Kim Goo-Young, Lee Young Mok, Kwon Joon Hyun, Cho Jun-Ho, Pan Chi-Jiunn, Starost Matthew F, Mansfield Brian C, Chou Janice Y
Section on Cellular Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, United States.
Division of Veterinary Resources, National Institutes of Health, Bethesda, MD 20892, United States.
Mol Genet Metab. 2017 Mar;120(3):229-234. doi: 10.1016/j.ymgme.2017.01.003. Epub 2017 Jan 10.
Glycogen storage disease type Ia (GSD-Ia), characterized by impaired glucose homeostasis and chronic risk of hepatocellular adenoma (HCA) and carcinoma (HCC), is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC). We have previously shown that G6pc-/- mice receiving gene transfer mediated by rAAV-G6PC, a recombinant adeno-associated virus (rAAV) vector expressing G6Pase-α, and expressing 3-63% of normal hepatic G6Pase-α activity maintain glucose homeostasis and do not develop HCA/HCC. However, the threshold of hepatic G6Pase-α activity required to prevent tumor formation remained unknown. In this study, we constructed rAAV-co-G6PC, a rAAV vector expressing a codon-optimized (co) G6Pase-α and showed that rAAV-co-G6PC was more efficacious than rAAV-G6PC in directing hepatic G6Pase-α expression. Over an 88-week study, we showed that both rAAV-G6PC- and rAAV-co-G6PC-treated G6pc-/- mice expressing 3-33% of normal hepatic G6Pase-α activity (AAV mice) maintained glucose homeostasis, lacked HCA/HCC, and were protected against age-related obesity and insulin resistance. Of the eleven rAAV-G6PC/rAAV-co-G6PC-treated G6pc-/- mice harboring 0.9-2.4% of normal hepatic G6Pase-α activity (AAV-low mice), 3 expressing 0.9-1.3% of normal hepatic G6Pase-α activity developed HCA/HCC, while 8 did not (AAV-low-NT). Finally, we showed that the AAV-low-NT mice exhibited a phenotype indistinguishable from that of AAV mice expressing ≥3% of normal hepatic G6Pase-α activity. The results establish the threshold of hepatic G6Pase-α activity required to prevent HCA/HCC and show that GSD-Ia mice harboring <2% of normal hepatic G6Pase-α activity are at risk of tumor development.
Ia型糖原贮积病（GSD-Ia）的特征是葡萄糖稳态受损以及存在肝细胞腺瘤（HCA）和肝细胞癌（HCC）的慢性风险，它由葡萄糖-6-磷酸酶-α（G6Pase-α或G6PC）缺乏引起。我们之前已经表明，接受由rAAV-G6PC介导的基因转移的G6pc-/-小鼠，rAAV-G6PC是一种表达G6Pase-α的重组腺相关病毒（rAAV）载体，其表达正常肝脏G6Pase-α活性的3%-63%，可维持葡萄糖稳态且不会发生HCA/HCC。然而，预防肿瘤形成所需的肝脏G6Pase-α活性阈值仍然未知。在本研究中，我们构建了rAAV-co-G6PC，一种表达密码子优化（co）的G6Pase-α的rAAV载体，并表明rAAV-co-G6PC在指导肝脏G6Pase-α表达方面比rAAV-G6PC更有效。在一项为期88周的研究中，我们表明，表达正常肝脏G6Pase-α活性3%-33%的经rAAV-G6PC和rAAV-co-G6PC处理的G6pc-/-小鼠（AAV小鼠）维持了葡萄糖稳态，没有HCA/HCC，并且对年龄相关的肥胖和胰岛素抵抗具有保护作用。在11只肝脏G6Pase-α活性为正常水平0.9%-2.4%的经rAAV-G6PC/rAAV-co-G6PC处理的G6pc-/-小鼠（AAV-low小鼠）中，3只肝脏G6Pase-α活性为正常水平0.9%-1.3%的小鼠发生了HCA/HCC，而8只没有（AAV-low-NT）。最后，我们表明，AAV-low-NT小鼠表现出与表达≥3%正常肝脏G6Pase-α活性的AAV小鼠无法区分的表型。这些结果确定了预防HCA/HCC所需的肝脏G6Pase-α活性阈值，并表明肝脏G6Pase-α活性低于正常水平2%的GSD-Ia小鼠有肿瘤发生的风险。
