Design,Synthesis And Mechanism Of Small Molecular Inhibitors Of BRD4 And PDGFRβ In Breast Cancer

Breast cancer is one of the most common malignant tumors in women.Three negative breast cancer,due to its poor differentiation,high invasiveness and distant metastasis,has become a difficult point in breast cancer research.In this paper,we designed and synthesized new type of small molecule inhibitors targeting BRD4 and PDGFRβ respectively for breast cancer treatment,and the mechanism was elucidated in vitro and vivo preliminarily.Breast cancer has distinct epigenomics characteristics.The dysfunction of histone modification factor,such as BRD4,could lead to overexpression of some oncogenes.For BRD4,we first identified the potential BRD4-AMPK axis of autophagy by TCGA big data and immunoprecipitation analysis for BRD4.Based-structure drug design,49 candidate compounds were synthesized through multiple rounds of structural optimization and screenings.A novel type BRD4 small molecule inhibitor,2-OH-4-hydroxy-3-hydroxy-5-dimethylphenyl-7-methyl-5-methyl-6 dimethyl-.5-methyl-6-dimethyl-6-tetrahydropyrido[43-d]thieno[23-d]pyrimidin43Hni-one(9f),was discovered.Based on the analysis of the crystal structure of 9f-BRD4 complex,the residues Pro82 and Gln85 played an enssential role in the selectivety of 9f over BRD4.The vitro assays showed that 9f could induce BRD4-AMPK-regulated autophagy related cell death.The pharmacodynamics of 9f were evaluated in nude mice and zebrafish xenoimplantation models.Secondly,we designed and synthesized a series of pyrimidine derivatives based on the structural characteristics of type Ⅱ inhibitors to inhibit the proliferation of triple negative breast cancer.41 pyrimidine derivatives were synthesized by multi-wheel structure optimization.The results showed that most of the compounds had moderate to strong antiproliferative activity,and Y29 showed the strongest antiproliferative activity in MDA-MB-231 cells.Then,we performed molecular docking and kinetic simulation,the results showed that PDGFβ-Y29 complex is a stable system.In vitro assay,Y29 could significantly inhibit breast cancer cell metastasis through autophagy induced by PDGFβ inhibition,and Y29 could enhance autophagy related cell death through AKT-MAPK negative feedback pathway.These studies have explored the potential small molecular inhibitors for BRD4 and PDGFRβ in breast cancer and illuminated the mechanism of action in triple-negative breast cancer and non-triple-negative breast cancer respectively.These results provide new rationales and methods for the development of promissing lead compounds for the treatment of breast cancer.