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: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: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.
Project description:RECQL4, a member of the RecQ helicase family, plays a role in maintaining genomic stability, but its precise function remains unclear. The N-terminus of RECQL4 has similarity to Sld2, a protein required for the firing of DNA replication origins in budding yeast. Consistent with this sequence similarity, Xenopus RECQL4 has been implicated in initiating DNA replication in oocyte extracts. To determine whether human RECQL4 is required for firing of DNA replication origins, we generated cells in which both RECQL4 alleles were targeted, resulting in either lack of protein expression (Knock-Out) or expression of a full-length, mutant protein lacking helicase activity (Helicase Dead). Surprisingly, both the RECQL4 Knock-Out and Helicase Dead cells were viable and exhibited essentially identical origin firing profiles as the parental cells. Analysis of the rate of fork progression revealed normal rates in the RECQL4 Knock Out cells, but decreased rates in the RECQL4 inactive cells. Thus, while budding yeast Sld2 is required for DNA replication origin firing, our evidence suggest that human RECQL4 has assumed a role in the regulation of replication fork progression.
Project description:Pulmonary metastasis continues to be the most common cause of death in osteosarcoma. Indeed, the 5-year survival for newly diagnosed osteosarcoma patients has not significantly changed in over 20 years. Further understanding of the mechanisms of metastasis and resistance for this aggressive pediatric cancer is necessary. Pet dogs naturally develop osteosarcoma providing a novel opportunity to model metastasis development and progression. Given the accelerated biology of canine osteosarcoma, we hypothesized that a direct comparison of canine and pediatric osteosarcoma expression profiles may help identify novel metastasis-associated tumor targets that have been missed through the study of the human cancer alone. Collectively, these data support the strong similarities between human and canine osteosarcoma and underline the opportunities provided by a comparative oncology approach as a means to improve our understanding of cancer biology and therapy. Profiles of human osteosarcoma, single channel design
Project description:Combining CDK4/6 inhibitors (CDK4/6i) with endocrine therapy has proven clinically effective and represents now the first-line treatment for advanced Luminal Breast Cancer (LBC) patients. However, resistance to CDK4/6i almost invariably arises in these patients, emphasising the critical need to comprehend these mechanisms and develop new strategies to overcome resistance. We report on the generation and characterisation of a LBC PDX displaying acquired resistance to CDK4/6i palbociclib. Treating a sensitive luminal BC PDX with the CDK4/6i palbociclib revealed that, despite initial tumour shrinkage, some tumours might eventually regrow under drug treatment. RNA sequencing, followed by gene set enrichment analyses, unveiled that this PDX have become refractory to CDK4/6i, both at biological and molecular level.