Morphological Evidence Of Apoptosis Research Articles

Anticancer activity of Morus nigra on human breast cancer cell line (MCF-7) the role of fresh and dry fruit extracts.

Black mulberry (Morus nigra L.) has a long history of medicinal use in folk medicine. In this study, in vitro anticancer properties of fresh and dry black mulberry (BM) ethanolic extracts on breast adenocarcinoma cell line (MCF-7) were investigated. Cytotoxic effect of both extracts was investigated by neutral red uptake method and the IC50 was assessed. The morphological changes, apoptosis and/or necrosis, were detected by Giemsa staining and acridine orange/ethidium bromide dual fluorescent staining methods, in addition to DNA fragmentation assay by gel electrophoresis and comet assay. Mitotic index was evaluated in MCF-7 groups to investigate the antiproliferative potential of fresh and dry BM extracts. Furthermore, micronucleus and other nuclear abnormalities were also investigated. BM extracts administration gave significant (p < 0.05) morphological evidence of apoptosis and increased cell death after 48 hours more than that of 24 hours-treated MCF-7 cells among fresh and dry extract groups. DNA analysis after 24 h of BM extracts treated groups has no fragmentation while apoptosis is generated after 48h showing more fragmentation in fresh BM groups. The mitotic index records were significantly decreased in dose and time dependent manner showing the better antiproliferative effect with fresh extract treatments. DNA single strand breaks were also increased among the treatment groups at dose and time dependent manner with the best results with fresh extract. It can be concluded that black mulberry fruit is a considerable source of health dietary supplement and its integration for pharmaceutical industries has to be in concern.

In situ hybridisation detects pro-apoptotic gene expression of a Bcl-2 family member in white syndrome-affected coral

White syndrome has been described as one of the most prolific diseases on the Great Barrier Reef. Previously, apoptotic cell death has been described as the mechanism driving the characteristic rapid tissue loss associated with this disease, but the molecular mechanisms controlling apoptotic cell death in coral disease have yet to be investigated. In situ methods were used to study the expression patterns of 2 distinct regulators of apoptosis in Acropora hyacinthus tissues undergoing white syndrome and apoptotic cell death. Apoptotic genes within the Bcl-2 family were not localized in apparently healthy coral tissues. However, a Bcl-2 family member (bax-like) was found to localize to cells and tissues affected by white syndrome and those with morphological evidence for apoptosis. A potential up-regulation of pro-apoptotic or bax-like gene expression in tissues with apoptotic cell death adjacent to disease lesions is consistent with apoptosis being the primary cause of rapid tissue loss in coral affected by white syndrome. Pro-apoptotic (bax-like) expression in desmocytes and the basal tissue layer, the calicodermis, distant from the disease lesion suggests that apoptosis may also underlie the sloughing of healthy tissues associated with the characteristic, rapid spread of tissue loss, evident of this disease. This study also shows that in situ hybridisation is an effective tool for studying gene expression in adult corals, and wider application of these methods should allow a better understanding of many aspects of coral biology and disease pathology.

Histopathology of motor cortex in an experimental focal ischemic stroke in mouse model

Experimental ischemia results in cortical brain lesion followed by ischemic stroke. In this study, focal cerebral ischemia was induced in mice by occlusion of the middle cerebral artery. We studied cortical layers I, II/III, V and VI in the caudal forelimb area (CFA) and medial agranular cortex (AGm) from control and C57BL/6 mice induced with ischemic stroke. Based on our analysis of CFA and AGm motor cortex, significant differences were observed in the numbers of neurons, astrocytes and microglia in the superficial II/III and deep V cortical layers. Cellular changes were more prominent in layer V of the CFA with nuclear pyknosis, chromatin fragmentation, necrosis and degeneration, as well as, morphological evidence of apoptosis, mainly in neurons. As result, the CFA was more severely impaired than the AGm in this focal cerebral ischemic model, as evidenced by the proliferation of astrocytes, potentially resulting in neuroinflammation by microglia-like cells.

Angiostatin inhibits activation and migration of neutrophils

There is a critical need to identify molecules that modulate the biology of neutrophils because activated neutrophils, though necessary for host defense, cause exuberant tissue damage through production of reactive oxygen species and increased lifespan. Angiostatin, an endogenous anti-angiogenic cleavage product of plasminogen, binds to integrin αvβ3, ATP synthase and angiomotin and its expression is increased in inflammatory conditions. We test the hypothesis that angiostatin inhibits neutrophil activation, induces apoptosis and blocks recruitment in vivo and in vitro. The data show immuno-reactivity for plasminogen/angiostatin in resting neutrophils. Angiostatin conjugated to FITC revealed that angiostatin was endocytozed by activated mouse and human neutrophils in a lipid raft-dependent fashion. Co-immunoprecipitation of human neutrophil lysates, confocal microscopy of isolated mouse and human neutrophils and functional blocking experiments showed that angiostatin complexes with flotillin-1 along with integrin αvβ3 and ATP synthase. Angiostatin inhibited fMLP-induced neutrophil polarization, as well as caused inhibition of hsp-27 phosphorylation and stabilization of microtubules. Angiostatin treatment, before or after LPS-induced neutrophil activation, inhibited phosphorylation of p38 and p44/42 MAPKs, abolished reactive oxygen species production and released the neutrophils from suppressed apoptosis, as indicated by expression of activated caspase-3 and morphological evidence of apoptosis. Finally, intravital microscopy and myeloperoxidase assay showed inhibition of neutrophil recruitment in post-capillary venules of TNFα-treated cremaster muscle in mouse. These in vitro and in vivo data demonstrate angiostatin as a broad deactivator and silencer of neutrophils and an inhibitor of their migration. These data potentially open new avenues for the development of anti-inflammatory drugs.

Erythropoietin protects against cisplatin-induced nephrotoxicity by attenuating endoplasmic reticulum stress-induced apoptosis

The anticancer drug cisplatin (CP)-induced nephrotoxicity associated with apoptosis plays crucial roles in tumor patients. Erythropoietin (EPO) has recently been shown to enhance recovery from CP-induced acute kidney injury (AKI) in rats by exerting anti-apoptotic effects. However, the molecular mechanisms of Erythropoietin protects against CP-induced AKI are not very clear. The present study investigated the protective effects of erythropoietin (EPO) against CP-induced nephrotoxicity and the possible mechanism in rats. Sprague-Dawley (SD) rats were randomly divided into four groups: (1) Control group (n=16): which received a single intraperitoneal injection of vehicle (0.9% saline; 5 mL/kg); (2) CP group (n=16): which received a single intraperitoneal injection of 10.0 mg/kg CP (previously dissolved at 2.0 mg/mL in 0.9% saline solution); (3) CP+rHuEPO group (n=16): which received rHuEPO (5000 U/kg) with co-injection of the LY294002 vehicle dimethyl sulfoxide (DMSO, 33.3 µL/kg; Sigma, St. Louis, MO, USA) by tail vein injection 2 days before CP administration, 15 min before CP administration, and 2 days after CP administration; (4) CP+rHuEPO+LY group (n=16): which received LY294002 (0.3 mg/kg) 10 min before rHuEPO administration by three injections into the tail vein at 2-day intervals beginning 2 days before CP administration. Apoptosis was assessed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. The expressions of C/EBP-homologous protein (CHOP), glucose-regulated protein 78 (GRP78), caspase-12, the phosphorylation of Akt, cleaved-caspase-3 and EPO receptor (EPOR) were measured after CP-treated. In addition, light microscopy and immunohistochemistry examinations were performed. The levels of serum urea and creatinine were increased at 96 h after CP-administered group. The eHuEPO-administered group had significantly lower serum creatinine levels. CP caused an increase in TUNEL-positive cells that was accompanied and apoptotic cell death induced by CP was significantly abrogated by rHuEPO at 96h by morphological evidence of apoptosis. The over-expression of CP-induced endoplasmic reticulum (ER) stress markers (CHOP and GRP78) and activation of caspase-12 were suppressed by rHuEPO, which also attenuated the CP-induced suppression of phosphatidylinositol-3kinase/Akt (PI3K/Akt) signaling in rat kidneys. In addition, LY294002 diminished the effect of rHuEPO on renal protection and antiapoptosis. Injection of rHuEPO enhance recovery from CP-induced AKI in rats by ameliorating renal functional impairment and exerting important anti-apoptotic effects. However, rHuEPO inhibited CP-induced AKI by a possible mechanism involving PI3K/Akt activation and the inhibition of ER stress-mediated apoptosis.

Citrinin reduces testosterone secretion by inducing apoptosis in rat Leydig cells

A previous study has shown that CTN (Citrinin) inhibits mouse testosterone production. In this study, the mechanism by which testosterone production is inhibited by CTN in rat Leydig cells was investigated, and the morphological evidence of apoptosis, including nuclei fragmentation and phosphatidylserine (PS) exposure on cell surfaces, was clearly observed 36h after CTN exposure. The results showed that citrinin at 50 and 100μM significantly suppressed testosterone secretion by human chorionic gonadotropin (hCG) at 10IU/ml. Western blotting results showed that CTN induced formation of processed p53, caspase-9, and caspase-3 proteins in a dose-dependent manner; CTN also induced a dose-dependent increase in caspase-3 catalytic activity. Western blot assays also showed that CTN decreased expression of three key enzymes (P450scc, 3β-HSD-1, and StAR) of testosterone production. Taken together, these results suggested that CTN reduced testosterone secretion by inducing apoptosis in rat Leydig cells, a mechanism that might account for CTN stimulation of p53 expression followed by activation of multiple caspases.

Attenuated mitochondrial NADP+-dependent isocitrate dehydrogenase activity enhances EGCG-induced apoptosis

(−)-Epigallocatechin-3-gallate (EGCG), a well-known chemopreventive factor, induces cancer cells undergoing apoptosis. Over the last several years, we have shown that the mitochondrial NADP+-dependent isocitrate dehydrogenase (IDPm) functions as an antioxidant and anti-apoptotic protein by supplying NADPH to antioxidant systems. Here, we show that EGCG induced the inactivation of IDPm as a purified enzyme and in cultured cancer cells in a dose- and time-dependent manner. Loss of enzyme activity was associated with the depletion of the thiol groups in protein. In addition, transfection of HeLa cells with an IDPm small interfering RNA (siRNA) markedly attenuated the activity of IDPm and substantially enhanced EGCG-induced apoptosis as indicated by the morphological evidence of apoptosis, DNA fragmentation, and the modulation of mitochondrial function and apoptotic marker proteins. Taken together, our results suggest that the suppression of IDPm activity resulted in the disruption of cellular redox balance and subsequently exacerbates EGCG-induced apoptotic cell death in HeLa cells. These results might have implications for developing an effective combination modality in cancer treatment.

Caffeic Acid Induces Apoptosis in Human Cervical Cancer Cells Through the Mitochondrial Pathway

The anti-proliferation effect of caffeic acid (3,4-dihydroxycinnamic acid), isolated from Ocimum gratissimum Linn, on human cervical cancer cells (HeLa cells) was examined to elucidate the associated mechanism and death mode. Flow cytometry showed that caffeic acid treatment results in dramatically increased apoptosis of HeLa cells. Western blot analysis revealed that caffeic acid activates various processed caspases. Caffeic acid significantly reduced proliferation of HeLa cells in a concentration-dependent manner. Morphological evidence of apoptosis, including nuclei fragmentation was clearly observed 24 and 48 hours after exposure to caffeic acid (1 mM and 10 mM) by flow cytometry. Time-dependent inhibition was also observed. Caffeic acid decreased levels of uncleaved caspase-3 and Bcl-2, and induced cleaved caspase-3 and p53. Caffeic acid induces apoptosis by inhibiting Bcl-2 activity, leading to release of cytochrome c and subsequent activation of caspase-3, indicating that caffeic acid induces apoptosis via the mitochondrial apoptotic pathway. This also suggests that caffeic acid has a strong anti-tumor effect and may be a promising chemopreventive or chemotherapeutic agent.

Silencing of mitochondrial NADP+‐dependent isocitrate dehydrogenase gene enhances selenite‐induced apoptosis

Selenium has been shown to play a chemopreventive role in human cancer, presumably by inducing tumor cell apoptosis. Selenite is thought to induce oxidative stress by the generation of the superoxide anion and catalyzing the oxidation of thiol groups. We previously reported that control of the mitochondrial redox balance is a primary function of mitochondrial NADP+‐dependent isocitrate dehydrogenase (IDPm) by supplying NADPH for antioxidant systems. When we investigated whether IDPm would be a vulnerable target of selenite, the loss of enzyme activity was observed. Transfection of HeLa cells with an IDPm small interfering RNA (siRNA) markedly decreased activity of IDPm and enhanced cells?susceptibility of selenite‐induced apoptosis as indicated by morphological evidence of apoptosis, DNA fragmentation, and the modulation of mitochondrial function and apoptotic marker proteins. These results suggest that IDPm siRNA sensitizes HeLa cells to selenite‐induced apoptotic cell death presumably through the perturbation of the cellular redox status.

Silencing of mitochondrial NADP+-dependent isocitrate dehydrogenase gene enhances selenite-induced apoptosis

Selenium has been shown to play a chemopreventive role in human cancer, presumably by inducing tumour cell apoptosis. Selenite is thought to induce oxidative stress by the generation of the superoxide anion and catalysing the oxidation of thiol groups. It has previously been reported that control of the mitochondrial redox balance is a primary function of mitochon-drial NADP+-dependent isocitrate dehydrogenase (IDPm) by supplying NADPH for antioxidant systems. When investigating whether IDPm would be a vulnerable target of selenite, the loss of enzyme activity was observed. Transfection of HeLa cells with an IDPm small interfering RNA (siRNA) markedly decreased activity of IDPm and enhanced cells’ susceptibility of selenite-induced apoptosis, as indicated by morphological evidence of apoptosis, DNA fragmentation and the modulation of mitochondrial function and apoptotic marker proteins. These results suggest that IDPm siRNA sensitizes HeLa cells to selenite-induced apoptotic cell death, presumably through the perturbation of the cellular redox status.

Cytosolic NADP +-dependent isocitrate dehydrogenase regulates cadmium-induced apoptosis

Cadmium ions have a high affinity for thiol groups. Therefore, they may disturb many cellular functions. We recently reported that cytosolic NADP +-dependent isocitrate dehydrogenase (IDPc) functions as an antioxidant enzyme to supply NADPH, a major source of reducing equivalents to the cytosol. Cadmium decreased the activity of IDPc both as a purified enzyme and in cultured cells. In the present study, we demonstrate that the knockdown of IDPc expression in HEK293 cells greatly enhances apoptosis induced by cadmium. Transfection of HEK293 cells with an IDPc small interfering RNA significantly decreased the activity of IDPc and enhanced cellular susceptibility to cadmium-induced apoptosis as indicated by the morphological evidence of apoptosis, DNA fragmentation and condensation, cellular redox status, mitochondria redox status and function, and the modulation of apoptotic marker proteins. Taken together, our results suggest that suppressing the expression of IDPc enhances cadmium-induced apoptosis of HEK293 cells by increasing disruption of the cellular redox status.

Apoptosis in pulp elimination during physiological root resorption in human primary teeth

Pulp samples of 50 healthy human teeth with indication for extraction were examined to evaluate the role of apoptosis in pulp elimination during physiological root resorption. Two groups were formed: a test group (n=30) composed of pulp samples of primary teeth with physiological root resorption and a control group (n=20) composed of pulp samples of permanent maxillary third molars. Morphological evidence of apoptosis as well as in situ detection of cellular DNA fragmentation by TUNEL assay and detection of internucleosomal pattern of fragmentation of the genomic DNA by electrophoresis were observed. The apoptotic index of the primary tooth group was significantly higher than that of the permanent tooth group (51.01 +/- 0.52 versus 25.32 +/- 0.68) (p<0.001). TUNEL reaction showed intense and diffuse labeling in the pulp samples of primary teeth, which were discrete in the controls. Intense DNA internucleosomal fragmentation, a specific pattern for apoptosis, was observed in primary tooth pulps DNA by electrophoresis, in the permanent tooth pulps this pattern fragmentation of the genomic DNA for apoptosis were not present. These results seem to indicate a role of apoptosis in pulp elimination during the physiological root resorption of human primary teeth.

Mechanism of patulin-induced apoptosis in human leukemia cells (HL-60)

Patulin (PAT) is a fungal secondary metabolite that exhibits potential cellular and animal toxicities. In this study, human promyelocytic leukemia (HL-60) cells were used to elucidate the mechanism and death mode associated with PAT. Morphological evidence of apoptosis, including membrane blebbing, nuclei fragmentation and DNA laddering formation was clearly observed 6 h after exposure to PAT. The results of Western blotting indicated that PAT activated various processed caspases, and cleaved DFF45 and poly (ADP-ribose) polymerase (PARP) in a dose-dependent manner; it also induced a time-dependent increase in caspase 3 and 9 catalytic activities. The apoptosis mediated by PAT in HL-60 was accompanied with cytochrome c release from mitochondria and Bcl-2 expression decrease. The presence of thiol-containing compounds with PAT dramatically reduced the caspase 3 activity that was triggered by PAT; the addition of antioxidants, including mannitol and Tiron, had a similar effect. However, the suppression of p53 protein expression by RNA interference (RNAi) in human embryonic kidney (HEK293) cells did not significantly modify PAT-elicited caspase 3 activity. These findings suggest that PAT-induced apoptosis is mediated through the mitochondrial pathway without the involvement of p53; the interaction with sulfhydryl groups of macromolecules by PAT and the subsequent generation of reactive oxygen species (ROS) plays a primary role in the apoptotic process.

The effect of mifepristone on apoptosis and caspase-3 activation in human ovarian luteinized granulosa cells

Objective To investigate the effect of mifepristone, an oral contraceptive, on apoptosis in human ovarian luteinized granulosa cells. Study design Human ovarian luteinized granulosa cells were treated in vitro with 1.25, 2.5, 5.0, 10.0, or 20.0 μM of mifepristone. Nuclear morphology, apoptosis ratio, and level of caspase-3 expression were determined with immunofluorescence microscopy, the terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL) assay, and flow cytometry. Results We found that mifepristone-treated cells contained single condensed chromatin with multiple nuclear fragments, which is morphologic evidence of apoptosis. A significant difference was observed in the TUNEL assay between mifepristone-treated cells and control cells ( P < 0.05). Consistent with the results of the TUNEL assay, the fluorescence intensity of caspase-3 in drug-treated cells was also significantly different ( P < 0.05) from control cells; specifically, the difference between cells treated with different doses of drugs was much smaller and negligible. Conclusion From these results, we propose that mifepristone induces human ovarian luteinized granulosa cells to undergo apoptosis by activating caspase-3.

&lt;I&gt;β&lt;/I&gt;-Escin, a natural triterpenoid saponin from Chinese horse chestnut seeds, depresses HL-60 human leukaemia cell proliferation and induces apoptosis RETRACTED ARTICLE

Beta-escin, a natural triterpenoid saponin isolated from the seed of the horse chestnut, is known to generate a wide variety of biochemical and pharmacological effects. The purpose of the present study was to examine the apoptotic and antiproliferative activity of beta-escin in HL-60 human acute myeloid leukaemia cells. Antiproliferative activity was examined by soft agar colony assay and the trypan blue exclusion method. Apoptotic activity was evaluated by morphological analysis, annexin V analysis, DNA fragmentation analysis and flow cytometry cell cycle analysis. The results showed that beta-escin caused a significant inhibition of HL-60 cell proliferation in a dose- and time-dependent manner. Morphological evidence of apoptosis, including vacuolization, apoptotic nuclei fragmentation and apoptotic body formation, was observed in cells treated with 30 microg mL(-1) of beta-escin for 24, 48 and 72 h. A significant increase in the population of annexin V+ and PI- cells (early apoptotic) among the total cells was observed in cells treated with beta-escin (30-50 microg mL(-1)) for 24 h (P<0.001). Typical DNA ladders, DNA with a unit length of about 180 bp, were detected in cells treated with beta-escin (30-50 microg mL(-1)) for 48 h by agarose gel electrophoresis. Flow cytometry cell cycle analysis revealed that beta-escin (30-50 microg mL(-1)) induced G1-S arrest and led to a significant accumulation of the sub-G1 population in HL-60 cells (P<0.05). Taken together, the results demonstrate that beta-escin is a potent natural inhibitor of cell proliferation and inducer of apoptosis in HL-60 acute myeloid leukaemia cells. The results indicate that beta-escin may be a useful candidate agent for exploring potential antileukaemic drugs.

Genotoxicity and cell death induced by tinidazole (TNZ)

Tinidazole (TNZ), a second-generation 5-nitroimidazole compound chemically related to metronidazole (MTZ), has been widely used throughout Europe and developing countries for the treatment of amoebic and parasitic infections. Despite TNZ's increasing use in therapeutics, scarce experimental reports are available in literature on its potential genotoxicity in human cells. Therefore, the aim of the present study was to achieve a precise characterization of the cytotoxic and genotoxic activities of this nitroimidazole in cultured human lymphocytes at therapeutic concentrations (0.1, 1, 10 and 50 μg/ml of culture) and evaluate the possible cell death mechanism associated with it. The endpoints analyzed included: mitotic index (MI), replication index (RI), sister chromatid exchange (SCE) and chromosomal aberrations (CA). A significant decrease ( p < 0.0001) in MI as well as an increase in SCE ( p < 0.0001) and CA ( p < 0.0001) frequencies were observed. No modifications in RI were found. The results suggest a genotoxic and cytotoxic effect of TNZ related with cell death process. Therefore, we evaluated this mechanism by DNA fragmentation (laddering), fluorescence microscopy using acridine orange/ethidium bromide (AO/EB) staining and flow cytometry propidium iodide (PI). DNA extracts of TNZ-treated cells resulted in nucleosomal DNA ladder pattern after 48 h of cell treatment; meanwhile no differences were detected in untreated cells. This pattern correlated with the observed decrease in cellular viability ( p < 0.05), morphological evidence of apoptosis and increase in the percentage of nuclei with hypodiploid DNA content of TNZ exposed cultures compared with control ( p < 0.05). We concluded that TNZ is genotoxic, cytotoxic and is able to modulate cell death through apoptotic mechanisms in the experimental design employed.

Progesterone facilitates cisplatin toxicity in epithelial ovarian cancer cells and xenografts

Objectives The underlying premise of these investigations was that the lipophilic hormone progesterone, which partitions into and (at relatively high concentrations) impedes the fluid mechanics of the plasmalemma, would perturb integral associations between membrane lipids and exporter pumps that otherwise confer drug resistance. That progesterone can affect susceptibility of ovarian adenocarcinoma cells and xenografts to cisplatin was tested. Methods The cisplatin-resistant human cell lines SKOV-3 and OVCAR-3 were treated for 24 hours with cisplatin (0.1 μg/ml) ± progesterone (0.01, 0.1 μg/ml). Cytotoxicity and platinum were measured by MTT assay and inductively coupled plasma mass spectrometry, respectively. Athymic mice were inoculated intraperitoneal (ip) with SKOV-3 cells. Cisplatin (2 mg/kg/week) ± progesterone (25 mg sustained-release pellet) regimens were initiated ip at one week (when micrometastases were present) and continued to six weeks post-xenograft. Tumor burdens, histopathology, and platinum concentrations were assessed upon necropsy at 24 hours after the final injection of cisplatin. Results There were no significant in vitro/vivo anticancer effects of cisplatin alone. High-dose progesterone enhanced platinum accretion and induced drug toxicity in both cell lines. Tumorigenesis was suppressed by cisplatin + progesterone. The treatment synergy was related to elevated tumor platinum and morphological evidence of apoptosis. Conclusion It appears that the addition of progesterone to ovarian cancer therapeutic modalities represents a step in improving responses.

Small interfering RNA‐mediated silencing of mitochondrial NADP+‐dependent isocitrate dehydrogenase enhances the sensitivity of HeLa cells toward tumor necrosis factor‐a and anticancer drugs

Tumor necrosis factor‐α (TNF‐α and several anticancer drugs induce the production of reactive oxygen species, which play an important causative role in apoptotic cell death. Recently, we demonstrated that the control of mitochondrial redox balance and the cellular defense against oxidative damage is one of the primary functions of mitochondrial NADP+‐dependent isocitrate dehydrogenase (IDPm) by supplying NADPH for antioxidant systems. In the present report, we show that silencing of IDPm expression in HeLa cells greatly enhances apoptosis induced by TNF‐α and anticancer drugs. Transfection of HeLa cells with an IDPm small interfering RNA (siRNA) markedly decreased activity of IDPm, enhancing the susceptibility of anticancer agent‐induced apoptosis reflected by morphological evidence of apoptosis, DNA fragmentation, cellular redox status, mitochondria redox status and function, and the modulation of apoptotic marker proteins. These results indicate that IDPm may play an important role in regulating the apoptosis induced by TNF‐α and anticancer drugs and the sensitizing effect of IDPm siRNA on the apoptotic cell death of HeLa cells offers the possibility of developing a modifier of cancer chemotherapy.

Beta-aescin: A potent natural inhibitor of proliferation and inducer of apoptosis in human chronic myeloid leukemia K562 cells in vitro

Beta-aescin, a natural triterpenoid saponin isolated from the seed of Chinese horse chestnut (Aesculus chinensis), is known to generate a wide variety of biochemical and pharmacological effects. In the present study, the authors investigated the anti-proliferative and apoptotic effects of beta-aescin in human chronic myeloid leukemia K562 cell line in vitro. The anti-proliferative effects were detected by CFU-K562 colony formation and cell viability assay. The apoptotic effects were analysed by morphological analysis, annexin V assay, DNA fragmentation assay and flow cytometry DNA content analysis. The results showed that beta-aescin exhibited potent dose- and time-dependent anti-proliferative effects in K562 cells. Morphological evidence of apoptosis, a significant increase of annexin V+ and PI− cells (early apoptotic) and apoptotic DNA fragmentation, were observed in cells treated with beta-aescin. Flow cytometry analysis revealed that beta-aescin could lead to an accumulation of sub G1 population in K562 cells, and suggesting a potential G1 phase accumulation in cell cycle profile of K562 cells. Our findings revealed that beta-aescin is a potent natural inhibitor of proliferation and inducer of apoptosis in K562 cells, and beta-aescin may be a candidate lead compound to explore potential antileukemia drugs.

Silencing of mitochondrial NADP +-dependent isocitrate dehydrogenase by small interfering RNA enhances heat shock-induced apoptosis

Heat shock may increase oxidative stress due to increased production of reactive oxygen species and/or the promotion of cellular oxidation events. Mitochondrial NADP +-dependent isocitrate dehydrogenase (IDPm) produces NADPH, an essential reducing equivalent for the antioxidant system. In this report, we demonstrate that silencing of IDPm expression in HeLa cells greatly enhances apoptosis induced by heat shock. Transfection of HeLa cells with an IDPm small interfering RNA (siRNA) markedly decreased activity of IDPm, enhancing the susceptibility of heat shock-induced apoptosis reflected by morphological evidence of apoptosis, DNA fragmentation, cellular redox status, mitochondria redox status and function, and the modulation of apoptotic marker proteins. These results indicate that IDPm may play an important role in regulating the apoptosis induced by heat shock and the sensitizing effect of IDPm siRNA on the apoptotic cell death of HeLa cells offers the possibility of developing a modifier of cancer therapy.