The hypoxia-regulated transcription factor DEC1 (Stra13, SHARP-2) and its expression in gastric cancer

Differentiated Embryo-Chondrocyte Expressed Gene1 and Parkinson's Disease: New Insights and Therapeutic Perspectives

Differentiated embryo-chondrocyte expressed gene1 (DEC1), an important transcription factor with a basic helix-loop-helix domain, is ubiquitously expressed in both human embryonic and adult tissues. DEC1 is involved in neural differentiation and neural maturation in the central nervous system (CNS). Recent studies suggest that DEC1 protects against Parkinson's disease (PD) by regulating apoptosis, oxidative stress, lipid metabolism, immune system, and glucose metabolism disorders. In this review, we summarize the recent progress on the role of DEC1 in the pathogenesis of PD and provide new insights into the prevention and treatment of PD and neurodegenerative diseases.

Upregulation of INHBA mediated by the transcription factor BHLHE40 promotes colon cancer cell proliferation and migration

BACKGROUND

Colon cancer is highly prevalent, and cell proliferation and migration are major reasons for its progression to malignancy. The upregulation of INHBA, a glycoprotein hormone that regulates the secretion of pituitary hormones, is documented to be oncogenic in numerous cancers, consisting of breast, gastric, and ovarian cancer. Herein, we assessed the role of INHBA in the proliferation along with the migration of colon cancer cells.

METHODS

TCGA datasets were used to assess INHBA expression and its correlation with prognosis in colon cancer patients. Analyses on JASPAR, PROMO, and ENCODE databases, uncovered high correlation between INHBA and BHLHE40. Western blot and RT-qPCR analysis were used to determine protein and mRNA levels. Cell transfection inhibited the expression of INHBA and BHLHE40. Cell proliferation rates were determined using CCK8 analysis. Wound healing assays were adopted to explore cell migration.

RESULTS

INHBA is markedly elevated in colon cancer tissues along with cells and is a predictive factor for patient's prognosis with colon cancer. INHBA silencing suppressed colon cancer cell proliferation and migration. Furthermore, we confirmed the association of INHBA with BHLHE40 in colon cancer cells. BHLHE40 could directly modulates INHBA expression. Here, we show that BHLHE40 modulates the expression of INHBA, which influences the proliferation, and migration of colon cancer cells.

CONCLUSION

INHBA acts as an oncogene in colon cancer and it can be regulated by the transcription factor BHLHE40.

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.

Differentiated embryo chondrocyte 1, induced by hypoxia-inducible factor 1α, promotes cell migration in oral squamous cell carcinoma cell lines

OBJECTIVE

This study aimed to explore the correlation between differentiated embryo chondrocyte 1 (DEC1) and hypoxia-inducible factor 1α (HIF-1α) in oral squamous cell carcinoma (OSCC) and how they participate in tumor progression.

STUDY DESIGN

An immunohistochemical staining method was used to detect the expression of HIF-1α and DEC1 in 64 OSCC specimens, and the correlation between HIF-1α and DEC1 was analyzed. The expression of HIF-1α and DEC1 in OSCC cells under normoxic and hypoxic environments was assessed and analyzed by Western blotting and immunofluorescence. Furthermore, the DEC1 gene was silenced by siRNA and treated with cobalt chloride (CoCl₂) to analyze the effects that DEC1 and hypoxia might have on the migration ability of OSCC cells.

RESULTS

The expression of HIF-1α and DEC1 in OSCC was positively correlated. Using CoCl₂ to simulate a hypoxic environment increased the protein levels of HIF-1α and DEC1 in OSCC cells. The HIF-1α inhibitor LW6 decreased HIF-1α and DEC1 expression in OSCC cells in a hypoxic environment. Silencing the DEC1 gene reduced the migration ability of OSCC cells.

CONCLUSION

The hypoxic environment in OSCC could upregulate the expression of DEC1 by increasing the protein level of HIF-1α, and this process might be involved in the migration of tumor cells.

Bhlhe40/Sirt1 Axis-Regulated Mitophagy Is Implicated in All-Trans Retinoic Acid-Induced Spina Bifida Aperta

Neural tube defects (NTDs) are the most severe congenital malformations that result from failure of neural tube closure during early embryonic development, and the underlying molecular mechanisms remain elusive. Mitophagy is the best-known way of mitochondrial quality control. However, the role and regulation of mitophagy in NTDs have not yet been elucidated. In this study, we used an all-trans retinoic acid (ATRA)-induced rat model to investigate mitophagy and its underlying mechanism in spina bifida aperta (SBA). The results of western blot, immunofluorescence and RT-qPCR analyses indicated that mitophagy was impaired and Sirt1 was downregulated in SBA. Administration of resveratrol-a strong specific Sirt1 activator-activated Sirt1, thus attenuating autophagy suppression and ameliorating SBA. RNA-sequencing and bioinformatics analysis results indicated that transcriptional regulation played an important role in NTDs. A luciferase reporter assay was performed to demonstrate that the transcription factor Bhlhe40 directly bound to and negatively regulated Sirt1 expression. Further, we discovered that the Bhlhe40/Sirt1 axis regulated mitophagy in neural stem cells. Collectively, our results for the first time demonstrate that Bhlhe40/Sirt1 axis regulated mitophagy is implicated in ATRA-induced SBA. Our findings provide new insights into pathogenesis of NTDs and a basis for potential therapeutic targets for NTDs.

Effect of DEC1 on the proliferation, adhesion, invasion and epithelial-mesenchymal transition of osteosarcoma cells

Differentiated embryonic chondrocyte-expressed gene 1 (DEC1) is associated with various types of human cancer; however, there is limited data regarding the functions of DEC1 in osteosarcoma. The present study aimed to examine the expression of DEC1 in human osteosarcoma tissues and cell lines. Furthermore, the effects of DEC1 on the proliferation, adhesion, invasion and epithelial-mesenchymal transition (EMT) of osteosarcoma cells were investigated. Using reverse transcription-quantitative PCR and western blot analysis, it was found that the expression levels of DEC1 were higher in human osteosarcoma tissues and osteosarcoma cell lines than in the controls. Both gain- and loss-of-function experiments suggested that DEC1 promotes the proliferation, adhesion and invasion of osteosarcoma cells in vitro, as determined by MTT, cell adhesion and cell invasion assays, respectively. Additionally, DEC1 was found to upregulate the mesenchymal markers N-cadherin and vimentin, whilst downregulating the epithelial marker E-cadherin. In conclusion, this present study showed increased expression levels of DEC1 in human osteosarcoma tissues and cell lines, and identified that DEC1 may exert its effect on osteosarcoma progression by promoting cell proliferation, adhesion and invasion. Furthermore, DEC1 was shown to have an inducible effect on EMT in osteosarcoma cell lines, thus contributing to the aggressiveness of osteosarcoma cells. This initial study indicated that DEC1 may serve as a novel molecular target for the treatment of osteosarcoma.

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.

Upexpression of BHLHE40 in gastric epithelial cells increases CXCL12 production through interaction with p-STAT3 in Helicobacter pylori-associated gastritis

BHLHE40, a member of the basic helix-loop-helix transcription factor family, has been reported to play an important role in inflammatory diseases. However, the regulation and function of BHLHE40 in Helicobacter pylori (H pylori)-associated gastritis is unknown. We observed that gastric BHLHE40 was significantly elevated in patients and mice with H pylori infection. Then, we demonstrate that H pylori-infected GECs express BHLHE40 via cagA-ERK pathway. BHLHE40 translocates to cell nucleus, and then binds to cagA protein-activated p-STAT3 (Tyr705). The complex increases chemotactic factor CXCL12 expression (production). Release of CXCL12 from GECs fosters CD4⁺ T cell infiltration in the gastric mucosa. Our results identify the cagA-BHLHE40-CXCL12 axis that contributes to inflammatory response in gastric mucosa during H pylori infection.

Expression of DEC2 enhances chemosensitivity by inhibiting STAT5A in gastric cancer

Gastric cancer (GC) is one of the most common cancers. Resistance to 5-fluorouracil (5-Fu)-based chemotherapy is a major cause of treatment failure followed by the poor prognosis of patients. In GC, it was reported that human differentiated embryonic chondrocyte-expressed gene 2 (DEC2), suppressed tumor proliferation and metastasis, but the effect of DEC2 on chemosensitivity of GC cells was unknown. In our study, we found that DEC2 can obviously increase the sensibility of GC cells to 5-Fu by promoting 5-Fu-induced apoptosis. DEC2 overexpression is significantly associated with decreased phosphorylation of STAT5A (P-STAT5A). More importantly, negative correlations between DEC2 with P-STAT5A expression were observed in tissue sections from GC patients. GC patients with low expression levels of DEC2 and high expression levels of P-STAT5A showed a poor prognosis. Furthermore, enhanced chemosensitivity mediated by DEC2 can be reversed by STAT5A which confer GC cells resistance to apoptosis induced by 5-Fu. Together, our results suggest that through inhibiting activation of STAT5A, DEC2 enhances 5-Fu-induced apoptosis and suppression of proliferation in GC cells. These findings will provide new insight for identifying potential targets that can be used to sensitize GC cells to chemotherapy.

The bHLH transcription factor DEC1 promotes thyroid cancer aggressiveness by the interplay with NOTCH1

Aberrant re-activation of transcription factors occurs frequently in cancer. Recently, we found the basic helix-loop-helix transcription factors DEC1 and DEC2 significantly up-regulated in a model of highly aggressive thyroid cancer, raising the hypothesis that these factors might be part of the program driving progression of these tumors. Here, we investigated for the first time the function of DEC1 and DEC2 in thyroid cancer. Using both gain- and loss-of-function approaches, we showed that DEC1 more than DEC2 sustains progression of thyroid cancer by promoting cell growth and invasiveness. We demonstrated that DEC1 controls NOTCH1 expression and that the interplay with the NOTCH pathway is relevant for DEC1 function in thyroid cancer. We confirmed this observation in vivo showing that DEC1 expression is a specific feature of tumor cells, that this transcription factor is significantly over-expressed in all major thyroid cancer histotypes and that its expression correlated with NOTCH1 in these tumors. Finally, we performed RNA-sequencing to define the DEC1-associated gene expression profile in thyroid cancer cells and we discovered that DEC1 drives the expression of many cell cycle-related genes, uncovering a potential new function for this transcription factor in cancer.

DEC1 is required for anti-apoptotic activity of gastric cancer cells under hypoxia by promoting Survivin expression

BACKGROUND

Human differentiated embryonic chondrocyte-expressed gene 1 (DEC1), which has been reported to be overexpressed in several types of cancer, is associated with tumorigenesis through participation in several biological processes. However, the complex mechanisms underlying DEC1 during carcinogenesis are controversial, and its roles in the development and malignancy of gastric cancer (GC) remain unclear.

METHODS

We measured DEC1 expression in human GC cell lines. DEC1 levels in GC cells were downregulated by shRNA lentivirus infection. We also evaluated the effect of DEC1 downregulation on xenograft growth in vivo. The viability and apoptosis of the cells were assayed using the CCK8 assay and flow cytometry. The levels of DEC1, Survivin, and Bcl-2 were evaluated by Western blotting. Luciferase reporter was used to verify the downstream target of DEC1. The association of DEC1 and Survivin expression with prognosis was investigated by immunohistochemistry.

RESULTS

Downregulation of DEC1 inhibits GC cell proliferation in vitro and tumorigenicity in vivo. We observed that hypoxia-induced expression of DEC1 protects GC cells from apoptosis via transcriptional upregulation of Survivin. Furthermore, positive correlations between DEC1 with Survivin expression were observed in tissue sections from GC patients. Notably, GC patients with high expression levels of DEC1 and Survivin showed poor prognosis.

CONCLUSIONS

DEC1 acts as an anti-apoptotic regulator in GC cells under hypoxia by promoting Survivin expression. Our study demonstrates the critical role of the DEC1 in oncogenesis and highlights a novel role for DEC1 in the regulation of cell apoptosis in GC.

Anti-tumor bioactivities of curcumin on mice loaded with gastric carcinoma

Curcumin, a derivative from the dried rhizome of curcuma longa, has been proven to possess anti-tumor effects. However, the detailed molecular mechanisms have not been fully elucidated. In this study, we aimed to explore the anti-tumor mechanisms of curcumin in treating gastric cancer. BALB/C mice grafted with a mouse gastric adenocarcinoma cell line (MFC) were used as the experimental model. Mice received different doses of curcumin after grafting. Tumor size was measured and tumor weight was determined after tumor inoculation. TUNEL assay and flow cytometric analysis were applied to evaluate the apoptosis of the cancer cells. Serum cytokines IFN-γ, TNF-α, granzyme B and perforin were detected by ELISA assay. The anti-tumor effect was determined using cytotoxic T-lymphocyte (CTL) assays and in vivo tumor prevention tests. The expression of DEC1, HIF-1α, STAT3 and VEGF in tumor tissues was examined by immunostaining and analyzed using an Image J analysis system. Compared with controls, tumor growth (size and weight) was significantly inhibited by curcumin treatment (P < 0.05). The apoptotic index in gastric cancer cells was significantly increased in the curcumin treatment group. Splenocyte cells from mice treated with curcumin exhibited higher cytolytic effects on MFC cancer cells than those from mice treated with saline (P < 0.01). The expression of DEC1, HIF-1α, STAT3 and VEGF in tumor tissues was down-regulated after curcumin treatment. Our results indicate that curcumin inhibits the proliferation of gastric carcinoma by inducing the apoptosis of tumor cells, activating immune cells to secrete a large amount of cytokines, and down-regulating the DEC1, HIF-1α, VEGF and STAT3 signal transduction pathways.

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

Differentiated embryo chondrocyte expressed gene 1 (Dec1), a crucial cell differentiation mediator and apoptosis inhibitor, is abundantly expressed in various types of human cancer and is associated with malignant tumor progression. As poor differentiation and low apoptosis are closely associated with poor survival rates and a poor response to radio/chemotherapy in patients with cancer, the prognostic value of Dec1 expression was examined in the present study and its correlation with response to temozolomide (TMZ) chemotherapy was analyzed in patients with glioma. Dec1 expression was analyzed by immunohistochemistry in 157 samples of newly diagnosed glioma and 63 recurrent glioblastoma cases that relapsed during TMZ chemotherapy. Correlations with clinical variables, prognosis and the response to TMZ chemotherapy were analyzed in the newly diagnosed gliomas. Dec1 expression was also compared with the apoptosis index determined by TdT‑mediated dUTP nick ending‑labeling assay in recurrent glioblastomas. The antiglioma effect of TMZ in nude mice xenografts with Dec1 expression was examined in vivo. High expression of Dec1, which was significantly associated with high pathological tumor grade and poor response to TMZ chemotherapy, was demonstrated to be an unfavorable independent prognostic factor and predicted poor survival in patients with newly diagnosed glioma. In patients with recurrent glioblastoma, there was a negative correlation between Dec1 expression and the apoptotic index. In nude mice treated with TMZ, Dec1 overexpression potentiated proliferation, but attenuated TMZ‑induced apoptosis. In conclusion, Dec1 is a prognostic factor for the clinical outcome and a predictive factor for the response to TMZ chemotherapy in patients with glioma.

DEC1 and DEC2 Crosstalk between Circadian Rhythm and Tumor Progression

Clock genes, major regulators of circadian rhythm, are involved in tumor progression. We have shown that clock genes basic helix-loop-helix (BHLH) transcription factors, differentiated embryonic chondrocyte gene 1 (DEC1/BHLHE40/Sharp2/Stra13) and DEC2 (BHLHE41/Sharp1) play important roles in circadian rhythm, cell proliferation, apoptosis, hypoxia response, various stresses, and epithelial-to-mesenchymal transition (EMT) of tumor cells. Various stresses, such as exposure to transforming growth factor-beta (TGF-β), hypoxia, cytokines, serum-free, and anti-tumor drugs affect DEC1 and DEC2 expression. An increased or decreased expression of DEC1 and DEC2 regulated tumor progression. However, DEC1 and DEC2 have opposite effects in tumor progression, where the reason behind remains unclear. We found that DEC2 has circadian expression in implanted mouse sarcoma cells, suggesting that DEC2 regulates tumor progression under circadian rhythm. In addition to that, we showed that DEC1 and DEC2 regulate target genes via positive or negative feedback system in tumor progression. We propose that DEC1 and DEC2 act as an accelerator or a brake in tumor progression. In this review, we summarize current progress of knowledge in the function of DEC1 and DEC2 genes in tumor progression.

Increased expression of interferon signaling genes in the bone marrow microenvironment of myelodysplastic syndromes

Introduction

The bone marrow (BM) microenvironment plays an important role in the pathogenesis of myelodysplastic syndromes (MDS) through a reciprocal interaction with resident BM hematopoietic cells. We investigated the differences between BM mesenchymal stromal cells (MSCs) in MDS and normal individuals and identified genes involved in such differences.

Materials and Methods

BM-derived MSCs from 7 MDS patients (3 RCMD, 3 RAEB-1, and 1 RAEB-2) and 7 controls were cultured. Global gene expression was analyzed using a microarray.

Result

We found 314 differentially expressed genes (DEGs) in RCMD vs. control, 68 in RAEB vs. control, and 51 in RAEB vs. RCMD. All comparisons were clearly separated from one another by hierarchical clustering. The overall similarity between differential expression signatures from the RCMD vs. control comparison and the RAEB vs. control comparison was highly significant (p = 0), which indicates a common transcriptomic response in these two MDS subtypes. RCMD and RAEB simultaneously showed an up-regulation of interferon alpha/beta signaling and the ISG15 antiviral mechanism, and a significant fraction of the RAEB vs. control DEGs were also putative targets of transcription factors IRF and ICSBP. Pathways that involved RNA polymerases I and III and mitochondrial transcription were down-regulated in RAEB compared to RCMD.

Conclusion

Gene expression in the MDS BM microenvironment was different from that in normal BM and exhibited altered expression according to disease progression. The present study provides genetic evidence that inflammation and immune dysregulation responses that involve the interferon signaling pathway in the BM microenvironment are associated with MDS pathogenesis, which suggests BM MSCs as a possible therapeutic target in MDS.

Hypoxia-induced overexpression of DEC1 is regulated by HIF-1α in hepatocellular carcinoma

Hypoxia-inducible factor-1α (HIF-1α) and differentiated embryo-chondrocyte expressed gene 1 (DEC1) are two key factors that protect hepatocellular carcinoma (HCC) cells from a hypoxic microenvironment. However, little is known concerning the effects of hypoxia on the expression of HIF-1α and DEC1 in HCC. In the present study, RT-PCR and western blotting were conducted to assay the mRNA and protein levels of HIF-1α and DEC1 under normoxia and hypoxia induced by exposure to CoCl2 for different time periods (0, 2, 4, 6, 24 and 48 h). In addition, the HIF-1α protein inhibitor, YC-1, was used to analyze the interaction between DEC1 and HIF-1α expression and the related mechanism. Results showed that expression of DEC1 in HCC was significantly upregulated at both the mRNA and protein levels, when compared with that in normal liver cells (P<0.05). Hypoxia induced the upregulation of HIF-1α in a time-dependent manner, which was also observed at the DEC1 mRNA and protein levels (P<0.05). However, hypoxia did not affect the transcription of HIF-1α (P>0.05). A positive correlation was found between HIF-1α and DEC1 expression in both BEL-7402 (r=0.885, P<0.05) and SMMC-7721 cells (r=0.826, P<0.05). Furthermore, inhibition of HIF-1α by YC-1 led to a significant decrease in DEC1 induced by hypoxia (P<0.05). We suggest that hypoxia induced the overexpression of DEC1, the mechanism of which may be related to the upregulation of HIF-1α in HCC. The efficacy of inhibiting HIF-1α and DEC1 expression as a possible treatment for HCC should be assessed in clinical trials.

CD28-inducible transcription factor DEC1 is required for efficient autoreactive CD4+ T cell response

The transcription factor DEC1 is induced by CD28 ligation and is required for optimal CD4⁺ T cell responses and the development of EAE.

During the initial hours after activation, CD4⁺ T cells experience profound changes in gene expression. Co-stimulation via the CD28 receptor is required for efficient activation of naive T cells. However, the transcriptional consequences of CD28 co-stimulation are not completely understood. We performed expression microarray analysis to elucidate the effects of CD28 signals on the transcriptome of activated T cells. We show that the transcription factor DEC1 is highly induced in a CD28-dependent manner upon T cell activation, is involved in essential CD4⁺ effector T cell functions, and participates in the transcriptional regulation of several T cell activation pathways, including a large group of CD28-regulated genes. Antigen-specific, DEC1-deficient CD4⁺ T cells have cell-intrinsic defects in survival and proliferation. Furthermore, we found that DEC1 is required for the development of experimental autoimmune encephalomyelitis because of its critical role in the production of the proinflammatory cytokines GM-CSF, IFN-γ, and IL-2. Thus, we identify DEC1 as a critical transcriptional mediator in the activation of naive CD4⁺ T cells that is required for the development of a T cell–mediated autoimmune disease.

Differentiated embryonic chondrocyte-expressed gene 1 is associated with hypoxia-inducible factor 1α and Ki67 in human gastric cancer

Background

Gastric cancer is a leading causes of cancer-related deaths ,but the underlying molecular mechanisms of its progression are largely unknown. Differentiated embryonic chondrocyte-expressed gene 1 (DEC1), is an important transcription factor involved in the progression of tumors and has recently been identified to be strongly inducible by hypoxia. Little is known about the contribution of DEC1 to the intracellular hypoxia and proliferation signaling events in gastric cancer.

Methods

Immunohistochemistry was used to detect the expression of DEC1, hypoxia-inducible factor 1(HIF-1α) and Ki67 in 173 human gastric cancer samples and adjacent non-tumor tissues samples. The relationship between DEC1, HIF-1α and Ki67 was evaluated.

Results

DEC1 protein was persistently expressed in the nucleus and cytoplasm of gastric cancer tissue. The protein expression of DEC1 and HIF-1α in tumour tissues was 83.8% and 54.3%, respectively, and was significantly higher than that in adjacent normal tissues (83.8% vs 23.7%, P <0.001; 54.3% vs 12.7%, P< 0.001). The expression of DEC1 and HIF-1α was associated with poor histological differentiation. (P < 0. 01). Furthermore, DEC1 level was positively correlated with HIF-1α (P < 0. 01, r=0.290) and Ki67 expression (P < 0. 01, r=0.249).

Conclusion

The upregulation of DEC1 may play an important role in hypoxia regulation and cell proliferation in gastric cancer. The relevant molecular mechanism requires further investigation.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1794565980889391med.motic.com/MoticGallery/Slide?id=08d180cd-5fdb-4cee-830a-0b1fef3311f2&user=2C69F0D6-A478-4A2B-ABF0-BB36763E8025med.motic.com/MoticGallery/Slide?id=4762991d-3f2f-43aa-b4bf-ecdd2c2ae3ec&user=2C69F0D6-A478-4A2B-ABF0-BB36763E8025med.motic.com/MoticGallery/Slide?id=2717f209-b3fd-4e71-b621-0d60ea507a82&user=2C69F0D6-A478-4A2B-ABF0-BB36763E8025

The transcription factor DEC1 (BHLHE40/STRA13/SHARP-2) is negatively associated with TNM stage in non-small-cell lung cancer and inhibits the proliferation through cyclin D1 in A549 and BE1 cells

The objective of the current study was to investigate the expression pattern and clinicopathological significance of differentiated embryo-chondrocyte-expressed gene 1 (DEC1) in patients with non-small-cell lung cancer (NSCLC). In 118 archived NSCLC tissues, the positive rate of DEC1 was reduced in human lung cancer samples (36/118, 30.5 %) compared with adjacent normal lung tissues (106/118, 89.8 %), as measured by immunohistochemical staining. Loss of DEC1 was correlated with poor differentiation (p=0.005) and high p-TNM stage (p=0.002). Consistently, downregulation of DEC1 by siRNA knockdown promoted the growth and colony formation in the A549 lung cancer cell line, and overexpression of DEC1 inhibited the growth and colony formation in the BE1 lung cancer cell line. In addition, a significant negative correlation was found between DEC1 and cyclin D1 (p=0.014) in 118 cases of NSCLC. Knockdown of DEC1 resulted in the upregulation of cyclin D1, and overexpression of DEC1 led to the downregulation of cyclin D1. Together with the observation that DEC1 bound directly to the promoter region of cyclin D1 in A549 cells, these results indicate that loss of DEC1 may promote tumor progression in NSCLC through upregulation of cyclin D1, and DEC1 might serve as a novel therapeutic target of NSCLC.

SUMO modification of Stra13 is required for repression of cyclin D1 expression and cellular growth arrest

Stra13, a basic helix-loop-helix (bHLH) transcription factor is involved in myriad biological functions including cellular growth arrest, differentiation and senescence. However, the mechanisms by which its transcriptional activity and function are regulated remain unclear. In this study, we provide evidence that post-translational modification of Stra13 by Small Ubiquitin-like Modifier (SUMO) dramatically potentiates its ability to transcriptionally repress cyclin D1 and mediate G₁ cell cycle arrest in fibroblast cells. Mutation of SUMO acceptor lysines 159 and 279 located in the C-terminal repression domain has no impact on nuclear localization; however, it abrogates association with the co-repressor histone deacetylase 1 (HDAC1), attenuates repression of cyclin D1, and prevents Stra13-mediated growth suppression. HDAC1, which promotes cellular proliferation and cell cycle progression, antagonizes Stra13 sumoylation-dependent growth arrest. Our results uncover an unidentified regulatory axis between Stra13 and HDAC1 in progression through the G₁/S phase of the cell cycle, and provide new mechanistic insights into regulation of Stra13-mediated transcriptional repression by sumoylation.

Overexpression of the DEC1 protein induces senescence in vitro and is related to better survival in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related death in China and has limited effective therapeutic options except for early surgery, since the underlying molecular mechanism driving its precursor lesions towards invasive ESCC is not fully understood. Cellular senescence is the state of the permanent growth arrest of a cell, and is considered as the initial barrier of tumor development. Human differentiated embryo chondrocyte expressed gene 1 (Dec1) is an important transcription factor that related to senescence. In this study, DEC1 immunohistochemical analysis was performed on tissue microarray blocks constructed from ESCC combined with adjacent precursor tissues of 241 patients. Compared with normal epithelia, DEC1 expression was significantly increased in intraepithelial neoplasia and DEC1 expression was significantly decreased in ESCC in comparison with intraepithelial neoplasia. In vitro, DEC1 overexpression induced cellular senescence, and it inhibited cell growth and colony formation in ESCC cell line EC9706. Fresh esophagectomy tissue sections from five ESCC patients were detected by immunohistochemistry of DEC1 and senescence-associated β-galactosidase (SA-β-Gal) activity, and strongly positive expression of DEC1 was correlated to more senescent cells in these fresh tissue sections. Kaplan – Meier method analysis of the 241 patients revealed that DEC1 expression levels were significantly correlated with the survival of ESCC patients after surgery. The expression levels of DEC1 were also correlated with age, tumor embolus, depth of invasion of ESCC, lymph metastasis status and pTNMs. These results suggest that DEC1 overexpression in precursor lesions of ESCC is a protective mechanism by inducing cellular senescence in ESCC initiation, and DEC1 may be a potential prognostic marker of ESCC.

DEC1 binding to the proximal promoter of CYP3A4 ascribes to the downregulation of CYP3A4 expression by IL-6 in primary human hepatocytes

In this study, we provided molecular evidences that interleukin-6 (IL-6) contributed to the decreased capacity of oxidative biotransformation in human liver by suppressing the expression of cytochrome P450 3A4 (CYP3A4). After human hepatocytes were treated with IL-6, differentially expressed in chondrocytes 1 (DEC1) expression rapidly increased, and subsequently, the CYP3A4 expression decreased continuously. Furthermore, the repression of CYP3A4 by IL-6 occurred after the increase of DEC1 in primary human hepatocytes. In HepG2 cells, knockdown of DEC1 increased the CYP3A4 expression and its enzymatic activity. In addition, it partially abolished the decreased CYP3A4 expression as well as its enzymatic activity induced by IL-6. Consistent with this, overexpression of DEC1 markedly reduced the CYP3A4 promoter activity and the CYP3A4 expression as well as its enzymatic activity. Using sequential truncation and site directed mutagenesis of CYP3A4 proximal promoter with DEC1 construct, we showed that DEC1 specifically bound to CCCTGC sequence in the proximal promoter of CYP3A4, which was validated by EMSA and ChIP assay. These findings suggest that the repression of CYP3A4 by IL-6 is achieved through increasing the DEC1 expression in human hepatocytes, the increased DEC1 binds to the CCCTGC sequence in the promoter of CYP3A4 to form CCCTGC-DEC1 complex, and the complex downregulates the CYP3A4 expression and its enzymatic activity.

SUMOylation of DEC1 protein regulates its transcriptional activity and enhances its stability

Differentiated embryo-chondrocyte expressed gene 1 (DEC1, also known as sharp2, stra13, or BHLHB2) is a mammalian basic helix-loop-helix protein that is involved in many aspects of gene regulation through acting as a transcription factor. Changes in DEC1 expression levels have been implicated in the development of cancers. Using COS-7 cell, we showed that DEC1 can be modified by the small ubiquitin-like modifiers, SUMO1, 2 and 3. Two major SUMOylation sites (K(159) and K(279)) were identified in the C-terminal domain of DEC1. Substitution of either K(159) or K(279) with arginine reduced DEC1 SUMOylation, but substitution of both K(159) and K(279) abolished SUMOylation, and more protein appeared to be retained in the cytoplasm compared to wild-type DEC1. The expression of DEC1 was up-regulated after serum starvation as previously reported, but at the same time, serum starvation also led to more SUMOylation of DEC1. In MCF-7 cells SUMOylation also stabilized DEC1 through inhibiting its ubiquitination. Moreover, SUMOylation of DEC1 promoted its repression of CLOCK/BMAL1-mediated transcriptional activity through recruitment of histone deacetylase1. These findings suggested that posttranslational modification of DEC1 in the form of SUMOylation may serve as a key factor that regulates the function of DEC1 in vivo.

The increased expression of DEC1 gene is related to HIF-1α protein in gastric cancer cell lines

Overexpression of differentiated embryo chondrocyte 1 (DEC1) has been reported to contribute to the cellular differentiation, proliferation, and apoptosis of various cancers. Our previous studies have shown that DEC1 was highly expressed in gastric cancer (GCa) tissues. However, there is no report about the expression of DEC1 in GCa cell lines until now. In this study, We evaluated the mRNA and protein expression of DEC1 and hypoxia-inducible factor 1α (HIF-1α) under normoxic and hypoxic conditions in six GCa cell lines: BGC-823, MGC80-3, MKN1, AGS, FU97 and SGC-7901. An HIF-1α protein inhibitor was used to analyze the association of DEC1 and HIF-1α expression. Under normoxia, the mRNA expression of both HIF-1α and DEC1 was moderate, whereas the protein expression of DEC1 was higher than that of HIF-1α. Hypoxia induced the mRNA expression of DEC1 and the protein expression of HIF-1α and DEC1 in a time-dependent manner but had no effect on the mRNA expression of HIF-1α. Furthermore, inhibition of HIF-1α protein expression resulted in a significant decrease in both the mRNA and protein expression of DEC1. Taken together, DEC1 expression is correlated with HIF-1α protein in GCa cell line, blockage of HIF-1α protein led to reduced DEC1 expression. The efficacy of inhibiting HIF-1α and DEC1 expression should be tested in clinical trials as possible treatment for GCa.

DEC1 nuclear expression: A marker of differentiation grade in hepatocellular carcinoma

AIM: To investigate the expression patterns of human differentiated embryo chondrocyte 1 (DEC1) in hepatocellular carcinoma (HCC) and corresponding adjacent non-tumor and the normal liver tissues, the association between DEC1 expression and histopathological variables and the role of DEC1 in hepatocarcinogenesis.

METHODS: The expression of DEC1 was detected immunohistochemically in 176 paraffin-embedded sections from 63 patients with HCC and 50 subjects with normal liver tissues.

RESULTS: DEC1 protein was persistently expressed in the cytoplasm of hepatocytes in normal liver and HCC tissues. Compared with adjacent non-tumor liver tissues, HCC tissues showed high nuclear expression of DEC1 protein. However, high DEC1 nuclear expression was more frequently detected in well-differentiated (83.3%) than in moderately (27.3%) and poorly differentiated HCC (16.7%). Low DEC1 expression was associated with poor histological differentiation and malignancy progression. A correlation was found between the nuclear expression of DEC1 protein and histological differentiation (r = 0.376, P = 0.024).

CONCLUSION: DEC1 is expressed in the cytoplasm of hepatocytes and because nuclear DEC1 expression is decreased with decreasing differentiation status of HCC, nuclear DEC1 might be a marker of HCC differentiation.

Hypoxia inducible BHLHB2 is a novel and independent prognostic marker in pancreatic ductal adenocarcinoma

AIMS

The cyclic adenosine monophosphate-inducible basic helix-loop-helix (bHLH) domain containing class-B2 transcriptional factor BHLHB2 is differentially expressed in a number of human malignancies. In the present study, the expression, regulation, functions and prognostic impact of BHLHB2 in pancreatic cancer were investigated.

METHODS

Expression analyses were carried out in tissues of the normal pancreas (n=10) and pancreatic ductal adenocarcinoma (n=77) as well as in eight pancreatic cancer cell lines using quantitative RT-PCR, semiquantitative immunohistochemistry, and immunoblot analyses. In vitro functional experiments were conducted using siRNA transfection, hypoxia, serum starvation, apoptosis induction with gemcitabine and actinomycin-D, and invasion assays. Survival analysis was performed using the Kaplan-Meier method. Prognostic factors were determined in a multivariable analysis using a Cox proportional hazards model.

RESULTS

BHLHB2 mRNA and protein expressions were strongly induced by hypoxia and by serum starvation in pancreatic cancer cell lines. BHLHB2 silencing with RNAi had no significant effects on growth and invasion but increased apoptosis resistance against gemcitabine by reducing caspace-3 cleavage. In BHLHB2 silenced cells the ED50 of gemcitabine increased from 13.95 ± 1.353 to 38.70 ± 5.262 nM (p<0.05). Ex vivo, the weak/absent nuclear staining in normal pancreatic ducts and acinar cells was replaced by moderate to strong nuclear/cytoplasmic staining in PanIN lesions and pancreatic cancer cells. Patients with weak/absent nuclear BHLHB2 staining had significantly worse median survival compared to those with strong staining (13 months vs. 27 months, p=0.03). In a multivariable analysis, BHLHB2 staining was an independent prognostic factor (Hazard-Ratio=2.348, 95% CI=1.250-4.411, p=0.008).

CONCLUSIONS

Hypoxia-inducible BHLHB2 expression is a novel independent prognostic marker in pancreatic cancer patients and indicates increased chemosensitivity towards gemcitabine.