Interaction and functional cooperation of PEBP2/CBF with Smads. Synergistic induction of the immunoglobulin germline Calpha promoter

Inhibition of UV-induced matrix metabolism by a myristoyl tetrapeptide

Regulation of extracellular matrix (ECM) composition is important in tissue homeostasis and function. We screened small peptides for their ability to inhibit ultraviolet (UV)-induced cell metabolism in epidermal fibroblasts. We found that UV irradiation increased matrix metalloproteinase (MMP) expression and inflammatory gene expression in human Hs68 fibroblast cells. We also demonstrated that a myristoyl tetrapeptide with the amino acid sequence Gly-Leu-Phe-Trp (mGLFW) suppressed the UV-induced expression of MMPs and inflammatory genes. Moreover, mGLFW stimulated the expression of ECM proteins in Hs68 fibroblasts. In order to provide the mechanism of action for mGLFW, we investigated UV-induced signaling changes in the presence of mGLFW using a cDNA microarray. UV exposure increased the expression of MMP genes, such as MMP1, MMP3, and MMP14, and inflammation-related genes, including interleukin 1 receptor and peroxisome proliferator-activated receptor gamma (PPARγ). Treatment with mGLFW abrogated the UV-induced expression of MMP-related genes and inflammatory genes. In addition, mGLFW increased the expression of collagen genes, including COL1A1, COL1A2, and COL5A1. We examined whether the activation of AP-1, a UV-activated transcription factor, is suppressed by mGLFW. The results demonstrated that AP-1 expression increased upon UV exposure and that this expression was inhibited by mGLFW. In conclusion, our results demonstrate that mGLFW reversed the effects of UV exposure by enhancing the expression of collagen proteins and suppressing the expression of MMPs, which degrade the ECM.

The RUNX complex: reaching beyond haematopoiesis into immunity

Among their diverse roles as transcriptional regulators during development and cell fate specification, the RUNX transcription factors are best known for the parts they play in haematopoiesis. RUNX proteins are expressed throughout all haematopoietic lineages, being necessary for the emergence of the first haematopoietic stem cells to their terminal differentiation. Although much progress has been made since their discoveries almost two decades ago, current appreciation of RUNX in haematopoiesis is largely grounded in their lineage-specifying roles. In contrast, the importance of RUNX to immunity has been mostly obscured for historic, technical and conceptual reasons. However, this paradigm is likely to shift over time, as a primary purpose of haematopoiesis is to resource the immune system. Furthermore, recent evidence suggests a role for RUNX in the innate immunity of non-haematopoietic cells. This review takes a haematopoiesis-centric approach to collate what is known of RUNX's contribution to the overall mammalian immune system and discuss their growing prominence in areas such as autoimmunity, inflammatory diseases and mucosal immunity.

Lactoferrin causes IgA and IgG2b isotype switching through betaglycan binding and activation of canonical TGF-β signaling

Lactoferrin (LF), a pleiotropic iron-binding glycoprotein, is known to modulate the humoral immune response. However, its exact role in Ig synthesis has yet to be elucidated. In this study, we investigated the effect of LF on Ig production by mouse B cells and its underlying mechanisms. LF, like transforming growth factor (TGF)-β1, stimulated B cells to produce IgA and IgG2b, while downregulating other isotypes. Using limiting dilution analysis, LF was shown to increase the frequency of IgA-secreting B-cell clones. This was paralleled by an increase in Ig germ-line α (GLα) transcripts, indicating that LF plays a role as an IgA switch factor. Interestingly, LF directly interacted with betaglycan (TGF-β receptor III, TβRIII) and in turn induced phosphorylation of TβRI and Smad3 through formation of the TβRIII/TβRII/TβRI complex, leading to IgA isotype switching. Peroral administration of LF increased intestinal/serum IgA production as well as number of IgA plasma cells in lamina propria. Finally, we found that LF has an adjuvant activity when nontoxigenic Salmonella typhimurium was inoculated perorally, conferring protection against intragastrical infection of toxigenic S. typhimurium. These results suggest that LF has an important effect on the mucosal/systemic IgA response and can contribute to protection against intestinal pathogens.

Role of (-)-epigallocatechin-3-gallate in the osteogenic differentiation of human bone marrow mesenchymal stem cells: An enhancer or an inducer?

Epidemiological investigations have revealed that the consumption of green tea, which is a rich source of (-)-epigallocatechin-3-gallate (EGCG), is associated with a reduced risk of osteoporosis. A number of in vitro and in vivo studies have also demonstrated that EGCG exerts a significant positive effect on osteogenesis; however, the single effect of EGCG on osteogenic differentiation has been seldom studied. EGCG was hypothesized to function as an enhancer or an inducer. In the present study, the effect of EGCG on the osteogenic differentiation of primary human bone marrow mesenchymal stem cells (hBMSCs), without other additives, was investigated. Three groups of stem cells were analyzed, which included a negative control group (hBMSCs cultured with culture medium only), an experimental group (cells treated with culture medium containing 2.5, 5 and 10 µM EGCG), and a positive control group (cells cultured with osteogenesis-induced culture medium). After 3, 7, 14 and 21 days, cell proliferation, alkaline phosphatase (ALP) activity and the expression of associated osteogenic genes were analyzed. The results revealed that ALP activity and the expression of associated osteogenic genes, with the exception of bone morphogenetic protein 2 (BMP2), were not affected by EGCG treatment alone. These results indicated that EGCG itself had little effect on the osteogenic differentiation of MSCs; however, EGCG was able to enhance osteogenesis in the presence of osteoinductive agents through the upregulation of BMP2 expression. Additionally, EGCG was shown to promote cell growth, demonstrating its safety as a therapeutic agent. Therefore, the present study indicated that treatment with EGCG was dependent on other osteogenic inducers.

High-magnitude mechanical strain inhibits the differentiation of bone-forming rat calvarial progenitor cells

PURPOSE

Orthodontic tooth movement occurs during the bone remodeling induced by therapeutic mechanical strain. It is important to investigate the relation between the strength of mechanical stress and bone formation activity. The aim of this study was to determine the effect of high-magnitude mechanical strain on bone formation in detail.

MATERIALS AND METHODS

Osteoblast-like cells isolated from fetal rat calvariae were loaded with 18% cyclic tension force (TF) for 48 h. To phenotypically investigate the effect of TF, we measured the number and the size of bone nodules stained by von Kossa technique on day 21 after cell seeding and determined the calcium content of bone nodules on day 14. Furthermore, we examined the gene expression of BMP-2, Runx2 and Msx2, which are important factors for bone nodule formation, on days 1, 4 and 7 after TF loading.

RESULTS

The maximum bone nodule size in the control group was 1620 and 719 μm in the TF group. Furthermore, the mean number of bone nodules sized over 360 μm in the TF group was significantly decreased compared to the control group. The calcium content was also significantly decreased to 42% by TF loading. The mRNA expression of BMP-2, Runx2 and Msx2 was decreased 1 and 4 days after TF loading.

CONCLUSION

The differentiation of bone forming progenitor cells into bone nodule forming cells was inhibited by TF due to the decreased expression of bone formation related factors such as BMP-2, Runx2 and Msx2.

Genomewide comprehensive analysis reveals critical cooperation between Smad and c-Fos in RANKL-induced osteoclastogenesis

We have previously reported that transforming growth factor β (TGF-β) plays an essential role in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. However, the detailed underlying molecular mechanisms still remain unclear. Formaldehyde-assisted isolation of regulatory elements (FAIRE) and chromatin immunoprecipitation (ChIP) followed by sequencing (FAIRE-seq and ChIP-seq) analyses indicated the cooperation of Smad2/3 with c-Fos during osteoclastogenesis. Biochemical analysis and immunocytochemical analysis revealed that physical interaction between Smad2/3 and c-Fos is required for their nuclear translocation. The gene expression of nuclear factor of activated T-cells, cytoplasmic 1 (Nfatc1), a key regulator of osteoclastogenesis, was regulated by RANKL and TGF-β, and c-Fos binding to open chromatin sites was suppressed by inhibition of TGF-β signaling by SB431542. Conversely, Smad2/3 binding to Nfatc1 was impaired by c-Fos deficiency. These results suggest that TGF-β regulates RANKL-induced osteoclastogenesis through reciprocal cooperation between Smad2/3 and c-Fos.

A pathway to bone: signaling molecules and transcription factors involved in chondrocyte development and maturation

Decades of work have identified the signaling pathways that regulate the differentiation of chondrocytes during bone formation, from their initial induction from mesenchymal progenitor cells to their terminal maturation into hypertrophic chondrocytes. Here, we review how multiple signaling molecules, mechanical signals and morphological cell features are integrated to activate a set of key transcription factors that determine and regulate the genetic program that induces chondrogenesis and chondrocyte differentiation. Moreover, we describe recent findings regarding the roles of several signaling pathways in modulating the proliferation and maturation of chondrocytes in the growth plate, which is the 'engine' of bone elongation.

Blocking c-Met signaling enhances bone morphogenetic protein-2-induced osteoblast differentiation

•

Role of c-Met signaling in osteoblast differentiation was investigated.

•

Osteoblast differentiation was determined by ALP and osteocalcin production by C2C12 and MC3T3-E1 cells.

•

c-Met signaling negatively regulates osteoblast differentiation.

•

Blocking c-Met signaling might serve as a therapeutic strategy for rheumatoid arthritis.

We previously demonstrated that blocking hepatocyte growth factor (HGF) receptor/c-Met signaling inhibited arthritis and articular bone destruction in mouse models of rheumatoid arthritis (RA). In the present study, we investigated the role of c-Met signaling in osteoblast differentiation using the C2C12 myoblast cell line derived from murine satellite cells and the MC3T3-E1 murine pre-osteoblast cell line. Osteoblast differentiation was induced by treatment with bone morphogenetic protein (BMP)-2 or osteoblast-inducer reagent in the presence or absence of either HGF antagonist (NK4) or c-Met inhibitor (SU11274). Osteoblast differentiation was confirmed by Runx2 expression, and alkaline phosphatase (ALP) and osteocalcin production by the cells. Production of ALP, osteocalcin and HGF was verified by enzyme-linked immunosorbent assay. Runx2 expression was confirmed by reverse transcription-PCR analysis. The phosphorylation status of ERK1/2, AKT, and Smads was determined by Western blot analysis. Both NK4 and SU11274 enhanced Runx2 expression, and ALP and osteocalcin production but suppressed HGF production in BMP-2-stimulated C2C12 cells. SU11274 also enhanced ALP and osteocalcin production in osteoblast-inducer reagent-stimulated MC3T3-E1 cells. SU11274 inhibited ERK1/2 and AKT phosphorylation in HGF-stimulated C2C12 cells. This result suggested that ERK and AKT were functional downstream of the c-Met signaling pathway. However, both mitogen-activated protein kinase/ERK kinase (MEK) and phosphatidylinositol 3-kinase (PI3K) inhibitor suppressed osteocalcin and HGF production in BMP-2-stimulated C2C12 cells. Furthermore, SU11274, MEK, and PI3K inhibitor suppressed Smad phosphorylation in BMP-2-stimulated C2C12 cells. These results indicate that although the c-Met-MEK-ERK-Smad and c-Met-PI3K-AKT-Smad signaling pathways positively regulate osteoblast differentiation, c-Met signaling negatively regulates osteoblast differentiation, independent of the MEK-ERK-Smad and PI3K-AKT-Smad pathways. Therefore, blocking c-Met signaling might serve as a therapeutic strategy for the repair of destructed bone in patients with RA.

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.

Smad-induced alterations of matrix metabolism by a myristoyl tetra peptide

Regulation of extracellular matrix (ECM) components is essential for tissue homeostasis and function. We screened a small peptide that induces ECM protein synthesis for its usefulness in protecting keratinocytes. In this report, we demonstrate that myristoyl tetrapeptide Ala-Ala-Pro-Val (mAAPV) stimulates the expression of ECM proteins and inhibits the expression of metalloproteinases (MMPs) that degrade ECM proteins in Hs68 human fibroblast cells. In order to elucidate the underlying molecular mechanisms for the effects of mAAVP, we investigated the changes in gene expression in the presence of mAAPV using a cDNA microarray. Treatment with mAAPV resulted in decreased expression of MMP-related genes such as MMP1, MMP3, TIMP1 and TIMP3 and increased expression of collagen genes, including COL1A1, COL1A2, COL3A1, COL5A1 and COL6A3. The pattern of gene expression regulated by mAAPV was very similar to that of gene expression induced by transforming growth factor (TGF)-β, indicating that the TGF-β signaling pathway is crucial for simultaneous activation of several ECM-related genes by mAAPV. We examined whether the activation of SMAD, a downstream protein of TGF-β receptor, is involved in the signal transduction pathway induced by mAAPV. The results demonstrate that mAAVP directly activates SMAD2 and induces SMAD3 to bind to DNA. In conclusion, our results demonstrate that mAAPV both enhances the expression of collagen and inhibits its degradation via production of protease inhibitors that prevent enzymatic breakdown of the ECM. The results suggest that mAAPV would be a useful ECM-protecting agent.

Association between RUNX3 promoter methylation and non-small cell lung cancer: a meta-analysis

BACKGROUND

Runt-related transcription factor 3 (RUNX3) is a known regulator in the transforming growth factor (TGF)-β signaling pathway, which promoter methylation playing a crucial role in diverse neoplasias. However, the relationship between RUNX3 promoter methylation and non-small cell lung cancer (NSCLC) remains to be clarified.

METHODS

We searched Pubmed, Embase, Cochrane Central, and Chinese Biological Medicine database, for articles published in English or Chinese until March 7, 2014. Our main analyses were focused on the association between RUNX3 promoter methylation and risk of NSCLC by meta-analysis methods. If heterogeneity was observed, we used random effects model to calculate the overall odds ratios, otherwise fixed effects model was used. Subgroup analyses and meta-regression analyses were employed to detect the sources of the heterogeneity. Sensitivity analysis was performed to evaluate the stability of our studies. A funnel plot and Egger's test were conducted to investigate any potential publication bias.

RESULTS

A total of 1,368 samples from 13 literatures were involved in this meta-analysis. The pooled odds ratio (OR) of RUNX3 methylation in NSCLC specimens compared to non-cancer controls was 6.70 [95% confidence interval (CI): 4.64-9.67]. In the analysis of specimen-types subgroup, the summary OR was 5.79 (95% CI: 3.97-8.46) for tissue specimen subgroup, and that was 45.64 (95% CI: 5.89-353.72) for serum specimen subgroup. The ORs for the age ≤60 years, 60-65 years and >65 years subgroup were 5.19 (95% CI: 3.27-8.24), 9.45 (95% CI: 2.45-36.45) and 13.23 (95% CI: 5.59-31.28) respectively. The result of meta-regression indicated that age was fundamental source of heterogeneity (coefficient =0.61, P=0.046, adjusted R(2) =100%). No publication bias was detected. In cancer specimens, the RUNX3 methylation was associated with histological type of the NSCLC, but no significant differences were found for RUNX3 methylation in relation to gender, smoking history, tumor TNM stage or tumor differentiation level.

CONCLUSIONS

This meta-analysis of pooled data provides additional evidence to support a strong association between methylation of the RUNX3 promoter and NSCLC. RUNX3 methylation was increasing with age.

SMILE inhibits BMP-2-induced expression of osteocalcin by suppressing the activity of the RUNX2 transcription factor in MC3T3E1 cells

Small heterodimer partner interacting leucine zipper protein (SMILE) is an orphan nuclear receptor and a member of the bZIP family of proteins. Several recent studies have suggested that SMILE is a novel co-repressor that is involved in nuclear receptor signaling; however, the role of SMILE in osteoblast differentiation has not yet been elucidated. This study demonstrates that SMILE inhibits osteoblast differentiation by regulating the activity of Runt-related transcription factor-2 (RUNX2). Tunicamycin, an inducer of endoplasmic reticulum stress, stimulated SMILE expression. Bone morphogenetic protein-2-induced expression of alkaline phosphatase and osteocalcin, both of which are osteogenic genes, was suppressed by SMILE. The molecular mechanism by which SMILE affects osteocalcin expression was also determined. An immunoprecipitation assay revealed a physical interaction between SMILE and RUNX2 that significantly impaired the RUNX2-dependent activation of the osteocalcin gene. A ChIP assay revealed that SMILE repressed the ability of RUNX2 to bind to the osteocalcin gene promoter. Taken together, these findings demonstrate that SMILE negatively regulates osteocalcin via a direct interaction with RUNX2.

Epigallocatechin-3-gallate (EGCG) as a pro-osteogenic agent to enhance osteogenic differentiation of mesenchymal stem cells from human bone marrow: an in vitro study

The proliferation and osteogenic capacity of mesenchymal stem cells (MSCs) needs to be improved for their use in cell-based therapy for osteoporosis. (-)-Epigallocatechin-3-gallate (EGCG), one of the green tea catechins, has been widely investigated in studies of osteoblasts and osteoclasts. However, no consensus on its role as an osteogenic inducer has been reached, possibly because of the various types of cell lines examined and the range of concentrations of EGCG used. In this study, the osteogenic effects of EGCG are studied in primary human bone-marrow-derived MSCs (hBMSCs) by detecting cell proliferation, alkaline phosphatase (ALP) activity and the expression of relevant osteogenic markers. Our results show that EGCG has a strong stimulatory effect on hBMSCs developing towards the osteogenic lineage, especially at a concentration of 5 μM, as evidenced by an increased ALP activity, the up-regulated expression of osteogenic genes and the formation of bone-like nodules. Further exploration has indicated that EGCG directes osteogenic differentiation via the continuous up-regulation of Runx2. The underlying mechanism might involve EGCG affects on osteogenic differentiation through the modulation of bone morphogenetic protein-2 expression. EGCG has also been found to promote the proliferation of hBMSCs in a dose-dependent manner. This might be associated with its antioxidative effect leading to favorable amounts of reactive oxygen species in the cellular environment. Our study thus indicates that EGCG can be used as a pro-osteogenic agent for the stem-cell-based therapy of osteoporosis.

Histone demethylase Jmjd3 regulates osteoblast differentiation via transcription factors Runx2 and osterix

Post-translational modifications of histones including methylation play important roles in cell differentiation. Jumonji domain-containing 3 (Jmjd3) is a histone demethylase, which specifically catalyzes the removal of trimethylation of histone H3 at lysine 27 (H3K27me3). In this study, we examined the expression of Jmjd3 in osteoblasts and its roles in osteoblast differentiation. Jmjd3 expression in the nucleus was induced in response to the stimulation of osteoblast differentiation as well as treatment of bone morphogenetic protein-2 (BMP-2). Either treatment with Noggin, an inhibitor of BMP-2, or silencing of Smad1/5 suppressed Jmjd3 expression during osteoblast differentiation. Silencing of Jmjd3 expression suppressed osteoblast differentiation through the expression of bone-related genes including Runx2, osterix, osteopontin, bone sialoprotein (BSP), and osteocalcin (OCN). Silencing of Jmjd3 decreased the promoter activities of Runx2 and osterix and increased the level of H3K27me3 on the promoter regions of Runx2 and osterix. Introduction of the exogenous Runx2 and osterix partly rescued osteoblast differentiation in the shJmjd3 cells. The present results indicate that Jmjd3 plays important roles in osteoblast differentiation and regulates the expressions of BSP and OCN via transcription factors Runx2 and osterix.

BMP-2 differentially modulates FGF-2 isoform effects in osteoblasts from newborn transgenic mice

We previously generated separate lines of transgenic mice that specifically overexpress either the Fibroblast growth factor (FGF)-2 low-molecular-mass isoform (Tg(LMW)) or the high-mass isoforms (Tg(HMW)) in the osteoblast lineage. Vector/control (Tg(Vector)) mice were also made. Here we report the use of isolated calvarial osteoblasts (COBs) from those mice to investigate whether the FGF-2 protein isoforms differentially modulate bone formation in vitro. Our hypothesis states that FGF-2 isoforms specifically modulate bone morphogenetic protein 2 (BMP-2) function and subsequently bone differentiation genes and their related signaling pathways. We found a significant increase in alkaline phosphatase-positive colonies in Tg(LMW) COBs compared with Tg(Vector) controls. BMP-2 treatment significantly increased mineralized colonies in Tg(Vector) and Tg(LMW) COBs. BMP-2 caused a further significant increase in mineralized colonies in Tg(LMW) COBs compared with Tg(Vector) COBs but did not increase alkaline phosphatase-positive colonies in Tg(HMW) COBs. Time-course studies showed that BMP-2 caused a sustained increase in phosphorylated mothers against decapentaplegic-1/5/8 (Smad/1/5/8), runt-related transcription factor-2 (Runx-2), and osterix protein in Tg(LMW) COBs. BMP-2 caused a sustained increase in phospho-p38 MAPK in Tg(Vector) but only a transient increase in Tg(LMW) and Tg(HMW) COBs. BMP-2 caused a transient increase in phospho-p44/42 MAPK in Tg(Vector) COBs and no increase in Tg(LMW) COBs, but a sustained increase was found in Tg(HMW) COBs. Basal expression of FGF receptor 1 protein was significantly increased in Tg(LMW) COBs relative to Tg(Vector) COBs, and although BMP-2 caused a transient increase in FGF receptor 1 expression in Tg(Vector) COBs and Tg(HMW) COBs, there was no further increase Tg(LMW) COBs. Interestingly, although basal expression of FGF receptor 2 was similar in COBs from all genotypes, BMP-2 treatment caused a sustained increase in Tg(LMW) COBs but decreased FGF receptor 2 in Tg(Vector) COBs and Tg(HMW) COBs.

TGF-β signaling in C. elegans

Transforming Growth Factor-β (TGF-β) superfamily ligands regulate many aspects of cell identity, function, and survival in multicellular animals. Genes encoding five TGF-β family members are present in the genome of C. elegans. Two of the ligands, DBL-1 and DAF-7, signal through a canonical receptor-Smad signaling pathway; while a third ligand, UNC-129, interacts with a noncanonical signaling pathway. No function has yet been associated with the remaining two ligands. Here we summarize these signaling pathways and their biological functions.

ATP citrate lyase knockdown impacts cancer stem cells in vitro

ATP citrate lyase (ACL) knockdown (KD) causes tumor suppression and induces differentiation. We have previously reported that ACL KD reverses epithelial–mesenchymal transition (EMT) in lung cancer cells. Because EMT is often associated with processes that induce stemness, we hypothesized that ACL KD impacts cancer stem cells. By assessing tumorsphere formation and expression of stem cell markers, we showed this to be the case in A549 cells, which harbor a Ras mutation, and in two other non-small-cell lung cancer cell lines, H1975 and H1650, driven by activating EGFR mutations. Inducible ACL KD had the same effect as stable ACL KD. Similar effects were noted in another well-characterized Ras-induced mammary model system (HMLER). Moreover, treatment with hydroxycitrate phenocopied the effects of ACL KD, suggesting that the enzymatic activity of ACL was critical. Indeed, acetate treatment reversed the ACL KD phenotype. Having previously established that ACL KD impacts signaling through the phosphatidylinositol 3-kinase (PI3K) pathway, not the Ras-mitogen-activated protein kinase (MAPK) pathway, and that EMT can be reversed by PI3K inhibitors, we were surprised to find that stemness in these systems was maintained through Ras-MAPK signaling, and not via PI3K signaling. Snail is a downstream transcription factor impacted by Ras-MAPK signaling and known to promote EMT and stemness. We found that snail expression was reduced by ACL KD. In tumorigenic HMLER cells, ACL overexpression increased snail expression and stemness, both of which were reduced by ACL KD. Furthermore, ACL could not initiate either tumorigenesis or stemness by itself. ACL and snail proteins interacted and ACL expression regulated the transcriptional activity of snail. Finally, ACL KD counteracted stem cell characteristics induced in diverse cell systems driven by activation of pathways outside of Ras-MAPK signaling. Our findings unveil a novel aspect of ACL function, namely its impact on cancer stemness in a broad range of genetically diverse cell types.

Evaluation of the relationship between dietary factors, CagA-positive Helicobacter pylori infection, and RUNX3 promoter hypermethylation in gastric cancer tissue

AIM: To evaluate the relationship among Helicobacter pylori (H. pylori) infection, CagA status, and dietary factors with RUNX3 promoter hypermethylation.

METHODS: Gastric cancer tissue samples were collected from 184 South Korean patients. All patients were interviewed following a semi-quantitative food frequency questionnaire. The average frequencies of intake and portion sizes of 89 common food items were documented, and total intakes of calories, nutrients, vitamins, and minerals were calculated for each subject. DNA was extracted from gastric cancer tissue samples, and amplification of the HSP60 gene was performed to detect H. pylori infection. Nested polymerase chain reaction (PCR) was used to detect the presence of the CagA gene. RUNX3 gene expression was measured by reverse transcription-PCR, and RUNX3 methylation status was evaluated by methylation-specific PCR. The odds ratios (ORs) and 95%CI associated with RUNX3 promoter hypermethylation status were estimated for each of the food groups, lifestyle factors, and the interaction between dietary and lifestyle factors with CagA status of H. pylori infection.

RESULTS: Overall, 164 patients (89.1%) were positive for H. pylori DNA, with the CagA gene detected in 59 (36%) of these H. pylori-positive samples. In all, 106 (57.6%) patients with gastric cancer demonstrated CpG island hypermethylation at the RUNX3 promoter. RUNX3 expression was undetectable in 52 (43.7%) of the 119 gastric cancer tissues sampled. A high consumption of eggs may increase the risk of RUNX3 methylation in gastric cancer patients, having a mean OR of 2.15 (range, 1.14-4.08). A significantly increased OR of 4.28 (range, 1.19-15.49) was observed with a high consumption of nuts in patients with CagA-positive H. pylori infection. High intakes of carbohydrate, vitamin B1, and vitamin E may decrease the risk of RUNX3 methylation in gastric cancer tissue, particularly in CagA- or H. pylori-negative infection, with OR of 0.41 (0.19-0.90), 0.42 (0.20-0.89), and 0.29 (0.13-0.62), respectively. A high consumption of fruits may protect against RUNX3 methylation.

CONCLUSION: These results suggest that the CagA status of H. pylori infection may be a modifier of dietary effects on RUNX3 methylation in gastric cancer tissue.

TGF-β superfamily gene expression and induction of the Runx1 transcription factor in adult neurogenic regions after brain injury

Traumatic brain injury (TBI) increases neurogenesis in the forebrain subventricular zone (SVZ) and the hippocampal dentate gyrus (DG). Transforming growth factor-β (TGF-β) superfamily cytokines are important regulators of adult neurogenesis, but their involvement in the regulation of this process after brain injury is unclear. We subjected adult mice to controlled cortical impact (CCI) injury, and isolated RNA from the SVZ and DG at different post-injury time points. qPCR array analysis showed that cortical injury caused significant alterations in the mRNA expression of components and targets of the TGF-β, BMP, and activin signaling pathways in the SVZ and DG after injury, suggesting that these pathways could regulate post-injury neurogenesis. In both neurogenic regions, the injury also induced expression of Runt-related transcription factor-1 (Runx1), which can interact with intracellular TGF-β Smad signaling pathways. CCI injury strongly induced Runx1 expression in activated and proliferating microglial cells throughout the neurogenic regions. Runx1 protein was also expressed in a subset of Nestin- and GFAP-expressing putative neural stem or progenitor cells in the DG and SVZ after injury. In the DG only, these Runx1+ progenitors proliferated. Our data suggest potential roles for Runx1 in the processes of microglial cell activation and proliferation and in neural stem cell proliferation after TBI.

RUNX family: Regulation and diversification of roles through interacting proteins

The Runt-related transcription factors (RUNX) belong to an ancient family of metazoan genes involved in developmental processes. Through multiple protein-interacting partners, RUNX proteins have been implicated in diverse signaling pathways and cellular processes. The frequent inactivation of RUNX genes in cancer indicates crucial roles for RUNX in tumor suppression. This review discusses the abilities of RUNX proteins, in particular RUNX3, to integrate oncogenic signals or environmental cues and to initiate appropriate tumor suppressive responses.

Antitumor activity of cell-permeable RUNX3 protein in gastric cancer cells

PURPOSE

Gastric cancer is a leading cause of cancer death worldwide. Limited therapeutic options highlight the need to understand the molecular changes responsible for the disease and to develop therapies based on this understanding. The goal of this study was to develop cell-permeable (CP-) forms of the RUNT-related transcription factor 3, RUNX3-a candidate tumor suppressor implicated in gastric and other epithelial cancers-to study the therapeutic potential of RUNX3 in the treatment of gastric cancer.

EXPERIMENTAL DESIGN

We developed novel macromolecule transduction domains (MTD) which were tested for the ability to promote protein uptake by mammalian cells and tissues and used to deliver of biologically active RUNX3 into human gastric cancer cells. The therapeutic potential CP-RUNX3 was tested in the NCI-N87 human tumor xenograft animal model.

RESULTS

RUNX3 fusion proteins, HM(57)R and HM(85)R, containing hydrophobic MTDs enter gastric cancer cells and suppress cell phenotypes (e.g., cell-cycle progression, wounded monolayer healing, and survival) and induce changes in biomarker expression (e.g., p21(Waf1) and VEGF) consistent with previously described effects of RUNX3 on TGF-β signaling. CP-RUNX3 also suppressed the growth of subcutaneous human gastric tumor xenografts. The therapeutic response was comparable with studies augmenting RUNX3 gene expression in tumor cell lines; however, the protein was most active when administered locally, rather than systemically (i.e., intravenously).

CONCLUSIONS

These results provide further evidence that RUNX3 can function as a tumor suppressor and suggest that practical methods to augment RUNX3 function could be useful in treating of some types of gastric cancer.

Integrin αvβ3 and CD44 pathways in metastatic prostate cancer cells support osteoclastogenesis via a Runx2/Smad 5/receptor activator of NF-κB ligand signaling axis

BACKGROUND

Bone loss and pathological fractures are common skeletal complications associated with androgen deprivation therapy and bone metastases in prostate cancer patients. We have previously demonstrated that prostate cancer cells secrete receptor activator of NF-kB ligand (RANKL), a protein essential for osteoclast differentiation and activation. However, the mechanism(s) by which RANKL is produced remains to be determined. The objective of this study is to gain insight into the molecular mechanisms controlling RANKL expression in metastatic prostate cancer cells.

RESULTS

We show here that phosphorylation of Smad 5 by integrin αvβ3 and RUNX2 by CD44 signaling, respectively, regulates RANKL expression in human-derived PC3 prostate cancer cells isolated from bone metastasis. We found that RUNX2 intranuclear targeting is mediated by phosphorylation of Smad 5. Indeed, Smad5 knock-down via RNA interference and inhibition of Smad 5 phosphorylation by an αv inhibitor reduced RUNX2 nuclear localization and RANKL expression. Similarly, knockdown of CD44 or RUNX2 attenuated the expression of RANKL. As a result, conditioned media from these cells failed to support osteoclast differentiation in vitro. Immunohistochemistry analysis of tissue microarray sections containing primary prostatic tumor (grade2-4) detected predominant localization of RUNX2 and phosphorylated Smad 5 in the nuclei. Immunoblotting analyses of nuclear lysates from prostate tumor tissue corroborate these observations.

CONCLUSIONS

Collectively, we show that CD44 signaling regulates phosphorylation of RUNX2. Localization of RUNX2 in the nucleus requires phosphorylation of Smad-5 by integrin αvβ3 signaling. Our results suggest possible integration of two different pathways in the expression of RANKL. These observations imply a novel mechanistic insight into the role of these proteins in bone loss associated with bone metastases in patients with prostate cancer.

Trks are novel oncogenes involved in the induction of neovascularization, tumor progression, and nodal metastasis in oral squamous cell carcinoma

The function of tropomyosin receptor kinase (Trk) family including TrkA, TrkB, and TrkC in cancer remains unknown. The role of Trks in oral squamous cell carcinoma (OSCC) was examined. Knockdown of Trks provided inhibition of growth or invasion and decrease of apoptosis in OSCC cells, which expressed Trks at high levels. VEGF expression was associated with TrkA and TrkB expression; a decrease of VEGF-C and VEGF-D was observed in OSCC cells with TrkB knockdown. TrkC did not affect the expression of VEGF family. An immunohistochemical analysis of 102 OSCCs showed that TrkB expression was related to microvessel density (MVD), lymph vessel density (LVD), and poor prognosis. TrkC expression was correlated with clinical stage, lymph node metastasis, MVD, LVD, and poor prognosis. TrkA expression was associated with VEGF expression, whereas TrkB expression was associated with the expressions of VEGF, VEGF-C and VEGF-D. No significant association was found between the expression of TrkC and genes of the VEGF family. Expression of Trks was not associated with RUNX3 silencing by methylation in OSCC cells. Trks expression was inversely correlated with RUNX3 expression in the OSCC cases. These results suggested that Trks enhances progression of OSCC through angiogenesis and lymphangiogenesis.

Runx3 expression and its roles in mouse endometrial cells

Runx3 is a transcription factor that belongs to the Runx family. We studied the localization of Runx3 mRNA in the mouse uterus, and its function in the mouse endometrium using Runx3 knockout (Runx3(-/-)) mice. Runx3 mRNA was detected in the endometrial luminal epithelial cells, glandular epithelial cells and stromal cells below the epithelial cell layer on the luminal side. The uteri of Runx3(-/-) mice were smaller than those of wt mice. The endometrial layer and uterine glands of Runx3(-/-) mice were less developed than those of wild-type mice, and the endometrial stromal layer was thinner. Transforming growth factor β1 and β3 (TGFβ1 and β3) mRNA levels in endometrial stromal cells of Runx3(-/-) mice were low compared with those of wild-type mice. Estradiol-17β (E2) increased Tgfb2 mRNA levels in endometrial stromal cells of Runx3(-/-) mice, but not in those of wild-type mice. E2 increased epidermal growth factor (EGF) mRNA levels in endometrial stromal cells of wild-type mice, but did not increase those of Runx3(-/-) mice. The diminished Tgfb1 and Tgfb3 mRNA expressions may lead to the reduced proliferation of endometrial stromal cells. Alterations of E2-associated expressions of Tgfb2 and Egf mRNA in endometrial stromal cells of Runx3(-/-) mice may be associated with suppression of E2-dependent endometrial epithelial cell proliferation in Runx3(-/-) mice. Thus, Runx3 is likely to be a regulatory factor responsible for endometrial growth.

RUNX3 downregulation in human lung adenocarcinoma is independent of p53, EGFR or KRAS status

RUNX3 aberrations play a pivotal role in the oncogenesis of breast, gastric, colon, skin and lung tissues. The aim of this study was to characterize further the expression of RUNX3 in lung cancers. To achieve this, a lung cancer tissue microarray (TMA), frozen lung cancer tissues and lung cell lines were examined for RUNX3 expression by immunohistochemistry, while the TMA was also examined for EGFR and p53 expression. RUNX3 promoter methylation status, and EGFR and KRAS mutation status were also investigated. Inactivation of RUNX3 was observed in 70% of the adenocarcinoma samples, and this was associated with promoter hypermethylation but not biased to EGFR/KRAS mutations. Our results suggest a central role of RUNX3 downregulation in pulmonary adenocarcinoma, which may not be dependent of other established cancer-causing pathways and may have important diagnostic and screening implications.

Cilomilast enhances osteoblast differentiation of mesenchymal stem cells and bone formation induced by bone morphogenetic protein 2

A rapid and efficient method to stimulate bone regeneration would be useful in orthopaedic stem cell therapies. Rolipram is an inhibitor of phosphodiesterase 4 (PDE4), which mediates cyclic adenosine monophosphate (cAMP) degradation. Systemic injection of rolipram enhances osteogenesis induced by bone morphogenetic protein 2 (BMP-2) in mice. However, there is little data on the precise mechanism, by which the PDE4 inhibitor regulates osteoblast gene expression. In this study, we investigated the combined ability of BMP-2 and cilomilast, a second-generation PDE4 inhibitor, to enhance the osteoblastic differentiation of mesenchymal stem cells (MSCs). The alkaline phosphatase (ALP) activity of MSCs treated with PDE4 inhibitor (cilomilast or rolipram), BMP-2, and/or H89 was compared with the ALP activity of MSCs differentiated only by osteogenic medium (OM). Moreover, expression of Runx2, osterix, and osteocalcin was quantified using real-time polymerase chain reaction (RT-PCR). It was found that cilomilast enhances the osteoblastic differentiation of MSCs equally well as rolipram in primary cultured MSCs. Moreover, according to the H89 inhibition experiments, Smad pathway was found to be an important signal transduction pathway in mediating the osteogenic effect of BMP-2, and this effect is intensified by an increase in cAMP levels induced by PDE4 inhibitor.

Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.

BRITER: a BMP responsive osteoblast reporter cell line

Background

BMP signaling pathway is critical for vertebrate development and tissue homeostasis. High-throughput molecular genetic screening may reveal novel players regulating BMP signaling response while chemical genetic screening of BMP signaling modifiers may have clinical significance. It is therefore important to generate a cell-based tool to execute such screens.

Methodology/Principal Findings

We have established a BMP responsive reporter cell line by stably integrating a BMP responsive dual luciferase reporter construct in the immortalized calvarial osteoblast cells isolated from tamoxifen inducible Bmp2; Bmp4 double conditional knockout mouse strain. This cell line, named BRITER (BMP Responsive Immortalized Reporter cell line), responds robustly, promptly and specifically to exogenously added BMP2 protein. The sensitivity to added BMP may be further increased by depleting the endogenous BMP2 and BMP4 proteins.

Conclusion

As the dynamic range of the assay (for BMP responsiveness) is very high for BRITER and as it responds specifically and promptly to exogenously added BMP2 protein, BRITER may be used effectively for chemical or molecular genetic screening for BMP signaling modifiers. Identification of novel molecular players capable of influencing BMP signaling pathway may have clinical significance.

Prolyl isomerase Pin1 downregulates tumor suppressor RUNX3 in breast cancer

Emerging evidence demonstrates that RUNX3 is a tumor suppressor in breast cancer. Inactivation of RUNX3 in mice results in spontaneous mammary gland tumors, and decreased or silenced expression of RUNX3 is frequently found in breast cancer cell lines and human breast cancer samples. However, the underlying mechanism for initiating RUNX3 inactivation in breast cancer remains elusive. Here, we identify prolyl-isomerase Pin1, which is often over-expressed in breast cancer, as a key regulator of RUNX3 inactivation. In human breast cancer cell lines and breast cancer samples, expression of Pin1 inversely correlates with the expression of RUNX3. In addition, Pin1 recognizes four phosphorylated Ser/Thr-Pro motifs in RUNX3 via its WW domain. Binding of Pin1 to RUNX3 suppresses the transcriptional activity of RUNX3. Furthermore, Pin1 reduces the cellular levels of RUNX3 in an isomerase activity-dependent manner by inducing the ubiquitination and proteasomal degradation of RUNX3. Knocking down Pin1 enhances the cellular levels and transcriptional activity of RUNX3 by inhibiting the ubiquitination and degradation of RUNX3. Our results identify Pin1 as a new regulator of RUNX3 inactivation in breast cancer.

Regulation of bone and cartilage development by network between BMP signalling and transcription factors

Bone morphogenetic protein(s) (BMP) are very powerful cytokines that induce bone and cartilage formation. BMP also stimulate osteoblast and chondrocyte differentiation. During bone and cartilage development, BMP regulates the expression and/or the function of several transcription factors through activation of Smad signalling. Genetic studies revealed that Runx2, Osterix and Sox9, all of which function downstream of BMP, play essential roles in bone and/or cartilage development. In addition, two other transcription factors, Msx2 and Dlx5, which interact with BMP signalling, are involved in bone and cartilage development. The importance of these transcription factors in bone and cartilage development has been supported by biochemical and cell biological studies. Interestingly, BMP is regulated by several negative feedback systems that appear necessary for fine-tuning of bone and cartilage development induced by BMP. Thus, BMP harmoniously regulates bone and cartilage development by forming network with several transcription factors.

RUNX3 is involved in caspase-3-dependent apoptosis induced by a combination of 5-aza-CdR and TSA in leukaemia cell lines

PURPOSE

Epigenetic therapy has had a significant impact on the management of haematologic malignancies. The aim of this study was to assess whether 5-aza-CdR and TSA inhibit the growth of leukaemia cells and induce caspase-3-dependent apoptosis by upregulating RUNX3 expression.

METHODS

K562 and Reh cells were treated with 5-aza-CdR, TSA or both compounds. RT-PCR and Western blot analyses were used to examine the expression of RUNX3 at the mRNA and protein levels, respectively. Immunofluorescence microscopy was used to detect the cellular location of RUNX3. Additionally, after K562 cells were transfected with RUNX3, apoptosis and proliferation were studied using Annexin V staining and MTT assays.

RESULTS

The expression of RUNX3 in leukaemia cell lines was markedly less than that in the controls. Demethylating drug 5-aza-CdR could induce RUNX3 expression, but the combination of TSA and 5-aza-CdR had a greater effect than did treatment with a single compound. The combination of 5-aza-CdR and TSA induced the translocation of RUNX3 from the cytoplasm into the nucleus. TSA enhanced apoptosis induced by 5-aza-CdR, and Annexin V and Hoechst 33258 staining showed that the combination induced apoptosis but not necrosis. Furthermore, apoptosis was dependent on the caspase-3 pathway. RUNX3 overexpression in K562 cells led to growth inhibition and apoptosis and potentiated the effects of 5-aza-CdR induction.

CONCLUSION

RUNX3 plays an important role in leukaemia cellular functions, and the induction of RUNX3-mediated effects may contribute to the therapeutic value of combination TSA and 5-aza-CdR treatment.

Osteoblastic γ-aminobutyric acid, type B receptors negatively regulate osteoblastogenesis toward disturbance of osteoclastogenesis mediated by receptor activator of nuclear factor κB ligand in mouse bone

The prevailing view is that signaling machineries for the neurotransmitter GABA are also expressed by cells outside the CNS. In cultured murine calvarial osteoblasts, mRNA was constitutively expressed for both subunits 1 and 2 of metabotropic GABA(B) receptor (GABA(B)R), along with inhibition by the GABA(B)R agonist baclofen of cAMP formation, alkaline phosphatase (ALP) activity, and Ca(2+) accumulation. Moreover, baclofen significantly inhibited the transactivation of receptor activator of nuclear factor-κB ligand (RANKL) gene in a manner sensitive to a GABA(B)R antagonist, in addition to decreasing mRNA expression of bone morphogenetic protein-2 (BMP2), osteocalcin, and osterix. In osteoblastic MC3T3-E1 cells stably transfected with GABA(B)R1 subunit, significant reductions were seen in ALP activity and Ca(2+) accumulation, as well as mRNA expression of osteocalcin, osteopontin, and osterix. In cultured calvarial osteoblasts from GABA(B)R1-null mice exhibiting low bone mineral density in tibia and femur, by contrast, both ALP activity and Ca(2+) accumulation were significantly increased together with promoted expression of both mRNA and proteins for BMP2 and osterix. No significant change was seen in the number of multinucleated cells stained for tartrate-resistant acid phosphatase during the culture of osteoclasts prepared from GABA(B)R1-null mice, whereas a significant increase was seen in the number of tartrate-resistant acid phosphatase-positive multinucleated cells in co-culture of osteoclasts with osteoblasts isolated from GABA(B)R1-null mice. These results suggest that GABA(B)R is predominantly expressed by osteoblasts to negatively regulate osteoblastogenesis through down-regulation of BMP2 expression toward disturbance of osteoclastogenesis after down-regulation of RANKL expression in mouse bone.

Balancing acts: the role of TGF-β in the mucosal immune system

The gastrointestinal mucosal immune system faces unique challenges in dealing not only with fed antigens but also both commensal and pathogenic bacteria. It is tasked with digesting, transporting and using nutritional antigens while protecting the host from pathogenic organisms. As such, mechanisms that mediate effective immunity and immune tolerance are active within the gut environment. To accomplish this, the mucosal immune system has evolved sophisticated mechanisms that safeguard the integrity of the mucosal barrier. Transforming growth factor-β (TGF-β) emerges as a key mediator, balancing the tolerogenic and immunogenic forces at play in the gut. In this review, we discuss the role of TGF-β in the generation and functioning of gut lymphocyte populations. We highlight recent findings, summarize controversies, outline remaining questions and provide our personal perspectives.

TGF-β1 stimulates mouse macrophages to express APRIL through Smad and p38MAPK/CREB pathways

A proliferation-inducing ligand (APRIL), a new TNF family member, supports B-cell survival and tumor cell proliferation. APRIL is secreted as a soluble protein by macrophages, dendritic cells and activated T cells. However, factors involved in regulation of APRIL expression are as yet unknown. In this study, we investigated the effect of TGF-β1 on APRIL expression in P388D1, a mouse macrophage cell line. TGF-β1 induced APRIL mRNA expression in a time- and dose-dependent manner. One nanogram per milliliter of TGF-β1 was optimal and APRIL transcripts appeared as early as 3 h after stimulation. Based on our studies, which included overexpression of Smad3, DN-Smad3, and sh-Smad3, we found that Smad3 mediates APRIL transcription at least partially. Further, experiments using inhibitors revealed that p38MAPK and CREB are also involved in TGF-β1-induced APRIL expression. These results suggest that TGF-β1, through Smad3 and p38MAPK/CREB signaling pathways, stimulates APRIL expression in macrophages.

Association between RUNX3 promoter methylation and gastric cancer: a meta-analysis

Background

Runt-related transcription factor 3 (RUNX3) is a member of the runt-domain family of transcription factors and has been reported to be a candidate tumor suppressor in gastric cancer. However, the association between RUNX3 promoter methylation and gastric cancer remains unclear.

Methods

We systematically reviewed studies of RUNX3 promoter methylation and gastric cancer published in English or Chinese from January 2000 to January 2011, and quantified the association between RUNX3 promoter methylation and gastric cancer using meta-analysis methods.

Results

A total of 1740 samples in 974 participants from seventeen studies were included in the meta-analysis. A significant association was observed between RUNX3 promoter methylation and gastric cancer, with an aggregated odds ratio (OR) of 5.63 (95%CI 3.15, 10.07). There was obvious heterogeneity among studies. Subgroup analyses (including by tissue origin, country and age), meta-regression were performed to determine the source of the heterogeneity. Meta-regression showed that the trend in ORs was inversely correlated with age. No publication bias was detected. The ORs for RUNX3 methylation in well-differentiated vs undifferentiated gastric cancers, and in intestinal-type vs diffuse-type carcinomas were 0.59 (95%CI: 0.30, 1.16) and 2.62 (95%CI: 1.33, 5.14), respectively. There were no significant differences in RUNX3 methylation in cancer tissues in relation to age, gender, TNM stage, invasion of tumors into blood vessel or lymphatic ducts, or tumor stage.

Conclusions

This meta-analysis identified a strong association between methylation of the RUNX3 promoter and gastric cancer, confirming the role of RUNX3 as a tumor suppressor gene.

RUNX3 in oncogenic and anti-oncogenic signaling in gastrointestinal cancers

The reputation of RUNX3 as a strong candidate for a tumor suppressor originated from studies of gastric carcinogenesis and now extends to a variety of other human cancers. The RUNX3 transcription factor is a downstream effector of the TGF-β superfamily signaling pathway and has a critical role in the regulation of cell proliferation, cell death by apoptosis, and cell adhesion. Recently, RUNX3 was proposed as a gatekeeper linking oncogenic Wnt and anti-oncogenic TGF-β/BMPs signaling pathways in intestinal tumorigenesis in mouse and human. Also, loss of RUNX3 leading to elevated oncogenic Wnt activity was found to be a key event in inducing a precancerous state of the stomach. Chronic Helicobacter pylori infection is reported to inactivate RUNX3 in gastric carcinogenesis by multiple mechanisms. This "Prospect" focuses on our current understanding of the tumor suppressive functions of RUNX3 in the context of gastrointestinal cancer initiation and progression.

Activin A stimulates mouse macrophages to express APRIL via the Smad3 and ERK/CREB pathways

A proliferation-inducing ligand (APRIL) is primarily expressed by macrophages and dendritic cells, and stimulates B cell proliferation, differentiation, survival, and Ig production. In the present study, we investigated the role and signaling mechanisms of activin A in APRIL expression by mouse macrophages. Activin A markedly enhanced APRIL expression in mouse macrophages at both the transcriptional and protein levels. Overexpression of dominant-negative (DN)-Smad3 and SB431542 abrogated activin-induced APRIL transcription. Furthermore, activin A induced Smad3 phosphorylation. These results indicate that activin A enhances APRIL expression through both activin receptor-like kinase 4 (ALK4) and Smad3. In a subsequent analysis of activin A signaling, it was found that PD98059, an extracellular signal-related kinase (ERK) inhibitor, eliminated activin A-induced APRIL expression. On the other hand, overexpression of cAMP responsive element-binding protein (CREB), a molecule downstream of ERK, augmented activin A-induced APRIL expression, and this effect could be abolished by PD98059. This finding that activin A induces ERK and CREB phosphorylation suggests that ERK and CREB act as intermediates in APRIL expression. Taken together, these results demonstrate that activin A can enhance APRIL expression through two different pathways, Smad3 and ERK/CREB.

Bone morphogenic protein: an elixir for bone grafting--a review

Bone morphogenetic proteins (BMPs) are multifunctional growth factors that belong to the transforming growth factor beta superfamily. This literature review focuses on the molecular biology of BMPs, their mechanism of action, and subsequent applications. It also discusses uses of BMPs in the fields of dentistry and orthopedics, research on methods of delivering BMPs, and their role in tissue regeneration. BMP has positive effects on bone grafts, and their calculated and timely use with other growth factors can provide extraordinary results in fractured or nonhealing bones. Use of BMP introduces new applications in the field of implantology and bone grafting. This review touches on a few unknown facts about BMP and this ever-changing field of research to improve human life.

Runx3 is required for full activation of regulatory T cells to prevent colitis-associated tumor formation

Inflammation is increasingly recognized as an essential component of tumorigenesis, which is promoted and suppressed by various T cell subsets acting in different ways. It was shown previously in Runx3-deficient mice that differentiation of CD8 T and NK cells is perturbed. In this study, we show that Runx3 is also required for proper differentiation and function of regulatory T cells. In Runx3-deficient mice, T cells were unable to inhibit inflammation and to suppress tumor development. As expected, recombination activating gene 2-deficient mice bearing Runx3-deficient lymphocytes spontaneously developed colon tumors. However, tumor formation was completely blocked by transfer of either regulatory T cells or CD8 T cells derived from wild-type mice to mutant mice or by housing mutant mice in a specific pathogen-free condition. These results indicate that Runx3-deficient lymphocytes and microorganisms act together to induce inflammation and consequently induce the development of colon tumors.

Dynamic smad-mediated BMP signaling revealed through transgenic zebrafish

Bone morphogenic protein (BMP) signaling is fundamental to development, injury response, and homeostasis. We have developed transgenic zebrafish that report Smad-mediated BMP signaling in embryos and adults. These lines express either enhanced green fluorescent protein (eGFP), destabilized eGFP, or destabilized Kusabira Orange 2 (KO2) under the well-characterized BMP Response Element (BRE). These fluorescent proteins were found to be expressed dynamically in regions of known BMP signaling including the developing tail bud, hematopoietic lineage, dorsal eye, brain structures, heart, jaw, fins, and somites, as well as other tissues. Responsiveness to changes in BMP signaling was confirmed by observing fluorescence after activation in an hsp70:bmp2b transgenic background or by inhibition in an hsp70:nog3 background. We further demonstrated faithful reportage by the BRE transgenic lines following chemical repression of BMP signaling using an inhibitor of BMP receptor activity, dorsomorphin. Overall, these lines will serve as valuable tools to explore the mechanisms and regulation of BMP signal during embryogenesis, in tissue maintenance, and during disease.

Control of the development of CD8αα+ intestinal intraepithelial lymphocytes by TGF-β

The molecular mechanisms directing the development of TCRαβ⁺CD8αα⁺ intestinal intraepithelial lymphocytes (IEL) are not thoroughly understood. Here we show that transforming growth factor-β (TGF-β) controls the development of TCRαβ⁺CD8αα⁺ IEL. Mice with either a TGF-β1 null mutation or a T cell-specific deletion of the TGF-β receptor I lacked TCRαβ⁺CD8αα⁺ IEL, whereas transgenic mice that over-expressed TGF-β1 had an increased population of TCRαβ⁺CD8αα⁺ IEL. Defective development of the TCRαβ⁺CD8αα⁺ IEL thymic precursors (CD4^-CD8^-TCRαβ⁺CD5⁺) was observed in the absence of TGF-β. In addition, we showed that TGF-β signaling induced CD8α expression in TCRαβ⁺CD8αα⁺ IEL thymic precursors and induced and maintained CD8α expression in peripheral populations of T cells. These data demonstrate a previously unrecognized role for TGF-β in the development of TCRαβ⁺CD8αα⁺ IEL and the expression of CD8 in T cells.