Pioglitazone upregulates adiponectin receptor 2 in 3T3-L1 adipocytes

Terminal differentiation into adipocyte and growth inhibition by PPARγ activation in human A549 lung adenocarcinoma cells

The present study investigated the terminal differentiation capacity into adipocytes and subsequent growth inhibition in A549 cancer cells treated with pioglitazone (PGZ), a PPARγ activator. The rate of cell growth in A549 cells was significantly (P < .05) inhibited in concentrations above 10 μM PGZ while maintaining less cytotoxic effects in MRC-5 fibroblasts. Following 50 μM PGZ treatment, population doubling time (PDT) was significantly (P < .05) increased by inhibition of cell growth, as per increasing PGZ exposure time by up to 4 weeks. The adiposome-like vesicles were commonly observed in the PGZ-treated A549 cells, and the vesicles were highly stained with Oil-Red O solution. In addition, the cell size and expression of GLUT4 and PPARγ were significantly (P < .05) increased, as per increasing PGZ exposure time by up to 4 weeks. The significant (P < .05) down-regulation of telomerase activity and up-regulation of senescence-associated β-galactosidase (SA β-GAL) activity was displayed in the PGZ-treated A549 cells, as per increasing PGZ exposure time by up to 4 weeks. The G1 phase of the cell cycle was also significantly (P < .05) increased in the PGZ-treated A549 cells compared with untreated A549 cells. The present results have demonstrated that activation of PPARγ using PGZ induces cellular differentiation into adipocytes and inhibits cell growth in the A549 cancer cells. The terminal differentiation into adipocytes could offer potent chemotherapy in the cancer cells showing high glucose metabolism.

Development of Novel Glitazones as Antidiabetic Agents: Molecular Design, Synthesis, Evaluation of Glucose Uptake Activity and SAR Studies

Background:

Thiazolidinediones and its bioisostere, namely, rhodanines have become ubiquitous class of heterocyclic compounds in drug design and discovery. In the present study, as part of molecular design, a series of novel glitazones that are feasible to synthesize in our laboratory were subjected to docking studies against PPAR-γ receptor for their selection.

Methods and Results:

As part of the synthesis of selected twelve glitazones, the core moiety, pyridine incorporated rhodanine was synthesized via dithiocarbamate. Later, a series of glitazones were prepared via Knovenageal condensation. In silico docking studies were performed against PPARγ protein (2PRG). The titled compounds were investigated for their cytotoxic activity against 3T3-L1 cells to identify the cytotoxicity window of the glitazones. Further, within the cytotoxicity window, glitazones were screened for glucose uptake activity against L6 cells to assess their possible antidiabetic activity.

Conclusion:

Based on the glucose uptake results, structure activity relationships are drawn for the title compounds.

Rosiglitazone Enhances Browning Adipocytes in Association with MAPK and PI3-K Pathways During the Differentiation of Telomerase-Transformed Mesenchymal Stromal Cells into Adipocytes

Obesity is a major risk for diabetes. Brown adipose tissue (BAT) mediates production of heat while white adipose tissue (WAT) function in the storage of fat. Roles of BAT in the treatment of obesity and related disorders warrants more investigation. Peroxisome proliferator activator receptor gamma (PPAR-γ) is the master regulator of both BAT and WAT adipogenesis and has roles in glucose and fatty acid metabolism. Adipose tissue is the major expression site for PPAR-γ. In this study, the effects of rosiglitazone on the brown adipogenesis and the association of MAPK and PI3K pathways was investigated during the in vitro adipogenic differentiation of telomerase transformed mesenchymal stromal cells (iMSCs). Our data indicate that 2 µM rosiglitazone enhanced adipogenesis by over-expression of PPAR-γ and C/EBP-α. More specifically, brown adipogenesis was enhanced by the upregulation of EBF2 and UCP-1 and evidenced by multilocular fatty droplets morphology of the differentiated adipocytes. We also found that rosiglitazone significantly activated MAPK and PI3K pathways at the maturation stage of differentiation. Overall, the results indicate that rosiglitazone induced overexpression of PPAR-γ that in turn enhanced adipogenesis, particularly browning adipogenesis. This study reports the browning effects of rosiglitazone during the differentiation of iMSCs into adipocytes in association with the activation of MAPK and PI3K signaling pathways.

Effect of pioglitazone on cardiometabolic profiles and safety in patients with type 2 diabetes undergoing percutaneous coronary artery intervention: a prospective, multicenter, randomized trial

Pioglitazone has superior antiatherosclerotic effects compared with other classes of antidiabetic agents, and there is substantial evidence that pioglitazone improves cardiovascular (CV) outcomes. However, there is also a potential risk of worsening heart failure (HF). Therefore, it is clinically important to determine whether pioglitazone is safe in patients with type 2 diabetes mellitus (T2DM) who require treatment for secondary prevention of CV disease, since they have an intrinsically higher risk of HF. This prospective, multicenter, open-label, randomized study investigated the effects of pioglitazone on cardiometabolic profiles and CV safety in T2DM patients undergoing elective percutaneous coronary intervention (PCI) using bare-metal stents or first-generation drug-eluting stents. A total of 94 eligible patients were randomly assigned to either a pioglitazone or conventional (control) group, and pioglitazone was started the day before PCI. Cardiometabolic profiles were evaluated before PCI and at primary follow-up coronary angiography (5-8 months). Pioglitazone treatment reduced HbA1c levels to a similar degree as conventional treatment (pioglitazone group 6.5 to 6.0%, P < 0.01; control group 6.5 to 5.9%, P < 0.001), without body weight gain. Levels of high-molecular weight adiponectin increased more in the pioglitazone group than the control group (P < 0.001), and the changes were irrespective of baseline glycemic control. Furthermore, pioglitazone significantly reduced plasma levels of natriuretic peptides and preserved cardiac systolic and diastolic function (assessed by echocardiography) without incident hospitalization for worsening HF. The incidence of clinical adverse events was also comparable between the groups. These results indicate that pioglitazone treatment before and after elective PCI may be tolerable and clinically safe and may improve cardiometabolic profiles in T2DM patients.

Impact of pioglitazone on bone mineral density and bone marrow fat content

Pioglitazone use is associated with an increased risk of fractures. In this randomized, placebo-controlled study, pioglitazone use for 12 months was associated with a significant increase in bone marrow fat content at the femoral neck, accompanied by a significant decrease in total hip bone mineral density. The change in bone marrow fat with pioglitazone use was predominantly observed in female vs. male participants.

INTRODUCTION

Use of the insulin sensitizer pioglitazone is associated with greater fracture incidence, although the underlying mechanisms are incompletely understood. This study aimed to assess the effect of pioglitazone treatment on femoral neck bone marrow (BM) fat content and on bone mineral density (BMD), and to establish if any correlation exists between the changes in these parameters.

METHODS

In this double-blind placebo-controlled clinical trial, 42 obese volunteers with metabolic syndrome were randomized to pioglitazone (45 mg/day) or matching placebo for 1 year. The following measurements were conducted at baseline and during the treatment: liver, pancreas, and femoral neck BM fat content (by magnetic resonance spectroscopy), BMD by DXA, abdominal subcutaneous and visceral fat, and beta-cell function and insulin sensitivity.

RESULTS

Results were available for 37 subjects who completed the baseline and 1-year evaluations. At 12 months, BM fat increased with pioglitazone (absolute change, +4.1%, p = 0.03), whereas BM fat content in the placebo group decreased non-significantly (-3.1%, p = 0.08) (p = 0.007 for the pioglitazone-placebo response difference). Total hip BMD declined in the pioglitazone group (-1.4%) and increased by 0.8% in the placebo group (p = 0.03 between groups). The change in total hip BMD was inversely and significantly correlated with the change in BM fat content (Spearman rho = -0.56, p = 0.01) in the pioglitazone group, but not within the placebo group (rho = -0.29, p = 0.24). Changes in BM fat with pioglitazone were predominantly observed in female vs. male subjects.

CONCLUSIONS

Pioglitazone use for 12 months compared with placebo is associated with significant increase in BM fat content at the femoral neck, accompanied by a small but significant decrease in total hip BMD.

A Metabolic Inhibitory Cocktail for Grave Cancers: Metformin, Pioglitazone and Lithium Combination in Treatment of Pancreatic Cancer and Glioblastoma Multiforme

Pancreatic cancer (PC) and glioblastoma multiforme (GBM) are among the human cancers with worst prognosis which require an urgent need for efficient therapies. Here, we propose to apply to treat both malignancies with a triple combination of drugs, which are already in use for different indications. Recent studies demonstrated a considerable link between risk of PC and diabetes. In experimental models, anti-diabetogenic agents suppress growth of PC, including metformin (M), pioglitazone (P) and lithium (L). L is used in psychiatric practice, yet also bears anti-diabetic potential and selectively inhibits glycogen synthase kinase-3 beta (GSK-3β). M, a biguanide class anti-diabetic agent shows anticancer activity via activating AMP-activated protein kinase (AMPK). Glitazones bind to PPAR-γ and inhibit NF-κB, triggering cell proliferation, apoptosis resistance and synthesis of inflammatory cytokines in cancer cells. Inhibition of inflammatory cytokines could simultaneously decrease tumor growth and alleviate cancer cachexia, having a major role in PC mortality. Furthermore, mutual synergistic interactions exist between PPAR-γ and GSK-3β, between AMPK and GSK-3β and between AMPK and PPAR-γ. In GBM, M blocks angiogenesis and migration in experimental models. Very noteworthy, among GBM patients with type 2 diabetes, usage of M significantly correlates with better survival while reverse is true for sulfonylureas. In experimental models, P synergies with ligands of RAR, RXR and statins in reducing growth of GBM. Further, usage of P was found to be lesser in anaplastic astrocytoma and GBM patients, indicating a protective effect of P against high-grade gliomas. L is accumulated in GBM cells faster and higher than in neuroblastoma cells, and its levels further increase with chronic exposure. Recent studies revealed anti-invasive potential of L in GBM cell lines. Here, we propose that a triple-agent regime including drugs already in clinical usage may provide a metabolic adjuvant therapy for PC and GBM.

Teneligliptin Decreases Uric Acid Levels by Reducing Xanthine Dehydrogenase Expression in White Adipose Tissue of Male Wistar Rats

We investigated the effects of teneligliptin on uric acid metabolism in male Wistar rats and 3T3-L1 adipocytes. The rats were fed with a normal chow diet (NCD) or a 60% high-fat diet (HFD) with or without teneligliptin for 4 weeks. The plasma uric acid level was not significantly different between the control and teneligliptin groups under the NCD condition. However, the plasma uric acid level was significantly decreased in the HFD-fed teneligliptin treated rats compared to the HFD-fed control rats. The expression levels of xanthine dehydrogenase (Xdh) mRNA in liver and epididymal adipose tissue of NCD-fed rats were not altered by teneligliptin treatment. On the other hand, Xdh expression was reduced significantly in the epididymal adipose tissue of the HFD-fed teneligliptin treated rats compared with that of HFD-fed control rats, whereas Xdh expression in liver did not change significantly in either group. Furthermore, teneligliptin significantly decreased Xdh expression in 3T3-L1 adipocytes. DPP-4 treatment significantly increased Xdh expression in 3T3-L1 adipocytes. With DPP-4 pretreatment, teneligliptin significantly decreased Xdh mRNA expression compared to the DPP-4-treated 3T3-L1 adipocytes. In conclusion, our studies suggest that teneligliptin reduces uric acid levels by suppressing Xdh expression in epididymal adipose tissue of obese subjects.

Melatonin promotes adipogenesis and mitochondrial biogenesis in 3T3-L1 preadipocytes

Melatonin is synthesized in the pineal gland, but elicits a wide range of physiological responses in peripheral target tissues. Recent advances suggest that melatonin controls adiposity, resulting in changes in body weight. The aim of this study was to investigate the effect of melatonin on adipogenesis and mitochondrial biogenesis in 3T3-L1 mouse embryo fibroblasts. Melatonin significantly increased the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), a master regulator of adipogenesis, and promoted differentiation into adipocytes. Melatonin-treated cells also formed smaller lipid droplets and abundantly expressed several molecules associated with lipolysis, including adipose triglyceride lipase, perilipin, and comparative gene identification-58. Moreover, the hormone promoted biogenesis of mitochondria, as indicated by fluorescent staining, elevated the citrate synthase activity, and upregulated the expression of PPAR-γ coactivator 1 α, nuclear respiratory factor-1, and transcription factor A. The expression of uncoupling protein 1 was also observable both at mRNA and at protein level in melatonin-treated cells. Finally, adiponectin secretion and the expression of adiponectin receptors were enhanced. These results suggest that melatonin promotes adipogenesis, lipolysis, mitochondrial biogenesis, and adiponectin secretion. Thus, melatonin has potential as an anti-obesity agent that may reverse obesity-related disorders.

Weight loss by Ppc-1, a novel small molecule mitochondrial uncoupler derived from slime mold

Mitochondria play a key role in diverse processes including ATP synthesis and apoptosis. Mitochondrial function can be studied using inhibitors of respiration, and new agents are valuable for discovering novel mechanisms involved in mitochondrial regulation. Here, we screened small molecules derived from slime molds and other microorganisms for their effects on mitochondrial oxygen consumption. We identified Ppc-1 as a novel molecule which stimulates oxygen consumption without adverse effects on ATP production. The kinetic behavior of Ppc-1 suggests its function as a mitochondrial uncoupler. Serial administration of Ppc-1 into mice suppressed weight gain with no abnormal effects on liver or kidney tissues, and no evidence of tumor formation. Serum fatty acid levels were significantly elevated in mice treated with Ppc-1, while body fat content remained low. After a single administration, Ppc-1 distributes into various tissues of individual animals at low levels. Ppc-1 stimulates adipocytes in culture to release fatty acids, which might explain the elevated serum fatty acids in Ppc-1-treated mice. The results suggest that Ppc-1 is a unique mitochondrial regulator which will be a valuable tool for mitochondrial research as well as the development of new drugs to treat obesity.

Effects of pioglitazone on cardiac and adipose tissue pathology in rats with metabolic syndrome

BACKGROUND

Pioglitazone is a thiazolidinedione drug that acts as an insulin sensitizer. We recently characterized DahlS.Z-Lepr(fa)/Lepr(fa) (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as a new animal model of metabolic syndrome. We have now investigated the effects of pioglitazone on cardiac and adipose tissue pathology in this model.

METHODS AND RESULTS

DS/obese rats were treated with pioglitazone (2.5 mg/kg per day, per os) from 9 to 13 weeks of age. Age-matched homozygous lean (DahlS.Z-Lepr(+)/Lepr(+), or DS/lean) littermates served as controls. Pioglitazone increased body weight and food intake in DS/obese rats. It also ameliorated left ventricular (LV) hypertrophy, fibrosis, and diastolic dysfunction as well as attenuated cardiac oxidative stress and inflammation, without lowering blood pressure, in DS/obese rats, but it had no effect on these parameters in DS/lean rats. In addition, pioglitazone increased visceral and subcutaneous fat mass but alleviated adipocyte hypertrophy and inflammation in visceral adipose tissue in DS/obese rats. Furthermore, pioglitazone increased the serum concentration of adiponectin, induced activation of AMP-activated protein kinase (AMPK) in the heart, as well as ameliorated glucose intolerance and insulin resistance in DS/obese rats.

CONCLUSIONS

Treatment of DS/obese rats with pioglitazone exacerbated obesity but attenuated LV hypertrophy, fibrosis, and diastolic dysfunction, with these latter effects being associated with the activation of cardiac AMPK signaling likely as a result of the stimulation of adiponectin secretion.

Regulation of insulin resistance and adiponectin signaling in adipose tissue by liver X receptor activation highlights a cross-talk with PPARγ

Liver X receptors (LXRs) have been recognized as a promising therapeutic target for atherosclerosis; however, their role in insulin sensitivity is controversial. Adiponectin plays a unique role in maintaining insulin sensitivity. Currently, no systematic experiments elucidating the role of LXR activation in insulin function based on adiponectin signaling have been reported. Here, we investigated the role of LXR activation in insulin resistance based on adiponectin signaling, and possible mechanisms. C57BL/6 mice maintained on a regular chow received the LXR agonist, T0901317 (30 mg/kg.d) for 3 weeks by intraperitoneal injection, and differentiated 3T3-L1 adipocytes were treated with T0901317 or GW3965. T0901317 treatment induced significant insulin resistance in C57BL/6 mice. It decreased adiponectin gene transcription in epididymal fat, as well as serum adiponectin levels. Activity of AMPK, a key mediator of adiponectin signaling, was also decreased, resulting in decreased Glut-4 membrane translocation in epididymal fat. In contrast, adiponectin activity was not changed in the liver of T0901317 treated mice. In vitro, both T0901317 and GW3965 decreased adiponectin expression in adipocytes in a dose-dependent manner, an effect which was diminished by LXRα silencing. ChIP-qPCR studies demonstrated that T0901317 decreased the binding of PPARγ to the PPAR-responsive element (PPRE) of the adiponectin promoter in a dose-dependent manner. Furthermore, T0901317 exerted an antagonistic effect on the expression of adiponectin in adipocytes co-treated with 3 µM Pioglitazone. In luciferase reporter gene assays, T0901317 dose-dependently inhibited PPRE-Luc activity in HEK293 cells co-transfected with LXRα and PPARγ. These results suggest that LXR activation induces insulin resistance with decreased adiponectin signaling in epididymal fat, probably due to negative regulation of PPARγ signaling. These findings indicate that the potential of LXR activation as a therapeutic target for atherosclerosis may be limited by the possibility of exacerbating insulin resistance-related disease.

Peroxisome proliferator-activated receptors-alpha and gamma are targets to treat offspring from maternal diet-induced obesity in mice

AIM

The aim of the present study was to evaluate whether activation of peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma by Bezafibrate (BZ) could attenuate hepatic and white adipose tissue (WAT) abnormalities in male offspring from diet-induced obese dams.

MATERIALS AND METHODS

C57BL/6 female mice were fed a standard chow (SC; 10% lipids) diet or a high-fat (HF; 49% lipids) diet for 8 weeks before mating and during gestation and lactation periods. Male offspring received SC diet at weaning and were subdivided into four groups: SC, SC/BZ, HF and HF/BZ. Treatment with BZ (100 mg/Kg diet) started at 12 weeks of age and was maintained for three weeks.

RESULTS

The HF diet resulted in an overweight phenotype and an increase in oral glucose intolerance and fasting glucose of dams. The HF offspring showed increased body mass, higher levels of plasmatic and hepatic triglycerides, higher levels of pro-inflammatory and lower levels of anti-inflammatory adipokines, impairment of glucose metabolism, abnormal fat pad mass distribution, higher number of larger adipocytes, hepatic steatosis, higher expression of lipogenic proteins concomitant to decreased expression of PPARalpha and carnitine palmitoyltransferase I (CPT-1) in liver, and diminished expression of PPARgamma and adiponectin in WAT. Treatment with BZ ameliorated the hepatic and WAT abnormalities generated by diet-induced maternal obesity, with improvements observed in the structural, biochemical and molecular characteristics of the animals' livers and epididymal fat.

CONCLUSION

Diet-induced maternal obesity lead to alterations in metabolism, hepatic lipotoxicity and adverse liver and WAT remodeling in the offspring. Targeting PPAR with Bezafibrate has beneficial effects reducing the alterations, mainly through reduction of WAT inflammatory state through PPARgamma activation and enhanced hepatic beta-oxidation due to increased PPARalpha/PPARgamma ratio in liver.

Pioglitazone prevents hyperglycemia induced decrease of AdipoR1 and AdipoR2 in coronary arteries and coronary VSMCs

BACKGROUND

Adiponectin receptors play an important role in inflammatory diseases like diabetes and atherosclerosis. Former studies revealed that the regulation of adiponectin receptors expression differs in the receptor responses to pioglitazone. However, expression of AdipoRs has not been investigated in the coronary arteries or the coronary vascular smooth muscle cells (VSMCs). In the present study we investigated the effect of pioglitazone on the adiponectin receptors both in vitro and in vivo.

METHODS

Male Sprague-Dawley rats were randomly divided in three groups. One of them fed with regular chow (the Control group) and two of them fed with high-fat diet and then received low-dose Streptozotocin once by intraperitoneal injection (the DM groups). Rats in one of the DM groups were further treated with pioglitazone (the PIO group). Blood pressure, serum adiponectin, fasting blood glucose, fasting serum insulin, cholesterol, triglyceride, AdipoR1 and AdipoR2 expression, and TNF-α expression in coronary arteries of these groups were investigated. For the in vitro study, the rat coronary VSMCs maintained under defined in vitro conditions were treated with either PIO or the PIO+ GW9662 (PPAR-γ antagonist), and then stimulated with high glucose. AdipoR1 and AdipoR2 expression, TNF-α expression and PPAR-γ expression were investigated.

RESULTS

Compared to the DM group, treatment with PIO in vivo significantly attenuated cholesterol level, triglyceride level, fasting serum insulin and TNF-α overexpression (p<0.05). PIO also increased AdipoR1 and AdipoR2 expression in coronary arteries, which were reduced notably in the DM group (p<0.05). Consistently, in the study with rat coronary VSMCs, PIO prominently downregulated TNF-α expression and induced PPAR-γ expression, as well as prevented hyperglycemia induced decrease of AdipoR1 and AdipoR2 expression (p<0.05). And pretreatment of PIO+GW9662 did not manifest the prevention effect.

CONCLUSION

In this study, we showed that treatment with PIO could ameliorate coronary insulin resistant and upregulate the expression of AdipoR1/R2. PIO showed an anti-atherogenic property via the activation of PPAR-γ, suppression of TNF-α overexpression in coronary and coronary VSMCs.

The Adipose Tissue Endocrine Mechanism of the Prophylactic Protective Effect of Pioglitazone in High-Fat Diet-Induced Insulin Resistance

OBJECTIVE: To explore the adipose tissue endocrine mechanism of pioglitazone and its possible prophylactic role in insulin resistance. METHODS: Male Wistar rats were randomized to receive a normal diet (N group), a high-fat insulin resistance-inducing diet (IR group), or a high-fat diet plus treatment with pioglitazone (P group). Glucose tolerance and insulin resistance were tested at weeks 10 and 11 after starting the diet and, at week 12, adipose, liver and skeletal muscle tissue samples were taken. HepG2 cells were cultured with palmitic acid (PA), pioglitazone and PA plus pioglitazone, and RNA interference was used to downregulate adiponectin receptor (AdipoR) 2 in these cells. The mRNA and protein levels of adipokines (resistin and adiponectin), AdipoR1 and 2 and uptake of [3H]-labelled glucose were measured in the HepG2 cells. RESULTS: Resistin and adiponectin in adipose tissue and AdipoR2 in liver tissue were significantly decreased in the IR group compared with the N group. Adiponectin and AdipoR2 were significantly increased and insulin resistance significantly decreased in the P group versus the IR group. In HepG2 cells, AdipoR2 levels and glucose uptake decreased significantly when PA was ≥ 200 μM, but were elevated by pioglitazone. Small interfering RNA-AdipoR2 confirmed glucose uptake in liver was regulated by AdipoR2. CONCLUSIONS: Pioglitazone prevented insulin resistance in rats fed a high-fat diet. Liver AdipoR2-mediated glucose uptake is important in the prophylactic effect of pioglitazone on insulin resistance.

Adiponectin and PPARγ: cooperative and interdependent actions of two key regulators of metabolism

The recent advances in the understanding of adiponectin and other adipokines have highlighted the role of adipose tissue as an active endocrine organ. One of the central regulators of adipocyte biology is peroxisome proliferator-activated receptor gamma (PPARγ), a transcription factor that induces the adipogenic gene expression program during development, promotes adipose remodeling, and regulates the functions of adipocytes in lipid storage, adipokine secretion, and energy homeostasis. Activation of PPARγ results in increased insulin sensitivity in skeletal muscle and liver and improves the secretory profile of adipose tissue, favoring release of insulin-sensitizing adipokines, such as adiponectin, and reducing inflammatory cytokines. Increased adiponectin production is likely a significant mediator of the systemic effects of PPARγ activation. This chapter will review the interplay between PPARγ and adiponectin in regulating metabolism, presenting evidence that PPARγ regulates adiponectin gene expression, processing, and secretion and that the two proteins have overlapping effects on downstream metabolic pathways.