Multistep and multitask Bax activation

Role of ATP5G3 in sodium nitroprusside-induced cell death in cervical carcinoma cells

We identified a gene, subunit C3 (ATP5G3) of mitochondrial ATP synthase, that displayed changes in gene expression under oxidative stress. We examined the role of ATP5G3 and its molecular mechanisms in sodium nitroprusside (SNP)-induced cell death using ATP5G3 small interfering RNA (siATP5G3)-transfected HeLa cells. A significant increase in cytotoxicity was observed in the transfected cells treated with SNP, which suggests a protective role of ATP5G3 in SNP-induced cytotoxicity in the cells. The transfected cells treated with photodegraded SNP showed equal cytotoxicity to SNP, and pretreatment with deferoxamine (DFO) completely inhibited this cytotoxicity. Further, cytotoxicity was significantly inhibited by pretreatment with a p38 inhibitor and was accentuated by the p38 activator in cells. Pretreatment with the Bcl-xL inhibitor also significantly accentuated cytotoxicity. The increase in p38 phosphorylation was significantly higher in siATP5G3-transfected cells treated with SNP in immunoblotting, which was inhibited by pretreatment with DFO. The increase in cytotoxicity with siATP5G3 transfection was completely blocked by cotransfection with sip38, and the blocking effect disappeared by cotransfection with additional siBcl-xL, which suggests that the protective role of ATP5G3 is mediated by Bcl-xL via the inhibition of p38 activity. Cytotoxicity was completely blocked by the cotransfection of siATP5G3 with siBax. No change in apoptotic parameters was observed during cytotoxicity. However, pretreatment with lysosomal inhibitors significantly inhibited cytotoxicity and increased p62 protein levels. These findings suggest that ATP5G3 plays a protective role in autophagic cell death/lysosome-associated cell death induced by SNP via the sequential signaling of ROS/p38/Bcl-xL/Bax in HeLa cells.

Androgen Deprivation Freezes Hormone-Sensitive Prostate Cancer Cells in a Reversible, Genetically Unstable Quasi-Apoptotic State, Bursting into Full Apoptosis upon Poly(ADP-ribose) Polymerase Inhibition

Androgen deprivation therapy (ADT) is a powerful treatment for metastatic hormone-sensitive prostate cancer (mHSPC) patients, but eventually and inevitably, cancer relapses, progressing to the fatal castration-resistant (CR)PC stage. Progression implies the emergence of cells proliferating in the absence of androgen through still elusive mechanisms. We show here for the first time that ADT induces LNCaP mHSPC cells to collectively enter a metastable quasi-apoptotic state (QUAPS) consisting of partial mitochondrial permeabilization, limited BAX and caspase activation, and moderate induction of caspase-dependent dsDNA breaks; despite this, cells maintain full viability. QUAPS is destabilized by poly(ADP)-polymerase inhibition (PARPi), breaking off toward overt intrinsic apoptosis and culture extinction. Instead, QUAPS is rapidly and efficiently reverted upon androgen restoration, with mitochondria rapidly recovering integrity and cells collectively resuming normal proliferation. Notably, replication restarts before DNA repair is completed, and implies an increased micronuclei frequency, indicating that ADT promotes genetic instability. The recovered cells re-acquire insensitivity to PARPi (as untreated LNCaP), pointing to specific, context-dependent vulnerability of mHSPC cells to PARPi during ADT. Summarizing, QUAPS is an unstable, pro-mutagenic state developing as a pro-survival pathway stabilized by PARP, and constitutes a novel viewpoint explaining how ADT-treated mHSPC may progress to CRPC, indicating possible preventive countermeasures.

Interaction of LATS1 with SMAC links the MST2/Hippo pathway with apoptosis in an IAP-dependent manner

Metastatic malignant melanoma is the deadliest skin cancer, and it is characterised by its high resistance to apoptosis. The main melanoma driving mutations are part of ERK pathway, with BRAF mutations being the most frequent ones, followed by NRAS, NF1 and MEK mutations. Increasing evidence shows that the MST2/Hippo pathway is also deregulated in melanoma. While mutations are rare, MST2/Hippo pathway core proteins expression levels are often dysregulated in melanoma. The expression of the tumour suppressor RASSF1A, a bona fide activator of the MST2 pathway, is silenced by promoter methylation in over half of melanomas and correlates with poor prognosis. Here, using mass spectrometry-based interaction proteomics we identified the Second Mitochondria-derived Activator of Caspases (SMAC) as a novel LATS1 interactor. We show that RASSF1A-dependent activation of the MST2 pathway promotes LATS1-SMAC interaction and negatively regulates the antiapoptotic signal mediated by the members of the IAP family. Moreover, proteomic experiments identified a common cluster of apoptotic regulators that bind to SMAC and LATS1. Mechanistic analysis shows that the LATS1-SMAC complex promotes XIAP ubiquitination and its subsequent degradation which ultimately results in apoptosis. Importantly, we show that the oncogenic BRAFV600E mutant prevents the proapoptotic signal mediated by the LATS1-SMAC complex while treatment of melanoma cell lines with BRAF inhibitors promotes the formation of this complex, indicating that inhibition of the LATS1-SMAC might be necessary for BRAFV600E-driven melanoma. Finally, we show that LATS1-SMAC interaction is regulated by the SMAC mimetic Birinapant, which requires C-IAP1 inhibition and the degradation of XIAP, suggesting that the MST2 pathway is part of the mechanism of action of Birinapant. Overall, the current work shows that SMAC-dependent apoptosis is regulated by the LATS1 tumour suppressor and supports the idea that LATS1 is a signalling hub that regulates the crosstalk between the MST2 pathway, the apoptotic network and the ERK pathway.

Killing by Degradation: Regulation of Apoptosis by the Ubiquitin-Proteasome-System

Apoptosis is a cell suicide process that is essential for development, tissue homeostasis and human health. Impaired apoptosis is associated with a variety of human diseases, including neurodegenerative disorders, autoimmunity and cancer. As the levels of pro- and anti-apoptotic proteins can determine the life or death of cells, tight regulation of these proteins is critical. The ubiquitin proteasome system (UPS) is essential for maintaining protein turnover, which can either trigger or inhibit apoptosis. In this review, we will describe the E3 ligases that regulate the levels of pro- and anti-apoptotic proteins and assisting proteins that regulate the levels of these E3 ligases. We will provide examples of apoptotic cell death modulations using the UPS, determined by positive and negative feedback loop reactions. Specifically, we will review how the stability of p53, Bcl-2 family members and IAPs (Inhibitor of Apoptosis proteins) are regulated upon initiation of apoptosis. As increased levels of oncogenes and decreased levels of tumor suppressor proteins can promote tumorigenesis, targeting these pathways offers opportunities to develop novel anti-cancer therapies, which act by recruiting the UPS for the effective and selective killing of cancer cells.

VEGF121 Mediates Post-Hypoxia Cardioprotective Effects Via CaSR and Mitochondria-Dependent Protease Pathway

BACKGROUND

Cardiovascular disease is the major cause of death worldwide. Hypoxia-mediated apoptosis in cardiomyocytes is a major cause of cardiovascular disorders. Treatment with vascular endothelial growth factor (VEGF) protein has been tested but operational difficulties have limited its use. However, with the advancements of gene therapy, interest has risen in VEGF-based gene therapy in cardiovascular disorders. However, the precise mechanism by which VEGF replenishment rescues post-hypoxia damage in cardiomyocytes is not known.

OBJECTIVES

To investigate the effect of post-hypoxia VEGF121 expression using neonatal rat cardiomyocytes.

METHODS

Cardiomyocytes isolated from neonatal rats were used to establish an in vitro model of hypoxia-induced cardiac injury. The effect of VEGF overexpression, alone or in combination with small-molecule inhibitors targeting calcium channel, calcium sensitive receptors (CaSR), and calpain on cell growth and proliferation on hypoxia-induced cardiomyocyte injury were determined using an MTT assay, TUNEL staining, Annexin V/PI staining, lactate dehydrogenase and caspase activity. For statistical analysis, a value of P<0.05 was considered to be significant.

RESULTS

The effect of VEGF121 was found to be mediated by CaSR and calpain but was not dependent on calcium channels.

CONCLUSIONS

Our findings, even though using an in vitro setting, lay the foundation for future validation and pre-clinical testing of VEGF-based gene therapy in cardiovascular diseases.

Epidermal Growth Factor Receptor and its Trafficking Regulation by Acetylation: Implication in Resistance and Exploring the Newer Therapeutic Avenues in Cancer

BACKGROUND

The EGFR is overexpressed in numerous cancers. So, it becomes one of the most favorable drug targets. Single-acting EGFR inhibitors on prolong use induce resistance and side effects. Inhibition of EGFR and/or its interacting proteins by dual/combined/multitargeted therapies can deliver more efficacious drugs with less or no resistance.

OBJECTIVE

The review delves deeper to cover the aspects of EGFR mediated endocytosis, leading to its trafficking, internalization, and crosstalk(s) with HDACs.

METHODS AND RESULTS

This review is put forth to congregate relevant literature evidenced on EGFR, its impact on cancer prognosis, inhibitors, and its trafficking regulation by acetylation along with the current strategies involved in targeting these proteins (EGFR and HDACs) successfully by involving dual/hybrid/combination chemotherapy.

CONCLUSION

The current information on cross-talk of EGFR and HDACs would likely assist researchers in designing and developing dual or multitargeted inhibitors through combining the required pharmacophores.

miR-181a-5p regulates the proliferation and apoptosis of glomerular mesangial cells by targeting KLF6

Diabetic nephropathy (DN) is a chronic loss of kidney function that frequently occurs in patients with diabetes mellitus and is characterized by abnormal glomerular mesangial cell (GMC) proliferation and apoptosis. By using microarray analysis, microRNA (miR)-181a-5p has previously been identified to be dysregulated in DN. The present study aimed to determine the underlying molecular mechanisms and function of miR-181a-5p in GMCs under DN conditions. First, reverse transcription-quantitative PCR was performed to detect miR-181a-5p and kruppel-like factor 6 (KLF6) expression in GMCs following high-glucose treatment. Subsequently, MTT and flow cytometric assays were performed in order to determine the effect of miR-181a-5p and KLF6 on high-glucose-driven GMC proliferation and apoptosis. After confirming that KLF6 was a target gene of miR-181a-5p via a bioinformatics analysis and luciferase reporter assay, the mRNA and protein expression levels of associated factors in different treatment groups were measured. The results demonstrated that miR-181a-5p was significantly downregulated, while KLF6 was significantly upregulated in GMCs following treatment with high glucose. Furthermore, overexpression of miR-181a led to suppression of cell proliferation and promoted apoptosis of GMCs induced by high glucose, while these effects were inhibited by co-transfection with KLF6. Finally, miR-181-5p was demonstrated to inhibit the expression of KLF6, Bcl-2, Wnt1 and β-catenin, while increasing the expression levels of Bax and caspase-3. In conclusion, the expression levels of miR-181a-5p were downregulated in GMCs following treatment with high glucose and overexpression of miR-181a-5p may inhibit GMC proliferation and promote apoptosis, at least partially through targeting KLF6 via the Wnt/β-catenin signaling pathway. Overall, the results of the present study suggest that miR-181a-5p may have a crucial role in the occurrence and development of DN and may be a valuable diagnostic marker and therapeutic target for DN.

KCP10043F Represses the Proliferation of Human Non-Small Cell Lung Cancer Cells by Caspase-Mediated Apoptosis via STAT3 Inactivation

We previously reported that 4-(4-fluorobenzylcarbamoylmethyl)-3-(4-cyclohexylphenyl)-2-[3-(N,N-dimethylureido)-N'-methylpropylamino]-3,4-dihydroquinazoline (KCP10043F) can induce G₁-phase arrest and synergistic cell death in combination with etoposide in lung cancer cells. Here, we investigated the underlying mechanism by which KCP10043F induces cell death in non-small cell lung cancer (NSCLC). Propidium iodide (PI) and annexin V staining revealed that KCP10043F-induced cytotoxicity was caused by apoptosis. KCP10043F induced a series of intracellular events: (1) downregulation of Bcl-2 and Bcl-xL and upregulation of Bax and cleaved Bid; (2) loss of mitochondrial membrane potential; (3) increase of cytochrome c release; (4) cleavage of procaspase-8, procaspase-9, procaspase-3, and poly (ADP-ribose) polymerase (PARP). In addition, KCP10043F exhibited potent inhibitory effects on constitutive or interleukin-6 (IL-6)-induced signal transducer and activator of transcription (STAT3) phosphorylation and STAT3-regulated genes including survivin, Mcl-1, and cyclin D₁. Furthermore, STAT3 overexpression attenuated KCP10043F-induced apoptosis and the cleavage of caspase-9, caspase-3, and PARP. Docking analysis disclosed that KCP10043F could bind to a pocket in the SH2 domain of STAT3 and prevent STAT3 phosphorylation. The oral administration of KCP10043F decreased tumor growth in an A549 xenograft mouse model, as associated with the reduced phosphorylated STAT3, survivin, Mcl-1, and Bcl-2 expression and increased TUNEL staining and PARP cleavage in tumor tissues. Collectively, our data suggest that KCP10043F suppresses NSCLC cell growth through apoptosis induction via STAT3 inactivation.

Hydroxychloroquine reverses the drug resistance of leukemic K562/ADM cells by inhibiting autophagy

Autophagy is an essential metabolic pathway mediated by lysosomal degradation, which is involved in scavenging and recycling senescent or damaged organelles and biological macromolecules in eukaryotic cells. The present study explored the association between the autophagic activity and chemotherapy resistance of leukaemia cells, and the possibility of using autophagy inhibitors to combat leukemic drug resistance. It was found that the levels of basic autophagy in multidrug‑resistant leukaemia cells (K562/ADM) were significantly higher compared with sensitive cells (K562), and that Adriamycin (ADM) was capable of inducing autophagic activity in K562 and K562/ADM cells. K562 and K562/ADM cells were treated with a series of hydroxychloroquine (HCQ) concentrations to inhibit cellular autophagy and detect cell sensitivity to ADM. The results demonstrated that the sensitivity of K562 cells to ADM was mildly enhanced by HCQ, and that the sensitivity of K562/ADM cells to ADM was markedly strengthened by HCQ. In addition, more typical morphological changes associated with apoptosis emerged, and the ratio of Bax/Bcl‑2 and activity of caspase‑3 were markedly increased in K562/ADM cells treated with HCQ. Notably, the expression of mdr1 mRNA and P‑glycoprotein (P‑gp) in drug‑resistant K562/ADM cells was upregulated along with increasing autophagic activity induced by ADM. Furthermore, HCQ significantly reduced the increase in P‑gp expression by inhibiting autophagic activity. Collectively, these findings indicated that the inhibition of autophagy significantly promoted the sensitivity of K562/ADM cells to ADM by facilitating apoptosis. Furthermore, inhibition of autophagy attenuated the expression of P‑gp; therefore, P‑gp may be involved in autophagic regulation in drug‑resistant cells.

Cerebral ischemia and neuroregeneration

Cerebral ischemia is one of the leading causes of morbidity and mortality worldwide. Although stroke (a form of cerebral ischemia)-related costs are expected to reach 240.67 billion dollars by 2030, options for treatment against cerebral ischemia/stroke are limited. All therapies except anti-thrombolytics (i.e., tissue plasminogen activator) and hypothermia have failed to reduce neuronal injury, neurological deficits, and mortality rates following cerebral ischemia, which suggests that development of novel therapies against stroke/cerebral ischemia are urgently needed. Here, we discuss the possible mechanism(s) underlying cerebral ischemia-induced brain injury, as well as current and future novel therapies (i.e., growth factors, nicotinamide adenine dinucleotide, melatonin, resveratrol, protein kinase C isozymes, pifithrin, hypothermia, fatty acids, sympathoplegic drugs, and stem cells) as it relates to cerebral ischemia.

The Role of BCL-2 Family Members in Acute Kidney Injury

B-cell lymphoma 2 (BCL-2) family proteins gather at the biologic cross-roads of renal cell survival: the outer mitochondrial membrane. Despite shared sequence and structural features, members of this conserved protein family constantly antagonize each other in a life-and-death battle. BCL-2 members innocently reside within renal cells until activated or de-activated by physiologic stresses caused by common nephrotoxins, transient ischemia, or acute glomerulonephritis. Recent experimental data not only illuminate the intricate mechanisms of apoptosis, the most familiar form of BCL-2-mediated cell death, but emphasizes their newfound roles in necrosis, necroptosis, membrane pore transition regulated necrosis, and other forms of acute cell demise. A major paradigm shift in non-cell death roles of the BCL-2 family has occurred. BCL-2 proteins also regulate critical daily renal cell housekeeping functions including cell metabolism, autophagy (an effective means for recycling cell components), mitochondrial morphology (organelle fission and fusion), as well as mitochondrial biogenesis. This article considers new concepts in the biochemical and structural regulation of BCL-2 proteins that contribute to membrane pore permeabilization, a universal feature of cell death. Despite these advances, persistent BCL-2 family mysteries continue to challenge cell biologists. Given their interface with many intracellular functions, it is likely that BCL-2 proteins determine cell viability under many pathologic circumstances relevant to the nephrologist and, as a consequence, represent an ideal therapeutic target.

Grape Seed Proanthocyanidin Extract Prevents Ovarian Aging by Inhibiting Oxidative Stress in the Hens

Oxidative stress is an important inducement in ovarian aging which results in fecundity decline in human and diverse animals. As a potent antioxidant, grape seed proanthocyanidin extract (GSPE) was investigated to ameliorate chicken ovarian aging in this study. Firstly, ovarian antioxidant capacity of hens at different ages (90, 150, 280, and 580 days old) was compared to elucidate its age-related changes. Subsequently, a D-gal-induced (2.5 mg/mL) aging ovarian model was established and the cultured ovarian tissues were treated with GSPE at 5 μg/mL for 72 h to evaluate the putative attenuating effects of GSPE on ovarian aging. Meanwhile, ovaries of D280 (young) and D580 (old) were treated with GSPE for 72 h in culture to verify the protective effects of GSPE on natural aging ovary. The results showed that GSPE could rescue the antioxidant capacity decline by increasing the antioxidase activities and their gene expression in either D-gal-induced or natural aging ovaries. Moreover, GSPE could maintain the homeostasis between cell proliferation and apoptosis in the D-gal-induced and natural aging ovaries, as well as alleviate D-gal-induced nucleus chromatin condensation in the ovarian granulosa cells. In conclusion, GSPE treatment can effectively prevent the ovarian aging process in hens by reducing oxidative stress.

Effects of 17-DMAG on diffuse large B-cell lymphoma cell apoptosis

17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) is a water soluble, semisynthetic derivative of endotoxin that has anticancer effects. The aim of the present study was to determine whether 17-DMAG enhances the apoptosis of lymphoma cells in diffuse large B-cell lymphoma. Apoptosis was induced in SU-DHL-4 diffuse large B-cell lymphoma cells treated with 17-DMAG, as evaluated by MTT assay and flow cytometry analysis. Apoptosis-associated protein levels were assessed using western blotting, and the results indicated that B-cell lymphoma 2 (Bcl-2)-associated protein X (Bax) was upregulated, whereas heat shock protein family A member 5 (HSPA5) and Bcl-2 were downregulated. Additionally, staining with 5,5',6,6'-Tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide revealed that treatment with 17-DMAG decreased mitochondrial membrane potential in SU-DHL-4 diffuse large B-cell lymphoma cells. These results suggested that 17-DMAG is able to inhibit proliferation in diffuse large B-cell lymphoma cells in a concentration-dependent manner. The underlying mechanism may be that 17-DMAG induces oxidative stress, which inhibits the expression of HSPA5 and Bcl-2 and promotes the expression of Bax, leading to the apoptosis of SU-DHL-4 cells. Taken together, these results indicated that 17-DMAG may be an effective novel agent for the treatment of diffuse large B-cell lymphoma.

Protective effect of tropisetron on high glucose induced apoptosis and oxidative stress in PC12 cells: roles of JNK, P38 MAPKs, and mitochondria pathway

Tropisetron, a selective 5-HT3 receptor (5-HT3R) antagonist, is widely used to counteract chemotherapy-induced emesis. There is growing interest concerning the beneficial effects of tropisetron on the treatment of several diseases. This study was carried out to examine effects of tropisetron on high glucose (HG) induced apoptosis in PC12 cells as a suitable culture model for studying neuronal functions. Apoptosis was induced by HG, and cells were treated with HG in the absence and presence of tropisetron for varying periods of time. The viability of PC12 cells was measured by MTT assay. The ROS (reactive oxygen species) production, lipid peroxidation (LPO) levels and total antioxidant power (TAP) were measured. The expressions of proapoptotic Bax, antiapoptotic Bcl-2, caspase-3, total and phosphorylated JNK and P38 MAPKs were also examined by western blotting. The results indicated that pretreatment with tropisetron significantly improved the viability of the cells and protected PC12 cells against HG induced apoptotic cell death. It could increase the concentrations of TAP. HG induced ROS generation, Bax expression and caspase 3 activation, were prevented by tropisetron. HG also induced activation of JNK and P38 MAPKs. The phosphorylation of these kinases was inhibited by tropisetron. It may be concluded that tropisetron treatment protects PC12 cells against HG-induced apoptosis by preventing JNK, P38 activation and mitochondrial pathway.

Oxoaporphine Metal Complexes (CoII, NiII, ZnII) with High Antitumor Activity by Inducing Mitochondria-Mediated Apoptosis and S-phase Arrest in HepG2

Three new oxoaporphine Co(II), Ni(II) and Zn(II) complexes 1–3 have been synthesized and fully characterized. 1–3 have similar mononuclear structures with the metal and ligand ratio of 1:2. 1–3 exhibited higher cytotoxicity than the OD ligand and cisplatin against HepG2, T-24, BEL-7404, MGC80–3 and SK-OV-3/DDP cells, with IC₅₀ value of 0.23−4.31 μM. Interestingly, 0.5 μM 1–3 significantly caused HepG2 arrest at S-phase, which was associated with the up-regulation of p53, p21, p27, Chk1 and Chk2 proteins, and decrease in cyclin A, CDK2, Cdc25A, PCNA proteins. In addition, 1–3 induced HepG2 apoptosis via a caspase-dependent mitochondrion pathway as evidenced by p53 activation, ROS production, Bax up-regulation and Bcl-2 down-regulation, mitochondrial dysfunction, cytochrome c release, caspase activation and PARP cleavage. Furthermore, 3 inhibited tumor growth in HepG2 xenograft model, and displayed more safety profile in vivo than cisplatin.

Depletion of NFBD1/MDC1 Induces Apoptosis in Nasopharyngeal Carcinoma Cells Through the p53-ROS-Mitochondrial Pathway

NFBD1, a signal amplifier of the p53 pathway, is vital for protecting cells from p53-mediated apoptosis and the early phase of DNA damage response under normal culture conditions. Here we investigated its expression in patients with nasopharyngeal carcinoma (NPC), and we describe the biological functions of the NFBD1 gene. We found that NFBD1 mRNA and protein were more highly expressed in NPC tissues than in nontumorous tissues. To investigate the function of NFBD1, we created NFBD1-depleted NPC cell lines that exhibited decreased cellular proliferation and colony formation, an increase in their rate of apoptosis, and an enhanced sensitivity to chemotherapeutic agents compared with in vitro controls. However, N-acetyl cysteine (NAC) and downregulation of p53 expression could partially reverse the apoptosis caused by the loss of NFBD1. Further analysis showed that loss of NFBD1 resulted in increased production of intracellular reactive oxygen species (ROS) depending on p53, which subsequently triggered the mitochondrial apoptotic pathway. Using a xenograft model in nude mice, we showed that silencing NFBD1 also significantly inhibited tumor growth and led to apoptosis. Taken together, our data suggest that inhibition of NFBD1 in NPC could be therapeutically useful.

Effects of NMDA-Receptor Antagonist on the Expressions of Bcl-2 and Bax in the Subventricular Zone of Neonatal Rats with Hypoxia-Ischemia Brain Damage

Neonatal hypoxia-ischemia brain damage is an important cause of death by affecting prognosis of neural diseases. It is difficult to find effective methods of prevention and treatment due to the complexity of its pathogenesis. N-methyl-D-aspartate (NMDA), as an excitotoxicity amino acids, has proven to play an important role in hypoxic-ischemic. However, the exact effects of the NMDA subunits, NR2A and NR2B, during hypoxic-ischemic have not been investigated in detail. Therefore, we sought to study whether the NMDA receptor antagonist could confer neuroprotective effects in a neonatal rat hypoxia-ischemia model. The effects of intraperitoneal injections of different drugs, namely MK-801 (0.5 mg/kg), NVP-AAM077 (5 mg/kg), and Ro25-6981 (5 mg/kg), on the expressions of anti-apoptotic protein Bcl-2 and apoptosis protein Bax in the subventricular zone were analyzed by immunohistochemical staining to explore the roles of NMDA subunits (NR2A and NR2B) in hypoxic-ischemic. We found that the NR2B antagonist (Ro25-6981) could inhibit hypoxic-ischemic with the increasing Bcl-2 expression. NR2A antagonists (NVP-AAM077) can increase cerebral hypoxia-ischemia in neonatal rats, promoting the expression of apoptotic protein Bax.

Protective mechanisms of melatonin against hydrogen-peroxide-induced toxicity in human bone-marrow-derived mesenchymal stem cells

Many obstacles compromise the efficacy of bone marrow mesenchymal stem cells (BM-MSCs) by inducing apoptosis in the grafted BM-MSCs. The current study investigates the effect of melatonin on important mediators involved in survival of BM-MSCs in hydrogen peroxide (H₂O₂) apoptosis model. In brief, BM-MSCs were isolated, treated with melatonin, and then exposed to H₂O₂. Their viability was assessed by MTT assay and apoptotic fractions were evaluated through Annexin V, Hoechst staining, and ADP/ATP ratio. Oxidative stress biomarkers including ROS, total antioxidant power (TAP), superoxide dismutase (SOD) and catalase (CAT) activity, glutathione (GSH), thiol molecules, and lipid peroxidation (LPO) levels were determined. Secretion of inflammatory cytokines (TNF-α and IL-6) were measured by ELISA assay. The protein expression of caspase-3, Bax, and Bcl-2, was also evaluated by Western blotting. Melatonin pretreatment significantly increased viability and decreased apoptotic fraction of H₂O₂-exposed BM-MSCs. Melatonin also decreased ROS generation, as well as increasing the activity of SOD and CAT enzymes and GSH content. Secretion of inflammatory cytokines in H₂O₂-exposed cells was also reduced by melatonin. Expression of caspase-3 and Bax proteins in H₂O₂-exposed cells was diminished by melatonin pretreatment. The findings suggest that melatonin may be an effective protective agent against H₂O₂-induced oxidative stress and apoptosis in MSC.

Recurrent phagocytosis-induced apoptosis in the cyclical generation change of the compound ascidian Botryllus schlosseri

Colonies of the marine, filter-feeding ascidian Botryllus schlosseri undergo cyclical generation changes or takeovers. These events are characterised by the progressive resorption of adult zooids and their replacement by their buds that grow to adult size, open their siphons and start filtering. During the take-over, tissues of adult zooids undergo extensive apoptosis; circulating, spreading phagocytes enter the effete tissues, ingest dying cells acquiring a giant size and a round morphology. Then, phagocytes re-enter the circulation where they represent a considerable fraction (more than 20%) of circulating haemocytes. In this study, we evidence that most of these circulating phagocytes show morphological and biochemical signs of apoptosis. Accordingly, these phagocytes express transcripts of orthologues of the apoptosis-related genes Bax, AIF1 and PARP1. Electron microscopy shows that giant phagocytes contain apoptotic phagocytes inside their own phagocytic vacuole. The transcript of the orthologues of the anti-apoptotic gene IAP7 was detected only in spreading phagocytes, mostly abundant in phases far from the take-over. Therefore, the presented data suggest that, at take-over, phagocytes undergo phagocytosis-induced apoptosis (PIA). In mammals, PIA is assumed to be a process assuring the killing and the complete elimination of microbes, by promoting the disposal of terminally differentiated phagocytes and the resolution of infection. In B. schlosseri, PIA assumes a so far undescribed role, being required for the control of asexual development and colony homeostasis.

Inhibitory effects of Shenkang injection and its main component emodin on the proliferation of high glucose‑induced renal mesangial cells through cell cycle regulation and induction of apoptosis

Increased mesangial cell proliferation is a major pathological feature of early-stage diabetic nephropathy (DN). The present study investigated the effects of the Traditional Chinese Medicine Shenkang injection (SKI) and its main component emodin (EM) on high glucose‑cultured mesangial cells. The proliferation rate, cell cycle distribution, apoptosis and morphology of rat renal mesangial cells (RMCs) cultured in the presence of various concentrations of glucose (5.6 or 25 mM), SKI (25, 50 or 100 mg/l) or EM (10, 20 or 40 µM) were assessed at time‑points of 12, 24 or 48 h. High‑glucose treatment promoted the proliferation of RMCs, which was significantly inhibited by SKI and EM, while these drugs had no effect on RMCs under normal glucose conditions, as indicated by an MTT assay. Furthermore, flow cytometric analysis revealed that SKI and EM inhibited the cell cycle progression of RMCs and induced apoptosis. Transmission electron microscopy revealed morphological characteristics of apoptosis and western blot analysis demonstrated the upregulation of B‑cell lymphoma 2‑associated X protein (bax) and activation of caspases in RMCs following treatment with SKI or EM under high‑glucose conditions. In conclusion, SKI and its major active component EM were shown to inhibit high‑glucose‑induced proliferation of RMCs via inducing cell cycle arrest at G1 phase as well as cellular apoptosis via upregulation of pro‑apoptotic mediators bax and caspase activation, and may therefore be suitable for the treatment of DN.

Non-canonical programmed cell death mechanisms triggered by natural compounds

Natural compounds are the fundament of pharmacological treatments and more than 50% of all anticancer drugs are of natural origins or at least derived from scaffolds present in Nature. Over the last 25 years, molecular mechanisms triggered by natural anticancer compounds were investigated. Emerging research showed that molecules of natural origins are useful for both preventive and therapeutic purposes by targeting essential hallmarks and enabling characteristics described by Hanahan and Weinberg. Moreover, natural compounds were able to change the differentiation status of selected cell types. One of the earliest response of cells treated by pharmacologically active compounds is the change of its morphology leading to ultra-structural perturbations: changes in membrane composition, cytoskeleton integrity, alterations of the endoplasmic reticulum, mitochondria and of the nucleus lead to formation of morphological alterations that are a characteristic of both compound and cancer type preceding cell death. Apoptosis and autophagy were traditionally considered as the most prominent cell death or cell death-related mechanisms. By now multiple other cell death modalities were described and most likely involved in response to chemotherapeutic treatment. It can be hypothesized that especially necrosis-related phenotypes triggered by various treatments or evolving from apoptotic or autophagic mechanisms, provide a more efficient therapeutic outcome depending on cancer type and genetic phenotype of the patient. In fact, the recent discovery of multiple regulated forms of necrosis and the initial elucidation of the corresponding cell signaling pathways appear nowadays as important tools to clarify the immunogenic potential of non-canonical forms of cell death induction.

1,25(OH)2D3 inhibits high glucose-induced apoptosis and ROS production in human peritoneal mesothelial cells via the MAPK/P38 pathway

The regulation of cell proliferation, differentiation and immunomodulation are affected by 1,25(OH)2D3. However, its function during apoptosis and oxidative stress in human peritoneal mesothelial cells (HPMCs) remains unknown. The aim of the present study was to investigate whether the regulation of apoptosis and oxidative stress have therapeutic relevance in peritoneal dialysis (PD) therapy. The present study investigated the effects of 1,25(OH)2D3 on high glucose (HG)-induced apoptosis and reactive oxygen species (ROS) production in HPMCs, and examined the underlying molecular mechanisms. Flow cytometry and western blotting were performed to detect cell apoptosis, 2,7-dichlorofluorescein diacetate was used to measure reactive oxygen species production and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to measure cell viability. The results of the present study demonstrated that exposure to HG increased apoptosis and ROS production in HPMCs, whereas pretreatment with 1,25(OH)2D3 significantly inhibited HG‑induced apoptosis and ROS production. Further analysis revealed that 1,25(OH)2D3 facilitated cell survival via the MAPK/P38 pathway. The results of the present study indicate that 1,25(OH)2D3 inhibits apoptosis and ROS production in HG‑induced HPMCs via inhibition of the MAPK/P38 pathway.

The Inhibitory Effect of Rhein on Proliferation of High Glucose-induced Mesangial Cell Through Cell Cycle Regulation and Induction of Cell Apoptosis

Objectives:

Increased mesangial cell proliferation and accumulation of extracellular matrix (ECM) are the major pathological features of early-stage diabetic nephropathy. This study was sought to investigate the inhibitory effects of rhein (RH) on high glucose (HG)-cultured mesangial cells. Specially, we focus on the analysis of proliferation rate, cell cycle regulation, apoptosis, and the expression of collagen IV and laminin.

Materials and Methods:

The established rat renal mesangial cell (RMC) line was cultured in medium with different concentrations of glucose (5.6 mM or 25 mM) and RH (40 μM, 20 μM, and 10 μM). Pro-treated cells were collected at 12 h, 24 h, and 48 h for cell proliferation analysis and after 24 h for the experiments of flow cytometry, transmission electron microscope, real-time polymerase chain reaction, and Western blotting.

Results:

Our data shows HG can promote the proliferation of RMCs and RH has an inhibitory effect on HG-induced RMC proliferation and expression of ECM. Based on our data, we hypothesize this inhibitory effect might be a result of cell cycle regulation and the induction of cellular apoptosis.

Conclusion:

RH can inhibit cellular proliferation and downregulate the expression of ECM under the circumstance of HG. The mechanism of growth suppression may be due to cell cycle arrest at G₁ phase, induction of cell apoptosis, and upregulation of apoptotic mediators bax and caspase-3.

SUMMARY

Rhein (RH) has an inhibitory effect on high glucose.induced rat mesangial cells proliferation

RH has an inhibitory effect on the expression of extracellular matrix

RH has a growth.suppression effect

RH can upregulate the expression of apoptotic mediators bax and caspase-3

All above shows RH is one of the main active ingredient in Shenkang injection.

Abbreviations used: RH: Rhein, ECM: Extracellular matrix, DN: Diabetic nephropathy, RMC: Renal mesangial cell, SKI: Shenkang injection, MTT: 3-(4,5-dimethylthiazol–2-yl)-2,5-diphenyltetrazolium bromide

Naringin inhibits lipopolysaccharide-induced damage in human umbilical vein endothelial cells via attenuation of inflammation, apoptosis and MAPK pathways

Endothelial cell activation, injury and dysfunction have been regarded as one of the initial key events in the pathogenesis of atherosclerosis. Lipopolysaccharide (LPS), an important mediator of inflammation, can cause endothelial cell damage and apoptosis. Naringin (Nar), one major flavanone glycoside from citrus fruits, shows various pharmacological actions, but the effect of Nar on LPS-induced damage in human umbilical vein endothelial cells (HUVECs) remains unknown. The present results showed that Nar significantly improved the survival rate of HUVECs, and decreased reactive oxygen species and intracellular Ca(2+) levels caused by LPS compared with model group. In addition, Nar obviously decreased cytochrome c release from mitochondria into cytosol. Moreover, Nar significantly down-regulated the protein or mRNA levels of IL-1, IL-6, TNF-α, VCAM-1, ICAM-1, NF-κB, AP-1, cleaved-3,-7,-9, p53, Bak and Bax, and up-regulated the expressions of Bcl-xl, Bcl-2 to suppress inflammation and apoptosis. Furthermore, Nar obviously inhibited phosphorylation levels of JNK, ERK and p38 MAPK. In conclusion, Nar exhibited potent effects against LPS-induced damage in HUVECs through the modulation of oxidative stress, inflammation, apoptosis and MAPK pathways, which should be developed as a potent candidate for the treatment of atherosclerosis in the future.

Cissus quadrangularis Linn. Stem Ethanolic Extract Liberates Reactive Oxygen Species and Induces Mitochondria Mediated Apoptosis in KB Cells

Background:

Cissus quadrangularis Linn. (CQ) commonly known as Hadjod (Family: Vitaceae) is usually distributed in India and Sri Lanka and contains several bioactive compounds responsible for various metabolic and physiologic effects.

Objective:

In this study, the biological effects of CQ ethanolic extract were evaluated by in vitro and supported by in silico analysis on KB oral epidermoid cancer cell line.

Materials and Methods:

Anti-cancer potential of ethanolic extract of CQ stem against KB oral epidermoid cancer cells was evaluated in terms of morphological analysis, nuclei staining, liberation of reactive oxygen species (ROS), cell cycle arrest, mitochondrial membrane potential (MMP) and p53 and Bcl-2 protein expression which reveal the induction of apoptosis along with supporting in silico analysis.

Results:

Ethanolic extract of CQ stem contains various bioactive compounds responsible for cancer cell morphological alterations, liberation of ROS, G1 phase cell cycle arrest and decreased MMP along with up-regulation of p53 and down-regulation of Bcl-2. By employing in silico approach, we have also postulated that the CQ extract active constituents sequester Bcl-2 with higher affinity as compared to p53, which may be the reason for induction of growth arrest and apoptosis in KB cells.

Conclusion:

Our data indicate that the CQ extract has a remarkable apoptotic effect that suggests that it could be a viable treatment option for specific types of cancers.

SUMMARY

Cissus quadrangularis stem ethanolic extract induces apoptosis and cell cycle arrest at G1 phase

It liberates (ROS) and mitochondria mediated apoptosis

It upregulates p53 and down-regulates Bcl-2 protein expression

In silico studies indicates that the active constituents of CQ binds Bcl-2 with higher affinity as compared to p53.

ROS and ROS-Mediated Cellular Signaling

It has long been recognized that an increase of reactive oxygen species (ROS) can modify the cell-signaling proteins and have functional consequences, which successively mediate pathological processes such as atherosclerosis, diabetes, unchecked growth, neurodegeneration, inflammation, and aging. While numerous articles have demonstrated the impacts of ROS on various signaling pathways and clarify the mechanism of action of cell-signaling proteins, their influence on the level of intracellular ROS, and their complex interactions among multiple ROS associated signaling pathways, the systemic summary is necessary. In this review paper, we particularly focus on the pattern of the generation and homeostasis of intracellular ROS, the mechanisms and targets of ROS impacting on cell-signaling proteins (NF-κB, MAPKs, Keap1-Nrf2-ARE, and PI3K-Akt), ion channels and transporters (Ca(2+) and mPTP), and modifying protein kinase and Ubiquitination/Proteasome System.

Free Radical Scavenging Activity: Antiproliferative and Proteomics Analyses of the Differential Expression of Apoptotic Proteins in MCF-7 Cells Treated with Acetone Leaf Extract of Diospyros lycioides (Ebenaceae)

Breast cancer is the most common cancer in South Africa. The acetone leaf extract of Diospyros lycioides was evaluated qualitatively and quantitatively for its antioxidant potential using DPPH assay and nitric oxide radical scavenging effect, while the viability of MCF-7 cells was evaluated using the MTT. MCF-7 treated cells were stained with Hoechst 335258 dye and annexin-V-FITC to be evaluated for apoptotic effect of the extract, while mRNA expression levels of apoptotic genes were assessed by quantitative real-time PCR and deferential protein expression levels using 2D gel electrophoresis and mass spectrometry. Results revealed presence of antioxidant constituents in the extract. Extract was shown to be cytotoxic in a concentration- and time-dependent manner. Cytotoxicity was demonstrated to be due to apoptosis, with 70% of the extract-treated cells being annexin-V-positive/PI negative at 48 hours. The extract was also shown to upregulate the expression of p53 gene with concomitant downregulation of the Bcl-2 antiapoptotic gene while differentially expressed proteins were identified as enolase, pyruvate kinase, and glyceraldehyde-3-phosphate. The extract in this study was shown to induce apoptosis at an early stage which makes it an ideal source that can be explored for compounds that may be used in the treatment and management of cancer.

Tricyclic Antidepressants Amitriptyline and Desipramine Induced Neurotoxicity Associated with Parkinson's Disease

Recent studies report that a history of antidepressant use is strongly correlated with the occurrence of Parkinson's disease (PD). However, it remains unclear whether antidepressant use can be a causative factor for PD. In the present study, we examined whether tricyclic antidepressants amitriptyline and desipramine can induce dopaminergic cell damage, both in vitro and in vivo. We found that amitriptyline and desipramine induced mitochondria-mediated neurotoxicity and oxidative stress in SH-SY5Y cells. When injected into mice on a subchronic schedule, amitriptyline induced movement deficits in the pole test, which is known to detect nigrostriatal dysfunction. In addition, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was reduced in amitriptyline-injected mice. Our results suggest that amitriptyline and desipramine may induce PD-associated neurotoxicity.

The Bax inhibitor MrBI-1 regulates heat tolerance, apoptotic-like cell death, and virulence in Metarhizium robertsii

Bax inhibitor 1 (BI-1) is a highly conserved protein originally identified as a suppressor of the proapoptotic protein Bax to inhibit cell death in animals and plants. The orthologs of BI-1 are widely distributed in filamentous fungi but their functions remain largely unknown. Herein, we report the identification and characterizations of MrBI-1, an ortholog of BI-1, in the entomopathogenic fungus Metarhizium robertsii. First, we found that MrBI-1 could partially rescue mammalian Bax-induced cell death in yeast. Deletion of MrBI-1 impaired fungal development, virulence and heat tolerance in M. robertsii. We also demonstrated that inactivation of MrBI-1 reduced fungal resistance to farnesol but not to hydrogen peroxide, suggesting that MrBI-1 contributes to antiapoptotic-like cell death via the endoplasmic reticulum stress-signaling pathway rather than the classical mitochondrium-dependent pathway. In particular, we found that unlike the observations in yeasts and plants, expression of mammalian Bax did not lead to a lethal effect in M. robertsii; however, it did aggravate the fungal apoptotic effect of farnesol. The results of this study advance our understanding of BI-1-like protein functions in filamentous fungi.

Synergistic induction of apoptosis in A549 cells by dihydroartemisinin and gemcitabine

This report is designed to study the ability of the combined treatment with gemcitabine (Gem) and dihydroartemisinin (DHA) to induce apoptosis in a non-small-cell lung cancer cell line (A549 cells). This combination treatment synergistically inhibited cell growth by inducing apoptosis, and this synergistic action was not associated with reactive oxygen species (ROS). Although either Gem or DHA induced a significant increase in ROS generation, the combination treatment did not further enhance ROS level. Compared with single drugs, the combination treatment significantly potentiated Bak activation, loss of mitochondrial membrane potential, caspase-9 and -3 activation, indicating the important role of the Bak-mediated intrinsic apoptosis pathway in the synergistic action, which was further verified by the significant prevention of the cytotoxicity of the combination treatment by inhibiting one of caspase-9, -3 and Bcl-xL or silencing Bak. In addition, the combination treatment also synergistically activated caspase-8, and inhibition of Fas and caspase-8 presented significant prevention on the cytotoxicity of the combination treatment, indicating that the Fas-caspase-8-mediated extrinsic apoptosis pathway partially participated in the synergistic action. Collectively, the present study demonstrates a strong synergistic action of the combined treatment with Gem and DHA in inducing apoptosis of A549 cells via both the Bak-mediated intrinsic pathway and the Fas-caspase-8-mediated extrinsic pathway.

Cancer-type-specific crosstalk between autophagy, necroptosis and apoptosis as a pharmacological target

Cell death plays an essential role in the development of organs, homeostasis, and cancer. Apoptosis and programmed necrosis are two major types of cell death, characterized by different cell morphology and pathways. Accumulating evidence shows autophagy as a new alternative target to treat tumor resistance. Besides its well-known pro-survival role, autophagy can be a physiological cell death process linking apoptosis and programmed necrosis cell death pathways, by various molecular mediators. Here, we summarize the effects of pharmacologically active compounds as modulators of different types of cancer cell death depending on the cellular context. Indeed, current findings show that both natural and synthetic compounds regulate the interplay between apoptosis, autophagy and necroptosis stimulating common molecular mediators and sharing common organelles. In response to specific stimuli, the same death signal can cause cells to switch from one cell death modality to another depending on the cellular setting. The discovery of important interconnections between the different cell death mediators and signaling pathways, regulated by pharmacologically active compounds, presents novel opportunities for the targeted treatment of cancer. The aim of this review is to highlight the potential role of these compounds for context-specific anticancer therapy.

The pathways by which mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury

Several studies have demonstrated that mild hypothermia exhibits a neuroprotective role and it can inhibit endothelial cell apoptosis following ischemia/reperfusion injury by decreasing caspase-3 expression. It is hypothesized that mild hypothermia exhibits neuroprotective effects on neurons exposed to ischemia/reperfusion condition produced by oxygen-glucose deprivation. Mild hypothermia significantly reduced the number of apoptotic neurons, decreased the expression of pro-apoptotic protein Bax and increased mitochondrial membrane potential, with the peak of anti-apoptotic effect appearing between 6 and 12 hours after the injury. These findings indicate that mild hypothermia inhibits neuronal apoptosis following ischemia/reperfusion injury by protecting the mitochondria and that the effective time window is 6-12 hours after ischemia/reperfusion injury.

Investigating the protective effect of lithium against high glucose-induced neurotoxicity in PC12 cells: involvements of ROS, JNK and P38 MAPKs, and apoptotic mitochondria pathway

Hyperglycemia that occurs under the diabetic condition is a major cause of diabetic complications such as diabetic neuropathy, one of the most common diabetes-related complications. It is well known that hyperglycemia could result in generation of reactive oxygen species (ROS). Over production of ROS recommended as an important mediator for apoptotic signaling pathway as well as a key early event in the development of diabetic neuropathy. Recently, many studies have indicated that lithium has robust neuroprotective effect in relation to several neurodegenerative diseases. The present study aimed to examine effects of lithium on high glucose (HG)-induced neurotoxicity and to determine some of the underlying molecular mechanisms involved in this response in PC12 cells as a neuronal culture model for diabetic neuropathy. PC12 cells were pretreated with different concentrations of lithium for 7 days, exposed to HG for 24 h. Cell viability was measured by MTT assay. ROS and lipid peroxidation levels as well as superoxide dismutase activity were measured. In order to examine the underlying molecular mechanisms, the expressions of Bax, Bcl-2, Caspase-3, total and phosphorylated JNK and P38 MAPK were also analyzed by Western blotting. The present results indicated that pretreatment with 1 mM lithium has protected PC12 cells against HG-induced apoptotic cell death. It could reduce ROS generation, Bax/Bcl-2 ratio, Caspase-3 activation, and JNK and P38 MAPK phosphorylation. It may be concluded that in HG condition, lithium pretreatment could prevent mitochondrial apoptosis as well as JNK and P38 MAPK pathway in PC12 cells.

Mitochondrial and metabolic dysfunction in renal convoluted tubules of obese mice: protective role of melatonin

Obesity is a common and complex health problem, which impacts crucial organs; it is also considered an independent risk factor for chronic kidney disease. Few studies have analyzed the consequence of obesity in the renal proximal convoluted tubules, which are the major tubules involved in reabsorptive processes. For optimal performance of the kidney, energy is primarily provided by mitochondria. Melatonin, an indoleamine and antioxidant, has been identified in mitochondria, and there is considerable evidence regarding its essential role in the prevention of oxidative mitochondrial damage. In this study we evaluated the mechanism(s) of mitochondrial alterations in an animal model of obesity (ob/ob mice) and describe the beneficial effects of melatonin treatment on mitochondrial morphology and dynamics as influenced by mitofusin-2 and the intrinsic apoptotic cascade. Melatonin dissolved in 1% ethanol was added to the drinking water from postnatal week 5–13; the calculated dose of melatonin intake was 100 mg/kg body weight/day. Compared to control mice, obesity-related morphological alterations were apparent in the proximal tubules which contained round mitochondria with irregular, short cristae and cells with elevated apoptotic index. Melatonin supplementation in obese mice changed mitochondria shape and cristae organization of proximal tubules, enhanced mitofusin-2 expression, which in turn modulated the progression of the mitochondria-driven intrinsic apoptotic pathway. These changes possibly aid in reducing renal failure. The melatonin-mediated changes indicate its potential protective use against renal morphological damage and dysfunction associated with obesity and metabolic disease.

Pro-apoptotic activities of polyphenolics from açai (Euterpe oleracea Martius) in human SW-480 colon cancer cells

This study aimed to evaluate the cell growth inhibition activity of açai (Euterpe oleracea Mart.) polyphenolic extract against colon cancer HT-29 and SW-480 cells and the nonmalignant CCD-18Co colon fibroblast cells. Results showed that açai polyphenolic extract (5-20 mg/L) inhibited preferentially the growth of SW-480 cells with no toxicity in CCD-18Co cells, and this was accompanied by reduction of H2O2-induced reactive oxygen species (ROS) generation. The mechanisms involved in SW-480 cell growth-inhibition by açai polyphenolic extract included the downregulation of NF-κB proinflammatory transcription factor and the nuclear factor-kappa B targets intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Furthermore, prooncogenic specificity proteins (Sp) were downregulated as well as Sp-targets Bcl-2, vascular endothelial growth factor, and survivin. This was accompanied by activation of mitochondrial proapoptotic pathway involving increase of cytochrome c, cleavage of caspase-3, and decrease of PARP-1. Results strongly suggest that açai polyphenolic extract has antiinflammatory and cytotoxic activities in colon cancer cells and can be effective as natural colon cancer chemopreventive agents.

Potent effects of flavonoid-rich extract from Rosa laevigata Michx fruit against hydrogen peroxide-induced damage in PC12 cells via attenuation of oxidative stress, inflammation and apoptosis

Oxidative stress-induced neuronal death has an important role in the pathogenesis of neurodegenerative disorders. The effects and mechanisms of action of the total flavonoids (TFs) from Rosa laevigata Michx fruit against hydrogen peroxide (H₂O₂)-induced oxidative injury in PC12 cells were investigated in this study. The results demonstrated that the TFs protected against cell apoptosis, DNA and mitochondrial damage caused by H₂O₂ based on single cell gel electrophoresis, in situ terminal deoxynucleotidyltransferase dUTP nick end labeling (TUNEL), flow cytometry and transmission electron microscope (TEM) assays. In addition, the TFs notably decreased cytochrome C release from mitochondria into the cytosol and intracellular Ca²⁺ levels, and diminished intracellular generation of reactive oxygen species (ROS). Furthermore, the TFs inhibited the phosphorylation levels of JNK, ERK and p38 MAPK as well as down-regulated the expressions of IL-1, IL-6, TNF-α, Fas, FasL, CYP2E1, Bak, caspase-3, caspase-9, p53, COX-2, NF-κB, AP-1, and up-regulated the expressions of Bcl-2 and Bcl-xl. In conclusion, these results suggest that the TFs from R. laevigata Michx fruit show good effects against H₂O₂-induced oxidative injury in PC12 cells by adjusting oxidative stress, and suppression of apoptosis and inflammation, and could be developed as a potential candidate to prevent oxidative stress in the future.

Energy restriction mimetic agents to target cancer cells: comparison between 2-deoxyglucose and thiazolidinediones

The use of energy restriction mimetic agents (ERMAs) to selectively target cancer cells addicted to glycolysis could be a promising therapeutic approach. Thiazolidinediones (TZDs) are synthetic agonists of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)γ that were developed to treat type II diabetes. These compounds also display anticancer effects which appear mainly to be independent of their PPARγ agonist activity but the molecular mechanisms involved in the anticancer action are not yet well understood. Results obtained on ciglitazone derivatives, mainly in prostate cancer cell models, suggest that these compounds could act as ERMAs. In the present paper, we introduce how compounds like 2-deoxyglucose target the Warburg effect and then we discuss the possibility that the PPARγ-independent effects of various TZD could result from their action as ERMAs.

Modulatory roles of glycolytic enzymes in cell death

Cancer cells depend on an altered energy metabolism characterized by increased rates of both glycolysis and glutaminolysis. Accordingly, corresponding key metabolic enzymes are overexpressed or hyperactivated. As a result, this newly acquired metabolic profile determines most other cancer hallmarks including resistance to cell death. Recent findings highlighted metabolic enzymes as direct modulators of cell death pathways. Conversely, key mediators of cell death mechanisms are emerging as new binding partners of glycolytic actors; moreover, there is evidence that metabolic regulators re-localize to specific subcellular compartments or organelles to modulate various types of cell demise. The final outcome is the resistance against cell death programs. Current findings give a new meaning to metabolic pathways and allow understanding how they affect cancer-specific pathological alterations. Furthermore, they shed light on potentially targetable functions of metabolic actors to restore susceptibility of cancer cells to death. Here, we discuss an emerging interplay between cell metabolism and cell death, focusing on interactions that may offer new options of targeted therapies in cancer treatment involving more specifically hexokinases and glyceraldehyde-3-phosphate dehydrogenase.

Plumbagin modulates leukemia cell redox status

Plumbagin is a plant naphtoquinone exerting anti-cancer properties including apoptotic cell death induction and generation of reactive oxygen species (ROS). The aim of this study was to elucidate parameters explaining the differential leukemia cell sensitivity towards this compound. Among several leukemia cell lines, U937 monocytic leukemia cells appeared more sensitive to plumbagin treatment in terms of cytotoxicity and level of apoptotic cell death compared to more resistant Raji Burkitt lymphoma cells. Moreover, U937 cells exhibited a ten-fold higher ROS production compared to Raji. Neither differential incorporation, nor efflux of plumbagin was detected. Pre-treatment with thiol-containing antioxidants prevented ROS production and subsequent induction of cell death by apoptosis whereas non-thiol-containing antioxidants remained ineffective in both cellular models. We conclude that the anticancer potential of plumbagin is driven by pro-oxidant activities related to the cellular thiolstat.

Cationic lipid-conjugated dexamethasone as a selective antitumor agent

Dexamethasone (Dex) is one of the highly potent synthetic glucocorticoids. It exhibits prominent anti-inflammatory but moderate anti-proliferative activities. It is widely used along side chemotherapy to alleviate toxic side effects. Additionally, Dex is also a potent inducer of gluconeogenesis. However, its overuse critically desensitizes cells against chemotherapy. Herein, we report on the development of a new class of cationic lipid-Dex conjugates in which the C-8 carbon chain analogue (DX8) exhibited glucocorticoid receptor (GR)-mediated, caspase-3-assisted, cancer cell-selective anti-proliferative activity. Melanoma tumors in DX8-treated mice exhibited significantly reduced tumor aggressiveness with respect to tumors in Dex-treated mice. Tumor lysates prepared from DX8-treated group showed elevated levels of p53. DX8-treated cancer cells showed clear degradation of kinase JAK3/STAT3 protein levels. Additionally, DX8-treatment decreased the level of VEGFR2 in tumor-endothelial cells implying DX8's anti-proliferative roles in both tumor cells and tumor neovascular cells. Collectively, our results demonstrate potent anti-angiogenic, and selective JAK3/STAT3 down-regulating anticancer characteristics of DX8, a new dexamethasone-based antitumor molecule.

Natural compound Alternol induces oxidative stress-dependent apoptotic cell death preferentially in prostate cancer cells

Prostate cancers at the late stage of castration resistance are not responding well to most of current therapies available in clinic, reflecting a desperate need of novel treatment for this life-threatening disease. In this study, we evaluated the anticancer effect of a recently isolated natural compound, Alternol, in multiple prostate cancer cell lines with the properties of advanced prostate cancers in comparison to prostate-derived nonmalignant cells. As assessed by trypan blue exclusion assay, significant cell death was observed in all prostate cancer cell lines except DU145 but not in nonmalignant (RWPE-1 and BPH1) cells. Further analyses revealed that Alternol-induced cell death was an apoptotic response in a dose- and time-dependent manner, as evidenced by the appearance of apoptosis hallmarks such as caspase-3 processing and PARP cleavage. Interestingly, Alternol-induced cell death was completely abolished by reactive oxygen species scavengers N-acetylcysteine and dihydrolipoic acid. We also demonstrated that the proapoptotic Bax protein was activated after Alternol treatment and was critical for Alternol-induced apoptosis. Animal xenograft experiments in nude mice showed that Alternol treatment largely suppressed tumor growth of PC-3 xenografts but not Bax-null DU-145 xenografts in vivo. These data suggest that Alternol might serve as a novel anticancer agent for patients with late-stage prostate cancer.