Project description:Retinoblastoma (Rb) is a deadly childhood eye cancer that is classically initiated by inactivation of the RB1 tumor suppressor. Clinical management continues to rely on nonspecific chemotherapeutic agents that are associated with treatment resistance and toxicity. Here, we analyzed 103 whole exomes, 16 whole transcriptomes, 5 single-cell transcriptomes, and 4 whole genomes from primary Rb tumors to identify novel Rb dependencies. Several recurrent genomic aberrations implicate estrogen-related receptor gamma (ESRRG) in Rb pathogenesis. RB1 directly interacts with and inhibits ESRRG, and RB1 loss uncouples ESRRG from negative regulation. ESRRG regulates genes involved in retinogenesis and oxygen metabolism in Rb cells. ESRRG is preferentially expressed in hypoxic Rb cells in vivo. Depletion or inhibition of ESRRG causes marked Rb cell death which is exacerbated in hypoxia. These findings reveal a novel dependency of Rb cells on ESRRG, and they implicate ESRRG as a potential therapeutic vulnerability in Rb.
Project description:Retinoblastoma (Rb) is a deadly childhood eye cancer that is classically initiated by inactivation of the RB1 tumor suppressor. Clinical management continues to rely on nonspecific chemotherapeutic agents that are associated with treatment resistance and toxicity. Here, we analyzed 103 whole exomes, 20 whole transcriptomes, 5 single-cell transcriptomes, and 4 whole genomes from primary Rb tumors to identify previously unknown Rb dependencies. Several recurrent genomic aberrations implicate estrogen-related receptor gamma (ESRRG) in Rb pathogenesis. RB1 directly interacts with and inhibits ESRRG, and RB1 loss uncouples ESRRG from negative regulation. ESRRG regulates genes involved in retinogenesis and oxygen metabolism in Rb cells. ESRRG is preferentially expressed in hypoxic Rb cells in vivo. Depletion or inhibition of ESRRG causes marked Rb cell death, which is exacerbated in hypoxia. These findings reveal a previously unidentified dependency of Rb cells on ESRRG, and they implicate ESRRG as a potential therapeutic vulnerability in Rb.
Project description:Retinoblastoma (Rb), the most prevalent intraocular malignant tumor in children with global survival rate less than 30%, is mainly caused by the deficiency of the tumor suppressor RB1. A line of evidence have shown that local inflammation and immune escape play important roles in the occurrence of Rb, however the underlying mechanism remains unclear. We hypothesize that the unique neuroimmune cell type, retinal microglia, has a vital role in the Rb pathogenesis. In this study, we differentiated microglia cells (iMGs) from established induced pluripotent stem cells (iPSCs) derived from a retinoblastoma patient with the defined RB1 mutations. We investigated the function of RB1 in innate immune response of microglia and found that the expression of interleukins and chemokines, especially interleukin 6 and TNF-α, were highly upregulated in LPS-stimulated RB1 deficient iMGs, which enhanced innate immune responses and created a pro-inflammation environment. These findings demonstrated that RB1 is indispensable to maintain microglia function in innate immunity and its deficiency leads to enhanced inflammation responses, which may accelerate tumor growth and malignancy. This study provides new insights for pathological mechanism and immunotherapeutic target of retinoblastoma.
Project description:MYCNOS (MYCN opposite strand) is co-amplified with MYCN in pediatric cancers including retinoblastoma. MYCNOS encodes several RNA variants whose functions have not been elucidated in retinoblastoma. Here, we attempted to decipher the role of MYCNOS variant 1 (MYCNOS1) on the activity of MYCN-amplified retinoblastoma. We observed that MYCNOS1 supports progression of retinoblastoma. Inhibition of MYCNOS1 expression may be needed to suppress MYCN activity when treating MYCN-amplified cancers without RB1 mutation.
Project description:In this study, we generated a human genome-wide map of DNA lesions induced by ultraviolet (UV) radiation in retinoblastoma knockout (RB1 KO) cells. Interestingly, we observed increased carcinogen susceptibility in closed HI-C domainS, pericentric and subtelomeric regions in RB1 KO. We also observed increased susceptibility at cancer driver loci such as TERT and TPTE. These loci are highly mutated in melanoma. Finally, we proposed that loss of tumor suppressor function can alter carcinogen susceptibility, and subsequently the mutation frequency of the genome.
Project description:Retinoblastoma is a rare childhood cancer of the developing retina. Most retinoblastomas initiate with biallelic inactivation of the RB1 gene through diverse mechanisms including point mutations, nucleotide insertions, deletions, loss of heterozygosity and promoter hypermethylation. Recently, a novel mechanism of retinoblastoma initiation was proposed. Gallie and colleagues discovered that a small proportion of retinoblastomas lack RB1 mutations and had MYCN amplification [1]. In this study, we identified recurrent chromosomal, regional and focal genomic lesions in 94 primary retinoblastomas with their matched normal DNA using SNP 6.0 chips. We also analyzed the RB1 gene mutations and compared the mechanism of RB1 inactivation to the recurrent copy number variations in the retinoblastoma genome. In addition to the previously described focal amplification of MYCN and deletions in RB1 and BCOR, we also identified recurrent focal amplification of OTX2, a transcription factor required for retinal photoreceptor development. We identified 10 retinoblastomas in our cohort that lacked RB1 point mutations or indels. We performed whole genome sequencing on those 10 tumors and their corresponding germline DNA. In one of the tumors, the RB1 gene was unaltered, the MYCN gene was amplified and RB1 protein was expressed in the nuclei of the tumor cells. In addition, several tumors had complex patterns of structural variations and we identified 3 tumors with chromothripsis at the RB1 locus. This is the first report of chromothripsis as a mechanism for RB1 gene inactivation in cancer.