Real-time flow cytometry for the kinetic analysis of oncosis

A near-infrared aggregation-induced emission photosensitizer targeting mitochondria for depleting Cu2+ to trigger light-activated cancer cells oncosis

Abnormally high levels of copper in tumors stimulate malignant proliferation and migration of cancer cells, which proposes a formidable challenge for the thorough therapy of malignant tumors. In this work, we developed a reliable, mitochondria-targeted near-infrared aggregation-induced emission fluorescent probe, TTQ-Th, whose thiourea moiety specifically could recognize mitochondria even both upon loss of mitochondrial membrane potential or in fixated cells, and can capture copper overexpressed by tumor cells, leading to severe copper deficiency. In parallel, TTQ-Th can generate sufficient reactive oxygen species (ROS) upon photoexcitation, while copper deficiency inhibits expression of related copper-based enzymes, resulting in a decline in ATP production. Such energy deficiency, combined with reduced MMP and elevated oxidative stress can lead to critical cell oncosis. Both in vitro and intracellular experiments can illustrate that the elevated ROS has remarkable damage to tumor cells and contributes to the elimination of the primary tumor, while copper deficiency further hinder tumor cell migration and induces G0/G1 cell cycle arrest in a dose-dependent manner, which is an efficacious strategy for the treatment of malignant tumors.

Construction and validation of a novel algorithm based on oncosis-related lncRNAs comprising the immune landscape and prediction of colorectal cancer prognosis

Colorectal cancer (CRC) has high morbidity and mortality, particularly if diagnosed at an advanced stage. Although there have been several studies on CRC, few have investigated the relationship between oncosis and CRC. Thus, the purpose of the present study was to identify oncosis-related long noncoding RNAs (lncRNAs) and to establish a clinical prognostic model. Original data were acquired from The Cancer Genome Atlas database and PubMed. Differentially expressed oncosis-related lncRNAs (DEorlncRNAs) were identified and were subsequently formed into pairs. Next, a series of tests and analyses, including both univariate and multivariate analyses, as well as Lasso and Cox regression analyses, were performed to establish a receiver operating characteristic curve. A cut-off point was subsequently used to divide the samples into groups labelled as high- or low-risk. Thus, a model was established and evaluated in several dimensions. Six pairs of DEorlncRNAs associated with prognosis according to the algorithm were screened out and the CRC cases were divided into high- and low-risk groups. Significant differences between patients in the different risk groups were observed for several traits, including survival outcomes, clinical pathology characteristics, immune cell infiltration status and drug sensitivity. In addition, PCR and flow cytometry were performed to further verify the model. In summary, a new risk model algorithm based on six pairs of DEorlncRNAs in CRC, which does not require specific data regarding the level of gene expression, was established and validated. This algorithm may be used to predict patient prognosis, immune cell infiltration and drug sensitivity.

Measurement of Cell Death in Mammalian Cells

Methods for assessing mammalian cell death are presented in this article, which is divided into six sections: (1) a brief overview of cytotoxicity and pathways of cell death; (2) a method to measure cell death using lactate dehydrogenase (LDH) release as a marker of membrane integrity; (3) a flow cytometry method that simultaneously measures two types of cell death, necrosis and apoptosis; (4) use of fluorescence microscopy and nuclear morphology to assess apoptosis and necrosis; (5) the use of multi-well plates and high-content analysis imaging systems to assess nuclear morphology; and (6) a discussion of the use of cytotoxicity assays to determine the mechanisms of cell death. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Measurement of plasma membrane integrity and viability using LDH release Basic Protocol 2: Measurement of necrosis and apoptosis using flow cytometry Basic Protocol 3: Determination of nuclear morphology and membrane integrity Alternate Protocol 1: Assessment of nuclear morphology and membrane integrity using DAPI and PI Alternate Protocol 2: Assessment of nuclear morphology using multi-well plates Basic Protocol 4: Measurement of time-dependent toxicity using cell death markers.

Disruption of microtubule function in cultured human cells by a cytotoxic ruthenium(ii) polypyridyl complex

Treatment of malignant and non-malignant cultured human cell lines with a cytotoxic IC₅₀ dose of ∼2 μM tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(ii) chloride (RPC2) retards or arrests microtubule motion as tracked by visualizing fluorescently-tagged microtubule plus end-tracking proteins. Immunofluorescent microscopic images of the microtubules in fixed cells show substantial changes to cellular microtubule network and to overall cell morphology upon treatment with RPC2. Flow cytometry with MCF7 and H358 cells reveals only minor elevations of the number of cells in G₂/M phase, suggesting that the observed cytotoxicity is not tied to mitotic arrest. In vitro studies with purified tubulin reveal that RPC2 acts to promote tubulin polymerization and when imaged by electron microscopy, these microtubules look normal in appearance. Isothermal titration calorimetry measurements show an associative binding constant of 4.8 × 10⁶ M^-1 for RPC2 to preformed microtubules and support a 1 : 1 RPC2 to tubulin dimer stoichiometry. Competition experiments show RPC2 does not compete for the taxane binding site. Consistent with this tight binding, over 80% of the ruthenium in treated cells is co-localized with the cytoskeletal proteins. These data support RPC2 acting as an in vivo microtubule stabilizing agent and sharing many similarities with cells treated with paclitaxel.

Flow Cytometry Reveals the Nature of Oncotic Cells

The term necrosis is commonly applied to cells that have died via a non-specific pathway or mechanism but strictly is the description of the degradation processes involved once the plasma membrane of the cell has lost integrity. The signalling pathways potentially involved in accidental cell death (ACD) or oncosis are under-studied. In this study, the flow cytometric analysis of the intracellular antigens involved in regulated cell death (RCD) revealed the phenotypic nature of cells undergoing oncosis or necrosis. Sodium azide induced oncosis but also classic apoptosis, which was blocked by zVAD (z-Vla-Ala-Asp(OMe)-fluoromethylketone). Oncotic cells were found to be viability^+ve/caspase-3^–ve/RIP3^+ve/–ve (Receptor-interacting serine/threonine protein kinase 3). These two cell populations also displayed a DNA damage response (DDR) phenotype pH2AX^+ve/PARP^–ve, cleaved PARP induced caspase independent apoptosis H2AX^–ve/PARP^+ve and hyper-activation or parthanatos H2AX^+ve/PARP^+ve. Oncotic cells with phenotype cell viability^+ve/RIP3^–ve/caspase-3^–ve showed increased DDR and parthanatos. Necrostatin-1 down-regulated DDR in oncotic cells and increased sodium azide induced apoptosis. This flow cytometric approach to cell death research highlights the link between ACD and the RCD processes of programmed apoptosis and necrosis.

New insights into cell cycle and DNA damage response machineries through high-resolution AMICO quantitative imaging cytometry

OBJECTIVE

Progress in biology and medicine research is being driven by development of new instrumentation and associated methodologies which open analytical capabilities that expand understanding of complexity of biological systems. Application of cytometry, which is now widely used in so many disciplines of biology, is the best example of such a progress.

METHODOLOGY

Recent publications push the envelope in expanding capabilities of cytometry by introducing a high resolution imaging cytometry defined as Automated Microscopy for Image CytOmetry (AMICO). This instrumentation is utilized to further elucidate mechanisms of the cell cycle progression and also the DNA damage response. This approach is going beyond the presently possible analytical technologies regarding throughput and depth of information.

CONCLUSIONS

The possibility of multiparametric analysis combined with the high resolution mapping of individual constituents of cell cycle and DNA damage response machineries provides new tools to probe molecular mechanism of these processes. The capability of analysis of proximity of these constituents to each other offered by AMICO is a novel and potentially important approach that can be used to elucidate mechanisms of other biological processes.

Measurement of cell death in mammalian cells

This unit presents methods used to assess cell death in mammalian cells. The unit is divided into five sections: (1) a brief overview of cytotoxicity and pathways of cell death, (2) an improved method to measure cell death using lactate dehydrogenase (LDH) release as a marker of membrane integrity, (3) a flow cytometry method that simultaneously measures two types of cell death, oncosis and apoptosis, (4) use of nuclear morphology to assess apoptosis and oncosis, and (5) a brief discussion of the use of cytotoxicity assays to determine the mechanisms of cell death.