Process of apoptosis induced by TNF-alpha in murine fibroblast Ltk-cells: continuous observation with video enhanced contrast microscopy

Scanning ion conductance microscopy revealed cisplatin-induced morphological changes related to apoptosis in single adenocarcinoma cells

The studies of drug-induced apoptosis play a vital role in the identification of potential drugs that could treat diseases such as cancer. Alterations in the native morphology of cancer cells following treatment with anticancer drugs serve as one of the indicators that reveal drug efficacy. Various techniques such as optical microscopy, electron microscopy (EM), and atomic force microscopy (AFM) have been used to map the three dimensional (3D) morphological changes in cells induced with drugs. However, caution should be exercised when interpreting morphological data from techniques that might alter the native morphology of cells, caused by phototoxicity, electron beam invasiveness, intrusive sample preparation, and cell membrane deformation. Herein, we have used scanning ion conductance microscopy (SICM) to study the 3D morphology and roughness of A549 adenocarcinoma cells under physiological conditions before and after cisplatin induced apoptosis, where we observed an increase in height, overall shrinkage of the cells, and irregular features form on the cell membrane. Tracking the morphology of the same single A549 cells exposed to cisplatin unveiled heterogeneity in response to the drug, formation of membrane blebs, and an increase in membrane roughness. We have also demonstrated the use of SICM for studying the effect of cisplatin on the dynamic changes in the volume of A549 cells over days. SICM is demonstrated as a technique for studying the effect of drug induced apoptosis in the same cells over time, and for multiple different single cells.

SAOS-2 osteosarcoma cells bind fibroblasts via ICAM-1 and this is increased by tumour necrosis factor-α

We recently reported exchange of membrane and cytoplasmic markers between SAOS-2 osteosarcoma cells and human gingival fibroblasts (h-GF) without comparable exchange of nuclear markers, while similar h-GF exchange was seen for melanoma and ovarian carcinoma cells. This process of “cellular sipping” changes phenotype such that cells sharing markers of both SAOS-2 and h-GF have morphology intermediate to that of either cell population cultured alone, evidencing increased tumour cell diversity without genetic change. TNF-α increases cellular sipping between h-GF and SAOS-2, and we here study binding of SAOS-2 to TNF-α treated h-GF to determine if increased cellular sipping can be accounted for by cytokine stimulated SAOS-2 binding. More SAOS-2 bound h-GF pe-seeded wells than culture plastic alone (p<0.001), and this was increased by h-GF pre-treatment with TNF-α (p<0.001). TNF-α stimulated binding was dose dependent and maximal at 1.16nM (p<0.05) with no activity below 0.006 nM. SAOS-2 binding to h-GF was independent of serum, while the lipopolysaccharide antagonist Polymyxin B did not affect results, and TNF-α activity was lost on boiling. h-GF binding of SAOS-2 started to increase after 30min TNF-α stimulation and was maximal by 1.5hr pre-treatment (p<0.001). h-GF retained maximal binding up to 6hrs after TNF-α stimulation, but this was lost by 18hrs (p<0.001). FACS analysis demonstrated increased ICAM-1 consistent with the time course of SAOS-2 binding, while antibody against ICAM-1 inhibited SAOS-2 adhesion (p<0.04). Pre-treating SAOS-2 with TNF-α reduced h-GF binding to background levels (p<0.003), and this opposite effect to h-GF cytokine stimulation suggests that the history of cytokine exposure of malignant cells migrating across different microenvironments can influence subsequent interactions with fibroblasts. Since cytokine stimulated binding was comparable in magnitude to earlier reported TNF-α stimulated cellular sipping, we conclude that TNF-α stimulated cellular sipping likely reflects increased SAOS-2 binding as opposed to enhanced exchange mechanisms.

Mitoneet mediates TNFα-induced necroptosis promoted by exposure to fructose and ethanol

Fructose and ethanol are metabolized principally in the liver and are both known to contribute to the development of hepatic steatosis that can progress to hepatic steatohepatitis. The present study indentifies a synergistic interaction between fructose and ethanol in promoting hepatocyte sensitivity to TNFα-induced necroptosis. Concurrent exposure to fructose and ethanol induces the overexpression of the CDGSH iron-sulfur domain-containing protein 1 (CISD1 or mitoneet), which is localized to the outer mitochondrial membrane. The increased expression of mitoneet primes the hepatocyte for TNFα-induced cytotoxicity. Treatment with TNFα induces the translocation of a Stat3-Grim-19 complex to the mitochondria, which binds to mitoneet and promotes the rapid release of its 2Fe-2S cluster, causing an accumulation of mitochondrial iron. The dramatic increase of mitochondrial iron provokes a surge in formation of reactive oxygen species, resulting in mitochondrial injury and cell death. Additionally, mitoneet is constitutively expressed at high levels in L929 fibrosarcoma cells and is required for L929 cells to undergo TNFα-induced necroptosis in the presence of caspase inhibition, indicating the importance of mitoneet to the necroptotic form of cell death.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Retinal pigment epithelium response to oxidant injury in the pathogenesis of early age-related macular degeneration

Age-related macular degeneration (AMD) represents the leading cause of vision loss in the elderly. Accumulation of lipid- and protein-rich deposits under the retinal pigment epithelium (RPE) heralds the onset of early AMD, but the pathogenesis of subretinal deposit formation is poorly understood. Numerous hypothetical models of deposit formation have been proposed, including hypotheses for a genetic basis, choroidal hypoperfusion, abnormal barrier formation, and lysosomal failure. This review explore the RPE injury hypothesis, characterized by three distinct stages (1) Initial RPE oxidant injury, caused by any number of endogenous or exogenous oxidants, results in extrusion of cell membrane "blebs," together with decreased activity of matrix metalloproteinases (MMPs), promoting bleb accumulation under the RPE as basal laminar deposits (BLD). (2) RPE cells are subsequently stimulated to increase synthesis of MMPs and other molecules responsible for extracellular matrix turnover (i.e., producing decreased collagen), affecting both RPE basement membrane and Bruchs membrane (BrM). This process leads to progression of BLD into basal linear deposits (BLinD) and drusen by admixture of blebs into BrM, followed by the formation of new basement membrane under the RPE to trap these deposits within BrM. We postulate that various hormones and other plasma-derived molecules related to systemic health cofactors are implicated in this second stage. (3) Finally, macrophages are recruited to sites of RPE injury and deposit formation. The recruitment of nonactivated or scavenging macrophages may remove deposits without further injury, while the recruitment of activated or reparative macrophages, through the release of inflammatory mediators, growth factors, or other substances, may promote complications and progression to the late forms of the disease.

Compound MMH01 possesses toxicity against human leukemia and pancreatic cancer cells

MMH01 is a compound isolated from Antrodia cinnamomea. MMH01 markedly inhibited growth of human leukemia U937 and pancreatic cancer BxPC3 cells. It resulted in distinct patterns of cell cycle distribution in U937 (G2/M, sub-G1 and polyploidy) and BxPC3 cells (G0/G1 and sub-G1). The modes of cell death in U937 cells include apoptosis and mitotic catastrophe, whereas apoptosis-associated events or necrosis in BxPC3 cells. Neither mitochondrial membrane permeabilization nor caspase dependence was noted. Proteins involving mitotic catastrophe-associated cell death such as cyclin B1 and checkpoint kinase 2 were activated in U937 cells. Only slight to moderate viability inhibition was noted to human monocytes, the normal counterpart of these myeloid leukemic cells. In conclusion, MMH01 possesses cytotoxicity against human leukemia and pancreatic cancer cells.

PET imaging of apoptosis with 64Cu-labeled streptavidin following pretargeting of phosphatidylserine with biotinylated annexin-V

PURPOSE

In vivo detection of apoptosis is a diagnostic tool with potential clinical applications in cardiology and oncology. Radiolabeled annexin-V (anxV) is an ideal probe for in vivo apoptosis detection owing to its strong affinity for phosphatidylserine (PS), the molecular flag on the surface of apoptotic cells. Most clinical studies performed to visualize apoptosis have used (99m)Tc-anxV; however, its poor distribution profile often compromises image quality. In this study, tumor apoptosis after therapy was visualized by positron emission tomography (PET) using (64)Cu-labeled streptavidin (SAv), following pre-targeting of apoptotic cells with biotinylated anxV.

METHODS

Apoptosis was induced in tumor-bearing mice by photodynamic therapy (PDT) using phthalocyanine dyes as photosensitizers, and red light. After PDT, mice were injected i.v. with biotinylated anxV, followed 2 h later by an avidin chase, and after another 2 h with (64)Cu-DOTA-biotin-SAv. PET images were subsequently recorded up to 13 h after PDT.

RESULTS

PET images delineated apoptosis in treated tumors as early as 30 min after (64)Cu-DOTA-biotin-SAv administration, with tumor-to-background ratios reaching a maximum at 3 h post-injection, i.e., 7 h post-PDT. Omitting the administration of biotinylated anxV or the avidin chase failed to provide a clear PET image, confirming that all three steps are essential for adequate visualization of apoptosis. Furthermore, differences in action mechanisms between photosensitizers that target tumor cells directly or via initial vascular stasis were clearly recognized through differences in tracer uptake patterns detecting early or delayed apoptosis.

CONCLUSION

This study demonstrates the efficacy of a three-step (64)Cu pretargeting procedure for PET imaging of apoptosis. Our data also confirm the usefulness of small animal PET to evaluate cancer treatment protocols.

Spironolactone induces apoptosis in human mononuclear cells. Association between apoptosis and cytokine suppression

Spironolactone (SPIR) has been described to suppress accumulation of pro-inflammatory cytokines. Here, the suppression of TNF-alpha in lipopolysaccharide (LPS)-stimulated mononuclear cell cultures was confirmed. However, SPIR was also found to induce apoptosis, prompting the investigations of a possible association between the two effects: The apoptosis-inducing and the cytokine-suppressive effects of SPIR correlated with regard to the effective concentration range. Also, pre-incubation experiments demonstrated a temporal separation of the two effects of < or = 4 h, with TNF-alpha suppression preceding apoptosis. An association between the two effects was also seen when testing several SPIR analogues. Contrary to TNF-alpha, the levels of IL-1beta increased in SPIR-treated cultures. However, the amount of IL-1beta in the supernatants depended upon the order of SPIR and LPS addition, as IL-1beta was non-detectable in cultures treated with SPIR prior to LPS, whereas elevated IL-1beta levels were seen when SPIR was added after LPS-stimulation. It is possible that the extracellular accumulation of IL-1beta is due to an increased release of already produced IL-1beta as a result of cell death. In conclusion, suppression of cytokine production by SPIR may be associated with its apoptotic potential, either directly (apoptosis is a consequence of suppressed cytokine production, or vice-versa) or indirectly (suppressed cytokine production and apoptosis are parallel but otherwise unrelated phenomena).

Effects of inhalation anesthetics halothane, sevoflurane, and isoflurane on human cell lines

Cytotoxic and antiproliferative effects of halothane, isoflurane, and sevoflurane in anesthetic doses on human colon carcinoma (Caco-2), larynx carcinoma (HEp-2), pancreatic carcinoma cells (MIA PaCa-2), poorly differentiated cells from lymph node metastasis of colon carcinoma (SW-620), and normal fibroblasts were investigated. Cells were exposed to anesthetic gas mixture consisting of O(2): N2O (35:60 vol.%), halothane (1.5 vol.%) or isoflurane (2.0 vol.%) or sevoflurane (3.0 vol.%), and CO(2) (5 vol.%), for 2, 4, and 6 h. Cytotoxicity of anesthetics was analyzed by validated tetrazolium dye assay MTT test. All anesthetics expressed cytotoxic effects on treated tumor cells in time and cell line dependent manner. Growth suppression in cells exposed to halothane was enhanced in HEp-2 (to 67.7%), Caco-2 (to 76.3%), and SW620 cells (to 80.9%), and was minimal in normal fibroblasts (to 89.4%). Antiproliferative activity of halothane was measured via radioactive precursors incorporation assay. In Caco-2 cells treated by halothane, decrease in DNA synthesis (52.4%, p=0.001), RNA synthesis (39.2%, p<0.001), and protein synthesis (19.2%, p=0.004) was observed. In HEp-2 cells, DNA and RNA syntheses were decreased to 72.5% and 79.9%, whereas protein synthesis was 14.0% of control (p<0.001). In SW620 cells, protein synthesis after 4 h was 24.4% (p=0.007). A DNA fragmentation was observed in Caco-2 and MIA PaCa-2 cells. Exposition of phosphatidylserine on outer lipid bilayer plasma membrane of tumor cell treated by halothane proved apoptosis as mode of cell death.

Photothermal detection of nicotine-induced apoptotic effects in pancreatic cancer cells

The objective of this study was to evaluate the capability of a photothermal (PT) assay in determining the effects of graded doses of nicotine in a pancreatic acinar cell line (AR42J). The cellular response to nicotine was detected through the monitoring of PT signals from light-absorbing endogenous cellular structures that have been used as natural indicators for nicotine's action. It was demonstrated that introducing nicotine to cultured acinar cells in vitro leads to changes in cellular absorbing structures, thereby altering the microstructure of PT cell images and the temporal shape of PT signals. The results showed that the dependence of specific PT parameters was almost proportional to nicotine concentrations ranging from 1 nM to 100 microM, with the saturation maximum at and around 100 microM - 1 mM; thereafter, PT signals decreased rapidly to control levels and even lower, in the range of 1 - 50 mM. Conventional fluorescent tests (Annexin V--Propidium Iodide) performed in parallel showed no effect with nicotine at a concentration <1 microM (three orders of magnitude greater than the sensitivity threshold of the PT assay). With an increase in nicotine concentration from 1 mM to 50 mM, rapidly growing apoptotic and necrotic cells were detected. Thus, the PT assay demonstrated the capability for high-sensitivity detection of nicotine's impact, which may be related to a change in cell metabolism, apoptosis, or necrosis, depending on nicotine concentration.

Silica-induced apoptosis in mouse alveolar macrophages is initiated by lysosomal enzyme activity

Past studies in our laboratory have shown that silica (-quartz) particle exposure of a mouse alveolar macrophage cell line (MH-S) elicits mitochondrial depolarization and caspase 3 and 9 activation, contributing to apoptosis. However, cellular pathways leading to these outcomes have not been extensively investigated. Initial studies revealed that silica exposure elicits lysosomal permeability after 1 h, as evidenced by leakage of FITC-conjugated dextran and acridine orange. We next evaluated a role for the lysosomal acidic compartment in apoptosis. Cells pretreated with the lysosomotropic weak base ammonium chloride, to increase lysosomal pH, showed decreased caspase activation and apoptotic DNA fragmentation. MH-S cells pretreated with pepstatin A, an inhibitor of lysosomal cathepsin D, showed decreased caspase 9 and 3 activation as well as a decreased percentage of cells that became apoptotic. DNA fragmentation and caspase 9 and 3 activation were also decreased in cells pretreated with despiramine, an inhibitor of lysosomal acidic sphingomyelinase. Silica pretreated with aluminum lactate (to blunt surface active sites) reduced caspase activation and apoptosis. Although aluminum lactate-treated silica still induced lysosomal permeability (by FITC-dextran leakage), one measure of lysosome integrity and function suggested a reduction in the extent and/or nature of lysosomal injury (by acridine orange retention). A role for reactive oxygen species (ROS) was investigated to explore another pathway for silica-induced apoptosis in addition to lysosomal enzymes; however, no role for ROS was apparent. Thus, following silica exposure, lysosomal injury precedes apoptosis, and the apoptotic signaling pathway includes cathepsin D and acidic sphingomyelinase.

TNF-? in vivo stimulates apoptosis in fibroblasts through caspase-8 activation and modulates the expression of pro-apoptotic genes

Apoptosis of matrix producing cells is common among many inflammatory diseases. The goal of the present study was to examine the apoptotic effects of tumor necrosis factor-alpha (TNF-alpha) on fibroblastic cells in vivo and to investigate the role of different caspases in this process. This was accomplished in vivo by subcutaneous injection of TNF-alpha in mice. The direct effects of TNF-alpha on fibroblast apoptosis were studied in vitro with normal diploid human fibroblasts. The results indicate that TNF-alpha in vivo induces apoptosis of fibroblasts. By RNase protection assay, we demonstrated that TNF-alpha stimulates expression of 12 apoptotic genes. Fluorometric studies demonstrated that TNF-alpha in vivo predominantly increased caspase-8 and -3 activity and by use of specific inhibitors, the activation of caspase-3 was shown to be initiated by caspase-8 with only a minor contribution from caspase-9. Thus, TNF-alpha acts to modulate the expression of many genes that favors apoptosis of fibroblastic cells, which is dependent mostly upon signaling through caspase-8.

Cyclin E overexpression enhances cytokine-mediated apoptosis in MCF7 breast cancer cells

Cyclin E, the regulatory component of the cyclin E/cyclin-dependent kinase (CDK) complex, is required for proliferation and overexpression of this cyclin is associated with many types of human tumors. To elucidate the mechanism by which cyclin E overexpression promotes tumorigenesis, cyclin E was overexpressed in two breast cancer lines: MCF7 and T47D. Cells overexpressing cyclin E display a marked decrease in the expression of Bcl-2, an antiapoptotic protein, and increased levels of the proapoptotic proteins Bad and Bax. The levels of Bcl-X(L) and Mcl-1 remain unchanged. Since the homeostasis of pro- and antiapoptotic proteins was altered, we asked if cyclin E overexpression modifies responses to cytokines. MCF7 cyclin E overexpressing cells have an enhanced sensitivity to Fas, TRAIL, and TNF-alpha-induced apoptosis. T47D cells overexpressing cyclin E have a significant increase in TNF-alpha and TRAIL-induced apoptosis. In conclusion, our results provide a link between expression of cyclin E, deregulation of Bcl-2, and an altered response to cytokine-mediated apoptosis.

Effective induction of antiglioma cytotoxic T cells by coadministration of interferon-beta gene vector and dendritic cells

As type I interferons (IFNs) enhance the stimulatory activity of dendritic cells (DCs), we hypothesized that transfection of glioma cells with the IFN-beta gene in the presence of DCs would provide particularly effective antitumor activity by both facilitating apoptosis of glioma cells and presenting the resulting glioma antigens to T cell by DCs, thereby inducing specific T-cell responses against glioma cells. A mouse glioma cell line 203G was first transfected with cDNA encoding IFN-beta using cationic liposomes, then cocultured with syngeneic bone marrow-derived DCs and naïve splenic T cells. The 203G cells were almost completely killed following 96-hour coculture with DCs and T cells, and strong tumor-specific cytotoxic T-lymphocyte (CTL) activity accompanied by high level interleukin (IL)-12 and IFN-gamma production was observed in culture. In addition, omission of either IFN-beta gene delivery, DCs or T cells from the coculture completely abrogated the induction of the CTL activity, suggesting that the combination of these components was required to elicit an optimal effect. On the basis of these in vitro data, syngeneic animals bearing subcutaneous 203G tumors received intratumoral injections of IFN-beta gene and DCs. Suppression of the tumor growth by this combinational therapy was superior to treatment with DC or IFN-beta gene solely. This combination may constitute a new therapeutic strategy to induce potent antiglioma immune responses.

Apoptotic DNA endonuclease (DNase-gamma) gene transfer induces cell death accompanying DNA fragmentation in human glioma cells

AIMS

Both the genetic restoration of the apoptotic pathway and the introduction of proapoptotic molecules are now drawing attention. Concerning apoptosis of human glioma cells induced by human interferon-beta protein, we found that DNA endonuclease (DNase-gamma) acts as an executive molecule. The authors investigated whether gene transfer of this DNase-gamma exerts some therapeutic effects on human glioma cells.

METHODS

We transduced U251SP, U251MG, and T98G human glioma cells with DNase-gamma gene via multilamellar cationic liposomes, monitored the growth of those cells, and carefully observed the cell-death pattern.

RESULTS

DNase-gamma gene transfer resulted in an overexpression of DNase-gamma protein and induced DNA fragmentation in gene-transferred cells. The cytotoxic effect rose with multiple inoculations of the liposome, suggesting a relationship between its expression and the therapeutic effect.

CONCLUSIONS

These results demonstrate that DNase-gamma gene transfer can induce apoptosis in human glioma cells, indicating its potential to become a future gene therapy strategy.

Antitumor effect of an adeno-associated virus vector containing the human interferon-beta gene on experimental intracranial human glioma

We constructed an adeno-associated virus (AAV) vector containing the human interferon-beta (HuIFN-b ) gene (AAV-IFN-beta) and investigated its antitumor effect against human glioma cells (U251-SP) inoculated into the brain of nude mice. Prior to this, we examined human glioma cells transduced with AAV-IFN-beta using video-enhanced contrast differential interference contrast (VEC-DIC) microscopy. Infection of AAV-IFN-beta induced apoptosis and secondary necrosis in human glioma cells. In in vivo experiments, we confirmed production of HuIFN-beta and induction of heat-shock protein (HSP) in glioma cells transduced with AAV-IFN-beta. Growth of the experimental gliomas was completely inhibited by six injections of AAV-IFN-beta, starting 7 days after transplantation of glioma cells. In addition, the survival of mice treated with AAV-IFN-beta was remarkably prolonged. These results indicate that AAV-IFN-beta induces apoptosis of glioma cells and has a strong antitumor effect in this experimental glioma model.