The dual role of C/EBPδ in cancer.

CCAAT/Enhancer-Binding Protein delta (C/EBPδ) is a transcription factor involved in differentiation and inflammation. While sparsely expressed in adult tissues, aberrant expression of C/EBPδ has been associated with different cancers. Initially, re-expression of C/EBPδ in cell cultures limited tumor cell proliferation, assigning it a tumor suppressor role. However, opposing observations were made in pre-clinical models and patients, suggesting that C/EBPδ not only mediates cell proliferation but dictates a broader spectrum of tumorigenesis-related effects. It is now widely accepted that C/EBPδ contributes to an inflammatory, tumor-promoting microenvironment, aids hypoxia adaption and contributes to the recruitment of blood vessels for improved nutrient supply to tumor cells and facilitated extravasation. This review summarizes the work published on this transcription factor in the field of cancer over the past decade. It points out areas in which a consensus on C/EBPδ's role appears to emerge and seek to explain seemingly contradictory results.

C/EBP-Family Redundancy Determines Patient Survival and Lymph Node Involvement in PDAC.

Pancreatic ductal adenocarcinoma (PDAC) is a dismal disease with a poor clinical prognosis and unsatisfactory treatment options. We previously found that the transcription factor CCAAT/Enhancer-Binding Protein Delta (C/EBPδ) is lowly expressed in PDAC compared to healthy pancreas duct cells, and that patient survival and lymph node involvement in PDAC is correlated with the expression of C/EBPδ in primary tumor cells. C/EBPδ shares a homologous DNA-binding sequence with other C/EBP-proteins, leading to the presumption that other C/EBP-family members might act redundantly and compensate for the loss of C/EBPδ. This implies that patient stratification could be improved when expression levels of multiple C/EBP-family members are considered simultaneously. In this study, we assessed whether the quantification of C/EBPß or C/EBPγ in addition to that of C/EBPδ might improve the prediction of patient survival and lymph node involvement using a cohort of 68 resectable PDAC patients. Using Kaplan-Meier analyses of patient groups with different C/EBP-expression levels, we found that both C/EBPß and C/EBPγ can partially compensate for low C/EBPδ and improve patient survival. Further, we uncovered C/EBPß as a novel predictor of a decreased likelihood of lymph node involvement in PDAC, and found that C/EBPß and C/EBPδ can compensate for the lack of each other in order to reduce the risk of lymph node involvement. C/EBPγ, on the other hand, appears to promote lymph node involvement in the absence of C/EBPδ. Altogether, our results show that the redundancy of C/EBP-family members might have a profound influence on clinical prognoses and that the expression of both C/EPBß and C/EBPγ should be taken into account when dichotomizing patients according to C/EBPδ expression.

C/EBPδ Suppresses Motility-Associated Gene Signatures and Reduces PDAC Cell Migration.

Pancreatic Ductal Adenocarcinoma (PDAC) is among the most aggressive human cancers and occurs globally at an increasing incidence. Metastases are the primary cause of cancer-related death and, in the majority of cases, PDAC is accompanied by metastatic disease at the time of diagnosis, making it a particularly lethal cancer. Regrettably, to date, no curative treatment has been developed for patients with metastatic disease, resulting in a 5-year survival rate of only 11%. We previously found that the protein expression of the transcription factor CCAAT/Enhancer-Binding Protein Delta (C/EBPδ) negatively correlates with lymph node involvement in PDAC patients. To better comprehend the etiology of metastatic PDAC, we explored the role of C/EBPδ at different steps of the metastatic cascade, using established in vitro models. We found that C/EBPδ has a major impact on cell motility, an important prerequisite for tumor cells to leave the primary tumor and to reach distant sites. Our data suggest that C/EBPδ induces downstream pathways that modulate actin cytoskeleton dynamics to reduce cell migration and to induce a more epithelial-like cellular phenotype. Understanding the mechanisms dictating epithelial and mesenchymal features holds great promise for improving the treatment of PDAC.

CEBPD modulates the airway smooth muscle transcriptomic response to glucocorticoids.

BACKGROUND: CCAAT/Enhancer Binding Protein D (CEBPD), a pleiotropic glucocorticoid-responsive transcription factor, modulates inflammatory responses. Of relevance to asthma, expression of CEBPD in airway smooth muscle (ASM) increases with glucocorticoid exposure. We sought to characterize CEBPD-mediated transcriptomic responses to glucocorticoid exposure in ASM by measuring changes observed after knockdown of CEBPD and its impact on asthma-related ASM function. METHODS: Primary ASM cells derived from four donors were transfected with CEBPD or non-targeting (NT) siRNA and exposed to vehicle control, budesonide (100 nM, 18 h), TNFα (10 ng/ml, 18 h), or both budesonide and TNFα. Subsequently, RNA-Seq was used to measure gene expression levels, and pairwise differential expression results were obtained for exposures versus vehicle and knockdown versus control conditions. Weighted gene co-expression analysis was performed to identify groups of genes with similar expression patterns across the various experimental conditions (i.e., CEBPD knockdown status, exposures). RESULTS: CEBPD knockdown altered expression of 3037 genes under at least one exposure (q-value < 0.05). Co-expression analysis identified sets of 197, 152 and 290 genes that were correlated with CEBPD knockdown status, TNFα exposure status, and both, respectively. JAK-STAT signaling pathway genes, including IL6R and SOCS3, were among those influenced by both TNFα and CEBPD knockdown. Immunoblot assays revealed that budesonide-induced IL-6R protein expression and augmented IL-6-induced STAT3 phosphorylation levels were attenuated by CEBPD knockdown in ASM. CONCLUSIONS: CEBPD modulates glucocorticoid responses in ASM, in part via modulation of IL-6 receptor signaling.

C/EBPδ-induced epigenetic changes control the dynamic gene transcription of S100a8 and S100a9.

The proinflammatory alarmins S100A8 and S100A9 are among the most abundant proteins in neutrophils and monocytes but are completely silenced after differentiation to macrophages. The molecular mechanisms of the extraordinarily dynamic transcriptional regulation of S100a8 and S100a9 genes, however, are only barely understood. Using an unbiased genome-wide CRISPR/Cas9 knockout (KO)-based screening approach in immortalized murine monocytes, we identified the transcription factor C/EBPδ as a central regulator of S100a8 and S100a9 expression. We showed that S100A8/A9 expression and thereby neutrophil recruitment and cytokine release were decreased in C/EBPδ KO mice in a mouse model of acute lung inflammation. S100a8 and S100a9 expression was further controlled by the C/EBPδ antagonists ATF3 and FBXW7. We confirmed the clinical relevance of this regulatory network in subpopulations of human monocytes in a clinical cohort of cardiovascular patients. Moreover, we identified specific C/EBPδ-binding sites within S100a8 and S100a9 promoter regions, and demonstrated that C/EBPδ-dependent JMJD3-mediated demethylation of H3K27me3 is indispensable for their expression. Overall, our work uncovered C/EBPδ as a novel regulator of S100a8 and S100a9 expression. Therefore, C/EBPδ represents a promising target for modulation of inflammatory conditions that are characterized by S100a8 and S100a9 overexpression.

Angiogenesis Driven by the CEBPD-hsa-miR-429-VEGFA Signaling Axis Promotes Urothelial Carcinoma Progression.

BACKGROUND AND PURPOSE: This research aimed to excavate the alternative mechanism of CEBPD on tumor growth and explore the biological significance of the CEBPD/hsa-miR-429/VEGFA axis on angiogenesis in urothelial carcinoma (UC). METHODS: Quantitative RT-PCR, immunoblotting assay and tube formation examined the effect of hsa-miR-429 mimic or/and inhibitor on VEGFA expression and angiogenesis in CEBPD-overexpressing UC-derived cells. The association between CEBPD, hsa-miR-429, VEGFA and microvascular density (MVD) and clinical outcome were evaluated in 296 patients with UBUC and 340 patients with UTUC, respectively. RESULTS: The increase in the transcript and protein of VEGFA as well as HUVECs tube formation was diminished upon the treatment of hsa-miR-429 mimic in CEBPD-overexpressing BFTC909 and TCCSUP. Nevertheless, the inhibited regulation of hsa-miR-429 mimic on the expression of VEGFA and ability of HUVECs tube formation was rescued by the combined incubation with hsa-miR-429 inhibitor in these two UC-derived cell lines. Furthermore, the clinical correlations showed that the higher level of VEGFA or MVD has a positive correlation with the expression of CEBPD and a negative relation to hsa-miR-429 and leads to tumor aggressiveness with worse disease-specific, metastasis-free survival in UBUC and UTUC cohorts. CONCLUSIONS: We decipher the oncogenic mechanism of CEBPD on angiogenesis through the hsa-miR-429 inhibition to stabilize the expression of VEGFA in UC. The novel research unveiled the modulation of the CEBPD/hsa-miR-429/VEGFA axis on the progression of UC and could be accessible to theranostic biomarkers.

CCAAT/enhancer binding protein (C/EBP) delta promotes the expression of PTX3 and macrophage phagocytosis during A. fumigatus infection.

Given the increasing incidence of pulmonary aspergillosis, it is important to understand the natural defense mechanisms by which the body can kill Aspergillus fumigatus conidia. Pentraxin 3 (PTX3) plays a nonredundant role in resistance to A. fumigatus. Here, we found that the key predicted PTX3 transcription factor, CCAAT/enhancer-binding protein δ (CEBPD), was up-regulated during A. fumigatus conidia infection. Functionally, CEBPD significantly promoted the expression of PTX3 and the phagocytic ability of macrophages. Mechanistically, CEBPD activated the PTX3 by directly binding to the promoter region of the PTX3 gene. We also showed that the RNA-binding protein human antigen R promoted CEBPD expression. These findings provide new insights into the crucial role of CEBPD in the phagocytosis of A. fumigatus conidia by macrophages and highlight this protein as a potential therapeutic target for invasive pulmonary aspergillosis.

PERK signaling through C/EBPδ contributes to ER stress-induced expression of immunomodulatory and tumor promoting chemokines by cancer cells.

Cancer cells experience endoplasmic reticulum (ER) stress due to activated oncogenes and conditions of nutrient deprivation and hypoxia. The ensuing unfolded protein response (UPR) is executed by ATF6, IRE1 and PERK pathways. Adaptation to mild ER stress promotes tumor cell survival and aggressiveness. Unmitigated ER stress, however, will result in cell death and is a potential avenue for cancer therapies. Because of this yin-yang nature of ER stress, it is imperative that we fully understand the mechanisms and dynamics of the UPR and its contribution to the complexity of tumor biology. The PERK pathway inhibits global protein synthesis while allowing translation of specific mRNAs, such as the ATF4 transcription factor. Using thapsigargin and tunicamycin to induce acute ER stress, we identified the transcription factor C/EBPδ (CEBPD) as a mediator of PERK signaling to secretion of tumor promoting chemokines. In melanoma and breast cancer cell lines, PERK mediated early induction of C/EBPδ through ATF4-independent pathways that involved at least in part Janus kinases and the STAT3 transcription factor. Transcriptional profiling revealed that C/EBPδ contributed to 20% of thapsigargin response genes including chaperones, components of ER-associated degradation, and apoptosis inhibitors. In addition, C/EBPδ supported the expression of the chemokines CXCL8 (IL-8) and CCL20, which are known for their tumor promoting and immunosuppressive properties. With a paradigm of short-term exposure to thapsigargin, which was sufficient to trigger prolonged activation of the UPR in cancer cells, we found that conditioned media from such cells induced cytokine expression in myeloid cells. In addition, activation of the CXCL8 receptor CXCR1 during thapsigargin exposure supported subsequent sphere formation by cancer cells. Taken together, these investigations elucidated a novel mechanism of ER stress-induced transmissible signals in tumor cells that may be particularly relevant in the context of pharmacological interventions.

CEBPD Potentiates the Macrophage Inflammatory Response but CEBPD Knock-Out Macrophages Fail to Identify CEBPD-Dependent Pro-Inflammatory Transcriptional Programs.

CCAAT/enhancer-binding protein delta (C/EBPδ) is a member of the C/EBP family of transcription factors. According to the current paradigm, C/EBPδ potentiates cytokine production and modulates macrophage function thereby enhancing the inflammatory response. Remarkably, however, C/EBPδ deficiency does not consistently lead to a reduction in Lipopolysaccharide (LPS)-induced cytokine production by macrophages. Here, we address this apparent discrepancy and show that the effect of C/EBPδ on cytokine production and macrophage function depends on both the macrophage subtype and the LPS concentration used. Using CRISPR-Cas generated macrophages in which the transactivation domain of C/EBPδ was deleted from the endogenous locus (ΔTAD macrophages), we next show that the context-dependent role of C/EBPδ in macrophage biology relies on compensatory transcriptional activity in the absence of C/EBPδ. We extend these findings by revealing a large discrepancy between transcriptional programs in C/EBPδ knock-out and C/EBPδ transactivation dead (ΔTAD) macrophages implying that compensatory mechanisms do not specifically modify C/EBPδ-dependent inflammatory responses but affect overall macrophage biology. Overall, these data imply that knock-out approaches are not suited for identifying the genuine transcriptional program regulated by C/EBPδ, and we suggest that this phenomenon applies for transcription factor families in general.

Non-Tumor CCAAT/Enhancer-Binding Protein Delta Potentiates Tumor Cell Extravasation and Pancreatic Cancer Metastasis Formation.

CCAAT/enhancer-binding protein delta (C/EBPδ) is a transcription factor involved in apoptosis and proliferation, which is downregulated in pancreatic ductal adenocarcinoma (PDAC) cells. Loss of nuclear C/EBPδ in PDAC cells is associated with decreased patient survival and pro-tumorigenic properties in vitro. Interestingly however, next to C/EBPδ expression in tumor cells, C/EBPδ is also expressed by cells constituting the tumor microenvironment and by cells comprising the organs and parenchyma. However, the functional relevance of systemic C/EBPδ in carcinogenesis remains elusive. Here, we consequently assessed the potential importance of C/EBPδ in somatic tissues by utilizing an orthotopic pancreatic cancer model. In doing so, we show that genetic ablation of C/EBPδ does not significantly affect primary tumor growth but has a strong impact on metastases; wildtype mice developed metastases at multiple sites, whilst this was not the case in C/EBPδ-/- mice. In line with reduced metastasis formation in C/EBPδ-/- mice, C/EBPδ-deficiency also limited tumor cell dissemination in a specific extravasation model. Tumor cell extravasation was dependent on the platelet-activating factor receptor (PAFR) as a PAFR antagonist inhibited tumor cell extravasation in wildtype mice but not in C/EBPδ-/- mice. Overall, we show that systemic C/EBPδ facilitates pancreatic cancer metastasis, and we suggest this is due to C/EBPδ-PAFR-dependent tumor cell extravasation.

Glycyrrhizic acid suppresses early stage of adipogenesis through repression of MEK/ERK-mediated C/EBPß and C/EBPδ expression in 3T3-L1 cells.

Glycyrrhizic acid (GA), a major constituent of the root of licorice (Glycyrrhiza glabra), and has various biological activities, including anti-obesity property. However, the molecular mechanism of anti-adipogenic effect of GA is still unclear. In this study, we investigated the anti-adipogenic effects of GA in mouse adipocytic 3T3-L1 cells and elucidated its underlying molecular mechanism. GA decreased the intracellular triglyceride level. The expression levels of the adipogenic and lipogenic genes were lowered by treatment with GA in a concertation-dependent manner. In contrast, GA did not affect the lipolytic gene expression and the released glycerol level. GA suppressed the early stage of adipogenesis when it was added for 0-3 h after initiation of adipogenesis. Moreover, GA reduced the mRNA levels of CCAAT/enhancer binding protein (C/EBP) ß and C/EBPδ, both of which activate the early stage of adipogenesis. Furthermore, GA decreased phosphorylation of extracellular signal-regulated kinase [ERK: p44/42 mitogen-activated protein kinase (MAPK)] in the early stage of adipogenesis. In addition, a MAPK kinase (MEK) inhibitor, PD98059 reduced the C/EBPß and C/EBPδ gene expression. These results indicate that GA suppressed the early stage of adipogenesis through repressing the MEK/ERK-mediated C/EBPß and C/EBPδ expression in 3T3-L1 cells. Thus, GA has an anti-adipogenic ability and a possible agent for treatment of obesity.

Activation of the ß-adrenergic receptor exacerbates lipopolysaccharide-induced wasting of skeletal muscle cells by increasing interleukin-6 production.

The skeletal muscle mass has been shown to be affected by catecholamines, such as epinephrine (Epi), norepinephrine (NE), and isoproterenol (ISO). On the other hand, lipopolysaccharide (LPS), one of the causative substances of sepsis, induces muscle wasting via toll-like receptors expressed in skeletal muscle. Although catecholamines are frequently administered to critically ill patients, it is still incompletely understood how these drugs affect skeletal muscle during critical illness, including sepsis. Herein, we examined the direct effects of catecholamines on LPS-induced skeletal muscle wasting using the C2C12 myoblast cell line. Muscle wasting induced by catecholamines and/or LPS was analyzed by the use of the differentiated C2C12 myotubes, and its underlying mechanism was explored by immunoblotting analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and the TransAM kit for p-65 NF-κB. Epi augmented myosin heavy chain (MHC) protein loss and reduction of the myotube diameter induced by LPS. LPS induced C/EBPδ protein, Atrogin-1 and inteleukin-6 (IL-6), and these responses were potentiated by Epi. An IL-6 inhibitor, LMT28, suppressed the potentiating effect of Epi on the LPS-induced responses. NF-κB activity was induced by LPS, but was not affected by Epi and recombinant IL-6, and the NF-κB inhibitor, Bay 11-7082, abolished Atrogin-1 mRNA expression induced by LPS with or without Epi. NE and ISO also potentiated LPS-induced IL-6 and Atroign-1 mRNA expression. Carvedilol, a nonselective ß-adrenergic receptor antagonist, suppressed the facilitating effects of Epi on the Atrogin-1 mRNA induction by LPS, and abolished the effects of Epi on the MHC protein loss in the presence of LPS. It was concluded that Epi activates the ß-adrenergic receptors in C2C12 myotubes and the IL-6-STAT3 pathway, leading to the augmentation of LPS-induced activation of the NF-κB- C/EBPδ-Atrogin-1 pathway and to the exacerbation of myotube wasting.

The STAT3 inhibitor Stattic acts independently of STAT3 to decrease histone acetylation and modulate gene expression.

Signal transducer and activator of transcription 3 (STAT3) is an important transcription factor involved in many physiological functions including embryonic development and immune responses and is often activated under pathological conditions such as cancer. Strategies to inactivate STAT3 are being pursued as potential anticancer therapies and have led to the identification of Stattic (6-nitrobenzo[b]thiophene-1,1-dioxide) as a "specific" STAT3 inhibitor that is often used to interrogate STAT3-mediated gene expression in vitro and in vivo. Here, we show that Stattic exerts many STAT3-independent effects on cancer cells, calling for reassessment of results previously ascribed to STAT3 functions. Studies of the STAT3-deficient prostate cancer cell line PC-3 (PC3) along with STAT3-proficient breast cancer cell lines (MDA-MB-231, SUM149) revealed that Stattic attenuated histone acetylation and neutralized effects of the histone deacetylase (HDAC) inhibitor romidepsin. In PC3 cells, Stattic alone inhibited gene expression of CCL20 and CCL2, but activated expression of TNFA, CEBPD, SOX2, and MYC. In addition, we found that Stattic promoted autophagy and caused cell death. These data point to profound epigenetic effects of Stattic that are independent of its function as a STAT3 inhibitor. Our results demonstrate that Stattic directly or indirectly reduces histone acetylation and suggest reevaluation of Stattic and related compounds as polypharmacological agents through multipronged cytotoxic effects on cancer cells.

Shikonin inhibits CEBPD downregulation in IL­17­treated HaCaT cells and in an imiquimod­induced psoriasis model.

Psoriasis is a chronic inflammatory skin disease characterized by well­defined scaly papules and plaques. Interleukin (IL)­17 is involved in its pathogenesis and promotes the proliferation of epidermal keratinocytes through signal transducer and activator of transcription 3 (STAT3) activation. Shikonin, a natural naphthoquinone isolated from Lithospermum erythrorhizon, possesses anti­inflammatory and immunosuppressive properties and can suppress IL­17­induced vascular endothelial growth factor expression by inhibiting the JAK/STAT3 pathway. In the present study, MTS, iCELLigence and RT­qPCR were used to determine the optimal concentration and duration of IL­17 or shikonin acting on HaCaT cells. The changes in the expression levels of genes associated with the IL­6/STAT3 pathway in differentially treated cells were analyzed via RT2Profiler™ PCR Array. Small interfering RNA was used to silence the expression levels of the target gene CCAAT/enhancer­binding protein δ (CEBPD). Western blotting and immunohistochemistry were used to evaluate the effect of shikonin on imiquimod­induced psoriasis in mice and the expression levels of CEBPD. Shikonin reversed IL­17­mediated downregulation of the tumor suppressor CEBPD in HaCaT cells. Moreover, low levels of CEBPD in the imiquimod­induced mouse model of psoriasis were restored by shikonin treatment, which ameliorated excessive keratinocyte proliferation. Taken together, these findings suggest that CEBPD plays a key role in the pathogenesis of psoriasis and can be targeted by shikonin as a potential therapeutic strategy.

Inhibiting Importin 4-mediated nuclear import of CEBPD enhances chemosensitivity by repression of PRKDC-driven DNA damage repair in cervical cancer.

Cervical cancer (CC) remains highest in the mortality of female reproductive system cancers, while cisplatin (CDDP) resistance is the one of main reasons for the lethality. Preceding evidence has supported that karyopherins are associated with chemoresistance. In this study, we simultaneously compared CDDP-incomplete responders with CDDP-complete responders of CC patients and CDDP-insensitive CC cell lines with CDDP-sensitive group. We finally identified that DNA-PKcs (PRKDC) was related to CDDP sensitivity after overlapping in CC sample tissues and CC cell lines. Further functional assay revealed that targeting PRKDC by shRNA and NU7026 (specific PRKDC inhibitor) could enhance CDDP sensitivity in vitro and in vivo, which was mediated by impairing DNA damage repair pathway in CC. Mechanistically, we found that PRKDC was transcriptionally upregulated by CCAAT/enhancer-binding protein delta (CEBPD), while intriguingly, CDDP treatment strengthened the transcriptional activity of CEBPD to PRKDC. We further disclosed that Importin 4 (IPO4) augmented the nuclear translocation of CEBPD through nuclear localization signals (NLS) to activate PRKDC-mediated DNA damage repair in response to CDDP. Moreover, we demonstrated that IPO4 and CEBPD knockdown improved CDDP-induced cytotoxicity in vitro and in vivo. Together, we shed the novel insight into the role of IPO4 in chemosensitivity and provide a clinical translational potential to enhance CC chemosensitivity since the IPO4-CEBPD-PRKDC axis is actionable via NU7026 (PRKDC inhibitor) or targeting IPO4 in combination with CDDP.

Maternal administration of probiotics promotes brain development and protects offspring's brain from postnatal inflammatory insults in C57/BL6J mice.

Neonatal morbidities are associated with long term neurological deficits in life and have also been associated with dysbiosis. We tested whether optimizing the neonate's microbiome through maternal probiotic supplementation can improve offspring's neurodevelopmental outcomes. Maternal LB supplementation, carried out by giving Lactobacillus acidophilus and Bifidobacterium infantis (LB) to pregnant C57/BL6J mice daily from E16 to weaning, significantly suppressed postnatal peripheral proinflammatory insult-induced systemic inflammation and normalized compromised blood-brain barrier permeability and tight junction protein expression in the offspring at pre-weaned age. Maternal LB exposure also regulated markers associated with leukocyte transendothelial migration, extracellular matrix injury and neuroinflammation. The suppressed neuroinflammation by maternal LB supplementation was associated with reduced astrocyte/microglia activation and downregulation of the transcriptional regulators CEBPD and IκBα. Furthermore, maternal LB supplementation promoted neuronal and oligodendrocyte progenitor cell development. Our study demonstrates the efficacy of maternal LB supplementation in modulating systemic and central nervous system inflammation as well as promoting neural/oligodendrocyte progenitor development in the offspring. This evidence suggests that maternal probiotic supplementation may be a safe and effective strategy to improve neurological outcomes in the offspring.

MiR-324-5p/PTPRD/CEBPD axis promotes papillary thyroid carcinoma progression via microenvironment alteration.

MiR-324-5p is overexpressed in papillary thyroid carcinoma (PTC) with lymph node metastasis and promotes malignant phenotypes of KTC-1 cell line. However, the detailed regulatory mechanism remains unknown. Tumor microenvironment plays a key role in tumor progression. CCAAT enhancer-binding protein delta (CEBPD) is important in immune and inflammatory responses. In this study, we investigated the interaction between miR-324-5p/PTPRD/CEBPD axis and tumor microenvironment in PTC progression. K1 and KTC-1 were transfected by lenti-CEBPD or CEBPD-sh vectors. Supernatant from different groups was harvested and added into culture media of human macrophages and HUVEC. Cell viability, colony formation, invasive and migrated cell number, and gap closure rate were elevated in lenti-CEBPD group. Compared with the control, supernatant from lenti-CEBPD group contained more abundant levels of VEGF and IL-4/IL-13, which, respectively, induced higher HUVEC invasion/migration rates and more obvious M2 marker (CD206) and genes (PPAR-γ and MRC-1) expression in macrophages. By means of luciferase reporter assay and gene manipulation, we identified that CEBPD was negatively regulated in PTC by protein tyrosine phosphatase receptor delta (PTPRD) which was the target of miR-324-5p. CEBPD-shRNA was also proved to reverse the effect of PTPRD-sh1 or miR-324-5p mimic on IL-4/IL-13 expression and HUVEC invasion. These results suggested that miR-324-5p/PTPRD/CEBPD axis was involved in the progression of PTC by inducing HUVEC invasion/migration and macrophage M2 polarization via VEGF and IL4/IL13, respectively.

Anti-Obesity Effect of Ginkgo Vinegar, a Fermented Product of Ginkgo Seed Coat, in Mice Fed a High-Fat Diet and 3T3-L1 Preadipocyte Cells.

Ginkgo seed coat is rarely used and is typically discarded, due to its offensive odor and its toxicity. Ginkgo vinegar is a fermented product of ginkgo seed coat, and fermentation removes the bad smell and most of the toxicity. Thus, ginkgo vinegar contains very low concentrations of toxic components. The present study examined the anti-obesity effect of ginkgo vinegar in mice fed a high-fat diet and its inhibition of adipogenesis in 3T3-L1 cells. Ginkgo vinegar suppressed high-fat diet-induced body weight gain and reduced the size of fat cells in mice. Ginkgo vinegar suppressed the expression of C/EBPδ and PPARγ, key proteins in adipogenesis, and inhibited lipid accumulation in 3T3-L1 cells that were induced to become adipocytes. These results suggested that ginkgo vinegar inhibited adipocyte differentiation. On the other hand, a corresponding concentration of acetic acid had significantly less effect on lipid accumulation and virtually no effect on adipogenic gene expression. These results suggested that, similar to Ginkgo biloba extract, ginkgo vinegar might prevent and improve adiposity. Therefore, ginkgo seed coat could be a useful material for medicinal ingredients.

Paeonol, an Ingredient of Kamishoyosan, Reduces Intracellular Lipid Accumulation by Inhibiting Glucocorticoid Receptor Activity in 3T3-L1 Cells.

Excessive triglyceride accumulation in lipid-metabolizing tissues is associated with an increased risk of a variety of metabolic diseases. Kamishoyosan (KSS) is a Kampo composed of 10 constituent herbs, and contains moutan cortex (MC) and paeonol (PN) as the major ingredient of MC. Here, we demonstrate the molecular mechanism underlying the effect of KSS on the differentiation of mouse preadipocytes (3T3-L1 cells). KSS inhibited the accumulation of triglycerides in a dose-dependent manner in 3T3-L1 cells that were induced to differentiate into adipocytes. We also found that MC and PN were responsible for the anti-adipogenetic effect of KSS and significantly suppressed the expression of CCAAT/enhancer-binding proteins-δ (C/EBP-δ) mRNA 3 days after the induction of differentiation. Thus, PN may contribute to the anti-adipogenetic property of MC in 3T3-L1 cells. In addition, PN inhibited dexamethasone (Dex)-induced glucocorticoid receptor (GR) promoter activity. Taken together, these results suggest that PN suppresses C/EBP-δ expression by inhibiting Dex-induced GR promoter activity at the early stage of differentiation and, consequently, delays differentiation into mature adipocytes. Our results suggest that the habitual intake of Kampo-containing PN contributes to the prevention of the onset of metabolic diseases by decreasing the excessive accumulation of triglycerides in lipid-metabolizing tissues.

Dominant-Negative ATF5 Compromises Cancer Cell Survival by Targeting CEBPB and CEBPD.

The basic leucine zipper transcription factor ATF5 is overexpressed in many tumor types and interference with its expression or function inhibits cancer cell survival. As a potential therapeutic approach to exploit these findings, we created dominant-negative (DN) ATF5 forms lacking DNA-binding ability that retain the ATF5 leucine zipper, and thus associate with and sequester ATF5's requisite leucine zipper-binding partners. Preclinical studies with DN-ATF5, including a cell-penetrating form, show in vitro and in vivo efficacy in compromising cancer cell survival. However, DN-ATF5's targets, and particularly those required for tumor cell survival, have been unknown. We report that cells lacking ATF5 succumb to DN-ATF5, indicating that ATF5 itself is not DN-ATF5's obligate target. Unbiased pull-down assays coupled with mass spectrometry and immunoblotting revealed that DN-ATF5 associates in cells with the basic leucine zipper proteins CEBPB and CEBPD and coiled-coil protein CCDC6. Consistent with DN-ATF5 affecting tumor cell survival by suppressing CEBPB and CEBPD function, DN-ATF5 interferes with CEBPB and CEBPD transcriptional activity, while CEBPB or CEBPD knockdown promotes apoptotic death of multiple cancer cells lines, but not of normal astrocytes. We propose a two-pronged mechanism by which DN-ATF5 kills tumor cells. One is by inhibiting heterodimer formation between ATF5 and CEBPB and CDBPD, thus suppressing ATF5-dependent transcription. The other is by blocking the formation of transcriptionally active CEBPB and CEBPD homodimers as well as heterodimers with partners in addition to ATF5. IMPLICATIONS: This study indicates that the potential cancer therapeutic DN-ATF5 acts by associating with and blocking the transcriptional activities of CEBPB and CEBPD.