GH signaling in human adipose and muscle tissue during 'feast and famine': amplification of exercise stimulation following fasting compared to glucose administration.

OBJECTIVE: Fasting and exercise stimulates, whereas glucose suppresses GH secretion, but it is uncertain how these conditions impact GH signaling in peripheral tissues. To test the original 'feast and famine hypothesis' by Rabinowitz and Zierler, according to which the metabolic effects of GH are predominant during fasting, we specifically hypothesized that fasting and exercise act in synergy to increase STAT-5b target gene expression. DESIGN AND METHODS: Eight healthy men were studied on two occasions in relation to a 1 h exercise bout: i) with a concomitant i.v. glucose infusion ('feast') and ii) after a 36 h fast ('famine'). Muscle and fat biopsy specimens were obtained before, immediately after, and 30 min after exercise. RESULTS: GH increased during exercise on both examination days and this effect was amplified by fasting, and free fatty acid (FFA) levels increased after fasting. STAT-5b phosphorylation increased similarly following exercise on both occasions. In adipose tissue, suppressors of cytokine signaling 1 (SOCS1) and SOCS2 were increased after exercise on the fasting day and both fasting and exercise increased cytokine inducible SH2-containing protein (CISH). In muscle, SOCS2 and CISH mRNA were persistently increased after fasting. Muscle SOCS1, SOCS3, and CISH mRNA expression increased, whereas SOCS2 decreased after exercise on both examination days. CONCLUSIONS: This study demonstrates that fasting and exercise act in tandem to amplify STAT-5b target gene expression (SOCS and CISH) in adipose and muscle tissue in accordance with the 'feast and famine hypothesis'; the adipose tissue signaling responses, which hitherto have not been scrutinized, may play a particular role in promoting FFA mobilization.

IL-27 alleviates the bleomycin-induced pulmonary fibrosis by regulating the Th17 cell differentiation.

BACKGROUND: Interleukin-27 (IL-27) is a multifunctional cytokine with both pro-inflammatory and immunoregulatory functions. At present, the role of IL-27 in pulmonary fibrosis remains unknown. METHODS: In this study, we observed the expression of IL-27/IL-27R in a mouse model of bleomycin (BLM)-induced pulmonary fibrosis. We verified the role of IL-27 using hematoxylin and eosin as well as Masson's staining methods and measuring the content of hydroxyproline as well as collagen I and III. We assessed the differentiation of T lymphocytes in the spleen and measured the concentration of cytokines in bronchoalveolar lavage fluid (BALF) and the expression level of relevant proteins in the JAK/STAT and TGF-ß/Smad signaling pathways in lung tissue. RESULTS: Increased IL-27 expression in BLM-induced pulmonary fibrosis was noted. IL-27 treatment may alleviate pulmonary fibrosis and increase the survival of mice. IL-27 inhibited the development of CD4(+) IL-17(+), CD4(+) IL-4(+) T, and CD4(+) Foxp3(+) cells and the secretion of IL-17, IL-4, IL-6, and TGF-ß. IL-27 induced the production of CD4(+) IL-10(+) and CD4(+) INF-γ(+) T cells. IL-27 decreased the levels of phosphorylated STAT1, STAT3, STAT5, Smad1, and Smad3 but increased the level of SOCS3. CONCLUSIONS: This study demonstrates that IL-27 potentially attenuates BLM-induced pulmonary fibrosis by regulating Th17 differentiation and cytokine secretion.

Seed targeting with tiny anti-miR-155 inhibits malignant progression of multiple myeloma cells.

BACKGROUND: miR-155 acts as a ubiquitous oncogene in major classes of human cancers and is a potential target for therapeutic intervention. However, the role of miR-155 in multiple myeloma is poorly understood. METHODS: To explore the role of miR-155 in multiple myeloma, we assessed the influence of tiny seed-targeting anti-miR-155 (t-anti-miR-155) on multiple myeloma cell line (RPMI-8266) viability and apoptosis in vitro. RESULTS: t-anti-miR-155 significantly inhibited multiple myeloma cell proliferation, migration, and colony formation. Additionally, t-anti-miR-155 significantly increased CD19 positive cell numbers, which are novel biomarkers for multiple myeloma and suppressor of cytokine signaling 1(SOCS1) was shown to be a target gene for miR-155 in multiple myeloma. Finally, the miR-155 signaling pathway was investigated by KEGG assay. CONCLUSION: miR-155 in RPMI-8266 cells is a critical oncomiR in multiple myeloma and seed-targeting t-anti-miR-155 might be a novel strategy for miR-155-based therapeutics.

Quercetagetin inhibits macrophage-derived chemokine in HaCaT human keratinocytes via the regulation of signal transducer and activator of transcription 1, suppressor of cytokine signalling 1 and transforming growth factor-ß1.

BACKGROUND: Inflammatory chemokines, such as macrophage-derived chemokine (MDC/CCL22), are elevated in the serum and lesioned skin of patients with atopic dermatitis (AD), and are ligands for C-C chemokine receptor 4, which is predominantly expressed on T helper 2 lymphocytes, basophils and natural killer cells. We have previously reported that quercetagetin has an inhibitory activity on inflammatory chemokines, which is induced by interferon (IFN)-γ and tumour necrosis factor (TNF)-α, occurring via inhibition of the signal transducer and activator of transcription 1 (STAT1) signal. OBJECTIVES: To investigate the specific mechanisms of quercetagetin on the STAT1 signal. METHODS: We confirmed the inhibitory activity of quercetagetin on MDC and STAT1 in HaCaT keratinocytes. The interaction between STAT1 and IFN-γR1 was investigated using immunoprecipitation. The small interfering RNA approach was used to investigate the role of suppressor of cytokine signalling 1 (SOCS1) and transforming growth factor (TGF)-ß1 induced by quercetagetin. RESULTS: Quercetagetin inhibited the expression of MDC at both the protein and mRNA levels in IFN-γ- and TNF-α-stimulated HaCaT human keratinocytes. Moreover, quercetagetin inhibited the phosphorylation of STAT1 through upregulation of SOCS1. Increased expression of SOCS1 disrupted the binding of STAT1 to IFN-γR1. Furthermore, quercetagetin augmented the expression of TGF-ß1, which is known to modulate the immune response and inflammation. CONCLUSIONS: These results suggest that quercetagetin may be a potent inhibitor of the STAT1 signal, which could be a new molecular target for anti-inflammatory treatment, and may thus have therapeutic applications as an immune modulator in inflammatory diseases such as AD.

Dynamic expression of the suppressor of cytokine signaling-3 and cytokines in the cerebral basilar artery of rats with subarachnoid hemorrhage, and the effect of acetylcholine.

BACKGROUND: There are complex interactions between acetylcholine (ACh), the suppressor of cytokine signaling-3 (SOCS-3), and cytokines, however, little is known about their dynamic expression or their effects on cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH). Therefore, we aimed to describe and clarify the dynamic expression of SOCS-3 and cytokines after SAH, as well as the relationships between the levels of SOCS-3, cytokines, and ACh. METHODS: The rat model of single cisterna magna injection was used to mimic acute SAH. The degree of CVS was indicated by lumen diameter and artery wall thickness under H&E staining. A semi-quantitative immunohistochemical analysis method was used to clarify the role of SOCS-3 in the CVS after SAH. We also measured the content of IL-6 and IL-10 in cerebrospinal fluid. RESULTS: We found that SOCS-3 expression levels increased rapidly within 12 h after SAH, more slowly after 12 h, and did not reach a peak within 48 h. Interleukin 6 (IL-6) levels rapidly increased within 24 h after SAH, reached a peak 24 h after SAH, and decreased slightly at 48 h. IL-10 levels increased during the first 6 h after SAH, after which this increase tapered off. ACh treatment reduced IL-6 levels and resulted in elevated levels of SOCS-3, but had no effect on IL-10 expression. Furthermore, ACh treatment relieved basilar arterial vasospasm, whereas mecamylamine pretreatment counteracted the activity of ACh. CONCLUSIONS: Taken together, these data indicate that SOCS-3 was involved in vasospasm via an IL-6- and IL-10-related mechanism, and that CVS following SAH could be reversed by the intraventricular injection of ACh.

Upregulation of SOCS-1 by Nutlin-3 in acute myeloid leukemia cells but not in primary normal cells.

OBJECTIVE: It has been shown that SOCS-1 plays an important role in the proper control of cytokine/growth factor responses and acts as a tumor suppressor in acute myeloid leukemias. Therefore, the objective of the present study was to evaluate the in vitro effect of treatment with Nutlin-3, a small molecule inhibitor of the MDM2/p53 interaction, on the expression of the suppressor of cytokine signaling 1 in primary acute myeloid leukemia cells and in myeloid cell lines with differential p53 status. METHOD: The expression of the suppressor of cytokine signaling 1 was quantitatively analyzed by real-time PCR in myeloid p53wild-type (OCI and MOLM) and p53null HL-60, leukemic cell lines, in patient-derived acute myeloid leukemia blasts, and in primary normal cell types, such as macrophages, endothelial cells, and bone marrow mesenchymal stem cells. The p53-dependence of the suppressor of cytokine signaling 1 upregulation that is induced by Nutlin-3 was analyzed in experiments performed using siRNA for p53, while the functional upregulation of the suppressor of cytokine signaling 1 was analyzed by assessing the levels of phosphorylated STAT-3. RESULTS: Nutlin-3 significantly upregulated the transcription of the suppressor of cytokine signaling 1 in p53wild-type OCI and MOLM but not in p53deleted p53null HL60, myeloid leukemic cell lines, as well as in primary acute myeloid leukemia blasts. Conversely, and somewhat unexpectedly, Nutlin-3 did not modulate the suppressor of cytokine signaling 1 expression in primary normal macrophages, endothelial cells, and bone marrow mesenchymal stem cells. The p53-dependent upregulation of the suppressor of cytokine signaling 1 by Nutlin-3 was associated with the downregulation of phosphorylated STAT-3, a major molecular target of the suppressor of cytokine signaling 1. CONCLUSION: Overall, our data suggest a potential role for the suppressor of cytokine signaling 1 as a therapeutic target of Nutlin-3 in p53 wild-type acute myeloid leukemias.

Myxovirus resistance, osteopontin and suppressor of cytokine signaling 3 polymorphisms predict hepatitis C virus therapy response in an admixed patient population: comparison with IL28B.

OBJECTIVES: Suppressor of cytokine signaling 3, myxovirus resistance protein and osteopontin gene polymorphisms may influence the therapeutic response in patients with chronic hepatitis C, and an association with IL28 might increase the power to predict sustained virologic response. Our aims were to evaluate the association between myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 gene polymorphisms in combination with IL28B and to assess the therapy response in hepatitis C patients treated with pegylated-interferon plus ribavirin. METHOD: Myxovirus resistance protein, osteopontin, suppressor of cytokine signaling 3 and IL28B polymorphisms were analyzed by PCR-restriction fragment length polymorphism, direct sequencing and real-time PCR. Ancestry was determined using genetic markers. RESULTS: We analyzed 181 individuals, including 52 who were sustained virologic responders. The protective genotype frequencies among the sustained virologic response group were as follows: the G/G suppressor of cytokine signaling 3 (rs4969170) (62.2%); T/T osteopontin (rs2853744) (60%); T/T osteopontin (rs11730582) (64.3%); and the G/T myxovirus resistance protein (rs2071430) genotype (54%). The patients who had ≥3 of the protective genotypes from the myxovirus resistance protein, the suppressor of cytokine signaling 3 and osteopontin had a greater than 90% probability of achieving a sustained response (p<0.0001). The C/C IL28B genotype was present in 58.8% of the subjects in this group. The sustained virological response rates increased to 85.7% and 91.7% by analyzing C/C IL28B with the T/T osteopontin genotype at rs11730582 and the G/G suppressor of cytokine signaling 3 genotype, respectively. Genetic ancestry analysis revealed an admixed population. CONCLUSION: Hepatitis C genotype 1 patients who were responders to interferon-based therapy had a high frequency of multiple protective polymorphisms in the myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 genes. The combined analysis of the suppressor of cytokine signaling 3 and IL28B genotypes more effectively predicted sustained virologic response than IL28B analysis alone.

Underlying pathways for interferon risk to type II diabetes mellitus.

UNLABELLED: It has been known that chronic liver treatments interfere with blood glucose metabolism. It was recognized that diabetes mellitus among chronic hepatitis C was greater in other types of chronic liver diseases. Hepatitis C directly promotes insulin resistance through the proteosomal degradation of insulin resistance substrate. It suppressed hepatocyte glucose uptake through down-regulation of surface expression of glucose transporter. Long-term exposure to cytokine over expression seems to be cytotoxic to both beta cells of the pancreas and to hepatocytes. Elevated tumor necrosis factor-a, or its neutralization, increased insulin sensitivity. Interferon-a may also elevate the serum level of interleukin-1 which is cytotoxic to pancreatic islet cells. Both diabetes mellitus and resistance to interferon-a therapy are abnormally mediated by over-expression of suppressor of cytokine signaling-1 in hepatocytes of chronic hepatitis C patients. CONCLUSION: These data suggest that interferon-a therapy should be administered with caution in patients showing any predisposition to Diabetes mellitus. Anti inflammatory therapy is critically recommended as a protector against disease development due to cytokine mediated Diabetes mellitus during hepatitis C therapy, since inflammation seems to be a main candidate to interferon suspected diabetogenesis.

Myxovirus resistance, osteopontin and suppressor of cytokine signaling 3 polymorphisms predict hepatitis C virus therapy response in an admixed patient population: comparison with IL28B

OBJECTIVES: Suppressor of cytokine signaling 3, myxovirus resistance protein and osteopontin gene polymorphisms may influence the therapeutic response in patients with chronic hepatitis C, and an association with IL28 might increase the power to predict sustained virologic response. Our aims were to evaluate the association between myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 gene polymorphisms in combination with IL28B and to assess the therapy response in hepatitis C patients treated with pegylated-interferon plus ribavirin. METHOD: Myxovirus resistance protein, osteopontin, suppressor of cytokine signaling 3 and IL28B polymorphisms were analyzed by PCR-restriction fragment length polymorphism, direct sequencing and real-time PCR. Ancestry was determined using genetic markers. RESULTS: We analyzed 181 individuals, including 52 who were sustained virologic responders. The protective genotype frequencies among the sustained virologic response group were as follows: the G/G suppressor of cytokine signaling 3 (rs4969170) (62.2%); T/T osteopontin (rs2853744) (60%); T/T osteopontin (rs11730582) (64.3%); and the G/T myxovirus resistance protein (rs2071430) genotype (54%). The patients who had ≥3 of the protective genotypes from the myxovirus resistance protein, the suppressor of cytokine signaling 3 and osteopontin had a greater than 90% probability of achieving a sustained response (p<0.0001). The C/C IL28B genotype was present in 58.8% of the subjects in this group. The sustained virological response rates increased to 85.7% and 91.7% by analyzing C/C IL28B with the T/T osteopontin genotype at rs11730582 and the G/G suppressor of cytokine signaling 3 genotype, respectively. Genetic ancestry analysis revealed an admixed population. CONCLUSION: Hepatitis C genotype 1 patients who were responders to interferon-based therapy had a high frequency of multiple protective polymorphisms in the myxovirus ...

Bisphosphonates inhibit phosphorylation of signal transducer and activator of transcription 3 and expression of suppressor of cytokine signaling 3: implications for their effects on innate immune function and osteoclastogenesis.

OBJECTIVE: This study tested the effects of bisphosphonates (BPs) on the suppressor of cytokine signaling 3 (SOCS3) protein in macrophages. SOCS3 has been shown to regulate cell differentiation and survival; however, its potential role in mediating the effects of BPs has not been explored. STUDY DESIGN: The cell viability of murine RAW 267.4 macrophages was assessed after culturing with control medium or media containing increasing concentrations of 2 BPs (ibandronate or clodronate) for 24, 48, and 72 hours. The phosphorylation status of signal transducer and activator of transcription 3 (STAT3) and the expression of SOCS3 protein levels were determined by Western blot analysis. RESULTS: In control cultures, STAT3 phosphorylation and STAT3 and SOCS3 protein levels increased within 5 minutes after the addition of fresh medium. This increase was inhibited in cultures treated with both BPs. Macrophage cell viability also decreased after BP treatment. CONCLUSIONS: These data demonstrate that, in addition to their effects on macrophage viability, BPs can decrease STAT3 and SOCS3 expression, which are important modulators of immune responses and bone homeostasis.

The activation of leptin-mediated survivin is limited by the inducible suppressor SOCS-3 in MCF-7 cells.

Although leptin has been found to be implicated in obesity-related breast carcinogenesis in postmenopausal women, the molecular mechanisms involved are yet to be defined. Recently, the antiapoptotic gene survivin has been recognized as a target gene for leptin in breast cancer. The aim of this study was to investigate the effect of leptin on the expression of survivin and on the transcriptional activity of its promoter in MCF-7 breast cancer cells. We also studied the potential involvement of SOCS-3 (a negative regulator of leptin's main signaling pathway JAK2/STAT3) in the expression of leptin-mediated survivin. Our results showed a significant increase in the mRNA (dose-dependent increase of 40-70%) and protein expression levels of survivin 24 h post-leptin treatment, which was followed by a significant decrease at 48 and 72 h (of 60-70%). In accordance, a chromatin immunoprecipitation assay revealed an initial strong binding of STAT3 to the survivin promoter, which was no longer detected after 24 h. Myc/mad/max network proteins and histone H3 acetylation status were not found to contribute to the expression of leptin-mediated survivin. Furthermore, a protein immunoprecipitation assay detected an enhanced SOCS-3 binding to the long isoform of leptin's receptor (Ob-Rb) 48 and 72 h after leptin administration, thus conferring inhibition to leptin signaling. In conclusion, our findings suggest, for the first time to our knowledge, that the effect of leptin on the antiapoptotic gene survivin is limited by the inhibitory role of SOCS-3 in the leptin-activated JAK2/STAT3 signaling pathway in MCF-7 breast cancer cells.

Negative impact of rAAV2 mediated expression of SOCS3 on the regeneration of adult retinal ganglion cell axons.

Intravitreal injections of recombinant ciliary neurotrophic factor (rCNTF) protect adult rat retinal ganglion cells (RGCs) after injury and stimulate regeneration, an effect enhanced by co-injection with a cAMP analogue (CPT-cAMP). This effect is partly mediated by PKA and associated signaling pathways, but CPT-cAMP also moderates upregulation of suppressor of cytokine signaling (SOCS) pathways after rCNTF injection, which will also enhance the responsiveness of RGCs to this and perhaps other cytokines. We now report that intravitreal injections of CPT-cAMP do not potentiate RGC axonal regeneration when CNTF is expressed via an adeno-associated viral vector (rAAV2), and concomitantly we show that increases in retinal SOCS mRNA expression are less when CNTF is delivered using the vector. We also directly tested the impact of elevated SOCS3 expression on the survival and regeneration of injured adult RGCs by injecting a bicistronic rAAV2-SOCS3-GFP vector into the vitreous of eyes in rats with a peripheral nerve graft sutured onto the cut optic nerve. Overexpression of SOCS3 resulted in an overall reduction in axonal regrowth and almost complete regeneration failure of RGCs transduced with the rAAV2-SOCS3-GFP vector. Furthermore, rAAV2-mediated expression of SOCS3 abolished the normally neurotrophic effects elicited by intravitreal rCNTF injections. In summary, CNTF delivery to the retina using viral vectors may be more effective than bolus rCNTF injections because the gene therapy approach has a less pronounced effect on neuron-intrinsic SOCS repressor pathways. Our new gain of function data using rAAV2-SOCS3-GFP demonstrate the negative impact of enhanced SOCS3 expression on the regenerative potential of mature CNS neurons.

Gene expression profiling concerning mineralization in human dental pulp cells treated with mineral trioxide aggregate.

INTRODUCTION: This study investigated changes in gene expressions related to mineralization when mineral trioxide aggregate (MTA) is applied in vitro to human dental pulp cells (HDPCs). METHODS: MTA in a Teflon tube (diameter 10 mm, height 2 mm) was applied to HDPCs. Empty tube-applied HDPCs were used as negative control. Total RNA was extracted at 6, 24, and 72 hours after MTA application for microarray analysis. The results were confirmed selectively by performing reverse transcriptase-polymerase chain reaction for genes that showed changes of more than 2-fold or less than half. RESULTS: Of the 24,546 genes, 109 genes were up-regulated more than 2-fold (eg, THBS1, VCAN, BHLHB2, FN1, COL10A1, TUFT1, and HMOX1), and 69 genes were down-regulated below 50% (eg, DCN, SOCS2, and IL8). CONCLUSIONS: These results suggest that rather than being a bio-inert material, MTA affects pulp cells in various ways. MTA appears to affect mineralization and induces slight inflammation and protective role against slight inflammation.

The anti-inflammatory effects of interleukin-4 are not mediated by suppressor of cytokine signalling-1 (SOCS1).

While it is known that the anti-inflammatory effects of interleukin (IL)-4 require new protein synthesis, the exact mechanisms by which IL-4 suppresses the production of pro-inflammatory cytokines by human monocytes and macrophages is unclear. IL-4 rapidly induced suppressor of cytokine signalling-1 (SOCS1) mRNA and protein, which peaked at 60 min, much earlier than lipopolysaccharide (LPS)-induced SOCS1 mRNA and protein which were consistently maximal 4 hr post-exposure. SOCS1 is a molecule generally considered to be induced for negative feedback of inflammatory processes. We investigated whether the early induction of SOCS1 by IL-4 was responsible for the suppression of LPS-induced tumour necrosis factor (TNF)-alpha production by IL-4. IL-4 suppressed LPS-induced TNF-alpha in freshly isolated monocytes at the level of transcription but acted by a different, possibly translational, mechanism in monocytes cultured overnight in macrophage colony-stimulating factor (M-CSF). Despite different modes of regulation by IL-4, the kinetics and magnitude of induction of SOCS1 mRNA and protein by IL-4 in the two cell types were identical. There was no significant difference in the suppression by IL-4 of LPS-induced TNF-alpha production by bone-marrow derived macrophages from wild-type mice, Ifngamma(-/-) mice and mice lacking SOCS1 (Socs1(-/-)Ifngamma(-/-)). These data suggest that SOCS1 is not involved in the suppression of LPS-induced TNF-alpha production by IL-4.

Cholinergic agonists regulate JAK2/STAT3 signaling to suppress endothelial cell activation.

The cholinergic anti-inflammatory pathway is a physiological mechanism that inhibits cytokine production and minimizes tissue injury during inflammation. Previous investigations revealed that cholinergic stimulation (via cholinergic agonists and vagus nerve stimulation) suppresses endothelial cell activation and leukocyte recruitment. The purpose of this study was to investigate the mechanisms by which cholinergic agonists (e.g., nicotine and GTS-21) regulate endothelial cell activation. Specifically, we examined the effects of cholinergic agonists on IL-6-mediated endothelial cell activation through the JAK2/STAT3 signaling pathway. Treatment of macrovascular human umbilical vein endothelial cells (HUVECs) and microvascular endothelial cells (MVECs) with the cholinergic agonists nicotine and GTS-21 significantly reduced IL-6-mediated monocyte chemoattractant protein-1 (MCP-1) production and ICAM-1 expression which are regulated through the JAK2/STAT3 pathway. We found that treatment of endothelial cells with cholinergic agonists significantly reduced STAT3 activation by phosphorylation and DNA binding. The inhibition of STAT3 phosphorylation was reversed by sodium orthovanadate, an inhibitor of tyrosine phosphatases, as well as by NSC-87877 suggesting a SHP1/2-dependent mechanism. Further investigations showed that cholinergic agonists reduced the phosphorylation of JAK2, an upstream component of the JAK2/STAT3 pathway. Finally, we observed that nicotine and GTS-21 treatment decreased levels of SOCS3 (suppressor of cytokine signaling; a regulator of the inflammatory activity of IL-6) in activated endothelial cells. These data demonstrate that cholinergic agonists suppress IL-6-mediated endothelial cell activation through the JAK2/STAT3 pathway. Our results have significant implications for better understanding the therapeutic potential of cholinergic agonists for treating IL-6 mediated inflammatory conditions.

Precision-cut slice cultures of tumors from MMTV-neu mice for the study of the ex vivo response to cytokines and cytotoxic drugs.

Ex vivo analysis of signaling pathways operating in tumor tissue is complicated by the three-dimensional structure, in particular by stroma-epithelial interactions. Studies performed with pure populations of tumor cells usually do not take into account this issue. One possibility to preserve the tissue architecture is the use of tumor slices. However, diffusion of oxygen and nutrients may become limiting factors, resulting in decreased cell viability and change of tissue morphology, especially after long-term incubation of slices. By using precision cut slices of defined thickness, we were able to establish culture conditions for tumor material obtained from MMTV-neu transgenic mice, which allow the study of the action of cytokines and cytotoxic drugs for up to 24 h. A slice thickness of 160 mum was found to be optimal for viability and handling of material. These slices were highly responsive to the action of the cytokine IFN-gamma, as evident form the increase of pY701 STAT1, detected by both immunohistochemistry and western blotting, and by the increase of mRNA levels of the IFN-gamma response genes IRF-1, SOCS-1, and STAT1, analyzed by reverse transcriptase-polymerase chain reaction. Furthermore, induction of apoptosis and increase of DNA damage could be monitored after treatment with IFN-gamma or doxorubicin. The slices were also a convenient source for the establishment of explant cultures of tumor epithelial cells. It is concluded that cultivation of precision-cut tumor slices provides a convenient way for the ex vivo molecular analysis of MMTV-neu tumor tissue under conditions which closely simulate the situation in vivo and can provide an alternative to in vivo experiments.

Foxp3-dependent microRNA155 confers competitive fitness to regulatory T cells by targeting SOCS1 protein.

Foxp3(+) regulatory T (Treg) cells limit pathogenic immune responses to self-antigens and foreign antigens. An essential role for microRNA (miRNA) in the maintenance and function of Treg cells, revealed by the Treg cell-specific Dicer ablation, raised a question as to a specific miRNA contribution. We found that Foxp3 controlled the elevated miR155 expression required for maintaining Treg cell proliferative activity and numbers under nonlymphopenic conditions. Moreover, miR155 deficiency in Treg cells resulted in increased suppressor of cytokine signaling 1 (SOCS1) expression accompanied by impaired activation of signal transducer and activator of transcription 5 (STAT5) transcription factor in response to limiting amounts of interleukin-2. Our studies suggest that Foxp3-dependent regulation of miR155 maintains competitive fitness of Treg cell subsets by targeting SOCS1, and they provide experimental support for a proposed role for miRNAs in ensuring the robustness of cellular phenotypes.

Insulin regulates SOCS2 expression and the mitogenic effect of IGF-1 in mesangial cells.

Renal hypertrophy and deposition of extracellular matrix proteins are consistent findings in diabetic nephropathy and these processes can be halted or reversed by euglycemic control. Using DNA microarray analysis of glomerular RNA from control and diabetic rats we found that the expression levels of insulin-like growth factor 1 receptor (IGF-1R) were increased while those of suppressor of cytokine signaling 2 (SOCS2) and STAT5 were decreased. All of these changes were normalized by islet cell transplantation. Overexpression of SOCS2 in rat mesangial cells inhibited IGF-1-induced activation of extracellular signal-regulated kinase, which subsequently reduced type IV collagen and DNA synthesis, an effect due to interaction of SOCS2 with IGF-1R. Inhibition of SOCS2 overexpression by small interfering RNA suppressed IGF-1R-mediated actions by preventing phosphorylation of tyrosine 317 in the p66Shc adaptor protein; however, overexpression of either SOCS1 or SOCS3 did not affect IGF-1R signaling. Insulin directly increased STAT5 and SOCS2 expression in mesangial cells. This study shows that insulin can inhibit the mitogenic action of IGF-1 in mesangial cells by regulating STAT5/SOCS2 expression. Insulin deficiency may contribute to the mesangial expansion found in diabetes through reduced STAT5/SOCS2 expression.