Pro-apoptotic role of NF-kappaB: implications for cancer therapy

Combinatory Nanovesicle with siRNA-Loaded Extracellular Vesicle and IGF-1 for Osteoarthritis Treatments

Extracellular vesicles (EVs) have been found to have the characteristics of their parent cells. Based on the characteristics of these EVs, various studies on disease treatment using mesenchymal stem cell (MSC)-derived EVs with regenerative activity have been actively conducted. The therapeutic nature of MSC-derived EVs has been shown in several studies, but in recent years, there have been many efforts to functionalize EVs to give them more potent therapeutic effects. Strategies for functionalizing EVs include endogenous and exogenous methods. In this study, human umbilical cord MSC (UCMSC)-derived EVs were selected for optimum OA treatments with expectation via bioinformatics analysis based on antibody array. And we created a novel nanovesicle system called the IGF-si-EV, which has the properties of both cartilage regeneration and long-term retention in the lesion site, attaching positively charged insulin-like growth factor-1 (IGF-1) to the surface of the UCMSC-derived Evs carrying siRNA, which inhibits MMP13. The downregulation of inflammation-related cytokine (MMP13, NF-kB, and IL-6) and the upregulation of cartilage-regeneration-related factors (Col2, Acan) were achieved with IGF-si-EV. Moreover, the ability of IGF-si-EV to remain in the lesion site for a long time has been proven through an ex vivo system. Collectively, the final constructed IGF-si-EV can be proposed as an effective OA treatment through its successful MMP13 inhibition, chondroprotective effect, and cartilage adhesion ability. We also believe that this EV-based nanoparticle-manufacturing technology can be applied as a platform technology for various diseases.

Sam68 is a druggable vulnerability point in cancer stem cells

Sam68 (Src associated in mitosis of 68 kDa) is an RNA-binding and multifunctional protein extensively characterized in numerous cellular functions, such as RNA processing, cell cycle regulation, kinase- and growth factor signaling. Recent investigations highlighted Sam68 as a primary target of a class of reverse-turn peptidomimetic drugs, initially developed as inhibitors of Wnt/β-catenin mediated transcription. Further investigations on such compounds revealed their capacity to selectively eliminate cancer stem cell (CSC) activity upon engaging Sam68. This work highlighted previously unappreciated roles for Sam68 in the maintenance of neoplastic self-renewal and tumor-initiating functions. Here, we discuss the implication of Sam68 in tumorigenesis, where central findings support its contribution to chromatin regulation processes essential to CSCs. We also review advances in CSC-targeting drug discovery aiming to modulate Sam68 cellular distribution and protein-protein interactions. Ultimately, Sam68 constitutes a vulnerability point of CSCs and an attractive therapeutic target to impede neoplastic stemness in human tumors.

Potent Suppression of Prostate Cancer Cell Growth and Eradication of Cancer Stem Cells by CD44-targeted Nanoliposome-quercetin Nanoparticles

The bioavailability of quercetin, a natural compound, is hindered by low solubility, limited absorption, and restricted systemic availability. Therefore, encapsulating it in biocompatible nanoparticles presents a promising solution. This study aimed to target prostate cancer stem cells (CSCs) overexpressing CD44+ receptors as well as cancer cells, employing quercetin-loaded hyaluronic acid-modified nanoliposomes (LP-Quer-HA). Synthesized via a green ethanol injection method, these nanoliposomes had an average diameter of 134 nm and an impressive loading efficiency of 96.9%. Human prostate cancer cells were treated with either 10 μM of free quercetin or the same concentration delivered by LP-Quer-HA for 72 hours. Free quercetin reduced androgen-resistant PC3 cell viability by 16%, while LP-Quer-HA significantly increased cell death to 60%. It induced apoptosis, upregulating cytochrome c, Bax, caspases 3 and 8, and downregulating survivin and Bcl-2 expression. Compared to free quercetin, LP-Quer-HA upregulated E-cadherin expression while inhibiting cell migration and reducing the expression of fibronectin, N-cadherin, and MMP9. Treatment of PC3 cell tumor spheroids with LP-Quer-HA decreased the number of CD44 cells and expression of CD44, Oct3/4 and Wnt. Moreover, LP-Quer-HA inhibited p-ERK expression while increasing p38/MAPK and NF-κB protein expression. In androgen-sensitive LNCaP cells, LP-Quer-HA efficacy was notable, reducing cell viability from 10% to 52% compared to free quercetin. Utilizing HA-modified nanoliposomes as a quercetin delivery system enhanced its potency at lower concentrations, reducing the CD44+ cell population and effectively impeding prostate cancer cell proliferation and migration. These findings underscore the potential of quercetin-loaded cationic nanoliposomes as a robust therapeutic approach.

miRNA-214-3p stimulates carcinogen-induced mammary epithelial cell apoptosis in mammary cancer-resistant species

Mammary cancer incidence varies greatly across species and underlying mechanisms remain elusive. We previously showed that mammosphere-derived epithelial cells from species with low mammary cancer incidence, such as horses, respond to carcinogen 7, 12-Dimethylbenz(a)anthracene-induced DNA damage by undergoing apoptosis, a postulated anti-cancer mechanism. Additionally, we found that miR-214-3p expression in mammosphere-derived epithelial cells is lower in mammary cancer-resistant as compared to mammary cancer-susceptible species. Here we show that increasing miR-214 expression and decreasing expression of its target gene nuclear factor kappa B subunit 1 in mammosphere-derived epithelial cells from horses abolishes 7,12-Dimethylbenz(a)anthracene-induced apoptosis. A direct interaction of miR-214-3p with another target gene, unc-5 netrin receptor A, is also demonstrated. We propose that relatively low levels of miR-214 in mammosphere-derived epithelial cells from mammals with low mammary cancer incidence, allow for constitutive gene nuclear factor kappa B subunit 1 expression and apoptosis in response to 7, 12-Dimethylbenz(a)anthracene. Better understanding of the mechanisms regulating cellular responses to carcinogens improves our overall understanding of mammary cancer resistance mechanisms.

Rel-A/PACER/miR 7 Axis May Play a Role in Radiotherapy Treatment in Breast Cancer Patients

Background

Radiotherapy has become the standard form of treatment for breast cancer (BC). Radioresistance is an issue that limits the effectiveness of radiotherapy (RT). Therefore, predictive biomarkers are needed to choose the appropriate RT for the patient. Activation of the proinflammatory transcription factor, nuclear factor-kappa B (NF-κB), is a frequently noted pathway in BC. Investigating the relationship between RT and alterations in gene expression involved in the immune pathway can help better control the disease. This research investigated the impact of RT on the expression levels of Rel-A, PACER, and miR-7 within the NF-κB signaling pathway.

Methods

Blood samples (n = 15) were obtained from BC patients during four different time intervals: 72 hours prior to initiating RT, as well as one, two, and four weeks following RT completion. Samples were also collected from 20 healthy women who had no immune or cancer-related diseases. Blood RNA was extracted, and complementary DNA was synthesized. Gene expression level was determined using R real-time polymerase chain reaction (RT-PCR).

Results

There was a significant difference in the expression level of Rel-A between patients and normal individual blood samples (p < 0.05). After four weeks of RT, qRT-PCR revealed a significant downregulation of miR-7 and upregulation of Rel-A and PACER in BC patients. Also, there was a significant association between Rel-A expression and monocyte numbers during RT (p < 0.001).

Conclusion

The expression level of PACER, miR-7 and Rel-A, changed after RT; therefore, these genes could be used as diagnostic and therapeutic RT markers in BC.

Bolstering the secretion and bioactivities of umbilical cord MSC-derived extracellular vesicles with 3D culture and priming in chemically defined media

Human mesenchymal stem cells (hMSCs)-derived extracellular vesicles (EVs) have been known to possess the features of the origin cell with nano size and have shown therapeutic potentials for regenerative medicine in recent studies as alternatives for cell-based therapies. However, extremely low production yield, unknown effects derived from serum impurities, and relatively low bioactivities on doses must be overcome for translational applications. As several reports have demonstrated the tunability of secretion and bioactivities of EVs, herein, we introduced three-dimensional (3D) culture and cell priming approaches for MSCs in serum-free chemically defined media to exclude side effects from serum-derived impurities. Aggregates (spheroids) with 3D culture dramatically enhanced secretion of EVs about 6.7 times more than cells with two-dimensional (2D) culture, and altered surface compositions. Further modulation with cell priming with the combination of TNF-α and IFN-γ (TI) facilitated the production of EVs about 1.4 times more than cells without priming (9.4 times more than cells with 2D culture without priming), and bioactivities of EVs related to tissue regenerations. Interestingly, unlike changing 2D to 3D culture, TI priming altered internal cytokines of MSC-derived EVs. Through simulating characteristics of EVs with bioinformatics analysis, the regeneration-relative properties such as angiogenesis, wound healing, anti-inflammation, anti-apoptosis, and anti-fibrosis, for three different types of EVs were comparatively analyzed using cell-based assays. The present study demonstrated that a combinatory strategy, 3D cultures and priming MSCs in chemically defined media, provided the optimum environments to maximize secretion and regeneration-related bioactivities of MSC-derived EVs without impurities for future translational applications.

Apoptotic caspase inhibits innate immune signaling by cleaving NF-κBs in both Mammals and Flies

Host organisms use different innate immune mechanisms to defend against pathogenic infections, while tight control of innate immunity is essential for proper immune induction and balance. Here, we reported that apoptotic induction or caspase-3 overexpression caused dramatic reduction of differently triggered cytokine signalings in human cells, murine primary cells and mouse model, while the loss of caspase-3 or inhibiting apoptosis markedly enhances these immune signalings. Furthermore, caspase-3 can mediate the cleavage of NF-κB members p65/RelA, RelB, and c-Rel via its protease activity. And the caspase-3-resistant p65/RelA, RelB, or c-Rel mutant mostly restored the caspase-3-induced suppression of cytokine production. Interestingly, we further uncovered that apoptotic induction also dramatically inhibited Toll immune signaling in Drosophila, and the Drosophila effector caspases, drICE and DCP-1, also mediated the degradation of DIF, the NF-κB of Toll signaling. Together, our findings demonstrate apoptotic effector caspases, including mammalian caspase-3 and fly drICE/DCP-1, can function as repressors of NF-κB-mediated innate immune signalings.

AKF-D52, a Synthetic Phenoxypyrimidine-Urea Derivative, Triggers Extrinsic/Intrinsic Apoptosis and Cytoprotective Autophagy in Human Non-Small Cell Lung Cancer Cells

Simple Summary

We previously reported the antiproliferative effects of a phenoxypyridine urea derivative. In this study, we aimed to investigate the antiproliferative effects of 1-(3,5-dimethoxyphenyl)-3-(4-(3-methoxyphenoxy)-2-((4-morpholinophenyl)amino)pyrimidin-5-yl)urea (AKF-D52) in non-small cell lung cancer cells. We found that (i) AKF-D52 induces apoptosis in caspase-dependent and caspase-independent pathways; (ii) AKF-D52-induced apoptosis is caused by the clustering of a death-inducing signaling complex and mitochondrial-dependent signaling; (iii) AKF-D52 induces cytoprotective autophagy, and pre-treatment with an autophagy inhibitor enhances the apoptotic effect of AKF-D52; and (iv) AKF-D52-induced apoptosis and autophagy are attenuated by the reactive oxygen species (ROS) scavenger α-tocopherol. Furthermore, AKF-D52 suppressed tumor growth in a xenograft mouse model. Collectively, our findings regarding the efficacy and molecular mechanisms of AKF-D52 identify this compound as a potential therapeutic agent for the treatment of lung cancer.

Abstract

Previously, we discovered that 1-(3,5-dimethoxyphenyl)-3-(4-(3-methoxyphenoxy)-2-((4-morpholinophenyl)amino)pyrimidin-5-yl)urea (AKF-D52), a synthetic phenoxypyrimidine urea derivative, acts as a growth inhibitor of various cancer cell types. In this study, we elucidated the antiproliferative properties of AFK-D52 and underlying mechanisms in non-small cell lung cancer (NSCLC) cells and an A549 xenograft animal model. AKF-D52 was found to induce both caspase-dependent and -independent apoptotic cell death. Furthermore, the mitochondrial component of the AKF-D52-induced apoptosis mechanism involves a reduction in mitochondrial membrane potential and regulation in B cell lymphoma-2 family protein expression. Moreover, AKF-D52 activates the extrinsic pathway through up-regulated expression of death receptor 3 and Fas and then the formation of a death-inducing signaling complex. AKF-D52 also induced autophagy by increasing acidic vesicular organelle formation and microtubule-associated protein 1A/1B-light chain 3-II levels and reducing p62 levels. Notably, pretreatment with autophagy inhibitors enhanced AKF-D52-induced cell death, indicating that the induced autophagy is cytoprotective. AKF-D52 treatment also triggered reactive oxygen species (ROS) production in NSCLC cells, whereas the antioxidant α-tocopherol abolished AKF-D52-induced cell death. In a xenograft lung cancer mouse model, AKF-D52 administration attenuated tumor growth by inducing apoptosis and autophagy in tumor tissues. Collectively, our data indicate that AKF-D52-induced ROS production plays a role in mediating apoptosis and cytoprotective autophagy in NSCLC.

Running With Scissors: Evolutionary Conflicts Between Viral Proteases and the Host Immune System

Many pathogens encode proteases that serve to antagonize the host immune system. In particular, viruses with a positive-sense single-stranded RNA genome [(+)ssRNA], including picornaviruses, flaviviruses, and coronaviruses, encode proteases that are not only required for processing viral polyproteins into functional units but also manipulate crucial host cellular processes through their proteolytic activity. Because these proteases must cleave numerous polyprotein sites as well as diverse host targets, evolution of these viral proteases is expected to be highly constrained. However, despite this strong evolutionary constraint, mounting evidence suggests that viral proteases such as picornavirus 3C, flavivirus NS3, and coronavirus 3CL, are engaged in molecular ‘arms races’ with their targeted host factors, resulting in host- and virus-specific determinants of protease cleavage. In cases where protease-mediated cleavage results in host immune inactivation, recurrent host gene evolution can result in avoidance of cleavage by viral proteases. In other cases, such as recently described examples in NLRP1 and CARD8, hosts have evolved ‘tripwire’ sequences that mimic protease cleavage sites and activate an immune response upon cleavage. In both cases, host evolution may be responsible for driving viral protease evolution, helping explain why viral proteases and polyprotein sites are divergent among related viruses despite such strong evolutionary constraint. Importantly, these evolutionary conflicts result in diverse protease-host interactions even within closely related host and viral species, thereby contributing to host range, zoonotic potential, and pathogenicity of viral infection. Such examples highlight the importance of examining viral protease-host interactions through an evolutionary lens.

HER2 Signaling in Breast Cancer

HER2 gene amplification occurs in many breast cancer patients and is associated with poor clinical prognosis. Trastuzumab is a therapeutic monoclonal antibody binding to HER2 and inhibits growth of HER2-positive breast cancer cells and used as a principal treatment for HER2-positive breast cancer. Unfortunately, some HER2-positive breast cancers eventually relapse after trastuzumab treatment. To investigate the molecular mechanism of trastuzumab resistance, we generated trastuzumab-resistant cells using a mouse model and found ECM1 protein is increased in trastuzumab-resistant cells. ECM1 was shown to increase EGFR signaling via upregulated matrix metalloproteinase 9/galectin-3/mucin pathway. To further find the novel mediators of HER2-driven signaling pathways in breast cancer, we investigated the upregulated proteins in HER2-overexpressing breast cancer cells using a proteomics approach and found that KRT19 is strongly upregulated in HER2-positive breast cancer cells and it activates HER2 signaling by binding to HER2 and stabilizes the receptor on the cell membrane. Moreover, we found that treatment of KRT19 antibody resulted in reduced cell viability of trastuzumab-resistant HER2-positive breast cancer cells as well as trastuzumab-sensitive cancer cells both in vitro and in vivo.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

Drosophila ELYS regulates Dorsal dynamics during development

Embryonic large molecule derived from yolk sac (ELYS) is a constituent protein of nuclear pores. It initiates assembly of nuclear pore complexes into functional nuclear pores toward the end of mitosis. Using cellular, molecular, and genetic tools, including fluorescence and Electron microscopy, quantitative PCR, and RNAi-mediated depletion, we report here that the ELYS ortholog (dElys) plays critical roles during Drosophila development. dElys localized to the nuclear rim in interphase cells, but during mitosis it was absent from kinetochores and enveloped chromatin. We observed that RNAi-mediated dElys depletion leads to aberrant development and, at the cellular level, to defects in the nuclear pore and nuclear lamina assembly. Further genetic analyses indicated that dElys depletion re-activates the Dorsal (NF-κB) pathway during late larval stages. Re-activated Dorsal caused untimely expression of the Dorsal target genes in the post-embryonic stages. We also demonstrate that activated Dorsal triggers apoptosis during later developmental stages by up-regulating the pro-apoptotic genes reaper and hid The apoptosis induced by Reaper and Hid was probably the underlying cause for developmental abnormalities observed upon dElys depletion. Moreover, we noted that dElys has conserved structural features, but contains a noncanonical AT-hook-like motif through which it strongly binds to DNA. Together, our results uncover a novel epistatic interaction that regulates Dorsal dynamics by dElys during development.

Synthetic lethality between VPS4A and VPS4B triggers an inflammatory response in colorectal cancer

Somatic copy number alterations play a critical role in oncogenesis. Loss of chromosomal regions containing tumor suppressors can lead to collateral deletion of passenger genes. This can be exploited therapeutically if synthetic lethal partners of such passenger genes are known and represent druggable targets. Here, we report that VPS4B gene, encoding an ATPase involved in ESCRT‐dependent membrane remodeling, is such a passenger gene frequently deleted in many cancer types, notably in colorectal cancer (CRC). We observed downregulation of VPS4B mRNA and protein levels from CRC patient samples. We identified VPS4A paralog as a synthetic lethal interactor for VPS4B in vitro and in mouse xenografts. Depleting both proteins profoundly altered the cellular transcriptome and induced cell death accompanied by the release of immunomodulatory molecules that mediate inflammatory and anti‐tumor responses. Our results identify a pair of novel druggable targets for personalized oncology and provide a rationale to develop VPS4 inhibitors for precision therapy of VPS4B‐deficient cancers.

Macrophage autophagy regulates mitochondria-mediated apoptosis and inhibits necrotic core formation in vulnerable plaques

The vulnerable plaque is a key distinguishing feature of atherosclerotic lesions that can cause acute atherothrombotic vascular disease. This study was designed to explore the effect of autophagy on mitochondria-mediated macrophage apoptosis and vulnerable plaques. Here, we generated the mouse model of vulnerable carotid plaque in ApoE^-/- mice. Application of ApoE^-/- mice with rapamycin (an autophagy inducer) inhibited necrotic core formation in vulnerable plaques by decreasing macrophage apoptosis. However, 3-methyladenine (an autophagy inhibitor) promoted plaque vulnerability through deteriorating these indexes. To further explore the mechanism of autophagy on macrophage apoptosis, we used macrophage apoptosis model in vitro and found that 7-ketocholesterol (7-KC, one of the primary oxysterols in oxLDL) caused macrophage apoptosis with concomitant impairment of mitochondria, characterized by the impairment of mitochondrial ultrastructure, cytochrome c release, mitochondrial potential dissipation, mitochondrial fragmentation, excessive ROS generation and both caspase-9 and caspase-3 activation. Interestingly, such mitochondrial apoptotic responses were ameliorated by autophagy activator, but exacerbated by autophagy inhibitor. Finally, we found that MAPK-NF-κB signalling pathway was involved in autophagy modulation of 7-KC-induced macrophage apoptosis. So, we provide strong evidence for the potential therapeutic benefit of macrophage autophagy in regulating mitochondria-mediated apoptosis and inhibiting necrotic core formation in vulnerable plaques.

Silver Nanoparticles Potentiates Cytotoxicity and Apoptotic Potential of Camptothecin in Human Cervical Cancer Cells

Silver nanoparticles (AgNPs) are widely used metal nanoparticles in health care industries, particularly due to its unique physical, chemical, optical, and biological properties. It is used as an antibacterial, antiviral, antifungal, and anticancer agent. Camptothecin (CPT) and its derivatives function as inhibitors of topoisomerase and as potent anticancer agents against a variety of cancers. Nevertheless, the combined actions of CPT and AgNPs in apoptosis in human cervical cancer cells (HeLa) have not been elucidated. Hence, we investigated the synergistic combinatorial effect of CPT and AgNPs in human cervical cancer cells. We synthesized AgNPs using sinigrin as a reducing and stabilizing agent. The synthesized AgNPs were characterized using various analytical techniques. The anticancer effects of a combined treatment with CPT and AgNPs were evaluated using a series of cellular and biochemical assays. The expression of pro- and antiapoptotic genes was measured using real-time reverse transcription polymerase chain reaction. The findings from this study revealed that the combination of CPT and AgNPs treatment significantly inhibited cell viability and proliferation of HeLa cells. Moreover, the combination effect significantly increases the levels of oxidative stress markers and decreases antioxidative stress markers compared to single treatment. Further, the combined treatment upregulate various proapoptotic gene expression and downregulate antiapoptotic gene expression. Interestingly, the combined treatment modulates various cellular signaling molecules involved in cell survival, cytotoxicity, and apoptosis. Overall, these results suggest that CPT and AgNPs cause cell death by inducing the mitochondrial membrane permeability change and activation of caspase 9, 6, and 3. The synergistic cytotoxicity and apoptosis effect seems to be associated with increased ROS formation and depletion of antioxidant. Certainly, a combination of CPT and AgNPs could provide a beneficial effect in the treatment of cervical cancer compared with monotherapy.

Crosstalk between NF-κB and Nucleoli in the Regulation of Cellular Homeostasis

Nucleoli are emerging as key sensors of cellular stress and regulators of the downstream consequences on proliferation, metabolism, senescence, and apoptosis. NF-κB signalling is activated in response to a similar plethora of stresses, which leads to modulation of cell growth and death programs. While nucleolar and NF-κB pathways are distinct, it is increasingly apparent that they converge at multiple levels. Exposure of cells to certain insults causes a specific type of nucleolar stress that is characterised by degradation of the PolI complex component, TIF-IA, and increased nucleolar size. Recent studies have shown that this atypical nucleolar stress lies upstream of cytosolic IκB degradation and NF-κB nuclear translocation. Under these stress conditions, the RelA component of NF-κB accumulates within functionally altered nucleoli to trigger a nucleophosmin dependent, apoptotic pathway. In this review, we will discuss these points of crosstalk and their relevance to anti-tumour mechanism of aspirin and small molecule CDK4 inhibitors. We will also briefly the discuss how crosstalk between nucleoli and NF-κB signalling may be more broadly relevant to the regulation of cellular homeostasis and how it may be exploited for therapeutic purpose.

XAF1 forms a positive feedback loop with IRF-1 to drive apoptotic stress response and suppress tumorigenesis

X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a proapoptotic tumor suppressor that is frequently inactivated in multiple human cancers. However, the molecular basis for the XAF1-mediated growth inhibition remains largely undefined. Here, we report that XAF1 forms a positive feedback loop with interferon regulatory factor-1 (IRF-1) and functions as a transcriptional coactivator of IRF-1 to suppress tumorigenesis. Under various stressful conditions, XAF1 transcription is activated by IRF-1, and elevated XAF1 stabilizes and activates IRF-1. Mechanistically, XAF1 binds to the multifunctional domain 2 of IRF-1 via the zinc finger domain 6, thereby hindering C-terminus of Hsc70-interacting protein (CHIP) interaction with and ubiquitination of IRF-1. Activation of the IRF-1−XAF1 loop greatly increases stress-induced apoptosis and decreases the invasive capability of tumor cells. Oncogenic Ras and growth factors interfere with the IRF-1−XAF1 interplay via Erk-mediated repression of XAF1 transcription. Furthermore, XAF1 enhances IRF-1-mediated transcription of proapoptotic genes via the XAF1-IRF-1 complex formation on these target promoters. Meanwhile, XAF1 inhibits NF-κB-mediated tumor cell malignancy by reinforcing IRF-1 binding to a subset of coregulated promoters. Expression levels of IRF-1 and XAF1 correlate tightly in both cancer cell lines and primary tumors, and XAF1-induced tumor regression is markedly attenuated in IRF-1-depleted tumors. Collectively, this study identifies a novel mechanism of XAF1-mediated tumor suppression, uncovering XAF1 as a feedback coactivator of IRF-1 under stressful conditions.

Transient inhibition of NF-κB signaling enhances ex vivo propagation of human hematopoietic stem cells

Despite extensive studies, defining culture conditions in which hematopoietic stem cells can be expanded ex vivo has been challenging. Here we show that chemical inhibition of the NF-κB signaling pathway leads to a significant improvement of hematopoietic stem cell function from ex vivo cultured human umbilical cord blood derived CD34⁺ cells. We found a distinct peak of activation of the NF-κB pathway shortly after cells were put in culture, and consequently inhibition of the pathway was both necessary and sufficient during the first 24 hours of culture where it reduced the levels of several pro-inflammatory cytokines. Taken together, NF-κB pathway inhibition facilitates propagation of hematopoietic stem cells in culture and may complement other strategies for hematopoietic stem cell expansion by relieving stress signals that are induced as an immediate response to culture initiation.

Inhibitory Effect of Lycopene on Amyloid-β-Induced Apoptosis in Neuronal Cells

Alzheimer′s disease (AD) is a fatal neurodegenerative disease. Brain amyloid-β deposition is a crucial feature of AD, causing neuronal cell death by inducing oxidative damage. Reactive oxygen species (ROS) activate NF-κB, which induces expression of Nucling. Nucling is a pro-apoptotic factor recruiting the apoptosome complex. Lycopene is an antioxidant protecting from oxidative stress-induced cell damage. We investigated whether lycopene inhibits amyloid-β-stimulated apoptosis through reducing ROS and inhibiting mitochondrial dysfunction and NF-κB-mediated Nucling expression in neuronal SH-SY5Y cells. We prepared cells transfected with siRNA for Nucling or nontargeting control siRNA to determine the role of Nucling in amyloid-β-induced apoptosis. The amyloid-β increased intracellular and mitochondrial ROS levels, apoptotic indices (p53, Bax/Bcl-2 ratio, caspase-3 cleavage), NF-kB activation and Nucling expression, while cell viability, mitochondrial membrane potential, and oxygen consumption rate decreased in SH-SY5Y cells. Lycopene inhibited these amyloid-β-induced alterations. However, amyloid-β did not induce apoptosis, determined by cell viability and apoptotic indices (p53, Bax/Bcl-2 ratio, caspase-3 cleavage), in the cells transfected with siRNA for Nucling. Lycopene inhibited apoptosis by reducing ROS, and by inhibiting mitochondrial dysfunction and NF-κB-target gene Nucling expression in neuronal cells. Lycopene may be beneficial for preventing oxidative stress-mediated neuronal death in patients with neurodegeneration.

Inhibition of NF-κB improves the stress resistance and myogenic differentiation of MDSPCs isolated from naturally aged mice

A decline in the regenerative capacity of adult stem cells with aging is well documented. As a result of this decline, the efficacy of autologous stem cell therapies is likely to decline with increasing donor age. In these cases, strategies to restore the function of aged stem cells would have clinical utility. Globally, the transcription factor NF-κB is up-regulated in aged tissues. Given the negative role that NF-κB plays in myogenesis, we investigated whether the age-related decline in the function of muscle-derived stem/progenitor cells (MDSPCs) could be improved by inhibition of NF-κB. Herein, we demonstrate that pharmacologic or genetic inhibition of NF-κB activation increases myogenic differentiation and improves resistance to oxidative stress. Our results suggest that MDSPC “aging” may be reversible, and that pharmacologic targeting of pathways such as NF-κB may enhance the efficacy of cell-based therapies.

Enhanced autophagy reveals vulnerability of P-gp mediated epirubicin resistance in triple negative breast cancer cells

Epirubicin (EPI) is widely used for triple negative breast cancer (TNBC), but a substantial number of patients develop EPI resistance that is associated with poor outcome. The underlying mechanism for EPI resistance remains poorly understood. We have developed and characterized an EPI-resistant (EPI-R) cell line from parental MDA-MB-231 cells. These EPI-R cells reached stable growth in the medium containing 8 μg/ml of EPI. They overexpressed P-glycoprotein (P-gp) and contained numerous autophagic vacuoles. The suppression of P-gp overexpression and/or autophagy restored the sensitivity of these EPI-R cells to EPI. We further show that autophagy conferred resistance to EPI on MDA cells by blocking the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-mediated pro-apoptotic signals. Together, these results reveal a synergistic role of P-gp, autophagy, and NF-κB pathways in the development of EPI resistance in TNBC cells. They also suggest that blocking the P-gp overexpression and autophagy may be an effective means of reducing EPI resistance.

Synergistic cytotoxic effects of bortezomib and CK2 inhibitor CX-4945 in acute lymphoblastic leukemia: turning off the prosurvival ER chaperone BIP/Grp78 and turning on the pro-apoptotic NF-κB

The proteasome inhibitor bortezomib is a new targeted treatment option for refractory or relapsed acute lymphoblastic leukemia (ALL) patients. However, a limited efficacy of bortezomib alone has been reported. A terminal pro-apoptotic endoplasmic reticulum (ER) stress/unfolded protein response (UPR) is one of the several mechanisms of bortezomib-induced apoptosis. Recently, it has been documented that UPR disruption could be considered a selective anti-leukemia therapy. CX-4945, a potent casein kinase (CK) 2 inhibitor, has been found to induce apoptotic cell death in T-ALL preclinical models, via perturbation of ER/UPR pathway. In this study, we analyzed in T- and B-ALL preclinical settings, the molecular mechanisms of synergistic apoptotic effects observed after bortezomib/CX-4945 combined treatment. We demonstrated that, adding CX-4945 after bortezomib treatment, prevented leukemic cells from engaging a functional UPR in order to buffer the bortezomib-mediated proteotoxic stress in ER lumen. We documented that the combined treatment decreased pro-survival ER chaperon BIP/Grp78 expression, via reduction of chaperoning activity of Hsp90. Bortezomib/CX-4945 treatment inhibited NF-κB signaling in T-ALL cell lines and primary cells from T-ALL patients, but, intriguingly, in B-ALL cells the drug combination activated NF-κB p65 pro-apoptotic functions. In fact in B-cells, the combined treatment induced p65-HDAC1 association with consequent repression of the anti-apoptotic target genes, Bcl-xL and XIAP. Exposure to NEMO (IKKγ)-binding domain inhibitor peptide reduced the cytotoxic effects of bortezomib/CX-4945 treatment. Overall, our findings demonstrated that CK2 inhibition could be useful in combination with bortezomib as a novel therapeutic strategy in both T- and B-ALL.

HIPK family kinases bind and regulate the function of the CCR4-NOT complex

Down-regulation of the HIPK interactor CNOT2 leads to reduced HIPK2 protein levels, identifying the CCR4-NOT complex as a new regulator of HIPK2 abundance. Functional assays reveal that HIPK2 and HIPK1 restrict CNOT2-dependent mRNA decay, thus extending the regulatory potential of these kinases to the level of posttranscriptional gene regulation.

The serine/threonine kinase HIPK2 functions as a regulator of developmental processes and as a signal integrator of a wide variety of stress signals, such as DNA damage, hypoxia, and reactive oxygen intermediates. Because the kinase is generated in a constitutively active form, its expression levels are restricted by a variety of different mechanisms. Here we identify the CCR4-NOT complex as a new regulator of HIPK2 abundance. Down-regulation or knockout of the CCR4-NOT complex member CNOT2 leads to reduced HIPK2 protein levels without affecting the expression level of HIPK1 or HIPK3. A fraction of all HIPK family members associates with the CCR4-NOT components CNOT2 and CNOT3. HIPKs also phosphorylate the CCR4-NOT complex, a feature that is shared with their yeast progenitor kinase, YAK1. Functional assays reveal that HIPK2 and HIPK1 restrict CNOT2-dependent mRNA decay. HIPKs are well known regulators of transcription, but the mutual regulation between CCR4-NOT and HIPKs extends the regulatory potential of these kinases by enabling posttranscriptional gene regulation.

At High Levels, Constitutively Activated STAT3 Induces Apoptosis of Chronic Lymphocytic Leukemia Cells

In chronic lymphocytic leukemia (CLL), the increment in PBLs is slower than the expected increment calculated from the cells' proliferation rate, suggesting that cellular proliferation and apoptosis are concurrent. Exploring this phenomenon, we found overexpression of caspase-3, higher cleaved poly (ADP-ribose) polymerase levels (p < 0.007), and a higher apoptosis rate in cells from patients with high counts compared with cells from patients with low counts. Although we previously found that STAT3 protects CLL cells from apoptosis, STAT3 levels were significantly higher in cells from patients with high counts than in cells from patients with low counts. Furthermore, overexpression of STAT3 did not protect the cells. Rather, it upregulated caspase-3 and induced apoptosis. Remarkably, putative STAT3 binding sites were identified in the caspase-3 promoter, and a luciferase assay, chromatin immunoprecipitation, and an EMSA revealed that STAT3 activated caspase-3 However, caspase-3 levels increased only when STAT3 levels were sufficiently high. Using chromatin immunoprecipitation and EMSA, we found that STAT3 binds with low affinity to the caspase-3 promoter, suggesting that at high levels, STAT3 activates proapoptotic mechanisms and induces apoptosis in CLL cells.

Dietary Flavonoid Hyperoside Induces Apoptosis of Activated Human LX-2 Hepatic Stellate Cell by Suppressing Canonical NF-κB Signaling

Hyperoside, an active compound found in plants of the genera Hypericum and Crataegus, is reported to exhibit antioxidant, anticancer, and anti-inflammatory activities. Induction of hepatic stellate cell (HSC) apoptosis is recognized as a promising strategy for attenuation of hepatic fibrosis. In this study, we investigated whether hyperoside treatment can exert antifibrotic effects in human LX-2 hepatic stellate cells. We found that hyperoside induced apoptosis in LX-2 cells and decreased levels of α-smooth muscle actin (α-SMA), type I collagen, and intracellular reactive oxygen species (ROS). Remarkably, hyperoside also inhibited the DNA-binding activity of the transcription factor NF-κB and altered expression levels of NF-κB-regulated genes related to apoptosis, including proapoptotic genes Bcl-Xs, DR4, Fas, and FasL and anti-apoptotic genes A20, c-IAP1, Bcl-X_L, and RIP1. Our results suggest that hyperoside may have potential as a therapeutic agent for the treatment of liver fibrosis.

Differential Response of Two Human Breast Cancer Cell Lines to the Phenolic Extract from Flaxseed Oil

Many studies have evidenced that the phenolic components from flaxseed (FS) oil have potential health benefits. The effect of the phenolic extract from FS oil has been evaluated on two human breast cancer cell lines, MCF7 and MDA-MB231, and on the human non-cancerous breast cell line, MCF10A, by SRB assay, cellular death, cell cycle, cell signaling, lipid peroxidation and expression of some key genes. We have evidenced that the extract shows anti-proliferative activity on MCF7 cells by inducing cellular apoptosis, increase of the percentage of cells in G0/G1 phase and of lipid peroxidation, activation of the H2AX signaling pathway, and upregulation of a six gene signature. On the other hand, on the MDA-MB2131 cells we verified only an anti-proliferative activity, a weak lipid peroxidation, the activation of the PI3K signaling pathway and an up-regulation of four genes. Overall these data suggest that the extract has both cytotoxic and pro-oxidant effects only on MCF7 cells, and can act as a metabolic probe, inducing differences in the gene expression. For this purpose, we have performed an interactomic analysis, highlighting the existing associations. From this approach, we show that the phenotypic difference between the two cell lines can be explained through their differential response to the phenolic extract.

Microtubule affinity-regulating kinase 2 is associated with DNA damage response and cisplatin resistance in non-small cell lung cancer

Microtubule affinity-regulating kinases (MARKs) are involved in several cellular functions but few studies have correlated MARK kinase expression with cancer, and none have explored their role in lung cancer. In this study, we identified MARK2 as frequently disrupted by DNA hypomethylation and copy gain, resulting in concordant overexpression in independent lung tumor cohorts and we demonstrate a role for MARK2 in lung tumor biology. Manipulation of MARK2 in lung cell lines revealed its involvement in cell viability and anchorage-independent growth. Analyses of both manipulated cell lines and clinical tumor specimens identified a potential role for MARK2 in cell cycle activation and DNA repair. Associations between MARK2 and the E2F, Myc/Max and NF-κB pathways were identified by luciferase assays and in-depth assessment of the NF-κB pathway suggests a negative association between MARK2 expression and NF-κB due to activation of non-canonical NF-κB signaling. Finally, we show that high MARK2 expression levels correlate with resistance to cisplatin, a standard first line chemotherapy for lung cancer. Collectively, our work supports a role for MARK2 in promoting malignant phenotypes of lung cancer and potentially modulating response to the DNA damaging chemotherapeutic, cisplatin.

NF-κB regulates caspase-4 expression and sensitizes neuroblastoma cells to Fas-induced apoptosis

Found in neurons and neuroblastoma cells, Fas-induced apoptosis and accompanied activation of NF-κB signaling were thought to be associated with neurodegenerative diseases. However, the detailed functions of NF-κB activation in Fas killing and the effect of NF-κB activation on its downstream events remain unclear. Here, we demonstrated that agonistic Fas antibody induces cell death in a dose-dependent way and NF-κB signaling is activated as well, in neuroblastoma cells SH-EP1. Unexpectedly, NF-κB activation was shown to be pro-apoptotic, as suggested by the reduction of Fas-induced cell death with either a dominant negative form of IκBα (DN-IκBα) or an IκB kinase-specific inhibitor. To our interest, when analyzing downstream events of NF-κB signaling, we found that DN-IκBα only suppressed the expression of caspase-4, but not other caspases. Vice versa, enhancement of NF-κB activity by p65 (RelA) overexpression increased the expression of caspase-4 at both mRNA and protein levels. More directly, results from dual luciferase reporter assay demonstrated the regulation of caspase-4 promoter activity by NF-κB. When caspase-4 activity was blocked by its dominant negative (DN) form, Fas-induced cell death was substantially reduced. Consistently, the cleavage of PARP and caspase-3 induced by Fas was also reduced. In contrast, the cleavage of caspase-8 remained unaffected in caspase-4 DN cells, although caspase-8 inhibitor could rescue Fas-induced cell death. Collectively, these data suggest that caspase-4 activity is required for Fas-induced cell apoptosis and caspase-4 may act upstream of PARP and caspase-3 and downstream of caspase-8. Overall, we demonstrate that NF-κB can mediate Fas-induced apoptosis through caspase-4 protease, indicating that caspase-4 is a new mediator of NF-κB pro-apoptotic pathway in neuroblastoma cells.

The retinoblastoma tumor suppressor modulates DNA repair and radioresponsiveness

PURPOSE

Perturbations in the retinoblastoma pathway are over-represented in advanced prostate cancer; retinoblastoma loss promotes bypass of first-line hormone therapy. Conversely, preliminary studies suggested that retinoblastoma-deficient tumors may become sensitized to a subset of DNA-damaging agents. Here, the molecular and in vivo consequence of retinoblastoma status was analyzed in models of clinical relevance.

EXPERIMENTAL DESIGN

Experimental work was performed with multiple isogenic prostate cancer cell lines (hormone sensitive: LNCaP and LAPC4 cells and hormone resistant C42, 22Rv1 cells; stable knockdown of retinoblastoma using shRNA). Multiple mechanisms were interrogated including cell cycle, apoptosis, and DNA damage repair. Transcriptome analysis was performed, validated, and mechanisms discerned. Cell survival was measured using clonogenic cell survival assay and in vivo analysis was performed in nude mice with human derived tumor xenografts.

RESULTS

Loss of retinoblastoma enhanced the radioresponsiveness of both hormone-sensitive and castrate-resistant prostate cancer. Hypersensitivity to ionizing radiation was not mediated by cell cycle or p53. Retinoblastoma loss led to alteration in DNA damage repair and activation of the NF-κB pathway and subsequent cellular apoptosis through PLK3. In vivo xenografts of retinoblastoma-deficient tumors exhibited diminished tumor mass, lower PSA kinetics, and decreased tumor growth after treatment with ionizing radiation (P < 0.05).

CONCLUSIONS

Loss of retinoblastoma confers increased radiosensitivity in prostate cancer. This hypersensitization was mediated by alterations in apoptotic signaling. Combined, these not only provide insight into the molecular consequence of retinoblastoma loss, but also credential retinoblastoma status as a putative biomarker for predicting response to radiotherapy.

Cytokine effects on cell viability and death of prostate carcinoma cells

We analyzed the effects of IL-13, IFN- γ , and IL-1 β on cell viability and death of LNCaP and PC-3 cells and major signaling pathways involved in these effects. Significant increase of LNCaP cell death (apoptotic and necrotic) and increased levels of active caspase 3 were observed in cells treated with inhibitors of ERK 1/2 (UO126) and p38 (SB203580) prior to IL-1 β treatment in comparison to cells treated with UO126, SB203580, or IL-1 β alone. Significant increase of LNCaP but not PC-3 cell death was detected after treatment with LY-294002 (inhibitor of phosphatidylinositol 3-kinase). No significant increase of LNCaP and PC-3 cell death was observed after treatment with SP600125 (inhibitor of JNK), SB203580 (inhibitor of p38), UO126 (inhibitor of ERK 1/2), or BAY 11-7082 (inhibitor of NF- κ B). Reduced c-FLIPL expression was observed in LNCaP cells treated with LY-294002. The significant potentiation of LNCaP cell death by inhibition of ERK 1/2, p38, and PI3-K pathways may provide a rationale for therapeutic approach in androgen-dependent prostate cancer.

Response to rotenone is glucose-sensitive in a model of human acute lymphoblastic leukemia: involvement of oxidative stress mechanism, DJ-1, Parkin, and PINK-1 proteins

To establish the effect of low (11 mM) and high (55 mM) glucose concentrations (G11, G55) on Jurkat cells exposed to rotenone (ROT, a class 5 mitocan). We demonstrated that ROT induces apoptosis in Jurkat cells cultured in G11 by oxidative stress (OS) mechanism involving the generation of anion superoxide radical (O₂^∙−, 68%)/hydrogen peroxide (H₂O₂, 54%), activation of NF-κB (32%), p53 (25%), c-Jun (17%) transcription factors, and caspase-3 (28%), apoptosis-inducing factor (AIF, 36%) nuclei translocation, c-Jun N-terminal kinase (JNK) activation, and loss of mitochondria transmembrane potential (ΔΨ_m, 62%) leading to nuclei fragmentation (~10% and ~40% stage I-II fragmented nuclei, resp.). ROT induces massive cytoplasmic aggregates of DJ-1 (93%), and upregulation of Parkin compared to untreated cells, but no effect on PINK-1 protein was observed. Cell death marker detection and DJ-1 and Parkin expression were significantly reduced when cells were cultured in G55 plus ROT. Remarkably, metformin sensitized Jurkat cells against ROT in G55. Our results indicate that a high-glucose milieu promotes resistance against ROT/H₂O₂-induced apoptosis in Jurkat cells. Our data suggest that combined therapy by using mitochondria-targeted damaging compounds and regulation of glucose (e.g., metformin) can efficiently terminate leukemia cells via apoptosis in hyperglycemic conditions.

Necro-inflammatory response of pancreatic acinar cells in the pathogenesis of acute alcoholic pancreatitis

The role of pancreatic acinar cells in initiating necro-inflammatory responses during the early onset of alcoholic acute pancreatitis (AP) has not been fully evaluated. We investigated the ability of acinar cells to generate pro- and anti-inflammatory mediators, including inflammasome-associated IL-18/caspase-1, and evaluated acinar cell necrosis in an animal model of AP and human samples. Rats were fed either an ethanol-containing or control diet for 14 weeks and killed 3 or 24 h after a single lipopolysaccharide (LPS) injection. Inflammasome components and necro-inflammation were evaluated in acinar cells by immunofluorescence (IF), histology, and biochemical approaches. Alcohol exposure enhanced acinar cell-specific production of TNFα, IL-6, MCP-1 and IL-10, as early as 3 h after LPS, whereas IL-18 and caspase-1 were evident 24 h later. Alcohol enhanced LPS-induced TNFα expression, whereas blockade of LPS signaling diminished TNFα production in vitro, indicating that the response of pancreatic acinar cells to LPS is similar to that of immune cells. Similar results were observed from acinar cells in samples from patients with acute/recurrent pancreatitis. Although morphologic examination of sub-clinical AP showed no visible signs of necrosis, early loss of pancreatic HMGB1 and increased systemic levels of HMGB1 and LDH were observed, indicating that this strong systemic inflammatory response is associated with little pancreatic necrosis. These results suggest that TLR-4-positive acinar cells respond to LPS by activating the inflammasome and producing pro- and anti-inflammatory mediators during the development of mild, sub-clinical AP, and that these effects are exacerbated by alcohol injury.

Toll-like receptor agonists induce apoptosis in mouse B-cell lymphoma cells by altering NF-κB activation

Toll-like receptor 9 (TLR9) recognizes microbial DNA containing unmethylated cytosyl guanosyl (CpG) sequences, induces innate immune responses, and facilitates antigen-specific adaptive immunity. Recent studies report that in addition to stimulating innate immunity, TLR9 ligands induce apoptosis of TLR9 expressing cancer cells. To understand the mechanism of TLR9-induced apoptosis, we compared the effects of CpG containing oligodeoxynucleotides (CpG ODN) on a mouse B-cell lymphoma line, CH27, with those on mouse splenic B cells. CpG ODN inhibited constitutive proliferation and induced apoptosis in the CH27 B-cell lymphoma line. In contrast, CpG ODN-treated primary B cells were stimulated to proliferate and were rescued from spontaneous apoptosis. The induction of apoptosis required the ODNs to contain the CpG motif and the expression of TLR9 in lymphoma B cells. A decrease in Bcl-xl expression and an increase in Fas and Fas ligand expression accompanied lymphoma B-cell apoptosis. Treatment with the Fas ligand-neutralizing antibody inhibited CpG ODN-induced apoptosis. CpG ODN triggered a transient NF-κB activation in the B-cell lymphoma cell line, which constitutively expresses a high level of c-Myc, while CpG ODN induced sustained increases in NF-κB activation and c-Myc expression in primary B cells. Furthermore, an NF-κB inhibitor inhibited the proliferation of the CH27 B-cell lymphoma line. Our data suggest that the differential responses of lymphoma and primary B cells to CpG ODN are the result of differences in NF-κB activation. The impaired NF-κB activation in the CpG ODN-treated B-cell lymphoma cell line alters the balance between NF-κB and c-Myc, which induces Fas/Fas ligand-dependent apoptosis.

Targeting nuclear factor-kappa B to overcome resistance to chemotherapy

Intrinsic or acquired resistance to chemotherapeutic agents is a common phenomenon and a major challenge in the treatment of cancer patients. Chemoresistance is defined by a complex network of factors including multi-drug resistance proteins, reduced cellular uptake of the drug, enhanced DNA repair, intracellular drug inactivation, and evasion of apoptosis. Pre-clinical models have demonstrated that many chemotherapy drugs, such as platinum-based agents, antracyclines, and taxanes, promote the activation of the NF-κB pathway. NF-κB is a key transcription factor, playing a role in the development and progression of cancer and chemoresistance through the activation of a multitude of mediators including anti-apoptotic genes. Consequently, NF-κB has emerged as a promising anti-cancer target. Here, we describe the role of NF-κB in cancer and in the development of resistance, particularly cisplatin. Additionally, the potential benefits and disadvantages of targeting NF-κB signaling by pharmacological intervention will be addressed.

Role of NF-κB as a Prognostic Marker in Breast Cancer : A Pilot Study in Indian Patients

The nuclear factor κB (NF-κB) is a superfamily of transcription factors. It plays an important role in development & progression of cancer. This study was conducted in a tertiary care centre to investigate the significance of NF-κB as a prognostic marker in breast cancer and study its relation with established prognostic markers such as tumor grade, lymph node status, hormone receptor & HER-2/neu expression. We measured NF-κB expression of breast cancer tissue as a test sample & from fibroadenoma as a control. Measurement was done by Western Blot Technique using p65 protein of NF-κB super family of transcription factors. ER,PR and HER-2/neu were measured by immunohistochemistry methods. NF-κB/p65 is significantly associated with large tumor size (≥5 cm), high grade tumors, negative ER, negative PR, positive HER-2/neu and high NPI (≥5.4) scores. NF-κB/p65 expression implies aggressive biological behaviour of breast cancer & this study validates significant association of NF-κB /p65 overexpression with large tumor size, negative estrogen & progesterone receptor status and overexpression of c-erbB2 oncoprotein.

TPEN induces apoptosis independently of zinc chelator activity in a model of acute lymphoblastic leukemia and ex vivo acute leukemia cells through oxidative stress and mitochondria caspase-3- and AIF-dependent pathways

Acute lymphoblastic leukemia is still an incurable disease with resistance to therapy developing in the majority of patients. We investigated the effect of TPEN, an intracellular zinc chelator, in Jurkat and in ex vivo acute lymphoblastic leukemia (ALL) cells resistant to chemotherapy. Changes of nuclei morphology, reactive oxygen species generation, presence of hypodiploid cells, phosphatidylserine translocation, mitochondrial membrane depolarization, immunohistochemical identification of cell death signalling molecules, and pharmacological inhibition were assayed to detect the apoptotic cell death pathways. We found that TPEN induces apoptosis in both types of cells by a molecular oxidative stress pathway involving O(2)(•-) > H(2)O(2) >> NF-κB (JNK/c-Jun) >p53> loss ΔΨ(m)> caspase-3, AIF > chromatin condensation/DNA fragmentation. Interestingly, TPEN induced apoptosis independently of glucose; leukemic cells are therefore devoid of survival capacity by metabolic resistance to treatment. Most importantly, TPEN cytotoxic effect can eventually be regulated by the antioxidant N-acetyl-cysteine and zinc ions. Our data suggest that TPEN can be used as a potential therapeutic prooxidant agent against refractory leukemia. These data contribute to understanding the importance of oxidative stress in the treatment of ALL.

Dentatin Induces Apoptosis in Prostate Cancer Cells via Bcl-2, Bcl-xL, Survivin Downregulation, Caspase-9, -3/7 Activation, and NF-κB Inhibition

This study was set to investigate antiproliferative potential of dentatin (a natural coumarin isolated from Clausena excavata Burm. F) against prostate cancer and to delineate the underlying mechanism of action. Treatment with dentatin dose-dependently inhibited cell growth of PC-3 and LNCaP prostate cancer cell lines, whereas it showed less cytotoxic effects on normal prostate epithelial cell line (RWPE-1). The inhibitory effect of dentatin on prostate cancer cell growth was due to induction of apoptosis as evidenced by Annexin V staining and cell shrinkage. We found that dentatin-mediated accumulation of reactive oxygen species (ROS) and downregulated expression levels of antiapoptotic molecules (Bcl-2, Bcl-xL, and Survivin), leading to disruption of mitochondrial membrane potential (MMP), cell membrane permeability, and release of cytochrome c from the mitochondria into the cytosol. These effects were associated with induction of caspase-9, -3/7 activities, and subsequent DNA fragmentation. In addition, we found that dentatin inhibited TNF-α-induced nuclear translocation of p65, suggesting dentatin as a potential NF-κB inhibitor. Thus, we suggest that dentatin may have therapeutic value in prostate cancer treatment worthy of further development.

Rhein induces apoptosis in human breast cancer cells

Human breast cancers cells overexpressing HER2/neu are more aggressive tumors with poor prognosis, and resistance to chemotherapy. This study investigates antiproliferation effects of anthraquinone derivatives of rhubarb root on human breast cancer cells. Of 7 anthraquinone derivatives, only rhein showed antiproliferative and apoptotic effects on both HER2-overexpressing MCF-7 (MCF-7/HER2) and control vector MCF-7 (MCF-7/VEC) cells. Rhein induced dose- and time-dependent manners increase in caspase-9-mediated apoptosis correlating with activation of ROS-mediated activation of NF-κB- and p53-signaling pathways in both cell types. Therefore, this study highlighted rhein as processing anti-proliferative activity against HER2 overexpression or HER2-basal expression in breast cancer cells and playing important roles in apoptotic induction of human breast cancer cells.

Nucleolar NF-κB/RelA mediates apoptosis by causing cytoplasmic relocalization of nucleophosmin

In a number of contexts, and particularly in response to cellular stress, stimulation of the NF-kappaB (NF-κB) pathway promotes apoptosis. One mechanism underlying this pro-apoptotic activity is nucleolar sequestration of RelA, which is reported to cause cell death by repressing NF-κB-driven transcription. Here, we identify a novel and distinct nucleolar activity of RelA that induces apoptosis. We demonstrate, using a viral nucleolar localization signal (NoLS)-RelA fusion protein, that direct targeting of RelA to the nucleolus mediates apoptosis, independent of NF-κB transcriptional activity. We demonstrate a requirement for nucleophosmin (NPM, B23.1) in this apoptotic effect, and the apoptotic effect of stress-induced nucleolar RelA. We show by multiple approaches that nucleolar translocation of RelA is causally involved in the relocalization of NPM from the nucleolus to the cytoplasm and that RelA-induced cytoplasmic NPM mediates apoptosis by facilitating the mitochondrial accumulation of BAX. These data uncover a novel stress-response pathway and mechanism by which RelA promotes apoptosis, independent of its effects on NF-κB transcriptional activity. These findings are relevant to the design of novel anticancer agents that target RelA to this compartment.

Vitamin K3 and vitamin C alone or in combination induced apoptosis in leukemia cells by a similar oxidative stress signalling mechanism

BACKGROUND

Secondary therapy-related acute lymphoblastic leukemia might emerge following chemotherapy and/or radiotherapy for primary malignancies. Therefore, other alternatives should be pursued to treat leukemia.

RESULTS

It is shown that vitamin K3- or vitamin C- induced apoptosis in leukemia cells by oxidative stress mechanism involving superoxide anion radical and hydrogen peroxide generation, activation of NF-κB, p53, c-Jun, protease caspase-3 activation and mitochondria depolarization leading to nuclei fragmentation. Cell death was more prominent when Jurkat and K562 cells are exposed to VC and VK3 in a ratio 1000:1 (10 mM: 10 μM) or 100:1 (300 μM: 3 μM), respectively.

CONCLUSION

We provide for the first time in vitro evidence supporting a causative role for oxidative stress in VK3- and VC-induced apoptosis in Jurkat and K562 cells in a domino-like mechanism. Altogether these data suggest that VK3 and VC should be useful in the treatment of leukemia.

Computational identification of transcriptional regulators in human endotoxemia

One of the great challenges in the post-genomic era is to decipher the underlying principles governing the dynamics of biological responses. As modulating gene expression levels is among the key regulatory responses of an organism to changes in its environment, identifying biologically relevant transcriptional regulators and their putative regulatory interactions with target genes is an essential step towards studying the complex dynamics of transcriptional regulation. We present an analysis that integrates various computational and biological aspects to explore the transcriptional regulation of systemic inflammatory responses through a human endotoxemia model. Given a high-dimensional transcriptional profiling dataset from human blood leukocytes, an elementary set of temporal dynamic responses which capture the essence of a pro-inflammatory phase, a counter-regulatory response and a dysregulation in leukocyte bioenergetics has been extracted. Upon identification of these expression patterns, fourteen inflammation-specific gene batteries that represent groups of hypothetically ‘coregulated’ genes are proposed. Subsequently, statistically significant cis-regulatory modules (CRMs) are identified and decomposed into a list of critical transcription factors (34) that are validated largely on primary literature. Finally, our analysis further allows for the construction of a dynamic representation of the temporal transcriptional regulatory program across the host, deciphering possible combinatorial interactions among factors under which they might be active. Although much remains to be explored, this study has computationally identified key transcription factors and proposed a putative time-dependent transcriptional regulatory program associated with critical transcriptional inflammatory responses. These results provide a solid foundation for future investigations to elucidate the underlying transcriptional regulatory mechanisms under the host inflammatory response. Also, the assumption that coexpressed genes that are functionally relevant are more likely to share some common transcriptional regulatory mechanism seems to be promising, making the proposed framework become essential in unravelling context-specific transcriptional regulatory interactions underlying diverse mammalian biological processes.

Proteasome inhibitor PS-341 (bortezomib) induces calpain-dependent IkappaB(alpha) degradation

The proteasome, a key component of the ubiquitin-proteasome pathway, has emerged as an important cancer therapeutic target. PS-341 (also called Bortezomib or Velcade) is the first proteasome inhibitor approved for newly diagnosed and relapsed multiple myeloma and is currently being tested in many clinical trials against other types of cancers. One proposed mechanism by which PS-341 exerts its anticancer effect is inactivation of nuclear factor-kappaB (NF-kappaB) through prevention of IkappaB(alpha) degradation. In this study, we show that PS-341 at concentrations that effectively inhibited the growth of human cancer cells, instead of increasing IkappaB(alpha) stability, paradoxically induced IkappaB(alpha) degradation. As a result, PS-341 facilitated p65 nuclear translocation and increased NF-kappaB activity. Moreover, IkappaB(alpha) degradation by PS-341 occurred early before induction of apoptosis and could not be inhibited by a pan-caspase inhibitor or caspase-8 silencing; however, it could be prevented with calpain inhibitors, calcium-chelating agents, calpain knockdown, or calpastatin overexpression. In agreement, PS-341 increased calpain activity. These data together indicate that PS-341 induces a calpain-mediated IkappaB(alpha) degradation independent of caspases. In the presence of a calpain inhibitor, the apoptosis-inducing activity of PS-341 was dramatically enhanced. Collectively, these unexpected findings suggest not only a novel paradigm regarding the relationship between proteasome inhibition and NF-kappaB activity but also a strategy to enhance the anticancer efficacy of PS-341.

Activation of nuclear factor kappa B in mammary epithelium promotes milk loss during mammary development and infection

We investigated whether nuclear factor kappa B (NF-kappaB), which exhibits a regulated pattern of activity during murine mammary gland development, plays an important role during lactation and involution, when milk production ceases and the gland undergoes apoptosis and re-modeling. We generated a doxycycline inducible transgenic mouse model to activate NF-kappaB specifically in the mammary epithelium through expression of a constitutively active form of IKK2, the upstream kinase in the classical NF-kappaB signaling cascade. We found that activation of NF-kappaB during involution resulted in a more rapid reduction in milk levels and increased cleavage of caspase-3, an indicator of apoptosis. We also found that activation of NF-kappaB during lactation with no additional involution signals had a similar effect. The observation that NF-kappaB is a key regulator of milk production led us to investigate the role of NF-kappaB during mastitis, an infection of the mammary gland in which milk loss is observed. Mammary gland injection of E. coli LPS resulted in activation of NF-kappaB and milk loss during lactation. This milk loss was decreased by selective inhibition of NF-kappaB in mammary epithelium. Together, our data reveal that activation of NF-kappaB leads to milk clearance in the lactating mammary gland. Therefore, targeting of NF-kappaB signaling may prove therapeutic during mastitis in humans and could be beneficial for the dairy industry, where such infections have a major economic impact.

Dexamethasone enhances trichosanthin-induced apoptosis in the HepG2 hepatoma cell line

AIMS

Trichosanthin (TCS) is a type I ribosome-inactivating protein (RIP) with antitumor activities for various cancers. In this paper, we aimed to investigate whether dexamethasone, an important synthetic member of the glucocorticoid steroids, in combination with TCS can be a potential therapy in treating hepatoma.

MAIN METHODS

Cell viability was investigated using MTT assay, and apoptosis was evaluated with Hoechst 33258 staining. Western blot analysis was used to examine the changes in the expression levels of IkappaB-alpha, NF-kappaB p65 subunit and Cox-2. Additionally, we took advantage of dominant-negative IkappaB (IkappaB-DM) over-expression and chemical inhibitor PDTC to inhibit NF-kappaB activation.

KEY FINDINGS

Our results demonstrated that dexamethasone could enhance TCS-induced apoptosis in the hepatoma cell line HepG2, decreasing IC50 values from in excess of 200microg/ml to 50microg/ml. In addition, our results demonstrated that TCS could induce rapid degradation of IkappaB-alpha, nuclear translocation of NF-kappaB and decrease of COX-2 expression in HepG2 cells. Inhibition of NF-kappaB by biological (IkappaB-DM) or chemical inhibitor (PDTC) increased HepG2 cells' sensitivity to TCS, resulting in cell viability rate decreasing and apoptotic rate increasing. Simultaneously, dexamethasone increased the level of IkappaB-alpha protein and effectively inhibited TCS-induced degradation of IkappaB-alpha.

SIGNIFICANCE

These results suggest that dexamethasone could enhance trichosanthin-induced apoptosis in the HepG2, at least in part, by inhibiting the NF-kappaB signaling pathway and thus strengthening the antitumor effects of TCS, which highlights the possibility of combined drug application of TCS and dexamethasone in the clinical treatment of hepatoma.

Leukocyte elastase induces lung epithelial apoptosis via a PAR-1-, NF-kappaB-, and p53-dependent pathway

Leukocyte elastase induces apoptosis of lung epithelial cells via alterations in mitochondrial permeability, but the signaling pathways regulating this response remain uncertain. Here we investigated the involvement of proteinase-activated receptor-1 (PAR-1), the transcription factor NF-kappaB, and the protooncogene p53 in this pathway. Elastase-induced apoptosis of lung epithelial cells correlated temporally with activation of NF-kappaB, phosphorylation, and nuclear translocation of p53, increased p53 up-regulated modulator of apoptosis (PUMA) expression, and mitochondrial translocation of Bax resulting in enhanced permeability. Elastase-induced apoptosis was also prevented by pharmacologic inhibitors of NF-kappaB and p53 and by short interfering RNA knockdown of PAR-1, p53, or PUMA. These inhibitors prevented elastase-induced PUMA expression, mitochondrial translocation of Bax, increased mitochondrial permeability, and attenuated apoptosis. NF-kappaB inhibitors also reduced p53 phosphorylation. We conclude that elastase-induced apoptosis of lung epithelial cells is mediated by a PAR-1-triggered pathway involving activation of NF-kappaB and p53, and a PUMA- and Bax-dependent increase in mitochondrial permeability leading to activation of distal caspases. Further, p53 contributes to elastase-induced apoptosis by both transcriptional and post-transcriptional mechanisms.

NF-kappaB blockade upregulates Bax, TSP-1, and TSP-2 expression in rat granulation tissue

Several diseases are characterized by chronic inflammation, a condition frequently associated with angiogenesis and fibrogenesis that account for the development of granulation tissue. Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) is a crucial modulator of intracellular prosurvival signaling pathways and is implicated in the pathogenesis of inflammatory process. In this study, we have investigated the role of NF-kappaB in the angiogenic and fibrogenic response induced by lambda-carrageenin in a rat model of chronic inflammation at 1, 3, and 5 days. The subcutaneous implant of lambda-carrageenin-soaked sponges in rat induced a time-related increase of granulation tissue formation accompanied by intense neovascularization. These lambda-carrageenin-induced changes were significantly reduced by coinjection of wild-type oligodeoxynucleotide (WT ODN) decoy to NF-kappaB. Molecular, morphological, and ultrastructural analysis performed on whole granulation tissue demonstrated: (1) inhibition of NF-kappaB/DNA binding activity; (2) downregulation of cyclooxygenase-2, matrix metalloproteinase-9, tumor necrosis factor-alpha, and vascular endothelial growth factor; (3) upregulation of thrombospondin (TSP)-1 at 1 day and TSP-2 at 5 days; and (4) increase in Bax to Bcl-2 ratio. Our findings show that the blockade of NF-kappaB activation by WT ODN decoy prevents the development of granulation tissue induced by lambda-carrageenin-soaked sponge implant upregulating Bax as well as TSP-1 and TSP-2 expression.

NF-KappaB expression correlates with apoptosis and angiogenesis in clear cell renal cell carcinoma tissues

Background

Clear cell renal cell carcinoma (ccRCC) is the most frequently encountered tumor in the adult kidney. Many factors are known to take part in the development and progression of this tumor. Nuclear factor kappa B (NF-κB) is a family of the genes that includes five members acting in events such as inflammation and apoptosis. In this study, the role of NF-κB (p50 subunit) in ccRCC and its relation to angiogenesis and apoptosis were investigated.

Methods

Formalin-fixed and paraffin embedded tissue blocks from 40 patients with ccRCC were studied. Expressions of NF-κB (p50), VEGF, EGFR, bc1-2 and p53 were detected immunohistochemically. The relationship of NF-κB with these markers and clinicopathological findings were evaluated.

Results

The expression of NF-κB was detected in 35 (85%), VEGF in 37 (92.5%), EGFR in 38 (95%), bc1-2 in 33 (82.5%) and p53 in 13 (32.5%) of 40 ccRCC patients. Statistical analyses revealed a significant relation between NF-κB expression and VEGF (p = 0.001), EGFR (p = 0.004), bc1-2 (p = 0.010) and p53 (p = 0.037). There was no significant correlation between NF-κB and such parameters as tumor grade, stage, age and sex.

Conclusion

The results of this study indicated that in ccRCC cases NF-κB was associated with markers of angiogenesis and apoptosis such as VEGF, EGFR, bc1-2 and p53. In addition, the results did not only suggest a close relationship between NF-κB and VEGF, EGFR, bc1-2 and p53 in ccRCC, but also indicate that NF-κB was a potential therapeutic target in the treatment of ccRCC resistant to chemotherapy.

HTLV-1 tax-induced NF-kappaB activation is synergistically enhanced by 12-O-tetradecanoylphorbol-13-acetate: mechanism and implications for Tax oncogenicity

Nuclear factor kappa B (NF-kappaB) factors regulate a wide range of physiological and oncogenic processes. Normally, these factors are transiently activated by specific external signals which induce their dissociation from inhibitors of kappaB (IkappaB) and subsequent translocation to the nucleus where p65 links to the cyclic adenosine monophosphate response element binding protein (CBP)-p300 and P/CAF coactivators that are essential for its transcriptional activity. The pathogenic potential of human T-cell leukemia virus type 1 (HTLV-1) Tax protein is partly ascribed to its capacity to constitutively activate NF-kappaB factors because constitutive activity of these factors play an important role in the pathophysiology of adult T-cell leukemia (ATL) and tropical spastic paraparesis-HTLV-1 associated myelopathy (TSP-HAM). In assessing the possibility of modulating Tax pathogenic potential by external factors, we focused here on 12-O -tetradecanoylphorbol-13-acetate (TPA) which is a potent protein kinase C (PKC) activator. There are conflicting reports regarding the effect of TPA and PKC on NF-kappaB. Therefore, we reassessed this issue and also investigated their influence on Tax-mediated activation of these factors. We found that TPA promoted NF-kappaB nuclear translocation and the DNA binding of p65 dimers through PKC activation. However, both TPA and ectopically expressed PKC had only a marginal effect on the transcriptional competence of these dimers, indicating that the DNA binding of such dimers is insufficient by itself for gene activation. Notably, however, both TPA and the ectopic PKC displayed strong synergistic enhancement of the Tax-induced activation of the NF-kappaB transcriptional function. In contrast, TPA and the ectopic PKC only slightly elevated the low activation of the NF-kappaB transcriptional capacity by cytoplasmic Tax mutants, indicating that the nuclear translocation of Tax was essential for this synergism. Subsequent experiments suggested that TPA contributed to this synergism by increasing the pool of free p65 which Tax could link to CBP and elevate, thereby, the amount of a p65-Tax-CBP ternary complex that could bind to NF-kappaB-responsive promoters and stimulate their expression. Finally, we demonstrated that this synergism operated also in HTLV-1-infected human T-cells. Earlier reports have shown a close linkage of pathological PKC-activating conditions (e.g., infectious and inflammatory diseases) to certain malignancies. On this ground, the present study suggests that such conditions may enhance the risk for ATL and TSP-HAM in HTLV-1 carriers by increasing the Tax-induced NF-kappaB activation.

NF-kappa B: a new player in angiostatic therapy

Angiogenesis is considered a promising target in the treatment of cancer. Most of the angiogenesis inhibitors in late-stage clinical testing or approved for the treatment of cancer act indirectly on endothelial cells. They either neutralize angiogenic growth factors from the circulation or block the signaling pathways activated by these growth factors. Another group of angiogenesis inhibitors are the direct angiostatic compounds. These agents have a direct effect on the endothelium, affecting cellular regulatory pathways, independently of the tumor cells. The reason that this category of agents is lagging behind regarding their translation to the clinic may be the lack of sufficient knowledge on the mechanism of action of these compounds. The transcription factor NF-κB has been recently connected with multiple aspects of angiogenesis. In addition, several recent studies report that angiogenesis inhibition is associated to NF-κB activation. This is of special interest since in tumor cells NF-κB activation has been associated to inhibition of apoptosis and currently novel treatment strategies are being developed based on inhibition of NF-κB. The paradigm that systemic NF-κB inhibition can serve as an anti-cancer strategy, therefore, might need to be re-evaluated. Based on recent data, it might be speculated that NF-κB activation, when performed specifically in endothelial cells, could be an efficient strategy for the treatment of cancer.