Deregulation of RAD21 and RUNX1 expression in endometrial cancer

Mucin-producing urothelial-type adenocarcinoma of the prostate with sarcomatoid features and novel molecular phenotype

Introduction

Mucin-producing urothelial-type adenocarcinoma of the prostate is a rare tumor that may not elevate serum prostate-specific antigen, creating significant diagnostic and monitoring challenges. We evaluate our case in detail and review prior studies to demonstrate that the pathologic and molecular features of this tumor are distinct from conventional prostate adenocarcinoma.

Case presentation

Our patient had a remote history of radiation-treated conventional prostate adenocarcinoma and presented many years later with an abscess-like prostate mass leading to urinary obstruction and hematuria. Biopsy revealed mucin-producing urothelial-type adenocarcinoma of the prostate with concurrent sarcomatoid features. Molecular studies showed a unique phenotype involving alterations in the KRAS, PTEN, RAD21, and TP53 genes.

Conclusions

To our knowledge, this is the first report that describes sarcomatoid features and molecular mutations in mucin-producing urothelial-type adenocarcinoma of the prostate.

Comprehensive multiomics analyses reveal pervasive involvement of aberrant cohesin binding in transcriptional and chromosomal disorder of cancer cells

Chromatin organization, whose malfunction causes various diseases including cancer, is fundamentally controlled by cohesin. While cancer cells have been found with mutated or misexpressed cohesin genes, there is no comprehensive survey about the presence and role of abnormal cohesin binding in cancer cells. Here, we systematically identified ∼1% of cohesin-binding sites (701-2,633) as cancer-aberrant binding sites of cohesin (CASs). We integrated CASs with large-scale transcriptomics, epigenomics, 3D genomics, and clinical information. CASs represent tissue-specific epigenomic signatures enriched for cancer-dysregulated genes with functional and clinical significance. CASs exhibited alterations in chromatin compartments, loops within topologically associated domains, and cis-regulatory elements, indicating that CASs induce dysregulated genes through misguided chromatin structure. Cohesin depletion data suggested that cohesin binding at CASs actively regulates cancer-dysregulated genes. Overall, our comprehensive investigation suggests that aberrant cohesin binding is an essential epigenomic signature responsible for dysregulated chromatin structure and transcription in cancer cells.

Differential Occupancy and Regulatory Interactions of KDM6A in Bladder Cell Lines

Epigenetic deregulation is a critical theme which needs further investigation in bladder cancer research. One of the most highly mutated genes in bladder cancer is KDM6A, which functions as an H3K27 demethylase and is one of the MLL3/4 complexes. To decipher the role of KDM6A in normal versus tumor settings, we identified the genomic landscape of KDM6A in normal, immortalized, and cancerous bladder cells. Our results showed differential KDM6A occupancy in the genes involved in cell differentiation, chromatin organization, and Notch signaling depending on the cell type and the mutation status of KDM6A. Transcription factor motif analysis revealed HES1 to be enriched at KDM6A peaks identified in the T24 bladder cancer cell line; moreover, it has a truncating mutation in KDM6A and lacks a demethylase domain. Our co-immunoprecipitation experiments revealed TLE co-repressors and HES1 as potential truncated and wild-type KDM6A interactors. With the aid of structural modeling, we explored how truncated KDM6A could interact with TLE and HES1, as well as RUNX and HHEX transcription factors. These structures provide a solid means of studying the functions of KDM6A independently of its demethylase activity. Collectively, our work provides important contributions to the understanding of KDM6A malfunction in bladder cancer.

α-Kleisin subunit of cohesin preserves the genome integrity of embryonic stem cells

Cohesin is a ring-shaped protein complex that comprises the SMC1, SMC3, and α-kleisin proteins, STAG1/2/3 subunits, and auxiliary factors. Cohesin participates in chromatin remodeling, chromosome segregation, DNA replication, and gene expression regulation during the cell cycle. Mitosis-specific α-kleisin factor RAD21 and meiosis-specific α-kleisin factor REC8 are expressed in embryonic stem cells (ESCs) to maintain pluripotency. Here, we demonstrated that RAD21 and REC8 were involved in maintaining genomic stability and modulating chromatin modification in murine ESCs. When the kleisin subunits were depleted, DNA repair genes were downregulated, thereby reducing cell viability and causing replication protein A (RPA) accumulation. This finding suggested that the repair of exposed single-stranded DNA was inefficient. Furthermore, the depletion of kleisin subunits induced DNA hypermethylation by upregulating DNA methylation proteins. Thus, we proposed that the cohesin complex plays two distinct roles in chromatin remodeling and genomic integrity to ensure the maintenance of pluripotency in ESCs. [BMB Reports 2023; 56(2): 108-113].

α-Kleisin subunit of cohesin preserves the genome integrity of embryonic stem cells

Cohesin is a ring-shaped protein complex that comprises the SMC1, SMC3, and α-kleisin proteins, STAG1/2/3 subunits, and auxiliary factors. Cohesin participates in chromatin remodeling, chromosome segregation, DNA replication, and gene expression regulation during the cell cycle. Mitosis-specific α-kleisin factor RAD21 and meiosis-specific α-kleisin factor REC8 are expressed in embryonic stem cells (ESCs) to maintain pluripotency. Here, we demonstrated that RAD21 and REC8 were involved in maintaining genomic stability and modulating chromatin modification in murine ESCs. When the kleisin subunits were depleted, DNA repair genes were downregulated, thereby reducing cell viability and causing replication protein A (RPA) accumulation. This finding suggested that the repair of exposed single-stranded DNA was inefficient. Furthermore, the depletion of kleisin subunits induced DNA hypermethylation by upregulating DNA methylation proteins. Thus, we proposed that the cohesin complex plays two distinct roles in chromatin remodeling and genomic integrity to ensure the maintenance of pluripotency in ESCs. [BMB Reports 2023; 56(2): 108-113].

Cohesin in DNA damage response and double-strand break repair

Cohesin, a four-subunit ring comprising SMC1, SMC3, RAD21 and SA1/2, tethers sister chromatids by DNA replication-coupled cohesion (RC-cohesion) to guarantee correct chromosome segregation during cell proliferation. Postreplicative cohesion, also called damage-induced cohesion (DI-cohesion), is an emerging critical player in DNA damage response (DDR). In this review, we sum up recent progress on how cohesin regulates the DNA damage checkpoint activation and repair pathway choice, emphasizing postreplicative cohesin loading and DI-cohesion establishment in yeasts and mammals. DI-cohesion and RC-cohesion show distinct features in many aspects. DI-cohesion near or far from the break sites might undergo different regulations and execute different tasks in DDR and DSB repair. Furthermore, some open questions in this field and the significance of this new scenario to our understanding of genome stability maintenance and cohesinopathies are discussed.

LINC00858 promotes colon cancer progression through activation of STAT3/5 signaling by recruiting transcription factor RAD21 to upregulate PCNP

The purpose of our investigation is to explore the putative molecular mechanisms underpinning LINC00858 involvement in colon cancer. The expression of LINC00858 in TCGA data was identified using the GEPIA website. Colon cancer cancerous tissues were clinically collected. The expression of LINC00858, RAD21, and PCNP in colon tissues or cells was determined using RT-qPCR. The interactions among LINC00858, RAD21, and PCNP promoter region were determined by means of RNA pull down, RIP, and ChIP assays. Cell proliferative, apoptotic, invasive, and migrated capabilities were evaluated. Western blot was conducted to determine RAD21, PCNP, phosphorylated (p)-STAT3, STAT3, p-STAT5 and STAT5 and apoptosis related proteins. A nude mouse model of colon cancer was constructed and tumorigenesis of colon cancer cells was observed. LINC00858 was upregulated in cancerous tissues and cells. LINC00858 recruited the transcription factor RAD21. Overexpression of LINC00858 promoted the binding of RAD21 and PCNP promoter region, which increased the expression of PCNP. Silencing of RAD21 or PCNP reversed the promoting effect of LINC00858 on the disease initiation and development. PCNP silencing inhibited proliferative ability and promoted apoptotic ability of cancerous cells via STAT3/5 inhibition, which was reversed by colivelin-activated STAT3. In vivo experiments further verified that LINC00858 enhanced the tumorigenicity of colon cancer cells in vivo by regulating the RAD21/PCNP/STAT3/5 axis. It indicated the promoting role of LINC00858 in colon cancer progression though activating PCNP-mediated STAT3/5 pathway by recruiting RAD21.

Thorough statistical analyses of breast cancer co-methylation patterns

Background

Breast cancer is one of the most commonly diagnosed cancers. It is associated with DNA methylation, an epigenetic event with a methyl group added to a cytosine paired with a guanine, i.e., a CG site. The methylation levels of different genes in a genome are correlated in certain ways that affect gene functions. This correlation pattern is known as co-methylation. It is still not clear how different genes co-methylate in the whole genome of breast cancer samples. Previous studies are conducted using relatively small datasets (Illumina 27K data). In this study, we analyze much larger datasets (Illumina 450K data).

Results

Our key findings are summarized below. First, normal samples have more highly correlated, or co-methylated, CG pairs than tumor samples. Both tumor and normal samples have more than 93% positive co-methylation, but normal samples have significantly more negatively correlated CG sites than tumor samples (6.6% vs. 2.8%). Second, both tumor and normal samples have about 94% of co-methylated CG pairs on different chromosomes, but normal samples have 470 million more CG pairs. Highly co-methylated pairs on the same chromosome tend to be close to each other. Third, a small proportion of CG sites’ co-methylation patterns change dramatically from normal to tumor. The percentage of differentially methylated (DM) sites among them is larger than the overall DM rate. Fourth, certain CG sites are highly correlated with many CG sites. The top 100 of such super-connector CG sites in tumor and normal samples have no overlaps. Fifth, both highly changing sites and super-connector sites’ locations are significantly different from the genome-wide CG sites’ locations. Sixth, chromosome X co-methylation patterns are very different from other chromosomes. Finally, the network analyses of genes associated with several sets of co-methylated CG sites identified above show that tumor and normal samples have different patterns.

Conclusions

Our findings will provide researchers with a new understanding of co-methylation patterns in breast cancer. Our ability to thoroughly analyze co-methylation of large datasets will allow researchers to study relationships and associations between different genes in breast cancer.

Runx1 promotes the development of glioma cells by regulating JAK-STAT signalling pathway

INTRODUCTION

Human glioma is known as the most frequent and primary malignant tumour of the central nervous system with high aggression and poor prognosis. Runx1 is essential for haematopoiesis and is associated with tumour progression in several types of cancers. Therefore, this study aimed to investigate the effect and the possible regulatory mechanisms of Runx1 in glioma.

MATERIAL AND METHODS

The expression of Runx1 in human glioma tissues was determined by qRT-PCR and immunohistochemistry (IHC). Subsequently, the effect of Runx1 on the glioma cell viability, migration, invasion and the protein level of p21, cyclin D1, MMP2, and MMP4 were detected by MTT, wound healing, transwell assays, and western blot, respectively, in U-138MG and U-251MG cell lines. We then explored the role of Runx1 in vivo by establishing a tumour-bearing mouse model.

RESULTS

The expression of Runx1 was significantly up-regulated in human glioma tissues and closely associated with tumour grade. Glioma patients with high Runx1 expression had decreased survival rate compared to those with low Runx1 level. Runx1 knockdown inhibited glioma cell viability, migration, invasion, and clone formation, while STAT3 suppressed these inhibitions. Moreover, Runx1 inhibited the activation of SOCS3/SOCS4 promoter, which in turn activated JAK/STAT3 signalling pathway. The tumour volume and weight of the siRunx1 group were lower than in the control group and the tumour mass grow more slowly as well.

CONCLUSIONS

Runx1 promotes the development of glioma cells via JAK/STAT signalling pathway by inhibiting the activation of SOCS3/SOCS4 promoter.

miR-122 Inhibits the Cervical Cancer Development by Targeting the Oncogene RAD21

Cervical cancer (CC) is one of the most frequently diagnosed tumors in female. miR-122 has been proved to be dominant in CC. The particular role of miR-122 in CC is unclear. Thus, we attempted to investigate the prognostic role of miR-122 in CC. We used the database of Kaplan-Meier curve plot. Growth and apoptosis of C33A cells were detected by CCK-8, colony formation assay, transwell assays and flow cytometry analysis. The target gene of miR-122 was identified using bioinformatics, q-PCR, western blot and luciferase assay. It showed that CC patients with overexpression of miR-122 have a better prognosis in the Kaplan-Meier plot database analysis. Overexpressed miR-122 inhibited the malignant growth and induced apoptosis of CC. miR-122 targeting of RAD21 cohesin complex component (RAD21) was identified using bioinformatics, Q-PCR, western blot and luciferase assay analyses. Moreover, we found miR-122 conduct its functions via RAD21 via the PI3K/AKT signaling pathway. Importantly, overexpression of RAD21 restored the roles of miR-122 in CC. Our data suggested that miR-122 could block malignant growth and promoted apoptosis by targeting RAD21 in CC. Our finding indicates miR-122 could potentially participate in the pathogenesis and be a biomarker or the potential therapeutic target of CC.

2α-Hydroxyalantolactone from Pulicaria undulata: activity against multidrug-resistant tumor cells and modes of action

BACKGROUND

Sesquiterpene lactones having α-methylene-γ-lactone moiety are promising natural metabolites showing various biological activity. One of the major metabolites isolated from Pulicaria undulata, 2α-hydroxyalantolactone (PU-1), has not been investigated in detail yet. Multidrug resistance (MDR) represents a major obstacle for cancer chemotherapy and the capability of novel natural products to overcoming MDR is of great interest.

PURPOSE

Exploring the molecular modes of action for potent natural product metabolites.

METHODS

The resazurin reduction assay was employed to evaluate the cytotoxicity of PU-1 on sensitive and their corresponding drug-resistant cell lines (overexpressing P-glycoprotein, BCRP, ABCB5, ΔEGFR, or TP53 knockout). Gene expression profiling was performed by transcriptome-wide mRNA microarray in the human CCRF-CEM leukemic cells after treatment with PU-1. The top significantly up- or down-regulated genes were identified by Chipster program and analyzed using Ingenuity Pathway Analysis (IPA) software. Finally, flow cytometry and Western blotting were performed for cell cycle analyses and apoptosis detection.

RESULTS

The sesquiterpene lactone, PU-1, showed potent cytotoxicity towards the drug-sensitive and -resistant cell lines. Transcriptome-wide mRNA expression profiling and pathway analysis pointed to genes involved in DNA damage response and G2/M cell cycle arrest. G2/M arrest was verified by flow cytometry and further confirmed by the upregulation of p21 and downregulation of p-CDC25C expression in Western blotting. Moreover, the suggested DNA damage checkpoint regulation was confirmed by immunofluorescence and Western blotting by upregulation of pS345 Chk1, p-H3 and γ-H2AX. Furthermore, PU-1 inhibited PI3K/AKT pathway, which is involved in signaling DNA damage and G2/M arrest. Cells ultimately induced apoptosis upon PU-1 treatment.

CONCLUSIONS

PU-1 is a potent natural product inhibiting otherwise drug-resistant human tumor cell growth through DNA damage, G2/M cell cycle arrest and apoptosis.

Dysregulation of NIPBL leads to impaired RUNX1 expression and haematopoietic defects

The transcription factor RUNX1, a pivotal regulator of HSCs and haematopoiesis, is a frequent target of chromosomal translocations, point mutations or altered gene/protein dosage. These modifications lead or contribute to the development of myelodysplasia, leukaemia or platelet disorders. A better understanding of how regulatory elements contribute to fine‐tune the RUNX1 expression in haematopoietic tissues could improve our knowledge of the mechanisms responsible for normal haematopoiesis and malignancy insurgence. The cohesin RAD21 was reported to be a regulator of RUNX1 expression in the human myeloid HL60 cell line and during primitive haematopoiesis in zebrafish. In our study, we demonstrate that another cohesin, NIPBL, exerts positive regulation of RUNX1 in three different contexts in which RUNX1 displays important functions: in megakaryocytes derived from healthy donors, in bone marrow samples obtained from adult patients with acute myeloid leukaemia and during zebrafish haematopoiesis. In this model, we demonstrate that alterations in the zebrafish orthologue nipblb reduce runx1 expression with consequent defects in its erythroid and myeloid targets such as gata1a and spi1b in an opposite way to rad21. Thus, also in the absence of RUNX1 translocation or mutations, additional factors such as defects in the expression of NIPBL might induce haematological diseases.

Identification and validation of microRNAs that synergize with miR-34a - a basis for combinatorial microRNA therapeutics

Efforts to search for better treatment options for cancer have been a priority, and due to these efforts, new alternative therapies have emerged. For instance, clinically relevant tumor-suppressive microRNAs that target key oncogenic drivers have been identified as potential anti-cancer therapeutics. MicroRNAs are small non-coding RNAs that negatively regulate gene expression at the posttranscriptional level. Aberrant microRNA expression, through misexpression of microRNA target genes, can have profound cellular effects leading to a variety of diseases, including cancer. While altered microRNA expression contributes to a cancerous state, restoration of microRNA expression has therapeutic benefits. For example, ectopic expression of microRNA-34a (miR-34a), a tumor suppressor gene that is a direct transcriptional target of p53 and thus is reduced in p53 mutant tumors, has clear effects on cell proliferation and survival in murine models of cancer. MicroRNA replacement therapies have recently been tested in combination with other agents, including other microRNAs, to simultaneously target multiple pathways to improve the therapeutic response. Thus, we reasoned that other microRNA combinations could collaborate to further improve treatment. To test this hypothesis miR-34a was used in an unbiased cell-based approach to identify combinatorial microRNA pairs with enhanced efficacy over miR-34a alone. This approach identified a subset of microRNAs that was able to enhance the miR-34a antiproliferative activity. These microRNA combinatorial therapeutics could offer superior tumor-suppressive abilities to suppress oncogenic properties compared to a monotherapeutic approach. Collectively these studies aim to address an unmet need of identifying, characterizing, and therapeutically targeting microRNAs for the treatment of cancer.

The effect of aberrant expression and genetic polymorphisms of Rad21 on cervical cancer biology

The therapeutic challenge of advanced, recurrent, and refractory cervical cancer (CC) needs to develop new molecularly targeted drugs. Rad21 is an important regulatory gene that maintains the correct dissociation of sister chromatids during cell mitosis. The aim of this study was to investigate the effect of Rad21 on CC. Rad21 expression in CC and cervical intraepithelial neoplasia III was significantly increased. Women with the rs2289937 C genotype (CC+CT) of rs4570 and rs4579555 genotypes and haplotype 1 (TTTCAGGCGC) were significantly associated with CC risk, while women with low frequencies of haplotype 6 (TTTTAGGCGC) also increased the risk of CC.Rad21‐specific shRNA decreased cancerous cell proliferation, migration, and invasion and increased the proportion of cells in G2/M phase as well as sensitivity to radiation. The Rad21 influenced the expression of XPO1, CyclinB1, CDK1, P21, P27, and P53 through up‐and downregulating the Rad21 expression. The TCGA database of CC also showed that Rad21 expression was associated with poor disease survival and XPO1 expression. Moreover, the KEGG pathway indicated that Rad21 is broadly involved in the cell cycle and RNA transportation via XPO1. This suggests that Rad21 involves the development of cervical cancer possibly by participating in the regulation of cell cycle and the nuclear output of the tumor suppressor gene via XPO1.

The Cohesion complex maintains genome stability by preventing end joining of distant DNA ends in S phase

Genome instability is a hallmark of cancer cells. The joining of distant DNA double-strand ends (DSEs) ineluctably leads to genome rearrangements. We found that the cohesion complex maintains genome stability by repressing the joining of distant DSEs specifically in the S phase, i.e., the main phase producing one-ended DSEs.

miR-216a-3p Inhibits the Proliferation, Migration, and Invasion of Human Gastric Cancer Cells via Targeting RUNX1 and Activating the NF-κB Signaling Pathway

This work aims to elucidate the effects and the potential underlying mechanisms of microRNA-216a-3p (miR-216a-3p) on the proliferation, migration, and invasion of gastric cancer (GC) cells. In this study, we revealed that the expression of miR-216a-3p was significantly elevated in GC tissues and cell lines. The different expression level of miR-216a-3p was firmly correlated with clinicopathological characteristics of GC patients. We next demonstrated that upregulation of miR-216a-3p could dramatically promote the ability of proliferation, migration, and invasion of GC cells using a series of experiments, whereas downregulation essentially inhibited these properties. Additionally, through bioinformatics analysis and biological approaches, we confirmed that runt-related transcription factor 1 (RUNX1) was a direct target of miR-216a-3p, and overexpression of RUNX1 could reverse the potential effect of miR-216a-3p on GC cells. Furthermore, mechanistic investigation using Western blot analysis showed that downregulation of RUNX1 by miR-216a-3p could stimulate the activation of NF-κB signaling pathway. In summary, this work proved that miR-216a-3p can promote GC cell proliferation, migration, and invasion via targeting RUNX1 and activating the NF-κB signaling pathway. Therefore, miR-216a-3p/RUNX1 could be a possible molecular target for innovative therapeutic agents against GC.

The enigmatic role of RUNX1 in female-related cancers - current knowledge & future perspectives

Historically associated with the aetiology of human leukaemia, the runt-related transcription factor 1 (RUNX1) gene has in recent years reared its head in an assortment of epithelial cancers. This review discusses the state-of-the-art knowledge of the enigmatic role played by RUNX1 in female-related cancers of the breast, the uterus and the ovary. The weight of evidence accumulated so far is indicative of a very context-dependent role, as either an oncogene or a tumour suppressor. This is corroborated by high-throughput sequencing endeavours which report different genetic alterations affecting the gene, including amplification, deep deletion and mutations. Herein, we attempt to dissect that contextual role by firstly giving an overview of what is currently known about RUNX1 function in these specific tumour types, and secondly by delving into connections between this transcription factor and the physiology of these female tissues. In doing so, RUNX1 emerges not only as a gene involved in female sex development but also as a crucial mediator of female hormone signalling. In view of RUNX1 now being listed as a driver gene, we believe that greater knowledge of the mechanisms underlying its functional dualism in epithelial cancers is worthy of further investigation.

Genomic rearrangements induced by unscheduled DNA double strand breaks in somatic mammalian cells

DNA double-strand breaks (DSBs) are highly toxic lesions that can lead to profound genome rearrangements and/or cell death. They routinely occur in genomes due to endogenous or exogenous stresses. Efficient repair systems, canonical non-homologous end-joining and homologous recombination exist in the cell and not only ensure the maintenance of genome integrity but also, via specific programmed DNA double-strand breaks, permit its diversity and plasticity. However, these repair systems need to be tightly controlled because they can also generate genomic rearrangements. Thus, when DSB repair is not properly regulated, genome integrity is no longer guaranteed. In this review, we will focus on non-programmed genome rearrangements generated by DSB repair, in somatic cells. We first discuss genome rearrangements induced by homologous recombination and end-joining. We then discuss recently described rearrangement mechanisms, driven by microhomologies, that do not involve the joining of DNA ends but rather initiate DNA synthesis (microhomology-mediated break-induced replication, fork stalling and template switching and microhomology-mediated template switching). Finally, we discuss chromothripsis, which is the shattering of a localized region of the genome followed by erratic rejoining.

Runx Genes in Breast Cancer and the Mammary Lineage

A full understanding of RUNX gene function in different epithelial lineages has been thwarted by the lethal phenotypes observed when constitutively knocking out these mammalian genes. However temporal expression of the Runx genes throughout the different phases of mammary gland development is indicative of a functional role in this tissue. A few studies have emerged describing how these genes impact on the fate of mammary epithelial cells by regulating lineage differentiation and stem/progenitor cell potential, with implications for the transformed state. The importance of the RUNX/CBFβ core factor binding complex in breast cancer has very recently been highlighted with both RUNX1 and CBFβ appearing in a comprehensive gene list of predicted breast cancer driver mutations. Nonetheless, the evidence to date shows that the RUNX genes can have dualistic outputs with respect to promoting or constraining breast cancer phenotypes, and that this may be aligned to individual subtypes of the clinical disease. We take this opportunity to review the current literature on RUNX and CBFβ in the normal and neoplastic mammary lineage while appreciating that this is likely to be the tip of the iceberg in our knowledge.

Candidate locus analysis of the TERT-CLPTM1L cancer risk region on chromosome 5p15 identifies multiple independent variants associated with endometrial cancer risk

Several studies have reported associations between multiple cancer types and single-nucleotide polymorphisms (SNPs) on chromosome 5p15, which harbours TERT and CLPTM1L, but no such association has been reported with endometrial cancer. To evaluate the role of genetic variants at the TERT-CLPTM1L region in endometrial cancer risk, we carried out comprehensive fine-mapping analyses of genotyped and imputed SNPs using a custom Illumina iSelect array which includes dense SNP coverage of this region. We examined 396 SNPs (113 genotyped, 283 imputed) in 4,401 endometrial cancer cases and 28,758 controls. Single-SNP and forward/backward logistic regression models suggested evidence for three variants independently associated with endometrial cancer risk (P = 4.9 × 10(-6) to P = 7.7 × 10(-5)). Only one falls into a haplotype previously associated with other cancer types (rs7705526, in TERT intron 1), and this SNP has been shown to alter TERT promoter activity. One of the novel associations (rs13174814) maps to a second region in the TERT promoter and the other (rs62329728) is in the promoter region of CLPTM1L; neither are correlated with previously reported cancer-associated SNPs. Using TCGA RNASeq data, we found significantly increased expression of both TERT and CLPTM1L in endometrial cancer tissue compared with normal tissue (TERT P = 1.5 × 10(-18), CLPTM1L P = 1.5 × 10(-19)). Our study thus reports a novel endometrial cancer risk locus and expands the spectrum of cancer types associated with genetic variation at 5p15, further highlighting the importance of this region for cancer susceptibility.

RAD21 cohesin overexpression is a prognostic and predictive marker exacerbating poor prognosis in KRAS mutant colorectal carcinomas

Background:

RAD21 is a component of the cohesion complex and is integral to chromosome segregation and error-free DNA repair. RAD21 is functionally important in tumour progression but its role in colorectal carcinoma (CRC) is unclear. We therefore assessed its clinicopathological and prognostic significance in CRC, as well as its effect on chemosensitivity.

Methods:

A retrospective observation study examined RAD21 expression in 652 CRCs using a tissue microarray approach. Correlation with clinicopathological factors including gender, tumour grade, mucinous subtype, TNM stage, disease-specific survival (DSS), BRAF and KRAS mutation status, tumour p53 immunostaining, tumour microsatellite instability and tumour CpG island methylator phenotype was performed. Colorectal cancer cell clones with stable RAD21 knockdown were generated and tested for cellular sensitivity to conventional chemotherapeutic drugs.

Results:

RAD21 expression was significantly correlated with male gender (56.7% vs 43.3%, P=0.02), well-differentiated histology (14.4% vs 4.0%, P=0.0001), higher T-stage (36.1% vs 27.0%, P=0.01), presence of metastasis (18.8% vs 12.6%, P=0.03), and shorter DSS (hazard ratio (HR) 1.4, 95% CI 1.1 to 1.9, P=0.01) in both univariate and multivariate analysis. RAD21 expression was associated with shorter DSS in patients with KRAS mutant tumours (HR:2.6, 95% CI:1.4–4.3, P=0.001) and in patients receiving adjuvant chemoradiotherapy (HR:1.9, 95% CI:1.2–3.0, P=0.008). Colorectal cancer cells with RAD21 knockdown exhibited enhanced sensitivity to 5-fluorouracil, either alone or in combination with oxaliplatin.

Conclusions:

RAD21 expression in CRC is associated with aggressive disease especially in KRAS mutant tumours and resistance to chemoradiotherapy. RAD21 may be an important novel therapeutic target.

Cohesin and CTCF differentially regulate spatiotemporal runx1 expression during zebrafish development

Runx1 is a transcription factor essential for definitive hematopoiesis. In all vertebrates, the Runx1 gene is transcribed from two promoters: a proximal promoter (P2), and a distal promoter (P1). We previously found that runx1 expression in a specific hematopoietic cell population in zebrafish embryos depends on cohesin. Here we show that zebrafish runx1 is directly bound by cohesin and CCCTC binding factor (CTCF) at the P1 and P2 promoters, and within the intron between P1 and P2. Cohesin initiates expression of runx1 in the posterior lateral mesoderm and influences promoter use, while CTCF represses its expression in the newly emerging cells of the tail bud. The intronic binding sites for cohesin and CTCF coincide with histone modifications that confer enhancer-like properties, and two of the cohesin/CTCF sites behaved as insulators in an in vivo assay. The identified cohesin and CTCF binding sites are likely to be cis-regulatory elements (CREs) for runx1 since they also recruit RNA polymerase II (RNAPII). CTCF depletion excluded RNAPII from two intronic CREs but not the promoters of runx1. We propose that cohesin and CTCF have distinct functions in the regulation of runx1 during zebrafish embryogenesis, and that these regulatory functions are likely to involve runx1 intronic CREs. Cohesin (but not CTCF) depletion enhanced RUNX1 expression in a human leukemia cell line, suggesting conservation of RUNX1 regulation through evolution.

A multimarker qPCR platform for the characterisation of endometrial cancer

The molecular background of endometrial cancer (EC) has not been fully elucidated. In the present study, we developed a quantitative PCR (qPCR) platform to examine the gene dosages of the potential molecular markers MGB1, TOP2A, ERBB1-4, MYC, CCND1, ESR1 and PI3K. The platform was applied in samples collected from 157 EC patients (stage I-IV) to verify its clinical utility and to examine the diagnostic and prognostic significance of the analysed biomarkers. The gene dosage pattern of the ERBB family and its downstream effectors PI3K and MYC showed particularly strong correlations with clinicopathological data. The ERBB PI3K/Akt pathway was upregulated in 31 (20%) of 156 cases. Activation of the ERBB PI3K/Akt pathway was positively correlated with a higher stage (p=0.001), higher grade (p=0.001), histological type II disease (p=0.0003) and metastases (p=0.02). The implemented hierarchical clustering revealed that cluster 2 was characterised by high copy numbers of the studied genes. Cluster 2 was associated with shorter overall survival (p=0.05). The platform was found to be a fast and simple method for direct analysis of the genes involved in uterine carcinogenesis, making it feasible for EC biology characterisation.

Screening of key genes in gastric cancer with DNA microarray analysis

Background

The aim of this study was to identify key genes and novel potential therapeutic targets related to gastric cancer (GC) by comparing cancer tissue samples and healthy control samples using DNA microarray analysis.

Methods

Microarray data set GSE19804 was downloaded from Gene Expression Omnibus. Preprocessing and differential analysis were conducted with of R statistical software packages, and a number of differentially expressed genes (DEGs) were obtained. Cluster analysis was also done with gene expression values. Functional enrichment analysis was performed for all the DEGs with DAVID tools. The significantly up- and downregulated genes were selected out and their interactors were retrieved with STRING and HitPredict, followed by construction of networks. For all the genes in the two networks, GeneCodis was chosen for gene function annotation.

Results

A total of 638 DEGs were identified, and we found that SPP1 and FABP4 were the markedly up- and downregulated genes, respectively. Cell cycle and regulation of proliferation were the most significantly overrepresented functional terms in up- and downregulated genes. In addition, extracellular matrix–receptor interaction was found to be significant in the SPP1-included interaction network.

Conclusions

A range of DEGs were obtained for GC. These genes not only provided insights into the pathogenesis of GC but also could develop into biomarkers for diagnosis or treatment.

Sister chromatid cohesion defects are associated with chromosome instability in Hodgkin lymphoma cells

Background

Chromosome instability manifests as an abnormal chromosome complement and is a pathogenic event in cancer. Although a correlation between abnormal chromosome numbers and cancer exist, the underlying mechanisms that cause chromosome instability are poorly understood. Recent data suggests that aberrant sister chromatid cohesion causes chromosome instability and thus contributes to the development of cancer. Cohesion normally functions by tethering nascently synthesized chromatids together to prevent premature segregation and thus chromosome instability. Although the prevalence of aberrant cohesion has been reported for some solid tumors, its prevalence within liquid tumors is unknown. Consequently, the current study was undertaken to evaluate aberrant cohesion within Hodgkin lymphoma, a lymphoid malignancy that frequently exhibits chromosome instability.

Methods

Using established cytogenetic techniques, the prevalence of chromosome instability and aberrant cohesion was examined within mitotic spreads generated from five commonly employed Hodgkin lymphoma cell lines (L-1236, KM-H2, L-428, L-540 and HDLM-2) and a lymphocyte control. Indirect immunofluorescence and Western blot analyses were performed to evaluate the localization and expression of six critical proteins involved in the regulation of sister chromatid cohesion.

Results

We first confirmed that all five Hodgkin lymphoma cell lines exhibited chromosome instability relative to the lymphocyte control. We then determined that each Hodgkin lymphoma cell line exhibited cohesion defects that were subsequently classified into mild, moderate or severe categories. Surprisingly, ~50% of the mitotic spreads generated from L-540 and HDLM-2 harbored cohesion defects. To gain mechanistic insight into the underlying cause of the aberrant cohesion we examined the localization and expression of six critical proteins involved in cohesion. Although all proteins produced the expected nuclear localization pattern, striking differences in RAD21 expression was observed: RAD21 expression was lowest in L-540 and highest within HDLM-2.

Conclusion

We conclude that aberrant cohesion is a common feature of all five Hodgkin lymphoma cell lines evaluated. We further conclude that aberrant RAD21 expression is a strong candidate to underlie aberrant cohesion, chromosome instability and contribute to the development of the disease. Our findings support a growing body of evidence suggesting that cohesion defects and aberrant RAD21 expression are pathogenic events that contribute to tumor development.