矢部 寛樹

Ewing sarcoma is a malignant bone and soft tissue tumor of children and young adults, which is known to be highly aggressive and invasive. It expresses specific chimeric genes (EWS-FLI-1, EWS-ERG, EWS-ETV1. and EWS-E1AF), the 3' portions of which are all members of the ETS family. ETS-related proteins, such as FLI-1. ERG, and E1AF, transactivate the promoters of matrix metalloproteinase (MMP) genes. which play important roles in the processes of invasion and metastasis. Therefore. we hypothesize that the Ewing sarcoma-specific chimeric genes also transactivate the MMP genes, contributing to the tumor's invasiveness and propensity for metastasis. To verify this hypothesis, we investigated the expression of MMPs in eight Ewing sarcoma cell lines. Surprisingly, MMP-1 and MMP-3 were not expressed at all in any of the cell lines. MMP-9 was expressed in four out of the eight cell lines, and MMP-2 and MT1-MMP in all of the cell lines. Ewing sarcoma-specific chimeric genes have been shown to transactivate the promoter of the MMP-1 gene by the reporter assay, and bind to the putative recognition sites in the MMP regulatory elements by the gel shift assay. However, an in vivo formaldehyde cross-linking study revealed that the chimeric protein did not bind to the predicted ETS recognition sites in the regulatory elements of the MMPs. These results indicate that the absence of the MMP expression in the tumor cells is at least in part due to the loss of accessibility of the ETS recognition sites in the regulatory elements of the MMP genes. Therefore, we should be careful before theorizing simply that a putative binding site is essential for the transcription of critical genes, since the binding of this fusion protein was found to be modulated in tumor cells in this study. (C) 2002 Elsevier Science (USA). All rights reserved.

Ewing's sarcoma, one of the most malignant tumors of children and young adults, expresses specific chimeric genes, e.g. EWS-FL1-1, EWS-ERG, EWS-ETV1 and EWS-FEV. In this paper, we extensively characterized a new fusion gene, EWS-E1AF by means of whole cDNA sequencing, RNA blot analysis, DNA blot analysis and chromosomal analysis, and showed it to be available for the diagnosis of Ewing's sarcoma and to participate in the oncogenesis of Ewing's sarcoma, Furthermore, we conducted a genetic analysis of Ewing family tumors in conjuction with immunohistochemical analysis and ultrastructural analysis. Our results demonstrate some limitations of both genetic analysis and histopathological analysis, and establish the relationship between neurogenic phenotypes and chimera genes.