UHRF1 promotes cell growth and metastasis through repression of p16(ink⁴a) in colorectal cancer

Identification and functional regulation of two alternative splicing isoforms of the Uhrf2 gene in Miichthysmiiuy

Alternative splicing can produce a variety of splicing isoforms to increase protein diversity, participate in the regulation of gene expression and the occurrence and development of diseases, and thus play an important role in innate immunity. Ubiquitin like with PHD and ring finger domains 2 (Uhrf2) protein is associated with cell proliferation, inflammation, tumors, and cancer, and is currently the focus of medical immunology research, but there is little research on alternative splicing of the Uhrf2 gene. In this study, we identified two different splicing isoforms of Uhrf2 in Miichthys miiuy through Sanger sequencing, dual-luciferase reporter gene assay, qRT-PCR, subcellular localization experiments, and named them Uhrf2-α and Uhrf2-β. Subcellular localization experiments found that Uhrf2-α was mainly located in the nucleus, while Uhrf2-β was mainly located in the cytoplasm. Although their localization was different, both could significantly inhibit the activation of IRF3 and NF-κB signaling pathways, and effectively inhibit the levels of inflammatory cytokines. These results indicate that Uhrf2-α and Uhrf2-β play important negative regulatory roles in innate immune responses in fish.

Aberrant cytoplasmic expression of UHRF1 restrains the MHC-I-mediated anti-tumor immune response

Immunotherapy successfully complements traditional cancer treatment. However, primary and acquired resistance might limit efficacy. Reduced antigen presentation by MHC-I has been identified as potential resistance factor. Here we show that the epigenetic regulator ubiquitin-like with PHD and ring finger domains 1 (UHRF1), exhibits altered expression and aberrant cytosolic localization in cancerous tissues, where it promotes MHC-I ubiquitination and degradation. Cytoplasmic translocation of UHRF1 is induced by its phosphorylation on a specific serine in response to signals provided by factors present in the tumor microenvironment (TME), such as TGF-β, enabling UHRF1 to bind MHC-I. Downregulation of MHC-I results in suppression of the antigen presentation pathway to establish an immune hostile TME. UHRF1 inactivation by genetic deletion synergizes with immune checkpoint blockade (ICB) treatment and induces an anti-tumour memory response by evoking low-affinity T cells. Our study adds to the understanding of UHRF1 in cancer immune evasion and provides a potential target to synergize with immunotherapy and overcome immunotherapeutic resistance.

Cell autonomous functions of CD47 in regulating cellular plasticity and metabolic plasticity

CD47 is a ubiquitously expressed cell surface receptor, which is widely known for preventing macrophage-mediated phagocytosis by interacting with signal regulatory protein α (SIRPα) on the surface of macrophages. In addition to its role in phagocytosis, emerging studies have reported numerous noncanonical functions of CD47 that include regulation of various cellular processes such as proliferation, migration, apoptosis, differentiation, stress responses, and metabolism. Despite lacking an extensive cytoplasmic signaling domain, CD47 binds to several cytoplasmic proteins, particularly upon engaging with its secreted matricellular ligand, thrombospondin 1. Indeed, the regulatory functions of CD47 are greatly influenced by its interacting partners. These interactions are often cell- and context-specific, adding a further level of complexity. This review addresses the downstream cell-intrinsic signaling pathways regulated by CD47 in various cell types and environments. Some of the key pathways modulated by this receptor include the PI3K/AKT, MAPK/ERK, and nitric oxide signaling pathways, as well as those implicated in glucose, lipid, and mitochondrial metabolism. These pathways play vital roles in maintaining tissue homeostasis, highlighting the importance of understanding the phagocytosis-independent functions of CD47. Given that CD47 expression is dysregulated in a variety of cancers, improving our understanding of the cell-intrinsic signals regulated by this molecule will help advance the development of CD47-targeted therapies.

UHRF1-mediated ubiquitination of nonhomologous end joining factor XLF promotes DNA repair in human tumor cells

UHRF1 (Ubiquitin-like with PHD and Ring Finger domains 1) is a crucial E3 ubiquitin ligase and epigenetic regulator with pivotal roles in various biological processes, including the maintenance of DNA methylation, regulation of gene expression, and facilitation of DNA damage repair. In this study, we unveil that UHRF1 interacts with the nonhomologous end joining factor XLF (also known as Cernunnos) following DNA double strand breaks in HeLa cells. Furthermore, we demonstrate that UHRF1 catalyzes lysine 63-linked polyubiquitination of XLF, rather than lysine 48-linked polyubiquitination. Notably, this polyubiquitination of XLF by UHRF1 does not affect its protein stability; instead, it enhances the recruitment of XLF to the sites of DNA damage. These findings shed light on the role of UHRF1 as a novel regulator of DNA repair through XLF in tumor cells.

Oncogenic Roles of UHRF1 in Cancer

Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is an essential protein involved in the maintenance of repressive epigenetic marks, ensuring epigenetic stability and fidelity. As an epigenetic regulator, UHRF1 comprises several functional domains (UBL, TTD, PHD, SRA, RING) that are collectively responsible for processes like DNA methylation, histone modification, and DNA repair. UHRF1 is a downstream effector of the RB/E2F pathway, which is nearly universally deregulated in cancer. Under physiological conditions, UHRF1 protein levels are cell cycle-dependent and are post-translationally regulated by proteasomal degradation. Conversely, UHRF1 is overexpressed and serves as an oncogenic driver in multiple cancers. This review focuses on the functional domains of UHRF1, highlighting its key interacting proteins and oncogenic roles in solid tumors including retinoblastoma, osteosarcoma, lung cancer, and breast cancer. Additionally, current therapeutic strategies targeting UHRF1 domains or its interactors are explored, providing an insight on potential clinical applications.

The expression and clinical significance of UHRF1 in soft tissue sarcomas and its prognostic value

To explore the expression and prognostic value of UHRF1 gene in soft tissue sarcoma (STS) and its related molecular mechanism. The expression data and clinicopathological parameters of STS were downloaded from the Cancer Genome Atlas (TCGA). The expression level of UHRF1 in STS and adjacent tissues and its relationship with clinicopathological characteristics were analyzed. The expression level of UHRF1 in STS tissues was significantly higher than that in paracancerous tissues (P < .001), and the overall survival (OS) time of patients with high UHRF1 expression was significantly shorter than that of patients with low UHRF1 expression (P = .002). The expression of UHRF1 was correlated with tumor necrosis, histological type and metastasis, and the differences were statistically significant (P = .013; P = .001; P = .002). The area ratio under receiver operating characteristic (ROC) curve between STS tissue and adjacent tissue of UHRF1 expression was 0.994. Number of tumors (HR = 0.416, 95%CI = 0.260-0.666, P < .001), depth of tumor (HR = 2.888, 95%CI = 0.910-9.168, P = .033), metastasis (HR = 2.888, 95% CI = 1.762-4.732, P < .001), residual tumor (HR = 2.637, 95% CI = 1.721-4.038, P < .001) and UHRF1 expression (HR = 1.342, 95% CI = 1.105-1.630, P = .003) were significantly associated with OS, and high expression of UHRF1 (HR = 1.387, 95%CI = 1.008-1.907, P = .044) was an independent risk factor for the prognosis of STS patients. The results of the nomogram exhibited that UHRF1 expression level had a significant effect on the total score value. GSEA enrichment analysis suggested that UHRF1 was involved in 14 signaling pathways regulating mRNA spliceosome, cell cycle, P53 signaling pathway were identified. Single sample gene set enrichment analysis (ssGSEA) exhibited that the expression of UHRF1 in STS was positively correlated with the level of Th2 cell infiltration, and negatively correlated with plasmacytoid dendritic cells (pDC), natural killer cells (NK), Eosinophils, Mast cells, etc. UHRF1 expression is involved in the immune microenvironment of HCC and affects the occurrence and development of HCC. UHRF1 is highly expressed in STS tissues. It is involved in the regulation of multiple tumor-related signaling pathways and immune cell microenvironment, suggesting that UHRF1 may be a potential molecular marker for prognosis prediction and targeted therapy of STS patients.

UHRF1 poly-auto-ubiquitination induced by the anti-cancer drug, thymoquinone, is involved in the DNA repair machinery recruitment

DNA methylation is one of the most important epigenetic mark involved in many physiologic cellular processes and pathologies. During mitosis, the transmission of DNA methylation patterns from a mother to the daughter cells is ensured through the action of the Ubiquitin-like, containing PHD and RING domains, 1/DNA methyltransferase 1 (UHRF1/DNMT1) tandem. UHRF1 is involved in the silencing of many tumor suppressor genes (TSGs) via mechanisms that remain largely to be deciphered. The present study investigated the role and the regulation of UHRF1 poly-ubiquitination induced by thymoquinone, a natural anti-cancer drug, known to enhance or re-activate the expression of TSGs. We found that the auto-ubiquitination of UHRF1, induced by TQ, is mediated by reactive oxygen species, and occurs following DNA damage. We demonstrated that the poly-ubiquitinated form of UHRF1 is K63-linked and can still silence the tumor suppressor gene p16INK4A/CDKN2A. We further showed that TQ-induced auto-ubiquitination is mediated via the activity of Tip60. Since this latter is known as a nuclear receptor co-factor, we investigated if the glucocorticoid receptor (GR) might be involved in the regulation of UHRF1 ubiquitination. Activation of the GR, with dexamethasone, did not influence auto-ubiquitination of UHRF1. However, we could observe that TQ induced a K48-linked poly-ubiquitination of GR, probably involved in the proteosomal degradation pathway. Mass-spectrometry analysis of FLAG-HA-tagged UHRF1 identified UHRF1 partners involved in DNA repair and showed that TQ increased their association with UHRF1, suggesting that poly-ubiquitination of UHRF1 is involved in the DNA repair process. We propose that poly-ubiquitination of UHRF1 serves as a scaffold to recruit the DNA repair machinery at DNA damage sites.

Highlighting functions of apoptosis and circular RNAs in colorectal cancer

Colorectal cancer (CRC) is known as one of the global problems that endangers the lives of thousands of people every year. Various treatments have been used to deal with this disease, but in some cases, they are not effective. Circular RNAs, as a novel class of noncoding RNAs, have different expression levels and various functions in cancer cells, such as gene regulation through microRNA sponging. They play an important role in various cellular processes, including differentiation, proliferation, invasion, and apoptosis. Changes in the process of apoptosis are closely related to the progression or inhibition of various malignancies. Induction of apoptosis in cancer cells is a promising target for tumor therapy. In this study, circRNAs were investigated as being central to the induction or inhibition of apoptosis in CRC. It is hoped that through targeted changes in the function of these biomolecules, better outcomes will be achieved in cancer treatment. Perhaps better outcomes for cancer treatment can be achieved by using new methods and modifying the expression of these nucleic acids. However, using this method may come with challenges and limitations.

Inhibitors of UHRF1 base flipping activity showing cytotoxicity against cancer cells

Ubiquitin-like containing PHD and RING finger domain 1 (UHRF1) is a nuclear multi-domain protein overexpressed in numerous human cancer types. We previously disclosed the anthraquinone derivative UM63 that inhibits UHRF1-SRA domain base-flipping activity, although having DNA intercalating properties. Herein, based on the UM63 structure, new UHRF1-SRA inhibitors were identified through a multidisciplinary approach, combining molecular modelling, biophysical assays, molecular and cell biology experiments. We identified AMSA2 and MPB7, that inhibit UHRF1-SRA mediated base flipping at low micromolar concentrations, but do not intercalate into DNA, which is a key advantage over UM63. These molecules prevent UHRF1/DNMT1 interaction at replication forks and decrease the overall DNA methylation in cells. Moreover, both compounds specifically induce cell death in numerous cancer cell lines, displaying marginal effect on non-cancer cells, as they preferentially affect cells with high level of UHRF1. Overall, these two compounds are promising leads for the development of anti-cancer drugs targeting UHRF1.

Novel UHRF1-MYC Axis in Acute Lymphoblastic Leukemia

Ubiquitin-like, containing PHD and RING finger domain, (UHRF) family members are overexpressed putative oncogenes in several cancer types. We evaluated the protein abundance of UHRF family members in acute leukemia. A marked overexpression of UHRF1 protein was observed in ALL compared with AML. An analysis of human leukemia transcriptomic datasets revealed concordant overexpression of UHRF1 in B-Cell and T-Cell ALL compared with CLL, AML, and CML. In-vitro studies demonstrated reduced cell viability with siRNA-mediated knockdown of UHRF1 in both B-ALL and T-ALL, associated with reduced c-Myc protein expression. Mechanistic studies indicated that UHRF1 directly interacts with c-Myc, enabling ALL expansion via the CDK4/6-phosphoRb axis. Our findings highlight a previously unknown role of UHRF1 in regulating c-Myc protein expression and implicate UHRF1 as a potential therapeutic target in ALL.

UHRF1 Induces Metastasis in Thyroid Cancer

Background

Ubiquitin-like with PHD and ring-finger domain 1 (UHRF1) has been defined as an oncogene in tumor cells. However, the role of UHRF1 in mediating metastasis in thyroid cancer remains unexplored. In this study, we aimed to investigate the metastatic function and the potential mechanisms of UHRF1 in thyroid cancer.

Methods

Transwell assays were used to detect the metastatic capability of thyroid cancer. Dual-luciferase reporter assays were applied to examine the activation of transcription factors. Coimmunoprecipitation assays and immunofluorescence staining assays were used to elucidate the potential mechanisms of UHRF1 in promoting the metastasis of thyroid cancer.

Results

In this study, we found that overexpression of UHRF1 promoted the metastasis of papillary thyroid cancer cells, and suppression of UHRF1 decreased the metastasis of anaplastic thyroid cancer cells. Regarding the signaling pathway in regulating metastasis, UHRF1 directly combined and activated the transcription factor c-Jun/AP-1 in the nucleus, subsequently increasing the transcription of IL-6 and MIF.

Conclusion

Our results suggest that UHRF1 could induce the metastasis of thyroid cancer, and the potential signaling pathway might be that UHRF1 activates c-Jun/AP-1 to increase the expression of IL-6 and MIF. These findings provide a novel mechanism of UHRF1 and illustrate that UHRF1/AP-1 complex could be a potential therapeutic target for patients with thyroid cancer.

Regulation of UHRF1 acetylation by TIP60 is important for colon cancer cell proliferation

Background

Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is upregulated in colon cancer cells and associated with silencing tumor suppressor genes (TSGs) to promote colon cancer cell proliferation.

Objective

To investigate epigenetic modification of UHRF1 by TIP60. Whether UHRF1 acetylation by TIP60 can induce cell proliferation in colon cancer cells.

Methods

Acetylation sites of UHRF1 by TIP60 was predicted by ASEB (Acetylation Set Enrichment Based) method and identified by immunoprecipitation assay using anti-pan-acetyl lysine antibody and in vitro acetylation assay. Based on this method, UHRF1 acetylation-deficient mimic 4KR (K644R, K646R, K648R, K650R) mutant was generated to investigate effects of UHRF1 acetylation by TIP60. shRNA system was used to generate stable knockdown cell line of UHRF1. With transient transfection of UHRF1 WT and 4KR, the effects of UHRF1 4KR mutant on Jun dimerization protein 2 (JDP2) gene expression, cell proliferation and cell cycle were investigated by RT-qPCR and FACS analysis in shUHRF1 colon cancer cell line.

Results

Downregulation of TIP60-mediated UHRF1 acetylation is correlated with suppressed cell cycle progression. Acetylation-deficient mimic of UHRF1 showed poor cell growth through increased expression of JDP2 gene.

Conclusions

Acetylation of UHRF1 4K residues by TIP60 is important for colon cancer cell growth. Furthermore, upregulated JDP2 expression by acetylation-deficient mutant of UHRF1 might be an important epigenetic target for colon cancer cell proliferation.

The Potential Role of Nigella sativa Seed Oil as Epigenetic Therapy of Cancer

Nigella sativa oil, commonly known as black seed oil (BSO), is a well-known Mediterranean food, and its consumption is associated with beneficial effects on human health. A large number of BSO's therapeutic properties is attributed to its pharmacologically active compound, thymoquinone (TQ), which inhibits cell proliferation and induces apoptosis by targeting several epigenetic players, including the ubiquitin-like, containing plant homeodomain (PHD) and an interesting new gene, RING finger domains 1 (UHRF1), and its partners, DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1). This study was designed to compare the effects of locally sourced BSO with those of pure TQ on the expression of the epigenetic complex UHRF1/DNMT1/HDAC1 and the related events in several cancer cells. The gas chromatographs obtained from GC-MS analyses of extracted BSO showed that TQ was the major volatile compound. BSO significantly inhibited the proliferation of MCF-7, HeLa and Jurkat cells in a dose-dependent manner, and it induced apoptosis in these cell lines. BSO-induced inhibitory effects were associated with a significant decrease in mRNA expression of UHRF1, DNMT1 and HDAC1. Molecular docking and MD simulation showed that TQ had good binding affinity to UHRF1 and HDAC1. Of note, TQ formed a stable metal coordinate bond with zinc tom, found in the active site of the HDAC1 protein. These findings suggest that the use of TQ-rich BSO represents a promising strategy for epigenetic therapy for both solid and blood tumors through direct targeting of the trimeric epigenetic complex UHRF1/DNMT1/ HDAC1.

Discovery and Mechanism of Small Molecule Inhibitors Selective for the Chromatin-Binding Domains of Oncogenic UHRF1

Chromatin abnormalities are common hallmarks of cancer cells, which exhibit alterations in DNA methylation profiles that can silence tumor suppressor genes. These epigenetic patterns are partly established and maintained by UHRF1 (ubiquitin-like PHD and RING finger domain-containing protein 1), which senses existing methylation states through multiple reader domains, and reinforces the modifications through recruitment of DNA methyltransferases. Small molecule inhibitors of UHRF1 would be important tools to illuminate molecular functions, yet no compounds capable of blocking UHRF1-histone binding in the context of the full-length protein exist. Here, we report the discovery and mechanism of action of compounds that selectively inhibit the UHRF1-histone interaction with low micromolar potency. Biochemical analyses reveal that these molecules are the first inhibitors to target the PHD finger of UHRF1, specifically disrupting histone H3 arginine 2 interactions with the PHD finger. Importantly, this unique inhibition mechanism is sufficient to displace binding of full-length UHRF1 with histones in vitro and in cells. Together, our study provides insight into the critical role of the PHD finger in driving histone interactions, and demonstrates that targeting this domain through a specific binding pocket is a tractable strategy for UHRF1-histone inhibition.

Advances in Genetics and Epigenetic Alterations in Alzheimer's Disease: A Notion for Therapeutic Treatment

Alzheimer's disease (AD) is a disabling neurodegenerative disorder that leads to long-term functional and cognitive impairment and greatly reduces life expectancy. Early genetic studies focused on tracking variations in genome-wide DNA sequences discovered several polymorphisms and novel susceptibility genes associated with AD. However, despite the numerous risk factors already identified, there is still no fully satisfactory explanation for the mechanisms underlying the onset of the disease. Also, as with other complex human diseases, the causes of low heritability are unclear. Epigenetic mechanisms, in which changes in gene expression do not depend on changes in genotype, have attracted considerable attention in recent years and are key to understanding the processes that influence age-related changes and various neurological diseases. With the recent use of massive sequencing techniques, methods for studying epigenome variations in AD have also evolved tremendously, allowing the discovery of differentially expressed disease traits under different conditions and experimental settings. This is important for understanding disease development and for unlocking new potential AD therapies. In this work, we outline the genomic and epigenomic components involved in the initiation and development of AD and identify potentially effective therapeutic targets for disease control.

UHRF1 Immunohistochemical Staining Separates Benign Reactive Spindle Cell Mesothelial Proliferations From Sarcomatoid Mesotheliomas

The separation of benign from malignant mesothelial proliferations is often a difficult pathologic problem. UHRF1 (ubiquitin-like with plant homeodomain and ring finger domains-1) is a regulator of DNA methylation and an epigenetic driver of various human cancers. It has recently been reported that UHRF1 is overexpressed in mesotheliomas. We asked whether UHRF1 immunohistochemistry could be used to separate benign from malignant mesothelial proliferations. Initial studies showed that UHRF1 stained mesothelial cells but also endothelial and other non-neoplastic cells, so that accurate counting of positive mesothelial cells was difficult. Therefore, we ran dual UHRF1-AE1/AE3 stains on 2 tissue microarrays containing 40 reactive mesothelial proliferations and 61 mesotheliomas and only counted UHRF1 staining in keratin-positive cells. On average 10.3±8.6% (mean±SD; range: 0% to 36, median: 6.8%) of epithelioid mesothelioma cells stained compared with 5.3±4.8% (range: 0% to 15%, median: 4.1%) of reactive epithelial mesothelial cells. This difference was statistically significant but there was too much overlap to use diagnostically. In contrast, 37±26% (range: 2.5% to 95%, median: 31%) of cells in sarcomatoid mesotheliomas compared with 1.2±1.2% (range: 0% to 3.0%, median: 1.0%) of cells in reactive spindle cell mesothelial proliferations stained. To confirm this difference we stained whole sections of 21 sarcomatoid mesotheliomas and 19 cases of organizing pleuritis. Staining of mesothelial cells was seen in 2.1±2.4% (range: 0% to 6.8%, median: 1.0%) of organizing pleuritis cases and 44±22% (range: 14% to 90%, median: 41%) of sarcomatoid mesotheliomas. We conclude that dual UHRF1-AE1/AE3 immunohistochemistry is very useful for separating benign spindle cell mesothelial proliferations from sarcomatoid mesotheliomas.

TIP60 governs the auto‑ubiquitination of UHRF1 through USP7 dissociation from the UHRF1/USP7 complex

Tat interactive protein, 60 kDa (TIP60) is an important partner of ubiquitin-like, containing PHD and RING finger domains 1 (UHRF1), ensuring various cellular processes through its acetyltransferase activity. TIP60 is believed to play a tumor suppressive role, partly explained by its downregulated expression in a number of cancers. The aim of the present study was to investigate the role and mechanisms of action of TIP60 in the regulation of UHRF1 expression. The results revealed that TIP60 overexpression downregulated the UHRF1 and DNA methyltransferase 1 (DNMT1) expression levels. TIP60 interfered with USP7-UHRF1 association and induced the degradation of UHRF1 in an auto-ubiquitination-dependent manner. Moreover, TIP60 activated the p73-mediated apoptotic pathway. Taken together, the data of the present study suggest that the tumor suppressor role of TIP60 is mediated by its regulation to UHRF1.

A Fast Ubiquitination of UHRF1 Oncogene Is a Unique Feature and a Common Mechanism of Thymoquinone in Cancer Cells

Downregulation of the ubiquitin-like containing PHD and ring finger 1 (UHRF1) oncogene in cancer cells in response to natural anticancer drugs, including thymoquinone (TQ), is a key event that induces apoptosis. TQ can induce UHRF1 autoubiquitination via the E3 ligase activity of its RING domain, most likely through the downregulation of herpes virus-associated ubiquitin-specific protease (HAUSP). In this study, we evaluated whether HAUSP downregulation and fast ubiquitination of UHRF1 are prerequisites for UHRF1 degradation in response to TQ in cancer cells and whether doxorubicin can mimic the effects of TQ on UHRF1 ubiquitination. RNA sequencing was performed to investigate differentially expressed genes in TQ-treated Jurkat cells. The protein expression of UHRF1, HAUSP and Bcl-2 was detected by means of Western blot analysis. The proliferation of human colon cancer (HCT-116) and Jurkat cells was analyzed via the WST-1 assay. RNA sequencing data revealed that TQ significantly decreased HAUSP expression. TQ triggered UHRF1 to undergo rapid ubiquitination as the first step in its degradation and the inhibition of its cell proliferation. TQ-induced UHRF1 ubiquitination is associated with HAUSP downregulation. Like TQ, doxorubicin induced a similar dose- and time-dependent downregulation of UHRF1 in cancer cells, but UHRF1 did not undergo ubiquitination as detected in response to TQ. Furthermore, TQ decreased Bcl-2 expression without triggering its ubiquitination. A fast UHRF1 ubiquitination is an indispensable event for its degradation in response to TQ but not for its responses to doxorubicin. TQ appears to trigger ubiquitination of UHRF1 but not of the Bcl-2 oncogene, thereby identifying UHRF1 as a specific target of TQ for cancer therapy.

UHRF1 Could Be a Prognostic Biomarker and Correlated with Immune Cell Infiltration in Hepatocellular Carcinoma

OBJECTIVE

This study was performed to investigate the relationship among UHRF1 expression, its biological function and immune infiltration in human hepatocellular carcinoma (HCC).

METHODS

Gene Expression Profiling Interactive Analysis (GEPIA), Oncomine, and The Cancer Genome Atlas (TCGA) databases were used to analyze UHRF1 expression between HCC and normal tissues. Subsequently, GEPIA, TCGA-Portal, Kaplan-Meier Plotter, Protein Atlas and SurvExpress databases were utilized for survival analysis. UHRF1 co-expression genes were identified via the cBioPortal and LinkedOmics databases. Further, gene ontology (GO) analysis as well as Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed. Protein-protein interaction (PPI) networks was constructed by STRING database and Cytoscape 3.7.1. Single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT algorithm were employed to assess the correlation between UHRF1 and tumor immune infiltrates on TCGA database. TIMER 2.0 database was used to explore the correlation of UHRF1 expression and immune infiltration level in HCC. Additionally, RT-qPCR was used to analyze the expression of UHRF1 and the relative genes in HCC cell lines.

RESULTS

Expression level of UHRF1 was upregulated in HCC tissues compared with paired normal tissues (P < 0.05 in GEPIA; P = 1.78E^-6 in Oncomine; and P < 0.0001 in TCGA). Its high expression was significantly related with a shorter overall survival in five databases (P < 0.05). Function enrichment analysis demonstrated that functions of UHRF1 concentrated in cell division process and cell cycle (P < 0.05). High UHRF1 expression exhibited dysregulated immune infiltration (ie, neutrophils, eosinophils, dendritic cells resting, macrophages M2, macrophages M0) and poor survival of high UHRF1 expression was tight correlated with immune infiltration status. Moreover, TP53 mutation can lead to high expression of UHRF1 (P = 4.2E^-10).

CONCLUSION

UHRF1 might function as an oncogene via inducing dysregulated immune infiltration in HCC and was identified as a novel prognostic biomarker and potential therapeutic target for HCC.

Transgenic zebrafish for modeling hepatocellular carcinoma

Liver cancer is the third leading cause of cancer‐related deaths throughout the world, and more than 0.6 million people die from liver cancer annually. Therefore, novel therapeutic strategies to eliminate malignant cells from liver cancer patients are urgently needed. Recent advances in high‐throughput genomic technologies have identified de novo candidates for oncogenes and pharmacological targets. However, testing and understanding the mechanism of oncogenic transformation as well as probing the kinetics and therapeutic responses of spontaneous tumors in an intact microenvironment require in vivo examination using genetically modified animal models. The zebrafish (Danio rerio) has attracted increasing attention as a new model for studying cancer biology since the organs in the model are strikingly similar to human organs and the model can be genetically modified in a short time and at a low cost. This review summarizes the current knowledge of epidemiological data and genetic alterations in hepatocellular carcinoma (HCC), zebrafish models of HCC, and potential therapeutic strategies for targeting HCC based on knowledge from the models.

CircFAT1 Suppresses Colorectal Cancer Development Through Regulating miR-520b/UHRF1 Axis or miR-302c-3p/UHRF1 Axis

Background: It was reported that circular RNAs (circRNAs) exerted important functions in various human cancers. However, the function of circFAT1 was less known. The purpose of this study was to reveal the functional mechanism of circFAT1 in colorectal cancer (CRC). Materials and Methods: Quantitative real-time polymerase chain reaction and Western blot assay were used to detect the levels of genes. Cell proliferation ability was assessed by 3-(4, 5-dimethyl-2-thiazoyl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to investigate cell apoptosis rate. The glucose consumption and lactate production were determined using related kits. Furthermore, the interaction between circFAT1 or ubiquitin-like PHD and RING finger domain-containing protein 1 (UHRF1) and miR-520b or miR-302c-3p was predicted by starbase3.0, and then confirmed by the dual-luciferase reporter assay. Besides, xenograft experiment was performed to analyze the effect of circFAT1 on tumor growth in vivo. Results: The levels of circFAT1 and UHRF1 were increased, as well as the levels of miR-520b and miR-302c-3p were decreased in CRC tissues and cells. CircFAT1 knockdown suppressed cell proliferation, cycle, and glycolysis as well as induced apoptosis. Interestingly, circFAT1 was a sponge of miR-520b and miR-302c-3p, and miR-520b and miR-302c-3p could target UHRF1. Both miR-520b overexpression and miR-302c-3p overexpression inhibited CRC cell growth. Furthermore, both miR-520b knockdown and miR-302c-3p depletion weakened the effect of circFAT1 knockdown on the growth of CRC cells. Besides, circFAT1 depletion repressed tumor growth in vivo. Conclusion: The authors' findings suggested that circFAT1 upregulated UHRF1 to affect CRC cell proliferation, apoptosis, and glycolysis through targeting miR-520b and miR-302c-3p, providing theoretical basis for the treatment of CRC.

UHRF1, a Regulator of Methylation, as a Diagnostic and Prognostic Marker for Lung Cancer

We evaluated the value of UHRF1, a regulator of methylation, as a biomarker for lung cancer. UHRF1 is expressed at higher levels in both lung adenocarcinoma (AD) and squamous cell carcinoma (SQ); however, a meta-analysis showed that UHRF1 expression is correlated with worse survival in patients with AD but not in those with SQ. UHRF1 knockdown suppressed the growth of lung cancer cell lines through G1 cell cycle arrest in some cell lines. These results suggest that UHRF1 may server as a diagnostic marker for AD and SQ and as a prognostic marker for AD in lung cancer.

Identification of master regulator genes of UV response and their implications for skin carcinogenesis

Solar UV radiation is a major environmental risk factor for skin cancer. Despite decades of robust and meritorious investigation, our understanding of the mechanisms underlying UV-induced skin carcinogenesis remain incomplete. We previously performed comprehensive transcriptomic profiling in human keratinocytes following exposure to different UV radiation conditions to generate UV-specific gene expression signatures. In this study, we utilized Virtual Inference of Protein Activity by Enriched Regulon (VIPER), a robust systems biology tool, on UV-specific skin cell gene signatures to identify master regulators (MRs) of UV-induced transcriptomic changes. We identified multiple prominent candidate UV MRs, including forkhead box M1 (FOXM1), thyroid hormone receptor interactor 13 and DNA isomerase II alpha, which play important roles in cell cycle regulation and genome stability. MR protein activity was either activated or suppressed by UV in normal keratinocytes. Intriguingly, many of the UV-suppressed MRs were activated in human skin squamous cell carcinomas (SCCs), highlighting their importance in skin cancer development. We further demonstrated that selective inhibition of FOXM1, whose activity was elevated in SCC cells, was detrimental to SCC cell survival. Taken together, our study uncovered novel UV MRs that can be explored as new therapeutic targets for future skin cancer treatment.

The Rare Variant rs35356162 in UHRF1BP1 Increases Bladder Cancer Risk in Han Chinese Population

Background: Seventeen loci have been found to be associated with bladder cancer risk by genome-wide association studies (GWAS) in European population. However, little is known about contribution of low-frequency and rare variants to bladder cancer susceptibility, especially in Eastern population.

Methods: We performed a three-stage case-control study including 3,399 bladder cancer patients and 4,647 controls to identify low-frequency and rare variants associated with bladder cancer risk in Han Chinese. We examined exome-array data in 1,019 bladder cancer patients and 1,008 controls in discovery stage. Two replication stages were included to validate variants identified. Bonferroni adjustment was performed to define statistical significance. Logistic regression was conducted to evaluate single marker association with bladder cancer risk. We used SKAT-O method to perform gene level-based analysis. We also conduct additional experiments to explore the underlying mechanism of filtered gene(s).

Results: We identified a novel rare coding variant (rs35356162 in UHRF1BP1: G > T, OR = 4.332, P = 3.62E-07 < 7.93E-07, Bonferroni cutoff) that increased bladder cancer risk in Han Chinese. Gene-level analysis showed a significant association of UHRF1BP1 (P = 4.47E-03) with bladder cancer risk. Experiments indicated down-regulation of UHRF1BP1 promoted migration and invasion through epithelial-mesenchymal transition in bladder cancer cell lines.

Conclusion: The rare variant of UHRF1BP1, rs35356162, increases bladder cancer risk in Han Chinese and UHRF1BP1 might act as a tumor suppressor in bladder cancer development and progression.

Summary: Little is known about potential contribution of low-frequency and rare variants to bladder cancer susceptibility. We performed a three-stage case-control study and identified a new rare variant, rs35356162 in UHRF1BP1, which increased bladder cancer risk in Han Chinese.

The nuclear phosphoinositide response to stress

Accumulating evidence reveals that nuclear phosphoinositides (PIs) serve as central signaling hubs that control a multitude of nuclear processes by regulating the activity of nuclear proteins. In response to cellular stressors, PIs accumulate in the nucleus and multiple PI isomers are synthesized by the actions of PI-metabolizing enzymes, kinases, phosphatases and phospholipases. By directly interacting with effector proteins, phosphoinositide signals transduce changes in cellular functions. Here we describe nuclear phosphoinositide signaling in multiple sub-nuclear compartments and summarize the literature that demonstrates roles for specific kinases, phosphatases, and phospholipases in the orchestration of nuclear phosphoinositide signaling in response to cellular stress. Additionally, we discuss the specific PI-protein complexes through which these lipids execute their functions by regulating the configuration, stability, and transcription activity of their effector proteins. Overall, our review provides a detailed landscape of the current understanding of the nuclear PI-protein interactome and its role in shaping the coordinated response to cellular stress.

MiR-506 Targets UHRF1 to Inhibit Colorectal Cancer Proliferation and Invasion via the KISS1/PI3K/NF-κB Signaling Axis

Background

The UHRF1 gene is an epigenetic modification factor that mediates tumor suppressor gene silencing in a variety of cancers. Related studies have reported that UHRF1 can inhibit the expression of the KISS1 gene. However, the regulatory mechanism underlying UHRF1 expression in colorectal cancer (CRC) is still unclear. The aim of this study was to gain a better understanding of the regulation of UHRF1 expression in CRC and to determine whether it regulates the mechanism by which KISS1 promotes CRC metastasis.

Methods

In the present study, the levels of miR-506, UHRF1 and KISS1 expression in CRC tissues and in human CRC cell lines were studied using quantitative real-time PCR (qRT-PCR) and Western blotting. Cell proliferation, migration, and invasion assays are used to detect cell proliferation, migration, and invasion. A dual-luciferase reporter system was used to confirm the target gene of miR-506.

Results

This study found that UHRF1 protein is highly expressed in CRC tissues and negatively correlated with KISS1 protein expression. UHRF1 overexpression activates the PI3K/NF-κB signaling pathway by inhibiting the mRNA expression levels of pathway mediators. Bioinformatics analysis and luciferase reporter gene assays confirmed that miR-506 targets UHRF1.

Conclusion

This study identified the regulation of UHRF1 expression in CRC and the mechanism of CRC metastasis. UHRF1 may be a new potential target molecule for future CRC metastasis treatment.

UHRF1 Promotes Proliferation of Human Adipose-Derived Stem Cells and Suppresses Adipogenesis via Inhibiting Peroxisome Proliferator-Activated Receptor γ

Once the adipose tissue is enlarged for the purpose of saving excess energy intake, obesity may be observed. Ubiquitin-like with PHD and RING Finger domains 1 (UHRF1) is helpful in repairing damaged DNA as it increases the resistance of cancer cells against cytocidal drugs. Peroxisome proliferator-activated receptor γ (PPARγ), an important nucleus transcription factor participating in adipogenesis, has been extensively reported. To date, no study has indicated whether UHRF1 can regulate proliferation and differentiation of human adipose-derived stem cells (hADSCs). Hence, this study aimed to utilize overexpression or downregulation of UHRF1 to explore the possible mechanism of proliferation and differentiation of hADSCs. We here used lentivirus, containing UHRF1 (LV-UHRF1) and siRNA-UHRF1 to transfect hADSCs, on which Cell Counting Kit-8 (CCK-8), cell growth curve, colony formation assay, and EdU proliferation assay were applied to evaluate proliferation of hADSCs, cells cycle was investigated by flow cytometry, and adipogenesis was detected by Oil Red O staining and Western blotting. Our results showed that UHRF1 can promote proliferation of hADSCs after overexpression of UHRF1, while proliferation of hADSCs was reduced through downregulation of UHRF1, and UHRF1 can control proliferation of hADSCs through transition from G1-phase to S-phase; besides, we found that UHRF1 negatively regulates adipogenesis of hADSCs via PPARγ. In summary, the results may provide a new insight regarding the role of UHRF1 on regulating proliferation and differentiation of hADSCs.

DNA Methylation Readers and Cancer: Mechanistic and Therapeutic Applications

DNA methylation is a major epigenetic process that regulates chromatin structure which causes transcriptional activation or repression of genes in a context-dependent manner. In general, DNA methylation takes place when methyl groups are added to the appropriate bases on the genome by the action of "writer" molecules known as DNA methyltransferases. How these methylation marks are read and interpreted into different functionalities represents one of the main mechanisms through which the genes are switched "ON" or "OFF" and typically involves different types of "reader" proteins that can recognize and bind to the methylated regions. A tightly balanced regulation exists between the "writers" and "readers" in order to mediate normal cellular functions. However, alterations in normal methylation pattern is a typical hallmark of cancer which alters the way methylation marks are written, read and interpreted in different disease states. This unique characteristic of DNA methylation "readers" has identified them as attractive therapeutic targets. In this review, we describe the current state of knowledge on the different classes of DNA methylation "readers" identified thus far along with their normal biological functions, describe how they are dysregulated in cancer, and discuss the various anti-cancer therapies that are currently being developed and evaluated for targeting these proteins.

UHRF1 depletion and HDAC inhibition reactivate epigenetically silenced genes in colorectal cancer cells

BACKGROUND

Ubiquitin-like protein containing PHD and RING finger domains 1 (UHRF1) is a major regulator of epigenetic mechanisms and is overexpressed in various human malignancies. In this study, we examined the involvement of UHRF1 in aberrant DNA methylation and gene silencing in colorectal cancer (CRC).

RESULTS

CRC cell lines were transiently transfected with siRNAs targeting UHRF1, after which DNA methylation was analyzed using dot blots, bisulfite pyrosequencing, and Infinium HumanMethylation450 BeadChip assays. Gene expression was analyzed using RT-PCR and gene expression microarrays. Depletion of UHRF1 rapidly induced genome-wide DNA demethylation in CRC cells. Infinium BeadChip assays and bisulfite pyrosequencing revealed significant demethylation across entire genomic regions, including CpG islands, gene bodies, intergenic regions, and repetitive elements. Despite the substantial demethylation, however, UHRF1 depletion only minimally reversed CpG island hypermethylation-associated gene silencing. By contrast, the combination of UHRF1 depletion and histone deacetylase (HDAC) inhibition reactivated the silenced genes and strongly suppressed CRC cell proliferation. The combination of UHRF1 depletion and HDAC inhibition also induced marked changes in the gene expression profiles such that cell cycle-related genes were strikingly downregulated.

CONCLUSIONS

Our results suggest that (i) maintenance of DNA methylation in CRC cells is highly dependent on UHRF1; (ii) UHRF1 depletion rapidly induces DNA demethylation, though it is insufficient to fully reactivate the silenced genes; and (iii) dual targeting of UHRF1 and HDAC may be an effective new therapeutic strategy.

UHRF1 is regulated by miR-124-3p and promotes cell proliferation in intrahepatic cholangiocarcinoma

Ubiquitin-like with PHD and ring finger domains 1 (UHRF1) is abnormally overexpressed in multiple cancers and closely correlated with tumor-promoting effects, such as high proliferation. However, how UHRF1 functions in intrahepatic cholangiocarcinoma (ICC) has not yet been determined. Herein, we found that UHRF1 is overexpressed in ICC tissues. Downregulated UHRF1 attenuated the transition of the G1/S cell cycle and then suppressed cell proliferation in vitro and tumor growth in vivo. Moreover, upstream regulators of the UHRF1 expression were predicted, and we found that direct binding of miR-124-3p inhibited the UHRF1 expression. Elevated miR-124-3p suppressed proliferation and led to the arrest of the cell cycle. Furthermore, the expression of UHRF1 was positively correlated with PCNA. Clinically, we showed that elevated UHRF1 was associated with poor prognosis, and served as an independent prognostic factor in ICC patients. Together, these findings demonstrate that UHRF1, regulated by miR-124-3p, acts as a tumor promoter by promoting cell proliferation in ICC.

MLL3 promotes the senescence of esophageal squamous cell carcinoma

Background

Senescence has been recognized as a mechanism for the suppression of tumorigenesis. However, how the senescence is regulated is not fully understood.

Aims

The present study aims to elucidate MLL3-mediated regulation of senescence.

Materials and methods

MLL3 protein levels in esophageal squamous cell carcinoma (ESCC) tissues were examined by Western blotting and immunohistochemistry. The effects of MLL3 on the growth and senescence of ESCC cells were examined using MTT assay, soft agar assay, and β-gal staining. The interaction between MLL3 and P16 was evaluated by immunoprecipitation and GST pull-down assay.

Results

In this study, we found that MLL3 promoted the senescence of ESCC cells. MLL3 was downregulated in ESCC. MLL3 inhibited the growth and colony formation of ESCC cells. Mechanistically, MLL3 interacted with P16 and impaired the interaction between P16 and UHRF1 (the E3 ligase for P16), thus upregulating the protein levels of several senescence regulators.

Conclusion

Collectively, this study demonstrated the regulation of senescence by MLL3.

Activated MEK/ERK Pathway Drives Widespread and Coordinated Overexpression of UHRF1 and DNMT1 in Cancer cells

The UHRF1-DNMT1 axis plays a key role in DNA maintenance methylation in mammals. Accumulative studies demonstrate that UHRF1 is broadly overexpressed in cancers, which contributes to cancer cell proliferation and tumorigenesis. Interestingly, a proteasome-dependent downregulation of UHRF1 has been observed in pluripotent ground state mouse embryonic stem cells (mESCs) cultured in the presence of two kinase (MEK1/MEK2 and GSK3β) inhibitors (termed 2i), raising the question whether UHRF1 is similarly regulated in cancer cells. Here we present evidence that while addition of 2i broadly downregulates UHRF1 and DNMT1 in various cancer cells, distinct underlying mechanisms are involved. In contrast to mESCs, 2i-induced downregulation of UHRF1 and DNMT1 in cancer cells cannot be rescued by proteasome inhibitor and occurs primarily at the level of transcription. Furthermore, downregulation of UHRF1 and DNMT1 by 2i is due to inhibition of MEK1/MEK2, but not GSK3β activity. Data mining reveals a marked co-expression of UHRF1 and DNMT1 in normal tissues as well as cancers. We provide evidence that multiple transcription factors including E2F1 and SP1 mediate the transcriptional activation of UHRF1 and DNMT1 by the activated MEK/ERK pathway. Together our study reveals distinct regulation of UHRF1/DNMT1 in mESCs and cancer cells and identifies activated MEK/ERK pathway as a driving force for coordinated and aberrant over-expression of UHRF1 and DNMT1 in cancers.

Epigenetic mechanism and target therapy of UHRF1 protein complex in malignancies

Ubiquitin-like with plant homeodomain and really interesting new gene finger domains 1 (UHRF1) functions as an epigenetic regulator recruiting PCNA, DNMT1, histone deacetylase 1, G9a, SuV39H, herpes virus-associated ubiquitin-specific protease, and Tat-interactive protein by multiple corresponding domains of DNA and H3 to maintain DNA methylation and histone modifications. Overexpression of UHRF1 has been found as a potential biomarker in various cancers resulting in either DNA hypermethylation or global DNA hypo-methylation, which participates in the occurrence, progression, and invasion of cancer. The role of UHRF1 in the reciprocal interaction between DNA methylation and histone modifications, the dynamic structural transformation of UHRF1 protein within epigenetic code replication machinery in epigenetic regulations, as well as modifications during cell cycle and chemotherapy targeting UHRF1 are evaluated in this study.

UHRF1 mediates cell migration and invasion of gastric cancer

Gastric cancer (GC) is a common highly aggressive malignant tumor in worldwide. Ubiquitin-like with PHD and ring-finger protein 1 (UHRF1) has a key role in several kinds of cancers development. However, the biology effect of UHRF1 on the tumorigenesis of GC remains unclear. In this research, the role of UHRF1 in the growth, migration, invasion and apoptosis and the underlying mechanisms were investigated in MGC803 and SGC7901 cells. The UHRF1 knockdown MGC803 and SGC7901 cell lines were used to investigate the roles of UHRF1 on GC cell growth, migration, invasion and apoptosis. The growth, migration and invasion rate of UHRF1 knockdown cells was lower than that of the control. Moreover, ROS generation and caspase-3/caspase-9 activities increased in UHRF1 knockdown cells. And mitochondrial membrane potential decreased in UHRF1 knockdown cells. These findings indicated that UHRF1 promoted the growth, migration and invasion of MGC803 and SGC7901 cells and inhibited apoptosis via a ROS-associated pathway.

Maintenance and pharmacologic targeting of ROR1 protein levels via UHRF1 in t(1;19) pre-B-ALL

Expression of the transmembrane pseudokinase ROR1 is required for survival of t(1;19)-pre-B-cell acute lymphoblastic leukemia (t(1;19) pre-B-ALL), chronic lymphocytic leukemia, and many solid tumors. However, targeting ROR1 with small-molecules has been challenging due to the absence of ROR1 kinase activity. To identify genes that regulate ROR1 expression and may, therefore, serve as surrogate drug targets, we employed an siRNA screening approach and determined that the epigenetic regulator and E3 ubiquitin ligase, UHRF1, is required for t(1;19) pre-B-ALL cell viability in a ROR1-dependent manner. Upon UHRF1 silencing, ROR1 protein is reduced without altering ROR1 mRNA, and ectopically expressed UHRF1 is sufficient to increase ROR1 levels. Additionally, proteasome inhibition rescues loss of ROR1 protein after UHRF1 silencing, suggesting a role for the proteasome in the UHRF1-ROR1 axis. Finally, we show that ROR1-positive cells are twice as sensitive to the UHRF1-targeting drug, naphthazarin, and undergo increased apoptosis compared to ROR1-negative cells. Naphthazarin elicits reduced expression of UHRF1 and ROR1, and combination of naphthazarin with inhibitors of pre-B cell receptor signaling results in further reduction of cell survival compared with either inhibitor alone. Therefore, our work reveals a mechanism by which UHRF1 stabilizes ROR1, suggesting a potential targeting strategy to inhibit ROR1 in t(1;19) pre-B-ALL and other malignancies.

DNA damage response and repair in colorectal cancer: Defects, regulation and therapeutic implications

DNA damage response, a key factor involved in maintaining genome integrity and stability, consists of several kinase-dependent signaling pathways, which sense and transduce DNA damage signal. The severity of damage appears to determine DNA damage responses, which can include cell cycle arrest, damage repair and apoptosis. A number of recent studies have demonstrated that defection in signaling through this network is thought to be an underlying mechanism behind the development and progression of various types of human malignancies, including colorectal cancer. In this review, colorectal cancer and its molecular pathology as well as DNA damage response is briefly introduced. Finally, the involvement of key components of this network in the initiation/progression, prognosis, response to treatment and development of drug resistance is comprehensively discussed.

Np95/Uhrf1 regulates tumor suppressor gene expression of neural stem/precursor cells, contributing to neurogenesis in the adult mouse brain

Adult neurogenesis is a process of generating new neurons from neural stem/precursor cells (NS/PCs) in restricted adult brain regions throughout life. It is now generally known that adult neurogenesis in the hippocampal dentate gyrus (DG) and subventricular zone participates in various higher brain functions, such as learning and memory formation, olfactory discrimination and repair after brain injury. However, the mechanisms underlying adult neurogenesis remain to be fully understood. Here, we show that Nuclear protein 95 KDa (Np95, also known as UHRF1 or ICBP90), which is an essential protein for maintaining DNA methylation during cell division, is involved in multiple processes of adult neurogenesis. Specific ablation of Np95 in adult NS/PCs (aNS/PCs) led to a decrease in their proliferation and an impairment of neuronal differentiation and to suppression of neuronal maturation associated with the impairment of dendritic formation in the hippocampal DG. We also found that deficiency of Np95 in NS/PCs increased the expression of tumor suppressor genes p16 and p53, and confirmed that expression of these genes in NS/PCs recapitulates the phenotype of Np95-deficient NS/PCs. Taken together, our findings suggest that Np95 plays an essential role in proliferation and differentiation of aNS/PCs through the regulation of tumor suppressor gene expression in adult neurogenesis.

Upregulation of UHRF1 promotes the progression of melanoma by inducing cell proliferation

Melanoma is the most aggressive cutaneous cancer due to its propensity to metastasise and proliferate. Melanoma accounts for 80–90% of skin-cancer related deaths worldwide. Alhough numerous published studies have attempted to define the markers of diagnosis and prognosis of melanoma, a sensitive and specific biomarker for melanoma remains unknown. Recently, ubiquitin-like with PHD and ring finger domains 1 (UHRF1) has attracted attention due to its role in cell proliferation and it has been deemed as a potential therapeutic target for cancer. The aim of the present study was to investigate the role and the clinical significance of UHRF1 in melanoma. Immunohistochemical analysis was performed with tissue microarray (TMA) to examine the expression of UHRF1 and Ki-67, and the role of UHRF1 in cell proliferation was determined through CCK-8, colony formation and flow cytometry by interfering with the expression of UHRF1. Subsequently, the relationship among the expression of UHRF1 and several major clinical characteristics of melanoma were analysed to evaluate the role of UHRF1 in the progression of melanoma. Finally, the clinical significance of UHRF1 was estimated in 56 melanoma patients. It was observed that the expression of UHRF1 was significantly upregulated in melanoma compared with benign nevi tissues (P<0.05). In addition, the downregulation of the expression of UHRF1 significantly decreased cell proliferation. Furthermore, the level of UHRF1 was positively correlated with the expression of Ki-67 in melanoma cells, as well as in melanoma tissues. Clinically, a high level of UHRF1 was prone to be related to a high TNM classification (P=0.017) and Breslow's thickness (P=0.034) of melanoma. Furthermore, a high level of UHRF1 was positively associated with a shorter overall survival of melanoma patients. Importantly, the Cox regression model analysis demonstrated that the expression of UHRF1 was an independent prognostic factor for the overall survival of melanoma patients. In conclusion, the elevated expression of UHRF1 plays an important role in melanoma cell proliferation and progression, and it can be used as a prognostic biomarker for melanoma.

Comparative Proteomics of Dying and Surviving Cancer Cells Improves the Identification of Drug Targets and Sheds Light on Cell Life/Death Decisions

Chemotherapeutics cause the detachment and death of adherent cancer cells. When studying the proteome changes to determine the protein target and mechanism of action of anticancer drugs, the still-attached cells are normally used, whereas the detached cells are usually ignored. To test the hypothesis that proteomes of detached cells contain valuable information, we separately analyzed the proteomes of detached and attached HCT-116, A375, and RKO cells treated for 48 h with 5-fluorouracil, methotrexate and paclitaxel. Individually, the proteomic data on attached and detached cells had comparable performance in target and drug mechanism deconvolution, whereas the combined data significantly improved the target ranking for paclitaxel. Comparative analysis of attached versus detached proteomes provided further insight into cell life and death decision making. Six proteins consistently up- or downregulated in the detached versus attached cells regardless of the drug and cell type were discovered; their role in cell death/survival was tested by silencing them with siRNA. Knocking down USP11, CTTN, ACAA2, and EIF4H had anti-proliferative effects, affecting UHRF1 additionally sensitized the cells to the anticancer drugs, while knocking down RNF-40 increased cell survival against the treatments. Therefore, adding detached cells to the expression proteomics analysis of drug-treated cells can significantly increase the analytical value of the approach. The data have been deposited to the ProteomeXchange with identifier PXD007686.

UHRF1 regulates global DNA hypomethylation and is associated with poor prognosis in esophageal squamous cell carcinoma

Background

Global DNA hypomethylation contributes to oncogenesis through various mechanisms. The level of long interspersed nucleotide element-1 (LINE- 1) methylation is considered a surrogate marker of global DNA methylation, and is attracting interest as a good predictor of cancer prognosis. However, the mechanism how LINE-1 (global DNA) methylation is controlled in cancer cells remains to be fully elucidated. Ubiquitin-like with PHD and RING finger domain 1 (UHRF1) plays a crucial role in DNA methylation. UHRF1 is overexpressed in many cancers, and UHRF1 overexpression may be a mechanism underlying DNA hypomethylation in cancer cells. Nonetheless, the relationship between UHRF1, LINE-1 methylation level, and clinical outcome in esophageal squamous cell carcinoma (ESCC) remains unclear.

Results

In ESCC cell lines, vector-mediated UHRF1 overexpression caused global DNA (LINE-1) hypomethylation and, conversely, UHRF1 knockdown using siRNA increased the global DNA methylation level. In ESCC tissues, UHRF1 expression was significantly associated with LINE-1 methylation levels. Furthermore, UHRF1 overexpression correlated with poor prognosis in our cohort of 160 ESCC patients.

Materials and Methods

The relationships between UHRF1 expression and LINE-1 methylation level (i.e., global DNA methylation level) were investigated using ESCC tissues and cell lines. In addition, we examined the correlation between UHRF1 expression, LINE-1 methylation, and clinical outcome in patients with ESCC.

Conclusions

Our results suggest that UHRF1 is a key epigenetic regulator of DNA methylation and might be a potential target for cancer treatment.

UHRF1 epigenetically down-regulates UbcH8 to inhibit apoptosis in cervical cancer cells

UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is an important epigenetic regulator that plays a part in DNA methylation, protein methylation and ubiquitination. It is also frequently overexpressed in many types of cancers, including cervical cancer, which is caused by human papillomavirus (HPV). In this study, we showed that UHRF1 was up-regulated in HPV oncogene E7 expressing cells and HPV-positive cervical cancer cells. We demonstrated that UHRF1 down-regulated the expression of UBE2L6 gene that encodes the ISG15-conjugating enzyme UbcH8. Overexpression of UHRF1 reduced UBE2L6 while knockdown UHRF1 elevated the expression of UBE2L6. We showed that UHRF1 regulated UBE2L6 gene by promoter hypermethylation in cervical cancer cells. Consistent with the functions of UHRF1, restored expression of UbcH8 induced apoptosis. These findings establish UBE2L6 as a novel target of UHRF1 that regulates the apoptosis function of UHRF1. Our studies suggest that UHRF1/ UbcH8 can be manipulated for therapy in cervical cancer.

Conformational dynamics of the TTD-PHD histone reader module of the UHRF1 epigenetic regulator reveals multiple histone-binding states, allosteric regulation, and druggability

UHRF1 is a key mediator of inheritance of epigenetic DNA methylation patterns during cell division and is a putative target for cancer therapy. Recent studies indicate that interdomain interactions critically influence UHRF1's chromatin-binding properties, including allosteric regulation of its histone binding. Here, using an integrative approach that combines small angle X-ray scattering, NMR spectroscopy, and molecular dynamics simulations, we characterized the dynamics of the tandem tudor domain-plant homeodomain (TTD-PHD) histone reader module, including its 20-residue interdomain linker. We found that the apo TTD-PHD module in solution comprises a dynamic ensemble of conformers, approximately half of which are compact conformations, with the linker lying in the TTD peptide-binding groove. These compact conformations are amenable to cooperative, high-affinity histone binding. In the remaining conformations, the linker position was in flux, and the reader adopted both extended and compact states. Using a small-molecule fragment screening approach, we identified a compound, 4-benzylpiperidine-1-carboximidamide, that binds to the TTD groove, competes with linker binding, and promotes open TTD-PHD conformations that are less efficient at H3K9me3 binding. Our work reveals a mechanism by which the dynamic TTD-PHD module can be allosterically targeted with small molecules to modulate its histone reader function for therapeutic or experimental purposes.

Interaction of the epigenetic integrator UHRF1 with the MYST domain of TIP60 inside the cell

Background

The nuclear epigenetic integrator UHRF1 is known to play a key role with DNMT1 in maintaining the DNA methylation patterns during cell division. Among UHRF1 partners, TIP60 takes part in epigenetic regulations through its acetyltransferase activity. Both proteins are involved in multiple cellular functions such as chromatin remodeling, DNA damage repair and regulation of stability and activity of other proteins. The aim of this work was to investigate the interaction between UHRF1 and TIP60 in order to elucidate the dialogue between these two proteins.

Methods

Biochemical (immunoprecipitation and pull-down assays) and microscopic (confocal and fluorescence lifetime imaging microscopy; FLIM) techniques were used to analyze the interaction between TIP60 and UHRF1 in vitro and in vivo. Global methylation levels were assessed by using a specific kit. The results were statistically analyzed using Graphpad prism and Origin.

Results

Our study shows that UHRF1, TIP60 and DNMT1 were found in the same epigenetic macro-molecular complex. In vitro pull-down assay showed that deletion of either the zinc finger in MYST domain or deletion of whole MYST domain from TIP60 significantly reduced its interaction with UHRF1. Confocal and FLIM microscopy showed that UHRF1 co-localized with TIP60 in the nucleus and confirmed that both proteins interacted together through the MYST domain of TIP60. Moreover, overexpression of TIP60 reduced the DNA methylation levels in HeLa cells along with downregulation of UHRF1 and DNMT1.

Conclusion

Our data demonstrate for the first time that TIP60 through its MYST domain directly interacts with UHRF1 which might be of high interest for the development of novel oncogenic inhibitors targeting this interaction.

Targeting microRNA/UHRF1 pathways as a novel strategy for cancer therapy

Ubiquitin-like containing plant homeodomain and RING finger domains 1 (UHRF1) is an anti-apoptotic protein involved in the silencing of several tumor suppressor genes (TSGs) through epigenetic modifications including DNA methylation and histone post-translational alterations, and also epigenetic-independent mechanisms. UHRF1 overexpression is observed in a number of solid tumors and hematological malignancies, and is considered a primary mechanism in inhibiting apoptosis. UHRF1 exerts its inhibitory activity on TSGs by binding to functional domains and therefore influences several epigenetic actors including DNA methyltransferase, histone deacetylase 1, histone acetyltransferase Tat-interacting protein 60 and histone methyltransferases G9a and Suv39H1. UHRF1 is considered to control a large macromolecular protein complex termed epigenetic code replication machinery, in order to maintain epigenetic silencing of TSGs during cell division, thus enabling cancer cells to escape apoptosis. MicroRNAs (miRNAs) are able to regulate the expression of its target gene by functioning as either an oncogene or a tumor suppressor. In the present review, the role of tumor suppressive miRNAs in the regulation of UHRF1, and the importance of targeting the microRNA/UHRF1 pathways in order to induce the reactivation of silenced TSGs and subsequent apoptosis are discussed.

UHRF1 is an Independent Prognostic Factor and a Potential Therapeutic Target of Esophageal Squamous Cell Carcinoma

Purpose: Ubiquitin-like with plant homeodomain and ring-finger domains 1 (UHRF1) plays an essential role in DNA methylation, and the overexpression of UHRF1 is associated with poor prognosis in various cancers. Esophageal squamous cell carcinoma (ESCC) accounts for approximately 90% of esophageal cancer cases in China, but the five-year survival rate for patients is less than 10% due to limited clinical approaches for early diagnosis and treatment. The present research aimed to investigate the expression of UHRF1 in ESCC and its biological role in ESCC development. Methods: UHRF1 expression in ESCC and normal esophageal tissues was examined using immunohistochemical staining, followed by analysis of the correlation between UHRF1 expression and clinical features. In addition, the effects of lentivirus-mediated RNA interference of UHRF1 on global DNA methylation, cell proliferation, cell cycle progression and apoptosis and were investigated in ESCC cells. Results: UHRF1 was overexpressed in ESCC tissues and was an independent prognostic factor for ESCC patients. In ESCC cells, knockdown of UHRF1 caused global DNA hypomethylation, inhibited cell proliferation and induced apoptosis. Furthermore, UHRF1 depletion induced cell cycle arrest at the G2/M phase, accompanied by activation of Wee1 and DNA damage response pathway. Conclusions: Our findings identify UHRF1 as a promising prognostic marker for ESCC and suggest that UHRF1 may be a potential therapy target for ESCC patients with elevated UHRF1 expression.

Regulation of UHRF1 by microRNA-378 modulates medulloblastoma cell proliferation and apoptosis

A previous study revealed that ubiquitin-like with PHD and RING finger domains 1 (UHRF1) promoted cell proliferation and was a potential biomarker in medulloblastoma (MB). In the present study, we reported that miR-378 inhibited the expression of UHRF1 to affect the proliferation of MB through competitive binding to the same region of its 3'-UTR. We found that the expression of miR-378 was significantly downregulated in MB tissues and inversely correlated with the expression of UHRF1. Western blot analysis revealed that overexpression of miR-378 led to the suppression of UHRF1. Moreover, a dual-luciferase assay demonstrated that miR-378 negatively regulated the activity of target gene UHRF1 by binding to its 3'-UTR. An in vitro assay revealed that overexpression of miR-378 suppressed MB cell proliferation and promoted cell apoptosis. Ectopic expression of UHRF1 rescued miR-378-suppressed cell proliferation and miR-378-promoted cell apoptosis. Collectively, the present study demonstrated that miR-378 could inhibit the proliferation of MB by downregulation of UHRF1 and act as a potential therapeutic target against MB.

The epigenetic integrator UHRF1: on the road to become a universal biomarker for cancer

Cancer is one of the deadliest diseases in the world causing record number of mortalities in both developed and undeveloped countries. Despite a lot of advances and breakthroughs in the field of oncology still, it is very hard to diagnose and treat the cancers at early stages. Here in this review we analyze the potential of Ubiquitin-like containing PHD and Ring Finger domain 1 (UHRF1) as a universal biomarker for cancers. UHRF1 is an important epigenetic regulator maintaining DNA methylation and histone code in the cell. It is highly expressed in a variety of cancers and is a well-known oncogene that can disrupt the epigenetic code and override the senescence machinery. Many studies have validated UHRF1 as a powerful diagnostic and prognostic tool to differentially diagnose cancer, predict the therapeutic response and assess the risk of tumor progression and recurrence. Highly sensitive, non-invasive and cost effective approaches are therefore needed to assess the level of UHRF1 in patients, which can be deployed in diagnostic laboratories to detect cancer and monitor disease progression.

miR‑27a promotes proliferation, migration, and invasion of colorectal cancer by targeting FAM172A and acts as a diagnostic and prognostic biomarker

Accumulating evidence shows that mircroRNAs (miRNAs) play a crucial role in the development of colorectal cancer. In our previous study, FAM172A was demonstrated to be a novel tumor suppressor gene in CRC. Therefore, the aim of the present study was to identify whether the miR‑27a could be a diagnostic and prognostic marker and the regulatory relationships between miR‑27a and FAM172A. We demonstrated high levels of miR‑27a expression in tissues of patients with CRC as well as in CRC cell lines. There was a positive correlation between the levels of miR‑27a and the poor overall survival of patients with CRC. Furthermore, elevated levels of miR‑27a expression were associated with TNM stage and distant metastasis. Increased expression or inhibition of miR‑27a promoted or inhibited the metastasis of CRC cell lines, respectively. Moreover, we showed that miR‑27a directly targets the 3'-untranslated region of FAM172A mRNA by using a dual-luciferase assay. Increased or decreased expression of FAM172A expression was observed when miR‑27a expression was inhibited or elevated in the CRC cells, respectively. In summary, our study showed that miR‑27a expression is a diagnostic and prognostic marker and correlates with overall survival of patients with CRC. Therefore, it may be a therapeutic approach for preventing metastasis of CRC to inhibit expression of miR‑27a or increase expression of FAM172A.

UHRF1: The key regulator of epigenetics and molecular target for cancer therapeutics

UHRF1 is a master regulator of epigenome as it coordinates DNA methylation and histone modifications. Compelling evidence suggests a strong link between UHRF1 overexpression and tumorigenesis, substantiating its ability to act as a potential biomarker for cancer diagnosis and prognosis. UHRF1 also mediates repair of damaged DNA that makes cancer cells resistant toward cytocidal drugs. Hence, understanding the molecular mechanism of UHRF1 regulation would help in developing cancer therapeutics. Natural compounds have shown applicability to downregulate UHRF1 leading to growth arrest and apoptosis in cancer cells.