PUMA cooperates with direct activator proteins to promote mitochondrial outer membrane permeabilization and apoptosis

Toxic effects of the insecticide tolfenpyrad on zebrafish embryos: Cardiac toxicity and mitochondrial damage

Tolfenpyrad, a highly effective and broad-spectrum insecticide and acaricide extensively utilized in agriculture, presents a potential hazard to nontarget organisms. This study was designed to explore the toxic mechanisms of tolfenpyrad on zebrafish embryos. Between 24 and 96 h after exposure of the fertilized embryos to tolfenpyrad at concentrations ranging from 0.001 to 0.016 mg/L (96 h-LC50 = 0.017 mg/L), lethal effects were apparent, accompanied with notable anomalies including pericardial edema, increased pericardial area, diminished heart rate, and an elongated distance between the venous sinus and the arterial bulb. Tolfenpyrad elicited noteworthy alterations in the expression of genes pertinent to cardiac development and apoptosis, with the most pronounced changes observed in the cardiac development-related genes of bone morphogenetic protein 2b (bmp2b) and p53 upregulated modulator of apoptosis (puma). The findings underscore that tolfenpyrad induces severe cardiac toxicity and mitochondrial damage in zebrafish embryos. This data is imperative for a comprehensive assessment of tolfenpyrad risks to aquatic ecosystems, particularly considering the limited knowledge regarding its detrimental impact on aquatic vertebrates.

Quercetin attenuates cisplatin-induced mitochondrial apoptosis via PI3K/Akt mediated inhibition of oxidative stress in pericytes and improves the blood labyrinth barrier permeability

Cisplatin (CDDP) is broadly employed to treat different cancers, whereas there are no drugs approved by the Food and Drug Administration (FDA) for preventing its side effects, including ototoxicity. Quercetin (QU) is a widely available natural flavonoid compound with anti-tumor and antioxidant properties. The research was designed to explore the protective effects of QU on CDDP-induced ototoxicity and its underlying mechanisms in male C57BL/6 J mice and primary cultured pericytes (PCs). Hearing changes, morphological changes of stria vascularis, blood labyrinth barrier (BLB) permeability and expression of apoptotic proteins were observed in vivo by using the auditory brainstem response (ABR) test, HE staining, Evans blue staining, immunohistochemistry, western blotting, etc. Oxidative stress levels, mitochondrial function and endothelial barrier changes were observed in vitro by using DCFH-DA probe detection, flow cytometry, JC-1 probe, immunofluorescence and the establishment in vitro BLB models, etc. QU pretreatment activates the PI3K/AKT signaling pathway, inhibits CDDP-induced oxidative stress, protects mitochondrial function, and reduces mitochondrial apoptosis in PCs. However, PI3K/AKT specific inhibitor (LY294002) partially reverses the protective effects of QU. In addition, in vitro BLB models were established by coculturing PCs and endothelial cells (ECs), which suggests that QU both reduces the CDDP-induced apoptosis in PCs and improves the endothelial barrier permeability. On the whole, the research findings suggest that QU can be used as a novel treatment to reduce CDDP-induced ototoxicity.

Evaluation of the Possible Protective Role of Nobiletin against Arsenic-Induced Liver Damage in Male Albino Rats

Arsenic (As) is a toxic contaminant present in organic and inorganic forms in the environment. Nobiletin (NOB) is a polymethoxy flavone that has recently gained substantial consideration due to its curative impacts. The present experiment was conducted to assess the hepatoprotective efficiency of NOB on As-generated hepatotoxicity. Twenty-four adult rats were equally distributed into four groups and designated as control, As (50 mg/kg)-treated, As + NOB (50 mg/kg and 25 mg/kg, respectively), and NOB (25 mg/kg)-treated groups. After 30 days, experimental animals were decapitated, then blood and tissue samples were collected for further analysis. The group treated with As showed a significant decrease in the activity of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), glutathione (GSH), glutathione reductase (GSR), and total antioxidant status (TAS), and a substantial increase in the accumulation of As in liver tissues, levels of total oxidant status (TOS), hydrogen peroxide (H₂O₂), and lipid peroxidation (TBARS). Significant increases in alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) levels were observed in As-treated rats. Moreover, nuclear factor (NF)-κB, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-6, and cyclo-oxygenase (COX)-2 activity, as well as the levels of pro-apoptotic markers (Bax, Caspase-3, and Caspase-9) were increased on exposure to As. In contrast, the anti-apoptotic marker (Bcl-2) level was significantly decreased. As administration showed a significant disturbance in hepatic tissue histology. However, cotreatment of NOB with As considerably increased the antioxidant enzyme activity, with a noteworthy reduction in the deposition of As in hepatic tissues, TBARS, and H₂O₂ levels. NOB-administrated rats showed considerable recovery in terms of inflammation, apoptosis, and histological damage. Hence, NOB can be considered a useful curative compound due to its medicinal properties against As-prompted hepatotoxicity.

Combined BCL-2 and PI3K/AKT Pathway Inhibition in KMT2A-Rearranged Acute B-Lymphoblastic Leukemia Cells

Numerous hematologic neoplasms, including acute B-lymphoblastic leukemia (B-ALL), are characterized by overexpression of anti-apoptotic BCL-2 family proteins. Despite the high clinical efficacy of the specific BCL-2 inhibitor venetoclax in acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL), dose limitation and resistance argue for the early exploration of rational combination strategies. Recent data indicated that BCL-2 inhibition in B-ALL with KMT2A rearrangements is a promising intervention option; however, combinatorial approaches have not been in focus so far. The PI3K/AKT pathway has emerged as a possible target structure due to multiple interactions with the apoptosis cascade as well as relevant dysregulation in B-ALL. Herein, we demonstrate for the first time that combined BCL-2 and PI3K/AKT inhibition has synergistic anti-proliferative effects on B-ALL cell lines. Of note, all tested combinations (venetoclax + PI3K inhibitors idelalisib or BKM-120, as well as AKT inhibitors MK-2206 or perifosine) achieved comparable anti-leukemic effects. In a detailed analysis of apoptotic processes, among the PI3K/AKT inhibitors only perifosine resulted in an increased rate of apoptotic cells. Furthermore, the combination of venetoclax and perifosine synergistically enhanced the activity of the intrinsic apoptosis pathway. Subsequent gene expression studies identified the pro-apoptotic gene BBC3 as a possible player in synergistic action. All combinatorial approaches additionally modulated extrinsic apoptosis pathway genes. The present study provides rational combination strategies involving selective BCL-2 and PI3K/AKT inhibition in B-ALL cell lines. Furthermore, we identified a potential mechanistic background of the synergistic activity of combined venetoclax and perifosine application.

Complete Models of p53 Better Inform the Impact of Hotspot Mutations

Mutations in tumor suppressor genes often lead to cancerous phenotypes. Current treatments leverage signaling pathways that are often compromised by disease-derived deficiencies in tumor suppressors. P53 falls into this category as genetic mutations lead to physical changes in the protein that impact multiple cellular pathways. Here, we show the first complete structural models of mutated p53 to reveal how hotspot mutations physically deviate from the wild-type protein. We employed a recently determined structure for the p53 monomer to map seven frequent clinical mutations using computational modeling approaches. Results showed that missense mutations often changed the conformational structure of p53 in the DNA-binding site along with its electrostatic surface charges. We posit these changes may amplify the toxic effects of these hotspot mutations by destabilizing an important zinc ion coordination region in p53 to impede proper DNA interactions. These results highlight the imperative need for new studies on patient-derived proteins that may assist in redesigning structure-informed targeted therapies.

Deregulation and epigenetic modification of BCL2-family genes cause resistance to venetoclax in hematologic malignancies

The BCL2 inhibitor venetoclax has been approved to treat different hematological malignancies. Because there is no common genetic alteration causing resistance to venetoclax in chronic lymphocytic leukemia (CLL) and B-cell lymphoma, we asked if epigenetic events might be involved in venetoclax resistance. Therefore, we employed whole-exome sequencing, methylated DNA immunoprecipitation sequencing, and genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 screening to investigate venetoclax resistance in aggressive lymphoma and high-risk CLL patients. We identified a regulatory CpG island within the PUMA promoter that is methylated upon venetoclax treatment, mediating PUMA downregulation on transcript and protein level. PUMA expression and sensitivity toward venetoclax can be restored by inhibition of methyltransferases. We can demonstrate that loss of PUMA results in metabolic reprogramming with higher oxidative phosphorylation and adenosine triphosphate production, resembling the metabolic phenotype that is seen upon venetoclax resistance. Although PUMA loss is specific for acquired venetoclax resistance but not for acquired MCL1 resistance and is not seen in CLL patients after chemotherapy-resistance, BAX is essential for sensitivity toward both venetoclax and MCL1 inhibition. As we found loss of BAX in Richter's syndrome patients after venetoclax failure, we defined BAX-mediated apoptosis to be critical for drug resistance but not for disease progression of CLL into aggressive diffuse large B-cell lymphoma in vivo. A compound screen revealed TRAIL-mediated apoptosis as a target to overcome BAX deficiency. Furthermore, antibody or CAR T cells eliminated venetoclax resistant lymphoma cells, paving a clinically applicable way to overcome venetoclax resistance.

Targeting Cpt1a-Bcl-2 interaction modulates apoptosis resistance and fibrotic remodeling

The mitochondrial calcium uniporter (MCU) regulates metabolic reprogramming in lung macrophages and the progression of pulmonary fibrosis. Fibrosis progression is associated with apoptosis resistance in lung macrophages; however, the mechanism(s) by which apoptosis resistance occurs is poorly understood. Here, we found a marked increase in mitochondrial B-cell lymphoma-2 (Bcl-2) in lung macrophages from subjects with idiopathic pulmonary fibrosis (IPF). Similar findings were seen in bleomycin-injured wild-type (WT) mice, whereas Bcl-2 was markedly decreased in mice expressing a dominant-negative mitochondrial calcium uniporter (DN-MCU). Carnitine palmitoyltransferase 1a (Cpt1a), the rate-limiting enzyme for fatty acid β-oxidation, directly interacted with Bcl-2 by binding to its BH3 domain, which anchored Bcl-2 in the mitochondria to attenuate apoptosis. This interaction was dependent on Cpt1a activity. Lung macrophages from IPF subjects had a direct correlation between CPT1A and Bcl-2, whereas the absence of binding induced apoptosis. The deletion of Bcl-2 in macrophages protected mice from developing pulmonary fibrosis. Moreover, mice had resolution when Bcl-2 was deleted or was inhibited with ABT-199 after fibrosis was established. These observations implicate an interplay between macrophage fatty acid β-oxidation, apoptosis resistance, and dysregulated fibrotic remodeling.

Bak instead of Bax plays a key role in metformin-induced apoptosis s in HCT116 cells

Metformin (Met) exhibits anticancer ability in various cancer cell lines. This report aims to explore the exact molecular mechanism of Met-induced apoptosis in HCT116 cells, a human colorectal cancer cell line. Met-induced reactive oxygen species (ROS) increase and ROS-dependent cell death accompanied by plasma membrane blistering, mitochondrial swelling, loss of mitochondrial membrane potential, and release of cytochrome c. Western blotting analysis showed that Met upregulated Bak expression but downregulated Bax expression. Most importantly, silencing Bak instead of Bax inhibited Met-induced loss of mitochondrial membrane potential, indicating the key role of Bak in Met-induced apoptosis. Live-cell fluorescence resonance energy transfer (FRET) analysis showed that Met unlocked the binding of Mcl-1 to Bak, and enhanced the binding of Bim to Bak and subsequent Bak homo-oligomerization. Western blotting analysis showed that Met enhanced AMPK phosphorylation and Bim expression, and compound C, an inhibitor of AMPK, inhibited Met-induced Bim upregulation. Although Met increased the expression of Bcl-xL, overexpression of Bcl-xL did not prevent Met-induced apoptosis. In summary, our data demonstrate for the first time that Met promotes ROS-dependent apoptosis by regulating the Mcl-1-Bim-Bak axis.

Role of the posterior mucosal defense barrier in portal hypertensive gastropathy

Portal hypertensive gastropathy (PHG) is a complication of cirrhotic or noncirrhotic portal hypertension. PHG is very important in the clinic because it can cause acute or even massive blood loss, and its treatment efficacy and prognosis are poor. Currently, the incidence of PHG in patients with cirrhosis is 20-80%, but its pathogenesis is complicated and poorly understood. Studies have shown that portal hypertension can cause changes in gastric mucosal microcirculation hemodynamics, leading to changes in gastric mucosal histology and function and thereby weakening the mucosal defense barrier. However, no specific drug treatment plans are currently available. This article reviews the current literature to further our understanding of the mechanism underlying PHG and the relationship between PHG and the posterior mucosal defense barrier and to explore new therapeutic targets.

Stress Relief Techniques: p38 MAPK Determines the Balance of Cell Cycle and Apoptosis Pathways

Protein signaling networks are formed from diverse and inter-connected cell signaling pathways converging into webs of function and regulation. These signaling pathways both receive and conduct molecular messages, often by a series of post-translation modifications such as phosphorylation or through protein-protein interactions via intrinsic motifs. The mitogen activated protein kinases (MAPKs) are components of kinase cascades that transmit signals through phosphorylation. There are several MAPK subfamilies, and one subfamily is the stress-activated protein kinases, which in mammals is the p38 family. The p38 enzymes mediate a variety of cellular outcomes including DNA repair, cell survival/cell fate decisions, and cell cycle arrest. The cell cycle is itself a signaling system that precisely controls DNA replication, chromosome segregation, and cellular division. Another indispensable cell function influenced by the p38 stress response is programmed cell death (apoptosis). As the regulators of cell survival, the BCL2 family of proteins and their dynamics are exquisitely sensitive to cell stress. The BCL2 family forms a protein-protein interaction network divided into anti-apoptotic and pro-apoptotic members, and the balance of binding between these two sides determines cell survival. Here, we discuss the intersections among the p38 MAPK, cell cycle, and apoptosis signaling pathways.

Endothelial cells from umbilical cord of women affected by gestational diabetes: A suitable in vitro model to study mechanisms of early vascular senescence in diabetes

Human umbilical cord endothelial cells (HUVECs) obtained from women affected by gestational diabetes (GD-HUVECs) display durable pro-atherogenic modifications and might be considered a valid in vitro model for studying chronic hyperglycemia effects on early endothelial senescence. Here, we demonstrated that GD- compared to C-HUVECs (controls) exhibited oxidative stress, altered both mitochondrial membrane potential and antioxidant response, significant increase of senescent cells characterized by a reduced NAD-dependent deacetylase sirtuin-1 (SIRT1) activity together with an increase in cyclin-dependent kinase inhibitor-2A (P16), cyclin-dependent kinase inhibitor-1 (P21), and tumor protein p53 (P53) acetylation. This was associated with the p300 activation, and its silencing significantly reduced the GD-HUVECs increased protein levels of P300 and Ac-P53 thus indicating a persistent endothelial senescence via SIRT1/P300/P53/P21 pathway. Overall, our data suggest that GD-HUVECs can represent an "endothelial hyperglycemic memory" model to investigate in vitro the early endothelium senescence in cells chronically exposed to hyperglycemia in vivo.

Fas/FasL mediates NF-κBp65/PUMA-modulated hepatocytes apoptosis via autophagy to drive liver fibrosis

Fas/Fas ligand (FasL)-mediated cell apoptosis involves a variety of physiological and pathological processes including chronic hepatic diseases, and hepatocytes apoptosis contributes to the development of liver fibrosis following various causes. However, the mechanism of the Fas/FasL signaling and hepatocytes apoptosis in liver fibrogenesis remains unclear. The Fas/FasL signaling and hepatocytes apoptosis in liver samples from both human sections and mouse models were investigated. NF-κBp65 wild-type mice (p65^f/f), hepatocytes specific NF-κBp65 deletion mice (p65Δhepa), p53-upregulated modulator of apoptosis (PUMA) wild-type (PUMA-WT) and PUMA knockout (PUMA-KO) littermate models, and primary hepatic stellate cells (HSCs) were also used. The mechanism underlying Fas/FasL-regulated hepatocytes apoptosis to drive HSCs activation in fibrosis was further analyzed. We found Fas/FasL promoted PUMA-mediated hepatocytes apoptosis via regulating autophagy signaling and NF-κBp65 phosphorylation, while inhibition of autophagy or PUMA deficiency attenuated Fas/FasL-modulated hepatocytes apoptosis and liver fibrosis. Furthermore, NF-κBp65 in hepatocytes repressed PUMA-mediated hepatocytes apoptosis via regulating the Bcl-2 family, while NF-κBp65 deficiency in hepatocytes promoted PUMA-mediated hepatocytes apoptosis and enhanced apoptosis-linked inflammatory response, which contributed to the activation of HSCs and liver fibrogenesis. These results suggest that Fas/FasL contributes to NF-κBp65/PUMA-modulated hepatocytes apoptosis via autophagy to enhance liver fibrogenesis, and this network could be a potential therapeutic target for liver fibrosis.

Melatonin abated Bisphenol A-induced neurotoxicity via p53/PUMA/Drp-1 signaling

Bisphenol A (BPA), an endocrine disruptor, is widely used in the manufacture of different daily life products. Accumulating evidence supports the association between the increasing incidence of neurodegenerative diseases and the BPA level in the environment. In the present study, we aimed to evaluate the neuroprotective role of melatonin against BPA-induced mitochondrial dysfunction-mediated apoptosis in the brain. Herein, adult Sprague Dawley rats were administrated (subcutaneously) with BPA (100 μg/kg BW, 1 mg/kg BW, and 10 mg/kg BW) and melatonin (4 mg/kg BW) for 16 days. Our results showed BPA exposure significantly increased the oxidative stress as demonstrated by increased free radicals (ROS), TBARs level, disrupted cellular architecture, and decreased antioxidant enzymes including SOD, CAT, APX, POD, and GSH levels. Additionally, BPA treatment increased the expression of PUMA, p53, and Drp-1 resulting in apoptosis in the brain tissue of rats. However, melatonin treatment significantly attenuated BPA-induced toxic effects by scavenging ROS, boosting antioxidant enzyme activities, and interestingly enervated brain apoptosis by normalizing p53, PUMA, and Drp-1 expressions at both transcriptional and translational level. Moreover, the brain tissue histology also revealed the therapeutic potential of melatonin by normalizing the cellular architecture. Conclusively, our finding suggests that melatonin could alleviate oxidative stress and mitochondrial dysfunction-linked apoptosis, rendering its neuroprotective potential against BPA-induced toxicity.

Polyhexamethylene Guanidine Phosphate Induces Apoptosis through Endoplasmic Reticulum Stress in Lung Epithelial Cells

Airway epithelial cell death contributes to the pathogenesis of lung fibrosis. Polyhexamethylene guanidine phosphate (PHMG-p), commonly used as a disinfectant, has been shown to be strongly associated with lung fibrosis in epidemiological and toxicological studies. However, the molecular mechanism underlying PHMG-p-induced epithelial cell death is currently unclear. We synthesized a PHMG-p–fluorescein isothiocyanate (FITC) conjugate and assessed its uptake into lung epithelial A549 cells. To examine intracellular localization, the cells were treated with PHMG-p–FITC; then, the cytoplasmic organelles were counterstained and observed with confocal microscopy. Additionally, the organelle-specific cell death pathway was investigated in cells treated with PHMG-p. PHMG-p–FITC co-localized with the endoplasmic reticulum (ER), and PHMG-p induced ER stress in A549 cells and mice. The ER stress inhibitor tauroursodeoxycholic acid (TUDCA) was used as a pre-treatment to verify the role of ER stress in PHMG-p-induced cytotoxicity. The cells treated with PHMG-p showed apoptosis, which was inhibited by TUDCA. Our results indicate that PHMG-p is rapidly located in the ER and causes ER-stress-mediated apoptosis, which is an initial step in PHMG-p-induced lung fibrosis.

Copanlisib promotes growth inhibition and apoptosis by modulating the AKT/FoxO3a/PUMA axis in colorectal cancer

Colorectal cancer (CRC) is the type of cancer with the third highest incidence and is associated with high mortality and low 5-year survival rates. We observed that copanlisib, an inhibitor of PI3K (pan-class I phosphoinositide 3-kinase) that preferentially inhibits PI3Kδ and PI3Kα, impedes the growth of CRC cells by inducing apoptosis via PUMA. There was a marked increase in the expression of PUMA independent of p53 after treatment with copanlisib. The response of CRC cells to copanlisib could be predicted by PUMA expression. Copanlisib was found to induce PUMA expression through FoxO3a by directly binding to the PUMA promoter after inhibiting AKT signaling. PUMA deficiency mitigated the apoptosis induced by copanlisib. Caspase activation and mitochondrial dysfunction led to copanlisib resistance, as observed through a clonogenic assay, whereas enhanced expression of PUMA increased the copanlisib-induced susceptibility to apoptosis. Moreover, the antitumor effects of copanlisib were suppressed by a deficiency of PUMA in a xenograft model, and caspase activation and reduced apoptosis were also observed in vivo. Copanlisib-mediated chemosensitization seemed to involve the concurrent induction of PUMA expression via mechanisms that were both dependent and independent of p53. These observations indicate that apoptosis mediated by PUMA is crucial for the anticancer effects of copanlisib and that manipulation of PUMA may aid in enhancing anticancer activities.

Pioglitazone alleviates cisplatin nephrotoxicity by suppressing mitochondria-mediated apoptosis via SIRT1/p53 signalling

Pioglitazone (PIO) attenuates cisplatin nephrotoxicity whereas the underlying mechanism remains unknown. Apoptosis is associated with mitochondrial dysfunction and SIRT1 activation can decrease cell apoptosis in cisplatin nephrotoxicity. Therefore, we explored whether the protective effect of PIO in cisplatin nephrotoxicity is achieved by suppressing mitochondria‐mediated apoptosis through SIRT1/p53 signalling regulation. Cell viability, apoptosis, survival rate, renal pathology and function were examined. Moreover, we also analysed the expression of SIRT1, Acetyl‐p53, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), mitochondrial permeability transition pore (mPTP) opening, adenosine triphosphate (ATP) and apoptosis‐related protein in vivo and in vitro. Pioglitazone treatment significantly increased cell viability, promoted SIRT1‐p53 interaction, upregulated Bcl‐2 expression, activated SIRT1 and elevated mitochondrial ATP synthesis after cisplatin treatment. However, PIO decreased the generation of ROS, opening of mPTP, dissipation of MMP and translocation of cytochrome c after cisplatin treatment. Pioglitazone also reduced the activation of caspase‐3 and caspase‐9, lowered the ratio of Bax/Bcl‐2, attenuated kidney pathological damage and dysfunction, down‐regulated the expression of Acetyl‐p53, PUMA‐α and Bax and abated cell apoptosis after cisplatin treatment. The SIRT1 inhibitor, EX527, clearly reversed the protective effects of PIO. These results implied PIO attenuated cisplatin nephrotoxicity by suppressing mitochondria‐mediated apoptosis through regulating SIRT1/p53 signalling.

Pistacia integerrima alleviated Bisphenol A induced toxicity through Ubc13/p53 signalling

Exposure to environmental toxicants such as Bisphenol A (BPA) has raised serious health issues globally particularly in developing countries. It is ubiquitously used in the manufacturing of canned food and feeding bottles. BPA generated reactive oxygen species can lead to several diseases including cardiotoxicity. However, the endpoints stimulated in BPA cardiotoxicity yet need to be investigated. The current study was aimed to investigate the underlying molecular pathways which may contribute in revealing the protective effects of Pistacia integerrima against BPA induced oxidative stress. The dose of 100 µg/kg BW of BPA, 200 mg/kg BW P. integerrima, and 4 mg/kg BW melatonin was administered to Sprague Dawley rats. Present results of western blotting and qRT-PCR showed the increased expression of p53, PUMA and Drp1, while downregulation of Ubc13 in heart tissues of BPA treated group whereas the levels were reversed upon treatment with P. integerrima. The role of BPA in heart tissue apoptosis was further confirmed by the increased level of P-p53, cytochrome C and disrupted cellular architecture whereas the P. integerrima has shown its ameliorative potential by mitigating the adverse effects of BPA. Moreover, the oxidant, antioxidant, lipid, and liver markers profile has also revealed the therapeutic potential of P. integerrima by maintaining the levels in the normal range. However, melatonin has also manifested the normalized expression of apoptotic markers, biochemical markers, and tissue architecture. Conclusively, the data suggest that P. integerrima may be a potential candidate for the treatment of BPA induced toxicity by neutralizing the oxidative stress through Ubc13/p53 pathway.

Crosstalk between autophagy and apoptosis: Mechanisms and therapeutic implications

The cellular recycling process of macroautophagy, which is the mechanism by which cellular material is delivered to lysosomes via double membraned vesicles called autophagosomes, is intimately connected to programmed cell death pathways, especially apoptosis. In this article, I discuss some underlying mechanisms and their implications for improving cancer therapy and propose that the approaches that have been taken to understand the autophagy-apoptosis connection to enhance cancer drug action can serve as a model for the kinds of information that should be developed to understand how autophagy controls other biological processes as well.

Effects of Granulocyte Colony-Stimulating Factor on Proliferation and Apoptosis of B Cells in Bone Marrow of Healthy Donors

BACKGROUND AND OBJECTIVE

The aim of this study was to investigate the effects of granulocyte colony-stimulating factor (G-CSF) on the proliferation and apoptosis of bone marrow (BM) B cells from healthy donors and its mechanism.

MATERIALS AND METHODS

The proliferation ability and apoptosis of BM cells from healthy donors before and after in vivo G-CSF application were determined by multiparameter flow cytometry. The gene expression of B cells was detected by RNA-Seq. In vitro experiments were performed to investigate the effects of G-CSF on the proliferation and apoptosis of BM B cells through which gene.

RESULTS

Treating healthy donors with G-CSF significantly decreased proliferation and increased apoptosis of BM B cells. The proliferation of CD19⁺CD27^- B cell subgroup and CD19⁺CD24^hiCD38^hi B cell subset were also decreased. G-CSF also significantly altered proapoptotic genes, cell cycle arrest genes, and DNA replication and cell cycle genes, especially significantly increased SOCS1 expression of BM B cells. In vitro experiments showed that SOCS1 overexpression did not affect B cell proliferation ability and apoptosis.

CONCLUSIONS

Our results suggest that extensive effects of G-CSF on BM B cells, such as inhibiting proliferation, inducing apoptosis, and altering a series of gene expression.

Peroxiredoxin 5 Silencing Sensitizes Dopaminergic Neuronal Cells to Rotenone via DNA Damage-Triggered ATM/p53/PUMA Signaling-Mediated Apoptosis

Peroxiredoxins (Prxs) are a family of thioredoxin peroxidases. Accumulating evidence suggests that changes in the expression of Prxs may be involved in neurodegenerative diseases pathology. However, the expression and function of Prxs in Parkinson’s disease (PD) remains unclear. Here, we showed that Prx5 was the most downregulated of the six Prx subtypes in dopaminergic (DA) neurons in rotenone-induced cellular and rat models of PD, suggesting possible roles in regulating their survival. Depletion of Prx5 sensitized SH-SY5Y DA neuronal cells to rotenone-induced apoptosis. The extent of mitochondrial membrane potential collapse, cytochrome c release, and caspase activation was increased by Prx5 loss. Furthermore, Prx5 knockdown enhanced the induction of PUMA by rotenone through a p53-dependent mechanism. Using RNA interference approaches, we demonstrated that the p53/PUMA signaling was essential for Prx5 silencing-exacerbated mitochondria-driven apoptosis. Additionally, downregulation of Prx5 augmented rotenone-induced DNA damage manifested as induction of phosphorylated histone H2AX (γ-H2AX) and activation of ataxia telangiectasia mutated (ATM) kinase. The pharmacological inactivation of ATM revealed that ATM was integral to p53 activation by DNA damage. These findings provided a novel link between Prx5 and DNA damage-triggered ATM/p53/PUMA signaling in a rotenone-induced PD model. Thus, Prx5 might play an important role in protection against rotenone-induced DA neurodegeneration.

Allosteric modulation of sigma receptors by BH3 mimetics ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax)

ABT-737, ABT-263 (Navitoclax) and ABT-199 (Venetoclax) are under intensive preclinical and clinical investigation as treatments for hematologic and other malignancies. These small molecules mimic pro-death B-cell lymphoma-2 (Bcl-2) Homology 3 (BH3) domain-only proteins. They also bear a structural resemblance to certain sigma (σ) receptor ligands. Moreover, the Bcl-2 and σ receptor protein families are both located primarily at the endoplasmic reticulum, mediate cell death and survival through protein-protein interactions, and physically associate. Accordingly, we examined the ability of the ABT series of BH3 mimetics to interact with σ receptors using radioligand-binding techniques. Negative allosteric modulation of [3H](+)-pentazocine, an agonist, binding to σ1 receptors in guinea pig brain membranes was observed for ABT-737, ABT-263 and ABT-199. Findings included reduction of specific binding to distinct plateaus in concentration-dependent fashion, significant slowing of radioligand dissociation kinetics, and decreases in radioligand affinity with no or modest changes in maximal receptor densities. Using a ternary complex model, dissociation constants (KX) for modulator binding to the σ1 receptor ranged from 1 to 2.5 μM, while negative cooperativity factors (α), representing the changes in affinity of ligand and modulator when bound as a ternary complex with the receptor, ranged from 0.15 to 0.42. These observations were extended and reinforced by studies using intact small cell (NCI-H69) and non-small cell (NCI-H23) lung cancer cells, and by using an antagonist σ1 receptor radioligand, E-N-1-(3'-[125I]iodoallyl)-N'-4-(3″,4″-dimethoxyphenethyl)piperazine, in mouse brain membranes. By contrast, exploratory studies indicate marked enhancement of the σ2 receptor binding of [3H]1,3-di-(o-tolyl)guanidine/(+)-pentazocine in NCI-H23 cells and guinea pig brain membranes. These findings raise intriguing questions regarding mechanism and potential functional outcomes.

BET inhibitor I-BET151 sensitizes GBM cells to temozolomide via PUMA induction

A significant roadblock in treatment of GBM multiforme (GBM) is resistance to temozolomide (TMZ). In this study, we investigated whether I-BET151, a specific BET inhibitor, could sensitize GBM cells to TMZ. Our findings showed that the action of I-BET151 could augment the effect of TMZ on cancer cells U251 and U87 cells. In U251 cells, administration of I-BET151 increased the TMZ-induced apoptosis GBM cells. I-BET151 remarkably enhanced the activities of caspase-3. In addition, I-BET151 promoted TMZ-induced migration and invasion in GBM cells. Moreover, I-BET151 increased the amount of reactive oxygen species as well as superoxide anions with a decrease of activity of SOD and the anti-oxidative properties of GBM cells. I-BET151 also induced increased PUMA expression, which is required for the functions of I-BET151 and regulates the synergistic cytotoxic effects of i-BET151 and TMZ in GBM cells. I-BET151 with TMZ also showed synergistic cytotoxic effects in vivo. These point out to an approach to tackle GBM using TMZ along with BET inhibitors.

Involvement of NLRP3 inflammasome in methamphetamine-induced microglial activation through miR-143/PUMA axis

Nod-like Receptor Protein 3 (NLRP3) inflammasome activation is known to lead to microglia-mediated neuroinflammation. Methamphetamine is known to induce microglial activation. However, whether NLRP3 inflammasome activation contributes to the microglial activation induced by methamphetamine remains elusive. P53-up-regulated modulator of apoptosis (PUMA) is a known apoptosis inducer; however, their role in microglial activation remains poorly understood. Methamphetamine treatment induced NLRP3 inflammasome activation as well microglial activation in animal model. Intriguingly, downregulation of PUMA significantly inhibited the activation of microglia. Methamphetamine treatment increased the expression of PUMA at protein level but not mRNA level. Further study indicated that PUMA expression was regulated at post-transcriptional level by miR-143, which was decreased in methamphetamine-treated cells via the negative transcription factor nuclear factor-kappa B1 (NF-κB1). Using gain- and loss-of-function approaches, we identified a unique role of miR-143/PUMA in mediating microglial activation via regulation of NLRP3 inflammasome activation. These findings provide new insight regarding the specific contributions of the miR-143/PUMA pathway to NLRP3 inflammasome activation in the context of drug abuse.

BCL2-Family Dysregulation in B-Cell Malignancies: From Gene Expression Regulation to a Targeted Therapy Biomarker

BCL2-family proteins have a central role in the mitochondrial apoptosis machinery and their expression is known to be deregulated in many cancer types. Effort in the development of small molecules that selectively target anti-apoptotic members of this family i.e., Bcl-2, Bcl-xL, Mcl-1 recently opened novel therapeutic opportunities. Among these apoptosis-inducing agents, BH3-mimetics (i.e., venetoclax) led to promising preclinical and clinical activity in B cell malignancies. However, several mechanisms of intrinsic or acquired resistance have been described ex vivo therefore predictive markers of response as well as mechanism-based combinations have to be designed. In the present study, we analyzed the expression of the BCL2-family genes across 10 mature B cell malignancies through computational normalization of 21 publicly available Affimetrix datasets gathering 1,219 patient samples. To better understand the deregulation of anti- and pro-apoptotic members of the BCL2-family in hematological disorders, we first compared gene expression profiles of malignant B cells to their relative normal control (naïve B cell to plasma cells, n = 37). We further assessed BCL2-family expression according to tissue localization i.e., peripheral blood, bone marrow, and lymph node, molecular subgroups or disease status i.e., indolent to aggressive. Across all cancer types, we showed that anti-apoptotic genes are upregulated while pro-apoptotic genes are downregulated when compared to normal counterpart cells. Of interest, our analysis highlighted that, independently of the nature of malignant B cells, the pro-apoptotic BH3-only BCL2L11 and PMAIP1 are deeply repressed in tumor niches, suggesting a central role of the microenvironment in their regulation. In addition, we showed selective modulations across molecular subgroups and showed that the BCL2-family expression profile was related to tumor aggressiveness. Finally, by integrating recent data on venetoclax-monotherapy clinical activity with the expression of BCL2-family members involved in the venetoclax response, we determined that the ratio (BCL2+BCL2L11+BAX)/BCL2L1 was the strongest predictor of venetoclax response for mature B cell malignancies in vivo.

Long intergenic noncoding RNA-p21 inhibits apoptosis by decreasing PUMA expression in non-small cell lung cancer

OBJECTIVE

Long noncoding RNAs (lncRNAs) are important mediators in tumor progression. Long intergenic noncoding RNA-p21 (lincRNA-p21) participates in multiple biological processes. This study explored the role of lincRNA-p21 in human non-small cell lung cancer (NSCLC) progression and potential regulatory mechanisms.

METHODS

LincRNA-p21 expression in NSCLC tissues and cell lines (A549, H1299, H1650, and NCI-H2087) was determined by quantitative real-time PCR. LincRNA-p21 overexpressing and sh-lincRNA-p21 lentiviral were respectively transfected into H1299 and A549 cells. Flow cytometry was used to measure apoptosis. Microarray analysis and RNA pull-down assay were used to predict the target genes of lincRNA-p21. Finally, PUMA siRNA and overexpressing PUMA were transfected into NSCLC cells, and the extent of cell apoptosis was measured. The protein expression levels of the relative genes were confirmed by western blot analysis.

RESULTS

LincRNA-p21 was significantly upregulated in NSCLC tissues and cells. The upregulation of lincRNA-p21 considerably inhibited cell apoptosis while the downregulation of lincRNA-p21 showed the opposite effect. PUMA was a direct target gene of lincRNA-p21 and was negatively correlated with lincRNA-p21 in NSCLC specimens. The anti-apoptotic effect of lincRNA-p21 can be effectively attenuated by the upregulation of PUMA.

CONCLUSION

LincRNA-p21 is aberrantly upregulated in NSCLC and inhibits cell apoptosis by decreasing PUMA expression.

Propofol-induced neurotoxicity in hESCs involved in activation of miR-206/PUMA signal pathway

BACKGROUND AND OBJECTIVE

Studies in developing animals have demonstrated that when anesthetic agents, such as propofol, are early administered in life, it can lead to neuronal cell death and learning disabilities. However, the mechanisms causing these effects remains unknown. A recent report found that propofol could significantly upregulat miR-206 expression in the human ASCs. miR-206 could also induce apoptosis in human malignant cancers. Therefore, in this study, we hypothesized that propofol induces neurotoxicity in human embryonic stem cells (hESCs).

METHODS

hESCs were exposed to propofol (50 μM) for 6 hr and cell death was assessed using TUNEL staining, and cleaved caspase-3 expression. miR-206 was knocked down using antagomir. PUMA was knocked down using a small interfering RNA. microRNA-206 (miR-206) expression was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). PUMA protein expression was detected using western blot assay.

RESULTS

hESCs exposed to propofol showed a significant increase in TUNEL positive cells and cleaved caspase-3 expression, followed by the upregulation of miR-206 and PUMA expression. Targeting PUMA inhibits propofol-induced cell apoptosis; miR-206 knockdown decreased propofol-induced cell apoptosis, cleaved caspase-3 and PUMA expression.

CONCLUSIONS

Propofol induce s cell death in hESC-derived neurons via activation of miR-206/PUMA signal pathway.

miRNA‑222 promotes liver cancer cell proliferation, migration and invasion and inhibits apoptosis by targeting BBC3

The present study aimed to investigate molecular mechanisms associated with liver cancer and provide a possible therapeutic target for the treatment of liver cancer. Liver cancer patients that were diagnosed and treated at the Central Hospital of China National Petroleum Corp. were included in the present study. microRNA (miR)‑222 was predicted to target B‑cell lymphoma-2 (Bcl‑2) binding component 3 (BBC3, also known as p53 upregulated modulator of apoptosis) by a bioinformatics analysis with TargetScan, which was verified by a dual‑luciferase reporter assay system. The correlations between BBC3 and miR‑222 levels and the patients' characteristics were analyzed. Furthermore, reverse transcription‑quantitative polymerase chain reaction was used to assess the mRNA levels of miRNA‑222 in the HCC‑LM3, MHCC97H and HepG2 cell lines. HepG2 cells were then transfected with miR‑222 inhibitor or miR‑negative control inhibitor. Cell proliferation, apoptosis, cell cycle, migration and invasion were evaluated by an MTT assay, flow cytometry, wound healing assay and Transwell assay, respectively. BBC3 was quantified by immunofluorescence and western blot analysis, and cyclin D1, Bcl‑2 and caspase‑3 levels were also evaluated by western blotting. miR‑222 inhibitor obviously inhibited HepG2 cell proliferation, migration, invasion, BBC3 and cyclin D1 protein expression levels and enhanced HepG2 cell apoptosis as well as the protein levels of Bcl‑2 and caspase‑3. miR‑222 level in tumors ≥5 cm (maximum) was significantly higher compared with tumors <5 cm (maximum) and was significantly higher in metastatic tumors compared with non‑metastatic tumors, while BBC3 level showed the adverse changes. The results of the present study suggested that miR‑222 inhibitor exerted anti‑cancer effects against liver cancer cells, probably by targeting the 3' untranslated region (UTR) of BBC3.

The selective tyrosine kinase-inhibitor nilotinib alleviates experimentally induced cisplatin nephrotoxicity and heptotoxicity

This work tested the action of nilotinib, selective inhibitor of tyrosine kinase on cisplatin (CP)-induced damage of kidney and liver in rats. Rats were assigned to 4 groups, control, nilotinib, CP, and CP plus nilotinib. Assessment of kidney and liver function, lipid peroxidation and antioxidant markers, anti-apoptotic protein Bcl2, nuclear factor- kappa B (NF-κB) immunoreactivity, and caspase 3 activity were done. CP-induced damage evidenced by histopathological changes, deterioration of renal and liver function, imbalance in oxidants/antioxidants markers, decreased Bcl2, increased caspase 3 activity, and NF-κB nuclear expression in both organs. Nilotinib treatment with CP restored kidney and liver oxidants/antioxidant levels also increased Bcl2 and decreased NF-κB immunoreactivity were evident with nilotinib treatment. In conclusions these results demonstrated a protective effect of nilotinib in experimentally induced CP kidney and liver damage that could be mediated through combating oxidative stress, reducing inflammation and anti-apoptosis in the two organs.

NVP-BKM120 inhibits colon cancer growth via FoxO3a-dependent PUMA induction

NVP-BKM120, a potent and highly selective PI3K inhibitor, is currently being investigated in phase I/II clinical trials. The mechanisms of action of NVP-BKM120 in colon cancer cells are unclear. In the present study, we investigated how NVP-BKM120 suppresses colon cancer cells growth and potentiates effects of other chemotherapeutic drugs. We found that NVP-BKM120 treatment enhance PUMA induction irrespective of p53 status through the FoxO3a pathway following AKT inhibition. Furthermore, PUMA is required for NVP-BKM120-induced apoptosis in colon cancer cells. In addition, NVP-BKM120 also synergized with 5-Fluorouracil or regorafenib to induce marked apoptosis via PUMA induction. Deficiency of PUMA suppressed apoptosis and antitumor effect of NVP-BKM120 in xenograft model. These results demonstrate a key role of PUMA in mediating the anticancer effects of NVP-BKM120 and suggest that PUMA could be used as an indicator of NVP-BKM120 sensitivity, and also have important implications for it clinical applications.

Actinomycin D synergistically enhances the cytotoxicity of CDDP on KB cells by activating P53 via decreasing P53-MDM2 complex

The aim of this study is to investigate the synergism of low dose of actinomycin D (LDActD) to the cytotoxicity of cisplatin (CDDP) on KB cells. The role of P53 reactivation by LDActD in the synergism and its mechanism were further studied. Cell viability was determined by MTT assay. Apoptosis was determined by AnnexinV-FITC/PI staining. Mitochondrial membrane potential (MMP) was detected by JC-1 staining. Expression of proteins was detected by Western blotting (WB) and/or immunofluorescence (IF). Molecular docking of actinomycin D (ACTD) to Mouse double minute 2 homolog (MDM2) and Mouse double minute 2 homolog X (MDMX). MDMX was analyzed by Discovery Studio. The content of P53-MDM2 complex was detected by ELISA assay. The cytotoxicity of CDDP was increased by the combination of LDActD in kinds of cancer cells. Molecular docking showed strong interaction between ACTD and MDM2/MDMX. Meanwhile, LDActD significantly decreased P53-MDM2 complex. Significant increase of the apoptotic activity by the combination therapy in KB cells is P53 upregulated modulator of apoptosis (PUMA) dependent. In addition to the decrease in MMP, LDActD increased P53 regulated protein and decreased BCL-XL in KB cells. LDActD efficiently enhanced the cytotoxicity of CDDP in cancer cells and induced P53-PUMA-dependent and mitochondria-mediated apoptosis in KB cells. The reactivation of P53 was probably achieved by disturbing the interaction of P53 and MDM2/MDMX.

Silencing microRNA-143 protects the integrity of the blood-brain barrier: implications for methamphetamine abuse

MicroRNA-143 (miR-143) plays a critical role in various cellular processes; however, the role of miR-143 in the maintenance of blood-brain barrier (BBB) integrity remains poorly defined. Silencing miR-143 in a genetic animal model or via an anti-miR-143 lentivirus prevented the BBB damage induced by methamphetamine. miR-143, which targets p53 unregulated modulator of apoptosis (PUMA), increased the permeability of human brain endothelial cells and concomitantly decreased the expression of tight junction proteins (TJPs). Silencing miR-143 increased the expression of TJPs and protected the BBB integrity against the effects of methamphetamine treatment. PUMA overexpression increased the TJP expression through a mechanism that involved the NF-κB and p53 transcription factor pathways. Mechanistically, methamphetamine mediated up-regulation of miR-143 via sigma-1 receptor with sequential activation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3' kinase (PI3K)/Akt and STAT3 pathways. These results indicated that silencing miR-143 could provide a novel therapeutic strategy for BBB damage-related vascular dysfunction.

Lipopolysaccharide Induces Human Pulmonary Micro-Vascular Endothelial Apoptosis via the YAP Signaling Pathway

Gram-negative bacterial lipopolysaccharide (LPS) induces a pathologic increase in lung vascular leakage under septic conditions. LPS-induced human pulmonary micro-vascular endothelial cell (HPMEC) apoptosis launches and aggravates micro-vascular hyper-permeability and acute lung injury (ALI). Previous studies show that the activation of intrinsic apoptotic pathway is vital for LPS-induced EC apoptosis. Yes-associated protein (YAP) has been reported to positively regulate intrinsic apoptotic pathway in tumor cells apoptosis. However, the potential role of YAP protein in LPS-induced HPMEC apoptosis has not been determined. In this study, we found that LPS-induced activation and nuclear accumulation of YAP accelerated HPMECs apoptosis. LPS-induced YAP translocation from cytoplasm to nucleus by the increased phosphorylation on Y357 resulted in the interaction between YAP and transcription factor P73. Furthermore, inhibition of YAP by small interfering RNA (siRNA) not only suppressed the LPS-induced HPMEC apoptosis but also regulated P73-mediated up-regulation of BAX and down-regulation of BCL-2. Taken together, our results demonstrated that activation of the YAP/P73/(BAX and BCL-2)/caspase-3 signaling pathway played a critical role in LPS-induced HPMEC apoptosis. Inhibition of the YAP might be a potential therapeutic strategy for lung injury under sepsis.

Synergistic Effect of Expressed miR-128 and Puma Protein on Targeted Induction of Tumor Cell Apoptosis

BACKGROUND

Puma is a highly robust pro-apoptotic protein. The protein becomes activated by p53 ensuing beyond-repair DNA damage. Downregulation of SIRT 1, by miR-128, elevates activated p53 that foment Puma indirectly.

OBJECTIVES

In the present study, we used two-expression Adeno-Associated Virus (AAV) system for co-expression of miR-128 and Puma in order to evaluate apoptotic response; both in the tumor and normal cells, respectively.

MATERIALS AND METHODS

Three recombinant AAVs constructs were generated. The First rAAV bearing Puma under the control of hTERT (p-AAV), the second construct designed such that to carry miR-128 downstream of CMV (mi-AAV), and the last construct comprises of the both CMV-miR-128 and hTERT- Puma. Real-Time PCR and western blotting were used to evaluate expression levels of the transduced genes.

RESULTS

MTT assay and DAPI staining shown suicidal effect of each recombinant AAV vectors. p-AAV cytotoxicity was recorded for 62% of the tumor cells, while for normal cells it was only 20% cytotoxic. The second construct, mi-AAV, was not as potent and selective as p-AAV. This construct was shown to be 27% and 16% cytotoxic for BT-474 and HEK-293 cells, respectively. Co-expression of Puma and miR-128 (p-mi-AAV) was accomplished with a selective cytotoxicity toward BT-474. This construct was 85% toxic for tumor cells, although it was only 25% toxic for the normal cell line (HEK-293).

CONCLUSIONS

In this study, we have shown that not only Puma is able to instigate apoptotic response but also its co-expression along with miR-128 could significantly enhance apoptosis in a synergistic manner.

The Evaluation and Comparison of Transcriptionally Targeted Noxa and Puma Killer Genes to Initiate Apoptosis Under Cancer-Specific Promoter CXCR1 in Hepatocarcinoma Gene Therapy

BACKGROUND

Cancerous cells proliferate as fast as possible without a proper surveillance system. This rapid cell division leads to enormous mutation rates, which help a tumor establish.

OBJECTIVES

This study evaluated the potential of inducing apoptosis using Noxa and Puma in a hepatocarcinoma cell line.

METHODS

The current study generated two recombinant lentiviruses, pLEX-GCN and pLEX-GCP, bearing Noxa and Puma, respectively. Transduction of both genes to hepatocarcinoma (HepG2) was verified using fluorescent microscopic analysis, western blotting, and quantitative real-time polymerase chain reaction (PCR). To evaluate the potential of Noxa and Puma to initiate apoptosis, a caspase-9 real-time, MTT assay, and a 4', 6-diamidino-2-phenylindole (DAPI) reagent were performed to stain apoptotic cells.

RESULTS

The data verified successful transduction to HepG2 and HEK293T. Higher relative expression of Noxa and Puma rather than the untransduced cell line showed these genes are expressed more in HepG2 in comparison to HEK293T. The results of the real-time PCR, MTT assay, and DAPI reagent illustrated that higher cells initiated apoptosis following Puma transduction rather than Noxa.

CONCLUSIONS

In this approach, the suicide gene was transferred to transformed cells and ignited apoptosis to exterminate them. Puma is a more potent killer gene and has higher capabilities to start intrinsic apoptosis pathway.

Subcellular localization of PUMA regulates its pro-apoptotic activity in Burkitt's lymphoma B cells

The BH3-only protein PUMA (p53-upregulated modulator of apoptosis) is a major regulator of apoptosis. It belongs to the Bcl-2 family of proteins responsible for maintaining mitochondrial outer membrane integrity by controlling the intrinsic (mitochondrial) apoptotic pathway. We describe here a new pathway regulating PUMA activation through the control of its subcellular distribution. Surprisingly, neither PUMA upregulation in normal activated human B lymphocytes nor high levels of PUMA in Burkitt's lymphoma (BL) were associated with cell death. We show that PUMA is localized to the cytosol in these cells. By contrast, various apoptosis-triggering signals were found to promote the translocation of PUMA to the mitochondria in these cells, leading to their death by apoptosis. This apoptosis was associated with the binding of mitochondrial PUMA to anti-apoptotic members of the Bcl-2 family, such as Bcl-2 and Mcl-1. This translocation was caspase-independent but was prevented by inhibiting or knocking down the expression of the MAPK kinase p38. Our data suggest that the accumulation of PUMA in the cytosol may be important for the participation of this protein in apoptosis without the need for prior transcription. This regulatory pathway may be an important feature of differentiation and tumorigenic processes.

Mir143-BBC3 cascade reduces microglial survival via interplay between apoptosis and autophagy: Implications for methamphetamine-mediated neurotoxicity

BBC3 (BCL2 binding component 3) is a known apoptosis inducer; however, its role in microglial survival remains poorly understood. In addition to the classical transcription factor TRP53, Mir143 is involved in BBC3 expression at the post-transcriptional level. Here, we identify unique roles of Mir143-BBC3 in mediating microglial survival via the regulation of the interplay between apoptosis and autophagy. Autophagy inhibition accelerated methamphetamine-induced apoptosis, whereas autophagy induction attenuated the decrease in microglial survival. Moreover, anti-Mir143-dependent BBC3 upregulation reversed the methamphetamine-induced decrease in microglial survival via the regulation of apoptosis and autophagy. The in vivo relevance of these findings was confirmed in mouse models, which demonstrated that the microinjection of anti-Mir143 into the hippocampus ameliorated the methamphetamine-induced decrease in microglia as well as that observed in heterozygous Mir143(+/-) mice. These findings provide new insight regarding the specific contributions of Mir143-BBC3 to microglial survival in the context of drug abuse.

A Comprehensive and System Review for the Pharmacological Mechanism of Action of Rhein, an Active Anthraquinone Ingredient

Rhein is a major medicinal ingredient isolated from several traditional Chinese medicines, including Rheum palmatum L., Aloe barbadensis Miller, Cassia angustifolia Vahl., and Polygonum multiflorum Thunb. Rhein has various pharmacological activities, such as anti-inflammatory, antitumor, antioxidant, antifibrosis, hepatoprotective, and nephroprotective activities. Although more than 100 articles in PubMed are involved in the pharmacological mechanism of action of rhein, only a few focus on the relationship of crosstalk among multiple pharmacological mechanisms. The mechanism of rhein involves multiple pathways which contain close interactions. From the overall perspective, the pathways which are related to the targets of rhein, are initiated by the membrane receptor. Then, MAPK and PI3K-AKT parallel signaling pathways are activated, and several downstream pathways are affected, thereby eventually regulating cell cycle and apoptosis. The therapeutic effect of rhein, as a multitarget molecule, is the synergistic and comprehensive result of the involvement of multiple pathways rather than the blocking or activation of a single signaling pathway. We review the pharmacological mechanisms of action of rhein by consulting literature published in the last 100 years in PubMed. We then summarize these pharmacological mechanisms from a comprehensive, interactive, and crosstalk perspective. In general, the molecular mechanism of action of drug must be understood from a systematic and holistic perspective, which can provide a theoretical basis for precise treatment and rational drug use.

Prostaglandin EP2 receptor signaling protects human trabecular meshwork cells from apoptosis induced by ER stress through down-regulation of p53

E-prostanoid receptor subtype 2 (EP2) agonists are currently under clinical development as hypotensive agents for the treatment of ocular hypertension. However, the effects of EP2 receptor agonists on trabecular meshwork (TM) alterations leading to primary open-angle glaucoma (POAG) are still unknown. Here, we evaluated whether EP2 receptor activation exhibits protective functions on TM cell death induced by endoplasmic reticulum (ER) stress. We show that the EP2 receptor agonist butaprost protects TM cell death mediated by the ER stress inducer tunicamycin through a cyclic AMP (cAMP)-dependent mechanism, but independent of the classical cAMP sensors, protein kinase A and exchange proteins activated by cAMP. The ER stress-induced intrinsic apoptosis inhibited by the EP2 receptor agonist was correlated with a decreased accumulation of the cellular stress sensor p53. In addition, p53 down-regulation was associated with inhibition of its transcriptional activity, which led to decreased expression of the pro-apoptotic p53-upregulated modulator of apoptosis (PUMA). The stabilization of p53 by nutlin-3a abolished butaprost-mediated cell death protection. In conclusion, we showed that EP2 receptor activation protects against ER stress-dependent mitochondrial apoptosis through down-regulation of p53. The specific inhibition of this pathway could reduce TM alterations observed in POAG patients.

Uncoupling of PUMA Expression and Apoptosis Contributes to Functional Heterogeneity in Renal Cell Carcinoma - Prognostic and Translational Implications

Renal cell carcinoma (RCC) is characterized by a profound disruption of proapoptotic signaling networks leading to chemo- and radioresistance. A key mediator of DNA damage-induced apoptosis is the BH3-only protein PUMA. Given its central role in proapoptotic signaling, we analyzed a series of more than 600 precision-annotated primary RCC specimens for PUMA protein expression. We found a reduced expression of PUMA in 22.6% of RCCs analyzed. Unexpectedly, however, PUMA deficiency was not associated with more aggressive tumor characteristic as expected. Instead, a reduced PUMA expression was associated with a lower TNM stage, lower histopathologic grade, and more favorable cancer-specific patient survival. A direct correlation in a separate patient cohort revealed a profound disconnection between PUMA expression and apoptosis as exemplified by the fact that the tumor with the highest level of apoptotic cells was PUMA deficient. In a series of in vitro studies, we corroborated these results and discovered the highest propensity to undergo apoptosis in an RCC cell line with virtually undetectable PUMA expression. At the same time, PUMA expression was not necessarily associated with stronger apoptosis induction, which underscores the striking functional heterogeneity of PUMA expression and apoptosis in RCC. Collectively, our findings suggest that PUMA-independent mechanisms of cell death exist and may play an important role in suppressing malignant progression. They underscore the functional heterogeneity of RCCs and suggest that PUMA expression alone may not be a suitable predictive biomarker. A better understanding of alternative proapoptotic pathways, however, may help to design novel therapeutic strategies for patients with advanced RCC.

Conserved molecular mechanisms underlying the effects of small molecule xenobiotic chemotherapeutics on cells

For proper determination of the apoptotic potential of chemoxenobiotics in synergism, it is important to understand the modes, levels and character of interactions of chemoxenobiotics with cells in the context of predicted conserved biophysical properties. Chemoxenobiotic structures are studied with respect to atom distribution over molecular space, the predicted overall octanol-to-water partition coefficient (Log OWPC; unitless) and molecular size viz a viz van der Waals diameter (vdWD). The Log OWPC-to-vdWD (nm^-1 ) parameter is determined, and where applicable, hydrophilic interacting moiety/core-to-vdWD (nm^-1 ) and lipophilic incorporating hydrophobic moiety/core-to-vdWD (nm^-1 ) parameters of their part-structures are determined. The cellular and sub-cellular level interactions of the spectrum of xenobiotic chemotherapies have been characterized, for which a classification system has been developed based on predicted conserved biophysical properties with respect to the mode of chemotherapeutic effect. The findings of this study are applicable towards improving the effectiveness of existing combination chemotherapy regimens and the predictive accuracy of personalized cancer treatment algorithms as well as towards the selection of appropriate novel xenobiotics with the potential to be potent chemotherapeutics for dendrimer nanoparticle-based effective transvascular delivery.

Identifying Novel Candidate Genes Related to Apoptosis from a Protein-Protein Interaction Network

Apoptosis is the process of programmed cell death (PCD) that occurs in multicellular organisms. This process of normal cell death is required to maintain the balance of homeostasis. In addition, some diseases, such as obesity, cancer, and neurodegenerative diseases, can be cured through apoptosis, which produces few side effects. An effective comprehension of the mechanisms underlying apoptosis will be helpful to prevent and treat some diseases. The identification of genes related to apoptosis is essential to uncover its underlying mechanisms. In this study, a computational method was proposed to identify novel candidate genes related to apoptosis. First, protein-protein interaction information was used to construct a weighted graph. Second, a shortest path algorithm was applied to the graph to search for new candidate genes. Finally, the obtained genes were filtered by a permutation test. As a result, 26 genes were obtained, and we discuss their likelihood of being novel apoptosis-related genes by collecting evidence from published literature.

ROS/p38/p53/Puma signaling pathway is involved in emodin-induced apoptosis of human colorectal cancer cells

AIM

Emodin was found effective in suppressing proliferation of cancer cells including colorectal cancer (CRC), but the mechanisms were still unclear. This study was aimed to investigate the possible mechanism of emodin's anti-CRC effects.

METHODS

Two most frequently used CRC cell lines, SW480 and SW620, were investigated in this study. Serially diluted emodin solutions were used to incubate CRC cells. siRNAs were used to silence the expressions of p38 and Puma respectively. Intracellular ROS production was detected by DCFH-DA staining; proliferation and apoptosis of CRC cells were assessed by MTT assay and Hoechst staining respectively. Western blotting was applied to evaluate the activation of p38/p53/Puma signaling.

RESULTS

Both in SW480 and SW620 cells, emodin inhibited proliferation by inducing ROS-mediated apoptosis in a concentration-dependent manner. The p38/p53/Puma signaling was also activated after emodin incubation in a concentration-dependent manner. The ROS scavenger NAC, p38 silencing and Puma silencing impaired the anti-proliferation and apoptosis- inducing effects of emodin.

CONCLUSIONS

emodin inhibited proliferation of human CRC cells by inducing cell apoptosis by activating ROS/p38/p53/Puma signaling.

Harnessing the p53-PUMA axis to overcome DNA damage resistance in renal cell carcinoma

Resistance to DNA damage–induced apoptosis is a hallmark of cancer and a major cause of treatment failure and lethal disease outcome. A tumor entity that is largely resistant to DNA-damaging therapies including chemo- or radiotherapy is renal cell carcinoma (RCC). This study was designed to explore the underlying molecular mechanisms of DNA damage resistance in RCC to develop strategies to resensitize tumor cells to DNA damage–induced apoptosis. Here, we show that apoptosis-resistant RCC cells have a disconnect between activation of p53 and upregulation of the downstream proapoptotic protein p53 upregulated modulator of apoptosis (PUMA). We demonstrate that this disconnect is not caused by gene-specific repression through CCCTC-binding factor (CTCF) but instead by aberrant chromatin compaction. Treatment with an HDAC inhibitor was found to effectively reactivate PUMA expression on the mRNA and protein level and to revert resistance to DNA damage–induced cell death. Ectopic expression of PUMA was found to resensitize a panel of RCC cell lines to four different DNA-damaging agents tested. Remarkably, all RCC cell lines analyzed were wild-type for p53, and a knockdown was likewise able to sensitize RCC cells to acute genotoxic stress. Taken together, our results indicate that DNA damage resistance in RCC is reversible, involves the p53-PUMA axis, and is potentially targetable to improve the oncological outcomes of RCC patients.

Cell death decision by p53 via control of the mitochondrial membrane

The tumor suppressor p53 is mutated in more than half of human cancers. Recent evidence has revealed that p53 not only regulates apoptosis but also regulates necrotic/necroptotic cell death via the mitochondria. The regulation of apoptosis by p53 is tightly connected to the mitochondrial outer membrane permeabilization and the induction of and interaction with Bcl-2 family members. Interestingly, p53-mediated regulation of necrosis/necroptosis is correlated with mitochondrial permeabilization pore opening via interactions with CypD and Drp1. This review discusses the p53-regulating molecules that induce apoptosis or necrosis/necroptosis via the mitochondria.

Mode of cell death induced by the HSP90 inhibitor 17-AAG (tanespimycin) is dependent on the expression of pro-apoptotic BAX

Inhibitors of the molecular chaperone heat shock protein 90 (HSP90) are of considerable current interest as targeted cancer therapeutic agents because of the ability to destabilize multiple oncogenic client proteins. Despite their resulting pleiotropic effects on multiple oncogenic pathways and hallmark traits of cancer, resistance to HSP90 inhibitors is possible and their ability to induce apoptosis is less than might be expected. Using an isogenic model for BAX knockout in HCT116 human colon carcinoma cells, we demonstrate the induction of BAX-dependent apoptosis at pharmacologically relevant concentrations of the HSP90 inhibitor 17-AAG both in vitro and in tumor xenografts in vivo. Removal of BAX expression by homologous recombination reduces apoptosis in vitro and in vivo but allows a lower level of cell death via a predominantly necrotic mechanism. Despite reducing apoptosis, the loss of BAX does not alter the overall sensitivity to 17-AAG in vitro or in vivo. The results indicate that 17-AAG acts predominantly to cause a cytostatic antiproliferative effect rather than cell death and further suggest that BAX status may not alter the overall clinical response to HSP90 inhibitors. Other agents may be required in combination to enhance tumor-selective killing by these promising drugs. In addition, there are implications for the use of apoptotic endpoints in the assessment of the activity of molecularly targeted agents.