Discovery of a small molecule targeting autophagy via ATG4B inhibition and cell death of colorectal cancer cells in vitro and in vivo
Discovery of a small molecule targeting autophagy via ATG4B inhibition and cell death of colorectal cancer cells in vitro and in vivo
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发现一种通过体外和体内 ATG4B 抑制和结直肠癌细胞细胞死亡靶向自噬的小分子
DOI：
10.1080/15548627.2018.1517073
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发表时间：
2019-02-01
期刊：
影响因子：
13.3
通讯作者：
Li, Min
中科院分区：
文献类型：
--
作者：
Fu, Yuanyuan;Hong, Liang;Li, Min
人类Atg 4同源物是一种半胱氨酸蛋白酶，它通过切割Atg 8同源物与脂膜结合以及Atg 8同源物与脂膜解结合，在巨自噬/自噬过程中发挥关键作用。与正常细胞相比，ATG 4 B在结直肠癌细胞中的表达显著增加，这表明ATG 4 B可能对癌症生物学很重要。ATG 4 B的抑制可以降低自噬活性，从而使癌细胞对治疗剂敏感。因此，非常需要开发用于研究以及用于潜在治疗用途的特异性和有效的ATG 4 B抑制剂。在这项研究中，我们整合了计算机筛选和体外试验，从非商业文库中发现了一种有效的ATG 4 B抑制剂，命名为S130。该化学物质以强亲和力与ATG 4 B结合，并特异性抑制ATG 4 B的活性，但不抑制其他蛋白酶的活性。S130不引起自噬体融合障碍，也不引起溶酶体功能障碍。相反，S130可能减弱自溶酶体上LC 3-II的脱脂，以抑制LC 3-I的再循环，这通常发生在ATG 4 B切割LC 3-II之后。有趣的是，S130诱导细胞死亡，这伴随着自噬应激，并可能因营养剥夺而进一步加剧。这种细胞毒性可以通过增强ATG 4 B活性而部分逆转。最后，我们发现S130在体内肿瘤组织中分布，并且也有效地抑制结直肠癌细胞的生长。因此，这项研究表明，ATG 4 B是一个潜在的抗癌靶点，S130可能是未来癌症治疗的新的小分子候选者。
ABSTRACT Human Atg4 homologs are cysteine proteases, which play key roles in the macroautophagy/autophagy process by cleaving Atg8 homologs for conjugation to lipid membranes and for deconjugation of Atg8 homologs from membranes. Expression of ATG4B is significantly increased in colorectal cancer cells compared to normal cells, suggesting that ATG4B may be important for cancer biology. Inhibition of ATG4B may reduce the autophagy activity, thereby sensitizing cancer cells to therapeutic agents. Thus, developing specific and potent ATG4B inhibitors for research as well as for potential therapeutic uses is highly needed. In this study, we integrated in silico screening and in vitro assays to discover a potent ATG4B inhibitor, named S130, from a noncommercial library. This chemical binds to ATG4B with strong affinity and specifically suppresses the activity of ATG4B but not other proteases. S130 did not cause the impairment of autophagosome fusion, nor did it result in the dysfunction of lysosomes. Instead, S130 might attenuate the delipidation of LC3-II on the autolysosomes to suppress the recycling of LC3-I, which normally occurs after LC3-II cleavage by ATG4B. Intriguingly, S130 induced cell death, which was accompanied with autophagy stress and could be further exacerbated by nutrient deprivation. Such cytotoxicity could be partially reversed by enhancing ATG4B activity. Finally, we found that S130 was distributed in tumor tissues in vivo and was also effective in arresting the growth of colorectal cancer cells. Thus, this study indicates that ATG4B is a potential anticancer target and S130 might be a novel small-molecule candidate for future cancer therapy.