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dc.contributor.advisorSchreiber, Stuart L.
dc.contributor.authorYuan, Yuan
dc.date.accessioned2013-03-06T21:25:27Z
dash.embargo.terms2014-10-05en_US
dc.date.issued2013-03-06
dc.date.submitted2012
dc.identifier.citationYuan, Yuan. 2012. Small-Molecule Modulators of Pancreatic Ductal Cells: Histone Methyltransferases and \(\beta\)-Cell Transdifferentiation. Doctoral dissertation, Harvard University.en_US
dc.identifier.otherhttp://dissertations.umi.com/gsas.harvard:10637en
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:10370567
dc.description.abstractSmall molecules are important not only for treating human diseases but also for studying disease-related biological processes. This dissertation focuses on the effects of small molecules on pancreatic ductal adenocarcinoma cells. Here, I describe the discovery of two small-molecule tool compounds and their applications for interrogating the biological processes related to two distinct diseases in the human pancreas. First, BRD4770 was identified as a histone methyltransferase inhibitor through a target-based biochemical approach, and was used as a probe to study the function of methyltransferases in cancer cells. Second, BRD7552 was discovered as an inducer of Pdx1 using a cell-based phenotypic screening approach, and was used to induce the expression of Pdx1, a master regulatory transcription factor required for \(\beta\)-cell transdifferentiation. This compound is particularly interesting for the study of type-1 diabetes (T1D). The histone methyltransferase G9a catalyzes methylation of lysine 9 on histone H3, a modification linked to aberrant silencing of tumor-suppressor genes. The second chapter describes the collaborative effort leading to the identification of BRD4770 as a probe to study the function of G9a in human pancreatic cancer cells. BRD4770 induces cellular senescence and inhibits both anchorage-dependent and -independent proliferation in PANC-1 cell line, presumably mediated through ATM-pathway activation. Chapter three describes the study of a natural product gossypol, which significantly enhances the BRD4770 cytotoxicity in p53-mutant cells through autophagic cell death. The up-regulation of BNIP3 might be responsible for the synergistic cell death, suggesting that G9a inhibition may help overcome drug resistance in certain cancer cells. Ectopic overexpression of Pdx1, Ngn3, and MafA can reprogram pancreatic exocrine cells to insulin-producing cells in mice, which sheds light on a new avenue for treating T1D. The fourth chapter focuses on a gene expression-based assay using quantitative real-time PCR technique to screen >60,000 compounds for induction of one or more of these three transcription factors. A novel compound BRD7552 which up-regulated Pdx1 mRNA and protein levels in PANC-1 cells was identified. BRD7552 induces changes of the epigenetic markers within the Pdx1 promoter region consistent with transcriptional activation. Furthermore, BRD7552 partially complements Pdx1 in cell culture, enhancing the expression of insulin induced by the introduction of the three genes in PANC-1 cells. In summary, the central theme of my dissertation is to identify novel bioactive small molecules using different screening approaches, as well as to explore their effects in pancreatic ductal cells.en_US
dc.description.sponsorshipChemistry and Chemical Biologyen_US
dc.language.isoen_USen_US
dash.licenseMETA_ONLY
dc.subjectBiochemistryen_US
dc.subjectChemistryen_US
dc.subjectbeta-cell transdifferentiationen_US
dc.subjecthigh-throughtput screeningen_US
dc.subjecthistone methyltransferaseen_US
dc.subjectpancreatic ductal cellsen_US
dc.subjectPdx1en_US
dc.subjectsmall-molecule probeen_US
dc.titleSmall-Molecule Modulators of Pancreatic Ductal Cells: Histone Methyltransferases and \(\beta\)-Cell Transdifferentiationen_US
dc.typeThesis or Dissertationen_US
dash.depositing.authorYuan, Yuan
dash.embargo.until10000-01-01
thesis.degree.date2012en_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorHarvard Universityen_US
thesis.degree.leveldoctoralen_US
thesis.degree.namePh.D.en_US
dc.contributor.committeeMemberVerdine, Gregoryen_US
dc.contributor.committeeMemberLiu, Daviden_US
dash.contributor.affiliatedYuan, Yuan


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