Discovery Of Novel Inhibitors Of PRMT5 And Inhibitors Of Menin-MLL Interaction

The thesis consists of two parts: the first part is discovery and optimization of selective inhibitors of protein arginine methyltransferase 5;The second part is the design,synthesis and pharmacological studies of inhibitors targeting the menin–mixed lineage leukaemia interface.1.Discovery and optimization of selective inhibitors of protein arginine methyltransferase 5.Epigenetic modifications of gene expression are essential to eukaryotic life,and their dysregulations are involved in many biological processes and numerous human diseases,especially in cancer.The protein arginine methylation is a common eukaryotic post-translational modification,with a lot of cytoplasmic and nuclear proteins being methylated on arginines.Protein arginine methyltransferases(PRMTs)can transfer the methyl group from Sadenosyl-L-methionine(Ado Met,SAM)to the guanidino group of specific arginine residues.Protein arginine methyltransferase 5(PRMT5),as a type II PRMTs,catalyzes two methyl groups transferring to arginine residues,forming ω-NG-monomethyl arginine and symmetrical ω-NG-dimethyl arginine on protein substrates.PRMT5 is reported to be validated a J-binding protein 1(JBP1),and can merge many proteins to form multimeric complex.PRMT5 is postulated to have vital roles in cell growth and proliferation,cell death,cell-cycle progression,cancer development and progression,signal transduction and so on.It has been reported that PRMT5 is overexpressed in leukemia,lymphoma,lung cancer,colorectal cancer and breast cancer.The PRMT5 has two ligand binding pockets: a SAM-binding site and a substrate-binding pocket.In order to find inhibitors with better selectivity profile,we choose to use the substrate-binding pocket for virtual screening because the SAM-binding site is shared by various histone and DNA methyltransferases.Through the virtual screening selecting and biological validating,DC_P33 was selected as a hit compound for further optimization.After analysing the structure-activity relationship(SAR),we designed and synthesized 37 compounds.Finally,we had a clear structure-activity relationship and got a novel compound zbd-22(IC50=1.0μmol).The work is useful for future development of specific PRMT5 inhibitors.2.Design,synthesis and pharmacological studies of inhibitors targeting the menin–mixed lineage leukaemia interface.Chromosomal rearrangements of the MLL gene located at chromosome band 11q23 are found in patients with de novo acute myeloid and acute lymphoblastic leukemias,and in therapy related leukemias or myelodysplastic syndrome.As a consequence of chromosomal translocations,the MLL gene is fused with one of over 60 different protein partners.Disruption of MLL by gene fusions upregulates expression of HOXA9 and MEIS1 genes that are critical to leukemogenesis.MLL fusion protein-mediated upregulation of HOXA9 and MEIS1 genes results in enhanced proliferation and blockage of hematopoietic differentiation,ultimately leading to acute leukemia.The oncogenic function of MLL fusion proteins is critically dependent on their direct interaction with menin,blocking the menin–MLL interaction might represent a viable approach to reverse the oncogenic activity of MLL fusion proteins in leukemia and may lead to novel therapeutics.Identifying inhibitors from existing drugs avoids substantial risks because these drugs have well-known safety and pharmacokinetic profiles.This process also skips the stages of chemical optimisation,toxicology and formulation development.In the present study,we screened a collection of clinical compounds to identify loperamide as a novel inhibitor targeting the menin–MLL interface.After a series of structural modifications,the most potent compound MM-46 exhibited a half maximal inhibitory concentration(IC50)value of 0.83 μM for inhibition of the menin-MLL interaction,a half-maximal growth inhibitory concentration(IC50)value of 6.3μM for inhibition of MV-4-11 human leukemia cells.Further optimization of this compound is under progress.