The mitochondrial death pathway: a promising therapeutic target in diseases

Curcumin attenuates resistance to irinotecan via induction of apoptosis of cancer stem cells in chemoresistant colon cancer cells

Resistance to conventional chemotherapeutic agents, including irinotecan (CPT‑11), 5-fluorouracil and capecitabine is a major cause for therapeutic failure in patients with colorectal cancer (CRC). Increasing evidence has demonstrated that cancer cells exhibiting stem cell-like characteristics are associated with the development of resistance to chemotherapeutic agents. As a plant polyphenol, curcumin has been demonstrated to have the ability to ameliorate resistance of CRC to chemotherapeutic agents, but the associations among curcumin, cancer stem cells (CSCs) and chemoresistance of CRC remain unclear. The present study established a CPT‑11-resistant colon cancer cell line, LoVo/CPT‑11 cells, and detected the expression levels of CSC identification markers [cluster of differentiation (CD)44, CD133, epithelial cell adhesion molecule (EpCAM) and CD24] in parental cells and CPT‑11-resistant cells. It was revealed that the expression levels of the colon CSC markers in LoVo/CPT‑11 cells were significantly higher compared those in parental cells at the mRNA and protein level. The effect of curcumin on the chemoresistance to CPT‑11 and the expression levels of CSC identification markers in LoVo/CPT‑11 cells separately treated with curcumin and CPT‑11 were further investigated. The results revealed that curcumin significantly attenuated chemoresistance to CPT‑11, and treatment with curcumin resulted in a significant reduction of the expression levels of CSC identification markers. Furthermore, a tumor sphere formation assay was used to enrich colon CSCs from LoVo/CPT‑11 cells, and demonstrated that curcumin efficiently diminished the traits of colon CSCs, as evidenced by the inability to form tumor spheres, the reduction in the expression of CSC identification markers, and apoptosis-induced effects on sphere-forming cells treated with curcumin alone or in combination with CPT‑11. Altogether, the present data demonstrated that curcumin attenuated resistance to chemotherapeutic drugs through induction of apoptosis of CSCs among colon cancer cells. These findings may provide novel evidence for the therapeutic application of curcumin in CRC intervention.

Sonodynamic therapy: A potential treatment for atherosclerosis

Atherosclerosis (AS), a chronic arterial disease, is one of the major causes of morbidity and mortality worldwide. Several treatment modalities have been demonstrated to be effective in treating AS; however, the mortality rate due to AS remains high. Sonodynamic therapy (SDT) is a promising new treatment using low-intensity ultrasound in combination with sonosensitizers. Although SDT was developed from photodynamic therapy (PDT), it has a stronger tissue-penetrating capability and exhibits a more focused effect on the target lesional site requiring treatment. Furthermore, SDT has been demonstrated to suppress the formation of atheromatous plaques, and it can increase plaque stability both in vitro and in vivo. In this article, we critically summarize the recent literature on SDT, focusing on its possible mechanism of action as well as the existing and newly discovered sonosensitizers and chemotherapeutic agents for the treatment of AS.

PEP‑1‑glutaredoxin 1 protects against hippocampal neuronal cell damage from oxidative stress via regulation of MAPK and apoptotic signaling pathways

Oxidative stress is known to be a primary risk factor for neuronal diseases. Glutaredoxin (GLRX)‑1, a redox‑regulator of the thioredoxin superfamily, is known to exhibit an important role in cell survival via various cellular functions. However, the precise roles of GLRX1 in brain ischemia are still not fully understood. The present study investigated whether transduced PEP‑1‑GLRX1 protein has protective effects against oxidative stress in cells and in an animal model. Transduced PEP‑1‑GLRX1 protein increased HT‑22 cell viability under oxidative stress and this fusion protein significantly reduced intracellular reactive oxygen species and levels of DNA damage. In addition, PEP‑1‑GLRX1 protein regulated RAC‑a serine/threonine‑protein kinase and mitogen‑activated protein kinase signaling, in addition to apoptotic signaling including B cell lymphoma (Bcl)‑2, Bcl‑2 associated X, apoptosis regulator, pro‑caspase‑9 and p53 expression levels. In an ischemic animal model, it was verified that PEP‑1‑GLRX1 transduced into the Cornu Ammonis 1 region of the animal brain, where it markedly protected against ischemic injury. These results indicate that PEP‑1‑GLRX1 attenuates neuronal cell death resulting from oxidative stress in vitro and in vivo. Therefore, PEP‑1‑GLRX1 may exhibit a beneficial role in the treatment of neuronal disorders, including ischemic injury.

Effective elimination of adult B-lineage acute lymphoblastic leukemia by disulfiram/copper complex in vitro and in vivo in patient-derived xenograft models

Disulfiram (DS), a clinically used drug to control alcoholism, has displayed promising anti-cancer activity against a wide range of tumors. Here, we demonstrated that DS/copper (Cu) complex effectively eliminated adult B-ALL cells in vitro and in vivo in patient-derived xenograft (PDX) humanized mouse models, reflected by inhibition of cell proliferation, induction of apoptosis, suppression of colony formation, and reduction of PDX tumor growth, while sparing normal peripheral blood mononuclear cells. Mechanistically, these events were associated with disruption of mitochondrial membrane potential and down-regulation of the anti-apoptotic proteins Bcl-2 and Bcl-xL. Further analysis on B-ALL patients' clinical characteristics revealed that the ex vivo efficacy of DS/Cu in primary samples was significantly correlated to p16 gene deletion and peripheral blood WBC counts at diagnosis, while age, LDH level, extramedullary infiltration, status post intensive induction therapy, immune phenotype, risk category, and Ph chromosome had no effect. Together, these findings indicate that disulfiram, particularly when administrated in combination with copper, might represent a potential repurposing agent for treatment of adult B-ALL patients, including those clinically characterized by one or more adverse prognostic factors.

Mitochondrial-Targeting Lonidamine-Doxorubicin Nanoparticles for Synergistic Chemotherapy to Conquer Drug Resistance

Lonidamine (LND) can act on mitochondria and inhibit energy metabolism in cancer cells and therefore has been used together with chemotherapy drugs for synergistically enhanced therapeutic efficacy. However, its use is hindered by the poor solubility and slow diffusion in the cytoplasm. To address these problems, we designed and prepared aqueous dispersible nanoparticles (NPs) containing integrated components including triphenylphosphine (TPP) to target the mitochondria of cells and LND and doxorubicin (DOX) for synergistic cancer treatment and conquering drug resistance. This design allows the NPs to concentrate in the mitochondria of cells, solve the low solubility of LND, and contain very high load of LND and DOX in comparison with previously reported drug-delivery systems based on various carrier nanomaterials. Detailed mechanism studies reveal that TPP-LND-DOX NPs could induce significant reactive oxygen species production, mitochondrial membrane potential decrease, and mitochondrial apoptosis pathway, thereby leading to great cytotoxicity in cancer cells. In vivo anticancer activities indicate that TPP-LND-DOX NPs exhibit the highest efficacy in tumor inhibition among all tested groups and show high effectiveness in drug-resistant model. This work demonstrates the potential use of our TPP-LND-DOX NPs to jointly promote the mitochondria apoptosis pathway and contribute to conquer drug resistance in cancer therapy.

Antitumor effect of Quercetin on Y79 retinoblastoma cells via activation of JNK and p38 MAPK pathways

Background

Quercetin (QCT) is a flavonol present in many vegetables, it is proved to show chemo preventive effect against lung, cervical, prostate, breast and colon cancer due to its anti-inflammatory, anti-tumor and anti-oxidant property. Looking into the reported chemo-preventive effect we speculated antitumor activity in retinoblastoma (RB) Y79 cells, we also studied the molecular mechanism for antitumor activity.

Methods

The effect of QCT on Y79 cell viability count was done by cell counting kit, cell cycle distribution, apoptosis studies and mitochondrial membrane potential was evaluated by flow cytometry. Protein expression was done by western blot analysis.

Results

The outcomes of study showed that QCT reduced Y79 cell viability and caused arrest of G1 phase in cell cycle via decreasing the expression levels of cyclin-dependent kinase (CDK)2/6 and cyclin D3 and by increasing the levels of both CDK inhibitor proteins p21 and p27. Apoptosis of Y79 cells mediated by QCT occurred via activation of both caspases-3/-9. Flow cytometry studies showed that QCT caused collapse in mitochondrial membrane potential (ΔΨm) in Y79 cells. Western blot studies confirmed that QCT brought about phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). We also established that inhibitors of JNK and p38 MAPK suppressed QCT mediated activation of both caspases-3/-9 and subdued the apoptosis of cancerous Y79 cells.

Conclusion

All the results of the study suggest that QCT induced the apoptosis of Y79 cells via activation of JNK and p38 MAPK pathways, providing a novel treatment approach for human RB.

Protective Effects of Hesperidin (Citrus Flavonone) on High Glucose Induced Oxidative Stress and Apoptosis in a Cellular Model for Diabetic Retinopathy

The aim of this study was to investigate the protective effects and mechanisms of hesperidin, a plant based active flavanone found in citrus fruits, under the oxidative stress and apoptosis induced by high levels of glucose in retinal ganglial cells (RGCs). RGC-5 cells were pretreated with hesperidin (12.5, 25, or 50 μmol/L) for 6 h followed by exposure to high (33.3 mmol/L) d-glucose for 48 h. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was adopted to evaluate cell viability. Mitochondrial function was estimated by measuring the mitochondrial membrane potential (ΔΨm). A fluorescent probe was employed to evaluate the intercellular production of reactive oxygen species (ROS). Colorimetric assay kits were used to evaluate lipid peroxidation, antioxidant enzyme activities, and protein carbonyls formation. The expression of apoptosis-related proteins and mitogen-activated protein kinase (MAPK) were measured with Western blotting. Hesperidin inhibited high glucose-mediated cell loss and restored mitochondrial function including a reversion of ΔΨm loss and cytochrome c release. Treated with hesperidin, high glucose-induced increase in ROS, malondialdehyde, and protein carbonyl levels were blocked in RGC-5 cells. Hesperidin was found to elevate the activities of superoxide dismutase, catalase, glutathione peroxidase, and to recover glutathione levels. Hesperidin inhibited high glucose-induced cell apoptosis by attenuating the downregulation of caspase-9, caspase-3, and Bax/Bcl-2. Furthermore, the phosphorylation of c-Jun N-terminal kinases (JNK) and p38 MAPK triggered by high glucose were attenuated in RGC-5 cells after their incubation with hesperdin. We concluded that hesperidin may protect RGC-5 cells from high glucose-induced injury since it owns the properties of antioxidant action and blocks mitochondria-mediated apoptosis.

Cancer-mitochondria-targeted photodynamic therapy with supramolecular assembly of HA and a water soluble NIR cyanine dye

Mitochondria-targeted cancer therapies have proven to be more effective than other similar non-targeting techniques, especially in photodynamic therapy (PDT). Indocyanine dye derivatives, particularly IR-780, are widely known for their PDT utility. However, poor water solubility, dark toxicity, and photobleaching are limiting factors for these dyes, which otherwise show promise based on their good absorption in the near-infrared (NIR) region and mitochondria targeting ability. Herein, we introduce an indocyanine derivative (IR-Pyr) that is highly water soluble, exhibiting higher mitochondrial targetability and better photostability than IR-780. Furthermore, electrostatic interactions between the positively charged IR-Pyr and negatively charged hyaluronic acid (HA) were utilized to construct a micellar aggregate that is selective towards cancer cells. The cancer mitochondria-targeted strategy confirms high PDT efficacy as proved by in vitro and in vivo experiments.

Sensitization of neuroblastoma for vincristine-induced apoptosis by Smac mimetic LCL161 is attended by G2 cell cycle arrest but is independent of NFκB, RIP1 and TNF-α

We demonstrated sensitization for chemotherapy by Smac mimetic (SM) LCL161, a potent antagonist of inhibitor of apoptosis proteins (IAP), in neuroblastoma (NB). Vinca alkaloids, particularly vincristine (VCR), displayed the strongest impact on inhibition of proliferation and apoptosis induction in combination with LCL161. The underlying signaling pathways remain elusive, though. LCL161 induces a quick degradation of cellular IAP 1 (cIAP-1). Combination of LCL161 with VCR had only marginal effects on X-linked IAP (XIAP) protein expression. Cell death is accompanied by activation of intrinsic (caspase-9 and MMP) and extrinsic (caspase-8) pathways of apoptosis, repression of migratory potential and cell cycle arrest in G2 phase.

LCL161-induced cIAP degradation leads to activation of non-canonical and blockade of canonical NF-κB pathways but not induction of apoptosis. Surprisingly NF-κB and TNF-α signaling is negligible for VCR- and VCR/LCL161-induced apoptosis since chemical inhibition of NF-κB using BAY-7085 and PBS-1086, as well as application of TNF-α blocking antibody Humira (adalimumab) has no relevant effect on cell death. Recently formation of a TNF-α-independent complex (ripoptosome) consisting of RIP1, FADD and caspase-8 following IAP inhibition by SM has been described. However, targeting of RIP1 by Necrostatin was not sufficient to influence apoptosis induced by VCR/LCL161.

Grifolin induces apoptosis and promotes cell cycle arrest in the A2780 human ovarian cancer cell line via inactivation of the ERK1/2 and Akt pathways

Grifolin, a secondary metabolic product isolated from the mushroom Albatrellus confluence, has been demonstrated to possess antitumor activities in a variety of malignant cells. However, the signaling pathways and the molecular mechanisms underlying the anticancer effects of the agent in human ovarian cancer remain to be elucidated. The aim of the present study was to examine the effect of grifolin treatment on the human ovarian cancer cell line, A2780. MTT and flow cytometry analysis were used to analyze the viability of A2780 cells following treatment with grifolin. Western blotting was used analyze the expression of apoptosis-associated and cell cycle arrest-associated proteins. The results of MTT assays and flow cytometry analysis revealed that grifolin suppressed cell viability, induced apoptosis and triggered cell cycle arrest. Western blotting revealed that grifolin treatment resulted in inactivation of protein kinase B (Akt) and extracellular signal-related kinase 1/2 (ERK1/2), accompanied by upregulation of Bcl-2 associated X, apoptosis regulator, cleaved-caspase-3 and cleaved-poly (ADP-ribose) polymerase, and downregulation of B cell lymphoma-2, cyclin dependent kinase 4 and cyclinD1. The results of the present study indicated that grifolin had significant anti-cancer effects on the human ovarian cancer A2780 cells, which occurred via the Akt and ERK1/2 signaling pathways to at least a certain extent. These results demonstrate the therapeutic potential of grifolin as a treatment for ovarian cancer.

LFG-500, a newly synthesized flavonoid, induces apoptosis in human ovarian carcinoma SKOV3 cells with involvement of the reactive oxygen species-mitochondria pathway

Ovarian cancer is the main cause of gynecologic malignancy-related mortality in women. Therefore, the disease requires improvements in treatment options and in the potency of chemotherapeutic drugs. The study of apoptosis in tumor cells is an important field for cancer therapy and cancer molecular biology. It has recently been established that LFG-500, a new synthesized flavonoid with a piperazine and benzyl group substitution, has strong anticancer activity. However, its exact molecular mechanism is not fully understood. The present study aimed to examine the effects of LFG-500 on human ovarian cancer SKOV3 cells, as well as to identify its underlying mechanisms. The data showed that LFG-500 inhibited the growth of SKOV3 cells in a concentration-dependent manner. It was found that LFG-500 induced apoptosis in SKOV3 cells, detected by DAPI staining and an Annexin V/PI double-staining assay. Moreover, LFG-500 reduced caspase-3 protein expression and increased the Bcl-2-associated X protein/B-cell lymphoma 2 protein ratio. Further findings revealed that LFG-500 treatment resulted in reactive oxygen species (ROS) accumulation and loss of mitochondrial transmembrane potential. Collectively, these results demonstrated that LFG-500 efficiently induced apoptosis in SKOV3 cells, an event possibly associated with the trigging of the mitochondrial apoptotic pathway through ROS accumulation. Therefore, LFG-500 shows potential as a potent anticancer agent for the treatment of ovarian cancer.

A novel β-diiminato manganeseIII complex as the promising anticancer agent induces G0/G1 cell cycle arrest and triggers apoptosis via mitochondrial-dependent pathways in MCF-7 and MDA-MB-231 human breast cancer cells

Novel β-diiminato manganese^III complex has shown promising anti-breast cancer activity.

Inhibitory effect of bufalin on retinoblastoma cells (HXO-RB44) via the independent mitochondrial and death receptor pathway

Cinobufacini (Huachansu) is a Chinese medicine prepared from the skin of Bufo bufo gargarizans Cantor (Bufonidae), and has long been used in traditional Chinese medicine. In the present study, the anti-retinoblastoma constituent bufalin obtained from Cinobufacini was investigated. Treatment of human retinoblastoma (HXO-RB44) cells with bufalin induced apoptosis which was accompanied by a decrease in mitochondrial membrane potential, activation of caspase-9, caspase-8 and caspase-3, as well as changes in the expression of cytochrome C. Bufalin induced the cleavage of caspase-3 and apoptosis, and it was inhibited by both Z-LETD-FMK and Z-IETD-FMK treatment. Taken together, these results demonstrate that bufalin-induced apoptosis in human retinoblastoma (HXO-RB44) cells involved both intrinsic and extrinsic pathways.

Alleviation of Lead-Induced Apoptosis by Puerarin via Inhibiting Mitochondrial Permeability Transition Pore Opening in Primary Cultures of Rat Proximal Tubular Cells

Previous study has demonstrated that mitochondrial-dependent apoptotic pathway is involved in the nephroprotective effect of puerarin (PU) against lead-induced cytotoxicity in primary cultures of rat proximal tubular (rPT) cells. To further clarify how PU exerts its antiapoptotic effects, this study was designed to investigate the role of mitochondrial permeability transition (MPT) and subsequent apoptotic events in the process of PU against Pb-induced cytotoxicity in rPT cells. The results showed that Pb-mediated mitochondrial permeability transition pore (MPTP) opening together with mitochondrial cytochrome c release, activations of caspase-9 and caspase-3, and subsequent poly-ADP-ribose polymerase (PARP) cleavage can be effectively blocked by the addition of PU. Simultaneously, upregulation and downregulation of Bcl-2 and Bax with increased Bcl-2/Bax ratio due to PU administration further alleviated Pb-induced mitochondrial apoptosis. Moreover, PU can reverse Pb-induced ATP depletion by restoring mitochondrial fragmentation to affect ATP production and by regulating expression levels of ANT-1 and ANT-2 to improve ATP transport. In summary, PU produced a significant protection against Pb-induced mitochondrial apoptosis in rPT cells by inhibiting MPTP opening to ameliorate the mitochondrial dysfunction.

HIV-1 promonocytic and lymphoid cell lines: an in vitro model of in vivo mitochondrial and apoptotic lesion

To characterize mitochondrial/apoptotic parameters in chronically human immunodeficiency virus (HIV-1)-infected promonocytic and lymphoid cells which could be further used as therapeutic targets to test pro-mitochondrial or anti-apoptotic strategies as in vitro cell platforms to deal with HIV-infection. Mitochondrial/apoptotic parameters of U1 promonocytic and ACH2 lymphoid cell lines were compared to those of their uninfected U937 and CEM counterparts. Mitochondrial DNA (mtDNA) was quantified by rt-PCR while mitochondrial complex IV (CIV) function was measured by spectrophotometry. Mitochondrial-nuclear encoded subunits II-IV of cytochrome-c-oxidase (COXII-COXIV), respectively, as well as mitochondrial apoptotic events [voltage-dependent-anion-channel-1(VDAC-1)-content and caspase-9 levels] were quantified by western blot, with mitochondrial mass being assessed by spectrophotometry (citrate synthase) and flow cytometry (mitotracker green assay). Mitochondrial membrane potential (JC1-assay) and advanced apoptotic/necrotic events (AnexinV/propidium iodide) were measured by flow cytometry. Significant mtDNA depletion spanning 57.67% (P < 0.01) was found in the U1 promonocytic cells further reflected by a significant 77.43% decrease of mitochondrial CIV activity (P < 0.01). These changes were not significant for the ACH2 lymphoid cell line. COXII and COXIV subunits as well as VDAC-1 and caspase-9 content were sharply decreased in both chronic HIV-1-infected promonocytic and lymphoid cell lines (<0.005 in most cases). In addition, U1 and ACH2 cells showed a trend (moderate in case of ACH2), albeit not significant, to lower levels of depolarized mitochondrial membranes. The present in vitro lymphoid and especially promonocytic HIV model show marked mitochondrial lesion but apoptotic resistance phenotype that has been only partially demonstrated in patients. This model may provide a platform for the characterization of HIV-chronicity, to test novel therapeutic options or to study HIV reservoirs.

Puerarin protects against cadmium-induced proximal tubular cell apoptosis by restoring mitochondrial function

Puerarin (PU) is a potent free radical scavenger with a protective effect in nephrotoxin-mediated oxidative damage. Here, we show a novel molecular mechanism by which PU exerts its anti-apoptotic effects in cadmium (Cd)-exposed primary rat proximal tubular (rPT) cells. Morphological assessment and flow cytometric analysis revealed that PU significantly decreased Cd-induced apoptotic cell death of rPT cells. Administration of PU protected cells against Cd-induced depletion of mitochondrial membrane potential (ΔΨm) and lipid peroxidation. Cd-mediated mitochondrial permeability transition pore (MPTP) opening, disruption of mitochondrial ultrastructure, mitochondrial cytochrome c (cyt-c) release, caspase-3 activation and subsequently poly ADP-ribose polymerase (PARP) cleavage could be effectively blocked by the addition of PU. Moreover, up-regulation of Bcl-2 and down-regulation of Bax and hence increased Bcl-2/Bax ratio were observed with the PU administration. In addition, PU reversed Cd-induced ATP depletion by restoring ΔΨm to affect ATP production and by regulating expression levels of ANT-1 and ANT-2 to improve ATP transport. In summary, PU inhibited Cd-induced apoptosis in rPT cells by ameliorating the mitochondrial dysfunction.

Porphyromonas gingivalis Differentially Modulates Cell Death Profile in Ox-LDL and TNF-α Pre-Treated Endothelial Cells

Objective

Clinical studies demonstrated a potential link between atherosclerosis and periodontitis. Porphyromonas gingivalis (Pg), one of the main periodontal pathogen, has been associated to atheromatous plaque worsening. However, synergism between infection and other endothelial stressors such as oxidized-LDL or TNF-α especially on endothelial cell (EC) death has not been investigated. This study aims to assess the role of Pg on EC death in an inflammatory context and to determine potential molecular pathways involved.

Methods

Human umbilical vein ECs (HUVECs) were infected with Pg (MOI 100) or stimulated by its lipopolysaccharide (Pg-LPS) (1μg/ml) for 24 to 48 hours. Cell viability was measured with AlamarBlue test, type of cell death induced was assessed using Annexin V/propidium iodide staining. mRNA expression regarding caspase-1, -3, -9, Bcl-2, Bax-1 and Apaf-1 has been evaluated with RT-qPCR. Caspases enzymatic activity and concentration of APAF-1 protein were evaluated to confirm mRNA results.

Results

Pg infection and Pg-LPS stimulation induced EC death. A cumulative effect has been observed in Ox-LDL pre-treated ECs infected or stimulated. This effect was not observed in TNF-α pre-treated cells. Pg infection promotes EC necrosis, however, in infected Ox-LDL pre-treated ECs, apoptosis was promoted. This effect was not observed in TNF-α pre-treated cells highlighting specificity of molecular pathways activated. Regarding mRNA expression, Pg increased expression of pro-apoptotic genes including caspases-1,-3,-9, Bax-1 and decreased expression of anti-apoptotic Bcl-2. In Ox-LDL pre-treated ECs, Pg increased significantly the expression of Apaf-1. These results were confirmed at the protein level.

Conclusion

This study contributes to demonstrate that Pg and its Pg-LPS could exacerbate Ox-LDL and TNF-α induced endothelial injury through increase of EC death. Interestingly, molecular pathways are differentially modulated by the infection in function of the pre-stimulation.

shRNA Depletion of cIAP1 Sensitizes Human Ovarian Cancer Cells to Anticancer Agent-Induced Apoptosis

Emerging evidence suggests a potential role of cellular inhibitor of apoptosis protein 1 (cIAP1) in the development of human ovarian cancer. However, its function in the progression of ovarian cancer has not been clearly determined. Our study aimed to investigate the effect of cIAP1 gene depletion on the chemosensitivity of ovarian cancer cells. We developed a novel short hairpin RNA (shRNA) plasmid specifically targeting cIAP1. Cell proliferation, invasion, and apoptosis of the shRNA-transfected cells were evaluated using MTT, Transwell chamber, and flow cytometric assays, respectively. The concentration of MMP-9 in the supernatant was detected by ELISA. Targeted depletion of cIAP1 by shRNA significantly reduced expression levels of cIAP1 mRNA and protein, leading to inhibition of cell proliferation and invasion capability in SKOV3 cells. At the same time, cIAP1 downregulation decreased the secretion of MMP-9. shRNA depletion of cIAP1 enhanced chemosensitivity of ovarian cancer cells to Taxol and carboplatin-induced apoptosis. cIAP1 is associated with tumor progression in human ovarian cancer. Therefore, cIAP1 might be a potential target for therapeutic anticancer drugs.

Procaspase-9 induces its cleavage by transnitrosylating XIAP via the Thioredoxin system during cerebral ischemia-reperfusion in rats

Transnitrosylation is an important mechanism by which nitric oxide (NO) modulates cell signaling pathways. For instance, SNO-caspase-3 can transnitrosylate the X-linked inhibitor of apoptosis (XIAP) to enhance apoptosis. XIAP is a potent antagonist of caspase apoptotic activity. Decrease in XIAP activity via nitrosylation results in SNO-XIAP-mediated caspase activation. Considering the functional liaison of procaspase-9 and XIAP, we hypothesized that procaspase-9 nitrosylates XIAP directly. Our data confirmed that cerebral ischemia-reperfusion induced XIAP nitrosylation, procaspase-9 denitrosylation and cleavage. Interestingly, the time courses of the nitrosylation of procaspase-9 and XIAP were negatively correlated, which was more prominent after cerebral ischemia-reperfusion, suggesting a direct interaction. The nitrosylation of XIAP, as well as the denitrosylation and cleavage of procaspase-9, were inhibited by DNCB, TrxR1 AS-ODNs, or TAT-AVPY treatment. Meanwhile, DNCB, TrxR1 AS-ODNs, or TAT-AVPY also inhibited the decrease in hippocampal CA1 neurons induced by ischemia-reperfusion in rats. The denitrosylation and cleavage of procaspase-9 induced by OGD/reoxygenation in SH-SY5Y cells were inhibited when cells were co-transfected with wild-type procaspase-9 and XIAP mutant (C449G). These data suggest that cerebral ischemia-reperfusion induces a transnitrosylation from procaspase-9 to XIAP via the Trx system to consequently cause apoptosis. Additionally, Cys325 is a critical S-nitrosylation site of procaspase-9.

Apoptosis Activation in Human Lung Cancer Cell Lines by a Novel Synthetic Peptide Derived from Conus californicus Venom

Lung cancer is one of the most common types of cancer in men and women and a leading cause of death worldwide resulting in more than one million deaths per year. The venom of marine snails Conus contains up to 200 pharmacologically active compounds that target several receptors in the cell membrane. Due to their diversity and specific binding properties, Conus toxins hold great potential as source of new drugs against cancer. We analyzed the cytotoxic effect of a 17-amino acid synthetic peptide (s-cal14.1a) that is based on a native toxin (cal14.1a) isolated from the sea snail Conus californicus. Cytotoxicity studies in four lung cancer cell lines were complemented with measurement of gene expression of apoptosis-related proteins Bcl-2, BAX and the pro-survival proteins NFκB-1 and COX-2, as well as quantification of caspase activity. Our results showed that H1299 and H1437 cell lines treated with s-call4.1a had decreased cell viability, activated caspases, and reduced expression of the pro-survival protein NFκB-1. To our knowledge, this is the first report describing activation of apoptosis in human lung cancer cell lines by s-cal14.1a and we offer insight into the possible mechanism of action.

Hep88 mAb-mediated paraptosis-like apoptosis in HepG2 cells via downstream upregulation and activation of caspase-3, caspase-8 and caspase-9

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide. Presently, targeted therapy via monoclonal antibodies to specific tumor-associated antigens is being continuously developed. Hep88 mAb has proven to exert tumoricidal effects on the HepG2 cell via a paraptosis-like morphology. To verify the pathway, we then demonstrated downstream up-regulation of caspase-3, caspase-8 and caspase-9, assessingmRNA expression by real-time PCR and associated enzyme activity by colorimetric assay. Active caspase-3 determination was also accomplished by flow cytometry. Active caspase-3 expression was increased by Hep88 mAb treatment in a dose-and time-dependent manner. All of the results indicated that Hep88 mAb induced programmed cell death in the HepG2 cell line from paraptosis-like to apoptosis by downstream induction of caspases. These conclusions imply that Hep88mAb might be a promising tool for the effective treatment of HCC in the future.

17β-estradiol protects against apoptosis induced by interleukin-1β in rat nucleus pulposus cells by down-regulating MMP-3 and MMP-13

In our previous study, 17β-estradiol was proved to protect rat annulus fibrosus cells against apoptosis induced by interleukin-1β (IL-1β). However, whether 17β-estradiol has protective effect on rat nucleus pulposus cells remains unclear. The purpose of this study was to further explore the effects of 17β-estradiol on rat nucleus pulposus cells based on IL-1β-induced apoptosis. TUNEL assay and Annexin V/PI double staining were used to detect apoptosis and revealed that IL-1β induced notable apoptosis, which was reversed by 17β-estradiol. Meanwhile, cell viability and binding ability were decreased by IL-1β, but activated caspase-3 was increased. However, all of the detected effects of IL-1β were eliminated by 17β-estradiol. Furthermore, real-time quantitative RT-PCR was used to further find that IL-1β downregulated expression level of type II collagen, aggrecan, tissue inhibitor of matrix metalloproteinase (TIMP)-1, while upregulated matrix metalloproteinase (MMP)-3, MMP-13 and Bcl-2, which was further confirmed by western blot. Finally, 17β-estradiol was proved to abolish the above negative effects of IL-1β. In summary, this work presented that IL-1β maybe induced apoptosis of rat nucleus pulposus cells, which was resisted by 17β-estradiol by down-regulating MMP-3 and MMP-13 via a mitochondrial pathway. This research provides a novel insight into the anti-apoptotic effect of 17β-estradiol on IL-1β-induced cytotoxicity, and may potentially lead to a better understanding of the clinical effects of 17β-estradiol, especially in terms of intervertebral disc degeneration.

Garcinia dulcis Fruit Extract Induced Cytotoxicity and Apoptosis in HepG2 Liver Cancer Cell Line

Garcinia dulcis or locally known in Malaysia as “mundu” belongs to the family of Clusiaceae. The study was conducted to investigate the anticancer potential of different parts of G. dulcis fruit extracts and their possible mechanism of action in HepG2 liver cancer cell line. MTT assay showed that the peel, flesh, and seed extracts of G. dulcis induced cytotoxicity in HepG2 cell line with IC₅₀ values of 46.33 ± 4.51, 38.33 ± 3.51, and 7.5 ± 2.52 µg/mL, respectively. The flesh extract of G. dulcis induced cell cycle arrest at sub-G₁ (apoptosis) phase in a time-dependent manner. Staining with Annexin V-FITC and propidium iodide showed that 41.2% of the cell population underwent apoptosis after 72 hours of exposure of the HepG2 cell line to G. dulcis flesh extract. Caspase-3 has been shown to be activated which finally leads to the death of HepG2 cell (apoptosis). GC-MS analysis showed that the highest percentage of compound identified in the extract of G. dulcis flesh was hydroxymethylfurfural and 3-methyl-2,5-furandione, together with xanthones and flavonoids (based on literature), could synergistically contribute to the observed effects. This finding suggested that the flesh extract of G. dulcis has its own potential as cancer chemotherapeutic agent against liver cancer cell.

TAT Modification of Alpha-Helical Anticancer Peptides to Improve Specificity and Efficacy

HPRP-A1 is an amphipathic α-helical anticancer peptide (ACP) derived from the N-terminus of ribosomal protein L1 (RpL1) of Helicobacter pylori. In our previously study, HPRP-A1 has been reported that induced HeLa cell apoptosis in a caspase-dependent approach and involved both by the death receptor ‘extrinsic’ pathway and the mitochondria ‘intrinsic’ pathway. Here we report the construction of a new hybrid peptide, HPRP-A1-TAT, comprising the cell-permeating peptide TAT linked to the C-terminus of HPRP-A1. This peptide exhibits higher anticancer activity against HeLa cells with lower toxicity against human RBC than HPRP-A1. Two FITC-labeled peptides, FITC-HPRP-A1 and FITC-HPRP-A1-TAT, were used to investigate and compare the cellular uptake mechanism using fluorescence spectra and flow cytometry. Compared with HPRP-A1, HPRP-A1-TAT quickly crossed cell, entered the cytoplasm via endocytosis, and disrupted the cell membrane integrity. HPRP-A1-TAT exhibited stronger anticancer activity than HPRP-A1 at the same concentration by increasing early apoptosis of HeLa cells and inducing caspase activity. Notably, after 24 h, the cellular concentration of HPRP-A1-TAT was higher than that of HPRP-A1. This result suggests that TAT protects HPRP-A1 against degradation, likely due to its high number of positively charged amino acids or the further release of peptides into cancer cells from endocytotic vesicles. We believe that this TAT modification approach may provide an effective new strategy for improving the therapeutic index and anticancer activity of ACPs for clinical use.

Direct Activation of Bax Protein for Cancer Therapy

Bax, a central cell death regulator, is an indispensable gateway to mitochondrial dysfunction and a major proapoptotic member of the B-cell lymphoma 2 (Bcl-2) family proteins that control apoptosis in normal and cancer cells. Dysfunction of apoptosis renders the cancer cell resistant to treatment as well as promotes tumorigenesis. Bax activation induces mitochondrial membrane permeabilization, thereby leading to the release of apoptotic factor cytochrome c and consequently cancer cell death. A number of drugs in clinical use are known to indirectly activate Bax. Intriguingly, recent efforts demonstrate that Bax can serve as a promising direct target for small-molecule drug discovery. Several direct Bax activators have been identified to hold promise for cancer therapy with the advantages of specificity and the potential of overcoming chemo- and radioresistance. Further investigation of this new class of drug candidates will be needed to advance them into the clinic as a novel means to treat cancer.

Ageing is a risk factor in imatinib mesylate cardiotoxicity

AIMS

Chemotherapy-induced heart failure is increasingly recognized as a major clinical challenge. Cardiotoxicity of imatinib mesylate, a highly selective and effective anticancer drug belonging to the new class of tyrosine kinase inhibitors, is being reported in patients, some progressing to congestive heart failure. This represents an unanticipated challenge that could limit effective drug use. Understanding the mechanisms and risk factors of imatinib mesylate cardiotoxicity is crucial for prevention of cardiovascular complications in cancer patients.

METHODS AND RESULTS

We used genetically engineered mice and primary rat neonatal cardiomyocytes to analyse the action of imatinib on the heart. We found that treatment with imatinib (200 mg/kg/day for 5 weeks) leads to mitochondrial-dependent myocyte loss and cardiac dysfunction, as confirmed by electron microscopy, RNA analysis, and echocardiography. Imatinib cardiotoxicity was more severe in older mice, in part due to an age-dependent increase in oxidative stress. Mechanistically, depletion of the transcription factor GATA4 resulting in decreased levels of its prosurvival targets Bcl-2 and Bcl-XL was an underlying cause of imatinib toxicity. Consistent with this, GATA4 haploinsufficient mice were more susceptible to imatinib, and myocyte-specific up-regulation of GATA4 or Bcl-2 protected against drug-induced cardiotoxicity.

CONCLUSION

The results indicate that imatinib action on the heart targets cardiomyocytes and involves mitochondrial impairment and cell death that can be further aggravated by oxidative stress. This in turn offers a possible explanation for the current conflicting data regarding imatinib cardiotoxicity in cancer patients and suggests that cardiac monitoring of older patients receiving imatinib therapy may be especially warranted.

MicroRNA-345 induces apoptosis in pancreatic cancer cells through potentiation of caspase-dependent and -independent pathways

Background:

Previously, miR-345 was identified as one of the most significantly downregulated microRNAs in pancreatic cancer (PC); however, its functional significance remained unexplored.

Methods:

miR-345 was overexpressed in PC cells by stable transfection, and its effect on growth, apoptosis and mitochondrial-membrane potential was examined by WST-1, Hoechst-33342/Annexin-V, and JC-1 staining, respectively. Gene expression was examined by quantitative reverse-transcription-PCR and/or immunoblotting, and subcellular fractions prepared and caspase-3/7 activity determined by commercially available kits. miR-345 target validation was performed by mutational analysis and luciferase-reporter assay.

Results:

miR-345 is significantly downregulated in PC tissues and cell lines relative to normal pancreatic cells, and its expression decreases gradually in PC progression model cell lines. Forced expression of miR-345 results in reduced growth of PC cells because of the induction of apoptosis, accompanied by a loss in mitochondrial membrane potential, cytochrome-c release, caspases-3/7 activation, and PARP-1 cleavage, as well as mitochondrial-to-nuclear translocation of apoptosis-inducing factor. These effects could be reversed by the treatment of miR-345-overexpressing PC cells with anti-miR-345 oligonucleotides. BCL2 was characterised as a novel target of miR-345 and its forced-expression abrogated the effects of miR-345 in PC cells.

Conclusions:

miR-345 downregulation confers apoptosis resistance to PC cells, and its restoration could be exploited for therapeutic benefit.

Butein Shows Cytotoxic Effects and Induces Apoptosis in Human Ovarian Cancer Cells

Butein is a polyphenol, one of the compounds of chalcones, which are flavonoids that are widely biosynthesized in plants, and exhibits different pharmacological activities. Plants containing butein have been used in Chinese traditional medicine. Recently, it has been reported that butein suppresses proliferation and triggers apoptosis in various human cancer cells in vitro and in vivo. The aim of this study was to investigate its pro-apoptotic effect and mechanisms in two cultured human ovarian cancer cells (ES-2 and TOV-21G). The effects of butein on cell viability were assessed by a MTT assay at 3, 10, 30, and 100 μ/M. The apoptotic pathway related factors, including the mitochondrial transmembrane potential (MTP), cytochrome c, caspase cascade, and Bcl-2 family proteins, were examined. MTT assay revealed that butein was cytotoxic to both ovarian cancer cells in a dose- and time-dependent manner. JC-1 flow cytometry, cytochrome c, and caspase activity assays revealed that butein damaged the MTP, increased the level of cytosol cytochrome c and the activities of caspase-3, -8, and -9 in the two ovarian cancer cells. Western blot analysis revealed that butein down-regulated the anti-apoptotic proteins Bcl-2 and Bcl-xL and increased the pro-apoptotic proteins Bax and Bad. These findings suggest that butein-induced apoptosis in ovarian cancer cells via the activation of both extrinsic and intrinsic pathways. In addition, butein also down-regulated the expressions of the inhibitor of apoptosis (IAP) proteins, XIAP, survivin, CIAP-1, and CIAP-2. This indicates that the inhibition of IAP proteins was also involved in butein-induced apoptosis. The results of our study suggest that butein may be a promising anticancer agent in treating ovarian cancer.

Rapamycin, an mTOR inhibitor, induced apoptosis via independent mitochondrial and death receptor pathway in retinoblastoma Y79 cell

Rapamycin is helpful in the treatment of certain cancers by inhibiting mTOR (mammalian target of rapamycin) pathway. Here, rapamycin mediated apoptosis were investigated in human retinoblastoma Y79 cells. The MTT assay showed that the IC50 value of rapamycin against Y79 cells was 0.136 ± 0.032 μmol/L. Flow cytometry analysis indicated that the percentage of apoptotic cells was increased from 2.16 ± 0.41% to 12.24 ± 3.10%, 20.16 ± 4.22%, and 31.32 ± 5.78% after 0.1, 0.2, and 0.4 μmol/L rapamycin or without rapamycin treatment for 48 hours. Flow cytometry analysis showed that rapamycin induced mitochondrial membrane potential (∆Ψm) collapse in Y79 cells in a concentration-dependent manner. Western blot assay showed that rapamycin led to release of cytochrome c from mitochondrial membranes to cytosol. Further Western blot assays showed that rapamycin induced activation of caspase-9 and caspase-8 and the cleavage of caspase-3. Rapamycin induced cleavages of caspase-3 and apoptosis was inhibited by both Z-LETD-FMK and Z-IETD-FMK treatment. Together, all these results illustrated that rapamycin induced apoptosis in human retinoblastoma Y79 cells involvement of both intrinsic and extrinsic pathways.

Mitochondrial permeability transition and its regulatory components are implicated in apoptosis of primary cultures of rat proximal tubular cells exposed to lead

Previous studies have already demonstrated that mitochondria play a key role in Pb-induced apoptosis in primary cultures of rat proximal tubular (rPT) cells. To further clarify the underlying mechanism of Pb-induced mitochondrial apoptosis, this study was designed to investigate the role of mitochondrial permeability transition (MPT) and its regulatory components in Pb-induced apoptosis in rPT cells. Mitochondrial permeability transition pore (MPTP) opening together with disruption of mitochondrial ultrastructure, translocation of cytochrome c from mitochondria to cytoplasm and subsequent caspase-3 activation were observed in this study, suggesting that MPT is involved in Pb-induced apoptosis in rPT cells. Simultaneously, Pb-induced caspase-3 activation and apoptosis can be significantly inhibited by three MPTP inhibitors (CsA, DIDS, BA), which target different regulatory components of MPTP (Cyp-D, VDAC, ANT), respectively, demonstrating that Cyp-D, VDAC and ANT participate in MPTP regulation during lead exposure. Moreover, decreased ATP levels and increased ADP/ATP ratio induced by lead treatment can be significantly reversed by BA, indicating that Pb-mediated ANT dysfunction resulted in ATP depletion. In addition, up-regulation of VDAC-1, ANT-1 together with down-regulation of Cyp-D, VDAC-2 and ANT-2 at both the levels of transcription and translation were revealed in rPT cells under lead exposure conditions. In conclusion, Pb-mediated mitochondrial apoptosis in rPT cells is dependent on MPTP opening. Different expression levels in each isoform of three regulatory components contribute to alteration in their functions, which may promote the MPTP opening.

Protective effect of geranylgeranylacetone against hydrogen peroxide-induced oxidative stress in human neuroblastoma cells

AIMS

Heat shock protein 70 (HSP70), one of the major HSPs, has been reported to suppress apoptosis and formation of pathogenic proteins in neurodegenerative disorders. Geranylgeranylacetone (GGA), an anti-ulcer drug, induces HSP70 and thereby protects against cellular damage in various diseases. We investigated the effect of GGA on hydrogen peroxide (H2O2)-induced neurotoxicity in human neuroblastoma SH-SY5Y cells.

MAIN METHODS

H2O2-induced neuronal toxicity was measured by a CCK-8 assay and Hoechst 33342 staining. We also assessed oxidative stress and apoptosis by measuring reactive oxygen species (ROS) generation with 2′,7′-dichlorofluorescein diacetate (DCFH-DA), caspase-3 activity, and mitogen-activated protein kinase (MAPK) pathway.

KEY FINDINGS

GGA showed a concentration-dependent inhibition on H2O2-induced apoptotic cell death. H2O2-induced induction of HSP70 was enhanced by GGA pretreatment. GGA effectively suppressed the up-regulation of Bax and down-regulation of Bcl-2. GGA also blocked the H2O2-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). In addition, GGA attenuated H2O2-induced ROS generation and caspase-3 activity.

SIGNIFICANCE

These results demonstrate that GGA protects SH-SY5Y cells from H2O2-induced apoptosis, at least in part by enhancing HSP70 production. Neuroprotective properties of GGA indicate that this compound may be a potential therapeutic agent for the treatment and prevention of neurodegenerative diseases.

Cryptotanshinone protects against adriamycin-induced mitochondrial dysfunction in cardiomyocytes

CONTEXT

The serious side effect of Adriamycin (ADR) is cardiomyopathy. Cryptotanshinone (CRY) is widely and safely used as antioxidant with MTD more than 5 mg/g in rats (p.o).

OBJECTIVE

The objective of this study is to study the protection effects of CRY against ADR-induced mitochondrial dysfunction in cardiomyocytes.

MATERIALS AND METHODS

The chemical administration lasted for 20 days with an effective dose of CRY (p.o.) at 50 mg/kg in rats. Mitochondrial respiratory chain complex activities, ATP generation, mitochondrial membrane potential (MMP), superoxide anion free radical, oxidative stress-relative enzymes, and mitochondrial biogenesis-relative factors in normal control, ADR (i.p., 1.25 mg/kg), and ADR (i.p., 1.25 mg/kg) + CYP (p.o., 50 mg/kg) groups were detected.

RESULTS

50 mg/kg CRY significantly promoted the energy production of ATP (16.99 ± 2.38 nmol/g Pro) (Pro: Protein) by increasing the complexes activities except II (p > 0.05). After the treatment of CRY, the suppressed MMP was increased while superoxide anion free radical (0.57 ± 0.07/mg Pro) was inhibited markedly. Mitochondrial biogenesis-relative factors PGC-1α, NRF-1, and TFAM were also promoted. Remarkable augmentations of NO, inducible nitric oxide synthase (iNOS), and increased activity of GSH-PX (p < 0.05) were also detected after the treatment of CRY, while no obvious changes on the activity of nitric oxide synthase (cNOS; p > 0.05) were observed.

DISCUSSION AND CONCLUSION

These results suggest that CRY protects against ADR-induced mitochondrial dysfunction in cardiomyocytes. It could be an ideal potential drug of cardioprotection.

Dihydromyricetin protects endothelial cells from hydrogen peroxide-induced oxidative stress damage by regulating mitochondrial pathways

HEADING AIMS

Dihydromyricetin (DMY) is the most abundant ingredient in vine tea. Here, we investigated the cytoprotective effects and possible mechanisms of DMY on hydrogen peroxide (H2O2)-induced oxidative stress damage in human umbilical vein endothelial cells (HUVECs).

MATERIALS AND METHODS

The percentage of cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. We determined the antioxidant properties of DMY by measuring the activity of superoxide dismutase (SOD) and malondialdehyde (MDA). Flow cytometry was used to measure apoptosis in HUVECs that were double stained with Hoechst 33342 and propidium iodide (PI). The generation of intracellular reactive oxygen species (ROS) was measured in 2',7'-dichlorofluorescin diacetate (DCFH-DA)-loaded HUVECs using a fluorescent microscope. Moreover, the expression of apoptosis-related proteins was determined by Western blotting. In addition, the release of nitric oxide (NO) was analyzed using a commercial kit.

KEY FINDINGS

HUVECs treated with H2O2 had a notable decrease in cell viability that was attenuated when cells were pretreated with DMY (37.5-300μM). DMY pretreatment significantly attenuated H2O2-induced apoptosis in HUVECs and inhibited intracellular ROS overproduction. Finally, pretreatment of cells with DMY prior to H2O2 exposure resulted in the inhibition of p53 activation, followed by the regulation of the expression of Bcl-2 and Bax, the release of cytochrome c, the cleavage (activation) of caspase-9 and caspase-3, and then the suppression of PARP cleavage in H2O2-induced HUVECs.

SIGNIFICANCE

Our study is the first to report that DMY can protect HUVECs from oxidative stress damage, an effect that is mediated by the mitochondrial apoptotic pathways.

Cell death controlling complexes and their potential therapeutic role

Programmed cell death plays a central role in the regulation of homeostasis and development of multicellular organisms. Deregulation of programmed cell death is connected to a number of disorders, including cancer and autoimmune diseases. Initiation of cell death occurs in the multiprotein complexes or high molecular weight platforms. Composition, structure, and molecular interactions within these platforms influence the cellular decision toward life or death and, therefore, define the induction of a particular cell death program. Here, we discuss in detail the key cell-death complexes-including DISC, complex II, and TNFRI complex I/II, and the necrosome, RIPoptosome, apoptosome, and PIDDosome-that control apoptosis or necroptosis pathways as well as their regulation. The possibility of their pharmacological targeting leading to the development of new strategies of interference with cell death programs via control of the high molecular weight platforms will be discussed.

The mystery of BCL2 family: Bcl-2 proteins and apoptosis: an update

Apoptosis is a critically important biological process that plays an essential role in cell fate and homeostasis. An important component of the apoptotic pathway is the family of proteins commonly known as the B cell lymphoma-2 (Bcl-2). The primary role of Bcl-2 family members is the regulation of apoptosis. Although the structure of Bcl-2 family of proteins was reported nearly 10 years ago, however, it still surprises us with its structural and functional complexity and diversity. A number of studies have demonstrated that Bcl-2 family influences many other cellular processes beyond apoptosis which are generally independent of the regulation of apoptosis, suggesting additional roles for Bcl-2. The disruption of the regulation of apoptosis is a causative event in many diseases. Since the Bcl-2 family of proteins is the key regulator of apoptosis, the abnormalities in its function have been implicated in many diseases including cancer, neurodegenerative disorders, ischemia and autoimmune diseases. In the past few years, our understanding of the mechanism of action of Bcl-2 family of proteins and its implications in various pathological conditions has enhanced significantly. The focus of this review is to summarize the current knowledge on the structure and function of Bcl-2 family of proteins in apoptotic cellular processes. A number of drugs have been developed in the past few years that target different Bcl-2 members. The role of Bcl-2 proteins in the pathogenesis of various diseases and their pharmacological significance as effective molecular therapeutic targets is also discussed.

Hydrogen sulfide improves left ventricular function in smoking rats via regulation of apoptosis and autophagy

The present study was designed to investigate the protective effects of hydrogen sulfide (H2S) against cigarette smoking-induced left ventricular dysfunction in rats. Left ventricular structure and function were assessed using two-dimensional echocardiography. Cardiomyocyte apoptosis was determined by Annexin V/PI and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. Cardiac autophagy was evaluated by detection of autophagy-related protein expression and observation of autophagosomes. Our results indicated that administration of NaHS (a donor of H2S) could protect against smoking-induced left ventricular systolic dysfunction. H2S was found to exert anti-apoptotic effects in the myocardium of smoking rats by inhibiting JNK and P38 mitogen-activated protein kinases pathways and activating PI3K/Akt signaling. Moreover, H2S could also reduce smoking-induced autophagic cell death via regulation of AMPK/mTOR signaling pathway. In conclusion, our study demonstrates that H2S can improve left ventricular systolic function in smoking rats via regulation of apoptosis and autophagy.