Wang Mengxiong, Law Mary E, Davis Bradley J, Yaaghubi Elham, Ghilardi Amanda F, Ferreira Renan B, Chiang Chi-Wu, Guryanova Olga A, Kopinke Daniel, Heldermon Coy D, Castellano Ronald K, Law Brian K
1Department of Pharmacology, University of Florida, Gainesville, FL USA.
2Department of Chemistry, University of Florida, Gainesville, FL USA.
Cell Death Discov. 2019 Dec 10;5:153. doi: 10.1038/s41420-019-0228-9. eCollection 2019.
Disulfide bond-disrupting agents (DDAs) are a new chemical class of agents recently shown to have activity against breast tumors in animal models. Blockade of tumor growth is associated with downregulation of EGFR, HER2, and HER3 and reduced Akt phosphorylation, as well as the induction of endoplasmic reticulum stress. However, it is not known how DDAs trigger cancer cell death without affecting nontransformed cells. As demonstrated here, DDAs are the first compounds identified that upregulate the TRAIL receptor DR5 through transcriptional and post-transcriptional mechanisms to activate the extrinsic cell death pathway. At the protein level, DDAs alter DR5 disulfide bonding to increase steady-state DR5 levels and oligomerization, leading to downstream caspase 8 and 3 activation. DDAs and TRAIL synergize to kill cancer cells and are cytotoxic to HER2+ cancer cells with acquired resistance to the EGFR/HER2 tyrosine kinase inhibitor Lapatinib. Investigation of the mechanisms responsible for DDA selectivity for cancer cells reveals that DDA-induced upregulation of DR5 is enhanced in the context of EGFR overexpression. DDA-induced cytotoxicity is strongly amplified by MYC overexpression. This is consistent with the known potentiation of TRAIL-mediated cell death by MYC. Together, the results demonstrate selective DDA lethality against oncogene-transformed cells, DDA-mediated DR5 upregulation, and protein stabilization, and that DDAs have activity against drug-resistant cancer cells. Our results indicate that DDAs are unique in causing DR5 accumulation and oligomerization and inducing downstream caspase activation and cancer cell death through mechanisms involving altered DR5 disulfide bonding. DDAs thus represent a new therapeutic approach to cancer therapy.
二硫键破坏剂（DDA）是一类新型化学试剂，最近在动物模型中显示出对乳腺肿瘤具有活性。肿瘤生长的阻断与表皮生长因子受体（EGFR）、人表皮生长因子受体2（HER2）和人表皮生长因子受体3（HER3）的下调以及Akt磷酸化的降低有关，同时还与内质网应激的诱导有关。然而，目前尚不清楚DDA如何在不影响未转化细胞的情况下触发癌细胞死亡。如本文所示，DDA是首个被鉴定出的通过转录和转录后机制上调肿瘤坏死因子相关凋亡诱导配体（TRAIL）受体DR5以激活外源性细胞死亡途径的化合物。在蛋白质水平上，DDA改变DR5的二硫键结合，以增加稳态DR5水平和寡聚化，导致下游半胱天冬酶8和3的激活。DDA与TRAIL协同作用杀死癌细胞，并且对获得性抗EGFR/HER2酪氨酸激酶抑制剂拉帕替尼的HER2+癌细胞具有细胞毒性。对DDA对癌细胞选择性的作用机制进行研究发现，在EGFR过表达的情况下，DDA诱导的DR5上调会增强。MYC过表达会强烈放大DDA诱导的细胞毒性。这与已知的MYC对TRAIL介导的细胞死亡的增强作用一致。总之，这些结果证明了DDA对癌基因转化细胞具有选择性致死性、DDA介导的DR5上调和蛋白质稳定作用，并且DDA对耐药癌细胞具有活性。我们的结果表明，DDA在通过涉及改变DR5二硫键结合的机制导致DR5积累和寡聚化以及诱导下游半胱天冬酶激活和癌细胞死亡方面具有独特性。因此，DDA代表了一种新的癌症治疗方法。
