Department of Experimental Surgery and Molecular Oncology of Solid Tumors, Medical Faculty Mannheim, University of Heidelberg and German Cancer Research Center, Heidelberg, Germany.
Int J Cancer. 2014 Jun 15;134(12):2808-19. doi: 10.1002/ijc.28638. Epub 2013 Dec 7.
The FUS-CHOP fusion protein has been found to be instrumental for specific oncogenic processes in liposarcoma, but its ability to induce metastasis and the underlying mechanisms by which this can be achieved remain unknown. To dissect its functional role in this context, we stably overexpressed this protein in SW872 liposarcoma and HT1080 fibrosarcoma cell lines, and were able to demonstrate that forced expression of FUS-CHOP significantly increases migration and invasion, as well as enhances lung and liver metastasis in the in vivo chicken chorioallantoic membrane (CAM) model, that is proliferation independent. Additionally, FUS-CHOP enhances the expression of matrix-metalloproteinases -2 and -9, and transactivates their promoters in vitro. Mutational analysis showed that C/EBP-β- (-769/-755), NF-κB (-525/-516) and CREB/AP-1 (-218/-207) sites were important for MMP-2 and NF-κB (-604/-598), AP-1 (-539/-532) and AP-1 (-81/-72) for MMP-9 transactivation. Moreover, a direct in vivo interaction of FUS-CHOP was observed in case of the MMP-2 promoter within region (-769/-207). siRNA data revealed that MMP-2 expression is essential in the FUS-CHOP induced metastatic phenotype. MMP-2-mRNA and protein expression correlated significantly with FUS-CHOP positivity in 46 resected patient liposarcoma tissues. We have for the first time provided substantial evidence for the FUS-CHOP oncoprotein as an inducer of metastasis that is due to the transcriptional induction of specific tumor-associated proteases. Insights gained from this study not only support a deeper understanding of the mechanistic properties of FUS-CHOP, but also open up new avenues for targeted therapy.
FUS-CHOP 融合蛋白已被发现对脂肪肉瘤中的特定致癌过程至关重要,但它诱导转移的能力及其实现的潜在机制仍不清楚。为了剖析其在这种情况下的功能作用,我们在 SW872 脂肪肉瘤和 HT1080 纤维肉瘤细胞系中稳定过表达这种蛋白,并能够证明 FUS-CHOP 的强制表达显著增加了迁移和侵袭,以及增强了体内鸡胚绒毛尿囊膜 (CAM) 模型中的肺和肝转移,这是增殖独立性的。此外,FUS-CHOP 增强了基质金属蛋白酶 -2 和 -9 的表达,并在体外激活它们的启动子。突变分析表明,C/EBP-β-(-769/-755)、NF-κB(-525/-516)和 CREB/AP-1(-218/-207) 位点对于 MMP-2 和 NF-κB(-604/-598)、AP-1(-539/-532)和 AP-1(-81/-72)对于 MMP-9 的反式激活很重要。此外,在 MMP-2 启动子区域 (-769/-207) 中观察到 FUS-CHOP 的直接体内相互作用。siRNA 数据表明,MMP-2 表达在 FUS-CHOP 诱导的转移表型中是必不可少的。在 46 例切除的脂肪肉瘤组织中,MMP-2-mRNA 和蛋白表达与 FUS-CHOP 阳性显著相关。我们首次提供了实质性证据,证明 FUS-CHOP 癌蛋白是一种诱导转移的蛋白,这是由于特定肿瘤相关蛋白酶的转录诱导。从这项研究中获得的见解不仅支持了对 FUS-CHOP 机械特性的更深入理解,而且为靶向治疗开辟了新途径。