title: Comparison of the activity levels and localization of dipeptidyl peptidase IV in normal and tumor human lung cells.
abstract: Dipeptidyl peptidase IV (DPPIV) was studied in three human lung cells - P (fetal lung-derived cells), A549 (lung adenocarcinoma) and SK-MES-1 (squamous cell carcinoma) using a fluorescent cytochemical procedure developed on the basis of the substrate 4-(glycyl-L-prolyl hydrazido)-N-hexyl-1,8-naphthalimide. The observed differences in the enzyme expression were confirmed by measuring the enzyme hydrolysis of glycyl-L-prolyl-para-nitroanilide. The surface and total dipeptidyl peptidase activities of P cells were correspondingly 7-8 and 3-10 times higher than those of SK-MES-1 and A549 cells. The ratio surface per total activity showed that in P (95%) and A549 (93%) cells the enzyme is associated with the plasmalemma while in SK-MES-1 cells (35%) it is bound to intracellular membranes. In order to compare the results from cell cultures with those in human tumor, the enzyme activity was investigated in cryo-sections of three cases of diagnosed squamous lung carcinoma. DPPIV activity was restricted to the connective tissue stroma surrounding the DPPIV-negative tumor foci.
authors.affiliation: Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Sofia, Bulgaria. mashadim@abv.bg
authors.forename: Mashenka
authors.initials: M
authors.lastname: Dimitrova
authors.forename: Ivaylo
authors.initials: I
authors.lastname: Ivanov
authors.forename: Ralitza
authors.initials: R
authors.lastname: Todorova
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Stefanova
authors.forename: Veselina
authors.initials: V
authors.lastname: Moskova-Doumanova
authors.forename: Tanya
authors.initials: T
authors.lastname: Topouzova-Hristova
authors.forename: Veselina
authors.initials: V
authors.lastname: Saynova
authors.forename: Elena
authors.initials: E
authors.lastname: Stephanova
mesh_terms: D001562:Benzimidazoles / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000473:pathology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000032:analysis / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008175:Lung Neoplasms / Q000201:enzymology / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D001562:Benzimidazoles; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D008565:Membrane Proteins; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4; C017807:bisbenzimide ethoxide trihydrochloride