Hematopoietic Transcription Factor RUNX1 is Essential for Promoting Macrophage-Myofibroblast Transition in Non-Small-Cell Lung Carcinoma

Macrophage-myofibroblast transition (MMT) is a newly discovered pathway for mass production of pro-tumoral cancer-associated fibroblasts (CAFs) in non-small cell lung carcinoma (NSCLC) in a TGF-β1/Smad3 dependent manner. Better understanding its regulatory signaling in tumor microenvironment (TME) may identify druggable target for the development of precision medicine. Here, by dissecting the transcriptome dynamics of tumor-associated macrophage at single-cell resolution, a crucial role of a hematopoietic transcription factor Runx1 in MMT formation is revealed. Surprisingly, integrative bioinformatic analysis uncovers Runx1 as a key regulator in the downstream of MMT-specific TGF-β1/Smad3 signaling. Stromal Runx1 level positively correlates with the MMT-derived CAF abundance and mortality in NSCLC patients. Mechanistically, macrophage-specific Runx1 promotes the transcription of genes related to CAF signatures in MMT cells at genomic level. Importantly, macrophage-specific genetic deletion and systemic pharmacological inhibition of TGF-β1/Smad3/Runx1 signaling effectively prevent MMT-driven CAF and tumor formation in vitro and in vivo, representing a potential therapeutic target for clinical NSCLC.

Runx1 Deficiency Promotes M2 Macrophage Polarization Through Enhancing STAT6 Phosphorylation

Our previous study had demonstrated that Runx1 promoted LPS-induced macrophage inflammatory response, however, the role of Runx1 in M2 macrophage polarization still remains largely unknown. This study was conducted to investigate the role of Runx1 in IL-4/IL-13-induced M2 macrophage polarization and its potential regulatory mechanism. We found that exposure of macrophages to IL-4/IL-13 induced a remarkable increasement in Runx1 expression level. Specifically, we established genetically modified mice lacking Runx1 in myeloid cells, including macrophages. RNA-Seq was performed to identify differentially expressed genes (DEGs) between Runx1 knockout and WT control bone marrow-derived macrophages (BMDMs). We identified 686 DEGs, including many genes which were highly expressed in M2 macrophage. In addition, bioinformatics analysis indicated that these DEGs were significantly enriched in extracellular matrix-related processes. Moreover, RT-qPCR analysis showed that there was an obvious upregulation in the relative expression levels of M2 marker genes, including Arg1, Ym1, Fizz1, CD71, Mmp9, and Tgm2, in Runx1 knockout macrophages, as compared to WT controls. Consistently, similar results were obtained in the protein and enzymatic activity levels of Arg1. Finally, we found that the STAT6 phosphorylation level was significantly enhanced in Runx1 knockout macrophages, and the STAT6 inhibitor AS1517499 partly reduced the upregulated effect of Runx1 deficiency on the M2 macrophage polarization. Taken together, Runx1 deficiency facilitates IL-4/IL-13-induced M2 macrophage polarization through enhancing STAT6 phosphorylation.

Kaempferol regulates the thermogenic function of adipocytes in high-fat-diet-induced obesity via the CDK6/RUNX1/UCP1 signaling pathway

Activation of adipose tissue thermogenesis is a promising strategy in the treatment of obesity and obesity-related metabolic disorders. Kaempferol (KPF) is a predominant dietary flavonoid with multiple pharmacological properties, such as anti-inflammatory and antioxidant activities. In this study, we sought to characterize the role of KPF in adipocyte thermogenesis. We demonstrated that KPF-treated mice were protected from diet-induced obesity, glucose tolerance, and insulin resistance, accompanied by markedly increased energy expenditure, ex vivo oxygen consumption of white fat, and increased expression of proteins related to adaptive thermogenesis. KPF-promoted beige cell formation is a cell-autonomous effect, since the overexpression of cyclin-dependent kinase 6 (CDK6) in preadipocytes partially reversed browning phenotypes observed in KPF-treated cells. Overall, these data implicate that KPF is involved in promoting beige cell formation by suppressing CDK6 protein expression. This study provides evidence that KPF is a promising natural product for obesity treatment by boosting energy expenditure.

Systemic deuteration of SCID mice using the water-isotopologue deuterium oxide (D2 O) inhibits tumor growth in an orthotopic bioluminescent model of human pancreatic ductal adenocarcinoma

Since its initial discovery as a natural isotopologue of dihydrogen oxide (1 H2 O), extensive research has focused on the biophysical, biochemical, and pharmacological effects of deuterated water (2 H2 O [D2 O, also referred to as "heavy water"]). Using a panel of cultured human pancreatic ductal adenocarcinoma (PDAC) cells we have profiled (i) D2 O-induced phenotypic antiproliferative and apoptogenic effects, (ii) redox- and proteotoxicity-directed stress response gene expression, and (iii) phosphoprotein-signaling related to endoplasmic reticulum (ER) and MAP-kinase stress response pathways. Differential array analysis revealed early modulation of stress response gene expression in both BxPC-3 and PANC-1 PDAC cells elicited by D2 O (90%; ≤6 h; upregulated: HMOX1, NOS2, CYP2E1, CRYAB, DDIT3, NFKBIA, PTGS1, SOD2, PTGS2; downregulated: RUNX1, MYC, HSPA8, HSPA1A) confirmed by independent RT-qPCR analysis. Immunoblot-analysis revealed rapid (≤6 h) onset of D2 O-induced MAP-kinase signaling (p-JNK, p-p38) together with ER stress response upregulation (p-eIF2α, ATF4, XBP1s, DDIT3/CHOP). Next, we tested the chemotherapeutic efficacy of D2 O-based drinking water supplementation in an orthotopic PDAC model employing firefly luciferase-expressing BxPC-3-FLuc cells in SCID mice. First, feasibility and time course of systemic deuteration (30% D2 O in drinking water; 21 days) were established using time-resolved whole-body proton magnetic resonance imaging and isotope-ratio mass spectrometry-based plasma (D/H)-analysis. D2 O-supplementation suppressed tumor growth by almost 80% with downregulated expression of PCNA, MYC, RUNX1, and HSP70 while increasing tumor levels of DDIT3/CHOP, HO-1, and p-eIF2α. Taken together, these data demonstrate for the first time that pharmacological induction of systemic deuteration significantly reduces orthotopic tumor burden in a murine PDAC xenograft model.

RUNX1 Ameliorates Rheumatoid Arthritis Progression through Epigenetic Inhibition of LRRC15

Leucine-rich repeat containing 15 (LRRC15) has been identified as a contributing factor for cartilage damage in osteoarthritis; however, its involvement in rheumatoid arthritis (RA) and the underlying mechanisms have not been well characterized. The purpose of this study was to explore the function of LRRC15 in RA-associated fibroblast-like synoviocytes (RA-FLS) and in mice with collagen-induced arthritis (CIA) and to dissect the epigenetic mechanisms involved. LRRC15 was overexpressed in the synovial tissues of patients with RA, and LRRC15 overexpression was associated with increased proliferative, migratory, invasive, and angiogenic capacities of RA-FLS and accelerated release of pro-inflammatory cytokines. LRRC15 knockdown significantly inhibited synovial proliferation and reduced bone invasion and destruction in CIA mice. Runt-related transcription factor 1 (RUNX1) transcriptionally represses LRRC15 by binding to core-binding factor subunit beta (CBF-β). Overexpression of RUNX1 significantly inhibited the invasive phenotype of RA-FLS and suppressed the expression of proinflammatory cytokines. Conversely, the effects of RUNX1 were significantly reversed after overexpression of LRRC15 or inhibition of RUNX1-CBF-β interactions. Therefore, we demonstrated that RUNX1-mediated transcriptional repression of LRRC15 inhibited the development of RA, which may have therapeutic effects for RA patients.

RUNX Binding Sites Are Enriched in Herpesvirus Genomes, and RUNX1 Overexpression Leads to Herpes Simplex Virus 1 Suppression

Herpes simplex virus 1 (HSV-1) and HSV-2 can efficiently establish lifelong, transcriptionally silent latency states in sensory neurons to escape host detection. While host factors have previously been associated with long-range insulators in the viral genome, it is still unknown whether host transcription factors can repress viral genes more proximately to promote latency in dorsal root ganglion (DRG) neurons. Here, we assessed whether RUNX (runt-related transcription factor) transcription factors, which are critical in the development of sensory neurons, could be binding HSV-1 genome directly to suppress viral gene expression and lytic infection. Using previously published transcriptome sequencing data, we confirmed that mouse DRG neurons highly express Runx1 mRNA. Through computational analysis of HSV-1 and HSV-2 genomes, we observed that putative RUNX consensus binding sites (CBSs) were more enriched and more closely located to viral gene transcription start sites than would be expected by chance. We further found that RUNX CBSs were significantly more enriched among genomes of herpesviruses compared to those of nonherpesviruses. Utilizing an in vitro model of HSV-1 infection, we found that overexpressed RUNX1 could bind putative binding sites in the HSV-1 genome, repress numerous viral genes spanning all three kinetic classes, and suppress productive infection. In contrast, knockdown of RUNX1 in neuroblastoma cells induced viral gene expression and increased HSV-1 infection in vitro In sum, these data support a novel role for RUNX1 in directly binding herpesvirus genome, silencing the transcription of numerous viral genes, and ultimately limiting overall infection.IMPORTANCE Infecting 90% of the global population, HSV-1 and HSV-2 represent some of the most prevalent viruses in the world. Much of their success can be attributed to their ability to establish lifelong latent infections in the dorsal root ganglia (DRG). It is still largely unknown, however, how host transcription factors are involved in establishing this latency. Here, we report that RUNX1, expressed highly in DRG, binds HSV-1 genome, represses transcription of numerous viral genes, and suppresses productive in vitro infection. Our computational work further suggests this strategy may be used by other herpesviruses to reinforce latency in a cell-specific manner.

RUNX1 Dosage in Development and Cancer

The transcription factor RUNX1 first came to prominence due to its involvement in the t(8;21) translocation in acute myeloid leukemia (AML). Since this discovery, RUNX1 has been shown to play important roles not only in leukemia but also in the ontogeny of the normal hematopoietic system. Although it is currently still challenging to fully assess the different parameters regulating RUNX1 dosage, it has become clear that the dose of RUNX1 can greatly affect both leukemia and normal hematopoietic development. It is also becoming evident that varying levels of RUNX1 expression can be used as markers of tumor progression not only in the hematopoietic system, but also in non-hematopoietic cancers. Here, we provide an overview of the current knowledge of the effects of RUNX1 dosage in normal development of both hematopoietic and epithelial tissues and their associated cancers.

AML1/Runx1 rescues Notch1-null mutation-induced deficiency of para-aortic splanchnopleural hematopoiesis

The Notch1-RBP-Jkappa and the transcription factor Runx1 pathways have been independently shown to be indispensable for the establishment of definitive hematopoiesis. Importantly, expression of Runx1 is down-regulated in the para-aortic splanchnopleural (P-Sp) region of Notch1- and Rbpsuh-null mice. Here we demonstrate that Notch1 up-regulates Runx1 expression and that the defective hematopoietic potential of Notch1-null P-Sp cells is successfully rescued in the OP9 culture system by retroviral transfer of Runx1. We also show that Hes1, a known effector of Notch signaling, potentiates Runx1-mediated transactivation. Together with the recent findings in zebrafish, Runx1 is postulated to be a cardinal down-stream mediator of Notch signaling in hematopoietic development throughout vertebrates. Our findings also suggest that Notch signaling may modulate both expression and transcriptional activity of Runx1.

The Vitamin D Receptor, Runx2, and the Notch Signaling Pathway Cooperate in the Transcriptional Regulation of Osteopontin

Osteopontin (OPN), a glycosylated phosphoprotein that binds calcium, is present in bone extracellular matrix and has been reported to modulate both mineralization and bone resorption. Targeted disruption in mice of the vitamin D receptor (VDR) or Runx2 results in marked inhibition of OPN expression in osteoblasts. In this study, we addressed possible cross-talk between VDR and Runx2 in regulating OPN transcription. 1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) or Runx2 stimulated OPN transcription (mouse OPN promoter -777/+79) 2-3-fold. However, coexpression of Runx2 and VDR in COS-7 cells and treatment with 1,25(OH)(2)D(3) resulted in an 8-fold induction of OPN transcription, indicating for the first time functional cooperation between Runx2 and VDR in the regulation of OPN transcription. In ROS 17/2.8 and MC3T3-E1 cells that contain endogenous Runx2, AML-1/ETO, which acts as a repressor of Runx2, significantly inhibited 1,25(OH)(2)D(3) induction of OPN transcription, OPN mRNA, and protein expression. Both a Runx2 site (-136/-130) and the vitamin D response element (-757/-743) in the OPN promoter are needed for cooperative activation. Chromatin immunoprecipitation analyses showed that 1,25(OH)(2)D(3) can enhance VDR and Runx2 recruitment on the OPN promoter, further indicating cooperation between these two factors in the regulation of OPN. In osteoblastic cells, Hes-1, a downstream factor of the Notch signaling pathway, was found to enhance basal and 1,25(OH)(2)D(3)-induced OPN transcription. This enhancement was inhibited by AML-1/ETO, an inhibitor of Runx2. Immunoprecipitation assays indicated that Hes-1 and Runx2 interact and that 1,25(OH)(2)D(3) can enhance this interaction. Taken together, these findings define novel mechanisms involving the intersection of three pathways, Runx2, 1,25(OH)(2)D(3), and Notch signaling, that play a major role in the regulation of OPN in osteoblastic cells and therefore in the process of bone remodeling.