Dec1 expression predicts prognosis and the response to temozolomide chemotherapy in patients with glioma

Obstructive sleep apnea-increased DEC1 regulates systemic inflammation and oxidative stress that promotes development of pulmonary arterial hypertension

Obstructive sleep apnea (OSA), characterized by chronic intermittent hypoxia (CIH), is a common risk factor for pulmonary arterial hypertension (PAH). As a hypoxia-induced transcription factor, differentially expressed in chondrocytes (DEC1) negatively regulates the transcription of peroxisome proliferative activated receptor-γ (PPARγ), a recognized protective factor of PAH. However, whether and how DEC1 is associated with PAH pathogenesis remains unclear. In the present study, we found that DEC1 was increased in lungs and pulmonary arterial smooth muscle cells (PASMCs) of rat models of OSA-associated PAH. Oxidative indicators and inflammatory cytokines were also elevated in the blood of the rats. Similarly, hypoxia-treated PASMCs displayed enhanced DEC1 expression and reduced PPARγ expression in vitro. Functionally, DEC1 overexpression exacerbated reactive oxygen species (ROS) production and the expression of pro-inflammatory cytokines (such as TNFα, IL-1β, IL-6, and MCP-1) in PASMCs. Conversely, shRNA knockdown of Dec1 increased PPARγ expression but attenuated hypoxia-induced oxidative stress and inflammatory responses in PASMCs. Additionally, DEC1 overexpression promoted PASMC proliferation, which was drastically attenuated by a PPARγ agonist rosiglitazone. Collectively, these results suggest that hypoxia-induced DEC1 inhibits PPARγ, and that this is a predominant mechanism underpinning oxidative stress and inflammatory responses in PASMCs during PAH. DEC1 could be used as a potential target to treat PAH.

Differentiated embryonic chondrocyte expressed gene-1 (DEC1) enhances the development of colorectal cancer with an involvement of the STAT3 signaling

Colorectal cancer (CRC) is the second deadly and the third most common malignancy worldwide. It has been projected that annual new cases of CRC will increase by 63% in 2040, constituting an even greater health challenge for decades to come. This study has linked DEC1 (differentiated embryonic chondrocyte expressed gene 1) to the pathogenesis of CRC. Based on the analysis of patient samples and database data, DEC1 is expressed much higher in CRC than the adjacent normal tissues. CRC patients with higher DEC1 expression have a shorter survival time. The carcinogenesis protocol with azoxymethane/dextran sulfate induces a higher number of tumors with larger sizes in DEC1^+/+ than DEC1^−/− mice. Overexpression of DEC1 increases the expression of proliferation- and antiapoptosis-related genes, but decreases the level of proapoptotic genes. Mechanistically, this study has shown that DEC1 is functionally looped to the IL-6/STAT3 signaling pathway (interleukin-6/signal transducer and activator of transcription 3). IL-6 induces DEC1, and DEC1 enhances the phosphorylation of STAT3, resulting in increased pSTAT3/STAT3 ratio. DEC1 and STAT3 are present in reciprocal immunocomplexes, pointing to physical interactions (presumably with pSTAT3). These findings establish that DEC1 is a CRC enhancer. The enhancement is achieved largely through the IL-6/STAT3 pathway. The potential of the physical interaction between DEC1 and STAT3 will likely serve as a foundation to develop intervention strategies for CRC prevention and therapy.

Reciprocal Expression of Differentiated Embryonic Chondrocyte Expressed Genes Result in Functional Antagonism in Gastric Cancer

BACKGROUND

Differentiated embryonic chondrocyte expressed genes (DECs) are critical regulators of cellular proliferation and differentiation. However, DEC1 and DEC2 as family member have opposite or identical roles in tumor, acting as an "accelerator" or a "brake" in progression.

AIMS

The possible crosstalk between DEC1 and DEC2 in the gastric cancer (GC).

METHODS

The association of DEC1 and DEC2 expression with prognosis was investigated by immunohistochemistry. The expression pattern of DECs in GC cells was examined using the CCLE database. DECs knockdown or overexpression was conducted via lentiviral transfection. The proliferation of GC cells was evaluated by CCK8, EdU, and Colony forming. ChIP and luciferase reporter assays were used to verify interaction between DEC1 and the DEC2 promoter. The combination downstream with DEC1 and DEC2 was predicted by bioinformation, with Western blot providing further verification.

RESULTS

We found that reciprocal expression of DEC1 and DEC2 works together to sustain the progression of GC by promoting cell growth. We confirmed this observation in vivo, showing that inhibition DEC1expression could increase DEC2 expression. DEC1 suppresses DEC2 expression by directly binding to the E-box of the DEC2 promoter in GC cells. Furthermore, this regulation of DEC1 on DEC2 enables the further indirect or cooperative activation of additional downstream target genes, MAPK, and STAT3.

CONCLUSION

Our data demonstrate that DEC1 and DEC2 interact physically and functionally and identify a novel mode of cross-regulatory interaction between DECs that abrogates their functional activity.

Endothelial Dec1-PPARγ Axis Impairs Proliferation and Apoptosis Homeostasis Under Hypoxia in Pulmonary Arterial Hypertension

Background: The hypoxia-induced pro-proliferative and anti-apoptotic characteristics of pulmonary arterial endothelial cells (PAECs) play critical roles in pulmonary vascular remodeling and contribute to hypoxic pulmonary arterial hypertension (PAH) pathogenesis. However, the mechanism underlying this hypoxic disease has not been fully elucidated.

Methods: Bioinformatics was adopted to screen out the key hypoxia-related genes in PAH. Gain- and loss-function assays were then performed to test the identified hypoxic pathways in vitro. Human PAECs were cultured under hypoxic (3% O₂) or normoxic (21% O₂) conditions. Hypoxia-induced changes in apoptosis and proliferation were determined by flow cytometry and Ki-67 immunofluorescence staining, respectively. Survival of the hypoxic cells was estimated by cell counting kit-8 assay. Expression alterations of the target hypoxia-related genes, cell cycle regulators, and apoptosis factors were investigated by Western blot.

Results: According to the Gene Expression Omnibus dataset (GSE84538), differentiated embryo chondrocyte expressed gene 1-peroxisome proliferative-activated receptor-γ (Dec1-PPARγ) axis was defined as a key hypoxia-related signaling in PAH. A negative correlation was observed between Dec1 and PPARγ expression in patients with hypoxic PAH. In vitro observations revealed an increased proliferation and a decreased apoptosis in PAECs under hypoxia. Furthermore, hypoxic PAECs exhibited remarkable upregulation of Dec1 and downregulation of PPARγ. Dec1 was confirmed to be crucial for the imbalance of proliferation and apoptosis in hypoxic PAECs. Furthermore, the pro-surviving effect of hypoxic Dec1 was mediated through PPARγ inhibition.

Conclusion: For the first time, Dec1-PPARγ axis was identified as a key determinant hypoxia-modifying signaling that is necessary for the imbalance between proliferation and apoptosis of PAECs. These novel endothelial signal transduction events may offer new diagnostic and therapeutic options for patients with hypoxic PAH.

BHLHE40 modulates post-traumatic stress disorder behaviors with the involvement of the PI3K/AKT signaling pathway

Post-traumatic stress disorder (PTSD) is closely related to the exposure to traumatic events and results in the structural and functional changes of hippocampus. Human basic helix-loop-helix family member e40 (BHLHE40) was reported to be implicated with neuron maturity and neuronal differentiation. The present study aimed to reveal the role of BHLHE40 on single-prolonged stress (SPS) model of PTSD in mice. The morris water maze test, open field test and contextual fear test were conducted to assess memory deficits, anxiety-like behaviors, and freezing of mice. Western blot was performed to identify proteins and reveal their levels in hippocampal tissues. We found that mice receiving SPS exhibited increased anxiety-like behaviors, memory deficits, and prolonged freezing time. The protein levels of BHLHE40 were downregulated in the hippocampal tissues of SPS mice. SPS reduced the protein levels of glutamate receptors, while overexpression of BHLHE40 promoted glutamate receptor protein levels in SPS mice. Moreover, BHLHE40 overexpression activated the PI3K/AKT pathway. BHLHE40 overexpression ameliorated the SPS-induced PTSD-like behavioral deficits. Overall, BHLHE40 promotes glutamate receptor protein levels to ameliorate PTSD-like behaviors with the involvement of the PI3K/AKT pathway. This novel discovery may provide a potential target for the improvement of PTSD.

Long noncoding RNA DLEU2 predicts a poor prognosis and enhances malignant properties in laryngeal squamous cell carcinoma through the miR-30c-5p/PIK3CD/Akt axis

Long noncoding RNAs (lncRNAs) have been identified as potential prognostic tools and therapeutic biomarkers for a variety of human cancers. However, the functional roles and underlying mechanisms of key lncRNAs affecting laryngeal squamous cell carcinomas (LSCCs) are largely unknown. Here, we adopted a novel subpathway strategy based on the lncRNA-mRNA profiles from the Cancer Genome Atlas (TCGA) database and identified the lncRNA deleted in lymphocytic leukemia 2 (DLEU2) as an oncogene in the pathogenesis of LSCCs. We found that DLEU2 was significantly upregulated and predicted poor clinical outcomes in LSCC patients. In addition, ectopic overexpression of DLEU2 promoted the proliferation and migration of LSCC cells both in vivo and in vitro. Mechanistically, DLEU2 served as a competing endogenous RNA to regulate PIK3CD expression by sponging miR-30c-5p and subsequently activated the Akt signaling pathway. As a target gene of DLEU2, PIK3CD was also upregulated and could predict a poor prognosis in LSCC patients. In conclusion, we found that the novel LSCC-related gene DLEU2 enhances the malignant properties of LSCCs via the miR-30c-5p/PIK3CD/Akt axis. DLEU2 and its targeted miR-30c-5p/PIK3CD/Akt axis may represent valuable prognostic biomarkers and therapeutic targets for LSCCs.

Potential Role of DEC1 in Cervical Cancer Cells Involving Overexpression and Apoptosis

Basic helix-loop-helix (BHLH) transcription factors differentiated embryonic chondrocyte gene 1 (DEC1) and gene 2 (DEC2) regulate circadian rhythms, apoptosis, epithelial mesenchymal transition (EMT), invasions and metastases in various kinds of cancer. The stem cell markers SOX2 and c-MYC are involved in the regulation of apoptosis and poor prognosis. In cervical cancer, however, their roles are not well elucidated yet. To determine the function of these genes in human cervical cancer, we examined the expression of DEC1, DEC2, SOX2 and c-MYC in human cervical cancer tissues. In immunohistochemistry, they were strongly expressed in cancer cells compared with in non-cancerous cells. Notably, the strong rate of DEC1 and SOX2 expressions were over 80% among 20 cases. We further examined the roles of DEC1 and DEC2 in apoptosis. Human cervical cancer HeLa and SiHa cells were treated with cisplatin-HeLa cells were sensitive to apoptosis, but SiHa cells were resistant. DEC1 expression decreased in the cisplatin-treated HeLa cells, but had little effect on SiHa cells. Combination treatment of DEC1 overexpression and cisplatin inhibited apoptosis and affected SOX2 and c-MYC expressions in HeLa cells. Meanwhile, DEC2 overexpression had little effect on apoptosis and on SOX2 and c-MYC expressions. We conclude that DEC1 has anti-apoptotic effects and regulates SOX2 and c-MYC expressions on apoptosis.

Non-circadian aspects of BHLHE40 cellular function in cancer

While many genes specifically act as oncogenes or tumor suppressors, others are tumor promoters or suppressors in a context-dependent manner. Here we will review the basic-helix-loop-helix (BHLH) protein BHLHE40, (also known as BHLHB2, STRA13, DEC1, or SHARP2) which is overexpressed in gastric, breast, and brain tumors; and downregulated in colorectal, esophageal, pancreatic and lung cancer. As a transcription factor, BHLHE40 is expressed in the nucleus, where it binds to target gene promoters containing the E-box hexanucleotide sequence, but can also be expressed in the cytoplasm, where it stabilizes cyclin E, preventing cyclin E-mediated DNA replication and cell cycle progression. In different organs BHLHE40 regulates different targets; hence may have different impacts on tumorigenesis. BHLHE40 promotes PI3K/Akt/mTOR activation in breast cancer, activating tumor progression, but suppresses STAT1 expression in clear cell carcinoma, triggering tumor suppression. Target specificity likely depends on cooperation with other transcription factors. BHLHE40 is activated in lung and esophageal carcinoma by the tumor suppressor p53 inducing senescence and suppressing tumor growth, but is also activated under hypoxic conditions by HIF-1α in gastric cancer and hepatocellular carcinomas, stimulating tumor progression. Thus, BHLHE40 is a multi-functional protein that mediates the promotion or suppression of cancer in a context dependent manner.

FXR1 promotes the malignant biological behavior of glioma cells via stabilizing MIR17HG

Background

Accumulating evidence has highlighted the potential role of RNA binding proteins (RBPs) in the biological behaviors of glioblastoma cells. Herein, the expression and function of RNA binding proteins FXR1 were investigated in human glioma cells.

Methods

Quantitative real-time PCR were conducted to evaluate the expression of MIR17HG and miR-346, miRNA-425-5p in glioma tissues and cells. Western blot were used to explore the expression of FXR1, TAL1 and DEC1 in glioma tissues and cells. Stable knockdown of FXR1 and MIR17HG in glioma cells were established to explore the function of FXR1, MIR17HG in glioma cells. Further, RIP and RNA pull-down assays were used to investigate the correlation between FXR1 and MIR17HG. Cell Counting Kit-8, transwell assays, and flow cytometry were used to investigate the function of FXR1 and MIR17HG in malignant biological behaviors of glioma cells. ChIP assays were employed to ascertain the correlations between TAL1 and MIR17HG.

Results

FXR1and MIR17HG were upregulated in glioma tissues and cell lines. Downregulation of FXR1 or MIR17HG resulted in inhibition of glioma cells progression. We also found that FXR1 regulates the biological behavior of glioma cells via stabilizing MIR17HG. In addition, downregulated MIR17HG increased miR-346/miR-425-5p expression and MIR17HG acted as ceRNA to sponge miR-346/miR-425-5p. TAL1 was a direct target of miR-346/miR-425-5p, and played oncogenic role in glioma cells. More importantly, TAL1 activated MIR17HG promoter and upregulated its expression, forming a feedback loop. Remarkably, FXR1 knockdown combined with inhibition of MIR17HG resulted in the smallest tumor volumes and the longest survivals of nude mice in vivo.

Conclusions

FXR1/MIR17HG/miR-346(miR-425-5p)/TAL1/DEC1 axis plays a novel role in regulating the malignant behavior of glioma cells, which may be a new potential therapeutic strategy for glioma therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0991-0) contains supplementary material, which is available to authorized users.

Interaction with SP1, but not binding to the E-box motifs, is responsible for BHLHE40/DEC1-induced transcriptional suppression of CLDN1 and cell invasion in MCF-7 cells

Basic helix-loop-helix family member e40 (BHLHE40) is located in 3p26.1 and acts as a transcriptional repressor of the circadian rhythm by suppressing the expression of the clock genes and clock-controlled genes. Recent research indicated that BHLHE40 may be involved in regulating tumor cell progression. However the mechanism by which BHLHE40 regulates the invasion and metastasis of tumor cells is unclear. Our in vitro assays showed that BHLHE40 promoted tumor cell invasion while BHLHE40 silencing by siRNA suppressed tumor cell invasion of MCF-7 cells. BHLHE40 suppressed the mRNA and protein expression of CLDN1 CLDN4 and CDH1 and promoted the expression of SNAI1 and SNAI2. Reporter assays demonstrated that BHLHE40 suppressed CLDN1 transcription but not through direct binding to the E-box motifs in the CLDN1 promoter. Further studies demonstrated BHLHE40 suppressed CLDN1 transcription by preventing the interaction between SP1 and a specific motif within the promoter region of CLDN1. BHLHE40 could not further suppress CLDN1 transactivation after SP1 siRNA transfection that is, BHLHE40-induced suppression of CLDN1 relied on SP1. Furthermore our data indicated that SP1 was a major regulator of CLDN1 transcription by binding to a specific motif that was located at -233 to -61 bp upstream of the transcription start site. Immunoprecipitation and co-localization data revealed an interaction between BHLHE40 and SP1. By constructing deletion mutants we found that the BHLH and Orange regions are both essential for the BHLHE40-SP1 interaction. BHLHE40 probably acts as an inhibitory nuclear cofactor or perhaps recruits other inhibitory cofactors to inhibit the SP1-mediated CLDN1 transactivation. These results suggest that BHLHE40 facilitates cell invasion and may be used as a novel target for breast cancer prevention and treatment.