McFadden Karyn, Hafez Amy Y, Kishton Rigel, Messinger Joshua E, Nikitin Pavel A, Rathmell Jeffrey C, Luftig Micah A
Department of Molecular Genetics and Microbiology, Center for Virology, Duke University School of Medicine, Durham, NC 27710;
Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710;
Proc Natl Acad Sci U S A. 2016 Feb 9;113(6):E782-90. doi: 10.1073/pnas.1517141113. Epub 2016 Jan 22.
Epstein-Barr virus (EBV) is an oncogenic herpesvirus that has been causally linked to the development of B-cell and epithelial malignancies. Early after infection, EBV induces a transient period of hyperproliferation that is suppressed by the activation of the DNA damage response and a G1/S-phase growth arrest. This growth arrest prevents long-term outgrowth of the majority of infected cells. We developed a method to isolate and characterize infected cells that arrest after this early burst of proliferation and integrated gene expression and metabolic profiling to gain a better understanding of the pathways that attenuate immortalization. We found that the arrested cells have a reduced level of mitochondrial respiration and a decrease in the expression of genes involved in the TCA cycle and oxidative phosphorylation. Indeed, the growth arrest in early infected cells could be rescued by supplementing the TCA cycle. Arrested cells were characterized by an increase in the expression of p53 pathway gene targets, including sestrins leading to activation of AMPK, a reduction in mTOR signaling, and, consequently, elevated autophagy that was important for cell survival. Autophagy was also critical to maintain early hyperproliferation during metabolic stress. Finally, in assessing the metabolic changes from early infection to long-term outgrowth, we found concomitant increases in glucose import and surface glucose transporter 1 (GLUT1) levels, leading to elevated glycolysis, oxidative phosphorylation, and suppression of basal autophagy. Our study demonstrates that oncogene-induced senescence triggered by a combination of metabolic and genotoxic stress acts as an intrinsic barrier to EBV-mediated transformation.
爱泼斯坦-巴尔病毒（EBV）是一种致癌性疱疹病毒，与B细胞和上皮恶性肿瘤的发生存在因果关系。感染后早期，EBV会诱导一段短暂的细胞过度增殖期，随后该过程会被DNA损伤反应的激活和G1/S期生长停滞所抑制。这种生长停滞可防止大多数受感染细胞长期存活。我们开发了一种方法来分离和鉴定在早期增殖爆发后停滞的受感染细胞，并整合基因表达和代谢谱分析，以更好地了解减弱永生化的途径。我们发现，停滞的细胞线粒体呼吸水平降低，参与三羧酸循环（TCA循环）和氧化磷酸化的基因表达减少。事实上，通过补充TCA循环可以挽救早期受感染细胞的生长停滞。停滞的细胞特征在于p53通路基因靶点的表达增加，包括导致AMPK激活的 sestrins，mTOR信号传导减少，从而自噬增强，这对细胞存活很重要。自噬对于在代谢应激期间维持早期过度增殖也至关重要。最后，在评估从早期感染到长期存活期间的代谢变化时，我们发现葡萄糖摄取和表面葡萄糖转运蛋白1（GLUT1）水平同时增加，导致糖酵解、氧化磷酸化升高以及基础自噬受到抑制。我们的研究表明，由代谢和基因毒性应激共同引发的癌基因诱导的衰老，是EBV介导的细胞转化的内在障碍。
