The RUNX3 gene--sequence, structure and regulated expression

Runx3 Regulates CD8+ T Cell Local Expansion and CD43 Glycosylation in Mice by H1N1 Influenza A Virus Infection

We have recently reported that transcription factor Runx3 is required for pulmonary generation of CD8+ cytotoxic T lymphocytes (CTLs) that play a crucial role in the clearance of influenza A virus (IAV). To understand the underlying mechanisms, we determined the effects of Runx3 knockout (KO) on CD8+ T cell local expansion and phenotypes using an inducible general Runx3 KO mouse model. We found that in contrast to the lungs, Runx3 general KO promoted enlargement of lung-draining mediastinal lymph node (mLN) and enhanced CD8+ and CD4+ T cell expansion during H1N1 IAV infection. We further found that Runx3 deficiency greatly inhibited core 2 O-glycosylation of selectin ligand CD43 on activated CD8+ T cells but minimally affected the cell surface expression of CD43, activation markers (CD44 and CD69) and cell adhesion molecules (CD11a and CD54). Runx3 KO had a minor effect on lung effector CD8+ T cell death by IAV infection. Our findings indicate that Runx3 differently regulates CD8+ T cell expansion in mLNs and lungs by H1N1 IAV infection. Runx3 is required for CD43 core 2 O-glycosylation on activated CD8+ T cells, and the involved Runx3 signal pathway may mediate CD8+ T cell phenotype for pulmonary generation of CTLs.

RUNX3 inhibits KSHV lytic replication by binding to the viral genome and repressing transcription

Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the gamma herpesvirus family, which can cause human malignancies including Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman's diseases. KSHV typically maintains a persistent latent infection within the host. However, after exposure to intracellular or extracellular stimuli, KSHV lytic replication can be reactivated. The reactivation process of KSHV triggers the innate immune response to limit viral replication. Here, we found that the transcriptional regulator RUNX3 is transcriptionally upregulated by the NF-κB signaling pathway in KSHV-infected SLK cells and B cells during KSHV reactivation. Notably, knockdown of RUNX3 significantly promotes viral lytic replication as well as the gene transcription of KSHV. Consistent with this finding, overexpression of RUNX3 impairs viral lytic replication. Mechanistically, RUNX3 binds to the KSHV genome and limits viral replication through transcriptional repression, which is related to its DNA- and ATP-binding ability. However, KSHV has also evolved corresponding strategies to antagonize this inhibition by using the viral protein RTA to target RUNX3 for ubiquitination and proteasomal degradation. Altogether, our study suggests that RUNX3, a novel host-restriction factor of KSHV that represses the transcription of viral genes, may serve as a potential target to restrict KSHV transmission and disease development.IMPORTANCEThe reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) from latent infection to lytic replication is important for persistent viral infection and tumorigenicity. However, reactivation is a complex event, and the regulatory mechanisms of this process are not fully elucidated. Our study revealed that the host RUNX3 is upregulated by the NF-κB signaling pathway during KSHV reactivation, which can repress the transcription of KSHV genes. At the late stage of lytic replication, KSHV utilizes a mechanism involving RTA to degrade RUNX3, thus evading host inhibition. This finding helps elucidate the regulatory mechanism of the KSHV life cycle and may provide new clues for the development of therapeutic strategies for KSHV-associated diseases.

DNA methylation of RUNX3 promotes the progression of gallbladder cancer through repressing SLC7A11-mediated ferroptosis

Gallbladder cancer (GBC) is a type of rare but highly aggressive cancer with a dismal prognosis. Runt-related transcription factor 3 (RUNX3), a member of the runt-domain family, and its promoter methylation have been widely observed in a variety of human malignancies. However, the biological function and underlying mechanism of RUNX3 in GBC remain elusive. In this study, bisulfate sequencing PCR (BSP), Western blot, and qPCR were applied to identify the expression level and DNA methylation level of RUNX3 in GBC tissues and cells. The transcriptional relationship between RUNX3 and Inhibitor of growth 1 (ING1) was validated by dual-luciferase reporter assay and ChIP assay. A series of gain-of-function and loss-of-function assays were performed to detect the function and the regulatory relationship of RUNX3 in vitro and in vivo. RUNX3 was aberrantly downregulated in GBC cells and tissues caused by DNA Methyltransferase 1 (DNMT1)-mediated methylation, and downregulation of RUNX3 is associated with poor prognosis of GBC patients. Functional experiments reveal that RUNX3 can induce ferroptosis of GBC cells in vitro and in vivo. Mechanistically, RUNX3 induces ferroptosis by activating ING1 transcription, thereby repressing SLC7A11 in a p53-dependent manner. In conclusion, the downregulation of RUNX3 is mediated by DNA methylation, which promotes the pathogenesis of gallbladder cancer through attenuating SLC7A11-mediated ferroptosis. This study gives novel insights into the role of RUNX3 in the ferroptosis of GBC cells, which may contribute to developing potential treatment targets for GBC.

Aberrant circulating tumor DNA methylation and exosomal microRNA biomarkers for early detection of colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) became the third most commonly diagnosed malignancy and the second leading cause of cancer death in 2020. However, the rates of early screening and early diagnosis for CRC remain unsatisfactory. Thus, it is essential to explore the initiating factors of CRC and strategies for its early diagnosis. Research progress in liquid biopsy has led to the finding that circulating tumor-derived DNA (ctDNA) and exosomes play vital roles in early detection of CRC. THE APPLICATIONS OF LIQUID BIOPSY FOR EARLY DETECTION OF COLORECTAL CANCER: Moreover, the increased understanding of epigenetics has highlighted the role of ctDNA methylation in CRC carcinogenesis, and the detection of aberrant ctDNA methylation markers is a feasible strategy for diagnosis of early-stage CRC. Among exosomal markers, microRNAs (miRNAs) are abundant and are the most researched. Upregulated or downregulated expression of exosome-derived miRNAs can indicate the occurrence of early-stage CRC.

FUTURE PERSPECTIVE

The current research progress on aberrant ctDNA methylation and tumor exosomal miRNA biomarkers in early detection of CRC is summarized in this review, and the advantages and shortcomings of the methods are discussed.

RUNX3 in Stem Cell and Cancer Biology

The runt-related transcription factors (RUNX) play prominent roles in cell cycle progression, differentiation, apoptosis, immunity and epithelial-mesenchymal transition. There are three members in the mammalian RUNX family, each with distinct tissue expression profiles. RUNX genes play unique and redundant roles during development and adult tissue homeostasis. The ability of RUNX proteins to influence signaling pathways, such as Wnt, TGFβ and Hippo-YAP, suggests that they integrate signals from the environment to dictate cell fate decisions. All RUNX genes hold master regulator roles, albeit in different tissues, and all have been implicated in cancer. Paradoxically, RUNX genes exert tumor suppressive and oncogenic functions, depending on tumor type and stage. Unlike RUNX1 and 2, the role of RUNX3 in stem cells is poorly understood. A recent study using cancer-derived RUNX3 mutation R122C revealed a gatekeeper role for RUNX3 in gastric epithelial stem cell homeostasis. The corpora of RUNX3^R122C/R122C mice showed a dramatic increase in proliferating stem cells as well as inhibition of differentiation. Tellingly, RUNX3^R122C/R122C mice also exhibited a precancerous phenotype. This review focuses on the impact of RUNX3 dysregulation on (1) stem cell fate and (2) the molecular mechanisms underpinning early carcinogenesis.

Inducible general knockout of Runx3 profoundly reduces pulmonary cytotoxic CD8+ T cells with minimal effect on outcomes in mice following influenza infection

Respiratory viruses pose a continuing and substantive threat to human health globally. Host innate and adaptive immune responses are the critical antiviral defense mechanisms to control viral replication and spread. The present study is designed to determine the role of transcription factor Runx3 in the host immune response to influenza A virus (IAV) infection. As Runx3 is required for embryonic development, we generated an inducible Runx3 global knockout (KO) mouse model and found that Runx3 KO in adult C57BL/6 mice minimally affected thymic function under normal conditions and survival was at least 250 days post Runx3 deletion. We applied the mouse model to IAV infection and found that Runx3 KO resulted in a huge reduction (>85%) in numbers of total and antigen-specific pulmonary CD8⁺ cytotoxic T cells during IAV infection, while it had a minor effect on pulmonary generation of CD4⁺ T cells. To our surprise, this general KO of Runx3 did not significantly alter viral clearance and animal survival following IAV infection. Interestingly, we found that Runx3 KO significantly increased the numbers of pulmonary innate immune cells such as macrophages and neutrophils and the production of pro-inflammatory cytokines during IAV infection. We further found that Runx3 was strongly detected in CCR2⁺ immune cells in IAV-infected mouse lungs and was induced in activated macrophages and dendritic cells (DCs). As pulmonary CD8⁺ cytotoxic T cells play a central role in the clearance of IAV, our findings suggest that Runx3 KO may enhance host innate immunity to compensate for the loss of pulmonary CD8⁺ cytotoxic T cells during IAV infection.

RUNX1 and RUNX3 Genes Expression Level in Adult Acute Lymphoblastic Leukemia-A Case Control Study

The genetic factors of adult acute lymphoblastic leukemia (ALL) development are only partially understood. The Runt-Related Transcription Factor (RUNX) gene family play a crucial role in hematological malignancies, serving both a tumor suppressor and promoter function. The aim of this study was the assessment of relative RUNX1 and RUNX3 genes expression level among adult ALL cases and a geographically and ethnically matched control group. The relative RUNX1 and RUNX3 genes expression level was assessed by qPCR. The investigated group comprised 60 adult patients newly diagnosed with ALL. The obtained results were compared with a group of 40 healthy individuals, as well as clinical and hematological parameters of patients, and submitted for statistical analysis. ALL patients tend to have significantly higher RUNX1 gene expression level compared with controls. This observation is also true for risk group stratification where high-risk (HR) patients presented higher levels of RUNX1. A higher RUNX1 transcript level correlates with greater leukocytosis while RUNX3 expression is reduced in Philadelphia chromosome bearers. The conducted study sustains the hypothesis that both a reduction and increase in the transcript level of RUNX family genes may be involved in leukemia pathogenesis, although their interaction is complex. In this context, overexpression of the RUNX1 gene in adult ALL cases in particular seems interesting. Obtained results should be interpreted with caution. Further analysis in this research field is needed.

EZH2 regulates a SETDB1/ΔNp63α axis via RUNX3 to drive a cancer stem cell phenotype in squamous cell carcinoma

Enhancer of zeste homolog 2 (EZH2) and SET domain bifurcated 1 (SETDB1, also known as ESET) are oncogenic methyltransferases implicated in a number of human cancers. These enzymes typically function as epigenetic repressors of target genes by methylating histone H3 K27 and H3-K9 residues, respectively. Here, we show that EZH2 and SETDB1 are essential to proliferation in 3 SCC cell lines, HSC-5, FaDu, and Cal33. Additionally, we find both of these proteins highly expressed in an aggressive stem-like SCC sub-population. Depletion of either EZH2 or SETDB1 disrupts these stem-like cells and their associated phenotypes of spheroid formation, invasion, and tumor growth. We show that SETDB1 regulates this SCC stem cell phenotype through cooperation with ΔNp63α, an oncogenic isoform of the p53-related transcription factor p63. Furthermore, EZH2 is upstream of both SETDB1 and ΔNp63α, activating these targets via repression of the tumor suppressor RUNX3. We show that targeting this pathway with inhibitors of EZH2 results in activation of RUNX3 and repression of both SETDB1 and ΔNp63α, antagonizing the SCC cancer stem cell phenotype. This work highlights a novel pathway that drives an aggressive cancer stem cell phenotype and demonstrates a means of pharmacological intervention.

ICAP-1 loss impairs CD8+ thymocyte development and leads to reduced marginal zone B cells in mice

ICAP‐1 regulates β1‐integrin activation and cell adhesion. Here, we used ICAP‐1‐null mice to study ICAP‐1 potential involvement during immune cell development and function. Integrin α4β1‐dependent adhesion was comparable between ICAP‐1‐null and control thymocytes, but lack of ICAP‐1 caused a defective single‐positive (SP) CD8⁺ cell generation, thus, unveiling an ICAP‐1 involvement in SP thymocyte development. ICAP‐1 bears a nuclear localization signal and we found it displayed a strong nuclear distribution in thymocytes. Interestingly, there was a direct correlation between the lack of ICAP‐1 and reduced levels in SP CD8⁺ thymocytes of Runx3, a transcription factor required for CD8⁺ thymocyte generation. In the spleen, ICAP‐1 was found evenly distributed between cytoplasm and nuclear fractions, and ICAP‐1^–/– spleen T and B cells displayed upregulation of α4β1‐mediated adhesion, indicating that ICAP‐1 negatively controls their attachment. Furthermore, CD3⁺‐ and CD19⁺‐selected spleen cells from ICAP‐1‐null mice showed reduced proliferation in response to T‐ and B‐cell stimuli, respectively. Finally, loss of ICAP‐1 caused a remarkable decrease in marginal zone B‐ cell frequencies and a moderate increase in follicular B cells. Together, these data unravel an ICAP‐1 involvement in the generation of SP CD8⁺ thymocytes and in the control of marginal zone B‐cell numbers.

Runt-Related Transcription Factor 3 Promotes Acute Myeloid Leukemia Progression

Acute myeloid leukemia (AML) is an aggressive hematological malignancy with high relapse/refractory rate. Genetic and epigenetic abnormalities are driving factors for leukemogenesis. RUNX1 and RUNX2 from the Runt-related transcription factor (RUNX) family played important roles in AML pathogenesis. However, the relationship between RUNX3 and AML remains unclear. Here, we found that RUNX3 was a super-enhancer-associated gene and highly expressed in AML cells. The Cancer Genome Atlas (TCGA) database showed high expression of RUNX3 correlated with poor prognosis of AML patients. We observed that Runx3 knockdown significantly inhibited leukemia progression by inducing DNA damage to enhance apoptosis in murine AML cells. By chromatin immunoprecipitation sequencing (ChIP-seq) analysis, we discovered that RUNX3 in AML cells mainly bound more genes involved in DNA-damage repair and antiapoptosis pathways compared to that in normal bone marrow cells. Runx3 knockdown obviously inhibited the expression of these genes in AML cells. Overall, we identified RUNX3 as an oncogene overexpressed in AML cells, and Runx3 knockdown suppressed AML progression by inducing DNA damage and apoptosis.

Runx Transcription Factors in T Cells-What Is Beyond Thymic Development?

Runx proteins (also known as Runt-domain transcription factors) have been studied for a long time as key regulators of cellular differentiation. RUNX2 has been described as essential for osteogenesis, whereas RUNX1 and RUNX3 are known to control blood cell development during different stages of cell lineage specification. However, recent studies show evidence of complex relationships between RUNX proteins, chromatin-modifying machinery, the cytoskeleton and different transcription factors in various non-embryonic contexts, including mature T cell homeostasis, inflammation and cancer. In this review, we discuss the diversity of Runx functions in mature T helper cells, such as production of cytokines and chemokines by different CD4 T cell populations; apoptosis; and immunologic memory acquisition. We then briefly cover recent findings about the contribution of RUNX1, RUNX2 and RUNX3 to various immunologic diseases. Finally, we discuss areas that require further study to better understand the role that Runx proteins play in inflammation and immunity.

The Preliminary Study for Postoperative Radiotherapy Survival Associated with RUNX3 and TLR9 Expression in Lung Cancer

Background

Many studies have reported that the inflammatory immune response related to TLR9 signaling activation participates in tumor development and affects the treatment outcome. RUNX3 functions as a tumor suppressor by regulating DNA methylation. RUNX3 protein plays an important role in TGF-β signaling pathway that is involved in tumor growth inhibition and apoptosis. At present, radiotherapy is still an important treatment in lung cancer, which induces immune response and affects the therapeutic outcome. The role of TLR9 signaling activation and RUNX3 in this process is not clear.

Methods

In this study, we investigated the expression of TLR9 in tumor and RUNX3 in surrounding tissues by immunohistochemical methods and analyzed the relationship on postoperative survival in lung cancer.

Results

We found that the high expression of TLR9 was the risk factor in postoperative survival of lung cancer with no difference in lifetime. The high expression of RUNX3 in lung cancer with TLR9 signaling activation was in favor of progression-free survival and overall survival in postoperative radiotherapy. It suggested that RUNX3 played an important role in lung cancer radiotherapy. In order to determine the effect of RUNX3 in lung cancer radiation with TLR9 signaling activation, we introduced 5-Aza-2ʹ-deoxycytidine (5-Aza-CdR) and exposed lung cancer A459 cells repeatedly. The high expression of RUNX3 especially RUNX3-B in cells treated with 5-Aza-CdR was observed. We examined that 5-Aza-CdR induced more cell blocking in G2/M phase in combining irradiation.

Conclusion

The result implied that it was feasible to improve radiosensitivity of lung cancer with TLR9 signaling activation by increasing RUNX3 expression, and 5-Aza-CdR was an option in this process.

An evolutionarily-conserved promoter allele governs HMG-CoA reductase expression in spontaneously hypertensive rat

3-Hydroxy-3-methyl glutaryl-coenzyme A reductase (Hmgcr) encodes the rate-limiting enzyme in the cholesterol biosynthesis pathway. The regulation of Hmgcr in rat models of genetic hypertension (viz. Spontaneously Hypertensive Rat [SHR] and its normotensive control Wistar/Kyoto [WKY] strain) is unclear. Interestingly, Hmgcr transcript and protein levels are diminished in liver tissues of SHR as compared to WKY. This observation is consistent with the diminished plasma cholesterol level in SHR animals. However, the molecular basis of these apparently counter-intuitive findings remains completely unknown. Sequencing of the Hmgcr promoter in SHR and WKY strains reveals three variations: A-405G, C-62T and a 11 bp insertion (-398_-388insTGCGGTCCTCC) in SHR. Among these variations, A-405G occurs at an evolutionarily-conserved site among many mammals. Moreover, SHR-Hmgcr promoter displays lower activity than WKY-Hmgcr promoter in various cell lines. Transient transfections of Hmgcr-promoter mutants and in silico analysis suggest altered binding of Runx3 and Srebf1 across A-405G site. On the other hand, C-62T and -398_-388insTGCGGTCCTCC variations do not appear to contribute to the reduced Hmgcr promoter activity in SHR as compared to WKY. Indeed, chromatin immunoprecipitation assays confirm differential binding of Runx3 and Srebf1 to Hmgcr promoter leading to reduced expression of Hmgcr in SHR as compared to WKY under basal as well as cholesterol-modulated conditions. Taken together, this study provides, for the first time, molecular basis for diminished Hmgcr expression in SHR animals, which may account for the reduced circulating cholesterol level in this widely-studied model for cardiovascular diseases.

Waiting in the wings: RUNX3 reveals hidden depths of immune regulation with potential implications for inflammatory bowel disease

BACKGROUND

Complex interactions between the environment and the mucosal immune system underlie inflammatory bowel disease (IBD). The involved cytokine signalling pathways are modulated by a number of transcription factors, one of which is runt-related transcription factor 3 (RUNX3).

OBJECTIVE

To systematically review the immune roles of RUNX3 in immune regulation, with a focus on the context of IBD.

METHODS

Relevant articles and reviews were identified through a Scopus search in April 2020. Information was categorized by immune cell types, analysed and synthesized. IBD transcriptome data sets and FANTOM5 regulatory networks were processed in order to complement the literature review.

RESULTS

The available evidence on the immune roles of RUNX3 allowed for its description in twelve cell types: intraepithelial lymphocyte, Th1, Th2, Th17, Treg, double-positive T, cytotoxic T, B, dendritic, innate lymphoid, natural killer and macrophages. In the gut, the activity of RUNX3 is multifaceted and context-dependent: it may promote homeostasis or exacerbated reactions via cytokine signalling and regulation of receptor expression. RUNX3 is mostly engaged in pathways involving ThPOK, T-bet, IFN-γ, TGF-β/IL-2Rβ, GATA/CBF-β, SMAD/p300 and a number of miRNAs. RUNX3 targets relevant to IBD may include RAG1, OSM and IL-17B. Moreover, in IBD RUNX3 expression correlates positively with GZMM, and negatively with IFNAR1, whereas in controls, it strongly associates with TGFBR3.

CONCLUSIONS

Dysregulation of RUNX3, mostly in the form of deficiency, likely contributes to IBD pathogenesis. More clinical research is needed to examine RUNX3 in IBD.

Elevated expression of RUNX3 co-expressing with EZH2 in esophageal cancer patients from India

Background

Runt related transcription factor3 (RUNX3) is considered as a tumor suppressor gene (TSG) that functions through the TGF-β dependent apoptosis. Promoter methylation of the CpG islands of RUNX3 and overexpression of enhancer of zeste homolog 2 (EZH2) has been suggested to downregulate RUNX3 in cancer.

Methods

Here, we studied the expression of RUNX3 and EZH2 in 58 esophageal tumors along with paired adjacent normal tissue. mRNA levels, protein expressions and cellular localizations of EZH2 and RUNX3 were analyzed using real-time PCR and immunohistochemistry, respectively. DNA methylation was further assessed by the methylation specific-PCR.

Results

Compared to normal tissue, a significant increase in expression of RUNX3 mRNA in 31/57 patient’s tumor tissue (p < 0.04) was observed. The expression of EZH2 was found to be upregulated compared to normal, and a significant positive correlation between EZH2 and RUNX3 expression was observed (p = 0.002). 22 of the 27 unmethylated cases at the promoter region of the RUNX3 had elevated RUNX3 protein expression (p < 0.001).

Conclusion

The data presented in this study provide new insights into the biology of RUNX3 and highlights the need to revisit our current understanding of the role of RUNX3 in cancer.

Histone demethylase Jumonji domain-containing 1A inhibits proliferation and progression of gastric cancer by upregulating runt-related transcription factor 3

The histone demethylase Jumonji domain‐containing 1A (JMJD1A) is overexpressed in multiple cancers and promotes cancer progression. However, the role and mechanism of JMJD1A in gastric cancer (GC) remains poorly understood. Here, we found that JMJD1A could suppress GC cell proliferation and xenograft tumor growth. Using RNA sequencing, we identified runt‐related transcription factor 3 (RUNX3) as a novel target gene of JMJD1A. Mechanistically, we identified that JMJD1A upregulated RUNX3 through co–activating Ets‐1 and reducing the H3K9me1/2 levels at the RUNX3 promoter in GC cells. Functionally, JMJD1A inhibits the growth of GC cells in vivo, which is partially dependent on RUNX3. Moreover, JMJD1A expression was decreased in GC and low expression of JMJD1A was correlated with an aggressive phenotype and a poor prognosis in patients with GC. Importantly, JMJD1A expression was positively associated with RUNX3 expression in GC samples. These studies indicated that JMJD1A upregulates RUNX3 expression via co–activation of transcription factor Ets‐1 to inhibit proliferation of GC cells. Our findings provide new insight into the mechanism by which JMJD1A regulates RUNX3 transcription and suggest that JMJD1A and/or RUNX3 may be used as a therapeutic intervention for GC.

Regulation of RUNX3 Expression by DNA Methylation in Prostate Cancer

Purpose

To investigate the role of DNA methylation in the regulation of Runt-related transcription factor 3 (RUNX3) and the effect of such mechanism on the proliferation of prostate cancer (PCa) cells.

Materials and Methods

The methylation of the RUNX3 in the promoter region in PCa cells was detected by bisulfite-sequencing PCR (BSP). Following treatment of the PCa cells with DNA methylation transferase inhibitor 5-AZA-2'-deoxycytidine (AZA), the effect on methylation level and expression of RUNX3 were analyzed by qRT-PCR, Western blot, and BSP assays. Furthermore, we investigated the effect of the demethylated RUNX3 on proliferation, cell cycle and apoptosis of PCa cells using CCK-8 and flow cytometry assays. Using the DNA methylation transferase (DNMT3b) knockout or overexpression models, the relationship between DNMT3b and RUNX3 methylation was further assessed by qRT-PCR, Western blot and methylation-specific PCR (MSP).

Results

The results indicated that the methylation level of RUNX3 in PCa cell lines was significantly higher than that of normal prostate epithelial (RWPE-1) cells. Furthermore, treatment with AZA not only promoted the demethylation of RUNX3 but also restored the mRNA and protein expression of RUNX3, and the reactivation of expression of the later exhibited its anti-tumor effects through regulation of the cycle progression in PCa cells. Moreover, DNMT3b could regulate the expression level of RUNX3 by altering the DNA methylation of the RUNX3 in PCa cells.

Conclusion

RUNX3 is hypermethylated in a panel of PCa cell lines; inhibition of DNA methylation of RUNX3 could restore its gene expression, which could promote its anticancer effect. Thus, RUNX3 may serve as a novel putative molecular target gene for PCa therapy.

Methylation Landscape of RUNX3 Promoter Region as a Predictive Marker for Th1/Th2 Imbalance in Bronchiolitis

Background

The methylation status of RUNX3 promoter region, its impact on RUNX3 gene expression, and Th1/Th2 imbalance are unknown in bronchiolitis. This study aimed to explore the predictors of bronchiolitis developing into asthma.

Material/Methods

The methylation status of RUNX3 promoter was assessed using Illumina HiSeq platform method. The relative RUNX3 mRNA levels in PBMCs were measured by qRT-PCR. Serum IL-4 and IFN-γ concentrations were measured by ELISA.

Results

A series of sites with significantly higher levels of methylation as compared to their corresponding controls were identified, including 24 sites in group Ba vs. group Cn, 13 sites in group Ba vs. group Ca, 7 sites in group Ba vs. group Bn, 16 sites in group Bn vs. group Cn, 11 sites in group Ca vs. group Cn, and 23 sites in group B vs. group C; P<0.05. The relative mRNA levels in group Ba were significantly lower than those in groups Cn, Ca, Bn; P<0.05. The serum IL-4 concentrations in group Ba were significantly higher than those in group Cn; P<0.05. The serum IFN-γ concentrations in group Ba were significantly lower than those in groups Cn, Ca, Bn; P<0.05. Correlation analysis showed that differentially methylated RUNX3 promoter region sites were significantly negatively correlated with levels of relative RUNX3 mRNA and IFN-γ, and were significantly positively correlated with IL-4 levels.

Conclusions

The methylation status of RUNX3 promoter region plays a role in Th1/Th2 imbalance by silencing RUNX3 gene expression, which can serve as predictive marker for the development of bronchiolitis into asthma.

RUNX transcription factors: orchestrators of development

RUNX transcription factors orchestrate many different aspects of biology, including basic cellular and developmental processes, stem cell biology and tumorigenesis. In this Primer, we introduce the molecular hallmarks of the three mammalian RUNX genes, RUNX1, RUNX2 and RUNX3, and discuss the regulation of their activities and their mechanisms of action. We then review their crucial roles in the specification and maintenance of a wide array of tissues during embryonic development and adult homeostasis.

RUNX1-dependent mechanisms in biological control and dysregulation in cancer

The RUNX1 transcription factor has recently been shown to be obligatory for normal development. RUNX1 controls the expression of genes essential for proper development in many cell lineages and tissues including blood, bone, cartilage, hair follicles, and mammary glands. Compromised RUNX1 regulation is associated with many cancers. In this review, we highlight evidence for RUNX1 control in both invertebrate and mammalian development and recent novel findings of perturbed RUNX1 control in breast cancer that has implications for other solid tumors. As RUNX1 is essential for definitive hematopoiesis, RUNX1 mutations in hematopoietic lineage cells have been implicated in the etiology of several leukemias. Studies of solid tumors have revealed a context-dependent function for RUNX1 either as an oncogene or a tumor suppressor. These RUNX1 functions have been reported for breast, prostate, lung, and skin cancers that are related to cancer subtypes and different stages of tumor development. Growing evidence suggests that RUNX1 suppresses aggressiveness in most breast cancer subtypes particularly in the early stage of tumorigenesis. Several studies have identified RUNX1 suppression of the breast cancer epithelial-to-mesenchymal transition. Most recently, RUNX1 repression of cancer stem cells and tumorsphere formation was reported for breast cancer. It is anticipated that these new discoveries of the context-dependent diversity of RUNX1 functions will lead to innovative therapeutic strategies for the intervention of cancer and other abnormalities of normal tissues.

DNA methylome of human neonatal umbilical cord: Enrichment of differentially methylated regions compared to umbilical cord blood DNA at transcription factor genes involved in body patterning and effects of maternal folate deficiency or children's sex

The DOHaD (developmental origins of health and disease) hypothesis claims that fetal malnutrition or exposure to environmental pollutants may affect their lifelong health. Epigenetic changes may play significant roles in DOHaD; however, access to human fetuses for research has ethical and technical hurdles. Umbilical cord blood (CB) has been commonly used as an epigenetic surrogate of fetuses, but it does not provide direct evidence of fetal exposure to pollutants. Here, we propose umbilical cord tissue (UC), which accumulates substances delivered to fetuses during gestation, as an alternative surrogate for epigenetic studies on fetuses. To explore the feasibility to examine UC epigenome by deep sequencing, we determined CpG methylation profiles of human postnatal UC by reduced representation bisulfite sequencing. Principal component analysis clearly separated the DNA methylomes of UC and CB pairs isolated from the same newborn (n = 10). Although all UC chromosomes were modestly hypomethylated compared to CB chromosomes, GO analysis revealed strong enrichment of differentially methylated regions (DMRs) at promoter-associated CpG islands in the HOX gene clusters and other genes encoding transcription factors involved in determination of the body pattern. DNA methylomes of UC autosomes were largely comparable between males and females. Deficiency of folate during pregnancy has been suggested to affect fetal DNA methylation to cause congenital anomalies. Whereas DNA methylome of UC was not significantly affected by early-gestational (12 weeks) low levels of maternal plasma folate (< 8 ng/ml, n = 10) compared to controls (>19 ng/mL, n = 10), two specific loci of LTR12C endogenous retroviruses in chromosome 12 were significantly hypermethylated in the low-folate group. Our study suggests that UC is useful as an alternative surrogate for studying environmental effects on DNA methylation in human fetuses, compensating CB by providing additional information about epigenetic regulation of genes involved in developmental body patterning and endogenous retroviruses.

RUNX family: Oncogenes or tumor suppressors (Review)

Runt-related transcription factor (RUNX) proteins belong to a transcription factors family known as master regulators of important embryonic developmental programs. In the last decade, the whole family has been implicated in the regulation of different oncogenic processes and signaling pathways associated with cancer. Furthermore, a suppressor tumor function has been also reported, suggesting the RUNX family serves key role in all different types of cancer. In this review, the known biological characteristics, specific regulatory abilities and experimental evidence of RUNX proteins will be analyzed to demonstrate their oncogenic potential and tumor suppressor abilities during oncogenic processes, suggesting their importance as biomarkers of cancer. Additionally, the importance of continuing with the molecular studies of RUNX proteins' and its dual functions in cancer will be underlined in order to apply it in the future development of specific diagnostic methods and therapies against different types of cancer.

Association between RUNX3 gene polymorphisms in severe preeclampsia and its clinical features

Preeclampsia is a complex genetic disorder and its pathogenesis remains to be investigated. Single nucleotide polymorphisms serve important roles in genetic predisposition. The present study aimed to explore the association between runt-related transcription factor 3 (RUNX3) gene polymorphisms in severe preeclampsia (SPE) and clinical features.A total of 417 participants were enrolled in the present study. The rs2236852, rs7528484 and rs760805 polymorphisms of the RUNX3 gene were tested using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Clinical information of patients and controls was collected. Relationship between clinical feature and different genotype was analyzed.Compared with rs2236852 GG genotype carriers, the odds ratios (OR) for the risk of SPE were 2.26 [95% confidence interval (CI), 1.24-4.12; P = .023] in AA genotype carriers. A significantly increased risk of SPE was associated with AG/AA genotypes compared with GG genotypes (OR, 1.74; 95% CI, 1.11-2.75; P = .015). AA homozygote carriers with SPE exhibited lower birth weight, shorter birth length and reduced incidence of hypoproteinemia compared with AG heterozygote carriers (P <.05). A significantly increased risk of SPE was determined to be associated with the rs7528484 CC genotype in codominant and recessive models (CC vs TT: OR, 3.70, 95% CI, 1.31-10.43, P = .01; CC vs TT/TC: OR, 3.98, 95% CI, 1.46-10.87, P = .003). Patients carrying C-allele (TC + CC) presented increased systolic pressure and an increased incidence of neonatal pneumonia compared with TT homozygote carriers (P <.05). Compared with rs760805 TT homozygote carriers, patients carrying AA homozygote exhibited significantly reduced 24 hours urinary protein levels, lower serum creatinine concentrations and a decreased incidence of neonatal asphyxia (P <.05).The present study suggested a genetic association between RUNX3 gene polymorphisms and SPE. The data provided a novel insight to guide future investigations.

The roles of RUNX3 in cervical cancer cells in vitro

RUNX3 serves an important role in development of various types of human cancer. The purpose of the present study was to investigate the potential biological function of RUNX3 in cervical cancer cells. In the present study, a RUNX3 overexpressed model was constructed in Hce1 cells by PCDNA3.1-RUNX3 transfection. Western blot analysis was used to measure RUNX3 expression in cervical cancer cells. Immunofluorescence analysis was performed to examine subcellular localization of RUNX3 in cervical cancer cells. Effects of RUNX3 expression on proliferation, migration and invasion of cervical cancer cells were detected by colony formation assay, wound healing assay and Transwell assay, respectively. Immunofluorescence confirmed the nuclear location of RUNX3 in cervical cancer cell. Result sindicated that upregulation of RUNX3 expression inhibited proliferation, migration and invasion of cervical cancer cells. However, knockdown of RUNX3 expression promoted the proliferation, migration and invasion of cervical cancer cells. Hence, RUNX3 may serve as a tumor suppressor gene in cervical cancer.

Expression levels of the runt-related transcription factor 1 and 3 genes in the development of acute myeloid leukemia

The aim of the present study was to evaluate the mRNA expression level of the runt-related transcription factor 1 (RUNX1) and runt-related transcription factor 3 (RUNX3) genes in patients with acute myeloid leukemia (AML). The etiology of AML is not yet fully known, but certain genetic factors may contribute to its manifestation. The RUNX1 and RUNX3 genes have been demonstrated to serve a role in the transcription process. The group investigated in the present study included 43 patients diagnosed with AML, and the relative RUNX1 and RUNX3 expression levels were determined using reverse transcription-quantitative polymerase chain reaction. The results indicated that RUNX1 and RUNX3 expression was associated with clinicopathological features, including sex and mortality risk. Expression levels of the RUNX1 gene were higher and more variable among females (P=0.044), and mortality was more frequent among patients with a higher RUNX3 expression level (P=0.036). The data obtained from the present study suggested that RUNX3 expression may have potential value as a prognostic factor; furthermore, sex is potentially a factor that may affect the difference in RUNX1 gene expression level among females and males. Further analyses in this field will aid in the identification and elucidation of the molecular basis of leukemia.

RUNX1: A Regulator of NF-kB Signaling in Pulmonary Diseases

Runt-related transcription factor 1 (RUNX1), a member of the RUNX family, is one of the key regulatory proteins in vertebrates. RUNX1 is involved in embryonic development, hematopoiesis, angiogenesis, tumorigenesis and immune response. In the past few decades, studies mainly focused on the effect of RUNX1 on acute leukemia and cancer. Only few studies about the function of RUNX1 in the pathological process of pulmonary diseases have been reported. Recent studies have demonstrated that RUNX1 is highly expressed in both mesenchymal and epithelial compartments of the developing and postnatal lung and that it plays a critical role in the lipopolysaccharide induced lung inflammation by regulating the NF-kB pathway. RUNX1 participates in the regulation of the NF-kB signaling pathway through interaction with IkB kinase complex in the cytoplasm or interaction with the NF-kB subunit P50. NF-kB is well-known signaling pathway necessary for inflammatory response in the lung. This review is to highlight the RUNX1 structure, isoforms and to present the mechanism that RUNX1 regulates NF-kB. This will illustrate the great potential role of RUNX1 in the inflammation signaling pathway in pulmonary diseases.

Runx2 mediated Induction of Novel Targets ST2 and Runx3 Leads to Cooperative Regulation of Hypertrophic Differentiation in ATDC5 Chondrocytes

Knowledge concerning expression and function of Suppression of Tumorigenicity 2 (ST2) in chondrocytes is at present, limited. Analysis of murine growth plates and ATDC5 chondrocytes indicated peak expression of the ST2 transmembrane receptor (ST2L) and soluble (sST2) isoforms during the hypertrophic differentiation concomitant with the expression of the hypertrophic markers Collagen X (Col X), Runx2 and MMP-13. Gain- and loss-of-function experiments in ATDC5 and primary human growth plate chondrocytes (PHCs), confirmed regulation of ST2 by the key transcription factor Runx2, indicating ST2 to be a novel Runx2 target. ST2 knock-out mice (ST2−/−) exhibited noticeable hypertrophic zone (HZ) reduction in murine growth plates, accompanied by lower expression of Col X and Osteocalcin (OSC) compared to wild-type (WT) mice. Likewise, ST2 knockdown resulted in decreased Col X expression and downregulation of OSC and Vascular Endothelial Growth Factor (VEGF) in ATDC5 cells. The ST2 suppression was also associated with upregulation of the proliferative stage markers Sox9 and Collagen II (Col II), indicating ST2 to be a new regulator of ATDC5 chondrocyte differentiation. Runx3 was, furthermore, identified as a novel Runx2 target in chondrocytes. This study suggests that Runx2 mediates ST2 and Runx3 induction to cooperatively regulate hypertrophic differentiation of ATDC5 chondrocytes.

Mislocalization of Runt-related transcription factor 3 results in airway inflammation and airway hyper-responsiveness in a murine asthma model

The Runt-related transcription factor (RUNX) gene family consists of three members, RUNX1, -2 and -3, which heterodimerize with a common protein, core-binding factor β, and contain the highly conserved Runt-homology domain. RUNX1 and -2 have essential roles in hematopoiesis and osteogenesis. Runx3 protein regulates cell lineage decisions in neurogenesis and thymopoiesis. The aim of the present study was to determine the expression features of the Runx3 protein in a murine asthma model. In vivo, Runx3 protein and mRNA were found to be almost equivalently expressed in the murine lung tissue of the control, ovalbumin (OVA) and genistein groups; however, the nuclear Runx3 protein was abated in lung tissue in OVA-immunized and challenged mice. Following treatment with genistein, which is a flavonoid previously demonstrated to decrease airway inflammation in asthma, the allergic airway inflammation and airway hyper-responsiveness were attenuated and the Runx3 protein tended to augment in the nucleus. These results were further determined in vitro. These results indicated that the mislocalization of Runx3 protein is a molecular mechanism of allergic inflammation and airway hyper-responsiveness in a murine asthma model.

Site-specific Hypermethylation of RUNX3 Predicts Poor Prognosis in Gastric Cancer

BACKGROUND AND AIMS

Methylation status of RUNX3 remains largely unknown in gastric cancer (GC). The aim of this study was to prognostically evaluate the methylation level of CpG sites within RUNX3 promoter region in GC.

METHODS

Using pyrosequencing, we quantitatively explored the methylation status of 8 CpG sites within RUNX3 promoter region for 76 gastric cancer and 24 normal gastric tissues. We then analyzed the association between methylation level of each CpG site and clinicopathological characteristics and outcomes in the cohort.

RESULTS

Methylation of RUNX3 promoter was significantly higher in GC than normal subjects. Overall methylation level was closely associated with tumor invasion and TNM stage. Positive associations were found between hypermethylation of the following concerned sites and variables: site -1392, -1397, -1403, -1415 and tumor invasion, as well as TNM stage; site -1392 and lymph node metastasis along with number of lymph node metastases; site -1415 and cancer recurrence; site -1403, -1415 and cancer-related deaths. In multivariate analysis, tumor invasion was correlated with sites -1392 and -1397. Lymph node metastasis was associated with site -1392. Most importantly, methylation of site -1415 was associated with poor survival by using Cox survival regression.

CONCLUSION

Analysis of RUNX3 gene promoter by quantitative pyrosequencing suggested methylation status of RUNX3 is different in normal and tumor tissues. RUNX3 methylation level is associated with GC, especially the methylation at site -1415 contributes to the poor prognosis in GC. Thus, RUNX3 methylation may serve as a valuable diagnostic and prognostic biomarker in GC.

An ensemble of regulatory elements controls Runx3 spatiotemporal expression in subsets of dorsal root ganglia proprioceptive neurons

Appel et al. defined the genomic transcription unit encompassing regulatory elements (REs) that mediate the tissue-specific expression of Runx3. Then, using transgenic mice expressing BAC reporters spanning the Runx3 locus, they discovered three REs that cross-talk with promoter-2 (P2) to drive TrkC neuron-specific Runx3 transcription.

The Runx3 transcription factor is essential for development and diversification of the dorsal root ganglia (DRGs) TrkC sensory neurons. In Runx3-deficient mice, developing TrkC neurons fail to extend central and peripheral afferents, leading to cell death and disruption of the stretch reflex circuit, resulting in severe limb ataxia. Despite its central role, the mechanisms underlying the spatiotemporal expression specificities of Runx3 in TrkC neurons were largely unknown. Here we first defined the genomic transcription unit encompassing regulatory elements (REs) that mediate the tissue-specific expression of Runx3. Using transgenic mice expressing BAC reporters spanning the Runx3 locus, we discovered three REs—dubbed R1, R2, and R3—that cross-talk with promoter-2 (P2) to drive TrkC neuron-specific Runx3 transcription. Deletion of single or multiple elements either in the BAC transgenics or by CRISPR/Cas9-mediated endogenous ablation established the REs’ ability to promote and/or repress Runx3 expression in developing sensory neurons. Our analysis reveals that an intricate combinatorial interplay among the three REs governs Runx3 expression in distinct subtypes of TrkC neurons while concomitantly extinguishing its expression in non-TrkC neurons. These findings provide insights into the mechanism regulating cell type-specific expression and subtype diversification of TrkC neurons in developing DRGs.

LRG1 promotes proliferation and inhibits apoptosis in colorectal cancer cells via RUNX1 activation

Leucine-rich-alpha-2-glycoprotein 1 (LRG1) has been shown to be involved in various human malignancies. Whether it plays a role in colorectal cancer (CRC) development remains unclear. Here, we investigated whether and through what mechanism LRG1 functions in human CRC cells. The plasma level of LRG1 was significantly increased in CRC patients, but it was remarkably decreased in patients with resected colorectal cancers. Meanwhile, both mRNA and protein levels of LRG1 were remarkable overexpressed in CRC tissues than normal tissues. The knockdown of LRG1 significantly inhibited cell proliferation, induced cell cycle arrest at the G0/G1 phase, and promoted apoptosis in SW480 and HCT116 cells in vitro. In addition, LRG1 silencing led to the downregulation of the levels of key cell cycle factors, such as cyclin D1, B, and E and anti-apoptotic B-cell lymphoma-2(Bcl-2). However, it up-regulated the expression of pro-apoptotic Bax and cleaved caspase-3. Furthermore, RUNX1 could be induced by LRG1 in a concentration-dependent manner, while the knockdown of RUNX1 blocked the promotion of the proliferation and inhibition of apoptosis induced by LRG1. Collectively, these findings indicate that LRG1 plays a crucial role in the proliferation and apoptosis of CRC by regulating RUNX1 expression. Thus, LRG1 may be a potential detection biomarker as well as a marker for monitoring recurrence and therapeutic target for CRC.

Core binding factor (CBF) is required for Epstein-Barr virus EBNA3 proteins to regulate target gene expression

ChIP-seq performed on lymphoblastoid cell lines (LCLs), expressing epitope-tagged EBNA3A, EBNA3B or EBNA3C from EBV-recombinants, revealed important principles of EBNA3 binding to chromatin. When combined with global chromatin looping data, EBNA3-bound loci were found to have a singular character, each directly associating with either EBNA3-repressed or EBNA3-activated genes, but not with both. EBNA3A and EBNA3C showed significant association with repressed and activated genes. Significant direct association for EBNA3B loci could only be shown with EBNA3B-repressed genes. A comparison of EBNA3 binding sites with known transcription factor binding sites in LCL GM12878 revealed substantial co-localization of EBNA3s with RUNX3-a protein induced by EBV during B cell transformation. The beta-subunit of core binding factor (CBFβ), that heterodimerizes with RUNX3, could co-immunoprecipitate robustly EBNA3B and EBNA3C, but only weakly EBNA3A. Depletion of either RUNX3 or CBFβ with lentivirus-delivered shRNA impaired epitope-tagged EBNA3B and EBNA3C binding at multiple regulated gene loci, indicating a requirement for CBF heterodimers in EBNA3 recruitment during target-gene regulation. ShRNA-mediated depletion of CBFβ in an EBNA3C-conditional LCL confirmed the role of CBF in the regulation of EBNA3C-induced and -repressed genes. These results reveal an important role for RUNX3/CBF during B cell transformation and EBV latency that was hitherto unexplored.

Runx transcription factors in the development and function of the definitive hematopoietic system

The Runx family of transcription factors (Runx1, Runx2, and Runx3) are highly conserved and encode proteins involved in a variety of cell lineages, including blood and blood-related cell lineages, during developmental and adult stages of life. They perform activation and repressive functions in the regulation of gene expression. The requirement for Runx1 in the normal hematopoietic development and its dysregulation through chromosomal translocations and loss-of-function mutations as found in acute myeloid leukemias highlight the importance of this transcription factor in the healthy blood system. Whereas another review will focus on the role of Runx factors in leukemias, this review will provide an overview of the normal regulation and function of Runx factors in hematopoiesis and focus particularly on the biological effects of Runx1 in the generation of hematopoietic stem cells. We will present the current knowledge of the structure and regulatory features directing lineage-specific expression of Runx genes, the models of embryonic and adult hematopoietic development that provide information on their function, and some of the mechanisms by which they affect hematopoietic function.

Precocious Phenotypic Transcription-Factor Expression During Early Development

A novel role for phenotypic transcription factors in very early differentiation was recently observed and merits further study to elucidate what role this precocious expression may have in development. The RUNX1 transcription factor exhibits selective and transient upregulation during early mesenchymal differentiation. In contrast to phenotype-associated transcriptional control of gene expression to establish and sustain hematopoietic/myeloid lineage identity, precocious expression of RUNX1 is functionally linked to control of an epithelial to mesenchymal transition that is obligatory for development. This early RUNX1 expression spike provides a paradigm for precocious expression of a phenotypic transcription factor that invites detailed mechanistic study to fully understand its biological importance. J. Cell. Biochem. 118: 953-958, 2017. © 2016 Wiley Periodicals, Inc.

Runx3 and Cell Fate Decisions in Pancreas Cancer

The RUNX family transcription factors are critical regulators of development and frequently dysregulated in cancer. RUNX3, the least well characterized of the three family members, has been variously described as a tumor promoter or suppressor, sometimes with conflicting results and opinions in the same cancer and likely reflecting a complex role in oncogenesis. We recently identified RUNX3 expression as a crucial determinant of the predilection for pancreatic ductal adenocarcinoma (PDA) cells to proliferate locally or promulgate throughout the body. High RUNX3 expression induces the production and secretion of soluble factors that support metastatic niche construction and stimulates PDA cells to migrate and invade, while simultaneously suppressing proliferation through increased expression of cell cycle regulators such as CDKN1A/p21 ^WAF1/CIP1 . RUNX3 expression and function are coordinated by numerous transcriptional and post-translational inputs, and interactions with diverse cofactors influence whether the resulting RUNX3 complexes enact tumor suppressive or tumor promoting programs. Understanding these exquisitely context-dependent tumor cell behaviors has the potential to inform clinical decision-making including the most appropriate timing and sequencing of local vs. systemic therapies.

Roles of RUNX in B Cell Immortalisation

RUNX1 and RUNX3 are the main RUNX genes expressed in B lymphocytes. Both are expressed throughout B-cell development and play key roles at certain key developmental transitions. The tumour-associated Epstein-Barr virus (EBV) has potent B-cell transforming ability and manipulates RUNX3 and RUNX1 transcription through novel mechanisms to control B cell growth. In contrast to resting mature B cells where RUNX1 expression is high, in EBV-infected cells RUNX1 levels are low and RUNX3 levels are high. Downregulation of RUNX1 in these cells results from cross-regulation by RUNX3 and serves to relieve RUNX1-mediated growth repression. RUNX3 is upregulated by the EBV transcription factor (TF) EBNA2 and represses RUNX1 transcription through RUNX sites in the RUNX1 P1 promoter. Recent analysis revealed that EBNA2 activates RUNX3 transcription through an 18 kb upstream super-enhancer in a manner dependent on the EBNA2 and Notch DNA-binding partner RBP-J. This super-enhancer also directs RUNX3 activation by two further RBP-J-associated EBV TFs, EBNA3B and 3C. Counter-intuitively, EBNA2 also hijacks RBP-J to target a super-enhancer region upstream of RUNX1 to maintain some RUNX1 expression in certain cell backgrounds, although the dual functioning EBNA3B and 3C proteins limit this activation. Interestingly, the B-cell genome binding sites of EBV TFs overlap extensively with RUNX3 binding sites and show enrichment for RUNX motifs. Therefore in addition to B-cell growth manipulation through the long-range control of RUNX transcription, EBV may also use RUNX proteins as co-factors to deregulate the transcription of many B cell genes during immortalisation.

Interferon-γ promotes double-stranded RNA-induced TLR3-dependent apoptosis via upregulation of transcription factor Runx3 in airway epithelial cells

Viral respiratory tract infections are the most common illness in humans. Infection of the respiratory viruses results in accumulation of viral replicative double-stranded RNA (dsRNA), which is one of the important components of infecting viruses for the induction of lung epithelial cell apoptosis and innate immune response, including the production of interferon (IFN). In the present study, we have investigated the regulation of dsRNA-induced airway epithelial cell apoptosis by IFN. We found that transcription factor Runx3 was strongly induced by type-II IFNγ, slightly by type-III IFNλ, but essentially not by type-I IFNα in airway epithelial cells. IFNγ-induced expression of Runx3 was predominantly mediated by JAK-STAT1 pathway and partially by NF-κB pathway. Interestingly, Runx3 can be synergistically induced by IFNγ with a synthetic analog of viral dsRNA polyinosinic-polycytidylic acid [poly(I:C)] or tumor necrosis factor-α (TNFα) through both JAK-STAT1 and NF-κB pathways. We further found that dsRNA poly(I:C)-induced apoptosis of airway epithelial cells was mediated by dsRNA receptor toll-like receptor 3 (TLR3) and was markedly augmented by IFNγ through the enhanced expression of TLR3 and subsequent activation of both extrinsic and intrinsic apoptosis pathways. Last, we demonstrated that upregulation of Runx3 by IFNγ promoted TLR3 expression, thus amplifying the dsRNA-induced apoptosis in airway epithelial cells. These novel findings indicate that IFNγ promotes dsRNA-induced TLR3-dependent apoptosis via upregulation of transcription factor Runx3 in airway epithelial cells. Findings from our study may provide new insights into the regulation of airway epithelial cell apoptosis by IFNγ during viral respiratory tract infection.

Inactivation of RUNX3/p46 Promotes Cutaneous T-Cell Lymphoma

The key role of RUNX3 in physiological T-cell differentiation has been extensively documented. However, information on its relevance for the development of human T-cell lymphomas or leukemias is scarce. Here, we show that alterations of RUNX3 by either heterozygous deletion or methylation of its distal promoter can be observed in the tumor cells of 15 of 21 (71%) patients suffering from Sézary syndrome, an aggressive variant of cutaneous T-cell lymphoma. As a consequence, mRNA levels of RUNX3/p46, the isoform controlled by the distal promoter, are significantly lower in Sézary syndrome tumor cells. Re-expression of RUNX3/p46 reduces cell viability and promotes apoptosis in a RUNX3/p46^low cell line of cutaneous T-cell lymphoma. Based on this, we present evidence that RUNX3 can act as a tumor suppressor in a human T-cell malignancy and suggest that this effect is predominantly mediated through transcripts from its distal promoter, in particular RUNX3/p46.

Aurora kinase-induced phosphorylation excludes transcription factor RUNX from the chromatin to facilitate proper mitotic progression

The Runt-related transcription factors (RUNX) are master regulators of development and major players in tumorigenesis. Interestingly, unlike most transcription factors, RUNX proteins are detected on the mitotic chromatin and apparatus, suggesting that they are functionally active in mitosis. Here, we identify key sites of RUNX phosphorylation in mitosis. We show that the phosphorylation of threonine 173 (T173) residue within the Runt domain of RUNX3 disrupts RUNX DNA binding activity during mitotic entry to facilitate the recruitment of RUNX proteins to mitotic structures. Moreover, knockdown of RUNX3 delays mitotic entry. RUNX3 phosphorylation is therefore a regulatory mechanism for mitotic entry. Cancer-associated mutations of RUNX3 T173 and its equivalent in RUNX1 further corroborate the role of RUNX phosphorylation in regulating proper mitotic progression and genomic integrity.

Distinguishing Lung Adenocarcinoma from Lung Squamous Cell Carcinoma by Two Hypomethylated and Three Hypermethylated Genes: A Meta-Analysis

Significant differences in the aberrant methylation of genes exist among various histological types of non-small cell lung cancer (NSCLC), which includes adenocarcinoma (AC) and squamous cell carcinoma (SCC). Different chemotherapeutic regimens should be administered to the two NSCLC subtypes due to their unique genetic and epigenetic profiles. The purpose of this meta-analysis was to generate a list of differentially methylated genes between AC and SCC. Our meta-analysis encompassed 151 studies on 108 genes among 12946 AC and 10243 SCC patients. Our results showed two hypomethylated genes (CDKN2A and MGMT) and three hypermethylated genes (CDH13, RUNX3 and APC) in ACs compared with SCCs. In addition, our results showed that the pooled specificity and sensitivity values of CDH13 and APC were higher than those of CDKN2A, MGMT and RUNX3. Our findings might provide an alternative method to distinguish between the two NSCLC subtypes.

Transcription Factor Runx3 Is Induced by Influenza A Virus and Double-Strand RNA and Mediates Airway Epithelial Cell Apoptosis

Influenza A virus (IAV) targets airway epithelial cells and exploits the host cell machinery to replicate, causing respiratory illness in annual epidemics and pandemics of variable severity. The high rate of antigenic drift (viral mutation) and the putative antigenic shift (reassortant strains) have raised the need to find the host cell inducible factors modulating IAV replication and its pathogenesis to develop more effective antiviral treatment. In this study, we found for the first time that transcription factor Runx3, a developmental regulator and tumor suppressor, was induced by IAV H1N1 and H3N2, viral RNA, a synthetic analog of viral double-stranded RNA (dsRNA) polyinosinic-polycytidylic acid, and type-II interferon-γ (IFNγ) in human airway epithelial cells. Whereas Runx3 was essentially not induced by type-I IFNα and type-III IFNλ, we show that Runx3 induction by IAV infection and viral RNA is mediated through the innate immune receptor MDA5 and the IκB kinase-β−NF-κB pathway. Moreover, we provide substantial evidence indicating that Runx3 plays a crucial role in airway epithelial cell apoptosis induced by IAV infection and dsRNA through the activation of extrinsic and intrinsic apoptosis pathways. Thus, we have identified Runx3 as an inducible and important transcription factor modulating IAV-induced host epithelial cell apoptosis.

The genetic association of RUNX3 with ankylosing spondylitis can be explained by allele-specific effects on IRF4 recruitment that alter gene expression

Objectives

To identify the functional basis for the genetic association of single nucleotide polymorphisms (SNP), upstream of the RUNX3 promoter, with ankylosing spondylitis (AS).

Methods

We performed conditional analysis of genetic association data and used ENCODE data on chromatin remodelling and transcription factor (TF) binding sites to identify the primary AS-associated regulatory SNP in the RUNX3 region. The functional effects of this SNP were tested in luciferase reporter assays. Its effects on TF binding were investigated by electrophoretic mobility gel shift assays and chromatin immunoprecipitation. RUNX3 mRNA levels were compared in primary CD8+ T cells of AS risk and protective genotypes by real-time PCR.

Results

The association of the RUNX3 SNP rs4648889 with AS (p<7.6×10⁻¹⁴) was robust to conditioning on all other SNPs in this region. We identified a 2 kb putative regulatory element, upstream of RUNX3, containing rs4648889. In reporter gene constructs, the protective rs4648889 ‘G’ allele increased luciferase activity ninefold but significantly less activity (4.3-fold) was seen with the AS risk ‘A’ allele (p≤0.01). The binding of Jurkat or CD8+ T-cell nuclear extracts to the risk allele was decreased and IRF4 recruitment was reduced. The AS-risk allele also affected H3K4Me1 histone methylation and associated with an allele-specific reduction in RUNX3 mRNA (p<0.05).

Conclusion

We identified a regulatory region upstream of RUNX3 that is modulated by rs4648889. The risk allele decreases TF binding (including IRF4) and reduces reporter activity and RUNX3 expression. These findings may have important implications for understanding the role of T cells and other immune cells in AS.

Loss of osteoblast Runx3 produces severe congenital osteopenia

Congenital osteopenia is a bone demineralization condition that is associated with elevated fracture risk in human infants. Here we show that Runx3, like Runx2, is expressed in precommitted embryonic osteoblasts and that Runx3-deficient mice develop severe congenital osteopenia. Runx3-deficient osteoblast-specific (Runx3(fl/fl)/Col1α1-cre), but not chondrocyte-specific (Runx3(fl/fl)/Col1α2-cre), mice are osteopenic. This demonstrates that an osteoblastic cell-autonomous function of Runx3 is required for proper osteogenesis. Bone histomorphometry revealed that decreased osteoblast numbers and reduced mineral deposition capacity in Runx3-deficient mice cause this bone formation deficiency. Neonatal bone and cultured primary osteoblast analyses revealed a Runx3-deficiency-associated decrease in the number of active osteoblasts resulting from diminished proliferation and not from enhanced osteoblast apoptosis. These findings are supported by Runx3-null culture transcriptome analyses showing significant decreases in the levels of osteoblastic markers and increases in the levels of Notch signaling components. Thus, while Runx2 is mandatory for the osteoblastic lineage commitment, Runx3 is nonredundantly required for the proliferation of these precommitted cells, to generate adequate numbers of active osteoblasts. Human RUNX3 resides on chromosome 1p36, a region that is associated with osteoporosis. Therefore, RUNX3 might also be involved in human bone mineralization.

The RUNX family: developmental regulators in cancer

RUNX proteins belong to a family of metazoan transcription factors that serve as master regulators of development. They are frequently deregulated in human cancers, indicating a prominent and, at times, paradoxical role in cancer pathogenesis. The contextual cues that direct RUNX function represent a fast-growing field in cancer research and could provide insights that are applicable to early cancer detection and treatment. This Review describes how RUNX proteins communicate with key signalling pathways during the multistep progression to malignancy; in particular, we highlight the emerging partnership of RUNX with p53 in cancer suppression.

Overexpression of RUNX3 inhibits malignant behaviour of Eca109 cells in vitro and vivo

Runt-related transcription factor 3 (RUNX3) is a tumor suppressor gene whose reduced expression may play an important role in the development and progression of esophageal squamous cell cancer (ESCC). The aim of this study was to investigate the clinical relevance of RUNX3 in ESCC patients and effects of overexpression on biological behaviour of Eca109 cells in vitro and in vivo. Immunohistochemistry was performed to detect the clinical relevance of RUNX3 and lymph node metastasis in 80 ESCC tissues and 40 non-cancerous tissues using the SP method. RT-PCR and Western blotting were applied to assess the RUNX3 level and verify the Eca109 cell line with stable overexpression. Localization of RUNX3 proteins was performed by cell immunofluorescence. CCK-8 and Scrape motility assays were used to determine proliferation and migration and the TUNEL assay to analyze cell apoptosis. Invasive potential was assessed in cell transwell invasion experiments. In nude mice, tumorigenesis in vivo was determined. Results showed decreased expression of RUNX3 in esophageal tissue to be significantly related to lymph node metastasis (LNM) (P<0.01). In addition, construction of a recombinant lentiviral vector and transfection into the human ESCC cell line Eca109 demonstrated that overexpression could inhibit cell proliferation, migration and invasion, and induce apoptosis. The in vivo experiments in mice showed tumorigenicity and invasiveness to be significantly reduced. Taken together, our studies indicate that underexpression of RUNX3 in human ESCC tissue is significantly correlated with progression. Restoration of RUNX3 expression significantly inhibits ESCC cells proliferation, migration, invasion and tumorigenesis.

Downregulation of Runx3 is closely related to the decreased Th1-associated factors in patients with gastric carcinoma

Runt-related transcription factor 3 (Runx3) is a tumor-suppressor gene and plays an important role in immune regulation, whose reduced expression may play an important role in the development and progression of gastric carcinoma. The aim of this study was to investigate the role of Runx3 on the levels of transcription factors in patients with gastric carcinoma and analyze the relationship between the expression of Runx3 and Th1-type cytokines in peripheral blood mononuclear cells (PBMCs). Our results showed that the expression levels of Runx3, T-bet, and IFN-γ in patients with gastric carcinoma were obviously lower than those in control groups, and there was a positive correlation between the expression of Runx3 and T-bet or IFN-γ in patients (p < 0.01). In order to further confirm this result, the Runx3 gene was constructed into pIRES2-eGFP and the recombined plasmid was transfected into SGC-7901 cells with liposome in vitro, the results obtained from the reverse transcription PCR indicated that the mRNA of Runx3, T-bet, or IFN-γ was significantly upregulated individually in Runx3 gene-transfected SGC-7901 cells. It suggested that the Runx3 and Th1-associated factors including T-bet and IFN-γ synchronization declines in gastric carcinoma may contribute to the development of cancer.

Alteration of runt-related transcription factor 3 gene expression and biologic behavior of esophageal carcinoma TE-1 cells after 5-azacytidine intervention

5-Azacytidine (5-azaC) was originally identified as an anticancer drug (NSC102876) which can cause hypomethylation of tumor suppressor genes. To assess its effects on runt-related transcription factor 3 (RUNX3), expression levels and the promoter methylation status of the RUNX3 gene were assessed. We also investigated alteration of biologic behavior of esophageal carcinoma TE-1 cells. MTT assays showed 5-azaC inhibited the proliferation of TE-1 cells in a time and dose-dependent way. Although other genes could be demethylated after 5-azaC intervention, we focused on RUNX3 gene in this study. The expression level of RUNX3 mRNA increased significantly in TE-1 cells after treatment with 5-azaC at hypotoxic levels. RT-PCR showed 5-azaC at 50 μM had the highest RUNX3-induction activity. Methylation-specific PCR indicated that 5-azaC induced RUNX3 expression through demethylation. Migration and invasion of TE-1 cells were inhibited by 5-azaC, along with growth of Eca109 xenografts in nude mice. In conclusion, we demonstrate that the RUNX3 gene can be reactivated by the demethylation reagent 5-azaC, which inhibits the proliferation, migration and invasion of esophageal carcinoma TE-1 cells.

Comparative analysis of each prescription of Jiedu Huayu Jianpi Fang for multiple gene demethylation and expression in mucosal dysplasia in rats

AIM: To evaluate the contribution of each prescription of Jiedu Huayu Jianpi Fang to the therapeutic effects on gastric mucosal dysplasia from the perspective of induced gene expression.

METHODS: We divided gastric mucosal dysplasia rats into a model control (MG) group, a Western medicine (retinoic acid) treatment (PCG) group, a combined prescription (Jiedu Huayu Jianpi) treatment (A) group, and Jiedu (B), Huayu (C), Yiqi (D), Yangying (E) and Liqi (F) single prescription treatment groups. Normal rats were used as controls (CG). Methylation specific PCR technique was used to detect the methylation status of p16, PETN, Thbs1, E-Cadherin, and Runx3 genes in gastric mucosal cells of rats. Real-time PCR and immunohistochemistry were used to detect the mRNA and protein expression of each genes.

RESULTS: All of the Jiedu Huayu Jianpi treatment groups showed a certain degree of demethylation of p16, PETN, Thbs1, E-Cadherin, and Runx3 gene. Compared with group CG, the mRNA expression of p16 (P < 0.01), PETN, E-Cadherin and Thbs1 in group A, Thbs1 in group B, p16, PETN and Thbs1 in group C, Thbs1 in group E, p16 and Thbs1 in group F increased significantly (P < 0.05 for all); and the protein expression of p16, PTEN, E-cad, RUNX3, and THBS1 in group A, p16 in group B, p16 and THBS1 in group C, p16, PTEN, E-cad and THBS1 in group D, p16, E-cad, RUNX3 and THBS1 in group E, p16, PTEN, E-cad, RUNX3 and THBS1 in group F increased significantly (P < 0.05 for all). The effect of Jiedu Huayu Jianpi Fang on gastric mucosal dysplasia was the most prominent, followed by Liqi, Yangyin, Huayu, Yiqi and Jiedu single prescriptions.

CONCLUSION: The effect of Jiedu Huayu Jianpi Fang on gastric mucosal dysplasia is much better than those of each single prescription. Gastric mucosal dysplasia should be treated mainly by means of Liqi and Yangyin.