Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, and University of Tübingen, Tübingen, Germany (O.B., M.S.); Fraunhofer Institute for Molecular Biology and Applied Ecology IME, ScreeningPort, Hamburg, Germany (T.K., O.K., B.W.); Biobank of the Department of General, Visceral, and Transplantion Surgery, University Hospital, Ludwig-Maximilians University, Munich, Munich, Germany (S.M.L.L., T.S.S.); Departments of Clinical Pharmacology, and Pharmacy and Biochemistry, University of Tübingen, Tübingen, Germany (M.S.); and Department of Chemistry, Institute for Biochemistry and Molecular Biology, Universität Hamburg, Hamburg, Germany (B.W.)
Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, and University of Tübingen, Tübingen, Germany (O.B., M.S.); Fraunhofer Institute for Molecular Biology and Applied Ecology IME, ScreeningPort, Hamburg, Germany (T.K., O.K., B.W.); Biobank of the Department of General, Visceral, and Transplantion Surgery, University Hospital, Ludwig-Maximilians University, Munich, Munich, Germany (S.M.L.L., T.S.S.); Departments of Clinical Pharmacology, and Pharmacy and Biochemistry, University of Tübingen, Tübingen, Germany (M.S.); and Department of Chemistry, Institute for Biochemistry and Molecular Biology, Universität Hamburg, Hamburg, Germany (B.W.).
Mol Pharmacol. 2021 Mar;99(3):184-196. doi: 10.1124/molpharm.120.000116. Epub 2021 Jan 22.
The HIV protease inhibitor nelfinavir is currently being analyzed for repurposing as an anticancer drug for many different cancers because it exerts manifold off-target protein interactions, finally resulting in cancer cell death. Xenosensing pregnane X receptor (PXR), which also participates in the control of cancer cell proliferation and apoptosis, was previously shown to be activated by nelfinavir; however, the exact molecular mechanism is still unknown. The present study addresses the effects of nelfinavir and its major and pharmacologically active metabolite nelfinavir hydroxy--butylamide (M8) on PXR to elucidate the underlying molecular mechanism. Molecular docking suggested direct binding to the PXR ligand-binding domain, which was confirmed experimentally by limited proteolytic digestion and competitive ligand-binding assays. Concentration-response analyses using cellular transactivation assays identified nelfinavir and M8 as partial agonists with EC values of 0.9 and 7.3 µM and competitive antagonists of rifampin-dependent induction with IC values of 7.5 and 25.3 µM, respectively. Antagonism exclusively resulted from binding into the PXR ligand-binding pocket. Impaired coactivator recruitment by nelfinavir as compared with the full agonist rifampin proved to be the underlying mechanism of both effects on PXR. Physiologic relevance of nelfinavir-dependent modulation of PXR activity was investigated in respectively treated primary human hepatocytes, which showed differential induction of PXR target genes and antagonism of rifampin-induced ABCB1 and CYP3A4 gene expression. In conclusion, we elucidate here the molecular mechanism of nelfinavir interaction with PXR. It is hypothesized that modulation of PXR activity may impact the anticancer effects of nelfinavir. SIGNIFICANCE STATEMENT: Nelfinavir, which is being investigated for repurposing as an anticancer medication, is shown here to directly bind to human pregnane X receptor (PXR) and thereby act as a partial agonist and competitive antagonist. Its major metabolite nelfinavir hydroxy--butylamide exerts the same effects, which are based on impaired coactivator recruitment. Nelfinavir anticancer activity may involve modulation of PXR, which itself is discussed as a therapeutic target in cancer therapy and for the reversal of chemoresistance.
HIV 蛋白酶抑制剂奈非那韦目前正在被分析用于重新用于治疗许多不同癌症的药物，因为它发挥多种非靶蛋白相互作用，最终导致癌细胞死亡。Xenosensing 孕烷 X 受体 (PXR) 也参与控制癌细胞增殖和凋亡，先前已显示被奈非那韦激活;然而，确切的分子机制仍不清楚。本研究旨在研究奈非那韦及其主要和药理学上有活性的代谢物奈非那韦羟基--丁酰胺 (M8) 对 PXR 的影响，以阐明潜在的分子机制。分子对接表明直接结合到 PXR 配体结合域，这通过有限的蛋白水解消化和竞争性配体结合测定实验得到证实。使用细胞转激活测定的浓度-反应分析鉴定奈非那韦和 M8 为 EC 值为 0.9 和 7.3 μM 的部分激动剂，以及 rifampin 依赖性诱导的竞争性拮抗剂，IC 值分别为 7.5 和 25.3 μM。拮抗剂仅因结合到 PXR 配体结合口袋中而产生。与完全激动剂 rifampin 相比，奈非那韦对共激活因子募集的抑制作用被证明是这两种对 PXR 作用的潜在机制。在分别用奈非那韦处理的原代人肝细胞中研究了奈非那韦依赖性 PXR 活性调节的生理相关性，结果显示 PXR 靶基因的差异诱导和 rifampin 诱导的 ABCB1 和 CYP3A4 基因表达的拮抗作用。总之，我们在这里阐明了奈非那韦与 PXR 相互作用的分子机制。据推测，PXR 活性的调节可能会影响奈非那韦的抗癌作用。意义声明：正在被重新用于研究作为抗癌药物的奈非那韦被证明可以直接与人类孕烷 X 受体 (PXR) 结合，从而作为部分激动剂和竞争性拮抗剂发挥作用。其主要代谢物奈非那韦羟基--丁酰胺也具有相同的作用，这是基于共激活因子募集的受损。奈非那韦的抗癌活性可能涉及 PXR 的调节，PXR 本身被认为是癌症治疗和逆转化疗耐药性的治疗靶点。
