Analysis of UHRF1 expression in human ovarian cancer tissues and its regulation in cancer cell growth

SHMT2 Drives the Progression of Colorectal Cancer by Regulating UHRF1 Expression

INTRODUCTION

Serine hydroxymethyltransferase 2 (SHMT2) has a critical role in serine-glycine metabolism to drive cancer cell proliferation. Yet, the function of SHMT2 in tumorigenesis, especially in human colorectal cancer (CRC) progression, remains largely unclear.

MATERIALS AND METHODS

CRC and paired normal samples were collected in the Department of Colorectal Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, and assessed by real-time polymerase chain reaction (qPCR) analysis, western blot (WB), and immunohistochemistry (IHC). Moreover, SHMT2 expression in human CRC cells was identified by qPCR and WB. The CRC cell proliferation, migration, and invasion after SHMT2 knockdown were explored through in vitro and in vivo assays. mRNA-seq assays were used to investigate the underlying mechanisms behind the SHMT2 function.

RESULTS

It was found that SHMT2 mRNA and protein were overexpressed in CRC tissue compared to the levels in normal mucosa. Positive expression of SHMT2 was significantly correlated with TNM stage and lymph node metastasis, and elevated expression of SHMT2 resulted as an independent prognostic factor in patients with CRC. SHMT2 knockdown impaired the proliferation of CRC in vitro and in vivo and induced cell cycle arrest by regulating UHRF1 expression.

CONCLUSION

Taken together, our findings reveal that UHRF1 is a novel target gene of SHMT2, which can be used as a potential therapeutic strategy for CRC therapy.

Structure-based screening combined with computational and biochemical analyses identified the inhibitor targeting the binding of DNA Ligase 1 to UHRF1

The accumulation of epigenetic alterations is one of the major causes of tumorigenesis. Aberrant DNA methylation patterns cause genome instability and silencing of tumor suppressor genes in various types of tumors. Therefore, drugs that target DNA methylation-regulating factors have great potential for cancer therapy. Ubiquitin-like containing PHD and RING finger domain 1 (UHRF1) is an essential factor for DNA methylation maintenance. UHRF1 is overexpressed in various cancer cells and down-regulation of UHRF1 in these cells reactivates the expression of tumor suppressor genes, thus UHRF1 is a promising target for cancer therapy. We have previously shown that interaction between the tandem Tudor domain (TTD) of UHRF1 and DNA ligase 1 (LIG1) di/trimethylated on Lys126 plays a key role in the recruitment of UHRF1 to replication sites and replication-coupled DNA methylation maintenance. An arginine binding cavity (Arg-binding cavity) of the TTD is essential for LIG1 interaction, thus the development of inhibitors that target the Arg-binding cavity could potentially repress UHRF1 function in cancer cells. To develop such an inhibitor, we performed in silico screening using not only static but also dynamic metrics based on all-atom molecular dynamics simulations, resulting in efficient identification of 5-amino-2,4-dimethylpyridine (5A-DMP) as a novel TTD-binding compound. Crystal structure of the TTD in complex with 5A-DMP revealed that the compound stably bound to the Arg-binding cavity of the TTD. Furthermore, 5A-DMP inhibits the full-length UHRF1:LIG1 interaction in Xenopus egg extracts. Our study uncovers a UHRF1 inhibitor which can be the basis of future experiments for cancer therapy.

Non-histone methylation of SET7/9 and its biological functions

BACKGROUND

(su(var)-3-9,enhancer-of-zeste,trithorax) domain-containing protein 7/9 (SET7/9) is a member of the protein lysine methyltransferases (PLMTs or PKMTs) family. It contains a SET domain. Recent studies demonstrate that SET7/9 methylates both lysine 4 of histone 3 (H3-K4) and lysine(s) of non-histone proteins, including transcription factors, tumor suppressors, and membrane-associated receptors.

OBJECTIVE

This article mainly reviews the non-histone methylation effects of SET7/9 and its functions in tumorigenesis and development.

METHODS

PubMed was screened for this information.

RESULTS

SET7/9 plays a key regulatory role in various biological processes such as cell proliferation, transcription regulation, cell cycle, protein stability, cardiac morphogenesis, and development. In addition, SET7/9 is involved in the pathogenesis of hair loss, breast cancer progression, human carotid plaque atherosclerosis, chronic kidney disease, diabetes, obesity, ovarian cancer, prostate cancer, hepatocellular carcinoma, and pulmonary fibrosis.

CONCLUSION

SET7/9 is an important methyltransferase, which can catalyze the methylation of a variety of proteins. Its substrates are closely related to the occurrence and development of tumors.

Converging genetic and epigenetic drivers of paediatric acute lymphoblastic leukaemia identified by an information-theoretic analysis

In cancer, linking epigenetic alterations to drivers of transformation has been difficult, in part because DNA methylation analyses must capture epigenetic variability, which is central to tumour heterogeneity and tumour plasticity. Here, by conducting a comprehensive analysis, based on information theory, of differences in methylation stochasticity in samples from patients with paediatric acute lymphoblastic leukaemia (ALL), we show that ALL epigenomes are stochastic and marked by increased methylation entropy at specific regulatory regions and genes. By integrating DNA methylation and single-cell gene-expression data, we arrived at a relationship between methylation entropy and gene-expression variability, and found that epigenetic changes in ALL converge on a shared set of genes that overlap with genetic drivers involved in chromosomal translocations across the disease spectrum. Our findings suggest that an epigenetically driven gene-regulation network, with UHRF1 (ubiquitin-like with PHD and RING finger domains 1) as a central node, links genetic drivers and epigenetic mediators in ALL.

Developmental and hormonal regulation of ubiquitin-like with plant homeodomain and really interesting new gene finger domains 1 gene expression in ovarian granulosa and theca cells of cattle

Ubiquitin-like with plant homeodomain and really interesting new gene finger domains 1 (UHRF1) is a multi-domain nuclear protein that plays an important role in epigenetics and tumorigenesis, but its role in normal ovarian follicle development remains unknown. Thus, the present study evaluated if UHRF1 mRNA abundance in bovine follicular cells is developmentally and hormonally regulated, and if changes in UHRF1 are associated with changes in DNA methylation in follicular cells. Abundance of UHRF1 mRNA was greater in granulosa cells (GC) and theca cells (TC) from small (<6 mm) than large (≥8 mm) follicles and was greater in small-follicle GC than TC. In GC and TC, fibroblast growth factor 9 (FGF9) treatment increased (P < 0.05) UHRF1 expression by 2-fold. Also, luteinizing hormone (LH) and insulin-like growth factor 1 (IGF1) increased (P < 0.05) UHRF1 expression in TC by 2-fold, and forskolin (an adenylate cyclase inducer) alone or combined with IGF1 increased (P < 0.05) UHRF1 expression by 3-fold. An E2F transcription factor inhibitor (E2Fi) decreased (P < 0.05) UHRF1 expression by 44% in TC and by 99% in GC. Estradiol, progesterone, and dibutyryl-cAMP decreased (P < 0.05) UHRF1 mRNA abundance in GC. Treatment of GC with follicle-stimulating hormone (FSH) alone had no effect but when combined with IGF1 enhanced the UHRF1 mRNA abundance by 2.7-fold. Beauvericin (a mycotoxin) completely inhibited the FSH plus IGF1-induced UHRF1 expression in small-follicle GC. Treatments that increased UHRF1 mRNA (i.e., FGF9) in GC tended to decrease (by 63%; P < 0.10) global DNA methylation, and those that decreased UHRF1 mRNA (i.e., E2Fi) in GC tended to increase (by 2.4-fold; P < 0.10) global DNA methylation. Collectively, these results suggest that UHRF1 expression in both GC and TC is developmentally and hormonally regulated, and that UHRF1 may play a role in follicular growth and development as well as be involved in ovarian epigenetic processes.

Methylation of UHRF1 by SET7 is essential for DNA double-strand break repair

Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is a key epigenetic regulator of DNA methylation maintenance and heterochromatin formation. The roles of UHRF1 in DNA damage repair also have been emphasized in recent years. However, the regulatory mechanism of UHRF1 remains elusive. In this study, we showed that UHRF1 is methylated by SET7 and demethylation is catalyzed by LSD1. In addition, methylation of UHRF1 is induced in response to DNA damage and its phosphorylation in S phase is a prerequisite for interaction with SET7. Furthermore, UHRF1 methylation catalyzes the conjugation of polyubiquitin chains to PCNA and promotes homologous recombination for DNA repair. SET7-mediated UHRF1 methylation is also shown to be essential for cell viability against DNA damage. Our data revealed the regulatory mechanism underlying the UHRF1 methylation status by SET7 and LSD1 in double-strand break repair pathway.

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.

ATP-binding cassette transporter A7 accelerates epithelial-to-mesenchymal transition in ovarian cancer cells by upregulating the transforming growth factor-β signaling pathway

Ovarian cancer (OC) has the highest fatality rates of all gynecological malignancies worldwide. The epithelial-to-mesenchymal transition (EMT) serves an essential role in the progression of OC. An improved understanding of the molecular mechanism underlying EMT in OC may increase the survival rate. ATP-binding cassette transporter A7 (ABCA7) is a candidate regulator of OC progression. However, the role of ABCA7 in OC is unclear. Using the PROGgeneV2 platform, the present study revealed that increased expression of ABCA7 is associated with poor outcomes in OC. The expression of ABCA7 was higher in OC tissues than in adjacent noncancerous tissues. ABCA7-knockdown decreased the migration of OC cells and the activation of mothers against decapentaplegic homolog 4 (SMAD4). Notably, downregulation of ABCA7 also increased the expression of an epithelial marker (E-cadherin) and decreased that of a mesenchymal marker (N-cadherin). In addition, the decreased expression of SMAD4 and EMT markers induced by ABCA7 depletion could be rescued by transforming growth factor β1 (TGF-β1) stimulation. Overall, these findings suggested that ABCA7 accelerates EMT in OC by upregulating the TGF-β signaling pathway.

Targeting the SET and RING-associated (SRA) domain of ubiquitin-like, PHD and ring finger-containing 1 (UHRF1) for anti-cancer drug development

Ubiquitin-like containing PHD Ring Finger 1 (UHRF1) is a multi-domain protein with a methyl-DNA binding SRA (SET and RING-associated) domain, required for maintenance DNA methylation mediated by DNMT1. Primarily expressed in proliferating cells, UHRF1 is a cell-cycle regulated protein that is required for S phase entry. Furthermore, UHRF1 participates in transcriptional gene regulation by connecting DNA methylation to histone modifications. Upregulation of UHRF1 may serve as a biomarker for a variety of cancers; including breast, gastric, prostate, lung and colorectal carcinoma. To this end, overexpression of UHRF1 promotes cancer metastasis by triggering aberrant patterns of DNA methylation, and subsequently, silencing tumor suppressor genes. Various small molecule effectors of UHRF1 have been reported in the literature, although the mechanism of action may not be fully characterized. Small molecules that potentially bind to the SRA domain may affect the ability of UHRF1 to bind hemimethylated DNA; thereby reducing aberrant DNA methylation. Therefore, in a subset of cancers, small molecule UHRF1 inhibitors may restore normal gene expression and serve as useful anti-cancer therapeutics.

The effect of CA125 on metastasis of ovarian cancer: old marker new function

CA125 has been used extensively to screen for neoplasms, especially in ovarian cancer. The serum CA125 level can be used as a better prognosis evaluation and it may dynamic monitoring the disease progression. We explored the effect of CA125 on ovarian cancer cell migration and its underlying mechanism. Transwell assays showed that exposure to 0.2 μg/ml or 0.4 μg/ml CA125 for 48 h increased migration of A2780 and OVCAR-3 ovarian cancer cells. This effect of CA125 was blocked addition of 200 ng/ml DKK-1, a Wnt pathway inhibitor. Conversely, addition of CA125 reversed the inhibitory effect of Wnt inhibition in A2780 cells pretreated with DKK-1. Examination of CA125 levels in serum from 97 ovarian cancer patients revealed no relationship between a patient's age or CA125 level currently used clinically for ovarian cancer diagnosis and metastasis. However, using receiver operating characteristic (ROC) curves, we identified a new cut-off value for the serum CA125 concentration (82.9 U/ml) that is predictive of metastasis. The area under the curve is 0.632. This new cut-off value has the potential to serve as a clinically useful indicator of metastasis in ovarian cancer patients.

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.

CDDO-Me reveals USP7 as a novel target in ovarian cancer cells

Deubiquitinating enzyme USP7 has been involved in the pathogenesis and progression of several cancers. Targeting USP7 is becoming an attractive strategy for cancer therapy. In this study, we identified synthetic triterpenoid C-28 methyl ester of 2-cyano-3, 12-dioxoolen-1, 9-dien-28-oic acid (CDDO-Me) as a novel inhibitor of USP7 but not of other cysteine proteases such as cathepsin B and cathepsin D. CDDO-Me inhibits USP7 activity via a mechanism that is independent of the presence of α, β-unsaturated ketones. Molecular docking studies showed that CDDO-Me fits well in the ubiquitin carboxyl terminus-binding pocket on USP7. Given that CDDO-Me is known to be effective against ovarian cancer cells, we speculated that CDDO-Me may target USP7 in ovarian cancer cells. We demonstrated that ovarian cancer cells have higher USP7 expression than their normal counterparts. Knockdown of USP7 inhibits the proliferation of ovarian cancer cells both in vitro and in vivo. Using the cellular thermal shift assay and the drug affinity responsive target stability assay, we further demonstrated that CDDO-Me directly binds to USP7 in cells, which leads to the decrease of its substrates such as MDM2, MDMX and UHRF1. CDDO-Me suppresses ovarian cancer tumor growth in an xenograft model. In conclusion, we demonstrate that USP7 is a novel target of ovarian cancer cells; targeting USP7 may contribute to the anti-cancer effect of CDDO-Me. The development of novel USP7 selective compounds based on the CDDO-Me-scaffold warrants further investigation.

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.

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.

Screening of potentially crucial genes and regulatory factors involved in epithelial ovarian cancer using microarray analysis

The present study aimed to screen potential genes implicated in epithelial ovarian cancer (EOC) and to further understand the molecular pathogenesis of EOC. In order to do this, datasets GSE14407 (containing 12 human ovarian cancer epithelia samples and 12 normal epithelia samples) and GSE29220 (containing 11 salivary transcriptomes from ovarian cancer patients with serous papillary adenocarcinoma and 11 matched controls) were obtained from the Gene Expression Omnibus. Differentially expressed genes (DEGs) within these datasets were screened using the Linear Models for Microarray Data package, and potential gene functions were predicted by functional and pathway enrichment analyses. Additionally, module analysis of protein-protein interaction networks was performed using MCODE software in Cytoscape. The potential microRNAs (miRNAs/miRs) and transcription factors (TFs) regulating DEGs were also analyzed, and the integrated TF-DEG and miRNA-DEG regulatory networks were visualized with Cytoscape. In total, 31 upregulated DEGs and 64 downregulated DEGs were screened. The upregulated DEGs, such as centromere protein F (CENPF) and ubiquitin like with PHD and ring finger domains 1 (UHRF1), were significantly associated with the cell cycle and were regulated by the TF nuclear transcription factor Y (NF-Y). CENPF was modulated by miR-373, and UHRF1 was regulated by miR-146a. The downregulated DEGs, such as aldehyde dehydrogenase 1 family member A2 (ALDH1A2), were distinctly involved in the response to estrogen stimulus and modulated by tumor protein 53 (TP53); protocadherin 9 (PCDH9) was regulated by TP53, miR-92b-3p and miR-137. The DEGs, including CENPF, UHRF1, ALDH1A2 and PCDH9, and a set of gene regulators, including all NFY genes, TP53, miR-373, miR-146a, miR-92b-3p and miR-137, may be involved in the pathogenesis of EOC.

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.

Elevated UHRF1 expression contributes to poor prognosis by promoting cell proliferation and metastasis in hepatocellular carcinoma

Ubiquitin-like with plant homeodomain and ring finger domains, 1 (UHRF1) is overexpressed in a variety of tumor tissues and is negatively correlated with prognosis of patients with cancers, yet so far, a comprehensive study of UHRF1 in hepatocellular carcinoma (HCC) has not been conducted. The present study was designed to explore the expression of UHRF1, associated clinical implications, and its possible functions in HCC. Reverse transcription-polymerase chain reaction and immunohistochemical staining were used to detect UHRF1 expression in HCC specimens including cancerous and noncancerous tissues. Associations of UHRF1 expression with demographic and clinicopathologic features in HCC were analyzed, and the effects of RNA interference of UHRF1 on cell proliferation, cell cycle, apoptosis, and migration were investigated in vitro and in vivo. UHRF1 mRNA and protein expression were both upregulated and negatively correlated with prognosis in HCC patients. Furthermore, inhibition of proliferation, migration, invasion, and epithelial-mesenchymal transition progression were observed in vitro and in vivo after UHRF1 knockdown, moreover, G2/M arrest was detected in HCC cells. In conclusion, elevated UHRF1 expression contributes to poor prognosis by promoting cell proliferation and metastasis in HCC.

UHRF1 gene silencing inhibits cell proliferation and promotes cell apoptosis in human cervical squamous cell carcinoma CaSki cells

BACKGROUND

Up-regulation of UHRF1 has been observed in a variety of cancers and appears to serve as an independent prognostic factor.

OBJECTIVE

To explore the effect of UHRF1 gene silencing on apoptosis and proliferation of cervical squamous cell carcinoma (CSCC) CaSki cells.

METHODS

This study consisted of 47 CSCC tissues and 40 normal cervical tissues. The CaSki cells were assigned into Blank group (CaSki cells not transfected), NC group (CaSki cells transfected with control siRNA), and UHRF1 Silence group (CaSki cells transfected with UHRF1 siRNA). qRT-PCR and Western blot were used for UHRF1 mRNA and protein expressions, CKK-8 assay for cell proliferation, flow cytometry for cell cycle and apoptosis, Western blot for expressions of apoptosis-related proteins. Nude mice tumor transplant experiment was performed.

RESULTS

UHRF1 exhibited higher mRNA and protein expressions in the CSCC tissues than normal cervical tissues (both P < 0.05). The cell proliferation ability in the UHRF1 Silence group was reduced when compared with the Blank group and the NC group, the cells at S-G2M stage in the UHRF1 Silence group were dropped when compared with the Blank group and the NC group (P < 0.05), while the cells at G0/G1 stage were elevated (P < 0.05), and the proportion of Annexin V positive cells in the UHRF1 Silence group was increased in comparison with the Blank group and the NC group (P < 0.05). Nude mice tumor transplant experiment indicated that the growth rate and weight of tumor in the Blank group and NC group was higher and heavier than the UHRF1 Silence group (P < 0.05).

CONCLUSION

UHRF1 showed a high expression in CSCC and UHRF1 silencing can reduce proliferation and enhance apoptosis of the CaSki cells.