STAT3 activation is required for interleukin-6 induced transformation in tumor-promotion sensitive mouse skin epithelial cells

Neurotoxicity of ischemic astrocytes involves STAT3-mediated metabolic switching and depends on glycogen usage

Astrocytic responses are critical for the maintenance of neuronal networks in health and disease. In stroke, reactive astrocytes undergo functional changes potentially contributing to secondary neurodegeneration, but the mechanisms of astrocyte-mediated neurotoxicity remain elusive. Here, we investigated metabolic reprogramming in astrocytes following ischemia-reperfusion in vitro, explored their role in synaptic degeneration, and verified the key findings in a mouse model of stroke. Using indirect cocultures of primary mouse astrocytes and neurons, we demonstrate that transcription factor STAT3 controls metabolic switching in ischemic astrocytes promoting lactate-directed glycolysis and hindering mitochondrial function. Upregulation of astrocytic STAT3 signaling associated with nuclear translocation of pyruvate kinase isoform M2 and hypoxia response element activation. Reprogrammed thereby, the ischemic astrocytes induced mitochondrial respiration failure in neurons and triggered glutamatergic synapse loss, which was prevented by inhibiting astrocytic STAT3 signaling with Stattic. The rescuing effect of Stattic relied on the ability of astrocytes to utilize glycogen bodies as an alternative metabolic source supporting mitochondrial function. After focal cerebral ischemia in mice, astrocytic STAT3 activation was associated with secondary synaptic degeneration in the perilesional cortex. Inflammatory preconditioning with LPS increased astrocytic glycogen content, reduced synaptic degeneration, and promoted neuroprotection post stroke. Our data indicate the central role of STAT3 signaling and glycogen usage in reactive astrogliosis and suggest novel targets for restorative stroke therapy.

Decursin inhibits tumor progression in head and neck squamous cell carcinoma by downregulating CXCR7 expression in vitro

CXC chemokine receptor 7 (CXCR7) is frequently overexpressed in cancer and plays a significant role in tumor growth and metastasis. Consequently, inhibition of CXCR7 is important for treatment strategies. However, little is known concerning the biological role of CXCR7 and its underlying mechanisms in head and neck squamous cell carcinoma (HNSCC). The present study investigated the role of CXCR7 in HNSCC, as well as the effects of decursin, a pyranocoumarin compound isolated from Angelica gigas Nakai, on CXCR7 and its downstream signaling. Expression levels of CXCR7 in HNSCC cells were examined using flow cytometry, reverse transcriptase PCR, western blot analysis, and immunofluorescence. The effects of CXCR7 on cell proliferation, migration, and invasion were studied using CCK-8, gap closure, and transwell assays. The results revealed that decursin significantly reduced CXCR7 expression and inhibited cell proliferation, migration, and invasion of human HNSCC cell lines. In addition, decursin induced G0/G1 cell cycle arrest in CXCR7-overexpressing cells and decreased the levels of cyclin A, cyclin E, and CDK2. Furthermore, CXCR7 promoted cancer progression via the STAT3/c-Myc pathway in HNSCC; suppression of CXCR7 with decursin prevented this effect. These results suggest that CXCR7 promotes cancer progression through the STAT3/c-Myc pathway and that the natural compound decursin targets CXCR7 and may be valuable in the treatment of HNSCC.

The Framework for Human Host Immune Responses to Four Types of Parasitic Infections and Relevant Key JAK/STAT Signaling

The human host immune responses to parasitic infections are complex. They can be categorized into four immunological pathways mounted against four types of parasitic infections. For intracellular protozoa, the eradicable host immunological pathway is TH1 immunity involving macrophages (M1), interferon gamma (IFNγ) CD4 T cells, innate lymphoid cells 1 (NKp44+ ILC1), CD8 T cells (Effector-Memory4, EM4), invariant natural killer T cells 1 (iNKT1) cells, and immunoglobulin G3 (IgG3) B cells. For intracellular protozoa, the tolerable host immunological pathway is TH1-like immunity involving macrophages (M2), interferon gamma (IFNγ)/TGFβ CD4 T cells, innate lymphoid cells 1 (NKp44- ILC1), CD8 T cells (EM3), invariant natural killer T 1 (iNKT1) cells, and immunoglobulin A1 (IgA1) B cells. For free-living extracellular protozoa, the eradicable host immunological pathway is TH22 immunity involving neutrophils (N1), interleukin-22 CD4 T cells, innate lymphoid cells 3 (NCR+ ILC3), iNKT17 cells, and IgG2 B cells. For free-living extracellular protozoa, the tolerable host immunological pathway is TH17 immunity involving neutrophils (N2), interleukin-17 CD4 T cells, innate lymphoid cells 3 (NCR- ILC3), iNKT17 cells, and IgA2 B cells. For endoparasites (helminths), the eradicable host immunological pathway is TH2a immunity with inflammatory eosinophils (iEOS), interleukin-5/interleukin-4 CD4 T cells, interleukin-25 induced inflammatory innate lymphoid cells 2 (iILC2), tryptase-positive mast cells (MCt), iNKT2 cells, and IgG4 B cells. For ectoparasites (parasitic insects and arachnids), the eradicable host immunological pathway is TH2b immunity with inflammatory basophils, chymase- and tryptase-positive mast cells (MCct), interleukin-3/interleukin-4 CD4 T cells, interleukin-33 induced nature innate lymphoid cells 2 (nILC2), iNKT2 cells, and immunoglobulin E (IgE) B cells. The tolerable host immunity against ectoparasites and endoparasites is TH9 immunity with regulatory eosinophils, regulatory basophils, interleukin-9 mast cells (MMC9), thymic stromal lymphopoietin induced innate lymphoid cells 2, interleukin-9 CD4 T cells, iNKT2 cells, and IgA2 B cells. In addition, specific transcription factors important for specific immune responses were listed. This JAK/STAT signaling is key to controlling or inducing different immunological pathways. In sum, Tfh is related to STAT5β, and BCL6 expression. Treg is related to STAT5α, STAT5β, and FOXP3. TH1 immunity is related to STAT1α, STAT4, and T-bet. TH2a immunity is related to STAT6, STAT1α, GATA1, and GATA3. TH2b immunity is related to STAT6, STAT3, GATA2, and GATA3. TH22 immunity is associated with both STAT3α and AHR. THαβ immunity is related to STAT1α, STAT1β, STAT2, STAT3β, and ISGF. TH1-like immunity is related to STAT1α, STAT4, STAT5α, and STAT5β. TH9 immunity is related to STAT6, STAT5α, STAT5β, and PU.1. TH17 immunity is related to STAT3α, STAT5α, STAT5β, and RORG. TH3 immunity is related to STAT1α, STAT1β, STAT2, STAT3β, STAT5α, STAT5β, and ISGF. This categorization provides a complete framework of immunological pathways against four types of parasitic infections. This framework as well as relevant JAK/STAT signaling can provide useful knowledge to control allergic hypersensitivities and parasitic infections via development of vaccines or drugs in the near future.

Dual blockage of STAT3 and ERK1/2 eliminates radioresistant GBM cells

Radiotherapy (RT) is the major modality for control of glioblastoma multiforme (GBM), the most aggressive brain tumor in adults with poor prognosis and low patient survival rate. To improve the RT efficacy on GBM, the mechanism causing tumor adaptive radioresistance which leads to the failure of tumor control and lethal progression needs to be further elucidated. Here, we conducted a comparative analysis of RT-treated recurrent tumors versus primary counterparts in GBM patients, RT-treated orthotopic GBM tumors xenografts versus untreated tumors and radioresistant GBM cells versus wild type cells. The results reveal that activation of STAT3, a well-defined redox-sensitive transcriptional factor, is causally linked with GBM adaptive radioresistance. Database analysis also agrees with the worse prognosis in GBM patients due to the STAT3 expression-associated low RT responsiveness. However, although the radioresistant GBM cells can be resensitized by inhibition of STAT3, a fraction of radioresistant cells can still survive the RT combined with STAT3 inhibition or CRISPR/Cas9-mediated STAT3 knockout. A complementally enhanced activation of ERK1/2 by STAT3 inhibition is identified responsible for the survival of the remaining resistant tumor cells. Dual inhibition of ERK1/2 and STAT3 remarkably eliminates resistant GBM cells and inhibits tumor regrowth. These findings demonstrate a previously unknown feature ofSTAT3-mediated ERK1/2 regulation and an effective combination of two targets in resensitizing GBM to RT.

A Case of Ocular Kaposi's Sarcoma Successfully Treated with Highly Active Antiretroviral Therapy (HAART) Combined with Docetaxel

Patient: Male, 24

Final Diagnosis: Ocular Kaposi’s sarcoma

Symptoms: Eyelid swelling • red eye

Medication: —

Clinical Procedure: Biopsy

Specialty: Oncology

Interleukin-6 blockade attenuates lung cancer tissue construction integrated by cancer stem cells

In the present study, we successfully generated lung cancer stem cell (CSC)-like cells by introducing a small set of transcription factors into a lung cancer cell line. In addition to properties that are conventionally referred to as CSC properties, the lung induced CSCs exhibited the ability to form lung cancer-like tissues in vitro with vascular cells and mesenchymal stem cells, which showed structures and immunohistological patterns that were similar to human lung cancer tissues. We named them “lung cancer organoids”. We found that interleukin-6 (IL-6), which was expressed in the lung induced CSCs, facilitates the formation of lung cancer organoids via the conversion of mesenchymal stem cells into alpha-smooth muscle actin (αSMA)-positive cells. Interestingly, the combination of anti-IL-6 antibody and cisplatin could destroy the lung cancer organoids, while cisplatin alone could not. Furthermore, IL-6 mRNA-positive cancer cells were found in clinical lung cancer samples. These results suggest that IL-6 could be a novel therapeutic target in lung cancer.

The antiangiogenic role of the pro-inflammatory cytokine interleukin-31

Pro-inflammatory cytokines in the tumor microenvironment are known for their ability to either inhibit or promote cancer progression. Here we evaluated the role of Interleukin-31 (IL31), a protein belonging to the pro-inflammatory IL-6 cytokine family which has been characterized in autoimmune disease, in tumorigenesis. We show that IL31 and its receptor, IL31RA, are highly expressed in various human and mouse cancer cell lines, as well as in tumor specimens from cancer patients. MC38 murine colon carcinoma cells depleted of IL31 exhibit an increase in invasive and migratory properties in vitro, effects that are reversed by supplementing the cells with exogenous IL31. In vivo, IL31-depleted MC38 tumor cells implanted to mice grow faster than control tumors. In contrast, MC38 tumor-bearing mice infused with recombinant IL31, exhibit a significant reduction in tumor growth than control mice. Furthermore, IL31 infusion reduces the number of metastatic lesions in the lungs of mice bearing 4T1 murine metastatic breast carcinoma. Lastly, injecting tumor-bearing, chemotherapy-treated mice with a long-lived IL31-IgG fusion protein reduces tumor growth, angiogenesis and pulmonary metastasis to a greater extent than when chemotherapy is used alone. The IL31 anti-tumor activity is explained, in part, by the anti-angiogenic effects demonstrated both in vitro and in vivo highlighting the potential use of IL31 as an anti-cancer drug.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

MicroRNA-1299 is a negative regulator of STAT3 in colon cancer

Signal transducers and activators of transcription (STAT) is a family of transcription factors which regulate cell proliferation, differentiation, apoptosis, metastasis, immune and inflammatory responses, and angiogenesis. STAT3 is a latent cytoplasmic transcription factor that belongs to STATs. STAT3 has been reported be regulates genes involved with cellular growth, proliferation and metastasis. Worldwide, colon cancer is one of the leading causes of cancer-related deaths. Cumulative evidence has established that STAT3 is essential for colon cancer progression to advanced malignancy. In our study, we showed that microRNA-1299 (miR-1299) was closely related to the TNM stage of colon cancer, and that the expression of miR-1299 was negatively correlated with the expression of STAT3 in colon cancer which means that miR-1299 can be a negative regulator of STAT3 in colon cancer. A total of 60 cases of different grades of colon samples were used to detect the expression of miR-1299. Results showed that miR-1299 was significantly lower in high-grade colons both in mRNA and protein levels. Furthermore, Overall survival (OS) in patients with low miR-1299 is shorter than 25.6 months, as compared with an OS of 28.4 months in patients with high level of miR-1299. We also confirmed that the overexpression of miR-1299 can not only downregulate the STAT3 pathway, but also inhibited colon cancer cell growth. Our findings could provide new insights into the molecular therapeutic of colon cancer.

STAT3: a critical component in the response to Helicobacter pylori infection

STAT3 imparts a profound influence on both the epithelial and immune components of the gastric mucosa, and through regulation of key intracellular signal transduction events, is well placed to control inflammatory and oncogenic outcomes in the context of Helicobacter (H.) pylori infection. Here we review the roles of STAT3 in the host immune response to H. pylori infection, from both gastric mucosal and systemic perspectives, as well as alluding more specifically to STAT3-dependent mechanisms that might be exploited as drug targets.

Antitumor efficacy of the anti-interleukin-6 (IL-6) antibody siltuximab in mouse xenograft models of lung cancer

INTRODUCTION

Interleukin-6 (IL-6) can activate downstream signaling pathways in lung cancer cells, such as the STAT3 pathway, and is reported to be produced by tumor cells with activating EGFR mutations. We examined IL-6/STAT3 in lung cancer tumor tissues and the effects of siltuximab, a neutralizing antibody to human IL-6, in mouse models of lung cancer.

METHODS

IL-6 and STAT3 activation levels were compared with tumor histology and presence of KRAS mutations in snap-frozen, non-small-cell lung cancer tumors. The effects of siltuximab alone or in combination with erlotinib were examined in mouse xenograft models constructed using three cell line xenograft models and one primary explant mouse model. We examined the influence of cancer-associated fibroblasts (CAFs) on tumor growth and siltuximab effects.

RESULTS

IL-6 levels were higher in tumors of squamous cell versus adenocarcinoma histology and were not associated with presence of KRAS mutations. Tyrosine phosphorylation status of STAT3 did not correlate with tumor IL-6 levels. Serine phosphorylation of STAT3 was correlated with KRAS mutation status. Both tumor and stromal cells contributed to total IL-6 within tumors. Siltuximab had minimal effect as a single agent in xenografts with tumor cells alone; however, in models coadministered with CAFs, siltuximab had more potent effects on tumor inhibition. We observed no effects of combined erlotinib and siltuximab.

CONCLUSIONS

IL-6 is elevated in subsets of human NSCLCs, especially with squamous cell histology. Tumors supported by stromal production of IL-6 seem to be the most vulnerable to tumor growth inhibition by siltuximab.

Parametrial fat tissue from high fat diet-treated SKH-1 mice stimulates transformation of mouse epidermal JB6 cells

Our previous studies indicated that decreasing visceral adipose tissue by surgical removal of the parametrial fat pads inhibited UVB-induced carcinogenesis in SKH-1 mice fed a high fat diet (HFD), but not a low fat diet (LFD) indicating that the parametrial fat tissue from mice fed a HFD played a role in skin carcinogenesis.

OBJECTIVE

In the present study, we sought to investigate how a HFD may influence the intrinsic properties of the parametrial fat tissue to influence UVB-induced skin tumor formation.

METHODS AND RESULTS

Immunohistochemical staining, adipokine array, and flow cytometry showed that parametrial fat tissue from mice fed a HFD had a higher density of macrophage-fused dead adipocytes (crown-like structures), more adipokines, and stimulated the production of more reactive oxygen species compared with parametrial fat tissue from mice fed a LFD. These differences between parametrial fat tissue from mice fed a HFD and LFD were associated with their effect on the in vitro transformation of mouse epidermal JB6 cells. Our results indicated that fat tissue filtrate (an aqueous filtrate made from the parametrial fat pad) from mice fed a HFD enhanced the conversion of JB6 cells from an epithelial-like morphology to cells with a fibroblast-like morphology to a greater extent than fat tissue filtrate from mice fed a LFD. Studies indicated that the fibroblast-like cells had decreased levels of E-cadherin, increased levels of Twist as assayed by western blot. Fat tissue filtrate made from the parametrial fat tissue of mice fed a HFD had 160% more transforming activity than that from mice fed a LFD and formed malignant mesenchymal tumors in vivo.

CONCLUSION

These studies provide the first in vitro demonstration of a parametrial fat tissue-induced transformation of an epidermal cell.

Role of STAT3 in cancer metastasis and translational advances

Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor, originally discovered as a transducer of signal from cell surface receptors to the nucleus. It is activated by tyrosine phosphorylation at position 705 leading to its dimerization, nuclear translocation, DNA binding, and activation of gene transcription. Under normal physiological conditions, STAT3 activation is tightly regulated. However, compelling evidence suggests that STAT3 is constitutively activated in many cancers and plays a pivotal role in tumor growth and metastasis. It regulates cellular proliferation, invasion, migration, and angiogenesis that are critical for cancer metastasis. In this paper, we first describe the mechanism of STAT3 regulation followed by how STAT3 is involved in cancer metastasis, then we summarize the various small molecule inhibitors that inhibit STAT3 signaling.

Critical analysis of the potential for targeting STAT3 in human malignancy

The signal transducer and activator of transcription (STAT) family of proteins was originally discovered in the context of normal cell biology where they function to transduce intracellular and extracellular signals to the nucleus, ultimately leading to transcription of specific target genes and downstream phenotypic effects. It was quickly appreciated that the STATs, especially STAT3, play a fundamental role in human malignancy. In contrast to normal biology in which transient STAT3 signaling is strictly regulated by a tightly coordinated network of activators and deactivators, STAT3 is constitutively activated in human malignancies. Constitutive STAT3 signaling has been associated with many cancerous phenotypes across nearly all human cancers, including the upregulation of cell growth, proliferation, survival, and motility, among others. Studies involving candidate preclinical STAT3 inhibitors have further demonstrated that the reversal of these phenotypes results from pharmacologic or genetic inhibition of STAT3, suggesting that STAT3 may be a promising target for clinical interventions. Indeed, a Phase 0 clinical trial involving a STAT3 decoy oligonucleotide demonstrated that STAT3 is a drug-gable target in human tumors. Because of the ubiquity of overactive STAT3 in cancer, its role in promoting a wide variety of cancerous phenotypes, and the strong clinical and preclinical studies performed to date, STAT3 represents a promising target for the development of inhibitors for the treatment of human cancers.

Effects of C-Phycocyanin on the representative genes of tumor development in mouse skin exposed to 12-O-tetradecanoyl-phorbol-13-acetate

C-Phycocyanin (C-PC), a biliprotein from the sea weed, has been shown to have the beneficial effects like antioxidant, anti-inflammatory, neuroprotective, and hepatoprotective properties and is used as food supplement. We are showing the effect of C-Phycocyanin on the early events altered by tumor promoter. TPA induced the expression of critical events of tumorigenesis like ornithine decarboxylase, cyclooxygenase-2, interleukin-6 and pSTAT3 in mouse skin after 5h of application, whereas expression of transglutaminase2 was decreased at this time point. This TPA-caused altered expression of genes was prevented in presence of C-Phycocyanin. This prevention by C-Phycocyanin appeared to be dependent on the dose of C-Phycocyanin used. The results are useful for the detailed study on the preventive effect of C-Phycocyanin on TPA induced tumor promotion.

Associations between promoter polymorphism -106A/G of interleukin-11 receptor alpha and papillary thyroid cancer in Korean population

BACKGROUND

The interleukin11 (IL11) and IL11 receptor alpha (IL11RA) are involved in cellular growth, differentiation, invasiveness, and tumor progression in several tumors. We investigated whether coding single nucleotide polymorphisms (cSNPs) of IL11 and promoter SNP IL11RA would contribute to the development of papillary thyroid cancer (PTC). We also assessed the relationships between IL11 and IL11RA SNPs and the clinicopathologic characteristics of PTC.

METHODS

One coding SNP, designated as rs1126757, Ala82Ala, in IL11 and one promoter SNP, designated as rs1061758, -106A/G, in IL11RA were genotyped using direct sequencing in 94 patents with PTC and 213 patients without PTC (controls). Genetic data were analyzed using commercially available software. The patients with PTC were dichotomized and compared with respect to clinicopathologic characteristics of PTC.

RESULTS

We found an association between PTC and the coding SNP(rs1061758) in IL11RA (codominant model 1 [G/G vs. A/G], odds ratio [OR] = 2.91, 95% confidence interval [CI], 1.44-5.89; P = .003; codominant model 2 [G/G vs. A/A], OR = 2.95, 95% CI, 1.30-6.72; P = .01; and dominant model, OR = 2.92, 95% CI, 1.47-5.80; P = .002). Moreover, SNP rs1061758 in IL11RA was associated with the multifocality of PTC (codominant model 2 [A/A vs. G/G], OR = 9.56, 95% CI, 1.77-51.69; P = .009; and recessive model, OR = 7.22, 95% CI, 1.72-30.3; P = .007). Genotype and allele analyses of SNP variant rs1126757 in IL11 revealed no statistically significant differences between patients with PTC and controls.

CONCLUSION

Our results suggest that an IL11RA promoter polymorphism--rs1061758--may be associated with the risk of PTC in the Korean population. In addition, rs1061758 might be related to the multifocality of PTC.

A Role for PPARgamma in the Regulation of Cytokines in Immune Cells and Cancer

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor and a member of the nuclear receptor superfamily. PPARγ and its ligands appear to serve diverse biological functions. In addition to the well-studied effects of PPARγ on metabolism and cellular differentiation, abundant evidence suggests that PPARγ is an important regulator of the immune system and cancers. Since cytokines are not only key modulators of inflammation with pro- and anti-inflammatory functions but they also can either stimulate or inhibit tumor growth and progression, this review summarizes the role for PPARγ in the regulation of cytokine production and cytokine-mediated signal transduction pathways in immune cells and cancer.

Herpesvirus-encoded GPCRs rewire cellular signaling

Viral G-protein-coupled receptors (vGPCRs) are chemokine receptor homologues encoded by the Herpes- and Capripoxviridae. They are thought to have been hijacked from the host genome during the course of evolution. These vGPCRs play different roles in the viral lifecycle and associated pathologies. Three members of the Herpesviridae, Kaposi sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) are capable of setting up persistent latent infections in humans. Two of the herpesviruses, KSHV and EBV, are associated with cancer, while HCMV may have an oncomodulary effect. The vGPCRs may contribute to the escape of immune surveillance and (constitutively) activate signaling pathways linked to proliferation and inflammation. Some vGPCRs induce activation of autocrine and paracrine signaling, resulting in secretion of growth factors and/or cytokines. As a result, vGPCRs effectively rewire cellular signaling networks. Delineating the cellular signaling networks modulated by these vGPCRs will be crucial for treatment of virus-associated pathologies.

HCMV-encoded chemokine receptor US28 mediates proliferative signaling through the IL-6-STAT3 axis

US28 is a viral G protein (heterotrimeric guanosine triphosphate-binding protein)-coupled receptor encoded by the human cytomegalovirus (HCMV). In addition to binding and internalizing chemokines, US28 constitutively activates signaling pathways linked to cell proliferation. Here, we show increased concentrations of vascular endothelial growth factor and interleukin-6 (IL-6) in supernatants of US28-expressing NIH 3T3 cells. Increased IL-6 was associated with increased activation of the signal transducer and activator of transcription 3 (STAT3) through upstream activation of the Janus-activated kinase JAK1. We used conditioned growth medium, IL-6-neutralizing antibodies, an inhibitor of the IL-6 receptor, and short hairpin RNA targeting IL-6 to show that US28 activates the IL-6-JAK1-STAT3 signaling axis through activation of the transcription factor nuclear factor kappaB and the consequent production of IL-6. Treatment of cells with a specific inhibitor of STAT3 inhibited US28-dependent [(3)H]thymidine incorporation and foci formation, suggesting a key role for STAT3 in the US28-mediated proliferative phenotype. US28 also elicited STAT3 activation and IL-6 secretion in HCMV-infected cells. Analyses of tumor specimens from glioblastoma patients demonstrated colocalization of US28 and phosphorylated STAT3 in the vascular niche of these tumors. Moreover, increased phospho-STAT3 abundance correlated with poor patient outcome. We propose that US28 induces proliferation in HCMV-infected tumors by establishing a positive feedback loop through activation of the IL-6-STAT3 signaling axis.

Role of NEK6 in tumor promoter-induced transformation in JB6 C141 mouse skin epidermal cells

NEK6 (NIMA-related kinase 6) is a homologue of the Aspergillus nidulans protein NIMA (never in mitosis, gene A). We demonstrate that overexpression of NEK6 induces anchorage-independent transformation of JB6 Cl41 mouse epidermal cells. Tissue arrays and Western immunoblot analysis show that NEK6 is overexpressed in malignant tissues and several cancer cell lines. Our data also show that NEK6 interacts with STAT3, an oncogenic transcription factor, and phosphorylates STAT3 on Ser(727), which is important for transcriptional activation. Additional studies using NEK6 mutants suggested that the phosphorylation on both Ser(206) and Thr(210) of NEK6 is critical for STAT3 phosphorylation and anchorage-independent transformation of mouse epidermal cells. Notably, knockdown of NEK6 decreased colony formation and STAT3 Ser(727) phosphorylation. Based on our findings, the most likely mechanism that can account for this biological effect involves the activation of STAT3 through the phosphorylation on Ser(727). Because of the critical role that STAT3 plays in mediating oncogenesis, the stimulatory effects of NEK6 on STAT3 and cell transformation suggest that this family of serine/threonine kinases might represent a novel chemotherapeutic target.

Inhibition of STAT3 signaling blocks the anti-apoptotic activity of IL-6 in human liver cancer cells

Interleukin-6 (IL-6) is a multifunctional cytokine, which may block apoptosis during inflammation to protect cells under very toxic conditions. However, IL-6 also activates STAT3 in many types of human cancer. Recent studies demonstrate that high levels of IL-6 are associated with hepatocellular carcinoma, the most common type of liver cancer. Here we reported that IL-6 promoted survival of human liver cancer cells through activating STAT3 in response to doxorubicin treatment. Endogenous IL-6 levels in SNU-449 cells were higher than in Hep3B cells. Meanwhile, SNU-449 cells were more resistant to doxorubicin than Hep3B cells. Addition of IL-6 induced STAT3 activation in Hep3B cells and led to protection against doxorubicin. In contrast, neutralizing IL-6 with anti-IL-6 antibody decreased survival of SNU-449 cells in response to doxorubicin. To elucidate the mechanism of the anti-apoptotic function of IL-6, we investigated if STAT3 mediated this drug resistance. Targeting STAT3 with STAT3 siRNA reduced the protection of IL-6 against doxorubicin-induced apoptosis, indicating that STAT3 signaling contributed to the anti-apoptotic effect of IL-6. Moreover, we further explored if a STAT3 small molecule inhibitor could abolish this anti-apoptotic effect. LLL12, a STAT3 small molecule inhibitor, blocked IL-6-induced STAT3 phosphorylation, resulting in attenuation of the anti-apoptotic activity of IL-6. Finally, neutralization of endogenous IL-6 with anti-IL-6 antibody or blockade of STAT3 with LLL12 lowered the recovery in SNU-449 cells after doxorubicin treatment. Therefore, our results demonstrated that targeting STAT3 signaling could interrupt the anti-apoptotic function of IL-6 in human liver cancer cells.

Interleukin-6 released from fibroblasts is essential for up-regulation of matrix metalloproteinase-1 expression by U937 macrophages in coculture: cross-talking between fibroblasts and U937 macrophages exposed to high glucose

Matrix metalloproteinases (MMPs) play a key role in periodontal disease. Although it is known that macrophages and fibroblasts are co-localized and express MMPs in the diseased periodontal tissue, the effect of interaction between these two cell types on MMP expression has not been well elucidated. Furthermore although it is known that diabetes is associated with accelerated periodontal tissue destruction, it remains unknown whether hyperglycemia, a major metabolic abnormality in diabetes, regulates MMP expression by affecting the cross-talking between fibroblasts and macrophages. In this study, human gingival fibroblasts and U937 macrophages were cocultured in a two-compartment transwell culture system, and the cells were treated with normal or high glucose. We found that coculture of fibroblasts and U937 macrophages led to an augmentation of MMP-1 expression by U937 macrophages, and high glucose further enhanced this augmentation. Similar observations were also made in the coculture of fibroblasts and human primary monocytes. We also found that interleukin 6 (IL-6) released by fibroblasts was essential for the augmentation of MMP-1 expression by U937 macrophages. Furthermore our results showed that high glucose, IL-6, and lipopolysaccharide had a synergistic effect on MMP-1 expression. Finally our study indicated that MAPK pathways and activator protein-1 transcription factor were involved in the coculture- and high glucose-augmented MMP-1 expression. In conclusion, this study demonstrates that IL-6 derived from fibroblasts is essential for MMP-1 up-regulation by cross-talking between fibroblasts and U937 macrophages exposed to high glucose, revealing an IL-6-dependent mechanism in MMP-1 up-regulation.

Inflammation-associated serum and colon markers as indicators of dietary attenuation of colon carcinogenesis in ob/ob mice

Although inflammatory cytokines and obesity-associated serum proteins have been reported as biomarkers of colorectal adenoma risk in humans, little is known of biomarkers of response to interventions that attenuate tumorigenesis. Dietary navy beans and their fractions attenuate colon carcinogenesis in carcinogen-induced genetically obese mice. We hypothesized that this attenuation would be associated with changes in inflammatory cytokines and obesity-related serum proteins that may serve as measures of efficacy. ob/ob mice (n = 160) were injected with the carcinogen azoxymethane (AOM) to induce colon cancer and randomly placed on one of four diets (control, whole navy bean, bean residue fraction, or bean extract fraction) for 26 to 28 wk. Serum was analyzed for 14 inflammation- or obesity-related proteins, and colon RNA was analyzed for expression of 84 inflammation-associated genes. Six of 14 serum proteins were increased [i.e., interleukin (IL)-4, IL-5, IL-6, IL-10, IFN gamma, granulocyte macrophage colony-stimulating factor] in hyperplastic/dysplastic stages of colon carcinogenesis. Bean-fed mice had significantly higher monocyte chemoattractant protein-1 and lower IL-6 levels in serum. In colon mucosa, 55 of 84 inflammation-associated genes differed between AOM-induced and noninduced mice. Of the 55 AOM-induced genes, 5 were counteracted by bean diets, including IL-6 whose increase in expression levels was attenuated by bean diets in AOM-induced mice. In summary, IL-6 emerged as a serum protein that was increased in hyperplastic/dysplastic stages of colon carcinogenesis, but attenuated with bean-based diet in serum and colon mucosa. Changes in a subset of inflammation-associated serum proteins and colon gene expression may serve as response indicators of dietary attenuation of colon carcinogenesis.

The role of infectious agents in the etiology of ocular adnexal neoplasia

Given the fact that infectious agents contribute to around 18% of human cancers worldwide, it would seem prudent to explore their role in neoplasms of the ocular adnexa: primary malignancies of the conjunctiva, lacrimal glands, eyelids, and orbit. By elucidating the mechanisms by which infectious agents contribute to oncogenesis, the management, treatment, and prevention of these neoplasms may one day parallel what is already in place for cancers such as cervical cancer, hepatocellular carcinoma, gastric mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma. Antibiotic treatment and vaccines against infectious agents may herald a future with a curtailed role for traditional therapies of surgery, radiation, and chemotherapy. Unlike other malignancies for which large epidemiological studies are available, analyzing ocular adnexal neoplasms is challenging as they are relatively rare. Additionally, putative infectious agents seemingly display an immense geographic variation that has led to much debate regarding the relative importance of one organism versus another. This review discusses the pathogenetic role of several microorganisms in different ocular adnexal malignancies, including human papilloma virus in conjunctival papilloma and squamous cell carcinoma, human immunodeficiency virus in conjunctival squamous carcinoma, Kaposi sarcoma-associated herpes virus or human herpes simplex virus-8 (KSHV/HHV-8) in conjunctival Kaposi sarcoma, Helicobacter pylori (H. pylori,), Chlamydia, and hepatitis C virus in ocular adnexal mucosa-associated lymphoid tissue lymphomas. Unlike cervical cancer where a single infectious agent, human papilloma virus, is found in greater than 99% of lesions, multiple organisms may play a role in the etiology of certain ocular adnexal neoplasms by acting through similar mechanisms of oncogenesis, including chronic antigenic stimulation and the action of infectious oncogenes. However, similar to other human malignancies, ultimately the role of infectious agents in ocular adnexal neoplasms is most likely as a cofactor to genetic and environmental risk factors.

Signal transducer and activator of transcription 3 activation promotes invasive growth of colon carcinomas through matrix metalloproteinase induction

Signal transducer and activator of transcription 3 (STAT3) is aberrantly activated in colorectal carcinomas (CRCs). Here, we define the relationship between STAT3 function and the malignant properties of colon carcinoma cells. Elevated activation of STAT3 enhances invasive growth of the CRC cell lines. To address mechanisms through which STAT3 influences invasiveness, the protease mRNA expression pattern of CRC biopsies was analyzed and correlated with the STAT3 activity status. These studies revealed a striking coincidence of STAT3 activation and strong expression of matrix metalloproteinases MMP-1, -3, -7, and -9. Immunohistological examination of CRC tumor specimens showed a clear colocalization of MMP-1 and activated STAT3. Experimentally induced STAT3 activity in CRC cell lines enhanced both the level of MMP-1 mRNA and secreted MMP-1 enzymatic activity. A direct connection of STAT3 activity and transcription from the MMP-1 promoter was shown by reporter gene experiments. Moreover, high-affinity binding of STAT3 to STAT recognition elements in both the MMP-1 and MMP-3 promoter was demonstrated. Xenograft tumors arising from implantation of CRC cells into nude mice showed simultaneous appearance and colocalization of p-Y-STAT3 and MMP-1 expression. Our results link aberrant activity of STAT3 in CRC to malignant tumor progression through upregulated expression of MMPs.

Paradoxical effects of cytokines in tumor immune surveillance and tumor immune escape

The role of cytokines in modulating the formation of new tumors is mediated by their ability to regulate antigen-specific anti-tumor responses and by the activation of non-specific mechanisms, including those involved in the processes of inflammation and innate resistance. Cytokines may influence the growth of tumors by acting directly on tumor cells as growth promoting or growth inhibiting factors or indirectly by attracting inflammatory cell types and affecting angiogenesis. Due to the potency and complexity of cytokine activity against tumor growth, the improvement of cloning techniques and the availability of recombinant forms of different cytokines, a great effort has been made in the recent years to exploit this anti-tumor potential for cancer therapy. This important goal has been difficult to achieve in most cases due to toxicity of most cytokines which could not be dissociated from their anti-tumoral functions. Nevertheless, if well designed, treatment protocols and/or modifications of the cytokine molecules may in some situations augment the anti-tumor effects while limiting the toxicity. One of these molecular approaches could be the design of peptides containing the functional domain of certain cytokines, exemplified by IT9302, a peptide homologous to the functional domain of IL-10, which has demonstrated to increase tumor NK cell sensitivity.

NFAT3 is specifically required for TNF-α-induced cyclooxygenase-2 (COX-2) expression and transformation of Cl41 cells

NFAT family is recognized as a transcription factor for inflammation regulation by inducing the expression of proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), the key mediator of inflammation, which was reported to induce cell transformation in mouse epidermal Cl41 cells. In this study, we demonstrated that TNF-α was able to induce NFAT activation, as well as the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). The induction of COX-2 by TNF-α was abolished by knockdown of NFAT3 with its siRNA, while the induction of iNOS was not effected. Moreover, TNF-α-induced anchorage-independent cell growth was significantly inhibited by NFAT3 siRNA and cyclosporine A, a chemical inhibitor for the calcineurin/NFAT pathway, which suggests the importance of NFAT3 in regulating TNF-α-induced anchorage-independent cell growth. Consequently, impairment of COX-2 by its siRNA or selective inhibitor also inhibited TNF-α-induced anchorage-independent cell growth. Taken together, our results indicate that NFAT3 plays an important role in the regulation of TNF-α-induced anchorage-independent cell growth, at least partially, by inducing COX-2 expression in Cl41 cells. These findings suggest that NFAT3/cyclooxygenase-2 act as a link between inflammation and carcinogenesis by being involved in the tumor promotion stage.

Expression of Interleukin-11 and Interleukin-11 receptor α in human colorectal adenocarcinoma; Immunohistochemical analyses and correlation with clinicopathological factors

AIM: There is strong evidence that interleukin-11 (IL-11) is involved in the regulation of tumor progression, cellular growth and differentiation. Recently, interleukin-11 receptor (IL-11R) has been detected on some cancer cells. In this study, we investigated the expression of IL-11 and IL-11R in colorectal adenocarcinoma.

METHODS: To elucidate the involvement of IL-11 and IL-11Rα in human intestinal adenocarcinomas, we examined 115 cases of surgically resected human colonic adenocarcinoma and 11 cases of adenoma by immunohistochemistry and Western blotting.

RESULTS: Among 115 cases of adenocarcinoma, 100 cases (87.0%) showed positive staining in the cytoplasm of carcinoma cells for the IL-11, and 87 cases (75.6%) were positive for the IL-11Rα. Six cases (54.5%) and four cases (36.4%) of 11 adenomas were positive for IL-11 and IL-11Rα, respectively. The expression of IL-11Rα correlated with the histological differentiation (P = 0.033503), the depth of tumor invasion (P = 0.006395), Dukes’ classification (P = 0.015648) and lymphatic invasion (P = 0.003865). However, the expression of IL-11Rα was not correlated with the venous invasion and the presence of lymph node metastasis. The expression of IL-11 was not correlated with any clinicopathological factors. In Western blot analysis, two human colorectal carcinoma cell lines and four tissues of surgically resected human carcinoma expressed both IL-11 and IL-11Rα proteins.

CONCLUSION: IL-11 and IL-11Rα are highly expressed in human colorectal adenocarcinoma and the IL-11Rα expression is correlated with clinicopathological factors. These findings suggest that the expression of IL-11Rα is an important factor for the invasion of human colorectal adenocarcinoma.

Activation of the c-Met receptor complex in fibroblasts drives invasive cell behavior by signaling through transcription factor STAT3

c-Met is the receptor for hepatocyte growth factor/scatter factor (HGF/SF). It mediates multiple cellular responses in development and adult life, and c-Met hyperactivity is associated with malignant transformation of cells and the acquisition of metastatic properties. Signal transducer and activator of transcription 3 (STAT3) has been shown to contribute to c-Met-mediated cell motility and is, thus, potentially involved in the control of invasive cell behavior. We have functionally reconstituted c-Met-dependent signal transduction in fibroblasts with the aim of studying Met-driven cell invasiveness and the role of STAT3 in this phenomenon. Activation of the system was achieved by means of a hybrid receptor comprising the extracellular domain of the nerve growth factor (NGF) receptor TrkA, the cytoplasmic part of c-Met and a C-terminally fused blue fluorescent protein (BFP). In addition, a GFP-tagged derivative of adaptor protein Gab1 was expressed. NGF-stimulation of mouse fibroblasts expressing tagged versions of both Trk-Met and Gab1 with NGF resulted in anchorage-independent growth and enhanced invasiveness. By freeze-fracture cytochemistry and electron microscopy, we were able to visualize the ligand-induced formation of multivalent receptor complex assemblies within the cell membrane. NGF-stimulation of the heterologous receptor system evoked activation of STAT3 as evidenced by tyrosine phosphorylation and the formation of STAT3 clusters at the cell membrane. siRNA-mediated ablation of STAT3 expression resulted in a drastic reduction of c-Met-driven invasiveness, indicating an important role of STAT3 in the control of this particularly relevant property of transformed cells.

PI-3K and Akt are mediators of AP-1 induction by 5-MCDE in mouse epidermal Cl41 cells

5-Methylchrysene has been found to be a complete carcinogen in laboratory animals. However, the tumor promotion effects of (+/-)-anti-5-methylchrysene-1,2-diol-3,4-epoxide (5-MCDE) remain unclear. In the present work, we found that 5-MCDE induced marked activator protein-1 (AP-1) activation in Cl41 cells. 5-MCDE also induced a marked activation of phosphatidylinositol 3-kinase (PI-3K). Inhibition of PI-3K impaired 5-MCDE-induced AP-1 transactivation, suggesting that PI-3K is an upstream kinase involved in AP-1 activation by 5-MCDE. Furthermore, we found that Akt is a PI-3K downstream mediator for 5-MCDE-induced AP-1 transactivation, whereas another PI-3K downstream kinase, p70(S6K), was not involved in AP-1 activation by 5-MCDE. Moreover, inhibition of Akt activation blocked 5-MCDE-induced activation of extracellular signal-regulated protein kinases (ERKs) and c-Jun NH(2)-terminal kinases (JNKs), whereas it did not affect p38K activation. Consistently, overexpression of a dominant-negative mutant of ERK2 or JNK1 blocked the AP-1 activation by 5-MCDE. These results demonstrate that 5-MCDE is able to induce AP-1 activation, and the AP-1 induction is specifically through a PI-3K/Akt-dependent and p70(S6K)-independent pathway.

p53 activation in chronic radiation-treated breast cancer cells: regulation of MDM2/p14ARF

Mammalian cells chronically exposed to ionizing radiation (IR) induce stress response with a tolerance to the subsequent cytotoxicity of IR. Although p53 is well documented in IR response, the signaling network causing p53 activation in chronic IR remains to be identified. Using breast carcinoma MCF+FIR cells that showed a transient radioresistance after exposure chronically to fractionated IR (FIR), the present study shows that the basal DNA binding and transcriptional activity of p53 was elevated by FIR. p53-controlled luciferase activity was strikingly induced ( approximately 7.9-fold) with little enhancement of p53/DNA binding activity ( approximately 1.3-fold). The phosphorylated p53 (Thr 55) was increased in the cytoplasm and nucleus of MCF+FIR but not in the sham-FIR control cells. On the contrary, the sham-FIR control MCF-7 cells showed a low p53 luciferase transcription ( approximately 3-fold) but a striking enhancement of p53/DNA binding (12-fold) after 5 Gy of IR. To determine the signaling elements regulating p53 activity, DNA microarray of MCF+FIR using sham-FIR MCF-7 cells as a reference demonstrated that the mRNA of p21, MDM2, and p14ARF was up-regulated. Time course Western blot analysis, however, showed no difference in p21 induction. In contrast, MDM2 that was absent in control cells and was predominantly induced by IR was not induced in MCF+FIR cells. In agreement with MDM2 inhibition, MDM2-inhibitory protein p14ARF was increased in MCF+FIR cells. In summary, these results demonstrate that up-regulation of p14ARF paralleled with MDM2 inhibition contributes to p53 accumulation in the nucleus and causes a high responsiveness of p53 in chronic IR-treated breast cancer cells.

p38 Mitogen-activated protein kinase regulation of JB6 Cl41 cell transformation promoted by epidermal growth factor

The relationship between cell transformation and p38 MAP kinase, a major mitogen-activated protein (MAP) kinase pathway converting signals of various extracellular stimuli into expression of specific target genes through activation of transcription factors, still remains unclear. The aim of the present study was to investigate the role of the p38 MAP kinase pathway in epidermal growth factor (EGF)-induced cell transformation in JB6 cells. Our data show that a dominant negative mutant of p38 MAP (DN-p38) kinase inhibits EGF-promoted JB6 Cl41 cell transformation and that SB202190, an inhibitor of p38 MAP kinase, also inhibits JB6 Cl41 cell transformation in a dose-dependent manner. Moreover, our results show that DN-p38 MAP kinase inhibits the phosphorylation of EGF-stimulated activating transcription factor-2 (ATF-2) and signal transducer and activator of transcription 1 (STAT1). Additionally, DN-p38 MAP kinase inhibits EGF-induced phosphorylation of c-Myc (Thr58/Ser62). Gel shift assays indicate that DN-p38 MAP kinase inhibits EGF-induced activator protein-1 (AP-1) DNA binding in a dose-dependent manner. These results show that p38 MAP kinase plays a key role in the regulation of EGF-induced cell transformation in JB6 cells through regulation of phosphorylation of p38 MAP kinase and activation of its target genes in phosphorylation, c-Myc cell transformation-related genes, and AP-1 binding ability.

Accelerated in vivo growth of prostate tumors that up-regulate interleukin-6 is associated with reduced retinoblastoma protein expression and activation of the mitogen-activated protein kinase pathway

Interleukin-6 (IL-6) is a multifunctional cytokine that activates the signaling pathways of Janus kinases-signal transducers and activators of transcription (STAT) and/or mitogen-activated protein kinases (MAPK) in various tumors. Thus, it modulates cell growth and apoptosis. IL-6 levels are elevated in tissues and sera from prostate cancer patients and IL-6 receptor expression has been detected in prostate cancer cell lines and clinical specimens. Continuous exposure of prostate cancer cells to IL-6 might alter their responsiveness to this cytokine. To gain more insight into the function of IL-6 in prostate carcinoma, we have inoculated LNCaP-IL-6+ cells, generated after prolonged treatment with IL-6, into nude mice (total n = 16, two independent experiments). Controls included animals bearing LNCaP-IL-6- cells, passaged at the same time as LNCaP-IL-6+ cells without supplementation of IL-6. LNCaP-IL-6+ tumor volumes were larger than those of their counterparts at all time points. There were no signs of cachexia in any of the experimental animals and all mice were free of metastases. To better understand the mechanisms responsible for accelerated growth of LNCaP-IL-6+ tumors, we have investigated the expression of cell-cycle regulatory molecules by Western blot analysis. The levels of cyclin-dependent kinase 2 were elevated in LNCaP-IL-6+ cells. There was a strong down-regulation of cyclins D1 and E in the LNCaP-IL-6+ subline. The cell-cycle inhibitor p27 was expressed at a low level in LNCaP-IL-6+ cells and could not be up-regulated by addition of IL-6. Most notably, LNCaP-IL-6+ cells exhibited a reduced expression of the hypophosphorylated form of the retinoblastoma protein (pRb). Accelerated tumor growth in our model system was also associated with alterations in IL-6-signaling pathways. The ability of IL-6 to induce tyrosine phosphorylation of STAT3 was abolished in the LNCaP-IL-6+ subline. In contrast, the levels of the MAPK extracellular signal-regulated kinases 1/2 increased in cells generated after long-term IL-6 treatment. The inhibitor of MAPK kinase PD 98059 retarded the proliferation of LNCaP-IL-6+ but not that of control cells. In summary, we show in the present study that chronic exposure of prostate cancer cells to IL-6 facilitates tumor growth in vivo by abolishment of the growth control by pRb and activation of the MAPK signaling pathway. These findings could be relevant to understand the role of IL-6 in prostate cancer progression.

The relation between the pure-tone audiogram and the click auditory brainstem response threshold in cochlear hearing loss

Auditory brainstem response thresholds for 209 ears with cochlear hearing loss were compared with the pure-tone thresholds. It is shown that the pure-tone threshold in the 2- to 4-kHz region has a one-to-one relationship with the auditory brainstem response threshold. Estimating the pure-tone threshold from the auditory brainstem response threshold, the standard error of the estimate is 11 dB. A small part of this estimation error is due to errors in the measurement of the auditory brainstem response threshold and the mean of the pure-tone thresholds at 2 and 4 kHz. The major part is due to unknown factors that are involved in the physiological relationship between the two thresholds.