Caspase-independent Apoptosis Pathways Research Articles

The Effect of Hypertonic Osmotic Stress and Its Duration on the Level and Activity of Executioner Caspase Enzymes in Blood Anuclear Cells (Platelets)

Background: Caspases are protease enzymes critical for apoptosis. Caspase-3 and caspase-7, known as executioner caspases, are present in anuclear cells such as platelets. Platelet mitochondria can engage in the intrinsic pathway of apoptosis during stress and cellular damage. Hypertonic osmotic stress influences not only cell shape but also induces chemical changes within the cell. This study examines the function of executioner caspases in platelets under hypertonic osmotic stress due to the absence of a caspase-independent apoptosis pathway in these nucleus-free cells. Methods: Platelets were exposed to osmotic stress in a hypertonic environment (1.7% sodium chloride), with an isotonic environment (0.9% sodium chloride) serving as the control. Both environments were maintained at 37°C for durations of 15 minutes and 24 hours. Following this, platelets were lysed using ultrasound waves, and cellular membranes were removed by centrifugation. The supernatants were then used to measure caspase-3 levels (ng/mL) using an ELISA method and caspase-3/7 activity (nmol/min/l) using a colorimetric method. Results: The study confirmed the presence of executioner caspases in platelets under non-stressed isotonic conditions. Following 15 minutes and 24 hours of hypertonic osmotic stress, caspase-3 levels increased as determined by ELISA. However, caspase-3/7 activity initially decreased. With extended stress duration from 15 minutes to 24 hours, both the levels and activity of these enzymes increased significantly (P-value < 0.05). Conclusions: Exposure to a hypertonic osmotic environment containing 1.7% sodium chloride increases caspase-3 levels in anuclear cells such as platelets, while initially reducing caspase-3/7 activity. Prolonging the duration of stress to 24 hours enhances both the level and activity of these enzymes.

Effect of Pistacia Terebinthus (terebinth) resin extract on aggressive breast cancer cells.

Breast cancer is one of the most common types of cancer causing high mortality rates among women worldwide. This study was aimed to evaluate the effect of Pistacia terebinthus (terebinth) resin extract (TRE) on the MDA-MB-231 breast cancer cell line. In the study, the cytotoxic dose of the resin extract in MDA-MB-231 cells was evaluated by MTS analysis. The effect of TRE on apoptosis was examined by Hoechst staining. Caspase-3 and cleaved caspase-3 protein expressions were determined by western blot analysis. Based on the outcomes of our MTS analysis, the IC50 dose of TRE was calculated at 56.54μg/mL during a 24-h application period. With Hoechst staining analysis, an increase was observed in cells that underwent apoptotic change at 10 and 100μg/ml TRE concentrations compared to the control. At 25 and 50μg/mL TRE concentrations, no apoptotic change was found in comparison to the control; however, a significant drop in the number of viable cells was observed because 200, 300, and 500μg/mL TRE concentrations were above the toxic dose. The caspase-3 protein expression level was significantly higher in cells treated with 100μg/ml TRE compared to the control group, while there was no significant change in cleaved caspase-3 protein expression. It was thought that P. terebinthus resin might cause cell death in MDA-MB-231 cells via caspase-independent apoptosis pathway or other cell death pathways, and it was concluded that it could be a supportive treatment for breast cancer treatment.

Transcriptome study on immune response against Vibrio parahaemolyticus challenge in gill of abalone Haliotis discus hannai Ino

Abalone (Haliotis discus hannai Ino) is one of the most vital economic shellfish cultured in China. However, bacterial and viral infection often leads to its high mortality and serious economic losses. In this study, transcriptome sequencing was performed on gill of abalone challenged by Vibrio parahaemolyticus for 0 h (control group, A0h), 8 h (A8h), and 48 h (A48h), respectively. Each library has an average of 53,361,675 clean reads. Approximately 85.71% reads were mapped to the reference genome of Haliotis discus hannai Ino. In comparison with A0h group, 7,656 and 2,789 genes were differentially expressed in the A8h and A48h groups, respectively. The differentially expressed genes (DEGs) were mostly enriched in oxidation–reduction process and oxidoreductase activity from GO analysis as well as immunity and metabolism-related pathways from Kyoto Encyclopedia of Genes and Genomes analysis. Cluster analysis demonstrated that all DEGs were categorized into eight subclusters by adopting the gene expression model. Specifically, a total of 1,070 significantly downregulated genes from two clusters were related to some metabolic pathways, ABC transporters, and cell adhesion. Moreover, 212 upregulated genes in one subcluster were enriched in several immune-related pathways, including nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway and apoptosis. Some members of the pattern recognition receptors family, which can initiate inflammatory signaling and induce apoptosis, were stimulated to upregulate in gill after challenge including C1q, perlucin, and low-density lipoprotein receptor–related protein. In addition, caspase-dependent apoptosis pathway was inactive, whereas caspase-independent apoptosis pathway was stimulating in response to Vibrio challenge. To eliminate invading pathogen, the immune effectors such as interleukin-17, matrix metalloproteinase, lysozyme, superoxide, and ferritin were also stimulated in gill. Moreover, this study also provides more information for comprehending the immunity and defense mechanisms against V. parahaemolyticus infection in abalone.

Piracetam attenuates cyclophosphamide-induced hepatotoxicity in rats: Amelioration of necroptosis, pyroptosis and caspase-dependent apoptosis

AimsCyclophosphamide (Cyclo) is an immunosuppressive and antineoplastic agent. The clinical use of Cyclo is limited by significant hepatotoxicity. Piracetam (Pira) is used to improve cognitive function. Pira possesses diverse physiological functions; however, the exact mechanisms of its activity are still non-elucidated. Main methodsForty rats were allocated in four groups. 1st group comprised normal rats; the remaining groups received single Cyclo dose (200 mg/kg/i.p.) on the experiment's 15th day. 2nd group comprised Cyclo-control rats. 3rd & 4th groups received Pira (100 & 300 mg/kg body weight) for 15 days. Key findingsCyclo administration resulted in deterioration of serum liver function tests and elevation of hepatic tissue concentration of P53, Nf-kβ, apoptosis-inducing factor-1, NLRP3 inflammasome, Bax; gene expression of receptor-induced protein-1 along with reduction of hepatic Bcl-2 concentration. Bax/Bcl-2 ratio headed for apoptosis. Cyclo administration also resulted in a severe deterioration of the hepatic histopathological picture and significant immunohistochemical expression of caspase-3, tumor necrosis factor-alpha (TNF-α) and Cyclooxygenase-2 (COX-2) in hepatic tissues versus the normal group. Pira significantly improved all the aforementioned parameters, reallocating the Bax/Bcl-2 ratio to anti-apoptosis. Moreover, Pira treatment amended Cyclo-induced histopathological abnormalities and significantly reduced caspase-3, TNF-α plus COX-2 immunoreactivity in hepatic tissues. SignificanceThe present work is the first to link Cyclo-induced hepatotoxicity to the activation of caspase-independent apoptosis (necroptosis), pyroptosis and caspase-dependent apoptosis signaling pathways. Pira treatment significantly ameliorated Cyclo-induced hepatotoxicity mainly via the amendment of necroptotic, pyroptotic and caspase-dependent apoptotic changes along with the histopathological deformities in rats' hepatic tissues.

Barrientosiimonas humi ethyl acetate extract exerts cytotoxicity against MCF-7 and MDA-MB-231 cells via induction of apoptosis and cell cycle arrest

Objective: To elucidate the cytotoxic effect of the secondary metabolites of Barrientosiimonas humi (B. humi) on MCF-7 and MDA-MB-231 human breast cancer cells and its underlying mechanisms of action.Methods: The extract was obtained from the fermentation of B. humi and fractionation of the crude extract was conducted via column chromatography. Cytotoxicity of the B. humi extract was determined by using MTT assay and real-time cellular analysis. Morphological changes, cell cycle profiles, mode of cell death, and caspase expressions of control and treated breast cancer cells were determined.Results: The ethyl acetate extract isolated from B. humi was cytotoxic against MCF-7 and MDA-MB-231 cell lines. One of the dichloromethane (DCM) fractions, designated as DCM-F2, exhibited the strongest activity among all the fractions and thereby was selected for further studies. DCM-F2 had selective cytotoxicity on target cells by inducing apoptosis, particularly in the early stage, and cell cycle arrest. Treated cells caused inhibition of cell cycle progression at 72 h leading to a significant increase (P < 0.05) in the G0/G1 population. DCM-F2 treated MDA-MB-231 cells showed caspase-dependent apoptosis, whereas DCM-F2 treated MCF-7 cells showed a caspase-independent apoptosis pathway. Five compounds were successfully isolated from B. humi. Cyclo (Pro-Tyr) was the most cytotoxic and selective compound against MCF-7 cells.Conclusions: B. humi ethyl acetate extract exhibits significant cytotoxicity against MCF-7 and MDA-MB-231 cells via induction of apoptosis and cell cycle arrest.

Phenolic Extraction of Moringa Oleifera Leaves Induces Caspase-Dependent and Caspase-Independent Apoptosis through the Generation of Reactive Oxygen Species and the Activation of Intrinsic Mitochondrial Pathway in Human Melanoma Cells

Moringa oleifera Lam. has long been used to treat many diseases, including diabetes, aging, inflammatory, and cancer. Many studies have revealed that the crude extract of Moringa oleifera Lam. leaves possesses anticancer property. Therefore, in this study, the extract of Moringa oleifera leaves was fractionated using different solvents to figure out the most effective fraction for anti-proliferative effect on melanoma cells. Methanol extract (MO-ME), hexane fraction (MO-HE), chloroform fraction (MO-CH), ethyl acetate fraction (MO-EA), and water-soluble fraction (MO-WA) of Moringa oleifera leaves were prepared. Total phenolic and flavonoid contents were determined. The anti-proliferative activity on melanoma cells and normal cells was investigated using WST-1 assay. The apoptotic activity was assessed by testing DNA condensation, DNA fragmentation, and phosphatidylserine (PS) externalization. The expression of apoptosis-related genes, the mitochondrial depolarization, and reactive oxygen species (ROS) were then examined to clarify the underlying molecular mechanisms. In this regard, MO-ME, MO-EA, and MO-CH inhibited the proliferation of both A375 human melanoma cells and A2058 human melanoma cells, but had little effect on WS1 normal human skin fibroblasts and primary normal human dermal fibroblasts (NHDF). Among fractions, the phenolic-rich MO-EA markedly inhibited the growth of A375 cells in a dose- and time-dependent manner. The anti-proliferation was supposed to be mediated via apoptosis, which was demonstrated by the significant increase of condensed chromatin, DNA fragmentation, and PS externalization. The apoptosis was stimulated by enhanced ROS production and reduction of mitochondrial membrane potential. MO-EA activated Bax while reducing Bcl-2 expression, leading to an increase in Bax/Bcl-2 ratio. The mechanisms of cell death involved in activation of Caspase-3/7 and Caspase-9 (Caspase-dependent pathway), activation, and translocation of apoptosis-inducing factor (AIF) into the nucleus (Caspase-independent pathway). Our study indicated that the phenolic-rich fraction exerted significant anticancer effects on melanoma cells in vitro which involved in Caspase-dependent and Caspase-independent apoptosis pathways mediated by mitochondrial ROS. These results provided a fundament for the using of phenolic-rich fraction of Moringa oleifera leaves to treat skin cancer effectively.

О влиянии нового производного пиримидина PIR-4 на концентрацию маркеров внешнего и внутреннего путей апоптоза в условиях экспериментальной церебральной ишемии

Исследовано антиапоптотическое действие нового производного пиримидина под шифром PIR-4 в условиях экспериментальной фокальной церебральной ишемии у крыс линии Вистар, разделенных на 5 групп (n = 10). В первую группу включены ложнооперированные особи, вторая группа — крысы негативного контроля, получавшие взвесь очищенной воды и твина-80. Третья и четвертая группы представлены животными, получавшими препараты сравнения кавинтон (3,2 мг/кг) и глиатилин (60 мг/кг), соответственно. Пятой группе крыс вводили соединение PIR-4. Все соединения вводили сразу после моделирования ишемии и в течение 3 сут ежедневно. Модель фокальной ишемии мозга — окклюзия левой средней мозговой артерии (наркоз — хлоралгидрат, 350 мг/кг). В ходе проведенного исследования установлено, что на фоне моделируемой патологии возрастает концентрация фактора некроза опухоли (TNF-α), фактора, индуцирующего апоптоз (AIF), p53-зависимого модулятора апоптоза (PUMA), снижается уровень Jun-N-концевой киназы (JNK). Препараты сравнения кавинтон и глиатилин корректировали возникшие изменения, препятствуя развитию внешнего и внутреннего путей апоптоза. На фоне получения крысами вещества PIR-4 также уменьшал концентрацию маркеров каспаза-зависимого и каспаза-независимого путей апоптоза, при этом по антиапоптотическому эффекту, превосходя кавинтон и не уступая глиатилину.

Mitochondria-mediated Caspase-dependent and Caspase-independent apoptosis induced by aqueous extract from Moringa oleifera leaves in human melanoma cells.

Malignant melanoma is a very aggressive and serious type of cutaneous cancer. Previous studies indicated the anti-cancer activity of aqueous extract of Moringa oleifera Lam. leaves (MOE) against a variety of cell lines. However, there has not been much research about the effect of MOE on melanoma. Therefore, this study was about to investigate the anti-proliferation mediated by apoptosis of MOE on human melanoma cell lines. Furthermore, the related molecular mechanisms of the apoptosis were also examined. An aqueous extract of Moringa oleifera leaves was prepared and the anti-proliferative activity on melanoma cells and normal cells was tested using WST-1 assay. The apoptotic hallmarks including DNA condensation and phosphatidylserine (PS) externalization were assessed. The expression of apoptosis-related genes and the depolarization of mitochondrial membrane potential were then examined to clarify the underlying molecular mechanisms. MOE inhibited cell growth of A375 cells and A2058 cells in a dose-dependent manner but had little effect on human normal fibroblasts. The cell growth inhibition was induced by apoptosis which was expressed via chromatin condensation and PS externalization. MOE decreased mitochondrial membrane potential. Additionally, MOE increased Bax/Bcl-2 ratio, activated Caspase-3/7, Caspase-9, PARP and AIF translocation, leading to apoptotic cell death. Our study indicated that MOE exerted significant anti-cancer effects on melanoma cells in vitro which involved mitochondria-mediated Caspase-dependent and Caspase-independent apoptosis pathways. These results provided a scientific approach for using Moringa oleifera leaves as an alternative therapy to treat skin cancer.

Combined Administration of Poly-ADP-Ribose Polymerase-1 and Caspase-3 Inhibitors Alleviates Neuronal Apoptosis After Spinal Cord Injury in Rats

Neuronal apoptosis plays a pivotal role in spinal cord injury (SCI)-induced secondary cellular events. Caspase-dependent and -independent pathways are involved in neuronal apoptosis. Caspase-3 is the final effector of caspase-dependent apoptosis, whereas poly-ADP-ribose polymerase-1 (PARP-1) and apoptosis-inducing factor (AIF) are key executors of caspase-independent apoptosis. However, it remains unclear whether simultaneous inhibition of the 2 apoptosis pathways will be more beneficial for neuronal survival. Therefore, this study investigated the ability of coadministration of the PARP-1 inhibitor 3-aminobenzamide (3-AB) and caspase-3 inhibitor z-DEVD-fmk to attenuate apoptosis in a rat SCI model. The rats were subjected to moderate contusive SCI. Locomotor function was measured using the Basso, Beattie, and Bresnahan rating scales; neuronal apoptosis was detected using transferase-mediated deoxyuridine triphosphate-biotin nick end labeling; and immunohistochemistry and Western blotting were used to measure protein expression. We found the locomotor function of rats was weakened within 7 days post-SCI. At day 7 post-SCI, neuronal apoptosis dramatically increased and the expression of PARP-1, AIF, and cleaved caspase-3 was significantly upregulated. Further, Bcl-2 expression was significantly downregulated. The highest locomotor function recovery was recorded after the combined administration of 3-AB and z-DEVD-fmk for 7 days post-SCI when compared with 3-AB or z-DEVD-fmk administered alone. In addition, this combination therapy significantly reduced neuronal apoptosis by preventing upregulation of PARP-1 and AIF, inhibiting caspase-3 activation, and elevating Bcl-2 expression. These results suggest that combination therapy is beneficial for neuronal function recovery in rats with SCI. The underlying mechanism may be associated with cosuppression of caspase-dependent and caspase-independent apoptosis pathways.

Whole exome sequencing identifies a novel variant in an apoptosis-inducing factor gene associated with X-linked recessive hearing loss in a Chinese family.

We report on the genetic analysis of a Chinese family in which four male patients presented with postlingual progressive hearing loss, associated with distal muscle wasting and unsteady ataxic gait. Using whole exome sequencing, we identified a new pathogenic variant (c.1463C>T, p.Pro488Leu) in the AIFM1 gene, which encodes the apoptosis-inducing factor mitochondrion-associated 1 precursor. AIFM1 is involved in the mitochondrial respiratory chain and cellular caspase-independent apoptosis pathway and has been reported to cause multiple phenotypes including hearing loss. The p.Pro488Leu missense variant segregated with symptoms in the pedigree. It was not found in the dbSNP database, databases of genomes and SNPs in the Chinese population, in 74 patients with sporadic hearing loss, or in 108 normal individuals.We also verified that this AIFM1variant enhanced cell apoptosis rates compared in 293T cells transfected with wild-type AIFM1. Different variations of AIFM1 give rise to different phenotypes in patients, and this is the second reported family with a variant in the C-terminal domain of AIFM1 showing the phenotype of hearing loss and peripheral neuropathy.

HG30, a tetrahydroanthraquinone compound isolated from the roots of Prismatomeris connate, induces apoptosis in human non-small cell lung cancer cells

HG30, a tetrahydroanthraquinone compound isolated from the roots of Prismatomeris connate, was previously shown to inhibit the proliferation of A549 cells. The aim of this study was to evaluate the antitumor activity of HG30 in two non-small cell lung cancer cell lines, A549 and H1299, and to explore potential underlying mechanisms. In cell viability and colony formation assays, HG30 treatment suppressed the proliferation and number of colonies formed by A549 and H1299 cells. Western blot analysis further demonstrated that induction of apoptosis by HG30 in A549 and H1299 cells involves both caspase-dependent apoptosis pathways, including mitochondria- and death receptor-mediated pathways, and an apoptosis-inducing factor (AIF) -associated caspase-independent apoptosis pathway. Specifically, HG30 treatment affected Bcl-2 family proteins and inhibitor of apoptosis protein (IAP) family proteins by down-regulating of Mcl-1, survivin and XIAP and up-regulation of Bid, and Bim.

The interaction between the light source dose and caspase-dependent and -independent apoptosis in human SK-MEL-3 skin cancer cells following photodynamic therapy with zinc phthalocyanine: A comparative study

The aim of this study is to determine the behavior of relative expression of Bcl-2, caspase-8, caspase-9, and caspase-3 genes of/in SK-MEL-3 cancer cells and explore molecular mechanisms responsible for the apoptosis response during an in vitro photodynamic therapy (PDT) with Zinc Phthalocyanine (ZnPc) using different doses of the light source. In this study, firstly the cytotoxic effects of ZnPc-PDT on SK-MEL-3 cells were evaluated. By irradiating the laser, ZnPc induced a significant amount of apoptosis on SK-MEL-3 cells in three IC50s including 0.064±0.01, 0.043±0.01, and 0.036±0.01μg/mL at the doses of 8, 16, and 24J/cm2, respectively. Moreover, flow cytometry and QRT-PCR experiments were done. The high percentage of apoptotic cells was seen in the early apoptosis stage. The expression of Bcl-2 and caspase-8 genes at all doses of laser experienced an obvious reduction in comparison to the control group. On the other hand, although the expression of caspase-9 and caspase-3 genes remains almost constant at 8J/cm2, but they faced an increment at 16 and 24J/cm2 doses. These data reveal caspase-dependent apoptosis in high and caspase-independent apoptosis in low doses of laser. Based on the results of present work, it can be suggested that the dose of the light source is a key factor in induction of caspase-dependent and caspase-independent apoptosis pathways following PDT.

Abstract 2243: Elucidating the mechanism of action of molecular iodine on breast cancer cells

Abstract Each year, over 1.7 million women are diagnosed with breast cancer worldwide and about 35% of these diagnosed are expected to die from the disease. A significant barrier to improving treatment of breast cancer lies in our incomplete understanding of breast cancer initiation and metastasis. Regular use of molecular iodine has been shown to reduce the sensitivity of breast cells to the proliferative effects of estrogen, resulting in normalization of breast tissue.The aim of the current study was to evaluate the mechanisms of molecular iodine on two common breast cancer sub-types using well-established breast cancer cell lines. In order to study Luminal A and triple-negative breast cancer in vitro, MCF7 (cells from a luminal A subtype) and MDA-MB231 (cells from a triple-negative subtype), were treated with molecular iodine at various concentrations to measure proliferation and cell death. This was subsequently followed by gene expression analysis of key important molecular markers, which are primarily responsible for cell growth and apoptosis. Primary human mammary epithelial cells derived from healthy female donor were used as an internal control. Data from this study indicated that molecular iodine had potent inhibitory effects on cell growth and showed a dramatic increase in cell death in both breast cancer cell lines. Gene expression analysis using quantitative RT-PCR further confirmed that cell cycle genes controlling G1-S phase transition were largely up-regulated. Changes were not seen in Cyclin B expression levels, which further suggest that cells were arrested before entry into cell division. BCL-2, PPAR-α and PPAR-γ were also up-regulated along with down-regulation of Caspase 3, suggesting molecular iodine induced cell death through activation of a caspase-independent apoptosis pathway. Interestingly, mesenchymal-epithelial transition (MET) occurrence was noticed upon molecular iodine treatment as indicated by sharp increase of GATA3 and E-Cadherin and significant down-regulation of Vimentin in invasive MDA-MB231 cells. Our current study enables us to understand a molecular mechanism controlling tumor cell growth and demonstrates potent cellular effects of molecular iodine on breast cancer cell lines. These results also demonstrate promising effects of molecular iodine for regulation of breast cancer EMT differentiation, which is required for tumor initiation and metastasis. Further studies are underway to determine possible effects of molecular iodine in these breast cancer subtypes using in vitro 3D models. Note: This abstract was not presented at the meeting. Citation Format: Zack Xu, Xin Chen, Noymi Yam, kin Chan, Usha Nagavarapu. Elucidating the mechanism of action of molecular iodine on breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2243. doi:10.1158/1538-7445.AM2017-2243

Stimulation of Anterior Thalamic Nucleus Protects Hippocampus Neural Injury in Kainic Acid-Induced Epileptic Rats

Anterior nucleus of thalamus (ANT) stimulation has been proved to be effective in the treatment of refractory epilepsy, but the underlying mechanisms remain to be elucidated. We examined the role of ANT stimulation on hippocampal neuron death after seizures induced by kainic acid (KA). Our data showed that ANT stimulation could significantly rescue neurons from death induced by seizures, by reducing the release of cytochrome c (cyto c) and also via apoptosis-inducing factor (AIF) induced by seizures through inhibiting the activated caspase-9 and caspase-3. Our data suggest that ANT stimulation may protect against neuronal loss and reduce neuronal injury in the ipsilateral CA3 region of the hippocampus in the KA-induced epileptic rats, and the underlying mechanism may be mediated by inhibiting mitochondrial caspase-dependent (cyto c release and the subsequent cleavage of caspase-) and caspase-independent (nuclear translocation of AIF) apoptosis pathways.

Curcumin confers protection to irradiated THP-1 cells while its nanoformulation sensitizes these cells via apoptosis induction.

Protection against ionizing radiation (IR) and sensitization of cancer cells to IR are apparently contrasting phenomena. However, curcumin takes on these contrasting roles leading to either protection or enhanced apoptosis in different irradiated cells. Here we studied whether pretreatment with free curcumin or a novel dendrosomal nanoformulation of curcumin (DNC) could exert protective/sensitizing effects on irradiated THP-1 leukemia cells. We employed assays including MTT viability, clonogenic survival, DNA fragmentation, PI/Annexin V flow cytometry, antioxidant system (ROS, TBARS for lipid peroxidation, 8-OHdG and γH2AX for DNA damage, glutathione, CAT and GPx activity, enzymes gene expression), ELISA (NF-κB and Nrf2 binding, TNF-α release), caspase assay, siRNA silencing of caspase-3, and western blotting to illustrate the observed protective role of curcumin in comparison with the opposite sensitizing role of its nanoformulation at a similar 10μM concentration. The in vivo relevance of this concentration was determined via intraperitoneal administration in mice. Curcumin significantly enhanced the antioxidant defense, while DNC induced apoptosis and reduced viability as well as survival of irradiated THP-1 cells. Nrf2 binding showed an early rise and fall in DNC-treated cells, despite a gradual increase in curcumin-treated cells. We also demonstrated that DNC induced apoptosis in THP-1 cells via caspase-3 activation; whereas in combination with radiation, DNC alternatively employed a caspase-independent apoptosis pathway involving cytochrome c release from mitochondria.

Digitoxin enhances the growth inhibitory effects of thapsigargin and simvastatin on ER negative human breast cancer cells

BackgroundThe cardiac glycoside digitoxin preferentially inhibits the growth of breast cancer cells and targets the Erk pathway. Digitoxin alters the expression of genes that mediate calcium metabolism and IAP genes. PurposeSince the optimal treatment for cancer involves the use of agents in combination, we assessed the growth inhibitory effects of digitoxin combined with agents that alter calcium metabolism, thapsigargin, a sarcoplasmic/ER Ca2+-ATPase inhibitor, and the statin simvastatin, as well as digitoxin's effect on the IAP pathway of apoptosis. MethodsTo reveal signaling pathways, we treated human cancer cells with digitoxin, alone or combined with thapsigargin or simvastatin, and measured cell growth using the MTT and colony formation assays. We used histology and Western blot analysis of HEK293 cells to assay effects on IAPs. ResultsDigitoxin inhibited the growth of breast, colon and ovarian cancer cells. Consistent with an effect on calcium metabolism, digitoxin exhibited synergy with thapsigargin and simvastatin on ER-negative breast cancer cells. Digitoxin activates expression of Erk pathway genes and suppresses expression of IAP genes. The growth inhibitory effects on HEK293 cells are not blocked by the pancaspase inhibitor zVAD-FMK, indicating that digitoxin may act by a caspase independent pathway of apoptosis. Furthermore, digitoxin does not have an effect on XIAP protein, a major anti-apoptotic protein. ConclusionDigitoxin appears to act through the Erk and stress response pathways and is worthwhile to study to prevent and treat cancer. Our findings warn of possible safety issues for cardiac patients who take a combination of digitoxin and statins.

Carbon ion beam triggers both caspase-dependent and caspase-independent pathway of apoptosis in HeLa and status of PARP-1 controls intensity of apoptosis.

High linear energy transfer (LET) carbon ion beam (CIB) is becoming very promising tool for various cancer treatments and is more efficient than conventional low LET gamma or X-rays to kill malignant or radio-resistant cells, although detailed mechanism of cell death is still unknown. Poly (ADP-ribose) polymerase-1 (PARP-1) is a key player in DNA repair and its inhibitors are well-known as radio-sensitizer for low LET radiation. The objective of our study was to find mechanism(s) of induction of apoptosis by CIB and role of PARP-1 in CIB-induced apoptosis. We observed overall higher apoptosis in PARP-1 knocked down HeLa cells (HsiI) compared with negative control H-vector cells after irradiation with CIB (0-4Gy). CIB activated both intrinsic and extrinsic pathways of apoptosis via caspase-9 and caspase-8 activation respectively, followed by caspase-3 activation, apoptotic body, nucleosomal ladder formation and sub-G1 accumulation. Apoptosis inducing factor translocation into nucleus in H-vector but not in HsiI cells after CIB irradiation contributed caspase-independent apoptosis. Higher p53 expression was observed in HsiI cells compared with H-vector after exposure with CIB. Notably, we observed about 37% fall of mitochondrial membrane potential, activation of caspase-9 and caspase-3 and mild activation of caspase-8 without any detectable apoptotic body formation in un-irradiated HsiI cells. We conclude that reduction of PARP-1 expression activates apoptotic signals via intrinsic and extrinsic pathways in un-irradiated cells. CIB irradiation further intensified both intrinsic and extrinsic pathways of apoptosis synergistically along with up-regulation of p53 in HsiI cells resulting overall higher apoptosis in HsiI than H-vector.

A novel triterpenoid isolated from apple functions as an anti-mammary tumor agent via a mitochondrial and caspase-independent apoptosis pathway.

A novel triterpenoid, named 3β-trans-cinnamoyloxy-2α-hydroxy-urs-12-en-28-oic acid (CHUA), was one of the main components of apple peels and showed potent in vitro antitumor activity against human tumor cells. In vivo antitumor experiments showed that CHUA could significantly inhibit the growth of mammary tumor in a nude mouse xenograft model at a dose of 50 mg/kg/day without body weight loss and mortality. In vitro, CHUA could induce apoptosis in MDA-MB-231 cells through the detection of DNA fragments and LDH activity. Simultaneously, mitochondrial transmembrane potential was markedly reduced and the release of cytochrome c was increased after CHUA treatment. It also up-regulated the expression ratio of mitochondrial Bax/Bcl-2 regulated by SIRT1 and p53. Interestingly, z-VAD-fmk and z-DEVD-fmk augmented cell death after CHUA treatment. Other protease(s) different from caspase-3 might be responsible for the degradation of PARP. These results suggested that the pro-apoptotic activity of CHUA may be adjusted by mitochondrial and caspase-independent pathways.

Pro-apoptotic effects of the novel tangeretin derivate 5-acetyl-6,7,8,4'-tetramethylnortangeretin on MCF-7 breast cancer cells.

Citrus polymethoxyflavone tangeretin (5,6,7,8,4'-pentamethoxyflavone, TAN) displays multiple biological activities, but previous reports showed that TAN failed to induce MCF-7 human breast cancer cells apoptosis. Herein, we prepared 5-acetyl-6,7,8,4'-tetramethylnortangeretin (5-ATAN), and evaluated its cytotoxicity on MCF-7 cells. 5-ATAN revealed stronger cytotoxicity than that of parent TAN in the growth inhibition of MCF-7 cells. 5-ATAN induced apoptosis via both caspase-independent and -dependent pathways, in which 5-ATAN induced the translocation of apoptosis inducing factor and phosphorylation of H2AX as well as poly (ADP-ribose) polymerase cleavage, caspase-3 activation. However, 5-ATAN did not affect extrinsic markers caspase-8, BID, and FADD. Further, 5-ATAN induced the loss of mitochondrial membrane potential (Δψm) by regulating the Bax/Bcl-2 ratio. Loss of Δψm led to the mitochondrial release of cytochrome c which triggered activation of caspase-9. In conclusion, these data indicate that 5-ATAN plays pro-apoptotic cytotoxic roles in MCF-7 cells through both caspase-dependent intrinsic apoptosis and caspase-independent apoptosis pathways.

Activation of extrinsic- and Daxx-mediated pathways in lymphoid tissue of PRRSV-infected pigs

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is a major infectious pathogen in pigs leading to huge economical losses worldwide. PRRSV is able to escape from host immunity and causes transient infections. In the present study, expression of different apoptotic markers and its connection with PRRSV were assessed in tonsil and mediastinal lymph node from PRRSV-infected pigs. Cleaved caspase (CCasp)8, CCasp9, Fas, Daxx, CCasp3 and PRRSV expression were analyzed by immunohistochemistry. An up-regulation of CCasp8, Fas and CCasp3 expression in lymphocytes and macrophages from both organs was found during PRRSV infection, indicating the activation of the extrinsic-mediated pathway of apoptosis. Moreover, Daxx expression was also enhanced in macrophages of both organs, suggesting a simultaneous caspase-independent pathway of apoptosis. A correlation between the expression of the different apoptotic markers and IL-10, IL-6 and TGF-β but not with PRRSV antigen was found in our study, which supports the hypothesis of an indirect mechanism in PRRSV-induced apoptosis.