Chan D, Wilson T J, Xu D, Cowdery H E, Sanij E, Hertzog P J, Kola I
Centre for Functional Genomics and Human Diseases, Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
Br J Cancer. 2003 Jan 13;88(1):137-45. doi: 10.1038/sj.bjc.6600669.
Ewing's sarcoma is a childhood bone tumour with poor prognosis, most commonly associated with a t(11;22)(q24;q12) reciprocal translocation that fuses the EWS and FLI-1 genes, resulting in the production of an aberrant chimeric transcription factor EWS/FLI-1. To elucidate the mechanisms by which EWS/FLI-1 mediates transformation in mouse models, we have generated a murine Ews/Fli-1 fusion protein. We demonstrate that this protein transforms fibroblast cells in vitro similar to human EWS/FLI-1 as demonstrated by serum and anchorage-independent growth, the formation of tumours in nude mice and elevation of the oncogenic marker c-myc. Furthermore, transformation of these cells was inhibited by a specific repressor, KRAB/FLI-1. The KRAB/FLI-1 repressor also suppressed the tumorigenic phenotype of a human Ewing's sarcoma cell line. These findings suggest that the transformed phenotype of Ewing's sarcoma cells can be reversed by using the sequence-specific FLI-1-DNA-binding domain to target a gene repressor domain. The inhibition of EWS/FLI-1 is the first demonstration of the KRAB domain suppressing the action of an ETS factor. This approach provides potential avenues for the elucidation of the biological mechanisms of EWS/FLI-1 oncogenesis and the development of novel therapeutic strategies.
尤因肉瘤是一种预后较差的儿童骨肿瘤，最常与t(11;22)(q24;q12)相互易位相关，该易位使EWS和FLI-1基因融合，导致产生异常的嵌合转录因子EWS/FLI-1。为了阐明EWS/FLI-1在小鼠模型中介导转化的机制，我们制备了一种鼠源Ews/Fli-1融合蛋白。我们证明，这种蛋白在体外能使成纤维细胞发生转化，类似于人EWS/FLI-1，表现为血清和非锚定依赖性生长、在裸鼠体内形成肿瘤以及致癌标志物c-myc水平升高。此外，这些细胞的转化被一种特异性阻遏物KRAB/FLI-1所抑制。KRAB/FLI-1阻遏物也抑制了人尤因肉瘤细胞系的致瘤表型。这些发现表明，通过使用序列特异性的FLI-1-DNA结合结构域靶向基因阻遏结构域，可以逆转尤因肉瘤细胞的转化表型。对EWS/FLI-1的抑制是KRAB结构域抑制ETS因子作用的首次证明。这种方法为阐明EWS/FLI-1肿瘤发生的生物学机制和开发新的治疗策略提供了潜在途径。
