title: Comprehensive comparison of the cytotoxic activities of onconase and bovine seminal ribonuclease.
abstract: Onconase (ONC) and bovine seminal ribonuclease (BS-RNase) are homologs of bovine pancreatic ribonuclease (RNase A). Unlike RNase A, ONC and BS-RNase can evade the cytosolic ribonuclease inhibitor protein and are potent cytotoxins. Here, the endogenous cytotoxic activities of ONC and BS-RNase are compared in a wide variety of assays. Injections of ONC into one or both testes of mice and rats evokes a stronger aspermatogenic activity than does the injection of BS-RNase. Epididymides exposed to ONC lose mass and all sperm. Testicular tissue is gradually colonized by immunite and fibrocytic cells. Yet, Leydig cells are always present and functional in the ligamented parts of testicles injected with ONC or BS-RNase. ONC is likewise more toxic to mouse embryos than is BS-RNase, both in vitro and in vivo. The antiproliferative effect of ONC on human tumor cell line ML-2 and lymphocytes in a mixed lymphocyte culture is also more pronounced than is that of BS-RNase. The number of granulocyte-macrophage colony-forming units is repressed almost completely by ONC, whereas a five-fold higher dose of BS-RNase does not cause substantial inhibition. In mice, ONC is less immunogenic than BS-RNase but more immunogenic than RNase A. Together, these data indicate that ONC is a pluripotent cytotoxin, and serves as the benchmark with which to gauge the cytotoxicity of other ribonucleases.
authors.affiliation: Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Libechov 277 21, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Matousek
authors.forename: Josef
authors.initials: J
authors.lastname: Soucek
authors.forename: Tomás
authors.initials: T
authors.lastname: Slavík
authors.forename: Milan
authors.initials: M
authors.lastname: Tománek
authors.forename: J Eugene
authors.initials: JE
authors.lastname: Lee
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Raines
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D000970:Antineoplastic Agents / Q000737:chemistry / Q000633:toxicity*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D005314:Embryonic and Fetal Development / Q000187:drug effects; D004722:Endoribonucleases / Q000737:chemistry / Q000633:toxicity*; D004822:Epididymis / Q000187:drug effects; D006801:Humans; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D051379:Mice; D008958:Models, Molecular; D051381:Rats; D012260:Ribonucleases / Q000737:chemistry / Q000633:toxicity*; D012671:Seminiferous Tubules / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects; D013093:Spermatogonia / Q000187:drug effects; D013234:Stem Cells / Q000187:drug effects; D013737:Testis / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D004722:Endoribonucleases; D012260:Ribonucleases; C032523:ribonuclease SPL; C058703:ranpirnase