Neggers Jasper Edgar, Vanstreels Els, Baloglu Erkan, Shacham Sharon, Landesman Yosef, Daelemans Dirk
Katholieke Universiteit Leuven, Department of Immunology and Microbiology, Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Leuven, Belgium.
Karyopharm Therapeutics, Newton, MA, USA.
Oncotarget. 2016 Oct 18;7(42):68842-68850. doi: 10.18632/oncotarget.11995.
Exportin-1 (CRM1/XPO1) is a crucial nuclear export protein that transports a wide variety of proteins from the nucleus to the cytoplasm. These cargo proteins include tumor suppressors and growth-regulatory factors and as such XPO1 is considered a potential anti-cancer target. From this perspective, inhibition of the XPO1-mediated nuclear export by selective inhibitor of nuclear export (SINE) compounds has shown broad-spectrum anti-cancer activity. Furthermore, the clinical candidate SINE, selinexor, is currently in multiple phase I/II/IIb trials for treatment of cancer. Resistance against selinexor has not yet been observed in the clinic, but in vitro selection of resistance did not reveal any mutations in the target protein, XPO1. However, introduction of a homozygous mutation at the drug's target site, the cysteine 528 residue inside the XPO1 cargo-binding pocket, by genetic engineering, confers resistance to selinexor. Here we investigated whether this resistance to selinexor is recessive or dominant. For this purpose we have engineered multiple leukemia cell lines containing heterozygous or homozygous C528S substitutions using CRISPR/Cas9-mediated genome editing. Our findings show that heterozygous mutation confers similar resistance against selinexor as homozygous substitution, demonstrating that SINE resistance can be obtained by a single and dominant mutation of the cysteine528 residue in XPO1.
输出蛋白1（CRM1/XPO1）是一种关键的核输出蛋白，可将多种蛋白质从细胞核转运至细胞质。这些货物蛋白包括肿瘤抑制因子和生长调节因子，因此XPO1被视为一个潜在的抗癌靶点。从这个角度来看，核输出选择性抑制剂（SINE）化合物对XPO1介导的核输出的抑制作用已显示出广谱抗癌活性。此外，临床候选药物SINE，即塞利尼索，目前正处于多项治疗癌症的I/II/IIb期试验中。在临床上尚未观察到对塞利尼索的耐药性，但在体外筛选耐药性时并未发现靶蛋白XPO1有任何突变。然而，通过基因工程在药物靶点位点，即XPO1货物结合口袋内的半胱氨酸528残基处引入纯合突变，可使细胞对塞利尼索产生耐药性。在此，我们研究了这种对塞利尼索的耐药性是隐性还是显性的。为此，我们使用CRISPR/Cas9介导的基因组编辑技术构建了多个含有杂合或纯合C528S替代的白血病细胞系。我们的研究结果表明，杂合突变赋予细胞对塞利尼索的耐药性与纯合替代相似，这表明通过XPO1中半胱氨酸528残基的单个显性突变即可获得对SINE的耐药性。
