title: Constitutive over expression of serine/threonine protein phosphatase 5 (PP5) augments estrogen-dependent tumor growth in mice.
abstract: Serine/threonine protein phosphatase 5 (PP5) appears to play an underappreciated role in the regulation of cellular proliferation. In estrogen-responsive cells, PP5 expression is stimulated by 17 beta-estradiol, and in a variety of p53 wild-type tumor cells the suppression of PP5 expression with ISIS 15534 inhibits growth. To further explore the relationship between PP5 and the development of human cancer, here we tested the effect of elevated PP5 expression on tumor growth using a mouse xenograph model and a stable MCF-7 cell line in which the expression of wild-type PP5 was placed under the control of tetracycline-off regulated transactivator and operator plasmids. In the xenograph model a modest two fold increase in PP5 protein levels significantly enhanced the growth rate of estrogen-dependent tumors, suggesting PP5 plays a positive role in tumor development.
authors.affiliation: Department of Biochemistry and Molecular Biology, MSB 2362, 307 University Blvd, University of South Alabama, Mobile, Alabama 36688 USA.
authors.forename: Teresa
authors.initials: T
authors.lastname: Golden
authors.forename: Ileana V
authors.initials: IV
authors.lastname: Aragon
authors.forename: Guofei
authors.initials: G
authors.lastname: Zhou
authors.forename: Scott R
authors.initials: SR
authors.lastname: Cooper
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Dean
authors.forename: Richard E
authors.initials: RE
authors.lastname: Honkanen
mesh_terms: D000818:Animals; D018567:Breast Neoplasms, Male / Q000201:enzymology* / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000378:metabolism*; D009875:Operator Regions, Genetic; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D015534:Trans-Activators; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D009687:Nuclear Proteins; D011500:Protein Synthesis Inhibitors; D015534:Trans-Activators; D004958:Estradiol; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5; D013752:Tetracycline