Design, Synthesis And Antitumor Activity Evaluation Of [1,2,3]triazolo[4,5-d] Pyrimidine Derivatives As LSD1 Inhibitors

The identification of lysine specific demethylase 1(LSD 1),as the first histone demethylase discovered,revealed that the histone methylation was also a dynamic and reversible process.LSD1 can demethylate mono-and dimethylated H3K4/K9 via flavin adenine dinucleotide(FAD)-dependent enzymatic oxidation.LSD1 could also demethylate nonhistone proteins such as p53,E2F transcription factor and DNA methyltransferases(DNMTs),and further modulate their activity.LSD1 has been observed to be overexpressed in various malignant tumors,and closely associated with tumorigenesis,proliferation,migration and invasion.Thus,LSD1 has been considered as a promising epigenetic target for anticancer drug discovery,and it will be of great significance to develop highly effective and specific LSD 1 inhibitors for cancer therapy.Our group has previously reported several classes of LSD1 inhibitors based on different skeletons including dithiocarbamate-triazoles,pyrimidine-thioureas and other heterocyclic arenes,displaying good inhibitory effect against LSD1 as well as LSD 1-overexpressed tumor cells.Molecular docking and dynamics simulations revealed that the hydrogen interactions between pyrimidine/triazole ring and amino acid residues may make an important contribution to the inhibition against LSD1.Herein,both of the two N-heterocycles were combined into one system,leading to a sereies of novel pyrimidine-triazole derivatives via the introduction of various groups,all of which were screened for LSD1 inhibition.Among them,the potent candidate compounds were further evaluated for their in vitro antitumor activities,and mechanism studies were also carried out.The main topics of this thesis are as follows.1.A fused[1,2,3]triazolo[4,5-d]pyrimidine scaffold was designed and synthesized by incorporating the pyrimidine and triazole rings into one skeleton.The preliminary structural modifications of this skeleton were performed,leading to the first series of 30 compounds with the aim of finding basic structural requirement for LSD1 inhibition.Among them,compound 1-37 exhibited the most inhibitory activity against LSDI.The mechanism study indicated that compound 1-37 inacti-vated LSD1 in a reversible process,and showed certain selectivity to LSDI over MAO-A/B.Moreover,compound I-37 could inhibit the proliferation,migration and EMT process,upregulated the expression of CD86 as a surrogate cellular biomarker for LSD1 activity.Molecular docking study predicted that the hydrogen interaction between pyridine and amino acid residues could be responsible for the inhibitory activity of 2-thiopyridine series.2.A series of potent LSD1 inhibitors were obtained by the introduction of mercapto heterocyclic units into the designed pyrimidine-triazole skeleton.The most active compound I1-15u(IC50 = 50 nM)could inhibit LSDI reversibly,selectively,and competitively with H3K4me2 substrate as well.In addition,compound II-15u displayed a broad-spectrum antiproliferative activity toward several LSD 1-overexpressed cancer cell lines,and was more sensitive to myeloid leukemia cell lines.Compound II-15u could strongly inhibit the proliferation and colony formation of THP-1,and also cause remarkable morphological changes of THP-1.This compound could also induce expression change of CD86 and CD llb in THP-1 cells,confirming its cellular activity and ability of inducing differentiation.Furthermore,molecular docking simulations and 3D-QSAR studies were performed to predict the binding models and to illustrate the SARs in this series,and would be helpful for the development of more efficient pyrimidine-triazole based LSDl inhibitors.3.Furthermore,a new class of pyrimidie-triazole derivatives bearing a hydrazone unit were designed,synthesized and screened for LSD1 inhibition and antiproliferation against several solid tumor cell lines.Most of this series of compounds exhibited moderate to good antiproliferative activity toward the test cell lines,however they did not show acceptable inhibitory activity toward LSD1I The most potent compound IJII-43 displayed a broad-spectrum proliferation inhibition with the IC50 around 1 μM.This candidate compound could significantly inhibit the colony formation of MGC-803,and also induce its apoptosis probably via the mitochondrial pathway.In conclusion,we have synthesized 122 pyrimidine-triazole derivatives and evaluated their LSD I inhibition,and a series of structurally novel LSD I inhibitor were obtained.The identification of these inhibitors expanded the chemotypes of LSD1 inhibitor,and would be of great significance for the further biological study of LSD1 involved mechanism,as well as for the development of anticancer drugs.