Universität Zu Lübeck, Institut Für Physiologie, Working Group Hypoxia, Ratzeburger Allee 160, 23562, Lübeck, Germany.
Karyopharm Therapeutics, 85 Wells Ave, Newton, MA, 02459, USA.
J Cancer Res Clin Oncol. 2021 Jul;147(7):2025-2033. doi: 10.1007/s00432-021-03626-2. Epub 2021 Apr 15.
The nuclear pore complexes (NPCs) are built of about 30 different nucleoporins and act as key regulators of molecular traffic between the cytoplasm and the nucleus for sizeable proteins (> 40 kDa) which must enter the nucleus. Various nuclear transport receptors are involved in import and export processes of proteins through the nuclear pores. The most prominent nuclear export receptor is chromosome region maintenance 1 (CRM1), also known as exportin 1 (XPO1). One of its cargo proteins is the prolyl hydroxylase 2 (PHD2) which is involved in the initiation of the degradation of hypoxia-inducible factors (HIFs) under normoxia. HIFs are proteins that regulate the cellular adaptation under hypoxic conditions. They are involved in many aspects of cell viability and play an important role in the hypoxic microenvironment of cancer. In cancer, CRM1 is often overexpressed thus being a putative target for the development of new cancer therapies. The newly FDA-approved pharmaceutical Selinexor (KPT-330) selectively inhibits nuclear export via CRM1 and is currently tested in additional Phase-III clinical trials. In this study, we investigated the effect of CRM1 inhibition on the subcellular localization of HIF-1α and radiosensitivity.
Human hepatoma cells Hep3B and human osteosarcoma cells U2OS were treated with Selinexor. Intranuclear concentration of HIF-1α protein was measured using immunoblot analysis. Furthermore, cells were irradiated with 2-8 Gy after treatment with Selinexor compared to untreated controls.
Selinexor significantly reduced the intranuclear level of HIF-1α protein in human hepatoma cells Hep3B and human osteosarcoma cells U2OS. Moreover, we demonstrated by clonogenic survival assays that Selinexor leads to dose-dependent radiosensitization in Hep3B-hepatoma and U2OS-osteosarcoma cells.
Targeting the HIF pathway by Selinexor might be an attractive tool to overcome hypoxia-induced radioresistance.
核孔复合物（NPCs）由约 30 种不同的核孔蛋白组成，是调节细胞质和细胞核之间大分子物质（>40 kDa）运输的关键因子，这些物质必须进入细胞核。各种核转运受体参与蛋白质通过核孔的输入和输出过程。最突出的核输出受体是染色体区域维持 1 （CRM1），也称为输出蛋白 1（XPO1）。其货物蛋白之一是脯氨酰羟化酶 2（PHD2），它参与缺氧诱导因子（HIFs）在常氧下的降解起始。HIFs 是调节缺氧条件下细胞适应性的蛋白质。它们参与细胞活力的许多方面，并在癌症的缺氧微环境中发挥重要作用。在癌症中，CRM1 常过度表达，因此成为开发新癌症治疗方法的潜在靶点。最近获得 FDA 批准的药物 Selinexor（KPT-330）通过 CRM1 选择性抑制核输出，目前正在进行额外的 III 期临床试验。在这项研究中，我们研究了 CRM1 抑制对 HIF-1α 亚细胞定位和放射敏感性的影响。
用 Selinexor 处理人肝癌细胞 Hep3B 和人骨肉瘤细胞 U2OS。使用免疫印迹分析测量 HIF-1α 蛋白的核内浓度。此外，与未处理的对照相比，在用 Selinexor 处理后，用 2-8 Gy 对细胞进行照射。
Selinexor 显著降低了人肝癌细胞 Hep3B 和人骨肉瘤细胞 U2OS 中的 HIF-1α 蛋白核内水平。此外，我们通过集落形成生存实验证明，Selinexor 导致 Hep3B-肝癌和 U2OS-骨肉瘤细胞的剂量依赖性放射增敏。
通过 Selinexor 靶向 HIF 通路可能是克服缺氧诱导的放射抵抗的一种有吸引力的工具。
