Department of Infectious Diseases, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
Department of Bioengineering and Therapeutic Sciences and Liver Center, UCSF, San Francisco, California, USA.
J Clin Invest. 2024 Sep 26;134(22):e174415. doi: 10.1172/JCI174415.
Activated mTORC2/AKT signaling plays a role in hepatocellular carcinoma (HCC). Research has shown that TSC/mTORC1 and FOXO1 are distinct downstream effectors of AKT signaling in liver regeneration and metabolism. However, the mechanisms by which these pathways mediate mTORC2/AKT activation in HCC are not yet fully understood. Amplification and activation of c-MYC are key molecular events in HCC. In this study, we explored the roles of tuberous sclerosis complex/mTORC1 (TSC/mTORC1) and FOXO1 as downstream effectors of mTORC2/AKT1 in c-MYC-induced hepatocarcinogenesis. Using various genetic approaches in mice, we found that manipulating the FOXO pathway had a minimal effect on c-MYC-induced HCC. In contrast, loss of mTORC2 inhibited c-MYC-induced HCC, an effect that was completely reversed by ablation of TSC2, which activated mTORC1. Additionally, we discovered that p70/RPS6 and 4EBP1/eIF4E acted downstream of mTORC1, regulating distinct molecular pathways. Notably, the 4EBP1/eIF4E cascade is crucial for cell proliferation and glycolysis in c-MYC-induced HCC. We also identified centromere protein M (CENPM) as a downstream target of the TSC2/mTORC1 pathway in c-MYC-driven hepatocarcinogenesis, and its ablation entirely inhibited c-MYC-dependent HCC formation. Our findings demonstrate that the TSC/mTORC1/CENPM pathway, rather than the FOXO cascade, is the primary signaling pathway regulating c-MYC-driven hepatocarcinogenesis. Targeting CENPM holds therapeutic potential for treating c-MYC-driven HCC.
mTORC2/AKT 信号的激活在肝细胞癌(HCC)中发挥作用。研究表明,TSC/mTORC1 和 FOXO1 是 AKT 信号在肝再生和代谢中的不同下游效应物。然而,这些途径介导 HCC 中 mTORC2/AKT 激活的机制尚未完全阐明。c-MYC 的扩增和激活是 HCC 的关键分子事件。在这项研究中,我们探讨了结节性硬化复合物/mTORC1(TSC/mTORC1)和 FOXO1 作为 mTORC2/AKT1 的下游效应物在 c-MYC 诱导的肝癌发生中的作用。我们使用小鼠中的各种遗传方法发现,操纵 FOXO 途径对 c-MYC 诱导的 HCC 影响很小。相比之下,mTORC2 的缺失抑制了 c-MYC 诱导的 HCC,而 TSC2 的缺失完全逆转了这种作用,TSC2 激活了 mTORC1。此外,我们发现 p70/RPS6 和 4EBP1/eIF4E 作为 mTORC1 的下游分子,调节不同的分子途径。值得注意的是,4EBP1/eIF4E 级联在 c-MYC 诱导的 HCC 中对细胞增殖和糖酵解至关重要。我们还确定着丝粒蛋白 M(CENPM)是 c-MYC 驱动的肝癌发生中 TSC2/mTORC1 途径的下游靶标,其缺失完全抑制了 c-MYC 依赖性 HCC 形成。我们的研究结果表明,TSC/mTORC1/CENPM 途径而不是 FOXO 级联是调节 c-MYC 驱动的肝癌发生的主要信号通路。靶向 CENPM 为治疗 c-MYC 驱动的 HCC 提供了治疗潜力。