORC1 的下游靶标核糖体蛋白 S6 的磷酸化。尽管 EAD1 也抑制自噬，但在自噬缺陷型 H1650 肺癌细胞（其 Atg7 存在双等位基因缺失）和 H460 Atg7 敲除细胞中，它仍保留完全的抗增殖活性。由于 Atg7 对于经典自噬途径至关重要，因此 EAD1 抑制细胞增殖可能不是通过抑制自噬来实现的。需要进一步研究以确定 LMP 与 mTORC1 破坏的关系及其对药物诱导细胞死亡的相对贡献。这些研究支持溶酶体作为新药物开发的未充分探索靶点。
