Cytometric methods to detect apoptosis

In Vitro Liver Toxicity Testing of Chemicals: A Pragmatic Approach

The liver is among the most frequently targeted organs by noxious chemicals of diverse nature. Liver toxicity testing using laboratory animals not only raises serious ethical questions, but is also rather poorly predictive of human safety towards chemicals. Increasing attention is, therefore, being paid to the development of non-animal and human-based testing schemes, which rely to a great extent on in vitro methodology. The present paper proposes a rationalized tiered in vitro testing strategy to detect liver toxicity triggered by chemicals, in which the first tier is focused on assessing general cytotoxicity, while the second tier is aimed at identifying liver-specific toxicity as such. A state-of-the-art overview is provided of the most commonly used in vitro assays that can be used in both tiers. Advantages and disadvantages of each assay as well as overall practical considerations are discussed.

Functional analysis of down-regulated miRNA-221-5p in HeLa cell treated with polyphenol-rich Polyalthia longifolia as regulators of apoptotic HeLa cell death

MicroRNAs are endogenous small non-coding-RNAs that control gene expression and cancer development. Previous studies reported that Polyalthia longifolia treatment induced apoptotic cell death in HeLa cells by down-regulation of miR-221-5p. Hence, the current study was conducted to validate the down-regulated miR-221-5p in HeLa cells. Functional analysis of miR-221-5p was conducted through the gain-of-function, and loss-of-function approach and the miRNA expression was quantified by a real-time polymerase chain reaction. The P. longifolia treatment significantly (p < 0.05) reduced miR-221-5p expression when compared to the untreated HeLa cells with a double delta Ct value of 6.32 and the expression fold change value was reduced up to 0.013. The transfection of miR-221-5p mimic significantly increased the expression of miR-221-5p with an expression fold change as high as 0.53 while anti-miR-221-5p transfected HeLa cells show the most significant decrease in miR-221-5p expression with an expression fold change of 0.011. The MTT assay results revealed that the over-expression of miR-221-5p increased the cell proliferation and viability of polyphenol-rich P. longifolia-treated HeLa cells and confirmed the role of downregulated miRNA 221-5p in HeLa cell death. The flow-cytometry analysis showed that the miR-221-5p over-expressed cells decreased the apoptosis of cells induced by polyphenol-rich P. longifolia treatment in HeLa cells, which proved the oncogenic role of miR-221-5p to inhibit apoptosis. Moreover, the depletion of caspase-3 in miR-221-5p-overexpressed HeLa cells showed the roles of downregulated miR-221-5p in the induction of apoptosis. In conclusion, these results suggest that the down-regulated miR-221-5p was involved in regulating apoptosis in HeLa cancer cells.

Different responses of colorectal cancer cells to alternative sequences of cetuximab and oxaliplatin

Therapeutic protocols including EGFR antibodies in the context of oxaliplatin-based regimens have variable clinical effect in colorectal cancer. Here, we tested the effect of the EGFR antibody cetuximab in different sequential combinations with oxaliplatin on the growth of colorectal cancer cells in vitro and in vivo. Cetuximab reduced the efficacy of oxaliplatin when administered before oxaliplatin but provided additive effect when administered after oxaliplatin regardless of the KRAS or BRAF mutation status of the cells. Systemic gene expression and protein phosphorylation screens revealed alternatively activated pathways regulating apoptosis, cell cycle and DNA damage response. Functional assays indicated that cetuximab-induced arrest of the cells into the G1 phase of the cell cycle was associated with reduced responsiveness of the cells to subsequent treatment with oxaliplatin. In contrast, oxaliplatin-enhanced responsiveness to subsequent treatment with cetuximab was associated with increased apoptosis, inhibition of STAT3 activity and increased EGFR down-regulation. This preclinical study indicates that optimizing the sequence of administration may enhance the antitumor effect of combination therapy with EGFR antibodies and oxaliplatin.

Novel pregnenolone derivatives modulate apoptosis via Bcl-2 family genes in hepatocellular carcinoma in vitro

A series of pregnenolone derivatives were synthesized and assessed for anti-cancer activity against hepatocellular carcinoma cell line (HepG2). The synthesized hetero-steroids (compounds 3, 4, 5, 6, 7, 8a and 8b) were evaluated for their cytotoxic activities using MTT (3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide) assay. Apoptotic activity was assessed using dual acridine orange/ethidium bromide staining method and DNA fragmentation assay. Pro-apoptotic genes (Bax and Bak) and anti-apoptotic genes (Bcl-2 and Bcl-xL) were analyzed using quantitative real time PCR. The results revealed that compounds 4 and 6 displayed cytotoxic activity (IC_50s, 36.97 ± 2.18 and 18.46 ± 0.64 μM, respectively), while compounds 5 and 7 exhibited weak cytotoxic activity (IC_50s, 93.87 ± 8.30 μM and 93.48 ± 4.14 μM, respectively). All synthesized heterocyclic pregnenolone derivatives induced apoptosis through DNA fragmentation. Compounds 4 and 6 increased early and late apoptotic cell percentages while compounds 3, 5, 7 and 8b increased either early or late apoptotic cell percentage. Moreover, compounds 3, 6 and 8b up-regulated the expression level of Bak gene. On the other hand, compounds 4, 5, 7 and 8a down-regulated the Bcl-2 expression level, besides, compounds 5, 7 and 8a down-regulated the Bcl-xL expression level. Compounds 5, 7, 8a and 8b increased the Bak/Bcl-xL ratio, besides, compound 8a raised the Bax/Bcl-xL ratio whereas compound 5 elevated Bax/Bcl-2 and Bak/Bcl-2 ratios. The present work introduced novel pro-apoptotic pregnenolone derivatives that acted against HepG2 cells through DNA fragmentation, apoptotic morphological changes and were able to increase the pro-apoptotic/anti-apoptotic ratios of Bcl-2 family genes. This study particularly revealed that the cytotoxic compound 4 is the most promising pro-apoptotic compound among other synthesized derivatives where it induced apoptosis (late and early) through the down-regulation of Bcl-2 gene expression level.

Juglans regia L. protects against UVB induced apoptosis in human epidermal keratinocytes

The present study was aimed to investigate the photoprotective effect of the male flower of J. regia L. (MEJR) against ultraviolet-B induced apoptosis in human skin cells. Human skin epidermal keratinocytes were pretreated with the MEJR (80 µg/ml, has been selected after MTT assay), prior to 30 min UVB-irradiation at a dose of 20 mJ/cm². Mitochondrial membrane potential was evaluated using Rhodamine-123 staining; the % apoptosis by Hoechst staining and acridine orange staining; DNA damage was measured by comet assay. The levels of p53, Bax, Bcl-xL, Bcl-2, Cytochrome c, Caspase-9 and Caspase-3 expression in HaCaT cells were analyzed by western blotting and RT-PCR. Pretreatment with MEJR 80 µg/ml prior to UVB-irradiation significantly prevents apoptotic characteristics, DNA damage and loss of mitochondrial membrane potential. Thus, MEJR protects UVB-mediated human skin cells, by modulating the expression of apoptotic markers and UVB-induced DNA damage in HaCaT cells.

The death pathways in mussel larval cells after a freeze-thaw cycle

We analyzed cell viability, caspase activity, plasma membrane alterations and cell ultrastructure morphology to estimate the morphological and biochemical alterations that occur in bivalve molluscan cell cultures during cryopreservation. The use of 5% dymethyl sulfoxide as a cryoprotectant resulted in greater cell survival and a scarcity of destroyed cells lacking cytosol among dead cells. In this case, almost all cells died through necrosis or apoptosis, which appeared to increase in mussel cell cultures after a freeze-thaw cycle. Apoptosis was not a main death pathway in mussel cells, but it was induced in a significant part of these cells (up to 24%) immediately after thawing and depended mostly on the cryoprotectant used. Regardless of the type of the used cryoprotectant, we observed some nuclear aberrations in cells after freezing-thawing, such as few multipolar mitoses or the absence of a division spindle in mitotic cells. After analyzing different methods for assessing cell damage, the best results were obtained from optimal approaches that could provide information regarding the cell disruption level after freezing-thawing and could be considered for future studies.

Esters and amides of maslinic acid trigger apoptosis in human tumor cells and alter their mode of action with respect to the substitution pattern at C-28

Cancer is one of the most commonly diagnosed diseases worldwide; its mortality rate is high, and there is still a demand for the development of antitumor active drugs. Triterpenoic acids show many pharmacological effects, among them antitumor activity. One of these, maslinic acid-1 is of interest because of its antitumor profile. It is not only cytotoxic but also triggers apoptosis in various human tumor cell lines. To improve the cytotoxicity of parent 1 we set out to synthesize a series of esters and amides differing in structure and lipophilicity. These compounds were tested in a sulforhodamine B assay for cytotoxicity, and screened for their ability to induce apoptosis using an acridine orange/propidium iodide assay, DNA laddering and cell cycle experiments. Esters containing small-chain, lipophilic residues increased the cytotoxicity whereas amides as well long-chain esters led to a decrease in activity. The antitumor activity seems to be independent from the substitution pattern at position C-28 for esters and amides but alters their mode of action.

Induction of apoptosis in human myeloid leukemia cells by remote exposure of resistive barrier cold plasma

Cold atmospheric plasma (CAP), an ambient temperature ionized gas, is gaining extensive interest as a promising addition to anti-tumor therapy primarily due to the ability to generate and control delivery of electrons, ions, excited molecules, UV photons, and reactive species such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) to a specific site. The heterogeneous composition of CAP offers the opportunity to mediate several signaling pathways that regulate tumor cells. Consequently, the array of CAP generated products has limited the identification of the mechanisms of action on tumor cells. The aim of this work is to assess the cell death response of human myeloid leukemia cells by remote exposure to CAP generated RNS by utilizing a novel resistive barrier discharge system that primarily produces RNS. The effect of variable treatments of CAP generated RNS was tested in THP-1 cell (human monocytic leukemia cell line), a model for hematological malignancy. The number of viable cells was evaluated with erythrosine-B staining, while apoptosis and necrosis was assessed by endonuclease cleavage observed by agarose gel electrophoresis and detection of cells with the exclusionary dye propidium iodide and fluorescently labeled annexin-V by flow cytometry and fluorescent microscopy. Our observations indicate that treatment dosage levels of 45 s of exposure to CAP emitted RNS-induced apoptotic cell death and for higher dosage conditions of ≥50 s of exposure to CAP induced necrosis. Overall the results suggest that CAP emitted RNS play a significant role in the anti-tumor potential of CAP.

Apoptosis and beyond: cytometry in studies of programmed cell death

A cell undergoing apoptosis demonstrates multitude of characteristic morphological and biochemical features, which vary depending on the inducer of apoptosis, cell type and the "time window" at which the process of apoptosis is observed. Because the gross majority of apoptotic hallmarks can be revealed by flow and image cytometry, the cytometric methods become a technology of choice in diverse studies of cellular demise. Variety of cytometric methods designed to identify apoptotic cells, detect particular events of apoptosis and probe mechanisms associated with this mode of cell death have been developed during the past two decades. In the present review, we outline commonly used methods that are based on the assessment of mitochondrial transmembrane potential, activation of caspases, DNA fragmentation, and plasma membrane alterations. We also present novel developments in the field such as the use of cyanine SYTO and TO-PRO family of probes. Strategies of selecting the optimal multiparameter approaches, as well as potential difficulties in the experimental procedures, are thoroughly summarized.

Acetonic extract of Buxus sempervirens induces cell cycle arrest, apoptosis and autophagy in breast cancer cells

Plants are an invaluable source of potential new anti-cancer drugs. Here, we investigated the cytotoxic activity of the acetonic extract of Buxus sempervirens on five breast cancer cell lines, MCF7, MCF10CA1a and T47D, three aggressive triple positive breast cancer cell lines, and BT-20 and MDA-MB-435, which are triple negative breast cancer cell lines. As a control, MCF10A, a spontaneously immortalized but non-tumoral cell line has been used. The acetonic extract of Buxus sempervirens showed cytotoxic activity towards all the five studied breast cancer cell lines with an IC(50) ranging from 7.74 µg/ml to 12.5 µg/ml. Most importantly, the plant extract was less toxic towards MCF10A with an IC(50) of 19.24 µg/ml. Fluorescence-activated cell sorting (FACS) analysis showed that the plant extract induced cell death and cell cycle arrest in G0/G1 phase in MCF7, T47D, MCF10CA1a and BT-20 cell lines, concomitant to cyclin D1 downregulation. Application of MCF7 and MCF10CA1a respective IC(50) did not show such effects on the control cell line MCF10A. Propidium iodide/Annexin V double staining revealed a pre-apoptotic cell population with extract-treated MCF10CA1a, T47D and BT-20 cells. Transmission electron microscopy analyses indicated the occurrence of autophagy in MCF7 and MCF10CA1a cell lines. Immunofluorescence and Western blot assays confirmed the processing of microtubule-associated protein LC3 in the treated cancer cells. Moreover, we have demonstrated the upregulation of Beclin-1 in these cell lines and downregulation of Survivin and p21. Also, Caspase-3 detection in treated BT-20 and T47D confirmed the occurrence of apoptosis in these cells. Our findings indicate that Buxus sempervirens extract exhibit promising anti-cancer activity by triggering both autophagic cell death and apoptosis, suggesting that this plant may contain potential anti-cancer agents for single or combinatory cancer therapy against breast cancer.

Leveraging image cytometry for the development of clinically feasible biomarkers: evaluation of activated caspase-3 in fine needle aspirate biopsies

Quantitation of activated caspases in xenograft models by laser scanning cytometry has demonstrated mechanism-specific biological activity of Anti-Trail Receptor immunoglobulin therapies in situ. These preclinical data confirmed that caspase activation is an early event that precedes tumor regression. To apply this platform for clinical monitoring of caspase activation using fine needle aspirate (FNA) biopsies, additional assay feasibility and validation experiments need be addressed. Furthermore, important instrument parameters should be considered including the maintenance and operation of the cytometer in a controlled state to ensure aspects like data traceability, reliability, and integrity. In the present chapter we describe a method to evaluate caspase activation in Colo205 cells and fine needle aspirate tumors by slide-based, laser scanning cytometry. This approach can be applied to cell cultures, preclinical and clinical fine needle aspirate material.

Analytical capabilities of the ImageStream cytometer

Imaging cytometry has recently become an important achievement in development of flow cytometric technologies. The ImageStream cytometer combines the vast features of classical flow cytometry including an impartial analysis of great number of cells in short period of time which results in strong statistical data output, with essential features of fluorescence microscopy such us collecting of real multiparameter images of analyzed objects. In this chapter, we would like to introduce an overview of imaging cytometry platform and emphasize the potential advantages of using this system for several experimental purposes. Moreover, both well established as well as potential applications of imaging cytometry will be described. Eventually, we would like to illustrate the unique use of ImageStream cytometer for identification and characterization of subpopulations of stem/ progenitor cells present in different biological specimens.

Rapid quantification of cell viability and apoptosis in B-cell lymphoma cultures using cyanine SYTO probes

The gross majority of classical apoptotic hallmarks can be rapidly examined by multiparameter flow cytometry. As a result, cytometry became a technology of choice in diverse studies of cellular demise. In this context, a novel class of substituted unsymmetrical cyanine SYTO probes has recently become commercially available. Derived from thiazole orange, SYTO display low intrinsic fluorescence, with strong enhancement upon binding to DNA and/or RNA. Broad selection of excitation/emission spectra has recently driven implementation of SYTO dyes in polychromatic protocols with the detection of apoptosis being one of the most prominent applications In this chapter, we outline a handful of commonly used protocols for the assessment of apoptotic events using selected SYTO probes (SYTO 16, 62, 80) in conjunction with common plasma membrane permeability markers (PI, YO-PRO 1, 7-AAD).

Pre-treatment of cells with pluronic L64 increases DNA transfection mediated by electrotransfer

Gene transfer into muscle cells is a key issue in biomedical research. Indeed, it is important for the development of new therapy for many genetic disorders affecting this tissue and for the use of muscle tissue as a secretion platform of therapeutic proteins. Electrotransfer is a promising method to achieve gene expression in muscles. However, this method can lead to some tissue damage especially on pathologic muscles. Therefore there is a need for the development of new and less deleterious methods. Triblock copolymers as pluronic L64 are starting to be used to improve gene transfer mediated by several agents into muscle tissue. Their mechanism of action is still under investigation. The combination of electrotransfer and triblock copolymers, in allowing softening electric field conditions leading to efficient DNA transfection, could potentially represent a milder and more secure transfection method. In the present study, we addressed the possible synergy that could be obtained by combining the copolymer triblock L64 and electroporation. We have found that a pre-treatment of cells with L64 could improve the transfection efficiency. This pre-treatment was shown to increase cell viability and this is partly responsible for the improvement of transfection efficiency. We have then labelled the plasmid DNA and the pluronic L64 in order to gain some insights into the mechanism of transfection of the combined physical and chemical methods. These experiences allowed us to exclude an action of L64 either on membrane permeabilization or on DNA/membrane interaction. Using plasmids containing or not binding sequences for NF-κB and an inhibitor of NF-κB pathway activation we have shown that this beneficial effect was rather related to the NF-κB signalling pathway, as it is described for other pluronics. Finally we address here some mechanistic issues on electrically mediated transfection, L64 mediated membrane permeabilization and the combination of both for gene transfer.

Cytometry in cell necrobiology revisited. Recent advances and new vistas

Over a decade has passed since publication of the last review on "Cytometry in cell necrobiology." During these years we have witnessed many substantial developments in the field of cell necrobiology such as remarkable advancements in cytometric technologies and improvements in analytical biochemistry. The latest innovative platforms such as laser scanning cytometry, multispectral imaging cytometry, spectroscopic cytometry, and microfluidic Lab-on-a-Chip solutions rapidly emerge as highly advantageous tools in cell necrobiology studies. Furthermore, we have recently gained substantial knowledge on alternative cell demise modes such as caspase-independent apoptosis-like programmed cell death (PCD), autophagy, necrosis-like PCD, or mitotic catastrophe, all with profound connotations to pathogenesis and treatment. Although detection of classical, caspase-dependent apoptosis is still the major ground for the advancement of cytometric techniques, there is an increasing demand for novel analytical tools to rapidly quantify noncanonical modes of cell death. This review highlights the key developments warranting a renaissance and evolution of cytometric techniques in the field of cell necrobiology.

Stanniocalcin-1 suppresses superoxide generation in macrophages through induction of mitochondrial UCP2

Mammalian STC1 decreases the mobility of macrophages and diminishes their response to chemokines. In the current experiments, we sought to determine the impact of STC1 on energy metabolism and superoxide generation in mouse macrophages. STC1 decreases ATP level in macrophages but does not affect the activity of respiratory chain complexes I-IV. STC1 induces the expression of mitochondrial UCP2, diminishing mitochondrial membrane potential and superoxide generation; studies in UCP2 null and gp91phox null macrophages suggest that suppression of superoxide by STC1 is UCP2-dependent yet is gp91phox-independent. Furthermore, STC1 blunts the effects of LPS on superoxide generation in macrophages. Exogenous STC1 is internalized by macrophages within 10 min and localizes to the mitochondria, suggesting a role for circulating and/or tissue-derived STC1 in regulating macrophage function. STC1 induces arrest of the cell cycle at the G1 phase and reduces cell necrosis and apoptosis in serum-starved macrophages. Our data identify STC1 as a key regulator of superoxide generation in macrophages and suggest that STC1 may profoundly affect the immune/inflammatory response.

Apoptosis and haemorrhagic shock

Abstract

This is a review paper that provides an overview of current information on programmed cell death in haemorrhagic shock, including the identification of different molecular receptor signals. A PubMed search for all dates was undertaken using the search terms apoptosis, trauma and haemorrhagic shock. Original research, sentinel and review papers from peer-reviewed journals were included for identification of key concepts. Haemorrhagic shock remains a primary cause of death in civilian and military trauma. Apoptosis is accelerated following haemorrhagic shock. Many methods are used to detect and quantify apoptosis. Fluid resuscitation regimens vary in their effect on the extent of apoptosis. Investigators are examining the effects of haemorrhagic shock and fluid resuscitation on apoptotic signalling pathways. Molecular information is becoming available and being applied to the care of patients experiencing haemorrhagic shock, making it essential for nurses and other health care providers to consider the mechanisms and consequences of apoptosis.

Flow cytometry-based apoptosis detection

An apoptosing cell demonstrates multitude of characteristic morphological and biochemical features, which vary depending on the stimuli and the cell type. The gross majority of classical apoptotic hallmarks can be rapidly examined by flow and image cytometry. Cytometry thus became a technology of choice in diverse studies of cellular demise. A large variety of cytometric methods designed to identify apoptotic cells and probe mechanisms associated with this mode of cell demise have been developed during the past two decades. In the present chapter, we outline a handful of commonly used methods that are based on the assessment of: mitochondrial transmembrane potential, activation of caspases, plasma membrane alterations and DNA fragmentation.

Multiparameter detection of apoptosis using red-excitable SYTO probes

Functional assays allowing phenotypic characterization of different cell death parameters at a single-cell level are important tools for preclinical anticancer drug screening. Currently, the selection of cytometric assays is limited by the availability of fluorescent probes with overlapping spectral characteristics. Following on our earlier reports on green and orange fluorescent SYTO probes, we provide herein further insights into applicability of novel red-excitable SYTO stains (SYTO 17, 59-64) for multiparameter analysis of cell fate. In particular, SYTO 62 appears to be a spectrally favorable candidate. Using a correlative comparison between SYTO 16, Annexin V, YO-PRO 1, and fluorescently labeled inhibitors of caspases (FLICA), we demonstrate the specificity of SYTO 62 in detection of apoptotic cell death. Used in conjunction with FLICA or Annexin V, SYTO 62 stain proved amenable for multivariate kinetic analysis of apoptotic events. Considering simplicity of staining protocols, low cost, and avoidance of spectral compensation problems, we expect that red-excitable SYTO dyes will find a wide range of cytometric applications.

Intravesical chemotherapy of high-grade bladder cancer with HTI-286, a synthetic analogue of the marine sponge product hemiasterlin

PURPOSE

HTI-286 is a fully synthetic analogue of the natural tripeptide hemiasterlin that inhibits tubulin polymerization and has strong cytotoxic potential. In this study, we evaluate the inhibitory effects of HTI-286 on human bladder cancer growth, both in vitro and as an intravesical agent in an orthotopic murine model.

EXPERIMENTAL DESIGN

Various bladder cancer cell lines were treated with HTI-286 and mitomycin C (MMC) in vitro. Human KU-7 bladder tumor cells that stably express firefly luciferase were inoculated in female nude mice by intravesical instillation and quantified using bioluminescence imaging. Mice with established KU-7-luc tumors were given HTI-286 or MMC intravesically twice a week for 2 h. Pharmacokinetic data was obtained using high-performance liquid chromatography-mass spectrometry analyses.

RESULTS

In vitro, HTI-286 was a potent inhibitor of proliferation in all tested cell lines and induced marked increases in apoptosis of KU-7-luc cells even after brief exposure. In vivo, HTI-286 significantly delayed cancer growth of bladder tumors in a dose-dependent fashion. HTI-286, at a concentration of 0.2 mg/mL, had comparable strong cytotoxicity as 2.0 mg/mL of MMC. The estimated systemic bioavailability of intravesically given HTI-286 was 1.5% to 2.1% of the initial dose.

CONCLUSIONS

Intravesical HTI-286 instillation therapy showed promising antitumor activity and minimal toxicity in an orthotopic mouse model of high-grade bladder cancer. These findings provide preclinical proof-of-principle for HTI-286 as an intravesical therapy for nonmuscle-invasive bladder cancer and warrant further evaluation of efficacy and safety in early-phase clinical trials.

Targeting prostate cancer with HTI-286, a synthetic analog of the marine sponge product hemiasterlin

Therapeutic resistance is the underlying cause for most cancer deaths and a major problem associated with treatment of metastatic prostate cancer. HTI-286, a fully synthetic analog of the natural tripeptide hemiasterlin, inhibits tubulin polymerization and circumvents transport-based resistance to taxanes. In our study, we evaluated its inhibitory effects on human prostate cancer growth in vitro and in different in vivo models. Androgen-dependent and androgen-independent prostate cancer cell lines including a docetaxel-refractory PC-3 subline (PC-3dR) were treated with HTI-286. Transcriptional profiling was carried out to screen for changes in gene expression induced by HTI-286 and compared to docetaxel. In vivo, nude mice with established PC-3 or PC-3dR xenografts were given HTI-286 intravenously. Additionally, mice bearing hormone-sensitive LNCaP tumors were treated with castration in combination with early or delayed HTI-286 therapy. In all cell lines tested, HTI-286 was a potent inhibitor of proliferation and induced marked increases in apoptosis. Despite similar transcriptomic changes regarding cell death and cell cycle regulating genes after exposure to HTI-286 or docetaxel, array analysis revealed distinct molecular signatures for both compounds. Invivo, HTI-286 significantly inhibited growth of PC-3 and LNCaP xenografts and retained potency in PC-3dR tumors. Simultaneous castration plus HTI-286 therapy was superior to sequential treatment in the LNCaP model. In conclusion, HTI-286 showed strong antitumor activity both in androgen-dependent and androgen- independent tumors and may be a promising agent in second- line treatment strategies for patients suffering from docetaxel- refractory prostate cancer.

Live-cell assay for detection of apoptosis by dual-laser flow cytometry using Hoechst 33342 and 7-amino-actinomycin D

This protocol describes a rapid and simple method for the identification of apoptotic cells. Owing to changes in membrane permeability, early apoptotic cells show an increased uptake of the vital DNA dye Hoechst 33342 (HO342) compared with live cells. The nonvital DNA dye 7-amino-actinomycin D (7-AAD) is added to distinguish late apoptotic or necrotic cells that have lost membrane integrity from early apoptotic cells that still have intact membranes as assayed by dye exclusion. The method is suitable to be combined with cell surface staining using Abs of interest labeled with fluorochromes that are compatible with HO342 and 7-AAD emissions. Surface antigen staining is carried out according to standard methods before staining for apoptosis. The basic assay can be completed in 30 min, and extra time is needed for cell surface antigen staining.

Induction of cell cycle changes and modulation of apoptogenic/anti-apoptotic and extracellular signaling regulatory protein expression by water extracts of I'm-Yunity (PSP)

Background

I'm-Yunity™ (PSP) is a mushroom extract derived from deep-layer cultivated mycelia of the patented Cov-1 strain of Coriolus versicolor (CV), which contains as its main bioactive ingredient a family of polysaccharo-peptide with heterogeneous charge properties and molecular sizes. I'm-Yunity™ (PSP) is used as a dietary supplement by cancer patients and by individuals diagnosed with various chronic diseases. Laboratory studies have shown that I'm-Yunity™ (PSP) enhances immune functions and also modulates cellular responses to external challenges. Recently, I'm-Yunity™ (PSP) was also reported to exert potent anti-tumorigenic effects, evident by suppression of cell proliferation and induction of apoptosis in malignant cells. We investigate the mechanisms by which I'm-Yunity™ (PSP) elicits these effects.

Methods

Human leukemia HL-60 and U-937 cells were incubated with increasing doses of aqueous extracts of I'm-Yunity™ (PSP). Control and treated cells were harvested at various times and analyzed for changes in: (1) cell proliferation and viability, (2) cell cycle phase transition, (3) induction of apoptosis, (4) expression of cell cycle, apoptogenic/anti-apoptotic, and extracellular regulatory proteins.

Results

Aqueous extracts of I'm-Yunity™ (PSP) inhibited cell proliferation and induced apoptosis in HL-60 and U-937 cells, accompanied by a cell type-dependent disruption of the G₁/S and G₂/M phases of cell cycle progression. A more pronounced growth suppression was observed in treated HL-60 cells, which was correlated with time- and dose-dependent down regulation of the retinoblastoma protein Rb, diminution in the expression of anti-apoptotic proteins bcl-2 and survivin, increase in apoptogenic proteins bax and cytochrome c, and cleavage of poly(ADP-ribose) polymerase (PARP) from its native 112-kDa form to the 89-kDa truncated product. Moreover, I'm-Yunity™ (PSP)-treated HL-60 cells also showed a substantial decrease in p65 and to a lesser degree p50 forms of transcription factor NF-κB, which was accompanied by a reduction in the expression of cyclooxygenase 2 (COX2). I'm-Yunity™ (PSP) also elicited an increase in STAT1 (signal transducer and activator of transcription) and correspondingly, decrease in the expression of activated form of ERK (extracellular signal-regulated kinase).

Conclusion

Aqueous extracts of I'm-Yunity™ (PSP) induces cell cycle arrest and alterations in the expression of apoptogenic/anti-apoptotic and extracellular signaling regulatory proteins in human leukemia cells, the net result being suppression of proliferation and increase in apoptosis. These findings may contribute to the reported clinical and overall health effects of I'm-Yunity™ (PSP).

Measurement of two caspase activities simultaneously in living cells by a novel dual FRET fluorescent indicator probe

BACKGROUND

A number of fluorescent caspase substrates and FRET-based indicators have been developed to study the in vivo activation of caspases, a conserved family of proteases critical in inflammatory, and apoptosis signaling pathways. To date, all substrates have measured only one caspase activity. Here, we describe a FRET-based probe for simultaneously measuring two distinct caspase activities in living cells.

METHODS

This probe consists of a CFP-YFP-mRFP fusion protein containing a caspase-3-cleavage motif, DEVD, between CFP and YFP, and a caspase-6-cleavage site, VEID, between YFP and mRFP. DEVDase and VEIDase activities could be assessed simultaneously by monitoring diminished FRET mediated by cleavage of either or both of these protease cleavage sites using flow cytometry.

RESULTS

DEVDase and VEIDase activities were completely inhibited by the pan-caspase inhibitor z-VAD-fmk and enhanced by DNA-damaging drugs or by anti-Fas stimulation. DEVD and VEID cleavage specificities were validated by using caspase-3-deficient MCF7-Fas cells and a caspase-6-specific inhibitor. Kinetic analysis with the FRET probe revealed that caspase-3 activation consistently preceded caspase-6 by approximately 30 min following induction of apoptosis.

CONCLUSIONS

We have developed a novel FRET-based probe for simultaneous detection of two caspase activities in living cells using flow cytometry. Simultaneous detection of two caspase activities using this probe has clearly provided information of the ordering of caspase-3 and -6 in the apoptotic pathway.

Cell cycle dependent apoptosis and cell cycle blocks induced by hyperthermia in HL-60 cells

The effects of heat are strongly dependent on the time of heating at a given temperature. The relationship between treatment time and temperature for a biological isoeffect (the Arrhenius plot) has been confirmed for a variety of normal tissues and tumours. A marked change of slope occurs somewhere between 42-43 degrees C. Above this transition temperature the slope is constant for a variety of cells and tissues. Therefore, when defining thermal doses in hyperthermia studies, both the time and temperature of heating are equally important determinants. In this study, cell cycle progression and apoptosis were analysed in HL-60 cells after heating from 5-60 min at 45.0 degrees C and also heating with five different iso-dose time-temperature heat treatments. A heat shock of 5-15 min at 45.0 degrees C caused the accumulation of cells in G1 and G2/M phases after 12 h at 37 degrees C, whereas a heat shock of 20-60 min at 45.0 degrees C reduced the number of non-apoptotic cells in all phases because the number of apoptotic cells increased. The fraction of apoptotic cells followed a sigmoid curve as the heating time increased from 5-60 min at 45.0 degrees C. Cell cycle analysis showed that apoptosis occurred predominantly in S-phase cells for shorter heating times but in all phases at longer times. An isodose heat shock lower than 44.0 degrees C (42.0-43.0 degrees C) gave the same apoptotic index, while heat shock from 44.0-46.0 degrees C caused a greater than expected apoptotic index. Thus, there was a transition at 44.0 degrees C in HL-60 cells, above which apoptosis increased rapidly. These results indicate that isodose analysis based on clonogenic survival in fibroblast cells may not be relevant for cell types which readily undergo apoptosis. Clonogenic survival was also compared with apoptosis for HL-60 cells and an apoptotic-resistant derivative cell line, HWC-2, heated for various times at 45.0 degrees C. Survival based on a clonogenic assay was much lower than survival based only on apoptotic index at all times for HL-60 cells. HWC-2 cells did not undergo apoptosis and also had a higher clonogenic survival than HL-60 cells.

Remission induction chemotherapy induces in vivo caspase-dependent apoptosis in bone marrow acute myeloid leukemia blast cells and spares lymphocytes

BACKGROUND

The goal of new therapeutic strategies is to adapt the treatment of acute myeloid leukemia (AML) patients to the prognostic and/or to the hematological response.

METHODS

We analyzed in vivo apoptosis induction in blast cells and in lymphocytes of AML patients receiving remission induction treatment.

RESULTS

We show, on 12 peripheral blood samples, that the increase of peripheral apoptotic blast cells cannot be considered as the earliest marker of the treatment efficiency, because the significant increase of apoptosis followed the white blood cell and the peripheral blast cell count reductions, probably due to an efficient clearance of circulating apoptotic cells. Furthermore, the study of 65 bone marrow samples at d15 showed that the treatment induced apoptosis of blast cells while sparing the lymphocytes. This apoptosis was evidenced both at the caspase and at the membrane levels using respectively fmk-VAD-FITC and Annexin V binding assays. We found that less than 50% of apoptosis, measured with the fmk-VAD-FITC, in the d15 residual bone marrow blast cells, correlated with lower disease-free survival probability.

CONCLUSION

More studies are needed in larger series and earlier during the remission induction treatment to confirm the possible prognostic significance of in vivo apoptosis induction.