Abstract LB-272: First evidence that FUS-CHOP leads to increased invasion and migration via MMPs in liposarcoma
Authors: Patil Nitin , Rasheed Suhail Ahmed Kabeer , Laufs Stephanie , Schwarzbach Matthias , Allgayer Heike 
Published: February 2011

A unique feature of human soft tissue liposarcoma is that it exhibits a characteristic and stable translocation (12;16)(113;p11), resulting in (a) FUS-CHOP fusion transcript(s) with a corresponding oncogenic protein. The translocation leads to a fusion between the CHOP (GADD153) gene and FUS (TLS), replacing the RNA-binding domain (amino-terminal part) of FUS by the basic leucine zipper domain of CHOP. In vitro, the transforming effects of FUS-CHOP have been demonstrated in fibroblasts. However, precise molecular mechanisms associated with FUS-CHOP as a putative transcription factor, and a putative ability of FUS-CHOP to promote invasion and metastasis as the hallmarks of malignant tumors have never been investigated.

The present project is being conducted to 1. determine the potential of FUS-CHOP to promote invasion and metastasis, 2. to define first potential target genes and molecular mediators in this context.

In first micro-array analysis conducted at resected liposarcoma patient tissues and HT1080 and SW872 cell lines, we found evidence that, among 144 genes deregulated significantly, the matrix metalloproteinases MMP-2, -9, and -7 were induced in expression after FUS-CHOP transfection. We validated these results in the HT1080 fibrosarcoma and SW872 liposarcoma cell lines at the RNA-level using real-time PCR, first of all focusing at MMPs. We found that MMP-2, -7, and -9 were significantly upregulated after FUS-CHOP transfection in both cell lines. Next, we performed luciferase experiments using a transient transfection of reporter constructs spanning the basal promoter sequences of MMP-2, -7, and -9, and an expression construct of FUS-CHOP, respectively. We found that an overexpression of FUS-CHOP was able to enhance the promoter activity of all the MMPs tested. Furthermore, we observed that overexpression of FUS-CHOP in HT1080 fibrosarcoma and SW872 liposarcoma cells significantly induced invasion and migration in Boyden chamber matrigel assays (p&lt;0.05).

Taken together, these results for the first time suggest that FUS-CHOP overexpression leads to invasion and migration of lipo-/fibrosarcoma cells, which might be, at least in part, due to the transcriptional regulation of different MMPs. In current ongoing studies, we are validating further putative target genes of FUS-CHOP in the context of metastasis, and are confirming the current results in an in vivo model. Furthermore, ongoing theoretical studies in our laboratory will elucidate precise molecular mechanisms in the context of FUS-CHOP as a transcription factor.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-272.