t-0070907 and 2-2-bis(4-glycidyloxyphenyl)propane

Embryonic stem (ES) cells are genetically normal, pluripotent cells, capable of self-renewal and multi-lineage differentiation. Leukemia inhibitory factor (LIF) is a growth factor that can maintain the pluripotency of mouse ES cells in culture. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor transcription factors that regulate growth and differentiation of many cell types. We have shown earlier that 15-Deoxy-(12,14)-Prostaglandin J2 (15d-PGJ2), a natural ligand for PPARgamma, inhibits LIF-induced proliferation of mouse ES cells in culture. In this study we demonstrate that the PPARgamma antagonist Bisphenol A diglycidyl ether (BADGE) and 2-Chloro-5-nitro-N-(4-pyridyl)benzamide (T0070907) reverse the inhibition of ES cell proliferation by PPARgamma agonists. Stable transfection of ES cells with a dominant negative PPARgamma1 mutant also reduced the inhibition of proliferation by PPARgamma agonists. While 15d-PGJ2 and ciglitazone-induced growth-arrest in ES cells by blocking LIF signaling, PPARgamma antagonists and dominant negative PPARgamma1 mutant reversed proliferation by restoring LIF-induced Tyk2-Stat3 signaling. These results suggest that PPARgamma regulates LIF-induced growth and self-renewal of mouse ES cells through Tyk2-Stat3 pathway.

Topics: Animals; Antineoplastic Agents; Benzamides; Benzhydryl Compounds; Cell Differentiation; Embryonic Stem Cells; Epoxy Compounds; Leukemia Inhibitory Factor; Mice; Phosphorylation; PPAR gamma; Prostaglandin D2; Pyridines; Signal Transduction; STAT3 Transcription Factor; TYK2 Kinase

The nuclear transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma) has been identified as an important therapeutic target in murine models of colorectal cancer (CRC). To examine whether PPARgamma inhibition has therapeutic effects in late-stage CRC, the effects of PPARgamma inhibitors on CRC cell survival were examined in CRC cell lines and a murine CRC model. Low doses (0.1-1 microM) of PPARgamma inhibitors (T0070907, GW9662 and BADGE) did not affect cell survival, while higher doses (10-100 microM) of all 3 PPARgamma inhibitors caused caspase-dependent apoptosis in HT-29, Caco-2 and LoVo CRC cell lines. Apoptosis was preceded by altered cell morphology, and this alteration was not prevented by caspase inhibition. PPARgamma inhibitors also caused dual G and M cell cycle arrest, which was not required for apoptosis or for morphologic alterations. Furthermore, PPARgamma inhibitors triggered loss of the microtubule network. Notably, unlike other standard antimicrotubule agents, PPARgamma inhibitors caused microtubule loss by regulating tubulin post-transcriptionally rather than by altering microtubule polymerization or dynamics. Proteasome inhibition by epoxomicin was unable to prevent tubulin loss. siRNA-mediated reduction of PPARgamma and PPARdelta proteins did not replicate the effects of PPARgamma inhibitors or interfere with the inhibitors' effects on apoptosis, cell cycle or tubulin. PPARgamma inhibitors also reduced CRC cell migration and invasion in assays in vitro and reduced both the number and size of metastases in a HT-29/SCID xenograft metastatic model of CRC. These results suggest that PPARgamma inhibitors are a novel potential antimicrotubule therapy for CRC that acts by directly reducing microtubule precursors.

Topics: Amino Acid Chloromethyl Ketones; Anilides; Animals; Apoptosis; Benzamides; Benzhydryl Compounds; Caco-2 Cells; Caspase Inhibitors; Caspases; Cell Cycle; Cell Line, Tumor; Cell Movement; Cell Shape; Colorectal Neoplasms; Dose-Response Relationship, Drug; Epoxy Compounds; HT29 Cells; Humans; Male; Mice; Mice, SCID; Neoplasm Metastasis; PPAR delta; PPAR gamma; Proteasome Endopeptidase Complex; Pyridines; Tubulin; Xenograft Model Antitumor Assays

Peroxisome proliferator-activated receptor-gamma is a nuclear receptor transcription factor that regulates cell growth, differentiation and homeostasis. PPARgamma agonists have been used to treat obesity, diabetes, cancer and inflammation and recent studies have shown the protective effects of PPARgamma agonists on experimental allergic encephalomyelitis (EAE), a Th1 cell-mediated autoimmune disease model of multiple sclerosis (MS). Our studies have further demonstrated that the PPARgamma agonists, 15d-PGJ2 and Ciglitazone, inhibit EAE through blocking IL-12 signaling leading to Th1 differentiation and the PPARgamma deficient heterozygous mice (PPARgamma+/-) or those treated with PPARgamma antagonists develop an exacerbated EAE in association with an augmented Th1 response. In this study, we show that the PPARgamma antagonists, Bisphenol A diglycidyl ether (BADGE) and 2-chloro-5-nitro-N-(4-pyridyl)benzamide (T0070907), reverse the inhibition of EAE by the PPARgamma agonists, Ciglitazone and 15-Deoxy-Delta(12,14)-Prostaglandin J2, in C57BL/6 wild-type and PPARgamma+/- mice. The reversal of EAE by BADGE and T0070907 was associated with restoration of neural antigen-induced T cell proliferation, IFNgamma production and Th1 differentiation inhibited by Ciglitazone and 15d-PGJ2. These results suggest that Ciglitazone and 15d-PGJ2 ameliorate EAE through PPARgamma-dependent mechanisms and further confirm a physiological role for PPARgamma in the regulation of CNS inflammation and demyelination in EAE.

Topics: Animals; Antigens; Benzamides; Benzhydryl Compounds; Cell Differentiation; Cell Proliferation; Demyelinating Diseases; Encephalomyelitis, Autoimmune, Experimental; Enzyme-Linked Immunosorbent Assay; Epoxy Compounds; Female; Immunologic Factors; Inflammation; Interferon-gamma; Mice; Mice, Inbred C57BL; Myelin Proteins; Myelin-Associated Glycoprotein; Myelin-Oligodendrocyte Glycoprotein; PPAR gamma; Prostaglandin D2; Pyridines; Th1 Cells; Thiazolidinediones

Peroxisome proliferator-activated receptor-gamma is a nuclear receptor transcription factor that regulates cell growth, differentiation and homeostasis. PPARgamma agonists have been used in the treatment of obesity, diabetes, cancer and inflammation. We and others have shown recently that PPARgamma agonists ameliorate experimental allergic encephalomyelitis (EAE), a Th1 cell-mediated autoimmune disease model of multiple sclerosis (MS). We have further shown that PPARgamma agonists inhibit EAE through blocking IL-12 signaling leading to Th1 differentiation and the PPARgamma-deficient heterozygous mice (PPARgamma(+/-)) develop an exacerbated EAE. In this study, we show that in vivo treatment (i.p.) with 100 mug PPARgamma antagonists, Bisphenol A diglycidyl ether (BADGE) or 2-Chloro-5-nitro-N-(4-pyridyl)benzamide (T0070907), on every other day from day 0 to 30, increased the severity and duration of EAE in C57BL/6 wild-type and PPARgamma(+/-) mice. The exacerbation of EAE by PPARgamma antagonists associates with an augmented neural antigen-induced T cell proliferation, IFNgamma production or Th1 differentiation. These results further suggest that PPARgamma is a critical physiological regulator of CNS inflammation and demyelination in EAE.

Topics: Animals; Benzamides; Benzhydryl Compounds; Cell Proliferation; Demyelinating Diseases; Dose-Response Relationship, Immunologic; Drug Administration Schedule; Drug Interactions; Encephalomyelitis, Autoimmune, Experimental; Enzyme-Linked Immunosorbent Assay; Epoxy Compounds; Female; Glycoproteins; Inflammation; Interferon-gamma; Mice; Mice, Inbred C57BL; Mice, Knockout; Myelin-Oligodendrocyte Glycoprotein; Peptide Fragments; PPAR gamma; Pyridines; Th1 Cells; Thymidine; Time Factors; Tritium