Project description:Abstract Background: Cataracts are among the most common causes of childhood vision loss worldwide. This study seeks to identify differentially expressed proteins in the aqueous humor of pediatric cataract patients. Methods: Samples of aqueous humor were collected from pediatric and adult cataract patients and underwent mass spectrometry-based proteomic analysis. Samples of pediatric cataracts were grouped by subtype and compared to adult samples. Differentially expressed proteins in each subtype were identified. Gene ontology analysis was performed using WikiPaths for each cataract subtype. Results: Seven pediatric patients and ten adult patients were included in the study. Of the pediatric samples, all seven (100%) were male, three (43%) had traumatic cataracts, two (29%) had congenital cataracts, and two (29%) had posterior polar cataracts. Of the adult patients, seven (70%) were female and seven (70%) had predominantly nuclear sclerotic cataracts. 128 proteins were upregulated in the pediatric samples and 127 proteins were upregulated in the adult samples, with 75 proteins shared by both groups. Gene ontology analysis identified inflammatory and oxidative stress pathways as upregulated in pediatric cataracts. Conclusions: Inflammatory and oxidative stress mechanisms may be involved in pediatric cataract formation and warrant further investigation.
Project description:Purpose: To define copy number alterations and gene expression signatures underlying pediatric high-grade glioma (HGG). Patients and Methods: We conducted a high-resolution analysis of genomic imbalances in 78 de novo pediatric HGG, including 7 diffuse intrinsic pontine gliomas, and 10 HGG cases arising in children who received cranial irradiation for a previous cancer, using Affymetrix 500K GeneChips. Gene expression signatures for 53 tumors were analyzed with Affymetrix U133v2 arrays. Results were compared with publicly available data from adult tumors. Results: Pediatric and adult glioblastoma were clearly distinguished by frequent gain of chromosome 1q (30% vs 9%) and lower frequency of chromosome 7 gain (13% vs 74%), respectively. The most common focal amplifications also differed, with PDGFRA and EGFR predominant in childhood and adult populations respectively. These common alterations in pediatric HGG were detected at higher frequency in irradiation-induced tumors, suggesting that these are initiating events in childhood gliomagenesis. CDKN2A was the most common tumor suppressor gene targeted by homozygous deletion in pediatric HGG. No IDH1 hotspot mutations were found in pediatric tumors, highlighting molecular differences in pathogenesis between childhood HGG and adult secondary glioblastoma. Integrated copy number and gene expression data indicated that deregulated PDGFRA signaling plays a major role in pediatric HGG. Conclusions: Integrated molecular profiling showed substantial differences in the molecular features underlying pediatric and adult HGG, indicating that findings in adult tumors cannot be simply extrapolated to younger patients. PDGFRA may be a useful target for pediatric HGG including diffuse pontine gliomas. Keywords: disease state analysis
Project description:Cancer genomics has illuminated a wide spectrum of genes and core molecular processes contributing to human malignancy. Still, the genetic and molecular basis of many cancers remains only partially explained. Genetic predisposition accounts for 5-10% of cancer diagnoses and genetic events cooperating with known somatic driver events are poorly understood. Analyzing established cancer predisposition genes in medulloblastoma (MB), a malignant childhood brain tumor, we recently identified pathogenic germline variants that account for 5% of all MB patients. Here, by extending our previous analysis to include all protein-coding genes, we discovered and replicated rare germline loss-of-function (LoF) variants across Elongator Complex Protein 1 (ELP1) on 9q31.3 in 15% of pediatric MBSHH cases, thus implicating ELP1 as the most common MB predisposition gene and increasing genetic predisposition to 40% for pediatric MBSHH. Inheritance was verified based on parent-offspring and pedigree analysis, which identified two families with a history of pediatric MB. ELP1-associated MBs were restricted to the molecular SHH subtype and were characterized by universal biallelic inactivation of ELP1 due to somatic loss of chromosome 9q. The majority of ELP1-associated MBs exhibited co-occurring somatic PTCH1 (9q22.32) alterations, suggesting that ELP1-deficiency predisposes to tumor development in combination with constitutive activation of SHH signaling. ELP1 is an essential subunit of the evolutionary conserved Elongator complex, whose primary function is to enable efficient translational elongation through tRNAs modifications at the wobble (U34) position. Biochemical, transcriptional, and proteomic analyses revealed that ELP1-associated MBSHH are characterized by a destabilized core Elongator complex, loss of Elongator-dependent tRNA modifications, codon-dependent translational reprogramming, and induction of the unfolded protein response (UPR), consistent with deregulation of protein homeostasis due to Elongator-deficiency in model systems. Our findings suggest that genetic predisposition to proteome instability is a previously underappreciated determinant in the pathogenesis of pediatric brain cancer. These results provide strong rationale for further investigating the role of protein homeostasis in other pediatric and adult cancer types and potential opportunities for novel therapeutic interference.