magnetic-resonance-guided-high-intensity-focused-ultrasound-generated

Magnetic Resonance-Guided High Intensity Focused Ultrasound Generated Hyperthermia: A Feasible Treatment Method in a Murine Rhabdomyosarcoma Model

Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) is an established method for producing localized hyperthermia. Given the real-time ...

Mount Sinai Hospital

Sarcomas are a heterogeneous group of mesenchymal malignancies and unfortunately there are limited functional genomics platforms to assess the molecular pathways contributing to sarcomagenesis. Thus, novel model systems are needed to validate which genes should be targeted for therapeutic intervention. We hypothesized that delivery of oncogenes into mouse skeletal muscle using a retroviral (RCAS-TVA) system would result in sarcomagenesis. We also sought to determine if the cell type transformed (mesenchymal progenitors vs. terminally differentiated tissues) would influence sarcoma biology. Cells transduced with RCAS vectors directing the expression of oncoproteins KrasG12D, c-Myc and/or Igf2 were injected into the hindlimbs of mice that expressed the retroviral TVA receptor in neural/mesenchymal progenitors, skeletal/cardiac muscle or ubiquitously (N-tva, AKE and BKE strains respectively). Disrupting the G1 checkpoint CDKN2 (p16/p19-/-) resulted in sarcoma in 30% of p16/p19-/- xN-tva mice with a median latency of 23 weeks (range 8-40 weeks). A similar incidence occurred in p16/p19-/- xBKE mice (32%), however, a shorter median latency (10.4 weeks) was observed. p16/p19-/- xAKE mice also developed sarcomas (24% incidence; median 9 weeks) yet 31% of mice also developed lung sarcomas. Gene-anchored PCR demonstrated retroviral DNA integration in 86% of N-tva, 93% of BKE and 88% of AKE tumors. KrasG12D was the most frequent oncogene isolated. Oncogene delivery by the RCAS-TVA system can generate sarcomas in mice with a defective cell cycle checkpoint. Sarcoma biology differed between the different RCAS models we created, likely due to the cell population being transformed. This genetically flexible system will be a valuable tool for sarcoma research.

Development of genetically flexible mouse models of sarcoma using RCAS-TVA mediated gene delivery.

Leiomyosarcoma (LMS) is a common type of soft tissue sarcoma that responds poorly to standard chemotherapy. Thus the goal of this study was to identify novel selective therapies that may be effective in leiomyosarcoma by screening cell lines with a small molecule library comprised of 480 kinase inhibitors to functionally determine which signalling pathways may be critical for LMS growth.

PI3K/AKT/mTOR inhibition in combination with doxorubicin is an effective therapy for leiomyosarcoma.

T cell receptor (TCR) recognition of a peptide antigen in the context of MHC molecules initiates positive and negative cascades that regulate T cell activation, proliferation and differentiation, and culminate in the acquisition of effector T cell functions. These processes are a prerequisite for the induction of specific T cell-mediated adaptive immune responses. A key event in the activation of TCR-coupled signaling pathways is the phosphorylation of tyrosine residues within the cytoplasmic tails of the CD3 subunits, predominantly CD3ζ. These transiently formed phosphotyrosyl epitopes serve as docking sites for SH2-domain containing effector molecules, predominantly the ZAP70 protein tyrosine kinase, which is critical for signal propagation. We found that CrkI and CrkII adaptor proteins also interact with CD3ζ in TCR activated-, but not in resting-, T cells. Crk binding to CD3ζ was independent of ZAP70 and also occurred in ZAP70-deficient T cells. Binding was mediated by Crk-SH2 domain interaction with phosphotyrosine-containing motifs on CD3ζ, via a direct physical interaction, as demonstrated by Far-Western blot. CrkII binding to CD3ζ could also be demonstrated in a heterologous system, where coexpression of a catalytically active Lck was used to phosphorylate the CD3ζ chain. TCR activation-induced Crk binding to CD3ζ resulted in increased and prolonged phosphorylation of CD3ζ, as well as ZAP70 and LAT, suggesting a positive role for CrkI/II binding to CD3ζ in regulation of TCR-coupled signaling pathways. Furthermore, Crk-dependent increased phosphorylation of CD3ζ coincided with inhibition of TCR downmodulation, supporting a positive role for Crk adaptor proteins in TCR-mediated signal amplification.

Crk adaptor proteins regulate CD3ζ chain phosphorylation and TCR/CD3 down-modulation in activated T cells.

Virtual Biobanking for Retroperitoneal Sarcoma: A Transatlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG) Initiative.

Leiomyosarcomas (LMS) are genetically heterogeneous tumors differentiating along smooth muscle lines. Currently, LMS treatment is not informed by molecular subtyping and is associated with highly variable survival. While disease site continues to dictate clinical management, the contribution of genetic factors to LMS subtype, origins, and timing are unknown. Here we analyze 70 genomes and 130 transcriptomes of LMS, including multiple tumor regions and paired metastases. Molecular profiling highlight the very early origins of LMS. We uncover three specific subtypes of LMS that likely develop from distinct lineages of smooth muscle cells. Of these, dedifferentiated LMS with high immune infiltration and tumors primarily of gynecological origin harbor genomic dystrophin deletions and/or loss of dystrophin expression, acquire the highest burden of genomic mutation, and are associated with worse survival. Homologous recombination defects lead to genome-wide mutational signatures, and a corresponding sensitivity to PARP trappers and other DNA damage response inhibitors, suggesting a promising therapeutic strategy for LMS. Finally, by phylogenetic reconstruction, we present evidence that clones seeding lethal metastases arise decades prior to LMS diagnosis.

Yael Babichev

2Lunenfeld-Tanenbaum Research Institute,
Lunenfeld-Tanenbaum Research Institute

Mount Sinai Hospital

Magnetic Resonance-Guided High Intensity Focused Ultrasound Generated Hyperthermia: A Feasible Treatment Method in a Murine Rhabdomyosarcoma Model

Yael Babichev

2Lunenfeld-Tanenbaum Research Institute,Lunenfeld-Tanenbaum Research Institute

Mount Sinai Hospital

Magnetic Resonance-Guided High Intensity Focused Ultrasound Generated Hyperthermia: A Feasible Treatment Method in a Murine Rhabdomyosarcoma Model

2Lunenfeld-Tanenbaum Research Institute,
Lunenfeld-Tanenbaum Research Institute