title: 2-Cyano-3,12-dioxoolean-1,9-dien-28-oic acid and related compounds inhibit growth of colon cancer cells through peroxisome proliferator-activated receptor gamma-dependent and -independent pathways.
abstract: 2-Cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and the corresponding methyl (CDDO-Me) and imidazole (CDDO-Im) esters induce peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent transactivation in SW-480 colon cancer cells, and these responses were inhibited by small inhibitory RNA for PPARgamma. Moreover, in a mammalian two-hybrid assay using the PPARgamma(2)-VP16 fusion plasmid and GAL4-coactivator/corepressor chimeras and a construct (pGAL4) containing five tandem GAL4 response elements, CDDO, CDDO-Me, and CDDO-IM induce transactivation and PPARgamma interaction with multiple coactivators. A major difference among the three PPARgamma agonists was the higher activity of CDDO-Im to induce PPARgamma interactions with the corepressor SMRT. CDDO, CDDO-Me, and CDDO-Im inhibited SW-480, HCT-116, and HT-29 colon cancer cell proliferation at low concentrations and induced cell death at higher concentrations. Growth inhibition at lower concentrations correlated with induction of the tumor suppressor gene caveolin-1 which is known to inhibit colon cancer cell growth. Induction of caveolin-1 by CDDO, CDDO-Me, and CDDO-Im was inhibited by the PPARgamma antagonist N-(4'-aminopyridyl-2-chloro-5-nitrobenzamide (T007), whereas higher doses induced apoptosis [poly(ADP-ribose) polymerase cleavage], which was not inhibited by T007. These results illustrate that CDDO-, CDDO-Me, and CDDO-Im induce both PPARgamma-dependent and -independent responses in colon cancer cells, and activation of these pathways are separable and concentration-dependent for all three compounds.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-4466, USA.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Chintharlapalli
authors.forename: Sabitha
authors.initials: S
authors.lastname: Papineni
authors.forename: Marina
authors.initials: M
authors.lastname: Konopleva
authors.forename: Michael
authors.initials: M
authors.lastname: Andreef
authors.forename: Ismael
authors.initials: I
authors.lastname: Samudio
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D047495:PPAR gamma / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: C116817:2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid; D000970:Antineoplastic Agents; D006131:Growth Inhibitors; D047495:PPAR gamma; D009828:Oleanolic Acid