Biology subjects

Alex Kentsis

Publications and source records attributed to Alex Kentsis.

6 recordsLinked to original sources

bioRxiv2016

Towards comprehensive and quantitative proteomics for diagnosis and therapy of human disease

Abbreviations\n\nAbstractDespite superior analytical features, mass spectrometry proteomics remains seldom used for the basic investigation and clinical treatment of human disease. This need is particularly pressing for childhood diseases that can be rare in incidence and variable in presentation. Modern mass spectrometry enables detailed functional characterization of the pathogenic biochemical processes, as achieved by accurate and comprehensive quantification of proteins and their regulatory chemical modifications. Here, we describe how high-accuracy mass spectrometry in combination with high-resolution chromatographic separations can be leveraged to meet these analytical requirements in a mechanism-focused manner. We review the quantification methods capable of producing accurate measurements of protein abundance and post-translational modification stoichiometries. We then discuss how experimental design and chromatographic resolution can be leveraged to achieve comprehensive functional characterization of biochemical processes in complex biological proteomes. Finally, we describe current approaches for quantitative analysis of a common functional protein modification: reversible phosphorylation. In all, current instrumentation and methods of high-resolution chromatography and mass spectrometry proteomics are poised for immediate translation into improved diagnostic and therapeutic strategies for pediatric and adult diseases.

Cell Biology↗

bioRxiv2016

Forward genetic screen of human transposase genomic rearrangements

Background. Numerous human genes encode potentially active DNA transposases or recombinases, but our understanding of their functions remains limited due to shortage of methods to profile their activities on endogenous genomic substrates. Results. To enable functional analysis of human transposase-derived genes, we combined forward chemical genetic hypoxanthine-guanine phosphoribosyltransferase 1 (HPRT1) screening with massively parallel paired-end DNA sequencing and structural variant genome assembly and analysis. Here, we report the HPRT1 mutational spectrum induced by the human transposase PGBD5, including PGBD5-specific signal sequences (PSS) that serve as potential genomic rearrangement substrates. Conclusions. The discovered PSS motifs and high-throughput forward chemical genomic screening approach should prove useful for the elucidation of endogenous genome remodeling activities of PGBD5 and other domesticated human DNA transposases and recombinases.

Genomics↗

bioRxiv2016

Genomics of primary chemoresistance and remission induction failure in pediatric and adult acute myeloid leukemia

Despite intense efforts, the cure rates of children and adults with AML remain unsatisfactory in large part due to resistance to chemotherapy. Whilst cytogenetic risk stratification proved valuable in identifying causes of therapy failure and disease relapse, cytogenetically normal AML remains the most prevalent disease type, with significant heterogeneity of clinical outcomes, including primary chemoresistance. Using targeted sequencing of 670 genes recurrently mutated in hematologic malignancies, we investigated the genetic basis of primary chemotherapy resistance and remission induction failure of 107 primary cases obtained at diagnosis from children and adults with cytogenetically normal AML. Comparative analysis revealed mutations of SETBP1, ASXL1 and RELN to be significantly enriched at diagnosis in primary induction failure as compared to remission cases. In addition, this analysis revealed novel genomic alterations not previously described in AML, as well as distinct genes that are significantly overexpressed in therapy resistant AML. However, identified gene mutations were sufficient to explain only a minority of cases of primary induction failure. Thus, additional genetic or molecular mechanisms must cause primary chemoresistance in pediatric and adult acute myeloid leukemias.\n\nKey PointsO_LITargeted gene sequencing of 670 genes in adult and pediatric AML\nC_LIO_LIProfiling of 107 primary AML samples identifies new genomic alterations for primary chemoresistance\nC_LI

Cancer Biology↗

bioRxiv2016

Integrating genomics into clinical pediatric oncology using the molecular tumor board at the Memorial Sloan Kettering Cancer Center

BackgroundPediatric oncologists have begun to leverage tumor genetic profiling to match patients with targeted therapies. At the Memorial Sloan Kettering Cancer Center (MSKCC), we developed the Pediatric Molecular Tumor Board (PMTB) to track, integrate, and interpret clinical genomic profiling and potential targeted therapeutic recommendations.\n\nProcedureThis retrospective case series includes all patients reviewed by the MSKCC PMTB from July 2014 to June 2015. Cases were submitted by treating oncologists and potential treatment recommendations were based upon the modified guidelines of the Oxford Centre for Evidence Based Medicine.\n\nResultsThere were 41 presentations of 39 individual patients during the study period. Gliomas, acute myeloid leukemia, and neuroblastoma were the most commonly reviewed cases. Thirty nine (87%) of the 45 molecular sequencing profiles utilized hybrid-capture targeted genome sequencing. In 30 (73%) of the 41 presentations, the PMTB provided therapeutic recommendations, of which 19 (46%) were implemented. Twenty-one (70%) of the recommendations involved targeted therapies. Three (14%) targeted therapy recommendations had published evidence to support the proposed recommendations (evidence levels 1-2), 8 (36%) recommendations had preclinical evidence (level 3), and 11 (50%) recommendations were based upon hypothetical biological rationales (level 4).\n\nConclusionsThe MSKCC PMTB enabled a clinically relevant interpretation of genomic profiling. Effective use of clinical genomics is anticipated to require new and improved tools to ascribe pathogenic significance and therapeutic actionability. Development of specific rule-driven clinical protocols will be needed for the incorporation and evaluation of genomic and molecular profiling in interventional prospective clinical trials.

Genomics↗

bioRxiv2016

Osteosarcoma with apparent Ewing sarcoma gene rearrangement

Poorly differentiated round cell sarcomas present diagnostic challenges due to their variable morphology and lack of specific immunophenotypic markers. We present a case of a 15-year-old female with a tibial tumor that exhibited features of Ewing-like sarcoma, including apparent rearrangement of the EWSR1 gene. Hybridization capture-based next-generation DNA sequencing showed evidence of complex genomic rearrangements, absence of known pathogenic Ewing-like chromosome translocations, and deletions RB1, PTCH1, and ATRX, supporting the diagnosis of osteosarcoma. This illustrates the potential of clinical genomic profiling to improve diagnosis and enable specifically targeted therapies for cancers with complex pathologies.

Molecular Biology↗

bioRxiv2015

Genomic DNA transposition induced by human PGBD5

Transposons are mobile genetic elements that are found in nearly all organisms, including humans. Mobilization of DNA transposons by transposase enzymes can cause genomic rearrangements, but our knowledge of human genes derived from transposases is limited. Here, we find that the protein encoded by human PGBD5, the most evolutionarily conserved transposable element-derived gene in chordates, can induce stereotypical cut-and-paste DNA transposition in human cells. Genomic integration activity of PGBD5 requires distinct aspartic acid residues in its transposase domain, and specific DNA sequences with inverted terminal repeats with similarity to piggyBac transposons. DNA transposition catalyzed by PGBD5 in human cells occurs genome-wide, with precise transposon excision and preference for insertion at TTAA sites. The apparent conservation of DNA transposition activity by PGBD5 raises the possibility that genomic remodeling may contribute to its biological function.

Genomics↗