cyclin-d1 and 2-4-thiazolidinedione

The effect of cell cycle synchronisation on glucose metabolism in cancer cells is not known. We assessed how cell cycle synchronisation by thiazolidinediones (TZDs) can affect glucose uptake by cancer cells and investigated the anti-cancer effect of combination therapy with TZDs and 2-deoxy-glucose (2-DG) in colon cancer cells and in mouse xenograft models. Troglitazone (58.1 ± 2.0 vs 48.6 ± 1.3%, p = 0.002) or pioglitazone (82.9 ± 1.9 vs 61.6 ± 3.4%, p < 0.001) induced cell cycle arrest in SW480 cells at G1 phase. Western blot analysis showed the degradation of cyclin D1 and CDK4, and an increase in the expression levels of p21 and p27 after TZDs treatment. Withdrawal of troglitazone treatment induced significant increase in cellular

Topics: Animals; Antineoplastic Agents; Cell Cycle Checkpoints; Colonic Neoplasms; Cyclin D1; Cyclin-Dependent Kinase 4; Deoxyglucose; Drug Synergism; Drug Therapy, Combination; Gene Expression; Glucose; Glucose Transporter Type 1; Humans; Mice; Thiazolidinediones; Tumor Cells, Cultured

Several peroxisome proliferator-activated receptor gamma (PPARgamma) agonists of the thiazolidinedione class inhibit vascular smooth muscle cell proliferation. It is not known whether the antiproliferative activity of PPARgamma agonists is limited to the thiazolidinedione class and/or is directly mediated through PPARgamma-dependent transactivation of target genes. We report here that a novel non-thiazolidinedione partial PPARgamma agonist (nTZDpa) attenuates rat aortic vascular smooth muscle cell proliferation. In a transfection assay for PPARgamma transcriptional activation, the non-thiazolidinedione partial PPARgamma agonist elicited approximately 25% of the maximal efficacy of the full PPARgamma agonist rosiglitazone. In the presence of the non-thiazolidinedione partial PPARgamma agonist, the transcriptional activity of the full agonist, rosiglitazone, was blunted, indicating that the non-thiazolidinedione partial PPARgamma agonist inhibits rosiglitazone-induced PPARgamma activity. The non-thiazolidinedione partial PPARgamma agonist (0.1-10 microM) inhibited vascular smooth muscle cell growth which was accompanied by an inhibition of retinoblastoma protein phosphorylation. Mitogen-induced downregulation of the cyclin-dependent kinase (CDK) inhibitor p27(kip1), and induction of the G1 cyclins cyclin D1, cyclin A, and cyclin E were also attenuated by the non-thiazolidinedione partial PPARgamma agonist. Maximal antiproliferative activity of the non-thiazolidinedione partial PPARgamma agonist required functional PPARgamma as adenovirus-mediated overexpression of a dominant-negative PPARgamma mutant partially reversed its inhibition of vascular smooth muscle cell growth. In contrast, overexpression of dominant-negative PPARgamma did not reverse the inhibitory effect of the non-thiazolidinedione partial PPARgamma agonist on cyclin D1. As the full PPARgamma agonist rosiglitazone exhibited no effect on cyclin D1, inhibition of that G1 cyclin by the non-thiazolidinedione partial PPARgamma agonist likely occurred through a PPARgamma-independent mechanism. These data demonstrate that a non-thiazolidinedione partial PPARgamma agonist may constitute a novel therapeutic for proliferative vascular diseases and could provide additional evidence for the important role of PPARgamma in regulating vascular smooth muscle cell proliferation.

Topics: Adenoviridae; Animals; Cell Cycle Proteins; Cell Division; Cells, Cultured; Cyclin A; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase Inhibitor p27; Down-Regulation; G1 Phase; Genetic Vectors; Inhibitory Concentration 50; Ligands; Luciferases; Mitogens; Muscle, Smooth, Vascular; Phosphorylation; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Recombinant Fusion Proteins; Retinoblastoma Protein; S Phase; Thiazoles; Thiazolidinediones; Transcription Factors; Transfection; Tumor Suppressor Proteins

Peroxisome proliferator-activated receptor gamma (PPARgamma) inhibits the growth of several types of cancer cells. However, the mechanisms by which this occurs are poorly understood. The goal of the present study was to investigate the effects of PPARgamma on mutated ras-induced cell growth, activation of transcription factors and expression of genes associated with cellular transformation in rat intestinal epithelial cells. A human PPARgamma cDNA was introduced to the activated H-ras-transfected IEC-6 cells (IECras) and 1 clone (IECrasPR82) that stably expresses both activated ras and PPARgamma was obtained. Thiazolidinedione derivatives such as troglitazone and rosiglitazone, selective ligands for PPARgamma, inhibited the cellular growth of IECrasPR82 cells in a time-dependent manner and induced G1 cell cycle arrest. Treatment with troglitazone (20 microM) decreased the expression of cyclin D1, heparin-binding epidermal growth factor-like growth factor (HB-EGF) and amphiregulin and suppressed the promoter activities of cyclin D1 and HB-EGF. Furthermore, a luciferase assay and an electrophoretic mobility shift assay showed that thiazolidinedione derivatives suppressed the transcriptional activities of AP-1 and Ets, both of which play crucial roles in the expression of cyclin D1 and HB-EGF. These findings suggest that reduction of EGF-like growth factors and cyclin D1 through the suppression of AP-1 and Ets may be 1 mechanism whereby PPARgamma inhibits their growth.

Topics: Animals; Blotting, Northern; Blotting, Western; Cell Division; Cell Line; Cell Line, Transformed; Cell Nucleus; Chromans; Cyclin D1; DNA, Complementary; Dose-Response Relationship, Drug; Epidermal Growth Factor; Epithelial Cells; Flow Cytometry; Humans; Hypoglycemic Agents; Intestines; Ligands; Luciferases; Plasmids; Promoter Regions, Genetic; ras Proteins; Rats; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Rosiglitazone; Thiazoles; Thiazolidinediones; Time Factors; Transcription Factor AP-1; Transcription Factors; Transcription, Genetic; Transcriptional Activation; Transfection; Troglitazone

The present study examined the expression and role of the thiazolidinedione (TZD)-activated transcription factor, peroxisome proliferator-activated receptor gamma (PPARgamma), in human bladder cancers. In situ hybridization shows that PPARgamma mRNA is highly expressed in all human transitional epithelial cell cancers (TCCa's) studied (n=11). PPARgamma was also expressed in five TCCa cell lines as determined by RNase protection assays and immunoblot. Retinoid X receptor alpha (RXRalpha), a 9-cis-retinoic acid stimulated (9-cis-RA) heterodimeric partner of PPARgamma, was also co-expressed in all TCCa tissues and cell lines. Treatment of the T24 bladder cancer cells with the TZD PPARgamma agonist troglitazone, dramatically inhibited 3H-thymidine incorporation and induced cell death. Addition of the RXRalpha ligands, 9-cis-RA or LG100268, sensitized T24 bladder cancer cells to the lethal effect of troglitazone and two other PPAR- activators, ciglitazone and 15-deoxy-delta(12,14)-PGJ2 (15dPGJ(2)). Troglitazone treatment increased expression of two cyclin-dependent kinase inhibitors, p21(WAF1/CIP1) and p16(INK4), and reduced cyclin D1 expression, consistent with G1 arrest. Troglitazone also induced an endogenous PPARgamma target gene in T24 cells, adipocyte-type fatty acid binding protein (A-FABP), the expression of which correlates with bladder cancer differentiation. In situ hybridization shows that A-FABP expression is localized to normal uroepithelial cells as well as some TCCa's. Taken together, these results demonstrate that PPARgamma is expressed in human TCCa where it may play a role in regulating TCCa differentiation and survival, thereby providing a potential target for therapy of uroepithelial cancers.

Topics: Alitretinoin; Antineoplastic Agents; Apoptosis; Carcinoma, Transitional Cell; Carrier Proteins; Cell Death; Chromans; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA; DNA, Complementary; Dose-Response Relationship, Drug; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; G1 Phase; Humans; Immunoblotting; In Situ Hybridization; Ligands; Luciferases; Myelin P2 Protein; Neoplasm Proteins; Nicotinic Acids; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Retinoid X Receptors; Ribonucleases; Tetrahydronaphthalenes; Thiazoles; Thiazolidinediones; Transcription Factors; Transcriptional Activation; Transfection; Tretinoin; Troglitazone; Tumor Cells, Cultured; Tumor Suppressor Proteins; Urinary Bladder Neoplasms