Cisplatin-stimulated murine bone marrow-derived macrophages secrete oncostatin M

Adipose tissue-to-breast cancer crosstalk: Comprehensive insights

The review focuses on mechanistic evidence for the link between obesity and breast cancer. According to the IARC study, there is sufficient evidence that obesity is closely related to a variety of cancers. Among them, breast cancer is particularly disturbed by adipose tissue due to the unique histological structure of the breast. The review introduces the relationship between obesity and breast cancer from two aspects, including factors that promote tumorigenesis or metastasis. We summarize alterations in adipokines and metabolic pathways that contribute to breast cancer development. Breast cancer metastasis is closely related to obesity-induced pro-inflammatory microenvironment, adipose stem cells, and miRNAs. Based on the mechanism by which obesity causes breast cancer, we list possible therapeutic directions, including reducing the risk of breast cancer and inhibiting the progression of breast cancer. We also discussed the risk of autologous breast remodeling and fat transplantation. Finally, the causes of the obesity paradox and the function of enhancing immunity are discussed. Evaluating the balance between obesity-induced inflammation and enhanced immunity warrants further study.

Oncostatin M Receptor-targeted antibodies suppress STAT3 signaling and inhibit ovarian cancer growth

While patients with advanced ovarian cancer may respond initially to treatment, disease relapse is common and nearly 50% of patients do not survive beyond five years, indicating an urgent need for improved therapies. To identify new therapeutic targets, we performed single cell and nuclear RNA-seq dataset analyses on 17 human ovarian cancer specimens, revealing the oncostatin M receptor (OSMR) as highly expressed in ovarian cancer cells. Conversely, oncostatin M (OSM), the ligand of OSMR, was highly expressed by tumor-associated macrophages and promoted proliferation and metastasis in cancer cells. Ovarian cancer cell lines and additional patient samples also exhibited elevated levels of OSMR when compared to other cell types in the tumor microenvironment or to normal ovarian tissue samples. OSMR was found to be important for ovarian cancer cell proliferation and migration. Binding of OSM to OSMR caused OSMR-IL6ST dimerization, which is required to produce oncogenic signaling cues for prolonged STAT3 activation. Human monoclonal antibody clones B14 and B21 directed to the extracellular domain of OSMR abrogated OSM-induced OSMR-IL6ST heterodimerization, promoted the internalization and degradation of OSMR, and effectively blocked OSMR-mediated signaling in vitro. Importantly, these antibody clones inhibited the growth of ovarian cancer cells in vitro and in vivo by suppressing oncogenic signaling through OSMR and STAT3 activation. Collectively, this study provides a proof of principle that anti-OSMR antibody can mediate disruption of OSM-induced OSMR-IL6ST dimerization and oncogenic signaling, thus documenting the pre-clinical therapeutic efficacy of human OSMR antagonist antibodies for immunotherapy in ovarian cancer.

The opposing effects of interferon-beta and oncostatin-M as regulators of cancer stem cell plasticity in triple-negative breast cancer

Background

Highly aggressive, metastatic and therapeutically resistant triple-negative breast cancers (TNBCs) are often enriched for cancer stem cells (CSC). Cytokines within the breast tumor microenvironment (TME) influence the CSC state by regulating tumor cell differentiation programs. Two prevalent breast TME cytokines are oncostatin-M (OSM) and interferon-β (IFN-β). OSM is a member of the IL-6 family of cytokines and can drive the de-differentiation of TNBC cells to a highly aggressive CSC state. Conversely, IFN-β induces the differentiation of TNBC, resulting in the repression of CSC properties. Here, we assess how these breast TME cytokines influence CSC plasticity and clinical outcome.

Methods

Using transformed human mammary epithelial cell (HMEC) and TNBC cell models, we assessed the CSC markers and properties following exposure to OSM and/or IFN-β. CSC markers included CD24, CD44, and SNAIL; CSC properties included tumor sphere formation, migratory capacity, and tumor initiation.

Results

There are three major findings from our study. First, exposure of purified, non-CSC to IFN-β prevents OSM-mediated CD44 and SNAIL expression and represses tumor sphere formation and migratory capacity. Second, during OSM-induced de-differentiation, OSM represses endogenous IFN-β mRNA expression and autocrine/paracrine IFN-β signaling. Restoring IFN-β signaling to OSM-driven CSC re-engages IFN-β-mediated differentiation by repressing OSM/STAT3/SMAD3-mediated SNAIL expression, tumor initiation, and growth. Finally, the therapeutic use of IFN-β to treat OSM-driven tumors significantly suppresses tumor growth.

Conclusions

Our findings suggest that the levels of IFN-β and OSM in TNBC dictate the abundance of cells with a CSC phenotype. Indeed, TNBCs with elevated IFN-β signaling have repressed CSC properties and a better clinical outcome. Conversely, TNBCs with elevated OSM signaling have a worse clinical outcome. Likewise, since OSM suppresses IFN-β expression and signaling, our studies suggest that strategies to limit OSM signaling or activate IFN-β signaling will disengage the de-differentiation programs responsible for the aggressiveness of TNBCs.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1136-x) contains supplementary material, which is available to authorized users.

Mechanism of prostaglandin E2-induced transcriptional up-regulation of Oncostatin-M by CREB and Sp1

Oncostatin-M (OSM) is a pleotropic cytokine belonging to the interleukin-6 family. Differential expression of OSM in response to varying stimuli and exhibiting repertoire of functions in different cells renders it challenging to study the mechanism of its expression. Prostaglandin E₂ (PGE₂) transcriptionally increased osm levels. In silico studies of ∼1 kb upstream of osm promoter region yielded the presence of CRE (cyclic AMP response element)-like sites at the distal end (CRE_osm). Deletion and point mutation of CRE_osm clearly indicated that this region imparted an important role in PGE₂-mediated transcription. Nuclear protein(s) from PGE₂-treated U937 cells, bound to this region, was identified as CRE-binding protein (CREB). CREB was phosphorylated on treatment and was found to be directly associated with CRE_osm The presence of cofactors p300 and CREB-binding protein in the complex was confirmed. A marked decrease in CREB phosphorylation, binding and transcriptional inhibition on treatment with PKA (protein kinase A) inhibitor, H89 (N-[2-[[3-(4-bromophenyl)-2-propenyl]amino]ethyl]-5-soquinolinesulfonamide), revealed the role of phosphorylated CREB in osm transcription. Additionally, other nuclear protein(s) were specifically associated with the proximal GC region (GC_osm) post PGE₂ treatment, later confirmed to be specificity protein 1 (Sp1). Interestingly, Sp1 bound to the proximal osm promoter was found to be associated with phospho-CREB-p300 complex bound to the distal osm promoter. Knockdown of Sp1 abrogated the expression and functionality of OSM. Thus, the present study conclusively proves that these transcription factors, bound at the distal and proximal promoter elements are found to associate with each other in a DNA-dependent manner and both are responsible for the PGE₂-mediated transcriptional up-regulation of Oncostatin-M.

Oncostatin M promotes cancer cell plasticity through cooperative STAT3-SMAD3 signaling

Increasing evidence supports the idea that cancer cell plasticity promotes metastasis and tumor recurrence, resulting in patient mortality. While it is clear that the tumor microenvironment (TME) contributes to cancer cell plasticity, the specific TME factors most actively controlling plasticity remain largely unknown. Here, we performed a screen to identify TME cytokines and growth factors that promote epithelial–mesenchymal plasticity, and acquisition of cancer stem cell (CSC) properties. Of 28 TME cytokines and growth factors tested, we identified Oncostatin M (OSM) as the most potent inducer of mesenchymal/CSC properties. OSM-induced plasticity was Signal Transducer and Activator of Transcription 3 (STAT3)-dependent, and also required a novel intersection with transforming growth factor-β (TGF-β)/SMAD signaling. OSM/STAT3 activation promoted SMAD3 nuclear accumulation, DNA binding and induced SMAD3-dependent transcriptional activity. Suppression of TGF-β receptor activity or ablation of SMAD3 or SMAD4, but not SMAD2, strongly suppressed OSM/STAT3-mediated plasticity. Moreover, removal of OSM or inhibition of STAT3 or SMAD3 resulted in a marked reversion to a non-invasive, epithelial phenotype. We propose that targeted blockade of the STAT3/SMAD3 axis in tumor cells may represent a novel therapeutic approach to prevent the plasticity required for metastatic progression and tumor recurrence.

Potent EMT and CSC Phenotypes Are Induced By Oncostatin-M in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is referred to as a silent killer due to the lack of clear symptoms, a lack of early detection methods, and a high frequency of metastasis at diagnosis. In addition, pancreatic cancer is remarkably resistant to chemotherapy, and clinical treatment options remain limited. The tumor microenvironment (TME) and associated factors are important determinants of metastatic capacity and drug resistance. Here, oncostatin M (OSM), an IL6 cytokine family member, was identified as an important driver of mesenchymal and cancer stem cell (CSC) phenotypes. Furthermore, the generation of cells that harbor mesenchymal/CSC properties following OSM exposure resulted in enhanced tumorigenicity, increased metastasis, and resistance to gemcitabine. OSM induced the expression of ZEB1, Snail (SNAI1), and OSM receptor (OSMR), engaging a positive feedback loop to potentiate the mesenchymal/CSC program. Suppression of JAK1/2 by ruxolitinib prevented STAT3-mediated transcription of ZEB1, SNAI1 and OSMR, as well as the emergence of a mesenchymal/CSC phenotype. Likewise, ZEB1 silencing, by shRNA-mediated knockdown, in OSM-driven mesenchymal/CSC reverted the phenotype back to an epithelial/non-CSC state. Importantly, the generation of cells with mesenchymal/CSC properties was unique to OSM, and not observed following IL6 exposure, implicating OSMR and downstream effector signaling as a distinct target in PDAC. Overall, these data demonstrate the capacity of OSM to regulate an epithelial-mesenchymal transition (EMT)/CSC plasticity program that promotes tumorigenic properties.Implications: Therapeutic targeting the OSM/OSMR axis within the TME may prevent or reverse the aggressive mesenchymal and CSC phenotypes associated with poor outcomes in patients with PDAC. Mol Cancer Res; 15(4); 478-88. ©2017 AACR.

Potent EMT and CSC Phenotypes Are Induced By Oncostatin-M in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is referred to as a silent killer due to the lack of clear symptoms, a lack of early detection methods, and a high frequency of metastasis at diagnosis. In addition, pancreatic cancer is remarkably resistant to chemotherapy, and clinical treatment options remain limited. The tumor microenvironment (TME) and associated factors are important determinants of metastatic capacity and drug resistance. Here, oncostatin M (OSM), an IL6 cytokine family member, was identified as an important driver of mesenchymal and cancer stem cell (CSC) phenotypes. Furthermore, the generation of cells that harbor mesenchymal/CSC properties following OSM exposure resulted in enhanced tumorigenicity, increased metastasis, and resistance to gemcitabine. OSM induced the expression of ZEB1, Snail (SNAI1), and OSM receptor (OSMR), engaging a positive feedback loop to potentiate the mesenchymal/CSC program. Suppression of JAK1/2 by ruxolitinib prevented STAT3-mediated transcription of ZEB1, SNAI1 and OSMR, as well as the emergence of a mesenchymal/CSC phenotype. Likewise, ZEB1 silencing, by shRNA-mediated knockdown, in OSM-driven mesenchymal/CSC reverted the phenotype back to an epithelial/non-CSC state. Importantly, the generation of cells with mesenchymal/CSC properties was unique to OSM, and not observed following IL6 exposure, implicating OSMR and downstream effector signaling as a distinct target in PDAC. Overall, these data demonstrate the capacity of OSM to regulate an epithelial-mesenchymal transition (EMT)/CSC plasticity program that promotes tumorigenic properties.Implications: Therapeutic targeting the OSM/OSMR axis within the TME may prevent or reverse the aggressive mesenchymal and CSC phenotypes associated with poor outcomes in patients with PDAC. Mol Cancer Res; 15(4); 478-88. ©2017 AACR.

STAT3-mediated SMAD3 activation underlies Oncostatin M-induced Senescence

Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent progression toward metastasis. Elevated levels of the Interleukin-6 (IL-6) family cytokine Oncostatin M (OSM) in the breast TME correlate with aggressive, metastatic cancers, increased tumor recurrence, and poor patient prognosis. Paradoxically, OSM engages a tumor-suppressive, Signal Transducer and Activator of Transcription 3 (STAT3)-dependent senescence response in normal and non-transformed human mammary epithelial cells (HMEC). Here, we identify a novel link between OSM-activated STAT3 signaling and the Transforming Growth Factor-β (TGF-β) signaling pathway that engages senescence in HMEC. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented OSM-induced senescence. OSM promoted a protein complex involving activated-STAT3 and SMAD3, induced the nuclear localization of SMAD3, and enhanced SMAD3-mediated transcription responsible for senescence. In contrast, expression of MYC (c-MYC) from a constitutive promoter abrogated senescence and strikingly, cooperated with OSM to promote a transformed phenotype, epithelial-mesenchymal transition (EMT), and invasiveness. Our findings suggest that a novel STAT3/SMAD3-signaling axis is required for OSM-mediated senescence that is coopted during the transformation process to confer aggressive cancer cell properties. Understanding how developing cancer cells bypass OSM/STAT3/SMAD3-mediated senescence may help identify novel targets for future "pro-senescence" therapies aiming to reengage this hidden tumor-suppressive response.

Cancer Stem Cell Plasticity Drives Therapeutic Resistance

The connection between epithelial-mesenchymal (E-M) plasticity and cancer stem cell (CSC) properties has been paradigm-shifting, linking tumor cell invasion and metastasis with therapeutic recurrence. However, despite their importance, the molecular pathways involved in generating invasive, metastatic, and therapy-resistant CSCs remain poorly understood. The enrichment of cells with a mesenchymal/CSC phenotype following therapy has been interpreted in two different ways. The original interpretation posited that therapy kills non-CSCs while sparing pre-existing CSCs. However, evidence is emerging that suggests non-CSCs can be induced into a transient, drug-tolerant, CSC-like state by chemotherapy. The ability to transition between distinct cell states may be as critical for the survival of tumor cells following therapy as it is for metastatic progression. Therefore, inhibition of the pathways that promote E-M and CSC plasticity may suppress tumor recurrence following chemotherapy. Here, we review the emerging appreciation for how plasticity confers therapeutic resistance and tumor recurrence.

Is there a need for emerging drugs for the acute respiratory distress syndrome?

The acute respiratory distress syndrome (ARDS) is a common and devastating syndrome of acute respiratory failure for which little effective pharmacotherapy exists. The authors describe some interventions that show promise as potential therapies for this condition, with particular reference to clinically relevant human models of ARDS. Aspirin, mesenchymal stromal (stem) cells, keratinocyte growth factor, IFN-β and oncostatin M inhibition are discussed.

HiJAK'd Signaling; the STAT3 Paradox in Senescence and Cancer Progression

Clinical and epidemiological data have associated chronic inflammation with cancer progression. Most tumors show evidence of infiltrating immune and inflammatory cells, and chronic inflammatory disorders are known to increase the overall risk of cancer development. While immune cells are often observed in early hyperplastic lesions in vivo, there remains debate over whether these immune cells and the cytokines they produce in the developing hyperplastic microenvironment act to inhibit or facilitate tumor development. The interleukin-6 (IL-6) family of cytokines, which includes IL-6 and oncostatin M (OSM), among others (LIF, CT-1, CNTF, and CLC), are secreted by immune cells, stromal cells, and epithelial cells, and regulate diverse biological processes. Each of the IL-6 family cytokines signals through a distinct receptor complex, yet each receptor complex uses a shared gp130 subunit, which is critical for signal transduction following cytokine binding. Activation of gp130 results in the activation of Signal Transducer and Activator of Transcription 3 (STAT3), and the Mitogen-Activated Protein Kinase (MAPK) and Phosphatidylinositol 3-Kinase (PI3K) signaling cascades. Tumor suppressive signaling can often be observed in normal cells following prolonged STAT3 activation. However, there is mounting evidence that the IL-6 family cytokines can contribute to later stages of tumor progression in many ways. Here we will review how the microenvironmental IL-6 family cytokine OSM influences each stage of the transformation process. We discuss the intrinsic adaptations a developing cancer cell must make in order to tolerate and circumvent OSM-mediated growth suppression, as well as the OSM effectors that are hijacked during tumor expansion and metastasis. We propose that combining current therapies with new ones that suppress the signals generated from the tumor microenvironment will significantly impact an oncologist’s ability to treat cancer.

Mycobacterium indicus pranii mediates macrophage activation through TLR2 and NOD2 in a MyD88 dependent manner

Mycobacterium indicus pranii (MIP) is a non-pathogenic strain of mycobacterium and has been used as a vaccine against tuberculosis and leprosy. Here, we investigated the role of different pattern recognition receptors in the recognition of heat-killed MIP by macrophages. Treatment of macrophages with MIP caused upregulation of pro-inflammatory cytokines (like TNFα and IL-1β) which was mediated through both TLR2 and NOD2, as revealed by our knockdown and/or knockout studies. Mechanistically, MIP-induced macrophage activation was shown to result in NF-κB activation and drastically abrogated by MyD88 deficiency, suggesting its regulation via an MyD88-dependent, NF-κB pathway. Interestingly, the IFN-inducible cytokine, CXCL10, which is known target of the TRIF-dependent TLR pathway was found to be upregulated in response to MIP but, in an MyD88-dependent manner. Collectively, these results demonstrate macrophages to recognize and respond to MIP through a TLR2, NOD2 and an MyD88-dependent pathway. However, further studies should clarify whether additional TLR-dependent or -independent pathways also exist in regulating the full spectrum of MIP action on macrophage activation.

c-MYC functions as a molecular switch to alter the response of human mammary epithelial cells to oncostatin M

Cytokines play an important role in creating an inflammatory microenvironment, which is now considered a hallmark of cancer. Although tumor cells can exploit cytokine signaling to promote growth, invasion, and metastasis, the response of normal and premalignant epithelial cells to cytokines present in a developing tumor microenvironment remains unclear. Oncostatin M (OSM), an IL-6 family cytokine responsible for STAT3 activation, has been implicated in cancer development, progression, invasion, and metastasis. Paradoxically, OSM can also suppress the growth of normal cells and certain tumor-derived cell lines. Using isogenic human mammary epithelial cells (HMEC) at different stages of neoplastic transformation, we found that OSM signaling suppressed c-MYC expression and engaged a p16- and p53-independent growth arrest that required STAT3 activity. Inhibition of STAT3 activation by expressing a dominant-negative STAT3 protein or a STAT3-shRNA prevented the OSM-mediated arrest. In addition, expression of c-MYC from a constitutive promoter also abrogated the STAT3-mediated arrest, and strikingly, cooperated with OSM to promote anchorage-independent growth (AIG), a property associated with malignant transformation. Cooperative transformation by c-MYC and OSM required PI3K and AKT signaling, showing the importance of multiple signaling pathways downstream of the OSM receptor in defining the cellular response to cytokines. These findings identify c-MYC as an important molecular switch that alters the cellular response to OSM-mediated signaling from tumor suppressive to tumor promoting.

Black tea polyphenol inhibits CXCL10 production in oncostatin M-stimulated human gingival fibroblasts

CXC chemokine ligand 10 (CXCL10) plays an important role in the infiltration of Th1 cells and thus in the exacerbation of periodontal disease. Theaflavin-3,3'-digallate (TFDG), polyphenol in black tea, has some beneficial effects but the effect of TFDG on CXCL10 production from human gingival fibroblasts (HGFs) is uncertain. In this study, we investigated the mechanisms by which TFDG may inhibit oncostatin M (OSM)-induced CXCL10 production in human gingival fibroblasts. TFDG prevented OSM-mediated CXCL10 production by HGFs in a dose dependent manner. TFDG significantly inhibited OSM-induced phosphorylation of c-Jun N terminal kinase (JNK), protein kinase B (Akt) (Ser473) that are related to CXCL10 production from OSM-stimulated HGFs. In addition, TFDG suppressed OSM receptor (OSMR) β expression on HGFs. These data provide a novel mechanism where the black tea flavonoid, theaflavin, could provide direct benefits in periodontal disease.

Catechins inhibit CXCL10 production from oncostatin M-stimulated human gingival fibroblasts

CXC chemokine ligand 10 (CXCL10) plays a pivotal role in the recruitment of Th1 cells and, thus, in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins derived from green tea, have multiple beneficial effects, but the effects of catechins on CXCL10 production from human gingival fibroblasts (HGFs) is not known. In this study, we investigated the mechanisms by which EGCG and ECG inhibit oncostatin M (OSM)-induced CXCL10 production in HGFs. HGFs constitutively expressed glycoprotein 130 and OSM receptor beta (OSMR beta), which are OSM receptors. OSM increased CXCL10 production in a concentration-dependent manner. EGCG and ECG prevented OSM-mediated CXCL10 production by HGFs. Inhibitors of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase (JNK), phosphatidylinositol-3-OH kinase and signal transducer and activator of transcription (STAT)3 decreased OSM-induced CXCL10 production. EGCG significantly prevented OSM-induced phosphorylation of JNK, Akt (Ser473) and STAT3 (Tyr705 and Ser727). ECG prevented phosphorylation of JNK and Akt (Ser473). In addition, EGCG and ECG attenuated OSMR beta expression on HGFs. These data provide a novel mechanism through which the green tea flavonoids, catechins, can provide direct benefits in periodontal disease.

PMA induces stabilization of oncostatin M mRNA in human lymphoma U937 cells

OSM (oncostatin M) is a pleiotropic cytokine belonging to the IL (interleukin) 6 family that modulates the growth of some cancer cell lines. We have found that PMA treatment of human U937 lymphoma cells increased the steady-state levels of OSM mRNA. Furthermore, the half-life of OSM mRNA was increased from 2.3 to 6.2 h. Measurement of mRNA/hnRNA (heterogeneous nuclear RNA) ratios in PMA-treated cells suggests further that the increase in OSM mRNA is due to enhanced mRNA stability. Consistent with this, synthetic OSM mRNA transcripts decayed faster in extracts of untreated U937 cells than in extracts of PMA-treated cells. The 3'-untranslated region of OSM mRNA contains a putative ARE (AU-rich element) that may play a role in mRNA stabilization. Addition of the OSM ARE motif to the 3'-end of beta-globin mRNA increased its decay rate in vitro. Decay assays with beta-globin-ARE(OSM) and beta-globin transcripts indicate that PMA induces mRNA stabilization in an ARE-dependent manner. PMA also induces at least five OSM ARE-binding proteins. Supershift assays indicated that HuR is present in PMA-induced OSM mRNA-protein complexes. PMA treatment appears to induce translocation of HuR from the nucleus to the cytoplasm. RNA-decay assays indicated that HuR stabilizes OSM RNA in vitro. Additionally, immunodepletion of HuR from U937 cell extracts led to more rapid decay of OSM transcripts. Collectively, these findings suggest that the ARE plays a role in PMA-induced stabilization of OSM mRNA and that this process involves multiple ARE-binding proteins, including HuR.

In human macrophages the complement component C5a induces the expression of oncostatin M via AP-1 activation

OBJECTIVE

Macrophages produce the cytokine oncostatin M (OSM), which beside other functions is also involved in inflammation. The complement component C5a mobilizes and activates these cells at inflammatory sites. We examined the effect of C5a on OSM production in human monocytes and in human monocyte-derived macrophages.

METHODS AND RESULTS

For macrophage transformation peripheral blood monocytes were cultivated for 8 to 10 days in the presence of human serum. C5a significantly increased in these cells OSM antigen as determined by specific ELISA and mRNA as quantitated by real-time polymerase chain reaction in these cells as well as in plaque macrophages. This effect was blocked by antibodies against the receptor C5aR/CD88 and by pertussis toxin. The C5a-induced phosphorylation of p38 and JNK and the C5a-induced increase in OSM production in macrophages was abolished by 2 p38 inhibitors and by a JNK inhibitor. Furthermore C5a increased the nuclear translocation of c-fos and c-jun. Using different OSM promoter deletion mutant constructs we show that the putative AP-1 element is responsible for activation of OSM promoter activity by C5a.

CONCLUSIONS

Our data establish a link between the complement system and the gp130 receptor cytokine family with possible implications for the pathology of inflammatory diseases.

Oncostatin M differentially regulates CXC chemokines in mouse cardiac fibroblasts

Ischemia-reperfusion injury in the heart is characterized by marked infiltration of neutrophils in the myocardial interstitial space. Studies in human, canine, and murine models have revealed oncostatin M (OSM) expression in infiltrating leukocytes. In an effort to assess possible roles of OSM in the myocardium, we used cardiac fibroblasts (mCFs) isolated from adult mouse heart to determine whether recombinant murine OSM regulates the synthesis and release of MIP2/CXCL2, KC/CXCL1, and LIX/CXCL5, which are three potent neutrophil chemoattractants in the mouse. Our results demonstrate that mCFs express OSM receptors and that, within the IL-6 cytokine family, OSM uniquely induces significant release of KC and LIX in mCFs. In addition, although OSM activates the JAK-signal transducers and activators of transcription and MAPK pathways, we demonstrate that the OSM-mediated CXC chemokine release in mCFs is also dependent on the activation of the phosphatidylinositol 3-kinase pathway.

Oncostatin M: a pleiotropic cytokine in the central nervous system

Oncostatin M (OSM), a member of the interleukin-6 (IL-6) cytokine family, has yet to be well studied, especially in the context of the central nervous system (CNS). The biological functions of OSM are complex and variable, depending on the cellular microenvironment. Inflammatory responses and tumor development are among two of the major events that OSM is involved in. Although OSM levels remain low in the normal CNS, elevated expression occurs in pathological conditions. Therefore, it is crucial to understand the regulation of OSM to control its expression and/or its effects. Accumulating data demonstrate that OSM binds to specific receptor complexes, then activates two major signaling pathways: Janus Kinase-Signal Transducers and Activators of Transcription (JAK-STAT) and Mitogen-Activated Protein Kinase (MAPK), to regulate downstream events. In this review, we focus on the biological functions of OSM, the signaling pathways of OSM in the CNS, and OSM involvement in CNS diseases.

Prostaglandin E2 is a novel inducer of oncostatin-M expression in macrophages and microglia

Oncostatin-M (OSM), a pluripotent cytokine of the interleukin-6 (IL-6) family, is produced in a number of inflammatory conditions. Known sources of OSM include monocytes-macrophages and T-cells. Here we present microglia, the resident macrophages of the brain, as a source of OSM in the CNS. In this context, we describe a novel inducer of OSM, prostaglandin E(2) (PGE(2)). PGE(2) induces OSM expression in microglia, monocytes, and macrophages of human and murine origin. PGE(2) induction of OSM is mimicked by cholera toxin, an activator of stimulatory G (G(s))-proteins; by forskolin, an activator of adenylate cyclase; and by the cAMP analog, dibutyryl-cAMP. PGE(2) induction of OSM gene expression is inhibited by the adenylate cyclase inhibitor 2',5'-dideoxyadenosine, by the protein kinase A (PKA) inhibitor H-89, and by a dominant-negative PKA construct. These data indicate that PGE(2) signals via G(s)-protein-coupled receptor(s), adenylate cyclase, and PKA to induce OSM expression. Accordingly, other activators of cAMP signaling such as norepinephrine and PGE(1) induce OSM. The ability of PGE(2) to induce OSM expression was tested under more physiological conditions, using cocultures of astrocytes and monocytes. Treatment of the cocultures with IL-1beta or tumor necrosis factor-alpha (TNF-alpha) results in production of PGE(2) and OSM. PGE(2) produced in the cocultures is responsible for OSM induction, because pretreatment with indomethacin, an inhibitor of prostaglandin synthesis, as well as depletion of PGE(2), abrogate OSM expression induced by IL-1beta or TNF-alpha. These data suggest that in the CNS, OSM may be produced through collaboration of astrocytes and macrophages-microglia.

LFA-1-dependent tumoricidal activity of cisplatin-treated macrophages

The role of leucocyte function associated antigen-1 (LFA-1) (CD11a/18) in the tumoricidal activity of cisplatin-treated macrophages was investigated. Anti-LFA-1 antibodies inhibited cisplatin-induced macrophage cytotoxicity towards three different tumour cell lines. The decrease in tumoricidal activity of cisplatin-treated macrophages was attributed to their decreased binding to tumour cells in the presence of anti-LFA-1 (CD11a/18) antibodies. Western blot analysis revealed that cisplatin treatment leads to the expression of LFA-1 on macrophages which otherwise remains non-detectable. Because there is no information regarding the mechanism of cisplatin-induced LFA-1 expression and tumour cell binding by macrophages, the role of various second messenger molecules in these processes was investigated. Results suggest that protein phosphatase 2A (PP2A) is not involved in these processes whereas protein tyrosine phosphatases (PTP) negatively regulate LFA-1 expression and tumour-cell binding of cisplatin-treated macrophages. Inhibitors of protein phosphatase 1 (PP1), protein kinase C (PKC), protein tyrosine kinase (PTK), calmodulin and calmodulin-dependent kinase-II (CamK II) prevented LFA-1 expression on cisplatin-treated macrophages. A comparison with earlier results indicated that LFA-expression follows a distinct signalling pathway which is separate from the signalling pathway involved in NO or tumour necrosis factor/interleukin-1 (TNF/IL-1) expression in cisplatin-stimulated macrophages.