Study On The Synthesis And Biological Activity Of Chimeras Targeting To Degrade PLK1/BRD4 Proteins

Cancer has become the most important public health problem in China,threatening people's lives and health,and also greatly increasing the burden on society.Finding better ways to treat cancer has always been a key topic for researchers.Targeted medicine is a cancer treatment method with relatively good clinical effect and relatively high patient acceptance.With the researchers' deep understanding of the tumor microenvironment and tumor heterogeneity,the targeted treatment technology of tumors has gradually shifted from the level of targeted tissues and organs to the enrichment of drugs at the tumor site to the relevant pathogenic proteins and tumor cells.Proteins that affect the tumor microenvironment,develop new tumor treatment drugs and methods from the level of genes and proteins.According to the mechanism of ubiquitin regulating protein degradation process,a new emerging drug development technology is formed: protein degradation targeting chimeras(Proteolysis-targeting Chimeras,PROTACs)technology.Protein degradation targeting chimeras(PROTACs)are heterobifunctional molecules with three parts: one end binds to the target protein,the other end recruits E3 ligase,and the middle connects the connecting chain.The chimera molecule simultaneously binds the target protein and ubiquitin ligase E3,and induces the formation of the target protein / PROTACs / E3 ternary complex,resulting in the ubiquitination and subsequent degradation of the target protein.PROTACs technology is a fast and reversible protein knockout method.It works in conjunction with Ubiquitin-Proteasomes System(UPS)to regulate protein levels.Its unique mode of action makes this technology applicable to transcription.Factors and other non-drugable targets expand the research scope of related protein targets.PROTACs technology degrades the target protein instead of inhibiting the target protein level,thereby removing all biological functions of enzymes or non-enzymes related to the target protein,avoiding drug resistance caused by potential genetic compensation or spontaneous mutations,and improving treatment efficiency.PROTACs molecules play a catalytic role in the degradation of target proteins.Therefore,low-dose PROTACs molecules can produce good pharmacological activity,thereby reducing the possibility of off-target effects,reducing toxic and side effects,and avoiding the formation of drug resistance.By generating interactions between specific target proteins and E3 ubiquitin ligase,PROTACs technology precisely targets pathogenic proteins and improves selectivity.Therefore,PROTACs technology can be used for the development of cancer treatment drugs.Acute myeloid leukemia(AML)is a clinically common hematological malignant disease in which bone marrow leukocytes(rather than lymphoid leukocytes)proliferate abnormally.Bromodomain-containing protein 4(BRD4)and Polo-like Kinase 1(PLK1)are effective therapeutic targets in acute myeloid leukemia(AML)cells.In this study,PROTACs technology was used to link the thalidomide analogue of E3 ubiquitin ligase CRBN with different lengths of polyethylene glycol chains and the BI2536 derivative with both PLK1 and BRD4 protease inhibitor activities to synthesize targeted degradation PLK1 And BRD4 dual-target small molecule compound PROTACs-HBL,and verify the antitumor activity of the compound in leukemia cell lines.The results of CCK8 test showed that the synthesized target compound HBL-1had a good proliferation inhibitory effect on the three leukemia cells MV4-11,MOLM-13 and KG1.Flow cytometry demonstrated that HBL-1 induces MV4-11 cell apoptosis,which blocks the cell cycle of MV4-11 in G0 / G1 phase.Transwell cell migration experiments show that HBL-1 has a stronger ability to inhibit MV4-11 cell migration than inhibitor BI2536.Western-blot detection confirmed that HBL-1 can achieve rapid,efficient and long-term degradation of PLK1 and BRD4 proteins.In the MV4-11 tumor xenograft model,HBL-1 efficiently degrades PLK1 and BRD4 proteins in tumor tissues,showing good pharmacodynamic characteristics.This project uses PROTACs technology to synthesize a degradation agent that targets the degradation of the PLK1 / BRD4 double protein.This is the first report that PROTACs technology is used to degrade PLK1 protein,and it is the first time that BRD4 and PLK1 proteins are simultaneously degraded in the same cell.The synthesis of this compound opens up a new method for the treatment of acute leukemia and other types of tumors.It is an important progress in the development of cancer therapeutics and has strong research potential.