Design And Synthesis Of The Small Molecule Antagonists Of MBT Domain

Epigenetic is an emerging research field which study the stably heritable change of theexpression of chromosome without the alterations in the DNA sequence. The epigenomenow can lead to a variety of human diseases. Recent studies showed that the tumor-relatedgenes, especially tumor-suppressor genes have abnormal epigenetic modifications. As aresult, research and development of small molecules that targeting the enzymes and proteinsrelated to epigenetic modification has become a hot area in oncology.The state of chromatin plays a key role in controlling the access to the genetic code. Itis largely regulated by specific chemical modifications to histone proteins and DNA. Themost important modifications of histones and DNA include: histone lysine and argininemethylation; lysine acetylation; DNA cytosine methylation; and histone sumoylation,ubiquitination, ADP-ribosylation and phosphorylation. The recognition of themethylation-state of lysine residues in histones is a critical event in chromatin regulation.The methylation-state of lysine residues will profoundly affect the interaction of the proteins,and the regulation and expression of genes. The interaction between MBT (The malignantbrain tumor) domain and the methylated lysine residues of histone is an importantmechanism in the regulation of chromatin.Data shows the modulation of MBT domain activity can lead to cell de-differentiation,re-expression of silenced genes, and possibly contribute to cellular reprogramming. So far,only a few small molecule antagonists of the MBT domain have been reported. The focus ofthis dissertation is to design and synthesis novel small molecule MBT domain antagonists. Incollaboration with Professor Frye’s research group in UNC, we have evaluated severalcompound series as potential MBT domain molecular probe.Based on the X-ray crystal structure of MBT domain, we designed and synthesized anew library of N-substituted tetrahydropyridine amide derivatives and N-substituted isoindoline derivatives. In addition, we also designed and synthesized a series ofN-aryl-substituted pyrrolidine compounds based on the X-ray co-crystal structure of theknown small molecule MBT domain antagonists UNC669with L3MBTL1. To this end, wehave developed eight synthetic routes and synthesized30novel compounds, which include:111-benzyl-N-substituted tetrahydropyridine compounds,61-cyclopentyl-N-substituted-tetrahydropyridine compounds,11-(4-methoxy)-substituted-tetrahydropyridine compound;6N-Substituted-isoindoline compounds;6N-aryl-substituted pyrrolidine compounds.The biological evaluation is carried out at the Center for Integrated Chemical Biologyand Drug Discovery of the University of North Carolina. So far, twenty four compoundsdesigned based on the crystal structure of the MBT domain have been screened using theAlpha Screen and ITC combination methods. None of these compounds showed appreciableantagonistic activity of the MBT domain. This result indicates that the pyrrolidine moiety ofUNC669may be the crucial structural requirement for its effective interaction with the MBTdomain. The evaluation of additional compounds with the pyrrolidine moiety is in progress.