背景:默克尔细胞癌(MCC)是一种侵袭性皮肤癌,比黑色素瘤致命三倍。2008年,发现80%的MCC病例是由一种新型多瘤病毒的基因组整合引起的,默克尔细胞多瘤病毒(MCPyV),及其小的和截短的大的肿瘤抗原的表达(ST和LT-t,分别)。MCPyV属于人类多瘤病毒家族;然而,它是唯一与癌症有明确关联的。
方法:为了研究各种多瘤病毒肿瘤抗原在细胞转化中的作用和机制,用pLENTIMCPyVLT-t转导大鼠2和293A细胞,MCPyVST,TSPyVST,HPyV7ST,或空pLENTI并通过多种转化测定进行评估,和亚细胞分裂。使用单因素方差分析检验来评估统计学显著性。
结果:软琼脂,扩散,倍增时间,葡萄糖摄取,和血清依赖性测定证实ST是MCPyV的主要转化蛋白。此外,发现MCPyVST是独特的转化,与其他非癌性人多瘤病毒的ST抗原一样,在进行类似评估时,丝裂体发育不全的脊髓相关多瘤病毒(TSPyV)和人多瘤病毒7(HPyV7)没有转化.转化和非转化肿瘤抗原之间的结构差异的鉴定揭示MCPyVST的独特转化结构域可能位于MCPyVST独特区域的结构上不同的环内。在所有已知的MCPyVST细胞相互作用器中,62%是完全或暂时的核,表明尽管没有经典的核定位信号,但MCPyVST仍位于细胞核。的确,亚细胞分馏证实,MCPyVST可以通过目前未知的,调节机制独立于其小尺寸,因为HPyV7和TSPyVST蛋白不能核易位。尽管发现核定位对MCPyVST的几种转化特性很重要,细胞质隔离的MCPyVST也具有一些特性,提示MCPyVST可能在各个亚细胞区室中执行不同的转化功能。
结论:一起,这些数据进一步阐明了MCPyVST和其他多瘤病毒ST蛋白之间的独特差异,这对于理解MCPyV是唯一已知的人类致癌多瘤病毒是必要的.
BACKGROUND: Merkel Cell Carcinoma (MCC) is an aggressive skin cancer that is three times deadlier than melanoma. In 2008, it was found that 80% of MCC cases are caused by the genomic integration of a novel polyomavirus, Merkel Cell Polyomavirus (MCPyV), and the expression of its small and truncated large tumor antigens (ST and LT-t, respectively). MCPyV belongs to a family of human polyomaviruses; however, it is the only one with a clear association to cancer.
METHODS: To investigate the role and mechanisms of various polyomavirus tumor antigens in cellular transformation, Rat-2 and 293A cells were transduced with pLENTI MCPyV LT-t, MCPyV ST, TSPyV ST, HPyV7 ST, or empty pLENTI and assessed through multiple transformation assays, and subcellular fractionations. One-way ANOVA tests were used to assess statistical significance.
RESULTS: Soft agar, proliferation, doubling time, glucose uptake, and serum dependence assays confirmed ST to be the dominant transforming protein of MCPyV. Furthermore, it was found that MCPyV ST is uniquely transforming, as the ST antigens of other non-oncogenic human polyomaviruses such as Trichodysplasia Spinulosa-Associated Polyomavirus (TSPyV) and Human Polyomavirus 7 (HPyV7) were not transforming when similarly assessed. Identification of structural dissimilarities between transforming and non-transforming tumor antigens revealed that the uniquely transforming domain(s) of MCPyV ST are likely located within the structurally dissimilar loops of the MCPyV ST unique region. Of all known MCPyV ST cellular interactors, 62% are exclusively or transiently nuclear, suggesting that MCPyV ST localizes to the nucleus despite the absence of a canonical nuclear localization signal. Indeed, subcellular fractionations confirmed that MCPyV ST could achieve nuclear localization through a currently unknown, regulated mechanism independent of its small size, as HPyV7 and TSPyV ST proteins were incapable of nuclear translocation. Although nuclear localization was found to be important for several transforming properties of MCPyV ST, some properties were also performed by a cytoplasmic sequestered MCPyV ST, suggesting that MCPyV ST may perform different transforming functions in individual subcellular compartments.
CONCLUSIONS: Together, these data further elucidate the unique differences between MCPyV ST and other polyomavirus ST proteins necessary to understand MCPyV as the only known human oncogenic polyomavirus.