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During the last decades, the knowledge of cell death mechanisms involved in anticancer therapy has grown exponentially. However, in many studies, cell death is still described in an incomplete manner. The frequent use of indirect proliferation assays, unspecific probes, or bulk analyses leads too often to misunderstandings regarding cell death events. There is a trend to focus on molecular or genetic regulations of cell demise without a proper characterization of the phenotype that is the object of this study. Sometimes, cancer researchers can feel overwhelmed or confused when faced with such a corpus of detailed insights, nomenclature rules, and debates about the accuracy of a particular probe or assay. On the basis of the information available, we propose a simple guide to distinguish forms of cell death in experimental settings using cancer cell lines. [ABSTRACT FROM AUTHOR]

Abstract: DNA damage, cell cycle and apoptosis form a network with important implications for cancer chemotherapy. Dysfunctions of the cycle checkpoints can allow cancer cells to acquire drug resistance. Etoposide is a well-known inducer of apoptosis, which is widely used in cell biology and in clinical practice. In this work we report that a pulse of 50μM etoposide (incubation for only 3h) on HeLa cells causes a sequence of events that leads to abnormal mitotic figures that could be followed either by cell death or, more commonly, by interphase restitution and endocycle. The endocycling polyploid cells enter immediately into mitosis and suffer metaphase blockage with multiple spindle poles, which were generally followed by a direct triggering of apoptosis from metaphase (mitotic catastrophe), or by a new process of endocycling, until surviving cells finally became apoptotic (96h after the treatment). [Copyright &y& Elsevier]

A response by Santiago Rello-Varona and colleagues to a letter to the editor about their article "(Not) all (dead) things share the same breath": identification of cell death mechanisms in anticancer therapy," published in a previous issue is presented.

Epigenetic modifications have been shown to be important in developmental tumors as Ewing sarcoma. We profiled the DNA methylation status of 15 primary tumors, 7 cell lines, 10 healthy tissues and 4 human mesenchymal stem cells lines samples using the Infinium Human Methylation 450K. Differential methylation analysis between Ewing sarcoma and reference samples revealed 1166 hypermethylated and 864 hypomethylated CpG sites (Bonferroni p < 0.05, δ-β-value with absolute difference of >0.20) corresponding to 392 and 470 genes respectively. Gene Ontology analysis of genes differentially methylated in Ewing sarcoma samples showed a significant enrichment of developmental genes. Membrane and cell signal genes were also enriched, among those, 11 were related to caveola formation. We identified differential hypermethylation of CpGs located in the body and S-Shore of the PTRF gene in Ewing sarcoma that correlated with its repressed transcriptional state. Reintroduction of PTRF/Cavin-1 in Ewing sarcoma cells revealed a role of this protein as a tumor suppressor. Restoration of caveolae in the membrane of Ewing sarcoma cells, by exogenously reintroducing PTRF, disrupts the MDM2/p53 complex, which consequently results in the activation of p53 and the induction of apoptosis. [ABSTRACT FROM AUTHOR]

Tetraploidy constitutes a genomically metastable state that can lead to aneuploidy and genomic instability. Tetraploid cells are frequently found in preneoplastic lesions, including intestinal cancers arising due to the inactivation of the tumor suppressor adenomatous polyposis coli (APC). Using a phenotypic screen, we identified resveratrol as an agent that selectively reduces the fitness of tetraploid cells by slowing down their cell cycle progression and by stimulating the intrinsic pathway of apoptosis. Selective killing of tetraploid cells was observed for a series of additional agents that indirectly or directly stimulate AMP-activated protein kinase (AMPK) including salicylate, whose chemopreventive action has been established by epidemiological studies and clinical trials. Both resveratrol and salicylate reduced the formation of tetraploid or higher-order polyploid cells resulting from the culture of human colon carcinoma cell lines or primary mouse epithelial cells lacking tumor protein p53 (TP53, best known as p53) in the presence of antimitotic agents, as determined by cytofluorometric and videomicroscopic assays. Moreover, oral treatment with either resveratrol or aspirin, the prodrug of salicylate, repressed the accumulation of tetraploid intestinal epithelial cells in the ApcMin/+ mouse model of colon cancer. Collectively, our results suggest that the chemopreventive action of resveratrol and aspirin involves the elimination of tetraploid cancer cell precursors. [ABSTRACT FROM AUTHOR]

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in childhood and adolescence. Patients with the most aggressive histological variant have an unfavorable prognosis due to a high metastasis incidence. Lysyl oxidase-like 2 (LOXL2) is a lysyl oxidase, member of a family of extracellular matrix (ECM) crosslinking enzymes that recently have emerged as important regulators of tumor progression and metastasis. We report that LOXL2 is overexpressed in RMS, suggesting a potential role for LOXL2 in RMS oncogenic progression. Consistently, transient and stable LOXL2 knockdown decreased cell migratory and invasive capabilities in two ARMS cell lines. Furthermore, introduction of LOXL2 in RMS non-expressing cells using wild type or mutated (catalytically inactive) constructs resulted in increased cell migration, cell invasion and number and incidence of spontaneous lung metastasis in vivo, independently of its catalytic activity. To further study the molecular mechanism associated with LOXL2 expression, a pull-down assay on LOXL2-transfected cells was performed and analyzed by mass spectrometry. The intermediated filament protein vimentin was validated as a LOXL2-interactor. Thus, our results suggest an oncogenic role of LOXL2 in RMS by regulating cytoskeleton dynamics and cell motility capabilities. [ABSTRACT FROM AUTHOR]

For many years, clinical and non-clinical investigations have investigated cortical bone structure in an attempt to address questions related to normal bone development, mineralisation, pathologies and even evolutionary trends in our lineage (adaptations). Research in the fields of medicine, materials science, physical anthropology, palaeontology, and even archaeobiology has contributed interesting data. However, many questions remain regarding the histomorphological and histochemical variations in human cortical bone during different stages of life. In the present work, we describe a study of long bone cortex transformations during ontogeny. We analysed cross-sections of 15 human humeri histomorphologically and histochemically from perinatal to adult age, marking and quantifying the spatial distribution of bone tissue types using GIS software and analysing the mineral composition and crystallinity of the mineralised cortex using Raman spectroscopy and X-ray diffraction. Our results allowed us to propose that human cortical bone undergoes three main 'events' through ontogeny that critically change the proportions and structure of the cortex. In early development, bone is not well mineralised and proportionally presents a wide cortex that narrows through the end of childhood. Before reaching complete maturity, the bone mineral area increases, allowing the bone to nearly reach the adult size. The medullary cavity is reduced, and the mineral areas have a highly ordered crystalline structure. The last event occurs in adulthood, when the 'oldest' individuals present a reduced mineralised area, with increasing non-mineralised cavities (including the medullary cavity) and reduced crystalline organisation. [ABSTRACT FROM AUTHOR]

Cancer cells accommodate multiple genetic and epigenetic alterations that initially activate intrinsic (cell-autonomous) and extrinsic (immune-mediated) oncosuppressive mechanisms. Only once these barriers to oncogenesis have been overcome can malignant growth proceed unrestrained. Tetraploidization can contribute to oncogenesis because hyperploid cells are genomically unstable. We report that hyperploid cancer cells become immunogenic because of a constitutive endoplasmic reticulum stress response resulting in the aberrant cell surface exposure of calreticulin. Hyperploid, calreticulin-exposing cancer cells readily proliferated in immunodeficient mice and conserved their increased DNA content. In contrast, hyperploid cells injected into immunocompetent mice generated tumors only after a delay, and such tumors exhibited reduced DNA content, endoplasmic reticulum stress, and calreticulin exposure. Our results unveil an immunosurveillance system that imposes immunoselection against hyperploidy in carcinogen- and oncogene-induced cancers. [ABSTRACT FROM AUTHOR]

Abstract: Throughout ontogeny, human bones undergo differentiation in terms of shape, size and tissue type; this is a complex scenario in which the variations in the tissue compartmentalisation of the cortical bone are still poorly understood. Currently, compartmentalisation is studied using methodologies that oversimplify the bone tissue complexity. Here, we present a new methodological approach that integrates a histological description and a mineral content analysis to study the compartmentalisation of the whole mineralised and non-mineralised tissues (i.e., spatial distribution in long bone sections). This new methodology, based on Geographical Information System (GIS) software, allows us to draw areas of interest (i.e., tracing vectorial shapes which are quantifiable) in raw images that are extracted from microscope and compared them spatially in a semi-automatic and quantitative fashion. As an example of our methodology, we have studied the tibiae from individuals with different age at death (infant, juvenile and adult). The tibia’s cortical bone presents a well-formed fibrolamellar bone, in which remodelling is clearly evidenced from early ontogeny, and we discuss the existence of “lines of arrested growth”. Concurrent with the histological variation, Raman and FT-IR spectroscopy analyses corroborate that the mineral content in the cortical bone changes differentially. The anterior portion of the tibia remains highly pierced and is less crystalline than the rest of the cortex during growth, which is evidence of more active and continuous remodelling. Finally, while porosity and other “non-mineralised cavities” are largely modified, the mineralised portion and the marrow cavity size persist proportionally during ontogeny. [Copyright &y& Elsevier]

Antineoplastic chemotherapies are particularly efficient when they elicit immunogenic cell death, thus provoking an anticancer immune response. Here we demonstrate that autophagy, which is often disabled in cancer, is dispensable for chemotherapy-induced cell death but required for its immunogenicity. In response to chemotherapy, autophagy-competent, but not autophagy-deficient, cancers attracted dendritic cells and T lymphocytes into the tumor bed. Suppression of autophagy inhibited the release of adenosine triphosphate (ATP) from dying tumor cells. Conversely, inhibition of extracellular ATP-degrading enzymes increased pericellular ATP in autophagy-deficient tumors, reestablished the recruitment of immune cells, and restored chemotherapeutic responses but only in immunocompetent hosts. Thus, autophagy is essential for the immunogenic release of ATP from dying cells, and increased extracellular ATP concentrations improve the efficacy of antineoplastic chemotherapies when autophagy is disabled. [ABSTRACT FROM AUTHOR]

Tetraploidy can constitute a metastable intermediate between normal diploidy and oncogenic aneuploidy. Here, we show that the absence of p53 is not only permissive for the survival but also for multipolar asymmetric divisions of tetraploid cells, which lead to the generation of aneuploid cells with a near-to-diploid chromosome content. Multipolar mitoses (which reduce the tetraploid genome to a sub-tetraploid state) are more frequent when p53 is downregulated and the product of the Mos oncogene is upregulated. Mos inhibits the coalescence of supernumerary centrosomes that allow for normal bipolar mitoses of tetraploid cells. In the absence of p53, Mos knockdown prevents multipolar mitoses and exerts genome-stabilizing effects. These results elucidate the mechanisms through which asymmetric cell division drives chromosomal instability in tetraploid cells. [ABSTRACT FROM AUTHOR]