Endotoxin induces proliferation of NSCLC in vitro and in vivo: role of COX-2 and EGFR activation

Occupational exposure to endotoxins and small cell lung cancer: a systematic review with meta-analysis

The relationship of occupational exposure to endotoxins with different histologic subtypes of lung cancer has not been established. Our objective was to conduct a systematic review with meta-analysis to assess the effect of exposure to endotoxins on the development of small cell lung cancer (SCLC). A bibliographic search was conducted using MEDLINE, Embase, CENTRAL, and Web of Science databases until December 2022, including all cohort and/or case-control studies that examined occupational exposure to endotoxins and SCLC. Risk of bias was assessed using the U.S. Office of Health Assessment and Translation tool. A random effects model was applied, publication bias were assessed, and a sensitivity analysis was conducted. Four papers were selected for meta-analysis purposes. A total of 144 incident cases of SCLC and 897 population or hospital controls were included. Occupational exposure to endotoxins was considered for textile/leather industry and agricultural sector workers exposed to endotoxins originating from wool, cotton, or leather dust. Except for one study, all investigations were classified as having a low probability of risk of biases. The results of the meta-analysis were not statistically significant (pooled OR: 0.86; 95% CI:0.69-1.08). In addition, neither between-study heterogeneity (I2=0%;p=0.92) nor publication bias was observed (p=0.49). The results of the sensitivity analysis, after including five studies that assessed the risk of SCLC among textile industry and crop/livestock farm workers (not specifically exposed to endotoxins), showed a negative statistically non-significant association and low between-study heterogeneity (pooled OR: 0.90; 95% CI:0.79-1.02; I2=22%;p=0.23). Subjects exposed to occupational exposure to endotoxins seem to exhibit a negative association with the development of SCLC, although the results are not conclusive.

Toll-like receptor-guided therapeutic intervention of human cancers: molecular and immunological perspectives

Toll-like receptors (TLRs) serve as the body's first line of defense, recognizing both pathogen-expressed molecules and host-derived molecules released from damaged or dying cells. The wide distribution of different cell types, ranging from epithelial to immune cells, highlights the crucial roles of TLRs in linking innate and adaptive immunity. Upon stimulation, TLRs binding mediates the expression of several adapter proteins and downstream kinases, that lead to the induction of several other signaling molecules such as key pro-inflammatory mediators. Indeed, extraordinary progress in immunobiological research has suggested that TLRs could represent promising targets for the therapeutic intervention of inflammation-associated diseases, autoimmune diseases, microbial infections as well as human cancers. So far, for the prevention and possible treatment of inflammatory diseases, various TLR antagonists/inhibitors have shown to be efficacious at several stages from pre-clinical evaluation to clinical trials. Therefore, the fascinating role of TLRs in modulating the human immune responses at innate as well as adaptive levels directed the scientists to opt for these immune sensor proteins as suitable targets for developing chemotherapeutics and immunotherapeutics against cancer. Hitherto, several TLR-targeting small molecules (e.g., Pam3CSK4, Poly (I:C), Poly (A:U)), chemical compounds, phytocompounds (e.g., Curcumin), peptides, and antibodies have been found to confer protection against several types of cancers. However, administration of inappropriate doses of such TLR-modulating therapeutics or a wrong infusion administration is reported to induce detrimental outcomes. This review summarizes the current findings on the molecular and structural biology of TLRs and gives an overview of the potency and promises of TLR-directed therapeutic strategies against cancers by discussing the findings from established and pipeline discoveries.

Marine Antimicrobial Peptide Epinecidin-1 Inhibits Proliferation Induced by Lipoteichoic acid and Causes cell Death in non-small cell lung cancer Cells via Mitochondria Damage

Non-small cell lung cancer (NSCLC) is among the deadliest cancers worldwide. Despite the recent introduction of several new therapeutic approaches for the disease, improvements in overall survival and progression-free survival have been minimal. Conventional treatments for NSCLC include surgery, chemotherapy and radiotherapy. Except for surgery, these treatments can impair a patient's immune system, leaving them susceptible to bacterial infections. As such, Staphylococcus aureus infections are commonly seen in NSCLC patients receiving chemotherapy, and a major constituent of the S. aureus cell surface, lipoteichoic acid (LTA), is thought to stimulate NSCLC cancer cell proliferation. Thus, inhibition of LTA-mediated cell proliferation might be a useful strategy for treating NSCLC. Epinecidin-1 (EPI), a marine antimicrobial peptide, exhibits broad-spectrum antibacterial activity, and it also displays anti-cancer activity in glioblastoma and synovial sarcoma cells. Furthermore, EPI has been shown to inhibit LTA-induced inflammatory responses in murine macrophages. Nevertheless, the anti-cancer and anti-LTA activities of EPI and the underlying mechanisms of these effects have not been fully tested in the context of NSCLC. In the present study, we demonstrate that EPI suppresses LTA-enhanced proliferation of NSCLC cells by neutralizing LTA and blocking its effects on toll-like receptor 2 and interleukin-8. Moreover, we show that EPI induces necrotic cell death via mitochondrial damage, elevated reactive oxygen species levels, and disrupted redox balance. Collectively, our results reveal dual anti-cancer activities of EPI in NSCLC, as the peptide not only directly kills cancer cells but it also blocks LTA-mediated enhancement of cell proliferation.

The effects of morphine on vascular cell adhesion molecule 1(VCAM-1) concentration in lung cancer cells

OBJECTIVE

Vascular cell adhesion molecule 1 (VCAM-1) plays an important role in tumour cell adhesion to endothelial cells. Some tumour cells also show aberrant expression of VCAM-1. Toll-like receptor 4 (TLR4) agonists can increase VCAM-1 expression. Morphine, an opioid receptor agonist, is also a TLR4 agonist. In this study, we aimed to evaluate whether morphine increase VCAM-1 expression in a TLR4 dependent manner.

METHODS

A549 Lung cancer cells were treated with different doses of morphine and TLR4 antagonist for 24 and 48 h. TLR4 gene expression was evaluated by real-time PCR and VCAM-1 protein was measured by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

Morphine enhanced mRNA expression of TLR4 and protein level of VCAM-1. TLR4 antagonist returned VCAM-1expression to the normal level.

CONCLUSION

Morphine effects VCAM-1expressions via TLR4 in lung cancer cell line.

Lipopolysaccharide and lipoteichoic acid regulate the PI3K/AKT pathway through osteopontin/integrin β3 to promote malignant progression of non-small cell lung cancer

Background

Lung cancer (LC) is a malignancy with one of the highest mortality rates. Respiratory microbiota is considered to play a key role in the development of LC, but the molecular mechanisms are rarely studied.

Methods

We used lipopolysaccharide (LPS) and lipoteichoic acid (LTA) to study human lung cancer cell lines PC9 and H1299. The gene expression of CXC chemokine ligand (CXCL)1/6, interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The Cell-Counting Kit 8 (CCK-8) was used to analyze cell proliferation. Transwell assays were performed to analyze cell migration ability. Flow cytometry was used to observe cell apoptosis. Western blot and qRT-PCR were used to analyze the expression of secreted phosphoprotein 1 (SPP1), toll-like receptor (TLR)-2/4, and NLR family pyrin domain containing 3 (NLRP3) to determine the mechanism of LPS + LTA. We evaluated the effect of LPS + LTA on cisplatin sensibility by analyzing cell proliferation, apoptosis, and caspase-3/9 expression levels. We observed the proliferation activity, apoptosis, and migration ability of cells in which SPP1 had been transfected small interfering (si) negative control (NC) and integrin β3 siRNA. Then the mRNA expression level and protein expression of PI3K, AKT, and ERK were analyzed. Finally, the nude mouse tumor transplantation model was conducted to verify.

Results

We studied that in two cell lines, the expression level of inflammatory factors in LPS+LTA group was significantly higher than that in single treatment group (P<0.001). We explored LPS + LTA combined treatment group significantly increased the expression of NLRP3 and genes and proteins. LPS + LTA + Cisplatin group could significantly reduce the inhibitory effect of LPS on cell proliferation (P<0.001), reduce the apoptosis rate (P<0.001) and significantly reduce the expression levels of caspase-3/9 (P<0.001) compared with Cisplatin group. Finally, we verified that LPS and LTA could increase osteopontin (OPN)/integrin β3 expression and activate the PI3K/AKT pathway to promote malignant progression of LC in vitro studies.

Conclusions

This study provides a theoretical basis for further exploration of the influence of lung microbiota on NSCLC and the optimization of LC treatment in the future.

Add fuel to the fire: Inflammation and immune response in lung cancer combined with COVID-19

The corona virus disease 2019 (COVID-19) global pandemic has had an unprecedented and persistent impact on oncological practice, especially for patients with lung cancer, who are more vulnerable to the virus than the normal population. Indeed, the onset, progression, and prognosis of the two diseases may in some cases influence each other, and inflammation is an important link between them. The original chronic inflammatory environment of lung cancer patients may increase the risk of infection with COVID-19 and exacerbate secondary damage. Meanwhile, the acute inflammation caused by COVID-19 may induce tumour progression or cause immune activation. In this article, from the perspective of the immune microenvironment, the pathophysiological changes in the lungs and whole body of these special patients will be summarised and analysed to explore the possible immunological storm, immunosuppression, and immune escape phenomenon caused by chronic inflammation complicated by acute inflammation. The effects of COVID-19 on immune cells, inflammatory factors, chemokines, and related target proteins in the immune microenvironment of tumours are also discussed, as well as the potential role of the COVID-19 vaccine and immune checkpoint inhibitors in this setting. Finally, we provide recommendations for the treatment of lung cancer combined with COVID-19 in this special group.

Macrophages Release Extracellular Vesicles of Different Properties and Composition Following Exposure to Nanoparticles

Extracellular vesicles are membrane-bound carriers with complex cargoes, which play a major role in intercellular communication, for instance, in the context of the immune response. Macrophages are known to release extracellular vesicles in response to different stimuli, and changes in their size, number, and composition may provide important insights into the responses induced. Macrophages are also known to be highly efficient in clearing nanoparticles, when in contact with them, and in triggering the immune system. However, little is known about how the nature and composition of the vesicles released by these cells may vary upon nanoparticle exposure. In order to study this, in this work, alveolar-like macrophages were exposed to a panel of nanoparticles with varying surface and composition, including amino-modified and carboxylated polystyrene and plain silica. We previously showed that these nanoparticles induced very different responses in these cells. Here, experimental conditions were carefully tuned in order to separate the extracellular vesicles released by the macrophages several hours after exposure to sub-toxic concentrations of the same nanoparticles. After separation, different methods, including high-sensitivity flow cytometry, TEM imaging, Western blotting, and nanoparticle tracking analysis, were combined in order to characterize the extracellular vesicles. Finally, proteomics was used to determine their composition and how it varied upon exposure to the different nanoparticles. Our results show that depending on the nanoparticles' properties. The macrophages produced extracellular vesicles of varying number, size, and protein composition. This indicates that macrophages release specific signals in response to nanoparticles and overall suggests that extracellular vesicles can reflect subtle responses to nanoparticles and nanoparticle impact on intercellular communication.

Design and optimisation of a small-molecule TLR2/4 antagonist for anti-tumour therapy

In anti-tumour therapy, the toll-like receptor 2/4 (TLR2/4) signalling pathway has been a double-edged sword. TLR2/4 agonists are commonly considered adjuvants for immune stimulation, whereas TLR2/4 antagonists demonstrate more feasibility for anti-tumour therapy under specific chronic inflammatory situations. In individuals with cancer retaliatory proliferation and metastasis after surgery, blocking the TLR2/4 signalling pathway may produce favourable prognosis for patients. Therefore, here, we developed a small-molecule co-inhibitor that targets the TLR2/4 signalling pathway. After high-throughput screening of a compound library containing 14 400 small molecules, followed by hit-to-lead structural optimisation, we finally obtained the compound TX-33, which has effective inhibitory properties against the TLR2/4 signalling pathways. This compound was found to significantly inhibit multiple pro-inflammatory cytokines released by RAW264.7 cells. This was followed by TX-33 demonstrating promising efficacy in subsequent anti-tumour experiments. The current results provide a novel understanding of the role of TLR2/4 in cancer and a novel strategy for anti-tumour therapy.

Concomitant use of analgesics and immune checkpoint inhibitors in non-small cell lung cancer: A pharmacodynamics perspective

The invention of immunotherapy, such as immune checkpoint inhibitors (ICIs) for advanced-stage non-small cell lung cancer (NSCLC), has become a new standard of care for a defined group of NSCLC patients. However, the possible impacts of ICI interactions with analgesics for alleviating cancer-related pain are unclear and lack clinical evidence. Many studies have indicated that opioids detrimentally affect the immune system, possibly harming patients of ongoing immunotherapy. Opioids may repress the immune system in various ways, including impairing T cell function, upregulating immunosuppressor Treg cells, and interrupting intestinal microflora composition that disrupts the entire immune system. Furthermore, opioids can influence tumor progression and metastasis directly as opioid receptors are overexpressed in several types of NSCLC. In contrast, another analgesic acting on cyclooxygenase (COX) inhibition (i.e., NSAIDs) may be a candidate for adjuvant therapy since COX-2 is also expressed in the tumor cells of NSCLC patients. In addition, COX-2 is associated with tumor proliferation and metastasis. Therefore, both prospective and retrospective studies should confirm the advantages and disadvantages of the concurrent use of analgesics and ICIs in a clinical setting.

Mangiferin inhibits lipopolysaccharide-induced epithelial-mesenchymal transition (EMT) and enhances the expression of tumor suppressor gene PER1 in non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is often complicated by pulmonary infection, which affects treatment and prognosis. Bacterial lipopolysaccharide (LPS) is an effective stimulator of inflammatory cytokine production, and previous studies have reported that LPS promotes tumor invasion and metastasis. Mangiferin is a plant-derived C-glucosylxanthone with many biological activities, such as antioxidation and anti-inflammation. This research mainly explored the mechanism of its antitumor activities on LPS-induced A549, NCI-H460, and NCI-H520 NSCLC cells. We determined that mangiferin exhibits growth inhibiting activity against LPS-induced NSCLC cells through the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. In addition, mangiferin reversed the LPS-induced downregulation of E-cadherin (epithelial marker); conversely, it significantly inhibited the expression of raised vimentin (mesenchymal markers). Moreover, the ability of NSCLC cells to migrate, as evidenced by the wound healing and transwell migration assays, and the expression of CXCR4 increased by LPS were significantly repressed by mangiferin. In addition, mangiferin markedly mediated protein levels of PER1 and NLRP3 in LPS-induced NSCLC cells and reduced the secretion of IL-1β. These results indicate that mangiferin is not only a remarkable anti-inflammatory compound but also an antitumor agent; thus, it has the potential for being developed into anti-inflammatory and antitumor drugs in the future.

Relevance of humanized three-dimensional tumor tissue models: a descriptive systematic literature review

Despite numerous advances in tumor screening, diagnosis, and treatment, to date, tumors remain one of the leading causes of death, principally due to metastasis and the physiological damage produced by tumor growth. Among the main limits related to the study of tumor physiology there is the complex and heterogeneity nature of its environment and the absence of relevant, simple and inexpensive models able to mimic the biological processes occurring in patients allowing the correct clinical translation of results. To enhance the understanding of the mechanisms of tumors and to develop and evaluate new therapeutic approaches the set-up of advanced and alternative models is mandatory. One of the more translational approaches seems to be the use of humanized three-dimensional (3D) tissue culture. This model allows to accurately mimic tumor morphology and biology, maintaining the native microenvironment without any manipulation. However, little is still known on the real clinical relevance of these models for the study of tumor mechanisms and for the screening of new therapy. The aim of this descriptive systematic literature review was to evaluate and summarize the current knowledge on human 3D tumor tissue culture models. We reviewed the strategies employed by researchers to set-up these systems, also considering the different approaches and culture conditions used. All these aspects greatly contribute to the existing knowledge on tumors, providing a specific link to clinical scenarios and making the humanized 3D tumor tissue models a more attractive tool both for researchers and clinicians.

Ursolic Acid Protects Against Proliferation and Inflammatory Response in LPS-Treated Gastric Tumour Model and Cells by Inhibiting NLRP3 Inflammasome Activation

Background

Inflammation is considered as one of the hallmarks of cancer development and progression. Ursolic acid (UA) showed strong effects as an anti-inflammatory and antioxidant. However, the anti-cancer effects of ursolic acid require further study.

Methods

This study aimed to investigate the role of ursolic acid in a lipopolysaccharide (LPS)-treated gastric tumour mouse model and in a human gastric carcinoma cell line (BGC-823 cells). This study also aimed to confirm whether ursolic acid can protect against proliferation and the inflammatory response induced by LPS, by inhibiting the activation of the NLRP3 inflammasome via the NF-κB pathway.

Results

The present study demonstrated that ursolic acid significantly attenuated LPS-treated proliferation in a gastric tumour mouse model and the human gastric carcinoma BGC-823 cell line, reduced the expression of the NLRP3 inflammasome and suppressed the release of pro-inflammatory cytokines. In addition, ursolic acid inhibited the LPS-induced activation of NF-κB. Furthermore, the NF-κB pathway regulated the activation of the NLRP3 inflammasome.

Conclusion

In conclusion, these results demonstrated that ursolic acid could suppress proliferation and the inflammatory response in an LPS-induced mouse gastric tumour model and human BGC-823 cells by inhibiting the activation of the NLRP3 inflammasome via the NF-κB pathway. This indicates that ursolic acid can be a potential therapeutic agent for the treatment of gastric cancer.

p62 is Negatively Implicated in the TRAF6-BECN1 Signaling Axis for Autophagy Activation and Cancer Progression by Toll-Like Receptor 4 (TLR4)

Toll-like receptors (TLRs) induce the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and autophagy through the TNF (Tumor necrosis factor) receptor-associated factor 6 (TRAF6)-evolutionarily conserved signaling intermediate in Toll pathways (ECSIT) and TRAF6-BECN1 signaling axes, respectively. Having shown that p62 negatively regulates Toll-like receptor 4 (TLR4)-mediated signaling via TRAF6-ECSIT signaling axis, we herein investigated whether p62 is functionally implicated in the TRAF6-BECN1 signaling axis, thereby regulating cancer cell migration and invasion. p62 interacted with TRAF6 and BECN1, to interrupt the functional associations required for TRAF6-BECN1 complex formation, leading to inhibitions of BECN1 ubiquitination and autophagy activation. Importantly, p62-deficient cancer cells, such as p62-knockdown (p62^KD) SK-HEP-1, p62^KD MDA-MB-231, and p62-knockout (p62^KO) A549 cells, showed increased activation of autophagy induced by TLR4 stimulation, suggesting that p62 negatively regulates autophagy activation. Moreover, these p62-deficient cancer cells exhibited marked increases in cell migration and invasion in response to TLR4 stimulation. Collectively, these results suggest that p62 is negatively implicated in the TRAF6-BECN1 signaling axis, thereby inhibiting cancer cell migration and invasion regulated by autophagy activation in response to TLR4 stimulation.

Regulation of DNA methylation signatures on NF-κB and STAT3 pathway genes and TET activity in cigarette smoke extract-challenged cells/COPD exacerbation model in vitro

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a global health problem. Currently, there is a lack of knowledge about the pathobiology of this disease and available therapies are ineffective. Cigarette smoking is the leading cause of COPD; however, not all smokers develop COPD. Exacerbations of COPD caused by microbes are common and detrimental. Approximately 20-50% of patient exacerbations are caused by bacterial colonization in the lower airways. It is generally accepted that epigenetic mechanisms, especially DNA methylation, play an important role during progression of COPD. Thus, we hypothesized that DNA methylation patterns vary significantly following smoke exposure and during exacerbations caused by bacterial infections. To test our hypothesis, we used an in vitro study model that mimics COPD exacerbations and performed extensive studies to understand the role of CpG promoter methylation of NF-κB and STAT3-mediated pathway genes. Both NF-κB and STAT3 transcription factors play critical roles in orchestrating inflammatory responses during cigarette smoke exposure. In brief, human lung adenocarcinoma cells with type II alveolar epithelium characteristics (A549) were challenged with cigarette smoke extract (CSE) or DMSO (control) followed by a 3-h challenge with bacterial lipopolysaccharide (LPS; from Pseudomonas aeruginosa) prior to the termination of CSE exposure (COPD exacerbation group). The production of cytokines/chemokines, regulation of transcription factors, and DNA methylation of specific genes were then assessed. We also studied changes in the expression and activity of ten-eleven translocases (TETs), the enzymes responsible for DNA demethylation, and assessed their role in regulating DNA methylation in the CSE-challenged group.

RESULTS

There was a significant increase in the release of cytokines/chemokines (IL-8, MCP-1, IL-6 and CCL5) in the COPD exacerbation group as compared to the control group. Hypomethylation of NF-κB-mediated pathway genes correlated with their induction in our COPD exacerbation study model. Further, we observed an important role of TET1/2 in regulating the DNA methylation of NF-κB, STAT3, IKK, and NIK genes and cytokine/chemokine production by A549 cells during CSE challenge.

CONCLUSIONS

Studies to further define the role of TETs in CSE-mediated epigenetic regulation may lead to the development of better and more effective therapeutic intervention strategies for COPD.

Combination of celecoxib and calyculin-A inhibits epithelial-mesenchymal transition in human oral cancer cells

Expression of cyclo-oxygenase-2 (COX-2) and protein phosphatase 2A (PP2A) deactivation occurs frequently in oral squamous cell carcinoma (OSCC). We initially assessed COX-2 and PP2A protein expression in OSCC specimens using immunohistochemical (IHC) staining and western blot analysis. We found strong COX-2 and phosphorylated PP2A (p-PP2A) expression in OSCC samples. No significant difference in total PP2A expression was observed between cancer and nontumor tissues. The effect of combining COX-2 inhibitor and celecoxib (CXB) with the PP2A inhibitor, calyculin-A (CLA) on the OSCC cell line, HSC3, was evaluated in vitro. We found that a combination of 1 nM CLA and 50 µM CXB significantly inhibited cell viability, and migration and invasion of HSC3 cells. Western blots for AKT, p-AKT, ERK, p-ERK, E-cadherin, vimentin and β-catenin were conducted after treatment with CXB and/or CLA. Increased E-cadherin and decreased β-catenin expression were found in CXB or CLA treated hsc-3 cells, whereas the combined CXB and CLA treatment showed no difference in E-cadherin or β-catenin expression. Our findings suggest that CLA alone was more effective than CXB alone, but not in the combined drug treatment.

Hydroxysafflor yellow A inhibited lipopolysaccharide-induced non-small cell lung cancer cell proliferation, migration, and invasion by suppressing the PI3K/AKT/mTOR and ERK/MAPK signaling pathways

BACKGROUND

Chronic inflammation plays a significant role in the occurrence and development of non-small cell lung cancer (NSCLC). Hydroxysafflor yellow A (HSYA), a chemical compound of the yellow color pigments extracted from the safflower, has been widely used in clinical treatment with positive antioxidation, anti-inflammation, and antitumor effects. However, the role and underlying mechanisms of HYSA on development and progress in inflammation-mediated NSCLC are unknown.

METHODS

Cell counting kit-8, colony formation, EdU, cell apoptosis, wound healing, Transwell migration and invasion, and enzyme-linked immunosorbent assays; flow cytometry; and Western blotting were conducted using human NSCLC cell lines A549 and H1299.

RESULTS

Lipopolysaccharide (LPS) significantly promoted the proliferation and enhanced colony formation of A549 and H1299 cells, while HYSA notably reversed the effects of LPS. HYSA induced apoptosis of LPS-mediated A549 and H1299 cells in a dose dependent manner; and remarkably suppressed migration, invasion, and epithelial-mesenchymal transition (EMT), significantly regulated production of LPS-induced inflammation cytokines, and downregulated protein expression of PI3K/Akt/mTOR and ERK/MAPK signaling pathways in LPS-induced A549 and H1299 cells. Furthermore, PI3K (LY294002) and ERK (SCH772984) inhibitors remarkably inhibited proliferation, migration, invasion, and EMT, and induced apoptosis in LPS-mediated A549 and H1299 cells. These effects were even more obvious in the presence of HYSA and LY294002 or SCH772984 compared to those of either agent alone.

CONCLUSION

HYSA suppressed LPS-mediated proliferation, migration, invasion, and EMT in A549 and H1299 cells by inhibiting the PI3K/Akt/mTOR and ERK/MAPK signaling pathways, indicating that HYSA may be a potential candidate to treat inflammation-mediated NSCLC.

Synthesis & molecular modeling studies of bronchodilatory active indole–pyridine conjugates

Aim: Synthesis of novel bronchodilatory active indole–pyridine conjugates. Results/methodology: Indole–pyridine conjugates (6a–n, 8a–i and 10a–c) were synthesized in a facile pathway through reaction of 2-[(1-alkyl-1H-indol-3-yl)methylene]malononitriles 4a,b with the corresponding ketone-containing compounds (5a–f, 7a–c and 9a,b) in the presence of sodium alkoxide. Single (6l, 8 g) and powder (6k, 8d) x-ray studies supported the structures. Results: Histamine precontracted isolated tracheal rings of guinea pig exhibited the potent bronchodilation properties of 6c (about double-fold potency relative to the standard reference, theophylline). Some of the synthesized conjugates (8d, 6c, 6f and 6e) revealed promising reduction of IL-8 production during lipopolysaccharide-induced airway inflammatory bioassay. Computational studies (3D pharmacophore, 2D-QSAR ‘quantitative structure–activity relationship’) showed high approximations to the bronchodilation properties and explained the parameters controlling biological observations.

Targeting CREB-binding protein overrides LPS induced radioresistance in non-small cell lung cancer cell lines

Non-small cell lung cancer (NSCLC) has a very poor prognosis even when treated with the best therapies available today often including radiation. NSCLC is frequently complicated by pulmonary infections which appear to impair prognosis as well as therapy, whereby the underlying mechanisms are still not known. It was investigated here, whether the bacterial lipopolysaccharides (LPS) might alter the tumor cell radiosensitivity. LPS were found to induce a radioresistance but solely in cells with an active TLR-4 pathway. Proteome profiling array revealed that LPS combined with irradiation resulted in a strong phosphorylation of cAMP response element-binding protein (CREB). Inhibition of CREB binding protein (CBP) by the specific inhibitor ICG-001 not only abrogated the LPS-induced radioresistance but even led to an increase in radiosensitivity. The sensitization caused by ICG-001 could be attributed to a reduction of DNA double-strand break (DSB) repair.

It is shown that in NSCLC cells LPS leads to a CREB dependent radioresistance which is, however, reversible through CBP inhibition by the specific inhibitor ICG-001. These findings indicate that the combined treatment with radiation and CBP inhibition may improve survival of NSCLC patients suffering from pulmonary infections.

TLR4/ROS/miRNA-21 pathway underlies lipopolysaccharide instructed primary tumor outgrowth in lung cancer patients

Activation of Toll-like receptor 4 (TLR4) signaling in human lung cancer with lipopolysaccharide (LPS) enhances tumor progression. However, whether primary human lung cancer outgrowth could respond to LPS and underlying mechanisms are unclear. Here we determined that TLR4 activation with LPS promoted outgrowth of primary human lung cancer cells in vitro and in vivo. Mechanistically, LPS stimulation increased expression levels of microRNA-21 (miR-21) in primary human lung cancer cells. Inhibition of miR-21 blocked the enhanced lung cancer growth induced by LPS in vitro and in vivo. Up-regulation of miR-21 promoted outgrowth of primary human lung cancer. Down-regulation of miR-21 limited primary human lung cancer outgrowth. Further, TLR4 activation in primary human lung cancer cells increased their ROS levels. Scavenge of ROS abrogated the up-regulation of miR-21 in primary human lung cancer cells and attenuated LPS-induced outgrowth. For in vivo relevance, expression of TLR4 was correlated with miR-21 expression and ROS production in freshly isolated, untreated primary human lung cancer cells. These findings demonstrate an essential role of TLR4/ROS/miR-21 pathway in LPS-induced outgrowth of primary human lung cancer. Our study connected a framework of innate signaling, oxidative stress and microRNA in tumor immunity and provided clues for developing new therapeutics for lung cancer.

Gram-negative bacteria facilitate tumor progression through TLR4/IL-33 pathway in patients with non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) accounts for the most cases in clinical lung cancer patients. Patients with NSCLC are often diagnosed in advanced stage and frequently infected with gram-negative bacteria. Pulmonary infection with gram-negative bacteria is the most frequent postoperative complication in NSCLC patients. While accumulating evidence indicate an involvement of gram-negative bacteria in NSCLC progression, the underlying mechanisms remain largely unknown. Herein, we explored the effect of gram-negative bacteria on tumor progression using tumor cells from NSCLC patients. We observed that infection with gram-negative bacteria predicted advanced stages and decreased time interval to recurrence of NSCLC patients. Incubation of NSCLC cells with gram-negative bacteria promoted their growth and metastasis. Mechanistically, gram-negative bacteria activated Toll-like receptor 4 (TLR4) signaling in NSCLC cells, leading to increased mRNA and protein expression of interleukin 33 (IL-33) through MyD88-dependent pathway. Knockdown of IL-33 abrogated the contribution of gram-negative bacteria to NSCLC progression by regulating cancer metabolic activities and stem cell properties. In NSCLC patients, higher TLR4 expression was associated with increased IL-33 expression, Ki-67 proliferation index and CD133 expression in those with gram-negative bacterial infection. These findings shed new light on the molecular mechanisms underlie gram-negative bacteria mediated tumor progression and provide clues for innovative therapeutic explorations for NSCLC patients.

Roles of toll-like receptors: From inflammation to lung cancer progression

Lung cancer is among the most common malignant tumors worldwide, and is characterized by a low survival rate compared with other cancers. Toll-like receptors (TLRs) are highly conserved in evolution and widely expressed on immune cells, where they serve an important role in the innate immune system by evoking inflammatory responses. Evasion of immune destruction is an important hallmark in the development of cancer. There is an established association between chronic inflammation and cancer, with TLRs serving important roles in the immune response against tumor cells. Recently, TLRs have been identified on tumor cells, where their activation may orchestrate the downstream signaling pathways that serve crucial functions in tumorigenesis and tumor progression. The present review summarizes the roles of TLRs as sensors on lung cancer cells that regulate lung cancer progression with regard to cell growth and invasion, angiogenesis and cancer stem cell behavior. This aimed to provide theoretical support for the development of therapies that target TLR signaling pathways for the treatment of lung cancer.

The Role of PGE2 in Alveolar Epithelial and Lung Microvascular Endothelial Crosstalk

Disruption of the blood-air barrier, which is formed by lung microvascular endothelial and alveolar epithelial cells, is a hallmark of acute lung injury. It was shown that alveolar epithelial cells release an unidentified soluble factor that enhances the barrier function of lung microvascular endothelial cells. In this study we reveal that primarily prostaglandin (PG) E₂ accounts for this endothelial barrier-promoting activity. Conditioned media from alveolar epithelial cells (primary ATI-like cells) collected from BALB/c mice and A549 cells increased the electrical resistance of pulmonary human microvascular endothelial cells, respectively. This effect was reversed by pretreating alveolar epithelial cells with a cyclooxygenase-2 inhibitor or by blockade of EP4 receptors on endothelial cells, and in A549 cells also by blocking the sphingosine-1-phosphate₁ receptor. Cyclooxygenase-2 was constitutively expressed in A549 cells and in primary ATI-like cells, and was upregulated by lipopolysaccharide treatment. This was accompanied by enhanced PGE₂ secretion into conditioned media. Therefore, we conclude that epithelium-derived PGE₂ is a key regulator of endothelial barrier integrity via EP4 receptors under physiologic and inflammatory conditions. Given that pharmacologic treatment options are still unavailable for diseases with compromised air-blood barrier, like acute lung injury, our data thus support the therapeutic potential of selective EP4 receptor agonists.

IL-17C mediates the recruitment of tumor-associated neutrophils and lung tumor growth

Chronic obstructive pulmonary disease (COPD) is associated with an increased risk for lung cancer and an aberrant microbiota of the lung. Microbial colonization contributes to chronic neutrophilic inflammation in COPD. Nontypeable Haemophilus influenzae (NTHi) is frequently found in lungs of stable COPD patients and is the major pathogen triggering exacerbations. The epithelial cytokine interleukin-17C (IL-17C) promotes the recruitment of neutrophils into inflamed tissues. The purpose of this study was to investigate the function of IL-17C in the pulmonary tumor microenvironment. We subjected mice deficient for IL-17C (IL-17C^-/-) and mice double deficient for Toll-like receptor 2 and 4 (TLR-2/4^-/-) to a metastatic lung cancer model. Tumor proliferation and growth as well as the number of tumor-associated neutrophils was significantly decreased in IL-17C^-/- and TLR-2/4^-/- mice exposed to NTHi. The NTHi-induced pulmonary expression of IL-17C was dependent on TLR-2/4. In vitro, IL-17C increased the NTHi- and tumor necrosis factor-α-induced expression of the neutrophil chemokines keratinocyte-derived chemokine and macrophage inflammatory protein 2 in lung cancer cells but did not affect proliferation. Human lung cancer samples stained positive for IL-17C, and in non-small cell lung cancer patients with lymph node metastasis, IL-17C was identified as a negative prognostic factor. Our data indicate that epithelial IL-17C promotes neutrophilic inflammation in the tumor microenvironment and suggest that IL-17C links a pathologic microbiota, as present in COPD patients, with enhanced tumor growth.

Lipoteichoic acids from Staphylococcus aureus stimulate proliferation of human non-small-cell lung cancer cells in vitro

Pulmonary infections are frequent complications in lung cancer and may worsen its outcome and survival. Inflammatory mediators are suspected to promote tumor growth in non-small-cell lung cancer (NSCLC). Hence, bacterial pathogens may affect lung cancer growth by activation of inflammatory signalling. Against this background, we investigated the effect of purified lipoteichoic acids (LTA) of Staphylococcus aureus (S. aureus) on cellular proliferation and liberation of interleukin (IL)-8 in the NSCLC cell lines A549 and H226. A549 as well as H226 cells constitutively expressed TLR-2 mRNA. Even in low concentrations, LTA induced a prominent increase in cellular proliferation of A549 cells as quantified by automatic cell counting. In parallel, metabolic activity of A549 cells was enhanced. The increase in proliferation was accompanied by an increase in IL-8 mRNA expression and a dose- and time-dependent release of IL-8. Cellular proliferation as well as the release of IL-8 was dependent on specific ligation of TLR-2. Interestingly, targeting IL-8 by neutralizing antibodies completely abolished the LTA-induced proliferation of A549 cells. The pro-proliferative effect of LTA could also be reproduced in the squamous NSCLC cell line H226. In summary, LTA of S. aureus induced proliferation of NSCLC cell lines of adeno- and squamous cell carcinoma origin. Ligation of TLR-2 followed by auto- or paracrine signalling by endogenously synthesized IL-8 is centrally involved in LTA-induced tumor cell proliferation. Therefore, pulmonary infections may exert a direct pro-proliferative effect on lung cancer growth.

IL-33 signaling fuels outgrowth and metastasis of human lung cancer

IL-33 is a member of IL-1 superfamily that drives production of Th2-related cytokines. Recently, accumulating evidence suggest an involvement of IL-33 in carcinogenesis. Herein, we determine a close correlation of IL-33 expression and cancer progress in patients with non-small-cell lung cancer (NSCLC). Overexpression of IL-33 by transfection with IL-33 expression vector enhances NSCLC outgrowth and metastasis, while genetic knockdown of IL-33 by transfection with IL-33 shRNA limits NSCLC progression. In consistent, IL-33 stimulation of NSCLC cells leads to robust NSCLC outgrowth and metastasis in vitro and in vivo. Mechanically, IL-33-triggered NSCLC progression relies on ST2 receptor and could be abrogated by ST2 blockade. IL-33/ST2 pathway up-regulates membrane glucose transporter 1 (GLUT1) on NSCLC cells, enhancing their glucose uptake and glycolysis. Accordingly, interfering GLUT1 expression dampens IL-33-enhanced glucose uptake and glycolysis in NSCLC cells, thereby abrogates IL-33-induced NSCLC outgrowth and metastasis. In essence, these findings derived from patients' NSCLC cells uncover a new function of IL-33 in NSCLC pathogenesis and identify GLUT1 as a novel target of IL-33 signaling. Block IL-33 is a promising therapeutic strategy to limit NSCLC glycolysis and tumor progression in clinical practice.

Gram-negative bacteria facilitate tumor outgrowth and metastasis by promoting lipid synthesis in lung cancer patients

BACKGROUND

Lung cancer is the leading cause of cancer-related death worldwide. Patients with lung cancer are very frequently present with pulmonary infections, in particular with Gram-negative bacteria. Herein, we investigated the effect of the co-presence of Gram-negative bacteria on outgrowth and metastasis of lung cancer cells in clinical patients.

METHODS

Lung cancer cells were isolated from clinical surgical tissues. Heat-inactivated E. coli was used as Gram-negative bacteria. Tumor outgrowth and invasion in vitro was analyzed with MTT assay and Biocoat Matrigel Invasion Chamber. Tumor growth and metastasis in vivo was evaluated in BALB/c nude mice. Lipid synthesis was evidenced by expressions of FASN and ACC1, as well as BODIPY Fluorophores staining. Block lipid synthesis was performed with C75 as a FAS inhibitor and transfection with ACC1 siRNA. Knockdown of TLR4 and TLR9 signaling was achieved by transfection with specific shRNAs and administration of specific antagonists.

RESULTS

Gram-negative bacteria significantly promoted lung cancer development including growth and metastasis in dose dependent manner. Mechanistically, Gram-negative bacteria activate TLR4 and TLR9 signaling and enhance lipid synthesis in human lung cancer cells. Knockdown of TLR4 and/or TLR9 was able to block Gram-negative bacteria mediated lipid synthesis and lung cancer development. Interference with lipid synthesis efficiently abrogated Gram-negative-bacteria-induced lung cancer development. In lung cancer patients, higher expressions of innate immune receptors, TLR4 and TLR9, were observed in those with Gram-negative infections and associated with the aberrant lipid synthesis that was observed in vitro.

CONCLUSIONS

Pulmonary infections with Gram-negative bacteria lead to aberrant lipid synthesis through TLR4 and TLR9 signaling in lung cancer patients and result in rapid proliferation and metastasis of lung cancer cells. These findings reveal a new mechanism for pulmonary infection-trigged caner development and provide clues for exploring therapeutics for lung cancer patients.

Celecoxib-erlotinib combination delays growth and inhibits angiogenesis in EGFR-mutated lung cancer

Combination treatment for non-small cell lung cancer (NSCLC) is becoming more popular due to the anticipation that it may be more effective than single drug treatment. In addition, there are efforts to genetically screen patients for specific mutations in light of attempting to administer specific anticancer agents that are most effective. In this study, we evaluate the anticancer and anti-angiogenic effects of low dose celecoxib-erlotinib combination in NSCLC in vitro and in vivo. In NSCLC cells harboring epidermal growth factor receptor (EGFR) mutations, combination celecoxib-erlotinib treatment led to synergistic cell death, but there was minimal efficacy in NSCLC cells with wild-type EGFR. In xenograft models, combination treatment also demonstrated greater inhibition of tumor growth compared to individual treatment. The anti-tumor effect observed was secondary to the targeting of angiogenesis, evidenced by decreased vascular endothelial growth factor A (VEGFA) levels and decreased levels of CD31 and microvessel density. Combination treatment targets angiogenesis through the modulation of of the PI3K/AKT and ERK/Raf1-1 pathway in NSCLC with EGFR exon 19 deletions. These findings may have significant clinical implications in patients with tumors harboring EGFR exon 19 deletions as they may be particularly sensitive to this regimen.

MiR-451 suppresses cell proliferation and metastasis in A549 lung cancer cells

Recent study showed that inflammation was related to lung cancer. However, the exact cause of lung inflammation leading to carcinogenesis is unknown. MicroRNAs (miRNAs) are a group of endogenous non-coding small RNAs that regulate the activity of targeted mRNAs by inflammatory response in many diseases. MiR-451 was reported to relate to the development of lung cancer and metastasis of glioma. But the effect of miR-451 on cell proliferation, migration, and invasion of lung cancer is not really clear. In order to explore the molecular mechanism of the occurrence and development of lung cancer, we investigated the effect of human miR-451 on the proliferation, invasion, and metastasis in lung cancer cell line A549. The miR-451 expression construct was generated into pGenesil-1.1 and transfected into A549 cells. Results showed that the recombinant vectors were verified by sequencing. And miR-451 was over-expressed in A549 by real-time RT PCR. Furthermore, the proliferation, invasion, and metastasis of the cells in miR-451 group were inhibited significantly compared with those in control and A549 groups by MTT assay, Transwell invasion assay, and wound-healing assay. And the lung cancer metastasis factors (MMP-2, MMP-9, VEGF, and CXCR4) were decreased in miR-451 group by Western blot. Moreover, it was proved that inflammation-related gene-PSMB8 was a target for miR-451 by bioinformatics analysis and dual-luciferase reporter assay. And the protein expressions of PSMB8 and NOS2 were decreased in miR-451 group compared with those in control and A549 groups. Therefore, our findings indicated that miR-451 related to PSMB8/NOS2 inflammatory factors may suppress the development and migration of lung cancer, providing evidence for the role of miR-451 in lung cancer.

Cigarette smoke-induced disruption of pulmonary barrier and bacterial translocation drive tumor-associated inflammation and growth

Microorganisms have an important role in tumorgenesis by the induction of inflammation and by a direct impact on tumor cells. Chronic obstructive pulmonary disease (COPD) is associated with an increased risk for lung cancer and microbial colonization. We asked whether bacterial pathogens act as tumor promoters during CS-induced pulmonary inflammation. In a metastatic lung cancer (LC) model, Lewis lung carcinoma (LLC) cells were injected in mice to initiate the growth of tumors in the lung. Exposure to the combination of cigarette smoke (CS) and nontypeable Haemophilus influenzae (NTHi) synergistically increased metastatic growth. Lung levels of albumin and LDH, translocation of bacterial factors into tumor tissue, tumor inflammation, and tumor proliferation were significantly increased in mice exposed to CS in combination with NTHi. Bacterial pathogens increased the proliferation of cultured LLC cells and human cancer cell lines. Metastatic growth induced by the exposure to CS in combination with NTHi was reduced in mice deficient for IL-17. Our data provide evidence that CS-induced loss of pulmonary barrier integrity allows bacterial factors to translocate into tumor tissue and to regulate tumor-associated inflammation and tumor proliferation. Translocation of bacterial factors in tumor tissue links CS-induced inflammation with tumor proliferation.

Erlotinib protects against LPS-induced endotoxicity because TLR4 needs EGFR to signal

Several components of the canonical pathway of response to lipopolysaccharide (LPS) are required for the EGF-dependent activation of NFκB. Conversely, the ability of Toll-like Receptor 4 (TLR4) to activate NFκB in response to LPS is impaired by down regulating EGF receptor (EGFR) expression or by using the EGFR inhibitor erlotinib. The LYN proto-oncogene (LYN) is required for signaling in both directions. LYN binds to the EGFR upon LPS stimulation, and erlotinib impairs this association. In mice, erlotinib blocks the LPS-induced expression of tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) and ameliorates LPS-induced endotoxity, revealing that EGFR is essential for LPS-induced signaling in vivo.

CD14 knockdown reduces lipopolysaccharide-induced cell viability and expression of inflammation-associated genes in gastric cancer cells in vitro and in nude mouse xenografts

The present study examined the role of CD14 in the regulation of lipopolysaccharide (LPS)-induced effects on gastric cancer cells. MGC‑803 cells were stably transfected with CD14 short hairpin (sh)RNA and treated with LPS, followed by assessment of cell proliferation, apoptosis and gene expression using a cell counting kit‑8 assay, flow cytometry, reverse transcription‑polymerase chain reaction and western blot analysis, respectively. The cells subjected to CD14 knockdown were treated with 10 g/ml LPS and injected into nude mice to form tumor xenografts. CD14 shRNA‑transfected MGC‑803 cells did not exhibit any significant changes in cell viability compared with the control cells (P>0.05), but cell viability was markedly increased in the wild‑type (WT) + LPS group (P<0.05). In contrast to the WT + LPS group, the cell viability of the sh‑CD14 + LPS group was markedly decreased (P<0.05). In addition, compared with those in the controls, the level of sh‑CD14 cell apoptosis did not change significantly; however, it was markedly reduced in the LPS group. Compared with that in the WT + LPS group, the rate of apoptosis in the sh‑CD14 + LPS group increased to a certain extent, while it remained lower in the control group. In addition, compared with that in the control, the expression of tumor necrosis factor‑α, interleukin (IL)‑1, IL‑6 and IL‑12, and human β‑defensin 2 was significantly increased in the WT + LPS group, while, compared with that in the WT + LPS group, the expression of these genes was markedly reduced in the sh‑CD14 + LPS group (P<0.05). The nude mouse experiments further confirmed the in vitro data, including the finding that LPS promoted the growth of xenografts, but knockdown of CD14 expression reduced the response of tumor cells to LPS treatment. In conclusion, LPS induced cell viability and the release of inflammatory cytokines, but inhibited gastric cancer cell apoptosis. Knockdown of CD14 expression had no significant effect on gastric cancer malignancy, but mediated LPS signal transduction.

Targeting Toll-like receptor 2 inhibits growth of head and neck squamous cell carcinoma

Infection-driven inflammation has been proposed to be involved in the tumorigenesis of head and neck squamous cell carcinoma (HNSCC). Oral HNSCC is often colonized with microbes such as gram-positive bacteria and yeast, where ligands derived from their wall components have been shown to specifically bind to Toll-like receptor 2 (TLR2). Although TLR2 has been described to be expressed in oral HNSCC, its function has not been well characterized. Here, we show the expression of TLR2 in both HNSCC cell lines and primary patient-derived HNSCC xenograft tumors. Activation of TLR2 with a yeast-derived ligand of TLR2, zymosan, promoted organoid formation in an ex vivo model of tumor growth, while blockade with anti-TLR2 antibodies inhibited organoid formation. Zymosan also induced phosphorylation of ERK and the p65 subunit of NF-κB, which was inhibited in the presence of anti-TLR2 antibodies, indicating that this receptor is functional in HNSCC and that the signaling through these pathways is intact. TLR2 blockade also inhibited growth of human xenografted tumors in immunodeficient mice. In summary, our data show that TLR2 is a functional receptor expressed in human HNSCC that plays a direct pro-tumorigenic role, and that it can be therapeutically targeted with blocking antibodies to reduce tumor growth.

LPS promote the odontoblastic differentiation of human dental pulp stem cells via MAPK signaling pathway

Human dental pulp stem cells (hDPSCs) show significant potential for exploitation in novel regeneration strategies, although lack of understanding of their responses to bacterial challenge constrains their application. The present study aimed to investigate whether lipopolysaccharide (LPS), the major pathogenic factor of Gram-negative bacteria, regulates the differentiation of hDPSCs and which intracellular signaling pathways may be involved. LPS treatment significantly promoted the differentiation of hDPSCs demonstrable by increased mineralized nodule formation and mRNA expression of several odontoblastic markers in a dose-dependent manner. While inhibition of TLR4, p38, and ERK signaling markedly antagonized LPS-mediated differentiation of hDPSCs. The inhibition of JNK and NF-κB signaling had no detectable effect on LPS activation of hDPSCs. LPS stimulation resulted in phosphorylation of NF-κB p65, IκB-α, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) in DPSCs in a time-dependent manner, which was markedly suppressed by their specific inhibitors, respectively. Data demonstrated that LPS promoted odontoblastic differentiation of hDPSCs via TLR4, ERK, and P38 MAPK signaling pathways, but not NF-κB signaling.

NADPH oxidase 1-dependent ROS is crucial for TLR4 signaling to promote tumor metastasis of non-small cell lung cancer

Recent evidence demonstrated an enhanced metastasis of non-small cell lung cancer (NSCLC) cells induced by lipopolysaccharide (LPS) stimulation, which reflected an important role of inflammation in tumor progression. However, the underlying mechanisms still remain unclear. Here, we evaluated the potential role of reactive oxygen species (ROS) in Toll-like receptor 4 (TLR4) signaling enhanced NSCLC metastasis. NSCLC cells were isolated from clinical surgical tissues. We found that LPS stimulation of NSCLC cells facilitates their metastasis that was accompanied by increased ROS production and could be abrogated by ROS inhibition. NADPH oxidase was essential for TLR4 signaling-enhanced NSCLC metastasis. Elevated NADPH oxidase 1 (NOX1) expression by LPS stimulation was observed. Blockade of NOX1 with ML171 alleviated enhanced NSCLC metastasis by TLR4 signaling. Enforced NOX1 expression promoted TLR4 signaling-enhanced NSCLC metastasis, while decreased NOX1 expression inhibited TLR4 signaling-enhanced NSCLC metastasis. Further, NOX1 could regulate the expression of CXCR4 and matrix metallopeptidase 9 (MMP9) in NSCLC cells. NOX1 expression in tumor tissues was correlated with TLR4 expression and clinical stages in NSCLC patients. Finally, inhibition of NOX1/ROS prevented enhanced lung tumor burdens of NSCLC by LPS-induced acute lung infection. Our findings demonstrated a crucial role of NOX1-dependent ROS for TLR4 signaling to enhance the metastasis of NSCLC, which could further the understanding of NSCLC pathogenesis and helpful for developing novel therapeutics for NSCLC.

Combined cetuximab and celecoxib treatment exhibits a synergistic anticancer effect on human oral squamous cell carcinoma in vitro and in vivo

The aim of the present study was to evaluate the potency of epidermal growth factor receptor (EGFR) pathway inhibition achieved by combining cetuximab (CET), an anti-EGFR monoclonal antibody, and celecoxib (CXB), a cyclooxygenase-2 (COX-2) inhibitor, in oral squamous cell carcinoma (OSCC) in vitro and in vivo. The OSCC cell line, HSC3, was treated with CET (0-400 µg/ml), CXB (0-40 µM), or a combination of both at a range of concentrations. Cell proliferation, apoptosis, migration and invasion were determined to assess the anticancer effects in vitro. The in vivo effects of CET and CXB on tumor cell growth were examined using an OSCC xenograft nude mouse model. In addition, downstream protein expression levels of EGFR, p-EGFR, PI3K, p-PI3K, AKT and p-Akt were evaluated by western blot analysis. It was found that the combination of low concentrations of CET and CXB significantly suppressed the proliferation, migration and invasion of the HSC3 tumor cells and decreased PEG2 production and VEGF expression in vitro, and inhibited tumor growth in vivo compared to the action of either agent alone. The results also showed that this combination significantly induced apoptosis and increased caspase-3 and caspase-8 activity compared to the action of either agent alone (P<0.01). Furthermore, the combination treatment significantly reduced the expression of p-EGFR, p-PI3K and p-Akt in the HSC3 cell line, which may contribute to the inhibition of tumor growth. Taken together, our findings revealed that the additive combination of CET and CXB is a potential drug candidate for the treatment of OSCC.

Carbon ion radiotherapy of human lung cancer attenuates HIF-1 signaling and acts with considerably enhanced therapeutic efficiency

Carbon ion irradiation is an emerging therapeutic option for various tumor entities. Radiation resistance of solid tumors toward photon irradiation is caused by attenuation of DNA damage in less oxygenated tumor areas and by increased hypoxia-inducible factor (HIF)-1 signaling. Carbon ion irradiation acts independently of oxygen; however, the role of HIF-1 is unclear. We analyzed the effect of HIF-1 signaling after carbon ions in comparison to photons by using biological equivalent radiation doses in a human non-small-cell cancer model. The studies were performed in cultured A549 and H1299 cell lines and in A549 xenografts. Knockdown of HIF-1α in vivo combined with photon irradiation delayed tumor growth (23 vs. 13 d; P<0.05). Photon irradiation induced HIF-1α and target genes, predominantly in oxygenated cells (1.6-fold; P<0.05), with subsequent enhanced tumor angiogenesis (1.7-fold; P<0.05). These effects were not observed after carbon ion irradiation. Micro-DNA array analysis indicated that photons, but not carbon ions, significantly induced components of the mTOR (mammalian target of rapamycin) pathway (gene set enrichment analysis; P<0.01) as relevant for HIF-1α induction. After carbon ion irradiation in vivo, we observed substantially decreased HIF-1α levels (8.9-fold; P<0.01) and drastically delayed tumor growth (P<0.01), an important finding that indicates a higher relative biological effectiveness (RBE) than anticipated from the cell survival data. Taken together, the evidence showed that carbon ions mediate an improved therapeutic effectiveness without tumor-promoting HIF-1 signaling.

Autophagy facilitates TLR4- and TLR3-triggered migration and invasion of lung cancer cells through the promotion of TRAF6 ubiquitination

Autophagy contributes to the pathogenesis of cancer, whereas toll-like receptors (TLRs) also play an important role in cancer development and immune escape. However, little is known about the potential interaction between TLR signaling and autophagy in cancer cells. Here we show that autophagy induced by TLR4 or TLR3 activation enhances various cytokine productions through promoting TRAF6 (TNF receptor-associated factor 6, E3 ubiquitin protein ligase) ubiquitination and thus facilitates migration and invasion of lung cancer cells. Stimulation of TLR4 and TLR3 with lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid [poly(I:C)] respectively triggered autophagy in lung cancer cells. This was mediated by the adaptor protein, toll-like receptor adaptor molecule 1 (TICAM1/TRIF), and was required for TLR4- and TLR3-induced increases in the production of IL6, CCL2/MCP-1 [chemokine (C-C motif) ligand 2], CCL20/MIP-3α [chemokine (C-C motif) ligand 20], VEGFA (vascular endothelial growth factor A), and MMP2 [matrix metallopeptidase 2 (gelatinase A, 72 kDa gelatinase, 72 kDa type IV collagenase)]. These cytokines appeared to be necessary for enhanced migration and invasion of lung cancer cells upon TLR activation. Remarkably, inhibition of autophagy by chemical or genetic approaches blocked TLR4- or TLR3-induced Lys63 (K63)-linked ubiquitination of TRAF6 that was essential for activation of MAPK and NFKB (nuclear factor of kappa light polypeptide gene enhancer in B-cells) pathways, both of which were involved in the increased production of the cytokines. Collectively, these results identify induction of autophagy by TLR4 and TLR3 as an important mechanism that drives lung cancer progression, and indicate that inhibition of autophagy may be a useful strategy in the treatment of lung cancer.

Bacterial Lipopolysaccharides Induce Steroid Sulfatase Expression and Cell Migration through IL-6 Pathway in Human Prostate Cancer Cells

Steroid sulfatase (STS) is responsiblefor the conversion of estrone sulfate to estrone that can stimulate growth in endocrine-dependent tumors such as prostate cancer. Although STS is considered as a therapeutic target for the estrogen-dependent diseases, cellular function of STS are still not clear. Previously, we found that tumor necrosis factor (TNF)-α significantly enhances steroid sulfatase expression in PC-3 human prostate cancer cells through PI3K/Akt-dependent pathways. Here, we studied whether bacterial lipopolysaccharides (LPS) which are known to induce TNF-α may increase STS expression. Treatment with LPS in PC-3 cells induced STS mRNA and protein in concentration- and time-dependent manners. Using luciferase reporter assay, we found that LPS enhanced STS promoter activity. Moreover, STS expression induced by LPS increased PC-3 tumor cell migration determined by wound healing assay. We investigated that LPS induced IL-6 expression and IL-6 increased STS expression. Taken together, these data strongly suggest that LPS induces STS expression through IL-6 pathway in human prostate cancer cells.

Trial Watch: Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette–Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology, we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.