Chromosome integrity checkpoints in stem and progenitor cells: transitions upon differentiation, pathogenesis, and aging

Calreticulin and JAK2V617F driver mutations induce distinct mitotic defects in myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) encompass a diverse group of hematologic disorders driven by mutations in JAK2, CALR, or MPL. The prevailing working model explaining how these driver mutations induce different disease phenotypes is based on the decisive influence of the cellular microenvironment and the acquisition of additional mutations. Here, we report increased levels of chromatin segregation errors in hematopoietic cells stably expressing CALRdel52 or JAK2V617F mutations. Our investigations employing murine 32DMPL and human erythroleukemic TF-1MPL cells demonstrate a link between CALRdel52 or JAK2V617F expression and a compromised spindle assembly checkpoint (SAC), a phenomenon contributing to error-prone mitosis. This defective SAC is associated with imbalances in the recruitment of SAC factors to mitotic kinetochores upon CALRdel52 or JAK2V617F expression. We show that JAK2 mutant CD34 + MPN patient-derived cells exhibit reduced expression of the master mitotic regulators PLK1, aurora kinase B, and PP2A catalytic subunit. Furthermore, the expression profile of mitotic regulators in CD34 + patient-derived cells allows to faithfully distinguish patients from healthy controls, as well as to differentiate primary and secondary myelofibrosis from essential thrombocythemia and polycythemia vera. Altogether, our data suggest alterations in mitotic regulation as a potential driver in the pathogenesis in MPN.

An Early Neoplasia Index (ENI10), Based on Molecular Identity of CD10 Cells and Associated Stemness Biomarkers, is a Predictor of Patient Outcome in Many Cancers

An accurate estimate of patient survival at diagnosis is critical to plan efficient therapeutic options. A simple and multiapplication tool is needed to move forward the precision medicine era. Taking advantage of the broad and high CD10 expression in stem and cancers cells, we evaluated the molecular identity of aggressive cancer cells. We used epithelial primary cells and developed a breast cancer stem cell–based progressive model. The superiority of the early-transformed isolated molecular index was evaluated by large-scale analysis in solid cancers. BMP2-driven cell transformation increases CD10 expression which preserves stemness properties. Our model identified a unique set of 159 genes enriched in G2–M cell-cycle phases and spindle assembly complex. Using samples predisposed to transformation, we confirmed the value of an early neoplasia index associated to CD10 (ENI10) to discriminate premalignant status of a human tissue. Using a stratified Cox model, a large-scale analysis (>10,000 samples, The Cancer Genome Atlas Pan-Cancer) validated a strong risk gradient (HRs reaching HR = 5.15; 95% confidence interval: 4.00–6.64) for high ENI10 levels. Through different databases, Cox regression model analyses highlighted an association between ENI10 and poor progression-free intervals for more than 50% of cancer subtypes tested, and the potential of ENI10 to predict drug efficacy. The ENI10 index constitutes a robust tool to detect pretransformed tissues and identify high-risk patients at diagnosis. Owing to its biological link with refractory cancer stem cells, the ENI10 index constitutes a unique way of identifying effective treatments to improve clinical care.

SIGNIFICANCE

We identified a molecular signature called ENI10 which, owing to its biological link with stem cell properties, predicts patient outcome and drugs efficiency in breast and several other cancers. ENI10 should allow early and optimized clinical management of a broad number of cancers, regardless of the stage of tumor progression.

Can precancerous stem cells be risk markers for malignant transformation in the oral mucosa?

Accurate assessment of the carcinogenic potential of oral mucosal diseases can significantly reduce the prevalence of oral cancer. We speculate that precancerous stem cells (pCSCs) arise during the evolution of carcinomas based on long-term experimental findings, published literature, and the cancer stem cell (CSC) theory, wherein pCSCs exist in precancerous lesions and have characteristics of both CSCs and normal stem cells. This apparently contradictory feature may be the foundation of the reversible transformation of precancerous lesions. Predicting malignant transformation in potentially malignant oral illnesses would allow for focused treatment, prognosis, and secondary prevention. Currently available clinical assays for chromosomal instability and DNA aneuploidy have several deficiencies. We hope that our study will increase attention to pCSC research and lead to the development of novel strategies for the prevention and treatment of oral cancer by identifying pCSC markers.

The second half of mitosis and its implications in cancer biology

The nucleus undergoes dramatic structural and functional changes during cell division. With the entry into mitosis, in human cells the nuclear envelope breaks down, chromosomes rearrange into rod-like structures which are collected and segregated by the spindle apparatus. While these processes in the first half of mitosis have been intensively studied, much less is known about the second half of mitosis, when a functional nucleus reforms in each of the emerging cells. Here we review our current understanding of mitotic exit and nuclear reformation with spotlights on the links to cancer biology.

LiveCellMiner: A new tool to analyze mitotic progression

Live-cell imaging has become state of the art to accurately identify the nature of mitotic and cell cycle defects. Low- and high-throughput microscopy setups have yield huge data amounts of cells recorded in different experimental and pathological conditions. Tailored semi-automated and automated image analysis approaches allow the analysis of high-content screening data sets, saving time and avoiding bias. However, they were mostly designed for very specific experimental setups, which restricts their flexibility and usability. The general need for dedicated experiment-specific user-annotated training sets and experiment-specific user-defined segmentation parameters remains a major bottleneck for fully automating the analysis process. In this work we present LiveCellMiner, a highly flexible open-source software tool to automatically extract, analyze and visualize both aggregated and time-resolved image features with potential biological relevance. The software tool allows analysis across high-content data sets obtained in different platforms, in a quantitative and unbiased manner. As proof of principle application, we analyze here the dynamic chromatin and tubulin cytoskeleton features in human cells passing through mitosis highlighting the versatile and flexible potential of this tool set.

Peculiar features of bone marrow cell proliferation in Djungarian hamsters with genetic disorders under thiotepa effect

The paper aims to examine the proliferation of bone marrow cell pool in Djungarian hamsters and the subsequent restoration of their genetic stability after the action of thiotepa (TT). The study involved 36 animals, of which 16 were in the control group (injected with 0.25 ml of physiological solution), and 20 in the experimental group (0.25 ml of thiotepa at a dose of 1.5 mg per 1 kg of body weight). The maximum number of cells with CA amounting to 30.0% was observed 13 hours after TT injection (p≤0.05 between the control and experimental groups) and rapidly declined to 5.7% over subsequent periods by the 37th hour of the experiment (p≤0.05). The results suggest that the restoration of cell pool genetic stability is largely associated with the cell selection mechanisms, which confers an advantage over cell proliferation without chromosome anomalies.

TERRA Gene Expression in Gastric Cancer: Role of hTERT

PURPOSE

One of the most important serious malignancies is gastric cancer (GC) with a high mortality globally. In this way, beside the environmental factors, genetic parameter has a remarkable effective fluctuation in GC. Correspondingly, telomeres are nucleoprotein structures measuring the length of telomeres and they have special potential in diagnosis of various types of cancers. Defect protection of the telomeric length initiates the instability of the genome during cancer, including gastric cancer. The most common way of maintaining telomere length is the function of the telomerase enzyme that replicates the TTAGGG to the end of the 3' chromosome.

METHODS

In this review, we want to discuss the alterations of hTERT repression on the modification of TERRA gene expression in conjunction with the importance of telomere and telomerase in GC.

RESULTS

The telomerase enzyme contains two essential components called telomerase reverse transcriptase (hTERT) and RNA telomerase (hTR, hTERC). Deregulation of hTERT plays a key role in the multistage process of tumorigenicity and anticancer drug resistance. The direct relationship between telomerase activity and hTERT has led to hTERT to be considered a key target for cancer treatment. Recent results show that telomeres are transcribed into telomeric repeat-containing RNA (TERRA) in mammalian cells and are long noncoding RNAs (lncRNAs) identified in different tissues. In addition, most chemotherapy methods have a lot of side effects on normal cells.

CONCLUSION

Telomere and telomerase are useful therapeutic goal. According to the main roles of hTERT in tumorigenesis, growth, migration, and cancer invasion, hTERT and regulatory mechanisms that control the expression of hTERT are attractive therapeutic targets for cancer treatment.

Induction of DNA damage as a consequence of occupational exposure to crystalline silica: A review and meta-analysis

About 40 million workers are occupationally exposed to crystalline silica (CS) which was classified as a human carcinogen by the IARC. It is assumed that damage of the genetic material via inflammation and reactive oxygen species by CS lead to formation of malignant cells. We conducted a systematic literature search to find out if inhalation of CS containing dusts at workplaces causes damage of the genetic material. Thirteen studies were found eligible for this review, in most of them (n = 9) micronuclei (MN) which reflect structural/numerical chromosomal aberrations were monitored in lymphocytes and/or in exfoliated buccal cells. In 5 investigations DNA damage was measured in blood cells in single cell gel electrophoresis (comet) experiments. Frequently studied groups were potters, stone cutters, miners and construction workers. Results of meta-analyses show that exposure to CS causes formation of MN and DNA breaks, the overall ratio values were in exposed workers 2.06- and 1.96-fold higher than in controls, respectively. Two studies reported increased levels of oxidized guanine, and higher levels of DNA adducts with malondialdehyde indicating that exposure to CS leads to oxidative damage. The exposure of the workers to CS was quantified only in two studies, information concerning the size and chemical structures of the particles is lacking in most investigations. Therefore, it is not possible to use the results to derive occupational exposure limits of workers to CS which vary strongly in different countries. Nevertheless, the evaluation of the current state of knowledge shows that biomonitoring studies in which damage of the genetic material is measured in CS exposed workers can contribute to assess adverse health effects as consequence of DNA instability in specific occupations.

The balance between mitotic death and mitotic slippage in acute leukemia: a new therapeutic window?

Mitosis is the process whereby an eukaryotic cell divides into two identical copies. Different multiprotein complexes are involved in the fine regulation of cell division, including the mitotic promoting factor and the anaphase promoting complex. Prolonged mitosis can result in cellular division, cell death, or mitotic slippage, the latter leading to a new interphase without cellular division. Mitotic slippage is one of the causes of genomic instability and has an important therapeutic and clinical impact. It has been widely studied in solid tumors but not in hematological malignancies, in particular, in acute leukemia. We review the literature data available on mitotic regulation, alterations in mitotic proteins occurring in acute leukemia, induction of prolonged mitosis and its consequences, focusing in particular on the balance between cell death and mitotic slippage and on its therapeutic potentials. We also present the most recent preclinical and clinical data on the efficacy of second-generation mitotic drugs (CDK1-Cyclin B1, APC/CCDC20, PLK, Aurora kinase inhibitors). Despite the poor clinical activity showed by these drugs as single agents, they offer a potential therapeutic window for synthetic lethal combinations aimed to selectively target leukemic cells at the right time, thus decreasing the risk of mitotic slippage events.

Calling Variants in the Clinic: Informed Variant Calling Decisions Based on Biological, Clinical, and Laboratory Variables

Deep sequencing genomic analysis is becoming increasingly common in clinical research and practice, enabling accurate identification of diagnostic, prognostic, and predictive determinants. Variant calling, distinguishing between true mutations and experimental errors, is a central task of genomic analysis and often requires sophisticated statistical, computational, and/or heuristic techniques. Although variant callers seek to overcome noise inherent in biological experiments, variant calling can be significantly affected by outside factors including those used to prepare, store, and analyze samples. The goal of this review is to discuss known experimental features, such as sample preparation, library preparation, and sequencing, alongside diverse biological and clinical variables, and evaluate their effect on variant caller selection and optimization.

Targeting the CINful genome: Strategies to overcome tumor heterogeneity

Genomic instability, and more specifically chromosomal instability (CIN), arises from a number of processes that are defective in cancer, such as aberrant mitotic cell division, replication stress, defective DNA damage repair, and ineffective telomere maintenance. CIN is an emerging hallmark of cancer that contributes to tumor heterogeneity through increased rates of genetic alterations. As genetic heterogeneity within a single tumor and between tumors is a key challenge leading to treatment failures, this brings to question, whether therapeutic approaches should aim at the genetic diversity or a specific mutation present within these tumors. Answering this question will determine the future of personalized targeted therapies. Here we discuss, how the genetic diversity associated with CIN in tumor cells can be used as a therapeutic advantage and targeted by exploiting the genetic concepts of synthetic lethality and synthetic dosage lethality. Given that a number of CIN-related pathways work together to fix the DNA damage within our genome and ensure proper segregation of chromosomes, we specifically focus on the genetic interactions amongst these pathways and their potential therapeutic applicability in cancer. We also discuss, how tumor genetic heterogeneity can be targeted in emerging immunotherapeutic approaches.

The Genomic Health of Human Pluripotent Stem Cells: Genomic Instability and the Consequences on Nuclear Organization

Human pluripotent stem cells (hPSCs) are increasingly used for cell-based regenerative therapies worldwide, with embryonic and induced pluripotent stem cells as potential treatments for debilitating and chronic conditions, such as age-related macular degeneration, Parkinson's disease, spinal cord injuries, and type 1 diabetes. However, with the level of genomic anomalies stem cells generate in culture, their safety may be in question. Specifically, hPSCs frequently acquire chromosomal abnormalities, often with gains or losses of whole chromosomes. This review discusses how important it is to efficiently and sensitively detect hPSC aneuploidies, to understand how these aneuploidies arise, consider the consequences for the cell, and indeed the individual to whom aneuploid cells may be administered.

Intermediate filaments and IF-associated proteins: from cell architecture to cell proliferation

Intermediate filaments (IFs), in coordination with microfilaments and microtubules, form the structural framework of the cytoskeleton and nucleus, thereby providing mechanical support against cellular stresses and anchoring intracellular organelles in place. The assembly and disassembly of IFs are mainly regulated by the phosphorylation of IF proteins. These phosphorylation states can be tracked using antibodies raised against phosphopeptides in the target proteins. IFs exert their functions through interactions with not only structural proteins, but also non-structural proteins involved in cell signaling, such as stress responses, apoptosis, and cell proliferation. This review highlights findings related to how IFs regulate cell division through phosphorylation cascades and how trichoplein, a centriolar protein originally identified as a keratin-associated protein, regulates the cell cycle through primary cilium formation.