Investigation of viral genome relating to human brain tumor using DNA amplification method

小脑髓母细胞瘤的起源和儿童期这种恶性肿瘤的发生机制仍然未知，主要是因为缺乏合适的动物模型。我们成功地用人乳多空病毒JC诱导仓鼠小脑髓母细胞瘤。利用这种动物模型，我们研究了小脑髓母细胞瘤的起源、病毒组织嗜性的分子基础、假定的转化机制以及这种病毒与人脑肿瘤的可能关系。首先，通过原位杂交，”可以证明从外部颗粒层迁移到内部颗粒层的细胞含有JC病毒大T蛋白mRNA，并且内颗粒层中的转化细胞也含有这种mRNA。因此，新生儿外颗粒层的细胞可能是负责髓母细胞瘤的原始细胞。第二，为了阐明JC病毒嗜神经性的机制，我们进行了CAT试验， ...更多信息 JC病毒增强子在神经母细胞瘤细胞中有活性，但在Hela细胞和胶质瘤细胞中无活性。第三，在JC病毒转化的可能机制研究中，免疫沉淀法证实JC病毒大T蛋白可与两种抑癌基因产物--视网膜母细胞瘤蛋白和p53蛋白结合。因此，JC病毒大T蛋白与抗癌基因产物之间的结合似乎是JC病毒转化的重要步骤。最后，我们使用DNA扩增方法研究了儿童期人脑肿瘤是否含有JC病毒基因组。3例儿童脑肿瘤石蜡切片PCR产物均未检测到JC病毒T区锌指结构域，而金黄地鼠脑肿瘤为阳性。虽然我们仍在进行这项研究，从石蜡切片提取的DNA扩增似乎不是合适的方法来回答最后的问题。因此，使用包含调控区、RB结构域、p53结构域和ATP结构域的JC病毒探针检查更多新鲜脑肿瘤和细胞系的病例变得更加重要。少

Origin of cerebellar medulloblastoma, and mechanism of oncogenesis of this malignant tumor in childhood remain unknown, largely because of a lack of suitable animal models. We have successfully induced medulloblastoma in hamster cerebellum by inoculating a human papovavirus JC. Using this animal model, we examined the origin of medulloblastoma in the cerebellum, the molecular basis of viral tissue tropism, the putative mechanism of transformation, and the possible relation of this virus to human brain tumors.First, by in-situ hybridization" it could be demonstrated that the cells migrating from the external granular layer to the internal granular layer contained the JC virus large T protein mRNA, and that transformed cells in the internal granular layer also contained this mRNA. Thus, the cells in the neonatal external granular layer may be the original cells responsible for the medulloblastoma.Second, to clarify the mechanism of JC virus neurotropism, we carried out a CAT assay, and w … More ere able to demonstrate that JC virus enhancer became active in neuroblastoma cells, but was inactive in Hela cells and glio-ma cells. This showed that JC virus enhancer plays an important role in tissue tropism.Third, in the studies of possible mechanism of transformation by JC virus, immunoprecipitation methods demonstrated that JC virus large T protein could bind onto both anti-oncogene products, the retinoblastoma protein and the protein p53. Thus, the association between JC virus large T protein and anti-oncogene products seemed to be an essential step in transformation by JC virus.Finally, we investigated using DNA amplification methods whether human brain tumors in childhood contain JC virus genome. Zinc finger domain of JC virus T region was not detected in PCR products from paraffin sections of 3 human brain tumors of childhood, compared to positive hamster brain tumors. Although we are still in progress of this study, DNA amplification extracted from paraffin section seemed not to be suitable method to answer the final question. Thus, it becomes more important to examine more cases of fresh brain tumors and cell lines using JC virus probes encompassing regulatory region, RB domain, p53 domain, and ATP domain. Less