Arginine methylation of the c-Jun coactivator RACO-1 is required for c-Jun/AP-1 activation

Immune infiltration is associated with pan-cancer prognostic biomarker RING finger protein 187

Cancer is associated with the highest mortality rate globally. While life-saving screening and treatments exist, better awareness is needed. RNF187, an E3 ligase regulating biological processes, belongs to the RING domain-containing E3 ligase family. RNF187 may serve as an oncogene due to abnormal expression in tumors. However, its association with immune infiltration and prognosis across various cancers remains unclear. We searched several databases including TCGA, GTE x, CCLE, TIMER, and GSEA. R software was used to evaluate RNF187 differential expression, survival, pathology stage, DNA methylation, tumor mutational burden (TMB), microsatellite instability (MSI), gene co-expression analysis, mismatch repairs (MMRs), tumor microenvironment (TME), and immune cell infiltration. Clinicopathological data were collected, and immunohistochemistry was used to verify RNF187 expression in tumor tissues. RNF187 expression was up-regulated in various cancers compared to that in normal tissues and associated with poor patient outcomes. Dysregulation of RNF187 expression in multiple cancer types was strongly correlated with DNA methylation, MMR, MSI, and TMB. RNF187 could interact with different immune cells in cancers. Biomarkers associated with RNF187 may be helpful for prognosis and immunology in treating pan-cancer patients.

E3 ubiquitin ligase RNF187 promotes growth of spermatogonia via lysine 48-linked polyubiquitination-mediated degradation of KRT36/KRT84

Ubiquitination is the most common post-translational modification and is essential for various cellular regulatory processes. RNF187, which is known as RING domain AP1 coactivator-1, is a member of the RING finger family. RNF187 can promote the proliferation and migration of various tumor cells. However, whether it has a similar role in regulating spermatogonia is not clear. This study explored the role and molecular mechanism of RNF187 in a mouse spermatogonia cell line (GC-1). We found that RNF187 knockdown reduced the proliferation and migration of GC-1 cells and promoted their apoptosis. RNF187 overexpression significantly increased the proliferation and migration of GC-1 cells. In addition, we identified Keratin36/Keratin84 (KRT36/KRT84) as interactors with RNF187 by co-immunoprecipitation and mass spectrometry analyses. RNF187 promoted GC-1 cell growth by degrading KRT36/KRT84 via lysine 48-linked polyubiquitination. Subsequently, we found that KRT36 or KRT84 overexpression significantly attenuated proliferation and migration of RNF187-overexpressing GC-1 cells. In summary, our study explored the involvement of RNF187 in regulating the growth of spermatogonia via lysine 48-linked polyubiquitination-mediated degradation of KRT36/KRT84. This may provide a promising new strategy for treating infertility caused by abnormal spermatogonia development.

Methylation of BRD4 by PRMT1 regulates BRD4 phosphorylation and promotes ovarian cancer invasion

Bromodomain-containing protein 4 (BRD4), the major component of bromodomain and extra-terminal domain (BET) protein family, has important functions in early embryonic development and cancer development. However, the posttranslational modification of BRD4 is not well understood. Multiple approaches were used to explore the mechanism of PRMT1-mediated BRD4 methylation and to determine the biological functions of BRD4 and PRMT1 in ovarian cancer. Here we report that BRD4 is asymmetrically methylated at R179/181/183 by PRMT1, which is antagonized by the Jumonji-family demethylase, JMJD6. PRMT1 is overexpressed in ovarian cancer tissue and is a potential marker for poor prognosis in ovarian cancer patients. Silencing of PRMT1 inhibited ovarian cancer proliferation, migration, and invasion in vivo and in vitro. PRMT1-mediated BRD4 methylation was found to promote BRD4 phosphorylation. Compared to BRD4 wild-type (WT) cells, BRD4 R179/181/183K mutant-expressing cells showed reduced ovarian cancer metastasis. BRD4 arginine methylation is also associated with TGF-β signaling. Our results indicate that arginine methylation of BRD4 by PRMT1 is involved in ovarian cancer tumorigenesis. Targeting PRMT1-mediated arginine methylation may provide a novel diagnostic target and an effective therapeutic strategy for ovarian cancer treatment.

Mitogen- and stress-activated protein kinase (MSK1/2) regulated gene expression in normal and disease states

The mitogen- and stress-activated protein kinases (MSK) are epigenetic modifiers that regulate gene expression in normal and disease cell states. MSK1 and 2 are involved in a chain of signal transduction events bringing signals from the external environment of a cell to specific sites in the genome. MSK1/2 phosphorylate histone H3 at multiple sites, resulting in chromatin remodeling at regulatory elements of target genes and the induction of gene expression. Several transcription factors (RELA of NF-κB and CREB) are also phosphorylated by MSK1/2 and contribute to induction of gene expression. In response to signal transduction pathways, MSK1/2 can stimulate genes involved in cell proliferation, inflammation, innate immunity, neuronal function, and neoplastic transformation. Abrogation of the MSK-involved signaling pathway is among the mechanisms by which pathogenic bacteria subdue the host's innate immunity. Depending on the signal transduction pathways in play and the MSK-targeted genes, MSK may promote or hinder metastasis. Thus, depending on the type of cancer and genes involved, MSK overexpression may be a good or poor prognostic factor. In this review, we focus on mechanisms by which MSK1/2 regulate gene expression, and recent studies on their roles in normal and diseased cells.

Dysregulation of miR-144-5p/RNF187 axis contributes to the progression of colorectal cancer

Background and Objectives

RING finger protein 187 (RNF187) belongs to RING domain-containing E3 ligases family, which was recently reported to be involved in oncogenesis and development of several cancers. This research aims to clarify the role of RNF187 in colorectal cancer (CRC) development.

Methods

The expression of RNF187 and miR-144-4p were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The levels of RNF187 protein were assessed by western blot analysis. Cell Counting Kit-8 (CCK8) assay, clonogenic assay, cell scratch test and transwell assay were used to determine the proliferation, migration and invasion of CRC cells in vitro. The binding of miR-144-5p and RNF197 mRNA was validated by luciferase reporter assays. Tumor-bearing nude mice were used to determine CRC cells growth in vivo.

Results

RNF187 expression significantly increased in CRC specimens and cell lines compared to normal colon tissues and normal colonic mucosa cell line, respectively. Upregulation of RNF187 expression was inversely correlated to poor prognosis in CRC patients. In addition, knockdown of RNF187 expression inhibited the proliferation, migration, and invasion but promoted the apoptosis of CRC lines Caco-2 and SW480 cells. Further studies validated that RNF187 was the direct target of miR-144-5p. The expression of miR-144-5p was downregulated in CRC tissues, which was negatively correlated to the expression of RNF187. Restoration of miR-144-5p significantly inhibited the progression of CRC cells and its anti-tumor effects could be abrogated by overexpression of RNF187.

Conclusion

Our findings demonstrate the deregulation of miR-144-5p/ RNF187 axis in CRC, as well as its role in regulation of the tumor progression, thus providing a novel therapeutic strategy for CRC treatment.

Stem Cell-Based Therapy for Diabetic Foot Ulcers

Diabetic foot ulcer has become a worldwide clinical medical challenge as traditional treatments are not effective enough to reduce the amputation rate. Therefore, it is of great social significance to deeply study the pathogenesis and biological characteristics of the diabetic foot, explore new treatment strategies and promote their application. Stem cell-based therapy holds tremendous promise in the field of regenerative medicine, and its mechanisms include promoting angiogenesis, ameliorating neuroischemia and inflammation, and promoting collagen deposition. Studying the specific molecular mechanisms of stem cell therapy for diabetic foot has an important role and practical clinical significance in maximizing the repair properties of stem cells. In addition, effective application modalities are also crucial in order to improve the survival and viability of stem cells at the wound site. In this paper, we reviewed the specific molecular mechanisms of stem cell therapy for diabetic foot and the extended applications of stem cells in recent years, with the aim of contributing to the development of stem cell-based therapy in the repair of diabetic foot ulcers.

Regulation of P53 signaling in breast cancer by the E3 ubiquitin ligase RNF187

The tumor suppressor P53 plays critical role in preventing cancer. P53 is rarely mutated and remains functional in luminal-type breast cancer(1). According to current knowledge, wild-type P53 function is tightly controlled by posttranslational modifications, such as ubiquitination. Several ubiquitin ligases have been shown to regulate P53 ubiquitination and protein stability. Here, we report that RNF187, a RING family ubiquitin ligase, facilitates breast cancer growth and inhibits apoptosis by modulating P53 signaling. RNF187 expression was elevated in breast cancer and correlated with breast cancer survival only in the P53 wild-type groups. Bioinformatic analysis showed that the expression of RNF187 was negatively correlated with the expression of P53 target genes, such as IGFBP3 and FAS, in breast cancer. RNF187 depletion inhibited breast cancer growth and facilitated cell death. RNA sequencing analysis indicated that RNF187 could be an important modulator of P53 signaling. Further experiments showed that RNF187 interacts with P53 and promotes its degradation by facilitating its polyubiquitination in breast cancer cells. Interestingly, the in vitro ubiquitin assay showed that RNF187 can directly ubiquitinate P53 in a manner independent of MDM2. These findings reveal a novel direct P53 regulator and a potential therapeutic target for breast cancer.

How Protein Methylation Regulates Steroid Receptor Function

Steroid receptors (SRs) are members of the nuclear hormonal receptor family, many of which are transcription factors regulated by ligand binding. SRs regulate various human physiological functions essential for maintenance of vital biological pathways, including development, reproduction, and metabolic homeostasis. In addition, aberrant expression of SRs or dysregulation of their signaling has been observed in a wide variety of pathologies. SR activity is tightly and finely controlled by post-translational modifications (PTMs) targeting the receptors and/or their coregulators. Whereas major attention has been focused on phosphorylation, growing evidence shows that methylation is also an important regulator of SRs. Interestingly, the protein methyltransferases depositing methyl marks are involved in many functions, from development to adult life. They have also been associated with pathologies such as inflammation, as well as cardiovascular and neuronal disorders, and cancer. This article provides an overview of SR methylation/demethylation events, along with their functional effects and biological consequences. An in-depth understanding of the landscape of these methylation events could provide new information on SR regulation in physiology, as well as promising perspectives for the development of new therapeutic strategies, illustrated by the specific inhibitors of protein methyltransferases that are currently available.

Contribution of the Transcription Factors Sp1/Sp3 and AP-1 to Clusterin Gene Expression during Corneal Wound Healing of Tissue-Engineered Human Corneas

In order to reduce the need for donor corneas, understanding of corneal wound healing and development of an entirely tissue-engineered human cornea (hTECs) is of prime importance. In this study, we exploited the hTEC to determine how deep wound healing affects the transcriptional pattern of corneal epithelial cells through microarray analyses. We demonstrated that the gene encoding clusterin (CLU) has its expression dramatically repressed during closure of hTEC wounds. Western blot analyses confirmed a strong reduction in the expression of the clusterin isoforms after corneal damage and suggest that repression of CLU gene expression might be a prerequisite to hTEC wound closure. Transfection with segments from the human CLU gene promoter revealed the presence of three regulatory regions: a basal promoter and two more distal negative regulatory regions. The basal promoter bears DNA binding sites for very potent transcription factors (TFs): Activator Protein-1 (AP-1) and Specificity protein-1 and 3 (Sp1/Sp3). By exploiting electrophoretic mobility shift assays (EMSA), we demonstrated that AP-1 and Sp1/Sp3 have their DNA binding site overlapping with one another in the basal promoter of the CLU gene in hCECs. Interestingly, expression of both these TFs is reduced (at the protein level) during hTEC wound healing, thereby contributing to the extinction of CLU gene expression during that process. The results of this study contribute to a better understanding of the molecular mechanisms accounting for the repression of CLU gene expression during corneal wound healing.

Arginine methylation and ubiquitylation crosstalk controls DNA end-resection and homologous recombination repair

Cross-talk between distinct protein post-translational modifications is critical for an effective DNA damage response. Arginine methylation plays an important role in maintaining genome stability, but how this modification integrates with other enzymatic activities is largely unknown. Here, we identify the deubiquitylating enzyme USP11 as a previously uncharacterised PRMT1 substrate, and demonstrate that the methylation of USP11 promotes DNA end-resection and the repair of DNA double strand breaks (DSB) by homologous recombination (HR), an event that is independent from another USP11-HR activity, the deubiquitylation of PALB2. We also show that PRMT1 is a ubiquitylated protein that it is targeted for deubiquitylation by USP11, which regulates the ability of PRMT1 to bind to and methylate MRE11. Taken together, our findings reveal a specific role for USP11 during the early stages of DSB repair, which is mediated through its ability to regulate the activity of the PRMT1-MRE11 pathway.

Structure, Activity, and Function of PRMT1

PRMT1, the major protein arginine methyltransferase in mammals, catalyzes monomethylation and asymmetric dimethylation of arginine side chains in proteins. Initially described as a regulator of chromatin dynamics through the methylation of histone H4 at arginine 3 (H4R3), numerous non-histone substrates have since been identified. The variety of these substrates underlines the essential role played by PRMT1 in a large number of biological processes such as transcriptional regulation, signal transduction or DNA repair. This review will provide an overview of the structural, biochemical and cellular features of PRMT1. After a description of the genomic organization and protein structure of PRMT1, special consideration was given to the regulation of PRMT1 enzymatic activity. Finally, we discuss the involvement of PRMT1 in embryonic development, DNA damage repair, as well as its participation in the initiation and progression of several types of cancers.

ZNF213 negatively controls triple negative breast cancer progression via Hippo/YAP signaling

Breast cancer is one of the most commonly diagnosed malignancies worldwide, while the triple negative breast cancer (TNBC) is the most aggressive and virulent subtype in breast cancers. Compared with luminal type breast cancers, which could be well controlled by endocrine treatment, TNBC is worse in prognosis and lack of effective targeted therapy. Thus, it would be interesting and meaningful to identify novel therapeutic targets for TNBC treatments. Recent genomic data showed the activation of Hippo/YAP signaling in TNBC, indicating its critical roles in TNBC carcinogenesis and cancer progression. Hippo/YAP signaling could subject to several kinds of protein modifications, including ubiquitination and phosphorylation. Quite a few studies have demonstrated these modifications, which controlled YAP protein stability and turnover, played critical role in Hippo signaling activation In our current study, we identified ZNF213 as a negative modifier for Hippo/YAP axis. ZNF213 depletion promoted TNBC cell migration and invasion, which could be rescued by further YAP silencing. ZNF213 knocking down facilitated YAP protein stability and Hippo target gene expression, including CTGF and CYR61. Further mechanism studies demonstrated that ZNF213 associated with YAP and facilitated YAP K48-linked poly-ubiquitination at several YAP lysine sites (K252, K254, K321 and K497). Besides, the clinical data showed that ZNF213 negatively correlated with YAP protein level and Hippo target gene expression in TNBC samples. ZNF213 expression correlated with good prognosis in TNBC patients. Our data provided novel insights in YAP proteolytic regulation and TNBC progression.

DNA or Protein Methylation-Dependent Regulation of Activator Protein-1 Function

Epigenetic regulation and modification govern the transcriptional mechanisms that promote disease initiation and progression, but can also control the oncogenic processes, cell signaling networks, immunogenicity, and immune cells involved in anti-inflammatory and anti-tumor responses. The study of epigenetic mechanisms could have important implications for the development of potential anti-inflammatory treatments and anti-cancer immunotherapies. In this review, we have described the key role of epigenetic progression: DNA methylation, histone methylation or modification, and protein methylation, with an emphasis on the activator protein-1 (AP-1) signaling pathway. Transcription factor AP-1 regulates multiple genes and is involved in diverse cellular processes, including survival, differentiation, apoptosis, and development. Here, the AP-1 regulatory mechanism by DNA, histone, or protein methylation was also reviewed. Various methyltransferases activate or suppress AP-1 activities in diverse ways. We summarize the current studies on epigenetic alterations, which regulate AP-1 signaling during inflammation, cancer, and autoimmune diseases, and discuss the epigenetic mechanisms involved in the regulation of AP-1 signaling.

RING finger protein 187 as a novel potential biomarker for predicting the prognosis of ovarian carcinoma in 2 cancer centers

RING finger protein 187 (RNF187) has been used to predict prognosis of several human carcinomas. However, the clinicopathologic and prognostic implication of RNF187 expression in ovarian carcinomas remains not to be evaluated. The aim of this study was to explore the clinicopathologic and the prognostic significance of RNF187 in patients with ovarian carcinomas. Expression levels of RNF187 protein were investigated by immunohistochemical staining based on tissue-microarray composed of 147 patients with ovarian carcinomas. Receiver operating characteristic curve analysis was used to select the ideal cut-off value of RNF187 expression in ovarian carcinoma, and then analyze the correlation between the status of RNF187 expression and various clinicopathologic variables by chi-square test. Univariate analysis was employed to investigate the association between clinicopathologic variables and prognosis of patients by Kaplan-Meier method. Multivariate analysis was performed to identify the independent prognostic factors by the Cox regression model. Our results demonstrated that high expression of RNF187 was significantly associated with late FIGO stage, high histologic grade and pN1 stage in ovarian carcinoma (P < 0.05). Univariate analysis uncovered patients with the high expression of RNF187 have the worse overall survival and disease-free survival (P < 0.05). More surprisingly, multivariate analysis determined that the RNF187 expression was served as an independent prognostic factor in ovarian carcinoma. The high expression of RNF187 might influence a more aggressive biological behavior in ovarian carcinoma. Therefore, RNF187 expression could be useful to act as a new independent prognostic biomarker for patients with ovarian carcinoma.

RACO-1 modulates Hippo signalling in oesophageal squamous cell carcinoma

Oesophageal cancer is one of the most lethal malignancies worldwide, whereas the 5-year survival is less than 20%. Although the detailed carcinogenic mechanisms are not totally clear, recent genomic sequencing data showed dysregulation of Hippo signalling could be a critical factor for oesophageal squamous cell carcinoma (ESCC) progression. Therefore, understanding of the molecular mechanisms that control Hippo signalling activity is of great importance to improve ESCC diagnostics and therapeutics. Our current study revealed RACO-1 as an inhibitory protein for YAP/TEAD axis. Depletion of RACO-1 increases the protein level of YAP and expression of YAP/TEAD target gene. Besides, RACO-1 silencing could promote ESCC cell invasion and migration, which effect could be rescued by YAP depletion in ESCC cells. Immunoprecipitation showed that RACO-1 associated with YAP and promote ubiquitination and degradation of YAP at k48 poly-ubiquitination site. Our research discovered a new regulator of Hippo signalling via modulating YAP stability. RACO-1 could be a promising factor, which serves cancer diagnostics and therapeutics in ESCC patients.

Methylation of EZH2 by PRMT1 regulates its stability and promotes breast cancer metastasis

Enhancer of zeste homolog 2 (EZH2), a key histone methyltransferase and EMT inducer, is overexpressed in diverse carcinomas, including breast cancer. However, the molecular mechanisms of EZH2 dysregulation in cancers are still largely unknown. Here, we discover that EZH2 is asymmetrically dimethylated at R342 (meR342-EZH2) by PRMT1. meR342-EZH2 was found to inhibit the CDK1-mediated phosphorylation of EZH2 at T345 and T487, thereby attenuating EZH2 ubiquitylation mediated by the E3 ligase TRAF6. We also demonstrate that meR342-EZH2 resulted in a decrease in EZH2 target gene expression, but an increase in breast cancer cell EMT, invasion and metastasis. Moreover, we confirm the positive correlations among PRMT1, meR342-EZH2 and EZH2 expression in the breast cancer tissues. Finally, we report that high expression levels of meR342-EZH2 predict a poor clinical outcome in breast cancer patients. Our findings may provide a novel diagnostic target and promising therapeutic target for breast cancer metastasis.

Protein Arginine Methyltransferase 1 (PRMT1) Selective Inhibitor, TC-E 5003, Has Anti-Inflammatory Properties in TLR4 Signaling

Protein arginine methyltransferase 1 (PRMT1) is the most predominant PRMT and is type I, meaning it generates monomethylarginine and asymmetric dimethylarginine. PRMT1 has functions in oxidative stress, inflammation and cancers, and modulates diverse diseases; consequently, numerous trials to develop PRMT1 inhibitors have been attempted. One selective PRMT1 inhibitor is N,N′-(Sulfonyldi-4,1-phenylene)bis(2-chloroacetamide), also named TC-E 5003 (TC-E). In this study, we investigated whether TC-E regulated inflammatory responses. Nitric oxide (NO) production was evaluated by the Griess assay and the inflammatory gene expression was determined by conducting RT-PCR. Western blot analyzing was carried out for inflammatory signaling exploration. TC-E dramatically reduced lipopolysaccharide (LPS)-induced NO production and the expression of inflammatory genes (inducible NO synthase (iNOS), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α and interleukin (IL)-6) as determined using RT-PCR. TC-E downregulated the nuclear translocation of the nuclear factor (NF)-κB subunits p65 and p50 and the activator protein (AP)-1 transcriptional factor c-Jun. Additionally, TC-E directly regulated c-Jun gene expression following LPS treatment. In NF-κB signaling, the activation of IκBα and Src was attenuated by TC-E. Taken together, these data show that TC-E modulates the lipopolysaccharide (LPS)-induced AP-1 and NF-κB signaling pathways and could possibly be further developed as an anti-inflammatory compound.

Regulation of Hippo signaling and triple negative breast cancer progression by an ubiquitin ligase RNF187

Breast cancer is the most common malignancy for women worldwide, while Triple Negative Breast Cancer (TNBC) accounts for 20% in all patients. Compared with estrogen receptor positive breast cancer, which could be effectively controlled via endocrine therapy, TNBC is more aggressive and worse in prognosis. It is therefore urgent and necessary to develop a novel therapeutic strategy for TNBC treatment. Recent studies identified Hippo signaling is highly activated in TNBC, which could be a driving pathway for TNBC progression. In our study, we determine RNF187 as a negative regulator for Hippo signaling activation. RNF187 depletion significantly decreases cell migration and invasion capacity in TNBC. These effects could be rescued by further YAP depletion. Depletion of RNF187 increases the YAP protein level and Hippo signaling target genes, such as CTGF and CYR61 in TNBC. Immuno-precipitation assay shows that RNF187 associates with YAP, promoting its degradation possibly via inducing YAP K48-dependent poly-ubiquitination. Interestingly, Our clinical data reveals that RNF187 reversely correlates with YAP protein level and Hippo target genes. RNF187 tends to correlate with good prognosis in TNBC patients. Our study provides evidence to establish a proteolytic mechanism in regulation Hippo signaling activation in TNBC.

c-Jun Overexpression Accelerates Wound Healing in Diabetic Rats by Human Umbilical Cord-Derived Mesenchymal Stem Cells

Objective

Mesenchymal stem cells (MSCs) are considered a promising therapy for wound healing. Here, we explored the role of c-Jun in diabetic wound healing using human umbilical cord-derived MSCs (hUC-MSCs).

Methods

Freshly isolated hUC-MSCs were subjected to extensive in vitro subcultivation. The cell proliferative and migratory capacities were assessed by the Cell Counting Kit-8 and scratch assays, respectively. c-Jun expression was evaluated by RT-PCR and western blot analysis. The function of c-Jun was investigated with lentivirus transduction-based gene silencing and overexpression. Diabetes mellitus was induced in SD rats on a high-glucose/fat diet by streptozocin administration. Wounds were created on the dorsal skin. The effects of c-Jun silencing and overexpression on wound closure by hUC-MSCs were examined. Reepithelialization and angiogenesis were assessed by histological and immunohistochemical analysis, respectively. Platelet-derived growth factor A (PDGFA), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF) levels were determined by western blot analysis.

Results

hUC-MSCs showed gradually decreased cell proliferation, migration, and c-Jun expression during subcultivation. c-Jun silencing inhibited cell proliferation and migration, while c-Jun overexpression enhanced proliferation but not migration. Compared with untransduced hUC-MSCs, local subcutaneous injection of c-Jun-overexpressing hUC-MSCs accelerated wound closure, enhanced angiogenesis and reepithelialization at the wound bed, and increased PDGFA and HGF levels in wound tissues.

Conclusion

c-Jun overexpression promoted hUC-MSC proliferation and migration in vitro and accelerated diabetic wound closure, reepithelization, and angiogenesis by hUC-MSCs in vivo. These beneficial effects of c-Jun overexpression in diabetic wound healing by hUC-MSCs were at least partially mediated by increased PDGFA and HGF levels in wound tissues.

High level of RNF187 contributes to the progression and drug resistance of osteosarcoma

Objectives: Ring finger protein 187 (RNF187) was recently demonstrated to be up-regulation and function as a promoter in multiple cancers. However, the roles of RNF187 in osteosarcoma (OS) are unclear. Here, we tried to reveal the clinicopathological and biological roles of RNF187 in OS. Materials and Methods: We employed the quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) to determine the expression of RNF187 in OS tissues and cells. Migration and invasion capacities were analyzed by wound healing and transwell assays, and colony formation and CCK8 assays were performed to investigate proliferative ability. The functional effects of RNF187 on OS drugs resistance were further determined by CCK8 and western blot assays. Then, the relationship between RNF187 expression and clinical implications was analyzed by tissue microarrays (TMAs) including 51 OS cases. Moreover, the prognostic value was also determined by Kaplan-Meier analysis. Results: We reported that RNF187 mRNA was significantly increased in OS tissues compared to matched nontumorous tissues (3.83 ±0.79 vs. 1.70 ± 0.63), which was in line with the IHC assay in TMAs. By RNA interference and cDNA transfection, we showed high level of RNF187 increased the migration, invasion and proliferation of OS cells. Moreover, we demonstrated that elevated RNF187 expression induced OS cell drugs resistance, activated the ERK1/2 molecular and markedly enhanced the BCL-2 expression. Clinically, OS patients with high level of RNF187 was associated with Histologic differentiation (p=0.001), an advanced Enneking stage (p=0.001), response to chemotherapy (p=0.004), and metastasis (p= 0.001). Clinically, our data displayed that the RNF187 overexpression in OS samples associated with shorten overall survival (p=0.001) and high tumor recurrence (p=0.001) in postoperative OS patients. Conclusions: Our results indicate that Elevated RNF187 expression is a new adverse outcomes marker for OS patients and may be used as a new therapeutic target of OS.

Virtual Screening with a Structure-Based Pharmacophore Model to Identify Small-Molecule Inhibitors of CARM1

CARM1 (coactivator-associated arginine methyltransferase 1), also known as PRMT4 (protein arginine N-methyltransferase 4), belongs to the protein arginine methyltransferase (PRMT) family, which has emerged as a potential anticancer drug target. To discover new CARM1 inhibitors, we performed virtual screening against the substrate-binding site in CARM1. Structure-based pharmacophore models, which were generated according to three druggable subpockets embedding critical residues for ligand binding, were applied for virtual screening. The importance of the solvent-exposed substrate-binding cavity was highlighted due to significant hydrophobicity. Aided by molecular docking, 15 compounds structurally distinct from known CARM1 inhibitors were selected to evaluate their inhibitory effects on CARM1 methyltransferase activity, which resulted in seven compounds exhibiting micromolar inhibition, with selectivity over other members in the PRMT protein family. Moreover, three of them exhibited potent antiproliferation activities in breast cancer cells. Particularly, compound NO.2 exhibited potent activity both in vitro and in cultured cells, which will serve as a leading hit for developing CARM1 inhibitors with improved efficacy. The virtual screening strategy in this study will be applicable for the discovery of substrate-competitive inhibitors targeting other members in the PRMT protein family.

Overexpression of RNF187 induces cell EMT and apoptosis resistance in NSCLC

Overexpression of RING finger protein 187 (RNF187) was recently revealed to be a driver of several cancers. However, the expression and function of RNF187 in non-small-cell lung cancer (NSCLC) are still unknown. Here, we uncovered that RNF187 expression was significantly higher in NSCLC samples than in matched normal lung samples at both the messenger RNA (3.55 ± 0.79 vs. 1.74 ± 0.63) and protein (2.85 ± 0.14 vs. 1.24 ± 0.02) levels. By downregulating or upregulating RNF187 expression in NSCLC cells, we showed that elevated RNF187 expression distinctly enhanced the migration, invasion, and colony formation of NSCLC cells. Moreover, we revealed that high level of RNF187 promoted NSCLC progression by inducing cell epithelial to mesenchymal transition (EMT) and apoptosis resistance mainly via activating the mitogen-activated protein kinase and PI3K signaling. Clinically, we demonstrated that RNF187 expression was positively associated with advanced TNM stage (p = 1.29 × 10 ^-6 ), lymph node metastasis ( p = 2.69 × 10 ^-9 ), and large tumor size ( p = 0.002). Importantly, NSCLC patients with elevated RNF187 expression related to the short overall survival rate( p = 1.29, E-7) and could serve as an independent prognostic factor in NSCLC patients. Thus, elevated RNF187 expression promotes NSCLC development by inducing cell EMT and apoptosis resistance, and RNF187 may be a novel prognostic indicator for NSCLC patients after curative resection.

Up-regulation of RNF187 induces hepatocellular carcinoma cell epithelial to mesenchymal transitions

Ring finger protein 187 (RNF187) has been identified to be a co-activator linking c Jun to Ras signaling. However, the expression and function of RNF187 in hepatocellular carcinomas (HCC) remains unclear. Here, we tried to determine the expression and roles of RNF187 in hepatocellular carcinomas (HCC).The expression of RNF187 was determined in HCC tissues and cell lines, and we found that RNF187 expressed highly in HCC tissues compared with the corresponding adjacent liver tissues both in mRNA and protein level, which was consistent with the result of immunohistochemistry on HCC tissue microarrays. In HCC cell lines, the level of RNF187 was positively associated with the HCC cells metastatic potential. By the RNF187 interference and cDNA transfection, we showed that the high level of RNF187 induced the HCC cells invasion and metastasis both in vitro and in vivo, as well as the high ability of colony formation.Mechanistically, we detected the high level of RNF187 promoted cell scatter by inducing epithelial-mesenchymal transition (EMT). Clinically, the high level of RNA187 was significantly correlated with a malignant phenotype, including larger tumor size, multiple tumors, and microvascular invasion. Importantly, high level of RNF187 correlated with HCC patients' shorter OS and lower disease free survival rates than those with low level of RNF187. Our results revealed that elevated expression of RNF187 induced hepatocellular carcinoma cell epithelial to mesenchymal transitions, and represented a novel marker for predicting the poor prognosis of HCC.

Methylation of the phosphatase-transcription activator EYA1 by protein arginine methyltransferase 1: mechanistic, functional, and structural studies

The eyes absent (EYA) family proteins are conserved transcriptional coactivators with intrinsic protein phosphatase activity. They play an essential role in the development of various organs in metazoans. These functions are associated with a unique combination of phosphatase and transactivation activities. However, it remains poorly understood how these activities and the consequent biologic functions of EYA are regulated. Here, we demonstrate that 2 conserved arginine residues, R304 and R306, of EYA1 are essential for its in vitro phosphatase activity and in vivo function during Drosophila eye development. EYA1 physically interacts with protein arginine methyltransferase 1, which methylates EYA1 at these residues both in vitro and in cultured mammalian and insect cells. Moreover, we show that wild-type, but not methylation-defective, EYA1 associates with γ-H2A.X in response to ionizing radiation. Taken together, our results identify the conserved arginine residues of EYA1 that play an important role for its activity, thus implicating arginine methylation as a novel regulatory mechanism of EYA function.-Li, X., Eberhardt, A., Hansen, J. N., Bohmann, D., Li, H., Schor, N. F. Methylation of the phosphatase-transcription activator EYA1 by protein arginine methyltransferase 1: mechanistic, functional, and structural studies.

Prognostic value of increased expression of RACO-1 in patients with hepatitis B-related hepatocellular carcinoma

RING domain AP-1 coactivator-1 (RACO-1) is a coactivator that links c-Jun to growth factor signaling and is essential for AP-1 function. This study aimed to investigate the expression and clinical significance of RACO-1 protein in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in China. A total of 136 tissue samples of HBV-related HCC were detected by immunohistochemistry (including 76 patients in training cohort and 60 patients in validation cohort). Correlation between RACO-1 expression and clinicopathologic features of HBV-related HCC was analyzed in both the cohorts. RACO-1 expression was significantly higher in HBV-related HCC tissues than in adjacent non-tumor liver tissues. All the patients were divided into two groups: the low expression group and the high expression group. RACO-1 expression was significantly related to vascular invasion (P=0.021), tumor numbers (P=0.046), International Union for Cancer Control/American Joint Committee on Cancer stage (P=0.006), cirrhosis (P=0.046), capsular (P=0.039), and Barcelona Clinic Liver Cancer stage (P=0.041) in training cohort. The validation cohort showed the same results. The high RACO-1 expression was the independent prognostic factor for HBV-related HCC patients in both training cohort and validation cohort. Our data implicate RACO-1 as a novel prognostic marker and a potential therapeutic target for HBV-related HCC.

TGF-β1 Upregulates the Expression of Triggering Receptor Expressed on Myeloid Cells 1 in Murine Lungs

Triggering receptor expressed on myeloid cells 1 (TREM-1) increases the expression of TGF-β family genes, which are known as profibrogenic cytokines in the pathogenesis of pulmonary fibrosis. In this study, we determined whether TGF-β1 regulated the expression of TREM-1 in a mouse model of pulmonary fibrosis. The expression of TGF-β1 and TREM-1 was increased on day 7, 14, and 21 after single intratracheal injection of bleomycin (BLM). And there was positive correlation between the expression of TGF-β1 and TREM-1. TGF-β1 increased expression of TREM-1 mRNA and protein in a time- and dose-dependent manner in mouse macrophages. The expression of the activator protein 1 (AP-1) was increased in lung tissues from mouse after BLM injection and in mouse macrophages after TGF-β1 treatment, respectively. TGF-β1 significantly increased the relative activity of luciferase in the cells transfected with plasmid contenting wild type-promoter of TREM-1. But TGF-β1 had no effect on the activity of luciferase in the cells transfected with a mutant-TREM1 plasmid carrying mutations in the AP-1 promoter binding site. In conclusion, we found the expression of TREM-1 was increased in lung tissues from mice with pulmonary fibrosis. TGF-β1 increased the expression of TREM-1 in mouse macrophages partly via the transcription factor AP-1.

Genome-wide studies identify a novel interplay between AML1 and AML1/ETO in t(8;21) acute myeloid leukemia

The AML1/ETO fusion protein is essential to the development of t(8;21) acute myeloid leukemia (AML) and is well recognized for its dominant-negative effect on the coexisting wild-type protein AML1. However, the genome-wide interplay between AML1/ETO and wild-type AML1 remains elusive in the leukemogenesis of t(8;21) AML. Through chromatin immunoprecipitation sequencing and computational analysis, followed by a series of experimental validations, we report here that wild-type AML1 is able to orchestrate the expression of AML1/ETO targets regardless of being activated or repressed; this is achieved via forming a complex with AML1/ETO and via recruiting the cofactor AP-1 on chromatin. On chromatin occupancy, AML1/ETO and wild-type AML1 largely overlap and preferentially bind to adjacent and distinct short and long AML1 motifs on the colocalized regions, respectively. On physical interaction, AML1/ETO can form a complex with wild-type AML1 on chromatin, and the runt homology domain of both proteins are responsible for their interactions. More importantly, the relative binding signals of AML1 and AML1/ETO on chromatin determine which genes are repressed or activated by AML1/ETO. Further analysis of coregulators indicates that AML1/ETO transactivates gene expression through recruiting AP-1 to the AML1/ETO-AML1 complex. These findings enrich our knowledge of understanding the significance of the interplay between the wild-type protein and the oncogenic fusion protein in the development of leukemia.

Post-translational control of transcription factors: methylation ranks highly

Methylation of lysine and arginine residues on histones has long been known to determine both chromatin structure and gene expression. In recent years, the methylation of non-histone proteins has emerged as a prevalent modification which impacts on diverse processes such as cell cycle control, DNA repair, senescence, differentiation, apoptosis and tumourigenesis. Many of these non-histone targets represent transcription factors, cell signalling molecules and tumour suppressor proteins. Evidence now suggests that the dysregulation of methyltransferases, demethylases and reader proteins is involved in the development of many diseases, including cancer, and several of these proteins represent potential therapeutic targets for small molecule compounds, fuelling a recent surge in chemical inhibitor design. Such molecules will greatly help us to understand the role of methylation in both health and disease.

Protein arginine methyltransferase 1 promoted the growth and migration of cancer cells in esophageal squamous cell carcinoma

Dysregulation of protein arginine methyltransferase 1 (PRMT1) has been reported in several cancer types. However, its expression pattern and biological functions in esophageal squamous cell carcinoma (ESCC) remained unknown. Here, we have found that the expression of PRMT1 was up-regulated in ESCC samples. In the biological function studies, forced expression of PRMT1 promoted the growth and migration of ESCC cells. However, knocking down the expression of PRMT1 inhibited the growth, migration, and metastasis of ESCC cells. Moreover, PRMT1 activated Hedgehog signaling and up-regulated the expression of target genes downstream of Hedgehog signaling. Taken together, our study revealed the oncogenic roles of PRMT1 in the progression of ESCC, and PRMT1 might be a promising therapeutic target for the treatment of ESCC.

The E3 ubiquitin ligase Trim7 mediates c-Jun/AP-1 activation by Ras signalling

The c-Jun/AP-1 transcription factor controls key cellular behaviours, including proliferation and apoptosis, in response to JNK and Ras/MAPK signalling. While the JNK pathway has been well characterized, the mechanism of activation by Ras was elusive. Here we identify the uncharacterized ubiquitin ligase Trim7 as a critical component of AP-1 activation via Ras. We found that MSK1 directly phosphorylates Trim7 in response to direct activation by the Ras-Raf-MEK-ERK pathway, and this modification stimulates Trim7 E3 ubiquitin ligase activity. Trim7 mediates Lys63-linked ubiquitination of the AP-1 co-activator RACO-1, leading to RACO-1 protein stabilization. Consequently, Trim7 depletion reduces RACO-1 levels and AP-1-dependent gene expression. Moreover, transgenic overexpression of Trim7 increases lung tumour burden in a Ras-driven cancer model, and knockdown of Trim7 in established xenografts reduces tumour growth. Thus, phosphorylation-ubiquitination crosstalk between MSK1, Trim7 and RACO-1 completes the long sought-after mechanism linking growth factor signalling and AP-1 activation.

The RNA-binding protein RBPMS1 represses AP-1 signaling and regulates breast cancer cell proliferation and migration

The activator protein-1 (AP-1) transcription factor complex plays a crucial role in tumor growth and progression. However, how AP-1 transcriptional activity is repressed is not fully understood. Here, we show that RNA-binding protein with multiple splicing 1 (RBPMS1) physically and functionally interacts with AP-1 in vitro and in vivo. The RNA-recognition motif (RRM) and C-terminus of the RBPMS1 isoforms RBPMS1A and RBPMS1C, but not RBPMS1B, interacted with cFos, a member of the AP-1 family that dimerizes with cJun to stimulate AP-1 transcriptional activity. RBPMS1 did not associate with Jun proteins. RBPMS1A and RBPMS1C bound to the basic leucine zipper (bZIP) domain of cFos that mediates dimerization of AP-1 proteins. In addition, RBPMS1A-C interacted with the transcription factor Smad3, which was shown to interact with cJun and increase AP-1 transcriptional activity. RBPMS1 inhibited c-Fos or Smad3-mediated AP-1 transactivation and the expression of AP-1 target genes known to be the key regulators of cancer growth and progression, including vascular endothelial growth factor (VEGF) and cyclin D1. Mechanistically, RBPMS1 blocks the formation of the cFos/cJun or Smad3/cJun complex as well as the recruitment of cFos or Smad3 to the promoters of AP-1 target genes. In cultured cells and a mouse xenograft model, RBPMS1 inhibited the growth and migration of breast cancer cells through c-Fos or Smad3. These data suggest that RBPMS1 is a critical repressor of AP-1 signaling and RBPMS1 activation may be a useful strategy for cancer treatment.