title: Extracellular signal-regulated kinase 1/2 and protein phosphatase 2A are involved in the antiproliferative activity of conjugated linoleic acid in MCF-7 cells.
abstract: Conjugated linoleic acid (CLA) has protective properties in breast cancer. Here, we studied the mechanisms underlying the effects of CLA on MCF-7 breast cancer cell proliferation, especially in correlation with the involvement of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and protein phosphatase 2A (PP2A). CLA inhibits MCF-7 cell growth in a concentration- and time-dependent manner, without triggering apoptosis. In assessing expression levels of proteins that play obligatory roles in the ERK cascade, we evidenced that CLA down-regulated Raf-1 and decreased levels of phospho-ERK1/2, as well as c-myc expression. Increase in PP2A expression rates were additionally observed after CLA treatment of MCF-7 cells. The above effects, as well as CLA-induced inhibition of cell growth, were reversed by okadaic acid, a specific inhibitor of PP2A. Thus, PP2A likely participates in deactivation of ERK1/2, and its up-regulation may represent a novel mechanism for CLA-induced inhibition of cell proliferation.
authors.affiliation: Department of Experimental Medicine and Oncology, University of Turin, C. Raffaello 30, 10125, Turin, Italy. antonella.miglietta@unito.it
authors.forename: Antonella
authors.initials: A
authors.lastname: Miglietta
authors.forename: Francesca
authors.initials: F
authors.lastname: Bozzo
authors.forename: Ludovica
authors.initials: L
authors.lastname: Gabriel
authors.forename: Claudia
authors.initials: C
authors.lastname: Bocca
authors.forename: Rosa Angela
authors.initials: RA
authors.lastname: Canuto
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000517:prevention & control; D002273:Carcinogens / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005260:Female; D006801:Humans; D044243:Linoleic Acids, Conjugated / Q000378:metabolism / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D054648:Protein Phosphatase 2; D015854:Up-Regulation / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D002273:Carcinogens; D003470:Culture Media; D004791:Enzyme Inhibitors; D044243:Linoleic Acids, Conjugated; D019319:Okadaic Acid; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2