Department of Pharmacology and Nutritional Sciences, Department of Molecular and Cellular Biochemistry, and Markey Cancer Center, College of Medicine, University of Kentucky, Lexington, KY, USA.
Department of Respiratory Medicine, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, People's Republic of China.
Cell Oncol (Dordr). 2020 Dec;43(6):1049-1066. doi: 10.1007/s13402-020-00537-1. Epub 2020 Oct 2.
Stemming from a myriad of genetic and epigenetic alterations, triple-negative breast cancer (TNBC) is tied to poor clinical outcomes and aspires for individualized therapies. Here we investigated the therapeutic potential of co-inhibiting integrin-dependent signaling pathway and BRD4, a transcriptional and epigenetic mediator, for TNBC.
Two independent patient cohorts were subjected to bioinformatic and IHC examination for clinical association of candidate cancer drivers. The efficacy and biological bases for co-targeting these drivers were interrogated using cancer cell lines, a protein kinase array, chemical inhibitors, RNAi/CRISPR/Cas9 approaches, and a 4 T1-Balb/c xenograft model.
We found that amplification of the chromosome 8q24 region occurred in nearly 20% of TNBC tumors, and that it coincided with co-upregulation or amplification of c-Myc and FAK, a key effector of integrin-dependent signaling. This co-upregulation at the mRNA or protein level correlated with a poor patient survival (p < 0.0109 or p < 0.0402, respectively). Furthermore, we found that 14 TNBC cell lines exhibited high vulnerabilities to the combination of JQ1 and VS-6063, potent pharmacological antagonists of the BRD4/c-Myc and integrin/FAK-dependent pathways, respectively. We also observed a cooperative inhibitory effect of JQ1 and VS-6063 on tumor growth and infiltration of Ly6G myeloid-derived suppressor cells in vivo. Finally, we found that JQ1 and VS-6063 cooperatively induced apoptotic cell death by altering XIAP, Bcl2/Bcl-xl and Bim levels, impairing c-Src/p130Cas-, PI3K/Akt- and RelA-associated signaling, and were linked to EMT-inducing transcription factor Snail- and Slug-dependent regulation.
Based on our results, we conclude that the BRD4/c-Myc- and integrin/FAK-dependent pathways act in concert to promote breast cancer cell survival and poor clinical outcomes. As such, they represent promising targets for a synthetic lethal-type of therapy against TNBC.
源于众多遗传和表观遗传改变，三阴性乳腺癌（TNBC）与不良临床结局相关，并需要个体化治疗。在此，我们研究了联合抑制整合素依赖性信号通路和 BRD4（一种转录和表观遗传介质）对 TNBC 的治疗潜力。
两个独立的患者队列接受了生物信息学和免疫组化检查，以研究候选癌症驱动因素的临床相关性。使用癌细胞系、蛋白激酶阵列、化学抑制剂、RNAi/CRISPR/Cas9 方法和 4T1-Balb/c 异种移植模型，研究了针对这些驱动因素的协同靶向治疗的疗效和生物学基础。
我们发现，染色体 8q24 区域的扩增发生在近 20%的 TNBC 肿瘤中，并且与 c-Myc 和 FAK 的共上调或扩增一致，FAK 是整合素依赖性信号的关键效应因子。这种在 mRNA 或蛋白水平上的共上调与患者生存不良相关（p<0.0109 或 p<0.0402，分别）。此外，我们发现 14 种 TNBC 细胞系对 JQ1 和 VS-6063 的组合具有高敏感性，JQ1 和 VS-6063 分别是 BRD4/c-Myc 和整合素/FAK 依赖性通路的强效药理学拮抗剂。我们还观察到 JQ1 和 VS-6063 在体内对肿瘤生长和 Ly6G 髓源抑制细胞浸润具有协同抑制作用。最后，我们发现 JQ1 和 VS-6063 通过改变 XIAP、Bcl2/Bcl-xl 和 Bim 水平、破坏 c-Src/p130Cas-、PI3K/Akt 和 RelA 相关信号以及与 EMT 诱导转录因子 Snail-和 Slug 依赖性调节相关，协同诱导细胞凋亡。
基于我们的结果，我们得出结论，BRD4/c-Myc-和整合素/FAK 依赖性通路协同作用促进乳腺癌细胞存活和不良临床结局。因此，它们代表针对 TNBC 的合成致死型治疗的有前途的靶点。
