Comparison of the activity levels and localization of dipeptidyl peptidase IV in normal and tumor human lung cells |
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Authors: | Dimitrova Mashenka Ivanov Ivaylo Todorova Ralitza Stefanova Nadezhda Moskova-Doumanova Veselina Topouzova-Hristova Tanya Saynova Veselina Stephanova Elena |
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Institution: | a Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria b Faculty of Biology, University of Sofia “St. Kl. Ohridsky”, 1164 Sofia, Bulgaria c Active Therapy Hospital “Doverie”, 1632 Sofia, Bulgaria |
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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. |
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Keywords: | Dipeptidyl peptidase IV Fluorogenic substrates Enzyme cytochemistry Lung cancer cells Squamous cell lung cancer |
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