Retinoblastoma and osteosarcoma are the third and eight most common forms of childhood cancers, respectively. Children with hereditary retinoblastoma -germline mutation in the RB1 gene- are predisposed to osteosarcoma later in their life. Despite recent progress in clinical outcomes in retinoblastoma and osteosarcoma, enucleation remains a frequent treatment for retinoblastoma and the survival rate for osteosarcoma is just over 50%, underscoring the need to identify molecular mechanisms responsible for disease progression and to develop more effective drugs. Previous finding from our laboratory suggest that aE2Fs regulate recruitment of the epigenetic machinery that is required for tumor formation in the absence of the Rb family and that epigenetic deregulation of genes in the absence of Rb is sufficient for retinoblastoma formation. However, while functional loss of RB1 is enough for retinoblastoma formation, osteosarcoma requires inactivation of an additional tumor suppressor, TP53. Through the study of the epigenetic landscape of retinoblastoma and osteosarcoma, in this research proposal we hope to determine why some cell types are more susceptible to tumor formation than other cell types, in particular following RB1 inactivation.
We aim to identify direct transcriptional targets of Rb epigenetically regulated by activator E2Fs in retinoblastoma and elucidate the role of epigenetics and genome instability in osteosarcomagenesis and how Rb participates in this process. The use integrative analyses of the changes in chromatin organization and gene expression that occur during tumorigenesis will help us identify potential novel therapeutic targets for anticancer treatment.

Public Health Relevance

Retinoblastoma and osteosarcoma are two common forms of childhood cancers. Children with hereditary retinoblastoma often develop osteosarcoma later in their life. An outstanding question in the field of cancer biology is why mutations in the gene tha causes tumors (RB1) in the retina are insufficient for tumor formation in the bone. In this proposal we will test the hypothesis that the level of dependence of a cell on RB1 for maintenance of their epigenetic fingerprint will be directly correlated with their propensity to progress into carcinogenesis when RB1 is lost. Thus, through integrative analyses of the changes in chromatin organization and gene expression that occur during tumorigenesis, we will identify potential novel therapeutic targets for anticancer treatment. The written critiques of individual reviewers are provided in essentially unedited form in this section. Please note that these critiques and criteria scores were prepared prior to the meeting and may not have been revised subsequent to any discussions at the review meeting. The Resume and Summary of Discussion section above summarizes the final opinions of the committee.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Career Transition Award (K99)
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Study Section
Subcommittee G - Education (NCI)
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Schmidt, Michael K
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St. Jude Children's Research Hospital
United States
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Wu, Stephanie C; Benavente, Claudia A (2018) Chromatin remodeling protein HELLS is upregulated by inactivation of the RB-E2F pathway and is nonessential for osteosarcoma tumorigenesis. Oncotarget 9:32580-32592
Benavente, Claudia A; Finkelstein, David; Johnson, Dianna A et al. (2014) Chromatin remodelers HELLS and UHRF1 mediate the epigenetic deregulation of genes that drive retinoblastoma tumor progression. Oncotarget 5:9594-608
Benavente, Claudia A; McEvoy, Justina D; Finkelstein, David et al. (2013) Cross-species genomic and epigenomic landscape of retinoblastoma. Oncotarget 4:844-59