Centrosome amplification, chromosome instability and cancer development

Sustained inactivation of the Polycomb PRC1 complex induces DNA repair defects and genomic instability in epigenetic tumors

Cancer initiation and progression are typically associated with the accumulation of driver mutations and genomic instability. However, recent studies demonstrated that cancer can also be driven purely by epigenetic alterations, without driver mutations. Specifically, a 24-h transient downregulation of polyhomeotic (ph-KD), a core component of the Polycomb complex PRC1, is sufficient to induce epigenetically initiated cancers (EICs) in Drosophila, which are proficient in DNA repair and characterized by a stable genome. Whether genomic instability eventually occurs when PRC1 downregulation is performed for extended periods of time remains unclear. Here, we show that prolonged depletion of PH, which mimics cancer initiating events, results in broad dysregulation of DNA replication and repair genes, along with the accumulation of DNA breaks, defective repair, and widespread genomic instability in the cancer tissue. A broad misregulation of H2AK118 ubiquitylation and to a lesser extent of H3K27 trimethylation also occurs and might contribute to these phenotypes. Together, this study supports a model where DNA repair and replication defects accumulate during the tumorigenic transformation epigenetically induced by PRC1 loss, resulting in genomic instability and cancer progression.

Mitotic kinases are emerging therapeutic targets against metastatic breast cancer

This review aims to outline mitotic kinase inhibitors' roles as potential therapeutic targets and assess their suitability as a stand-alone clinical therapy or in combination with standard treatments for advanced-stage solid tumors, including triple-negative breast cancer (TNBC). Breast cancer poses a significant global health risk, with TNBC standing out as the most aggressive subtype. Comprehending the role of mitosis is crucial for understanding how TNBC advances from a solid tumor to metastasis. Chemotherapy is the primary treatment used to treat TNBC. Some types of chemotherapeutic agents target cells in mitosis, thus highlighting the need to comprehend the molecular mechanisms governing mitosis in cancer. This understanding is essential for devising targeted therapies to disrupt these mitotic processes, prevent or treat metastasis, and improve patient outcomes. Mitotic kinases like Aurora kinase A, Aurora Kinase B, never in mitosis gene A-related kinase 2, Threonine-Tyrosine kinase, and Polo-kinase 1 significantly impact cell cycle progression by contributing to chromosome separation and centrosome homeostasis. When these kinases go awry, they can trigger chromosome instability, increase cell proliferation, and activate different molecular pathways that culminate in a transition from epithelial to mesenchymal cells. Ongoing clinical trials investigate various mitotic kinase inhibitors as potential biological treatments against advanced solid tumors. While clinical trials against mitotic kinases have shown some promise in the clinic, more investigation is necessary, since they induce severe adverse effects, particularly affecting the hematopoietic system.

The DNA Damage Response (DDR) landscape of endometrial cancer defines discrete disease subtypes and reveals therapeutic opportunities

Genome maintenance is an enabling characteristic that allows neoplastic cells to tolerate the inherent stresses of tumorigenesis and evade therapy-induced genotoxicity. Neoplastic cells also deploy many mis-expressed germ cell proteins termed Cancer Testes Antigens (CTAs) to promote genome maintenance and survival. Here, we present the first comprehensive characterization of the DNA Damage Response (DDR) and CTA transcriptional landscapes of endometrial cancer in relation to conventional histological and molecular subtypes. We show endometrial serous carcinoma (ESC), an aggressive endometrial cancer subtype, is defined by gene expression signatures comprising members of the Replication Fork Protection Complex (RFPC) and Fanconi Anemia (FA) pathway and CTAs with mitotic functions. DDR and CTA-based profiling also defines a subset of highly aggressive endometrioid endometrial carcinomas (EEC) with poor clinical outcomes that share similar profiles to ESC yet have distinct characteristics based on conventional histological and genomic features. Using an unbiased CRISPR-based genetic screen and a candidate gene approach, we confirm that DDR and CTA genes that constitute the ESC and related EEC gene signatures are required for proliferation and therapy-resistance of cultured endometrial cancer cells. Our study validates the use of DDR and CTA-based tumor classifiers and reveals new vulnerabilities of aggressive endometrial cancer where none currently exist.

Knockout of Brca1-interacting factor Ola1 in female mice induces tumors with estrogen suppressible centrosome amplification

Obg-like ATPase 1 (OLA1) is a binding protein of Breast cancer gene 1 (BRCA1), germline pathogenic variants of which cause hereditary breast cancer. Cancer-associated variants of BRCA1 and OLA1 are deficient in the regulation of centrosome number. Although OLA1 might function as a tumor suppressor, the relevance of OLA1 deficiency to carcinogenesis is unclear. Here, we generated Ola1 knockout mice. Aged female Ola1+/- mice developed lymphoproliferative diseases, including malignant lymphoma. The lymphoma tissues had low expression of Ola1 and an increase in the number of cells with centrosome amplification. Interestingly, the proportion of cells with centrosome amplification in normal spleen from Ola1+/- mice was higher in male mice than in female mice. In human cells, estrogen stimulation attenuated centrosome amplification induced by OLA1 knockdown. Previous reports indicate that prominent centrosome amplification causes cell death but does not promote tumorigenesis. Thus, in the current study, the mild centrosome amplification observed under estrogen stimulation in Ola1+/- female mice is likely more tumorigenic than the prominent centrosome amplification observed in Ola1+/- male mice. Our findings provide a possible sex-dependent mechanism of the tumor suppressor function of OLA1.

The contribution of asymmetric cell division to phenotypic heterogeneity in cancer

Cells have evolved intricate mechanisms for dividing their contents in the most symmetric way during mitosis. However, a small proportion of cell divisions results in asymmetric segregation of cellular components, which leads to differences in the characteristics of daughter cells. Although the classical function of asymmetric cell division (ACD) in the regulation of pluripotency is the generation of one differentiated daughter cell and one self-renewing stem cell, recent evidence suggests that ACD plays a role in other physiological processes. In cancer, tumor heterogeneity can result from the asymmetric segregation of genetic material and other cellular components, resulting in cell-to-cell differences in fitness and response to therapy. Defining the contribution of ACD in generating differences in key features relevant to cancer biology is crucial to advancing our understanding of the causes of tumor heterogeneity and developing strategies to mitigate or counteract it. In this Review, we delve into the occurrence of asymmetric mitosis in cancer cells and consider how ACD contributes to the variability of several phenotypes. By synthesizing the current literature, we explore the molecular mechanisms underlying ACD, the implications of phenotypic heterogeneity in cancer, and the complex interplay between these two phenomena.

Centrosome amplification-related signature correlated with immune microenvironment and treatment response predicts prognosis and improves diagnosis of hepatocellular carcinoma by integrating machine learning and single-cell analyses

BACKGROUND

Centrosome amplification is a well-recognized oncogenic driver of tumor initiation and progression across a variety of malignancies and has been linked with tumor aggressiveness, metastasis, and adverse prognosis. Nevertheless, the significance of centrosome amplification in HCC is not well understood.

METHODS

The TCGA dataset was downloaded for centrosome amplification-related signature construction using the LASSO-penalized Cox regression algorithm, while the ICGC dataset was obtained for signature validation. Single-cell RNA sequencing from GSE149614 was analyzed to profile gene expression and the liver tumor niche.

RESULTS

A total of 134 centrosome amplification-related prognostic genes in HCC were detected and 6 key prognostic genes (SSX2IP, SPAG4, SAC3D1, NPM1, CSNK1D, and CEP55) among them were screened out to construct a signature with both high sensitivity and specificity in diagnosis and prognosis of HCC patients. The signature, as an independent factor, was associated with frequent recurrences, high mortality rates, advanced clinicopathologic features, and high vascular invasions. Moreover, the signature was intimately associated with cell cycle-related pathways and TP53 mutation profile, suggesting its underlying role in accelerating cell cycle progression and leading to liver cancer development. Meanwhile, the signature was also closely correlated with immunosuppressive cell infiltration and immune checkpoint expression, making it a vital immunosuppressive factor in the tumor microenvironment. Upon single-cell RNA sequencing, SSX2IP and SAC3D1 were found to be specially expressed in liver cancer stem-like cells, where they promoted cell cycle progression and hypoxia.

CONCLUSIONS

This study provided a direct molecular link of centrosome amplification with clinical characteristics, tumor microenvironment, and clinical drug-response, highlighting the critical role of centrosome amplification in liver cancer development and therapy resistance, thereby providing valuable insights into prognostic prediction and therapeutic response of HCC.

Polyploid Cancer Cell Models in Drosophila

Cells with an abnormal number of chromosomes have been found in more than 90% of solid tumors, and among these, polyploidy accounts for about 40%. Polyploidized cells most often have duplicate centrosomes as well as genomes, and thus their mitosis tends to promote merotelic spindle attachments and chromosomal instability, which produces a variety of aneuploid daughter cells. Polyploid cells have been found highly resistant to various stress and anticancer therapies, such as radiation and mitogenic inhibitors. In other words, common cancer therapies kill proliferative diploid cells, which make up the majority of cancer tissues, while polyploid cells, which lurk in smaller numbers, may survive. The surviving polyploid cells, prompted by acute environmental changes, begin to mitose with chromosomal instability, leading to an explosion of genetic heterogeneity and a concomitant cell competition and adaptive evolution. The result is a recurrence of the cancer during which the tenacious cells that survived treatment express malignant traits. Although the presence of polyploid cells in cancer tissues has been observed for more than 150 years, the function and exact role of these cells in cancer progression has remained elusive. For this reason, there is currently no effective therapeutic treatment directed against polyploid cells. This is due in part to the lack of suitable experimental models, but recently several models have become available to study polyploid cells in vivo. We propose that the experimental models in Drosophila, for which genetic techniques are highly developed, could be very useful in deciphering mechanisms of polyploidy and its role in cancer progression.

Hexavalent Chromium Targets Securin to Drive Numerical Chromosome Instability in Human Lung Cells

Hexavalent chromium [Cr(VI)] is a known human lung carcinogen with widespread exposure in environmental and occupational settings. Despite well-known cancer risks, the molecular mechanisms of Cr(VI)-induced carcinogenesis are not well understood, but a major driver of Cr(VI) carcinogenesis is chromosome instability. Previously, we reported Cr(VI) induced numerical chromosome instability, premature centriole disengagement, centrosome amplification, premature centromere division, and spindle assembly checkpoint bypass. A key regulator of these events is securin, which acts by regulating the cleavage ability of separase. Thus, in this study we investigated securin disruption by Cr(VI) exposure. We exposed human lung cells to a particulate Cr(VI) compound, zinc chromate, for acute (24 h) and prolonged (120 h) time points. We found prolonged Cr(VI) exposure caused marked decrease in securin levels and function. After prolonged exposure at the highest concentration, securin protein levels were decreased to 15.3% of control cells, while securin mRNA quantification was 7.9% relative to control cells. Additionally, loss of securin function led to increased separase activity manifested as enhanced cleavage of separase substrates; separase, kendrin, and SCC1. These data show securin is targeted by prolonged Cr(VI) exposure in human lung cells. Thus, a new mechanistic model for Cr(VI)-induced carcinogenesis emerges with centrosome and centromere disruption as key components of numerical chromosome instability, a key driver in Cr(VI) carcinogenesis.

The DNA Damage Response (DDR) landscape of endometrial cancer defines discrete disease subtypes and reveals therapeutic opportunities

Genome maintenance is an enabling characteristic that allows neoplastic cells to tolerate the inherent stresses of tumorigenesis and evade therapy-induced genotoxicity. Neoplastic cells also deploy mis-expressed germ cell proteins termed Cancer Testes Antigens (CTAs) to promote genome maintenance and survival. Here, we present the first comprehensive characterization of the DNA Damage Response (DDR) and CTA transcriptional landscapes of endometrial cancer in relation to conventional histological and molecular subtypes. We show endometrial serous carcinoma (ESC), an aggressive endometrial cancer subtype, is defined by gene expression signatures comprising members of the Replication Fork Protection Complex (RFPC) and Fanconi Anemia (FA) pathway and CTAs with mitotic functions. DDR and CTA- based profiling also defines a subset of highly aggressive endometrioid endometrial carcinomas (EEC) with poor clinical outcomes that share similar profiles to ESC yet have distinct characteristics based on conventional histological and genomic features. Using an unbiased CRISPR-based genetic screen and a candidate gene approach, we confirm that DDR and CTA genes that constitute the ESC and related EEC gene signatures are required for proliferation and therapy-resistance of cultured endometrial cancer cells. Our study validates the use of DDR and CTA-based tumor classifiers and reveals new vulnerabilities of aggressive endometrial cancer where none currently exist.

Permission to pass: on the role of p53 as a gatekeeper for aneuploidy

Aneuploidy-the karyotype state in which the number of chromosomes deviates from a multiple of the haploid chromosome set-is common in cancer, where it is thought to facilitate tumor initiation and progression. However, it is poorly tolerated in healthy cells: during development and tissue homeostasis, aneuploid cells are efficiently cleared from the population. It is still largely unknown how cancer cells become, and adapt to being, aneuploid. P53, the gatekeeper of the genome, has been proposed to guard against aneuploidy. Aneuploidy in cancer genomes strongly correlates with mutations in TP53, and p53 is thought to prevent the propagation of aneuploid cells. Whether p53 also participates in preventing the mistakes in cell division that lead to aneuploidy is still under debate. In this review, we summarize the current understanding of the role of p53 in protecting cells from aneuploidy, and we explore the consequences of functional p53 loss for the propagation of aneuploidy in cancer.

Functional Materials for Subcellular Targeting Strategies in Cancer Therapy: Progress and Prospects

Neoadjuvant and adjuvant therapies have made significant progress in cancer treatment. However, tumor adjuvant therapy still faces challenges due to the intrinsic heterogeneity of cancer, genomic instability, and the formation of an immunosuppressive tumor microenvironment. Functional materials possess unique biological properties such as long circulation times, tumor-specific targeting, and immunomodulation. The combination of functional materials with natural substances and nanotechnology has led to the development of smart biomaterials with multiple functions, high biocompatibilities, and negligible immunogenicities, which can be used for precise cancer treatment. Recently, subcellular structure-targeting functional materials have received particular attention in various biomedical applications including the diagnosis, sensing, and imaging of tumors and drug delivery. Subcellular organelle-targeting materials can precisely accumulate therapeutic agents in organelles, considerably reduce the threshold dosages of therapeutic agents, and minimize drug-related side effects. This review provides a systematic and comprehensive overview of the research progress in subcellular organelle-targeted cancer therapy based on functional nanomaterials. Moreover, it explains the challenges and prospects of subcellular organelle-targeting functional materials in precision oncology. The review will serve as an excellent cutting-edge guide for researchers in the field of subcellular organelle-targeted cancer therapy.

Identification of a novel spirocyclic Nek2 inhibitor using high throughput virtual screening

NIMA Related Kinase 2 (Nek2) kinase is an attractive target for the development of therapeutic agents for several types of highly invasive cancers. Despite this, no small molecule inhibitor has advanced to the late clinical stages thus far. In this work, we have identified a novel spirocyclic inhibitor (V8) of Nek2 kinase, utilizing a high-throughput virtual screening (HTVS) approach. Using recombinant Nek2 enzyme assays, we show that V8 can inhibit Nek2 kinase activity (IC50 = 2.4 ± 0.2 µM) by binding to the enzyme's ATP pocket. The inhibition is selective, reversible and is not time dependent. To understand the key chemotype features responsible for Nek2 inhibition, a detailed structure-activity relationships (SAR) was performed. Using molecular models of the energy-minimized structures of Nek2-inhibitory complexes, we identify key hydrogen-bonding interactions, including two from the hinge-binding region, likely responsible for the observed affinity. Finally, using cell-based studies, we show that V8 attenuates (a) pAkt/PI3 Kinase signaling in a dose-dependent manner, and (b) proliferative and migratory phenotypes of highly aggressive human MDA-MB-231 breast and A549 lung cancer cell lines. Thus, V8 is an important novel lead compound for the development of highly potent and selective Nek2 inhibitory agents.

lncRNA XIST/miR‑129‑2‑3p axis targets CCP110 to regulate the proliferation, invasion and migration of endometrial cancer cells

Centromere coiled-coil protein 110 (CCP110) plays a role in the development of several types of cancer; however, its regulatory mechanism and role in endometrial cancer is unclear. The present study revealed that CCP110 is regulated by a signaling pathway involving microRNA (miR/miRNA)-129-2-3p and the long non-coding RNA (lncRNA) X-inactive-specific transcript (XIST), and plays a role in controlling the proliferation, migration and invasion of endometrial cancer cells. CCP110 was upregulated in human endometrial cancer tissues, as revealed by immunohistochemistry, and high expression of the protein was related to reduced overall survival of the patients. Genetic knockdown of CCP110 by small interfering RNA promoted apoptosis and suppressed the proliferation, migration, invasion and colony formation of endometrial cancer cells significantly in the endometrial cancer Ishikawa and HEC-1B cell lines, as assessed by flow cytometry, and Cell Counting Kit-8, Transwell and colony formation assays. A bioinformatics analysis and luciferase reporter assay revealed that CCP110 is a target of miR-129-2-3p. Overexpression of miR-129-2-3p mimic fragments inhibited the proliferation, migration and invasion of endometrial cancer cells significantly, while co-overexpression of CCP110 counteracted these inhibitory effects. The expression level of the lncRNA XIST was upregulated significantly in endometrial cancer tissues, as assessed by reverse transcription-quantitative PCR assay, while that of miR-129-2-3p was downregulated significantly. A bioinformatics analysis and luciferase reporter assay showed that XIST could inhibit miR-129-2-3p via a miRNA sponge effect. Furthermore, co-overexpression of XIST antagonized the inhibitory effect of the miR-129-2-3p mimic on the luciferase reporter gene signal and protein expression of CCP110. Co-overexpression of XIST also abolished the inhibitory effect of the miR-129-2-3p mimic on the proliferation, migration and invasion of endometrial cancer cells. Overall, these data identified a novel regulatory mechanism of CCP110 involving XIST and miR-129-2-3p, which affected the development of endometrial carcinoma. CCP110, XIST and miR-129-2-3p could represent novel targets for the clinical treatment of endometrial cancer.

Transcriptome Profiling and Network Analysis Provide Insights Into the Pathogenesis of Vulvar Lichen Sclerosus

Vulvar lichen sclerosus (VLS) is a chronic inflammatory dermatosis that affects female anogenital skin. Although VLS is considered a T cell-mediated autoimmune disease, the diagnosis criteria, molecular mechanism, and universally accepted therapies for this disease remain largely unresolved. To explore disease pathogenesis and potential biomarkers, we performed an RNA-Seq-based transcriptome analysis to profile the gene expression of VLS lesions. Differentially expressed gene (DEG) analysis revealed profound changes in expressions of coding genes, microRNAs, and long non-coding RNAs. Pathway and network analysis suggested that T cell activation-associated genes, including CD3G, CD3D, CD8B, LAT, LCK, ZAP70, CCR5, CXCR3, CXCL9, CXCL10, and CXCL11, were highly expressed in VLS, while NR4A family genes (NR4A1, NR4A2, NR4A3), whose coding products inhibit T cell activity, were significantly downregulated, suggesting heightened T cell response in VLS. Neutrophil chemoattractant genes CXCL1, CXCL2, CXCL3, CXCL8, and their cognate receptor CXCR2 were downregulated, suggesting dampened neutrophil activity. We also found the downregulation of genes involved in cell cycle progression, including cyclins (CCNB1, CCNB2, CCNL1, CCNE1, and CCNK) and centrosome factors (CENPA, CENPE, CENPF, and CENPN), while microRNA-203a and let-7, microRNAs known to inhibit cell growth, were found to be upregulated. These data collectively indicate that cell proliferation in VLS is compromised. In sum, these findings comprehensively deciphered key regulatory genes and networks in VLS, which could further our understanding of disease mechanisms and point toward therapeutic strategies.

Terminally differentiated osteoclasts organize centrosomes into large clusters for microtubule nucleation and bone resorption

Osteoclasts are highly specialized, multinucleated cells responsible for the selective resorption of the dense, calcified bone matrix. Microtubules (MTs) contribute to the polarization and trafficking events involved in bone resorption by osteoclasts, however the origin of these elaborate arrays is less clear. Osteoclasts arise through cell fusion of precursor cells. Previous studies have suggested that centrosome MT nucleation is lost during this process, with the nuclear membrane and its surrounding Golgi serving as the major microtubule organizing centres (MTOCs) in these cells. Here we reveal that precursor cell centrosomes are maintained and functional in the multinucleated osteoclast and interestingly form large MTOC clusters, with the clusters organizing significantly more MTs, compared to individual centrosomes. MTOC cluster formation requires dynamic microtubules and minus-end directed MT motor activity. Inhibition of these centrosome clustering elements had a marked impact on both F-actin ring formation and bone resorption. Together these findings show that multinucleated osteoclasts employ unique centrosomal clusters to organize the extensive microtubules during bone attachment and resorption. [Media: see text].

Estrogens—Origin of Centrosome Defects in Human Cancer?

Estrogens are associated with a variety of diseases and play important roles in tumor development and progression. Centrosome defects are hallmarks of human cancers and contribute to ongoing chromosome missegragation and aneuploidy that manifest in genomic instability and tumor progression. Although several mechanisms underlie the etiology of centrosome aberrations in human cancer, upstream regulators are hardly known. Accumulating experimental and clinical evidence points to an important role of estrogens in deregulating centrosome homeostasis and promoting karyotype instability. Here, we will summarize existing literature of how natural and synthetic estrogens might contribute to structural and numerical centrosome defects, genomic instability and human carcinogenesis.

Keep Calm and Carry on with Extra Centrosomes

Simple Summary

Precise chromosome segregation during mitosis is a vital event orchestrated by formation of bipolar spindle poles. Supernumerary centrosomes, caused by centrosome amplification, deteriorates mitotic processes, resulting in segregation defects leading to chromosomal instability (CIN). Centrosome amplification is frequently observed in various types of cancer and considered as a significant contributor to destabilization of chromosomes. This review provides a comprehensive overview of causes and consequences of centrosome amplification thoroughly describing molecular mechanisms.

Abstract

Aberrations in the centrosome number and structure can readily be detected at all stages of tumor progression and are considered hallmarks of cancer. Centrosome anomalies are closely linked to chromosome instability and, therefore, are proposed to be one of the driving events of tumor formation and progression. This concept, first posited by Boveri over 100 years ago, has been an area of interest to cancer researchers. We have now begun to understand the processes by which these numerical and structural anomalies may lead to cancer, and vice-versa: how key events that occur during carcinogenesis could lead to amplification of centrosomes. Despite the proliferative advantages that having extra centrosomes may confer, their presence can also lead to loss of essential genetic material as a result of segregational errors and cancer cells must deal with these deadly consequences. Here, we review recent advances in the current literature describing the mechanisms by which cancer cells amplify their centrosomes and the methods they employ to tolerate the presence of these anomalies, focusing particularly on centrosomal clustering.

Clinical Applications of Aneuploidies in Evolution of NSCLC Patients: Current Status and Application Prospect

As one of the first characteristics of cancer cells, chromosomal aberrations during cell division have been well documented. Aneuploidy is a feature of most cancer cells accompanied by an elevated rate of mis-segregation of chromosomes, called chromosome instability (CIN). Aneuploidy causes ongoing karyotypic changes that contribute to tumor heterogeneity, drug resistance, and treatment failure, which are considered predictors of poor prognosis. Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, and its genome map shows extensive aneuploid changes. Elucidating the role of aneuploidy in the pathogenesis of LC will reveal information about the key factors of tumor occurrence and development, help to predict the prognosis of cancer, clarify tumor evolution, metastasis, and drug response, and may promote the development of precision oncology. In this review, we describe many possible causes of aneuploidy and provide evidence of the role of aneuploidy in the evolution of LC, providing a basis for future biological and clinical research.

SASS6 promotes proliferation of esophageal squamous carcinoma cells by inhibiting the p53 signaling pathway

SASS6 encodes for the Homo sapiens SAS-6 centriolar assembly protein and is important for proper centrosome formation. Although centrosomes are amplified in a wide variety of tumor types, abnormally high SASS6 expression had previously only been identified in colon cancer. Moreover, the role of SASS6 in esophageal squamous cell carcinoma (ESCC) pathogenesis has not yet been elucidated. The aim of this study was to investigate the role and mechanisms of SASS6 in ESCC. In this study, we found that the mRNA and protein levels of SASS6 were increased in human ESCC samples. In addition, SASS6 protein expression was associated with the esophageal cancer stage and negatively affected survival of patients with ESCC. Furthermore, silencing of SASS6 inhibited cell growth and promoted apoptosis of ESCC cells in vitro and inhibited xenograft tumor formation in vivo. A genetic cluster and pathway analysis showed that SASS6 regulated the p53 signaling pathway. Western blot demonstrated that CCND2, GADD45A and EIF4EBP1 protein expression decreased and that TP53 protein expression increased after the knockdown of SASS6 in ESCC cells. Therefore, SASS6 promoted the proliferation of esophageal cancer by inhibiting the p53 signaling pathway. SASS6 has potential as a novel tumor marker and a therapeutic target for ESCC.

Novel biomarker for hepatocellular carcinoma: high tumoral PLK-4 expression is associated with better prognosis in patients without microvascular invasion

BACKGROUND

Hepatocellular carcinoma (HCC) recurrence after liver resection (LR) adversely affects prognosis but is difficult to predict. Aberrant expression of Polo-Like Kinase 4 (PLK-4) is implicated in several adult malignancies. We sought to evaluate the prognostic value of PLK-4 expression in HCC after curative-intent LR.

METHODS

Patients undergoing LR for HCC between July-2015 and November-2017 at our centre were retrospectively identified. PLK-4 expression was measured in tumour and adjacent non-tumour liver tissue using quantitative RT-PCR. Disease-free survival (DFS) was evaluated by Kaplan-Meier and Cox proportional hazard models.

RESULTS

A total of 145 patients were identified. Patients were divided according to PLK-4 expression (high: n = 58, low: n = 87) by generating a receiver operating characteristic curve for recurrence with an area under the curve of 0.72 (95% CI: 0.6-0.8). Recurrence and death rates were similar between groups. In patients without mVI, low PLK-4 expression was associated with worse actuarial DFS (low 1-, 3-, 5-year 83%, 60%, 47% vs. high 91%, 81%, 81%; p = 0.02). In patients without mVI, high PLK-4 expression was an independent predictor of survival (HR 0.3, 95% CI: 0.1-1.0; p = 0.04).

CONCLUSION

PLK-4 represents a biomarker for good prognosis in patients with HCC who do not have mVI. This could aid clinical decision making for adjuvant clinical trials.

Aberrant Expression of microRNA Clusters in Head and Neck Cancer Development and Progression: Current and Future Translational Impacts

MicroRNAs are small non-coding RNAs known to negative regulate endogenous genes. Some microRNAs have high sequence conservation and localize as clusters in the genome. Their coordination is regulated by simple genetic and epigenetic events mechanism. In cells, single microRNAs can regulate multiple genes and microRNA clusters contain multiple microRNAs. MicroRNAs can be differentially expressed and act as oncogenic or tumor suppressor microRNAs, which are based on the roles of microRNA-regulated genes. It is vital to understand their effects, regulation, and various biological functions under both normal and disease conditions. Head and neck squamous cell carcinomas are some of the leading causes of cancer-related deaths worldwide and are regulated by many factors, including the dysregulation of microRNAs and their clusters. In disease stages, microRNA clusters can potentially control every field of oncogenic function, including growth, proliferation, apoptosis, migration, and intercellular commutation. Furthermore, microRNA clusters are regulated by genetic mutations or translocations, transcription factors, and epigenetic modifications. Additionally, microRNA clusters harbor the potential to act therapeutically against cancer in the future. Here, we review recent advances in microRNA cluster research, especially relative to head and neck cancers, and discuss their regulation and biological functions under pathological conditions as well as translational applications.

Histone Modifying Enzymes in Gynaecological Cancers

Simple Summary

Epigenetics is a process that allows genetic control, without the involvement of sequence changes to DNA or genes. In cancer, epigenetics is a key event in tumour development that can alter the expression of cancer driver genes and result in genomic instability. Due to the critical role of epigenetics in malignant transformation, therapies that target these processes have been developed to treat cancer. Here, we provide a summary of the epigenetic changes that have been described in a variety of gynaecological cancers. We then highlight how these changes are being targeted in preclinical models and clinical trials for gynaecological cancers.

Abstract

Genetic and epigenetic factors contribute to the development of cancer. Epigenetic dysregulation is common in gynaecological cancers and includes altered methylation at CpG islands in gene promoter regions, global demethylation that leads to genome instability and histone modifications. Histones are a major determinant of chromosomal conformation and stability, and unlike DNA methylation, which is generally associated with gene silencing, are amenable to post-translational modifications that induce facultative chromatin regions, or condensed transcriptionally silent regions that decondense resulting in global alteration of gene expression. In comparison, other components, crucial to the manipulation of chromatin dynamics, such as histone modifying enzymes, are not as well-studied. Inhibitors targeting DNA modifying enzymes, particularly histone modifying enzymes represent a potential cancer treatment. Due to the ability of epigenetic therapies to target multiple pathways simultaneously, tumours with complex mutational landscapes affected by multiple driver mutations may be most amenable to this type of inhibitor. Interrogation of the actionable landscape of different gynaecological cancer types has revealed that some patients have biomarkers which indicate potential sensitivity to epigenetic inhibitors. In this review we describe the role of epigenetics in gynaecological cancers and highlight how it may exploited for treatment.

A look into the link between centrosome amplification and breast cancer

Centrosome amplification (CA) is a common feature of human tumors, but it is not clear whether this is a cause or a consequence of cancer. The centrosome amplification observed in tumor cells may be explained by a series of events, such as failure of cell division, dysregulation of centrosome cycle checkpoints, and de novo centriole biogenesis disorder. The formation and progression of breast cancer are characterized by genomic abnormality. The centrosomes in breast cancer cells show characteristic structural aberrations, caused by centrosome amplification, which include: an increase in the number and volume of centrosomes, excessive increase of pericentriolar material (PCM), inappropriate phosphorylation of centrosomal molecular, and centrosome clustering formation induced by the dysregulation of important genes. The mechanism of intracellular centrosome amplification, the impact of which on breast cancer and the latest breast cancer target treatment options for centrosome amplification are exhaustively elaborated in this review.

The Ins and Outs of HOPS/TMUB1 in biology and pathology

Liver regeneration represents an outstanding tool to study not only proliferation, but also other important processes such as inflammation, regenerative response or stem cell biology. Several novel genes have been identified as being involved in the proliferation of residual hepatocytes. One of them, HOPS/TMUB1, is proving to be a significant player in the control of proliferation, both contributing to genomic stability and as a partner of essential molecules. HOPS is an ubiquitin-like protein, shuttling from nucleus to cytoplasm, and it is engaged in a number of biological and physiopathological functions. HOPS overexpression in tumour cell lines strongly reduces proliferation, arresting cell cycle in G₀ /G₁ . HOPS is involved in centrosome assembly and maintenance, and its knockdown causes genomic instability. Moreover, a direct interaction of HOPS with nucleophosmin (NPM) and p19^Arf has been established, resulting in proper control of p19^Arf stability and localization. These data indicate that HOPS acts as a functional bridge in the interaction between NPM and p19^Arf , providing new mechanistic insight into how NPM and p19^Arf will oppose cell proliferation. HOPS exerts a control in p53 stability, directing p53 mitochondrial apoptosis and cytoplasmic localization. HOPS plays a direct role as novel post-translational modifier of p53, much like SUMO or NEDD. HOPS is overexpressed in a high number of human tumours in patients affected by large intestinal, CNS, liver and oesophageal tumours. This review highlights HOPS involvement in distinct cellular functions, establishing its role as a key player in cell biology and pathology in a broader context.

Centrosomal protein TAX1BP2 inhibits centrosome-microtubules aberrations induced by hepatitis B virus X oncoprotein

Liver cancer (hepatocellular carcinoma, HCC) is one of the most prevalent cancers worldwide. Several etiological factors of HCC, including hepatitis B or hepatitis C virus infection, liver cirrhosis and aflatoxin B1 intake has been identified. HBx, which is an oncogenic protein encoded by the hepatitis B virus, is strongly associated with hepatocarcinogenesis. Using stable HBx-expressing cell, we showed that HBx induced chromosome gain, with amplification of centrosomes numbers and deregulation of centrosome ultrastructure. To dissect the mechanism for chromosome instability, our result revealed that HBx contributed to a hyperactive centrosome-microtubule dynamics by accelerating microtubule nucleation and polymerization. Further investigations suggested that HBx interacted with a centrosome linker protein TAX1BP2, which has previously been shown to function as an intrinsic block of centrosome amplification and a tumour suppressor in HCC. Restoring TAX1BP2 was able to block HBx-mediated centrosome amplification and abolish the HBx-mediated centrosome aberration, thereby suppressing chromosome instability. Thus, we demonstrate here a mechanism by which HBx deregulates centrosome-microtubule dynamics through interacting with TAX1BP2, which underlines the possibility of restoration of TAX1BP2 to rescue cells from chromosome instability.

Molecular Biology of Osteosarcoma

Osteosarcoma (OS) is the most frequent primary bone cancer in children and adolescents and the third most frequent in adults. Many inherited germline mutations are responsible for syndromes that predispose to osteosarcomas including Li Fraumeni syndrome, retinoblastoma syndrome, Werner syndrome, Bloom syndrome or Diamond-Blackfan anemia. TP53 is the most frequently altered gene in osteosarcoma. Among other genes mutated in more than 10% of OS cases, c-Myc plays a role in OS development and promotes cell invasion by activating MEK-ERK pathways. Several genomic studies showed frequent alterations in the RB gene in pediatric OS patients. Osteosarcoma driver mutations have been reported in NOTCH1, FOS, NF2, WIF1, BRCA2, APC, PTCH1 and PRKAR1A genes. Some miRNAs such as miR-21, -34a, -143, -148a, -195a, -199a-3p and -382 regulate the pathogenic activity of MAPK and PI3K/Akt-signaling pathways in osteosarcoma. CD133+ osteosarcoma cells have been shown to exhibit stem-like gene expression and can be tumor-initiating cells and play a role in metastasis and development of drug resistance. Although currently osteosarcoma treatment is based on adriamycin chemoregimens and surgery, there are several potential targeted therapies in development. First of all, activity and safety of cabozantinib in osteosarcoma were studied, as well as sorafenib and pazopanib. Finally, novel bifunctional molecules, of potential imaging and osteosarcoma targeting applications may be used in the future.

A Quantitative Centrosomal Amplification Score Predicts Local Recurrence of Ductal Carcinoma In Situ

PURPOSE

The purpose of this study is to predict risk of local recurrence (LR) in ductal carcinoma in situ (DCIS) with a new visualization and quantification approach using centrosome amplification (CA), a cancer cell-specific trait widely associated with aggressiveness.

EXPERIMENTAL DESIGN

This first-of-its-kind methodology evaluates the severity and frequency of numerical and structural CA present within DCIS and assigns a quantitative centrosomal amplification score (CAS) to each sample. Analyses were performed in a discovery cohort (DC, n = 133) and a validation cohort (VC, n = 119).

RESULTS

DCIS cases with LR exhibited significantly higher CAS than recurrence-free cases. Higher CAS was associated with a greater risk of developing LR (HR, 6.3 and 4.8 for DC and VC, respectively; P < 0.001). CAS remained an independent predictor of relapse-free survival (HR, 7.4 and 4.5 for DC and VC, respectively; P < 0.001) even after accounting for potentially confounding factors [grade, age, comedo necrosis, and radiotherapy (RT)]. Patient stratification using CAS (P < 0.0001) was superior to that by Van Nuys Prognostic Index (VNPI; HR for CAS = 6.2 vs. HR for VNPI = 1.1). Among patients treated with breast-conserving surgery alone, CAS identified patients likely to benefit from adjuvant RT.

CONCLUSIONS

CAS predicted 10-year LR risk for patients who underwent surgical management alone and identified patients who may be at low risk of recurrence, and for whom adjuvant RT may not be required. CAS demonstrated the highest concordance among the known prognostic models such as VNPI and clinicopathologic variables such as grade, age, and comedo necrosis.

Genomic instability and cancer: lessons from Drosophila

Cancer is a genetic disease that involves the gradual accumulation of mutations. Human tumours are genetically unstable. However, the current knowledge about the origins and implications of genomic instability in this disease is limited. Understanding the biology of cancer requires the use of animal models. Here, we review relevant studies addressing the implications of genomic instability in cancer by using the fruit fly, Drosophila melanogaster, as a model system. We discuss how this invertebrate has helped us to expand the current knowledge about the mechanisms involved in genomic instability and how this hallmark of cancer influences disease progression.

Checking NEKs: Overcoming a Bottleneck in Human Diseases

In previous years, several kinases, such as phosphoinositide 3-kinase (PI3K), mammalian target of rapamycin (mTOR), and extracellular-signal-regulated kinase (ERK), have been linked to important human diseases, although some kinase families remain neglected in terms of research, hiding their relevance to therapeutic approaches. Here, a review regarding the NEK family is presented, shedding light on important information related to NEKs and human diseases. NEKs are a large group of homologous kinases with related functions and structures that participate in several cellular processes such as the cell cycle, cell division, cilia formation, and the DNA damage response. The review of the literature points to the pivotal participation of NEKs in important human diseases, like different types of cancer, diabetes, ciliopathies and central nervous system related and inflammatory-related diseases. The different known regulatory molecular mechanisms specific to each NEK are also presented, relating to their involvement in different diseases. In addition, important information about NEKs remains to be elucidated and is highlighted in this review, showing the need for other studies and research regarding this kinase family. Therefore, the NEK family represents an important group of kinases with potential applications in the therapy of human diseases.

Malignancy Index Using Intraoperative Flow Cytometry is a Valuable Prognostic Factor for Glioblastoma Treated With Radiotherapy and Concomitant Temozolomide

BACKGROUND

Intraoperative prediction of radiochemosensitivity is desirable for improving the clinical management of glioblastoma (GBM) patients. We have previously developed an original technique for intraoperative flow cytometry (iFC) and defined a malignancy index (MI).

OBJECTIVE

To determine whether MI correlates with prognosis in GBM patients who underwent the standard treatment protocol of radiotherapy and temozolomide administration.

METHODS

The current study included 102 patients with GBM that had been newly diagnosed from 2010 to 2015 who underwent our iFC analysis and received the standard treatment protocol. We evaluated MI values in each patient, then statistically analyzed the relationship between MI and prognosis using survival analysis that include other clinicopathological factors (age, sex, Karnofsky performance status [KPS], extent of resection, second-line bevacizumab, O6-methylguanine-DNA methyltransferase [MGMT] status, MIB-1 labeling index, and mutation of the isocitrate dehydrogenase 1 gene [IDH1]).

RESULTS

Log-rank test revealed that age, KPS, extent of resection, MGMT status, IDH1 mutation, and high MI (≥26.3%) significantly correlated with overall survival. Multivariate analysis with Cox regression modeling identified MI as the most significant prognostic factor (hazard ratio = 2.246; 95% confidence interval = 1.347-3.800; P = .0019). MI showed strong correlation with IDH1 mutation status in chi-square test (P = .0023). In addition, log-rank test revealed that MI affects overall survival more strongly in patients with IDH1 wildtype than those with IDH1 mutant.

CONCLUSION

MI from an iFC study may help predict the prognosis in patients with GBM who receive the standard treatment. Survival can be related to sensitivity to radio-chemotherapy.

Nesprin-1 impact on tumorigenic cell phenotypes

The largest protein of the nuclear envelope (NE) is Nesprin-1 which forms a network along the NE interacting with actin, Emerin, Lamin, and SUN proteins. Mutations in the SYNE1 gene and reduction in Nesprin-1 protein levels have been reported to correlate with several age related diseases and cancer. In the present study, we tested whether Nesprin-1 overexpression can reverse the malignant phenotype of Huh7 cells, a human liver cancer cell line, which carries a mutation in the SYNE1 gene resulting in reduced Nesprin-1 protein levels, has altered nuclear shape, altered amounts and localization of NE components, centrosome localization and genome stability. Ectopic expression of a mini-Nesprin-1 led to an improvement of the nuclear shape, corrected the mislocalization of NE proteins, the centrosome positioning, and the alterations in the DNA damage response network. Additionally, Nesprin-1 had a profound effect on cellular senescence. These findings suggest that Nesprin-1 may be effective in tumorigenic cell phenotype correction of human liver cancer.

Histone Deacetylase SIRT1 Targets Plk2 to Regulate Centriole Duplication

The protein deacetylase SIRT1 (Sirtuin 1) regulates many cellular processes, including cell-cycle progression, DNA damage response, and metabolism. Although the centrosome is a key regulator of cell-cycle progression and genome stability, little is known concerning SIRT1 controlled centrosome-associated events. Here we report that the centrosome protein Plk2 is acetylated and undergoes deacetylation by SIRT1. Acetylation protects Plk2 from ubiquitination, and SIRT1-mediated deacetylation promotes ubiquitin-dependent degradation of Plk2. SIRT1 controls centriole duplication by temporally modulating centrosomal Plk2 levels. AURKA phosphorylates SIRT1 and promotes the SIRT1-Plk2 interaction in mitosis. In early-mid G₁, phosphorylated SIRT1 deacetylates and promotes Plk2 degradation. In late G₁, SIRT1 is hypophosphorylated and its affinity to Plk2 is decreased, resulting in a rapid accumulation of centrosomal Plk2, which contributes to the timely initiation of centriole duplication. Collectively, our findings uncover a critical role of SIRT1 in centriole duplication and provide a mechanistic insight into SIRT1-mediated centrosome-associated functions.

DNA aneuploidy and centrosome amplification in canine tumor cell lines

DNA aneuploidy, the altered DNA content of a cell, is a common feature of canine tumors. However, it is unclear whether aneuploid DNA in canine tumor cells show centrosome amplification (CA), which contributes to numerical and structural chromosome aberrations that result in DNA aneuploidy. Here, we evaluated whether DNA aneuploidy and CA occur concurrently in canine tumor cell lines. Centrosome numbers were evaluated in 18 canine tumor cell lines by immunocytochemistry with anti-γ-tubulin antibody, and DNA content was evaluated by flow cytometry using propidium iodide. A total of 15 cell lines showed DNA aneuploidy, and CA was observed in 5 of these 15 cell lines. Together, our results suggest that DNA aneuploidy in canine tumor cells might be explained at least in part by CA. In addition, cell lines with CA may be useful tools to examine the detailed relationship between CA and DNA aneuploidy and the molecular mechanism of CA in canine tumor.

A cis-eQTL genetic variant in PLK4 confers high risk of hepatocellular carcinoma

Purpose

The overexpression and knockdown of PLK4 were both reported to generate aneuploidy. Thus, we aimed to investigate whether genetic variants in PLK4 contribute to the development of hepatocellular carcinoma (HCC).

Methods

We evaluated associations of common variants in PLK4 and its promoter for the risk of HCC in our association study (1300 cases and 1344 controls). The genotype‐tissue expression (GTEx) and The cancer genome atlas (TCGA) databases were used to quantify the expression of PLK4. Cell proliferation and migration affected by PLK4 in HCC were assessed in vitro. Drug susceptibility testing (DST) model was used to assess the sensibility of PLK4‐activated HCC to CFI‐400945, a small molecule inhibitor of PLK4.

Results

Herein, we found a significant association between rs3811741, located in the PLK4 intron, and liver cancer risk (OR = 1.26, P = 9.81 × 10⁻⁵). Although PLK4 expressed at lower levels in somatic tissues compared to the testis, the risk allele A of rs3811741 was associated with increased PLK4 expression in liver cancer tissues. Additionally, PLK4 high expression was remarkably associated with shortened survival of HCC (HR = 1.97, P = .001). Furthermore, overexpression of PLK4 promoted, while knockdown of PLK4 suppressed cancer cell proliferation, migration, and invasion. DST model demonstrated that CFI‐400945 can effectively suppress rampant proliferation of HCC with highly expressed PLK4.

Conclusion

Taken together, our study demonstrated that PLK4 is a susceptibility gene and plays an oncogenic role in HCC. Furthermore, we identified that PLK4 sensitives HCC to CFI‐400945, which may be an ideal therapy target for HCC.

Heat Stress-Induced Multiple Multipolar Divisions of Human Cancer Cells

Multipolar divisions of heated cells has long been thought to stem from centrosome aberrations of cells directly caused by heat stress. In this paper, through long-term live-cell imaging, we provide direct cellular evidences to demonstrate that heat stress can promote multiple multipolar divisions of MGC-803 and MCF-7 cells. Our results show that, besides facilitating centrosome aberration, polyploidy induced by heat stress is another mechanism that causes multipolar cell divisions, in which polyploid cancer cells engendered by mitotic slippage, cytokinesis failure, and cell fusion. Furthermore, we also find that the fates of theses polyploid cells depend on their origins, in the sense that the polyploid cells generated by mitotic slippage experience bipolar divisions with a higher rate than multipolar divisions, while those polyploid cells induced by both cytokinesis failure and cell fusion have a higher frequency of multipolar divisions compared with bipolar divisions. This work indicates that heat stress-induced multiple multipolar divisions of cancer cells usually produce aneuploid daughter cells, and might lead to genetically unstable cancer cells and facilitate tumor heterogeneity.

Evaluation of Protein Kinase Inhibitors with PLK4 Cross-Over Potential in a Pre-Clinical Model of Cancer

Polo-like kinase 4 (PLK4) is a cell cycle-regulated protein kinase (PK) recruited at the centrosome in dividing cells. Its overexpression triggers centrosome amplification, which is associated with genetic instability and carcinogenesis. In previous work, we established that PLK4 is overexpressed in pediatric embryonal brain tumors (EBT). We also demonstrated that PLK4 inhibition exerted a cytostatic effect in EBT cells. Here, we examined an array of PK inhibitors (CFI-400945, CFI-400437, centrinone, centrinone-B, R-1530, axitinib, KW-2449, and alisertib) for their potential crossover to PLK4 by comparative structural docking and activity inhibition in multiple established embryonal tumor cell lines (MON, BT-12, BT-16, DAOY, D283). Our analyses demonstrated that: (1) CFI-400437 had the greatest impact overall, but similar to CFI-400945, it is not optimal for brain exposure. Also, their phenotypic anti-cancer impact may, in part, be a consequence of the inhibition of Aurora kinases (AURKs). (2) Centrinone and centrinone B are the most selective PLK4 inhibitors but they are the least likely to penetrate the brain. (3) KW-2449, R-1530 and axitinib are the ones predicted to have moderate-to-good brain penetration. In conclusion, a new selective PLK4 inhibitor with favorable physiochemical properties for optimal brain exposure can be beneficial for the treatment of EBT.

Acto-myosin force organization modulates centriole separation and PLK4 recruitment to ensure centriole fidelity

The presence of aberrant number of centrioles is a recognized cause of aneuploidy and hallmark of cancer. Hence, centriole duplication needs to be tightly regulated. It has been proposed that centriole separation limits centrosome duplication. The mechanism driving centriole separation is poorly understood and little is known on how this is linked to centriole duplication. Here, we propose that actin-generated forces regulate centriole separation. By imposing geometric constraints via micropatterns, we were able to prove that precise acto-myosin force arrangements control direction, distance and time of centriole separation. Accordingly, inhibition of acto-myosin contractility impairs centriole separation. Alongside, we observed that organization of acto-myosin force modulates specifically the length of S-G2 phases of the cell cycle, PLK4 recruitment at the centrosome and centriole fidelity. These discoveries led us to suggest that acto-myosin forces might act in fundamental mechanisms of aneuploidy prevention.

Combined study on clastogenic, aneugenic and apoptotic properties of doxorubicin in human cells in vitro

BACKGROUND

Doxorubicin is a widely used anticancer drug due to its broad spectrum of antitumor activity. Various mechanisms have been proposed for its cytostatic activity, including DNA intercalation, topoisomerase II inhibition, generation of free radicals and apoptosis. The present study aims to further clarify the cytostatic activity of doxorubicin by its specific effect on (a) DNA damage, (b) micronucleation and (c) apoptosis, using a combination of different methods and cell systems such as human lymphocytes and HL-60 human leukemic cells. DNA lesions were analyzed by the alkaline comet assay in combination with formamidopyrimidine (Fpg) and human 8-oxoguanine (hOGG1) repair enzymes. Micronucleation was investigated by the Cytokinesis-Block Micronucleus assay (CBMN) in combination with Fluorescence In Situ Hybridization analysis. Impairment on mitotic apparatus was investigated by double immunofluorescence of β- and γ-tubulin. Apoptotic cell frequency was determined by the CBMN cytome assay. Complementary to the above, caspase-3 level was investigated by Western blot.

RESULTS

It was found that doxorubicin generates DNA breakage induced by oxidative damage in DNA bases, which can be repaired by the Fpg and hOGG1 enzymes. Increased micronucleus frequency was identified mainly through chromosome breakage and, at a lesser extent, through chromosome delay. Analysis of mitotic spindle showed disturbance of chromosome orientation and centrosome duplication and/or separation, leading to aneuploidy. Enhanced frequency of apoptotic leukemic cells was also observed. Caspase-3 seems to be involved in the generation of apoptosis.

CONCLUSIONS

The aforementioned findings derived from different treatment schedules, doses and time of exposure on primary versus transformed cells extend our knowledge about doxorubicin genotoxicity and contribute to the better understanding of the mechanisms by which doxorubicin induces genotoxic effects on human cells.

PCNA and JNK1-Stat3 pathways respectively promotes and inhibits diabetes-associated centrosome amplification by targeting at the ROCK1/14-3-3σ complex in human colon cancer HCT116 cells

We have recently reported that type 2 diabetes promotes centrosome amplification via enhancing the expression, biding, and centrosome translocation of rho‐associated coiled‐coil containing protein kinase 1 (ROCK1)/14‐3‐3σ complex in HCT116 cells. In the functional proteomic study, we further investigated the molecular pathways underlying the centrosome amplification using HCT116 cells. We found that treatment of HCT116 cells with high glucose, insulin, and palmitic acid triggered the centrosome amplification and increased the expressions of proliferating cell nuclear antigen (PCNA), nucleophosmin (NPM), and 14‐3‐3σ. Individual knockdown of PCNA, NPM, or 14‐3‐3σ inhibited the centrosome amplification. Knockdown of PCNA inhibited the treatment‐increased expression of ROCK1, whereas knockdown of ROCK1 did not affect the PCNA expression. High glucose, insulin, and palmitic acid also increased the expressions of c‐Jun N‐terminal kinase‐1 (JNK1) and signal transducer and activator of transcription 3 (Stat3), individual knockdown of which upregulated the treatment‐increased expression of 14‐3‐3σ and promoted the centrosome amplification. In contrast, overexpression of JNK1 inhibited the centrosome amplification. Knockdown of Stat3 enhanced the centrosome translocation of 14‐3‐3σ. Moreover, we showed that knockdown of JNK1 inhibited the treatment‐increased expression of Stat3. Knockdown of PCNA, JNK1, or Stat3 did not have an effect on NPM and vice versa. In conclusion, our results suggest that PCNA and JNK1‐Stat3 pathways respectively promotes and feedback inhibits the centrosome amplification by targeting at the ROCK1/14‐3‐3σ complex, and NPM serves as an independent signal for the centrosome amplification.

Pharmacological Inhibition of PARP6 Triggers Multipolar Spindle Formation and Elicits Therapeutic Effects in Breast Cancer

: PARP proteins represent a class of post-translational modification enzymes with diverse cellular functions. Targeting PARPs has proven to be efficacious clinically, but exploration of the therapeutic potential of PARP inhibition has been limited to targeting poly(ADP-ribose) generating PARP, including PARP1/2/3 and tankyrases. The cancer-related functions of mono(ADP-ribose) generating PARP, including PARP6, remain largely uncharacterized. Here, we report a novel therapeutic strategy targeting PARP6 using the first reported PARP6 inhibitors. By screening a collection of PARP compounds for their ability to induce mitotic defects, we uncovered a robust correlation between PARP6 inhibition and induction of multipolar spindle (MPS) formation, which was phenocopied by PARP6 knockdown. Treatment with AZ0108, a PARP6 inhibitor with a favorable pharmacokinetic profile, potently induced the MPS phenotype, leading to apoptosis in a subset of breast cancer cells in vitro and antitumor effects in vivo. In addition, Chk1 was identified as a specific substrate of PARP6 and was further confirmed by enzymatic assays and by mass spectrometry. Furthermore, when modification of Chk1 was inhibited with AZ0108 in breast cancer cells, we observed marked upregulation of p-S345 Chk1 accompanied by defects in mitotic signaling. Together, these results establish proof-of-concept antitumor efficacy through PARP6 inhibition and highlight a novel function of PARP6 in maintaining centrosome integrity via direct ADP-ribosylation of Chk1 and modulation of its activity. SIGNIFICANCE: These findings describe a new inhibitor of PARP6 and identify a novel function of PARP6 in regulating activation of Chk1 in breast cancer cells.

TTK promotes mesenchymal signaling via multiple mechanisms in triple negative breast cancer

Abnormal expression of TTK kinase has been associated with the initiation, progression, and therapeutic resistance of breast and other cancers, but its roles remain to be clarified. In this study, we examined the role of TTK in triple negative breast cancer (TNBC), and found that higher TTK expression correlated with mesenchymal and proliferative phenotypes in TNBC cells. Pharmacologic inhibition and genomic silencing of TTK not only reversed the epithelial-to-mesenchymal transition (EMT) in TNBC cells, but also increased the expression of KLF5, an effector of TGF-β signaling and inhibitor of EMT. In addition, TTK inhibition decreased the expression of EMT-associated micro-RNA miR-21 but increased the expression of miR-200 family members and suppressed TGF-β signaling. To test if upregulation of KLF5 plays a role in TTK-induced EMT, TTK and KLF5 were silenced simultaneously, which reversed the decreased EMT caused by loss of TTK. Consistently, the decrease in miR-21 expression and increase in miR-200 expression caused by TTK silencing were rescued by loss of KLF5. Altogether, this study highlights a novel role and signaling pathway for TTK in regulating EMT of TN breast cancer cells through TGF-β and KLF5 signaling, highlighting targetable signaling pathways for TTK inhibitors in aggressive breast cancer.

Extrauterine high-grade serous carcinomas with bilateral adnexal involvement as the only two disease sites are clonal based on tp53 sequencing results: implications for biology, classification, and staging

A previous multicenter study of 67 cases of Stage I/II tubo-ovarian high-grade serous carcinoma with complete tubal sampling identified 7 cases in which there were only two disease sites, comprising tumor involving opposite adnexa with no extra-adnexal involvement. This study aimed to determine whether such low-stage extrauterine high-grade serous carcinomas with only two sites of involvement, located on opposite adnexa, have identical or different TP53 mutations in order to investigate their clonal relationship. DNA extracted from both sites of involvement was subjected to TP53 sequencing (n=6) or sequencing of one site and mutation confirmation by droplet digital PCR for the other site (n=1). Of the 7 cases analyzed, 1 case had unilateral serous tubal intraepithelial carcinoma with contralateral ovarian high-grade serous carcinoma, 3 had tubal high-grade serous carcinomas (±serous tubal intraepithelial carcinoma) with contralateral ovarian high-grade serous carcinoma, 2 had bilateral ovarian high-grade serous carcinomas with normal tubes, and 1 had bilateral fallopian tube high-grade serous carcinoma with normal ovaries. All 7 cases showed identical TP53 mutations in tumor from both disease sites. Therefore, these rare cases of high-grade serous carcinoma confined to opposite adnexa all show clonal identity between the two sites of involvement, suggesting unifocal origin and metastasis rather than multifocal origin. Our results suggest that serous tubal intraepithelial carcinoma or adnexal high-grade serous carcinoma can metastasize to the contralateral adnexa without peritoneal involvement. Given the clonal relationship between the two sites, such cases should be considered stage II, with stage I reserved for cases with unilateral and unifocal adnexal involvement. Furthermore, serous tubal intraepithelial carcinoma without invasion should be taken to constitute a disease site for staging purposes.

Kinesin Motor Protein KIFC1 Is a Target Protein of miR-338-3p and Is Associated With Poor Prognosis and Progression of Renal Cell Carcinoma

KIFC1 (kinesin family member C1) plays a critical role in clustering of extra centrosomes in various cancer cells and thus could be considered as a promising therapeutic target. However, whether KIFC1 is involved in the procession of renal cell carcinoma (RCC) still remains unclear. In this study, we found that KIFC1 was upregulated in RCC tissues and is responsible for RCC tumorigenesis (p < 0.001). The high expression of KIFC1 correlates with aggressive clinicopathologic parameters. Kaplan–Meier analysis suggested that KIFC1 was associated with poor survival prognosis in RCC. Silencing KIFC1 dramatically resulted in inhibition of proliferation, delayed the cell cycle at G₂/M phase, and suppressed cell invasion and migration in vitro. The antiproliferative effect of KIFC1 silencing was also observed in xenografted tumors in vivo. miR-338-3p could directly bind to the 3′-untranslated region (3′-UTR) of KIFC1, and ectopic miR-338-3p expression mimicked the inhibitory functions of KIFC1 silencing on RCC cells through inactivation of the PI3K/AKT signaling pathway. Therefore, these results revealed that KIFC1 may be a novel biomarker and an effective therapeutic target for the treatment of RCC.

Prevention effect of rare ginsenosides against stress-hormone induced MTOC amplification

Stress has been suggested as one of important cause of human cancer without molecular biological evidence. Thus, we test the effect of stress-related hormones on cell viability and mitotic fidelity. Similarly to estrogen, stress hormone cortisol and its relative cortisone increase microtubule organizing center (MTOC) number through elevated expression of γ-tubulin and provide the Taxol resistance to human cancer cell lines. However, these effects are achieved by glucocorticoid hormone receptor (GR) but not by estrogen receptor (ER). Since ginsenosides possess steroid-like structure, we hypothesized that it would block the stress or estrogen-induced MTOC amplification and Taxol resistance. Among tested chemicals, rare ginsenoside, CSH1 (Rg6) shows obvious effect on inhibition of MTOC amplification, γ-tubulin induction and Taxol resistance. Comparing to Fulvestant (FST), ER-α specific inhibitor, this chemical can block the cortisol/cortisone-induced MTOC deregulation as well as ER-α signaling. Our results suggest that stress hormone induced tumorigenesis would be achieved by MTOC amplification, and CSH1 would be useful for prevention of stress-hormone or steroid hormone-induced chromosomal instability.

Synchronous tumours of the female reproductive tract

Many ovarian endometrioid carcinomas present with concurrent endometrial carcinoma, and these organ-confined, low-grade synchronous endometrial and ovarian tumours consistently behave as independent primary tumours, rather than a single advanced-stage carcinoma; they are associated with a very favourable prognosis and there is no need for adjuvant treatment. This phenomenon of synchronous tumours involving two or more sites within the female reproductive tract is well recognised, occurring in 1-2% of cases. Although some tumours can be recognised as metastasis, in many the relationship between the synchronous tumours is uncertain. Recently, application of next generation sequencing to synchronous endometrial and ovarian carcinomas has shed light on the relationship between these tumours, but raised more questions about the biology of this curious phenomenon. Herein, we review synchronous tumours involving more than one site in the female genital tract, discuss the pathogenesis, and offer guidelines for how to handle in routine practice.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Centrosome amplification: a suspect in breast cancer and racial disparities

The multifaceted involvement of centrosome amplification (CA) in tumorigenesis is coming into focus following years of meticulous experimentation, which have elucidated the powerful abilities of CA to promote cellular invasion, disrupt stem cell division, drive chromosomal instability (CIN) and perturb tissue architecture, activities that can accelerate tumor progression. Integration of the extant in vitro, in vivo and clinical data suggests that in some tissues CA may be a tumor-initiating event, in others a consequential 'hit' in multistep tumorigenesis, and in some others, non-tumorigenic. However, in vivo data are limited and primarily focus on PLK4 (which has CA-independent mechanisms by which it promotes aggressive cellular phenotypes). In vitro breast cancer models suggest that CA can promote tumorigenesis in breast cancer cells in the setting of p53 loss or mutation, which can both trigger CA and promote cellular tolerance to its tendency to slow proliferation and induce aneuploidy. It is thus our perspective that CA is likely an early hit in multistep breast tumorigenesis that may sometimes be lost to preserve aggressive karyotypes acquired through centrosome clustering-mediated CIN, both numerical and structural. We also envision that the robust link between p53 and CA may underlie, to a considerable degree, racial health disparity in breast cancer outcomes. This question is clinically significant because, if it is true, then analysis of centrosomal profiles and administration of centrosome declustering drugs could prove highly efficacious in risk stratifying breast cancers and treating African American (AA) women with breast cancer.

Global gene expression profiling and senescence biomarker analysis of hESC exposed to H2O2 induced non-cytotoxic oxidative stress

Background

Human embryonic stem cells (hESCs) potentially offer new routes to study, on the basis of the Developmental Origins of Health and Disease (DOHaD) concept, how the maternal environment during pregnancy influences the offspring’s health and can predispose to chronic disease in later life. Reactive oxygen species (ROS), antioxidant defences and cellular redox status play a key function in gene expression regulation and are involved in diabetes and metabolic syndromes as in ageing.

Methods

We have, therefore, designed an in vitro cell model of oxidative stress by exposing hESCs to hydrogen peroxide (H₂O₂) during 72 h, in order to resemble the period of preimplantation embryonic development.

Results

We have analysed the global gene expression profiles of hESCs (HUES3) exposed to non-cytotoxic H₂O₂ concentrations, using Illumina microarray HT-12 v4, and we found the differential expression of 569 upregulated and 485 downregulated genes. The most affected gene ontology categories were those related with RNA processing and splicing, oxidation reduction and sterol metabolic processes. We compared our findings with a published RNA-seq profiling dataset of human embryos developed in vitro, thereupon exposed to oxidative stress, and we observed that one of the common downregulated genes between this publication and our data, NEDD1, is involved in centrosome structure and function.

Conclusions

Therefore, we assessed the presence of supernumerary centrosomes and showed that the percentage of cells with more than two centrosomes increased acutely with H₂O₂ treatment in hESCs (HUES3 and 7) and in a control somatic cell line (Hs27), inducing a premature entry into senescence.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0602-6) contains supplementary material, which is available to authorized users.

KIF11 silencing and inhibition induces chromosome instability that may contribute to cancer

Understanding the aberrant pathways that contribute to oncogenesis and identifying the altered genes involved in these pathways is a critical first step to develop effective strategies to better combat cancer. Chromosome instability (CIN) is an aberrant phenotype that occurs in ∼80% of all cancer types and is associated with aggressive tumors, the acquisition of multidrug resistance and poor patient prognosis. Despite these associations however, the aberrant genes and molecular defects underlying CIN remain poorly understood. KIF11 is an evolutionarily conserved microtubule motor protein that functions in centrosome and chromosome dynamics in mitosis. Interestingly, the yeast ortholog of KIF11, namely CIN8 is a CIN gene and thus aberrant KIF11 expression and function is suspected to underlie CIN. In support of this possibility, KIF11 is somatically altered in a large number of cancer types. Using a complementary biochemical and genetic approach we examined whether KIF11 silencing with siRNAs or inhibition with monastrol was able to convert two distinct and karyotypically stable cell lines into karyotypically unstable cell lines. Indeed, quantitative imaging microscopy and flow cytometry revealed that KIF11 silencing induced increases in nuclear areas, micronucleus formation, DNA content and chromosome numbers relative to controls that was also observed following KIF11 inhibition. Collectively, this study identifies and validates KIF11 as an evolutionarily conserved CIN gene, and further suggests that aberrant expression and function may contribute to the pathogenesis of a subset of cancers.