Department of Biomedical Sciences, University of Minnesota Medical School Duluth, MN 55812, USA.
Department of Biomedical Sciences, University of Minnesota Medical School Duluth, MN 55812, USA.
Toxicol Appl Pharmacol. 2022 May 1;442:116003. doi: 10.1016/j.taap.2022.116003. Epub 2022 Mar 28.
Molnupiravir is an orally active nucleoside analog antiviral drug that recently was approved by the U.S. FDA for emergency treatment of adult patients infected with the SARS-CoV-2 (COVID-19) virus and at risk for severe progression. The active form of the drug, N-hydroxycytidine (NHC) triphosphate competes for incorporation by RNA-dependent RNA-polymerase (RdRp) into the replicating viral genome resulting in mutations and arrest of the replicating virus. Historically, some nucleoside analog antiviral drugs have been found to lack specificity for the virus and also inhibit replication and/or expression of the mitochondrial genome. The objective of the present study was to test whether molnupiravir and/or NHC also target mitochondrial DNA polymerase gamma (PolG) or RNA polymerase (POLRMT) activity to inhibit the replication and/or expression of the mitochondrial genome leading to impaired mitochondrial function. Human-derived HepG2 cells were exposed for 48 h in culture to increasing concentrations of either molnupiravir or NHC after which cytotoxicity, mtDNA copy number and mitochondrial gene expression were determined. The phenotypic endpoint, mitochondrial respiration, was measured with the Seahorse® XF96 Extracellular Flux Analyzer. Both molnupiravir and NHC were cytotoxic at concentrations of ≥10 μM. However, at non-cytotoxic concentrations, neither significantly altered mitochondrial gene dose or transcription, or mitochondrial respiration. From this we conclude that mitochondrial toxicity is not a primary off target in the mechanism of cytotoxicity for either molnupiravir or its active metabolite NHC in the HepG2 cell line.
莫努匹韦是一种口服活性核苷类似物抗病毒药物，最近被美国食品药品监督管理局（FDA）批准用于治疗感染 SARS-CoV-2（COVID-19）病毒且有重症进展风险的成年患者。该药物的活性形式 N-羟基胞苷三磷酸（NHC）三磷酸与 RNA 依赖性 RNA 聚合酶（RdRp）竞争掺入复制中的病毒基因组，导致突变和复制病毒的停滞。历史上，一些核苷类似物抗病毒药物被发现缺乏对病毒的特异性，并且还抑制线粒体基因组的复制和/或表达。本研究的目的是测试莫努匹韦和/或 NHC 是否也靶向线粒体 DNA 聚合酶γ（PolG）或 RNA 聚合酶（POLRMT）活性，以抑制线粒体基因组的复制和/或表达，导致线粒体功能受损。在培养中，用人源性 HepG2 细胞暴露于递增浓度的莫努匹韦或 NHC 48 小时，然后测定细胞毒性、线粒体 DNA 拷贝数和线粒体基因表达。用 Seahorse® XF96 细胞外通量分析仪测量表型终点，即线粒体呼吸。莫努匹韦和 NHC 的浓度≥10μM 时均具有细胞毒性。然而，在非细胞毒性浓度下，它们均未显著改变线粒体基因剂量或转录，或线粒体呼吸。由此我们得出结论，线粒体毒性不是莫努匹韦或其活性代谢物 NHC 在 HepG2 细胞系中细胞毒性机制的主要非靶标。
