Bcl-XL interacts with Apaf-1 and inhibits Apaf-1-dependent caspase-9 activation

A comparative study of apoptosis, pyroptosis, necroptosis, and PANoptosis components in mouse and human cells

Regulated cell death is a key component of the innate immune response, which provides the first line of defense against infection and homeostatic perturbations. However, cell death can also drive pathogenesis. The most well-defined cell death pathways can be categorized as nonlytic (apoptosis) and lytic (pyroptosis, necroptosis, and PANoptosis). While specific triggers are known to induce each of these cell death pathways, it is unclear whether all cell types express the cell death proteins required to activate these pathways. Here, we assessed the protein expression and compared the responses of immune and non-immune cells of human and mouse origin to canonical pyroptotic (LPS plus ATP), apoptotic (staurosporine), necroptotic (TNF-α plus z-VAD), and PANoptotic (influenza A virus infection) stimuli. When compared to fibroblasts, both mouse and human innate immune cells, macrophages, expressed higher levels of cell death proteins and activated cell death effectors more robustly, including caspase-1, gasdermins, caspase-8, and RIPKs, in response to specific stimuli. Our findings highlight the importance of considering the cell type when examining the mechanisms regulating inflammation and cell death. Improved understanding of the cell types that contain the machinery to execute different forms of cell death and their link to innate immune responses is critical to identify new strategies to target these pathways in specific cellular populations for the treatment of infectious diseases, inflammatory disorders, and cancer.

In situ vaccination caused by diverse irradiation-driven cell death programs

Interest surrounding the effect of irradiation on immune activation has exponentially grown within the last decade. This includes work regarding mechanisms of the abscopal effect and the success achieved by combination of radiotherapy and immunotherapy. It is hypothesized that irradiation triggers the immune system to eliminate tumors by inducing tumor cells immunogenic cell death (ICD) in tumor cells. Activation of the ICD pathways can be exploited as an in situ vaccine. In this review, we provide fundamental knowledge of various forms of ICD caused by irradiation, describe the relationship between various cell death pathways and the immune activation effect driven by irradiation, and focus on the therapeutic value of exploiting these cell death programs in the context of irradiation. Furthermore, we summarize the immunomodulatory effect of different cell death programs on combinative radiotherapy and immunotherapy. In brief, differences in cell death programs significantly impact the irradiation-induced immune activation effect. Evaluating the transition between them will provide clues to develop new strategies for radiotherapy and its combination with immunotherapy.

Inhibition of Caspase 3 and Caspase 9 Mediated Apoptosis: A Multimodal Therapeutic Target in Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the significant causes of death and morbidity, and it is hence a focus of translational research. Apoptosis plays an essential part in the pathophysiology of TBI, and its inhibition may help overcome TBI's negative consequences and improve functional recovery. Although physiological neuronal death is necessary for appropriate embryologic development and adult cell turnover, it can also drive neurodegeneration. Caspases are principal mediators of cell death due to apoptosis and are critical for the required cleavage of intracellular proteins of cells committed to die. Caspase-3 is the major executioner Caspase of apoptosis and is regulated by a range of cellular components during physiological and pathological conditions. Activation of Caspase-3 causes proteolyzation of DNA repair proteins, cytoskeletal proteins, and the inhibitor of Caspase-activated DNase (ICAD) during programmed cell death, resulting in morphological alterations and DNA damage that define apoptosis. Caspase-9 is an additional crucial part of the intrinsic pathway, activated in response to several stimuli. Caspases can be altered post-translationally or by modulatory elements interacting with the zymogenic or active form of a Caspase, preventing their activation. The necessity of Caspase-9 and -3 in diverse apoptotic situations suggests that mammalian cells have at least four distinct apoptotic pathways. Continued investigation of these processes is anticipated to disclose new Caspase regulatory mechanisms with consequences far beyond apoptotic cell death control. The present review discusses various Caspase-dependent apoptotic pathways and the treatment strategies to inhibit the Caspases potentially.

Endoplasmic Reticulum Stress Signaling and Neuronal Cell Death

Besides protein processing, the endoplasmic reticulum (ER) has several other functions such as lipid synthesis, the transfer of molecules to other cellular compartments, and the regulation of Ca²⁺ homeostasis. Before leaving the organelle, proteins must be folded and post-translationally modified. Protein folding and revision require molecular chaperones and a favorable ER environment. When in stressful situations, ER luminal conditions or chaperone capacity are altered, and the cell activates signaling cascades to restore a favorable folding environment triggering the so-called unfolded protein response (UPR) that can lead to autophagy to preserve cell integrity. However, when the UPR is disrupted or insufficient, cell death occurs. This review examines the links between UPR signaling, cell-protective responses, and death following ER stress with a particular focus on those mechanisms that operate in neurons.

ILP-2: A New Bane and Therapeutic Target for Human Cancers

Inhibitor of apoptosis protein-related-like protein-2 (ILP-2), also known as BIRC-8, is a member of the inhibitor of apoptosis protein (IAPs) family, which mainly encodes the negative regulator of apoptosis. It is selectively overexpressed in a variety of human tumors and can help tumor cells evade apoptosis, promote tumor cell growth, increase tumor cell aggressiveness, and appears to be involved in tumor cell resistance to chemotherapeutic drugs. Several studies have shown that downregulation of ILP-2 expression increases apoptosis, inhibits metastasis, reduces cell growth potential, and sensitizes tumor cells to chemotherapeutic drugs. In addition, ILP-2 inhibits apoptosis in a unique manner; it does not directly inhibit the activity of caspases but induces apoptosis by cooperating with other apoptosis-related proteins. Here, we review the current understanding of the various roles of ILP-2 in the apoptotic cascade and explore the use of interfering ILP-2, and the combination of related anti-tumor agents, as a novel strategy for cancer therapy.

Programmed cell death detection methods: a systematic review and a categorical comparison

Programmed cell death is considered a key player in a variety of cellular processes that helps to regulate tissue growth, embryogenesis, cell turnover, immune response, and other biological processes. Among different types of cell death, apoptosis has been studied widely, especially in the field of cancer research to understand and analyse cellular mechanisms, and signaling pathways that control cell cycle arrest. Hallmarks of different types of cell death have been identified by following the patterns and events through microscopy. Identified biomarkers have also supported drug development to induce cell death in cancerous cells. There are various serological and microscopic techniques with advantages and limitations, that are available and are being utilized to detect and study the mechanism of cell death. The complexity of the mechanism and difficulties in distinguishing among different types of programmed cell death make it challenging to carry out the interventions and delay its progression. In this review, mechanisms of different forms of programmed cell death along with their conventional and unconventional methods of detection of have been critically reviewed systematically and categorized on the basis of morphological hallmarks and biomarkers to understand the principle, mechanism, application, advantages and disadvantages of each method. Furthermore, a very comprehensive comparative analysis has been drawn to highlight the most efficient and effective methods of detection of programmed cell death, helping researchers to make a reliable and prudent selection among the available methods of cell death assay. Conclusively, how programmed cell death detection methods can be improved and can provide information about distinctive stages of cell death detection have been discussed.

Chidamide augment sorafenib-derived anti-tumor activities in human osteosarcoma cells lines and xenograft mouse model

Previous studies have showed promising but short-lived activity of sorafenib in osteosarcoma treatments. Researches have suggested ameliorated sensitivity to standard dose of conventional cancer therapies in combination with histone deacetylase inhibitors (HDACis) through various mechanisms. Herein, for the first time, we exploited the synergism of combination therapies with sorafenib and chidamide, a member of HDACis, in the control of OS using human OS cell lines and OS xenograft mouse model and discussed interactive mechanisms between the two drugs. The combination therapy exerted a strong synergism in the inhibition of OS cell proliferation, meanwhile prominently induced cell apoptosis and cell cycle arrest in G0/G1 phase in OS cells with increased expression of MCL-1, decreased expression of caspase-3 and P21, along with diminished level of the overlapped protein P-ERK1/2. Furthermore, oral administration of the combined treatment led to a more optical therapeutic outcome, including lower degrees of tumoral cell proliferation, greater extent of apoptosis, along with induction of cell cycle arrest in tumor tissues, while exhibiting minimal toxicity. This study shows that the combination of sorafenib and chidamide can combat OS in a synergistic fashion and prompts the promising development of innovative combined therapeutic strategies for OS.

The concept of intrinsic versus extrinsic apoptosis

Regulated cell death is a vital and dynamic process in multicellular organisms that maintains tissue homeostasis and eliminates potentially dangerous cells. Apoptosis, one of the better-known forms of regulated cell death, is activated when cell-surface death receptors like Fas are engaged by their ligands (the extrinsic pathway) or when BCL-2-family pro-apoptotic proteins cause the permeabilization of the mitochondrial outer membrane (the intrinsic pathway). Both the intrinsic and extrinsic pathways of apoptosis lead to the activation of a family of proteases, the caspases, which are responsible for the final cell demise in the so-called execution phase of apoptosis. In this review, I will first discuss the most common types of regulated cell death on a morphological basis. I will then consider in detail the molecular pathways of intrinsic and extrinsic apoptosis, discussing how they are activated in response to specific stimuli and are sometimes overlapping. In-depth knowledge of the cellular mechanisms of apoptosis is becoming more and more important not only in the field of cellular and molecular biology but also for its translational potential in several pathologies, including neurodegeneration and cancer.

PELI1 promotes radiotherapy sensitivity by inhibiting noncanonical NF-κB in esophageal squamous cancer

The low sensitivity of radiotherapy is the main cause of tumor tolerance against ionizing radiation (IR). However, the molecular mechanisms by which radiosensitivity is controlled remain elusive. Here, we observed that high expression of pellino E3 ubiquitin protein ligase 1 (PELI1) was correlated with improved prognosis in human esophageal squamous cell carcinoma stage III patients that received adjuvant radiotherapy. Moreover, we found PELI1‐mediated IR‐induced tumor cell apoptosis in vivo and in vitro. Mechanistically, PELI1 mediated the lysine 48 (Lys48)–linked polyubiquitination and degradation of NF‐κB–inducing kinase (NIK; also known as MAP3K14), the master kinase of the noncanonical NF‐κB pathway, thereby inhibiting IR‐induced activation of the noncanonical NF‐κB signaling pathway during radiotherapy. As a consequence, PELI1 inhibited the noncanonical NF‐κB–induced expression of the anti‐apoptotic gene BCL2 like 1 (Bclxl; also known as BCL2L1), leading to an enhancement of the IR‐induced apoptosis signaling pathway and ultimately promoting IR‐induced apoptosis in tumor cells. Therefore, Bclxl or NIK knockdown abolished the apoptosis‐resistant effect in PELI1‐knockdown tumor cells after radiotherapy. These findings establish PELI1 as a critical tumor intrinsic regulator in controlling the sensitivity of tumor cells to radiotherapy through modulating IR‐induced noncanonical NF‐κB expression.

Contribution of Apaf-1 to the pathogenesis of cancer and neurodegenerative diseases

Deregulation of apoptosis is associated with various pathologies, such as neurodegenerative disorders at one end of the spectrum and cancer at the other end. Generally speaking, differentiated cells like cardiomyocytes, skeletal myocytes and neurons exhibit low levels of Apaf-1 (Apoptotic protease activating factor 1) protein suggesting that down-regulation of Apaf-1 is an important event contributing to the resistance of these cells to apoptosis. Nonetheless, upregulation of Apaf-1 has not emerged as a common phenomenon in pathologies associated with enhanced neuronal cell death, i.e., neurodegenerative diseases. In cancer, on the other hand, Apaf-1 downregulation is a common phenomenon, which occurs through various mechanisms including mRNA hyper-methylation, gene methylation, Apaf-1 localization in lipid rafts, inhibition by microRNAs, phosphorylation, and interaction with specific inhibitors. Due to the diversity of these mechanisms and involvement of other factors, defining the exact contribution of Apaf-1 to the development of cancer in general and neurodegenerative disorders, in particular, is complicated. The current review is an attempt to provide a comprehensive image of Apaf-1's contribution to the pathologies observed in cancer and neurodegenerative diseases with the emphasis on the therapeutic aspects of Apaf-1 as an important target in these pathologies.

Intrinsic and extrinsic pathways of apoptosis: Role in cancer development and prognosis

Apoptosis, also named programmed cell death, is a fundament process required for morphogenetic homeostasis during early development and in pathophysiological conditions. It is come into existence in 1972 by work of Kerr, Wyllie and Currie and later on investigated during the research on development of the C. elegans. Trigger by several stimuli, apoptosis is necessary during the embryonic development and aging as homeostatic mechanism to control the cell population and also play a key role as defense mechanism against the immune responses and elimination of damaged cells. Cancer, a genetic disease, is a growing burden on the health and economy of both developing and developed countries. Every year there is tremendously increasing in the number of new cancer cases and mortality rate. Although, there is a significant improvement have been made in biotechnological and bioinformatic fields however, the therapeutic advantages and cancer etiology is still under explored. Several studies determined the deregulation of different apoptotic components during the cancer development and progression. Apoptosis relies on activation of distinct signaling pathways that are often deregulated in cancer. Thus, exploring the single or more than one apoptotic component underlying their expression in carcinogenesis could help to track the disease progression. Current book chapter will provide the several evidences supporting the use of different apoptotic components as prognosis and prediction markers in various human cancer types.

Apaf-1 Pyroptosome Senses Mitochondrial Permeability Transition

Caspase-4 is an intracellular sensor for cytosolic bacterial lipopolysaccharide (LPS) and underlies infection-elicited pyroptosis. It is unclear whether and how caspase-4 detects host-derived factors to trigger pyroptosis. Here we show that mitochondrial permeability transition (MPT) activates caspase-4 by promoting the assembly of a protein complex, which we term the Apaf-1 pyroptosome, for the execution of facilitated pyroptosis. MPT, when induced by bile acids, calcium overload, or an adenine nucleotide translocator 1 (ANT1) activator, triggers assembly of the pyroptosome comprised of Apaf-1 and caspase-4 with a stoichiometry ratio of 7:2. Unlike the direct cleavage of gasdermin D (GSDMD) by caspase-4 upon LPS ligation, caspase-4 activated in the Apaf-1 pyroptosome proceeds to cleave caspase-3 and thereby GSDME to induce pyroptosis. Caspase-4-initiated and GSDME-executed pyroptosis underlies cholestatic liver failure. These findings identify Apaf-1 pyroptosome as a pivotal machinery for cells sensing MPT signals and may shed light on understanding how cells execute intrinsic pyroptosis under sterile conditions.

Exosomes derived from RPE cells under oxidative stress mediate inflammation and apoptosis of normal RPE cells through Apaf1/caspase-9 axis

This study aims to explore the effects of exosomes, secreted by retinal pigment epithelial (RPE) cells under oxidative stress (OS), on apoptosis and inflammation of normal RPE cells. Exosomes secreted by normal RPE cells (named as exo) and rotenone (2.5 µmol/L) stimulated RPE cells (named as rot-exo) were isolated and extracted by multi-step differential centrifugation for morphology observation under a transmission electron microscopy. pcDNA3.1a, pcDNA3.1a-Apaf1, and p3xFlag-CMV-caspase-9 plasmids were constructed and transfected into ARPE-19 cells. Exosomes secreted by ARPE-19 cells were injected into the vitreous body of rats to verify the effect of Apaf1 and caspase-9 on cell apoptosis and inflammation. Co-immunoprecipitation was applied to clarify the interaction of Apaf1 with caspase-9. Exosomes secreted by rotenone stimulated ARPE-19 cells could induce cell apoptosis, oxidative injury, and inflammation in ARPE-19 cells. Exosomes secreted under OS can damage retinal functions of rats and have upregulated expression of Apaf1. Overexpression of Apaf1 in exosomes secreted under OS can cause the inhibition of cell proliferation, the increase of cell apoptosis and elicitation of inflammatory response in ARPE-19 cells. Exosomes derived from ARPE-19 cells under OS regulate Apaf1 expression to increase cell apoptosis and to induce oxidative injury and inflammatory response through a caspase-9 apoptotic pathway.

Grass carp (Ctenopharyngodon idella) Bcl-xl: transcriptional regulation and anti-apoptosis analysis

Bcl-xl, Bax2, and NF-κB are well-known to be involved in anti-apoptosis response. Although Bcl-xl has been reported in fish, the NF-κB-mediated regulatory mechanism and anti-apoptotic function are still unclear. Here, we cloned and characterized the full-length cDNA sequence of grass carp (Ctenopharyngodon idella) Bcl-xl (CiBcl-xl) and its promoter region sequence. The full-length cDNA of CiBcl-xl is 2836 bp with an ORF of 627 bp encoding a polypeptide of 208 amino acids. Phylogenetic tree analysis revealed that CiBcl-xl shared high homology with Dario rerio Bcl-xl (DrBcl-xl). After stimulation with Poly I:C, the expression of CiBcl-xl in CIK cells and various tested tissues of grass carp were significantly upregulated. To further understand the transcriptional control of fish Bcl-xl induced by NF-κB, CiC-rel and Cip65 were expressed in Escherichia coli BL21 and purified by affinity chromatography with the Ni-NTA His-Bind resin. In vitro, gel mobility shift assays demonstrated the high affinity of CiC-rel and Cip65 with CiBcl-xl promoter. Dual-luciferase reporter assays showed that CiC-rel and Cip65 activated CiBcl-xl promoter. Also, knockdown of CiC-rel and Cip65 reduced the expression of Bcl-xl. Therefore, similar to those of mammals, fish C-rel and p65 can upregulate the transcription of Bcl-xl. In addition, we found that overexpression of CiBcl-xl in CIK cells increased the cell activity and inhibited cell apoptosis, while overexpression of Bax2 promoted cell apoptosis. Meanwhile, co-transfection of CiBcl-xl and CiBax2 into cells can ease up apoptotic rate. To further investigate the molecular basis of synergistic effect of Bcl-xl and Bax2, we showed that Bcl-xl and Bax2 interacted with each other. The results suggested that Bcl-xl executed its anti-apoptotic function by binding to and inhibiting the pro-apoptotic activity of Bax2.

Carbon nanotube-delivered iC9 suicide gene therapy for killing breast cancer cells in vitro

AIM

To induce a safe death to MCF-7 human breast cancer cell line through gene therapy based on iC9 suicide gene.

MATERIALS & METHODS

To induce apoptosis to MCF-7 cell line, iC9 gene was transfected using pyridine-functionalized multi-walled carbon nanotubes. Then, to enhance chemotherapy, iC9 suicide gene therapy was performed alongside.

RESULTS

The results show that the MCF-7 cells were efficiently eliminated in a high percentage by this approach. Furthermore, the suicide gene by itself/in combination with the chemotherapeutic drugs managed to pass the cell cycle arrests.

CONCLUSION

We introduced an in vitro treatment approach based on suicide gene therapy and the first step was taken toward the enhancement of chemotherapy, although more investigation is required.

Nutritional Regulators of Bcl-xL in the Brain

B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic Bcl-2 protein found in the mitochondrial membrane. Bcl-xL is reported to support normal brain development and protects neurons against toxic stimulation during pathological process via its roles in regulation of mitochondrial functions. Despite promising evidence showing neuroprotective properties of Bcl-xL, commonly applied molecular approaches such as genetic manipulation may not be readily applicable for human subjects. Therefore, findings at the bench may be slow to be translated into treatments for disease. Currently, there is no FDA approved application that specifically targets Bcl-xL and treats brain-associated pathology in humans. In this review, we will discuss naturally occurring nutrients that may exhibit regulatory effects on Bcl-xL expression or activity, thus potentially providing affordable, readily-applicable, easy, and safe strategies to protect the brain.

Therapeutic effects of the novel subtype-selective histone deacetylase inhibitor chidamide on myeloma-associated bone disease

Histone deacetylases are promising therapeutic targets in hematological malignancies. In the work herein, we investigated the effect of chidamide, a new subtype-selective histone deacetylase inhibitor that was independently produced in China, on multiple myeloma and its associated bone diseases using different models. The cytotoxicity of chidamide toward myeloma is due to its induction of cell apoptosis and cell cycle arrest by increasing the levels of caspase family proteins p21 and p27, among others. Furthermore, chidamide exhibited significant cytotoxicity against myeloma cells co-cultured with bone mesenchymal stromal cells and chidamide-pretreated osteoclasts. Importantly, chidamide suppressed osteoclast differentiation and resorption in vitro by dephosphorylating p-ERK, p-p38, p-AKT and p-JNK and inhibiting the expression of Cathepsin K, NFATc1 and c-fos. Finally, chidamide not only prevented tumor-associated bone loss in a disseminated murine model by partially decreasing the tumor burden but also prevented rapid receptor activator of nuclear factor κ-β ligand (RANKL)-induced bone loss in a non-tumor-bearing mouse model. Based on our results, chidamide exerted dual anti-myeloma and bone-protective effects in vitro and in vivo. These findings strongly support the potential clinical use of this drug as a treatment for multiple myeloma in the near future.

Vaccinia Virus Encodes a Novel Inhibitor of Apoptosis That Associates with the Apoptosome

Apoptosis is an important antiviral host defense mechanism. Here we report the identification of a novel apoptosis inhibitor encoded by the vaccinia virus (VACV) M1L gene. M1L is absent in the attenuated modified vaccinia virus Ankara (MVA) strain of VACV, a strain that stimulates apoptosis in several types of immune cells. M1 expression increased the viability of MVA-infected THP-1 and Jurkat cells and reduced several biochemical hallmarks of apoptosis, such as PARP-1 and procaspase-3 cleavage. Furthermore, ectopic M1L expression decreased staurosporine-induced (intrinsic) apoptosis in HeLa cells. We then identified the molecular basis for M1 inhibitory function. M1 allowed mitochondrial depolarization but blocked procaspase-9 processing, suggesting that M1 targeted the apoptosome. In support of this model, we found that M1 promoted survival in Saccharomyces cerevisiae overexpressing human Apaf-1 and procaspase-9, critical components of the apoptosome, or overexpressing only conformationally active caspase-9. In mammalian cells, M1 coimmunoprecipitated with Apaf-1-procaspase-9 complexes. The current model is that M1 associates with and allows the formation of the apoptosome but prevents apoptotic functions of the apoptosome. The M1 protein features 14 predicted ankyrin (ANK) repeat domains, and M1 is the first ANK-containing protein reported to use this inhibitory strategy. Since ANK-containing proteins are encoded by many large DNA viruses and found in all domains of life, studies of M1 may lead to a better understanding of the roles of ANK proteins in virus-host interactions.IMPORTANCE Apoptosis selectively eliminates dangerous cells such as virus-infected cells. Poxviruses express apoptosis antagonists to neutralize this antiviral host defense. The vaccinia virus (VACV) M1 ankyrin (ANK) protein, a protein with no previously ascribed function, inhibits apoptosis. M1 interacts with the apoptosome and prevents procaspase-9 processing as well as downstream procaspase-3 cleavage in several cell types and under multiple conditions. M1 is the first poxviral protein reported to associate with and prevent the function of the apoptosome, giving a more detailed picture of the threats VACV encounters during infection. Dysregulation of apoptosis is associated with several human diseases. One potential treatment of apoptosis-related diseases is through the use of designed ANK repeat proteins (DARPins), similar to M1, as caspase inhibitors. Thus, the study of the novel antiapoptosis effects of M1 via apoptosome association will be helpful for understanding how to control apoptosis using either natural or synthetic molecules.

Anticancer activity of Nelumbo nucifera stamen extract in human colon cancer HCT-116 cells in vitro

The aim of the present study was to investigate the anticancer activities of Nelumbo nucifera (Ba lotus) stamen ethanol crude extract (BLSEE) in human colon carcinoma HCT-116 cells. MTT assay, flow cytometry analysis and reverse transcription-polymerase chain reaction assay were employed to investigate the anticancer mechanisms of BLSEE (100, 200 and 400 µg/ml) in HCT-116 cells. BLSEE reduced HCT-116 cell proliferation in a dose-dependent manner. BLSEE treatment also significantly increased the sub-G1 population in HCT-116 cells (P=0.0020 at 400 µg/ml), as shown by flow cytometry assay. Following treatment with BLSEE, the mRNA levels of the apoptosis-associated factors Fas, Fas ligand, tumor necrosis factor-related apoptosis-inducing ligand, death receptor 4 (DR4), death receptor 5 (DR5), caspases 3, 8 and 9, and B-cell lymphoma-2 (Bcl-2) associated X protein were increased, and the expression of anti-apoptotic Bcl-2 and Bcl-extra large was decreased in HCT-116 cells. The mRNA levels of matrix metalloproteinase (MMP)-2, MMP-9, TIMP metallopeptidase inhibitor 1 and TIMP metallopeptidase inhibitor 2 were also regulated by BLSEE treatment. In addition, BLSEE was able to modulate the expression of inflammation-associated nuclear factor-κB, inhibitory κBα, inducible nitric oxide synthase and cyclooxygenase 2 in HCT-116 cells. The present study clearly indicated the cytotoxicity of BLSEE in HCT-116 cells through induced cellular apoptosis. These results also suggested the BLSEE may be a powerful agent against colon cancer cells.

Endoplasmic reticulum-mediated unfolded protein response and mitochondrial apoptosis in cancer

Abrogation of endoplasmic reticulum (ER) protein folding triggered by exogenous or endogenous factors, stimulates a cellular stress response, termed ER stress. ER stress re-establishes ER homeostasis through integrated signaling termed the ER-unfolded protein response (UPR^ER). In the presence of severe toxic or prolonged ER stress, the pro-survival function of UPR^ER is transformed into a lethal signal transmitted to and executed through mitochondria. Mitochondria are key for both apoptotic and autophagic cell death. Thus ER is vital in sensing and coordinating stress pathways to maintain overall physiological homeostasis. However, this function is deregulated in cancer, resulting in resistance to apoptosis induction in response to various stressors including therapeutic agents. Here we review the connections between ER stress and mitochondrial apoptosis, describing potential cancer therapeutic targets.

In Vitro Pre-Clinical Validation of Suicide Gene Modified Anti-CD33 Redirected Chimeric Antigen Receptor T-Cells for Acute Myeloid Leukemia

Background

Approximately fifty percent of patients with acute myeloid leukemia can be cured with current therapeutic strategies which include, standard dose chemotherapy for patients at standard risk of relapse as assessed by cytogenetic and molecular analysis, or high-dose chemotherapy with allogeneic hematopoietic stem cell transplant for high-risk patients. Despite allogeneic hematopoietic stem cell transplant about 25% of patients still succumb to disease relapse, therefore, novel strategies are needed to improve the outcome of patients with acute myeloid leukemia.

Methods and findings

We developed an immunotherapeutic strategy targeting the CD33 myeloid antigen, expressed in ~ 85–90% of patients with acute myeloid leukemia, using chimeric antigen receptor redirected T-cells. Considering that administration of CAR T-cells has been associated with cytokine release syndrome and other potential off-tumor effects in patients, safety measures were here investigated and reported. We genetically modified human activated T-cells from healthy donors or patients with acute myeloid leukemia with retroviral supernatant encoding the inducible Caspase9 suicide gene, a ΔCD19 selectable marker, and a humanized third generation chimeric antigen receptor recognizing human CD33. ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells had a 75±3.8% (average ± standard error of the mean) chimeric antigen receptor expression, were able to specifically lyse CD33⁺ targets in vitro, including freshly isolated leukemic blasts from patients, produce significant amount of tumor-necrosis-factor-alpha and interferon-gamma, express the CD107a degranulation marker, and proliferate upon antigen specific stimulation. Challenging ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells with programmed-death-ligand-1 enriched leukemia blasts resulted in significant killing like observed for the programmed-death-ligand-1 negative leukemic blasts fraction. Since the administration of 10 nanomolar of a non-therapeutic dimerizer to activate the suicide gene resulted in the elimination of only 76.4±2.0% gene modified cells in vitro, we found that co-administration of the dimerizer with either the BCL-2 inhibitor ABT-199, the pan-BCL inhibitor ABT-737, or mafosfamide, resulted in an additive effect up to complete cell elimination.

Conclusions

This strategy could be investigated for the safety of CAR T-cell applications, and targeting CD33 could be used as a ‘bridge” therapy for patients coming to allogeneic hematopoietic stem cell transplant, as anti-leukemia activity from infusing CAR.CD33 T-cells has been demonstrated in an ongoing clinical trial. Albeit never performed in the clinical setting, our future plan is to investigate the utility of iC9-CAR.CD33 T-cells as part of the conditioning therapy for an allogeneic hematopoietic stem cell transplant for acute myeloid leukemia, together with other myelosuppressive agents, whilst the activation of the inducible Caspase9 suicide gene would grant elimination of the infused gene modified T-cells prior to stem cell infusion to reduce the risk of engraftment failure as the CD33 is also expressed on a proportion of the donor stem cell graft.

The NF-κB pathway participates in the response to sulfide stress in Urechis unicinctus

The NF-κB pathway is known to be involved in regulating apoptosis, inflammation and immunity in organisms. In this study, we first identified full-length cDNA sequences of two key molecules in the NF-κB pathway, namely, NEMO and p65, and characterized their responses in the hindgut of Urechis unicinctus (Echiura, Urechidae) exposed to sulfide. The full-length of cDNA was 2491 bp for U. unicinctus NEMO (UuNEMO) and 1971 bp for U. unicinctus p65 (Uup65), and both polyclonal antibodies were prepared using UuNEMO or Uup65 expressed prokaryotically with the sequence of their whole open reading frame. Immunoprecipitation and Western blotting showed that the NF-κB pathway was activated in U. unicinctus exposed to sulfide, in which the content of UuNEMO ubiquitination and nuclear Uup65 increased significantly (p < 0.05) in hindgut tissue of U. unicinctus exposed to sulfide. Furthermore, the mRNA level of UuBcl-xL, a downstream anti-apoptosis gene of the NF-κB pathway, increased significantly (p < 0.05) from 48 h to 72 h and the mRNA level of UuBax, a Bcl-xL antagonist gene, decreased significantly (p < 0.05) at 48 h in the hindgut of U. unicinctus exposed to 50 μM sulfide. During the 150 μM sulfide exposure, the level of UuBcl-xL showed no obvious change, whereas the UuBax mRNA level increased significantly (p < 0.05) at 72 h post-exposure to 150 μM sulfide. We suggested that the activated NF-κB pathway up-regulates UuBcl-xL expression, and evokes an anti-apoptotic response to resist sulfide damage at 50 μM in U. unicinctus. Meanwhile, a Bax-mediated pro-apoptotic response occurs when U. unicinctus is exposed to 150 μM sulfide.

Cancer suicide gene therapy: a patent review

INTRODUCTION

Cancer is considered the second leading cause of death worldwide despite the progress made in early detection and advances in classical therapies. Advancing in the fight against cancer requires the development of novel strategies, and the suicide gene transfer to tumor cells is providing new possibilities for cancer therapy.

AREAS COVERED

In this manuscript, authors present an overview of suicide gene systems and the latest innovations done to enhance cancer suicide gene therapy strategies by i) improving vectors for targeted gene delivery using tissue specific promoter and receptors; ii) modification of the tropism; and iii) combining suicide genes and/or classical therapies for cancer. Finally, the authors highlight the main challenges to be addressed in the future.

EXPERT OPINION

Even if many efforts are needed for suicide gene therapy to be a real alternative for cancer treatment, we believe that the significant progress made in the knowledge of cancer biology and characterization of cancer stem cells accompanied by the development of novel targeted vectors will enhance the effectiveness of this type of therapeutic strategy. Moreover, combined with current treatments, suicide gene therapy will improve the clinical outcome of patients with cancer in the future.

Functional Implications of the spectrum of BCL2 mutations in Lymphoma

Mutations in the translocated BCL2 gene are often detected in diffuse large B-cell lymphomas (DLBCLs), indicating both their significance and pervasiveness. Large series genome sequencing of more than 200 DLBCLs has identified frequent BCL2 mutations clustered in the exons coding for the BH4 domain and the folded loop domain (FLD) of the protein. However, BCL2 mutations are mostly contemplated to represent bystander events with negligible functional impact on the pathogenesis of DLBCL. BCL2 arbitrates apoptosis through a classic interaction between its hydrophobic groove forming BH1-3 domains and the BH3 domain of pro-apoptotic members of the BCL2 family. The effects of mutations are mainly determined by the ability of the mutated BCL2 to mediate apoptosis by this inter-member protein binding. Nevertheless, BCL2 regulates diverse non-canonical pathways that are unlikely to be explained by canonical interactions. In this review, first, we identify recurrent missense mutations in the BH4 domain and the FLD reported in independent lymphoma sequencing studies. Second, we discuss the probable consequences of mutations on the binding ability of BCL2 to non-BCL2 family member proteins crucial for 1) maintaining mitochondrial energetics and calcium hemostasis such as VDAC, IP3R, and RyR and 2) oncogenic pathways implicated in the acquisition of the 'hallmarks of cancer' such as SOD, Raf-1, NFAT, p53, HIF-1α, and gelsolin. The study also highlights the likely ramifications of mutations on binding of BCL2 antagonists and BH3 profiling. Based on our analysis, we believe that an in-depth focus on BCL2 interactions mediated by these domains is warranted to elucidate the functional significance of missense mutations in DLBCL. In summary, we provide an extensive overview of the pleiotropic functions of BCL2 mediated by its physical binding interaction with other proteins and the various ways BCL2 mutations would affect the normal function of the cell leading to the development of DLBCL.

Influence of doxorubicin on apoptosis and oxidative stress in breast cancer cell lines

Breast cancer is one of the leading causes of mortality among women worldwide due to aggressive behavior, early metastasis, resistance to existing chemotherapeutic agent and high mortality rate. Doxorubicin (Dox) is a powerful antitumoral drug. It is one of the most active agents for treatment of breast cancer. The aim of the present study was to evaluate the influence of Dox in apoptosis and oxidative stress in the breast cancer cell lines MCF-10F, MCF-7 and MDA-MB-231. These studies showed that Dox decreased anti-apoptotic Bcl-2 protein expression and affected oxidative stress by increasing hydrogen peroxide production and simultaneously decreasing NF-κB gene and protein expression in MCF-7, a tumorigenic triple-positive cell line. Results also indicated that Dox induced apoptosis by upregulating Bax, caspase-8 and caspase-3 and downregulation of Bcl-2 protein expression. On the contrary, ROS damage decreased by increasing SOD2 gene and protein expression and hydrogen peroxide production with parallel NF-κB protein expression decrease in MDA-MB-231, a tumorigenic triple-negative breast cancer cell line. It can be concluded that Dox activated apoptosis by inducing proteolytic processing of Bcl-2 family, caspases and simultaneously decreased oxidative stress by influencing ROS damage in MCF-7 and MDA-MB-231 cell lines.

Flavokawain C Inhibits Cell Cycle and Promotes Apoptosis, Associated with Endoplasmic Reticulum Stress and Regulation of MAPKs and Akt Signaling Pathways in HCT 116 Human Colon Carcinoma Cells

Flavokawain C (FKC) is a naturally occurring chalcone which can be found in Kava (Piper methysticum Forst) root. The present study evaluated the effect of FKC on the growth of various human cancer cell lines and the underlying associated mechanisms. FKC showed higher cytotoxic activity against HCT 116 cells in a time- and dose-dependent manner in comparison to other cell lines (MCF-7, HT-29, A549 and CaSki), with minimal toxicity on normal human colon cells. The apoptosis-inducing capability of FKC on HCT 116 cells was evidenced by cell shrinkage, chromatin condensation, DNA fragmentation and increased phosphatidylserine externalization. FKC was found to disrupt mitochondrial membrane potential, resulting in the release of Smac/DIABLO, AIF and cytochrome c into the cytoplasm. Our results also revealed that FKC induced intrinsic and extrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bak) and death receptors (DR5), while downregulation of the levels of anti-apoptotic proteins (XIAP, cIAP-1, c-Flip_L, Bcl-xL and survivin), resulting in the activation of caspase-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase (PARP). FKC was also found to cause endoplasmic reticulum (ER) stress, as suggested by the elevation of GADD153 protein after FKC treatment. After the cells were exposed to FKC (60μM) over 18hrs, there was a substantial increase in the phosphorylation of ERK 1/2. The expression of phosphorylated Akt was also reduced. FKC also caused cell cycle arrest in the S phase in HCT 116 cells in a time- and dose-dependent manner and with accumulation of cells in the sub-G1 phase. This was accompanied by the downregulation of cyclin-dependent kinases (CDK2 and CDK4), consistent with the upregulation of CDK inhibitors (p21^Cip1 and p27^Kip1), and hypophosphorylation of Rb.

Cinnamomum cassia Suppresses Caspase-9 through Stimulation of AKT1 in MCF-7 Cells but Not in MDA-MB-231 Cells

Background

Cinnamomum cassia bark is a popular culinary spice used for flavoring and in traditional medicine. C. cassia extract (CE) induces apoptosis in many cell lines. In the present study, particular differences in the mechanism of the anti-proliferative property of C. cassia on two breast cancer cell lines, MCF-7 and MDA-MB-231, were elucidated.

Methodology/Principal Findings

The hexane extract of C. cassia demonstrated high anti-proliferative activity against MCF-7 and MDA-MB-231 cells (IC₅₀, 34±3.52 and 32.42 ±0.37 μg/ml, respectively). Oxidative stress due to disruption of antioxidant enzyme (SOD, GPx and CAT) activity is suggested as the probable cause for apoptosis initiation. Though the main apoptosis pathway in both cell lines was found to be through caspase-8 activation, caspase-9 was also activated in MDA-MB-231 cells but suppressed in MCF-7 cells. Gene expression studies revealed that AKT1, the caspase-9 suppressor, was up-regulated in MCF-7 cells while down-regulated in MDA-MB-231 cells. Although, AKT1 protein expression in both cell lines was down-regulated, a steady increase in MCF-7 cells was observed after a sharp decrease of suppression of AKT1. Trans-cinnamaldehyde and coumarin were isolated and identified and found to be mainly responsible for the observed anti-proliferative activity of CE (Cinnamomum cassia).

Conclusion

Activation of caspase-8 is reported for the first time to be involved as the main apoptosis pathway in breast cancer cell lines upon treatment with C. cassia. The double effects of C. cassia on AKT1 gene expression in MCF-7 cells is reported for the first time in this study.

Doxorubicin Changes Bax /Bcl-xL Ratio, Caspase-8 and 9 in Breast Cancer Cells

PURPOSE

Doxorubicin is administrated as a single agent in first-line therapy of breast cancer to induce apoptosis in tumor cells. Bax, Bcl-xL, Caspase-8 and 9 proteins are involved in induction of apoptosis. The present study describes Bax, Bcl-xL gene expression and Caspase-8 and 9 protein levels in MCF-7 cells incubated with doxorubicin at different doses an incubation times.

METHODS

The cytotoxic effects of doxorubicin were studied using MTT assay. MCF-7 cells were treated with three concentrations of doxorubicin (0.1, 0.5, 1 μM) and incubated for 24, 48 and 72 hours then expression levels of Bax and Bcl-xL genes were elucidated by Real-time RT-PCR technique and protein levels of caspase-8 and caspase-9 proteins were measured using ELISA method. Morphological modifications of the cells were also monitored via light microscopic images.

RESULTS

Doxorubicin decreased the anti-apoptotic Bcl-xL and increased pro-apoptotic Bax mRNA levels. Doxorubicin induced a significant increase in Bax /Bcl-xL ratio in all doses and incubation times (p<0.05). Highest (more than 10 fold) increase in Bax /Bcl-xL ratio was revealed after 48 h incubation of the cells with in all doses of doxorubicin. Doxorubicin also increased caspase-9 level in a time and dose-dependent manner, while caspase-8 level didn't follow time and dose dependency pattern.

CONCLUSION

Our results confirm that doxorubicin induces mitochondrial-dependent apoptosis by down-regulation of Bcl-xL and up- regulation of Bax and caspase-9 expressions.

Bit-1 is an essential regulator of myogenic differentiation

Muscle differentiation requires a complex signaling cascade that leads to the production of multinucleated myofibers. Genes regulating the intrinsic mitochondrial apoptotic pathway also function in controlling cell differentiation. How such signaling pathways are regulated during differentiation is not fully understood. Bit-1 (also known as PTRH2) mutations in humans cause infantile-onset multisystem disease with muscle weakness. We demonstrate here that Bit-1 controls skeletal myogenesis through a caspase-mediated signaling pathway. Bit-1-null mice exhibit a myopathy with hypotrophic myofibers. Bit-1-null myoblasts prematurely express muscle-specific proteins. Similarly, knockdown of Bit-1 expression in C2C12 myoblasts promotes early differentiation, whereas overexpression delays differentiation. In wild-type mice, Bit-1 levels increase during differentiation. Bit-1-null myoblasts exhibited increased levels of caspase 9 and caspase 3 without increased apoptosis. Bit-1 re-expression partially rescued differentiation. In Bit-1-null muscle, Bcl-2 levels are reduced, suggesting that Bcl-2-mediated inhibition of caspase 9 and caspase 3 is decreased. Bcl-2 re-expression rescued Bit-1-mediated early differentiation in Bit-1-null myoblasts and C2C12 cells with knockdown of Bit-1 expression. These results support an unanticipated yet essential role for Bit-1 in controlling myogenesis through regulation of Bcl-2.

Persea declinata (Bl.) Kosterm Bark Crude Extract Induces Apoptosis in MCF-7 Cells via G0/G1 Cell Cycle Arrest, Bcl-2/Bax/Bcl-xl Signaling Pathways, and ROS Generation

Persea declinata (Bl.) Kosterm is a member of the Lauraceae family, widely distributed in Southeast Asia. It is from the same genus with avocado (Persea americana Mill), which is widely consumed as food and for medicinal purposes. In the present study, we examined the anticancer properties of Persea declinata (Bl.) Kosterm bark methanolic crude extract (PDM). PDM exhibited a potent antiproliferative effect in MCF-7 human breast cancer cells, with an IC₅₀ value of 16.68 µg/mL after 48 h of treatment. We observed that PDM caused cell cycle arrest and subsequent apoptosis in MCF-7 cells, as exhibited by increased population at G₀/G₁ phase, higher lactate dehydrogenase (LDH) release, and DNA fragmentation. Mechanistic studies showed that PDM caused significant elevation in ROS production, leading to perturbation of mitochondrial membrane potential, cell permeability, and activation of caspases-3/7. On the other hand, real-time PCR and Western blot analysis showed that PDM treatment increased the expression of the proapoptotic molecule, Bax, but decreased the expression of prosurvival proteins, Bcl-2 and Bcl-xL, in a dose-dependent manner. These findings imply that PDM could inhibit proliferation in MCF-7 cells via cell cycle arrest and apoptosis induction, indicating its potential as a therapeutic agent worthy of further development.

Interaction of translationally controlled tumor protein with Apaf-1 is involved in the development of chemoresistance in HeLa cells

Background

Translationally controlled tumor protein (TCTP), alternatively called fortilin, is believed to be involved in the development of the chemoresistance of tumor cells against anticancer drugs such as etoposide, taxol, and oxaliplatin, the underlying mechanisms of which still remain elusive.

Methods

Cell death analysis of TCTP-overexpressing HeLa cells was performed following etoposide treatment to assess the mitochondria-dependent apoptosis. Apoptotic pathway was analyzed through measuring the cleavage of epidermal growth factor receptor (EGFR) and phospholipase C-γ (PLC-γ), caspase activation, mitochondrial membrane perturbation, and cytochrome c release by flow cytometry and western blotting. To clarify the role of TCTP in the inhibition of apoptosome, in vitro apoptosome reconstitution and immunoprecipitation was used. Pull-down assay and silver staining using the variants of Apaf-1 protein was applied to identify the domain that is responsible for its interaction with TCTP.

Results

In the present study, we confirmed that adenoviral overexpression of TCTP protects HeLa cells from cell death induced by cytotoxic drugs such as taxol and etoposide. TCTP antagonized the mitochondria-dependent apoptotic pathway following etoposide treatment, including mitochondrial membrane damage and resultant cytochrome c release, activation of caspase-9, and -3, and eventually, the cleavage of EGFR and PLC-γ. More importantly, TCTP interacts with the caspase recruitment domain (CARD) of Apaf-1 and is incorporated into the heptameric Apaf-1 complex, and that C-terminal cleaved TCTP specifically associates with Apaf-1 of apoptosome in apoptosome-forming condition thereby inhibiting the amplification of caspase cascade.

Conclusions

TCTP protects the cancer cells from etoposide-induced cell death by inhibiting the mitochondria-mediated apoptotic pathway. Interaction of TCTP with Apaf-1 in apoptosome is involved in the molecular mechanism of TCTP-induced chemoresistance. These findings suggest that TCTP may serve as a therapeutic target for chemoresistance in cancer treatment.

Subditine, a new monoterpenoid indole alkaloid from bark of Nauclea subdita (Korth.) Steud. induces apoptosis in human prostate cancer cells

In this study, a new apoptotic monoterpenoid indole alkaloid, subditine (1), and four known compounds were isolated from the bark of Nauclea subdita. Complete (1)H- and (13)C- NMR data of the new compound were reported. The structures of isolated compounds were elucidated with various spectroscopic methods such as 1D- and 2D- NMR, IR, UV and LCMS. All five compounds were screened for cytotoxic activities on LNCaP and PC-3 human prostate cancer cell-lines. Among the five compounds, the new alkaloid, subditine (1), demonstrated the most potent cell growth inhibition activity and selective against LNCaP with an IC50 of 12.24±0.19 µM and PC-3 with an IC50 of 13.97±0.32 µM, compared to RWPE human normal epithelial cell line (IC50 = 30.48±0.08 µM). Subditine (1) treatment induced apoptosis in LNCaP and PC-3 as evidenced by increased cell permeability, disruption of cytoskeletal structures and increased nuclear fragmentation. In addition, subditine (1) enhanced intracellular reactive oxygen species (ROS) production, as reflected by increased expression of glutathione reductase (GR) to scavenge damaging free radicals in both prostate cancer cell-lines. Excessive ROS could lead to disruption of mitochondrial membrane potential (MMP), release of cytochrome c and subsequent caspase 9, 3/7 activation. Further Western blot analyses showed subditine (1) induced down-regulation of Bcl-2 and Bcl-xl expression, whereas p53 was up-regulated in LNCaP (p53-wild-type), but not in PC-3 (p53-null). Overall, our data demonstrated that the new compound subditine (1) exerts anti-proliferative effect on LNCaP and PC-3 human prostate cancer cells through induction of apoptosis.

Histone deacetylase inhibitor upregulates peroxisomal fatty acid oxidation and inhibits apoptotic cell death in abcd1-deficient glial cells

In X-ALD, mutation/deletion of ALD gene (ABCD1) and the resultant very long chain fatty acid (VLCFA) derangement has dramatically opposing effects in astrocytes and oligodendrocytes. While loss of Abcd1 in astrocytes produces a robust inflammatory response, the oligodendrocytes undergo cell death leading to demyelination in X-linked adrenoleukodystrophy (X-ALD). The mechanisms of these distinct pathways in the two cell types are not well understood. Here, we investigated the effects of Abcd1-knockdown and the subsequent alteration in VLCFA metabolism in human U87 astrocytes and rat B12 oligodendrocytes. Loss of Abcd1 inhibited peroxisomal β-oxidation activity and increased expression of VLCFA synthesizing enzymes, elongase of very long chain fatty acids (ELOVLs) (1 and 3) in both cell types. However, higher induction of ELOVL's in Abcd1-deficient B12 oligodendrocytes than astrocytes suggests that ELOVL pathway may play a prominent role in oligodendrocytes in X-ALD. While astrocytes are able to maintain the cellular homeostasis of anti-apoptotic proteins, Abcd1-deletion in B12 oligodendrocytes downregulated the anti-apototic (Bcl-2 and Bcl-xL) and cell survival (phospho-Erk1/2) proteins, and upregulated the pro-apoptotic proteins (Bad, Bim, Bax and Bid) leading to cell loss. These observations provide insights into different cellular signaling mechanisms in response to Abcd1-deletion in two different cell types of CNS. The apoptotic responses were accompanied by activation of caspase-3 and caspase-9 suggesting the involvement of mitochondrial-caspase-9-dependent mechanism in Abcd1-deficient oligodendrocytes. Treatment with histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) corrected the VLCFA derangement both in vitro and in vivo, and inhibited the oligodendrocytes loss. These observations provide a proof-of principle that HDAC inhibitor SAHA may have a therapeutic potential for X-ALD.

The influence of the pleiotropic action of erythropoietin and its derivatives on nephroprotection

Erythropoietin (EPO) is traditionally described as a hematopoietic cytokine or growth hormone regulating proliferation, differentiation, and survival of erythroid progenitors. The use of EPO in patients with chronic kidney disease (CKD) was a milestone achievement in the treatment of anemia. However, EPO involves some degree of risk, which increases with increasing hemoglobin levels. A growing number of studies have assessed the renoprotective effects of EPO in acute kidney injury (AKI) or CKD. Analysis of the biological effects of erythropoietin and pathophysiology of CKD in these studies suggests that treatment with erythropoiesis-stimulating agents (ESAs) may exert renoprotection by pleiotropic actions on several targets and directly or indirectly slow the progression of CKD. By reducing ischemia and oxidative stress or strengthening anti-apoptotic processes, EPO may prevent the development of interstitial fibrosis and the destruction of tubular cells. Furthermore, it could have a direct protective impact on the integrity of the interstitial capillary network through its effects on endothelial cells and promotion of vascular repair, or modulate inflammation response. Thus, it is biologically plausible to suggest that correcting anemia with ESAs could slow the progression of CKD.                         The aim of this article is to discuss these possible renoprotection mechanisms and provide a comprehensive overview of erythropoietin and its derivatives.

Calix[6]arene bypasses human pancreatic cancer aggressiveness: downregulation of receptor tyrosine kinases and induction of cell death by reticulum stress and autophagy

Pancreatic cancer ranks fourth among cancer-related causes of death in North America. Minimal progress has been made in the diagnosis and treatment of patients with late-stage tumors. Moreover, pancreatic cancer aggressiveness is closely related to high levels of pro-survival mediators, which can ultimately lead to rapid disease progression, resistance and metastasis. The main goal of this study was to define the mechanisms by which calix[6]arene, but not other calixarenes, efficiently decreases the aggressiveness of a drug resistant human pancreas carcinoma cell line (Panc-1). Calix[6]arene was more potent in reducing Panc-1 cell viability than gemcitabine and 5-fluorouracil. In relation to the underlying mechanisms of cytotoxic effects, it led to cell cycle arrest in the G0/G1 phase through downregulation of PIM1, CDK2, CDK4 and retinoblastoma proteins. Importantly, calix[6]arene abolished signal transduction of Mer and AXL tyrosine kinase receptors, both of which are usually overexpressed in pancreatic cancer. Accordingly, inhibition of PI3K and mTOR was also observed, and these proteins are positively modulated by Mer and AXL. Despite decreasing the phosphorylation of AKT at Thr308, calix[6]arene caused an increase in phosphorylation at Ser473. These findings in conjunction with increased BiP and IRE1-α provide a molecular basis explaining the capacity of calix[6]arene to trigger endoplasmic reticulum stress and autophagic cell death. Our findings highlight calix[6]arene as a potential candidate for overcoming pancreatic cancer aggressiveness. Importantly, we provide evidence that calix[6]arene affects a broad array of key targets that are usually dysfunctional in pancreatic cancer, a highly desirable characteristic for chemotherapeutics.

Induction of apoptosis in human breast cancer cells via caspase pathway by vernodalin isolated from Centratherum anthelminticum (L.) seeds

BACKGROUND

Centratherum anthelminticum (L.) seeds (CA) is a well known medicinal herb in Indian sub-continent. We recently reported anti-oxidant property of chloroform fraction of Centratherum anthelminticum (L.) seeds (CACF) by inhibiting tumor necrosis factor-α (TNF-α)-induced growth of human breast cancer cells. However, the active compounds in CACF have not been investigated previously.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we showed that CACF inhibited growth of MCF-7 human breast cancer cells. CACF induced apoptosis in MCF-7 cells as marked by cell size shrinkage, deformed cytoskeletal structure and DNA fragmentation. To identify the cytotoxic compound, CACF was subjected to bioassay-guided fractionation which yielded 6 fractions. CACF fraction A and B (CACF-A, -B) demonstrated highest activity among all the fractions. Further HPLC isolation, NMR and LC-MS analysis of CACF-A led to identification of vernodalin as the cytotoxic agent in CACF-A, and -B. 12,13-dihydroxyoleic acid, another major compound in CACF-C fraction was isolated for the first time from Centratherum anthelminticum (L.) seeds but showed no cytotoxic effect against MCF-7 cells. Vernodalin inhibited cell growth of human breast cancer cells MCF-7 and MDA-MB-231 by induction of cell cycle arrest and apoptosis. Increased of reactive oxygen species (ROS) production, coupled with downregulation of anti-apoptotic molecules (Bcl-2, Bcl-xL) led to reduction of mitochondrial membrane potential (MMP) and release of cytochrome c in both human breast cancer cells treated with vernodalin. Release of cytochrome c from mitochondria to cytosol triggered activation of caspase cascade, PARP cleavage, DNA damage and eventually cell death.

CONCLUSIONS/SIGNIFICANCE

To the best of our knowledge, this is the first comprehensive study on cytotoxic and apoptotic mechanism of vernodalin isolated from the Centratherum anthelminticum (L.) seeds in human breast cancer cells. Overall, our data suggest a potential therapeutic value of vernodalin to be further developed as new anti-cancer drug.

Spinal muscular atrophy and the antiapoptotic role of survival of motor neuron (SMN) protein

Spinal muscular atrophy (SMA) is a devastating and often fatal neurodegenerative disease that affects spinal motor neurons and leads to progressive muscle wasting and paralysis. The survival of motor neuron (SMN) gene is mutated or deleted in most forms of SMA, which results in a critical reduction in SMN protein. Motor neurons appear particularly vulnerable to reduced SMN protein levels. Therefore, understanding the functional role of SMN in protecting motor neurons from degeneration is an essential prerequisite for the design of effective therapies for SMA. To this end, there is increasing evidence indicating a key regulatory antiapoptotic role for the SMN protein that is important in motor neuron survival. The aim of this review is to highlight key findings that support an antiapoptotic role for SMN in modulating cell survival and raise possibilities for new therapeutic approaches.

Absence of Nogo-B (reticulon 4B) facilitates hepatic stellate cell apoptosis and diminishes hepatic fibrosis in mice

Nogo-B (reticulon 4B) accentuates hepatic fibrosis and cirrhosis, but the mechanism remains unclear. The aim of this study was to identify the role of Nogo-B in hepatic stellate cell (HSC) apoptosis in cirrhotic livers. Cirrhosis was generated by carbon tetrachloride inhalation in wild-type (WT) and Nogo-A/B knockout (Nogo-B KO) mice. HSCs were isolated from WT and Nogo-B KO mice and cultured for activation and transformation to myofibroblasts (MF-HSCs). Human hepatic stellate cells (LX2 cells) were used to assess apoptotic responses of activated HSCs after silencing or overexpressing Nogo-B. Livers from cirrhotic Nogo-B KO mice showed significantly reduced fibrosis (P < 0.05) compared with WT mice. Apoptotic cells were more prominent in fibrotic areas of cirrhotic Nogo-B KO livers. Nogo-B KO MF-HSCs showed significantly increased levels of apoptotic markers, cleaved poly (ADP-ribose) polymerase, and caspase-3 and -8 (P < 0.05) compared with WT MF-HSCs in response to staurosporine. Treatment with tunicamycin, an endoplasmic reticulum stress inducer, increased cleaved caspase-3 and -8 levels in Nogo-B KO MF-HSCs compared with WT MF-HSCs (P < 0.01). In LX2 cells, Nogo-B knockdown enhanced apoptosis in response to staurosporine, whereas Nogo-B overexpression inhibited apoptosis. The absence of Nogo-B enhances apoptosis of HSCs in experimental cirrhosis. Selective blockade of Nogo-B in HSCs may represent a potential therapeutic strategy to mitigate liver fibrosis.

Role of naofen in apoptosis of hepatocytes induced by lipopolysaccharide through mitochondrial signaling in rats

AIM

  Lipopolysaccharide (LPS) causes apoptosis of hepatocytes, which is probably mediated by inflammatory substances released from Kupffer cells (KCs). Recently, we have reported that naofen, a newly found intracellular WD40-repeat protein, has a role in inducing the apoptosis in HEK293 cells. Hence, the present study was undertaken to investigate a role of naofen in the LPS-induced apoptosis of rat hepatocytes.

METHODS

  Rats were treated with i.v. injections of LPS, and livers were extirpated to evaluate expression of naofen and apoptosis. In in vitro experiments, hepatocytes and KCs were separately isolated from rat livers. The incubation medium for KCs treated with LPS (KC-CM) was used for hepatocyte culture.

RESULTS

  Intravenous injections of LPS enhanced the expression of naofen in the livers. Livers showed terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive staining, and elevated caspase-3 activity. In isolated KCs or hepatocytes, LPS hardly affected naofen expression and caspase-3 activity, whereas incubation of hepatocytes with KC-CM enhanced both naofen expression and caspase-3 activation. Transfection of hepatocyte with naofen siRNA prevented such effects of KC-CM, and clearly eliminated KC-CM-induced reduction of Bcl-2 and Bcl-xL. In contrast, overexpression of naofen in hepatocytes downregulated Bcl-2 and Bcl-xL, released cytochrome c from mitochondria, and activated caspase-3.

CONCLUSION

  These results indicate that LPS may induce the hepatic apoptosis in association with enhanced naofen expression, and that naofen may mediate the activation of caspase-3 through downregulating the Bcl-2 and Bcl-xL expression, and releasing cytochrome c from mitochondria to cytoplasm.

Regulation of anti-apoptotic BCL2-proteins by non-canonical interactions: the next step forward or two steps back?

All aspects of cellular biology affect the process of regulated cell death, or apoptosis, and disruption of this process is a causative event in many diseases. Therefore, a comprehensive understanding of all pathways that regulate apoptosis would increase our knowledge of basic cellular functions, as well as the etiologies of many diseases. In turn, we may be able to use this knowledge to better treat patients with diseases, including cancer. Although the basic signaling pathway that regulates apoptosis has been known for over 10 years, we still have much to learn about the upstream signaling components that can directly regulate the core apoptosis machinery. The focus of this review will be to direct attention to non-canonical regulators of the BCL2-family of proteins, especially our void of understanding of such interactions, and the controversy that surrounds some such interactions.

Health and cellular impacts of air pollutants: from cytoprotection to cytotoxicity

Air pollution as one of the ravages of our modern societies is primarily linked to urban centers, industrial activities, or road traffic. These atmospheric pollutants have been incriminated in deleterious health effects by numerous epidemiological and in vitro studies. Environmental air pollutants are a heterogeneous mixture of particles suspended into a liquid and gaseous phase which trigger the disruption of redox homeostasis—known under the term of cellular oxidative stress—in relation with the establishment of inflammation and cell death via necrosis, apoptosis, or autophagy. Activation or repression of the apoptotic process as an adaptative response to xenobiotics might lead to either acute or chronic toxicity. The purpose of this paper is to highlight the central role of oxidative stress induced by air pollutants and to focus on the subsequent cellular impacts ranging from cytoprotection to cytotoxicity by decreasing or stimulating apoptosis, respectively.

Protective role of heme oxygenase-1 in Listeria monocytogenes-induced abortion

It is well-known fact that various pathogens, including bacteria, virus, and protozoa, induce abortion in humans and animals. However the mechanisms of infectious abortion are little known. In this study, we demonstrated that Listeria monocytogenes infection in trophoblast giant cells decreased heme oxygenase (HO)-1 and B-cell lymphoma-extra large (Bcl-XL) expression, and that their overexpression inhibited cell death induced by the infection. Furthermore, HO-1 and Bcl-XL expression levels were also decreased by L. monocytogenes in pregnant mice. Treatment with cobalt protoporphyrin, which is known to induce HO-1, inhibited infectious abortion. Taken together, our study indicates that L. monocytogenes infection decreases HO-1 and Bcl-XL expression and induces cell death in placenta, leading to infectious abortion.

Hypoxia-ischemia and retinal ganglion cell damage

Retinal hypoxia is the potentially blinding mechanism underlying a number of sight-threatening disorders including central retinal artery occlusion, ischemic central retinal vein thrombosis, complications of diabetic eye disease and some types of glaucoma. Hypoxia is implicated in loss of retinal ganglion cells (RGCs) occurring in such conditions. RGC death occurs by apoptosis or necrosis. Hypoxia-ischemia induces the expression of hypoxia inducible factor-1α and its target genes such as vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS). Increased production of VEGF results in disruption of the blood retinal barrier leading to retinal edema. Enhanced expression of NOS results in increased production of nitric oxide which may be toxic to the cells resulting in their death. Excess glutamate release in hypoxic-ischemic conditions causes excitotoxic damage to the RGCs through activation of ionotropic and metabotropic glutamate receptors. Activation of glutamate receptors is thought to initiate damage in the retina by a cascade of biochemical effects such as neuronal NOS activation and increase in intracellular Ca²⁺ which has been described as a major contributing factor to RGC loss. Excess production of proinflammatory cytokines also mediates cell damage. Besides the above, free-radicals generated in hypoxic-ischemic conditions result in RGC loss because of an imbalance between antioxidant- and oxidant-generating systems. Although many advances have been made in understanding the mediators and mechanisms of injury, strategies to improve the damage are lacking. Measures to prevent neuronal injury have to be developed.