a Segal Cancer Centre and Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Departments of Medicine and Oncology , McGill University , Montreal , QC , Canada.
Autophagy. 2019 Aug;15(8):1376-1390. doi: 10.1080/15548627.2019.1582951. Epub 2019 Mar 1.
Patients with triple-negative breast cancer (TNBC) often have a poor prognosis largely due to lack of effective targeted therapy. Using a library of seleno-purines coupled to a high-throughput biochemical enzymatic assays we identified a potent pharmacological enhancer of autophagy (referred herein as SLLN-15) that selectively activated cytostatic macroautophagy/autophagy in TNBC preclinical models. SLLN-15 induced a dose-dependent anti-proliferative activity in the TNBC cell lines MDA-MB-231 and BT-20 via induction of autophagy and autophagic flux. This induction was associated with a selective inhibition of AKT-MTOR signaling. Conversely, rapamycin, a known autophagy inducer and MTOR inhibitor, was unable to duplicate SLLN-15's effect on TNBC cells. Inhibition of autophagy by siRNA-mediated targeting of the autophagy regulators, and or using 3-methyladenine (3-MA), significantly protected against SLLN-15-induced inhibition of cell viability, further supporting that SLLN-15-induced inhibition of cancer cell proliferation was autophagy-dependent. SLLN-15-induced autophagy in TNBC cells was also associated with decreased AURKA expression, decreased AKT phosphorylation and subsequent blockage of the AKT-MTOR pathway. In vivo, oral SLLN-15 revealed a potent anticancer and anti-metastatic activity in mice bearing TNBC. Altogether, this study describes a novel regulator of mammalian autophagy, with potential utility as an experimental therapeutic for TNBCs. 3-MA: 3-methyladenine; ATG5: autophagy related 5; ATG7: autophagy related 7; AURKA: aurora kinase A; AURKB: aurora kinase B; BECN1: beclin 1; CQ: chloroquine; DMSO: dimethyl sulfoxide; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; ERBB2: erb-b2 receptor tyrosine kinase 2; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; PARP1: poly(ADP-ribose) polymerase 1; PI: propidium iodide; SQSTM1/p62: sequestosome 1; TNBC: triple-negative breast cancer.
患有三阴性乳腺癌（TNBC）的患者预后通常较差，主要是因为缺乏有效的靶向治疗。我们使用与高通量生化酶测定法偶联的硒嘌呤文库，鉴定出一种有效的自噬药理学增强剂（在此称为 SLLN-15），它可选择性地激活 TNBC 临床前模型中的细胞生长停滞性巨自噬/自噬。SLLN-15 通过诱导自噬和自噬流，在 TNBC 细胞系 MDA-MB-231 和 BT-20 中引起剂量依赖性的抗增殖活性。这种诱导与 AKT-MTOR 信号的选择性抑制有关。相反，雷帕霉素，一种已知的自噬诱导剂和 MTOR 抑制剂，无法复制 SLLN-15 对 TNBC 细胞的作用。通过 siRNA 靶向自噬调节剂 和 或使用 3-甲基腺嘌呤（3-MA）抑制自噬，可显著防止 SLLN-15 诱导的细胞活力抑制，这进一步支持 SLLN-15 诱导的癌细胞增殖抑制是自噬依赖性的。SLLN-15 在 TNBC 细胞中诱导的自噬也与 AURKA 表达减少、AKT 磷酸化减少以及随后 AKT-MTOR 通路阻断有关。在体内，口服 SLLN-15 对患有 TNBC 的小鼠显示出强大的抗癌和抗转移活性。总之，本研究描述了一种哺乳动物自噬的新型调节剂，作为 TNBC 的实验治疗具有潜在用途。3-MA：3-甲基腺嘌呤；ATG5：自噬相关 5；ATG7：自噬相关 7；AURKA：极光激酶 A；AURKB：极光激酶 B；BECN1：自噬相关蛋白 5；CQ：氯喹；DMSO：二甲基亚砜；GAPDH：甘油醛-3-磷酸脱氢酶；GFP：绿色荧光蛋白；ERBB2：表皮生长因子受体 2；MAP1LC3B/LC3B：微管相关蛋白 1 轻链 3B；MTOR：雷帕霉素靶蛋白激酶；PARP1：多聚（ADP-核糖）聚合酶 1；PI：碘化丙啶；SQSTM1/p62：自噬相关蛋白 1；TNBC：三阴性乳腺癌。
