Suppression of SOCS3 increases susceptibility of renal cell carcinoma to interferon-α

The Interplay Between Helicobacter pylori and Suppressors of Cytokine Signaling (SOCS) Molecules in the Development of Gastric Cancer and Induction of Immune Response

Helicobacter pylori (H. pylori) colonizes the stomach and leads to the secretion of a vast range of cytokines by infiltrated leukocytes directing immune/inflammatory response against the bacterium. To regulate immune/inflammatory responses, suppressors of cytokine signaling (SOCS) proteins bind to multiple signaling components located downstream of cytokine receptors, such as Janus kinase (JAK), signal transducers and activators of transcription (STAT). Dysfunctional SOCS proteins in immune cells may facilitate the immune evasion of H. pylori, allowing the bacteria to induce chronic inflammation. Dysregulation of SOCS expression and function can contribute to the sustained H. pylori-mediated gastric inflammation which can lead to gastric cancer (GC) development. Among SOCS molecules, dysregulated expression of SOCS1, SOCS2, SOCS3, and SOCS6 were indicated in H. pylori-infected individuals as well as in GC tissues and cells. H. pylori-induced SOCS1, SOCS2, SOCS3, and SOCS6 dysregulation can contribute to the GC development. The expression of SOCS molecules can be influenced by various factors, such as epigenetic DNA methylation, noncoding RNAs, and gene polymorphisms. Modulation of the expression of SOCS molecules in gastric epithelial cells and immune cells can be considered to control gastric carcinogenesis as well as regulate antitumor immune responses, respectively. This review aimed to explain the interplay between H. pylori and SOCS molecules in GC development and immune response induction as well as to provide insights regarding potential therapeutic strategies modulating SOCS molecules.

Identification of AKI signatures and classification patterns in ccRCC based on machine learning

Background

Acute kidney injury can be mitigated if detected early. There are limited biomarkers for predicting acute kidney injury (AKI). In this study, we used public databases with machine learning algorithms to identify novel biomarkers to predict AKI. In addition, the interaction between AKI and clear cell renal cell carcinoma (ccRCC) remain elusive.

Methods

Four public AKI datasets (GSE126805, GSE139061, GSE30718, and GSE90861) treated as discovery datasets and one (GSE43974) treated as a validation dataset were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between AKI and normal kidney tissues were identified using the R package limma. Four machine learning algorithms were used to identify the novel AKI biomarkers. The correlations between the seven biomarkers and immune cells or their components were calculated using the R package ggcor. Furthermore, two distinct ccRCC subtypes with different prognoses and immune characteristics were identified and verified using seven novel biomarkers.

Results

Seven robust AKI signatures were identified using the four machine learning methods. The immune infiltration analysis revealed that the numbers of activated CD4 T cells, CD56^dim natural killer cells, eosinophils, mast cells, memory B cells, natural killer T cells, neutrophils, T follicular helper cells, and type 1 T helper cells were significantly higher in the AKI cluster. The nomogram for prediction of AKI risk demonstrated satisfactory discrimination with an Area Under the Curve (AUC) of 0.919 in the training set and 0.945 in the testing set. In addition, the calibration plot demonstrated few errors between the predicted and actual values. In a separate analysis, the immune components and cellular differences between the two ccRCC subtypes based on their AKI signatures were compared. Patients in the CS1 had better overall survival, progression-free survival, drug sensitivity, and survival probability.

Conclusion

Our study identified seven distinct AKI-related biomarkers based on four machine learning methods and proposed a nomogram for stratified AKI risk prediction. We also confirmed that AKI signatures were valuable for predicting ccRCC prognosis. The current work not only sheds light on the early prediction of AKI, but also provides new insights into the correlation between AKI and ccRCC.

Lack of association between SOCS3 and SOCS7 polymorphisms and psoriasis

Background

Psoriasis is a common, chronic, inflammatory skin disease that involves changes taking place as a result of activation of the immune system. Suppressor of cytokine signaling proteins (SOCS) are intracellular proteins that act as endogenous inhibitors of proinflammatory pathways triggered by various cytokines. In this study, the relationship between psoriasis disease and SOCS gene polymorphisms is investigated in relation to the pathogenesis of psoriasis to clarify the psoriasis susceptibility profile.

Methods

The SOCS3 rs4969169 and SOCS7 rs3748726 polymorphisms were detected using the polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) method. The study was approved by the Clinical Research Ethics Committee of Bulent Ecevit University and performed in accordance with the ethical standards established in the 1964 Declaration of Helsinki and later amendments. All participants were informed of the parameters of the study, and they signed consent forms before being included. Statistical analysis was performed using the SPSS 18.0 (SPSS Inc.) package program.

Results

For the SOCS3 rs4969169 genotype frequency, the CC/CT genotypes represented 67%/33% in the patient group and 73%/27% in the control group. For the SOCS7 rs3748726 genotype frequency, the TT/TC/CC genotypes made up 89%/9%/1% in the patient group and 91%/8%/1% in the control group.

Conclusion

The polymorphisms of SOCS3 rs4969169 and SOCS7 rs3748726 were found to have no effective role in the pathogenesis of psoriasis. This is the first study to investigate this topic, and further studies with larger, more ethnically diverse samples are encouraged.

SOCS5 contributes to temozolomide resistance in glioblastoma by regulating Bcl-2-mediated autophagy

Temozolomide (TMZ) is the primary chemotherapeutic drug for treating glioblastoma (GBM); however, the final clinical outcome is considerably limited by the poor response and resistance to TMZ. Although autophagy is thought to be associated with chemotherapy resistance and cancer cell survival, the precise molecular mechanisms underlying this process remain elusive. The suppressor of cytokine signaling (SOCS) family is widely distributed in vivo and exerts a range of effects on tumors; however, the expression pattern and role of SOCS in GBM remains unknown. In this study, we determined that high SOCS5 expression level was associated with poor prognosis and TMZ resistance in GBM. TMZ induced an increase in SOCS5 expression level and upregulated autophagy during the acquisition of drug resistance. The observed increase in the extent of autophagy was mediated by SOCS5. Mechanistically, SOCS5 enhances the transcription of Bcl-2. Knockdown of SOCS5 inhibited TMZ chemoresistance in GBM cells through the inhibition of Bcl-2 recruited autophagy; upregulation of Bcl-2 blocked this effect. In summary, our findings revealed the involvement and underlying mechanism of SOCS5 in TMZ resistance. SOCS5 plays a critical role in GBM chemoresistance and may serve as a novel prognostic marker and therapeutic target for chemotherapeutically treating drug-resistant GBM.

Prognostic Significance of SOCS3 in Patients With Solid Tumors: A Meta-Analysis

Background

The identification of reliable biomarkers for predicting disease recurrence and the survival of patients with cancer is of great importance. Numerous previous studies have revealed that the abnormal expression of the suppressor of cytokine signaling 3 (SOCS3) was associated with patient outcomes. However, these results were inconsistent. The aim of the present study was to assess the prognostic value of SOCS3 in patients with solid tumors.

Methods

Studies focusing on the prognostic value of SOCS3 in solid tumors were searched for in the PubMed, Embase, Web of Science, and Scopus databases. We included studies that compared disease-free survival (DFS) and overall survival based on different levels of SOCS3. Other outcomes (e.g., Edmondson grading, tumor size, tumor vascular invasion, lymph node invasion, and distant metastasis) were also considered. The hazard ratio (HR)/risk ratio (RR) and corresponding 95% CI were determined.

Results

Twelve studies with 1,551 patients were included in this meta-analysis. The pooled analysis demonstrated that the higher expression of SOCS3 was significantly associated with better disease-free survival (HR:0.36, 95% CI:0.17–0.77, P < 0.001) and overall survival (HR:0.45, 95% CI:0.32–0.62, P < 0.001) compared with low expression. Moreover, SOCS3 expression was closely correlated with the Edmondson grading [odds ratio (OR):0.77, 95% CI:0.61–0.98, P = 0.033], vascular invasion (OR:0.63, 95% CI:0.52–0.78, P < 0.001), and distant metastasis (OR:0.73, 95% CI:0.51–1.03, P = 0.076). However, the levels of SOCS3 were not significantly associated with tumor size (OR:0.85, 95% CI:0.71–1.03, P = 0.090) and lymph node invasion (OR:0.73, 95% CI:0.51–1.03, P = 0.076).

Conclusion

Increased SOCS3 expression in tumor mass was associated with better DFS and OS, suggesting it might be a novel and reliable biomarker for predicting the risk of cancer recurrence and mortality.

Role of Hypoxia in the Interferon Response

In solid tumors, as the tumor grows and the disease progresses, hypoxic regions are often generated, but in contrast to most normal cells which cannot survive under these conditions, tumour cells adapt to hypoxia by HIF-driven mechanisms. Hypoxia can further promote cancer development by generating an immunosuppressive environment within the tumour mass, which allows tumour cells to escape the immune system recognition. This is achieved by recruiting immunosuppressive cells and by upregulating molecules which block immune cell activation. Hypoxia can also confer resistance to antitumor therapies by inducing the expression of membrane proteins that increase drug efflux or by inhibiting the apoptosis of treated cells. In addition, tumor cells require an active interferon (IFN) signalling pathway for the success of many anticancer therapies, such as radiotherapy or chemotherapy. Therefore, hypoxic effects on this pathway needs to be addressed for a successful treatment.

The Yin and Yang of Type I IFNs in Cancer Promotion and Immune Activation

Simple Summary

The crucial immune stimulatory functions exerted by Type I Interferons (IFNs) in cancer settings have been not only widely demonstrated during the last fifty years but also recently harnessed for therapy. However, depending on the dose and timing, and the downstream induced signatures, Type I IFNs can and do foster cancer progression and immune evasion. Dysregulations of Type I IFN signaling cascade are more and more frequently found in the tumor microenvironment, representing critical determinants of therapeutic innate and adaptive resistance to several anticancer treatments. Understanding when and through which genetic signatures Type I IFNs control or promote cancer growth is extremely urgent in order to prevent and by-pass the deleterious clinical effects and develop optimized innovative (combinatorial) strategies for an effective cancer management.

Abstract

Type I Interferons (IFNs) are key regulators of natural and therapy-induced host defense against viral infection and cancer. Several years of remarkable progress in the field of oncoimmunology have revealed the dual nature of these cytokines. Hence, Type I IFNs may trigger anti-tumoral responses, while leading immune dysfunction and disease progression. This dichotomy relies on the duration and intensity of the transduced signaling, the nature of the unleashed IFN stimulated genes, and the subset of responding cells. Here, we discuss the role of Type I IFNs in the evolving relationship between the host immune system and cancer, as we offer a view of the therapeutic strategies that exploit and require an intact Type I IFN signaling, and the role of these cytokines in inducing adaptive resistance. A deep understanding of the complex, yet highly regulated, network of Type I IFN triggered molecular pathways will help find a timely and immune“logical” way to exploit these cytokines for anticancer therapy.

Interleukin-6 induces drug resistance in renal cell carcinoma

Metastatic renal cell carcinoma (mRCC) is a tumor entity with poor prognosis due to limited therapy options. Tyrosine kinase inhibitors (TKIs), the novel targeted agents have been used for the treatment of mRCC and have shown efficacy. Interferon (IFN)-α is also one of the most frequently used agents in immunotherapy. However, drug resistance needs to be overcome to achieve a sufficiently positive effect. Interleukin-6 (IL-6), which induce suppressor of cytokine signaling-3 (SOCS3) expression, is one of the factors associated with poor prognosis of patients with renal cell carcinoma (RCC). To analyze the influence of IL-6 in drug resistance of RCC, anti-IL-6 receptor antibody was used in combination with IFN or TKIs. The SOCS3 mRNA expression level was significantly increased by IFN-α stimulation in 786-O RCC cells which were resistant to IFN, but not in ACHN cells that were sensitive to IFN. The overexpression of SOCS3 by gene transfection in ACHN significantly inhibited the growth-inhibitory effect of IFN-α. An in vivo study demonstrated that co-administration of SOCS3-targeted siRNA promoted INF-α-induced cell death and growth suppression in 786-O cell xenograft. SOCS3 could be a key component in the resistance to interferon treatment of renal cell carcinoma. Because SOCS3 is rapidly up-regulated by IL-6 and a negative regulator of cytokine signaling, IL-6 expression on RCC cells was also analyzed and the 786-O cells showed the high level of IL-6 mRNA expression under the condition of interferon stimulation. IL-6R antibody, tocilizumab, significantly suppressed cell proliferation in 786-O cells by interferon stimulation accompanied with phosphorylation of STAT1 and inhibited SOCS3 expression. The in vivo effects of combination therapy with tocilizumab and interferon showed significant suppression of 786-O tumor growth in a xenograft model. We also hypothesized that TKI resistance and IL-6 secretion are causally connected. And we found that 786-O RCC cells secrete high IL-6 levels after low dose stimulation with the TKIs sorafenib, sunitinib and pazopanib, inducing activation of AKT-mTOR pathway, NFκB, HIF-2α and VEGF expression. Tocilizumab neutralizes the AKT-mTOR pathway activation and results in reduced proliferation. A combination therapy with tocilizumab and TKI suppresses 786-O tumor growth and inhibits angiogenesis in vivo more efficient than TKI alone. Our findings suggest that IL-6 could induce drug resistance on RCC, and combination therapy of IL-6R inhibitors and IFN/TKIs may represent a novel therapeutic approach for RCC treatment.

Plasticity of Type I Interferon-Mediated Responses in Cancer Therapy: From Anti-tumor Immunity to Resistance

The efficacy of several therapeutic strategies against cancer, including cytotoxic drugs, radiotherapy, targeted immunotherapies and oncolytic viruses, depend on intact type I interferon (IFN) signaling for the promotion of both direct (tumor cell inhibition) and indirect (anti-tumor immune responses) effects. Malfunctions of this pathway in tumor cells or in immune cells may be responsible for the lack of response or resistance. Although type I IFN signaling is required to trigger anti-tumor immunity, emerging evidence indicates that chronic activation of type I IFN pathway may be involved in mediating resistance to different cancer treatments. The plastic and dynamic features of type I IFN responses should be carefully considered to fully exploit the therapeutic potential of strategies targeting IFN signaling. Here, we review available evidence supporting the involvement of type I IFN signaling in mediating resistance to various cancer therapies and highlight the most promising modalities that are being tested to overcome resistance.

Suppression of SOCS3 enhances TRAIL-induced cell growth inhibition through the upregulation of DR4 expression in renal cell carcinoma cells

Background

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a tumor-selective apoptosis inducer that is expressed in natural killer cells, whose cytotoxicity is activated by interferon (IFN). We investigated the effect of suppressor of cytokine signaling (SOCS) 3 on the expression of TRAIL receptors (DR4) and on TRAIL sensitivity in renal cell carcinoma (RCC) cells.

Methods

Vector expression, RNA interference and IL-6 receptor antibody tocilizumab were used to investigate the functional role of SOCS3 in DR4 expression. Immunoprecipitation was employed to detect the biochemical interaction between SOCS3 and DR4. The expression of DR4 induced by combination with IFN-α and tocilizumab was also examined by immunohistochemical staining using mice xenograft model.

Results

DR4 expression was up-regulated by IFN stimulation in RCC cells. 786-O cells were resistant to TRAIL and showed higher SOCS3 expression. ACHN cells showed higher DR4 expression and lower SOCS3 expression. Suppression of SOCS3 up-regulated DR4 expression and enhanced the TRAIL sensitivity in 786-O cells. In ACHN cells, DR4 expression was down-regulated by transfection with pCI-SOCS3, and the cells became resistant to TRAIL. Immunoprecipitation revealed the biochemical interaction between SOCS3 and DR4. A marked increase in IFN-induced DR4 protein expression after tocilizumab treatment was observed by immunohistochemical staining in the tumor from the mice xenograft model.

Conclusions

Our results indicate that IFN and SOCS3 regulate DR4 expression in RCC cells. Combination therapy with IFN-α, tocilizumab and an anti-DR4 agonistic ligand appears to effectively inhibit advanced RCC cell growth.

The role and gene expression profile of SOCS3 in colorectal carcinoma

SOCS3 has been postulated to play a role in the occurrence and progression of malignancies. However, the relationship of SOCS3 with colorectal carcinoma remains poorly understood. The purpose of the study was to explore the role of SOCS3 in colorectal carcinoma and its underlying mechanisms. Protein and mRNA expression of SOCS3 in colorectal carcinoma and normal colorectal mucosa was detected using immunohistochemistry and real-time quantitative PCR. SOCS3 expression was significantly lower in colorectal carcinoma tissue than in normal colorectal mucosa, and was negatively correlated with tumor invasion depth, lymph node metastasis, differentiation degree, and TNM stage. A stably transfected colorectal carcinoma cell line (8348SOCS3) with high expression of SOCS3 was established. The effects of SOCS3 overexpression on the growth, proliferation, invasion and tumor formation of colorectal carcinoma cells were examined by CCK-8 assay, transwell method and tumorigenicity assays in nude mice. Then we found SOCS3 overexpression significantly decreased proliferation and invasion capability of 8348 cells in vitro and in vivo. Furthermore, the effect of SOCS3 overexpression on the gene expression profile of colorectal carcinoma cells was analyzed using human genome arrays. The results revealed 369 genes that were differentially expressed in 8348SOCS3 cells. 193 genes was significantly increased and 176 genes was significantly decreased. Bioinformatics analysis demonstrated that high SOCS3 expression affected multiple signaling pathways in colorectal carcinoma including TGF-β/Smads, NF-κB, and HIF-MAPK pathways. Especially for the TGF-β/Smads pathways, high SOCS3 expression could inhibit TGF-β1 expression and activate Smad4 expression. These data suggested that low expression of SOCS3 was associated with the occurrence and progression of colorectal carcinoma. SOCS3 protein may be a useful indicator for malignancy and prognosis of colorectal carcinoma and also a new target for gene therapy.

Structural optimization and evaluation of novel 2-pyrrolidone-fused (2-oxoindolin-3-ylidene)methylpyrrole derivatives as potential VEGFR-2/PDGFRβ inhibitors

Background

Tumor angiogenesis, essential for tumor growth and metastasis, is tightly regulated by VEGF/VEGFR and PDGF/PDGFR pathways, and therefore blocking those pathways is a promising therapeutic target. Compared to sunitinib, the C(5)-Br derivative of 2-pyrrolidone-fused (2-oxoindolin-3-ylidene)methylpyrrole has significantly greater in vitro activities against VEGFR-2, PDGFRβ, and tube formation.

Results and discussion

The objective of this study was to perform further structural optimization, which revealed certain new products with even more potent anti-tumor activities, both cellularly and enzymatically. Of these, 15 revealed ten- and eightfold stronger potencies against VEGFR-2 and PDGFRβ than sunitinib, respectively, and showed selectivity against HCT116 with a favorable selective index (SI > 4.27). The molecular docking results displayed that the ligand–protein binding affinity to VEGFR-2 could be enhanced by introducing a hydrogen-bond-donating (HBD) substituent at C(5) of (2-oxoindolin-3-ylidene)methylpyrrole such as 14 (C(5)-OH) and 15 (C(5)-SH).

Conclusions

Among newly synthetic compounds, 7 and 13–15 exhibited significant inhibitory activities against VEGFR-2 and PDGFRβ. Of these, the experimental results suggest that 15 might be a promising anti-proliferative agent. Graphical abstract

Synthesis and Evaluation of Novel 2-Pyrrolidone-Fused (2-Oxoindolin-3-ylidene)methylpyrrole Derivatives as Potential Multi-Target Tyrosine Kinase Receptor Inhibitors

Signaling pathways of VEGFs and PDGFs are crucial in tumor angiogenesis, which is essential in solid tumor progression and metastasis. This study reports our strategy for designing and synthesizing a series of novel 2-pyrrolidone-fused (2-oxoindolin-3-ylidene)methylpyrrole derivatives as potential multi-target tyrosine kinase receptor inhibitors. The target compounds were obtained by condensation of 5-substituted oxindoles with N-substituted 2-pyrrolidone aldehyde 7 in satisfactory yields. Of these, 11 and 12 had the highest potency and, compared to sunitinib, showed: (1) significant increase in anti-proliferation of various cancer cells with a favorable selective index (SI); (2) higher inhibitory potency against both VEGFR-2 and PDGFRβ. The molecular modeling results showed that, in terms of VEGFR-2 binding, the synthesized products had a similar binding mode to sunitinib but with tighter interaction.

In vitro and in vivo conditional sensitization of hepatocellular carcinoma cells to TNF-induced apoptosis by taxol

High mortality among hepatocellular carcinoma (HCC) patients reflects both late diagnosis and low curability, due to pharmacoresistance. Taxol (TAX) is toxic for many human HCC-derived cell lines, yet its clinical efficacy on HCCs is poor. Combining TAX with other drugs appears a promising possibility to overcome such refractoriness. We analyzed whether combining tumor necrosis factor (TNF) with TAX would improve their toxicity. Human HCC-derived cell lines were treated with TAX or TNF, alone or combined. Apoptosis was assessed by morphology and flow-cytometry. Several pro- and anti-apoptotic molecules were evaluated by western blotting and/or enzymatic assay. After a 24 hour treatment, TNF was ineffective and TAX modestly cytotoxic, whereas HCC cells were conditionally sensitized to TNF by TAX. Indeed some relevant parameters were shifted to a prodeath setting: TNF-receptor 1 was increased, SOCS3, c-FLIP and pSTAT3 were markedly downregulated. These observations provide a significant clue to critically improve the drug susceptibility of HCC cells by combining 2 agents, TAX and TNF. The sequential application of TAX at a low dosage followed by TNF for only a short time triggered a strong apoptotic response. Of interest, prior TAX administration could also sensitize to TNF-induced apoptosis in the Yoshida AH-130 hepatoma transplanted in mice. Therefore, scrutinizing the possibility to develop similar combination drug regimens in suitable preclinical models seems highly advisable.

Interleukin-6 as an emerging regulator of renal cell cancer

BACKGROUND

Our knowledge on the molecular basis of kidney cancer metastasisis still relatively low. About 25-30% of patients suffering from clear cell renal cell carcinoma (ccRCC)present metastatic disease at the time of primary diagnosis. Only 10% of patients diagnosed with stage IV disease survive 5 years and 20-50% of patients diagnosed with localized tumor develop metastases within 3 years. High mortality of patients with this cancer is associated with a large potential for metastasis and resistance to oncologic treatments such as chemo- and radiotherapy. Literature data based on studies conducted on other types of cancers suggest that in metastatic ccRCC, the complex of interleukin-6 (IL-6) and its soluble receptor (sIL-6R; complex IL-6/sIL-6R) and the signal transduction pathway (gp130/STAT3) might play a key role in this process.

PURPOSE

Therefore, in this review we focus on the role of IL-6 and its signaling pathways as a factor for development and spread of RCC. Analyzing the molecular basis of cancer spreading will enable the development of prognostic tests, evaluate individual predisposition for metastasis, and produce drugs that target metastases. As the development of effective systemic treatments evolve from advancements in molecular biology, continued studies directed at understanding the genetic and molecular complexities of this disease are critical to improve RCC treatment options.

MicroRNA-185 targets SOCS3 to inhibit beta-cell dysfunction in diabetes

Diabetes is the most common and complex metabolic disorder, and one of the most important health threats now. MicroRNAs (miRNAs) are a group of small non-coding RNAs that have been suggested to play a vital role in a variety of physiological processes, including glucose homeostasis. In this study, we investigated the role of miR-185 in diabetes. MiR-185 was significantly downregulated in diabetic patients and mice, and the low level was correlated to blood glucose concentration. Overexpression of miR-185 enhanced insulin secretion of pancreatic β-cells, promoted cell proliferation and protected cells from apoptosis. Further experiments using in silico prediction, luciferase reporter assay and western blot assay demonstrated that miR-185 directly targeted SOCS3 by binding to its 3'-UTR. On the contrary to miR-185's protective effects, SOCS3 significantly suppressed functions of β-cell and inactivated Stat3 pathway. When treating cells with miR-185 mimics in combination with SOCS3 overexpression plasmid, the inhibitory effects of SOCS3 were reversed. While combined treatment of miR-185 mimics and SOCS3 siRNA induced synergistically promotive effects compared to either miR-185 mimics or SOCS3 siRNA treatment alone. Moreover, we observed that miR-185 level was inversely correlated with SOCS3 expression in diabetes patients. In conclusion, this study revealed a functional and mechanistic link between miR-185 and SOCS3 in the pathogenesis of diabetes. MiR-185 plays an important role in the regulation of insulin secretion and β-cell growth in diabetes. Restoration of miR-185 expression may serve a potentially promising and efficient therapeutic approach for diabetes.

Abrogation of STAT3 signaling cascade by zerumbone inhibits proliferation and induces apoptosis in renal cell carcinoma xenograft mouse model

Persistent activation of signal transducer and activator of transcription 3 (STAT3) is one of the characteristic features of renal cell carcinoma (RCC) and often linked to its deregulated proliferation, survival, and angiogenesis. In the present report, we investigated whether zerumbone, a sesquiterpene, exerts its anticancer effect through modulation of STAT3 activation pathway. The pharmacological effect of zerumbone on STAT3 activation, associated protein kinases and phosphatase, and apoptosis was investigated using both RCC cell lines and xenograft mouse model. We observed that zerumbone suppressed STAT3 activation in a dose- and time-dependent manner in RCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Pervanadate treatment reversed zerumbone-induced downregulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that zerumbone induced the expression of tyrosine phosphatase SHP-1 that correlated with its ability to inhibit STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of zerumbone to inhibit STAT3 activation. The inhibition of STAT3 activation by zerumbone also caused the suppression of the gene products involved in proliferation, survival, and angiogenesis. Finally, when administered i.p., zerumbone inhibited STAT3 activation in tumor tissues and the growth of human RCC xenograft tumors in athymic nu/nu mice without any side effects. Overall, our results suggest for the first time that zerumbone is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of RCC and other solid tumors.

The role of CXC-chemokine receptor CXCR2 and suppressor of cytokine signaling-3 (SOCS-3) in renal cell carcinoma

BACKGROUND

Chemokine receptor signaling pathways are implicated in the pathobiology of renal cell carcinoma (RCC). However, the clinical relevance of CXCR2 receptor, mediating the effects of all angiogenic chemokines, remains unclear. SOCS (suppressor of cytokine signaling)-3 is a negative regulator of cytokine-driven responses, contributing to interferon-α resistance commonly used to treat advanced RCC with limited information regarding its expression in RCC.

METHODS

In this study, CXCR2 and SOCS-3 were immunohistochemically investigated in 118 RCC cases in relation to interleukin (IL)-6 and (IL)-8, their downstream transducer phosphorylated (p-)STAT-3, and VEGF expression, being further correlated with microvascular characteristics, clinicopathological features and survival. In 30 cases relationships with hypoxia-inducible factors, i.e. HIF-1a, p53 and NF-κΒ (p65/RelA) were also examined. Validation of immunohistochemistry and further investigation of downstream transducers, p-JAK2 and p-c-Jun were evaluated by Western immunoblotting in 5 cases.

RESULTS

Both CXCR2 and IL-8 were expressed by the neoplastic cells their levels being interrelated. CXCR2 strongly correlated with the levels of HIF-1a, p53 and p65/RelA in the neoplastic cells. Although SOCS-3 was simultaneously expressed with p-STAT-3, its levels tended to show an inverse relationship with p-JAK-2 and p-c-Jun in Western blots and were positively correlated with HIF-1a, p53 and p65/p65/RelA expression. Neither CXCR2 nor SOCS-3 correlated with the extent of microvascular network. IL-8 and CXCR2 expression was associated with high grade, advanced stage and the presence/number of metastases but only CXCR2 adversely affected survival in univariate analysis. Elevated SOCS-3 expression was associated with progression, the presence/number of metastasis and shortened survival in both univariate and multivariate analysis.

CONCLUSIONS

Our findings implicate SOCS-3 overexpression in RCC metastasis and biologic aggressiveness advocating its therapeutic targeting. IL-8/CXCR2 signaling also contributes to the metastatic phenotype of RCC cells but appears of lesser prognostic utility. Both CXCR2 and SOCS-3 appear to be related to transcription factors induced under hypoxia.

Anti-apoptotic effects of suppressor of cytokine signaling 3 and 1 in psoriasis

Because of their genetically determined capacity to respond to pro-inflammatory stimuli, keratinocytes have a crucial role in the pathogenesis of psoriasis. Upon IFN-γ and TNF-α exposure, psoriatic keratinocytes express exaggerated levels of inflammatory mediators, and show aberrant hyperproliferation and terminal differentiation. The thickening of psoriasic skin also results from a peculiar resistance of keratinocytes to cytokine-induced apoptosis. In this study, we investigated on the molecular mechanisms concurring to the resistance of psoriatic keratinocytes to cell death, focusing on the role having suppressor of cytokine signaling (SOCS)1 and SOCS3, two molecules abundantly expressed in IFN-γ/TNF-α-activated psoriatic keratinocytes, in sustaining anti-apoptotic pathways. We found that SOCS1 and SOCS3 suppress cytokine-induced apoptosis by sustaining the activation of the PI3K/AKT pathway in keratinocytes. The latter determines the activation of the anti-apoptotic NF-κB cascade and, in parallel, the inhibition of the pro-apoptotic BAD function in keratinocytes. For the first time, we report that phosphorylated AKT and phosphorylated BAD are strongly expressed in lesional psoriatic skin, compared with healthy or not lesional skin, and they strictly correlate to the high expression of SOCS1 and SOCS3 molecules in the psoriatic epidermis. Finally, the depletion of SOCS1 and SOCS3, as well as the chemical inactivation of PI3K activity in psoriatic keratinocytes, definitively unveils the role of PI3K/AKT cascade on the resistance of diseased keratinocytes to apoptosis.

Phosphorylation of signal transducer and activator of transcription 3 in soft tissue leiomyosarcoma is associated with a better prognosis

Signal transducer and activator of transcription (STAT) 3 mediates a broad range of biological processes, including cell survival and proliferation, and STAT3 has generally been regarded as a pro-oncogenic transcription factor. We investigated the phosphorylation status of STAT3 and the protein expression of the suppressor of cytokine signaling 3 (SOCS3) by immunohistochemistry in 145 formalin-fixed, paraffin-embedded samples of soft tissue leiomyosarcoma (LMS), including 129 primary tumors. Eight benign soft tissue smooth muscle tumors were also examined. Thirteen frozen LMS samples, which were paired with normal tissue samples, were assessed by Western blot analysis for the phosphorylation of STAT3 and SOCS3 expression. Immunohistochemical study showed that the phosphorylation of STAT3 was not a major event in LMS (37%). Moreover, phosphorylated STAT3 (pSTAT3) expression was significantly correlated with a better prognosis. Overexpression of SOCS3 was recognized in 52% of the cases and negatively correlated with pSTAT3 expression. Among the benign tumors, 63 and 25% were positive for pSTAT3 and SOCS3, respectively. Immunoblotting detected pSTAT3 in all tumor samples, but at lower levels than in non-neoplastic tissue. SOCS3 was detected in 92% (12 out of 13) of tumor tissues, but in none of the normal tissues. Contrary to the previous investigations of many other malignant tumors, STAT3 was inactivated in most LMS cases, likely owing to SOCS3 overexpression. STAT3 might not contribute to the progression of soft tissue LMS, and the phosphorylation status of STAT3 has the potential to be a favorable prognostic marker of LMS.

Vitamin D deficiency induces cardiac hypertrophy and inflammation in epicardial adipose tissue in hypercholesterolemic swine

INTRODUCTION

Vitamin D is a sectosteroid that functions through Vitamin D receptor (VDR), a transcription factor, which controls the transcription of many targets genes. Vitamin D deficiency has been linked with cardiovascular diseases, including heart failure and coronary artery disease. Suppressor of cytokine signaling (SOCS)3 regulates different biological processes such as inflammation and cellular differentiation and is an endogenous negative regulator of cardiac hypertrophy.

OBJECTIVE

The purpose of this study was to test the hypothesis that vitamin D deficiency causes cardiomyocyte hypertrophy and increased proinflammatory profile in epicardial adipose tissue (EAT), and this correlates with decreased expression of SOCS3 in cardiomyocytes and EAT.

METHODS

Eight female Yucatan miniswine were fed vitamin D-sufficient (900 IU/d) or vitamin D-deficient hypercholesterolemic diet. Lipid profile, metabolic panel, and serum 25(OH)D levels were regularly measured. After 12 months animals were euthanized and histological, immunohistochemical and qPCR studies were performed on myocardium and epicardial fat.

RESULTS

Histological studies showed cardiac hypertrophy, as judged by cardiac myocyte cross sectional area, in the vitamin D-deficient group. Immunohistochemical and qPCR analyses showed significantly decreased mRNA and protein expression of VDR and SOCS3 in cardiomyocytes of vitamin D-deficient animals. EAT from vitamin D-deficient group had significantly higher expression of TNF-α, IL-6, MCP-1, and decreased adiponectin in association with increased inflammatory cellular infiltrate. Interestingly, EAT from vitamin D-deficient group had significantly decreased expression of SOCS3.

CONCLUSION

These data suggest that vitamin D deficiency induces hypertrophy in cardiomyocytes which is associated with decreased expression of VDR and SOCS3. Vitamin D deficiency is also associated with increased inflammatory markers in EAT. Activity of VDR in the body is controlled through regulation of vitamin D metabolites. Therefore, restoration of VDR function by supplementation of VDR ligands in vitamin D-deficient population might be helpful in reducing inflammation and cardiovascular risk.

Role of SOCS1 in tumor progression and therapeutic application

SOCS1, a prototype molecule of the SOCS family, was initially defined as a suppressor of cytokine signaling. The molecular mechanisms of SOCS1-mediated functions have been subsequently identified by studies using gene knockout mice and gene silencing technology. As part of a negative feedback regulation, SOCS1 downregulates cytokine signaling through direct inhibition of the JAK tyrosine kinase and the signaling cascade of activated cytokine receptors, thereby attenuating cytokine-initiated signal transduction. Moreover, other studies have demonstrated that SOCS1 also downregulates TLR signaling through direct and indirect mechanisms. Both cytokine receptor and TLR signaling pathways mediate important functions in survival, maturation and differentiation of various types of cells and in the regulation of immune function. Abnormal expression of SOCS1 in tumor cells has been detected in various human cancers, where it is associated with dysregulation of cytokine receptor and TLR signaling to promote cell transformation. Recent studies on the function of SOCS1 in tumor cells have revealed its novel role in carcinogenesis. In this review, we will focus on the mechanism of action of SOCS1 in both tumor cells and antigen-presenting cells in the tumor microenvironment. The potential of using SOCS1 as a diagnostic marker and therapeutic target in tumor diagnosis, prognosis and treatment is discussed.

Suppressors of cytokine signaling inhibit tubular epithelial cell-myofibroblast transdifferentiation

BACKGROUND/AIMS

Tubular epithelial cell-myofibroblast transdifferentiation (TEMT) can be induced by diverse cytokines. The suppressors of cytokine signaling (SOCS) proteins negatively regulate cytokine signaling. This study is aimed at examining the role of SOCS-1 and SOCS-3 in TEMT induced by cytokines.

METHODS

The cell ultrastructure was observed using transmission electron microscopy. The protein and mRNA levels of cytokeratin 18 (CK18) and α-smooth muscle actin (α-SMA) were detected by immunocytochemistry, Western blot and real-time PCR. The levels of phosphorylated-signal transducer and activator of transcription (p-STAT) 1 and 3 were detected by Western blot. The protein and mRNA levels of SOCS-1 and SOCS-3 were detected by Western blot and real-time PCR. The levels of collagen type I and fibronectin (FN) were determined by ELISA.

RESULTS

Interleukin-1β (IL-1β) and oncostatin M (OSM) were able to downregulate CK18 expression and upregulate α-SMA, p-STAT1, p-STAT3, collagen type I and FN expression in cultured human renal proximal tubular epithelial cells (HKCs), whereas pretreatment with AG490 prevented these expression changes from occurring. All of the changes induced by IL-1β or OSM could be decreased by SOCS-1 and SOCS-3 overexpression, and were increased by SOCS-1 and SOCS-3 knockdown.

CONCLUSIONS

SOCS-1 and SOCS-3 can prevent tubulointerstitial fibrosis by inhibiting TEMT, which may be connected with the activation of STAT1 and STAT3.

Signal transducers and activators of transcription-from cytokine signalling to cancer biology

Signal transducers and activators of transcription (STATs) are, as the name indicates, both signal transducers and transcription factors. STATs are activated by cytokines and some growth factors and thus control important biological processes. These include cell growth, cell differentiation, apoptosis and immune responses. Dysregulation of STATs, either due to constitutive activation or function impairment, can have, therefore, deleterious biological consequences. This review places particular emphasis on their structural organization, biological activities and regulatory mechanisms most commonly utilized by cells to control STAT-mediated signalling. STATs also play important roles in cancer and immune deficiencies and are thus being exploited as therapeutic targets.