Lucanthone Is a Novel Inhibitor of Autophagy That Induces Cathepsin D-mediated Apoptosis
Lucanthone Is a Novel Inhibitor of Autophagy That Induces Cathepsin D-mediated Apoptosis
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DOI：
10.1074/jbc.m110.151324
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发表时间：
2011-02-25
影响因子：
4.8
通讯作者：
Nawrocki, Steffan T.
中科院分区：
文献类型：
--
作者：
Carew, Jennifer S.;Espitia, Claudia M.;Nawrocki, Steffan T.
由营养剥夺、缺氧和暴露于许多化学治疗剂诱导的细胞应激激活称为自噬的进化保守的细胞存活途径。这种途径使癌细胞能够进行自我消化，产生ATP和其他必要的生物合成分子，以暂时避免细胞死亡。因此，自噬的破坏可能使癌细胞对细胞死亡敏感并增加化疗诱导的细胞凋亡。氯喹及其类似物羟氯喹是唯一临床相关的自噬抑制剂。由于这两种药物均诱导眼毒性，因此需要具有更好治疗指数的新型自噬抑制剂。在这里，我们证明了小分子lucanthone抑制自噬，诱导溶酶体膜透化，并在乳腺癌模型中具有比氯喹更有效的活性。暴露于lucanthone导致微管相关蛋白1轻链3（LC 3）的处理和招聘的自噬体，但受损的自噬降解所揭示的透射电子显微镜和积累的p62/SQSTM 1。微阵列分析、qRT-PCR和免疫印迹法确定，紫丁香酮刺激了组织蛋白酶D的大量诱导，这与细胞死亡相关。因此，敲低组织蛋白酶D减少了Lucanthone介导的细胞凋亡。随后使用p53（+/+）和p53（-/-）HCT 116细胞的研究证实，不依赖于p53状态，紫锥菊酮诱导组织蛋白酶D表达并降低癌细胞活力。此外，Lucanthone增强了组蛋白去乙酰化酶抑制剂伏立诺他的抗癌活性。总的来说，我们的研究结果表明，lucanthone是一种新的自噬抑制剂，通过组织蛋白酶D的积累诱导细胞凋亡，并增强伏立诺他介导的乳腺癌模型中的细胞死亡。
Cellular stress induced by nutrient deprivation, hypoxia, and exposure to many chemotherapeutic agents activates an evolutionarily conserved cell survival pathway termed autophagy. This pathway enables cancer cells to undergo self-digestion to generate ATP and other essential biosynthetic molecules to temporarily avoid cell death. Therefore, disruption of autophagy may sensitize cancer cells to cell death and augment chemotherapy-induced apoptosis. Chloroquine and its analog hydroxychloroquine are the only clinically relevant autophagy inhibitors. Because both of these agents induce ocular toxicity, novel inhibitors of autophagy with a better therapeutic index are needed. Here we demonstrate that the small molecule lucanthone inhibits autophagy, induces lysosomal membrane permeabilization, and possesses significantly more potent activity in breast cancer models compared with chloroquine. Exposure to lucanthone resulted in processing and recruitment of microtubule-associated protein 1 light chain 3 (LC3) to autophagosomes, but impaired autophagic degradation as revealed by transmission electron microscopy and the accumulation of p62/SQSTM1. Microarray analysis, qRT-PCR, and immunoblotting determined that lucanthone stimulated a large induction in cathepsin D, which correlated with cell death. Accordingly, knockdown of cathepsin D reduced lucanthone-mediated apoptosis. Subsequent studies using p53(+/+) and p53(-/-) HCT116 cells established that lucanthone induced cathepsin D expression and reduced cancer cell viability independently of p53 status. In addition, lucanthone enhanced the anticancer activity of the histone deacetylase inhibitor vorinostat. Collectively, our results demonstrate that lucanthone is a novel autophagic inhibitor that induces apoptosis via cathepsin D accumulation and enhances vorinostat-mediated cell death in breast cancer models.