Research Of Novel Small Molecule Inhibitors Of BRD4 With Anti-renal Cancer Activity

In our modern society,one of the severe consequences of fast-pace life,environment pollution and population aging is the horrible increase of cancer morbidity.In China,renal cancer rate increases 3%every year.What's more,some of the renal caner cases were discovered and diagnosed at late stages.Even if surgery or drug treatment was applied,a large proportion of renal cancer patients suffered from cancer re-occurrence or drug resistance.The overall survival of renal cancer is only about two years.With the deeper understanding of the mechanism of renal cancer and the rapid development of molecular biology,many biomarkers and novel therapeutical targets are involved in renal caner monitoring and treatment.Although there are several first line or second line anti-renal cancer drugs including the VEGFR inhibitor sunitinib,anti-VEGF monoclonal antibody bevacizumab,cancer immunotherapy anti-PD-1 nivolumab etc.,the problems of low response rate?about30%?and drug resistance remain tough,which encourages us to develop novel targets and drugs for renal cancer treatment.In addition,BRD4,a key“reader”in epigenetics,was reported to be over-expressed together with its down-stream oncogene c-myc in renal cell carcinoma.Thus,it's worth trying to develop novel BRD4 inhibitors to suppress renal cancer cell growth.In this research,the combined strategy of drug repurposing and target-based durg design was employed.First,a high-throughput screening platform of ALPHA assay was built to test the binding affinity to BRD4 of compounds from the FDA-approved drug library,which resulted an active hit compound nitroxoline(IC₅₀=1.1?M)with simple structure and good drug-likeness.Second,by several rounds of chemical modification,we systemically assess the SAR around the hit scaffold,8-hydroxy-quinoline,and optimized the IC₅₀0 values to less than 200 nM.In total,27 8-hydroxy-quinoline derivatives were synthesized.Among them,BDF-1253 showed GI₅₀0 at low single digital micro-molar level against 4 renal cancer cell lines 786-O,Caki,ACHN and A498 in vitro,and caused little toxicity to the normal renal tissue.For in vivo efficacy evaluation,BDF-1253 inhibited renal tumor growth on xenograft mice model with no obvious toxicity.Finally,the anti-cancer mechanism of BDF-1253 against renal cancer was revealed by RT-PCR,western blot and RNA-seq experiments,which suggested that by inhibition BRD4 our lead compound,BDF-1253,down-regulated the expression of the oncogene c-myc,up-regulated the expression of the tumor suppressor gene p53 and activated the apoptosis pathway.In summary,our research proved the feasibility of using BRD4inhibitors to intervene the development of renal cancer.More active compounds were proposed for the research and development of anti-renal cancer drugs.