ZNF281 contributes to the DNA damage response by controlling the expression of XRCC2 and XRCC4

Expression of ZNF281 in colorectal cancer correlates with response to radiotherapy and survival

BACKGROUND

The treatment of Colorectal cancer (CRC) is extremely complex and survival rates vary depending on the stage of the disease at the time of diagnosis. Neoadjuvant chemoradiotherapy (NACRT), is the conventional treatment for locally advanced rectal cancer (LARC); however, the resistance to chemoradiotherapy in LARC is difficult to predict.

MATERIALS AND METHODS

In this study, clinical data of 126 LARC patients were collected and analyzed, and relevant validation was performed using GEO database and in vitro and in vivo experiments, including Western blotting and Real-time quantitative PCR, immunohistochemistry, immunofluorescence, clonogenic cell survival assays, and nude-mouse xenograft models.

RESULTS

In patients with LARC who were treated with neoadjuvant radiotherapy (NART), higher ZNF281 expression in malignant tissue was associated with a poorer prognosis and lesser degree of tumor regression. Cell and mouse experiments have shown that ZNF281 reduces the damage caused by X-rays to CRC cells and tumors grown in mice.

CONCLUSION

We found that the expression of ZNF281 predicted the radiation response of CRC cells and suggested the prognosis of patients with LARC who received neoadjuvant radiation therapy.

Inhibition of the transcription factor ZNF281 by SUFU to suppress tumor cell migration

Although the Hedgehog (Hh) pathway plays an evolutionarily conserved role from Drosophila to mammals, some divergences also exist. Loss of Sufu, an important component of the Hh pathway, does not lead to an obvious developmental defect in Drosophila. However, in mammals, loss of SUFU results in serious disorder, even various cancers. This divergence suggests that SUFU plays additional roles in mammalian cells, besides regulating the Hh pathway. Here, we identify that the transcription factor ZNF281 is a novel binding partner of SUFU. Intriguingly, the Drosophila genome does not encode any homologs of ZNF281. SUFU is able to suppress ZNF281-induced tumor cell migration and DNA damage repair by inhibiting ZNF281 activity. Mechanistically, SUFU binds ZNF281 to mask the nuclear localization signal of ZNF281, culminating in ZNF281 cytoplasmic retention. In addition, SUFU also hampers the interactions between ZNF281 and promoters of target genes. Finally, we show that SUFU is able to inhibit ZNF281-induced tumor cell migration using an in vivo model. Taken together, these results uncover a Hh-independent mechanism of SUFU exerting the anti-tumor role, in which SUFU suppresses tumor cell migration through antagonizing ZNF281. Therefore, this study provides a possible explanation for the functional divergence of SUFU in mammals and Drosophila.

ZNF281 drives hepatocyte senescence in alcoholic liver disease by reducing HK2-stabilized PINK1/Parkin-mediated mitophagy

We investigated the role of zinc-finger protein 281 (ZNF281), a novel molecule, in ethanol-induced hepatocyte senescence and uncovered the potential mechanism. Real-time PCR, Western blot, immunofluorescence staining, and enzyme-linked immunosorbent assay were performed to explore the role of ZNF281 in hepatocyte senescence. ZNF281 expression was upregulated in both alcohol-fed mice livers and ethanol-treated hepatocytes. Silence of ZNF281 in hepatocytes using siRNA mitigated ethanol-caused decrease in cell viability and increased release of aspartate aminotransferase, alanine transaminase, and lactate dehydrogenase. ZNF281 siRNA reduced senescence-associated β-galactosidase-positive cells under ethanol exposure, abolished cell cycle arrest at G0/G1 phase, and diminished senescence-associated secretory phenotype and proinflammatory cytokines (IL-1β and IL-6) release. At molecular level, ZNF281 deficiency altered the expression profile of senescence-associated proteins including p53, p21, p16, high mobility group AT-hook 1, and phospho-histone H2A.X and telomerase-associated regulatory factors including telomerase reverse transcriptase, telomeric repeat binding factor 1 (TRF1), and TRF2. ZNF281 knockdown promoted hepatocyte recovery from ethanol-induced mitochondrial dysfunction and ROS production, which was correlated with rescuing HK2-PINK1/Parkin signalling-mediated mitophagy. Mechanistically, ZNF281 directly bound to 5'-GGCGGCGGGCGG-3' motif within HK2 promoter region and transcriptionally repressed HK2 expression. Systematic ZNF281 knockdown by adeno-associated virus encoding ZNF281 shRNA protected mice from alcohol feeding-caused hepatocyte injury and senescence. This study provides a novel factor ZNF281 as a driver of hepatocyte senescence during alcoholic liver disease.

ZNF281 Promotes Colon Fibroblast Activation in TGFβ1-Induced Gut Fibrosis

Crohn’s disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastrointestinal tract. Chronic inflammation is the main factor leading to intestinal fibrosis, resulting in recurrent stenosis, especially in CD patients. Currently, the underlying molecular mechanisms of fibrosis are still unclear. ZNF281 is a zinc-finger transcriptional regulator that has been characterized as an epithelial-to-mesenchymal transition (EMT)-inducing transcription factor, suggesting its involvement in the regulation of pluripotency, stemness, and cancer. The aim of this study is to investigate in vivo and in vitro the role of ZNF281 in intestinal fibrogenesis. Intestinal fibrosis was studied in vivo in C57BL/6J mice with chronic colitis induced by two or three cycles of administration of dextran sulfate sodium (DSS). The contribution of ZNF281 to gut fibrosis was studied in vitro in the human colon fibroblast cell line CCD-18Co, activated by the pro-fibrotic cytokine TGFβ1. ZNF281 was downregulated by siRNA transfection, and RNA-sequencing was performed to identify genes regulated by TGFβ1 in activated colon fibroblasts via ZNF281. Results showed a marked increase of ZNF281 in in vivo murine fibrotic colon as well as in in vitro human colon fibroblasts activated by TGFβ1. Moreover, abrogation of ZNF281 in TGFβ1-treated fibroblasts affected the expression of genes belonging to specific pathways linked to fibroblast activation and differentiation into myofibroblasts. We demonstrated that ZNF281 is a key regulator of colon fibroblast activation and myofibroblast differentiation upon fibrotic stimuli by transcriptionally controlling extracellular matrix (ECM) composition, remodeling, and cell contraction, highlighting a new role in the onset and progression of gut fibrosis.

Transcription factors in DNA damage response

Transcription factors (TFs) constitute a wide and highly diverse group of proteins capable of controlling gene expression. Their roles in oncogenesis, tumor progression, and metastasis have been established, but recently their role in the DNA damage response pathway (DDR) has emerged. Many of them can affect elements of canonical DDR pathways, modulating their activity and deciding on the effectiveness of DNA repair. In this review, we focus on the latest reports on the effects of two TFs with dual roles in oncogenesis and metastasis (hypoxia-inducible factor-1 α (HIF1α), proto-oncogene MYC) and three epithelial-mesenchymal transition (EMT) TFs (twist-related protein 1 (TWIST), zinc-finger E-box binding homeobox 1 (ZEB1), and zinc finger protein 281 (ZNF281)) associated with control of canonical DDR pathways.

ZFP281-BRCA2 prevents R-loop accumulation during DNA replication

R-loops are prevalent in mammalian genomes and involved in many fundamental cellular processes. Depletion of BRCA2 leads to aberrant R-loop accumulation, contributing to genome instability. Here, we show that ZFP281 cooperates with BRCA2 in preventing R-loop accumulation to facilitate DNA replication in embryonic stem cells. ZFP281 depletion reduces PCNA levels on chromatin and impairs DNA replication. Mechanistically, we demonstrate that ZFP281 can interact with BRCA2, and that BRCA2 is enriched at G/C-rich promoters and requires both ZFP281 and PRC2 for its proper recruitment to the bivalent chromatin at the genome-wide scale. Furthermore, depletion of ZFP281 or BRCA2 leads to accumulation of R-loops over the bivalent regions, and compromises activation of the developmental genes by retinoic acid during stem cell differentiation. In summary, our results reveal that ZFP281 recruits BRCA2 to the bivalent chromatin regions to ensure proper progression of DNA replication through preventing persistent R-loops.

R-loops are prevalent in mammalian genomes and involved in many fundamental cellular processes. Here, Wang et al. report that ZFP281 cooperates with BRCA2 in preventing R-loop accumulation to facilitate DNA replication in embryonic stem cells.

Circulating Tumor Cells in Breast Cancer Patients: A Balancing Act between Stemness, EMT Features and DNA Damage Responses

Circulating tumor cells (CTCs) traverse vessels to travel from the primary tumor to distant organs where they adhere, transmigrate, and seed metastases. To cope with these challenges, CTCs have reached maximal flexibility to change their differentiation status, morphology, migratory capacity, and their responses to genotoxic stress caused by metabolic changes, hormones, the inflammatory environment, or cytostatic treatment. A significant percentage of breast cancer cells are defective in homologous recombination repair and other mechanisms that protect the integrity of the replication fork. To prevent cell death caused by broken forks, alternative, mutagenic repair, and bypass pathways are engaged but these increase genomic instability. CTCs, arising from such breast tumors, are endowed with an even larger toolbox of escape mechanisms that can be switched on and off at different stages during their journey according to the stress stimulus. Accumulating evidence suggests that DNA damage responses, DNA repair, and replication are integral parts of a regulatory network orchestrating the plasticity of stemness features and transitions between epithelial and mesenchymal states in CTCs. This review summarizes the published information on these regulatory circuits of relevance for the design of biomarkers reflecting CTC functions in real-time to monitor therapeutic responses and detect evolving chemoresistance mechanisms.

Impact of the interplay between stemness features, p53 and pol iota on replication pathway choices

Using human embryonic, adult and cancer stem cells/stem cell-like cells (SCs), we demonstrate that DNA replication speed differs in SCs and their differentiated counterparts. While SCs decelerate DNA replication, differentiated cells synthesize DNA faster and accumulate DNA damage. Notably, both replication phenotypes depend on p53 and polymerase iota (POLι). By exploring protein interactions and newly synthesized DNA, we show that SCs promote complex formation of p53 and POLι at replication sites. Intriguingly, in SCs the translocase ZRANB3 is recruited to POLι and required for slow-down of DNA replication. The known role of ZRANB3 in fork reversal suggests that the p53–POLι complex mediates slow but safe bypass of replication barriers in SCs. In differentiated cells, POLι localizes more transiently to sites of DNA synthesis and no longer interacts with p53 facilitating fast POLι-dependent DNA replication. In this alternative scenario, POLι associates with the p53 target p21, which antagonizes PCNA poly-ubiquitination and, thereby potentially disfavors the recruitment of translocases. Altogether, we provide evidence for diametrically opposed DNA replication phenotypes in SCs and their differentiated counterparts putting DNA replication-based strategies in the spotlight for the creation of therapeutic opportunities targeting SCs.

ZNF-281 as the Potential Diagnostic Marker of Oral Squamous Cell Carcinoma

ZNF-281 is a zinc finger factor which can lead to cancer progression and metastasis. Its up-regulation reported in many cancers was correlated with metastasis and worsened patients' prognosis. This is the first study describing ZNF-281 in the context of OSCC. Oral tissue samples drawn from 66 OSCC patients and 36 control patients were collected to determine protein (using immunochemistry and the semi-quantitative H-score method) and mRNA expression levels (using the RT-qPCR reaction). Our aim was to assess the ZNF-281 expression level in OSCC and the control group. Moreover, we determined the impact of ZNF-281 on survival parameters and the association of diversified clinical parameters with ZNF-281 expression. Clinical factors such as grade, AJCC stage and radiotherapy have an impact on the ZNF-281 H-score level, whereas AJCC stage and grade have an influence on ZNF-281 mRNA expression. Our survival analysis indicated that the impact on overall survival is not statistically significant, and the prognostic potential of ZNF-281 is rather limited. Our findings show that both levels of the ZNF-281 H-score and mRNA are decreased in OSCC in comparison to normal tissue. Moreover, we estimated that the H-score can differentiate normal tissue from OSCC with a sensitivity of 97% and specificity of 93.7%.

ZNF-281 as the Potential Diagnostic Marker of Oral Squamous Cell Carcinoma

ZNF-281 is a zinc finger factor which can lead to cancer progression and metastasis. Its up-regulation reported in many cancers was correlated with metastasis and worsened patients' prognosis. This is the first study describing ZNF-281 in the context of OSCC. Oral tissue samples drawn from 66 OSCC patients and 36 control patients were collected to determine protein (using immunochemistry and the semi-quantitative H-score method) and mRNA expression levels (using the RT-qPCR reaction). Our aim was to assess the ZNF-281 expression level in OSCC and the control group. Moreover, we determined the impact of ZNF-281 on survival parameters and the association of diversified clinical parameters with ZNF-281 expression. Clinical factors such as grade, AJCC stage and radiotherapy have an impact on the ZNF-281 H-score level, whereas AJCC stage and grade have an influence on ZNF-281 mRNA expression. Our survival analysis indicated that the impact on overall survival is not statistically significant, and the prognostic potential of ZNF-281 is rather limited. Our findings show that both levels of the ZNF-281 H-score and mRNA are decreased in OSCC in comparison to normal tissue. Moreover, we estimated that the H-score can differentiate normal tissue from OSCC with a sensitivity of 97% and specificity of 93.7%.

Constructing and validating a diagnostic nomogram for multiple sclerosis via bioinformatic analysis

The purpose of this study was to identify biomarkers and construct a diagnostic prediction model for multiple sclerosis (MS). Microarray datasets in the Gene Expression Omnibus (GEO) were downloaded. Weighted gene coexpression analysis (WGCNA) was used to search for hub modules and biomarkers related to MS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to roughly define their biological functions and pathways. Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analysis were used to identify the diagnostic biomarkers and construct a nomogram. The calibration curve and receiver operating characteristic (ROC) curve were used to judge the diagnostic predictive ability. In addition, cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) algorithm was used to calculate the proportion of 22 kinds of immune cells. GSE41850 was used as the training set, and GSE17048 was used as the test set. WGCNA revealed one hub module containing 165 hub genes. Most of their biological functions and pathways are related to cell metabolism and immune cell activation. The diagnostic nomogram contained ARPC5, ROD1, UBQLN2, ZNF281, ABCA1 and FAS. The ROC curve and the calibration curve of the training set and test set confirmed that the nomogram had great prediction ability. In addition, monocytes and M0 macrophages were significantly different between MS patients and healthy people. The expression of ARPC5, ZNF281 and ABCA1 is correlated with M0 macrophages. The nomogram provides new insights and contributes to the accurate diagnosis of MS.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02675-1.

ZNF281-miR-543 Feedback Loop Regulates Transforming Growth Factor-β-Induced Breast Cancer Metastasis

Breast cancer is the most common malignancy, and metastasis is the main cause of cancer-associated mortality in women worldwide. Transforming growth factor-β (TGF-β) signaling, an inducer of epithelial-to-mesenchymal transition (EMT), plays an important role in breast cancer metastasis. Abnormal expression of miR-543 is associated with tumorigenesis and progression of various human cancers; however, the knowledge about the role of miR-543 in breast cancer metastasis is still unknown. In this study, we demonstrated that miR-543 inhibits the EMT-like phenotype and TGF-β-induced breast cancer metastasis both in vitro and in vivo by targeting ZNF281. ZNF281 transactivates the EMT-related transcription factor ZEB1 and Snail. Furthermore, both ZEB1 and Snail can transcriptionally suppress miR-543 expression. Taken together, our data uncover the ZNF281-miR-543 feedback loop and provide a mechanism to extend the understanding of TGF-β network complexity.

From single gene analysis to single cell profiling: a new era for precision medicine

Molecular profiling of DNA and RNA has provided valuable new insights into the genetic basis of non-malignant and malignant disorders, as well as an increased understanding of basic mechanisms that regulate human disease. Recent technological advances have enabled the analyses of alterations in gene-based structure or function in a comprehensive, high-throughput fashion showing that each tumor type typically exhibits distinct constellations of genetic alterations targeting one or more key cellular pathways that regulate cell growth and proliferation, evasion of the immune system, and other aspects of cancer behavior. These advances have important implications for future research and clinical practice in areas as molecular diagnostics, the implementation of gene or pathway-directed targeted therapy, and the use of such information to drive drug discovery. The 1st international and 32nd Annual Conference of Italian Association of Cell Cultures (AICC) conference wanted to offer the opportunity to match technological solutions and clinical needs in the era of precision medicine.

ZNF281 is recruited on DNA breaks to facilitate DNA repair by non-homologous end joining

Efficient repair of DNA double-strand breaks (DSBs) is of critical importance for cell survival. Although non-homologous end joining (NHEJ) is the most used DSBs repair pathway in the cells, how NHEJ factors are sequentially recruited to damaged chromatin remains unclear. Here, we identify a novel role for the zinc-finger protein ZNF281 in participating in the ordered recruitment of the NHEJ repair factor XRCC4 at damage sites. ZNF281 is recruited to DNA lesions within seconds after DNA damage through a mechanism dependent on its DNA binding domain and, at least in part, on poly-ADP ribose polymerase (PARP) activity. ZNF281 binds XRCC4 through its zinc-finger domain and facilitates its recruitment to damaged sites. Consequently, depletion of ZNF281 impairs the efficiency of the NHEJ repair pathway and decreases cell viability upon DNA damage. Survival analyses from datasets of commonly occurring human cancers show that higher levels of ZNF281 correlate with poor prognosis of patients treated with DNA-damaging therapies. Thus, our results define a late ZNF281-dependent regulatory step of NHEJ complex assembly at DNA lesions and suggest additional possibilities for cancer patients' stratification and for the development of personalised therapeutic strategies.

ZNF281/Zfp281 is a target of miR-1 and counteracts muscle differentiation

Defects in achieving a fully differentiated state and aberrant expression of genes and microRNAs (miRs) involved in differentiation are common to virtually all tumor types. Here, we demonstrate that the zinc finger transcription factor ZNF281/Zfp281 is down‐regulated during epithelial, muscle, and granulocytic differentiation in vitro. The expression of this gene is absent in terminally differentiated human tissues, in contrast to the elevated expression in proliferating/differentiating ones. Analysis of the 3’UTR of ZNF281/Zfp281 revealed the presence of numerous previously undescribed miR binding sites that were proved to be functional for miR‐mediated post‐transcriptional regulation. Many of these miRs are involved in differentiation pathways of distinct cell lineages. Of interest, ZNF281/Zfp281 is able to inhibit muscle differentiation promoted by miR‐1, of which ZNF281/Zfp281 is a direct target. These data suggest that down‐regulation of ZNF281/Zfp281 during differentiation in various cell types may occur through specific miRs whose expression is tissue‐restricted. In addition, we found that in rhabdomyosarcoma and leiomyosarcoma tumors, the expression of ZNF281/Zfp281 is significantly higher compared with normal counterparts. We extended our analysis to other human soft tissue sarcomas, in which the expression of ZNF281 is associated with a worse prognosis. In summary, we highlight here a new role of ZNF281/Zfp281 in counteracting muscle differentiation; its down‐regulation is at least in part mediated by miR‐1. The elevated expression of ZNF281/Zfp281 in soft tissue sarcomas warrants further analysis for its possible exploitation as a prognostic marker in this class of tumors.

EMT and Stemness-Key Players in Pancreatic Cancer Stem Cells

Metastasis and tumor progression are the major cause of death in patients suffering from pancreatic ductal adenocarcinoma. Tumor growth and especially dissemination are typically associated with activation of an epithelial-to-mesenchymal transition (EMT) program. This phenotypic transition from an epithelial to a mesenchymal state promotes migration and survival both during development and in cancer progression. When re-activated in pathological contexts such as cancer, this type of developmental process confers additional stemness properties to specific subsets of cells. Cancer stem cells (CSCs) are a subpopulation of cancer cells with stem-like features that are responsible for the propagation of the tumor as well as therapy resistance and cancer relapse, but also for circulating tumor cell release and metastasis. In support of this concept, EMT transcription factors generate cells with stem cell properties and mediate chemoresistance. However, their role in pancreatic ductal adenocarcinoma metastasis remains controversial. As such, a better characterization of CSC populations will be crucial in future development of therapies targeting these cells. In this review, we will discuss the latest updates on the mechanisms common to pancreas development and CSC-mediated tumor progression.

Expression of zinc finger transcription factors (ZNF143 and ZNF281) in serous borderline ovarian tumors and low-grade ovarian cancers

Low-grade ovarian cancers represent up to 8% of all epithelial ovarian carcinomas (EOCs). Recent studies demonstrated that epithelial-mesenchymal transition (EMT) is crucial for the progression of EOCs. EMT plays a key role in cancer invasion, metastasis formation and chemotherapy resistance. An array of novel EMT transcription factors from the zinc finger protein family have been described recently, among them zinc finger protein 143 (ZNF143) and zinc finger protein 281 (ZNF281). The study included tissue specimens from 42 patients. Based on histopathological examination of surgical specimens, eight lesions were classified as serous borderline ovarian tumors (sBOTs) and 34 as low-grade EOCs. The proportions of the ovarian tumors that tested positively for ZNF143 and ZNF281 were 90 and 57%, respectively. No statistically significant differences were found in the expressions of ZNF143 and ZNF281 transcription factors in SBOTs and low-grade EOCs. Considering the expression patterns for ZNF143 and ZNF281 identified in this study, both sBOTs and low-grade EOCs might undergo a dynamic epithelial-mesenchymal interconversion. The lack of statistically significant differences in the expressions of the zinc finger proteins in sBOTs and low-grade serous EOCs might constitute an evidence for common origin of these two tumor types.

XRCC2 (X-ray repair cross complementing 2)

XRCC2 is one of five somatic RAD51 paralogs, all of which have Walker A and B ATPase motifs. Each of the paralogs, including XRCC2, has a function in DNA double-strand break repair by homologous recombination (HR). However, their individual roles are not as well understood as that of RAD51 itself. The XRCC2 protein forms a complex (BCDX2) with three other RAD51 paralogs, RAD51B, RAD51C and RAD51D. It is believed that the BCDX2 complex mediates HR downstream of BRCA2 but upstream of RAD51, as XRCC2 is involved in the assembly of RAD51 into DNA damage foci. XRCC2 can bind DNA and, along with RAD51D, can promote homologous pairing in vitro. Consistent with its role in HR, XRCC2-deficient cells have increased levels of spontaneous chromosome instability, and exhibit hypersensitivity to DNA interstrand crosslinking agents such as mitomycin C and cisplatin as well as ionizing radiation, alkylating agents and aldehydes. XRCC2 also functions in promoting DNA replication and chromosome segregation. Biallelic mutation of XRCC2 (FANCU) causes the FA-U subtype of FA, while heterozygosity for deleterious mutations in XRCC2 may be associated with an increased breast cancer risk. XRCC2 appears to function 'downstream' in the FA pathway, since it is not required for FANCD2 monoubiquitination, which is the central step in the FA pathway. Clinically, the only known FA-U patient in the world exhibits severe congenital abnormalities, but had not developed, by seven years of age, the bone marrow failure and cancer that are often seen in patients from other FA complementation groups.

Radiation resistance of normal human astrocytes: the role of non-homologous end joining DNA repair activity

Radiotherapy is a common modality for treatment of brain cancers, but it can induce long-term physiological and cognitive deficits. The responses of normal human brain cells to radiation is not well understood. Astrocytes have been shown to have a variety of protective mechanisms against oxidative stress and have been shown to protect neurons. We investigated the response of cultured normal human astrocytes (NHAs) to X-ray irradiation. Following exposure to 10 Gy X-irradiation, NHAs exhibited DNA damage as indicated by the formation of γ-H2AX foci. Western blotting showed that NHAs displayed a robust increase in expression of non-homologous end joining DNA repair enzymes within 15 min post-irradiation and increased expression of homologous recombination DNA repair enzymes ~2 h post-irradiation. The cell cycle checkpoint protein p21/waf1 was upregulated from 6-24 h, and then returned to baseline. Levels of DNA repair enzymes returned to basal ~48 h post-irradiation. NHAs re-entered the cell cycle and proliferation was observed at 6 days. In contrast, normal human mesenchymal stem cells (MSCs) failed to upregulate DNA repair enzymes and instead displayed sustained upregulation of p21/waf1, a cell cycle checkpoint marker for senescence. Ectopic overexpression of Ku70 was sufficient to protect MSCs from sustained upregulation of p21/waf1 induced by 10 Gy X-rays. These findings suggest that increased expression of Ku70 may be a key mechanism for the radioresistance of NHAs, preventing their accelerated senescence from high-dose radiation. These results may have implications for the development of novel targets for radiation countermeasure development.

Transcription Factor ZNF281: A Novel Player in Intestinal Inflammation and Fibrosis

Background and aims: Recent evidences reveal the occurrence of a close relationship among epithelial to mesenchymal transition (EMT), chronic inflammation and fibrosis. ZNF281 is an EMT-inducing transcription factor (EMT-TF) involved in the regulation of pluripotency, stemness, and cancer. The aim of this study was to investigate in vitro, in vivo, and ex vivo a possible role of ZNF281 in the onset and progression of intestinal inflammation. A conceivable contribution of the protein to the development of intestinal fibrosis was also explored. Methods: Human colorectal adenocarcinoma cell line, HT29, and C57BL/6 mice were used for in vitro and in vivo studies. Mucosal biopsy specimens were taken during endoscopy from 29 pediatric patients with Crohn's disease (CD), 24 with ulcerative colitis (UC) and 16 controls. ZNF281 was knocked down by transfecting HT29 cells with 20 nM small interference RNA (siRNA) targeting ZNF281 (siZNF281). Results: We show for the first time that ZNF281 is induced upon treatment with inflammatory agents in HT29 cells, in cultured uninflamed colonic samples from CD patients and in DSS-treated mice. ZNF281 expression correlates with the disease severity degree of CD and UC patients. Silencing of ZNF281 strongly reduces both inflammatory (IL-8, IL-1beta, IL-17, IL-23) and EMT/fibrotic (SNAIL, Slug, TIMP-1, vimentin, fibronectin, and α-SMA) gene expression; besides, it abolishes the increase of extracellular-collagen level as well as the morphological modifications induced by inflammation. Conclusions: The identification of transcription factor ZNF281 as a novel player of intestinal inflammation and fibrosis allows a deeper comprehension of the pathogenetic mechanisms underlying inflammatory bowel disease (IBD) and provide a new target for their cure.

Cell death in cancer in the era of precision medicine

Tumors constitute a large class of diseases that affect different organs and cell lineages. The molecular characterization of cancers of a given type has revealed an extraordinary heterogeneity in terms of genetic alterations and DNA mutations; heterogeneity that is further highlighted by single-cell DNA sequencing of individual patients. To address these issues, drugs that specifically target genes or altered pathways in cancer cells are continuously developed. Indeed, the genetic fingerprint of individual tumors can direct the modern therapeutic approaches to selectively hit the tumor cells while sparing the healthy ones. In this context, the concept of precision medicine finds a vast field of application. In this review, we will briefly list some classes of target drugs (Bcl-2 family modulators, Tyrosine Kinase modulators, PARP inhibitors, and growth factors inhibitors) and discuss the application of immunotherapy in tumors (T cell-mediated immunotherapy and CAR-T cells) that in recent years has drastically changed the prognostic outlook of aggressive cancers. We will also consider how apoptosis could represent a primary end point in modern cancer therapy and how "classic" chemotherapeutic drugs that induce apoptosis are still utilized in therapeutic schedules that involve the use of target drugs or immunotherapy to optimize the antitumor response.

ZNF281 inhibits neuronal differentiation and is a prognostic marker for neuroblastoma

High-risk neuroblastomas (NBs) show undifferentiated/poorly differentiated morphology as a distinctive feature. We have identified the transcription factor ZNF281 as a factor that can counteract the neuronal differentiation of primary neurons in culture and NB cells. The expression of ZNF281 is inhibited by TAp73 and promoted by MYCN. In turn, ZNF281 inhibits the expression of GDNF and NRP2, two proteins associated with neuronal differentiation. In patients with NB, the expression of ZNF281 is higher in high-risk patients and is associated with worse prognosis. Understanding the molecular mechanisms that regulate neuronal differentiation is relevant for the identification of defects in this process that underlie the development of tumors such as NB, in which an aberrant differentiation arrest has occurred.

Derangement of cellular differentiation because of mutation or inappropriate expression of specific genes is a common feature in tumors. Here, we show that the expression of ZNF281, a zinc finger factor involved in several cellular processes, decreases during terminal differentiation of murine cortical neurons and in retinoic acid-induced differentiation of neuroblastoma (NB) cells. The ectopic expression of ZNF281 inhibits the neuronal differentiation of murine cortical neurons and NB cells, whereas its silencing causes the opposite effect. Furthermore, TAp73 inhibits the expression of ZNF281 through miR34a. Conversely, MYCN promotes the expression of ZNF281 at least in part by inhibiting miR34a. These findings imply a functional network that includes p73, MYCN, and ZNF281 in NB cells, where ZNF281 acts by negatively affecting neuronal differentiation. Array analysis of NB cells silenced for ZNF281 expression identified GDNF and NRP2 as two transcriptional targets inhibited by ZNF281. Binding of ZNF281 to the promoters of these genes suggests a direct mechanism of repression. Bioinformatic analysis of NB datasets indicates that ZNF281 expression is higher in aggressive, undifferentiated stage 4 than in localized stage 1 tumors supporting a central role of ZNF281 in affecting the differentiation of NB. Furthermore, patients with NB with high expression of ZNF281 have a poor clinical outcome compared with low-expressors. These observations suggest that ZNF281 is a controller of neuronal differentiation that should be evaluated as a prognostic marker in NB.

Zinc-finger proteins in health and disease

Zinc-finger proteins (ZNFs) are one of the most abundant groups of proteins and have a wide range of molecular functions. Given the wide variety of zinc-finger domains, ZNFs are able to interact with DNA, RNA, PAR (poly-ADP-ribose) and other proteins. Thus, ZNFs are involved in the regulation of several cellular processes. In fact, ZNFs are implicated in transcriptional regulation, ubiquitin-mediated protein degradation, signal transduction, actin targeting, DNA repair, cell migration, and numerous other processes. The aim of this review is to provide a comprehensive summary of the current state of knowledge of this class of proteins. Firstly, we describe the actual classification of ZNFs, their structure and functions. Secondly, we focus on the biological role of ZNFs in the development of organisms under normal physiological and pathological conditions.

Prognostic significance of XRCC4 expression in hepatocellular carcinoma

Background

Our previous investigations have shown that the variants of X-ray repair complementing 4 (XRCC4) may be involved in hepatocellular carcinoma (hepatocarcinoma) tumorigenesis. This study aimed to investigate the possible prognostic significance of XRCC4 expression for hepatocarcinoma patients and possible value for the selection of transarterial chemoembolization (TACE) treatment.

Materials and Methods

We conducted a hospital-based retrospective analysis (including 421 hepatocarcinoma cases) to analyze the effects of XRCC4 on hepatocarcinoma prognosis and TACE. The levels of XRCC4 expression were tested using immunohistochemistry. The sensitivity of cancer cells to anti-cancer drug doxorubicin was evaluated using the half-maximal inhibitory concentration (IC50).

Results

XRCC4 expression was significantly correlated with pathological features including tumor stage, liver cirrhosis, and micro-vessel density. XRCC4 expression was an independent prognostic factor of hepatocarcinoma, and TACE treatments had no effects on prognosis of hepatocarcinoma patients with high XRCC4 expression. More intriguingly, TACE improved the prognosis of hepatocarcinoma patients with low XRCC4 expression. Functionally, XRCC4 overexpression increased while XRCC4 knockdown reduced the IC50 of cancer cells to doxorubicin.

Conclusions

These results suggest that XRCC4 may be an independent prognostic factor for hepatocarcinoma patients, and that decreasing XRCC4 expression may be beneficial for post-operative adjuvant TACE treatment in hepatocarcinoma.

GSK-3β phosphorylation-dependent degradation of ZNF281 by β-TrCP2 suppresses colorectal cancer progression

Zinc finger protein 281 (ZNF281) has been recently shown to be critical for CRC progression. However, the immediate upstream regulators of ZNF281 remain unclear. Here we reported that the E3 ligase the β-transducin repeat-containing protein 2 (β-TrCP2) governs the ubiquitination and degradation of ZNF281. In human CRC specimens, endogenous β-TrCP2 were inversely correlated with ZNF281. Beta-TrCP2 reversed the phenotype of CRC cell with overexpressed ZNF281. Moreover, we found that glycogen synthase kinase 3β (GSK-3β), not GSK-α, could bind to and phosphorylate ZNF281 at one consensus motif (TSGEHS; phosphorylation site is shown in italics), which promotes the interaction of ZNF281 with β-TrCP2, not β-TrCP1, and leads to the subsequent ubiquitination and degradation of phosphorylated ZNF281. A mutant of ZNF281 (ZNF281-S638A) is much more stable than wild-type ZNF281 because ZNF281-S638A mutant abolishes the phosphorylation by GSK-3β and can not be ubiquitinated and degraded by β-TrCP2. Conversely, ZNF281 transcriptionally repressed the expression of β-TrCP2, indicating a negative feedback loop between ZNF281 and β-TrCP2 in CRC cells. These findings suggest that the turnover of ZNF281 by β-TrCP2 might provide a potentially novel treatment for patients with CRC.

ZNF281 Promotes Growth and Invasion of Pancreatic Cancer Cells by Activating Wnt/β-Catenin Signaling

BACKGROUND

Zinc finger protein 281 (ZNF281) has been identified to be involved in embryonic stem cell differentiation and tissue development. Also, ZNF281 was found in various types of cancers. However, its biological functions and clinical significance in pancreatic cancer remain elusive.

AIMS

To explore the role of ZNF281 in pancreatic cancer cells proliferation and invasion.

METHODS

ZNF281 expression was examined in public database Oncomine and cBioPortal. The correlation between ZNF281 and clinicopathological features was measured, and Kaplan-Meier method was used to measure the overall survival and recurrence-free survival in the TCGA cohort. Ectopic expression and knockdown of ZNF281 were performed to measure the impact on cell proliferation and invasion. Western blot and immunoprecipitation were further used to identify the ZNF281 interacting proteins. Topflash luciferase assay was used to detect the Wnt/β-catenin signaling activation.

RESULTS

ZNF281 was predominantly up-regulated in pancreatic cancer tissues and significantly associated with advanced stage. Meanwhile, the high expression of ZNF281 indicated shorter overall survival and recurrence-free survival and ZNF281 could be an independent prognostic factor of pancreatic cancer. ZNF281 promoted cell proliferation and invasion in vitro. Mechanically, ZNF281 activated Wnt/β-catenin signaling and induced the downstream gene expression by directly binding with β-catenin and decreasing the polyubiquitination.

CONCLUSIONS

ZNF281 promotes pancreatic cancer cells proliferation and invasion by interacting and up-regulating β-catenin, highlighting the role of ZNF281 in pancreatic cancer progression.

New factors in mammalian DNA repair-the chromatin connection

In response to DNA damage mammalian cells activate a complex network of stress response pathways collectively termed DNA damage response (DDR). DDR involves a temporary arrest of the cell cycle to allow for the repair of the damage. DDR also attenuates gene expression by silencing global transcription and translation. Main function of DDR is, however, to prevent the fixation of debilitating changes to DNA by activation of various DNA repair pathways. Proper execution of DDR requires careful coordination between these interdependent cellular responses. Deregulation of some aspects of DDR orchestration is potentially pathological and could lead to various undesired outcomes such as DNA translocations, cellular transformation or acute cell death. It is thus critical to understand the regulation of DDR in cells especially in the light of a strong linkage between the DDR impairment and the occurrence of common human diseases such as cancer. In this review we focus on recent advances in understanding of mammalian DNA repair regulation and a on the function of PAXX/c9orf142 and ZNF281 proteins that recently had been discovered to play a role in that process. We focus on regulation of double-strand DNA break (DSB) repair via the non-homologous end joining pathway, as unrepaired DSBs are the primary cause of pathological cellular states after DNA damage. Interestingly these new factors operate at the level of chromatin, which reinforces a notion of a central role of chromatin structure in the regulation of cellular DDR regulation.

DNA repair and aging: the impact of the p53 family

Cells are constantly exposed to endogenous and exogenous factors that threaten the integrity of their DNA. The maintenance of genome stability is of paramount importance in the prevention of both cancer and aging processes. To deal with DNA damage, cells put into operation a sophisticated and coordinated mechanism, collectively known as DNA damage response (DDR). The DDR orchestrates different cellular processes, such as DNA repair, senescence and apoptosis. Among the key factors of the DDR, the related proteins p53, p63 and p73, all belonging to the same family of transcription factors, play multiple relevant roles. Indeed, the members of this family are directly involved in the induction of cell cycle arrest that is necessary to allow the cells to repair. Alternatively, they can promote cell death in case of prolonged or irreparable DNA damage. They also take part in a more direct task by modulating the expression of core factors involved in the process of DNA repair or by directly interacting with them. In this review we will analyze the fundamental roles of the p53 family in the aging process through their multifaceted function in DDR.

Dynamic Protein Interactions of the Polycomb Repressive Complex 2 during Differentiation of Pluripotent Cells

Polycomb proteins assemble to form complexes with important roles in epigenetic regulation. The Polycomb Repressive Complex 2 (PRC2) modulates the di- and tri-methylation of lysine 27 on histone H3, each of which are associated with gene repression. Although three subunits, EZH1/2, SUZ12, and EED, form the catalytic core of PRC2, a wider group of proteins associate with low stoichiometry. This raises the question of whether dynamic variation of the PRC2 interactome results in alternative forms of the complex during differentiation. Here we compared the physical interactions of PRC2 in undifferentiated and differentiated states of NTERA2 pluripotent embryonic carcinoma cells. Label-free quantitative proteomics was used to assess endogenous immunoprecipitation of the EZH2 and SUZ12 subunits of PRC2. A high stringency data set reflecting the endogenous state of PRC2 was produced that included all previously reported core and associated PRC2 components, and several novel interacting proteins. Comparison of the interactomes obtained in undifferentiated and differentiated cells revealed candidate proteins that were enriched in complexes isolated from one of the two states. For example, SALL4 and ZNF281 associate with PRC2 in pluripotent cells, whereas PCL1 and SMAD3 preferentially associate with PRC2 in differentiating cells. Analysis of the mRNA and protein levels of these factors revealed that their association with PRC2 correlated with their cell state-specific expression. Taken together, we propose that dynamic changes to the PRC2 interactome during differentiation may contribute to directing its activity during cell fate transitions.