The epigenetic factor BORIS/CTCFL regulates the NOTCH3 gene expression in cancer cells

Study of the cyto- and genotoxic activity of water from the Kapshagai reservoir (Kazakhstan) on laboratory mice

Chemical compounds in the environment, which exhibit toxic and genotoxic activity, increase the mutational pressure on biota. This study aimed to investigate the genotoxic, mutagenic, and toxic effects of water from the Ile River and the Kapshagai Reservoir, both sites of active economic activities. Cytogenetic analysis of bone marrow from mice exposed to water samples from the Ile River and the Kapshagai Reservoir revealed a statistically significant increase in aberrant (p<0.05) and polyploid cells (p<0.01), as well as a decrease in the mitotic index (p<0.001), compared to the negative control. The water samples caused statistically significant increases in single- and double-strand DNA breaks in cells across various organs in the experimental mice compared to unexposed animals (p<0.001). These observations suggest the existence of chemical compounds within the water samples from the Kapshagai Reservoir and the Ile River, which exhibit genotoxic, mutagenic, and toxic properties.

BORIS/CTCFL epigenetically reprograms clustered CTCF binding sites into alternative transcriptional start sites

BACKGROUND

Pervasive usage of alternative promoters leads to the deregulation of gene expression in carcinogenesis and may drive the emergence of new genes in spermatogenesis. However, little is known regarding the mechanisms underpinning the activation of alternative promoters.

RESULTS

Here we describe how alternative cancer-testis-specific transcription is activated. We show that intergenic and intronic CTCF binding sites, which are transcriptionally inert in normal somatic cells, could be epigenetically reprogrammed into active de novo promoters in germ and cancer cells. BORIS/CTCFL, the testis-specific paralog of the ubiquitously expressed CTCF, triggers the epigenetic reprogramming of CTCF sites into units of active transcription. BORIS binding initiates the recruitment of the chromatin remodeling factor, SRCAP, followed by the replacement of H2A histone with H2A.Z, resulting in a more relaxed chromatin state in the nucleosomes flanking the CTCF binding sites. The relaxation of chromatin around CTCF binding sites facilitates the recruitment of multiple additional transcription factors, thereby activating transcription from a given binding site. We demonstrate that the epigenetically reprogrammed CTCF binding sites can drive the expression of cancer-testis genes, long noncoding RNAs, retro-pseudogenes, and dormant transposable elements.

CONCLUSIONS

Thus, BORIS functions as a transcription factor that epigenetically reprograms clustered CTCF binding sites into transcriptional start sites, promoting transcription from alternative promoters in both germ cells and cancer cells.

Association of mutation and expression of the brother of the regulator of imprinted sites (BORIS) gene with breast cancer progression

INTRODUCTION

The BORIS, 11 zinc-finger transcription factors, is a member of the cancer-testis antigen (CTA) family. It is mapped to chromosome number 20q13.2 and this region is genetically linked to the early onset of breast cancer. The current study analyzed the correlation between BORIS mutations and the expression of the protein in breast cancer cases.

MATERIALS AND METHODS

A population-based study including a total of 155 breast cancer tissue samples and an equal number of normal adjacent tissues from Indian female breast cancer patients was carried out. Mutations of the BORIS gene were detected by polymerase chain reaction-single standard confirmation polymorphisms (PCR-SSCP) and automated DNA sequencing and by immunohistochemistry for BORIS protein expression were performed. The observed findings were correlated with several clinicopathological parameters to find out the clinical relevance of associations.

RESULTS

Of all the cases 16.12% (25/155) showed mutations in the BORIS gene. The observed mutations present on codon 329 are missense, leading to Val> Ile (G>A) change on exon 5 of the BORIS gene. A significant association was observed between mutations of the BORIS gene and some clinicopathological features like nodal status (p = 0.013), estrogen receptor (ER) expression (p = 0.008), progesterone receptor (PR) expression (p = 0.039), clinical stage (p = 0.010) and menopausal status (p = 0.023). The protein expression analysis showed 20.64% (32/155) samples showing low or no expression (+), 34.19% (53/155) with moderate expression (++), and 45.17% (70/155) showing high expression (+++) of BORIS protein. A significant association was observed between the expression of BORIS protein and clinicopathological features like clinical stage (p = 0.013), nodal status (p = 0.049), ER expression (p = 0.039), and PR expression (p = 0.027). When mutation and protein expression were correlated in combination with clinicopathological parameters a significant association was observed in the category of high (+++) level of BORIS protein expression (p = 0.017).

CONCLUSION

The BORIS mutations and high protein expression occur frequently in carcinoma of the breast suggesting their association with the onset and progression of breast carcinoma. Further, the BORIS has the potential to be used as a biomarker.

Notch3 regulates Mybl2 via HeyL to limit proliferation and tumor initiation in breast cancer

Notch signaling is a conserved signaling pathway that participates in many aspects of mammary gland development and homeostasis, and has extensively been associated with breast tumorigenesis. Here, to unravel the as yet debated role of Notch3 in breast cancer development, we investigated its expression in human breast cancer samples and effects of its loss in mice. Notch3 expression was very weak in breast cancer cells and was associated with good patient prognosis. Interestingly, its expression was very strong in stromal cells of these patients, though this had no prognostic value. Mechanistically, we demonstrated that Notch3 prevents tumor initiation via HeyL-mediated inhibition of Mybl2, an important regulator of cell cycle. In the mammary glands of Notch3-deficient mice, we observed accelerated tumor initiation and proliferation in a MMTV-Neu model. Notch3-null tumors were enriched in Mybl2 mRNA signature and protein expression. Hence, our study reinforces the anti-tumoral role of Notch3 in breast tumorigenesis.

The function of brother of the regulator of imprinted sites in cancer development

As Douglas Hanahan and Robert Weinberg compiled, there are nine hallmarks of cancer that are conducive to cancer cell development and survival. Previous studies showed that brother of the regulator of imprinted sites (BORIS) might promote cancer progression through these aspects. The competition between BORIS and CCCTC-binding factor (CTCF), which is crucial in the formation of chromatin loops, affects the normal function of CTCF and leads to neoplasia and deformity. In addition, BORIS belongs to the cancer-testis antigen families, which are potential targets in cancer diagnosis and treatment. Herein, we discuss the function and mechanisms of BORIS, especially in cancer development.

The Cross-Talk between Epigenetic Gene Regulation and Signaling Pathways Regulates Cancer Pathogenesis

Cancer begins due to uncontrolled cell division. Cancer cells are insensitive to the signals that control normal cell proliferation. This uncontrolled cell division is due to the accumulation of abnormalities in different factors associated with the cell division, including different cyclins, cell cycle checkpoint inhibitors, and cellular signaling. Cellular signaling pathways are aberrantly activated in cancer mainly due to epigenetic regulation and post-translational regulation. In this chapter, the role of epigenetic regulation in aberrant activation of PI3K/AKT, Ras, Wnt, Hedgehog, Notch, JAK/STAT, and mTOR signaling pathways in cancer progression is discussed. The role of epigenetic regulators in controlling the upstream regulatory proteins and downstream effector proteins responsible for abnormal cellular signaling-mediated cancer progression is covered in this chapter. Similarly, the role of signaling pathways in controlling epigenetic gene regulation-mediated cancer progression is also discussed. We have tried to ascertain the current status of potential epigenetic drugs targeting several epigenetic regulators to prevent different cancers.

Ageing affects subtelomeric DNA methylation in blood cells from a large European population enrolled in the MARK-AGE study

Ageing leaves characteristic traces in the DNA methylation make-up of the genome. However, the importance of DNA methylation in ageing remains unclear. The study of subtelomeric regions could give promising insights into this issue. Previously reported associations between susceptibility to age-related diseases and epigenetic instability at subtelomeres suggest that the DNA methylation profile of subtelomeres undergoes remodelling during ageing. In the present work, this hypothesis has been tested in the context of the European large-scale project MARK-AGE. In this cross-sectional study, we profiled the DNA methylation of chromosomes 5 and 21 subtelomeres, in more than 2000 age-stratified women and men recruited in eight European countries. The study included individuals from the general population as well as the offspring of nonagenarians and Down syndrome subjects, who served as putative models of delayed and accelerated ageing, respectively. Significant linear changes of subtelomeric DNA methylation with increasing age were detected in the general population, indicating that subtelomeric DNA methylation changes are typical signs of ageing. Data also show that, compared to the general population, the dynamics of age-related DNA methylation changes are attenuated in the offspring of centenarian, while they accelerate in Down syndrome individuals. This result suggests that subtelomeric DNA methylation changes reflect the rate of ageing progression. We next attempted to trace the age-related changes of subtelomeric methylation back to the influence of diverse variables associated with methylation variations in the population, including demographics, dietary/health habits and clinical parameters. Results indicate that the effects of age on subtelomeric DNA methylation are mostly independent of all other variables evaluated.

CTCF and CTCFL in cancer

CTCF plays a key role in organizing chromatin into TAD structures but it can also function as a transcription factor. CTCFL (CTCF-like), the paralog of CTCF, is normally transiently expressed in pre-meiotic male germ cells together with ubiquitously expressed CTCF. It plays a unique role in spermatogenesis by regulating expression of testis-specific genes. Genetic alterations in CTCF and its paralog CTCFL have both been found in numerous cancers, but it remains unknown to what extent CTCFL deregulates transcription on its own or by opposing CTCF. Here, we discuss some of the potential mechanisms by which these two proteins could alter gene regulation and contribute to oncogenic transcriptional programs.

Notch3 in Development, Health and Disease

Notch3 is one of four mammalian Notch proteins, which act as signalling receptors to control cell fate in many developmental and adult tissue contexts. Notch signalling continues to be important in the adult organism for tissue maintenance and renewal and mis-regulation of Notch is involved in many diseases. Genetic studies have shown that Notch3 gene knockouts are viable and have limited developmental defects, focussed mostly on defects in the arterial smooth muscle cell lineage. Additional studies have revealed overlapping roles for Notch3 with other Notch proteins, which widen the range of developmental functions. In the adult, Notch3, in collaboration with other Notch proteins, is involved in stem cell regulation in different tissues in stem cell regulation in different tissues, and it also controls the plasticity of the vascular smooth muscle phenotype involved in arterial vessel remodelling. Overexpression, gene amplification and mis-activation of Notch3 are associated with different cancers, in particular triple negative breast cancer and ovarian cancer. Mutations of Notch3 are associated with a dominantly inherited disease CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and there is further evidence linking Notch3 misregulation to hypertensive disease. Here we discuss the distinctive roles of Notch3 in development, health and disease, different views as to the underlying mechanisms of its activation and misregulation in different contexts and potential for therapeutic intervention.

BORIS/CTCFL promotes a switch from a proliferative towards an invasive phenotype in melanoma cells

Melanoma is among the most aggressive cancers due to its tendency to metastasize early. Phenotype switching between a proliferative and an invasive state has been suggested as a critical process for metastasis, though the mechanisms that regulate state transitions are complex and remain poorly understood. Brother of Regulator of Imprinted Sites (BORIS), also known as CCCTC binding factor-Like (CTCFL), is a transcriptional modulator that becomes aberrantly expressed in melanoma. Yet, the role of BORIS in melanoma remains elusive. Here, we show that BORIS is involved in melanoma phenotype switching. Genetic modification of BORIS expression in melanoma cells combined with whole-transcriptome analysis indicated that BORIS expression contributes to an invasion-associated transcriptome. In line with these findings, inducible BORIS overexpression in melanoma cells reduced proliferation and increased migration and invasion, demonstrating that the transcriptional switch is accompanied by a phenotypic switch. Mechanistically, we reveal that BORIS binds near the promoter of transforming growth factor-beta 1 (TFGB1), a well-recognized factor involved in the transition towards an invasive state, which coincided with increased expression of TGFB1. Overall, our study indicates a pro-invasive role for BORIS in melanoma via transcriptional reprogramming.

Choice of binding sites for CTCFL compared to CTCF is driven by chromatin and by sequence preference

The two paralogous zinc finger factors CTCF and CTCFL differ in expression such that CTCF is ubiquitously expressed, whereas CTCFL is found during spermatogenesis and in some cancer types in addition to other cell types. Both factors share the highly conserved DNA binding domain and are bound to DNA sequences with an identical consensus. In contrast, both factors differ substantially in the number of bound sites in the genome. Here, we addressed the molecular features for this binding specificity. In contrast to CTCF we found CTCFL highly enriched at ‘open’ chromatin marked by H3K27 acetylation, H3K4 di- and trimethylation, H3K79 dimethylation and H3K9 acetylation plus the histone variant H2A.Z. CTCFL is enriched at transcriptional start sites and regions bound by transcription factors. Consequently, genes deregulated by CTCFL are highly cell specific. In addition to a chromatin-driven choice of binding sites, we determined nucleotide positions critical for DNA binding by CTCFL, but not by CTCF.

Histone Modifications Drive Aberrant Notch3 Expression/Activity and Growth in T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive blood cancer caused by the deregulation of key T-cell developmental pathways, including Notch signaling. Aberrant Notch signaling in T-ALL occurs by NOTCH1 gain-of-function mutations and by NOTCH3 overexpression. Although NOTCH3 is assumed as a Notch1 target, machinery driving its transcription in T-ALL is undefined in leukemia subsets lacking Notch1 activation. Here, we found that the binding of the intracellular Notch3 domain, as well as of the activated Notch1 fragment, to the NOTCH3 gene locus led to the recruitment of the H3K27 modifiers JMJD3 and p300, and it was required to preserve transcriptional permissive/active H3K27 marks and to sustain NOTCH3 gene expression levels. Consistently, pharmacological inhibition of JMJD3 by GSKJ4 treatment or of p300 by A-485 decreased the levels of expression of NOTCH3, NOTCH1 and of the Notch target genes DELTEX1 and c-Myc and abrogated cell viability in both Notch1- and Notch3-dependent T-cell contexts. Notably, re-introduction of exogenous Notch1, Notch3 as well as c-Myc partially rescued cells from anti-growth effects induced by either treatment. Overall our findings indicate JMJD3 and p300 as general Notch1 and Notch3 signaling co-activators in T-ALL and suggest further investigation on the potential therapeutic anti-leukemic efficacy of their enzymatic inhibition in Notch/c-Myc axis-related cancers and diseases.

Predicting Novel Therapies and Targets: Regulation of Notch3 by the Bromodomain Protein BRD4

Systematic approaches for accurate repurposing of targeted therapies are needed. We developed and aimed to biologically validate our therapy predicting tool (TPT) for the repurposing of targeted therapies for specific tumor types by testing the role of Bromodomain and Extra-Terminal motif inhibitors (BETi) in inhibiting BRD4 function and downregulating Notch3 signaling in ovarian cancer.Utilizing established ovarian cancer preclinical models, we carried out in vitro and in vivo studies with clinically relevant BETis to determine their therapeutic effect and impact on Notch3 signaling.Treatment with BETis or siRNA-mediated BRD4 knockdown resulted in decreased cell viability, reduced cell proliferation, and increased cell apoptosis in vitro. In vivo studies with orthotopic mouse models demonstrated that treatment with BETi decreased tumor growth. In addition, knockdown of BRD4 with doxycycline-inducible shRNA increased survival up to 50% (P < 0.001). Treatment with either BETis or BRD4 siRNA decreased Notch3 expression both in vitro and in vivo BRD4 inhibition also decreased the expression of NOTCH3 targets, including HES1 Chromatin immunoprecipitation revealed that BRD4 was present at the NOTCH3 promoter.Our findings provide biological validation for the TPT by demonstrating that BETis can be an effective therapeutic agent for ovarian cancer by downregulating Notch3 expression.The TPT could rapidly identify candidate drugs for ovarian or other cancers along with novel companion biomarkers.

BORIS: a key regulator of cancer stemness

BORIS (CTCFL) is a DNA binding protein which is involved in tumorigenesis. Although, there are different opinions on the level of gene expression and function of BORIS in normal and cancer tissues, the results of many studies have classified BORIS as a protein belonging to cancer/testis (CT) genes, which are identified as a group of genes that are expressed normally in testis, and abnormally in various types of cancers. In testis, BORIS induces the expression of some male germ cell/testis specific genes, and plays crucial roles during spermatogenesis and production of sperm. In tumorigenesis, the role of BORIS in the expression induction of some CT genes and oncogenes, as well as increasing proliferation/viability of cancer cells has been demonstrated in many researches. In addition to cancer cells, some believe that BORIS is also expressed in normal conditions and plays a universal function in cell division and regulation of genes. The following is a comprehensive review on contradictory views on the expression pattern and biological function of BORIS in normal, as well as cancer cells/tissues, and presents some evidence that support the expression of BORIS in cancer stem cells (CSCs) and advanced stage/poorer differentiation grade of cancers. Boris is involved in the regulation of CSC cellular and molecular features such as self-renewal, chemo-resistance, tumorigenicity, sphere-forming ability, and migration capacity. Finally, the role of BORIS in regulating two important signaling pathways including Wnt/β-catenin and Notch in CSCs, and its ability in recruiting transcription factors or chromatin-remodeling proteins to induce tumorigenesis is discussed.

Notch signaling as a therapeutic target for acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Although the therapy of ALL has significantly improved, the heterogeneous genetic landscape of the disease often causes relapse, which is difficult to treat. Achieving a positive outcome for patients with relapsed or refractory ALL remains a challenging issue. The high prevalence of NOTCH-activating mutations in T-cell acute lymphoblastic leukemia (T-ALL) and the central role of NOTCH signaling in regulating cell survival and growth of ALL provide a rationale for the development of Notch signaling-targeted strategies in this disease. Therapeutic alternatives with effective anti-leukemic potential and low toxicity are needed. Areas covered: This review provides an overview of the currently available drugs directly or indirectly targeting Notch signaling in ALL. Besides considering the known Notch targeting approaches, such as γ-secretase inhibitors (GSIs) and Notch inhibiting antibodies (mAbs), currently in clinical trials, we focus on the recent insights into the molecular mechanisms underlying the Notch signaling regulation in ALL. Expert opinion: Novel drugs targeting specific steps of Notch signaling or intersecting pathways could improve the efficiency of the conventional hematological cancers therapies. Further studies are required to translate the new findings into future clinical applications.

MAGEA1 inhibits the expression of BORIS via increased promoter methylation

Melanoma-associated antigen A1 (MAGEA1) and BORIS are members of the cancer testis antigens (CTA) family. Their functions and expression regulation mechanisms are not fully understood. In this study, we revealed new functions and regulatory mechanisms of MAGEA1 and BORIS in breast cancer cells, which were investigated in parental and genetically manipulated breast cancer cells via gene overexpression or siRNA interference-mediated down-regulation. We identified the interaction between MAGEA1 and CTCF, which was required for the binding of MAGEA1 to BORIS promoter and critical for the recruitment of DNMT3a. A protein complex containing MAGEA1, CTCF and DNMT3a will be formed before or after the conjunction with BORIS promoter. The binding of this complex to the BORIS promoter accounts for the hypermethylation and repression of BORIS expression, which results in cell death in the breast cancer cell lines tested. Multiple approaches are employed, including co-IP, GST-pull down, co-localization, cell death analyses using the Annexin V-FITC/PI double staining and caspase3 activation assays, ChIP and bisulfite sequencing PCR assays for methylation. These results have implications in the development of strategies in CTA-based immune therapeutics.

The Notch3 Receptor and Its Intracellular Signaling-Dependent Oncogenic Mechanisms

During evolution, gene duplication of the Notch receptor suggests a progressive functional diversification. The Notch3 receptor displays a number of structural differences with respect to Notch1 and Notch2, most of which have been reported in the transmembrane and in the intracellular regions, mainly localized in the negative regulatory region (NRR) and trans-activation domain (TAD). Targeted deletion of Notch3 does not result in embryonic lethality, which is in line with its highly restricted tissue expression pattern. Importantly, deregulated Notch3 expression and/or activation, often results in disrupted cell differentiation and/or pathological development, most notably in oncogenesis in different cell contexts. Mechanistically this is due to Notch3-related genetic alterations or epigenetic or posttranslational control mechanisms. In this chapter we discuss the possible relationships between the structural differences and the pathological role of Notch3 in the control of mouse and human cancers. In future, targeting the unique features of Notch3-oncogenic mechanisms could be exploited to develop anticancer therapeutics.

Brother of the regulator of the imprinted site (BORIS) variant subfamily 6 is involved in cervical cancer stemness and can be a target of immunotherapy

Cervical cancer is a major cause of cancer death in females worldwide. Cervical cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are resistant to conventional radiotherapy and chemotherapy, and CSCs/CICs are thought to be responsible for recurrence. Eradication of CSCs/CICs is thus essential to cure cervical cancer. In this study, we isolated cervical CSCs/CICs by sphere culture, and we identified a cancer testis (CT) antigen, CTCFL/BORIS, that is expressed in cervical CSCs/CICs. BORIS has 23 mRNA isoform variants classified by 6 subfamilies (sfs), and they encode 17 different BORIS peptides. BORIS sf1 and sf4 are expressed in both CSCs/CICs and non-CSCs/CICs, whereas BORIS sf6 is expressed only in CSCs/CICs. Overexpression of BORIS sf6 in cervical cancer cells increased sphere formation and tumor-initiating ability compared with those in control cells, whereas overexpression of BORIS sf1 and BORIS sf4 resulted in only slight increases. Thus, BORIS sf6 is a cervical CSC/CIC-specific subfamily and has a role in the maintenance of cervical CSCs/CICs. BORIS sf6 contains a specific c-terminal domain (C34), and we identified a human leukocyte antigen (HLA)-A2-restricted antigenic peptide, BORIS C34_24(9) encoded by BORIS sf6. A BORIS C34_24(9)-specific cytotoxic T cell (CTL) clone showed cytotoxicity for BORIS sf6-overexpressing cervical cancer cells. Furthermore, the CTL clone significantly suppressed sphere formation of CaSki cells. Taken together, the results indicate that the CT antigen BORIS sf6 is specifically expressed in cervical CSCs/CICs, that BORIS sf6 has a role in the maintenance of CSCs/CICs, and that BORIS C34_24(9) peptide is a promising candidate for cervical CSC/CIC-targeting immunotherapy.

Brother of the regulator of the imprinted site (BORIS) variant subfamily 6 is a novel target of lung cancer stem-like cell immunotherapy

Lung cancer is one of the most common malignancies with a high rate of mortality. Lung cancer stem-like cells (CSCs)/ cancer-initiating cells (CICs) play major role in resistance to treatments, recurrence and distant metastasis and eradication of CSCs/CICs is crucial to improve recent therapy. Cytotoxic T lymphocytes (CTLs) are major effectors of cancer immunotherapy, and CTLs recognize antigenic peptides derived from antigens that are presented by major histocompatibility complex (MHC) class I molecules. In this study, we analyzed the potency of a cancer-testis (CT) antigen, brother of the regulator of the imprinted site variant subfamily 6 (BORIS sf6), in lung CSC/CIC immunotherapy. BORIS sf6 mRNA was expressed in lung carcinoma cells (9/19), especially in sphere-cultured lung cancer stem-like cells, and in primary lung carcinoma tissues (4/9) by RT-PCR. Immunohistochemical staining using BORIS sf6-specific antibody revealed that high expression of BORIS sf6 is related to poorer prognosis. CTLs could be induced by using a human leukocyte antigen, (HLA)-A2 restricted antigenic peptide (BORIS C34_24(9)), from all of 3 HLA-A2-positive individuals, and CTL clone cells specific for BORIS C34_24(9) peptide could recognize BORIS sf6-positive, HLA-A2-positive lung carcinoma cells. These results indicate that BORIS sf6 is a novel target of lung cancer immunotherapy that might be useful for targeting treatment-resistant lung cancer stem-like cells.

A polymorphic minisatellite region of BORIS regulates gene expression and its rare variants correlate with lung cancer susceptibility

Aberrant expression of BORIS/CTCFL (Brother of the Regulator of Imprinted Sites/CTCF-like protein) is reported in different malignancies. In this study, we characterized the entire promoter region of BORIS/CTCFL, including the CpG islands, to assess the relationship between BORIS expression and lung cancer. To simplify the construction of luciferase reporter cassettes with various-sized portions of the upstream region, genomic copies of BORIS were isolated using TAR cloning technology. We analyzed three promoter blocks: the GATA/CCAAT box, the CpG islands and the minisatellite region BORIS-MS2. Polymorphic minisatellite sequences were isolated from genomic DNA prepared from the blood of controls and cases. Of the three promoter blocks, the GATA/CCAAT box was determined to be a critical element of the core promoter, while the CpG islands and the BORIS-MS2 minisatellite region were found to act as regulators. Interestingly, the polymorphic minisatellite region BORIS-MS2 was identified as a negative regulator that repressed the expression levels of luciferase reporter cassettes less effectively in cancer cells compared with normal cells. We also examined the association between the size of BORIS-MS2 and lung cancer in a case–control study with 590 controls and 206 lung cancer cases. Rare alleles of BORIS-MS2 were associated with a statistically significantly increased risk of lung cancer (odds ratio, 2.04; 95% confidence interval, 1.02–4.08; and P=0.039). To conclude, our data provide information on the organization of the BORIS promoter region and gene regulation in normal and cancer cells. In addition, we propose that specific alleles of the BORIS-MS2 region could be used to identify the risk for lung cancer.

Prolyl-isomerase Pin1 controls Notch3 protein expression and regulates T-ALL progression

Deregulated Notch signaling is associated with T-cell Acute Lymphoblastic Leukemia (T-ALL) development and progression. Increasing evidence reveals that Notch pathway has an important role in the invasion ability of tumor cells, including leukemia, although the underlying molecular mechanisms remain mostly unclear. Here, we show that Notch3 is a novel target protein of the prolyl-isomerase Pin1, which is able to regulate Notch3 protein processing and to stabilize the cleaved product, leading to the increased expression of the intracellular domain (N3_IC), finally enhancing Notch3-dependent invasiveness properties. We demonstrate that the combined inhibition of Notch3 and Pin1 in the Notch3-overexpressing human leukemic TALL-1 cells reduces their high invasive potential, by decreasing the expression of the matrix metalloprotease MMP9. Consistently, Pin1 depletion in a mouse model of Notch3-induced T-ALL, by reducing N3_IC expression and signaling, impairs the expansion/invasiveness of CD4⁺CD8⁺ DP cells in peripheral lymphoid and non-lymphoid organs. Notably, in in silico gene expression analysis of human T-ALL samples we observed a significant correlation between Pin1 and Notch3 expression levels, which may further suggest a key role of the newly identified Notch3-Pin1 axis in T-ALL aggressiveness and progression. Thus, combined suppression of Pin1 and Notch3 proteins may be exploited as an additional target therapy for T-ALL.

Epigenetic mechanisms in cancer: push and pull between kneaded erasers and fate writers

Research concerning the epigenome over the years has systematically and sequentially shown substantial development and we have moved from global inhibition of modifications of the epigenome toward identification and targeted therapy against tumor-specific epigenetic mechanisms. In accordance with this approach, several drugs with epigenetically modulating activity have received considerable attention and appreciation, and recently emerging scientific evidence is uncovering details of their mode of action. High-throughput technologies have considerably improved our existing understanding of tumor suppressors, oncogenes, and signaling pathways that are key drivers of cancer. In this review, we summarize the general epigenetic mechanisms in cancer, including: the post-translational modification of DNA methyltransferase and its mediated inactivation of Ras association domain family 1 isoform A, Sonic hedgehog signaling, Wnt signaling, Notch signaling, transforming growth factor signaling, and natural products with epigenetic modification ability. Moreover, we introduce the importance of nanomedicine for delivery of natural products with modulating ability to epigenetic machinery in cancer cells. Such in-depth and comprehensive knowledge regarding epigenetic dysregulation will be helpful in the upcoming era of molecular genomic pathology for both detection and treatment of cancer. Epigenetic information will also be helpful when nanotherapy is used for epigenetic modification.