9-deoxy-delta-9-prostaglandin-d2 and Breast-Neoplasms

1,1-Bis(3'-indolyl)-1-(p-trifluoromethylphenyl)methane (DIM-C-pPhCF(3)) and several p-substituted phenyl analogues have been investigated as a new class of peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. Structure-activity studies in PPARgamma-dependent transactivation assays in MCF-7 breast cancer cells show that 5-20 micro M concentrations of compounds containing p-trifluoromethyl, t-butyl, cyano, dimethylamino, and phenyl groups were active, whereas p-methyl, hydrogen, methoxy, hydroxyl, or halogen groups were inactive as PPARgamma agonists. Induction of PPARgamma-dependent transactivation by 15-deoxy-Delta12,14-prostaglandin J2 (PGJ2) and DIM-C-pPhCF(3) was inhibited in MCF-7 cells cotreated with the PPARgamma-specific antagonist N-(4'-aminopyridyl)-2-chloro-5-nitrobenzamide. In mammalian two-hybrid assays, DIM-C-pPhCF(3) and PGJ2 (5-20 micro M) induced interactions of PPARgamma with steroid receptor coactivator (SRC) 1, SRC2 (TIFII), and thyroid hormone receptor-associated protein 220 but not with SRC3 (AIB1). In contrast, DIM-C-pPhCF(3), but not PGJ2, induced interactions of PPARgamma with PPARgamma coactivator-1. C-substituted diindolylmethanes inhibit carcinogen-induced rat mammary tumor growth, induce differentiation in 3T3-L1 preadipocytes, inhibit MCF-7 cell growth and G(0)/G(1)-S phase progression, induce apoptosis, and down-regulate cyclin D1 protein and estrogen receptor alpha in breast cancer cells. These compounds are a novel class of synthetic PPARgamma agonists that induce responses in MCF-7 cells similar to those observed for PGJ2.

Topics: 3T3-L1 Cells; Adipocytes; Animals; Apoptosis; Breast Neoplasms; Carcinogens; Cell Cycle; Cell Differentiation; Cell Division; Cell Line, Tumor; Cell Separation; Cloning, Molecular; Cyclin D1; Dose-Response Relationship, Drug; Down-Regulation; Estrogen Receptor alpha; Female; Flow Cytometry; G1 Phase; Humans; Indoles; Ligands; Luciferases; Methane; Mice; Plasmids; Prostaglandin D2; Protein Structure, Tertiary; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Receptors, Estrogen; Resting Phase, Cell Cycle; Structure-Activity Relationship; Transcription Factors; Transcriptional Activation; Transfection; Two-Hybrid System Techniques

Treatment of MCF-7 cells with the peroxisome proliferator-activated receptor (PPAR) gamma agonists ciglitazone or 15-deoxy-Delta 12,14-prostaglandin J2 resulted in a concentration- and time-dependent decrease of cyclin D1 and estrogen receptor (ER) alpha proteins, and this was accompanied by decreased cell proliferation and G(1)-G(0)-->S-phase progression. Down-regulation of cyclin D1 and ER alpha by PPARgamma agonists was inhibited in cells cotreated with the proteasome inhibitors MG132 and PSII, but not in cells cotreated with the protease inhibitors calpain II and calpeptin. Moreover, after treatment of MCF-7 cells with 15-deoxy-Delta 12,14-prostaglandin J2 and immunoprecipitation with cyclin D1 or ER alpha antibodies, there was enhanced formation of ubiquitinated cyclin D1 and ER alpha bands. Thus, PPARgamma-induced inhibition of breast cancer cell growth is due, in part, to proteasome-dependent degradation of cyclin D1 (and ER alpha), and this pathway may be important for other cancer cell lines.

Topics: Breast Neoplasms; Cell Division; Cyclin D1; Cysteine Endopeptidases; Down-Regulation; Estrogen Receptor alpha; G1 Phase; Humans; Multienzyme Complexes; Prostaglandin D2; Proteasome Endopeptidase Complex; Receptors, Cytoplasmic and Nuclear; Receptors, Estrogen; RNA, Messenger; S Phase; Thiazoles; Thiazolidinediones; Transcription Factors; Transcription, Genetic; Tumor Cells, Cultured; Ubiquitin