The phosphotidyl inositol 3-kinase/Akt signal pathway is involved in interleukin-6-mediated Mcl-1 upregulation and anti-apoptosis activity in basal cell carcinoma cells

Reversine, a selective MPS1 inhibitor, induced autophagic cell death via diminished glucose uptake and ATP production in cholangiocarcinoma cells

Reversine is a selective inhibitor of mitotic kinase monopolar spindle 1 (MPS1) and has been reported as an anticancer agent in various cancers. The effects of reversine on bile duct cancer, cholangiocarcinoma (CCA), a lethal cancer in Northeastern Thailand, were investigated. This study reports that reversine inhibited cell proliferation of CCA cell lines in dose- and time-dependent manners but had less inhibitory effect on an immortalized cholangiocyte cell line. Reversine also triggered apoptotic cell death by decreasing anti-apoptotic proteins, Bcl-XL and Mcl-1, increasing Bax pro-apoptotic protein and activating caspase-3 activity. Moreover, reversine induced autophagic cell death by increasing LC3-II and Beclin 1 while decreasing p62. Reversine activated autophagy via the AKT signaling pathway. Additionally, this study demonstrated for the first time that reversine could diminish the expression of Hypoxia-Inducible Factor 1- alpha (HIF-1α) and glucose transporter 1 (GLUT1), resulting in a reduction of glucose uptake and energy production in CCA cell lines. These findings suggest that reversine could be a good candidate as an alternative or supplementary drug for CCA treatment.

Interleukin-6 Rescues Lymphocyte from Apoptosis and Exhaustion Induced by Chronic Hepatitis C Virus Infection

Chronic hepatitis C virus (HCV) infection appears to trigger the onset of immune exhaustion and apoptosis to potentially assist viral persistence inside the host, eventually leading to exacerbated conditions of inflammation and hepatocarcinogenesis. Growing evidence suggests that spontaneous apoptosis of peripheral blood mononuclear cells (PBMCs) could be one of the potential immune impairment mechanisms in chronic viral infection. Interleukin-6 (IL-6) is a pleiotropic cytokine that plays an essential role in regulating immune and inflammatory responses. Owing to its known role in priming T cell growth, differentiation, and inhibition of lymphocyte apoptosis, we investigated the protective effect of IL-6 in rescuing lymphocytes from apoptosis and functional exhaustion in chronic HCV infection. The expression pattern of antiapoptotic (Mcl-1 and Bcl-2), proapoptotic (caspase-3 and Bim) genes along with interferon gamma (IFN-γ) and T cell inhibitory receptor (TIM-3) was analyzed before and after in vitro IL-6 treatment of patient-derived PBMCs. It was observed that the expression of antiapoptotic genes, Mcl-1 and Bcl-2 increased (threefolds and twofolds, respectively) and there was a considerable downregulation in T cell inhibitory receptor (TIM-3) and caspase-3. Similarly, the capacity of PBMCs to produce IFN-γ was also significantly increased (p < 0.001) depicting the promising nature of IL-6 in enhancing lymphocyte effector function. Summing it up, the study supports the positive role of IL-6 in rescuing PBMC population; however, the cytokine alone is not sufficient to sustain the adaptive immunity. It could be used as a potential candidate for combinational therapy along with other regulatory factors for ex vivo enhancement of lymphocyte and may help in moving one step toward adoptive T cell therapy in chronic HCV infection.

Reawakening of dormant estrogen-dependent human breast cancer cells by bone marrow stroma secretory senescence

Background

Dormant estrogen receptor positive (ER+) breast cancer micrometastases in the bone marrow survive adjuvant chemotherapy and recur stochastically for more than 20 years. We hypothesized that inflammatory cytokines produced by stromal injury can re-awaken dormant breast cancer cells.

Methods

We used an established in vitro dormancy model of Michigan Cancer Foundation-7 (MCF-7) breast cancer cells incubated at clonogenic density on fibronectin-coated plates to determine the effects of inflammatory cytokines on reactivation of dormant ER+ breast cancer cells. We measured induction of a mesenchymal phenotype, motility and the capacity to re-enter dormancy. We induced secretory senescence in murine stromal monolayers by oxidation, hypoxia and estrogen deprivation with hydrogen peroxide (H₂O₂), carbonyl-cyanide m-chlorophenylhydrazzone (CCCP) and Fulvestrant (ICI 182780), respectively, and determined the effects on growth of co-cultivated breast cancer cells.

Results

Exogenous recombinant human (rh) interleukin (IL)-6, IL-8 or transforming growth factor β1 (TGFβ1) induced regrowth of dormant MCF-7 cells on fibronectin-coated plates. Dormant cells had decreased expression of E-cadherin and estrogen receptor α (ERα) and increased expression of N-cadherin and SNAI2 (SLUG). Cytokine or TGFβ1 treatment of dormant clones induced formation of growing clones, a mesenchymal appearance, increased motility and an impaired capacity to re-enter dormancy. Stromal injury induced secretion of IL-6, IL-8, upregulated tumor necrosis factor alpha (TNFα), activated TGFβ and stimulated the growth of co-cultivated MCF-7 cells. MCF-7 cells induced secretion of IL-6 and IL-8 by stroma in co-culture.

Conclusions

Dormant ER+ breast cancer cells have activated epithelial mesenchymal transition (EMT) gene expression programs and downregulated ERα but maintain a dormant epithelial phenotype. Stromal inflammation reactivates these cells, induces growth and a mesenchymal phenotype. Reactivated, growing cells have an impaired ability to re-enter dormancy. In turn, breast cancer cells co-cultured with stroma induce secretion of IL-6 and IL-8 by the stroma, creating a positive feedback loop.

Oncostatin M treatment increases the responsiveness toward cisplatin-based chemoradiotherapy in cervical cancer cells in a STAT3-dependent manner

Cervical cancer stage-dependent therapies include surgery, chemotherapy, radiotherapy and chemoradiotherapy. Concurrent cisplatin-based chemoradiotherapy (CCRT) is the standard therapy for locally advanced cervical carcinoma (FIGO>IIB), however therapy resistance in a subset of patients is still a major clinical challenge. The present study aimed to analyze the impact of Oncostatin M (OSM) stimulation on CCRT-induced cell death. The present study used cells derived from cervical squamous cell carcinomas (SW756, 808, CaSki and 879) and adenocarcinoma (HeLa). The cervical carcinoma cells were HPV18-positive (HeLa, SW756, 808) or HPV16-positive (CaSki, 879). In addition to the established cell lines HeLa, SW756 and CaSki, the more recently generated cervical cancer cells 808 and 879 were also used. To analyze their radiosensitivity, cells were treated with increasing doses of irradiation (0-8 Gy). To mimic chemotherapy, radiotherapy or CCRT in vitro, the cells were challenged with 0.975 µg/ml cisplatin, irradiated with 6 Gy or a combination. A total of 10 ng/ml OSM was applied for 2 h prior to the respective therapy. The responsiveness toward radiation alone varied among the cervical carcinoma cells. CaSki, 808 and 879 cells were resistant to irradiation up to 8 Gy. OSM pre-treatment sensitized two out of five cell lines (HeLa and 879) to irradiation. Notably, all tested cells were sensitized by OSM for CCRT-treatment, particularly in the less radiosensitive cells. Cell death enhancement was dependent on phosphorylated signal transducer and activator of transcription 3 (STAT3; Tyr705) signaling activation as demonstrated with a dominant-negative version of STAT3 interfering with phosphorylation at Tyr705 (dnSTAT3-Y705F). In conclusion, OSM pre-treatment was able to override resistance to CCRT via the STAT3 signaling pathway.

Interleukin-6: A promising cytokine to support liver regeneration and adaptive immunity in liver pathologies

Liver pathologies (fibrosis, cirrhosis, alcoholic, non-alcoholic diseases and hepatocellular carcinoma) represent one of the most common causes of death worldwide. A number of genetic and environmental factors contribute to the development of liver diseases. Interleukin-6 (IL-6) is a pleiotropic cytokine, exerting variety of effects on inflammation, liver regeneration, and defence against infections by regulating adaptive immunity. Due to its high abundance in inflammatory settings, IL-6 is often viewed as a detrimental cytokine. However, accumulating evidence supports the view that IL-6 has a beneficial impact in numerous liver pathologies, due to its roles in liver regeneration and in promoting an anti-inflammatory response in certain conditions. IL-6 promotes proliferation, angiogenesis and metabolism, and downregulates apoptosis and oxidative stress; together these functions are critical for mediating hepatoprotection. IL-6 is also an important regulator of adaptive immunity where it induces T cell differentiation and regulates autoimmunity. It can augment antiviral adaptive immune responses and mitigate exhaustion of T cells during chronic infection. This review focuses on studies that present IL-6 as a key factor in regulating liver regeneration and in supporting effector immune functions and suggests that these functions of IL-6 can be exploited in treatment strategies for liver pathologies.

Acute myotube protein synthesis regulation by IL-6-related cytokines

IL-6 and leukemia inhibitory factor (LIF), members of the IL-6 family of cytokines, play recognized paradoxical roles in skeletal muscle mass regulation, being associated with both growth and atrophy. Overload or muscle contractions can induce a transient increase in muscle IL-6 and LIF expression, which has a regulatory role in muscle hypertrophy. However, the cellular mechanisms involved in this regulation have not been completely identified. The induction of mammalian target of rapamycin complex 1 (mTORC1)-dependent myofiber protein synthesis is an established regulator of muscle hypertrophy, but the involvement of the IL-6 family of cytokines in this process is poorly understood. Therefore, we investigated the acute effects of IL-6 and LIF administration on mTORC1 signaling and protein synthesis in C2C12 myotubes. The role of glycoprotein 130 (gp130) receptor and downstream signaling pathways, including phosphoinositide 3-kinase (PI3K)-Akt-mTORC1 and signal transducer and activator of transcription 3 (STAT3)-suppressor of cytokine signaling 3 (SOCS3), was investigated by administration of specific siRNA or pharmaceutical inhibitors. Acute administration of IL-6 and LIF induced protein synthesis, which was accompanied by STAT3 activation, Akt-mTORC1 activation, and increased SOCS3 expression. This induction of protein synthesis was blocked by both gp130 siRNA knockdown and Akt inhibition. Interestingly, STAT3 inhibition or Akt downstream mTORC1 signaling inhibition did not fully block the IL-6 or LIF induction of protein synthesis. SOCS3 siRNA knockdown increased basal protein synthesis and extended the duration of the protein synthesis induction by IL-6 and LIF. These results demonstrate that either IL-6 or LIF can activate gp130-Akt signaling axis, which induces protein synthesis via mTORC1-independent mechanisms in cultured myotubes. However, IL-6- or LIF-induced SOCS3 negatively regulates the activation of myotube protein synthesis.

Targeted disruption of TC-PTP in the proliferative compartment augments STAT3 and AKT signaling and skin tumor development

Tyrosine phosphorylation is a vital mechanism that contributes to skin carcinogenesis. It is regulated by the counter-activities of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Here, we report the critical role of T-cell protein tyrosine phosphatase (TC-PTP), encoded by Ptpn2, in chemically-induced skin carcinogenesis via the negative regulation of STAT3 and AKT signaling. Using epidermal specific TC-PTP knockout (K14Cre.Ptpn2^fl/fl) mice, we demonstrate loss of TC-PTP led to a desensitization to tumor initiator 7,12-dimethylbenz[a]anthracene (DMBA)-induced apoptosis both in vivo epidermis and in vitro keratinocytes. TC-PTP deficiency also resulted in a significant increase in epidermal thickness and hyperproliferation following exposure to the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). Western blot analysis showed that both phosphorylated STAT3 and phosphorylated AKT expressions were significantly increased in epidermis of TC-PTP-deficient mice compared to control mice following TPA treatment. Inhibition of STAT3 or AKT reversed the effects of TC-PTP deficiency on apoptosis and proliferation. Finally, TC-PTP knockout mice showed a shortened latency of tumorigenesis and significantly increased numbers of tumors during two-stage skin carcinogenesis. Our findings reveal that TC-PTP has potential as a novel target for the prevention of skin cancer through its role in the regulation of STAT3 and AKT signaling.

Interleukin-6 inhibits apoptosis of exocrine gland tissues under inflammatory conditions

Interleukin (IL)-6 is a multi-functional cytokine that can either promote or suppress tissue inflammation depending on the specific disease context. IL-6 is elevated in the exocrine glands and serum of patients with Sjögren's syndrome (SS), but the specific role of IL-6 in the pathogenesis of this disease has not been defined. In this study, we showed that IL-6 expression levels were increased with age in C56BL/6.NOD-Aec1Aec2 mice, a primary SS model, and higher than the control C57BL/6 mice. To assess the role of IL-6 during the immunological phase of SS development, a neutralizing anti-IL-6 antibody was administered into 16 week-old female C56BL/6.NOD-Aec1Aec2 mice, 3 times weekly for a consecutive 8 weeks. Neutralization of endogenous IL-6 throughout the immunological phase of SS development led to increased apoptosis, caspase-3 activation, leukocytic infiltration, and IFN-γ- and TNF-α production in the salivary gland. To further determine the effect of IL-6 on the apoptosis of exocrine gland cells, recombinant human IL-6 or the neutralizing anti-IL-6 antibody was injected into female C57BL/6 mice that received concurrent injection of anti-CD3 antibody to induce the apoptosis of exocrine gland tissues. Neutralization of IL-6 enhanced, whereas administration of IL-6 inhibited apoptosis and caspase-3 activation in salivary and lacrimal glands in this model. The apoptosis-suppressing effect of IL-6 was associated with up-regulation of Bcl-xL and Mcl-1 in both glands. Moreover, IL-6 treatment induced activation of STAT3 and up-regulated Bcl-xL and Mcl-1 gene expression in a human salivary gland epithelial cell line. In conclusion, IL-6 inhibits the apoptosis of exocrine gland tissues and exerts a tissue-protective effect under inflammatory conditions including SS. These findings suggest the possibility of using this property of IL-6 to preserve exocrine gland tissue integrity and function under autoimmune and inflammatory conditions.

Expression of leukemia inhibitory factor in the rat retina following acute ocular hypertension

The aim of the present study was to investigate the expression of leukemia inhibitory factor (LIF) and its downstream signaling pathways in the rat retina following acute ocular hypertension. The intraocular pressure of the rats was elevated to 110 mmHg for 1 h by infusing the anterior chamber with normal saline. The retinal tissues were obtained 12 h, 24 h, and 2, 3 and 7 days after termination of the ocular hypertension. Hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were performed to assess the morphological changes and the apoptosis of retinal cells, respectively. Quantification of the retinal ganglion cells (RGCs) was performed using fluorogold retrograde (FG) staining. The expression levels of LIF, LIF receptor (LIFR), signal transducers and activators of transcription 3 (STAT3), phosphorylated STAT3 (P-STAT3), Akt, phosphorylated-Akt (P-Akt), extracellular signal-regulated kinase (ERK) and phosphorylated ERK (P-ERK) were determined at different time-points following acute ocular hypertension using western blot analysis. Reverse transcription-quantitative polymerase chain reaction was performned to detect the mRNA expression levels of LIF and LIFR. The results revealed that 12 h, 24 h, 2, 3 and 7 days after reperfusion, the thickness of the inner nuclear layer and the inner plexiform layer was decreased, with a significant reduction in the number of RGCs, as determined using TUNEL and FG staining. The expression levels of LIF and LIFR were increased following acute ocular hypertension. At 12 h post-retinal reperfusion, the expression levels of P-STAT3 and P-Akt were significantly upregulated, while the expression of P-ERK was decreased. The changes in the expression levels of LIF and LIFR suggested that LIF may be important in the process of degeneration/protection following retinal ischemia induced by acute ocular hypertension, via activation of the Janus kinase/STAT and Akt signaling pathways.

Immunohistochemical analysis of the mechanistic target of rapamycin and hypoxia signalling pathways in basal cell carcinoma and trichoepithelioma

BACKGROUND

Basal cell carcinoma (BCC) is the most common cancer in Caucasians. Trichoepithelioma (TE) is a benign neoplasm that strongly resembles BCC. Both are hair follicle (HF) tumours. HFs are hypoxic microenvironments, therefore we hypothesized that hypoxia-induced signalling pathways could be involved in BCC and TE as they are in other human malignancies. Hypoxia-inducible factor 1 (HIF1) and mechanistic/mammalian target of rapamycin (mTOR) are key players in these pathways.

OBJECTIVES

To determine whether HIF1/mTOR signalling is involved in BCC and TE.

METHODS

We used immunohistochemical staining of formalin-fixed paraffin-embedded BCC (n = 45) and TE (n = 35) samples to assess activity of HIF1, mTORC1 and their most important target genes. The percentage positive tumour cells was assessed manually in a semi-quantitative manner and categorized (0%, <30%, 30-80% and >80%).

RESULTS

Among 45 BCC and 35 TE examined, expression levels were respectively 81% and 57% (BNIP3), 73% and 75% (CAIX), 79% and 86% (GLUT1), 50% and 19% (HIF1α), 89% and 88% (pAKT), 55% and 61% (pS6), 15% and 25% (pMTOR), 44% and 63% (PHD2) and 44% and 49% (VEGF-A). CAIX, Glut1 and PHD2 expression levels were significantly higher in TE when only samples with at least 80% expression were included.

CONCLUSIONS

HIF and mTORC1 signalling seems active in both BCC and TE. There are no appreciable differences between the two with respect to pathway activity. At this moment immunohistochemical analyses of HIF, mTORC1 and their target genes does not provide a reliable diagnostic tool for the discrimination of BCC and TE.

Induction of chemokine receptor CXCR4 expression by transforming growth factor-β1 in human basal cell carcinoma cells

BACKGROUND

Higher CXCR4 expression enhances basal cell carcinoma (BCC) invasion and angiogenesis. The underlying mechanism of increased CXCR4 expression in invasive BCC is still not well understood.

OBJECTIVE

To investigate the mechanisms involved in the regulation of CXCR4 expression in invasive BCC.

METHODS

We used qRT-PCR, RT-PCR, Western blot, and flow cytometric analyses to examine different CXCR4 levels among the clinical samples, co-cultured BCC cells and BCC cells treated with recombinant transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF). Immunohistochemical studies were used to demonstrate the correlation between TGF-β1 and CXCR4 expressions. The signal transduction pathway and transcriptional regulation were confirmed by treatments with chemical inhibitors, neutralizing antibodies, or short interfering RNAs, as well as luciferase reporter activity.

RESULTS

Invasive BCC has higher TGF-β1 and CTGF levels compared to non-invasive BCC. Non-contact dermal fibroblasts co-culture with human BCC cells also increases the expression of CXCR4 in BCC cells. Treatment with recombinant human TGF-β1, but not CTGF, enhanced the CXCR4 levels in time- and dose-dependent manners. The protein level and surface expression of CXCR4 in human BCC cells was increased by TGF-β1 treatment. TGF-β1 was intensely expressed in the surrounding fibroblasts of invasive BCC and was positively correlated with the CXCR4 expression of BCC cells. The transcriptional regulation of CXCR4 by TGF-β1 is mediated by its binding to the TGF-β receptor II and phosphorylation of the extracellular signal-related kinase 1/2 (ERK1/2)-ETS-1 pathway.

CONCLUSION

TGF-β1 induces upregulation of CXCR4 in human BCC cells by phosphorylation of ERK1/2-ETS-1 pathway.

Integrating pathway analysis and genetics of gene expression for genome-wide association study of basal cell carcinoma

Genome-wide association studies (GWASs) have primarily focused on marginal effects for individual markers and have incorporated external functional information only after identifying robust statistical associations. We applied a new approach combining the genetics of gene expression and functional classification of genes to the GWAS of basal cell carcinoma (BCC) to identify potential biological pathways associated with BCC. We first identified 322,324 expression-associated single-nucleotide polymorphisms (eSNPs) from two existing GWASs of global gene expression in lymphoblastoid cell lines (n = 955), and evaluated the association of these functionally annotated SNPs with BCC among 2,045 BCC cases and 6,013 controls in Caucasians. We then grouped them into 99 KEGG pathways for pathway analysis and identified two pathways associated with BCC with p value <0.05 and false discovery rate (FDR) <0.5: the autoimmune thyroid disease pathway (mainly HLA class I and II antigens, p < 0.001, FDR = 0.24) and Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway (p = 0.02, FDR = 0.49). Seventy-nine (25.7%) out of 307 significant eSNPs in the JAK-STAT pathway were associated with BCC risk (p < 0.05) in an independent replication set of 278 BCC cases and 1,262 controls. In addition, the association of JAK-STAT signaling pathway was marginally validated using 16,691 eSNPs identified from 110 normal skin samples (p = 0.08). Based on the evidence of biological functions of the JAK-STAT pathway on oncogenesis, it is plausible that this pathway is involved in BCC pathogenesis.

Inhibition of pre-B cell colony-enhancing factor attenuates inflammation and apoptosis induced by pandemic H1N1 2009 in lung endothelium

The recent pandemic influenza A (H1N1 2009) virus infection has caused acute lung injury in susceptible population resulting in high mortality in ICU patients. In this report, we observed the effect of pre-B cell colony-enhancing factor (PBEF) on the inflammation and apoptosis in H1N1-infected human pulmonary microvascular endothelial cells (HPMECs). We constructed an in vitro HPMEC monolayer model. The results showed that H1N1 2009 induced the increased expression of inflammatory cytokines (IL-6/IL-8/TNF-α/IP-10) and apoptosis factors (FasL/TRAIL) in infected HPMECs. However, PBEF silencing with siRNA inhibited the expression of some inflammatory cytokines and decreased the apoptosis mediated by FasL. We conclude that PBEF might be partially responsible for the localized inflammatory response to H1N1 2009 in the lung microvascular endothelium and the H1N1-induced endothelial cell apoptosis probably through the FasL-mediated pathway.

Interleukin-6: a potential target for post-thrombotic syndrome

BACKGROUND

Deep vein thrombosis (DVT) and its associated sequelae, post-thrombotic syndrome (PTS), are significant health care problems in the United States. It is estimated that a maximum of 60% of patients diagnosed with DVT develop PTS, which is characterized by extensive perivenous and mural fibrosis. Interleukin-6 (IL-6) has been linked to fibrosis, and high circulating plasma levels have been found to increase the risk of developing DVT. The aim of this study was to elucidate the role of IL-6 in the progression of vein wall fibrosis by using a mouse model of DVT.

METHODS AND RESULTS

C57BL/6 mice (n = 136) were treated with either anti-IL-6 monoclonal antibody or control rat-immunoglobulin G. Thrombus was induced by using an inferior vena cava ligation model. The inferior vena cava and thrombus were harvested at days 2, 6, or 14 for thrombus weight, gene expression of IL-6 and/or C-C motif chemokine ligand 2 (CCL2), inflammatory cell recruitment, and morphometric analysis of vein wall fibrosis. Mice treated with anti-IL-6 had smaller thrombus weights at day 2, decreased vein wall gene expression and protein concentration of CCL2 at day 2, and impaired vein wall influx of monocytes from days 2 to 6, as compared with controls. Intimal thickness was reduced by 44% (p < 0.05) and vein wall collagen deposition was decreased by 30% at day 14 in the anti-IL-6 group (p < 0.05).

CONCLUSIONS

Neutralizing IL-6 throughout venous thrombogenesis decreased the production of CCL2, reduced monocyte recruitment, and decreased vein wall intimal thickness and fibrosis. These results suggest that IL-6 may serve as a therapeutic target to prevent the fibrotic complications seen in PTS.

Neuroprotection of interleukin-6 against NMDA-induced apoptosis and its signal-transduction mechanisms

We have previously shown that interleukin-6 (IL-6)-protected neurons against the suppression of neuronal vitality and overload of intracellular Ca(2+) induced by glutamate or N-methyl-D: -aspartate (NMDA). Herein we provide further evidence for IL-6 neuroprotection against NMDA-induced apoptosis and explore the signal-transduction mechanisms underlying the anti-apoptotic action of IL-6. Cerebellar granule neurons (CGNs) from postnatal 8-day infant rats were chronically exposed to IL-6 (40 or 120 ng/ml) for 8 days, and stimulated with NMDA (100 μM) for 30 min. To observe the signaling pathways, we employed AG490 (5 or 10 μM), an inhibitor of Janus kinases (JAKs), or LY294002 (5 or 10 μM), an inhibitor of phosphatidylinositol 3-kinase (PI3K), to pretreat the CGNS together with IL-6. The levels of phosphorylation for the downstream effectors of JAKs and PI3K, i.e., phosphorylated STAT3 and Akt, were quantified by Western blot assay. In the cultured CGNs with various drug exposures, the expressions of Bcl-2, Bax, and caspase-3 were measured by real-time PCR and Western blot, and the percentage of apoptotic nuclei was tested by Hoechst 33342 staining. After the CGNs were chronically exposed to IL-6, NMDA stimulation led to an increase in the expression of Bcl-2 mRNA and a decrease in the expression of Bax and caspase-3 mRNAs and proteins when compared with those neurons lacking IL-6 exposure. IL-6 pretreatment of the neurons without NMDA stimulation concentration-dependently enhanced the expressions of Bcl-2 mRNA and protein while attenuating the expressions of Bax and caspase-3 mRNAs and proteins in comparison with control lacking any treatment. Furthermore, IL-6 prevented the increase in the percentage of apoptotic neurons induced by NMDA. The combined pretreatment of the CGNs with AG490 and IL-6 or with LY294002 and IL-6 reduced these anti-apoptotic effects of IL-6. Neither AG490 nor LY294002 exposure alone altered the expressions of Bcl-2, Bax, and cleaved caspase-3 proteins. IL-6 up-regulated the levels of phosphorylated STAT3 and Akt, and this was blocked by AG490 and LY294002, respectively. These results suggest that IL-6 protects neurons against NMDA-induced apoptosis, and that the IL-6 neuroprotection is jointly mediated by JAK-STAT3 and PI3K-Akt signaling pathways.

Translation initiation: a critical signalling node in cancer

Mammalian target of rapamycin (mTOR) is a master regulator of translation initiation that controls the recruitment of ribosomes to mRNA templates in response to intracellular and extracellular cues. Evidence suggests that mTOR and its direct downstream targets, S6K and eIF4E/4E-BP, play significant roles in oncogenesis, and that inhibiting this pathway holds promise as an anti-proliferative approach. Recent genome-wide analyses of mutations in human cancers indicate that transformed cells activate a handful of processes and signalling pathways that are major contributors to their phenotype. Here we review the current literature implicating mTOR and translation initiation downstream of many of these various signalling pathways and processes usurped in human cancers. This review highlights the widespread activation of mTOR/eIF4E following acquisition of oncogenic lesions and its implication in promoting the transformation phenotype and indicates that targeting the control of translation initiation makes logical sense as a broad-acting therapeutic approach.

Modification of alternative splicing of Mcl-1 pre-mRNA using antisense morpholino oligonucleotides induces apoptosis in basal cell carcinoma cells

Myeloid cell leukemia-1 (Mcl-1, Mcl-1L) is an anti-apoptotic protein of the Bcl-2 family that acts as a critical molecule in apoptosis control. Mcl-1 pre-mRNA can undergo alternative splicing to yield the short isoform, Mcl-1S, which resembles BH3-only pro-apoptotic proteins and induces apoptosis. Overexpression of Mcl-1 may play a role in various human tumors, and Mcl-1 may serve as a target in cancer therapy. In this study, we found an imbalance between the expression levels of Mcl-1L and Mcl-1S in the skin basal cell carcinoma (BCC) cell line when compared with primary keratinocytes. We showed that overexpression of Mcl-1S induces apoptosis in BCC cells. Finally, we showed that Mcl-1 antisense morpholino oligonucleotides (AMOs) can specifically target Mcl-1 pre-mRNA and shift the splicing pattern from Mcl-1L to Mcl-1S mRNA and protein. This shift increases the level of pro-apoptotic Mcl-1S and reduces the level of anti-apoptotic Mcl-1L, which induces apoptosis in BCC cells and AGS cells, a human gastric adenocarcinoma epithelial cell line. Thus, this report provides a strategy for cancer therapy in which AMOs change the alternative splicing pattern of Mcl-1 pre-mRNA and thereby induce apoptosis.

Conditioned media from mouse osteosarcoma cells promote MC3T3-E1 cell proliferation using JAKs and PI3-K/Akt signal crosstalk

The maintenance of bone mass requires a strict balance between bone formation by osteoblasts and bone resorption by osteoclasts. In tumoral bone environment, tumor cells frequently disturb this balance by interaction with bone cells to create a favorable site for tumor growth, and promote pathological bone changes. Thus, elucidation of the mechanisms underlying interaction between tumor cells and bone cells might eventually lead to a more rational strategy for therapeutic intervention for bone tumors and better understanding of bone biology. In the present study, the effects of mouse osteosarcoma cells on mouse preosteoblastic cells were determined by assessment of cell viability, osteoblastic differentiation and signal transduction pathways. MOS-J/POS-1 conditioned media (CM) significantly induced MC3T3-E1 cell proliferation in a dose-dependent manner and reduced both alkaline phosphatase activity and mineralized nodule formation. Piceatannol, AG490, LY294002 and rapamycin significantly abrogated this up-regulated cell proliferation; however, UO126 and STAT3 inhibitor peptide did not affect this up-regulated cell proliferation. MOS-J/POS-1 CM activated ERK 1/2, STAT3 and Akt signal transduction pathways; however, pro-proliferating signal induced by MOS-J/POS-1 CM was transmitted via Akt not ERK 1/2 and STAT3 pathways. Furthermore, Western blot analyses clearly revealed novel signal crosstalk between JAKs and PI3-K/Akt in osteoblastic cells. The specific factor(s) involved in MOS-J/POS-1 CM-induced MC3T3-E1 cell proliferation that use JAKs/PI3-K/Akt/mTOR pathway remain(s) to be determined. Determination of the specific factor(s) responsible for JAKs and PI3-K/Akt signal crosstalk that results in up-regulated preosteoblast proliferation will offer new insight into the pathology of osteosarcoma as well as other bone-related diseases.

Role of interleukin-6 signalling in glucose and lipid metabolism

Derangements in whole body glucose and lipid metabolism, accompanied by insulin resistance, are key features of obesity and the metabolic syndrome. A role for inflammation as a causative factor is an emerging concept in the field of metabolic disease. Research has centred on identifying important inflammatory markers, and tumour necrosis factor-alpha has been highlighted as a key mediator of insulin resistance, as well as interleukin-6 (IL-6). A parallel ongoing endeavour is the unravelling of molecular mechanisms underlying the beneficial effects of physical exercise on whole body glucose and lipid metabolism. Release of IL-6 from the contracting skeletal muscle has been proposed to be one of the molecular signals promoting the beneficial exercise-induced effects. These two opposing views of IL-6 underscore that the role of IL-6 in whole body physiology is incompletely resolved. This review aims at summarizing the current data on mechanisms by which IL-6 may impact on glucose and lipid metabolism.

Involvement of matrix metalloproteinase-13 in stromal-cell-derived factor 1 alpha-directed invasion of human basal cell carcinoma cells

Basal cell carcinoma (BCC) is one of the most common skin neoplasms in humans and is usually characterized by local aggressiveness with little metastatic potential, although deep invasion, recurrence, and regional and distant metastases may occur. Here, we studied the mechanism of BCC invasion. We found that human BCC tissues and a BCC cell line had significant expression of CXCR4, which was higher in invasive than non-invasive BCC types. Further, of 19 recurrent tumors among 390 BCCs diagnosed during the past 12 years, 17/19 (89.5%) had high CXCR4 expression. We found that the CXCR4 ligand, stromal-cell-derived factor 1alpha (SDF-1alpha), directed BCC invasion and that this was mediated by time-dependent upregulation of mRNA expression and gelatinase activity of matrix metalloproteinase-13 (MMP-13). The transcriptional regulation of MMP-13 by SDF-1alpha was mediated by phosphorylation of extracellular signal-related kinase 1/2 and activation of the AP-1 component c-Jun. Finally, CXCR4-transfected BCC cells injected into nude mice induced aggressive BCCs that co-expressed CXCR4 and MMP-13. The identification of SDF-1alpha/CXCR4 as an important factor in BCC invasiveness may contribute insight into mechanisms involved in the aggressive potential of human BCC and may improve therapy for invasive BCCs.

Over-expression of interleukin-6 enhances cell survival and transformed cell growth in human malignant cholangiocytes

BACKGROUND/AIMS

Over-expression of IL-6 has been implicated in cholangiocarcinoma growth but the cellular mechanisms involved are unknown. Our aims were to assess the mechanisms by which over-expression of IL-6 promotes transformed cell growth in malignant cholangiocytes.

METHODS

Stably transfected cell lines over-expressing IL-6 were derived from malignant human cholangiocytes. Transformed cell growth was assessed by anchorage independent growth in vitro and by xenograft growth in nude mice. Expression of the anti-apoptotic protein Mcl-1 was quantitated by immunoblot analysis and by real-time PCR. Gene silencing was performed using siRNA. Dominant negative upstream kinase activators and isoform-specific constructs were used to evaluate the involvement of p38 MAP kinase signaling pathways.

RESULTS

Over-expression of IL-6 increased xenograft growth, anchorage independent growth and cell survival but did not significantly alter cell proliferation. The basal expression of Mcl-1 was increased in IL-6 over-expressing cells. Selective knockdown of Mcl-1 by siRNA increased gemcitabine-induced cytotoxicity. Moreover, IL-6 increased Mcl-1 mRNA and protein expression via a p38 MAPK dependent mechanism.

CONCLUSIONS

These data demonstrate a major role of survival signaling pathways in mediating the effects of IL-6 over-expression in cholangiocarcinoma growth. Mcl-1 is identified as a mediator of IL-6-induced tumor cell survival and shown to be transcriptionally regulated by IL-6 via a p38 MAPK dependent pathway. We conclude that modulation of IL-6 mediated survival signaling pathways involving the p38 MAPK or downstream targets such as Mcl-1 may prove useful therapeutic strategies for human cholangiocarcinoma.

Over-expression of interleukin-6 enhances cell survival and transformed cell growth in human malignant cholangiocytes

BACKGROUND/AIMS

Over-expression of IL-6 has been implicated in cholangiocarcinoma growth but the cellular mechanisms involved are unknown. Our aims were to assess the mechanisms by which over-expression of IL-6 promotes transformed cell growth in malignant cholangiocytes.

METHODS

Stably transfected cell lines over-expressing IL-6 were derived from malignant human cholangiocytes. Transformed cell growth was assessed by anchorage independent growth in vitro and by xenograft growth in nude mice. Expression of the anti-apoptotic protein Mcl-1 was quantitated by immunoblot analysis and by real-time PCR. Gene silencing was performed using siRNA. Dominant negative upstream kinase activators and isoform-specific constructs were used to evaluate the involvement of p38 MAP kinase signaling pathways.

RESULTS

Over-expression of IL-6 increased xenograft growth, anchorage independent growth and cell survival but did not significantly alter cell proliferation. The basal expression of Mcl-1 was increased in IL-6 over-expressing cells. Selective knockdown of Mcl-1 by siRNA increased gemcitabine-induced cytotoxicity. Moreover, IL-6 increased Mcl-1 mRNA and protein expression via a p38 MAPK dependent mechanism.

CONCLUSIONS

These data demonstrate a major role of survival signaling pathways in mediating the effects of IL-6 over-expression in cholangiocarcinoma growth. Mcl-1 is identified as a mediator of IL-6-induced tumor cell survival and shown to be transcriptionally regulated by IL-6 via a p38 MAPK dependent pathway. We conclude that modulation of IL-6 mediated survival signaling pathways involving the p38 MAPK or downstream targets such as Mcl-1 may prove useful therapeutic strategies for human cholangiocarcinoma.

Interleukin 6 upregulates myeloid cell leukemia-1 expression through a STAT3 pathway in cholangiocarcinoma cells

Interleukin 6 (IL-6) contributes to the pathogenesis of cholangiocarcinoma by upregulating myeloid cell leukemia-1 (Mcl-1), a key antiapoptotic Bcl-2 family member protein. IL-6 can alter gene transcription via Janus kinases (JAK) and signal transducer and activator of transcription (STAT) signal cascade. We examined this cascade in IL-6 regulation of Mcl-1 transcription in human cholangiocarcinoma cell lines. STAT3 was constitutively activated (i.e., tyrosine-phosphorylated) in cholangiocarcinoma cells but not in nonmalignant cholangiocytes. Treatment with anti-IL-6 antisera or the JAK inhibitor AG490 or transfection with dominant negative STAT3 diminished Mcl-1 messenger RNA and protein levels. Likewise, these attempts to interrupt the STAT3 cascade also reduced Mcl-1 promoter activity. Site-directed mutagenesis of a putative STAT3 consensus binding sequence decreased Mcl-1 promoter activity. Chromatin immunoprecipitation analysis demonstrated a direct binding of STAT3 to the putative STAT3 binding sequences in the Mcl-1 promoter. Downregulation of Mcl-1 by AG490 sensitized the cells to apoptosis mediated by tumor necrosis factor-related apoptosis-inducing ligand. In conclusion, we have directly demonstrated a STAT3 regulatory element in the Mcl-1 promoter. Downregulation of Mcl-1 transcription by inhibiting this cascade is a potential strategy for the treatment of this cancer.

A novel peptide specifically binding to interleukin-6 receptor (gp80) inhibits angiogenesis and tumor growth

Experimental and clinical findings support the essential role of interleukin (IL)-6 in the pathogenesis of various human cancers and provide a rationale for targeted therapeutic investigations. A novel peptide, S7, which selectively binds to IL-6 receptor (IL-6R) alpha chain (gp80) and broadly inhibits IL-6-mediated events, was identified using phage display library screening. The synthetic S7 peptide specifically bound to soluble IL-6R as well as cognate human IL-6R alpha, resulting in a dose-dependent blockade of the interaction between IL-6 and IL-6R alpha. S7 peptide prevents IL-6-mediated survival signaling and sensitizes cervical cancer cells to chemotherapeutic compounds in vitro. The in vitro analysis of antiangiogenic activity showed that S7 peptide substantially inhibits IL-6-induced vascular endothelial growth factor-A expression and angiogenesis in different cancer cell lines. Furthermore, S7 peptide was bioavailable in vivo, leading to a significant suppression of IL-6-induced vascular endothelial growth factor-mediated cervical tumor growth in severe combined immunodeficient mice. These observations show the feasibility of targeting IL-6/IL-6R interaction using the small peptide and highlight its potential in the clinical applications.

Interleukin-6 induced basic fibroblast growth factor-dependent angiogenesis in basal cell carcinoma cell line via JAK/STAT3 and PI3-kinase/Akt pathways

We have previously demonstrated a xenograft of interleukin-6 (IL-6) overexpressing basal cell carcinoma (BCC) cell line induced tumors with high vasculature in nude mice. Here we asked whether IL-6 could induce angiogenic activity in BCC cell line. Tenfold concentrated conditioned medium (CM) from IL-6 overexpressing BCC cells exhibited higher angiogenic activities in chorioallantoic membrane and Matrigel plug assays, when compared with CM from vector control or parental BCC cells. The level of basic fibroblast growth factor 2 (bFGF) mRNA and secreted bFGF increased in IL-6 overexpressing BCC cells as shown by RT-PCR and ELISA, respectively. Concordantly, recombinant IL-6 treatment caused the elevation of bFGF mRNA and protein levels in parental BCC cells in a time-dependent manner. Neutralizing bFGF function by anti-bFGF antibody significantly inhibited CM-induced human umbilical vein endothelial cells (HUVEC) tube formation and Matrigel plug formation. Meanwhile, cyclooxygenase 2 (COX-2)-specific siRNA markedly abolish HUVEC tube formation. These data indicated both bFGF and COX-2 play an essential role for IL-6-induced angiogenesis in BCC cell line. Treatment with AG490 (Janus tyrosine kinase [JAK] inhibitor) and LY294002 (PI3-Kinase inhibitor) inhibited IL-6-mediated upregulation of bFGF mRNA and protein secretion. Consistently, transfection with dominant negative mutants of signal transducer and activator of transcription 3 (STAT3) and acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt) effectively abolished IL-6-mediated expression of bFGF mRNA and protein. Our data suggest that under in vitro experimental condition, bFGF and COX-2 are downstream effectors of IL-6-induced angiogenic activity in BCC cell. The IL-6-mediated bFGF upregulation is through activation of JAK/STAT3 and PI3-Kinase/Akt pathways.

Use of pyrosequencing to detect clinically relevant polymorphisms of genes in basal cell carcinoma

BACKGROUND

Pyrosequencing is a new method to detect single nucleotide polymorphisms (SNPs). Basal cell carcinoma (BCC) is one of the most common neoplasms in the world, and its incidence has been increasing worldwide in recent years. BCC is caused by an interplay between genetic and environment factors.

METHODS

Pyrosequencing and restrict fragment length polymorphism (RFLP) were used in the study. We conducted a case-control association study in BCC cases and controls from Sweden. For SNPs in IL-6, IL-10 and IL-1beta, 241 cases were at the age of 27-70 years (mean 50 years) and 260 healthy controls were 26-71 years (mean 48 years), 241 cases were 27-70 years (mean 50 years) and 574 healthy controls were 22-74 years (mean 52 years) for cyclin D1 G870A, 197 cases were 29-69 years (mean 47 years) and 574 healthy controls were 22-74 years (mean 52 years) for MTHFR C677T and A1298C. Nine SNPs for IL-6-174G/C, -634G/C and -597G/A; IL-10-1082G/A and -592C/A; IL-1beta-511C/T; cyclin D1 G870A; MTHFR C677T and A1298C were analyzed.

RESULTS

Most genotype distributions were in accordance with Hardy-Weinberg equilibrium (HWE), except IL-10-1082G/A, which had a significantly deviation from HWE in BCC cases (P<0.05). Linkage disequilibrium was observed between the -174 and -597 alleles in the IL-6 gene in the studied populations. The differences for cyclin D1 G870A and methylenetetrahydrofolate reductase (MTHFR) C677T were found between BCC cases group and control group (P<0.05, OR=1.34, 95% CI, 1.00-1.74; P<0.05, OR=1.67, 95% CI, 1.13-2.47, respectively).

CONCLUSIONS

Cyclin D1 G870A and MTHFR C677T were associated with BC cases from Sweden, the other SNPs studied here were not associated with BCC, but chance cannot be excluded.

New advances on the functions of epidermal growth factor receptor and ceramides in skin cell differentiation, disorders and cancers

Recent advances in understanding of the biological functions of the epidermal growth factor and epidermal growth factor receptor (EGF-EGFR) system and ceramide production for the maintenance of skin integrity and barrier function are reported. In particular, the opposite roles of EGFR and ceramide cascades in epithelial keratinocyte proliferation, migration and terminal differentiation are described. Moreover, the functions of ceramides in the epidermal permeability barrier are reviewed. The alterations in EGFR signaling and ceramide metabolism, which might be involved in the etiopathogenesis of diverse skin disorders and cancers, are described. New progress in understanding of skin organization, which might provide the basis for the design of new transcutaneous drug delivery techniques as well as for the development of new therapies of skin disorders and cancers, are reported.

Principles of interleukin (IL)-6-type cytokine signalling and its regulation

The IL (interleukin)-6-type cytokines IL-6, IL-11, LIF (leukaemia inhibitory factor), OSM (oncostatin M), ciliary neurotrophic factor, cardiotrophin-1 and cardiotrophin-like cytokine are an important family of mediators involved in the regulation of the acute-phase response to injury and infection. Besides their functions in inflammation and the immune response, these cytokines play also a crucial role in haematopoiesis, liver and neuronal regeneration, embryonal development and fertility. Dysregulation of IL-6-type cytokine signalling contributes to the onset and maintenance of several diseases, such as rheumatoid arthritis, inflammatory bowel disease, osteoporosis, multiple sclerosis and various types of cancer (e.g. multiple myeloma and prostate cancer). IL-6-type cytokines exert their action via the signal transducers gp (glycoprotein) 130, LIF receptor and OSM receptor leading to the activation of the JAK/STAT (Janus kinase/signal transducer and activator of transcription) and MAPK (mitogen-activated protein kinase) cascades. This review focuses on recent progress in the understanding of the molecular mechanisms of IL-6-type cytokine signal transduction. Emphasis is put on the termination and modulation of the JAK/STAT signalling pathway mediated by tyrosine phosphatases, the SOCS (suppressor of cytokine signalling) feedback inhibitors and PIAS (protein inhibitor of activated STAT) proteins. Also the cross-talk between the JAK/STAT pathway with other signalling cascades is discussed.

Principles of interleukin (IL)-6-type cytokine signalling and its regulation

The IL (interleukin)-6-type cytokines IL-6, IL-11, LIF (leukaemia inhibitory factor), OSM (oncostatin M), ciliary neurotrophic factor, cardiotrophin-1 and cardiotrophin-like cytokine are an important family of mediators involved in the regulation of the acute-phase response to injury and infection. Besides their functions in inflammation and the immune response, these cytokines play also a crucial role in haematopoiesis, liver and neuronal regeneration, embryonal development and fertility. Dysregulation of IL-6-type cytokine signalling contributes to the onset and maintenance of several diseases, such as rheumatoid arthritis, inflammatory bowel disease, osteoporosis, multiple sclerosis and various types of cancer (e.g. multiple myeloma and prostate cancer). IL-6-type cytokines exert their action via the signal transducers gp (glycoprotein) 130, LIF receptor and OSM receptor leading to the activation of the JAK/STAT (Janus kinase/signal transducer and activator of transcription) and MAPK (mitogen-activated protein kinase) cascades. This review focuses on recent progress in the understanding of the molecular mechanisms of IL-6-type cytokine signal transduction. Emphasis is put on the termination and modulation of the JAK/STAT signalling pathway mediated by tyrosine phosphatases, the SOCS (suppressor of cytokine signalling) feedback inhibitors and PIAS (protein inhibitor of activated STAT) proteins. Also the cross-talk between the JAK/STAT pathway with other signalling cascades is discussed.