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ユ−イング肉種t(11;22)転座切断点領域の構造解析：阿部周一¹, 小畑慶子², 平賀博明^３, 野島孝之^４, 吉田廸弘¹（^１北大・理・動染研, ^２愛媛大・医・公衛, ^３国立札幌病院・整形, ^４金沢医大・病理）

Molecular characterization of the genomic breakpoint region of t(11;22) translocation in Ewing's sarcoma: Syuiti ABE¹, Keiko OBATA², Hiroaki HIRAGA^３, Takayuki NOJIMA^４, and Michihiro C. Yoshida¹ (¹Chromosome Res. Unit, Fac. Sci., Hokkaido Univ., ²Lab. Hygien., Ehime Univ. Sch. Med., ³Div. Orthoped. Surg., Sapporo Natl. Hosp., and 4Dept. Pathol., Kanazawa Univ. Sch. Med.)

In order to characterize the breakpoint region of t(11;22)(q24;q12) translocation, which joins the EWS gene located on chromosome 22 with the FLI1 gene located on chromosome 11, PCR-based sequence analysis was performed on tumor genomic DNA from 8 cases of Ewing's sarcoma showing 4 types of EWS-FLI1 fusion genes resulted from junction between EWS intron 7 or 10 with FLI1 intron 4, 7, or 8. The breakpoints in EWS intron 7 and 10 were found to occur within approximately 300bp. Although none of the previously reported DNA sequences were identified in the vicinity of the junctions, most of the breakpoints occurred at or near the sequences highly homologous to Alu sequence or eukaryotic topoisomerase II cleavage site. In addition, 6 to 10bp sequences including an AGAAAARDRR and palindromic oligomers flanked all of the breakpoints of both genes. Deletion and duplication around the junctions in both genes were observed in some cases. These findings indicate that t(11;22) is asymmetric at the molecular level, and that the characteristic sequences flanking the breakpoints may have a functional significance in the genesis of the t(11;22).