Identification Of Histone Deacetylase Inhibitors With Benzoylhydrazide Scaffold That Selectively Inhibit Class I Histone Deacetylases

Tumor development is associated with genetic modification,including DNA methylation,and post transcriptional modification of histone acetylation,these modifications can regulate the DN A contractedness and chromosome structure without change the DNA sequence.Histone deacetylase(HDAC)is a class of proteases,which can remove the acetyl-base from the histone or other cellular proteins.They plays an important role in the regulation of chromosome structure modification and gene expression.According to the analysis of different HDAC structure and yeast HDAC homology,molecular weight,containing the catalytic structure,location in the cell,the HDAC proteins can be divided into four subtypes including class I,II,III,IV.In clinical cancer therapy,histone deacetylase inhibitors(HDAC i)are widely accepted in treatment.C lass I histone deacetylase is a traditional disease therapeutic targets.At present,these are a variety of small molecule HDAC inhibitors(HDAC i)with different chemical structure were found and researched,o f which there are many compounds in previous laboratory studies and clinical trials showed good antitumor activity to specific treatment specific cancers,such as cutaneous T cell lymphoma and the outer peripheral T cell lymphoma.At present more and more studies on HDAC i have been found,they can be divided into four categories,hydroxamic acids,amino benzamide compounds,cyclic peptide compounds and short chain fatty acid.Hydroxamic acids.Hydroxamic acids is most widely developed and has entered into the preclinical and clinical studies,which including FDA approved Vorinostat and Belinostat.Entinostat has benzamide structure,and is used in the treatment of ER+ breast cancer.C yclic peptide HDAC i such as romidepsin,which was approved by the FDA in 2009 for the treatment of T cell lymphoma.Even so,the clinical HDAC inhibitors have limited specificity on HDAC subtype,or with unpredictable resistant or side effects.Therefore,it is needed to develop a new chemical structure to make up for these shortcomings.Through a high-throughput screening(HTS)way,we found a class of compounds having selected inhibition of class I HDAC,including HDAC1,HDAC2 and HDAC3.This novel group of histone deacetylase inhibitor with benzoylhydrazine scaffold structure that have not been previously reported,with selectively inhib i-tion on classes I histone deacetylase.Our previous SAR analysis confirmed that this kind of scaffold structure has a center of the-C(O)-NH-NH-groups,on both sides of the phenyl and short chain fatty composition structure.Center groups may provide hydrogen bonds and weak Zn2+ chelating activity,and the both sides hydrophobic groups specifically interact with HDAC catalytic center of the hydrophobic pocket.Importantly,HDAC inhibitors with weaker Zn2+ chelation may reduce the non-target protein binding activity.The novel group of HDAC i can competitively form complex with HDAC meanwhile have a fast-on/slow-off characteristics.In these compounds,we choose the most representative compound of UF010,which can inhibit tumor cell growth through specific inhibition of class I histone deacetylase.This is because of changes in the global level of protein acetylation and gene expression,which result in tumor suppressor pathway activation and inhib ition of many oncogenic pathway.Based on the cellular experimens,the inhibition of UF010 on histones and p53 deacetylation levels is higher than amino benzamide compounds,but weaker than hydroxamic acid compounds with strong chelation warhead of Zn2+.In addition,UF010 can regulate the expression of genes widely,as to active the antitumor pathway.NUPR1 may play an important role in the occu rrence and development of tumor.In addition,the ERK1/2 pathway will be also activated.Activation of these pathways may be resistant to UF010.It will likely be able to improve the a nti-tumor effect of UF010 combined with other drugs can inhibit the survival pathway.From the clinical toxicity experiments of HDAC inhibitors,the general reduced toxicity of HDAC inhibitors is better for cancer treatment.In addition,low toxicity compounds is more suitable for treatment of neurodegenerative diseases and metabolic diseases,because the treatment of these diseases to avoid cell death.In preliminary experiments,we demonstrate the UF010 in cell culture medium half-life can reach 15.8 hours,which is similar with metabolism of romidepsin.Further studies can focus to analyze UF010 and its analogues pharmacokinetic properties.Therefore,screening the compounds have same subunit with UF010 with growth inhib itory activity to tumor cells,provides a new direction for the developing of drugs for clinical treatment.This novel HDAC inhibitors can be a powerful tool to study the biological effect of HDAC in human disease,and has a wide prospect of clinical application.