title: Establishment of a dipeptidyl peptidases (DPP) 8/9 expressing cell model for evaluating the selectivity of DPP4 inhibitors.
abstract: BACKGROUND
  Dipeptidyl peptidases (DPPs) 8 and 9 are homologous, cytoplasmic postproline-cutting enzymes, which have similar enzymatic activity and preferred substrates as DPP4. DPP4 is a well-known target for treating diabetes mellitus. With the increased concern of non-selectivity and toxicities caused by DPP4 inhibitors, it is essential to establish new ex vivo system to investigate DPP4 inhibitors' effect on DPP8 and DPP9.
  
  
  METHODS
  Here we reported a newly established cell model system by cloning and transfecting human DPP8/9 genes into HEK 293 cells. We then used this model to evaluate the clinically applied DPP4 inhibitors' effect on DPP8/9, by direct enzymatic activity assay. Given the difference of cellular locations between DPP4 and DPP8/9, we also evaluated the influence of these drugs on intracellular DPP8/9 activity and cell viability by extracellular treatment with different inhibitors.
  
  
  RESULTS
  Direct enzymatic activity assay revealed significant and concentration-dependent inhibition effect of vildagliptin, saxagliptin on DPP8/9. Extracellular incubation of DPP8/9 over expressed cells with sitagliptin, vildagliptin, saxagliptin, alogliptin and linagliptin, showed only mild inhibition on DPP8/9. Moreover, all of these drugs showed no significant influence on cell viability.
  
  
  CONCLUSIONS
  Our results demonstrated that the DPP8/9 over-expressing cell model system is a very useful and promising system for investigating the selectivity and associated toxicity of DPP4 inhibitors on DPP8/9.
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Huan
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China.
authors.forename: Jing-long
authors.initials: JL
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China. Electronic address: shenzhf@imm.ac.cn.
authors.forename: Zhu-fang
authors.initials: ZF
authors.lastname: Shen
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004150:Dipeptidases / Q000235:genetics* / Q000378:metabolism; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D008954:Models, Biological; D009570:Nitriles / Q000737:chemistry / Q000494:pharmacology*; D011759:Pyrrolidines / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D000077597:Vildagliptin
chemical_list: D004151:Dipeptides; D004791:Enzyme Inhibitors; D009570:Nitriles; D011759:Pyrrolidines; D011994:Recombinant Proteins; C502994:saxagliptin; D004150:Dipeptidases; C471241:DPP9 protein, human; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C042807:DPP4 protein, human; C487997:DPP8 protein, human; D018819:Dipeptidyl Peptidase 4; D000077597:Vildagliptin; D000218:Adamantane
keywords: cell model; dipeptidyl peptidases; inhibitors; selectivity