FUS–DDIT3 Fusion Protein-Driven IGF-IR Signaling is a Therapeutic Target in Myxoid Liposarcoma

Abstract

Myxoid liposarcoma is an aggressive disease with particular propensity to develop hematogenic metastases. Over 90% of myxoid liposarcoma are characterized by a reciprocal t(12;16)(q13;p11) translocation. The resulting chimeric FUS-DDIT3 fusion protein plays a crucial role in myxoid liposarcoma pathogenesis; however, its specific impact on oncogenic signaling pathways remains to be substantiated. We here investigate the functional role of FUS-DDIT3 in IGF-IR/PI3K/Akt signaling driving myxoid liposarcoma pathogenesis. Immunohistochemical evaluation of key effectors of the IGF-IR/PI3K/Akt signaling axis was performed in a comprehensive cohort of myxoid liposarcoma specimens. FUS-DDIT3 dependency and biological function of the IGF-IR/PI3K/Akt signaling cascade were analyzed using a HT1080 fibrosarcoma-based myxoid liposarcoma tumor model and multiple tumor-derived myxoid liposarcoma cell lines. An established myxoid liposarcoma avian chorioallantoic membrane model was used for confirmation of the preclinical results. A comprehensive subset of myxoid liposarcoma specimens showed elevated expression and phosphorylation levels of various IGF-IR/PI3K/Akt signaling effectors. In HT1080 fibrosarcoma cells, overexpression of FUS-DDIT3 induced aberrant IGF-IR/PI3K/Akt pathway activity, which was dependent on transcriptional induction of the gene. Conversely, RNAi-mediated knockdown in myxoid liposarcoma cells led to an inactivation of IGF-IR/PI3K/Akt signaling associated with diminished mRNA expression. Treatment of myxoid liposarcoma cell lines with several IGF-IR inhibitors resulted in significant growth inhibition and Our preclinical study substantiates the fundamental role of the IGF-IR/PI3K/Akt signaling pathway in myxoid liposarcoma pathogenesis and provides a mechanism-based rationale for molecular- targeted approaches in myxoid liposarcoma cancer therapy..

The multikinase inhibitor EC‐70124 synergistically increased the antitumor activity of doxorubicin in sarcomas

“…9,19 Upstream, the PI3K/AKT/mTOR pathway may be triggered by the activation several receptor tyrosine kinases (RTKs), such as IGF1R, platelet-derived growth factor receptor (PDGFR) or fibroblast growth factor receptor, and nonreceptor tyrosine kinases, like SRC, whose deregulation reportedly plays a role in the tumorigenic process in several types of sarcoma. 15,17,18,20 Consistent with these findings, the efficiency of several mTOR inhibitors have been evaluated in sarcomas. 9 Clinical testing of rapamycin and its derived analogs has provided at best only modest results.…”

“…On the other hand, the activation of mTORC2 is involved in actin remodeling and may also contribute to complete activation of mTORC1 through the activation of AKT earlier in the pathway . Upstream, the PI3K/AKT/mTOR pathway may be triggered by the activation several receptor tyrosine kinases (RTKs), such as IGF1R, platelet‐derived growth factor receptor (PDGFR) or fibroblast growth factor receptor, and nonreceptor tyrosine kinases, like SRC, whose deregulation reportedly plays a role in the tumorigenic process in several types of sarcoma …”

“…[9][10][11][12] Specifically, myxoid and round cell liposarcomas (MRCLS), an adipocytic tumor characterized by the expression of the fusion oncogene FUS-CHOP, frequently show oncogenic events, such as mutations in PI3KCA or overactivation of insulin-like growth factor I receptor (IGF1R) or SRC signaling, which provoke an abnormal activation of these route. [13][14][15][16][17][18] mTOR is a serine/threonine protein kinase that exists in two different complexes (mTORC1 and mTORC2). Activated mTORC1 phosphorylates its downstream targets S6 kinase-1, which in turn phosphorylates/activates the ribosomal protein S6 (S6), and the eukaryotic initiation factor 4E-binding protein-1 (4EBP1) resulting in the activation of the synthesis of a panoply of proteins involved in cell growth, metabolism and survival.…”

Myxoid liposarcoma: it's a hippo's world

“…Hope for future improved therapies builds on published studies that have provided important insights into druggable alterations in MSL signaling: Activating mutations in the catalytic subunit of phosphatidylinositol‐4,5‐bisphosphate 3‐kinase catalytic subunit alpha (PIK3CA) occur predominantly in the more aggressive round cell variant of MLS (Trautmann et al , ). Moreover, myxoid liposarcomas were associated with FUS:DDIT3‐driven induction of insulin‐like growth factor 2 (IGF2) expression and activation of insulin‐like growth factor 1 receptor (IGF‐IR)/phosphoinositide 3‐kinase (PI3K)/AKT serine/threonine kinase 1 (AKT) signaling (Trautmann et al , ), overexpression of fibroblast growth factor receptor 2 (FGFR2) (Künstlinger et al , ), and activation of casein 2 kinase/atypical nuclear‐factor kappaB signaling (Willems et al , ). These observations corresponded to significant in vitro and/or in vivo inhibition of MLS growth after treatment with PI3K/mTOR inhibitors, IGF‐IR receptor inhibitors, FGFR inhibitors in combination with trabectedin, and the casein kinase 2 inhibitor 4,5,6,7‐tetrabromobenzotriazole (TBB) combined with dasatinib (Willems et al , ; Künstlinger et al , ; Trautmann et al , ).…”

“…Moreover, myxoid liposarcomas were associated with FUS:DDIT3‐driven induction of insulin‐like growth factor 2 (IGF2) expression and activation of insulin‐like growth factor 1 receptor (IGF‐IR)/phosphoinositide 3‐kinase (PI3K)/AKT serine/threonine kinase 1 (AKT) signaling (Trautmann et al , ), overexpression of fibroblast growth factor receptor 2 (FGFR2) (Künstlinger et al , ), and activation of casein 2 kinase/atypical nuclear‐factor kappaB signaling (Willems et al , ). These observations corresponded to significant in vitro and/or in vivo inhibition of MLS growth after treatment with PI3K/mTOR inhibitors, IGF‐IR receptor inhibitors, FGFR inhibitors in combination with trabectedin, and the casein kinase 2 inhibitor 4,5,6,7‐tetrabromobenzotriazole (TBB) combined with dasatinib (Willems et al , ; Künstlinger et al , ; Trautmann et al , ). The present study by Trautmann et al introduces overactive YAP1 signaling as a hallmark of human MLS, and another candidate target for therapeutic intervention.…”