Harnessing tumor necrosis factor receptors to enhance antitumor activities of drugs

Regulation of anoikis by extrinsic death receptor pathways

Metastatic cancer cells can develop anoikis resistance in the absence of substrate attachment and survive to fight tumors. Anoikis is mediated by endogenous mitochondria-dependent and exogenous death receptor pathways, and studies have shown that caspase-8-dependent external pathways appear to be more important than the activity of the intrinsic pathways. This paper reviews the regulation of anoikis by external pathways mediated by death receptors. Different death receptors bind to different ligands to activate downstream caspases. The possible mechanisms of Fas-associated death domain (FADD) recruitment by Fas and TNF receptor 1 associated-death domain (TRADD) recruitment by tumor necrosis factor receptor 1 (TNFR1), and DR4- and DR5-associated FADD to induce downstream caspase activation and regulate anoikis were reviewed. This review highlights the possible mechanism of the death receptor pathway mediation of anoikis and provides new insights and research directions for studying tumor metastasis mechanisms. Video Abstract.

Comparative assessment on the probable mechanisms underlying the hepatorenal toxicity of commercial imidacloprid and hexaflumuron formulations in rats

Pesticides are viewed as a major wellspring of ecological contamination and causing serious risky consequences for people and animals. Imidacloprid (IM) and hexaflumuron (HFM) are extensively utilized insect poisons for crop assurance on the planet. A few investigations examined IM harmfulness in rodents, but its exact mechanism hasn't been mentioned previously as well as the toxicity of HFM doesn't elucidate yet. For this reason, the present study was designed to explore the mechanism of each IM and HFM-evoked rat liver and kidney toxicity and to understand its molecular mechanism. 21 male Wistar albino rats were divided into 3 groups, as follows: group (1), normal saline; group (2), IM; and group (3), HFM. Both insecticides were orally administered every day for 28 days at a dose equal to 1/10 LD50 from the active ingredient. After 28 days postdosing, rats were anesthetized to collect blood samples then euthanized to collect liver and kidney tissue specimens. The results showed marked changes in walking, body tension, alertness, and head movement with a significant reduction in rats' body weight in both IM and HFM receiving groups. Significant increases in MDA levels and decrease of GHS levels were recorded in liver and kidney homogenates of either IM or HFM groups. Liver and kidney tissues obtained from both pesticide receiving groups showed extensive histopathological alterations with a significant increase in the serum levels of ALT, AST, urea, and creatinine and a decrease in total proteins, albumin, and globulin levels. In addition, there was upregulation of the transcript levels of casp-3, JNK, and HO-1 genes with strong immunopositivity of casp-3, TNF-ὰ, and NF-_KB protein expressions in the liver and kidneys of rats receiving either IM or HFM compared with the control group. In all studied parameters, HFM caused hepatorenal toxicity more than those induced by IM. We can conclude that each IM and HFM provoked liver and kidneys damage through overproduction of ROS, activation of NF-_KB signaling pathways and mitochondrial/JNK-dependent apoptosis pathway.

Fractalkine Is Linked to the Necrosome Pathway in Acute Pulmonary Inflammation

Acute pulmonary inflammation affects over 10% of intensive care unit (ICU) patients and is associated with high mortality. Fractalkine (CX₃CL1) and its receptor, CX₃CR1, have been shown to affect pulmonary inflammation, but previous studies have focused on macrophages. In a murine model of acute pulmonary inflammation, we identified inflammatory hallmarks in C57BL/6J and CX₃CR1^−/− mice. Pulmonary inflammation was significantly enhanced in the CX₃CR1^−/− animals compared to the C57BL/6J animals, as assessed by microvascular permeability, polymorphonuclear neutrophil (PMN) migration into lung tissue and alveolar space. The CX₃CR1^−/− mice showed increased levels of apoptotic PMNs in the lungs, and further investigations revealed an increased activation of necrosome-related receptor-interacting serine/threonine-protein kinases 1 (RIPK1), 3 (RIPK3), and mixed-lineage kinase domain-like pseudokinase (MLKL). Phosphorylated MLKL leads to membrane rupture and damage-associated molecular pattern (DAMP) release, which further enhance inflammation. The release of DAMPs was significantly higher in the CX₃CR1^−/− mice and led to the activation of various cascades, explaining the increased inflammation. RIPK3 and MLKL inhibition improved the inflammatory response in human PMNs in vitro and confirmed our in vivo findings. In conclusion, we linked CX₃CL1 to the necrosome complex in pulmonary inflammation and demonstrated a pivotal role of the necrosome complex in human PMNs.

Transcriptome analysis in normal human liver cells exposed to 2, 3, 3', 4, 4', 5 - Hexachlorobiphenyl (PCB 156)

BACKGROUNDS

Polychlorinated biphenyls are persistent environmental pollutants associated with the onset of non-alcoholic fatty liver disease in humans, but there is limited information on the underlying mechanism. In the present study, we investigated the alterations in gene expression profiles in normal human liver cells L-02 following exposure to 2, 3, 3', 4, 4', 5 - hexachlorobiphenyl (PCB 156), a potent compound that may induce non-alcoholic fatty liver disease.

METHODS

The L-02 cells were exposed to PCB 156 for 72 h and the contents of intracellular triacylglyceride and total cholesterol were subsequently measured. Microarray analysis of mRNAs and long non-coding RNAs (lncRNAs) in the cells was also performed after 3.4 μM PCB 156 treatment.

RESULTS

Exposure to PCB 156 (3.4 μM, 72 h) resulted in significant increases of triacylglyceride and total cholesterol concentrations in L-02 cells. Microarray analysis identified 222 differentially expressed mRNAs and 628 differentially expressed lncRNAs. Gene Ontology and pathway analyses associated the differentially expressed mRNAs with metabolic and inflammatory processes. Moreover, lncRNA-mRNA co-expression network revealed 36 network pairs comprising 10 differentially expressed mRNAs and 34 dysregulated lncRNAs. The results of bioinformatics analysis further indicated that dysregulated lncRNA NONHSAT174696, lncRNA NONHSAT179219, and lncRNA NONHSAT161887, as the regulators of EDAR, CYP1B1, and ALDH3A1 respectively, played an important role in the PCB 156-induced lipid metabolism disorder.

CONCLUSION

Our findings provide an overview of differentially expressed mRNAs and lncRNAs in L-02 cells exposed to PCB 156, and contribute to the field of polychlorinated biphenyl-induced non-alcoholic fatty liver disease.

The Physiological Role of Tumor Necrosis Factor in Human Immunity and Its Potential Implications in Spinal Manipulative Therapy: A Narrative Literature Review

OBJECTIVE

Although tumor necrosis factor (TNF) is a well-known inflammatory cytokine in the pathological development of various human diseases, its physiological roles are not widely understood nor appreciated. The molecular mechanisms underlying spinal manipulation therapy (SMT) remain elusive. The relationship between TNF and SMT is unclear. Thus, we performed this literature review to better understand TNF physiology and its potential relationship with SMT, and we propose a novel mechanism by which SMT may achieve clinical benefits by using certain beneficial features of TNF.

METHODS

We searched several databases for relevant articles published between 1975 and 2015 and then reexamined the studies from current immunophysiological perspectives.

RESULTS

The history and recent progresses in TNF physiology research were explored. Conflicting reports on the relationship between TNF and SMT were identified. Based on the newly discovered interaction between TNF and regulatory T cells, we proposed a putative biphasic TNF response to SMT, which may resolve the conflicts in the reported observations and interpretations.

CONCLUSION

The current literature about TNF informed our discussion of new physiological roles for TNF, which may help to better understand the physiological effects of SMT.

Lactate does not activate NF-κB in oxidative tumor cells

The lactate anion is currently emerging as an oncometabolite. Lactate, produced and exported by glycolytic and glutaminolytic cells in tumors, can be recycled as an oxidative fuel by oxidative tumors cells. Independently of hypoxia, it can also activate transcription factor hypoxia-inducible factor-1 (HIF-1) in tumor and endothelial cells, promoting angiogenesis. These protumoral activities of lactate depend on lactate uptake, a process primarily facilitated by the inward, passive lactate-proton symporter monocarboxylate transporter 1 (MCT1); the conversion of lactate and NAD(+) to pyruvate, NADH and H(+) by lactate dehydrogenase-1 (LDH-1); and a competition between pyruvate and α-ketoglutarate that inhibits prolylhydroxylases (PHDs). Endothelial cells do not primarily use lactate as an oxidative fuel but, rather, as a signaling agent. In addition to HIF-1, lactate can indeed activate transcription factor nuclear factor-κB (NF-κB) in these cells, through a mechanism not only depending on PHD inhibition but also on NADH alimenting NAD(P)H oxidases to generate reactive oxygen species (ROS). While NF-κB activity in endothelial cells promotes angiogenesis, NF-κB activation in tumor cells is known to stimulate tumor progression by conferring resistance to apoptosis, stemness, pro-angiogenic and metastatic capabilities. In this study, we therefore tested whether exogenous lactate could activate NF-κB in oxidative tumor cells equipped for lactate signaling. We report that, precisely because they are oxidative, HeLa and SiHa human tumor cells do not activate NF-κB in response to lactate. Indeed, while lactate-derived pyruvate is well-known to inhibit PHDs in these cells, we found that NADH aliments oxidative phosphorylation (OXPHOS) in mitochondria rather than NAD(P)H oxidases in the cytosol. These data were confirmed using oxidative human Cal27 and MCF7 tumor cells. This new information positions the malate-aspartate shuttle as a key player in the oxidative metabolism of lactate: similar to glycolysis that aliments OXPHOS with pyruvate produced by pyruvate kinase and NADH produced by glyceraldehyde-3-phosphate dehydrogenase (GAPDH), oxidative lactate metabolism aliments OXPHOS in oxidative tumor cells with pyruvate and NADH produced by LDH1.

Tanshinone IIA Facilitates TRAIL Sensitization by Up-regulating DR5 through the ROS-JNK-CHOP Signaling Axis in Human Ovarian Carcinoma Cell Lines

Tanshinone IIA (TIIA) extracted from Salvia miltiorrhiza has been shown to possess antitumor and TRAIL-sensitizing activity. The involvement of DR5 in the mechanism whereby TIIA exerts its effects is unknown. This study aimed to explore the mechanism underlying TIIA augmentation of TRAIL-induced cell death in ovarian carcinoma cells. Cell viability was determined by MTS assay. Real-time RT-PCR and Western blotting were used to assess the mRNA and protein expression of relating signaling proteins. Transcriptional activation was explored by a dual-luciferase reporter assay. We found that TIIA sensitized human ovarian carcinoma cells to TRAIL-induced extrinsic apoptosis. Combined treatment with subtoxic concentrations of TIIA and TRAIL was more effective than single treatments with respect to cytotoxicity, clonogenic inhibition, and the induction of caspase-8 and PARP activity in ovarian carcinoma cell lines TOV-21G and SKOV3. TIIA induced DR5 protein and mRNA expression in a concentration-dependent manner. DR5/Fc treatment markedly suppressed the TRAIL cytotoxicity enhanced by TIIA. These results indicate that DR5 plays an essential role in TIIA-induced TRAIL sensitization and that induction of DR5 by TIIA is mediated through the up-regulation of CCAAT/enhancer-binding protein homologous protein (CHOP). Knockdown of CHOP gene expression by shRNA attenuated DR5 up-regulation and rescued cell viability under the treatment of TIIA-TRAIL combination. TIIA promoted JNK-mediated signaling to up-regulated CHOP and thereby inducing DR5 expression as shown by the ability of a JNK inhibitor to potently suppress the TIIA-mediated activation of CHOP and DR5. In addition, the quenching of ROS using NAC prevented the induction of JNK phosphorylation and CHOP induction. Furthermore, inhibition of ROS by NAC significantly attenuated TRAIL sensitization by TIIA. Taken together, these data suggest that TIIA enhances TRAIL-induced apoptosis by upregulating DR5 receptors through the ROS-JNK-CHOP signaling axis in human ovarian carcinoma cells.

Studies of genes involved in craniofacial development and tumorigenesis: FGF3 contributes to isolated oral clefts and may interact with PAX9

OBJECTIVE

Previous studies suggest individuals born with oral clefts and their families have a higher susceptibility for cancer, which raises the hypothesis that these two conditions share common molecular pathways. This study evaluated the association between oral clefts and polymorphisms in genes that play a role in craniofacial and tumor development.

MATERIALS AND METHODS

Four hundred and ninety-seven subjects born with oral clefts and 823 unaffected subjects were recruited. Twenty-nine markers in 13 genes were genotyped by the Taqman method. Chi-square was used to compare allele and genotype frequencies. Bonferroni correction for multiple testing was used and the established alpha was 0.0003. This study also used logistic regression to test if genetic variants were associated with oral clefts using positive family history of cancer and age as covariates.

RESULTS

There was no association between family history of cancer and oral clefts (p = 0.51). None of the 1320 study participants had a diagnosis of cancer at the time of participation in the study. The marker rs4980700 in FGF3 was associated with oral clefts (p = 0.0002). Logistic regression analysis also provided evidence for gene-gene interaction between FGF3 (rs4980700) and PAX9 (rs2073242), increasing the risk for isolated oral clefts (p = 0.0003).

CONCLUSION

FGF3 is associated with oral clefts and may interact with PAX9.

TRAF molecules in cell signaling and in human diseases

The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of intracellular proteins were originally identified as signaling adaptors that bind directly to the cytoplasmic regions of receptors of the TNF-R superfamily. The past decade has witnessed rapid expansion of receptor families identified to employ TRAFs for signaling. These include Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), T cell receptor, IL-1 receptor family, IL-17 receptors, IFN receptors and TGFβ receptors. In addition to their role as adaptor proteins, most TRAFs also act as E3 ubiquitin ligases to activate downstream signaling events. TRAF-dependent signaling pathways typically lead to the activation of nuclear factor-κBs (NF-κBs), mitogen-activated protein kinases (MAPKs), or interferon-regulatory factors (IRFs). Compelling evidence obtained from germ-line and cell-specific TRAF-deficient mice demonstrates that each TRAF plays indispensable and non-redundant physiological roles, regulating innate and adaptive immunity, embryonic development, tissue homeostasis, stress response, and bone metabolism. Notably, mounting evidence implicates TRAFs in the pathogenesis of human diseases such as cancers and autoimmune diseases, which has sparked new appreciation and interest in TRAF research. This review presents an overview of the current knowledge of TRAFs, with an emphasis on recent findings concerning TRAF molecules in signaling and in human diseases.

Plant sterols as anticancer nutrients: evidence for their role in breast cancer

While many factors are involved in the etiology of cancer, it has been clearly established that diet significantly impacts one’s risk for this disease. More recently, specific food components have been identified which are uniquely beneficial in mitigating the risk of specific cancer subtypes. Plant sterols are well known for their effects on blood cholesterol levels, however research into their potential role in mitigating cancer risk remains in its infancy. As outlined in this review, the cholesterol modulating actions of plant sterols may overlap with their anti-cancer actions. Breast cancer is the most common malignancy affecting women and there remains a need for effective adjuvant therapies for this disease, for which plant sterols may play a distinctive role.

Far-field photostable optical nanoscopy (PHOTON) for real-time super-resolution single-molecular imaging of signaling pathways of single live cells

Cellular signaling pathways play crucial roles in cellular functions and design of effective therapies. Unfortunately, study of cellular signaling pathways remains formidably challenging because sophisticated cascades are involved, and a few molecules are sufficient to trigger signaling responses of a single cell. Here we report the development of far-field photostable-optical-nanoscopy (PHOTON) with photostable single-molecule-nanoparticle-optical-biosensors (SMNOBS) for mapping dynamic cascades of apoptotic signaling pathways of single live cells in real-time at single-molecule (SM) and nanometer (nm) resolutions. We have quantitatively imaged single ligand molecules (tumor necrosis factor α, TNFα) and their binding kinetics with their receptors (TNFR1) on single live cells; tracked formation and internalization of their clusters and their initiation of intracellular signaling pathways in real-time; and studied apoptotic signaling dynamics and mechanisms of single live cells with sufficient temporal and spatial resolutions. This study provides new insights into complex real-time dynamic cascades and molecular mechanisms of apoptotic signaling pathways of single live cells. PHOTON provides superior imaging and sensing capabilities and SMNOBS offer unrivaled biocompatibility and photostability, which enable probing of signaling pathways of single live cells in real-time at SM and nm resolutions.