2002 — 2007 |
Lessnick, Stephen L |
K08Activity Code Description: To provide the opportunity for promising medical scientists with demonstrated aptitude to develop into independent investigators, or for faculty members to pursue research aspects of categorical areas applicable to the awarding unit, and aid in filling the academic faculty gap in these shortage areas within health profession's institutions of the country. |
Tumor Suppressors in Ewing's Sarcoma
[unreadable] DESCRIPTION (provided by applicant): The mechanisms of cancer development in children are poorly understood. Molecular analysis of the recurrent chromosomal translocations found in many pediatric solid tumors has identified unique fusion oncogenes for each tumor type. Ewing's sarcoma is a pediatric tumor of uncertain histologic origin that is defined by the presence of a specific chromosomal rearrangement, t(11;22)(q24;q12). This translocation generates the EWS/FLI fusion oncogene. While EWS/FLI expression appears to be required for Ewing's sarcoma development, it is unlikely to be the only genetic alteration present in this tumor. The goal of this proposal, therefore, is to identify additional genetic events that are required in the genesis of Ewing's sarcoma. While expression of EWS/FLI in immortalized murine fibroblasts results in cellular transformation, our preliminary work demonstrates that expression of EWS/FLI in primary human fibroblasts results in growth arrest. Our hypothesis is that primary cells have growth-inhibitory pathways in place that prevent neoplastic transformation by oncogenes, and that these pathways are likely to be abrogated in Ewing's sarcoma. We propose a multifaceted approach to identify these pathways. First, we will use data obtained from expression analysis to identify and validate pathways that mediate this growth arrest. Next, we will identify new pathways by suppressor screening. Finally, we will determine whether these pathways are altered in Ewing's sarcoma clinical samples to identify which are biologically relevant to the development of this tumor. The results generated by these studies will not only identify cooperative mutations important for Ewing's sarcoma development, but will also provide unique insights into the mechanisms that primary cells use to inhibit oncogenic transformation.
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2009 — 2011 |
Lessnick, Stephen L. |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Antibody-Based Detection of Translocations in Pediatric Cancer
DESCRIPTION (provided by applicant): Many cancers are associated with recurrent abnormalities of chromosome structure. One abnormality, a chromosomal translocation, occurs when portions of two normal chromosomes are exchanged. In the cancer setting, translocations may change the expression of genes near the chromosomal breakpoint, or may cause an abnormal "fusion oncogene" to be formed when portions of two genes at the breakpoint become linked together in an abnormal way. The products of these fusion oncogenes induce cancer development in the cells where they occur. In many instances, the presence of these fusion oncogenes may provide diagnostic, prognostic, or therapeutic information about the tumor. A highly sensitive and specific approach for detecting these chromosomal translocations would allow new information to be developed about cancers that contain them, and would also be of great use to the clinical care of these patients with these tumors. Unfortunately, although current approaches have been useful in detecting translocations and their products, they have a number of shortcomings that limit their use. We now propose to develop a new approach for translocation detection that avoids many of the difficulties associated with current methods: antibody detection of translocations (ADOT). We plan to develop two versions of this technology, one that can analyze thousands of potential translocations at a time, but is somewhat costly, and one that can analyze a limited number of translocations at once, but is relatively cheap. We will determine the functional characteristics of these approaches, and compare them to current methodologies. At the end of these studies, we will have developed and characterized a technique for detecting these important chromosomal abnormalities that may be ready for clinical and research applications.
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2010 — 2014 |
Lessnick, Stephen L. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Ews/Fli and Its Targets in Ewing's Sarcoma
DESCRIPTION (provided by applicant): Ewing's sarcoma is a highly malignant bone-associated cancer of children and young adults that usually expresses the EWS/FLI fusion protein. EWS/FLI is the key oncoprotein in Ewing's sarcoma, and functions as an aberrant transcription factor. We recently demonstrated that EWS/FLI downregulates many more genes than it upregulates, and that a portion of these are directly regulated by EWS/FLI binding. This suggests that the widely-accepted model of EWS/FLI functioning as a transcriptional activator may be incomplete, and that it may act as a transcriptional repressor in some settings. Furthermore, our work identified a number of dysregulated genes that are required for the oncogenic behavior of Ewing's sarcoma cells, but suggested that additional targets remain to be identified. Finally, we made the unexpected discovery that EWS/FLI upregulates some of its targets by binding to GGAA-containing microsatellites. This was surprising because these microsatellites do not conform to known EWS/FLI binding sites, nor have they been previously implicated in cancer development. Based on our preliminary data, we hypothesize that EWS/FLI functions as a transcriptional activator at some loci, and as a repressor at other loci, that both of these functions are required to dysregulate critical target genes to induce oncogenic transformation, and that polymorphisms that effect transcriptional function at these loci modulate Ewing's sarcoma susceptibility or prognosis. Experiments are now proposed to test this hypothesis. The transcriptional repression domain of EWS/FLI will be defined, and its role in both the transcriptional and oncogenic function of EWS/FLI determined. Identification and analysis of genes directly regulated by EWS/FLI using both experimental and computational approaches will allow for the identification of new key targets that are involved in the development of Ewing's sarcoma. Analysis of microsatellites in patients and populations will help to define the role of these elements in disease phenotypes and susceptibility to Ewing's sarcoma. At the completion of these studies, we will have developed a deeper understanding of the mechanistic basis of Ewing's sarcoma and applied it translationally. This may allow for the development of new prognostic or therapeutic approaches to this disease, and may impact on our understanding of other ETS-associated cancers as well. PUBLIC HEALTH RELEVANCE: Many cancers are associated with abnormal ETS proteins, such as prostate cancer, leukemia, breast cancer, and sarcoma. Ewing's sarcoma, with its abnormal ETS protein EWS/FLI, serves as a paradigm to understand the function of ETS proteins in cancer. Thus, understanding the mechanisms by which EWS/FLI causes Ewing's sarcoma may identify new approaches for treating this very aggressive cancer of children and young adults, and may also allow for an improved understanding and treatments of other ETS-associated cancers as well.
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2014 — 2017 |
Lessnick, Stephen L. Sharma, Sunil |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
(Pqb-2) 'Driver' Vs. 'Passenger' Epigenetic Events in Ewing Sarcoma @ Research Inst Nationwide Children's Hosp
DESCRIPTION (provided by applicant): Ewing sarcoma is a highly malignant bone-associated cancer of children and young adults that harbors the EWS/FLI fusion protein. EWS/FLI is the key driver mutation in Ewing sarcoma because it is expressed in nearly all cases of the disease, it functions as an oncoprotein in model systems, and inhibition of EWS/FLI expression or function in Ewing sarcoma cell lines causes a loss of the oncogenic phenotype. EWS/FLI functions as an aberrant transcription factor to both activate and repress critical target genes that modulate the cancerous phenotype. Because of its absolute reliance on a single mutant transcription factor, Ewing sarcoma provides an unparalleled model to understand the relationship between a driver mutation and driver versus passenger epigenetic events in oncogenic transformation. Our published data demonstrate that EWS/FLI functions both as a transcriptional activator, and as a transcriptional repressor, at important target genes. We found that EWS/FLI functions via interaction with the nucleosome remodeling and deacetylase (NuRD) co- repressor complex to mediate transcriptional repression, and that NuRD-associated histone deacetylase (HDAC) and lysine-specific demethylase 1 (LSD1) activities are required for this function. In contrast, the mechanisms by which EWS/FLI mediates transcriptional activation are less well understood, but our preliminary data indicate that LSD1 function is also required for this activity. We therefore hypothesize that LSD1 serves as a key epigenetic regulator in Ewing sarcoma, and that its specific genomic localization is specified via its interaction with EWS/FLI to direct driver epigenetic changes at target genes critical for the Ewing sarcoma cancerous phenotype.
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