Project description:Osteosarcoma is the most common malignancy of bone, and occurs most frequently in children and adolescents. Currently, the most reliable technique for prognostication is measuring histopathologic tumor necrosis following preoperative chemotherapy, and favourable prognosis is signified by 90% or greater estimated necrosis of the tumour. Neither genetic testing nor molecular biomarkers have been described for this tumour. We used the novel nanoString mRNA expression analysis system to analyzed total RNA from 35 flash-frozen sporadic paediatric osteosarcoma biopsy and resection specimens to quantify mRNA expression for 17 oncogenes and tumour suppressor genes. Three oncogenes, cell cycle regulator gene CDC5L, the RecQ DNA helicase gene RECQL4, and the cyclin-dependent kinase gene CDK4, were more highly expressed (p<0.05) in tumours which responded poorly to neoadjuvant chemotherapy. A similar trend (p<0.10) was identified for the osteoblast-specific transcription factor gene RUNX2. No statistically significant difference existed in comparing expression of CDC5L, RECQL4, CDK4, and RUNX2 between biopsy and resection samples. Additionally, analysis of expression data in the context of histological subtype yielded preliminary results for deducing molecular subtypes of osteosarcomas. Osteoblastic osteosarcomas possessed higher expression of CDKN1A, PTEN, and RUNX2 relative to their fibroblastic counterparts (p<0.05). This research study shows that CDC5L, RECQL4, and CDK4 tumour expression levels may be useful for identifying patients who may not benefit from the current standardized chemotherapy regimen. Total RNA was isolated from 52 pediatric osteosarcoma samples (prechemotherapy biopsies and resections), 3 osteosarcoma cell lines, and normal human osteoblasts. nanoString mRNA expression analysis was applied to samples split between 3 batches to compare samples based on clinical and pathologic data reports, and to compare samples with normal human osteoblasts. For 43 samples, there were complete data and the RNA was successfully assayed. Analysis was performed using R.
Project description:Osteosarcoma is the most common malignancy of bone, and occurs most frequently in children and adolescents. Currently, the most reliable technique for prognostication is measuring histopathologic tumor necrosis following preoperative chemotherapy, and favourable prognosis is signified by 90% or greater estimated necrosis of the tumour. Neither genetic testing nor molecular biomarkers have been described for this tumour. We used the novel nanoString mRNA expression analysis system to analyzed total RNA from 35 flash-frozen sporadic paediatric osteosarcoma biopsy and resection specimens to quantify mRNA expression for 17 oncogenes and tumour suppressor genes. Three oncogenes, cell cycle regulator gene CDC5L, the RecQ DNA helicase gene RECQL4, and the cyclin-dependent kinase gene CDK4, were more highly expressed (p<0.05) in tumours which responded poorly to neoadjuvant chemotherapy. A similar trend (p<0.10) was identified for the osteoblast-specific transcription factor gene RUNX2. No statistically significant difference existed in comparing expression of CDC5L, RECQL4, CDK4, and RUNX2 between biopsy and resection samples. Additionally, analysis of expression data in the context of histological subtype yielded preliminary results for deducing molecular subtypes of osteosarcomas. Osteoblastic osteosarcomas possessed higher expression of CDKN1A, PTEN, and RUNX2 relative to their fibroblastic counterparts (p<0.05). This research study shows that CDC5L, RECQL4, and CDK4 tumour expression levels may be useful for identifying patients who may not benefit from the current standardized chemotherapy regimen.
Project description:This study was performed to provide a detailed understanding of the functions and pathways that intersect with the essential DNA replication factor RECQL4. Mutations in RECQL4 cause Rothmund-Thomson Syndrome (RTS), a familial cancer syndrome associated with early onset osteosarcoma in a high proportion of patients. Using murine RECQL4 mutations that closely map to recurrent human RTS mutations, we performed an unbiased genome-wide screen to identify genes that, when deleted, rescued the phenotypes associated with RECQL4 mutation.
Project description:This study was performed to provide a detailed understanding of the functions and pathways that intersect with the essential DNA replication factor RECQL4. Mutations in RECQL4 cause Rothmund-Thomson Syndrome (RTS), a familial cancer syndrome associated with early onset osteosarcoma in a high proportion of patients. Using murine RECQL4 mutations that closely map to recurrent human RTS mutations, we performed an unbiased genome-wide screen to identify genes that, when deleted, rescued the phenotypes associated with RECQL4 mutation.
Project description:The high frequency of somatic copy number alterations, as opposed to point mutations, is considered a unique feature of high-grade serous ovarian carcinoma (HGSOC). Amplification-dependent overexpression of RECQL4, which participates in DNA replication and repair, mediates the development of various cancers, but its pathobiological and clinical roles are poorly understood. Here, using bioinformatics analysis, RECQL4 amplification was found to occur in 27% of HGSOC samples in the TCGA cohort. RECQL4 was found to be upregulated and associated with a poor prognosis based on the immunohistochemistry staining of HGSOC. Functionally, RECQL4 overexpression increased proliferation and invasion of ovarian cancer cells both in vitro and in vivo. RECQL4 silencing had the opposite effects. In addition, RECQL4 knockdown enhanced the sensitivity of ovarian cancer cells to cisplatin and PARP inhibitor (PARPi). Further mechanistic investigations revealed that MAFB was a downstream target of RECQL4. The oncogenic effect of RECQL4 was attenuated after MAFB knockdown. Moreover, RECQL4 overexpression was negatively regulated by the tumour suppressor miR-10a-5p. Collectively, these findings indicate that genomic amplification and low expression of miR-10a-5p contribute to RECQL4 overexpression in ovarian cancer. This is the first study to reveal the oncogenic functions and clinical significance of RECQL4 in ovarian cancer.
Project description:Osteosarcoma (OS) is the most common primary bone cancer in adolescents, young adults (AYA), and children, with up to 25% of patients developing metastatic disease, primarily in the lungs. Despite survival rates being >70% for localized tumors, patients with metastatic OS have <30% survival due to limited effective salvage therapies. OS is characterized by chromosomal instability (CINs) and dysregulated CDK4/6 and PI3K/mTOR pathways. The retinoblastoma protein (RB), a downstream target of CDK4/6, is a key regulator of G1/S cell cycle progression. We validated these targets in OS cell lines, xenografts, and patient-derived xenografts (PDXs), revealing CDK4/6 hyperactivation. While CDK4/6 inhibitors show promise, they are ineffective as monotherapies due to cytostatic effects and resistance from compensatory pathways, such as PI3K/AKT/mTOR. This study investigates dual inhibition of CDK4/6 and PI3K/mTOR using palbociclib and voxtalisib, respectively, in OS models. In RB proficient (RB+) OS lines, the combination therapy exhibited synergistic inhibition of cell growth and G1 arrest, while inducing autophagy without disrupting palbociclib-induced senescence. Prolonged treatment triggered autophagy in treatment-naïve PDXs, with senescence partially reversed in the combination group. Combination therapy enhanced palbociclib efficacy in both pretreated and naïve PDX models, improving survival. Mechanistically, palbociclib reduced CDK1/2 activity, while voxtalisib suppressed CDK1/2 and RB1 phosphorylation, impairing cell cycle progression. The combination significantly reduced metastatic burden and improved survival in OS lung colonization models, inhibiting pre-established metastatic foci. Kinome profiling and proteomic analyses confirmed decreased PI3K and mTOR activity. This study highlights the potential of CDK4/6 and PI3K/mTOR dual inhibition in OS, offering therapeutic promise for overcoming resistance and improving outcomes in pediatric and AYA patients with CDK4/6 hyperactivation.
Project description:Exposure to ionizing radiation during childhood markedly increases the risk of developing papillary thyroid cancer. We identified non-overlapping somatic driver mutations in all 26 cases of post-Chernobyl thyroid cancers we studied through candidate gene assays and next generation RNA-sequencing. We found that 22/26 harbored fusion oncogenes arising primarily through intrachromosomal rearrangements. Altogether 23/26 of the oncogenic drivers identified in this cohort aberrantly activate MAPK signaling, including the two novel somatic rearrangements ETV6-NTRK3 and AGK-BRAF. Two other tumors harbored distinct fusions leading to overexpression of the nuclear receptor PPARγ. A lower prevalence of fusion oncogenes was found in a cohort of pediatric thyroid cancers from children from the same geographical regions that were not exposed to radiation. Radiation-induced thyroid cancers are a paradigm of tumorigenesis driven by fusion oncogenes that activate MAPK signaling or, less frequently, a PPARγ-driven transcriptional program. Examination of transcriptome profiles and genetic somatic changes in thyroid cancer.
Project description:Despite the development of diagnostic and advanced treatment strategies, the prognosis of patients with osteosarcoma remains poor. A limited understanding of the pathogenesis of osteosarcomas has impeded any improvement in patient outcomes over the past 4 decades. It is thus urgent to identify novel effective targets and treatment regimens for osteosarcoma patients. In this study we delineated the super-enhancer landscape in osteosarcoma cells on the basis of H3K27ac signal intensity by ChIP-Seq and found that super-enhancer-associated genes contribute to the malignant potential of osteosarcoma. THZ2, a novel small molecular inhibitor, shows a powerful anti-osteosarcoma ability through suppress super-enhancer-associated genes selectively. Utilizing the characteristics of super-enhancers in cancer cells, we identified 5 critical super-enhancer-associated oncogenes. With the comparative and retrospective analysis in large numbers of human specimens from patients, these 5 oncogenes were observed closely related with patient prognosis. Our findings determined that targeting super-enhancer-associated oncogenes with transcriptional inhibitor, THZ2, was a promising therapeutic strategy in osteosarcoma, and provided novel candidate targets for patients with osteosarcoma.