Thiazolidinedione suppresses the expression of erythroid phenotype in erythroleukemia cell line K562

Exploring the nexus of nuclear receptors in hematological malignancies

Hematological malignancies (HM) represent a subset of neoplasms affecting the blood, bone marrow, and lymphatic systems, categorized primarily into leukemia, lymphoma, and multiple myeloma. Their prognosis varies considerably, with a frequent risk of relapse despite ongoing treatments. While contemporary therapeutic strategies have extended overall patient survival, they do not offer cures for advanced stages and often lead to challenges such as acquisition of drug resistance, recurrence, and severe side effects. The need for innovative therapeutic targets is vital to elevate both survival rates and patients' quality of life. Recent research has pivoted towards nuclear receptors (NRs) due to their role in modulating tumor cell characteristics including uncontrolled proliferation, differentiation, apoptosis evasion, invasion and migration. Existing evidence emphasizes NRs' critical role in HM. The regulation of NR expression through agonists, antagonists, or selective modulators, contingent upon their levels, offers promising clinical implications in HM management. Moreover, several anticancer agents targeting NRs have been approved by the Food and Drug Administration (FDA). This review highlights the integral function of NRs in HM's pathophysiology and the potential benefits of therapeutically targeting these receptors, suggesting a prospective avenue for more efficient therapeutic interventions against HM.

Cellular specificity of androgen receptor, coregulators, and pioneer factors in prostate cancer

Androgen signalling, through the transcription factor androgen receptor (AR), is vital to all stages of prostate development and most prostate cancer progression. AR signalling controls differentiation, morphogenesis, and function of the prostate. It also drives proliferation and survival in prostate cancer cells as the tumour progresses; given this importance, it is the main therapeutic target for disseminated disease. AR is also essential in the surrounding stroma, for the embryonic development of the prostate and controlling epithelial glandular development. Stromal AR is also important in cancer initiation, regulating paracrine factors that excite cancer cell proliferation, but lower stromal AR expression correlates with shorter time to progression/worse outcomes. The profile of AR target genes is different between benign and cancerous epithelial cells, between castrate-resistant prostate cancer cells and treatment-naïve cancer cells, between metastatic and primary cancer cells, and between epithelial cells and fibroblasts. This is also true of AR DNA-binding profiles. Potentially regulating the cellular specificity of AR binding and action are pioneer factors and coregulators, which control and influence the ability of AR to bind to chromatin and regulate gene expression. The expression of these factors differs between benign and cancerous cells, as well as throughout disease progression. The expression profile is also different between fibroblast and mesenchymal cell types. The functional importance of coregulators and pioneer factors in androgen signalling makes them attractive therapeutic targets, but given the contextual expression of these factors, it is essential to understand their roles in different cancerous and cell-lineage states.

Does Thiazolidinedione therapy exacerbate fluid retention in congestive heart failure?

The ever-growing global burden of congestive heart failure (CHF) and type 2 diabetes mellitus (T2DM) as well as their co-existence necessitate that anti-diabetic pharmacotherapy will modulate the cardiovascular risk inherent to T2DM while complying with the accompanying restrictions imposed by CHF. The thiazolidinedione (TZD) family of peroxisome proliferator-activated receptor γ (PPARγ) agonists initially provided a promising therapeutic option in T2DM owing to anti-diabetic efficacy combined with pleiotropic beneficial cardiovascular effects. However, the utility of TZDs in T2DM has declined in the past decade, largely due to concomitant adverse effects of fluid retention and edema formation attributed to salt-retaining effects of PPARγ activation on the nephron. Presumably, the latter effects are potentially deleterious in the context of pre-existing fluid retention in CHF. However, despite a considerable body of evidence on mechanisms responsible for TZD-induced fluid retention suggesting that this class of drugs is rightfully prohibited from use in CHF patients, there is a paucity of experimental and clinical studies that investigate the effects of TZDs on salt and water homeostasis in the CHF setting. In an attempt to elucidate whether TZDs actually exacerbate the pre-existing fluid retention in CHF, our review summarizes the pathophysiology of fluid retention in CHF. Moreover, we thoroughly review the available data on TZD-induced fluid retention and proposed mechanisms in animals and patients. Finally, we will present recent studies challenging the common notion that TZDs worsen renal salt and water retention in CHF.

Peroxisome Proliferator-Activated Receptor Ligands and Their Role in Chronic Myeloid Leukemia: Therapeutic Strategies

Imatinib therapy remains the gold standard for treatment of chronic myeloid leukemia; however, the acquired resistance to this therapeutic agent in patients has urged the scientists to devise modalities for overcoming this chemoresistance. For this purpose, initially therapeutic agents with higher tyrosine kinase activity were introduced, which had the potential for inhibiting even mutant forms of Bcr-Abl. Furthermore, coupling imatinib with peroxisome proliferator-activated receptor ligands also showed beneficial effects in chronic myeloid leukemia cell proliferation. These combination protocols inhibited cell growth and induced apoptosis as well as differentiation in chronic myeloid leukemia cell lines. In addition, peroxisome proliferator-activated receptors ligands increased imatinib uptake by upregulating the expression of human organic cation transporter 1. Taken together, peroxisome proliferator-activated receptors ligands are currently being considered as novel promising therapeutic candidates for chronic myeloid leukemia treatment, because they can synergistically enhance the efficacy of imatinib. In this article, we reviewed the potential of peroxisome proliferator-activated receptors ligands for use in chronic myeloid leukemia treatment. The mechanism of action of these therapeutics modalities are also presented in detail.

The Effect of Baicalin as A PPAR Activator on Erythroid Differentiation of CD133(+)Hematopoietic Stem Cells in Umbilical Cord Blood

OBJECTIVE

The peroxisome proliferator-activated receptors (PPARs) are a group of nu- clear receptor proteins whose functions as transcription factors regulate gene expres- sions. PPARs play essential roles in the regulation of cellular differentiation, development, and metabolism (carbohydrate, lipid, protein), and tumorigenesis of higher organisms. This study attempts to determine the effect of baicalin, a PPARγ activator, on erythroid differentiation of cluster of differentiation 133(+)(CD133(+)) cord blood hematopoietic stem cells (HSCs).

MATERIALS AND METHODS

In this experimental study, in order to investigate the effects of the PPARγ agonists baicalin and troglitazone on erythropoiesis, we isolated CD133(+) cells from human umbilical cord blood using the MACS method. Isolated cells were cultured in erythroid-inducing medium with or without various amounts of the two PPARγ activa- tors (baicalin and troglitazone). Erythroid differentiation of CD133(+)cord blood HSCs were assessed using microscopic morphology analysis, flow cytometric analysis of erythroid surface markers transferrin receptor (TfR) and glycophorin A (GPA) and bycolony forming assay.

RESULTS

Microscopic and flow cytometric analysis revealed the erythroid differentiation of CD133(+)cord blood HSCs under applied erythroid inducing conditions. Our flow cytometric data showed that the TfR and GPA positive cell population diminished significantly in the presence of either troglitazone or baicalin. The suppression of erythroid differentiation in response to PPARγ agonists was dose-dependent. Erythroid colony-forming ability of HSC decreased significantly after treatment with both PPARγ agonists but troglitazone had a markedly greater effect.

CONCLUSION

Our results have demonstrated that PPARγ agonists modulate erythroid dif- ferentiation of CD133(+)HSCs, and therefore play an important role in regulation of normal erythropoiesis under physiologic conditions. Thus, considering the availability and applica- tion of this herbal remedy for treatment of a wide range of diseases, the inhibitory effect of baicalin on erythropoiesis should be noted.

Residual effect of reductions in red blood cell count and haematocrit and haemoglobin levels after 10-month withdrawal of pioglitazone in patients with Type 2 diabetes

AIM

To investigate the recovery of thiazolidinedione-induced body weight gain and haematopoietic changes after stopping pioglitazone treatment in patients with Type 2 diabetes.

METHODS

This retrospective cohort study included 214 patients divided into three groups according to pioglitazone treatment status. The first study arm included patients who received pioglitazone for 38 months then interrupted this for 10 months (pioglitazone-interruption group). The second arm consisted of patients who received pioglitazone throughout the 48 months (pioglitazone-continuous group); the third arm included patients who had never received pioglitazone therapy (control group).

RESULTS

Red blood cell count and haematocrit and haemoglobin levels decreased significantly, while body weight increased in the two pioglitazone-treated groups as compared with the control group at 38 months. Multivariate regression analysis showed that the reductions in red blood cell count/haemoglobin levels were associated with pioglitazone use. In the pioglitazone-interruption group, no recoveries of red blood cells, or haematocrit or haemoglobin levels were observed after stopping pioglitazone for 10 months compared with the pioglitazone-continuous group, but body weight gain decreased to a level that was significantly lower than that in the pioglitazone-continuous group and did not differ significantly from the control group.

CONCLUSION

In this study, we observed a reversal of body weight gain but no recoveries in red blood cells or haematocrit or haemoglobin levels after stopping pioglitazone for 10 months in patients treated with pioglitazone for 38 months. This finding should prompt a reconsideration of the sustained effect of thiazolidinediones on the haematopoietic system in patients with Type 2 diabetes.

Evaluation of peroxisome proliferator-activated receptor agonists on interleukin-5-induced eosinophil differentiation

Peroxisome proliferator-activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin-5 (IL-5) -induced eosinophil differentiation from haemopoietic progenitor cells. Non-adherent mononuclear cells or CD34(+) cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult(®) cultures with IL-5 (10 ng/ml) and IL-3 (25 ng/ml) in the presence of 1-1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony-forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood-extracted CD34(+) cells cultured with IL-5 or IL-5 + IL-3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm, P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL-5-induced phosphorylation of extracellular signal-regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal-regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses.

Anaemia, a common but often unrecognized risk in diabetic patients: a review

Anaemia in patients with diabetes, both type 1 and type 2, is a frequent clinical finding. The mechanisms of anaemia are multifactorial and often not very well understood. Iatrogenic causes, including oral antidiabetic drugs, ACE inhibitors and ARBs, and renal insufficiency are the major causes of anaemia in patients with type 2 diabetes. In patients with type 1, the cause is often an associated autoimmune disease, and screening for autoimmune gastritis, pernicious anaemia, Hashimoto's thyroiditis, coeliac disease and Addison's disease is recommended. Other rare causes - including G6PD deficiency, microangiopathic haemolytic anaemia and thiamine-responsive megaloblastic anaemia - should be suspected in young patients or when the classical causes are excluded. Early detection and recognition of the cause(s) of anaemia in patients with diabetes could help to prevent other clinical manifestations as well as the complications of diabetes.

The aryl hydrocarbon receptor nuclear translocator (ARNT) modulates the antioxidant response in AML cells

We observed AML cell lines vary in their sensitivity to induction of apoptosis by troglitazone (TG), which induces apoptosis through the generation of intracellular reactive oxygen species (ROS). TG-resistant cell lines had increased abundance of ARNT transcripts and protein. Expression of ARNT in TG-sensitive cells made these cells resistant to both TG and daunorubicin. ARNT-expressing cells had increased expression of SOD2 and Nrf2 transcripts and elevated intracellular GSH concentration. Our results indicate that ARNT expression in AML cells augments antioxidant response and confers resistance to ROS inducers. This suggests ARNT may modulate ROS signaling and drug response in AML.

Role of peroxisome proliferator-activated receptor gamma and its ligands in the treatment of hematological malignancies

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a multifunctional transcription factor with important regulatory roles in inflammation, cellular growth, differentiation, and apoptosis. PPARgamma is expressed in a variety of immune cells as well as in numerous leukemias and lymphomas. Here, we review recent studies that provide new insights into the mechanisms by which PPARgamma ligands influence hematological malignant cell growth, differentiation, and survival. Understanding the diverse properties of PPARgamma ligands is crucial for the development of new therapeutic approaches for hematological malignancies.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

New recurrent deletions in the PPARgamma and TP53 genes are associated with childhood myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a rare hematological malignancy in children. It was performed FISH analysis in 19 pediatric MDS patients to investigate deletions involving the PPARgamma and TP53 genes. Significant losses in the PPARgamma gene and deletions in the tumor suppressor gene TP53 were observed in 17 and 18 cases, respectively. Using quantitative RT-PCR, it was detected PPARgamma transcript downexpression in a subset of these cases. G-banding analysis revealed 17p deletions in a small number of these cases. One MDS therapy-related patient had neither a loss of PPARgamma nor TP53. These data suggest that the PPARgamma and TP53 genes may be candidates for molecular markers in pediatric MDS, and that these potentially recurrent deletions could contribute to the identification of therapeutic approaches in primary pediatric MDS.

Adipose tissue-derived and bone marrow-derived mesenchymal cells develop into different lineage of steroidogenic cells by forced expression of steroidogenic factor 1

Steroidogenic factor 1 (SF-1)/adrenal 4 binding protein is an essential nuclear receptor for steroidogenesis, as well as for adrenal and gonadal gland development. We have previously clarified that adenovirus-mediated forced expression of SF-1 can transform long-term cultured mouse bone marrow mesenchymal cells (BMCs) into ACTH-responsive steroidogenic cells. In the present study, we extended this work to adipose tissue-derived mesenchymal cells (AMCs) and compared its steroidogenic capacity with those of BMCs prepared from the identical mouse. Several cell surface markers, including potential mesenchymal cell markers, were identical in both cell types, and, as expected, forced expression of SF-1 caused AMCs to be transformed into ACTH-responsive steroidogenic cells. However, more elaborate studies revealed that the steroidogenic property of AMCs was rather different from that of BMCs, especially in steroidogenic lineage. In response to increased SF-1 expression and/or treatment with retinoic acid, AMCs were much more prone to produce adrenal steroid, corticosterone rather than gonadal steroid, testosterone, whereas the contrary was evident in BMCs. Such marked differences in steroidogenic profiles between AMCs and BMCs were also evident by the changes of steroidogenic enzymes. These novel results suggest a promising utility of AMCs for autologous cell regeneration therapy for patients with steroid insufficiency and also a necessity for appropriate tissue selection in preparing mesenchymal stem cells according to the aim. The different steroidogenic potency of AMCs or BMCs might provide a good model for the clarification of the mechanism of tissue- or cell-specific adrenal and gonadal steroidogenic cell differentiation.

Reduction in hematocrit and hemoglobin following pioglitazone treatment is not hemodilutional in Type II diabetes mellitus

Peripheral edema, mild weight gain, and anemia are often observed in type II diabetic patients treated with thiazolidinediones (TZDs). Small decreases in hemoglobin (Hb) and hematocrit (Hct) appear to be a class effect of TZDs and are generally attributed to fluid retention, although experimental data are lacking. We analyzed 50 patients with type II diabetes mellitus undergoing either placebo or pioglitazone (PIO, 45 mg/day) for 16 weeks. Before and after therapy, we measured Hb/Hct and used (3)H(2)O and bioimpedance to quantitate total body water (TBW), extracellular water, and fat-free mass. The majority (89%) of the increment in body weight was accounted for by increased body fat. Hb and Hct fell significantly in the PIO group (-0.9+/-0.2 g/dl, -2.4+/-0.5%, both P<0.0001), without change in TBW. A decline in white blood cell (-0.8+/-0.1 x 10(3)/mm(3), P<0.0001) and platelet (-15+/-6 x 10(3)/mm(3), P<0.02) counts was seen after PIO. In conclusion, the small decreases in Hb/Hct observed after 16 weeks of PIO treatment cannot be explained by an increase in TBW. Other causes, such a mild marrow suppressive effect, should be explored.

Anemia and the role of erythropoietin in diabetes

Anemia is more common in patients with diabetes than without diabetes, and the problem is magnified in patients with renal impairment. Diabetic patients with anemia may be at increased risk of adverse outcomes from diabetic retinopathy, nephropathy, neuropathy, and cardiovascular disease. The etiology of anemia in diabetes is multifactorial and includes inflammation, nutritional deficiencies, concomitant autoimmune diseases, drugs, and hormonal changes in addition to kidney disease. Anemia that is associated with erythropoietin deficiency may have prognostic significance for persons with nephropathy or heart failure. In early diabetic nephropathy, damage to the peritubular fibroblasts can occur and lead to erythropoietin deficiency and anemia prior to the loss of filtration. Correction of the anemia not only leads to less fatigue, greater exercise tolerance, and an improved quality of life but also to a reduction in mortality and hospital admissions for congestive heart failure (CHF). Data are accumulating that suggest that treatment of anemia will slow the progression of microvascular and macrovascular complications, including postural hypotension from autonomic neuropathy, retinopathy, and loss of renal function from diabetic nephropathy. Promptly diagnosing and treating anemia in patients with diabetes may result in an improved quality of life and decreased morbidity and mortality.

Pivotal role of peroxisome proliferator-activated receptor gamma (PPARgamma) in regulation of erythroid progenitor cell proliferation and differentiation

OBJECTIVE

The aim of this study was to reveal the role of peroxisome proliferator-activated receptor gamma (PPARgamma) in erythropoiesis.

METHODS

The effects of PPARgamma ligands on cellular proliferation and differentiation were investigated in erythroid colony-forming cells (ECFCs) purified from human peripheral blood.

RESULTS

RT-PCR analysis revealed that PPARgamma mRNA is expressed in ECFCs. Synthetic PPARgamma ligands, troglitazone or pioglitazone, suppressed cellular proliferation without inducing apoptosis and delayed maturation of ECFCs, as determined by flow cytometry. The delay in erythroid maturation by troglitazone was confirmed by the down-regulation of gamma-globin, beta-globin and GATA-1 mRNA, and the maintenance of GATA-2 mRNA.

CONCLUSIONS

Our results suggest that PPARgamma modulates the differentiation process of erythroid progenitor cells, and plays a crucial role in regulating the balance of hematopoiesis.

SF-1/Ad4BP transforms primary long-term cultured bone marrow cells into ACTH-responsive steroidogenic cells

Bone marrow stem cells develop into haematopoietic and mesenchymal lineages, but have not been known to participate in steroidogenic cell production. Steroidogenic factor 1 (SF-1), also designated adrenal 4 binding protein (Ad4BP), is an essential orphan nuclear receptor for steroidogenesis as well as for adrenal and gonadal gland development. In the present study, we revealed that the adenovirus-mediated forced expression of SF-1 can transform cultured primary long-term cultured bone marrow cells into steroidogenic cells, showing the de novo synthesis of multiple steroid hormones in response to adrenocorticotropic hormone (ACTH). This finding may provide an initial step in innovative autograft cell transfer therapy for steroid hormone deficiencies.

Therapeutic potential of thiazolidinediones as anticancer agents

Thiazolidinediones (TZDs) are synthetic ligands that activate the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-gamma). These compounds are widely used in the treatment of Type 2 diabetes. TZDs have antitumour activity in a wide variety of experimental cancer models, in vitro and in vivo, by affecting the cell cycle, induction of cell differentiation and apoptosis as well as by inhibiting tumour angiogenesis. These effects are mediated through both PPAR-gamma-dependent and -independent pathways depending on concentration and tumour cell type. Angiogenesis inhibition mechanisms of TZDs include directly inhibiting endothelial cell proliferation and migration as well as decreasing tumour cell vascular endothelial growth factor production. Further studies suggest that TZDs may be effective in prevention of certain cancers and in the treatment of cancer as adjuvant therapy.

Peroxisome proliferator-activated receptor gamma ligands inhibit cell growth and induce apoptosis in human liver cancer BEL-7402 cells

AIM: To investigate the characteristics of PPAR gamma ligands induced apoptosis in liver cancer cells.

METHODS: The effects of ligands for each of the PPAR gamma ligands on DNA synthesis and cell viability were examined in BEL-7402 liver cancer cells. Apoptosis was characterized by Hochest33258 staining, DNA fragmentation, TUNEL and ELISA, and cell cycle kinetics by FACS. Modulation of apoptosis related caspases expression by PPAR gamma ligands was examined by Western blot.

RESULTS: PPARgamma ligands, 15-deoxy-^{12, 14}-prostaglandin J2 (15d-PGJ2) and troglitazone (TGZ), suppressed DNA synthesis of BEL-7402 cells. Both 15d-PGJ2 and TGZ induced BEL-7402 cell death in a dose dependent manner, which was associated with an increase in fragmented DNA and TUNEL-positive cells. At concentrations of 10 and 30 µM, 15d-PGJ₂ or troglitazone increased the proportion of cells with G₀/G₁ phase DNA content and decreased those with S phase DNA content. There was no significant change in the proportion of cells with G₂/M DNA content. The activities of Caspases-3, -6, -7 and -9 were increased by 15d-PGJ2 and TGZ treatment, while the activity of Caspase 8 had not significantly changed.

CONCLUSION: The present results suggest the potential usefulness of PPAR gamma ligands for chemoprevention and treatment of liver cancers.

Peroxisome proliferator-activated receptors (PPARs) in health and disease

Peroxisome proliferator-activated receptors (PPARs) belong to the superfamily of steroid-thyroid-retinoid nuclear receptors. PPARs are transcription factors activated by specific ligands and play an important role during cell signalling. Intensive study of PPARs during recent years has revealed their importance in both normal physiology and in the pathology of various tissues. They participate in the regulation of lipid metabolism, inflammation and the development of atherosclerosis or diabetes. They also play a role in the regulation of growth and differentiation of cancer. It has been suggested that PPAR ligands may have potent anticancer effects and therefore may serve as potential anticancer drugs. In this review we focus on a role of PPARs in breast cancer and in glial tumors of the brain.