title: Deregulation of cyclin E2 expression and associated kinase activity in primary breast tumors.
abstract: The increased expression of G(1) cyclins has been associated with the many types of human tumors. In primary solid tumors however, the expression and activity of cyclin E2, the newest member of the G(1) cyclin family, is largely unknown. In this study we have analysed the expression of the E-type cyclins in primary solid tumors from breast, lung, uterus, ovary, colon, and rectal tissues. Relative gene expression was analysed by quantitative real-time reverse transcription polymerase chain reaction (Taqman). The levels of cyclin E1 and cyclin E2 were significantly elevated (23 vs 38%, respectively) in primary breast tumor samples relative to normal breast tissue controls. We also observed an inverse correlation between the expression of cyclin E1/E2 and estrogen receptor in breast tumors. Our results demonstrate that the expression and associated catalytic activity for both cyclin E1 and cyclin E2 is elevated in primary breast tumors when compared to normal breast tissue. The increased level of cyclin E2 in breast tumors suggests that, similar to cyclin E1, it may contribute to the pathogenesis of breast cancer.
authors.affiliation: Department of Cancer Biology, Amgen Inc., Thousand Oaks, California, CA 91320, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Payton
authors.forename: Shelia
authors.initials: S
authors.lastname: Scully
authors.forename: Grace
authors.initials: G
authors.lastname: Chung
authors.forename: Steve
authors.initials: S
authors.lastname: Coats
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D015179:Colorectal Neoplasms; D019927:Cyclin E; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D016213:Cyclins / Q000235:genetics*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D005833:Genital Neoplasms, Female; D006801:Humans; D008175:Lung Neoplasms; D009928:Organ Specificity; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: C503688:CCNE2 protein, human; D019927:Cyclin E; D016213:Cyclins; D018844:Cyclin-Dependent Kinases