Sunga Choi

Cordyceps pruinosa extracts induce apoptosis of HeLa cells by a caspase dependent pathway.

AIM OF THE STUDY Cordyceps is a parasitic fungus and has long been used as a traditional Chinese medicine to treat illnesses, promote longevity, increase athletic power, and relieve exhaustion and cancer. In this study, we reveal the mechanisms underlying apoptosis induced by Cordyceps pruinosa butanol fraction (CPBF) in the human cervical adenocarcinoma cell line, HeLa. MATERIALS AND METHODS Proliferation and apoptosis of cells were examined by MTT assay, DNA fragmentation, phosphatidyl serine distribution assay, Western blot analysis, and immunocytochemistry. To determine the association between CPBF related apoptosis and ROS, electron spin resonance (ESR) trapping experiments were used. RESULTS CPBF inhibited proliferation and induced apoptosis in HeLa cells in a dose-dependent manner using a MTT assay, DNA fragmentation, and a phosphatidyl serine distribution assay. Western blot analysis showed that apoptosis in HeLa cells was caspase-3- and -9-dependent. Proteolytic cleavage of PARP and the release of cytochrome c from the mitochondria into the cytosol were significantly increased and the Bcl-2/Bax protein ratio was decreased. Apoptosis induced by CPBF was not prevented by various antioxidants. CONCLUSIONS These results indicate that apoptotic effects of CPBF on HeLa cells are mediated by mitochondria-dependent death-signaling pathway independent of reactive oxygen species, suggesting that CPBF might be effective as an anti-proliferative agent for cancer.

Cordycepin-induced apoptosis and autophagy in breast cancer cells are independent of the estrogen receptor

Cordycepin (3-deoxyadenosine), found in Cordyceps spp., has been known to have many therapeutic effects including immunomodulatory, anti-inflammatory, antimicrobial, and anti-aging effects. Moreover, anti-tumor and anti-metastatic effects of cordycepin have been reported, but the mechanism causing cancer cell death is poorly characterized. The present study was designed to investigate whether the mechanisms of cordycepin-induced cell death were associated with estrogen receptor in breast cancer cells. Exposure of both MDA-MB-231 and MCF-7 human breast cancer cells to cordycepin resulted in dose-responsive inhibition of cell growth and reduction in cell viability. The cordycepin-induced cell death in MDA-MB-231 cells was associated with several specific features of the mitochondria-mediated apoptotic pathway, which was confirmed by DNA fragmentation, TUNEL, and biochemical assays. Cordycepin also caused a dose-dependent increase in mitochondrial translocation of Bax, triggering cytosolic release of cytochrome c and activation of caspases-9 and -3. Interestingly, MCF-7 cells showed autophagy-associated cell death, as observed by the detection of an autophagosome-specific protein and large membranous vacuole ultrastructure morphology in the cytoplasm. Cordycepin-induced autophagic cell death has applications in treating MCF-7 cells with apoptotic defects, irrespective of the ER response. Although autophagy has a survival function in tumorigenesis of some cancer cells, autophagy may be important for cordycepin-induced MCF-7 cell death. In conclusion, the results of our study demonstrate that cordycepin effectively kills MDA-MB-231 and MCF-7 human breast cancer cell lines in culture. Hence, further studies should be conducted to determine whether cordycepin will be a clinically useful, ER-independent, chemotherapeutic agent for human breast cancer.

Anti-glutamatergic effect of riluzole: comparison with valproic acid.

Riluzole, an anti-amyotrophic lateral sclerosis drug, known to decrease presynaptic glutamate release, is viewed as a candidate supplementary medication for epilepsy. In the present study, we compared the effects of riluzole and valproate (VPA) in the pilocarpine-induced limbic seizure model and in the gamma-hydroxybutyrate lactone (GBL)-induced absence seizure model. We applied immunohistochemical study for vesicular transporter 1 (VGLUT1) and extracellular recording in the rat dentate gyrus of both pilocarpine- and GBL-induced seizure models to measure effects of riluzole and VPA. Both VPA and riluzole treatments reduced VGLUT1 immunoreactivity. Riluzole treatment completely inhibited pre-ictal spikes and spike-wave discharges in the pilocarpine- and GBL-induced epilepsy models, whereas VPA partially inhibited these phenomena. In both seizure models, the anti-epileptic effects of VPA and riluzole are basically related to anti-glutamatergic (reducing field excitatory postsynaptic potential slope and excitability ratio), not GABAergic (paired-pulse inhibition) effect. Riluzole was more effective at reducing seizure activity in both epilepsy models than VPA. These results suggest that riluzole is a potential antiepileptic drug with activity against limbic seizure and absence seizure.

Valproic acid reduces enhanced vesicular glutamate transporter immunoreactivities in the dentate gyrus of the seizure prone gerbil

To elucidate the relationship between glutamatergic current and vesicular glutamate transporter (VGLUT) expressions, we performed the comparative analyses of evoked potentials and VGLUT immunoreactivities in the dentate gyrus, and its response to antiepileptic drug treatments in a gerbil model. The EPSP slope that could be evoked in seizure sensitive (SS) gerbils was significantly greater than in seizure resistant (SR) gerbils. There was also a strong trend towards the larger population spike amplitude in SS gerbils. In addition, VGLUT immunoreactivities were markedly enhanced in the dentate gyrus of SS gerbils, as compared with the SR gerbils. Following valproic acid (VPA, 30 mg/kg), the population spike amplitude and the EPSP slope in response to the stimulus were markedly reduced in the dentate gyri both of SR and of SS gerbils, although this dosage of VPA had no effect in low stimulus currents in SS gerbils. Vigabatrin (VGB) and low dosage of VPA treatment did not affect the evoked responses. Similarly, VPA treatment reduced enhanced VGLUT immunoreactivities in the dentate gyrus of SS gerbils, whilst VGB did not. These findings suggest that up-regulation of VGLUT immunoreactivities may be related to the hyperexcitability of granule cells in SS gerbils, and altered VGLUT immunoreactivity in the dentate gyrus may be independent of GABAergic transmission.

Ginsenoside Rh2 induces Bcl‐2 family proteins‐mediated apoptosis in vitro and in xenografts in vivo models

The cancer chemoprevention effects of ginseng saponins have been demonstrated against a variety of experimental tumors; however, their molecular mechanisms in vitro and in in vivo models are not well studied. This study was undertaken to gain insights into the molecular mechanisms of ginsenoside Rh2 (Rh2)‐induced cell death in human breast cancer cell lines as well as in in vivo xenografts. Rh2 treatment significantly inhibited viability of both MCF‐7 and MDA‐MB‐231 human breast cells in a concentration‐dependent manner, which correlated with mitochondria‐mediated apoptosis. Rh2‐induced apoptosis was accompanied by the down‐regulation of antiapoptotic proteins Bcl‐2, Bcl‐xL, and Mcl‐1. It also caused induction of the proapoptotic members Bak, Bax, and Bim leading to mitochondrial translocation of Bax and activation of caspases. Moreover, Rh2‐induced apoptosis was partially, yet significantly protected by transient transfection of MCF‐7 cells with Bax‐ and Bak‐targeted siRNAs. Oral gavage of 5 mg Rh2/kg of mouse (three times a week) significantly caused apoptosis of MDA‐MB‐231 xenografts. An increase in Bax and Bak and a decrease in Bcl‐2 and Bcl‐xL transcript levels, in accordance with their protein expression, were observed in tumor tissue. Tumors from Rh2‐treated mice exhibited a markedly higher count of apoptotic bodies and reduced proliferation index compared with control tumors. Our data suggest that Rh2 used in traditional oriental medicine for the treatment of various ailments, may be an attractive agent for the treatment and/or prevention of human breast cancers. J. Cell. Biochem. 112: 330–340, 2011.

Peripheral benzodiazepine receptor regulates vascular endothelial activations via suppression of the voltage-dependent anion channel-1

Peripheral benzodiazepine receptor (PBR) is a multifunctional protein mainly found on the outer mitochondrial membrane. PBR expression is increased by tumor necrosis factor‐α (TNF‐α) in endothelial cells. Adenoviral overexpression of PBR inhibits monocyte adhesion, VCAM‐1, and ICAM‐1 expression in TNF‐α‐activated endothelial cells. Rotenone, cyclosporine A, and bongkrekic acid suppress TNF‐α‐induced VCAM‐1 expression. Overexpression of PBR inhibits voltage‐dependent anion channel‐1 (VDAC‐1) expression and the silencing of PBR increases VDAC‐1 expression in endothelial cells. Moreover, TNF‐α‐induced VCAM‐1 expression is suppressed by VDAC‐1 gene silencing. PBR overexpression significantly decreases TNF‐α‐induced mitochondrial reactive oxygen species and MnSOD expression. These results suggest that PBR can inhibit endothelial activation and this action is related to the inhibition of mitochondrial ROS and/or VDAC‐1 expression in endothelial cells.

Reduced calcium binding protein immunoreactivity induced by electroconvulsive shock indicates neuronal hyperactivity, not neuronal death or deactivation.

Calcium-binding proteins (CBPs), such as parvalbumin and calbindin D-28k, are useful markers of specific neuronal types in the CNS. In recent studies, expression of CBPs may be indicative of a deactivated neuronal state, particularly epilepsy. However, it is controversial whether altered expression of CBPs in the hippocampus practically indicate neuronal activity. Therefore, the present study was performed to investigate the extent of profiles of expression of CBPs in the rat hippocampus affected by several episodes induced by electroconvulsive shock. In the present study, following electroconvulsive shock expression of CBPs were reduced in the hippocampus in a stimulus-dependent manner, and recovered to the control level at 6 h after electroconvulsive shock. However, paired-pulse responses of the dentate gyrus were transiently impaired by electroconvulsive shock, and immediately normalized to baseline value. In addition, effects of electroconvulsive shock on expression of CBPs and paired-pulse responses were prevented by pretreatment of vigabatrin. These findings suggest that reduced expression of CBPs induced by seizure activity may be indicative of hyperactivity of CBP positive neurons, which is a practical consequence of the abnormal discharge, and that they may play an important role in regulating seizure activity.

Histone deacetylases inhibitor trichostatin A modulates the extracellular release of APE1/Ref-1.

Apurinic/apyrimidinic endonuclease 1/Redox factor-1 (APE1/Ref-1) can be acetylated via post-translational modification. We investigated the effect of an inhibitor of histone deacetylases on the extracellular release of APE1/Ref-1 in HEK293 cells. Trichostatin A (TSA), an inhibitor of histone deacetylases, induced APE1/Ref-1 secretion without changing cell viability. In a fluorescence quantitative assay, the secreted APE1/Ref-1 was estimated to be about 10 ng/mL in response to TSA (1 μM). However, TSA did not induce the secretion of lysine-mutated APE1/Ref-1 (K6R/K7R). TSA also caused nuclear to cytoplasmic translocation of APE1/Ref-1. Taken together, these findings suggest that APE1/Ref-1 is a protein whose secretion is governed by lysine acetylation.

F-actin depolymerization accelerates clasmatodendrosis via activation of lysosome-derived autophagic astroglial death.

Clasmatodendrosis is an irreversible astroglial degenerative change, which includes extensive swelling and vacuolization of cell bodies and disintegrated and beaded processes. Since alteration in F-actin level influences on the formation of vacuoles/vesicles during exocytosis/endocytosis in astrocytes, we investigated whether F-actin polymerization involves clasmatodendrosis in the rat hippocampus following status epilepticus (SE). In the present study, vacuoles in clasmatodendrotic astrocytes showed LAMP-1 and LC3-II (a marker for autophagy) immunoreactivity. These findings reveal that clasmatodendrosis may be lysosome-derived autophagic astroglial death. Jasplakinolide (an F-actin stabilizer) infusion significantly decreased the size and the number of medium/large-sized vacuoles in each clasmatodendritic astrocyte accompanied by enhancement of phalloidin signals, as compared to vehicle-infusion. In contrast, latrunculin A (an F-actin-depolymerizing agent) infusion increased the size and the number of medium/large-sized vacuoles, which were dissociated adjacent to cell membrane. Therefore, our findings suggest that F-actin stabilization may inhibit lysosome-derived autophagic astroglial death during clasmatodendrosis.

APE1/Ref-1 as a Serological Biomarker for the Detection of Bladder Cancer

Purpose Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein that shows elevated expression in a number of cancers. We attempted to determine whether serum APE1/Ref-1 is elevated in patients with bladder cancer. Materials and Methods Serum APE1/Ref-1 levels were determined using enzyme-linked immunosorbent assay in serum from patients with bladder cancer who had not received chemotherapy or radiotherapy (n=51) and non-tumor controls (n=55). The area under the receiver operating characteristic area under the curve was applied to determine the correlation between clinical factors and the serum levels of APE1/Ref-1. Results Serum levels of APE1/Ref-1 in bladder cancer patients were significantly elevated compared to those of the control group (3.548±0.333 ng/100 μL [n=51] for bladder cancer vs. 1.547±0.319 ng/100 μL [n=55] for the control group), with a sensitivity and specificity of 93% and 59%, respectively. Serum APE1/Ref-1 levels are associated with tumor stage, grade, muscle invasion, and recurrence. Conclusion Serum APE1/Ref-1 might be useful as a potential serologic biomarker for bladder cancer.