Sororin is a master regulator of sister chromatid cohesion and separation

Role of cell division cycle-associated proteins in regulating cell cycle and promoting tumor progression

The cell division cycle-associated protein (CDCA) family is important in regulating cell division. High CDCA expression is significantly linked to tumor development. This review summarizes clinical and basic studies on CDCAs conducted in recent decades. Furthermore, it systematically introduces the molecular expression and function, key mechanisms, cell cycle regulation, and roles of CDCAs in tumor development, cell proliferation, drug resistance, invasion, and metastasis. Additionally, it presents the latest research on tumor diagnosis, prognosis, and treatment targeting CDCAs. These findings are pivotal for further in-depth studies on the role of CDCAs in promoting tumor development and provide theoretical support for their application as new anti-tumor targets.

The maintenance of oocytes in the mammalian ovary involves extreme protein longevity

Women are born with all of their oocytes. The oocyte proteome must be maintained with minimal damage throughout the woman's reproductive life, and hence for decades. Here we report that oocyte and ovarian proteostasis involves extreme protein longevity. Mouse ovaries had more extremely long-lived proteins than other tissues, including brain. These long-lived proteins had diverse functions, including in mitochondria, the cytoskeleton, chromatin and proteostasis. The stable proteins resided not only in oocytes but also in long-lived ovarian somatic cells. Our data suggest that mammals increase protein longevity and enhance proteostasis by chaperones and cellular antioxidants to maintain the female germline for long periods. Indeed, protein aggregation in oocytes did not increase with age and proteasome activity did not decay. However, increasing protein longevity cannot fully block female germline senescence. Large-scale proteome profiling of ~8,890 proteins revealed a decline in many long-lived proteins of the proteostasis network in the aging ovary, accompanied by massive proteome remodeling, which eventually leads to female fertility decline.

Sororin is an evolutionary conserved antagonist of WAPL

Cohesin mediates sister chromatid cohesion to enable chromosome segregation and DNA damage repair. To perform these functions, cohesin needs to be protected from WAPL, which otherwise releases cohesin from DNA. It has been proposed that cohesin is protected from WAPL by SORORIN. However, in vivo evidence for this antagonism is missing and SORORIN is only known to exist in vertebrates and insects. It is therefore unknown how important and widespread SORORIN's functions are. Here we report the identification of SORORIN orthologs in Schizosaccharomyces pombe (Sor1) and Arabidopsis thaliana (AtSORORIN). sor1Δ mutants display cohesion defects, which are partially alleviated by wpl1Δ. Atsororin mutant plants display dwarfism, tissue specific cohesion defects and chromosome mis-segregation. Furthermore, Atsororin mutant plants are sterile and separate sister chromatids prematurely at anaphase I. The somatic, but not the meiotic deficiencies can be alleviated by loss of WAPL. These results provide in vivo evidence for SORORIN antagonizing WAPL, reveal that SORORIN is present in organisms beyond the animal kingdom and indicate that it has acquired tissue specific functions in plants.

CDCA5-EEF1A1 interaction promotes progression of clear cell renal cell carcinoma by regulating mTOR signaling

BACKGROUND

Cell division cycle associated 5 (CDCA5) plays ontogenetic role in various human cancers. However, its specific function and regulatory mechanism in ccRCC remain uncertain.

METHODS

Immunohistochemistry and western blots were performed to investigate the expression of CDCA5 in ccRCC tissues. Genetic knockdown and upregulation of CDCA5 were performed to investigate its functional roles in ccRCC proliferation, migration, apoptosis and sunitinib resistance. Furthermore, Co-IP assay and LC-MS/MS were performed to investigate the underlying mechanisms.

RESULTS

We found that CDCA5 expression is frequently upregulated in ccRCC tumors and is associated with poor prognosis of ccRCC patients. Functionally, CDCA5 promotes proliferation, migration, and sunitinib resistance, while inhibiting apoptosis in ccRCC cells. In vivo mouse xenograft model confirms that silencing of CDCA5 drastically inhibits the growth of ccRCC. Mechanistically, we discovered that CDCA5 interacts with Eukaryotic Translation Elongation Factor 1 Alpha 1 (EEF1A1) to regulate mTOR signaling pathway, thereby promoting ccRCC progression.

CONCLUSIONS

Taken together, our results demonstrate the significant role of CDCA5 in ccRCC progression. The findings may provide insights for the development of new treatment strategies targeting CDCA5 for ccRCC patients.

Role of chromosomal cohesion and separation in aneuploidy and tumorigenesis

Cell division is a crucial process, and one of its essential steps involves copying the genetic material, which is organized into structures called chromosomes. Before a cell can divide into two, it needs to ensure that each newly copied chromosome is paired tightly with its identical twin. This pairing is maintained by a protein complex known as cohesin, which is conserved in various organisms, from single-celled ones to humans. Cohesin essentially encircles the DNA, creating a ring-like structure to handcuff, to keep the newly synthesized sister chromosomes together in pairs. Therefore, chromosomal cohesion and separation are fundamental processes governing the attachment and segregation of sister chromatids during cell division. Metaphase-to-anaphase transition requires dissolution of cohesins by the enzyme Separase. The tight regulation of these processes is vital for safeguarding genomic stability. Dysregulation in chromosomal cohesion and separation resulting in aneuploidy, a condition characterized by an abnormal chromosome count in a cell, is strongly associated with cancer. Aneuploidy is a recurring hallmark in many cancer types, and abnormalities in chromosomal cohesion and separation have been identified as significant contributors to various cancers, such as acute myeloid leukemia, myelodysplastic syndrome, colorectal, bladder, and other solid cancers. Mutations within the cohesin complex have been associated with these cancers, as they interfere with chromosomal segregation, genome organization, and gene expression, promoting aneuploidy and contributing to the initiation of malignancy. In summary, chromosomal cohesion and separation processes play a pivotal role in preserving genomic stability, and aberrations in these mechanisms can lead to aneuploidy and cancer. Gaining a deeper understanding of the molecular intricacies of chromosomal cohesion and separation offers promising prospects for the development of innovative therapeutic approaches in the battle against cancer.

Integrated Multi-omics Analyses Identify CDCA5 as a Novel Biomarker Associated with Alternative Splicing, Tumor Microenvironment, and Cell Proliferation in Colon Cancer Via Pan-cancer Analysis

Background: CDCA5 has been reported as a gene involved in the cell cycle, however current research provides little details. Our goal was to figure out its functions and probable mechanisms in pan-cancer. Methods: Pan-cancer bulk sequencing data and web-based analysis tools were applied to analyze CDCA5's correlations with the gene expression, clinical prognosis, genetic alterations, promoter methylation, alternative splicing, immune checkpoints, tumor microenvironment and enrichment. Real‑time PCR, cell clone formation assay, CCK-8 assay, cell proliferation assay, migration assay, invasion assay and apoptosis assay were used to evaluate the effect of CDCA5 silencing on colon cancer cell lines. Results: CDCA5 is highly expressed in most tumors, which has been linked to a poor prognosis. Immune checkpoints analysis revealed that CDCA5 was associated with the immune gene CD276 in various tumors. Single-cell analysis showed that CDCA5 correlated with proliferating T cell infiltration in COAD. Enrichment analysis demonstrated that CDCA5 may modify cell cycle genes to influence p53 signaling. The examination of DLD1 cells revealed that CDCA5 increased the proliferation and blocked cell apoptosis. Conclusion: This study contributes to the knowledge of the role of CDCA5 in carcinogenesis, highlighting the prognostic potential and carcinogenic involvement of CDCA5 in pan-cancer.

Clinical Efficacy of ONC201 in H3K27M-Mutant Diffuse Midline Gliomas Is Driven by Disruption of Integrated Metabolic and Epigenetic Pathways

Patients with H3K27M-mutant diffuse midline glioma (DMG) have no proven effective therapies. ONC201 has recently demonstrated efficacy in these patients, but the mechanism behind this finding remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue/cerebrospinal fluid (CSF) correlate samples from patients treated in two completed multisite clinical studies. Patients treated with ONC201 following initial radiation but prior to recurrence demonstrated a median overall survival of 21.7 months, whereas those treated after recurrence had a median overall survival of 9.3 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle-related genes in baseline tumor sequencing. ONC201 treatment increased 2-hydroxyglutarate levels in cultured H3K27M-DMG cells and patient CSF samples. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuroglial differentiation genes. Overall, ONC201 demonstrates efficacy in H3K27M-DMG by disrupting integrated metabolic and epigenetic pathways and reversing pathognomonic H3K27me3 reduction.

SIGNIFICANCE

The clinical, radiographic, and molecular analyses included in this study demonstrate the efficacy of ONC201 in H3K27M-mutant DMG and support ONC201 as the first monotherapy to improve outcomes in H3K27M-mutant DMG beyond radiation. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction. This article is featured in Selected Articles from This Issue, p. 2293.

Clinical evidence for a role of E2F1-induced replication stress in modulating tumor mutational burden and immune microenvironment

DNA replication stress (RS) is frequently induced by oncogene activation and is believed to promote tumorigenesis. However, clinical evidence for the role of oncogene-induced RS in tumorigenesis remains scarce, and the mechanisms by which RS promotes cancer development remain incompletely understood. By performing a series of bioinformatic analyses on the oncogene E2F1, other RS-inducing factors, and replication fork processing factors in TCGA cancer database using previously established tools, we show that hyperactivity of E2F1 likely promotes the expression of several of these factors in virtually all types of cancer to induce RS and cytosolic self-DNA production. In addition, the expression of these factors positively correlates with that of ATR and Chk1 that govern the cellular response to RS, the tumor mutational load, and tumor infiltration of immune-suppressive CD4+Th2 cells and myeloid-derived suppressor cells (MDSCs). Consistently, high expression of these factors is associated with poor patient survival. Our study provides new insights into the role of E2F1-induced RS in tumorigenesis and suggests therapeutic approaches for E2F1-overexpressing cancers by targeting genomic instability, cytosolic self-DNA and the tumor immune microenvironment.

The influence of COVID-19 on colorectal cancer was investigated using bioinformatics and systems biology techniques

Introduction

Coronavirus disease 2019 (COVID-19) is a global pandemic and highly contagious, posing a serious threat to human health. Colorectal cancer (CRC) is a risk factor for COVID-19 infection. Therefore, it is vital to investigate the intrinsic link between these two diseases.

Methods

In this work, bioinformatics and systems biology techniques were used to detect the mutual pathways, molecular biomarkers, and potential drugs between COVID-19 and CRC.

Results

A total of 161 common differentially expressed genes (DEGs) were identified based on the RNA sequencing datasets of the two diseases. Functional analysis was performed using ontology keywords, and pathway analysis was also performed. The common DEGs were further utilized to create a protein-protein interaction (PPI) network and to identify hub genes and key modules. The datasets revealed transcription factors-gene interactions, co-regulatory networks with DEGs-miRNAs of common DEGs, and predicted possible drugs as well. The ten predicted drugs include troglitazone, estradiol, progesterone, calcitriol, genistein, dexamethasone, lucanthone, resveratrol, retinoic acid, phorbol 12-myristate 13-acetate, some of which have been investigated as potential CRC and COVID-19 therapies.

Discussion

By clarifying the relationship between COVID-19 and CRC, we hope to provide novel clues and promising therapeutic drugs to treat these two illnesses.

The Comprehensive Analysis Illustrates the Role of CDCA5 in Breast Cancer: An Effective Diagnosis and Prognosis Biomarker

Background

Several studies have been conducted to investigate the role of cell division cycle-associated 5 (CDCA5) in cancer. Its role in breast cancer, however, remains unknown.

Methods

The Gene Expression Omnibus and Cancer Genome Atlas Program databases provided the open-access information needed for the research. The CCK8 and colony formation assays were used to measure cell proliferation. The capacity of breast cancer cells to invade and migrate was assessed using the transwell assay.

Results

In our study, CDCA5 was identified as the interested gene through a series of bioinformatics analysis. We found a higher CDCA5 expression level in tissue and cells of breast cancer. Meanwhile, CDCA5 has been linked to increased proliferation, invasion, and migration of breast cancer cells, which was also associated with worse clinical features. The biochemical pathways, in which CDCA5 was engaged, were identified using biological enrichment analysis. Immune infiltration research revealed that CDCA5 was linked to enhanced activity of several immune function terms. Meanwhile, DNA methylation might be responsible for the aberrant level of CDCA5 in tumor tissue. In addition, CDCA5 could significantly increase the paclitaxel and docetaxel sensitivity, indicating that it has the potential for clinical application. Also, we found that CDCA5 is mainly localized in cell nucleoplasm. Moreover, in the breast cancer microenvironment, we found that CDCA5 is mainly expressed in malignant cells, proliferation T cells, and neutrophils.

Conclusion

Overall, our findings suggest that CDCA5 is a potential prognostic indicator and target for breast cancer, which can indicate the direction of the relevant research.

KLF5-mediated CDCA5 expression promotes tumor development and progression of epithelial ovarian carcinoma

Cell division cycle associated 5 (CDCA5) is correlated with the development and progression of many malignant tumors. However, little is known about its role in epithelial ovarian cancer (EOC) progression. In this study, the clinical value, biological function and underlying mechanisms of CDCA5 in EOC were evaluated. CDCA5 mRNA and protein levels were substantially upregulated in EOC and had a significant positive correlation with adverse clinicopathological characteristics and a poor prognosis. CDCA5 facilitated proliferation, invasion, and metastasis and disrupted mitochondrial-mediated endogenous apoptosis by activating the cell cycle pathway and inhibiting the P53 pathway in EOC cells. Conversely, knockdown of CDCA5 expression blocked the malignant activities of EOC cells and suppressed the growth of xenograft tumors in vivo. Mechanistically, the transcription factor KLF5 bound to a specific site in the CDCA5 promoter and promoted CDCA5 expression. Moreover, KLF5 overexpression rescued the negative regulation of inhibited CDCA5 expression on EOC cell proliferation. In conclusion, our findings revealed that CDCA5 promoted tumor progression of EOC via the KLF5/CDCA5/cell cycle and P53 axes, which might provide new insights into the roles of CDCA5 in EOC.

Deciphering cervical cancer-associated biomarkers by integrated multi-omics approach

OBJECTIVES

Cervical Squamous Cell Carcinoma (CESC) is one of the most fatal female malignancies, and the underlying molecular mechanisms governing this disease have not been fully explored. In this research, we planned to conduct the analysis of Gene Expression Omnibus (GEO) cervical squamous cell carcinoma microarray datasets by a detailed in silico approach and to explore some novel biomarkers of CESC.

METHODS

The top commonly differentially expressed genes (DEGs) from the GSE138080 and GSE113942 datasets were analyzed by Limma package-based GEO2R tool. The protein-protein interaction (PPI) network of the DEGs was drawn through Search Tool for the Retrieval of Interacting Genes (STRING), and top 6 hub genes were obtained from Cytoscape. Expression analysis and validation of hub genes expression in CESC samples and cell lines were done using UALCAN, OncoDB, GENT2, and HPA. Additionally, cBioPortal, Gene set enrichment analysis (GSEA) tool, Kaplan-Meier (KM) plotter, ShinyGO, and DGIdb databases were also used to check some important values of hub genes in CESC.

RESULTS

Out of 79 DEGs, the minichromosome maintenance complex component 4 (MCM4), nucleolar and spindle-associated protein 1 (NUSAP1), cell division cycle associated 5 (CDCA5), cell division cycle 45 (CDC45), denticleless E3 ubiquitin protein ligase homolog (DTL), and chromatin licensing and DNA replication factor 1 (CDT1) genes were regarded as hub genes in CESC. Further analysis revealed that the expressions of all these hub genes were significantly elevated in CESC cell lines and samples of diverse clinical attributes. In this study, we also documented some important correlations between hub genes and some other diverse measures, including DNA methylation, genetic alterations, and Overall Survival (OS). Last, we also identify hub genes associated ceRNA network and 31 important chemotherapeutic drugs.

CONCLUSION

Through detailed in silico methodology, we identified 6 hub genes, including MCM4, NUSAP1, CDCA5, CDC45, DTL, and CDT1, which are likely to be associated with CESC development and diagnosis.

Identification of Candidate Genes in Breast Cancer Induced by Estrogen Plus Progestogens Using Bioinformatic Analysis

Menopausal hormone therapy (MHT) was widely used to treat menopause-related symptoms in menopausal women. However, MHT therapies were controversial with the increased risk of breast cancer because of different estrogen and progestogen combinations, and the molecular basis behind this phenomenon is currently not understood. To address this issue, we identified differentially expressed genes (DEGs) between the estrogen plus progestogens treatment (EPT) and estrogen treatment (ET) using the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data. As a result, a total of 96 upregulated DEGs were first identified. Seven DEGs related to the cell cycle (CCNE2, CDCA5, RAD51, TCF19, KNTC1, MCM10, and NEIL3) were validated by RT-qPCR. Specifically, these seven DEGs were increased in EPT compared to ET (p < 0.05) and had higher expression levels in breast cancer than adjacent normal tissues (p < 0.05). Next, we found that estrogen receptor (ER)-positive breast cancer patients with a higher CNNE2 expression have a shorter overall survival time (p < 0.05), while this effect was not observed in the other six DEGs (p > 0.05). Interestingly, the molecular docking results showed that CCNE2 might bind to 17β-estradiol (−6.791 kcal/mol), progesterone (−6.847 kcal/mol), and medroxyprogesterone acetate (−6.314 kcal/mol) with a relatively strong binding affinity, respectively. Importantly, CNNE2 protein level could be upregulated with EPT and attenuated by estrogen receptor antagonist, acolbifene and had interactions with cancer driver genes (AKT1 and KRAS) and high mutation frequency gene (TP53 and PTEN) in breast cancer patients. In conclusion, the current study showed that CCNE2, CDCA5, RAD51, TCF19, KNTC1, MCM10, and NEIL3 might contribute to EPT-related tumorigenesis in breast cancer, with CCNE2 might be a sensitive risk indicator of breast cancer risk in women using MHT.

Identification of Human Cell Cycle Phase Markers Based on Single-Cell RNA-Seq Data by Using Machine Learning Methods

The cell cycle is composed of a series of ordered, highly regulated processes through which a cell grows and duplicates its genome and eventually divides into two daughter cells. According to the complex changes in cell structure and biosynthesis, the cell cycle is divided into four phases: gap 1 (G1), DNA synthesis (S), gap 2 (G2), and mitosis (M). Determining which cell cycle phases a cell is in is critical to the research of cancer development and pharmacy for targeting cell cycle. However, current detection methods have the following problems: (1) they are complicated and time consuming to perform, and (2) they cannot detect the cell cycle on a large scale. Rapid developments in single-cell technology have made dissecting cells on a large scale possible with unprecedented resolution. In the present research, we construct efficient classifiers and identify essential gene biomarkers based on single-cell RNA sequencing data through Boruta and three feature ranking algorithms (e.g., mRMR, MCFS, and SHAP by LightGBM) by utilizing four advanced classification algorithms. Meanwhile, we mine a series of classification rules that can distinguish different cell cycle phases. Collectively, we have provided a novel method for determining the cell cycle and identified new potential cell cycle-related genes, thereby contributing to the understanding of the processes that regulate the cell cycle.

Loss of cell division cycle‑associated 5 promotes cell apoptosis by activating DNA damage response in clear cell renal cell carcinoma

Cell division cycle-associated 5 (CDCA5) protein, which is involved in cohesion, contributes to cell cycle regulation and chromosome segregation by maintaining genomic stability. Accumulating evidence indicates that CDCA5 expression is upregulated in a number of types of cancer associated with a poor prognosis. However, the biological function of CDCA5 in clear cell renal cell carcinoma (ccRCC) remains largely unknown. In the present study, The Cancer Genome Atlas data mining revealed that CDCA5 was more highly expressed in ccRCC than in adjacent normal tissues. Importantly, such a high expression was associated with a higher risk of distant metastasis and poorer clinical outcomes. Moreover, the clinical and prognostic value of CDCA5 expression was further investigated using immunohistochemistry on tissue microarrays containing paired tumor tissues and adjacent normal tissues from 137 patients with ccRCC. Functional analyses revealed that CDCA5 knockdown significantly inhibited the proliferation and migration of ccRCC cells, and suppressed the growth of xenografts in nude mice. Mechanistically, CDCA5 knockdown induced severe DNA damage with the persistent accumulation of γ-H2A histone family member X foci, resulting in G2/M cell cycle arrest and finally, in chromosomal instability and apoptosis. CDCA5 knockdown significantly decreased the phosphorylation levels of Stat3 and NF-κB, suggesting that CDCA5 plays a role in regulating the inflammatory response. Collectively, the findings of the present study indicate that ccRCC cells require CDCA5 for malignant progression, and that CDCA5 inhibition may enhance the outcomes of patients with high-risk ccRCC.

Knockdown of CDCA5 suppresses malignant progression of breast cancer cells by regulating PDS5A

Breast cancer is one of the most common malignant tumors in women. Cell division cycle‑associated 5 (CDCA5) is closely associated with the behavior of various cancer types. The aim of the present study was to explore the effect of CDCA5 on breast cancer. Western blot analysis and reverse transcription‑quantitative PCR were used to detect the expression level of CDCA5 in human normal mammary cells and human breast cancer cell lines. To determine its function in MDA‑MB‑231 cells, CDCA5 was silenced in MDA‑MB‑231 cells by transient short hairpin RNA transfection. Cell Counting Kit‑8 and clonogenicity assays were used to evaluate cell proliferation. Wound healing and Transwell assays were used to detect cell invasion and migration. Western blot analysis was used to detect the protein expressions of Ki67 and PCNA associated with proliferation, MMP2 and MMP9 associated with migration. CDCA5 was found to be markedly increased in breast cancer cell lines. CDCA5 knockdown was able to suppress cell proliferation, invasion and migration. CDCA5 inhibition downregulated PDS5 cohesin‑associated factor A (PDS5A) expression in breast cancer cells. PDS5A overexpression was found to reverse the effect of CDCA5 inhibition on breast cancer cell proliferation and migration. CDCA5 knockdown was shown to suppress the malignant progression of breast cancer cells by regulating PDS5A. The present findings may provide new potential targets for breast cancer therapy.

The Cohesin Complex and Its Interplay with Non-Coding RNAs

The cohesin complex is a multi-subunit protein complex initially discovered for its role in sister chromatid cohesion. However, cohesin also has several other functions and plays important roles in transcriptional regulation, DNA double strand break repair, and chromosome architecture thereby influencing gene expression and development in organisms from yeast to man. While most of these functions rely on protein–protein interactions, post-translational protein, as well as DNA modifications, non-coding RNAs are emerging as additional players that facilitate and modulate the function or expression of cohesin and its individual components. This review provides a condensed overview about the architecture as well as the function of the cohesin complex and highlights its multifaceted interplay with both short and long non-coding RNAs.

Discovery and Validation of a Compound to Target Ewing's Sarcoma

Ewing’s sarcoma, characterized by pathognomonic t (11; 22) (q24; q12) and related chromosomal ETS family translocations, is a rare aggressive cancer of bone and soft tissue. Current protocols that include cytotoxic chemotherapeutic agents effectively treat localized disease; however, these aggressive therapies may result in treatment-related morbidities including second-site cancers in survivors. Moreover, the five-year survival rate in patients with relapsed, recurrent, or metastatic disease is less than 30%, despite intensive therapy with these cytotoxic agents. By using high-throughput phenotypic screening of small molecule libraries, we identified a previously uncharacterized compound (ML111) that inhibited in vitro proliferation of six established Ewing’s sarcoma cell lines with nanomolar potency. Proteomic studies show that ML111 treatment induced prometaphase arrest followed by rapid caspase-dependent apoptotic cell death in Ewing’s sarcoma cell lines. ML111, delivered via methoxypoly(ethylene glycol)-polycaprolactone copolymer nanoparticles, induced dose-dependent inhibition of Ewing’s sarcoma tumor growth in a murine xenograft model and invoked prometaphase arrest in vivo, consistent with in vitro data. These results suggest that ML111 represents a promising new drug lead for further preclinical studies and is a potential clinical development for the treatment of Ewing’s sarcoma.

PDS5A and PDS5B in Cohesin Function and Human Disease

Precocious dissociation of sisters 5 (PDS5) is an associate protein of cohesin that is conserved from yeast to humans. It acts as a regulator of the cohesin complex and plays important roles in various cellular processes, such as sister chromatid cohesion, DNA damage repair, gene transcription, and DNA replication. Vertebrates have two paralogs of PDS5, PDS5A and PDS5B, which have redundant and unique roles in regulating cohesin functions. Herein, we discuss the molecular characteristics and functions of PDS5, as well as the effects of its mutations in the development of diseases and their relevance for novel therapeutic strategies.

Identifying and Validating Potential Biomarkers of Early Stage Lung Adenocarcinoma Diagnosis and Prognosis

Background

Lung adenocarcinoma (LUAD) is the most common pathological type of lung cancer. At present, most patients with LUAD are diagnosed at an advanced stage, and the prognosis of advanced LUAD is poor. Hence, we aimed to identify novel biomarkers for the diagnosis and treatment of early stage LUAD and to explore their predictive value.

Methods

The microarray datasets GSE63459, GSE27262, and GSE33532 were searched, and the differentially expressed genes (DEGs) were obtained using GEO2R. The DEGs were subjected to gene ontology (GO) and pathway enrichment analyses using METASCAPE. A protein–protein interaction (PPI) network was plotted with STRING and visualized by Cytoscape. Module analysis of the PPI network was performed using MCODE. Overall survival (OS) analysis and analysis of the mRNA expression levels of genes identified by MCODE were performed with UALCAN. Western blot analysis of hub genes in LUAD patients, MTS assays, and clonogenic assays were performed to test the effects of the hub genes on cell proliferation in vitro.

Results

A total of 341 DEGs were obtained, which were mainly enriched in terms related to blood vessel development, growth factor binding, and extracellular matrix organization. A PPI network consisting of 300 nodes and 1140 edges was constructed, and a significant module including 15 genes was identified. Elevated expression of ASPM, CCNB2, CDCA5, PRC1, KIAA0101, and UBE2T was associated with poor OS in LUAD patients. In the protein level, the hub gene was overexpressed in LUAD patients. In vitro experiments showed that knockdown of the hub genes in the LUAD cell lines could promote cell proliferation.

Conclusions

DEGs are potential biomarkers for early stage lung adenocarcinoma and could have utility for the diagnosis and predicting treatment efficacy.

CDCA5 promotes the progression of prostate cancer by affecting the ERK signalling pathway

Cell division cycle-associated 5 (CDCA5) can regulate cell cycle-related proteins to promote the proliferation of cancer cells. The purpose of the present study was to investigate the expression level of CDCA5 in prostate cancer (PCa) and its effect on PCa progression. The signalling pathway by which CDCA5 functions through was also attempted to elucidate. Clinical specimens of PCa patients were collected from the Second Hospital of Tianjin Medical University. The expression level of CDCA5 in cancer tissues and paracancerous tissues from PCa patients was detected by RT-qPCR analysis and IHC. The relationship between the expression level of CDCA5 and the survival rate of PCa patients was analysed using TCGA database. Two stable cell lines (C4-2 and PC-3) with CDCA5 knockdown were established, and the effects of CDCA5 on PCa cell proliferation were detected by MTT and colony formation assays. Flow cytometry was performed to detect the effect of CDCA5 on the PCa cell division cycle, and western blot analysis was used to determine changes in ERK phosphorylation levels after CDCA5 knockdown. The effect of CDCA5 expression on prostate tumour growth was assessed using a mouse xenograft model. The results revealed that the mRNA and protein expression levels of CDCA5 were significantly higher in PCa tissues than in paracancerous tissues. High CDCA5 expression was associated with the prognosis of patients with PCa. CDCA5 expression knockdown significantly reduced the number of PCa cells in mitoses and inhibited their proliferation in vitro and in vivo. When CDCA5 was knocked down, the phosphorylation level of ERK was also reduced. Collectively, CDCA5 was upregulated and affected the prognosis of patients with PCa. Decreased CDCA5 expression inhibited PCa cell proliferation by inhibiting the ERK signalling pathway. Thus, CDCA5 may be a potential therapeutic target for PCa.

WAPL induces cervical intraepithelial neoplasia modulated with estrogen signaling without HPV E6/E7

Since cervical cancer still afflicts women around the world, it is necessary to understand the underlying mechanism of cervical cancer development. Infection with HPV is essential for the development of cervical intraepithelial neoplasia (CIN). In addition, estrogen receptor signaling is implicated in the development of cervical cancer. Previously, we have isolated human wings apart-like (WAPL), which is expected to cause chromosomal instability in the process of HPV-infected precancerous lesions to cervical cancer. However, the role of WAPL in the development of CIN is still unknown. In this study, in order to elucidate the role of WAPL in the early lesion, we established WAPL overexpressing mice (WAPL Tg mice) and HPV E6/E7 knock-in (KI) mice. WAPL Tg mice developed CIN lesion without HPV E6/E7. Interestingly, in WAPL Tg mice estrogen receptor 1 (ESR1) showed reduction as compared with the wild type, but cell growth factors MYC and Cyclin D1 controlled by ESR1 expressed at high levels. These results suggested that WAPL facilitates sensitivity of ESR1 mediated by some kind of molecule, and as a result, affects the expression of MYC and Cyclin D1 in cervical cancer cells. To detect such molecules, we performed microarray analysis of the uterine cervix in WAPL Tg mice, and focused MACROD1, a co-activator of ESR1. MACROD1 expression was increased in WAPL Tg mice compared with the wild type. In addition, knockdown of WAPL induced the downregulation of MACROD1, MYC, and Cyclin D1 but not ESR1 expression. Furthermore, ESR1 sensitivity assay showed lower activity in WAPL or MACROD1 downregulated cells than control cells. These data suggested that WAPL increases ESR1 sensitivity by activating MACROD1, and induces the expression of MYC and Cyclin D1. Therefore, we concluded that WAPL not only induces chromosomal instability in cervical cancer tumorigenesis, but also plays a key role in activating estrogen receptor signaling in early tumorigenesis.

Integrate analysis of the promote function of Cell division cycle-associated protein family to pancreatic adenocarcinoma

Background: The cell division cycle-associated (CDCA) protein family plays a pivotal role in the regulation of the cell cycle during tumorigenesis and predicts the prognosis of tumors, but an analysis of these proteins in pancreatic adenocarcinoma (PAAD) is still lacking. Methods: Oncomine and GEPIA were used to observe the expression and prognostic value of eight CDCAs in pan-cancer. Univariate Cox analysis of single CDCAs and multivariate Cox analysis of all eight CDCAs were performed to evaluate the integrated prognostic value of CDCAs, and the results are displayed as hazard ratios (HRs) and 95% confidence intervals (95% CIs). K-M plots and receiver operating characteristics curves were used to display the predicted function and accuracy of CDCAs to determine the risk score. Annotation of CDCA-related genes, gene sets enrichment analysis (GSEA) and gene sets variation analysis (GSVA) were performed to reveal the CDCAs that impact biological processes. Results: CDCAs expression in most tumors is higher than that in normal tissues and is associated with a poor prognosis. Regarding PAAD, increased CDCA expression along with advanced PAAD tumor stage, NUF2, CDCA2, CDCA3, CDCA4 and CDCA5 expression are risk factors for poor prognosis, while CBX2 expression is a protective factor (P < 0.05). The integrated prognostic value of CDCAs in PAAD patients was validated by SurvExpress in the TCGA-PAAD cohort (P < 0.001, HR = 2.16, 95% CI = 1.41-3.3) and the ICGC-PACA cohort (P < 0.001, HR = 2.56, 95% CI = 1.73-3.79). Genetic alteration and DNA methylation of CDCAs might not affect the prognosis of PAAD patients. After comparing high- and low-risk groups separated by CDCA risk scores, the activated pathways were revealed and included the cell cycle, DNA repair, P53, MYC-targets, E2F-targets and PI3K pathways. Conclusion: CDCAs can predict the OS prognosis of PAAD patients. The cell cycle, DNA repair, E2F, P53 and PI3K signaling pathways, in which CDCAs are involved, impact the tumorigenesis of PAAD.

Cohesin subunit RAD21: From biology to disease

RAD21 (also known as KIAA0078, NXP1, HR21, Mcd1, Scc1, and hereafter called RAD21), an essential gene, encodes a DNA double-strand break (DSB) repair protein that is evolutionarily conserved in all eukaryotes from budding yeast to humans. RAD21 protein is a structural component of the highly conserved cohesin complex consisting of RAD21, SMC1a, SMC3, and SCC3 [STAG1 (SA1) and STAG2 (SA2) in metazoans] proteins, involved in sister chromatid cohesion. This function is essential for proper chromosome segregation, post-replicative DNA repair, and prevention of inappropriate recombination between repetitive regions. In interphase, cohesin also functions in the control of gene expression by binding to numerous sites within the genome. In addition to playing roles in the normal cell cycle and DNA DSB repair, RAD21 is also linked to the apoptotic pathways. Germline heterozygous or homozygous missense mutations in RAD21 have been associated with human genetic disorders, including developmental diseases such as Cornelia de Lange syndrome (CdLS) and chronic intestinal pseudo-obstruction (CIPO) called Mungan syndrome, respectively, and collectively termed as cohesinopathies. Somatic mutations and amplification of the RAD21 have also been widely reported in both human solid and hematopoietic tumors. Considering the role of RAD21 in a broad range of cellular processes that are hot spots in neoplasm, it is not surprising that the deregulation of RAD21 has been increasingly evident in human cancers. Herein, we review the biology of RAD21 and the cellular processes that this important protein regulates and discuss the significance of RAD21 deregulation in cancer and cohesinopathies.

Cyclin-Dependent Kinase 1 (CDK1) is Co-Expressed with CDCA5: Their Functions in Gastric Cancer Cell Line MGC-803

Background

Gastric cancer (GC) is a worldwide malignancy and the molecular mechanism of the GC carcinogenesis has not been fully elucidated. Our previous study suggested CDCA5 played a role in GC development via regulating cell proliferation, migration, and apoptosis in GC cells.

Material/Methods

Here, we first carried out bioinformatics analysis and found cyclin-dependent kinase 1 (CDK1) was possibly associated with CDCA5 using STRING. Then, the expression levels of CDK1 and CDCA5 in cancer tissues were estimated through Oncomine and The Cancer Genome Atlas (TCGA) database. After that, functional experiments were exerted to detect the association of CDK1 and CDCA5. Finally, cell proliferation assay, colon formation assay, cell scratch assay, transwell migration and invasion assays were applied to explore the roles of CDK1 and CDCA5 in GC cells MGC-803.

Results

CDK1 and CDCA5 were both upregulated and co-expressed in GC tissues. The expression of CDK1 and CDCA5 in MGC-803 was positively related. CDK1 or CDCA5 inhibition can suppress the proliferation, colon formation, migration, and invasion abilities of GC cells.

Conclusions

Co-expression of CDK1 and CDCA5 might confer cell proliferation, migration, and invasion abilities in GC cells, and this can provide some clues for further therapies of gastric tumors.

Clinical correlation of opposing molecular signatures in head and neck squamous cell carcinoma

Background

The concept of head and neck cancers (HNSCC) having unique molecular signatures is well accepted but relating this to clinical presentation and disease behaviour is essential for patient benefit. Currently the clinical significance of HNSCC molecular subtypes is uncertain therefore personalisation of HNSCC treatment is not yet possible.

Methods

We performed meta-analysis on 8 microarray studies and identified six significantly up- (PLAU, FN1, CDCA5) and down-regulated (CRNN, CLEC3B and DUOX1) genes which were subsequently quantified by RT-qPCR in 100 HNSCC patient margin and core tumour samples.

Results

Retrospective correlation with sociodemographic and clinicopathological patient details identified two subgroups of opposing molecular signature (+q6 and -q6) that correlated to two recognised high-risk HNSCC populations in the UK. The +q6 group were older, male, and excessive alcohol users whilst the –q6 group were younger, female, paan-chewers and predominantly Bangladeshi. Additionally, all patients with tumour recurrence were in the latter subgroup.

Conclusions

We provide the first evidence linking distinct molecular signatures in HNSCC with clinical presentations. Prospective trials are required to determine the correlation between these distinct genotypes and disease progression or treatment response. This is an important step towards the ultimate goal of improving outcomes by utilising personalised molecular-signature-guided treatments for HNSCC patients.

Systematic cancer-testis gene expression analysis identified CDCA5 as a potential therapeutic target in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies with poor prognosis. Cancer-testis genes (CTGs) have been vigorously pursued as targets for cancer immunotherapy, but the expressive patterns and functional roles of CTGs remain unclear in ESCC.

METHODS

A systematic screening strategy was adopted to screen CTGs in ESCC by integrating multiple public databases and RNA expression microarray data from 119 ESCC subjects. For the newly identified ESCC prognosis-associated CTGs, an independent cohort of 118 patients with ESCC was recruited to validate the relationship via immunohistochemistry. Furthermore, functional assays were performed to determine the underlying mechanisms.

FINDINGS

21 genes were recognized as CTGs, in particular, CDCA5 was aberrantly upregulated in ESCC tissues and significantly associated with poor prognosis (HR = 1.85, 95%CI: 1.14-3.01, P = .013). Immunohistochemical staining confirmed that positive CDCA5 expression was associated with advanced TNM staging and a shorter overall survival rate (45.59% vs 28.00% for CDCA5-/+ subjects, P = 1.86 × 10-3). H3K27 acetylation in CDCA5 promoter might lead to the activation of CDCA5 during ESCC tumorigenesis. Functionally, in vitro assay of gain- and loss-of-function of CDCA5 suggested that CDCA5 could promote ESCC cells proliferation, invasion, migration, apoptosis resistance and reduce chemosensitivity to cisplatin. Moreover, in vivo assay showed that silenced CDCA5 could inhibit tumor growth. Mechanistically, CDCA5 knockdown led to an arrest in G2/M phase and changes in the expression of factors that played fundamental roles in the cell cycle pathway.

INTERPRETATION

CDCA5 contributed to ESCC progression and might serve as an attractive target for ESCC immunotherapy. FUND: This work was supported by the Natural Science Foundation of Jiangsu Province (No. BK20181083 and BK20181496), Jiangsu Top Expert Program in Six Professions (No. WSW-003 and WSW-007), Major Program of Science and Technology Foundation of Jiangsu Province (No. BE2016790 and BE2018746), Jiangsu Medical Young Talent Project (No. QNRC2016566), the Program of Jiangsu Medical Innovation Team (No. CXTDA2017006), Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX18_1487) and Jiangsu Province 333 Talents Project (No. BRA2017545).

CDCA5, Transcribed by E2F1, Promotes Oncogenesis by Enhancing Cell Proliferation and Inhibiting Apoptosis via the AKT Pathway in Hepatocellular Carcinoma

Cell division cycle associated 5 (CDCA5) is an important element for the interaction between cohesin and chromatin in interphase. It is abnormally expressed in many types of cancer and works as an indicator of poor prognosis, but little is known about its activity in hepatocellular carcinoma (HCC). In the present study, we found that the expression of CDCA5 was upregulated in HCC tissues compared to paracancerous tissues and had a negative correlation with patient survival. Cell proliferation and tumorigenesis were inhibited and cell apoptosis was induced with the knockdown of CDCA5, suggesting an oncogenic role of CDCA5 in liver cancer. Luciferase reporter assay and chromatin immunoprecipitation showed that CDCA5 was transcribed by E2F1. Furthermore, we confirmed that CDCA5 interrupted cell behavior via the AKT pathway. These findings demonstrated that CDCA5 plays an important role in HCC progression.

Cell division cycle associated 5 promotes colorectal cancer progression by activating the ERK signaling pathway

Cell division cycle associated 5 (CDCA5) is implicated in the development and progression of a variety of human cancers. Functional significance of CDCA5 in colorectal cancer (CRC), however, has not been investigated. Using a combination of on-line data mining, biochemistry, and molecular biology, we examined the potential oncogenic activity of CDCA5 and the underlying mechanisms. Experiments with human tissue sample showed increased CDCA5 expression in CRC vs. in noncancerous adjacent tissue, and association of CDCA5 upregulation in CRC tissues with shorter patient survival. Also, representative CRC cell-lines had higher CDCA5 expression vs. fetal colonic mucosal cells. CDCA5 knockdown using lentivirus-mediated shRNA inhibited the proliferation and induced apoptosis in cultured HCT116 and HT-29 cells, and suppressed the growth of xenograft in nude mice. CDCA5 knockdown decreased the expression of CDK1 and CyclinB1, increased caspase-3 activity, cleaved PARP and the Bax/Bcl-2 ratio. CDCA5 knockdown also significantly decreased phosphorylation of ERK1/2 and expression of c-jun. Taken together, these findings suggest a significant role in CRC progression of CRC, likely by activating the ERK signaling pathway.

Splicing alterations contributing to cancer hallmarks in the liver: central role of dedifferentiation and genome instability

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide. HCCs are molecularly heterogeneous tumors, and this complexity is to a great extent responsible for their poor response to conventional and targeted therapies. In this review we summarize recent evidence indicating that imbalanced expression of mRNA splicing factors can be a relevant source for this heterogeneity. We also discuss how these alterations may play a driver role in hepatocarcinogenesis by impinging on the general hallmarks of cancer. Considering the natural history of HCC, we focused on two pathogenic features that are characteristic of liver tumors: chromosomal instability and phenotypic de-differentiation. We highlight mechanisms connecting splicing derangement with these two processes and the enabling capacities acquired by liver cells along their neoplastic transformation. A thorough understanding of the alterations in the splicing machinery may also help to identify new HCC biomarkers and to design novel therapeutic strategies.

Silencing of CDCA5 inhibits cancer progression and serves as a prognostic biomarker for hepatocellular carcinoma

Cell division cycle associated 5 (CDCA5) has been associated with the progression of several types of cancers. However, its possible role and mechanism in hepatocellular carcinoma (HCC) remain unknown. In the present study, immunohistochemical staining and real-time PCR were used to assess CDCA5 protein and mRNA levels in clinical samples. Statistical analysis was performed to explore the clinical correlation between CDCA5 protein expression and clinicopathological features and overall survival in HCC patients. Cell counting and colony formation assays were employed to analyse the effect of CDCA5 on cell proliferation, and flow cytometry was used to study the role of CDCA5 in cell cycle progression and apoptosis. Moreover, subcutaneous xenograft tumour models were implemented to predict the efficacy of targeting CDCA5 in HCC in vivo. We found that CDCA5 expression was significantly higher in HCC tumour tissues, was associated with clinicopathological characteristics, and predicted poor overall survival in HCC patients. Silencing of CDCA5 with small interfering RNA (siRNA) inhibited cell proliferation and induced G2/M cell cycle arrest in vitro. The xenograft growth assay revealed that CDCA5 downregulation impeded HCC growth in vivo. Further study indicated that CDCA5 depletion decreased the levels of ERK1/2 and AKT phosphorylation in vitro and in vivo. Taken together, these results indicate that CDCA5 may act as a novel prognostic biomarker and therapeutic target for HCC.

Distinct expression of CDCA3, CDCA5, and CDCA8 leads to shorter relapse free survival in breast cancer patient

Breast cancer is a dangerous disease that results in high mortality rates for cancer patients. Many methods have been developed for the treatment and prevention of this disease. Determining the expression patterns of certain target genes in specific subtypes of breast cancer is important for developing new therapies for breast cancer. In the present study, we performed a holistic approach to screening the mRNA expression of six members of the cell division cycle-associated gene family (CDCA) with a focus on breast cancer using the Oncomine and The Cancer Cell Line Encyclopedia (CCLE) databases. Furthermore, Gene Expression-Based Outcome for Breast Cancer Online (GOBO) was also used to deeply mine the expression of each CDCA gene in clinical breast cancer tissue and breast cancer cell lines. Finally, the mRNA expression of the CDCA genes as related to breast cancer patient survival were analyzed using a Kaplan-Meier plot. CDCA3, CDCA5, and CDCA8 mRNA expression levels were significantly higher than the control sample in both clinical tumor sample and cancer cell lines. These highly expressed genes in the tumors of breast cancer patients dramatically reduced patient survival. The interaction network of CDCA3, CDCA5, and CDCA8 with their co-expressed genes also revealed that CDCA3 expression was highly correlated with cell cycle related genes such as CCNB2, CDC20, CDKN3, and CCNB1. CDCA5 expression was correlated with BUB1 and TRIP13, while CDCA8 expression was correlated with BUB1 and CCNB1. Altogether, these findings suggested CDCA3, CDCA5, and CDCA8 could have a high potency as targeted breast cancer therapies.

Role of triosephosphate isomerase and downstream functional genes on gastric cancer

Triosephosphate isomerase (TPI) is highly expressed in many types of human tumors and is involved in migration and invasion of cancer cells. However, TPI clinicopathological significance and malignant function in gastric cancer (GC) have not been well defined. The present study aimed to examine TPI expression in GC tissue and its biological functions. Furthermore, we investigated its downstream genes by gene chip technology. Our results showed that TPI expression was higher in gastric cancer tissues than adjacent tissues, although no statistical differences were found between TPI expression and clinicopathological factors. TPI overexpression in human gastric carcinoma cell line BGC-823 enhanced cell proliferation, invasion and migration, but did not change cell cycle distribution, while TPI knockdown suppressed proliferation, invasion and migration, induced apoptosis and increased G2/M arrest of human gastric carcinoma cell line MGC-803. Since the cell division cycle associated 5 (CDCA5) was identified as the one with the most decreased expression after TPI knockdown, we investigated its role in MGC-803 cells. The results showed that CDCA5 knockdown also inhibited proliferation, migration, induced apoptosis and increased G2/M arrest similarly to TPI knockdown. CDCA5 overexpression promoted MGC-803 cell proliferation, clone formation and migration abilities. These results indicated that TPI expression level might affect GC cell behavior, suggesting that both TPI and CDCA5 might be considered as potential tumor markers related with GC development and might be potential new targets in GC treatment.

Pds5 Regulates Sister-Chromatid Cohesion and Chromosome Bi-orientation through a Conserved Protein Interaction Module

Sister-chromatid cohesion is established by the cohesin complex in S phase and persists until metaphase, when sister chromatids are captured by microtubules emanating from opposite poles [1]. The Aurora-B-containing chromosome passenger complex (CPC) plays a crucial role in achieving chromosome bi-orientation by correcting erroneous microtubule attachment [2]. The centromeric localization of the CPC relies largely on histone H3-T3 phosphorylation (H3-pT3), which is mediated by the mitotic histone kinase Haspin/Hrk1 [3-5]. Hrk1 localization to centromeres depends largely on the cohesin subunit Pds5 in fission yeast [5]; however, it is unknown how Pds5 regulates Hrk1 localization. Here we identify a conserved Hrk1-interacting motif (HIM) in Pds5 and a Pds5-interacting motif (PIM) in Hrk1 in fission yeast. Mutations in either motif result in the displacement of Hrk1 from centromeres. We also show that the mechanism of Pds5-dependent Hrk1 recruitment is conserved in human cells. Notably, the PIM in Haspin/Hrk1 is reminiscent of the YSR motif found in the mammalian cohesin destabilizer Wapl and stabilizer Sororin, both of which bind PDS5 [6-12]. Similarly, and through the same motifs, fission yeast Pds5 binds to Wpl1/Wapl and acetyltransferase Eso1/Eco1, in addition to Hrk1. Thus, we have identified a protein-protein interaction module in Pds5 that serves as a chromatin platform for regulating sister-chromatid cohesion and chromosome bi-orientation.

Therapeutic potential of targeting cell division cycle associated 5 for oral squamous cell carcinoma

Molecularly targeted drugs are used in the treatment of a variety of malignant tumors, but this approach to developing novel therapies for oral squamous cell carcinoma (OSCC) has lagged behind the progress seen for other cancers. We have attempted to find appropriate molecular targets for OSCC and identified cell division cycle associated 5 (CDCA5) as a cancer-related gene which was overexpressed in all the human OSCC cells tested by microarray analysis. In this study, we investigated the expression and function of CDCA5 in OSCC. First, we confirmed that CDCA5 was overexpressed in 4 human OSCC cell lines by quantitative RT-PCR and Western blotting. We then tested the effect of synthetic small interfering RNAs specific for CDCA5 on the growth and invasion of human OSCC cells. Knockdown of CDCA5 markedly inhibited the growth of OSCC cells in vitro and in vivo. We also examined the expression of CDCA5 protein in 80 cases of OSCC immunohistochemically and found a significant association between CDCA5 expression levels and overall survival. These results suggest that CDCA5 functions as a critical gene supporting OSCC progression and that targeting CDCA5 may be a useful therapeutic strategy for OSCC.

SORORIN and PLK1 as potential therapeutic targets in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive type of cancer of the thoracic cavity commonly associated with asbestos exposure and a high mortality rate. There is a need for new molecular targets for the development of more effective therapies for MPM. Using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and an RNA interference-based screening, we examined the SORORIN gene as potential therapeutic targets for MPM in addition to the PLK1 gene, which is known for kinase of SORORIN. Following in vitro investigation of the effects of target silencing on MPM cells, cell cycle analyses were performed. SORORIN expression was analyzed immunohistochemically using a total of 53 MPM samples on tissue microarray. SORORIN was found to be overexpressed in the majority of clinical MPM samples and human MPM cell lines as determined by qRT-PCR. Gene suppression of each SORORIN and PLK1 led to growth inhibition in MPM cell lines. Knockdown of SORORIN showed an increased number of G2M-phase population and a larger nuclear size, suggesting mitotic arrest. High expression of SORORIN (SORORIN-H) was found in 50.9% of all the MPM cases, and there is a tendency towards poorer prognosis for the SORORIN-H group but the difference is not significant. Suppression of SORORIN with PLK1 inhibitor BI 6727 showed a combinational growth suppressive effect on MPM cell growth. Given high-dose PLK1 inhibitor induced drug-related adverse effects in several clinical trials, our results suggest inhibition SORORIN-PLK1 axis may hold promise for the treatment of MPMs.

Cohesin Removal along the Chromosome Arms during the First Meiotic Division Depends on a NEK1-PP1γ-WAPL Axis in the Mouse

Mammalian NIMA-like kinase-1 (NEK1) is a dual-specificity kinase highly expressed in mouse germ cells during prophase I of meiosis. Loss of NEK1 induces retention of cohesin on chromosomes at meiotic prophase I. Timely deposition and removal of cohesin is essential for accurate chromosome segregation. Two processes regulate cohesin removal: a non-proteolytic mechanism involving WAPL, sororin, and PDS5B and direct cleavage by separase. Here, we demonstrate a role for NEK1 in the regulation of WAPL loading during meiotic prophase I, via an interaction between NEK1 and PDS5B. This regulation of WAPL by NEK1-PDS5B is mediated by protein phosphatase 1 gamma (PP1γ), which both interacts with and is a phosphotarget of NEK1. Taken together, our results reveal that NEK1 phosphorylates PP1γ, leading to the dephosphorylation of WAPL, which, in turn, results in its retention on chromosome cores to promote loss of cohesion at the end of prophase I in mammals.

Sororin loads to the synaptonemal complex central region independently of meiotic cohesin complexes

The distribution and regulation of the cohesin complexes have been extensively studied during mitosis. However, the dynamics of their different regulators in vertebrate meiosis is largely unknown. In this work, we have analyzed the distribution of the regulatory factor Sororin during male mouse meiosis. Sororin is detected at the central region of the synaptonemal complex during prophase I, in contrast with the previously reported localization of other cohesin components in the lateral elements. This localization of Sororin depends on the transverse filaments protein SYCP1, but not on meiosis-specific cohesin subunits REC8 and SMC1β. By late prophase I, Sororin accumulates at centromeres and remains there up to anaphase II The phosphatase activity of PP2A seems to be required for this accumulation. We hypothesize that Sororin function at the central region of the synaptonemal complex could be independent on meiotic cohesin complexes. In addition, we suggest that Sororin participates in the regulation of centromeric cohesion during meiosis in collaboration with SGO2-PP2A.

CDCA5 overexpression is an indicator of poor prognosis in patients with urothelial carcinomas of the upper urinary tract and urinary bladder

AIMS

Urothelial carcinoma (UC) is the most common tumor involving upper urinary tract (UTUC) and urinary bladder (UBUC) whose molecular survival determinants remains obscured. By computerizing a public transcriptomic database of UBUCs (GSE32894), we identified cell division cycle associated 5 (CDCA5) as the most significantly upregulated gene among those associated with G1-S transition of the mitotic cell cycle (GO:0000082). We therefore analyzed the clinicoptaological significance of CDCA5 expression in our well-characterized UC cohort.

METHODS AND RESULTS

Quantigene assay was used to detect CDCA5 transcript levels in 36 UTUCs and 30 UBUCs. We used immunohistochemistry evaluated by H-scores to determine CDCA5 protein expression in 295 UBUCs and 340 UTUCs, respectively. CDCA5 expression was further correlated with clinicopathological features and disease-specific survival (DSS) and metastasis-free survival (MeFS). For both groups of UCs, increments of CDCA5 transcript levels were associated with higher pT status, CDCA5 protein overexpression was also significantly associated with advanced pT status, nodal metastasis, high histological grade, vascular invasion, and frequent mitoses. CDCA5 overexpression was predictive for worse DSS and MeFS in univariate and multivariate analysis.

CONCLUSIONS

CDCA5 overexpression is associated with advanced clinical features of UC, suggesting its potential value as a prognostic biomarker and a novel therapeutic target.

The activity regulation of the mitotic centromere-associated kinesin by Polo-like kinase 1

The mitotic centromere-associated kinesin (MCAK), a potent microtubule depolymerase, is involved in regulating microtubule dynamics. The activity and subcellular localization of MCAK are tightly regulated by key mitotic kinases, such as Polo-like kinase 1 (Plk1) by phosphorylating multiple residues in MCAK. Since Plk1 phosphorylates very often different residues of substrates at different stages, we have dissected individual phosphorylation of MCAK by Plk1 and characterized its function in more depth. We have recently shown that S621 in MCAK is the major phosphorylation site of Plk1, which is responsible for regulating MCAK's degradation by promoting the association of MCAK with APC/CCdc20. In the present study, we have addressed another two residues phosphorylated by Plk1, namely S632/S633 in the C-terminus of MCAK. Our data suggest that Plk1 phosphorylates S632/S633 and regulates its catalytic activity in mitosis. This phosphorylation is required for proper spindle assembly during early phases of mitosis. The subsequent dephosphorylation of S632/S633 might be necessary to timely align the chromosomes onto the metaphase plate. Therefore, our studies suggest new mechanisms by which Plk1 regulates MCAK: the degradation of MCAK is controlled by Plk1 phosphorylation on S621, whereas its activity is modulated by Plk1 phosphorylation on S632/S633 in mitosis.

C-terminus of Sororin interacts with SA2 and regulates sister chromatid cohesion

Sororin is a conserved protein required for accurate separation of sister chromatids in each cell cycle. Sororin is recruited to chromatin during DNA replication, protects sister chromatid cohesion in S and G2 phase, and regulates the resolution of sister chromatid cohesion in mitosis. Sororin binds to cohesin complex, but how Sororin and cohesin subunits interact remains unclear. Here we report that the C-terminus of Sororin, especially the last 12 amino acid (aa) residues, is important for Sororin to bind cohesin core subunit SA2. Deletion of the last 12aa residues not only inhibits the interactions between Sororin and SA2 but also causes precocious chromosome separation. Our data suggest that the C-terminus of Sororin functions as an anchor binding to SA2, which facilitates other conserved motifs on Sororin to interact with other proteins to regulate sister chromatid cohesion and separation.

Polo-like kinase 1 regulates the stability of the mitotic centromere-associated kinesin in mitosis

Proper bi-orientation of chromosomes is critical for the accurate segregation of chromosomes in mitosis. A key regulator of this process is MCAK, the mitotic centromere-associated kinesin. During mitosis the activity and localization of MCAK are regulated by mitotic key kinases including Plk1 and Aurora B. We show here that S621 in the MCAK's C-terminal domain is the major phosphorylation site for Plk1. This phosphorylation regulates MCAK's stability and facilitates its recognition by the ubiquitin/proteasome dependent APC/C(Cdc20) pathway leading to its D-box dependent degradation in mitosis. While phosphorylation of S621 does not directly affect its microtubule depolymerising activity, loss of Plk1 phosphorylation on S621 indirectly enhances its depolymerization activity in vivo by stabilizing MCAK, leading to an increased level of protein. Interfering with phosphorylation at S621 causes spindle formation defects and chromosome misalignments. Therefore, this study suggests a new mechanism by which Plk1 regulates MCAK: by regulating its degradation and hence controlling its turnover in mitosis.

Characterization of the interaction between the cohesin subunits Rad21 and SA1/2

The cohesin complex is responsible for the fidelity of chromosomal segregation during mitosis. It consists of four core subunits, namely Rad21/Mcd1/Scc1, Smc1, Smc3, and one of the yeast Scc3 orthologs SA1 or SA2. Sister chromatid cohesion is generated during DNA replication and maintained until the onset of anaphase. Among the many proposed models of the cohesin complex, the 'core' cohesin subunits Smc1, Smc3, and Rad21 are almost universally displayed as tripartite ring. However, other than its supportive role in the cohesin ring, little is known about the fourth core subunit SA1/SA2. To gain deeper insight into the function of SA1/SA2 in the cohesin complex, we have mapped the interactive regions of SA2 and Rad21 in vitro and ex vivo. Whereas SA2 interacts with Rad21 through a broad region (301-750 aa), Rad21 binds to SA proteins through two SA-binding motifs on Rad21, namely N-terminal (NT) and middle part (MP) SA-binding motif, located at 60-81 aa of the N-terminus and 383-392 aa of the MP of Rad21, respectively. The MP SA-binding motif is a 10 amino acid, α-helical motif. Deletion of these 10 amino acids or mutation of three conserved amino acids (L(385), F(389), and T(390)) in this α-helical motif significantly hinders Rad21 from physically interacting with SA1/2. Besides the MP SA-binding motif, the NT SA-binding motif is also important for SA1/2 interaction. Although mutations on both SA-binding motifs disrupt Rad21-SA1/2 interaction, they had no apparent effect on the Smc1-Smc3-Rad21 interaction. However, the Rad21-Rad21 dimerization was reduced by the mutations, indicating potential involvement of the two SA-binding motifs in the formation of the two-ring handcuff for chromosomal cohesion. Furthermore, mutant Rad21 proteins failed to significantly rescue precocious chromosome separation caused by depletion of endogenous Rad21 in mitotic cells, further indicating the physiological significance of the two SA-binding motifs of Rad21.

Reconstruction of an integrated genome-scale co-expression network reveals key modules involved in lung adenocarcinoma

Our goal of this study was to reconstruct a “genome-scale co-expression network” and find important modules in lung adenocarcinoma so that we could identify the genes involved in lung adenocarcinoma. We integrated gene mutation, GWAS, CGH, array-CGH and SNP array data in order to identify important genes and loci in genome-scale. Afterwards, on the basis of the identified genes a co-expression network was reconstructed from the co-expression data. The reconstructed network was named “genome-scale co-expression network”. As the next step, 23 key modules were disclosed through clustering. In this study a number of genes have been identified for the first time to be implicated in lung adenocarcinoma by analyzing the modules. The genes EGFR, PIK3CA, TAF15, XIAP, VAPB, Appl1, Rab5a, ARF4, CLPTM1L, SP4, ZNF124, LPP, FOXP1, SOX18, MSX2, NFE2L2, SMARCC1, TRA2B, CBX3, PRPF6, ATP6V1C1, MYBBP1A, MACF1, GRM2, TBXA2R, PRKAR2A, PTK2, PGF and MYO10 are among the genes that belong to modules 1 and 22. All these genes, being implicated in at least one of the phenomena, namely cell survival, proliferation and metastasis, have an over-expression pattern similar to that of EGFR. In few modules, the genes such as CCNA2 (Cyclin A2), CCNB2 (Cyclin B2), CDK1, CDK5, CDC27, CDCA5, CDCA8, ASPM, BUB1, KIF15, KIF2C, NEK2, NUSAP1, PRC1, SMC4, SYCE2, TFDP1, CDC42 and ARHGEF9 are present that play a crucial role in cell cycle progression. In addition to the mentioned genes, there are some other genes (i.e. DLGAP5, BIRC5, PSMD2, Src, TTK, SENP2, PSMD2, DOK2, FUS and etc.) in the modules.

Cohesin in gametogenesis

Sister chromatid cohesion depends on cohesin, a tripartite complex that forms ring structures to hold sister chromatids together in mitosis and meiosis. Meiocytes feature a multiplicity of distinct cohesin proteins and complexes, some meiosis specific, which serve additional functions such as supporting synapsis of two pairs of sister chromatids and determining the loop-axis architecture of prophase I chromosomes. Despite considerable new insights gained in the past few years into the localization and function of some cohesin proteins, and the recent identification of yet another meiosis-specific cohesin subunit, a plethora of open questions remains, which concern not only fundamental germ cell biology but also the consequences of cohesin impairment for human reproductive health.