Project 3: Skin hypoxia, MCPyV infection, and MCC tumorigenesis

项目摘要 默克尔细胞癌(MCC)是最具侵袭性的皮肤癌之一。默克尔细胞的克隆性整合 多瘤病毒(MCPyV)基因组进入宿主DNA已在约80%的MCC中观察到，并代表着一个关键 MCC发展的因果因素。由MCPyV基因组编码的LT和ST已被证明不支持 不仅是病毒复制，而且还有MCPyV诱导的肿瘤形成。免疫抑制是另一个重要风险。 与MCPyV相关的MCC的发展因素。MCC的死亡率接近50%。的发病率。 自2000年以来，MCC在美国的销量增长了95%。MCC极易发生转移。转移性 癌症更难治疗，而且往往是致命的。因此，有必要更好地理解 MCPyV和MCC的致癌机制研究进展 致命的皮肤癌。MCC肿瘤通常在人的真皮中发现，真皮维持低氧状态。 微环境。低氧支持肿瘤进展的部分原因是通过驱动代谢适应、血管生成 和转移，通过上调低氧调节的基因。重要的是，我们发现了大量的 低氧基因在MCC中被高度诱导，提示低氧皮肤微环境代表着 MCC进展和转移扩散的重要起点。其中一些基因，如碳水化合物 脱水酶9(CA9)和血管内皮生长因子A(VEGF-A)在促进肿瘤生长中起关键作用 和转移。然而，MCPyV感染细胞和MCC肿瘤细胞如何应对缺氧及其影响 MCPyV感染和MCC肿瘤发生过程中低氧调控基因表达的研究尚不清楚。 我们发现MCPyV癌基因LT与表观遗传阅读器BRD4相关，BRD4在功能上相互作用 利用低氧反应的关键调节因子HIF-1α来控制低氧基因的转录 和血管内皮生长因子-A。我们还发现MCPyV ST可以诱导低氧基因的表达。基于这些发现， 我们假设MCPyV LT和ST与其东道主合作伙伴之间的协作交互，例如 BRD4和HIF-1α共同调节MCPyV感染和MCC来源的细胞中缺氧基因的表达 促进病毒感染和MCC肿瘤的发生。在这个项目中，我们建议确定MCPyV如何相互作用 与宿主细胞在低氧皮肤环境中(目标1)，表征LT-BRD4-HIF-1α的影响 相互作用对皮肤细胞缺氧基因表达的影响(AIM 2)，并研究MCPyV癌基因的功能 在控制MCC缺氧重编程及其对MCC肿瘤发生的影响方面(目标3)。这些结果将填补 我们对MCPyV感染的细胞和相关的MCC的缺氧反应机制的理解上的差距。 我们的研究可能为支持低氧介导的代谢的病毒和细胞因子提供新的见解 MCPyV感染和MCC致癌过程中的重新编程，揭示了新的策略 改进对MCPyV诱发癌症的治疗干预。

Project Abstract Merkel cell carcinoma (MCC) is one of the most aggressive skin cancers. Clonal integration of Merkel cell polyomavirus (MCPyV) genome into the host DNA has been observed in ~80% of MCCs, and represents a key causal factor for MCC development. LT and sT encoded by MCPyV genome have been shown to support not only viral replication but also MCPyV-induced tumorigenesis. Immune suppression is another important risk factor for the development of MCPyV-associated MCC. MCC has a nearly 50% mortality rate. The incidence of MCC has increased by >95% in the US since 2000. MCC is highly prone to metastasis. The metastatic cancers are more difficult to treat and can often be fatal. Thus, there is a need to better understand the oncogenic mechanisms of MCPyV and MCC in order to develop new strategies to prevent and treat this highly lethal skin cancer. MCC tumors are usually detected in the human dermis, which maintain a hypoxic microenvironment. Hypoxia supports tumor progression partly by driving metabolic adaptation, angiogenesis and metastasis, through upregulation of hypoxia-regulated genes. Importantly, we found that a large number of hypoxia genes are highly induced in MCC, suggesting that the hypoxic skin microenvironment represents an important starting point for MCC progression and metastatic spread. Some of these genes such as carbonic anhydrase 9 (CA9) and vascular endothelial growth factor A (VEGF-A) are critical for promoting tumor growth and metastasis. However, how MCPyV infected cells and MCC tumor cells respond to hypoxia and the impact of hypoxia-regulated gene expression on MCPyV infection and MCC tumorigenesis remain largely unknown. We showed that MCPyV oncogene LT is associated with epigenetic reader BRD4, which functionally interacts with HIF-1α, a key regulator of hypoxic responses, to control the transcription of hypoxic genes such as CA9 and VEGF-A. We also found that MCPyV sT can induce hypoxic gene expression. Building on these findings, we hypothesize that collaborative interactions between MCPyV LT and sT with their host partners, such as BRD4 and HIF-1α, collectively regulate hypoxia gene expression in MCPyV-infected and MCC origin cells to promote viral infection and MCC tumorigenesis. In this project, we propose to determine how MCPyV interacts with the host cells in the hypoxic skin environment (Aim 1), characterize the impact of LT-BRD4-HIF-1α interaction on hypoxic gene expression in skin cells (Aim 2), and investigate the function of MCPyV oncogenes in controlling MCC hypoxic reprograming and the impact on MCC tumorigenesis (Aim 3). These results will fill the gap in our understanding of hypoxic response mechanism in MCPyV-infected cells and associated MCC. Our study may provide new insights into viral and cellular factors that support hypoxia-mediated metabolic reprogramming during MCPyV infection and MCC oncogenic development, revealing new strategies to improve therapeutic intervention of MCPyV-induced cancers.