PDF(Pubmed)
Abstract：
Osteosarcoma (OS) is the most common primary pediatric bone malignancy. One promising new therapeutic target is SKP2, encoding a substrate recognition factor of the SCF E3 ubiquitin ligase responsible for ubiquitination and proteasome degradation of substrate p27, thus driving cellular proliferation. We have shown previously that knockout of Skp2 in an immunocompetent transgenic mouse model of OS improved survival, drove apoptosis, and induced tumor inflammation. Here, we applied single-cell RNA-sequencing (scRNA-seq) to study primary OS tumors derived from Osx-Cre driven conditional knockout of Rb1 and Trp53. We showed that murine OS models recapitulate the tumor heterogeneity and microenvironment complexity observed in patient tumors. We further compared this model with OS models with functional disruption of Skp2: one with Skp2 knockout and the other with the Skp2-p27 interaction disrupted (resulting in p27 overexpression). We found reduction of T cell exhaustion and upregulation of interferon activation, along with evidence of replicative and endoplasmic reticulum-related stress in the Skp2 disruption models, and showed that interferon induction was correlated with improved survival in OS patients. Additionally, our scRNA-seq analysis uncovered decreased activities of metastasis-related gene signatures in the Skp2-disrupted OS, which we validated by observation of a strong reduction in lung metastasis in the Skp2 knockout mice. Finally, we report several potential mechanisms of escape from targeting Skp2 in OS, including upregulation of Myc targets, DNA copy number amplification and overexpression of alternative E3 ligase genes, and potential alternative lineage activation. These mechanistic insights into OS tumor biology and Skp2 function suggest novel targets for new, synergistic therapies, while the data and our comprehensive analysis may serve as a public resource for further big data-driven OS research.
摘要：
骨肉瘤（OS）是最常见的儿童原发性骨恶性肿瘤。一个有希望的新治疗靶点是SKP2，编码SCFE3泛素连接酶的底物识别因子，负责底物p27的泛素化和蛋白酶体降解，从而驱动细胞增殖。我们之前已经证明，在OS的免疫活性转基因小鼠模型中敲除Skp2改善了存活率，驱使细胞凋亡，并诱导肿瘤炎症。这里,我们应用单细胞RNA测序(scRNA-seq)来研究源自Osx-Cre驱动的Rb1和Trp53条件性敲除的原发性OS肿瘤。我们表明，鼠OS模型概括了在患者肿瘤中观察到的肿瘤异质性和微环境复杂性。我们进一步比较了该模型与具有Skp2功能破坏的OS模型:一个具有Skp2敲除,另一个具有Skp2-p27相互作用破坏(导致p27过表达)。我们发现T细胞耗竭的减少和干扰素激活的上调，随着复制和内质网相关的应激在Skp2破坏模型的证据，并显示干扰素诱导与OS患者生存率改善相关。此外,我们的scRNA-seq分析揭示了Skp2破坏的OS中转移相关基因特征的活性降低，我们通过在Skp2基因敲除小鼠中观察到肺转移明显减少来验证。最后,我们报道了几种在OS中逃避靶向Skp2的潜在机制，包括Myc目标的上调，DNA拷贝数扩增和过表达替代性E3连接酶基因，和潜在的替代谱系激活。这些对OS肿瘤生物学和Skp2功能的机制见解为新的，协同疗法，而数据和我们的综合分析可以作为进一步的大数据驱动的操作系统研究的公共资源。
