title: Bovine seminal ribonuclease is cytotoxic for both malignant and normal telomerase-positive cells.
abstract: Bovine seminal-ribonuclease (BS-RNase) is a member of the 'ribonucleases with special biological actions' family since it possesses specific anti-tumour, anti-spermatogenic and embryotoxic activities and exerts an immunosuppressive effect on T lymphocytes. In previous studies it was demonstrated that BS-RNase induced apoptosis in proliferating, malignant and normal cells and that telomerase activity loss also caused apoptotic death in neoplastic cells. Since an obvious relationship between cell proliferation and telomerase activity exists, the aim of this work was to study if the pro-apoptotic cytotoxic action exerted by BS-RNase on proliferating malignant cells (HT29) and proliferating normal cells (PHA-stimulated lymphocytes) could be linked to a possible BS-RNase effect on telomerase activity. In BS-RNase-treated HT29 cells (Na-butyrate-differentiated or not) and human lymphocytes (proliferating or not), we investigated cell vitality (MTT method) and morphology (SEM), BS-RNase localization (immunofluorescence), telomerase activity (TRAP-ELISA method), hTR mRNA expression (RT-PCR), and hTERT levels (western blot). While no BS-RNase effect was detectable on not proliferating cells, a clear relationship was noticed between the diminished number of vital elements of both proliferating cell populations after treatment (48 h and 72 h for HT29 and PHA-stimulated lymphocytes, respectively) with 50 microg/ml BS-RNase and the decrease of their telomerase activity. At the same time, we found that hTR levels, the RNA subunit of telomerase, in proliferation-inhibited BS-RNase-treated cells were diminished. Moreover, by immunofluorescence technique, we detected BS-RNase in the HT29 cell nucleolus after 3-h treatment. Therefore, as hTR has been recently proven to co-fractionate with nucleoli, we hypothesize that a BS-RNase direct action on the telomerase hTR subunit could be a possible mechanism of action by which BS-RNase exerts its pro-apoptotic effects only on proliferating cells.
authors.affiliation: Dipartimento di Chimica Biologica, Chimica Medica e Biologia Molecolare, Università degli Studi di Catania, Catania, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Viola
authors.forename: Massimo
authors.initials: M
authors.lastname: Libra
authors.forename: Daniela
authors.initials: D
authors.lastname: Callari
authors.forename: Fulvia
authors.initials: F
authors.lastname: Sinatra
authors.forename: Daniele
authors.initials: D
authors.lastname: Spada
authors.forename: Davide
authors.initials: D
authors.lastname: Noto
authors.forename: Giovanni
authors.initials: G
authors.lastname: Emmanuele
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Romano
authors.forename: Maurizio
authors.initials: M
authors.lastname: Averna
authors.forename: Franca Maria
authors.initials: FM
authors.lastname: Pezzino
authors.forename: Franca
authors.initials: F
authors.lastname: Stivala
authors.forename: Salvatore
authors.initials: S
authors.lastname: Travali
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D002417:Cattle; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D049109:Cell Proliferation; D015536:Down-Regulation; D004722:Endoribonucleases / Q000737:chemistry* / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000166:cytology; D008214:Lymphocytes / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000187:drug effects; D019098:Telomerase / Q000096:biosynthesis* / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D013778:Tetrazolium Salts; D013844:Thiazoles; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; D004722:Endoribonucleases; C032523:ribonuclease SPL; C022616:thiazolyl blue