An essential role for NF-kappaB in preventing TNF-alpha-induced cell death

The synergy between ionizing radiation and immunotherapy in the treatment of prostate cancer

There has been a surge in the use of immunotherapy for genitourinary malignancies. Immunotherapy is an established treatment for metastatic renal cell carcinoma and nonmuscle invasive bladder cancer, but its potential for treating prostate cancer (PCa) remains under investigation. Despite reported survival benefits, no published Phase III PCa trials using immunotherapy only as a treatment has demonstrated direct antitumor effects by reducing prostate-specific antigen levels. Subsequently, the thought of combining immunotherapy with other treatment modalities has gained traction as a way to achieving optimal results. Based on data from other malignancies, it is hypothesized that radiotherapy and immunotherapy can act synergistically to improve outcomes. We will discuss the clinical potential of combining immune-based treatments with radiotherapy as a treatment for advanced PCa.

System-wide coordinates of higher order functions in host-pathogen environment upon Mycobacterium tuberculosis infection

Molecular signatures and their interactions behind the successful establishment of infection of Mycobacterium tuberculosis (Mtb) inside macrophage are largely unknown. In this work, we present an inter-system scale atlas of the gene expression signatures, their interactions and higher order gene functions of macrophage-Mtb environment at the time of infection. We have carried out large-scale meta-analysis of previously published gene expression microarray studies andhave identified a ranked list of differentially expressed genes and their higher order functions in intracellular Mtb as well as the infected macrophage. Comparative analysis of gene expression signatures of intracellular Mtb with the in vitro dormant Mtb at different hypoxic and oxidative stress conditions led to the identification of the large number of Mtb functional groups, namely operons, regulons and pathways that were common and unique to the intracellular environment and dormancy state. Some of the functions that are specific to intracellular Mtb are cholesterol degradation and biosynthesis of immunomodulatory phenolic compounds. The molecular signatures we have identified to be involved in adaptation to different stress conditions in macrophage environment may be critical for designing therapeutic interventions against tuberculosis. And, our approach may be broadly applicable for investigating other host-pathogen interactions.

The Direct and Indirect Roles of NF-κB in Cancer: Lessons from Oncogenic Fusion Proteins and Knock-in Mice

NF-κB signaling pathways play an important role in the regulation of cellular immune and stress responses. Aberrant NF-κB activity has been implicated in almost all the steps of cancer development and many of the direct and indirect contributions of this transcription factor system for oncogenesis were revealed in the recent years. The indirect contributions affect almost all hallmarks and enabling characteristics of cancer, but NF-κB can either promote or antagonize these tumor-supportive functions, thus prohibiting global NF-κB inhibition. The direct effects are due to mutations of members of the NF-κB system itself. These mutations typically occur in upstream components that lead to the activation of NF-κB together with further oncogenesis-promoting signaling pathways. In contrast, mutations of the downstream components, such as the DNA-binding subunits, contribute to oncogenic transformation by affecting NF-κB-driven transcriptional output programs. Here, we discuss the features of recently identified oncogenic RelA fusion proteins and the characterization of pathways that are regulating the transcriptional activity of NF-κB by regulatory phosphorylations. As NF-κB’s central role in human physiology prohibits its global inhibition, these auxiliary or cell type-specific NF-κB regulating pathways are potential therapeutic targets.

Prediction of early hepatocellular carcinoma recurrence using germinal center kinase-like kinase

Germinal center kinase-like kinase (GLK) is a key controller of autoimmunity. In this study, we assessed the clinical relevance and tumorigenic effects of GLK in hepatocellular carcinoma (HCC). Using immunohistochemistry, we showed that the GLK proportion score increased in both cancerous and adjacent non-cancerous liver tissue from patients with HCC recurrence. A Kaplan-Meier analysis revealed that patients with a wide distribution of GLK in non-cancerous liver tissue had a higher rate of HCC recurrence than those with very low or no GLK expression. Multivariate Cox regression analyses indicated that a high GLK proportion score in non-cancerous liver tissue was an independent predictor of early HCC recurrence after resection. Lentiviral vector-mediated overexpression of GLK activated the nuclear factor kappa B (NFκB) signaling cascade and accelerated cell cycle progression in primary human hepatocytes, thereby promoting proliferation. An increase in GLK expression coincided with NFκB activation and enhanced expression of proliferating cell nuclear antigen in HCC tissue. Our findings demonstrate a potential hepatocarcinogenic effect of GLK and the feasibility of using GLK to predict early HCC recurrence.

Targeting BNIP3 in inflammation-mediated heart failure: a novel concept in heart failure therapy

Myocardial injury activates inflammatory mediators and provokes the integration of BCL-2/adenovirus E1B 19KD interacting protein 3 (BNIP3) into mitochondrial membranes. Translocation of BNIP3 to mitochondria inexorably causes mitochondrial fragmentation. Heart failure (HF) epitomizes the life-threatening phase of BNIP3-induced mitochondrial dysfunction and cardiomyocyte death. Available data suggest that inflammatory mediators play a key role in cardiac cell demise and have been implicated in the pathogenesis of HF syndrome. In the present study, we reviewed the changes in BNIP3 protein expression levels during inflammatory response and postulated its role in inflammation-mediated HF. We also identified inflammatory mediators' response such as stimulation of TNF-α and NO as potent inducer of BNIP3. Previous studies suggest that the pro-apoptotic protein has a common regulator with IL-1β and induces IL-6-stimulated cardiac hypertrophy. These findings corroborate our contention that interventions designed to functionally modulate BNIP3 activity during inflammatory-mediated HF may prove beneficial in preventing HF. Such a revelation will open new avenue for further research to unravel a novel therapeutic strategy in HF diseases. Moreover, understanding of the relationship between BNIP3 and inflammatory mediators in HF pathologies will not only contribute to the discovery of drugs that can inhibit inflammation-mediated heart diseases, but also enhance the current knowledge on the key role BNIP3 plays during inflammation.

Nimotuzumab enhances the sensitivity of non-small cell lung cancer cells to tumor necrosis factor-α by inhibiting the nuclear factor-кB signaling pathway

Non-small cell lung cancer (NSCLC) accounts for ~85% of lung cancer cases worldwide. Current guidelines recommend the use of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors for patients with NSCLC. The EGF/EGFR signaling pathway has been demonstrated to activate nuclear factor (NF)-κB, which may inhibit tumor necrosis factor (TNF)-α induced cell apoptosis. The aim of the present study was to investigate whether inhibiting the EGF/EGFR signaling pathway sensitizes NSCLC cell lines to TNF-α-induced apoptosis. The resistance of NSCLC cell lines to TNF-α was evaluated by cell viability assay. The effect of nimotuzumab (Ni) on NSCLC cell sensitivity to TNF-α, as well as the role of NF-κB in mediating resistance to TNF-α-induced apoptosis, was explored by western blot analysis, cell viability assay, apoptosis assay and an NF-κB DNA binding assay. It was demonstrated that EGFR protein expression was markedly higher in the H292 and H1975 cell lines compared with H460 and H1299 cell lines. H292 and H1975 also exhibited significantly increased TNF-α resistance compared with H460 and H1299 cells. Low dose Ni treatment slightly reduced the viability of H292 and H1975 cells; however, combined treatment with low dose Ni and TNF-α significantly inhibited H292 and H1299 cell viability compared with H460 and H1299 cells by inducing cell apoptosis. NF-κB protein expression and activity were also inhibited by the combination treatment. TNF-α treatment alone induced apoptosis in NF-κB deficient H292 and H1975 cells, similar to the effect of combination treatment in wild type H292 and H1975 cells. The results of the present study suggest that Ni sensitizes NSCLC cell lines to TNF-α-induced cell death by inhibiting NF-κB protein expression and activation, indicating a novel mechanism by which Ni suppresses the development of NSCLC.

An in-vitro approach for water quality determination: activation of NF-κB as marker for cancer-related stress responses induced by anthropogenic pollutants of drinking water

Epidemiological studies show that there is a link between urban water pollution and increase in human morbidity and mortality. With the increase in number of new substances arising from the chemical, pharmaceutical, and agricultural industries, there is an urgent need to develop biological test systems for fast evaluation of potential risks to humans and the environmental ecosystems. Here, a combined cellular reporter assay based on the cellular survival and the stress-induced activation of the survival-promoting factor nuclear factor κB (NF-κB) and its use for the detection of cytotoxicity and cancer-related stress responses is presented. A total of 14 chemicals that may be found in trace-amounts in ground water levels are applied and tested with the presented assay. The project is embedded within the joint research project TOX-BOX which aims to develop a harmonized testing strategy for risk management of anthropogenic trace substances in potable water. The assay identified carbendazim as a NF-κB-activating agent in mammalian cells.

γδ T cells provide the early source of IFN-γ to aggravate lesions in spinal cord injury

Immune responses and neuroinflammation are critically involved in spinal cord injury (SCI). γδ T cells, a small subset of T cells, regulate the inflammation process in many diseases, yet their function in SCI is still poorly understood. In this paper, we demonstrate that mice deficient in γδ T cells (TCRδ^-/- ) showed improved functional recovery after SCI. γδ T cells are detected at the lesion sites within 24 hours after injury and are predominantly of the Vγ4 subtype and express the inflammatory cytokine IFN-γ. Inactivating IFN-γ signaling in macrophages results in a significantly reduced production of proinflammatory cytokines in the cerebrospinal fluid (CSF) of mice with SCIs and improves functional recovery. Furthermore, treatment of SCI with anti-Vγ4 antibodies has a beneficial effect, similar to that obtained with anti-TNF-α. In SCI patients, γδ T cells are detected in the CSF, and most of them are IFN-γ positive. In conclusion, manipulation of γδ T cell functions may be a potential approach for future SCI treatment.

Fibroblasts Promote Inflammation and Pain via IL-1α Induction of the Monocyte Chemoattractant Chemokine (C-C Motif) Ligand 2

Fibroblasts persist within fibrotic scar tissue and exhibit considerable phenotypic and functional plasticity. Herein, we hypothesized that scar-associated fibroblasts may be a source of stress-induced inflammatory exacerbations and pain. To test this idea, we used a human model of surgery-induced fibrosis, total knee arthroplasty (TKA). Using a combination of tissue protein expression profiling and bioinformatics, we discovered that many months after TKA, the fibrotic joint exists in a state of unresolved chronic inflammation. Moreover, the infrapatellar fat pad, a soft tissue that becomes highly fibrotic in the post-TKA joint, expresses multiple inflammatory mediators, including the monocyte chemoattractant, chemokine (C-C motif) ligand (CCL) 2, and the innate immune trigger, IL-1α. Fibroblasts isolated from the post-TKA fibrotic infrapatellar fat pad express the IL-1 receptor and on exposure to IL-1α polarize to a highly inflammatory state that enables them to stimulate the recruitment of monocytes. Blockade of fibroblast CCL2 or its transcriptional regulator NF-κB prevented IL-1α-induced monocyte recruitment. Clinical investigations discovered that levels of patient-reported pain in the post-TKA joint correlated with concentrations of CCL2 in the joint tissue, such that the chemokine is effectively a pain biomarker in the TKA patient. We propose that an IL-1α-NF-κB-CCL2 signaling pathway, operating within scar-associated fibroblasts, may be therapeutically manipulated for alleviating inflammation and pain in fibrotic joints and other tissues.

Nanocurcumin-pyrroloquinoline formulation prevents hypertrophy-induced pathological damage by relieving mitochondrial stress in cardiomyocytes under hypoxic conditions

This study investigates the therapeutic effect of a nanocurcumin formulation (NCF) containing nanocurcumin (NC) and pyrroloquinoline quinone (PQQ) on ameliorating hypoxia-induced stress in hypertrophied primary human ventricular cardiomyocytes (HVCM) under hypoxic conditions, as validated in a Sprague-Dawley rat model of chronic hypobaric hypoxia (cHH)-induced right ventricular hypertrophy (RVH). Based on our previous findings, here, we analyzed the improvement in the protective efficacy of NCF against mitochondrial damage. The electron transport chain Complexes’ activities were analyzed as a chief operational center for mitochondrial homeostasis, along with key gene and protein markers for mitochondrial biogenesis, redox function, fatty acid oxidation, bio-energetic deficit and cell survival. NCF supplementation imparts cyto-protection from hypoxia-induced hypertrophy and damage in both in vitro and in vivo models while maintaining mitochondrial homeostasis better than NC and PQQ alone. This study proposes the use of NCF as a potential candidate molecule for imparting protection from high altitude-induced maladies in ascendants.

TRIM8: Making the Right Decision between the Oncogene and Tumour Suppressor Role

The TRIM8/GERP protein is a member of the TRIM family defined by the presence of a common domain structure composed of a tripartite motif including a RING-finger, one or two B-box domains, and a coiled-coil motif. The TRIM8 gene maps on chromosome 10 within a region frequently found deleted and rearranged in tumours and transcribes a 3.0-kB mRNA. Its expression is mostly ubiquitously in murine and human tissues, and in epithelial and lymphoid cells, it can be induced by IFNγ. The protein spans 551 aa and is highly conserved during evolution. TRIM8 plays divergent roles in many biological processes, including important functions in inflammation and cancer through regulating various signalling pathways. In regulating cell growth, TRIM8 exerts either a tumour suppressor action, playing a prominent role in regulating p53 tumour suppressor activity, or an oncogene function, through the positive regulation of the NF-κB pathway. The molecular mechanisms underlying this dual role in human cancer will be discussed in depth in this review, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the pro-oncogenic arm of the TRIM8 signalling pathway without affecting its tumour suppressive effects.

Embryonic Lethality and Host Immunity of RelA-Deficient Mice Are Mediated by Both Apoptosis and Necroptosis

In mammalian cells, signaling pathways triggered by TNF can be switched from NF-κB activation to apoptosis and/or necroptosis. The in vivo mechanisms underlying the mutual regulation of these three signaling pathways are poorly understood. In this article, we report that the embryonic lethality of RelA-deficient mice is partially prevented by the deletion of Rip3 or Mlkl, but it is fully rescued by the combined ablation of Fadd and Rip3 or Mlkl or by blocking RIP1 kinase activity (RIP1^K45A). RelA^-/-Fadd^-/-Rip3^-/- triple-knockout (TKO) and RelA^-/-Rip1^K45A/K45A mice displayed bacterial pneumonia leading to death ∼2 wk after birth. Moreover, RelA^-/-Rip1^K45A/K45A mice, but not TKO mice, developed severe inflammation associated with inflammatory skin lesion. Antibiotic treatment improved bacterial pneumonia, extended the lifespan of TKO and RelA^-/-Rip1^K45A/K45A mice, and alleviated skin inflammation in RelA^-/-Rip1^K45A/K45A mice. These results show the mechanisms underlying the in vivo mutual regulation between NF-κB activation and the cell death pathway and provide new insights into this interplay in embryonic development and host immune homeostasis.

NF-κB and the Transcriptional Control of Inflammation

The NF-κB transcription factor was discovered 30 years ago and has since emerged as the master regulator of inflammation and immune homeostasis. It achieves this status by means of the large number of important pro- and antiinflammatory factors under its transcriptional control. NF-κB has a central role in inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, and autoimmunity, as well as diseases comprising a significant inflammatory component such as cancer and atherosclerosis. Here, we provide an overview of the studies that form the basis of our understanding of the role of NF-κB subunits and their regulators in controlling inflammation. We also describe the emerging importance of posttranslational modifications of NF-κB in the regulation of inflammation, and highlight the future challenges faced by researchers who aim to target NF-κB transcriptional activity for therapeutic benefit in treating chronic inflammatory diseases.

Model of vascular desmoplastic multispecies tumor growth

We present a three-dimensional nonlinear tumor growth model composed of heterogeneous cell types in a multicomponent-multispecies system, including viable, dead, healthy host, and extra-cellular matrix (ECM) tissue species. The model includes the capability for abnormal ECM dynamics noted in tumor development, as exemplified by pancreatic ductal adenocarcinoma, including dense desmoplasia typically characterized by a significant increase of interstitial connective tissue. An elastic energy is implemented to provide elasticity to the connective tissue. Cancer-associated fibroblasts (myofibroblasts) are modeled as key contributors to this ECM remodeling. The tumor growth is driven by growth factors released by these stromal cells as well as by oxygen and glucose provided by blood vasculature which along with lymphatics are stimulated to proliferate in and around the tumor based on pro-angiogenic factors released by hypoxic tissue regions. Cellular metabolic processes are simulated, including respiration and glycolysis with lactate fermentation. The bicarbonate buffering system is included for cellular pH regulation. This model system may be of use to simulate the complex interactions between tumor and stromal cells as well as the associated ECM and vascular remodeling that typically characterize malignant cancers notorious for poor therapeutic response.

Investigating the Antiangiogenic, Anti-drug Resistance and Apoptotic Effects of Soy Isoflavone Extract Alone or in Combination with Docetaxel on Murine 4T1 Breast Tumor Model

BACKGROUND

One major concern in the treatment of cancer patients during chemotherapy is drug resistance. Here we investigated the effects of soy isoflavone extracts alone or in combination with Docetaxel on the drug resistance, angiogenesis, apoptosis, and tumor volume in mouse 4T1 breast tumor model.

METHODS

Sixty female BALB/c mice were randomly divided into 4 groups: control, dietary soy isoflavone extract [Iso, 100 mg/kg diet (0.01%)], Docetaxel (10 mg/kg) injection, and the combination of dietary soy isoflavone extract and intravenous Docetaxel injection (Docetaxel + Iso). One week after the third injection, the breast tumors of eight mice from each group were excised to analyze NF-κBp65' vascular endothelial growth factor receptor-2 (VEGFR2) and Pgp gene and protein expressions and the other seven mice were monitored for survival rate analysis until they died.

RESULTS

NF-κBp65 gene and protein expressions were significantly lower in the Docetaxel + Iso group in comparison with that of the Docetaxel group. VEGFR2 protein expression in the Docetaxel + Iso and Iso groups was significantly lower than that of the Docetaxel group.

CONCLUSION

These findings may indicate that the combined use of isoflavone extracts together with chemotherapeutic agents has more efficient anti-carcinogenic effects than their individual use.

Capacity of Pneumococci to Activate Macrophage Nuclear Factor κB: Influence on Necroptosis and Pneumonia Severity

During pneumococcal pneumonia, antibacterial defense requires the orchestrated expression of innate immunity mediators, initiated by alveolar macrophages and dependent on transcription driven by nuclear factor κB (NF-κB). Such immune pressure may select for pneumococci, which avoid or subvert macrophage NF-κB activation. Analyzing pneumococci collected from children in Massachusetts, we found that the activation of macrophage NF-κB by Streptococcus pneumoniae is highly diverse, with a preponderance of low NF-κB activators that associate particularly with complicated pneumonia. Low NF-κB activators cause more severe lung infections in mice, and they drive macrophages toward an alternate and detrimental cell fate of necroptosis. Both outcomes can be reversed by activation of macrophages with pneumococci that are high NF-κB activators. These results suggest that low NF-κB activation is a virulence property of pneumococci and that the appropriate activation of macrophages, including NF-κB, may hold promise as an adjunct therapeutic avenue for pneumococcal pneumonia.

Modulation of heart rate and heart rate variability by n-3 long chain polyunsaturated fatty acids: Speculation on mechanism(s)

Heart rate (HR) and heart rate variability (HRV) are valuable markers of health. Although the underlying mechanism(s) are controversial, it is well documented that n-3 long chain polyunsaturated fatty acid (LCPUFA) intake improves HR and HRV in various populations. Autonomic modulation and/or alterations in cardiac electrophysiology are commonly cited as potential mechanisms responsible for these effects. This article reviews existing evidence for each and explores a separate mechanism which has not received much attention but has scientific merit. Based on presented evidence, it is proposed that n-3 LCPUFAs affect HR and HRV directly by autonomic modulation and indirectly by altering circulating factors, both dependently and independently of the autonomic nervous system. The evidence for changes in cardiac electrophysiology as the mechanism by which n-3 LCPUFAs affect HR and HRV needs strengthening.

Valproic acid increases NF-κB transcriptional activation despite decreasing DNA binding ability in P19 cells, which may play a role in VPA-initiated teratogenesis

The nuclear factor-kappa B (NF-κB) family of transcription factors regulate gene expression in response to diverse stimuli. We previously demonstrated that valproic acid (VPA) exposure in utero decreases total cellular protein expression of the NF-κB subunit p65 in CD-1 mouse embryos with a neural tube defect but not in phenotypically normal littermates. This study evaluated p65 mRNA and protein expression in P19 cells and determined the impact on DNA binding ability and activity. Exposure to 5mM VPA decreased p65 mRNA and total cellular protein expression however, nuclear p65 protein expression was unchanged. VPA reduced NF-κB DNA binding and nuclear protein of the p65 DNA-binding partner, p50. NF-κB transcriptional activity was increased with VPA alone, despite decreased phosphorylation of p65 at Ser276, and when combined with tissue necrosis factor α. These results demonstrate that VPA increases NF-κB transcriptional activity despite decreasing DNA binding, which may play a role in VPA-initiated teratogenesis.

Conditional, Genetically Encoded, Small Molecule-Regulated Inhibition of NFκB Signaling in RPE Cells

Purpose

Nuclear factor κB (NFκB) is a ubiquitously expressed, proinflammatory transcription factor that controls the expression of genes involved in cell survival, angiogenesis, complement activation, and inflammation. Studies have implicated NFκB-dependent cytokines or complement-related factors as being detrimentally involved in retinal diseases, thus making inhibition of NFκB signaling a potential therapeutic target. We sought to develop a conditional and reversible method that could regulate pathogenic NFκB signaling by the addition of a small molecule.

Methods

We developed a genetically based, trimethoprim (TMP)-regulated approach that conditionally inhibits NFκB signaling by fusing a destabilized dihydrofolate reductase (DHFR) domain to an inhibitor of NFκB, IκBα, in ARPE-19 cells. We then challenged ARPE-19 cells with a number of stimuli that have been demonstrated to trigger NFκB signaling, including LPS, TNFα, IL-1α, and A2E. Western blotting, electrophoretic mobility shift assay, quantitative PCR, ELISA, and NFκB reporter assays were used to evaluate the effectiveness of this DHFR-IκBα approach.

Results

This destabilized domain approach, coupled with doxycycline-inducibility, allowed for accurate control over the abundance of DHFR-IκBα. Stabilization of DHFR-IκBα with TMP prevented IL-1α-, A2E-, LPS-, and TNFα-induced NFκB-mediated upregulation and release of the proinflammatory cytokines IL-1β and IL-6 from ARPE-19 cells (by as much as 93%). This strategy is dosable, completely reversible, and can be cycled “on” or “off” within the same cell population repeatedly to confer protection at desired time points.

Conclusions

These studies lay the groundwork for the use of destabilized domains in retinal pigment epithelium (RPE) cells in vivo and in this context, demonstrate their utility for preventing inflammatory signaling.

Heat-induced inflammation and its role in esophageal cancer

Esophageal cancer, the sixth most common cause of death from cancer worldwide, consists of different histological types and displays various patterns of incidence. Esophageal adenocarcinoma and esophageal squamous cell carcinoma are the most prevalent types. As epidemiological studies report that ingesting hot substances is one major risk factor for squamous cell carcinoma, evaluating the effect of this external stress on esophagus cells seems desirable. This specific kind of stress brings about cellular changes and stabilizes them by affecting different cellular features such as genetic stability, membrane integrity and the regulation of signaling pathways. It also causes tissue injury by affecting the extracellular matrix and cell viability. Thus, one of the main consequences of thermal injury is the activation of the immune system, which can result in chronic inflammation. The genetic alteration that has occurred during thermal injury and the consequent reduction in the function of repair systems is further strengthened by chronic inflammation, thereby increasing the probability that mutated cell lines may appear. The molecules that present in this circumstance, such as heat shock proteins, cytokines, chemokines and other inflammatory factors, affect intercellular signaling pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells, signal transducer activator of transcription-3 and hypoxia-inducible factor 1α in supporting the survival and emergence of mutant phenotypes and the consequent malignant progression in altered cell lines. This investigation of these effective factors and their probable role in the tumorigenic path may improve current understanding.

Biological determinants of radioresistance and their remediation in pancreatic cancer

Despite recent advances in radiotherapy, a majority of patients diagnosed with pancreatic cancer (PC) do not achieve objective responses due to the existence of intrinsic and acquired radioresistance. Identification of molecular mechanisms that compromise the efficacy of radiation therapy and targeting these pathways is paramount for improving radiation response in PC patients. In this review, we have summarized molecular mechanisms associated with the radio-resistant phenotype of PC. Briefly, we discuss the reversible and irreversible biological consequences of radiotherapy, such as DNA damage and DNA repair, mechanisms of cancer cell survival and radiation-induced apoptosis following radiotherapy. We further describe various small molecule inhibitors and molecular targeting agents currently being tested in preclinical and clinical studies as potential radiosensitizers for PC. Notably, we draw attention towards the confounding effects of cancer stem cells, immune system, and the tumor microenvironment in the context of PC radioresistance and radiosensitization. Finally, we discuss the need for examining selective radioprotectors in light of the emerging evidence on radiation toxicity to non-target tissue associated with PC radiotherapy.

Cystatin D (CST5): An ultra-early inflammatory biomarker of traumatic brain injury

Traumatic brain injury (TBI) is set to become the leading cause of neurological disability across all age groups. Currently, no reliable biomarkers exist to help diagnose the severity of TBI to identify patients who are at risk of developing secondary injuries. Thus, the discovery of reliable biomarkers for the management of TBI would improve clinical interventions. Inflammatory markers are particularly suited for biomarker discovery as TBI leads to very early alterations in inflammatory proteins. Using the Proseek Multiplex Inflammation assay, we measured in patients that had suffered mild TBI (n = 10) or severe TBI (n = 10) with extra-cranial injury or extracranial injury only (EC) (n = 10), 92 inflammation-associated proteins in serum obtained: <1 hr (within 1-hour), 4–12 hr and 48–72 hr post injury. Changes were compared to healthy volunteers (HV). Our results identified CST5, AXIN1 and TRAIL as novel early biomarkers of TBI. CST5 identified patients with severe TBI from all other cohorts and importantly was able to do so within the first hour of injury. AXIN1 and TRAIL were able to discriminate between TBI and HV at <1 hr. We conclude that CST5, AXIN1 and TRAIL are worthy of further study in the context of a pre-hospital or pitch-side test to detect brain injury.

SUMO-triggered ubiquitination of NR4A1 controls macrophage cell death

Nuclear receptor NR4A1 has been implicated as a key regulator in a wide range of pathophysiological responses. As an immediate early response gene, NR4A1 can be rapidly and potently induced by a variety of stimuli. Its induction is followed by its rapid degradation, but the mechanism by which NR4A1 is degraded remains poorly understood. Here we show that nuclear receptor NR4A1 is sumoylated by SUMO2/3. Upon poly-SUMO modification, NR4A1 can be targeted by the SUMO-dependent E3 ubiquitin ligase RNF4 for polyubiquitination and subsequent degradation. The SUMO E3 ligase PIAS3 promotes SUMOylation and polyubiquitination of NR4A1, while the SUMO protease SENP1 acts to de-conjugate SUMO. We demonstrate that this pathway is important for rapid degradation of NR4A1 after induced by stress. Moreover, we identify two SUMO modification sites in NR4A1 that are critical for maintaining low levels of NR4A1 expression. Mutation of these two NR4A1 SUMO modification sites enhances the stability of NR4A1. Importantly, we show that SUMOylation is critical in controlling NR4A1 function in inflammatory cytokine signaling and controlling macrophage cell death. SUMOylation and subsequent ubiquitination on NR4A1 mitigates its inhibition of innate immune signaling, such as TNF-α- and IL-1β-induced NF-κB activation. This mechanism of sequential SUMOylation and ubiquitination, which together control the degradation of NR4A1, could be exploited for the therapeutic treatment of diseases with NR4A1 involvement.

Curcumin as a multifaceted compound against human papilloma virus infection and cervical cancers: A review of chemistry, cellular, molecular, and preclinical features

Curcumin, the bioactive polyphenolic ingredient of turmeric, has been extensively studied for its effects on human papilloma virus (HPV) infection as well as primary and malignant squamous cervical cancers. HPV infections, especially those related to HPV 16 and 18 types, have been established as the leading cause of cervical cancer; however, there are also additional contributory factors involved in the etiopathogenesis of cervical cancers. Curcumin has emerged as having promising chemopreventive and anticancer effects against both HPV-related and nonrelated cervical cancers. In this review, we first discuss the biological relevance of curcumin and both its pharmacological effects and pharmaceutical considerations from a chemical point of view. Next, the signaling pathways that are modulated by curcumin and are relevant to the elimination of HPV infection and treatment of cervical cancer are discussed. We also present counter arguments regarding the effects of curcumin on signaling pathways and molecular markers dysregulated by benzo(a)pyrene (Bap), a carcinogen found in pathological cervical lesions of women who smoke frequently, and estradiol, as two important risk factors involved in persistent HPV-infection and cervical cancer. Finally, various strategies to enhance the pharmacological activity and pharmacokinetic characteristics of curcumin are discussed with examples of studies in experimental models of cervical cancer. © 2016 BioFactors, 43(3):331-346, 2017.

Thymoquinone inhibits the migration of mouse neuroblastoma (Neuro-2a) cells by down-regulating MMP-2 and MMP-9

Thymoquinone (TQ), an active component derived from the medial plant Nigella sativa, has been used for medical purposes for more than 2 000 years. Recent studies have reported that TQ blocked angiogenesis in animal model and reduced migration, adhesion, and invasion of glioblastoma cells. We have recently shown that TQ could exhibit a potent cytotoxic effect and induce apoptosis in mouse neuroblastoma (Neuro-2a) cells. In the present study, TQ treatment markedly decreased the adhesion and migration of Neuro-2a cells. TQ down-regulated MMP-2 and MMP-9 protein expression and mRNA levels and their activities. Furthermore, TQ significantly down-regulated the protein expression of transcription factor NF-κB (p65) but not significantly altered the expression of N-Myc. Taken together, our data indicated that TQ's inhibitory effect on the migration of Neuro-2a cells was mediated through the suppression of MMP-2 and MMP-9 expression, suggesting that TQ treatment can be a promising therapeutic strategy for human malignant neuroblastoma.

Early spatiotemporal-specific changes in intermediate signals are predictive of cytotoxic sensitivity to TNFα and co-treatments

Signaling pathways can generate different cellular responses to the same cytotoxic agents. Current quantitative models for predicting these differential responses are usually based on large numbers of intracellular gene products or signals at different levels of signaling cascades. Here, we report a study to predict cellular sensitivity to tumor necrosis factor alpha (TNFα) using high-throughput cellular imaging and machine-learning methods. We measured and compared 1170 protein phosphorylation events in a panel of human lung cancer cell lines based on different signals, subcellular regions, and time points within one hour of TNFα treatment. We found that two spatiotemporal-specific changes in an intermediate signaling protein, p90 ribosomal S6 kinase (RSK), are sufficient to predict the TNFα sensitivity of these cell lines. Our models could also predict the combined effects of TNFα and other kinase inhibitors, many of which are not known to target RSK directly. Therefore, early spatiotemporal-specific changes in intermediate signals are sufficient to represent the complex cellular responses to these perturbations. Our study provides a general framework for the development of rapid, signaling-based cytotoxicity screens that may be used to predict cellular sensitivity to a cytotoxic agent, or identify co-treatments that may sensitize or desensitize cells to the agent.

Inhibitor of Apoptosis Protein-1 Regulates Tumor Necrosis Factor-Mediated Destruction of Intestinal Epithelial Cells

BACKGROUND AND AIMS

Tumor necrosis factor (TNF) is a cytokine that promotes inflammation and contributes to pathogenesis of inflammatory bowel diseases. Unlike other cells and tissues, intestinal epithelial cells undergo rapid cell death upon exposure to TNF, by unclear mechanisms. We investigated the roles of inhibitor of apoptosis proteins (IAPs) in the regulation of TNF-induced cell death in the intestinal epithelium of mice and intestinal organoids.

METHODS

RNA from cell lines and tissues was analyzed by quantitative polymerase chain reaction, protein levels were analyzed by immunoblot assays. BIRC2 (also called cIAP1) was expressed upon induction from lentiviral vectors in young adult mouse colon (YAMC) cells. YAMC cells, the mouse colon carcinoma cell line MC38, the mouse macrophage cell line RAW 264.7, or mouse and human organoids were incubated with second mitochondrial activator of caspases (Smac)-mimetic compound LCL161 or recombinant TNF-like weak inducer of apoptosis (TNFSF12) along with TNF, and cell death was quantified. C57BL/6 mice with disruption of Xiap, Birc2 (encodes cIAP1), Birc3 (encodes cIAP2), Tnfrsf1a, or Tnfrsf1b (Tnfrsf1a and b encode TNF receptors) were injected with TNF or saline (control); liver and intestinal tissues were collected and analyzed for apoptosis induction by cleaved caspase 3 immunohistochemistry. We also measured levels of TNF and alanine aminotransferase in serum from mice.

RESULTS

YAMC cells, and mouse and human intestinal organoids, died rapidly in response to TNF. YAMC and intestinal crypts expressed lower levels of XIAP, cIAP1, cIAP2, and cFLIP than liver tissue. Smac-mimetics reduced levels of cIAP1 and XIAP in MC38 and YAMC cells, and Smac-mimetics and TNF-related weak inducer of apoptosis increased TNF-induced cell death in YAMC cells and organoids-most likely by sequestering and degrading cIAP1. Injection of TNF greatly increased levels of cell death in intestinal tissue of cIAP1-null mice, compared with wild-type C57BL/6 mice, cIAP2-null mice, or XIAP-null mice. Excessive TNF-induced cell death in the intestinal epithelium was mediated TNF receptor 1.

CONCLUSIONS

In a study of mouse and human cell lines, organoids, and tissues, we found cIAP1 to be required for regulation of TNF-induced intestinal epithelial cell death and survival. These findings have important implications for the pathogenesis of TNF-mediated enteropathies and chronic inflammatory diseases of the intestine.

ZGDHu-1 promotes apoptosis of mantle cell lymphoma cells

Mantle cell lymphoma (MCL) is a well-defined aggressive Non-Hodgkin-lymphoma with short survival rates and remains incurable to date. Previously, we demonstrated the antitumor activity of ZGDHu-1(N, N'-di-(m-methylphenyi)-3, 6-dimethyl-1, 4-dihydro-1, 2, 4, 5-tetrazine-1, 4-dicarboamide) in chronic lymphocytic leukemia. In this study, ZGDHu-1 shows potent anti-lymphoma activity in MCL cells. ZGDHu-1 significantly induces cell cycle G2/M phase arrest and apoptosis in MCL cells. ZGDHu-1 reduces the protein levels of Mcl-1, Bcl-XL and cyclin D1. Importantly, ZGDHu-1 inhibits TNFα-induced IkBa phosphorylation, p65 nuclear translocation and NF-kB downstream target gene expression in MCL cells. MCL samples expressing high levels of Bcl-2 and high Bcl-2/Bax ratios tend to be less effective to ZGDHu-1. Together, these results suggest that ZGDHu-1 could inhibit the NF-kB signaling pathway partly, which may lead to the suppression of cell proliferation and the induction of apoptosis in MCL cells. Thus, our studies provide evidence of the potential of ZGDHu-1 in treating mantle cell lymphoma.

SP110b Controls Host Immunity and Susceptibility to Tuberculosis

RATIONALE

How host genetic factors affect Mycobacterium tuberculosis (Mtb) infection outcomes remains largely unknown. SP110b, an IFN-induced nuclear protein, is the nearest human homologue to the mouse Ipr1 protein that has been shown to control host innate immunity to Mtb infection. However, the function(s) of SP110b remains unclear.

OBJECTIVES

To elucidate the role of SP110b in controlling host immunity and susceptibility to tuberculosis (TB), as well as to identify the fundamental immunological and molecular mechanisms affected by SP110b.

METHODS

Using cell-based approaches and mouse models of Mtb infection, we characterized the function(s) of SP110b/Ipr1. We also performed genetic characterization of patients with TB to investigate the role of SP110 in controlling host susceptibility to TB.

MEASUREMENTS AND MAIN RESULTS

SP110b modulates nuclear factor-κB (NF-κB) activity, resulting in downregulation of tumor necrosis factor-α (TNF-α) production and concomitant upregulation of NF-κB-induced antiapoptotic gene expression, thereby suppressing IFN-γ-mediated monocyte and/or macrophage cell death. After Mtb infection, TNF-α is also downregulated in Ipr1-expressing mice that have alleviated cell death, less severe necrotic lung lesions, more efficient Mtb growth control in the lungs, and longer survival. Moreover, genetic studies in patients suggest that SP110 plays a key role in modulating TB susceptibility in concert with NFκB1 and TNFα genes.

CONCLUSIONS

These results indicate that SP110b plays a crucial role in shaping the inflammatory milieu that supports host protection during infection by fine-tuning NF-κB activity, suggesting that SP110b may serve as a potential target for host-directed therapy aimed at manipulating host immunity against TB.

Targeting IKK and NF-κB for Therapy

In addition to regulating immune responses, the NF-κB family of transcription factors also promotes cellular proliferation and survival. NF-κB and its activating kinase, IKK, have become appealing therapeutic targets because of their critical roles in the progression of many diseases including chronic inflammation and cancer. Here, we discuss the conditions that lead to pathway activation, the effects of constitutive activation, and some of the strategies used to inhibit NF-κB signaling.

Epigallocatechin-3-gallate attenuates cerebral cortex damage and promotes brain regeneration in acrylamide-treated rats

ACR increased the rate of nestin-positive cells implying that ACR caused cell damage, and EGCG decreased the rates of nestin-positive cells against ACR suggesting that EGCG may promote cell regeneration.

The DNA Damage Response in Neurons: Die by Apoptosis or Survive in a Senescence-Like State?

Neurons are exposed to high levels of DNA damage from both physiological and pathological sources. Neurons are post-mitotic and their loss cannot be easily recovered from; to cope with DNA damage a complex pathway called the DNA damage response (DDR) has evolved. This recognizes the damage, and through kinases such as ataxia-telangiectasia mutated (ATM) recruits and activates downstream factors that mediate either apoptosis or survival. This choice between these opposing outcomes integrates many inputs primarily through a number of key cross-road proteins, including ATM, p53, and p21. Evidence of re-entry into the cell-cycle by neurons can be seen in aging and diseases such as Alzheimer's disease. This aberrant cell-cycle re-entry is lethal and can lead to the apoptotic death of the neuron. Many downstream factors of the DDR promote cell-cycle arrest in response to damage and appear to protect neurons from apoptotic death. However, neurons surviving with a persistently activated DDR show all the features known from cell senescence; including metabolic dysregulation, mitochondrial dysfunction, and the hyper-production of pro-oxidant, pro-inflammatory and matrix-remodeling factors. These cells, termed senescence-like neurons, can negatively influence the extracellular environment and may promote induction of the same phenotype in surrounding cells, as well as driving aging and age-related diseases. Recently developed interventions targeting the DDR and/or the senescent phenotype in a range of non-neuronal tissues are being reviewed as they might become of therapeutic interest in neurodegenerative diseases.

Influence of Quercetin in the Temporal Regulation of Redox Homeostasis in Drosophila melanogaster

Numerous biological processes are governed by the biological clock. Studies using Drosophila melanogaster (L.) are valuable that could be of importance for their effective applications on rodent studies. In this study, the beneficial role of quercetin (a flavonoid) on H2O2 induced stress in D. melanogaster was investigated. D. melanogaster flies were divided into four groups (group I - control, group II - H2O2 (acute exposure), group III - quercetin, and group IV - quercetin + H2O2 treated). Negative geotaxis assay, oxidative stress indicators (protein carbonyls, thiobarbituric reactive substances [TBARS]), and antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione-S-transferase [GST], glutathione peroxidase, and reduced glutathione [GSH]) were measured at 4 h intervals over 24 h and temporal expression of heat shock protein-70 (Hsp70), Upd1 (homolog of IL-6 in Drosophila), and nitric oxide synthase (Nos) was analyzed by Western blotting. Groups II and IV showed altered biochemical rhythms (compared with controls). Decreased mesor values of negative geotaxis, SOD, CAT, GST, and GSH were noticed in H2O2, increased mesor of oxidative stress indicators (TBARS and protein carbonyl content) and a reversibility of the rhythmic characteristics were conspicuous after quercetin treatment. The expression levels of Hsp70, Upd1, and Nos were noticeably maximum at 04:00. Significant elevation of expression by H2O2 was nearly normalized by quercetin treatment. The possible mechanism by which quercetin modulates oxidant-antioxidant imbalance under oxidative stress could be ascribed to the modulation of the rhythmic properties. Our results will be helpful to understand the molecular interlink between circadian rhythm and oxidative stress mechanism.

NF-κB Protection against Apoptosis Induced by HEMA

The cytotoxicity of dental monomers has been widely investigated, but the underlying mechanisms have not been elucidated. We studied the molecular mechanisms involved in cell death induced by HEMA. In human primary fibroblasts, HEMA induced a dose-dependent apoptosis that was confirmed by the activation of caspases-8, -9, and -3. We found an increase of reactive oxygen species (ROS) and NF-κB activation after HEMA exposure. Blocking of ROS production by anti-oxidants had no direct influence on apoptosis caused by HEMA, but inhibition of NF-κB increased the fraction of apoptotic cells. Accordingly, mouse embryonic fibroblasts (MEF) from p65−/− mice were more susceptible to HEMA-induced apoptosis than were wild-type controls. Our results indicate that exposure to HEMA triggers apoptosis and that this mechanism is not directly dependent upon redox signaling. Nevertheless, ROS induction by HEMA activates NF-κB, which exerts a protective role in counteracting apoptosis.

Prevention of Spontaneous and Experimentally Induced Diabetes in Mice with Zinc Sulfate-Enriched Drinking Water is Associated with Activation and Reduction of NF-κB and AP-1 in Islets, Respectively

Recently, we reported that zinc sulfate-enriched (25 mM) drinking water (Zn2+) protected male C57BL/6 mice from diabetes induced by multiple low doses of streptozotocin (MLD-STZ) and that MLD-STZ activates the transcription factors nuclear factor (NF)-κB and activator protein (AP)-1 in islets of these mice. Therefore, we studied the effect of Zn2+ on spontaneous diabetes in female nonobese diabetic (NOD) mice and on the activity of NF-κB and AP-1 in islets of NOD and MLD-STZ–injected male C57BL/6 mice. We hypothesized that Zn2+ may affect NF-κB, which may play a key role in immune-mediated diabetogenesis. Here we continuously administered Zn2+ to NOD mice, to both parents and their F1 offspring, and treated C57BL/6 male mice with MLD-STZ either alone or in addition to Zn2+. We assessed effects of Zn2+ on insulitis and peri-insulitis in 8-week-old NOD mice and analyzed NF-κB and AP-1 activities in islets. Zn2+ significantly prevented diabetes in female F1 offspring and significantly reduced insulitis and peri-insulitis. Zn2+ significantly stimulated NF-κB and AP-1 activation in NOD mice, in contrast, in C57BL/6 mice, Zn2+ significantly reduced their activation by MLD-STZ. These data demonstrate that NF-κB may play a critical role in immune-mediated diabetes. Depending on the mode of β-cell destruction, Zn2+ may prevent apoptosis through activation of NF-κB in NOD mice or prevent inflammatory immune destruction through inhibition of NF-κB in MLD-STZ-treated C57BL/6 mice.

Role of the HTLV-1 viral factors in the induction of apoptosis

Adult T-cell leukemia (ATL) and HTLV-1-associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) are the two main diseases that are caused by the HTLV-1 virus. One of the features of HTLV-1 infection is its resistance against programmed cell death, which maintains the survival of cells to oncogenic transformation and underlies the viruses' therapeutic resistance. Two main genes by which the virus develops cancer are Tax and HBZ; playing an essential role in angiogenesis in regulating viral transcription and modulating multiple host factors as well as apoptosis pathways. Here we have reviewed by prior research how the apoptosis pathways are suppressed by the Tax and HBZ and new drugs which have been designed to deal with this suppression.

IAP antagonists induce anti-tumor immunity in multiple myeloma

The cellular inhibitors of apoptosis (cIAP) 1 and 2 are amplified in about 3% of cancers and have been identified in multiple malignancies as being potential therapeutic targets as a result of their role in the evasion of apoptosis. Consequently, small-molecule IAP antagonists, such as LCL161, have entered clinical trials for their ability to induce tumor necrosis factor (TNF)-mediated apoptosis of cancer cells. However, cIAP1 and cIAP2 are recurrently homozygously deleted in multiple myeloma (MM), resulting in constitutive activation of the noncanonical nuclear factor (NF)-κB pathway. To our surprise, we observed robust in vivo anti-myeloma activity of LCL161 in a transgenic myeloma mouse model and in patients with relapsed-refractory MM, where the addition of cyclophosphamide resulted in a median progression-free-survival of 10 months. This effect was not a result of direct induction of tumor cell death, but rather of upregulation of tumor-cell-autonomous type I interferon (IFN) signaling and a strong inflammatory response that resulted in the activation of macrophages and dendritic cells, leading to phagocytosis of tumor cells. Treatment of a MM mouse model with LCL161 established long-term anti-tumor protection and induced regression in a fraction of the mice. Notably, combination of LCL161 with the immune-checkpoint inhibitor anti-PD1 was curative in all of the treated mice.

Suppression of LASP-1 attenuates the carcinogenesis of prostatic cancer cell lines: Key role of the NF-κB pathway

Prostate cancer (PCa) is one of the most frequently diagnosed cancers among males worldwide and causes a considerable number of deaths each year. One of the newly explored targets for the development of therapies against PCa is LIM and SH3 protein 1 (LASP-1). In the present study, the function of LASP-1 in the oncogenesis and metastasis of PCa was investigated using a series of in vitro experiments. Moreover, the mechanism through which LASP-1 exerted its effect on the carcinogenesis of PCa was also explored. The expression levels of LASP-1 in clinical PCa specimens were determined both at the mRNA and protein levels. Afterwards, the activity of LASP-1 in human PCa cell lines PC3 and DU145 was inhibited using a short hairpin RNA (shRNA) interfering method. The effects of LASP-1 knockdown on the cell growth, apoptosis, cell cycle distribution, migration and invasion were assessed. It was demonstrated that the expression of LASP-1 was significantly higher in the clinical PCa tissues than the level in the corresponding para-carcinoma tissues. Following the knockdown of the LASP-1 gene in human PCa cell lines, the viability, migration and invasion of the cancer cells were decreased. It was also demonstrated that the change in the cell viability and motile ability were associated with an induction of cell apoptosis and G1 phase cell cycle arrest. Based on the results of the detection of the expression of NF-κB-related factors, it was indicated that LASP-1 may affect the carcinogenesis of PCa through a NF-κB inhibition-dependent manner. Although the detailed explanation of the mechanism of LASP-1 in the carcinogenesis of PCa requires further elucidation, the present study highlights the potential of LASP-1 as a promising therapeutic target to ameliorate the oncogenesis and metastasis of PCa.

Diosmetin triggers cell apoptosis by activation of the p53/Bcl-2 pathway and inactivation of the Notch3/NF-κB pathway in HepG2 cells

Diosmetin (DIOS), a flavonoid compound, is abundant in Citrus limon. Emerging studies have shown that DIOS is an effective compound implicated in multiple types of cancer. However, whether DIOS serves a role in hepatocellular carcinoma (HCC) is still obscure. HepG2 cells were used in the present study, and it was observed that DIOS exhibited antitumor activity against liver cancer cells. Western blotting was performed to evaluate cell apoptosis and survival-associated proteins, and the results demonstrated that DIOS treatment resulted in the activation of the p53-dependent apoptosis pathway. Our results revealed that DIOS caused inhibition of the nuclear factor (NF)-κB signaling pathway and downregulation of Notch3 receptor. Furthermore, by using small hairpin RNA-Notch3, it was confirmed that DIOS inhibited the NF-κB signaling pathway by inactivation of Notch3. In conclusion, the present results demonstrated that DIOS triggered cell apoptosis by activation of the p53 signaling pathway and inhibited the NF-κB cell survival pathway by downregulation of Notch3 receptor expression. DIOS is a potential agent for prevention of HCC.

Krabbe's leukodystrophy: Approaches and models in vitro

This Review describes some in vitro approaches used to investigate the mechanisms involved in Krabbe's disease, with particular regard to the cellular systems employed to study processes of inflammation, apoptosis, and angiogenesis. The aim was to update the knowledge on the results obtained from in vitro models of this neurodegenerative disorder and provide stimuli for future research. For a long time, the nonavailability of established neural cells has limited the understanding of neuropathogenic mechanisms in Krabbe's leukodystrophy. More recently, the development of new Krabbe's disease cell models has allowed the identification of neurologically relevant pathogenic cascades, including the major role of elevated psychosine levels. Thus, direct and/or indirect roles of psychosine in the release of cytokines, reactive oxygen species, and nitric oxide and in the activation of kinases, caspases, and angiogenic factors results should be clearer. In parallel, it is now understood that the presence of globoid cells precedes oligodendrocyte apoptosis and demyelination. The information described here will help to continue the research on Krabbe's leukodystrophy and on potential new therapeutic approaches for this disease that even today, despite numerous attempts, is without cure. © 2016 Wiley Periodicals, Inc.

E1A enhances cellular sensitivity to DNA-damage-induced apoptosis through PIDD-dependent caspase-2 activation

Expression of the adenoviral protein, E1A, sensitizes mammalian cells to a wide variety of apoptosis-inducing agents through multiple cellular pathways. For example, E1A sensitizes cells to apoptosis induced by TNF-superfamily members by inhibiting NF-kappa B (NF-κB)-dependent gene expression. In contrast, E1A sensitization to nitric oxide, an inducer of the intrinsic apoptotic pathway, is not dependent upon repression of NF-κB-dependent transcription but rather is dependent upon caspase-2 activation. The latter observation suggested that E1A-induced enhancement of caspase-2 activation might be a critical factor in cellular sensitization to other intrinsic apoptosis pathway-inducing agents. Etoposide and gemcitabine are two DNA damaging agents that induce intrinsic apoptosis. Here we report that E1A-induced sensitization to both of these agents, like NO, is independent of NF-κB activation but dependent on caspase-2 activation. The results show that caspase-2 is a key mitochondrial-injuring caspase during etoposide and gemcitabine-induced apoptosis of E1A-positive cells, and that caspase-2 is required for induction of caspase-3 activity by both chemotherapeutic agents. Expression of PIDD was required for caspase-2 activation, mitochondrial injury and enhanced apoptotic cell death. Furthermore, E1A-enhanced sensitivity to injury-induced apoptosis required PIDD cleavage to PIDD-CC. These results define the PIDD/caspase-2 pathway as a key apical, mitochondrial-injuring mechanism in E1A-induced sensitivity of mammalian cells to chemotherapeutic agents.