Abstract PR004: Fusion protein-driven IGF-IR signals deregulate hippo pathway promoting oncogenic cooperation of YAP1 and FUS-DDIT3

Introduction: Myxoid liposarcoma (MLS) is molecularly characterized by a recurrent chromosomal translocation which generates a chimeric FUS-DDIT3 fusion gene. The FUS-DDIT3 oncoprotein, acting as a transcriptional dysregulator, has been shown to be essential in MLS pathogenesis, among others through deregulation of IGF-IR/PI3K/AKT signaling, but its exact mode of function remains incompletely understood. Recently, a particular reliance on the Hippo pathway effector and transcriptional co-regulator YAP1 was found in MLS; however, the molecular mechanism of FUS-DDIT3-dependent YAP1 activation and its contribution to MLS pathogenesis remain unclear. Experimental Procedures: The expression of IGF-IR and YAP1 was analyzed in a large cohort of MLS specimens by immunohistochemistry. In vitro analyses were performed employing a human mesenchymal stem cell system stably expressing FUS-DDIT3 and human MLS cell lines. RNA interference-based approaches, experiments with small-molecule kinase inhibitors, co-immunoprecipitation, proximity ligation assays, transcriptome sequencing and adipogenic differentiation assays were performed to determine the interplay of FUS-DDIT3, IGF-IR-dependent signals, and YAP1 in MLS cells. Results: Immunohistochemically, a significant subset of MLS samples showed concurrent expression of IGF-IR and nuclear YAP1. In vitro, FUS-DDIT3-driven IGF-IR signaling was found to promote stability and nuclear accumulation of YAP1 via deregulation of the Hippo pathway. Co-immunoprecipitation and proximity ligation assays revealed nuclear co-localization of FUS-DDIT3 and YAP1 in FUS-DDIT3-expressing mesenchymal stem cells and MLS cell lines. Transcriptome sequencing of MLS cells demonstrated that FUS-DDIT3 and YAP1 co-regulate specific oncogenic gene signatures related to proliferation, cell cycle progression, apoptosis, and adipogenesis. In differentiation assays, FUS-DDIT3 and YAP1 were found to cooperate in adipogenic differentiation arrest. Conclusions: Our study provides molecular insights into a complex FUS-DDIT3-driven network involving IGF-IR signals acting on Hippo/YAP1, and uncovers cooperative effects of YAP1 and FUS-DDIT3 in the pathogenesis of MLS.

Citation Format: Ruth Berthold, Ilka Isfort, Cihan Erkut, Lorena Heinst, Inga Grünewald, Eva Wardelmann, Thomas Kindler, Pierre Åman, Thomas G.P. Grünewald, Florencia Cidre-Aranaz, Marcel Trautmann, Stefan Fröhling, Claudia Scholl, Wolfgang Hartmann. Fusion protein-driven IGF-IR signals deregulate hippo pathway promoting oncogenic cooperation of YAP1 and FUS-DDIT3 [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr PR004.

MondoA drives malignancy in B-ALL through enhanced adaptation to metabolic stress

Cancer cells are in most instances characterized by rapid proliferation and uncontrolled cell division. Hence, they must adapt to proliferation-induced metabolic stress through intrinsic or acquired antimetabolic stress responses to maintain homeostasis and survival. One mechanism to achieve this is reprogramming gene expression in a metabolism-dependent manner. MondoA (also known as Myc-associated factor X-like protein X-interacting protein [MLXIP]), a member of the MYC interactome, has been described as an example of such a metabolic sensor. However, the role of MondoA in malignancy is not fully understood and the underlying mechanism in metabolic responses remains elusive. By assessing patient data sets, we found that MondoA overexpression is associated with worse survival in pediatric common acute lymphoblastic leukemia (ALL; B-precursor ALL [B-ALL]). Using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) and RNA-interference approaches, we observed that MondoA depletion reduces the transformational capacity of B-ALL cells in vitro and dramatically inhibits malignant potential in an in vivo mouse model. Interestingly, reduced expression of MondoA in patient data sets correlated with enrichment in metabolic pathways. The loss of MondoA correlated with increased tricarboxylic acid cycle activity. Mechanistically, MondoA senses metabolic stress in B-ALL cells by restricting oxidative phosphorylation through reduced pyruvate dehydrogenase activity. Glutamine starvation conditions greatly enhance this effect and highlight the inability to mitigate metabolic stress upon loss of MondoA in B-ALL. Our findings give novel insight into the function of MondoA in pediatric B-ALL and support the notion that MondoA inhibition in this entity offers a therapeutic opportunity and should be further explored.

Abstract A13: Genome-wide association study identifies multiple new loci associated with Ewing sarcoma susceptibility

Ewing sarcoma (EWS), a pediatric tumor predominantly occurring in children of European ancestry, is characterized by the EWSR1-FLI1 fusion oncogene. We performed a genome-wide association study (GWAS) of 749 EWS cases and 1,378 unaffected individuals of European ancestry. Our study replicated previously reported susceptibility loci at 1p36.22, 10q21.3, and 15q15.1 and identified new loci at 6p25.1, 8q24.23, 20p11.22, and 20p11.23 (P-values <5x10-8). Effect estimates exhibited odds ratios (ORs) in excess of 1.7, which is high for cancer GWAS, and striking in light of the rarity of EWS cases in familial cancer syndromes. In expression quantitative trait locus (eQTL) analyses, we observed altered expression patterns for plausible candidate genes at 6p25.1 with RREB1, a RAS-responsive element, and at 20p11.23 with KIZ, a centrosomal stabilization protein. The 20p11.22 locus is also near NKX2-2, a highly overexpressed gene in EWS. Interestingly, most loci reside near GGAA repeat sequences where binding of the EWSR1-FLI1 fusion protein occurs. The seven EWS susceptibility loci discovered in only 749 cases make EWS one of the most productive GWAS studied cancers when considering a locus-to-case discovery ratio. The substantive estimated ORs suggest a distinctive underlying genetic architecture for EWS in which moderate-risk SNPs likely constitute a significant fraction and may interact with EWSR1-FLI1 binding.

Citation Format: Mitchell J. Machiela, Thomas G.P. Grünewald, Didier Surdez, Stephanie Reynaud, Olivier Mirabeau, Eric Karlins, Rebeca Alba Rubio, Sakina Zaidi, Sandrine Grossetete-Lalami, Stelly Ballet, Eve Lapouble, Valérie Laurence, Jean Michon, Gaelle Pierron, Heinrich Kovar, Nathalie Gaspar, Udo Kontny, Anna González-Neira, Piero Picci, Javier Alonso, Ana Patino-Garcia, Nadège Corradini, Neal D. Freedman, Nathaniel Rothman, Casey L. Dagnall, Laurie Burdett, Kristine Jones, Michelle Manning, Kathleen Wyatt, Weiyin Zhou, Meredith Yeager, David G. Cox, Robert N. Hoover, Javed Khan, Gregory T. Armstrong, Wendy M. Leisenring, Smita Bhatia, Leslie L. Robison, Uta Dirksen, Markus Metzler, Wolfgang Hartmann, Konstantin Strauch, Thomas Kirchner, Andreas E. Kulozik, Lindsay M. Morton, Lisa Mirabello, Margaret A. Tucker, Franck Tirode, Stephen Chanock, Olivier Delattre. Genome-wide association study identifies multiple new loci associated with Ewing sarcoma susceptibility [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr A13.

Lysosome-associated membrane glycoprotein 1 predicts fratricide amongst T cell receptor transgenic CD8+ T cells directed against tumor-associated antigens

AIM

Autologous as well as allogeneic CD8+ T cells transduced with tumor antigen specific T cell receptors (TCR) may cause significant tumor lysis upon adoptive transfer. Besides unpredictable life-threatening off-target effects, these TCRs may unexpectedly commit fratricide. We hypothesized lysosome-associated membrane glycoprotein 1 (LAMP1, CD107a) to be a marker for fratricide in TCR transgenic CD8+ T cells.

METHODS

We identified HLA-A*02:01/peptide-restricted T cells directed against ADRB3295. After TCR identification, we generated HLA-A*02:01/peptide restricted TCR transgenic T cells by retroviral transduction and tested T cell expansion rates as well as A*02:01/peptide recognition and ES killing in ELISpot and xCELLigence assays. Expansion arrest was analyzed via Annexin and CD107a staining. Results were compared to CHM1319-TCR transgenic T cells.

RESULTS

Beta-3-adrenergic receptor (ADRB3) as well as chondromodulin-1 (CHM1) are over-expressed in Ewing Sarcoma (ES) but not on T cells. TCR transgenic T cells demonstrated HLA-A*02:01/ADRB3295 mediated ES recognition and killing in ELISpot and xCELLigence assays. 24h after TCR transduction, CD107a expression correlated with low expansion rates due to apoptosis of ADRB3 specific T cells in contrast to CHM1 specific transgenic T cells. Amino-acid exchange scans clearly indicated the cross-reactive potential of HLA-A*02:01/ADRB3295- and HLA-A*02:01/CHM1319-TCR transgenic T cells. Comparison of peptide motive binding affinities revealed extended fratricide among ADRB3295 specific TCR transgenic T cells in contrast to CHM1319.

CONCLUSION

Amino-acid exchange scans alone predict TCR cross-reactivity with little specificity and thus require additional assessment of potentially cross-reactive HLA-A*02:01 binding candidates. CD107a positivity is a marker for fratricide of CD8+ TCR transgenic T cells.