Author
Barsha Poudel
Other affiliations: Wageningen University and Research Centre, University of Queensland
Bio: Barsha Poudel is an academic researcher from University of Southern Queensland. The author has contributed to research in topics: Pyrenophora teres & Hordeum vulgare. The author has an hindex of 6, co-authored 10 publications receiving 2649 citations. Previous affiliations of Barsha Poudel include Wageningen University and Research Centre & University of Queensland.
Papers
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QIMR Berghofer Medical Research Institute1, Garvan Institute of Medical Research2, University of Queensland3, Royal North Shore Hospital4, University of Western Sydney5, Fremantle Hospital6, Royal Adelaide Hospital7, Princess Alexandra Hospital8, University of Western Australia9, Glasgow Royal Infirmary10, Beatson West of Scotland Cancer Centre11, University of Bergen12, Dresden University of Technology13, Johns Hopkins University School of Medicine14, University of Texas MD Anderson Cancer Center15, Memorial Sloan Kettering Cancer Center16, University of Verona17, University of California, San Francisco18, University of Glasgow19
TL;DR: Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2 or PALB2) and a mutational signature of DNA damage repair deficiency, and 4 of 5 individuals with these measures of defective DNA maintenance responded to platinum therapy.
Abstract: Pancreatic cancer remains one of the most lethal of malignancies and a major health burden. We performed whole-genome sequencing and copy number variation (CNV) analysis of 100 pancreatic ductal adenocarcinomas (PDACs). Chromosomal rearrangements leading to gene disruption were prevalent, affecting genes known to be important in pancreatic cancer (TP53, SMAD4, CDKN2A, ARID1A and ROBO2) and new candidate drivers of pancreatic carcinogenesis (KDM6A and PREX2). Patterns of structural variation (variation in chromosomal structure) classified PDACs into 4 subtypes with potential clinical utility: the subtypes were termed stable, locally rearranged, scattered and unstable. A significant proportion harboured focal amplifications, many of which contained druggable oncogenes (ERBB2, MET, FGFR1, CDK6, PIK3R3 and PIK3CA), but at low individual patient prevalence. Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2 or PALB2) and a mutational signature of DNA damage repair deficiency. Of 8 patients who received platinum therapy, 4 of 5 individuals with these measures of defective DNA maintenance responded.
2,035 citations
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QIMR Berghofer Medical Research Institute1, University of Queensland2, Peter MacCallum Cancer Centre3, University of Melbourne4, University of Glasgow5, South Australia Pathology6, Imperial College London7, Royal Women's Hospital8, University of Sydney9, University of New South Wales10, Victorian Life Sciences Computation Initiative11, La Trobe University12, Harvard University13, University of Chicago14, University of Western Australia15
TL;DR: It is shown that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance.
Abstract: Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.
1,195 citations
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TL;DR: This corrects the article to show that the method used to derive the H2O2 “spatially aggregating force” is based on a two-step process, not a single step, like in the previous version of this paper.
Abstract: Nature 521, 489–494 (2015); doi: 10.1038/nature14410 In this Article, the affiliations of authors Michael Quinn and Orla McNally should read “22Department of Obstetrics and Gynaecology, The University of Melbourne, and The Royal Women’s Hospital, Parkville, Victoria 3052, Australia”. Their affiliations have been corrected in the HTML and PDF versions online.
21 citations
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TL;DR: A five-locus phylogenetic analysis of 80 isolates of Macrophomina from 28 plant species in Australia, combined with genealogical concordance phylogenetic species recognition and coalescent-based species delimitation approaches, found M. phaseolina, M. pseudophaseolina and M. tecta sp.
Abstract: Worldwide, most isolates of Macrophomina (Botryosphaeriaceae) have been attributed to the generalist phytopathogen M. phaseolina. Since 2014, three cryptic species of Macrophomina have been recognised by molecular methods. This study elucidates the taxonomy of Macrophomina species associated with broadacre and horticultural crops in Australia. A five-locus phylogenetic analysis of 80 isolates of Macrophomina from 28 plant species in Australia, combined with genealogical concordance phylogenetic species recognition and coalescent-based species delimitation approaches, found M. phaseolina, M. pseudophaseolina and supported the introduction of M. tecta sp. nov. Macrophomina phaseolina was the most frequently isolated (88%). Macrophomina pseudophaseolina is reported for the first time in Australia. Macrophomina tecta was isolated from stems of Sorghum bicolor and Vigna radiata with charcoal rot symptoms in New South Wales and Queensland. The potential for two or more Macrophomina species to co-infect the same host has implications for disease epidemiology and pathogen evolution. Future investigations into the distribution, biology, host range and population diversity of the new Macrophomina records are needed.
19 citations
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TL;DR: A suite of sequence-specific markers were developed which clearly distinguish the two forms of P. teres and enable unambiguous identification of hybrids and develop a suite of markers which identify hybrids with genetic and pathogenic variability.
Abstract: Pyrenophora teres f. teres and P. teres f. maculata cause net form and spot form, respectively, of net blotch on barley (Hordeum vulgare). The two forms reproduce sexually, producing hybrids with genetic and pathogenic variability. Phenotypic identification of hybrids is challenging because lesions induced by hybrids on host plants resemble lesions induced by either P. teres f. teres or P. teres f. maculata. In this study, 12 sequence-specific polymerase chain reaction markers were developed based on expressed regions spread across the genome. The primers were validated using 210 P. teres isolates, 2 putative field hybrids (WAC10721 and SNB172), 50 laboratory-produced hybrids, and 7 isolates collected from barley grass (H. leporinum). The sequence-specific markers confirmed isolate WAC10721 as a hybrid. Only four P. teres f. teres markers amplified on DNA of barley grass isolates. Amplified fragment length polymorphism markers suggested that P. teres barley grass isolates are genetically different from P. teres barley isolates and that the second putative hybrid (SNB172) is a barley grass isolate. We developed a suite of markers which clearly distinguish the two forms of P. teres and enable unambiguous identification of hybrids.
18 citations
Cited by
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TL;DR: It is suggested that the natural selection against large insertion/deletion is so weak that a large amount of variation is maintained in a population.
11,521 citations
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University of Queensland1, University of Glasgow2, QIMR Berghofer Medical Research Institute3, Garvan Institute of Medical Research4, Baylor College of Medicine5, University of Utah6, South Australia Pathology7, University of Adelaide8, Harvard University9, Campbelltown Hospital10, St. Vincent's Health System11, University of New South Wales12, University of Newcastle13, Royal North Shore Hospital14, University of Sydney15, Royal Prince Alfred Hospital16, Fiona Stanley Hospital17, Royal Adelaide Hospital18, Princess Alexandra Hospital19, University of Western Australia20, Beatson West of Scotland Cancer Centre21, Southern General Hospital22, Dresden University of Technology23, University of Texas MD Anderson Cancer Center24, Memorial Sloan Kettering Cancer Center25, Johns Hopkins University School of Medicine26, University of Verona27, Mayo Clinic28, University of Melbourne29
TL;DR: Detailed genomic analysis of 456 pancreatic ductal adenocarcinomas identified 32 recurrently mutated genes that aggregate into 10 pathways: KRAS, TGF-β, WNT, NOTCH, ROBO/SLIT signalling, G1/S transition, SWI-SNF, chromatin modification, DNA repair and RNA processing.
Abstract: Integrated genomic analysis of 456 pancreatic ductal adenocarcinomas identified 32 recurrently mutated genes that aggregate into 10 pathways: KRAS, TGF-β, WNT, NOTCH, ROBO/SLIT signalling, G1/S transition, SWI-SNF, chromatin modification, DNA repair and RNA processing. Expression analysis defined 4 subtypes: (1) squamous; (2) pancreatic progenitor; (3) immunogenic; and (4) aberrantly differentiated endocrine exocrine (ADEX) that correlate with histopathological characteristics. Squamous tumours are enriched for TP53 and KDM6A mutations, upregulation of the TP63∆N transcriptional network, hypermethylation of pancreatic endodermal cell-fate determining genes and have a poor prognosis. Pancreatic progenitor tumours preferentially express genes involved in early pancreatic development (FOXA2/3, PDX1 and MNX1). ADEX tumours displayed upregulation of genes that regulate networks involved in KRAS activation, exocrine (NR5A2 and RBPJL), and endocrine differentiation (NEUROD1 and NKX2-2). Immunogenic tumours contained upregulated immune networks including pathways involved in acquired immune suppression. These data infer differences in the molecular evolution of pancreatic cancer subtypes and identify opportunities for therapeutic development.
2,443 citations
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TL;DR: Inflammation is a biological response of the immune system that can be triggered by a variety of factors, including pathogens, damaged cells and toxic compounds, potentially leading to tissue damage or disease.
Abstract: Inflammation is a biological response of the immune system that can be triggered by a variety of factors, including pathogens, damaged cells and toxic compounds. These factors may induce acute and/or chronic inflammatory responses in the heart, pancreas, liver, kidney, lung, brain, intestinal tract and reproductive system, potentially leading to tissue damage or disease. Both infectious and non-infectious agents and cell damage activate inflammatory cells and trigger inflammatory signaling pathways, most commonly the NF-κB, MAPK, and JAK-STAT pathways. Here, we review inflammatory responses within organs, focusing on the etiology of inflammation, inflammatory response mechanisms, resolution of inflammation, and organ-specific inflammatory responses.
2,197 citations
01 Jan 2011
TL;DR: The sheer volume and scope of data posed by this flood of data pose a significant challenge to the development of efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data.
Abstract: Rapid improvements in sequencing and array-based platforms are resulting in a flood of diverse genome-wide data, including data from exome and whole-genome sequencing, epigenetic surveys, expression profiling of coding and noncoding RNAs, single nucleotide polymorphism (SNP) and copy number profiling, and functional assays. Analysis of these large, diverse data sets holds the promise of a more comprehensive understanding of the genome and its relation to human disease. Experienced and knowledgeable human review is an essential component of this process, complementing computational approaches. This calls for efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data. However, the sheer volume and scope of data pose a significant challenge to the development of such tools.
2,187 citations
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Wellcome Trust Sanger Institute1, Cambridge University Hospitals NHS Foundation Trust2, Lund University3, Erasmus University Medical Center4, Radboud University Nijmegen5, European Bioinformatics Institute6, University of Oslo7, Oslo University Hospital8, Gachon University9, Netherlands Cancer Institute10, Université libre de Bruxelles11, University of Antwerp12, Harvard University13, University of Amsterdam14, University of Ulsan15, Hanyang University16, Memorial Sloan Kettering Cancer Center17, University of Texas MD Anderson Cancer Center18, French Institute of Health and Medical Research19, Ninewells Hospital20, ICM Partners21, University of Queensland22, University of Iceland23, Curie Institute24, University of Cambridge25, Institute of Cancer Research26, King's College London27, University of Bergen28, Singapore General Hospital29
TL;DR: This analysis of all classes of somatic mutation across exons, introns and intergenic regions highlights the repertoire of cancer genes and mutational processes operative, and progresses towards a comprehensive account of the somatic genetic basis of breast cancer.
Abstract: We analysed whole-genome sequences of 560 breast cancers to advance understanding of the driver mutations conferring clonal advantage and the mutational processes generating somatic mutations. We found that 93 protein-coding cancer genes carried probable driver mutations. Some non-coding regions exhibited high mutation frequencies, but most have distinctive structural features probably causing elevated mutation rates and do not contain driver mutations. Mutational signature analysis was extended to genome rearrangements and revealed twelve base substitution and six rearrangement signatures. Three rearrangement signatures, characterized by tandem duplications or deletions, appear associated with defective homologous-recombination-based DNA repair: one with deficient BRCA1 function, another with deficient BRCA1 or BRCA2 function, the cause of the third is unknown. This analysis of all classes of somatic mutation across exons, introns and intergenic regions highlights the repertoire of cancer genes and mutational processes operating, and progresses towards a comprehensive account of the somatic genetic basis of breast cancer.
1,696 citations