title: Changes in O-Linked N-Acetylglucosamine (O-GlcNAc) Homeostasis Activate the p53 Pathway in Ovarian Cancer Cells.
abstract: O-GlcNAcylation is a dynamic post-translational modification consisting of the addition of a single N-acetylglucosamine sugar to serine and threonine residues in proteins by the enzyme O-linked β-N-acetylglucosamine transferase (OGT), whereas the enzyme O-GlcNAcase (OGA) removes the modification. In cancer, tumor samples present with altered O-GlcNAcylation; however, changes in O-GlcNAcylation are not consistent between tumor types. Interestingly, the tumor suppressor p53 is modified by O-GlcNAc, and most solid tumors contain mutations in p53 leading to the loss of p53 function. Because ovarian cancer has a high frequency of p53 mutation rates, we decided to investigate the relationship between O-GlcNAcylation and p53 function in ovarian cancer. We measured a significant decrease in O-GlcNAcylation of tumor tissue in an ovarian tumor microarray. Furthermore, O-GlcNAcylation was increased, and OGA protein and mRNA levels were decreased in ovarian tumor cell lines not expressing the protein p53. Treatment with the OGA inhibitor Thiamet-G (TMG), silencing of OGA, or overexpression of OGA and OGT led to p53 stabilization, increased nuclear localization, and increased protein and mRNA levels of p53 target genes. These data suggest that changes in O-GlcNAc homeostasis activate the p53 pathway. Combination treatment of the chemotherapeutic cisplatin with TMG decreased tumor cell growth and enhanced cell cycle arrest without impairing cytotoxicity. The effects of TMG on tumor cell growth were partially dependent on wild type p53 activation. In conclusion, changes in O-GlcNAc homeostasis activate the wild type p53 pathway in ovarian cancer cells, and OGA inhibition has the potential as an adjuvant treatment for ovarian carcinoma.
authors.affiliation: From the Laboratório de Glicobiologia Estrutural e Funcional, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, 21941-902RJ, Brazil.
authors.forename: Rafaela Muniz
authors.initials: RM
authors.lastname: de Queiroz
authors.affiliation: Division of Hematology/Oncology, Department of Pathology, University of Kansas Medical Center, Kansas City, Kansas 66160.
authors.forename: Rashna
authors.initials: R
authors.lastname: Madan
authors.affiliation: Cancer Biology and.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Chien
authors.affiliation: From the Laboratório de Glicobiologia Estrutural e Funcional, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, 21941-902RJ, Brazil, diaswb@biof.ufrj.br.
authors.forename: Wagner Barbosa
authors.initials: WB
authors.lastname: Dias
authors.affiliation: the Departments of Biochemistry and Molecular Biology and cslawson@kumc.edu.
authors.forename: Chad
authors.initials: C
authors.lastname: Slawson
mesh_terms: D000117:Acetylglucosamine / Q000235:genetics / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D020868:Gene Silencing; D006706:Homeostasis; D006801:Humans; D009154:Mutation; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011499:Protein Processing, Post-Translational; D055550:Protein Stability / Q000187:drug effects; D011714:Pyrans / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D013844:Thiazoles / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D001619:beta-N-Acetylhexosaminidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D011714:Pyrans; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C495901:TP53 protein, human; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; C572247:thiamet G; D017351:N-Acetylglucosaminyltransferases; C110628:hexosaminidase C; D001619:beta-N-Acetylhexosaminidases; D000117:Acetylglucosamine
keywords: O-GlcNAcase; O-linked N-acetylglucosamine (O-GlcNAc); O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT); cell growth; ovarian cancer; p53