Research of novel treatment for childhood leukemia by disrupting the chimeric gene function using RNAi

染色体易位是导致儿童白血病和其他恶性疾病的基因组突变之一。由于染色体易位产生的嵌合mRNA促进了肿瘤的发生，利用RNAi干扰嵌合mRNA的功能被认为是治疗儿童白血病和恶性疾病的可能途径。然而，在某些情况下，易位断裂点的基因组结构还不清楚，这阻碍了利用RNAi进行新的治疗。为了建立这一新的治疗策略，本研究分析了由染色体易位产生的嵌合mRNA的分子结构，分析了带有t(15；17)(q13；q11)的急性髓细胞白血病(AML)细胞和带有t(2；2)(q21；q35)的滑膜肉瘤细胞的易位断裂点。建立了AML细胞的cDNA文库，筛选出含有易位断裂点的噬菌体。在滑膜肉瘤细胞中，由于横纹肌肉瘤常见的断裂点PAX3基因位于断裂点的一个位置，因此采用3‘-RACE(快速扩增cDNAEnd)的方法对其进行了分析。含有嵌合mRNA的候选产物已经被扩增，这些结果促进了利用RNAi破坏嵌合mRNA的新的治疗策略。将分析RNAi对这些嵌合mRNA的破坏作用。

Chromosome translocations are one of the genomic mutations which are responsible for childhood leukemia and other malignant disorders. Because chromosome translocation generates chimeric mRNA which promote the carcinogenesis, the disruption of chimeric mRNA function using RNAi is thought to be possible therapeutic approach for childhood leukemia and malignant disorders. However, genomic structure of translocation breakpoint have not been clarified in some cases, which hampers the development of novel therapy using RNAi. In this Research, to establish this new therapeutic strategy, the molecular structure of chimeric mRNA generated by chromosomal translocation was analyzed.We analyzed the translocation breakpoint of acute myelocytic leukemia (AML) cells with t(15;17)(q13;q11), and synovial sarcoma cells with t(2;2)(q21;q35). A cDNA library derived from AML cells were established and bacteriophages containing translocation breakpoint have been selected. In the case of synovial sarcoma cells, because PAX3 gene which is common breakpoint of rhabdomyosarcoma is located on the one site of breakpoints, counterpart have been analyzed using 3'-RACE (rapid amplification of cDNA end) method. Candiate product containing chimeric mRNA have been amplified.These results promote the novel therapeutic strategy disrupting chimeric mRNA using RNAi. The effect of RNAi which disrupt these chimeric mRNA will be analyzed.