Harvard Medical School Initiative for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215.
Program in Virology, Division of Medical Sciences, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2021 Nov 9;118(45). doi: 10.1073/pnas.2105428118.
Kaposi's sarcoma-associated herpesvirus (KSHV) causes the endothelial tumor KS, a leading cause of morbidity and mortality in sub-Saharan Africa. KSHV-encoded microRNAs (miRNAs) are known to play an important role in viral oncogenesis; however, the role of host miRNAs in KS tumorigenesis remains largely unknown. Here, high-throughput small-RNA sequencing of the cellular transcriptome in a KS xenograft model revealed miR-127-3p as one of the most significantly down-regulated miRNAs, which we validated in KS patient tissues. We show that restoration of miR-127-3p suppresses KSHV-driven cellular transformation and proliferation and induces G cell cycle arrest by directly targeting the oncogene SKP2. This miR-127-3p-induced G arrest is rescued by disrupting the miR-127-3p target site in SKP2 messenger RNA (mRNA) using gene editing. Mechanistically, miR-127-3p-mediated SKP2 repression elevates cyclin-dependent kinase (CDK) inhibitor p21 and down-regulates cyclin E, cyclin A, and CDK2, leading to activation of the RB protein tumor suppressor pathway and suppression of the transcriptional activities of E2F and Myc, key oncoprotein transcription factors crucial for KSHV tumorigenesis. Consequently, metabolomics analysis during miR-127-3p-induced cell cycle arrest revealed significant depletion of dNTP pools, consistent with RB-mediated repression of key dNTP biosynthesis enzymes. Furthermore, miR-127-3p reconstitution in a KS xenograft mouse model suppresses KSHV-positive tumor growth by targeting SKP2 in vivo. These findings identify a previously unrecognized tumor suppressor function for miR-127-3p in KS and demonstrate that the miR-127-3p/SKP2 axis is a viable therapeutic strategy for KS.
卡波西肉瘤相关疱疹病毒（KSHV）导致内皮肿瘤 KS，这是撒哈拉以南非洲发病率和死亡率的主要原因。KSHV 编码的 microRNAs（miRNAs）在病毒致癌作用中起着重要作用；然而，宿主 miRNAs 在 KS 肿瘤发生中的作用在很大程度上尚不清楚。在这里，在 KS 异种移植模型中的细胞转录组高通量小 RNA 测序显示 miR-127-3p 是下调最显著的 miRNAs 之一，我们在 KS 患者组织中验证了这一点。我们表明，miR-127-3p 的恢复通过直接靶向癌基因 SKP2 抑制 KSHV 驱动的细胞转化和增殖并诱导 G 细胞周期停滞。通过使用基因编辑破坏 SKP2 mRNA 中的 miR-127-3p 靶位点，可以挽救这种 miR-127-3p 诱导的 G 期停滞。从机制上讲，miR-127-3p 介导的 SKP2 抑制会升高细胞周期蛋白依赖性激酶（CDK）抑制剂 p21 并下调细胞周期蛋白 E、细胞周期蛋白 A 和 CDK2，从而激活 RB 蛋白肿瘤抑制途径并抑制 E2F 和 Myc 的转录活性，E2F 和 Myc 是关键的癌蛋白转录因子，对 KSHV 肿瘤发生至关重要。因此，miR-127-3p 诱导的细胞周期停滞期间的代谢组学分析显示 dNTP 池显著耗竭，与 RB 介导的关键 dNTP 生物合成酶抑制一致。此外，在 KS 异种移植小鼠模型中重建 miR-127-3p 通过在体内靶向 SKP2 抑制 KSHV 阳性肿瘤生长。这些发现确定了 miR-127-3p 在 KS 中的以前未被认识到的肿瘤抑制功能，并证明了 miR-127-3p/SKP2 轴是 KS 的可行治疗策略。
