Terminal differentiation of human liposarcoma cells induced by ligands for peroxisome proliferator-activated receptor gamma and the retinoid X receptor

Peroxisome proliferator-activated receptor gamma (PPARγ) is central to the initiation and propagation of human angiomyolipoma, suggesting its potential as a therapeutic target

Angiomyolipoma (AML), the most common benign renal tumor, can result in severe morbidity from hemorrhage and renal failure. While mTORC1 activation is involved in its growth, mTORC1 inhibitors fail to eradicate AML, highlighting the need for new therapies. Moreover, the identity of the AML cell of origin is obscure. AML research, however, is hampered by the lack of in vivo models. Here, we establish a human AML‐xenograft (Xn) model in mice, recapitulating AML at the histological and molecular levels. Microarray analysis demonstrated tumor growth in vivo to involve robust PPARG‐pathway activation. Similarly, immunostaining revealed strong PPARG expression in human AML specimens. Accordingly, we demonstrate that while PPARG agonism accelerates AML growth, PPARG antagonism is inhibitory, strongly suppressing AML proliferation and tumor‐initiating capacity, via a TGFB‐mediated inhibition of PDGFB and CTGF. Finally, we show striking similarity between AML cell lines and mesenchymal stem cells (MSCs) in terms of antigen and gene expression and differentiation potential. Altogether, we establish the first in vivo human AML model, which provides evidence that AML may originate in a PPARG‐activated renal MSC lineage that is skewed toward adipocytes and smooth muscle and away from osteoblasts, and uncover PPARG as a regulator of AML growth, which could serve as an attractive therapeutic target.

PPARγ sumoylation-mediated lipid accumulation in lung cancer

Metabolic reprogramming as a crucial emerging hallmark of cancer is critical for tumor cells to maintain cellular bioenergetics, biosynthesis and reduction/oxidation (REDOX) balance. Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor regulating transcription of diverse gene sets involved in inflammation, metabolism, and suppressing tumor growth. Thiazolidinediones (TZDs), as selective PPARγ ligands, are insulin-sensitizing drugs widely prescribed for type 2 diabetic patients in the clinic. Here, we report that sumoylation of PPARγ couples lipid metabolism to tumor suppressive function of the receptor in lung cancer. We found that ligand activation of PPARγ dramatically induced de novo lipid synthesis as well as fatty acid beta (β)-oxidation in lung cancer both in vitro and in vivo. More importantly, it turns out that PPARγ regulation of lipid metabolism was dependent on sumoylation of PPARγ. Further biochemical analysis revealed that PPARγ-mediated lipid synthesis depletes nicotinamide adenine dinucleotide phosphate (NADPH), consequently resulting in increased mitochondrial reactive oxygen species (ROS) level that subsequently disrupted REDOX balance in lung cancer. Therefore, liganded PPARγ sumoylation is not only critical for cellular lipid metabolism but also induces oxidative stress that contributes to tumor suppressive function of PPARγ. This study provides an important insight of future translational and clinical research into targeting PPARγ regulation of lipid metabolism in lung cancer patients accompanying type 2 diabetes.

Do Mesenchymal Stem Cells Derived From Atypical Lipomatous Tumors Have Greater Differentiation Potency Than Cells From Normal Adipose Tissues?

BACKGROUND

The p53 protein in mesenchymal stem cells (MSCs) regulates differentiation to osteogenic or adipogenic lineage. Because p53 function is depressed in most malignancies, if MSCs in malignancy also have p53 hypofunction, differentiation therapy to osteogenic or adipogenic lineage may be an effective treatment. We therefore wished to begin to explore this idea by evaluating atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) cells, because murine double minute 2 (MDM2) gene amplification, which leads to p53 hypofunction, is found in almost all ALT/WDLs.

QUESTIONS/PURPOSES

We compared osteogenic and adipogenic differentiation potency between MSCs isolated and cultured from normal adipose tissues and ALT/WDLs from the same patients.

METHODS

During tumor resections in six patients with ALT/WDL, we analyzed 3 mL of tumor, and for comparison, we harvested a similar amount of normal-appearing subcutaneous adipose tissue from an area remote from the tumor for comparison. Adipogenic differentiation potency was quantitatively assessed using spectrometry after oil red O staining. Osteogenic differentiation potency was semiquantitatively assessed by measuring a specific colored area after alkaline phosphatase (ALP) and alizarin red S staining. ALP is related to preosseous cellular metabolism, and alizarin red is related to calcium deposits in cell culture. There were three observers for each assessment, and each assessment (including induced-differentiation and histologic analysis) was performed in duplicate. We then analyzed the mechanism of the difference of osteogenic differentiation potency using the MDM2-specific inhibitor Nutlin-3 at various concentrations.

RESULTS

In terms of adipogenic differentiation potency, contrary to our expectations, more fatty acid droplets were observed in MSCs derived from normal fat than in MSCs derived from ALT/WDL, although we found no significant difference between MSCs derived from ALT/WDL and MSCs derived from normal fat; the mean differentiation potency values (normal adipose tissue versus ALT/WDL) (± SD) were 0.34 (SD, ± 0.13; 95% CI, 0.24-0.44) versus 0.25 (SD, ± 0.10; 95% CI, 0.18-0.33; p = 0.22). By contrast, we found greater osteogenic differentiation potency in MSCs derived from ALT/WDL than in MSCs derived from normal fat. The mean differentiation potency values (normal adipose tissue versus ALT/WDL) (±SD) based on ALP staining was 1.0 versus 17 (SD, ± 36; 95% CI, -2.8 to 38; p = 0.04). However, we found no differences based on alizarin red S staining; mean differentiation potency value (normal adipose tissue versus ALT/WDL) (± SD) was 1.0 versus 4.2 (SD, ± 4.8; 95% CI, 1.3-7.2; p = 0.58). The gap of osteogenic differentiation potency between MSCs from normal adipose tissue and ALT/WDL was decreased as MDM2-inhibitor Nutlin-3 concentration increased.

CONCLUSIONS

MSCs derived from ALT/WDL had higher osteogenic differentiation potency based on ALP staining, which disappeared as Nutlin-3 concentration increased, suggesting that could be caused by amplified MDM2 in ALT/WDL. Future laboratory studies might mechanistically confirm the gene and protein expression, and based on the mechanism of the gap of differentiation potency, if p53 contrast between MSCs in tumor and normal tissue could be stimulated, less-toxic and more-effective differentiation therapy to MSCs in malignancies might be developed.

Thiazolidinediones abrogate cervical cancer growth

Peroxisome proliferator-activated receptor gamma (PPAR γ) is activated by thiazolidinedione drugs (TZDs) and can promote anti-cancer properties. We used three TZDs (pioglitazone, rosiglitazone, and ciglitazone) to target cervical cancer cell lines and a nude mouse animal model. Each agent increased activation of PPAR γ, as judged by a luciferase reporter gene assay in three HPV-associated cell lines (CaSki, SiHa, and HeLa cells) while decreasing cellular proliferation in a dose-dependent manner. They also promoted Oil Red O accumulation in treated cell lines and upregulated the lipid differentiation marker adipsin. Interestingly, xenograft HeLa tumors in nude mice treated with 100mg/kg/day pioglitazone exhibited decreased growth compared to control mice or mice treated with standard cervical chemotherapy. In conclusion, TZDs slow tumor cell growth in vitro and in vivo with decreases in cell proliferation and increases in PPAR γ and adipsin. These agents may be interesting treatments or treatment adjuncts for HPV-associated cancers or perhaps even precancerous conditions.

Pharmacological therapies for Liposarcoma

INTRODUCTION

Liposarcoma (LS) is one of the most common adult soft tissue sarcomas (STS). For metastatic disease, systemic treatment options were historically represented by standard cytotoxic chemotherapy. More recently, innovative therapies have been introduced and they are currently part of the therapeutic armamentarium, positively impacting disease control and patients' quality of life. Moreover, in the last decade, a better understanding of the molecular characteristics of each STS subtype allowed to detect new potential targets and develop novel, biology-driven compounds at different stages of testing. Areas covered: This review is focused on LS, retracing their pharmacological management, starting with a summary of results achieved with standard chemotherapy, then moving to a deeper analysis on data obtained with new, approved therapies and finally reporting an update on ongoing clinical trials, thus providing an overview on the current scenario and outlining how it might evolve in the coming years. Expert commentary: Important strides have been made in the knowledge and treatment of LS. Peculiar molecular features and fundamental signalling pathways represent nowadays druggable targets for novel therapies. However, predictive biomarkers still need to be identified in order to better select the target population, to possibly test combinations of drugs, with the ultimate goal of improving outcomes.

Polyphenols in Regulation of Redox Signaling and Inflammation During Cardiovascular Diseases

Cardiovascular diseases remain one of the major health problems worldwide. The worldwide research against cardiovascular diseases as well as genome wide association studies were successful in indentifying the loci associated with this prominent life-threatening disease but still a substantial amount of casualty remains unexplained. Over the last decade, the thorough understanding of molecular and biochemical mechanisms of cardiac disorders lead to the knowledge of various mechanisms of action of polyphenols to target inflammation during cardiac disorders. The present review article summarizes major mechanisms of polyphenols against cardiovascular diseases.

Role of TCTP for Cellular Differentiation and Cancer Therapy

The translationally controlled tumor protein (TCTP) is a highly conserved protein that is regulated due to a high number of extracellular stimuli. TCTP has an important role for cell cycle and normal development. On the other side, tumor reversion and malignant transformation have been associated with TCTP. TCTP has been found among the 12 genes that are differentially expressed during mouse oocyte maturation, and an overexpression of this gene was reported in a wide variety of different cancer types. Its antiapoptotic effect is indicated by the interaction with several proapoptotic proteins of the Bcl-2 family and the p53 tumor suppressor protein. In this article, we draw attention to the role of TCTP in cancer, especially, focusing on cell differentiation and tumor reversion, a biological process by which highly tumorigenic cells lose their malignant phenotype. This protein has been shown to be the most strongly downregulated protein in revertant cells compared to the parental cancer cells. Decreased expression of TCTP results either in the reprogramming of cancer cells into reversion or apoptosis. As conventional chemotherapy is frequently associated with the development of drug resistance and high toxicity, the urge for the development of new or additional scientific approaches falls into place. Differentiation therapy aims at reinducing differentiation backward to the nonmalignant cellular state. Here, different approaches have been reported such as the induction of retinoid pathways and the use of histone deacetylase inhibitors. Also, PPARγ agonists and the activation of the vitamin D receptor have been reported as potential targets in differentiation therapy. As TCTP is known as the histamine-releasing factor, antihistaminic drugs have been shown to target this protein. Antihistaminic compounds, hydroxyzine and promethazine, inhibited cell growth of cancer cells and decreased TCTP expression of breast cancer and leukemia cells. Recently, we found that two antihistaminics, levomepromazine and buclizine, inhibited cancer cell growth by direct binding to TCTP and induction of cell differentiation. These data confirmed that TCTP is an exquisite target for anticancer differentiation therapy and antihistaminics have potential to be lead compounds for the direct interaction with TCTP as new inhibitors of human TCTP and tumor growth.

Effect of (-)-epigallocatechin-3-gallate on anti-inflammatory response via heme oxygenase-1 induction during adipocyte-macrophage interactions

In this study, we examined the effects of (-)-epigallocatechin-3-gallate (EGCG) on anti-inflammatory responses through the induction of heme oxygenase-1 (HO-1) in cocultured macrophages and adipocytes. EGCG significantly decreased the secretion of nitric oxide (NO) and monocyte chemoattractant protein-1 in the coculture of RAW 264.7 macrophages and differentiated 3T3-L1 adipocytes. In addition, EGCG inhibited the expression of inducible nitric oxide synthase in cocultured macrophages and peroxisome proliferator-activated receptor-gamma in cocultured adipocytes. Furthermore, the HO-1 expression showed an approximately 4-fold increase in cocultured adipocytes and an approximately 6-fold increase in cocultured macrophages. Lastly, HO-1 silencing induced NO generation in cocultured cells regardless of EGCG treatment. These results indicate that EGCG inhibited inflammatory responses by suppressing the production of proinflammatory cytokines through HO-1 induction during adipocyte-macrophage interaction.

Troglitazone Enhances the Apoptotic Response of DLD-1 Colon Cancer Cells to Photodynamic Therapy

PURPOSE

The aim of this study was to investigate whether the peroxisomal proliferator-activated receptor gamma (PPARγ) ligand troglitazone in combination with photodynamic therapy (PDT) enhances the apoptotic response of DLD-1 colon cancer cells.

MATERIALS AND METHODS

The effects of troglitazone, PDT, and troglitazone in combination with PDT on cell viability and apoptosis were assessed in DLD-1 cells. Cell viability and proliferation were evaluated using the tetrazolium-based MTT assay, and apoptosis was evaluated via cell staining with propidium iodide (PI) and annexin V-FITC. The levels of pro-caspase-3 were measured via Western blot analyses.

RESULTS

Treatment of troglitazone and PDT induced the growth retardation and cell death of DLD-1 cells in a dose-dependent manner, respectively. The combination treatment significantly suppressed cell growth and increased the apoptotic response of DLD-1 and resulted in apoptosis rather than necrosis, as shown by PI/annexin V staining and degradation of procaspase-3.

CONCLUSION

These results document the anti-proliferative and apoptotic activities of PDT in combination with the PPARγ ligand troglitazone and provide a strong rationale for testing the therapeutic potential of combination treatment in colon cancer.

Current classification, treatment options, and new perspectives in the management of adipocytic sarcomas

Sarcomas are a heterogeneous group of mesenchymal tumors arising from soft tissue or bone, with an uncertain etiology and difficult classification. Soft tissue sarcomas (STSs) account for around 1% of all adult cancers. Till date, more than 50 histologic subtypes have been identified. Adipocyte sarcoma or liposarcoma (LPS) is one of the most common STS subtypes, accounting for 15% of all sarcomas, with an incidence of 24% of all extremity STSs and 45% of all retroperitoneal STSs. The new World Health Organization classification system has divided LPS into four different subgroups: atypical lipomatous tumor/well-differentiated LPS, dedifferentiated LPS, myxoid LPS, and pleomorphic LPS. These lesions can develop at any location and exhibit different aggressive potentials reflecting their morphologic diversity and clinical behavior. Patients affected by LPS should be managed in specialized multidisciplinary cancer centers. Whereas surgical resection is the mainstay of treatment for localized disease, the benefits of adjuvant and neoadjuvant chemotherapy are still unclear. Systemic treatment, particularly chemotherapy, is still limited in metastatic disease. Despite the efforts toward a better understanding of the biology of LPS, the outcome of advanced and metastatic patients remains poor. The advent of targeted therapies may lead to an improvement of treatment options and clinical outcomes. A larger patient enrollment into translational and clinical studies will help increase the knowledge of the biological behavior of LPSs, test new drugs, and introduce new methodological studies, that is, on treatment response.

PPAR Gamma in Neuroblastoma: The Translational Perspectives of Hypoglycemic Drugs

Neuroblastoma (NB) is the most common and aggressive pediatric cancer, characterized by a remarkable phenotypic diversity and high malignancy. The heterogeneous clinical behavior, ranging from spontaneous remission to fatal metastatic disease, is attributable to NB biology and genetics. Despite major advances in therapies, NB is still associated with a high morbidity and mortality. Thus, novel diagnostic, prognostic, and therapeutic approaches are required, mainly to improve treatment outcomes of high-risk NB patients. Among neuroepithelial cancers, NB is the most studied tumor as far as PPAR ligands are concerned. PPAR ligands are endowed with antitumoral effects, mainly acting on cancer stem cells, and constitute a possible add-on therapy to antiblastic drugs, in particular for NB with unfavourable prognosis. While discussing clinical background, this review will provide a synopsis of the major studies about PPAR expression in NB, focusing on the potential beneficial effects of hypoglycemic drugs, thiazolidinediones and metformin, to reduce the occurrence of relapses as well as tumor regrowth in NB patients.

Macrophage PPARγ inhibits Gpr132 to mediate the anti-tumor effects of rosiglitazone

Tumor-associated macrophage (TAM) significantly contributes to cancer progression. Human cancer is enhanced by PPARγ loss-of-function mutations, but inhibited by PPARγ agonists such as TZD diabetes drugs including rosiglitazone. However, it remains enigmatic whether and how macrophage contributes to PPARγ tumor-suppressive functions. Here we report that macrophage PPARγ deletion in mice not only exacerbates mammary tumor development but also impairs the anti-tumor effects of rosiglitazone. Mechanistically, we identify Gpr132 as a novel direct PPARγ target in macrophage whose expression is enhanced by PPARγ loss but repressed by PPARγ activation. Functionally, macrophage Gpr132 is pro-inflammatory and pro-tumor. Genetic Gpr132 deletion not only retards inflammation and cancer growth but also abrogates the anti-tumor effects of PPARγ and rosiglitazone. Pharmacological Gpr132 inhibition significantly impedes mammary tumor malignancy. These findings uncover macrophage PPARγ and Gpr132 as critical TAM modulators, new cancer therapeutic targets, and essential mediators of TZD anti-cancer effects.

DOI:http://dx.doi.org/10.7554/eLife.18501.001

The immune system can both contribute to cancer progression and restrain the growth of tumors. Some immune cells – called macrophages – create an inflammatory environment around a tumor, which can support the spread of the cancer cells.

Independent observations and experiments have shown that a protein called PPARγ can suppress the development and growth of tumors. Drugs called thiazolidinediones (or TZDs for short), which are normally used to treat type 2 diabetes, activate PPARγ and therefore have anti-tumor effects. However, it is not fully understood how PPARγ and TZDs suppress tumor development.

Cheng et al. hypothesized that the PPARγ protein and TZDs can inhibit the activity of the inflammatory macrophages that help tumors to develop. To test this, mice were genetically engineered so that their macrophages could not produce the PPARγ protein. These engineered mice were more likely to develop breast cancer than normal. Furthermore, the breast tumors in the modified mice did not shrink when they were treated with TZDs, whereas the tumors of normal mice did.

Cheng et al. also found that PPARγ inhibits the ability of macrophages to produce a protein called Gpr132, which itself contributes to inflammation and allows breast cancer cells to grow. Mice that were unable to produce Grp132 displayed less inflammation, and cancer growth was blocked. Drugs that inhibited the activity of Grp132 in normal mice also reduced the ability of breast tumors to spread.

Future experiments will need to examine exactly how the Gpr132 proteins produced by macrophages communicate with the cancer cells. Furthermore, developing new drugs that can inhibit Gpr132 could ultimately lead to more effective treatments for cancer.

DOI:http://dx.doi.org/10.7554/eLife.18501.002

Notch activation drives adipocyte dedifferentiation and tumorigenic transformation in mice

Adipocyte-specific activation of Notch signaling suppresses lipid metabolism pathways that provide ligands to Pparγ, leading to adipocyte dedifferentiation and development of liposarcomas (LPSs) resembling human dedifferentiated LPSs with complete penetrance. Pparγ ligand supplementation prevents liposarcoma development.

Liposarcomas (LPSs) are the most common soft-tissue cancer. Because of the lack of animal models, the cellular origin and molecular regulation of LPS remain unclear. Here, we report that mice with adipocyte-specific activation of Notch signaling (Ad/N1ICD) develop LPS with complete penetrance. Lineage tracing confirms the adipocyte origin of Ad/N1ICD LPS. The Ad/N1ICD LPS resembles human dedifferentiated LPS in histological appearance, anatomical localization, and gene expression signature. Before transformation, Ad/N1ICD adipocytes undergo dedifferentiation that leads to lipodystrophy and metabolic dysfunction. Although concomitant Pten deletion normalizes the glucose metabolism of Ad/N1ICD mice, it dramatically accelerates the LPS prognosis and malignancy. Transcriptomes and lipidomics analyses indicate that Notch activation suppresses lipid metabolism pathways that supply ligands to Pparγ, the master regulator of adipocyte homeostasis. Accordingly, synthetic Pparγ ligand supplementation induces redifferentiation of Ad/N1ICD adipocytes and tumor cells, and prevents LPS development in Ad/N1ICD mice. Importantly, the Notch target HES1 is abundantly expressed in human LPS, and Notch inhibition suppresses the growth of human dedifferentiated LPS xenografts. Collectively, ectopic Notch activation is sufficient to induce dedifferentiation and tumorigenic transformation of mature adipocytes in mouse.

Commonalities in the Association between PPARG and Vitamin D Related with Obesity and Carcinogenesis

The PPAR nuclear receptor family has acquired great relevance in the last decade, which is formed by three different isoforms (PPARα, PPARβ/δ, and PPAR ϒ). Those nuclear receptors are members of the steroid receptor superfamily which take part in essential metabolic and life-sustaining actions. Specifically, PPARG has been implicated in the regulation of processes concerning metabolism, inflammation, atherosclerosis, cell differentiation, and proliferation. Thus, a considerable amount of literature has emerged in the last ten years linking PPARG signalling with metabolic conditions such as obesity and diabetes, cardiovascular disease, and, more recently, cancer. This review paper, at crossroads of basic sciences, preclinical, and clinical data, intends to analyse the last research concerning PPARG signalling in obesity and cancer. Afterwards, possible links between four interrelated actors will be established: PPARG, the vitamin D/VDR system, obesity, and cancer, opening up the door to further investigation and new hypothesis in this fascinating area of research.

Clinical relevance of peroxisome proliferator-activated receptor-gamma expression in myxoid liposarcoma

Background

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that belongs to the nuclear hormone receptor superfamily. PPARγ is essential in adipocyte differentiation from precursor cells. Its antitumorigenic effects are reported in certain malignancies; however, its effects in liposarcoma are unclear.

Methods

We analyzed PPARγ expression using immunohistochemistry (IHC) in 46 patients with myxoid liposarcoma [MLS; median age, 47 years (range, 14–90 years) and mean follow-up period, 91 months (range, 13–358 months)]. PPARγ mRNA expression levels were measured by quantitative reverse transcription polymerase chain reaction. Further, we evaluated the correlation of PPARγ expression with clinical outcomes.

Results

We found that the metastasis-free survival rate was significantly higher in lower PPARγ expressers [34 patients with labeling index (LI) <50 %] than in higher expressers (12 patients with LI ≥50 %; p = 0.01). Cox multivariate analysis revealed that a higher PPARγ level was an independent predictor of metastasis (relative risk = 6.945, p = 0.026). Furthermore, using 28 fresh MLS specimens, we confirmed an increased PPARγ mRNA expression level in the higher LI group (p = 0.001).

Conclusions

In this study, higher PPARγ expression in MLS was a risk factor associated with distant metastasis; therefore, it would be a novel prognostic marker for MLS. Further analyses will help to understand the correlation between PPARγ expression and tumor malignancy in liposarcoma.

The role of PPARγ-mediated signalling in skin biology and pathology: new targets and opportunities for clinical dermatology

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that modulate the expression of multiple different genes involved in the regulation of lipid, glucose and amino acid metabolism. PPARs and cognate ligands also regulate important cellular functions, including cell proliferation and differentiation, as well as inflammatory responses. This includes a role in mediating skin and pilosebaceous unit homoeostasis: PPARs appear to be essential for maintaining skin barrier permeability, inhibit keratinocyte cell growth, promote keratinocyte terminal differentiation and regulate skin inflammation. They also may have protective effects on human hair follicle (HFs) epithelial stem cells, while defects in PPARγ-mediated signalling may promote the death of these stem cells and thus facilitate the development of cicatricial alopecia (lichen planopilaris). Overall, however, selected PPARγ modulators appear to act as hair growth inhibitors that reduce the proliferation and promote apoptosis of hair matrix keratinocytes. The fact that commonly prescribed PPARγ-modulatory drugs of the thiazolidine-2,4-dione class can exhibit a battery of adverse cutaneous effects underscores the importance of distinguishing beneficial from clinically undesired cutaneous activities of PPARγ ligands and to better understand on the molecular level how PPARγ-regulated cutaneous lipid metabolism and PPARγ-mediated signalling impact on human skin physiology and pathology. Surely, the therapeutic potential that endogenous and exogenous PPARγ modulators may possess in selected skin diseases, ranging from chronic inflammatory hyperproliferative dermatoses like psoriasis and atopic dermatitis, via scarring alopecia and acne can only be harnessed if the complexities of PPARγ signalling in human skin and its appendages are systematically dissected.

Functional activation of PPARγ in human upper aerodigestive cancer cell lines

Upper aerodigestive cancer is an aggressive malignancy with relatively stagnant long-term survival rates over 20 yr. Recent studies have demonstrated that exploitation of PPARγ pathways may be a novel therapy for cancer and its prevention. We tested whether PPARγ is expressed and inducible in aerodigestive carcinoma cells and whether it is present in human upper aerodigestive tumors. Human oral cancer CA-9-22 and NA cell lines were treated with the PPAR activators eicosatetraynoic acid (ETYA), 15-deoxy-δ- 12,14-prostaglandin J2 (PG-J2), and the thiazolidinedione, ciglitazone, and evaluated for their ability to functionally activate PPARγ luciferase reporter gene constructs. Cellular proliferation and clonogenic potential after PPARγ ligand treatment were also evaluated. Aerodigestive cancer specimens and normal tissues were evaluated for PPARγ expression on gene expression profiling and immunoblotting. Functional activation of PPARγ reporter gene constructs and increases in PPARγ protein were confirmed in the nuclear compartment after PPARγ ligand treatment. Significant decreases in cell proliferation and clonogenic potential resulted from treatment. Lipid accumulation was induced by PPARγ activator treatment. 75% of tumor specimens and 100% of normal control tissues expressed PPARγ RNA, and PPARγ protein was confirmed in 66% of tumor specimens analyzed by immunoblotting. We conclude PPARγ can be functionally activated in upper aerodigestive cancer and that its activation downregulates several features of the neoplastic phenotype. PPARγ expression in human upper aerodigestive tract tumors and normal cells potentially legitimizes it as a novel intervention target in this disease. © 2016 Wiley Periodicals, Inc.

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.

Cell Systems to Investigate the Impact of Polyphenols on Cardiovascular Health

Polyphenols are a diverse group of micronutrients from plant origin that may serve as antioxidants and that contribute to human health in general. More specifically, many research groups have investigated their protective effect against cardiovascular diseases in several animal studies and human trials. Yet, because of the excessive processing of the polyphenol structure by human cells and the residing intestinal microbial community, which results in a large variability between the test subjects, the exact mechanisms of their protective effects are still under investigation. To this end, simplified cell culture systems have been used to decrease the inter-individual variability in mechanistic studies. In this review, we will discuss the different cell culture models that have been used so far for polyphenol research in the context of cardiovascular diseases. We will also review the current trends in cell culture research, including co-culture methodologies. Finally, we will discuss the potential of these advanced models to screen for cardiovascular effects of the large pool of bioactive polyphenols present in foods and their metabolites.

PPARγ activation following apoptotic cell instillation promotes resolution of lung inflammation and fibrosis via regulation of efferocytosis and proresolving cytokines

Changes in macrophage phenotype have been implicated in apoptotic cell-mediated immune modulation via induction of peroxisome proliferator-activated receptor-γ (PPARγ). In this study, we characterized PPARγ induction by apoptotic cell instillation over the course of bleomycin-induced lung injury in C57BL/6 mice. Next, the role of PPARγ activation in resolving lung inflammation and fibrosis was investigated. Our data demonstrate that apoptotic cell instillation after bleomycin results in immediate and prolonged enhancement of PPARγ mRNA and protein in alveolar macrophages and lung. Moreover, PPARγ activity and expression of its target molecules, including CD36, macrophage mannose receptor, and arginase 1, were persistently enhanced following apoptotic cell instillation. Coadministration of the PPARγ antagonist, GW9662, reversed the enhanced efferocytosis, and the reduced proinflammatory cytokine expression, neutrophil recruitment, myeloperoxidase activity, hydroxyproline contents, and fibrosis markers, including type 1 collagen α2, fibronectin and α-smooth muscle actin (α-SMA), in the lung by apoptotic cell instillation. In addition, inhibition of PPARγ activity reversed the expression of transforming growth factor-β (TGF-β), interleukin (IL)-10, and hepatocyte growth factor (HGF). These findings indicate that one-time apoptotic cell instillation contributes to anti-inflammatory and antifibrotic responses via upregulation of PPARγ expression and subsequent activation, leading to regulation of efferocytosis and production of proresolving cytokines.

Epigenetic Activity of Peroxisome Proliferator-Activated Receptor Gamma Agonists Increases the Anticancer Effect of Histone Deacetylase Inhibitors on Multiple Myeloma Cells

Epigenetic modifications play a major role in the development of multiple myeloma. We have previously reported that the PPARγ agonist pioglitazone (PIO) enhances, in-vitro, the cytotoxic effect of the Histone deacetylase inhibitor (HDACi), valproic acid (VPA), on multiple myeloma cells. Here, we described the development of a new multiple myeloma mouse model using MOLP8 cells, in order to evaluate the effect of VPA/PIO combination on the progression of myeloma cells, by analyzing the proliferation of bone marrow plasma cells. We showed that VPA/PIO delays the progression of the disease and the invasion of myeloma cells in the bone marrow. Mechanistically, we demonstrated that VPA/PIO increases the cleavage of caspase 3 and PARP, and induces the acetylation of Histone 3 (H3). Furthermore, we provided evidence that PPARγ agonist is able to enhance the action of other HDACi such as Vorinostat or Mocetinostat. Using PPARγ antagonist or siPPARγ, we strongly suggest that, as described during adipogenesis, PIO behaves as an epigenetic regulator by improving the activity of HDACi. This study highlights the therapeutic benefit of PIO/VPA combination, compared to VPA treatment as a single-arm therapy on multiple myeloma and further highlights that such combination may constitute a new promising treatment strategy which should be supported by clinical trials.

Differential expression of cyclin G2, cyclin-dependent kinase inhibitor 2C and peripheral myelin protein 22 genes during adipogenesis

Increase of fat cells (FCs) in adipose tissue is attributed to proliferation of preadipocytes or immature adipocytes in the early stage, as well as adipogenic differentiation in the later stage of adipose development. Although both events are involved in the FC increase, they are contrary to each other, because the former requires cell cycle activity, whereas the latter requires cell cycle withdrawal. Therefore, appropriate regulation of cell cycle inhibition is critical to adipogenesis. In order to explore the important cell cycle inhibitors and study their expression in adipogenesis, we adopted a strategy combining the Gene Expression Omnibus (GEO) database available on the NCBI website and the results of quantitative real-time PCR (qPCR) data in porcine adipose tissue. Three cell cycle inhibitors - cyclin G2 (CCNG2), cyclin-dependent kinase inhibitor 2C (CDKN2C) and peripheral myelin protein (PMP22) - were selected for study because they are relatively highly expressed in adipose tissue compared with muscle, heart, lung, liver and kidney in humans and mice based on two GEO DataSets (GDS596 and GDS3142). In the latter analysis, they were found to be more highly expressed in differentiating/ed preadipocytes than in undifferentiated preadipocytes in human and mice as shown respectively by GDS2366 and GDS2743. In addition, GDS2659 also suggested increasing expression of the three cell cycle inhibitors during differentiation of 3T3-L1 cells. Further study with qPCR in Landrace pigs did not confirm the high expression of these genes in adipose tissue compared with other tissues in market-age pigs, but confirmed higher expression of these genes in FCs than in the stromal vascular fraction, as well as increasing expression of these genes during in vitro adipogenic differentiation and in vivo development of adipose tissue. Moreover, the relatively high expression of CCNG2 in adipose tissue of market-age pigs and increasing expression during development of adipose tissue was also confirmed at the protein level by western blot analysis. Based on the analysis of the GEO DataSets and results of qPCR and Western blotting we conclude that all three cell cycle inhibitors may inhibit adipocyte proliferation, but promote adipocyte differentiation and hold a differentiated state by inducing and maintaining cell cycle inhibition. Therefore, their expression in adipose tissue is positively correlated with age and mature FC number. By regulating the expression of these genes, we may be able to control FC number, and, thus, reduce excessive fat tissue in animals and humans.

Pioglitazone treatment increases survival and prevents body weight loss in tumor-bearing animals: possible anti-cachectic effect

Cachexia is a multifactorial syndrome characterized by profound involuntary weight loss, fat depletion, skeletal muscle wasting, and asthenia; all symptoms are not entirely attributable to inadequate nutritional intake. Adipose tissue and skeletal muscle loss during cancer cachexia development has been described systematically. The former was proposed to precede and be more rapid than the latter, which presents a means for the early detection of cachexia in cancer patients. Recently, pioglitazone (PGZ) was proposed to exhibit anti-cancer properties, including a reduction in insulin resistance and adipose tissue loss; nevertheless, few studies have evaluated its effect on survival. For greater insight into a potential anti-cachectic effect due to PGZ, 8-week-old male Wistar rats were subcutaneously inoculated with 1 mL (2×10⁷) of Walker 256 tumor cells. The animals were randomly assigned to two experimental groups: TC (tumor + saline-control) and TP5 (tumor + PGZ/5 mg). Body weight, food ingestion and tumor growth were measured at baseline and after removal of tumor on days 7, 14 and 26. Samples from different visceral adipose tissue (AT) depots were collected on days 7 and 14 and stored at -80o C (5 to 7 animals per day/group). The PGZ treatment showed an increase in the survival average of 27.3% (P< 0.01) when compared to TC. It was also associated with enhanced body mass preservation (40.7 and 56.3%, p< 0.01) on day 14 and 26 compared with the TC group. The treatment also reduced the final tumor mass (53.4%, p<0.05) and anorexia compared with the TC group during late-stage cachexia. The retroperitoneal AT (RPAT) mass was preserved on day 7 compared with the TC group during the same experimental period. Such effect also demonstrates inverse relationship with tumor growth, on day 14. Gene expression of PPAR-γ, adiponectin, LPL and C/EBP-α from cachectic rats was upregulated after PGZ. Glucose uptake from adipocyte cells (RPAT) was entirely re-established due to PGZ treatment. Taken together, the results demonstrate beneficial effects of PGZ treatment at both the early and final stages of cachexia.

Chemotherapy and chemoprevention by thiazolidinediones

Thiazolidinediones (TZDs) are synthetic ligands of Peroxisome-Proliferator-Activated Receptor gamma (PPARγ). Troglitazone, rosiglitazone, and pioglitazone have been approved for treatment of diabetes mellitus type II. All three compounds, together with the first TZD ciglitazone, also showed an antitumor effect in preclinical studies and a beneficial effect in some clinical trials. This review summarizes hypotheses on the role of PPARγ in tumors, on cellular targets of TZDs, antitumor effects of monotherapy and of TZDs in combination with other compounds, with a focus on their role in the treatment of differentiated thyroid carcinoma. The results of chemopreventive effects of TZDs are also considered. Existing data suggest that the action of TZDs is highly complex and that actions do not correlate with cellular PPARγ expression status. Effects are cell-, species-, and compound-specific and concentration-dependent. Data from human trials suggest the efficacy of TZDs as monotherapy in prostate cancer and glioma and as chemopreventive agent in colon, lung, and breast cancer. TZDs in combination with other therapies might increase antitumor effects in thyroid cancer, soft tissue sarcoma, and melanoma.

Genistein exerts growth inhibition on human osteosarcoma MG-63 cells via PPARγ pathway

The peroxisome proliferator-activated receptor γ (PPARγ) is emerging as an important regulator in various metabolic processes of cancer. Genistein, as a major isoflavonoid isolated from dietary soybean, possesses a wide variety of biological activities, particularly, in cancer prevention. However, the mechanisms by which genistein elicits its growth inhibiting effects in osteosarcoma (OS) MG-63 cells have not been extensively elucidated. MG-63 cells were treated for 2 days with various concentrations of genistein and/or GW9662 (a selective antagonist of PPARγ). The effect of different drugs on cell viability was determined by Cell Counting Kit-8 (CCK-8). The assay of cell proliferation was performed using 5-ethynyl-2'-deoxyuridine (EdU). The changes of apoptosis and cell cycle progression were detected by flow cytometry experiments. The protein expression of PPARγ pathway (PPARγ, PTEN, BCL-2, Survivin, P21WAF1/CIP1 and Cyclin B1) was determined by western blot analysis. The expression of PPARγ and PTEN mRNA was detected by real-time quantitative RT-PCR analysis. We report that genistein caused OS cell growth inhibition. We found that the PPARγ expression in OS cells increased after genistein treatment. Further studies on the mechanisms of genistein revealed a series of cell growth changes related to the PPARγ pathway; while cell cycle changes can be reversed by GW9662. Genistein plays an important role in preventing OS cell growth, which can impede the OS cell cycle as a non-toxic activator of PPARγ, providing novel insights into the mechanisms of the therapeutic activities of genistein.

Development of Small Molecules Targeting the Wnt Signaling Pathway in Cancer Stem Cells for the Treatment of Colorectal Cancer

Colorectal cancer (CRC) was ranked third in morbidity and mortality in the United States in 2013. Although substantial progress has been made in surgical techniques and postoperative chemotherapy in recent years, the prognosis for colon cancer is still not satisfactory, mainly because of cancer recurrence and metastasis. The latest studies have shown that cancer stem cells (CSCs) play important roles in cancer recurrence and metastasis. Drugs that target CSCs might therefore have great therapeutic potential in prevention of cancer recurrence and metastasis. The wingless-int (Wnt) signaling pathway in CSCs has been suggested to play crucial roles in colorectal carcinogenesis, and has become a popular target for anti-CRC therapy. Dysregulation of the Wnt signaling pathway, mostly by inactivating mutations of the adenomatous polyposis coli tumor suppressor or oncogenic mutations of β-catenin, has been implicated as a key factor in colorectal tumorigenesis. Abnormal increases of β-catenin levels represents a common pathway in Wnt signaling activation and is also observed in other human malignancies. These findings highlight the importance of developing small-molecule drugs that target the Wnt pathway. Herein we provide an overview on the current development of small molecules that target the Wnt pathway in colorectal CSCs and discuss future research directions.

Extensive lipoma-like changes of myxoid liposarcoma: morphologic, immunohistochemical, and molecular cytogenetic analyses

Myxoid liposarcomas (MLSs) with extensive lipoma-like changes (MLSLC) are rare, and it is often difficult to distinguish them from well-differentiated liposarcoma (LS)/dedifferentiated LS (WDLS/DDLS) with myxoid changes. For the characterization of these neoplasms, we studied 8 MLSLCs, 11 ordinary MLSs, 4 WDLSs, and 6 DDLSs. Cytogenetically, MLSLC and ordinary MLS were characterized by t(12;16)(q13;p11) and FUS-DDIT3 fusion gene, whereas WDLS/DDLS lacked the fusion gene but possessed giant marker/ring chromosomes. Both lipoma-like and myxoid components of the same MLSLC exhibited the identical FUS-DDIT3, as confirmed by fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemically, MDM2 and CDK4 were positive in WDLS/DDLS but negative in MLSLC and ordinary MLS. PPARγ, C/EBPα, adipophilin, and perilipin were found in each type of LS. Adipophilin was expressed chiefly in tiny fat droplets of immature lipoblasts, whereas perilipin showed a strong positive staining in large fat vacuoles of signet ring and multivacuolated lipoblasts. The Ki-67 labeling index was lower in the lipoma-like component of MLSLC when compared with the myxoid component of the same tumors as well as ordinary MLS (p < 0.001). When compared with ordinary MLS, MLSLC may be less aggressive in clinical behavior (rare recurrences or metastases) after a wide surgical excision. In conclusion, the distinction between MLSLC and WDLS/DDLS is important, because of the differences of molecular cytogenetic features as well as clinical behaviors between these distinct sarcomas presenting similar morphologic features. In addition, the combined immunohistochemical detection of adipophilin and perilipin may provide a useful ancillary tool for identification of lipoblastic cells in soft tissue sarcomas.

Advances in the targeted therapy of liposarcoma

Liposarcoma (LPS) is the most common type of soft-tissue sarcoma. Complete surgical resection is the only curative means for localized disease; however, both radiation and conventional cytotoxic chemotherapy remain controversial for metastatic or unresectable disease. An increasing number of trials with novel targeted therapy of LPS have provided encouraging data during recent years. This review will provide an overview of the advances in our understanding of LPS and summarize the results of recent trials with novel therapies targeting different genetic and molecular aberrations for different subtypes of LPS.

New nanocomposite-graphene pastes based stochastic microsensors

Stochastic sensors based on metal nanocomposites-graphene pastes modified with protoporphyrin-IX were used for the assay of PPAR-γ in cerebrospinal liquid.

Pleiotropic role of PPARγ in intracerebral hemorrhage: an intricate system involving Nrf2, RXR, and NF-κB

Intracerebral hemorrhage (ICH) is a subtype of stroke involving formation of hematoma within brain parenchyma, which accounts for 8-15% of all strokes in Western societies and 20-30% among Asian populations, and has a 1-year mortality rate >50%. The high mortality and severe morbidity make ICH a major public health problem. Only a few evidence-based targeted treatments are used for ICH management, and interventions focus primarily on supportive care and comorbidity prevention. Even in patients who survive the ictus, extravasated blood (including plasma components) and subsequent intrahematoma hemolytic products trigger a series of adverse events within the brain parenchyma, leading to secondary brain injury, edema and severe neurological deficits or death. Although the hematoma in humans gradually resolves within months, full restoration of neurological function can be slow and often incomplete, leaving survivors with devastating neurological deficits. During past years, peroxisome proliferator-activated receptor gamma (PPARγ) transcription factor and its agonists received recognition as important players in regulating not only glucose and lipid metabolism (which underlies its therapeutic effect in type 2 diabetes mellitus), and more recently, as an instrumental pleiotropic regulator of antiinflammation, antioxidative regulation, and phagocyte-mediated cleanup processes. PPARγ agonists have emerged as potential therapeutic target for stroke. The use of PPARγ as a therapeutic target appears to have particularly strong compatibility toward pathogenic components of ICH. In addition to its direct genomic effect, PPARγ may interact with transcription factor, NF-κB, which may underlie many aspects of the antiinflammatory effect of PPARγ. Furthermore, PPARγ appears to regulate expression of Nrf2, another transcription factor and master regulator of detoxification and antioxidative regulation. Finally, the synergistic costimulation of PPARγ and retinoid X receptor, RXR, may play an additional role in the therapeutic modulation of PPARγ function. In this article, we outline the main components of the role of PPARγ in ICH pathogenesis.

Pax-8-PPAR-γ fusion protein in thyroid carcinoma

Thyroid carcinoma is the most common endocrine malignancy, and its incidence is continuing to increase. Most thyroid carcinomas contain one of several known driver mutations, such as the Val600Glu substitution in B-Raf, Ras mutations, RET gene fusions, or PAX8-PPARG gene fusions. The PAX8-PPARG gene fusion results in the production of a Pax-8-PPAR-γ fusion protein (PPFP), which is found in approximately one-third of follicular thyroid carcinomas, as well as some follicular-variant papillary thyroid carcinomas. In vitro and in vivo evidence indicates that PPFP is an oncoprotein. Although specific mechanisms of action remain to be defined, PPFP is considered to act as a dominant-negative inhibitor of wild-type PPAR-γ and/or as a unique transcriptional activator of subsets of PPAR-γ-responsive and Pax-8-responsive genes. Detection of the fusion transcript in thyroid nodule biopsy specimens can aid clinical decision-making when cytological findings are indeterminate. The PPAR-γ agonist pioglitazone is highly therapeutic in a transgenic mouse model of PPFP-positive thyroid carcinoma, suggesting that PPAR-γ agonists might be beneficial in patients with PPFP-positive thyroid carcinomas.

Pioglitazone inhibits the proliferation and metastasis of human pancreatic cancer cells

Proliferator-activated receptor-γ (PPAR-γ) is a nuclear receptor that acts as a transcription factor in several types of tissue. PPAR-γ ligands are known to inhibit numerous cancer cell processes, including pancreatic cancer cell proliferation through terminal differentiation. Previous studies concerning the inhibitory effect of PPAR-γ ligands derived from thiazolidinediones (TZDs) on the metastatic potential of cancer cells have been reported. The present study aimed to investigate whether pioglitazone, a prescription TZD class drug and a ligand of PPAR-γ, inhibits the proliferation and metastasis of pancreatic cancer cells. The inhibitory effect of pioglitazone on the proliferation of the Capan-1, Aspc-1, BxPC-3, PANC-1 and MIApaCa-2 pancreatic cancer cell lines was analyzed. Alterations in carcinoembryonic antigen (CEA), interleukin-8 (IL-8) and cyclooxygenase-2 (COX-2) mRNA expression levels subsequent to pioglitazone treatment were examined in BxPC-3 cells by quantitative reverse transcription polymerase chain reaction. In addition, whether the oral administration of pioglitazone prevents tumorigenesis and spontaneous BxPC-3 cell lymph node and lung metastases was investigated using a rectal xenograft model. Pioglitazone treatment resulted in the inhibition of proliferation in all five pancreatic cancer cell lines in vitro. Pioglitazone induced CEA mRNA expression, suppressed IL-8 and COX-2 mRNA expression in vitro, and inhibited BxPC-3 xenograft growth. Pioglitazone also reduced BxPC-3 cell lymph node and lung metastasis in the rectal xenograft model. These results suggest that pioglitazone treatment inhibited the proliferation and metastasis of pancreatic cancer cells through the induction of differentiation and the inhibition of angiogenesis-associated protein expression.

Attenuation of IFN-γ-induced B7-H1 expression by 15-deoxy-delta(12,14)-prostaglandin J2 via downregulation of the Jak/STAT/IRF-1 signaling pathway

AIM

B7-H1, which belongs to the B7 family of costimulatory molecules, is implicated in the ability of tumors to evade the host immune response. The development of evasion mechanisms within the tumor microenvironment may be responsible for poor therapeutic responses. In this manuscript, we report that the 15-deoxy-δ(12,14)-prostaglandin J2 (15d-PGJ2), peroxisome proliferator-activated receptor gamma (PPARγ) activator leads to the downregulation of the cancer-associated expression of B7-H1 in response to interferon-gamma (IFN-γ) and the associated signaling cascades.

MAIN METHODS

The expression of B7-H1 from IFN-γ-induced B16F10 melanoma cells was measured with flow cytometric analysis. The regulatory mechanisms of 15d-PGJ2 on cellular signaling pathways were examined using Western blot and electrophoretic mobility shift assays.

KEY FINDINGS

The flow cytometric analysis revealed that the B7-H1 costimulatory molecule is significantly upregulated in B16F10 melanoma cells by stimulation with IFN-γ. However, 15d-PGJ2 strongly downregulates B7-H1 expression in IFN-γ-stimulated B16F10 melanoma cells. Furthermore, the significant damping effect of 15d-PGJ2 on B7-H1 expression involves the inhibition of the tyrosine phosphorylation of Janus kinase (Jak) and signal transducer(s) and activator(s) of transcription (STAT) and, thereby, the interferon regulatory factor-1 (IRF-1) trans-activation of STAT. These effects of 15d-PGJ2 were not abrogated by the PPARγ antagonist GW9662, indicating that they occur through a PPARγ-independent mechanism.

SIGNIFICANCE

In this study, we demonstrate that 15d-PGJ2 suppresses the IFN-γ-elicited expression of B7-H1 by the inhibition of IRF-1 transcription via the Jak/STAT signaling pathway through a PPARγ-independent mechanism in mouse melanoma cells.

Reprogramming of mesenchymal stem cells by oncogenes

Mesenchymal stem cells (MSCs) originate from embryonic mesoderm and give rise to the multiple lineages of connective tissues. Transformed MSCs develop into aggressive sarcomas, some of which are initiated by specific chromosomal translocations that generate fusion proteins with potent oncogenic properties. The sarcoma oncogenes typically prime MSCs through aberrant reprogramming. They dictate commitment to a specific lineage but prevent mature differentiation, thus locking the cells in a state of proliferative precursors. Deregulated expression of lineage-specific transcription factors and controllers of chromatin structure play a central role in MSC reprogramming and sarcoma pathogenesis. This suggests that reversing the epigenetic aberrancies created by the sarcoma oncogenes with differentiation-related reagents holds great promise as a beneficial addition to sarcoma therapies.

Anthracycline-based chemotherapy in extraskeletal myxoid chondrosarcoma: a retrospective study

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare subgroup within soft tissue sarcomas. Its sensitivity to chemotherapy is reported to be low.

METHODS

We retrospectively reviewed a series of 11 EMC patients treated as from 2001 within the Italian Rare Cancer Network (RCN) with anthracycline-based chemotherapy. Pathologic diagnosis was centrally reviewed in all cases and confirmed by the presence of the specific chromosomal rearrangements, involving the NR4A3 gene locus on chromosome 9.

RESULTS

Eleven patients treated with anthracycline-based chemotherapy were included (M/F: 9/2 - mean age: 52 years - site of primary: lower limb/other = 9/2 - metastatic = 11 - front line/ further line = 10/1 - anthracycline as single agent/ combined with ifosfamide = 1/10). Ten patients are evaluable for response. Overall, best response according to RECIST was: partial response (PR) = 4 (40 %), stable disease (SD) = 3, progressive disease (PD) = 3 cases. Median PFS was 8 (range 2-10) months.

CONCLUSIONS

By contrast to what reported so far, anthracycline-based chemotherapy is active in a distinct proportion of EMC patients.

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.

Stemness and inducing differentiation of small cell lung cancer NCI-H446 cells

Small cell lung cancer (SCLC) accounts for nearly 15% of human lung cancers and is one of the most aggressive solid tumors. The SCLC cells are thought to derive from self-renewing pulmonary neuroendocrine cells by oncogenic transformation. However, whether the SCLC cells possess stemness and plasticity for differentiation as normal stem cells has not been well understood thus far. In this study, we investigated the expressions of multilineage stem cell markers in the cancer cells of SCLC cell line (NCI-H446) and analyzed their clonogenicity, tumorigenicity, and plasticity for inducing differentiation. It has been found that most cancer cells of the cell line expressed multilineage stem cell markers under the routine culture conditions and generated single-cell clones in anchorage-dependent or -independent conditions. These cancer cells could form subcutaneous xenograft tumors and orthotopic lung xenograft tumors in BALB/C-nude mice. Most cells in xenograft tumors expressed stem cell markers and proliferation cell nuclear antigen Ki67, suggesting that these cancer cells remained stemness and highly proliferative ability in vivo. Intriguingly, the cancer cells could be induced to differentiate into neurons, adipocytes, and osteocytes, respectively, in vitro. During the processes of cellular phenotype-conversions, autophagy and apoptosis were two main metabolic events. There is cross-talking between autophagy and apoptosis in the differentiated cancer cells. In addition, the effects of the inhibitor and agonist for Sirtuin1/2 on the inducing osteogenic differentiation indicated that Sirtuin1/2 had an important role in this process. Taken together, these results indicate that most cancer cells of NCI-H446 cell line possess stemness and plasticity for multilineage differentiation. These findings have potentially some translational applications in treatments of SCLC with inducing differentiation therapy.

Novel systemic therapies in advanced liposarcoma: a review of recent clinical trial results

Liposarcoma is one of the most common adult soft tissue sarcomas an consists of three histologic subtypes (well and dedifferentiated, myxoid/round cell, and pleomorphic). Surgery is the mainstay of treatment for localized disease; however for unresectable or metastatic disease, effective treatment options are currently limited. In the past decade, a better understanding of the distinct genetic and molecular aberrations for each of the three histologic subtypes has led to the development of several novel systemic therapies. Data from phase I and early phase II clinical trials have been reported. Despite challenges with conducting clinical trials in liposarcoma, preliminary results for several of these novel, biology-driven therapies are encouraging.

The PPARγ agonist efatutazone increases the spectrum of well-differentiated mammary cancer subtypes initiated by loss of full-length BRCA1 in association with TP53 haploinsufficiency

Peroxisome proliferator-activated receptor gamma (PPARγ) agonists have anticancer activity and influence cell differentiation. We examined the impact of the selective PPARγ agonist efatutazone on mammary cancer pathogenesis in a mouse model of BRCA1 mutation. Mice with conditional loss of full-length BRCA1 targeted to mammary epithelial cells in association with germline TP53 insufficiency were treated with efatutazone through the diet starting at age 4 months and were euthanized at age 12 months or when palpable tumor reached 1 cm(3). Although treatment did not reduce percentage of mice developing invasive cancer, it significantly reduced prevalence of noninvasive cancer and total number of cancers per mouse and increased prevalence of well-differentiated cancer subtypes not usually seen in this mouse model. Invasive cancers from controls were uniformly estrogen receptor α negative and undifferentiated, whereas well-differentiated estrogen receptor α-positive papillary invasive cancers appeared in efatutazone-treated mice. Expression levels of phosphorylated AKT and CDK6 were significantly reduced in the cancers developing in efatutazone-treated mice. Efatutazone treatment reduced rates of mammary epithelial cell proliferation and development of hyperplastic alveolar nodules and increased expression levels of the PPARγ target genes Adfp, Fabp4, and Pdhk4 in preneoplastic mammary tissue. Intervention efatutazone treatment in mice with BRCA1 deficiency altered mammary cancer development by promoting development of differentiated invasive cancer and reducing prevalence of noninvasive cancer and preneoplastic disease.

Novel dedifferentiated liposarcoma xenograft models reveal PTEN down-regulation as a malignant signature and response to PI3K pathway inhibition

Liposarcoma is a type of soft tissue sarcoma that exhibits poor survival and a high recurrence rate. Treatment is generally limited to surgery and radiation, which emphasizes the need for better understanding of this disease. Because very few in vivo and in vitro models can reproducibly recapitulate the human disease, we generated several xenograft models from surgically resected human dedifferentiated liposarcoma. All xenografts recapitulated morphological and gene expression characteristics of the patient tumors after continuous in vivo passages. Importantly, xenograftability was directly correlated with disease-specific survival of liposarcoma patients. Thus, the ability for the tumor of a patient to engraft may help identify those patients who will benefit from more aggressive treatment regimens. Gene expression analyses highlighted the association between xenograftability and a unique gene expression signature, including down-regulated PTEN tumor-suppressor gene expression and a progenitor-like phenotype. When treated with the PI3K/AKT/mTOR pathway inhibitor rapamycin alone or in combination with the multikinase inhibitor sorafenib, all xenografts responded with increased lipid content and a more differentiated gene expression profile. These human xenograft models may facilitate liposarcoma research and accelerate the generation of readily translatable preclinical data that could ultimately influence patient care.

Experimental therapies and ongoing clinical trials to slow down progression of ADPKD

The improvement of imaging techniques over the years has contributed to the understanding of the natural history of autosomal dominant polycystic kidney disease, and facilitated the observation of its structural progression. Advances in molecular biology and genetics have made possible a greater understanding of the genetics, molecular, and cellular pathophysiologic mechanisms responsible for its development and have laid the foundation for the development of potential new therapies. Therapies targeting genetic mechanisms in ADPKD have inherent limitations. As a result, most experimental therapies at the present time are aimed at delaying the growth of the cysts and associated interstitial inflammation and fibrosis by targeting tubular epithelial cell proliferation and fluid secretion by the cystic epithelium. Several interventions affecting many of the signaling pathways disrupted in ADPKD have been effective in animal models and some are currently being tested in clinical trials.

Adipocytes: impact on tumor growth and potential sites for therapeutic intervention

The prevalence of obesity has increased dramatically in recent decades, reaching epidemic proportions. It is becoming clear that obesity is associated not only with type 2 diabetes mellitus and cardiovascular disease, but also with multiple types of cancer. Obesity is characterized by impaired adipose tissue function, leading to adipocyte hypertrophy, inflammation, hypoxia and induced angiogenesis, extracellular matrix remodeling and fibrosis as well as additional stress responses. While epidemiological data indicate that obesity is a well-established risk factor for certain malignancies, the molecular mechanisms underlying the link between obesity and cancer are still poorly understood. Recent data implicates systemic and paracrine factors secreted from adipose tissue during the obese state, promoting cancer development and progression. Here, we focus on the obesity-associated adipose tissue remodeling that may not only lead to metabolic complications, but also to a permissive pro-tumorigenic environment. Particular attention is given to the local pro-tumorigenic effects derived from adipocytes that present an important part of the tumor microenvironment of at least some cancers, in an attempt to describe the nature of the major players of the adipocyte-cancer cell crosstalk that dictates to a large extent tumor progression.

Peroxisome proliferator-activated receptor γ agonists induce cell cycle arrest through transcriptional regulation of Kruppel-like factor 4 (KLF4)

Peroxisome proliferator-activated receptor γ (PPARγ), a subgroup of ligand-activated nuclear receptors, plays critical roles in cell cycle regulation, differentiation, apoptosis, and invasion. PPARγ is involved in tumorigenesis and is a potent target for cancer therapy. PPARγ transactivation of KLF4 has been demonstrated in various studies; however, how PPARγ regulates KLF4 expression is not clear. In this study, we reveal that PPARγ regulates the expression of KLF4 by binding directly to the PPAR response element (PPRE) within the KLF4 promoter. The PPRE resides at -1657 to -1669 bp upstream of the KLF4 ATG codon, which is essential for the transactivation of troglitazone-induced KLF4 expression. Furthermore, we found that stable silencing of KLF4 obviously suppressed the G(1)/S arrest and anti-proliferation effects induced by PPARγ ligands. Taken together, our data indicate that up-regulation of KLF4 upon PPARγ activation is mediated through the PPRE in the KLF4 promoter, thus providing further insights into the PPARγ signal transduction pathway as well as a novel cancer therapeutic strategy.

Overcoming challenges of ovarian cancer stem cells: novel therapeutic approaches

Understanding the genetic and molecular mechanisms of ovarian cancer has been the focus of research efforts working toward the greater goal of improving cancer therapy for patients with residual disease after initial treatment with conventional surgery and neoadjuvant chemotherapy. The focus of this review will be centered on new therapeutic strategies based on Cancer Stem Cells studies of chemoresistant subpopulations, the prevention of metastasis, and individualized therapy in order to find the most successful combination of treatments to effectively treat human ovarian cancer. We reviewed recent literature (1993-2011) of novel treatment approaches to ovarian cancer stem cells. As the focus of ovarian cancer investigation has centered on the cancer stem cell model and the complexities that it presents in the development of effective treatments, the future of treating ovarian cancer lies in utilizing individualized treatment systems that include enhancing existing treatments, aiming for novel therapy targets, managing the plasticity of stem cells to induce cellular differentiation, and regulating oncogenic signaling pathways.

Modulation of PPAR-γ by Nutraceutics as Complementary Treatment for Obesity-Related Disorders and Inflammatory Diseases

A direct correlation between adequate nutrition and health is a universally accepted truth. The Western lifestyle, with a high intake of simple sugars, saturated fat, and physical inactivity, promotes pathologic conditions. The main adverse consequences range from cardiovascular disease, type 2 diabetes, and metabolic syndrome to several cancers. Dietary components influence tissue homeostasis in multiple ways and many different functional foods have been associated with various health benefits when consumed. Natural products are an important and promising source for drug discovery. Many anti-inflammatory natural products activate peroxisome proliferator-activated receptors (PPAR); therefore, compounds that activate or modulate PPAR-gamma (PPAR-γ) may help to fight all of these pathological conditions. Consequently, the discovery and optimization of novel PPAR-γ agonists and modulators that would display reduced side effects is of great interest. In this paper, we present some of the main naturally derived products studied that exert an influence on metabolism through the activation or modulation of PPAR-γ, and we also present PPAR-γ-related diseases that can be complementarily treated with nutraceutics from functional foods.

NAADP mediates insulin-stimulated glucose uptake and insulin sensitization by PPARγ in adipocytes

Insulin stimulates glucose uptake through the membrane translocation of GLUT4 and GLUT1. Peroxisome proliferator-activated receptor γ (PPARγ) enhances insulin sensitivity. Here, we demonstrate that insulin stimulates GLUT4 and GLUT1 translocation, and glucose uptake, by activating the signaling pathway involving nicotinic acid adenine dinucleotide phosphate (NAADP), a calcium mobilizer, in adipocytes. We also demonstrate that PPARγ mediates insulin sensitization by enhancing NAADP production through upregulation of CD38, the only enzyme identified for NAADP synthesis. Insulin produced NAADP by both CD38-dependent and -independent pathways, whereas PPARγ produced NAADP by CD38-dependent pathway. Blocking the NAADP signaling pathway abrogated both insulin-stimulated and PPARγ-induced GLUT4 and GLUT1 translocation, thereby inhibiting glucose uptake. CD38 knockout partially inhibited insulin-stimulated glucose uptake. However, CD38 knockout completely blocked PPARγ-induced glucose uptake in adipocytes and PPARγ-mediated amelioration of glucose tolerance in diabetic mice. These results demonstrated that the NAADP signaling pathway is a critical molecular target for PPARγ-mediated insulin sensitization.