Development of fluorescent dual-FRET probe for simultaneous detection of caspase-8 and caspase-9 activities and their relative quantification.

A multi-FRET three-fluorophore probe containing coumarin, fluorescein and rhodamine B with two enzymatically cleavable linkers has been synthesized and optimized for the simultaneous activity detection and relative quantification of two proteases - caspase-8 and caspase-9. The probe designed as a ratiometric single-excitation triple-emission system shows specific change in fluorescence intensities upon enzymatic cleavage of individual linkers in model mixtures as well as in a cell lysate. The activation of caspase-8 and caspase-9 is responsible for initiation of extrinsic or intrinsic apoptotic pathway, respectively, and the probe was proposed as a single chemical tool which could help to decipher a mechanism of cell death induced by various stimuli. The main advantage of this probe is the simplicity of its preparation using conventional organic synthesis, easy application for measurement and evaluation of the results.

Combined Effect of HPV and Several Gene SNPs in Laryngeal Cancer.

Background and objectives: Laryngeal squamous cell carcinoma (LSCC) is one of the most common head and neck tumors. The molecular mechanism of LSCC remains unclear. The aim of this study was to evaluate the prevalence of Human papillomavirus (HPV) and single nucleotide polymorphisms (SNPs) of TP53, MDM2, MDM4, MTHFR, CASP8, and CCR5 genes in LSCC, and to assess their correlations with patient survival. Materials and Methods: 49 LSCC patients were enrolled in this study. PCR and qRT-PCR were used to detect, identify, and quantify HPV. SNPs were genotyped using PCR and PCR-RFLP. Results: By analyzing the interactions of the SNPs of the genes with clinical parameters, the majority of patients with lymph node status (N1,2) were identified as carriers of MDM2 T/G, CASP8 ins/del, CCR5 wt/wt SNP. Cluster analysis showed that patients with MDM2 T/T SNP survive longer than patients identified as CASP8 ins/ins, MTHFR C/C, and MDM4 A/A variant carriers; meanwhile, LSCC patients with MDM2 T/T polymorphic variant had the best survival. Multivariate analysis showed that HPV-positive patients without metastasis in regional lymph nodes (N0) and harboring CASP8 ins/del variant had the best survival. Meanwhile, HPV-negative patients with identified metastasis in lymph nodes (N1 and N2) and CASP8 ins/del variant had poor survival. Conclusions: This finding suggests patients survival prognosis and tumor behavior are different according HPV status, SNP variants, and clinical characteristics of the LSCC.

Enterotoxigenic Escherichia coli infection promotes apoptosis in piglets.

Enterotoxigenic Escherichia coli (ETEC), as a universal pathogen, often causes diarrhea in animals and humans. However, whether ETEC infection induces apoptosis in host remains controversial. Herein, we use ETEC-infected piglet to investigate apoptosis in the jejunum. Apoptosis and the activation of capase-3 are observed in piglet jejunum after ETEC infection. Additionally, ETEC infection induces the activation of caspase-8 pathway, but inhibits the activation of caspase-9 pathway in piglet jejunum. These findings demonstrate that ETEC infection may inhibit the intrinsic pathway and activate the extrinsic pathway of apoptosis in piglets.

Chemical Composition of Aqueous Ethanol Extract of Luffa cylindrica Leaves and Its Effect on Representation of Caspase-8, Caspase-3, and the Proliferation Marker Ki67 in Intrinsic Molecular Subtypes of Breast Cancer in Vitro.

Breast cancer constitutes the second most prevalent cancer in Egypt, the problem needs more trends in treatment and treatment development either by regimen modification or introducing new drugs, and the main objective of this study is to screen the effects of the aqueous ethanol herbal extract of Luffa cylindrica leaves on different types of breast cancer cell lines representing different molecular subtypes of the disease. The major active constituents of the extract were tentatively identified by LC/MS which revealed the presence of phenolic compound derivatives and saponin that may be responsible in part for the activity of the extract. The emphasis was laid on the main apoptotic pathways as well as the extract effect on the normal cell line. Results of phytochemical investigation, cell cycle analysis, and molecular analysis of apoptotic and proliferative markers have shown effective anticancer activity against MCF-7, BT-474, and MDA-MB-231 cell lines which represent three subtypes of breast cancer, luminal A, luminal B, and triple negative, respectively. On the other hand, the effects on normal lung fibroblast cell line are less prominent at the dose used for treating breast cancer cell lines.

Caspase-3 and caspase-8 expression in breast cancer: caspase-3 is associated with survival.

Impaired apoptosis is one of the hallmarks of cancer. Caspase-3 and -8 are key regulators of the apoptotic response and have been shown to interact with the calpain family, a group of cysteine proteases, during tumorigenesis. The current study sought to investigate the prognostic potential of caspase-3 and -8 in breast cancer, as well as the prognostic value of combinatorial caspase and calpain expression. A large cohort (n = 1902) of early stage invasive breast cancer patients was used to explore the expression of caspase-3 and -8. Protein expression was examined using standard immunohistochemistry on tissue microarrays. High caspase-3 expression, but not caspase-8, is significantly associated with adverse breast cancer-specific survival (P = 0.008 and P = 0.056, respectively). Multivariate analysis showed that caspase-3 remained an independent factor when confounding factors were included (hazard ratio (HR) 1.347, 95% confidence interval (CI) 1.086-1.670; P = 0.007). The analyses in individual subgroups demonstrated the significance of caspase-3 expression in clinical outcomes in receptor positive (ER, PR or HER2) subgroups (P = 0.001) and in non-basal like subgroup (P = 0.029). Calpain expression had been previously assessed. Significant association was also found between high caspase-3/high calpain-1 and breast cancer-specific survival in the total patient cohort (P = 0.005) and basal-like subgroup (P = 0.034), as indicated by Kaplan-Meier analysis. Caspase-3 expression is associated with adverse breast cancer-specific survival in breast cancer patients, and provides additional prognostic values in distinct phenotypes. Combinatorial caspase and calpain expression can predict worse prognosis, especially in basal-like phenotypes. The findings warrant further validation studies in independent multi-centre patient cohorts.

Hepatitis B Virus X Protein Reduces Podocyte Adhesion via Downregulation of α3ß1 Integrin.

BACKGROUND/AIMS: Hepatitis B virus (HBV)-associated glomerulonephritis (HBV-GN) is characterized by a reduced number of podocytes due to apoptosis and shedding from the basement membrane. However, the pathological mechanism of HBV-GN is unclear. We previously showed that hepatitis B virus X protein (HBx) promotes apoptosis in tubular epithelial cells. In this study, we transfected podocytes with HBx and examined the effects on adhesion and apoptosis of these cells. METHODS: Podocytes were transfected with pc-DNA3.1 (+)-HBx. One control group was not transfected and another control group was transfected with empty plasmids. Podocyte adhesion was assessed by a fluorescence assay, apoptosis was measured by flow cytometry and fluorescence microscopy, and expression of α3ß1 integrin was determined by western blotting and the reverse transcription polymerase chain reaction (RT-PCR). Activity of caspase-8 was measured by a spectrophotometric assay. RESULTS: Relative to controls, podocytes with pc-DNA3.1(+)-HBx had reduced cell adhesion, increased apoptosis, reduced expression of α3ß1 integrin, and increased caspase-8 activity. ß1 integrin blockage reduced podocyte adhesion, but increased apoptosis and caspase-8 activity. Treatment of transfected podocytes with a caspase-8 inhibitor (Z-IETD-FMK) had no effect on the HBx-mediated integrin downregulation and reduced podocyte adhesion, suggesting that α3ß1 integrin downregulaton is sufficient to alter cell adhesion. CONCLUSIONS: Our in vitro results indicate that HBx reduced podocyte adhesion and expression of α3ß1 integrin, and increased apoptosis. Moreover, HBx-mediated downregulation of α3ß1 integrin expression is sufficient to reduce podocyte adhesion. HBx-induced apoptosis of podocytes may contribute to HBV-GN.

Expression of Fas, FasL, caspase-8 and other factors of the extrinsic apoptotic pathway during the onset of interdigital tissue elimination.

Elimination of the interdigital web is considered to be the classical model for assessing apoptosis. So far, most of the molecules described in the process have been connected to the intrinsic (mitochondrial) pathway. The extrinsic (receptor mediated) apoptotic pathway has been rather neglected, although it is important in development, immunomodulation and cancer therapy. This work aimed to investigate factors of the extrinsic apoptotic machinery during interdigital regression with a focus on three crucial initiators: Fas, Fas ligand and caspase-8. Immunofluorescent analysis of mouse forelimb histological sections revealed abundant expression of these molecules prior to digit separation. Subsequent PCR Array analyses indicated the expression of several markers engaged in the extrinsic pathway. Between embryonic days 11 and 13, statistically significant increases in the expression of Fas and caspase-8 were observed, along with other molecules involved in the extrinsic apoptotic pathway such as Dapk1, Traf3, Tnsf12, Tnfrsf1A and Ripk1. These results demonstrate for the first time the presence of extrinsic apoptotic components in mouse limb development and indicate novel candidates in the molecular network accompanying the regression of interdigital tissue during digitalisation.

Developing Activity Localization Fluorescence Peptide Probe Using Thiol-Ene Click Reaction for Spatially Resolved Imaging of Caspase-8 in Live Cells.

Small molecule probes suitable for high-resolution fluorescence imaging of enzyme activity pose a challenge in chemical biology. We developed a novel design of activity localization fluorescence (ALF) peptide probe, which enables spatially resolved, highly sensitive imaging of peptidase in live cells. The ALF probe was synthesized by a facile thiol-ene click reaction of a cysteine-appended peptide with an acryloylated fluorophore. Upon cleavage by peptidase, the probe undergoes a seven-membered intramolecular cyclization and releases the fluorophore with the excited-state intramolecular photon transfer (ESIPT) effect. A highly fluorescent, insoluble aggregate was formed around the enzyme, which facilitates high-sensitivity and high-resolution imaging. This design is demonstrated for detection of caspase-8 activation. The results show that our design allows easy, high-yield synthesis of the probe, and the probe affords high sensitivity for caspase-8 detection. Live cell imaging reveals that the probe is able to render highly localized and high-contrast fluorescence signal for caspase-8. Our design holds the potential as a generally applicable strategy for developing high-sensitivity and high-resolution imaging peptide probes in cell biology and diagnostics.

Functional analysis of miR-181a and Fas involved in hepatitis B virus-related hepatocellular carcinoma pathogenesis.

The hepatitis B virus (HBV) is responsible for most of hepatocellular carcinoma (HCC). However, whether HBV plays an important role during hepatocarcinogenesis through effecting miRNAs remains unknown. Here, we reported that HBV up-regulated microRNA-181a (miR-181a) by enhancing its promoter activity. Simultaneously, we found that miR-181a inhibited apoptosis in vitro and promoted tumor cell growth in vivo. TNF receptor superfamily member 6 (Fas) was further identified as a target of miR-181a. We also found that Fas could reverse the apoptosis-inhibition effect induced by miR-181a. Moreover, HBV could inhibit cell apoptosis by down-regulating Fas expression, which could be reversed by miR-181a inhibitor. Our data demonstrated that HBV suppressed apoptosis of hepatoma cells by up-regulating miR-181a expression and down-regulating Fas expression, which may provide a new understanding of the mechanism in HBV-related HCC pathogenesis.

Strategy for dual-analyte luciferin imaging: in vivo bioluminescence detection of hydrogen peroxide and caspase activity in a murine model of acute inflammation.

In vivo molecular imaging holds promise for understanding the underlying mechanisms of health, injury, aging, and disease, as it can detect distinct biochemical processes such as enzymatic activity, reactive small-molecule fluxes, or post-translational modifications. Current imaging techniques often detect only a single biochemical process, but, within whole organisms, multiple types of biochemical events contribute to physiological and pathological phenotypes. In this report, we present a general strategy for dual-analyte detection in living animals that employs in situ formation of firefly luciferin from two complementary caged precursors that can be unmasked by different biochemical processes. To establish this approach, we have developed Peroxy Caged Luciferin-2 (PCL-2), a H(2)O(2)-responsive boronic acid probe that releases 6-hydroxy-2-cyanobenzothiazole (HCBT) upon reacting with this reactive oxygen species, as well as a peptide-based probe, z-Ile-Glu-ThrAsp-D-Cys (IETDC), which releases D-cysteine in the presence of active caspase 8. Once released, HCBT and D-cysteine form firefly luciferin in situ, giving rise to a bioluminescent signal if and only if both chemical triggers proceed. This system thus constitutes an AND-type molecular logic gate that reports on the simultaneous presence of H(2)O(2) and caspase 8 activity. Using these probes, chemoselective imaging of either H(2)O(2) or caspase 8 activity was performed in vitro and in vivo. Moreover, concomitant use of PCL-2 and IETDC in vivo establishes a concurrent increase in both H(2)O(2) and caspase 8 activity during acute inflammation in living mice. Taken together, this method offers a potentially powerful new chemical tool for studying simultaneous oxidative stress and inflammation processes in living animals during injury, aging, and disease, as well as a versatile approach for concurrent monitoring of multiple analytes using luciferin-based bioluminescence imaging technologies.

A coupled protein and probe engineering approach for selective inhibition and activity-based probe labeling of the caspases.

Caspases are cysteine proteases that play essential roles in apoptosis and inflammation. Unfortunately, their highly conserved active sites and overlapping substrate specificities make it difficult to use inhibitors or activity-based probes to study the function, activation, localization, and regulation of individual members of this family. Here we describe a strategy to engineer a caspase to contain a latent nucleophile that can be targeted by a probe containing a suitably placed electrophile, thereby allowing specific, irreversible inhibition and labeling of only the engineered protease. To accomplish this, we have identified a non-conserved residue on the small subunit of all caspases that is near the substrate-binding pocket and that can be mutated to a non-catalytic cysteine residue. We demonstrate that an active-site probe containing an irreversible binding acrylamide electrophile can specifically target this cysteine residue. Here we validate the approach using the apoptotic mediator, caspase-8, and the inflammasome effector, caspase-1. We show that the engineered enzymes are functionally identical to the wild-type enzymes and that the approach allows specific inhibition and direct imaging of the engineered targets in cells. Therefore, this method can be used to image localization and activation as well as the functional contributions of individual caspase proteases to the process of cell death or inflammation.

Expression of Bak and Bak/Mcl-1 ratio can predict photodynamic therapy outcome for oral verrucous hyperplasia and leukoplakia.

BACKGROUND: Our previous studies showed that topical 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) is very effective for oral verrucous hyperplasia (OVH) and relatively less effective for oral leukoplakia (OL) lesions. Nevertheless, there has been no report on the association of the expression of apoptosis-related proteins in OVH and OL biopsy tissues prior to PDT with PDT treatment outcomes. METHODS: This study used immunohistochemistry to evaluate whether the expression of Bak, Mcl-1, caspase-3, caspase-8, caspase-9, p53, p21, or PCNA protein in biopsy specimens of OVH and OL lesions could be used to predict the clinical outcomes of 18 OVH and 40 OL lesions treated with topical ALA-PDT. The marker labeling score (LS) was defined as labeling index (positive cells/total cells) multiplied by staining intensity. The lesions after ALA-PDT treatment were divided into complete response (CR) group and partial or no response (PR/NR) group. RESULTS: The mean Bak LS and the mean Bak/Mcl-1 LS ratio were significantly higher in the CR group than in the PR/NR group. However, there was no significant difference in the Mcl-1, caspase-3, caspase-8, caspase-9, p53, p21, or PCNA protein LS between the CR and PR/NR groups. CONCLUSION: We conclude that the Bak LS or Bak/Mcl-1 LS ratio may be a useful biomarker to predict the clinical outcomes of OVH and OL lesions treated with topical ALA-PDT. Pre-PDT epithelial cell levels of Mcl-1, caspase-3, caspase-8, caspase-9, p53, p21, and PCNA may not have a significant influence on the clinical outcome of OVH and OL lesions treated with topical ALA-PDT.

The study of the Oxytropis kansuensis-induced apoptotic pathway in the cerebrum of SD rats.

BACKGROUND: Locoweeds cause significant livestock poisoning and economic loss all over the world. Animals can develop locoism, a chronic neurological disease, after grazing on locoweeds. Oxytropis kansuensis is a variety of locoweed that contains swainsonine as its main toxic ingredient. The purpose of this study was to investigate the apoptotic pathway induced in the cerebrum by swainsonine. RESULTS: Twenty-four Sprague-Dawley rats were randomly divided into four groups (experimental groups I, II, III and a control group) and 6 SD rats of each group were feed in 3 cages separately. Rats were penned as groups and fed with feeds containing 15% (SW content 0.03‰), 30% (SW content 0.06‰), or 45% (SW content 0.09‰) O. kansuensis for experimental groups I, II, and III, respectively, or complete feed in the case of the control group. One hundred and nineteen days after poisoning, and all rats showed neurological disorders at different degrees, which were considered to be successful established a chronic poisoning model of O. kansuensis. rats were sacrificed and the expression of Fas, FasL, Bcl-2, Bax as well as cleaved caspase-3, -8 and -9 proteins in brain tissues were detected by Western blot. The results showed that SW treatment up-regulated Fas and Fas ligand (FasL) (P < 0.05), and that there was an increase in Bax and a decrease in Bcl-2 protein (P < 0.01). Moreover, SW treatment significantly increases the activation of caspase-3, 8 and -9, the key effectors in apoptosis pathway (P < 0.01). CONCLUSION: Our data suggest that SW induces apoptosis in cells of the brain through death receptor and mitochondria-mediated, caspase-dependent apoptotic pathways in the brain tissue of SD rats.

Galangin induces apoptosis in hepatocellular carcinoma cells through the caspase 8/t-Bid mitochondrial pathway.

This study has investigated whether galangin, a flavonol derived from Alpinia officinarum Hance and used as food additives in southern China, induces apoptosis in hepatocellular carcinoma cells (HCCs) by activation of the caspase-8 and Bid pathway. The apoptosis of HCCs was evaluated by in situ uptake of propidium iodide and Hoechst 33258. Protein expressions were detected by Western blotting. Caspase-8 activity was measured using colorimetric method. To confirm the galangin-induced apoptotic pathway, inhibition of caspase-8 activity by Z-IETD-FMK, knockdown of Bid expression with siRNA, and overexpression of Bcl-2 in cells were carried out, respectively. The results show that galangin has significantly induced apoptosis in HCC lines. The caspase-8 is activated, and the cleavage of Bid results in the increase in tBid. The galangin-induced apoptosis is attenuated by Z-IETD-FMK, Bid siRNA, and Bcl-2 overexpression, respectively. However, Bcl-2 fails to suppress caspase-8 activation and the cleavage of Bid. This study has demonstrated that galangin induces apoptosis in HCCs by activating caspase 8/t-Bid mitochondrial pathway. Although Bcl-2 overexpression attenuates galangin-mediated apoptosis of HCCs, it is not mediated by the inhibition of tBid generation and caspase-8 activation.

Type of serum influences the rituximab dependent cytotoxicity and apoptosis of chronic lymphocytic leukemia cells in vitro.

PURPOSE: The aim of the study was to compare the influence of types of serum on the in vitro viability and on either spontaneous or rituximab (RIT)-induced apoptosis of chronic lymphocytic leukemia (CLL) cells. METHODS: The influence of fetal calf serum (FCS), patients' autologous serum (AS) and human AB-serum (ABS), used alone and in combinations consisting of two of them (v/v-1:1), on RIT-dependent cytotoxicity, apoptosis, detection of active forms of caspases-3,-9,-8 and disruption of mitochondrial membrane potential (ΔΨm) were assessed by flow cytometry. RIT was used at the concentration of 10 µg/ml. The spontaneous apoptosis was assessed in culture without RIT. RESULTS: AS revealed the protective action on CLL cells, however this serum added in vitro to the culture either alone or in combination with FCS was the only one to allow RIT to exert its cytotoxic action against CLL cells. RIT-induced apoptosis involved changes in ΔΨm and activation of caspases-3,-8,-9 when AS+FCS was applicated. Drug induced apoptosis (DIA) was 6.02 and 0.34, when FCS+AS and FCS alone were used, respectively (p<0.01). The RIT-dependent cytotoxic effect decreased when FCS+AS or FCS+ABS were used, as compared to effect of AS used separately. The cytotoxic effect of RIT did not depend on drug concentration, but on the type of serum added to the culture. CONCLUSIONS: The strongest cytotoxic effect of RIT in the presence of AS suggests that this drug activity towards CLL cells is enhanced by known cytotoxic mechanisms, caspase-dependent apoptotic pathway and possible influence of other extracellular factors present in the patients' sera.

Testicular apoptosis and histopathological changes induced by a 2.45 GHz electromagnetic field.

There is a growing public concern about the potential human health hazard caused by exposure to electromagnetic radiation (EMR). The objective of this study is to investigate the effects of 2450 mhz electromagnetic field on apoptosis and histopathological changes on rat testis tissue. Twelve-week-old male Wistar Albino rats were used in this study. Eighteen rats equally divided into three different groups which were named group I, II and III. Cage control (group I), sham control (group II) and 2.45 GHz EMR (group III) groups were formed. Group III were exposed to 2.45 GHz EMR, at 3.21 W/kg specific absorption rate for 60 minutes/ day for 28 days. There was no difference among the groups for the diameter of the seminiferous tubules, pyknotic, karyolectic and karyotic cells. However, the number of Leydig cells of testis tissue of the rats in group III was significantly reduced comparing with the group I (p < 0.05). Estimation of spermatogenesis using the Johnsen testicular biopsy score revealed that the difference between groups is statistically significant. The level of TNF-α, Caspase-3 and Bcl-2 were compared, and no significant difference was found between the groups. When Bax apoptosis genes and Caspase-8 apoptosis enzyme were compared, there were significant differences between the groups (p < 0.05). Electromagnetic field affects spermatogenesis and causes to apoptosis due to the heat and other stress-related events in testis tissue.

Intracellular Casp8p41 content is inversely associated with CD4 T cell count.

Casp8p41 is a protein fragment generated by cleavage of procaspase 8 by human immunodeficiency virus (HIV) protease. We measured Casp8p41 content in memory CD4 T cells and analyzed the association of Casp8p41 content with CD4 T cell count, cross-sectionally and longitudinally. Casp8p41 content was inversely correlated with CD4 T cell count, and change in Casp8p41 content was associated with absolute CD4 T cell count with change over time. Casp8p41 change was a better predictor of CD4 T cell count change than activated CD8 T cell percentage or viral load and was comparable to bacterial 16s DNA levels. This suggests that Casp8p41 is a relevant mediator of CD4 T cell death during HIV infection.

[Heat shock protein 90--modulator of TNFalpha-induced apoptosis of Jurkat tumor cells].

rTNFalpha-induced programmed death of Jurkat tumor cells cultured with 17-AAG, a selective inhibitor of heat shock protein (Hsp90), was studied by fluorescent microscopy with the use of FITC-labeled annexin V and propidium iodide. Caspase-3 and -8 activities were determined by spectrophotometry using a caspase- 3 and -8 colorimetric assay kit. It was shown that inhibition of Hsp90 leads to activation of Jurkat cell apoptosis while Hsp90 itself suppresses this process. 17-AAG enhances rTNFa-induced apoptosis of tumor cells.

Real-time monitoring of caspase-3/8 activity by self-assembling nanofiber probes in living cells.

Caspase-3/8 are key members of the cysteine-aspartyl protease family with pivotal roles in apoptosis. We have designed and synthesized self-assembling probes, Nap-GFFpYDEVD-AFC and Nap-GFFpYIETD-AFC, with fluorescence 'turn-on' properties for real-time monitoring of Caspase-3/8 activity in living cells.

Salivary GFAP as a potential biomarker for diagnosis of mild cognitive impairment and Alzheimer's disease and its correlation with neuroinflammation and apoptosis.

Glial fibrillary acidic protein (GFAP) is the main constituent of the astrocytic cytoskeleton, overexpressed during reactive astrogliosis-a hallmark of Alzheimer's Disease (AD). GFAP and established biomarkers of neurodegeneration, inflammation, and apoptosis have been determined in the saliva of amnestic-single-domain Mild Cognitive Impairment (MCI) (Ν = 20), AD (Ν = 20) patients, and cognitively healthy Controls (Ν = 20). Salivary GFAP levels were found significantly decreased in MCI and AD patients and were proven an excellent biomarker for discriminating Controls from MCI or AD patients. GFAP levels correlate with studied biomarkers and Aß42, IL-1ß, and caspase-8 are its main predictors.