Ewing’s sarcoma is a devastating disease that affects children and young adults. Current therapies for this disease are highly toxic and lead to significant side effects.  Thus, new approaches to therapy are urgently needed.  The most common driving oncogenic event in Ewing’s sarcoma is a translocation known as EWS-FLI-1 in which the RNA binding protein EWS is translocated with the ets transcription factor FLI-1. Recent data from our laboratory demonstrates that one consequence of EWS-FLI-1 expression is the upregulation of several long non-coding RNAs (lncRNAs). As lncRNAs are increasingly recognized as regulators of many cellular processes, this observation may provide…  Read More »

Alveolar rhabdomyosarcoma (aRMS) is an aggressive cancer of skeletal muscle histogenesis that affects children and adults. A signature aRMS mutation is PAX3-FOXO1, which encodes a “super-transcription factor” thought to illegitimately reactivate embryonic myogenic pathways. PAX3-FOXO1-positive patients with metastasis have a 4-year survival of <10%. Understanding PAX3-FOXO1 pathogenicity is essential for designing novel aRMS therapies. Using primary human skeletal-muscle myoblasts (HSMMs) as precursors, we engineered a genetic model of aRMS and found that PAX3-FOXO1 enables proliferation past the senescence checkpoint. To identify genes downstream of PAX3-FOXO1 supporting this senescence bypass, we performed transcriptome profiling and observed changes in several Wnt pathway…  Read More »

Inflammatory myofibroblastic tumor (IMT) is a tumor of visceral soft tissue which harbors anaplastic lymphoma kinase (ALK) gene fusions in approximately 50% of cases. ALK tyrosine kinase inhibitors (TKIs) have been validated as an effective therapy for patients with ALK positive IMT, however, the efficacy of these inhibitors is limited by the development of acquired resistance.  Furthermore, molecular targets for the ALK negative IMT cohort remain undefined.  The objectives of this proposal are to define and characterize novel therapeutic targets in ALK negative IMT and to study mechanisms of sensitivity/resistance to ALK TKIs in ALK positive IMT. In our initial…  Read More »

The Ewing’s sarcoma family of tumors (EFT) is an aggressive childhood malignancy with dismal outcomes for patients with metastatic and recurrent disease. In an effort to identify novel agents against EFT and to provide new insights into critical pathways relied upon by these tumors, we screened a library of 309,898 chemicals for agents that selectively inhibit the growth of well-characterized EFT cell lines positive for the EWS-FLI1 fusion. By taking advantage of chemical genomic and computational biology techniques, we identified a set of highly active, structurally related agents that may represent a novel class of proteasome inhibitors. Bortezomib, the only…  Read More »

Chordoma is a rare sarcoma believed to originate from malignant transformation of notochordal remnants and accounts for 2-4% of all primary bone malignancies. Previous studies have found that brachyury expression in chordoma is necessary to maintain cell growth. However, the mechanism of brachyury-promoted growth in chordoma is not clear. Brachyury is not expressed in normal adult tissues except for the testes, suggesting that this unique protein may represent a promising therapeutic target. An important transcription factor within the T-box family of genes, brachyury is expressed in normal, undifferentiated embryonic notochord in the axial skeleton and plays an evolutionarily conserved function…  Read More »

The central hypothesis of this proposal is that combining sorafenib which enriches for sarcoma cancer stem cells (CSCs) with Natural Killer (NK) cell immunotherapy preferentially targeting the remaining sarcoma CSCs will result in a synergistic therapeutic effect against STS. If successful, this novel combination of targeted therapies may translate into clinical trials for human patients with metastatic STS. The CSC hypothesis postulates that a sub-population of quiescent cells exists within tumors which are resistant to cytotoxic therapies. It is these CSCs which then seed tumor relapse. Therefore, therapies which add a specific anti-CSC strategy to cytoreductive therapies may provide a…  Read More »

Research Idea: For the last 20 years, cellular biologists have been focusing on the role of Ras signaling pathway in neurofibromatosis 1(NF1) and its lethal derivation, malignant peripheral nerve sheath tumor (MPNST). Ras-like (Ral) proteins are crucial members of the Ras family, shown to play a pivotal role in human tumors. Because Ral guanine nucleotide exchange factors (Ral-GEFs) are direct effectors of Ras, the Ral signaling pathway has been traditionally considered a Ras-effector pathway. We introduced RalA, for the first time, as an important regulator of the biological features of MPNST with potentials for being targeted for treatment of this…  Read More »

Standard treatment for sarcoma is surgery and chemotherapy. Drug treatment usually includes a combination of doxorubicin and ifosfamide.  Unfortunately, the efficacy of these agents is hampered by the eventual development of multidrug resistance (MDR).  The mechanism of acquiring MDR in sarcomas is not well understood.  Experimental evidence from several laboratories implicate a wide range of mechanisms including miRs (also known as miRNAs) that contribute to drug sensitivity/resistance and reversing MDR has been a high priority goal for clinical and investigational oncologists. miRs are non-coding RNA chains of 21-25 nucleotides. The miRs are important regulators of gene and protein expressions; controlling…  Read More »

Osteosarcoma (OS) is the most common primary malignancy of bone. The 5-year survival for OS patients is 60-70% and virtually all deaths result from pulmonary metastases. There have been no demonstrable improvements in OS prognosis in over twenty years, and the greatest obstacle to advancement is failure to understand and address the biology of OS metastases. Novel treatment strategies focused on metastatic potential are required to improve survival. We have used related murine OS cell lines to identify factors that may confer metastatic potential. K7M2 cells are vigorously metastatic to the lung, but K12 cells are much less metastatic. We…  Read More »

A better understanding of the biology and metabolism of sarcoma growth is necessary to develop novel therapies. Argininosuccinate synthase 1 (ASS1) is the rate-limiting enzyme in the conversion of citrulline to arginine. When ASS1 is not expressed, arginine becomes an essential amino acid to a cancer cell that must be delivered from the diet. Immunohistochemical analysis of 45 subtypes of sarcoma demonstrates that ASS1 is not expressed in over 85% of 619 out of 701 patient samples, thus making this a common enzymatic defect that can be exploited therapeutically. We have demonstrated sarcomas that lack ASS1 die when treated with…  Read More »