Slug/β-catenin-dependent proinflammatory phenotype in hypoxic breast cancer stem cells. Am J Pathol. 2013;183:1688-1697. [PMID: 24036252 DOI: 10.1038/cdd.2011.207]

pH-Triggered Transformable Peptide Nanocarriers Extend Drug Retention for Breast Cancer Combination Therapy

Increasing the penetration and accumulation of antitumor drugs at the tumor site are crucial in chemotherapy. Smaller drug-loaded nanoparticles (NPs) typically exhibit increased tumor penetration and more effective permeation through the nuclear membrane, whereas larger drug-loaded NPs show extended retention at the tumor site. In addition, cancer stem cells (CSCs) have unlimited proliferative potential and are crucial for the onset, progression, and metastasis of cancer. Therefore, a drug-loaded amphiphilic peptide, DDP- and ATRA-loaded Pep1 (DA/Pep1), is designed that self-assembles into spherical NPs upon the encapsulation of cis-diamminedichloroplatinum (DDP) and all-trans retinoic acid (ATRA). In an acidic environment, DA/Pep1 transforms into aggregates containing sheet-like structures, which significantly increases drug accumulation at the tumor site, thereby increasing antitumor effects and inhibiting metastasis. Moreover, although DDP treatment can increase the number of CSCs present, ATRA can induce the differentiation of CSCs in breast cancer to increase the therapeutic effect of DDP. In conclusion, this peptide nanodelivery system that transforms in response to the acidic tumor microenvironment is an extremely promising nanoplatform that suggests a new idea for the combined treatment of tumors.

Roles of PPAR activation in cancer therapeutic resistance: Implications for combination therapy and drug development

Therapeutic resistance is a major obstacle to successful treatment or effective containment of cancer. Peroxisome proliferator-activated receptors (PPARs) play an essential role in regulating energy homeostasis and determining cell fate. Despite of the pleiotropic roles of PPARs in cancer, numerous studies have suggested their intricate relationship with therapeutic resistance in cancer. In this review, we provided an overview of the roles of excessively activated PPARs in promoting resistance to modern anti-cancer treatments, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The mechanisms through which activated PPARs contribute to therapeutic resistance in most cases include metabolic reprogramming, anti-oxidant defense, anti-apoptosis signaling, proliferation-promoting pathways, and induction of an immunosuppressive tumor microenvironment. In addition, we discussed the mechanisms through which activated PPARs lead to multidrug resistance in cancer, including drug efflux, epithelial-to-mesenchymal transition, and acquisition and maintenance of the cancer stem cell phenotype. Preliminary studies investigating the effect of combination therapies with PPAR antagonists have suggested the potential of these antagonists in reversing resistance and facilitating sustained cancer management. These findings will provide a valuable reference for further research on and clinical translation of PPAR-targeting treatment strategies.

Circadian clock and lipid metabolism disorders: a potential therapeutic strategy for cancer

Recent research has emphasized the interaction between the circadian clock and lipid metabolism, particularly in relation to tumors. This review aims to explore how the circadian clock regulates lipid metabolism and its impact on carcinogenesis. Specifically, targeting key enzymes involved in fatty acid synthesis (SREBP, ACLY, ACC, FASN, and SCD) has been identified as a potential strategy for cancer therapy. By disrupting these enzymes, it may be possible to inhibit tumor growth by interfering with lipid metabolism. Transcription factors, like SREBP play a significant role in regulating fatty acid synthesis which is influenced by circadian clock genes such as BMAL1, REV-ERB and DEC. This suggests a strong connection between fatty acid synthesis and the circadian clock. Therefore, successful combination therapy should target fatty acid synthesis in addition to considering the timing and duration of drug use. Ultimately, personalized chronotherapy can enhance drug efficacy in cancer treatment and achieve treatment goals.

LncRNA MAFG-AS1 is involved in human cancer progression

Long noncoding RNAs (lncRNAs) refer to a type of non-protein-coding transcript of more than 200 nucleotides. LncRNAs play fundamental roles in disease development and progression, and lncRNAs are dysregulated in many pathophysiological processes. Thus, lncRNAs may have potential value in clinical applications. The lncRNA, MAF BZIP Transcription Factor G (MAFG)-AS1, is dysregulated in several cancer, including breast cancer, lung cancer, liver cancer, bladder cancer, colorectal cancer, gastric cancer, esophagus cancer, prostate cancer, pancreatic cancer, ovarian cancer, and glioma. Altered MAFG-AS1 levels are also associated with diverse clinical characteristics and patient outcomes. Mechanistically, MAFG-AS1 mediates a variety of cellular processes via the regulation of target gene expression. Therefore, the diagnostic, prognostic, and therapeutic aspects of MAFG-AS1 have been widely explored. In this review, we discuss the expression, major roles, and molecular mechanisms of MAFG-AS1, the relationship between MAFG-AS1 and clinical features of diseases, and the clinical applications of MAFG-AS1.

Peroxisome proliferator-activated receptors as therapeutic target for cancer

Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor family. There are three subtypes of PPARs, including PPAR-α, PPAR-β/δ and PPAR-γ. They are expressed in different tissues and act by regulating the expression of target genes in the form of binding to ligands. Various subtypes of PPAR have been shown to have significant roles in a wide range of biological processes including lipid metabolism, body energy homeostasis, cell proliferation and differentiation, bone formation, tissue repair and remodelling. Recent studies have found that PPARs are closely related to tumours. They are involved in cancer cell growth, angiogenesis and tumour immune response, and are essential components in tumour progression and metastasis. As such, they have become a target for cancer therapy research. In this review, we discussed the current state of knowledge on the involvement of PPARs in cancer, including their role in tumourigenesis, the impact of PPARs in tumour microenvironment and the potential of using PPARs combinational therapy to treat cancer by targeting essential signal pathways, or as adjuvants to boost the effects of current chemo and immunotherapies. Our review highlights the complexity of PPARs in cancer and the need for a better understanding of the mechanism in order to design effective cancer therapies.

The role of NF-κB in breast cancer initiation, growth, metastasis, and resistance to chemotherapy

Breast cancer (BC) is the second most fatal disease and is the prime cause of cancer allied female deaths. BC is caused by aberrant tumor suppressor genes and oncogenes regulated by transcription factors (TFs) like NF-κB. NF-κB is a pro-inflammatory TF that crucially alters the expressions of various genes associated with inflammation, cell progression, metastasis, and apoptosis and modulates a network of genes that underlie tumorigenesis. Herein, we focus on NF-κB signaling pathways, its regulators, and the rationale for targeting NF-κB. This review also includes TFs that maintain NF-κB crosstalk and their roles in promoting angiogenesis and metastasis. In addition, we discuss the importance of combination therapies, resistance to treatment, and potential novel therapeutic strategies including nanomedicine that targets NF-κB.

Peroxisome proliferator-activated receptor-α (PPARα) regulates wound healing and mitochondrial metabolism in the cornea

Diabetes can result in impaired corneal wound healing. Mitochondrial dysfunction plays an important role in diabetic complications. However, the regulation of mitochondria function in the diabetic cornea and its impacts on wound healing remain elusive. The present study aimed to explore the molecular basis for the disturbed mitochondrial metabolism and subsequent wound healing impairment in the diabetic cornea. Seahorse analysis showed that mitochondrial oxidative phosphorylation is a major source of ATP production in human corneal epithelial cells. Live corneal biopsy punches from type 1 and type 2 diabetic mouse models showed impaired mitochondrial functions, correlating with impaired corneal wound healing, compared to nondiabetic controls. To approach the molecular basis for the impaired mitochondrial function, we found that Peroxisome Proliferator-Activated Receptor-α (PPARα) expression was downregulated in diabetic human corneas. Even without diabetes, global PPARα knockout mice and corneal epithelium-specific PPARα conditional knockout mice showed disturbed mitochondrial function and delayed wound healing in the cornea, similar to that in diabetic corneas. In contrast, fenofibrate, a PPARα agonist, ameliorated mitochondrial dysfunction and enhanced wound healing in the corneas of diabetic mice. Similarly, corneal epithelium-specific PPARα transgenic overexpression improved mitochondrial function and enhanced wound healing in the cornea. Furthermore, PPARα agonist ameliorated the mitochondrial dysfunction in primary human corneal epithelial cells exposed to diabetic stressors, which was impeded by siRNA knockdown of PPARα, suggesting a PPARα-dependent mechanism. These findings suggest that downregulation of PPARα plays an important role in the impaired mitochondrial function in the corneal epithelium and delayed corneal wound healing in diabetes.

Stemness of Normal and Cancer Cells: The Influence of Methionine Needs and SIRT1/PGC-1α/PPAR-α Players

Stem cells are a population of undifferentiated cells with self-renewal and differentiation capacities. Normal and cancer stem cells share similar characteristics in relation to their stemness properties. One-carbon metabolism (OCM), a network of interconnected reactions, plays an important role in this dependence through its role in the endogenous synthesis of methionine and S-adenosylmethionine (SAM), the universal donor of methyl groups in eukaryotic cells. OCM genes are differentially expressed in stem cells, compared to their differentiated counterparts. Furthermore, cultivating stem cells in methionine-restricted conditions hinders their stemness capacities through decreased SAM levels with a subsequent decrease in histone methylation, notably H3K4me3, with a decrease in stem cell markers. Stem cells' reliance on methionine is linked to several mechanisms, including high methionine flux or low endogenous methionine biosynthesis. In this review, we provide an overview of the recent discoveries concerning this metabolic dependence and we discuss the mechanisms behind them. We highlight the influence of SIRT1 on SAM synthesis and suggest a role of PGC-1α/PPAR-α in impaired stemness produced by methionine deprivation. In addition, we discuss the potential interest of methionine restriction in regenerative medicine and cancer treatment.

Combination of pioglitazone and dendritic cell to optimize efficacy of immune cell therapy in CT26 tumor models

Introduction

The maturation faith of dendritic cells is restrained by the inflammatory environment and cytokines, such as interleukin-6 and its downstream component. Therefore, introducing the suitable antigen to dendritic cells is crucial. However, reducing the severity of the suppressive tumor microenvironment is indispensable. The present study examined the combination therapy of lymphocyte antigen 6 family member E (LY6E) pulsed mature dendritic cells (LPMDCs) and pioglitazone against colorectal cancer (CRC) to elevate the effectiveness of cancer treatment through probable role of pioglitazone on inhibiting IL-6/STAT3 pathway.

Methods

Dendritic cells were generated from murine bone marrow and were pulsed with lymphocyte antigen 6 family member E peptide to assess antigen-specific T-cell proliferation and cytotoxicity assay with Annexin/PI. The effect of pioglitazone on interleukin (IL)-6/STAT3 was evaluated in vitro by real-time polymerase chain reaction (PCR). Afterward, the CRC model was established by subcutaneous injection of CT26, mouse colon carcinoma cell line, in female mice. After treatment, tumor, spleen, and lymph nodes samples were removed for histopathological, ELISA, and real-time PCR analysis.

Results

In vitro results revealed the potential of lysate-pulsed dendritic cells in the proliferation of double-positive CD3-8 splenocytes and inducing immunogenic cell death responses, whereas pioglitazone declined the expression of IL-6/STAT3 in colorectal cell lines. In animal models, the recipient of LPMDCs combined with pioglitazone demonstrated high tumor-infiltrating lymphocytes. Elevating the IL-12 and interferon-gamma (IFN-γ) levels and prolonged survival in lysate-pulsed dendritic cell and combination groups were observed.

Conclusion

Pioglitazone could efficiently ameliorate the immunosuppressive feature of the tumor microenvironment, mainly through IL-6. Accordingly, applying this drug combined with LPMDCs provoked substantial CD8 positive responses in tumor-challenged animal models.

The synergistic effect of eucalyptus oil and retinoic acid on human esophagus cancer cell line SK-GT-4

Background

In order to improve cancer patients' chances of survival, scientists have prioritized finding alternatives to chemotherapy, focusing their efforts on natural sources. The current study investigates the anti-cancer action of retinoic acid and Eucalyptus oil in esophageal cancer and studies their combined effect as well as the cellular pathways that each trigger as part of ongoing research in this field. As a model of esophageal cancer, the SK-GT-4 cancer cell line was treated with a series of concentrations of both materials.

Results

The concentrations of Eucalyptus oil (10, 100, 1000, and 1500 g/mL) and Retinoic acid (5, 100, 150, and 200 M/mL) were used for treatment of cells. The MTT test was used to assess the anti-cancer activity of Eucalyptus oil and Retinoic acid, and qPCR was used to determine cellular pathways. Our findings show that both Eucalyptus oil and Retinoic acid inhibit cancer cell growth significantly. Our findings revealed that the IC50 values for eucalyptus oil were 63 g/mL and 111.3 M l/mL for retinoic acid. Furthermore, the impact was at the level that causes apoptosis. The findings suggested that any herbal substance could act as an inducer of the caspase-9-dependent pathway. The caspase-8-dependent pathway, on the other hand, was restricted to retinoic acid.

Conclusion

Our research discovered that the two chemicals worked together to create a synergistic effect. This synergistic effect could be attributed to a close connection between external and internal apoptotic pathways, which inhibits SK-GT-4 cell growth.

Graphical Abstract

Disparate roles of retinoid acid signaling molecules in kidney disease

Retinoid acid (RA) is synthesized mainly in the liver and has multiple functions in development, cell differentiation and proliferation, and regulation of inflammation. RA has been used to treat multiple diseases, such as cancer and skin disorders. The kidney is a major organ for RA metabolism, which is altered in the diseased condition. RA is known to have renal-protective effects in multiple animal models of kidney disease. RA has been shown to ameliorate podocyte injury through induction of expression of differentiation markers and regeneration of podocytes from its progenitor cells in animal models of kidney disease. The effects of RA in podocytes are mediated mainly by activation of the cAMP/PKA pathway via RA receptor-α (RARα) and activation of its downstream transcription factor, Kruppel-like factor 15. Screening of RA signaling molecules in human kidney disease has revealed RAR responder protein 1 (RARRES1) as a risk gene for glomerular disease progression. RARRES1, a podocyte-specific growth arrest gene, is regulated by high doses of both RA and TNF-α. Mechanistically, RARRES1 is cleaved by matrix metalloproteinases to generate soluble RARRES1, which then induces podocyte apoptosis through interaction with intracellular RIO kinase 1. Therefore, a high dose of RA may induce podocyte toxicity through upregulation of RARRES1. Based on the current findings, to avoid potential side effects, we propose three strategies to develop future therapies of RA for glomerular disease: 1) develop RARα- and Kruppel-like factor 15-specific agonists, 2) use the combination of a low dose of RAR-α agonist with phosphodiesterase 4 inhibitors, and 3) use a combination of RARα agonist with RARRES1 inhibitors.NEW & NOTEWORTHY Retinoic acid (RA) exerts pleotropic cellular effects, including induction of cell differentiation while inhibiting proliferation and inflammation. These effects are mediated by both RA responsive element-dependent or -independent pathways. In kidneys, RA confers renoprotection by signaling through podocyte RA receptor (RAR)α and activation of cAMP/PKA/Kruppel-like factor 15 pathway to promote podocyte differentiation. Nevertheless, in kidney disease settings, RA can also promote podocyte apoptosis and loss through downstream expression of RAR responder protein 1, a recently described risk factor for glomerular disease progression. These disparate roles of RA underscore the complexity of its effects in kidney homeostasis and disease, and a need to target specific RA-mediated pathways for effective therapeutic treatments against kidney disease progression.

PPARs and Tumor Microenvironment: The Emerging Roles of the Metabolic Master Regulators in Tumor Stromal-Epithelial Crosstalk and Carcinogenesis

Peroxisome proliferator-activated receptors (PPARs) have been extensively studied for more than three decades. Consisting of three isotypes, PPARα, γ, and β/δ, these nuclear receptors are regarded as the master metabolic regulators which govern many aspects of the body energy homeostasis and cell fate. Their roles in malignancy are also increasingly recognized. With the growing interest in crosstalk between tumor stroma and epithelium, this review aims to highlight the current knowledge on the implications of PPARs in the tumor microenvironment. PPARγ plays a crucial role in the metabolic reprogramming of cancer-associated fibroblasts and adipocytes, coercing the two stromal cells to become substrate donors for cancer growth. Fibroblast PPARβ/δ can modify the risk of tumor initiation and cancer susceptibility. In endothelial cells, PPARβ/δ and PPARα are pro- and anti-angiogenic, respectively. Although the angiogenic role of PPARγ remains ambiguous, it is a crucial regulator in autocrine and paracrine signaling of cancer-associated fibroblasts and tumor-associated macrophages/immune cells. Of note, angiopoietin-like 4 (ANGPTL4), a secretory protein encoded by a target gene of PPARs, triggers critical oncogenic processes such as inflammatory signaling, extracellular matrix derangement, anoikis resistance and metastasis, making it a potential drug target for cancer treatment. To conclude, PPARs in the tumor microenvironment exhibit oncogenic activities which are highly controversial and dependent on many factors such as stromal cell types, cancer types, and oncogenesis stages. Thus, the success of PPAR-based anticancer treatment potentially relies on innovative strategies to modulate PPAR activity in a cell type-specific manner.

PPARα-Selective Antagonist GW6471 Inhibits Cell Growth in Breast Cancer Stem Cells Inducing Energy Imbalance and Metabolic Stress

Breast cancer is the most frequent cancer and the second leading cause of death among women. Triple-negative breast cancer is the most aggressive subtype of breast cancer and is characterized by the absence of hormone receptors and human epithelial growth factor receptor 2. Cancer stem cells (CSCs) represent a small population of tumor cells showing a crucial role in tumor progression, metastasis, recurrence, and drug resistance. The presence of CSCs can explain the failure of conventional therapies to completely eradicate cancer. Thus, to overcome this limit, targeting CSCs may constitute a promising approach for breast cancer treatment, especially in the triple-negative form. To this purpose, we isolated and characterized breast cancer stem cells from a triple-negative breast cancer cell line, MDA-MB-231. The obtained mammospheres were then treated with the specific PPARα antagonist GW6471, after which, glucose, lipid metabolism, and invasiveness were analyzed. Notably, GW6471 reduced cancer stem cell viability, proliferation, and spheroid formation, leading to apoptosis and metabolic impairment. Overall, our findings suggest that GW6471 may be used as a potent adjuvant for gold standard therapies for triple-negative breast cancer, opening the possibility for preclinical and clinical trials for this class of compounds.

Interleukin-6 neutralization ameliorates symptoms in prematurely aged mice

Hutchinson-Gilford progeria syndrome (HGPS) causes premature aging in children, with adipose tissue, skin and bone deterioration, and cardiovascular impairment. In HGPS cells and mouse models, high levels of interleukin-6, an inflammatory cytokine linked to aging processes, have been detected. Here, we show that inhibition of interleukin-6 activity by tocilizumab, a neutralizing antibody raised against interleukin-6 receptors, counteracts progeroid features in both HGPS fibroblasts and Lmna^{G609G / G609G} progeroid mice. Tocilizumab treatment limits the accumulation of progerin, the toxic protein produced in HGPS cells, rescues nuclear envelope and chromatin abnormalities, and attenuates the hyperactivated DNA damage response. In vivo administration of tocilizumab reduces aortic lesions and adipose tissue dystrophy, delays the onset of lipodystrophy and kyphosis, avoids motor impairment, and preserves a good quality of life in progeroid mice. This work identifies tocilizumab as a valuable tool in HGPS therapy and, speculatively, in the treatment of a variety of aging-related disorders.

Prolonged overnutrition with fructose or fat induces metabolic derangements in rats by disrupting the crosstalk between the hypothalamus and periphery: Possible amelioration with fenofibrate

Metabolic Syndrome (MetS) increases the risk of developing type 2 diabetes mellitus and cardiovascular complications. The crosstalk between the hypothalamus and periphery is vital for regulating food intake and energy homeostasis. However, it is impaired during MetS. The present study aimed to compare the distinct central and peripheral metabolic derangements induced by a high-fructose drink or high-fat diet, as well as the possible intervention by fenofibrate. Rats were divided into five groups: standard chow diet (SCD) group, high-fructose group (FR), high-fat group (HF), FR plus fenofibrate group (FR-F), and HF plus fenofibrate group (HF-F). FR and HF groups showed hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia, steatosis, and adipocyte hypertrophy. This was associated with elevated circulating levels of proinflammatory cytokines and free fatty acids (FFAs). The latter mediators are involved in the hypothalamic inflammation and dysregulation of signaling cascades that control food intake and glucose homeostasis. The effects were more pronounced in the HF group than FR group, which were matched with the observed higher levels of plasma FFAs and cytokines. Fenofibrate administration improved not only the peripheral metabolic disturbances, but also the central disturbances associated with insulin resistance induced by FR or HF diet. This study sheds light on the pivotal role of the hypothalamus in diet-induced MetS. Furthermore, the study suggests the utmost importance of developing a standardized model of metabolic syndrome in place of the great diversity between available models, which can induce different effects and negatively impact the validity of prospective studies.

Neuroprotective effect of PPAR alpha and gamma agonists in a mouse model of amyloidogenesis through modulation of the Wnt/beta catenin pathway via targeting alpha- and beta-secretases

The present study was conducted to evaluate the efficacy of fenofibrate and pioglitazone in a mouse model of amyloidogenesis induced by amyloidβ (βA) peptide. Mice were injected intracerebroventricularly with βA1-40 (400 pmol/mouse) once, followed by treatment with fenofibrate (300 mg/kg), pioglitazone (30 mg/kg),or both. After 21 days of daily treatment, memory impairment and cognitive function were evaluated by Morris water maze (MWM), Y-maze and object recognition tests. On the 22nd day, mice were sacrificed, and their hippocampi were dissected to determine the levels of α- and β-secretase, peroxisome proliferator-activated receptor (PPARα and β), Wnt and β-catenin. Significant memory impairment and cognitive dysfunction were observed in the mouse model group. This finding was associated with a significant increase in α- and β-secretase levels and a significant decrease in Wnt, β-catenin, and PPARα and β levels. Neuronal damage was also evident after histopathological examination. Treatment with fenofibrate, pioglitazone and their combination resulted in a significant improvement in the behavioural and neurochemical changes induced by βA injection. The present findings indicate that the combined administration of fenofibrate and pioglitazone was more effective than monotherapy in ameliorating the behavioural, neurochemical and histopathological changes in amyloidogenesis model mice and provide a promising therapeutic approach in the management of Alzheimer's disease complicated by diabetes and hypercholesterolemia.

Anakoinosis: Correcting Aberrant Homeostasis of Cancer Tissue-Going Beyond Apoptosis Induction

The current approach to systemic therapy for metastatic cancer is aimed predominantly at inducing apoptosis of cancer cells by blocking tumor-promoting signaling pathways or by eradicating cell compartments within the tumor. In contrast, a systems view of therapy primarily considers the communication protocols that exist at multiple levels within the tumor complex, and the role of key regulators of such systems. Such regulators may have far-reaching influence on tumor response to therapy and therefore patient survival. This implies that neoplasia may be considered as a cell non-autonomous disease. The multi-scale activity ranges from intra-tumor cell compartments, to the tumor, to the tumor-harboring organ to the organism. In contrast to molecularly targeted therapies, a systems approach that identifies the complex communications networks driving tumor growth offers the prospect of disrupting or "normalizing" such aberrant communicative behaviors and therefore attenuating tumor growth. Communicative reprogramming, a treatment strategy referred to as anakoinosis, requires novel therapeutic instruments, so-called master modifiers to deliver concerted tumor growth-attenuating action. The diversity of biological outcomes following pro-anakoinotic tumor therapy, such as differentiation, trans-differentiation, control of tumor-associated inflammation, etc. demonstrates that long-term tumor control may occur in multiple forms, inducing even continuous complete remission. Accordingly, pro-anakoinotic therapies dramatically extend the repertoire for achieving tumor control and may activate apoptosis pathways for controlling resistant metastatic tumor disease and hematologic neoplasia.

WY-14643 Regulates CYP1B1 Expression through Peroxisome Proliferator-Activated Receptor α-Mediated Signaling in Human Breast Cancer Cells

Human cytochrome P450 1B1 (CYP1B1)-mediated biotransformation of endobiotics and xenobiotics plays an important role in the progression of human breast cancer. In this study, we investigated the effects of WY-14643, a peroxisome proliferator-activated receptor α (PPARα) agonist, on CYP1B1 expression and the related mechanism in MCF7 breast cancer cells. We performed quantitative reverse transcription-polymerase chain reaction, transient transfection, and chromatin immunoprecipitation to evaluate the effects of PPARα on peroxisome proliferator response element (PPRE)-mediated transcription. WY-14643 increased the protein and mRNA levels of CYP1B1, as well as promoter activity, in MCF-7 cells. Moreover, WY-14643 plus GW6471, a PPARα antagonist, significantly inhibited the WY-14643-mediated increase in CYP1B1 expression. PPARα knockdown by a small interfering RNA markedly suppressed the induction of CYP1B1 expression by WY-14643, suggesting that WY-14643 induces CYP1B1 expression via a PPARα-dependent mechanism. Bioinformatics analysis identified putative PPREs (−833/−813) within the promoter region of the CYP1B1 gene. Inactivation of these putative PPREs by deletion mutagenesis suppressed the WY-14643-mediated induction of CYP1B1 promoter activation. Furthermore, WY-14643 induced PPARα to assume a form capable of binding specifically to the PPRE-binding site in the CYP1B1 promoter. Our findings suggest that WY-14643 induces the expression of CYP1B1 through activation of PPARα.

Activation and Expression of Peroxisome Proliferator-Activated Receptor Alpha Are Associated with Tumorigenesis in Colorectal Carcinoma

Peroxisome proliferator-activated receptor alpha (PPAR-α) belongs to the PPAR family and plays a critical role in inhibiting cell proliferation and tumorigenesis in various tumors. However, the role of PPAR-α in colorectal tumorigenesis is unclear. In the present study, we found that fenofibrate, a PPAR-α agonist, significantly inhibited cell proliferation and induced apoptosis in colorectal carcinoma cells. In addition, PPAR-α was expressed in the nucleus of colorectal carcinoma cells, and the expression of nuclear PPAR-α increased in colorectal carcinoma tissue compared with that of normal epithelium tissue (P<0.01). The correlation between the expression of nuclear PPAR-α and clinicopathological factors was evaluated in human colorectal carcinoma tissues, and the nuclear expression of PPAR-α was significantly higher in well-to-moderately differentiated adenocarcinoma than in mucinous adenocarcinoma (P<0.05). These findings indicate that activation of PPAR-α may be involved in anticancer effects in colorectal carcinomas, and nuclear expression of PPAR-α may be a therapeutic target for colorectal adenocarcinoma treatment.

Retinoic Acid-Related Orphan Receptor C Regulates Proliferation, Glycolysis, and Chemoresistance via the PD-L1/ITGB6/STAT3 Signaling Axis in Bladder Cancer

Retinoic acid-related orphan receptor C (RORC) is a member of the nuclear orphan receptor family and performs critical regulatory functions in cell proliferation, metastasis, and chemoresistance in various types of malignant tumors. Here we showed that expression of RORC is lost in tumor tissues of bladder cancer patients. Enhanced expression of RORC suppressed cell proliferation and glucose metabolism and increased cisplatin-induced apoptosis in vitro and in vivo. RORC bound the promoter region of programmed death ligand-1 (PD-L1) and negatively regulated PD-L1 expression. PD-L1 directly interacted with integrin β6 (ITGB6) and activated the ITGB6/FAK signaling pathway. RORC prevented the nuclear translocation of STAT3 via suppression of the PD-L1/ITGB6 signaling pathway, which further inhibited bladder cell proliferation and glucose metabolism and increased cisplatin-induced apoptosis. These findings reveal that RORC regulates bladder cancer cell proliferation, glucose metabolism, and chemoresistance by participating in the PD-L1/ITGB6/STAT3 signaling axis. Moreover, this new understanding of PD-L1 signaling may guide the selection of therapeutic targets to prevent tumor recurrence. SIGNIFICANCE: These findings suggest that RORC-mediated regulation of a PD-L1/ITGB6/FAK/STAT3 signaling axis in bladder cancer provides several potential therapeutic targets to prevent tumor progression.

Clinical Efficacy of a Novel Therapeutic Principle, Anakoinosis

Classic tumor therapy, consisting of cytotoxic agents and/or targeted therapy, has not overcome therapeutic limitations like poor risk genetic parameters, genetic heterogeneity at different metastatic sites or the problem of undruggable targets. Here we summarize data and trials principally following a completely different treatment concept tackling systems biologic processes: the principle of communicative reprogramming of tumor tissues, i.e., anakoinosis (ancient greek for communication), aims at establishing novel communicative behavior of tumor tissue, the hosting organ and organism via re-modeling gene expression, thus recovering differentiation, and apoptosis competence leading to cancer control - in contrast to an immediate, "poisoning" with maximal tolerable doses of targeted or cytotoxic therapies. Therefore, we introduce the term "Master modulators" for drugs or drug combinations promoting evolutionary processes or regulating homeostatic pathways. These "master modulators" comprise a broad diversity of drugs, characterized by the capacity for reprogramming tumor tissues, i.e., transcriptional modulators, metronomic low-dose chemotherapy, epigenetically modifying agents, protein binding pro-anakoinotic drugs, such as COX-2 inhibitors, IMiDs etc., or for example differentiation inducing therapies. Data on 97 anakoinosis inducing schedules indicate a favorable toxicity profile: The combined administration of master modulators, frequently (with poor or no monoactivity) may even induce continuous complete remission in refractory metastatic neoplasia, irrespectively of the tumor type. That means recessive components of the tumor, successively developing during tumor ontogenesis, are accessible by regulatory active drug combinations in a therapeutically meaningful way. Drug selection is now dependent on situative systems characteristics, to less extent histology dependent. To sum up, anakoinosis represents a new substantive therapy principle besides novel targeted therapies.

Peroxisome Proliferator-Activated Receptors (PPAR)γ Agonists as Master Modulators of Tumor Tissue

In most clinical trials, thiazolidinediones do not show any relevant anti-cancer activity when used as mono-therapy. Clinical inefficacy contrasts ambiguous pre-clinical data either favoring anti-tumor activity or tumor promotion. However, if thiazolidinediones are combined with additional regulatory active drugs, so-called ‘master modulators’ of tumors, i.e., transcriptional modulators, metronomic low-dose chemotherapy, epigenetically modifying agents, protein binding pro-anakoinotic drugs, such as COX-2 inhibitors, IMiDs, etc., the results indicate clinically relevant communicative reprogramming of tumor tissues, i.e., anakoinosis, meaning ‘communication’ in ancient Greek. The concerted activity of master modulators may multifaceted diversify palliative care or even induce continuous complete remission in refractory metastatic tumor disease and hematologic neoplasia by establishing novel communicative behavior of tumor tissue, the hosting organ, and organism. Re-modulation of gene expression, for example, the up-regulation of tumor suppressor genes, may recover differentiation, apoptosis competence, and leads to cancer control—in contrast to an immediate, ‘poisoning’ with maximal tolerable doses of targeted/cytotoxic therapies. The key for uncovering the therapeutic potential of Peroxisome proliferator-activated receptor γ (PPARγ) agonists is selecting the appropriate combination of master modulators for inducing anakoinosis: Now, anakoinosis is trend setting by establishing a novel therapeutic pillar while overcoming classic obstacles of targeted therapies, such as therapy resistance and (molecular-)genetic tumor heterogeneity.

Epigenetic up-regulation of ribosome biogenesis and more aggressive phenotype triggered by the lack of the histone demethylase JHDM1B in mammary epithelial cells

The alterations of ribosome biogenesis and protein synthesis play a direct role in the development of tumors. The accessibility and transcription of ribosomal genes is controlled at several levels, with their epigenetic regulation being one of the most important. Here we explored the JmjC domain-containing histone demethylase 1B (JHDM1B) function in the epigenetic control of rDNA transcription. Since JHDM1B is a negative regulator of gene transcription, we focused on the effects induced by JHDM1B knock-down (KD). We studied the consequences of stable inducible JHDM1B silencing in cell lines derived from transformed and untransformed mammary epithelial cells. In these cellular models, prolonged JHDM1B downregulation triggered a surge of 45S pre-rRNA transcription and processing, associated with a re-modulation of the H3K36me2 levels at rDNA loci and with changes in DNA methylation of specific CpG sites in rDNA genes. We also found that after JHDM1B KD, cells showed a higher ribosome content: which were engaged in mRNA translation. JHDM1B KD and the consequent stimulation of ribosomes biogenesis conferred more aggressive features to the tested cellular models, which acquired a greater clonogenic, staminal and invasive potential. Taken together, these data indicate that the reduction of JHDM1B leads to a more aggressive cellular phenotype in mammary gland cells, by virtue of its negative regulatory activity on ribosome biogenesis.

Lipid-sensors, enigmatic-orphan and orphan nuclear receptors as therapeutic targets in breast-cancer

Breast-cancer is heterogeneous and consists of various groups with different biological characteristics. Innovative pharmacological approaches accounting for this heterogeneity are needed. The forty eight human Nuclear-Hormone-Receptors are ligand-dependent transcription-factors and are classified into Endocrine-Receptors, Adopted-Orphan-Receptors (Lipid-sensors and Enigmatic-Orphans) and Orphan-receptors. Nuclear-Receptors represent ideal targets for the design/synthesis of pharmacological ligands. We provide an overview of the literature available on the expression and potential role played by Lipid-sensors, Enigmatic-Orphans and Orphan-Receptors in breast-cancer. The data are complemented by an analysis of the expression levels of each selected Nuclear-Receptor in the PAM50 breast-cancer groups, following re-elaboration of the data publicly available. The major aim is to support the idea that some of the Nuclear-Receptors represent largely unexploited therapeutic-targets in breast-cancer treatment/chemo-prevention. On the basis of our analysis, we conclude that the Lipid-Sensors, NR1C3, NR1H2 and NR1H3 are likely to be onco-suppressors in breast-cancer. The Enigmatic-Orphans, NR1F1 NR2A1 and NR3B3 as well as the Orphan-Receptors, NR0B1, NR0B2, NR1D1, NR2F1, NR2F2 and NR4A3 exert a similar action. These Nuclear-Receptors represent candidates for the development of therapeutic strategies aimed at increasing their expression or activating them in tumor cells. The group of Nuclear-Receptors endowed with potential oncogenic properties consists of the Lipid-Sensors, NR1C2 and NR1I2, the Enigmatic-Orphans, NR1F3, NR3B1 and NR5A2, as well as the Orphan-Receptors, NR2E1, NR2E3 and NR6A1. These oncogenic Nuclear-Receptors should be targeted with selective antagonists, reverse-agonists or agents/strategies capable of reducing their expression in breast-cancer cells.

Evaluation of Antioxidant Intakes in Relation to Inflammatory Markers Expression Within the Normal Breast Tissue of Breast Cancer Patients

Chronic inflammation may be a causative factor in breast cancer. One possible underlying mechanism is the generation of oxidative stress, which may favor tumorigenic processes. Antioxidant consumption may, therefore, help reduce tissue inflammation levels. However, few studies have explored this relation in breast tissue. We aimed to evaluate correlations between antioxidant (vitamin A/retinol, vitamin C, vitamin E, β-carotene, α-carotene, lycopene, lutein/zeaxanthin, β-cryptoxanthin, selenium, and zinc) intakes and protein expression levels of interleukin (IL)-6, tumor necrosis factor-α, C-reactive protein, cyclooxygenase-2, leptin, serum amyloid A1, signal transducer and activator of transcription 3, IL-8, IL-10, lactoferrin, and transforming growth factor-β measured in the normal breast tissue of 160 women diagnosed with breast cancer. Antioxidant intakes were collected using a self-administered food frequency questionnaire. Inflammation marker expression was assessed by immunohistochemistry. Correlations between antioxidant intakes and inflammatory marker expression were evaluated using Spearman's partial correlation coefficients ( r) for all women and for premenopausal and postmenopausal women separately. After Bonferroni correction, negative correlations were observed between dietary β-tocopherol and IL-10 expression in all women combined ( r = -0.26, P = .003) and among postmenopausal women ( r = -0.39, P = .003). For all women, a negative correlation was found between total zinc intakes and IL-10 ( r = -0.26, P = .002). Among postmenopausal women, dietary selenium intake was negatively correlated with the expression of lactoferrin ( r = -0.39, P = .003). No associations were observed in premenopausal women. Our findings suggest that consumption of specific antioxidants, including β-tocopherol, zinc, and selenium, may act on the breast tissue through mechanisms affecting the expression of some inflammation markers, particularly among postmenopausal women.

Targeting cancer stem cells and signaling pathways by phytochemicals: Novel approach for breast cancer therapy

Breast cancer is the most common form of cancer diagnosed in women worldwide and the second leading cause of cancer-related deaths in the USA. Despite the development of newer diagnostic methods, selective as well as targeted chemotherapies and their combinations, surgery, hormonal therapy, radiotherapy, breast cancer recurrence, metastasis and drug resistance are still the major problems for breast cancer. Emerging evidence suggest the existence of cancer stem cells (CSCs), a population of cells with the capacity to self-renew, differentiate and be capable of initiating and sustaining tumor growth. In addition, CSCs are believed to be responsible for cancer recurrence, anticancer drug resistance, and metastasis. Hence, compounds targeting breast CSCs may be better therapeutic agents for treating breast cancer and control recurrence and metastasis. Naturally occurring compounds, mainly phytochemicals have gained immense attention in recent times because of their wide safety profile, ability to target heterogeneous populations of cancer cells as well as CSCs, and their key signaling pathways. Therefore, in the present review article, we summarize our current understanding of breast CSCs and their signaling pathways, and the phytochemicals that affect these cells including curcumin, resveratrol, tea polyphenols (epigallocatechin-3-gallate, epigallocatechin), sulforaphane, genistein, indole-3-carbinol, 3, 3'-di-indolylmethane, vitamin E, retinoic acid, quercetin, parthenolide, triptolide, 6-shogaol, pterostilbene, isoliquiritigenin, celastrol, and koenimbin. These phytochemicals may serve as novel therapeutic agents for breast cancer treatment and future leads for drug development.

Peritoneal expression of Matrilysin helps identify early post-operative recurrence of colorectal cancer

Recurrence of colorectal cancer (CRC) following a potentially curative resection is a challenging clinical problem. Matrix metalloproteinase-7 (MMP-7) is over-expressed by CRC cells and supposed to play a major role in CRC cell diffusion and metastasis. MMP-7 RNA expression was assessed by real-time PCR using specific primers in peritoneal washing fluid obtained during surgical procedure. After surgery, patients underwent a regular follow up for assessing recurrence. transcripts for MMP-7 were detected in 31/57 samples (54%). Patients were followed-up (range 20-48 months) for recurrence prevention. Recurrence was diagnosed in 6 out of 55 patients (11%) and two patients eventually died because of this. Notably, all the six patients who had relapsed were positive for MMP-7. Sensitivity and specificity of the test were 100% and 49% respectively. Data from patients have also been corroborated by computational approaches. Public available coloncarcinoma datasets have been employed to confirm MMP7 clinical impact on the disease. Interestingly, MMP-7 expression appeared correlated to Tgfb-1, and correlation of the two factors represented a poor prognostic factor. This study proposes positivity of MMP-7 in peritoneal cavity as a novel biomarker for predicting disease recurrence in patients with CRC.

Role of nuclear receptors in breast cancer stem cells

The recapitulation of primary tumour heterogenity and the existence of a minor sub-population of cancer cells, capable of initiating tumour growth in xenografts on serial passages, led to the hypothesis that cancer stem cells (CSCs) exist. CSCs are present in many tumours, among which is breast cancer. Breast CSCs (BCSCs) are likely to sustain the growth of the primary tumour mass, as well as to be responsible for disease relapse and metastatic spreading. Consequently, BCSCs represent the most significant target for new drugs in breast cancer therapy. Both the hypoxic condition in BCSCs biology and pro-inflammatory cytokine network has gained increasing importance in the recent past. Breast stromal cells are crucial components of the tumours milieu and are a major source of inflammatory mediators. Recently, the anti-inflammatory role of some nuclear receptors ligands has emerged in several diseases, including breast cancer. Therefore, the use of nuclear receptors ligands may be a valid strategy to inhibit BCSCs viability and consequently breast cancer growth and disease relapse.

Flubendazole, FDA-approved anthelmintic, targets breast cancer stem-like cells

Cancer stem-like cell (CS-like cell) is considered to be responsible for recurrence and drug resistance events in breast cancer, which makes it a potential target for novel cancer therapeutic strategy. The FDA approved flubendazole, has been widely used in the treatment of intestinal parasites. Here, we demonstrated a novel effect of flubendazole on breast CS-like cells. Flubendazole inhibited breast cancer cells proliferation in dose- and time-dependent manner and delayed tumor growth in xenograft models by intraperitoneal injection. Importantly, flubendazole reduced CD44^high/CD24^low subpopulation and suppressed the formation of mammosphere and the expression of self-renewal related genes including c-myc, oct4, sox2, nanog and cyclinD1. Moreover, we found that flubendazole induced cell differentiation and inhibited cell migration. Consistently, flubendazole reduced mesenchymal markers (β-catenin, N-cadherin and Vimentin) expression and induced epithelial and differentiation marker (Keratin 18) expression in breast cancer cells. Mechanism study revealed that flubendazole arrested cell cycle at G2/M phase and induced monopolar spindle formation through inhibiting tubulin polymerization. Furthermore, flubendazole enhanced cytotoxic activity of conventional therapeutic drugs fluorouracil and doxorubicin against breast cancer cells. In conclusion, our findings uncovered a remarkable effect of flubendazole on suppressing breast CS-like cells, indicating a novel utilization of flubendazole in breast cancer therapy.

Combined Treatment with Epigenetic, Differentiating, and Chemotherapeutic Agents Cooperatively Targets Tumor-Initiating Cells in Triple-Negative Breast Cancer

Efforts to induce the differentiation of cancer stem cells through treatment with all-trans retinoic acid (ATRA) have yielded limited success, partially due to the epigenetic silencing of the retinoic acid receptor (RAR)-β The histone deacetylase inhibitor entinostat is emerging as a promising antitumor agent when added to the standard-of-care treatment for breast cancer. However, the combination of epigenetic, cellular differentiation, and chemotherapeutic approaches against triple-negative breast cancer (TNBC) has not been investigated. In this study, we found that combined treatment of TNBC xenografts with entinostat, ATRA, and doxorubicin (EAD) resulted in significant tumor regression and restoration of epigenetically silenced RAR-β expression. Entinostat and doxorubicin treatment inhibited topoisomerase II-β (TopoII-β) and relieved TopoII-β-mediated transcriptional silencing of RAR-β Notably, EAD was the most effective combination in inducing differentiation of breast tumor-initiating cells in vivo Furthermore, gene expression analysis revealed that the epithelium-specific ETS transcription factor-1 (ESE-1 or ELF3), known to regulate proliferation and differentiation, enhanced cell differentiation in response to EAD triple therapy. Finally, we demonstrate that patient-derived metastatic cells also responded to treatment with EAD. Collectively, our findings strongly suggest that entinostat potentiates doxorubicin-mediated cytotoxicity and retinoid-driven differentiation to achieve significant tumor regression in TNBC. Cancer Res; 76(7); 2013-24. ©2016 AACR.

Fibrates inhibit the apoptosis of Batten disease lymphoblast cells via autophagy recovery and regulation of mitochondrial membrane potential

Batten disease (BD; also known as juvenile neuronal ceroid lipofuscinosis) is a genetic disorder inherited as an autosomal recessive trait and is characterized by blindness, seizures, cognitive decline, and early death resulting from the inherited mutation of the CLN3 gene. Mitochondrial oxidative stress, endoplasmic reticulum (ER) stress, disrupted autophagy, and enhanced apoptosis have been suggested to play a role in BD pathogenesis. Fibrates, a class of lipid-lowering drugs that induce peroxisome proliferator-activated receptor-α (PPAR-α) activation, are the most commonly used PPAR agonists. Assuming that fibrates have a neuroprotective effect, we studied the effects of fibrates, fenofibrate, bezafibrate, and gemfibrozil on apoptosis, depolarization of mitochondrial membrane, and defective autophagy in BD lymphoblast cells. The viability of fibrate-treated BD lymphoblast cells increased to levels of normal lymphoblast cells. In addition, treatment with fibrates inhibited depolarization of mitochondrial membrane potential in BD lymphoblast cells. Defective autophagy in BD lymphoblast cells was normalized when treated with fibrates as indicated by increased acridine orange staining. The recovery of autophagy in BD lymphoblast cells is most likely attributed to the upregulation of autophagy proteins, lysosomal-associated membrane protein 1 (LAMP1), and LC3 I/II, after treatment with fibrates. This study therefore suggests that fibrates may have a therapeutic potential against BD.

Carbonic Anhydrase 9 mRNA/microRNA34a Interplay in Hypoxic Human Mammospheres

The hypoxic environment is a crucial component of the cancer stem cell niche and it is capable of eliciting stem cell features in cancer cells. We previously reported that SNAI2 up-regulates the expression of Carbonic Anhydrase iso-enzyme 9 (CA9) in hypoxic MCF7 cells. Here we show that SNAI2 down-regulates miR34a expression in hypoxic MCF7 cell-derived mammospheres. Next, we report on the capability of miR34a to decrease CA9 mRNA stability and CA9 protein expression. We also convey that the over-expression of cloned CA9-mRNA-3'UTR increases the mRNA half-life and protein levels of two miR34a targets JAGGED1 and NOTCH3. The data here reported shows that the SNAI2-dependent down-regulation of miR34a substantially contributes to the post-transcriptional up-regulation of CA9, and that CA9-mRNA-3'UTR acts as an endogenous microRNA sponge. We conclude that CA9/miR34 interplay shares in the hypoxic regulation of mammospheres and therefore, may play a relevant role in the hypoxic breast cancer stem cell niche.

Loss of 5-lipoxygenase activity protects mice against paracetamol-induced liver toxicity

BACKGROUND AND PURPOSE

Paracetamol (acetaminophen) is the most widely used over-the-counter analgesic and overdosing with paracetamol is the leading cause of hospital admission for acute liver failure. 5-Lipoxygenase (5-LO) catalyses arachidonic acid to form LTs, which lead to inflammation and oxidative stress. In this study, we examined whether deletion or pharmacological inhibition of 5-LO could protect mice against paracetamol-induced hepatic toxicity.

EXPERIMENTAL APPROACH

Both genetic deletion and pharmacological inhibition of 5-LO in C57BL/6J mice were used to study the role of this enzyme in paracetamol induced liver toxicity. Serum and tissue biochemistry, H&E staining, and real-time PCR were used to assess liver toxicity.

KEY RESULTS

Deletion or pharmacological inhibition of 5-LO in mice markedly ameliorated paracetamol-induced hepatic injury, as shown by decreased serum alanine transaminase and aspartate aminotransferase levels and hepatic centrilobular necrosis. The hepatoprotective effect of 5-LO inhibition was associated with induction of the antitoxic phase II conjugating enzyme, sulfotransferase2a1, suppression of the pro-toxic phase I CYP3A11 and reduction of the hepatic transporter MRP3. In 5-LO(-/-) mice, levels of GSH were increased, and oxidative stress decreased. In addition, PPAR α, a nuclear receptor that confers resistance to paracetamol toxicity, was activated in 5-LO(-/-) mice.

CONCLUSIONS AND IMPLICATIONS

The activity of 5-LO may play a critical role in paracetamol-induced hepatic toxicity by regulating paracetamol metabolism and oxidative stress.

Activation of peroxisome proliferator-activated receptor gamma is crucial for antitumoral effects of 6-iodolactone

BACKGROUND

Molecular iodine (I2) exhibits antiproliferative and apoptotic effects on in vivo and in vitro cancer models. These effects are thought to be mediated by an iodinated arachidonic acid derivative, 6-iodolactone (6IL), and one of the proposed mechanisms is that 6IL activates Peroxisome Proliferator-Activated Receptors type gamma (PPARG). These receptors have been implicated in the inhibition of carcinogenic processes, in addition to their classical role in maintaining lipid and glucose homeostasis. The aim of this study was to determine whether PPARG participates in the 6IL antiproliferative and apoptotic effects on the mammary cancer cell line MCF-7.

METHODS

The 6IL/PPARG complex was inhibited by the PPARG antagonist GW9662, in both an endogenous and overexpressed (adenoviral vector infection) context, and stable PPARG-knockdown MCF-7 cells (RNA interference, confirmed with hydrolysis probes and Western blot), were used to corroborate the PPARG participation. 6IL effects on proliferation (measured by Trypan Blue exclusion) and apoptosis (phosphatidylserine identification by flow cytometer) were evaluated in conditions of chemical inhibition (GW9662) and silencing (RNA interference). A wound-healing assay was conducted on wild-type and stable PPARG-knockdown MCF-7 cells to evaluate the antimigrational effect of 6IL. Caspase-8 activity was evaluated to determine if the extrinsic pathway is involved in the effects of 6IL and I2 treatment.

RESULTS

Antiproliferative and pro-apoptotic 6IL effects require the activation of PPARG. In addition, wound-healing assays show that 6IL is able to inhibit MCF-7 cell migration and that PPARG plays a role in this phenomenon. Finally, the data exclude the participation of the extrinsic apoptotic pathway in 6IL- and I2-induced apoptosis.

CONCLUSIONS

These results support the previously proposed mechanism, in which the I2 effects are mediated by 6IL, and they provide further support for the use of I2 as coadjuvant in breast cancer treatment.

Interleukin-6 and pro inflammatory status in the breast tumor microenvironment

BACKGROUND

Greater than 50,000 new cases of breast cancer cases were diagnosed in Italy during 2013, with nearly 15,000 women succumbing to the disease. These epidemiological statistics highlight the overwhelming clinical dilemma of breast cancer and emphasize the need for novel therapeutic targets and prevention strategies. Countless studies in the fields of mammary gland development and breast cancer have led to an appreciation of a breast tumor microenvironment that actively contributes to the heterogeneous nature of breast cancer.

METHODS

The current review will focus on the impact of IL-6 and in the breast tumor microenvironment. Excessive IL-6 has been demonstrated in primary breast tumors and breast cancer patient sera and is associated with poor clinical outcomes in breast cancer. These clinical associations are corroborated by emerging preclinical data revealing that IL-6 is a potent growth factor and promotes an epithelial-mesenchyme (EMT) phenotype in breast cancer cells to indicate that IL-6 in the breast tumor microenvironment is clinically relevant.

RESULTS

High serum levels of interleukin-6 correlate with poor outcome in breast cancer patients. However, few data are yet available on the relationship between IL-6 and stem/progenitor cells, which may fuel the genesis of breast cancer in vivo. Mammospheres (MS) from node invasive breast carcinoma tissues express IL-6 mRNA at higher levels than MS from matched non-neoplastic mammary glands. IL-6 mRNA is detectable only in basal-like breast carcinoma tissues; our results reveal that IL-6 triggers a Notch-3-dependent upregulation of the Notch ligand Jagged-1, whose interaction with Notch-3 promotes the growth of MS and Michigan Cancer Foundation-7 (MCF-7)-derived spheroids. IL-6 induces a Notch-3-dependent upregulation of the carbonic anhydrase IX gene and promotes a hypoxia-resistant/invasive phenotype in MCF-7 cells and MS.

CONCLUSIONS

In conclusion, our data support the hypothesis that IL-6 induces malignant features in Notch-3-expressing, stem/progenitor cells from human ductal breast carcinoma and normal mammary gland.

Therapeutic Effects of PPAR α on Neuronal Death and Microvascular Impairment

Peroxisome-proliferator activated receptor-alpha (PPARα) is a broadly expressed nuclear hormone receptor and is a transcription factor for diverse target genes possessing a PPAR response element (PPRE) in the promoter region. The PPRE is highly conserved, and PPARs thus regulate transcription of an extensive array of target genes involved in energy metabolism, vascular function, oxidative stress, inflammation, and many other biological processes. PPARα has potent protective effects against neuronal cell death and microvascular impairment, which have been attributed in part to its antioxidant and anti-inflammatory properties. Here we discuss PPARα's effects in neurodegenerative and microvascular diseases and also recent clinical findings that identified therapeutic effects of a PPARα agonist in diabetic microvascular complications.

p63 transcriptionally regulates the expression of matrix metallopeptidase 13

p63 is a transcriptional factor belonging to p53 family of genes. Beside the role in cancer, partially shared with p53 and the other member p73, p63 also plays exclusive roles in development and homeostasis of ectodermal/epidermal-related organs. Here we show that p63 transcriptionally controls the expression of the matrix metallopeptidase 13 (MMP13). p63 binds a p53-like responsive element in the human promoter of MMP13, thus promoting the activation of its transcription. The catalytic activity of MMP13 is required in high invasion capacity of metastatic cancer cells, however, although p63 and MMP13 expression correlates in cancer patients, their co-expression does not predict cancer patient survival. Our results demonstrate that p63 directly controls MMP13 expression.

Mechanism of retinoic acid-induced transcription: histone code, DNA oxidation and formation of chromatin loops

Histone methylation changes and formation of chromatin loops involving enhancers, promoters and 3′ end regions of genes have been variously associated with active transcription in eukaryotes. We have studied the effect of activation of the retinoic A receptor, at the RARE–promoter chromatin of CASP9 and CYP26A1 genes, 15 and 45 min following RA exposure, and we found that histone H3 lysines 4 and 9 are demethylated by the lysine-specific demethylase, LSD1 and by the JMJ-domain containing demethylase, D2A. The action of the oxidase (LSD1) and a dioxygenase (JMJD2A) in the presence of Fe++ elicits an oxidation wave that locally modifies the DNA and recruits the enzymes involved in base and nucleotide excision repair (BER and NER). These events are essential for the formation of chromatin loop(s) that juxtapose the RARE element with the 5′ transcription start site and the 3′ end of the genes. The RARE bound-receptor governs the 5′ and 3′ end selection and directs the productive transcription cycle of RNA polymerase. These data mechanistically link chromatin loops, histone methylation changes and localized DNA repair with transcription.

Targeting breast cancer initiating cells: advances in breast cancer research and therapy

Over the past 10 years there have been significant advances in our understanding of breast cancer and the important roles that breast cancer initiating cells (CICs) play in the development and resistance of breast cancer. Breast CICs endowed with self-renewing and tumor-initiating capacities are believed to be responsible for the relapses which often occur after various breast cancer therapies. In this review, we will summarize some of the key developments in breast CICs which will include discussion of some of the key genes implicated: estrogen receptor (ER), HER2, BRCA1, TP53, PIK3CA, RB, P16INK1 and various miRs as well some drugs which are showing promise in targeting CICs. In addition, the concept of combined therapies will be discussed. Basic and clinical research is resulting in novel approaches to improve breast cancer therapy by targeting the breast CICs.

A RXR ligand 6-OH-11-O-hydroxyphenanthrene with antitumour properties enhances (-)-epigallocatechin-3-gallate activity in three human breast carcinoma cell lines

(−)-Epigallocatechin-3-gallate (EGCG) and chemotherapeutic agents cotreatment can improve cytotoxicity against cancer cells. We showed that EGCG and the rexinoid 6-OH-11-O-hydroxyphenanthrene (IIF), given together, were cytotoxic toward MCF-7, MCF-7TAM, and MDA-MB-231, three breast carcinoma cell lines showing different molecular characteristics. Cell growth arrest and apoptosis were greater after EGCG and IIF cotreatment than after individual administration. Cytotoxicity was related to upregulation of 67-kDa laminin receptor (LR67), one of the principal molecular targets of EGCG, and activation of the nuclear retinoic X receptors (RXRs) pathway. Furthermore, the transcription factor Forkhead box O3 (Foxo3a), a protein able to trigger apoptosis through upregulation of genes necessary for cell death, was activated. EGCG and IIF cotreatment produced a significant nuclear import of Foxo3a from the cytoplasm in MCF-7, MCF-7TAM, and MDA-MB-231 cells. In MCF-7TAM cells only, Foxo3a nuclear localization was associated with p473AKT downregulation. For the first time we showed that when EGCG and IIF, two harmless molecules, were given together, they might increase cytotoxicity in three breast carcinoma cell lines, two of them being representative of poorly responsive breast carcinoma types.

Identification of FDA-approved drugs targeting breast cancer stem cells along with biomarkers of sensitivity

Recently developed genomics-based tools are allowing repositioning of Food and Drug Administration (FDA)-approved drugs as cancer treatments, which were employed to identify drugs that target cancer stem cells (CSCs) of breast cancer. Gene expression datasets of CSCs from six studies were subjected to connectivity map to identify drugs that may ameliorate gene expression patterns unique to CSCs. All-trans retinoic acid (ATRA) was negatively connected with gene expression in CSCs. ATRA reduced mammosphere-forming ability of a subset of breast cancer cells, which correlated with induction of apoptosis, reduced expression of SOX2 but elevated expression of its antagonist CDX2. SOX2/CDX2 ratio had prognostic relevance in CSC-enriched breast cancers. K-ras mutant breast cancer cell line enriched for CSCs was resistant to ATRA, which was reversed by MAP kinase inhibitors. Thus, ATRA alone or in combination can be tested for efficacy using SOX2, CDX2, and K-ras mutation/MAPK activation status as biomarkers of response.

Unlocking Doors without Keys: Activation of Src by Truncated C-terminal Intracellular Receptor Tyrosine Kinases Lacking Tyrosine Kinase Activity

One of the best examples of the renaissance of Src as an open door to cancer has been the demonstration that just five min of Src activation is sufficient for transformation and also for induction and maintenance of cancer stem cells [1]. Many tyrosine kinase receptors, through the binding of their ligands, become the keys that unlock the structure of Src and activate its oncogenic transduction pathways. Furthermore, intracellular isoforms of these receptors, devoid of any tyrosine kinase activity, still retain the ability to unlock Src. This has been shown with a truncated isoform of KIT (tr-KIT) and a truncated isoform of VEGFR-1 (i₂₁-VEGFR-1), which are intracellular and require no ligand binding, but are nonetheless able to activate Src and induce cell migration and invasion of cancer cells. Expression of the i₂₁-VEGFR-1 is upregulated by the Notch signaling pathway and repressed by miR-200c and retinoic acid in breast cancer cells. Both Notch inhibitors and retinoic acid have been proposed as potential therapies for invasive breast cancer.

Actin-binding protein alpha-actinin 4 (ACTN4) is a transcriptional co-activator of RelA/p65 sub-unit of NF-kB

ACTN4 is an actin-binding protein that participates in cytoskeleton organisation. It resides both in the cytoplasm and nucleus and physically associates with various transcription factors. Here, we describe an effect of ACTN4 expression on transcriptional activity of the RelA/p65 subunit of NF-kB. We demonstrate that ACTN4 enhances RelA/p65-dependant expression of c-fos, MMP-3 and MMP-1 genes, but it does not affect TNC, ICAM1 and FN1 expression. Importantly, actin-binding domains of ACTN4 are not critical for the nuclear translocation and co-activation of RelA/p65-dependent transcription. Collectively, our data suggest that in the nucleus, ACTN4 functions as a selective transcriptional co-activator of RelA/p65.