IL-6 increases MMP-13 expression and motility in human chondrosarcoma cells

Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions

Natural products with health benefits, nutraceuticals, have shown considerable promise in many studies; however, this potential has yet to translate into widespread clinical use for any condition. Notably, many drugs currently on the market, including the first analgesic aspirin, are derived from plant extracts, emphasizing the historical significance of natural products in drug development. Curcumin and resveratrol, well-studied nutraceuticals, have excellent safety profiles with relatively mild side effects. Their long history of safe use and the natural origins of numerous drugs contrast with the unfavorable reputation associated with nutraceuticals. This review aims to explore the nutraceutical potential for treating pseudoachondroplasia, a rare dwarfing condition, by relating the mechanisms of action of curcumin and resveratrol to molecular pathology. Specifically, we will examine the curcumin and resveratrol mechanisms of action related to endoplasmic reticulum stress, inflammation, oxidative stress, cartilage health, and pain. Additionally, the barriers to the effective use of nutraceuticals will be discussed. These challenges include poor bioavailability, variations in content and purity that lead to inconsistent results in clinical trials, as well as prevailing perceptions among both the public and medical professionals. Addressing these hurdles is crucial to realizing the full therapeutic potential of nutraceuticals in the context of pseudoachondroplasia and other health conditions that might benefit.

Early Resveratrol Treatment Mitigates Joint Degeneration and Dampens Pain in a Mouse Model of Pseudoachondroplasia (PSACH)

Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol's therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented.

Evidence of a role for interleukin-6 in anoikis resistance in oral squamous cell carcinoma

In an endeavour to understand metastasis from oral squamous cell carcinomas, we characterised the metastatic potential of a human tongue derived cell line (SCC-4 cells) and compared this phenotype to pre-cancerous dysplastic oral keratinocyte (DOK) cells derived from human tongue and primary gingival keratinocytes (PGK). We demonstrate that SCC-4 cells constitutively synthesize and release significant amounts of IL-6, a process that is enhanced by the addition of the TLR2/TLR6 agonist, Pam2CSK4. The expression of TLR2/6 and IL-6Ra/gp130 receptors was also confirmed in SCC-4 cells. Cancerous SCC-4 human tongue cells also have a classic EMT profile, unlike precancerous human tongue DOK cells. We also established that IL-6 is driving anoikis resistance in an autocrine fashion and that anti-IL-6 neutralising antibodies, anti-IL-6 receptor antibodies and anti-TLR2 receptor antibodies inhibit anoikis resistance in cancerous SCC-4 human tongue cells. The data suggest a promising role for anti-IL-6 receptor antibody and anti-TLR2 receptor antibody treatment for oral cancer.

Microbial Associations with Pancreatic Cancer: A New Frontier in Biomarkers

Simple Summary

Pancreatic cancer (PC) continues to be characterized by high morbidity and mortality, owing to the fact, among others, that it is often diagnosed at late stages. Thus far, the search for reliable biomarkers has failed. A number of recent studies have found that there are differences in the microbiota between patients with PC and their healthy counterparts. These differences extend to specific anatomical locations such as the oral cavity, the gastrointestinal tract, and the pancreas itself. The purpose of this review is to outline some of the main differences in the bacterial and fungal populations between patients with PC and their healthy counterparts that have recently come to light. Additionally, the present review aims to highlight the mechanisms underlying the aforementioned microbial associations with PC.

Abstract

Pancreatic cancer (PC) remains a global health concern with high mortality and is expected to increase as a proportion of overall cancer cases in the coming years. Most patients are diagnosed at a late stage of disease progression, which contributes to the extremely low 5-year survival rates. Presently, screening for PC remains costly and time consuming, precluding the use of widespread testing. Biomarkers have been explored as an option by which to ameliorate this situation. The authors conducted a search of available literature on PubMed to present the current state of understanding as it pertains to the use of microbial biomarkers and their associations with PC. Carriage of certain bacteria in the oral cavity (e.g., Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Streptococcus sp.), gut (e.g., Helicobacter pylori, Synergistetes, Proteobacteria), and pancreas (e.g., Fusobacterium sp., Enterobacteriaceae, Pseudomonadaceae) has been associated with an increased risk of developing PC. Additionally, the fungal genus Malassezia has likewise been associated with PC development. This review further outlines potential oncogenic mechanisms involved in the microbial-associated development of PC.

TGFβ1-Induced Transglutaminase-2 Triggers Catabolic Response in Osteoarthritic Chondrocytes by Modulating MMP-13

BACKGROUND

Transforming growth factor beta 1 (TGFβ1) plays an essential role in maintaining cartilage homeostasis. TGFβ1 is known to upregulate anabolic processes in articular cartilage, but the role of TGFβ1 in chondrocyte catabolism remains unclear. Thus, we examined whether TGFβ1 increases catabolic processes in the osteoarthritic joint via transglutaminase 2 (TG2). In this study, we investigated whether interplay between TGFβ1 and TG2 mediates chondrocyte catabolism and cartilage degeneration in osteoarthritis.

METHODS

To investigate the role of TGFβ1 and TG2 in osteoarthritis, we performed immunostaining to measure the levels of TGFβ1 and TG2 in 6 human non-osteoarthritic and 16 osteoarthritic joints. We conducted quantitative reverse transcription polymerase chain reaction and western blot analysis to investigate the relationship between TGFβ1 and TG2 in chondrocytes and determined whether TG2 regulates the expressions of matrix metalloproteinase (MMP)-13, type II, and type X collagen. We also examined the extent of cartilage degradation after performing anterior cruciate ligament transection (ACLT) and destabilization of the medial meniscus (DMM) surgery in TG2 knock-out mice.

RESULTS

We confirmed the overexpression of TGFβ1 and TG2 in human osteoarthritic cartilage compared with non-osteoarthritic cartilage. TGFβ1 treatment significantly increased the expression of TG2 via p38 and ERK activation. TGFβ1-induced TG2 also elevated the level of MMP-13 and type X collagen via NF-κB activation in chondrocytes. Cartilage damage after ACLT and DMM surgery was less severe in TG2 knock-out mice compared with wild-type mice.

CONCLUSION

TGFβ1 modulated catabolic processes in chondrocytes in a TG2-dependent manner. TGFβ1-induced TG2 might be the therapeutic target for treating cartilage degeneration and osteoarthritis.

PLD1 promotes tumor invasion by regulation of MMP-13 expression via NF-κB signaling in bladder cancer

Invasion of bladder cancer (BC) cells from the mucosa into the muscle layer is canonical for BC progression while phospholipase D isoform 1 (PLD1) is known to mediate development of cancer through phosphatidic acid (PA) production. We therefore used in silico, in vitro and in vivo approaches to detail the effect of PLD1 on BC invasion. In BC patients, higher levels of PLD1 expression were associated with poor prognoses. PLD1 knockdown significantly suppressed cellular invasion by human BC cells and matrix metalloproteinase-13 (MMP-13) was observed to mediate this effect. In our mouse bladder carcinogenesis model, the development of invasive BCs was suppressed by PLD1 knockout and a global transcriptomic analysis in this model indicated MMP-13 as a potential tumor invasion gene with NF-κB (nuclear factor-kB) as its transcriptional regulator. Furthermore, PA administration increased MMP-13 expression in line with NF-κB p65 phosphorylation levels. Collectively, we demonstrate that PLD1 promotes tumor invasion of BC by regulation of MMP-13 expression through the NF-κB signaling pathway and that PLD1 might be a potential therapeutic target to prevent clinical progression in BC patients.

Melatonin impedes prostate cancer metastasis by suppressing MMP-13 expression

Prostate cancer has high metastatic potential. Men with higher urinary levels of the sleep hormone melatonin are much less likely to develop advanced prostate cancer compared with men with lower levels of melatonin. Melatonin has shown anticancer activity in experimental investigations. Nevertheless, the therapeutic effect of melatonin in metastatic prostate cancer has largely remained a mystery. Analyses of Gene Expression Omnibus data and human tissue samples indicated that levels of matrix metallopeptidase 13 (MMP-13) expression are higher in prostate cancer patients than in healthy cancer-free individuals. Mechanistic investigations revealed that melatonin inhibits MMP-13 expression and the migratory and invasive capacities of prostate cancer cells via the MT1 receptor and the phospholipase C, p38, and c-Jun signaling cascades. Importantly, tumor growth rate and metastasis to distant organs were suppressed by melatonin in an orthotopic prostate cancer model. This is the first demonstration showing that melatonin impedes metastasis of prostate cancer by suppressing MMP-13 expression in both in vitro and in vivo models. Thus, melatonin is promising in the management of prostate cancer metastasis and deserves to undergo clinical investigations.

S1P promotes IL-6 expression in osteoblasts through the PI3K, MEK/ERK and NF-κB signaling pathways

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease, in which the immune system attacks joint tissue. Interleukin (IL)-6 is a key proinflammatory cytokine in RA progression. Sphingosine-1-phosphate (S1P), a platelet-derived lysophospholipid mediator, reportedly regulates osteoimmunology. Here, we examined the effects of S1P on IL-6 expression in osteoblasts. Our results and records from the Gene Expression Omnibus (GEO) database demonstrate higher levels of IL-6 in patients with RA compared with those with osteoarthritis. Stimulation of osteoblasts with S1P increased mRNA and protein expression of IL-6. PI3K, MEK, ERK and NF-κB inhibitors and their small interfering RNAs (siRNAs) reduced S1P-promoted IL-6 expression. S1P also facilitated PI3K, MEK/ERK and NF-κB signaling cascades. Our results indicate that S1P promotes the expression of IL-6 in osteoblasts via the PI3K, MEK/ERK and NF-κB signaling pathways.

Sphingosine-1-phosphate promotes PDGF-dependent endothelial progenitor cell angiogenesis in human chondrosarcoma cells

The malignant bone tumors that are categorized as chondrosarcomas display a high potential for metastasis in late-stage disease. Higher-grade chondrosarcomas contain higher levels of expression of platelet-derived growth factor (PDGF) and its receptor. The phosphorylation of sphingosine by sphingosine kinase enzymes SphK1 and SphK2 generates sphingosine-1-phosphate (S1P), which inhibits human chondrosarcoma cell migration, while SphK1 overexpression suppresses lung metastasis of chondrosarcoma. We sought to determine whether S1P mediates levels of PDGF-A expression and angiogenesis in chondrosarcoma. Surprisingly, our investigations found that treatment of chondrosarcoma cells with S1P and transfecting them with SphK1 cDNA increased PDGF-A expression and induced angiogenesis of endothelial progenitor cells (EPCs). Ras, Raf, MEK, ERK and AP-1 inhibitors and their small interfering RNAs (siRNAs) inhibited S1P-induced PDGF-A expression and EPC angiogenesis. Our results indicate that S1P promotes the expression of PDGF-A in chondrosarcoma via the Ras/Raf/MEK/ERK/AP-1 signaling cascade and stimulates EPC angiogenesis.

Continuous low-intensity ultrasound attenuates IL-6 and TNFα-induced catabolic effects and repairs chondral fissures in bovine osteochondral explants

BACKGROUND

Cartilage repair outcomes are compromised in a pro-inflammatory environment; therefore, the mitigation of pro-inflammatory responses is beneficial. Treatment with continuous low-intensity ultrasound (cLIUS) at the resonant frequency of 5 MHz is proposed for the repair of chondral fissures under pro-inflammatory conditions.

METHODS

Bovine osteochondral explants, concentrically incised to create chondral fissures, were maintained under cLIUS (14 kPa (5 MHz, 2.5 Vpp), 20 min, 4 times/day) for a period of 28 days in the presence or absence of cytokines, interleukin-6 (IL-6) or tumor necrosis factor (TNF)α. Outcome assessments included histological and immunohistochemical staining of the explants; and the expression of catabolic and anabolic genes by qRT-PCR in bovine chondrocytes. Cell migration was assessed by scratch assays, and by visualizing migrating cells into the hydrogel core of cartilage-hydrogel constructs.

RESULTS

Both in the presence and absence of cytokines, higher percent apposition along with closure of fissures were noted in cLIUS-stimulated explants as compared to non-cLIUS-stimulated explants on day 14. On day 28, the percent apposition was not significantly different between unstimulated and cLIUS-stimulated explants exposed to cytokines. As compared to non-cLIUS-stimulated controls, on day 28, cLIUS preserved the distribution of proteoglycans and collagen II in explants despite exposure to cytokines. cLIUS enhanced the cell migration irrespective of cytokine treatment. IL-6 or TNFα-induced increases in MMP13 and ADAMTS4 gene expression was rescued by cLIUS stimulation in chondrocytes. Under cLIUS, TNFα-induced increase in NF-κB expression was suppressed, and the expression of collagen II and TIMP1 genes were upregulated.

CONCLUSION

cLIUS repaired chondral fissures, and elicited pro-anabolic and anti-catabolic effects, thus demonstrating the potential of cLIUS in improving cartilage repair outcomes.

Oxaprozin: A new hope in the modulation of matrix metalloproteinase 9 activity

Oxaprozin (4,5-diphenyl-2-oxazolepropionic acid) is a non-steroidal, analgesic and antipyretic propionic acid derivative, whose activity in treating inflammatory disorders is well known. The aim of this study was to investigate the ability of oxaprozin to modulate the activity of matrix metalloproteinase 9 (MMP-9), a zinc-dependent endopeptidase involved in a wide range of physiological and pathological events associated with extracellular matrix (ECM) remodelling. The interaction between oxaprozin and MMP-9 was firstly investigated in silico by molecular docking and analysis with LIGPLOT software. Subsequently, the potential inhibitory activity of oxaprozin against MMP-9 and the possible mechanism of the ligand-enzyme interaction were investigated in vitro. Taking into account the in silico findings, MMP-9 can be considered a potential target of oxaprozin, which seems to be able to chelate the catalytic zinc ion through the nitrogen of the oxazole ring and the carboxylate moiety. Moreover, one of the phenyl rings interact with the S1' inhibitor-binding pocket through hydrophobic interaction. Gelatin zymography and enzymatic inhibition assay confirmed the potential role of oxaprozin as a competitive inhibitor of MMP-9. These observations sound particularly interesting if we consider the pathological role of MMP-9, especially evident in inflammatory conditions and cancer. This work may represent a starting point to improve the understanding of the role of oxaprozin, as well as its structural analogues, in modulating the MMP-9 function.

Thrombospondin 2 promotes tumor metastasis by inducing matrix metalloproteinase-13 production in lung cancer cells

Thrombospondin (TSP)-2, a matricellular glycoprotein of the TSP family, regulates multiple biological functions, including proliferation, angiogenesis, cell adhesion, and extracellular matrix (ECM) modeling. The clinical relevance of TSP-2 has been explored in many different cancers. TSP-2 expression levels vary between different cancer types, and their role in tumor progression remains controversial. Although previous studies have reported higher serum TSP-2 levels in patients with non-small cell lung cancer, the role of TSP-2 in lung cancer progression remains to be addressed. A total of 585 lung adenocarcinoma datasets, including mRNA sequencing and clinical data, were retrieved from The Cancer Genome Atlas (TCGA). Forty paired adjacent normal tissues and lung tumor tissue datasets were used to examine TSP-2 expression levels. Tumor microarray were performed with immunohistochemical staining to examine TSP-2 expression in lung cancer patients. Transwell migration assay, quantitative real-time PCR and Western blot were used to investigate molecular mechanism of TSP-2 in lung cancer cell. TSP-2 promotes matrix metalloproteinase-13 (MMP-13) expression, cell migration, and cell invasion by mediating integrin αvβ3/FAK/Akt/NF-κB signal transduction. Using TSP-2 knockdown stable cell lines, we found that TSP-2 knockdown reduces MMP-13 expression and cell mobility. When we manipulated the tumor tissue microarray and TCGA datasets to investigate the clinical relevance of TSP-2, we found high TSP-2 expression levels in lung cancer specimens. The present study demonstrates that TSP-2 regulates cell mobility through MMP-13 expression in lung cancer cells. In addition, TSP-2 expression was associated with MMP-13 expression and poor prognosis in lung cancer. TSP-2 may therefore be a promising novel target for lung cancer treatment.

Endothelin-1 promotes epithelial-mesenchymal transition in human chondrosarcoma cells by repressing miR-300

Chondrosarcoma is a malignant tumor of mesenchymal origin predominantly composed of cartilage-producing cells. This type of bone cancer is extremely resistant to radiotherapy and chemotherapy. Surgical resection is the primary treatment, but is often difficult and not always practical for metastatic disease, so more effective treatments are needed. In particular, it would be helpful to identify molecular markers as targets for therapeutic intervention. Endothelin-1 (ET-1), a potent vasoconstrictor, has been shown to enhance chondrosarcoma angiogenesis and metastasis. We report that ET-1 promotes epithelial–mesenchymal transition (EMT) in human chondrosarcoma cells. EMT is a key pathological event in cancer progression, during which epithelial cells lose their junctions and apical-basal polarity and adopt an invasive phenotype. Our study verifies that ET-1 induces the EMT phenotype in chondrosarcoma cells via the AMP-activated protein kinase (AMPK) pathway. In addition, we show that ET-1 increases EMT by repressing miR-300, which plays an important role in EMT-enhanced tumor metastasis. We also show that miR-300 directly targets Twist, which in turn results in a negative regulation of EMT. We found a highly positive correlation between ET-1 and Twist expression levels as well as tumor stage in chondrosarcoma patient specimens. Therefore, ET-1 may represent a potential novel molecular therapeutic target in chondrosarcoma metastasis.

Tumor-derived exosomes educate dendritic cells to promote tumor metastasis via HSP72/HSP105-TLR2/TLR4 pathway

How the tumor microenvironment educates dendritic cells (DCs) to promote tumorigenesis remains largely unknown, and the role of tumor-derived exosomes (TEXs) in tumorigenesis is controversial. Here, we report that in addition to the activation of DCs, TEXs induce DCs to produce increased interleukin-6 (IL-6), which dramatically promotes tumor invasion by increasing signal transducer and activator of transcription 3 (STAT3)-dependent matrix metalloproteinases 9 transcription activity in tumor cells. HSP72 and HSP105 on the TEX surface induce IL-6 secretion of DCs in a TLR2- and TLR4-dependent manner. In addition, HSP72 and HSP105 are predominantly present on exosomes from sera of tumor patients but not healthy people, indicating their value in tumor prediction. Furthermore, TEXs are powerful activators of DCs, and the depletion of IL-6 converts TEXs from tumor promoters to tumor inhibitors in vivo. Therefore, our results reveal a novel mechanism for the TEX-mediated education of DCs and shed light on the conundrum that TEXs present by playing dual roles in tumorigenesis.

Cancer Cytokines and the Relevance of 3D Cultures for Studying Those Implicated in Human Cancers

Cancers are complex conditions and involve several factors for oncogenesis and progression. Of the various factors influencing the physiology of cancers, cytokines are known to play significant roles as mediators of functions. Intricate cytokine networks have been identified in cancers and interest in cytokines associated with cancers has been gaining ground. Of late, some of these cytokines are even identified as potential targets for cancer therapy apart from a few others such as IL-6 being identified as markers for disease prognosis. Of the major contributors to cancer research, cancer cell lines occupy the top slot as the most widely used material in vitro. In vitro cell cultures have seen significant evolution by the introduction of 3-dimensional (3D) culture systems. 3D cell cultures are now widely accepted as excellent material for cancer research which surpass the traditional monolayer cultures. Cancer research has benefited from 3D cell cultures for understanding the various hallmarks of cancers. However, the potential of these culture systems are still unexploited for cancer cytokine research compared to the other aspects of cancers such as gene expression changes, drug-induced toxicity, morphology, angiogenesis, and invasion. Considering the importance of cancer cytokines, 3D cell cultures can be better utilized in understanding their roles and functions. Some of the possibilities where 3D cell cultures can contribute to cancer cytokine research arise from the distinct morphology of the tumor spheroids, the extracellular matrix (ECM), and the spontaneous occurrence of nutrient and oxygen gradients. Also, the 3D culture models enable one to co-culture different types of cells as a simulation of in vivo conditions, enhancing their utility to study cancer cytokines. We review here the cancer associated cytokines and the contributions of 3D cancer cell cultures for studying cancer cytokines. J. Cell. Biochem. 118: 2544-2558, 2017. © 2017 Wiley Periodicals, Inc.

Induction of MMP‑1 and ‑3 by cyclical mechanical stretch is mediated by IL‑6 in cultured fibroblasts of keratoconus

In order to understand the effect of mechanical stretch on corneal extracellular matrix remodeling, human keratoconus fibroblasts (HKCFBs) were subjected to cyclic stretch in vitro and the expression of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), and inflammatory cytokines were evaluated. HKCFBs were seeded into a flexible membrane base and subjected to a cyclic stretch regimen of 10% equibiaxial stretch at a stretching frequency of 1 Hz for 6 h using a Flexcell tension unit. An antibody directed against interleukin‑6 (IL‑6 Ab) was used to investigate the roles of IL‑6 on mechanical stretch mediated regulation of MMP in HKCFBs. Culture supernatants were assayed using an enzyme‑linked immunosorbent assay for MMP‑1 and ‑3, TIMP‑1 and ‑2, and IL‑6. Total RNA from the cells was extracted, and quantitative polymerase chain reaction was used to determine mRNA for MMP‑1 and ‑3, TIMP‑1 and ‑2, and IL‑6. In stretched cells, levels of MMP‑1 and ‑3 demonstrated an increase compared with unstretched cells, but levels of TIMP‑1, and ‑2 revealed a decrease. Mechanical stretch significantly increased the mRNA expression and protein synthesis of IL‑6 compared with unstretched cells. IL‑6 induced MMP‑1 and ‑3 expression, whereas no significant effects were observed in levels of TIMP‑1 and ‑2 compared with the untreated control groups. Additionally, the IL‑6 Ab markedly inhibited the stretch‑induced increase in MMP‑1 and ‑3 in culture supernatants in a dose‑dependent manner. No significant differences in TIMP‑1 and ‑2 protein levels were detected between stretched cells treated with IL‑6 Ab and stretched cells without IL‑6 Ab treatment. These results indicate that cyclical mechanical stretch augments IL‑6 production and MMP expression, and reduces levels of TIMP in HKCFBs. Thus, it is suggested that IL‑6 mediates the stretch‑induced MMP expression.

Tumor-Activated Mesenchymal Stromal Cells Promote Osteosarcoma Stemness and Migratory Potential via IL-6 Secretion

Osteosarcoma (OS) is an aggressive bone malignancy with a high relapse rate despite combined treatment with surgery and multiagent chemotherapy. As for other cancers, OS-associated microenvironment may contribute to tumor initiation, growth, and metastasis. We consider mesenchymal stromal cells (MSC) as a relevant cellular component of OS microenvironment, and have previously found that the interaction between MSC and tumor cells is bidirectional: tumor cells can modulate their peripheral environment that in turn becomes more favorable to tumor growth through metabolic reprogramming. Here, we determined the effects of MSC on OS stemness and migration, two major features associated with recurrence and chemoresistance. The presence of stromal cells enhanced the number of floating spheres enriched in cancer stem cells (CSC) of the OS cell population. Furthermore, the co-culturing with MSC stimulated the migratory capacity of OS via TGFβ1 and IL-6 secretion, and the neutralizing antibody anti-IL-6 impaired this effect. Thus, stromal cells in combination with OS spheres exploit a vicious cycle where the presence of CSC stimulates mesenchymal cytokine secretion, which in turn increases stemness, proliferation, migration, and metastatic potential of CSC, also through the increase of expression of adhesion molecules like ICAM-1. Altogether, our data corroborate the concept that a comprehensive knowledge of the interplay between tumor and stroma that also includes the stem-like fraction of tumor cells is needed to develop novel and effective anti-cancer therapies.

Interplay between YB-1 and IL-6 promotes the metastatic phenotype in breast cancer cells

Epithelial to mesenchymal transition (EMT) induces cell plasticity and promotes metastasis. The multifunctional oncoprotein Y-box binding protein-1 (YB-1) and the pleiotropic cytokine interleukin 6 (IL-6) have both been implicated in tumor cell metastasis and EMT, but via distinct pathways. Here, we show that direct interplay between YB-1 and IL-6 regulates breast cancer metastasis. Overexpression of YB-1 in breast cancer cell lines induced IL-6 production while stimulation with IL-6 increased YB-1 expression and YB-1 phosphorylation. Either approach was sufficient to induce EMT features, including increased cell migration and invasion. Silencing of YB-1 partially reverted the EMT and blocked the effect of IL-6 while inhibition of IL-6 signaling blocked the phenotype induced by YB-1 overexpression, demonstrating a clear YB-1/IL-6 interdependence. Our findings describe a novel signaling network in which YB-1 regulates IL-6, and vice versa, creating a positive feed-forward loop driving EMT-like metastatic features during breast cancer progression. Identification of signaling partners or pathways underlying this co-dependence may uncover novel therapeutic opportunities.

A Co-Culture Model of Fibroblasts and Adipose Tissue-Derived Stem Cells Reveals New Insights into Impaired Wound Healing After Radiotherapy

External radiation seems to be associated with increased amounts of cytokines and other cellular modulators. Impaired microcirculation and fibrosis are examples of typical long term damage caused by radiotherapy. Adipose tissue-derived stem cells (ASC) are discussed to enhance wound healing, but their role in wounds due to radiotherapy is poorly understood. Normal human fibroblasts (NHF) and ASCs were co-cultured and external radiation with doses from 2-12 Gray (Gy) was delivered. Cell proliferation and mRNA levels of matrix metalloproteinases (MMP1, MMP2 and MMP13) were determined 48 h after irradiation of the co-cultures by qPCR. Additionally, tissue inhibitors of matrix metalloproteinases (TIMP1, TIMP2) were determined by enzyme-linked immunosorbent assay (ELISA). There was a reduction of cell proliferation after external radiation in mono-cultures of NHFs and ASCs compared to controls without irradiation. The co-culture of ASCs and NHFs showed reduced impairment of cell proliferation after external radiation. Gene expression of MMP1 and MMP13 was reduced after external irradiation in NHF. MMP2 expression of irradiated NHFs was increased. In the co-culture setting, MMP1 and MMP2 gene expression levels were upregulated. TIMP1 and TIMP2 protein expression was increased after irradiation in NHFs and their co-cultures with ASCs. ASCs seem to stimulate cell proliferation of NHFs and modulate relevant soluble mediators as well as proteinases after external radiation.

Suppressed invasive and migratory behaviors of SW1353 chondrosarcoma cells through the regulation of Src, Rac1 GTPase, and MMP13

Chondrosarcoma is the second frequent type of primary bone cancer. In response to stress to the endoplasmic reticulum, activation of eIF2α-mediated signaling is reported to induce apoptosis. However, its effects on invasive and migratory behaviors of chondrosarcoma have not been understood. Focusing on potential roles of Src kinase, Rac1 GTPase, and MMP13, we investigated eIF2α-driven regulation of SW1353 chondrosarcoma cells. In particular, we employed two chemical agents (salubrinal, Sal; and guanabenz, Gu) that elevate the level of eIF2α phosphorylation. The result revealed that both Sal and Gu reduced invasion and motility of SW1353 chondrosarcoma cells in a dose dependent manner. Live imaging using a fluorescent resonance energy transfer (FRET) technique showed that Sal and Gu downregulated activities of Src kinase as well as Rac1 GTPase in an eIF2α dependent manner. RNA interference experiments supported an eIF2α-mediated regulatory network in the inhibitory role of Sal and Gu. Partial silencing of MMP13 also suppressed malignant phenotypes of SW1353 chondrosarcoma cells. However, MMP13 was not regulated via eIF2α since administration of Sal but not Gu reduced expression of MMP13. In summary, we demonstrate that eIF2α dependent and independent pathways regulate invasion and motility of SW1353 chondrosarcoma cells, and inactivation of Src, Rac1, and MMP13 by Sal could provide a potential adjuvant therapy for combating metastatic chondrosarcoma cells.

IL6 secreted by Ewing sarcoma tumor microenvironment confers anti-apoptotic and cell-disseminating paracrine responses in Ewing sarcoma cells

Background

The prognosis of patients with Ewing sarcoma (ES) has improved over the course of the last decades. However, those patients suffering from metastatic and recurrent ES still have only poor chances of survival and require new therapeutic approaches. Interleukin-6 (IL6) is a pleiotropic cytokine expressed by immune cells and a great variety of cancer cells. It induces inflammatory responses, enhances proliferation and inhibits apoptosis in cancer cells, thereby promoting chemoresistance.

Methods

We investigated expression of IL6, its receptors and the IL6 signal transduction pathway in ES tumor samples and cell lines applying reverse transcriptase PCR, immunoblot and immunohistochemistry. The impact of IL6 on cell viability and apoptosis in ES cell lines was analyzed by MTT and propidium iodide staining, migration assessed by chorioallantoic membrane (CAM) assay.

Results

Immunohistochemistry proved IL6 expression in the stroma of ES tumor samples. IL6 receptor subunits IL6R and IL6ST were expressed on the surface of ES cells. Treatment of ES cells with rhIL6 resulted in phosphorylation of STAT3. rhIL6 protected ES cells from serum starvation-induced apoptosis and promoted migration. IL6 blood serum levels were elevated in a subgroup of ES patients with poor prognosis.

Conclusions

These data suggest that IL6 contributes to ES tumor progression by increasing resistance to apoptosis in conditions of cellular stress, such as serum starvation, and by promotion of metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1564-7) contains supplementary material, which is available to authorized users.

p16(INK4A) inhibits the pro-metastatic potentials of osteosarcoma cells through targeting the ERK pathway and TGF-β1

Extracellular signal-regulated kinase (ERK) is a downstream component of the evolutionarily conserved mitogen-activated protein kinase-signaling pathway, which controls the expression of a plethora of genes implicated in various physiological processes. This pathway is often hyper-activated by mutations or abnormal extracellular signaling in different types of human cancer, including the most common primary malignant bone tumor osteosarcomas. p16(INK4A) is an important tumor suppressor gene frequently lost in osteosarcomas, and is associated with the progression of these malignancies. We have shown, here, that the ERK1/2 protein kinase is also activated by p16(INK4A) down-regulation in osteosarcoma cells and normal human as well as mouse cells. This inhibitory effect is associated with the suppression of the upstream kinase MEK1/2, and is mediated via the repression of miR-21-5p and the consequent up-regulation of the MEK/ERK antagonist SPRY2 in osteosarcoma cells. Furthermore, we have shown that p16(INK4) inhibits the migration/invasion abilities of these cells through miR-21-5p-dependent inhibition of ERK1/2. In addition, we present clear evidence that p16(INK4) represses the paracrine pro-migratory effect of osteosarcoma cells on stromal fibroblasts through the inhibition of the TGF-β1 expression/secretion. This effect is also ERK1/2-dependent, indicating that in addition to their cell-autonomous actions, p16(INK4) and ERK1/2 have also non-cell-autonomous cancer-related functions. Together, these results indicate that the tumor suppressor p16(INK4) protein represses the carcinogenic process of osteosarcoma cells not only as a cell cycle regulator, but also as a negative regulator of pro-carcinogenic/-metastatic pathways. This indicates that targeting the ERK pathway is of utmost therapeutic value.

Possible contribution of aminopeptidase N (APN/CD13) to migration and invasion of human osteosarcoma cell lines

Osteosarcoma is the most common primary malignancy of the bone. Aminopeptidase N (APN/CD13), a Zn+2-dependent ectopeptidase localized on the cell surface, is widely considered to influence the invasion mechanism. This study explores the potential involvement of APN in migration and invasion of human osteosarcoma cells in vitro using inhi-bitors and activators of APN. Cells treated with APN inhibitor bestatin displayed decreased migration and invasion in a Boyden chamber Transwell assay. Western blotting revealed reduced levels of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathway proteins, reduced phosphorylation of p38, ERK1/2 and JNK and decreased levels of NF-κB. Bestatin treatment also lowered APN, matrix metalloproteinase (MMP)-2 and -9 enzymatic activity and their mRNA expression. Reduced MMP-2 and -9 protein levels were also observed. By comparison, cells treated with cytokine interleukin-6 (IL-6), a stimulator of APN, displayed increased migration and invasion. Western blotting revealed increased levels of MAPK and PI3K pathway proteins, phosphorylated p38, ERK1/2 and JNK, and NF-κB. IL-6 treatment also increased APN and MMP-2 and -9 enzymatic activity. An increase of APN, MMP-2 and -9 mRNA levels, and MMP-2 and -9 protein levels was also observed. Together these experiments reveal potential enzymatic and signalling roles for APN in osteosarcoma and establish a starting point for an in-depth analysis of the role of APN in regulating invasiveness. A deeper knowledge about the regulatory mechanisms of APN may contribute to the development of anti-metastatic therapies.

Inflammation-induced NFATc1-STAT3 transcription complex promotes pancreatic cancer initiation by KrasG12D

Cancer-associated inflammation is a molecular key feature in pancreatic ductal adenocarcinoma. Oncogenic KRAS in conjunction with persistent inflammation is known to accelerate carcinogenesis, although the underlying mechanisms remain poorly understood. Here, we outline a novel pathway whereby the transcription factors NFATc1 and STAT3 cooperate in pancreatic epithelial cells to promote Kras(G12D)-driven carcinogenesis. NFATc1 activation is induced by inflammation and itself accelerates inflammation-induced carcinogenesis in Kras(G12D) mice, whereas genetic or pharmacologic ablation of NFATc1 attenuates this effect. Mechanistically, NFATc1 complexes with STAT3 for enhancer-promoter communications at jointly regulated genes involved in oncogenesis, for example, Cyclin, EGFR and WNT family members. The NFATc1-STAT3 cooperativity is operative in pancreatitis-mediated carcinogenesis as well as in established human pancreatic cancer. Together, these studies unravel new mechanisms of inflammatory-driven pancreatic carcinogenesis and suggest beneficial effects of chemopreventive strategies using drugs that are currently available for targeting these factors in clinical trials.

SIGNIFICANCE

Our study points to the existence of an oncogenic NFATc1-STAT3 cooperativity that mechanistically links inflammation with pancreatic cancer initiation and progression. Because NFATc1-STAT3 nucleoprotein complexes control the expression of gene networks at the intersection of inflammation and cancer, our study has significant relevance for potentially managing pancreatic cancer and other inflammatory-driven malignancies.

Syk/JNK/AP-1 signaling pathway mediates interleukin-6-promoted cell migration in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) typically migrates and metastasizes. Interleukin-6 (IL-6) is a multifunctional cytokine associated with disease status and cancer outcomes. The effect of IL-6 on human OSCC cells, however, is unknown. Here, we showed that IL-6 increased cell migration and Intercellular adhesion molecule-1 (ICAM-1) expression in OSCC cells. Pretreatment of OSCC cells with IL-6R monoclonal antibody (mAb) significantly abolished IL-6-induced cell migration and ICAM-1 expression. By contrast, IL-6-mediated cell motility and ICAM-1 upregulation were attenuated by the Syk and c-Jun N-terminal kinase (JNK) inhibitors. Stimulation of OSCC cells with IL-6 promoted Syk and JNK phosphorylation. Furthermore, IL-6 enhanced AP-1 activity, and the IL-6R mAb, Syk inhibitor, or JNK inhibitor all reduced IL-6-mediated c-Jun phosphorylation, c-Jun binding to the ICAM-1 promoter, and c-Jun translocation into the nucleus. Our results indicate that IL-6 enhances the migration of OSCC cells by increasing ICAM-1 expression through the IL-6R receptor and the Syk, JNK, and AP-1 signal transduction pathways.

Unbiased RNAi screen for hepcidin regulators links hepcidin suppression to proliferative Ras/RAF and nutrient-dependent mTOR signaling

The hepatic hormone hepcidin is a key regulator of systemic iron metabolism. Its expression is largely regulated by 2 signaling pathways: the "iron-regulated" bone morphogenetic protein (BMP) and the inflammatory JAK-STAT pathways. To obtain broader insights into cellular processes that modulate hepcidin transcription and to provide a resource to identify novel genetic modifiers of systemic iron homeostasis, we designed an RNA interference (RNAi) screen that monitors hepcidin promoter activity after the knockdown of 19 599 genes in hepatocarcinoma cells. Interestingly, many of the putative hepcidin activators play roles in signal transduction, inflammation, or transcription, and affect hepcidin transcription through BMP-responsive elements. Furthermore, our work sheds light on new components of the transcriptional machinery that maintain steady-state levels of hepcidin expression and its responses to the BMP- and interleukin-6-triggered signals. Notably, we discover hepcidin suppression mediated via components of Ras/RAF MAPK and mTOR signaling, linking hepcidin transcriptional control to the pathways that respond to mitogen stimulation and nutrient status. Thus using a combination of RNAi screening, reverse phase protein arrays, and small molecules testing, we identify links between the control of systemic iron homeostasis and critical liver processes such as regeneration, response to injury, carcinogenesis, and nutrient metabolism.

Effect of the cytokine levels in serum on osteosarcoma

Osteosarcoma (OS) is the most common malignant bone tumor in patients under 20 years old. Studies have shown that cytokines play important roles in regulating immune responses in OS. In the current study, we investigated the effect of cytokines on OS by assessing serum cytokine profiles. Serum levels of 11 cytokines were measured by multiplex protein arrays in 58 patients with OS and 72 healthy controls. Results showed that serum levels of interleukin 1 receptor antagonist (IL-1Ra), IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α) were significantly increased in patients than in controls (2.5-fold, 2.4-fold, 2.7-fold, and 2.1-fold, respectively). When comparing the expression of cytokines in OS patients with different clinical parameters, cases with osteoblastic subtype revealed increased level of IL-6 than patients with other subtypes (p < 0.05); cases with metastasis demonstrated significantly higher level of TNF-α than those without metastasis (p < 0.05), whereas OS patients whose tumor size were bigger than 8 cm presented elevated levels of IL-8 and TNF-α than those with small tumor size (p < 0.05 and p < 0.05, respectively). These data indicated that IL-1Ra, IL-6, IL-8, and TNF-α were associated with increased risk of OS, in which IL-8 and TNF-α may be further correlated with the progression of this disease.

Tpl2 kinase impacts tumor growth and metastasis of clear cell renal cell carcinoma

Due to the innate high metastatic ability of renal cell carcinoma (RCC), many patients with RCC experience local or systemic relapses after surgical resection. A deeper understanding of the molecular pathogenesis underlying advanced RCC is essential for novel innovative therapeutics. Tumor progression locus 2 (Tpl2), upregulated in various tumor types, has been reported to be associated with oncogenesis and metastatic progression via activation of the MAPK signaling pathway. Herein, the relevance of Tpl2 in tumor growth and metastasis of RCC is explored. Inspection of The Cancer Genome Atlas (TCGA) indicated that Tpl2 overexpression was significantly related to the presence of metastases and poor outcome in clear cell RCC (ccRCC), which is the most aggressive subtype of RCC. Moreover, expression of Tpl2 and CXCR4 showed a positive correlation in ccRCC patients. Depletion of Tpl2 by RNAi or activity by a Tpl2 kinase inhibitor in human ccRCC cells remarkably suppressed MAPK pathways and impaired in vitro cell proliferation, clonogenicity, anoikis resistance, migration, and invasion capabilities. Similarly, orthotopic xenograft growth and lung metastasis were significantly inhibited by Tpl2 silencing. Furthermore, Tpl2 knockdown reduced CXCL12-directed chemotaxis and chemoinvasion accompanied with impaired downstream signaling, indicating potential involvement of Tpl2 in CXCR4-mediated metastasis. Taken together, these data indicate that Tpl2 kinase is associated with and contributes to disease progression of ccRCC.

IMPLICATIONS

Tpl2 kinase activity has prognostic and therapeutic targeting potential in aggressive clear cell renal cell carcinoma.

Interleukin-6 mediates epithelial-stromal interactions and promotes gastric tumorigenesis

Interleukin-6 (IL-6) is a pleiotropic cytokine that affects various functions, including tumor development. Although the importance of IL-6 in gastric cancer has been documented in experimental and clinical studies, the mechanism by which IL-6 promotes gastric cancer remains unclear. In this study, we investigated the role of IL-6 in the epithelial–stromal interaction in gastric tumorigenesis. Immunohistochemical analysis of human gastritis, gastric adenoma, and gastric cancer tissues revealed that IL-6 was frequently detected in the stroma. IL-6–positive cells in the stroma showed positive staining for the fibroblast marker α-smooth muscle actin, suggesting that stromal fibroblasts produce IL-6. We compared IL-6 knockout (IL-6^−/−) mice with wild-type (WT) mice in a model of gastric tumorigenesis induced by the chemical carcinogen N-methyl-N-nitrosourea. The stromal fibroblasts expressed IL-6 in tumors from WT mice. Gastric tumorigenesis was attenuated in IL-6^−/− mice, compared with WT mice. Impaired tumor development in IL-6^−/− mice was correlated with the decreased activation of STAT3, a factor associated with gastric cancer cell proliferation. In vitro, when gastric cancer cell line was co-cultured with primary human gastric fibroblast, STAT3–related genes including COX-2 and iNOS were induced in gastric cancer cells and this response was attenuated with neutralizing anti-IL-6 receptor antibody. IL-6 production from fibroblasts was increased when fibroblasts were cultured in the presence of gastric cancer cell–conditioned media. IL-6 production from fibroblasts was suppressed by an interleukin-1 (IL-1) receptor antagonist and siRNA inhibition of IL-1α in the fibroblasts. IL-1α mRNA and protein were increased in fibroblast lysate, suggesting that cell-associated IL-1α in fibroblasts may be involved. Our results suggest the importance of IL-6 mediated stromal-epithelial cell interaction in gastric tumorigenesis.

HGF and c-Met interaction promotes migration in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a potent capacity for local invasion and causing distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. Hepatocyte growth factor (HGF) has been demonstrated to stimulate cancer proliferation, migration, and metastasis. However, the effect of HGF on migration activity of human chondrosarcoma cells is not well known. Here, we found that human chondrosarcoma tissues demonstrated significant expression of HGF, which was higher than that in normal cartilage. We also found that HGF increased the migration and expression of matrix metalloproteinase (MMP)-2 in human chondrosarcoma cells. c-Met inhibitor and siRNA reduced HGF-increased cell migration and MMP-2 expression. HGF treatment resulted in activation of the phosphatidylinositol 3'-kinase (PI3K)/Akt/PKCδ/NF-κB pathway, and HGF-induced expression of MMP-2 and cell migration was inhibited by specific inhibitors or siRNA-knockdown of PI3K, Akt, PKCδ, and NF-κB cascades. Taken together, our results indicated that HGF enhances migration of chondrosarcoma cells by increasing MMP-2 expression through the c-Met receptor/PI3K/Akt/PKCδ/NF-κB signal transduction pathway.

Interleukin-6 induces vascular endothelial growth factor expression and promotes angiogenesis through apoptosis signal-regulating kinase 1 in human osteosarcoma

Osteosarcoma is characterized by a high malignant and metastatic potential. Angiogenesis is essential for the caner metastasis. Interleukin-6 (IL-6) is a multifunctional cytokine that is associated with the disease status and outcomes of cancers. However, the relationship between IL-6 and vascular endothelial growth factor (VEGF) expression in human osteosarcoma is mostly unknown. Here we found that the IL-6 and VEGF expression was correlated with tumor stage and significantly higher than that in normal bone. Incubation of osteosarcoma cells with IL-6 increased VEGF mRNA and protein expression. Pretreatment of cells with IL-6R antibody reduced IL-6-mediated VEGF production. The apoptosis signal-regulating kinase 1 (ASK1)/p38/AP-1 pathway was activated after IL-6 treatment, and IL-6-induced VEGF expression was abolished by the specific inhibitor and siRNA of ASK1, p38, and AP-1 cascades. Importantly, knockdown IL-6 reduced VEGF expression and abolished osteosarcoma conditional medium-mediated angiogenesis. Taken together, these results indicate that IL-6 occurs through ASK1 and p38, which in turn activates AP-1, resulting in the activations of VEGF expression and contributing the angiogenesis of human osteosarcoma cells.

Toll-like receptor 4 activation in microvascular endothelial cells triggers a robust inflammatory response and cross talk with mononuclear cells via interleukin-6

OBJECTIVE

It is known that toll-like receptor 4 (TLR4) plays an important role in atherosclerosis. Because both microvascular (MIC) and macrovascular (MAC) endothelial cells (ECs) are present in atherosclerotic lesions, the present study compared TLR4-triggered inflammatory response and cross talk with mononuclear cells between MIC and MAC ECs.

METHODS AND RESULTS

ELISA, real-time polymerase chain reaction, and gene expression profiling showed that TLR4 activation by lipopolysaccharide stimulated a much higher expression of inflammatory genes including cytokines, chemokines, growth factors, and adhesion molecules in MIC ECs than MAC ECs. Furthermore, coculture studies showed that TLR4 activation in MIC ECs, but not MAC ECs, induced a cross talk with U937 mononuclear cells through MIC EC-released interleukin-6 to upregulate matrix metalloproteinase-1 expression in U937 cells. To explore molecular mechanisms underlying the different responses to TLR4 activation between MIC and MAC ECs, we showed that MIC ECs had a higher expression of TLR4 and CD14 and a higher TLR4-mediated nuclear factor-kappaB activity than MAC ECs.

CONCLUSIONS

The present study showed that TLR4 activation triggers a more robust inflammatory response in MIC ECs than MAC ECs. Given the importance of inflammatory cytokines and matrix metalloproteinases in plaque rupture, MIC ECs may play a key role in plaque destabilization through a TLR4-dependent mechanism.

A forward loop between glioma and microglia: glioma-derived extracellular matrix-activated microglia secrete IL-18 to enhance the migration of glioma cells

The mediators and cellular effectors of inflammation are important constituents of the local environment of tumors. In some occasions, oncogenic changes induce an inflammatory microenvironment that promotes the progression of tumors. In gliomas, the presence of microglia may represent tumor-related inflammation and microglia activation, and subsequent inflammatory responses may influence tumor growth and metastasis. Here, we found that C6 glioma--but not primary astrocyte-derived extracellular matrix (ECM) could activate microglia, including primary microglia and BV-2 cell line, and activated microglia-secreted interleukin (IL)-18, a potent inflammatory cytokine of the IL-1 family, to promote C6 migration. In addition, by coating purified ECM components, it was found that secretion of IL-18 by activated microglia was enhanced when microglia encountered with fibronectin and vitronectin. Furthermore, IL-18-induced C6 migration and microfilament disassembly were antagonized by iNOS inhibitor, guanylate cyclase inhibitor, and protein kinase G inhibitor. Taken together, these results indicate that IL-18 secreted by microglia, which was activated by C6 glioma-derived ECM, enhanced migration of C6 glioma through NO/cGMP pathway.