Tumour-promoting role of SOCS1 in colorectal cancer cells

Unveiling the pathological functions of SOCS in colorectal cancer: Current concepts and future perspectives

Colorectal cancer (CRC) remains a significant global health challenge, marked by increasing incidence and mortality rates in recent years. The pathogenesis of CRC is complex, involving chronic inflammation of the intestinal mucosa, heightened immunoinflammatory responses, and resistance to apoptosis. The suppressor of cytokine signaling (SOCS) family, comprised of key negative regulators within cytokine signaling pathways, plays a crucial role in cell proliferation, growth, and metabolic regulation. Deficiencies in various SOCS proteins can trigger the activation of the Janus kinase (JAK) and signal transducers and activators of transcription (STAT) pathways, following the binding of cytokines and growth factors to their receptors. Mounting evidence indicates that SOCS proteins are integral to the development and progression of CRC, positioning them as promising targets for novel anticancer therapies. This review delves into the structure, function, and molecular mechanisms of SOCS family members, examining their roles in cell proliferation, apoptosis, migration, epithelial-mesenchymal transition (EMT), and immune modulation. Additionally, it explores their potential impact on the regulation of CRC immunotherapy, offering new insights and perspectives that may inform the development of innovative therapeutic strategies for CRC.

Tumor-derived miR-6794-5p enhances cancer growth by promoting M2 macrophage polarization

BACKGROUND

Solid tumors promote tumor malignancy through interaction with the tumor microenvironment, resulting in difficulties in tumor treatment. Therefore, it is necessary to understand the communication between cells in the tumor and the surrounding microenvironment. Our previous study revealed the cancer malignancy mechanism of Bcl-w overexpressed in solid tumors, but no study was conducted on its relationship with immune cells in the tumor microenvironment. In this study, we sought to discover key factors in exosomes secreted from tumors overexpressing Bcl-w and analyze the interaction with the surrounding tumor microenvironment to identify the causes of tumor malignancy.

METHODS

To analyze factors affecting the tumor microenvironment, a miRNA array was performed using exosomes derived from cancer cells overexpressing Bcl-w. The discovered miRNA, miR-6794-5p, was overexpressed and the tumorigenicity mechanism was confirmed using qRT-PCR, Western blot, invasion, wound healing, and sphere formation ability analysis. In addition, luciferase activity and Ago2-RNA immunoprecipitation assays were used to study the mechanism between miR-6794-5p and its target gene SOCS1. To confirm the interaction between macrophages and tumor-derived miR-6794-5p, co-culture was performed using conditioned media. Additionally, immunohistochemical (IHC) staining and flow cytometry were performed to analyze macrophages in the tumor tissues of experimental animals.

RESULTS

MiR-6794-5p, which is highly expressed in exosomes secreted from Bcl-w-overexpressing cells, was selected, and it was shown that the overexpression of miR-6794-5p increased migratory ability, invasiveness, and stemness maintenance by suppressing the expression of the tumor suppressor SOCS1. Additionally, tumor-derived miR-6794-5p was delivered to THP-1-derived macrophages and induced M2 polarization by activating the JAK1/STAT3 pathway. Moreover, IL-10 secreted from M2 macrophages increased tumorigenicity by creating an immunosuppressive environment. The in vitro results were reconfirmed by confirming an increase in M2 macrophages and a decrease in M1 macrophages and CD8+ T cells when overexpressing miR-6794-5p in an animal model.

CONCLUSIONS

In this study, we identified changes in the tumor microenvironment caused by miR-6794-5p. Our study indicates that tumor-derived miR-6794-5p promotes tumor aggressiveness by inducing an immunosuppressive environment through interaction with macrophage.

SOCS1 acts as a ferroptosis driver to inhibit the progression and chemotherapy resistance of triple-negative breast cancer

OBJECTIVES

Ferroptosis is involved in many types of cancers, including triple-negative breast cancer (TNBC). Suppressor of cytokine signaling 1 (SOCS1) has recently been implicated as a regulator of ferroptosis. We aim to explore whether targeting SOCS1 is a potential therapeutic strategy for TNBC therapy.

METHODS

Stable cell lines were constructed using lentivirus transfection. Cell viability was determined using CCK-8 and cell colony formation assays, respectively. Assays including lactate dehydrogenase release, lipid peroxidation and malondialdehyde assays were conducted to evaluate ferroptosis. Real-time quantitative polymerase chain reaction and western blotting were performed to evaluate mRNA and protein expression, respectively. A xenograft animal model was established by subcutaneous injection of cells into the flank.

RESULTS

Our results showed that SOCS1 overexpression inhibited cell proliferation and induced ferroptosis in TNBC cells, while SOCS1 knockdown promoted cell proliferation and reduced ferroptosis. We also found that SOCS1 regulated ferroptosis by modulating GPX4 expression. Furthermore, SOCS1 regulated cisplatin resistance in TNBC cells by promoting ferroptosis. Our in vivo data suggested that SOCS1 regulated tumor growth and cisplatin resistance in vivo.

CONCLUSIONS

SOCS1 inhibits the progression and chemotherapy resistance of TNBC by regulating GPX4 expression.

Interleukin-15 cytokine checkpoints in natural killer cell anti-tumor immunity

Over recent years, the use of immune checkpoint inhibitors (ICI) has progressed to first and second-line treatments in several cancer types, transforming patient outcomes. While these treatments target T cell checkpoints, such as PD-1, LAG3 and CTLA-4, their efficacy can be compromised through adaptive resistance whereby tumors acquire mutations in genes regulating neoantigen presentation by MHC-I [93]. ICI-responsive tumor types such as advanced metastatic melanoma typically have a high mutational burden and immune infiltration; however, most patients still do not benefit from ICI monotherapy for a number of reasons [94]. This highlights the need for novel immunotherapy strategies that evoke the immune control of tumor cells with low neoantigen/MHC-I expression, overcome immune suppressive tumor microenvironments and promote tumor inflammation. In this regard, targeting natural killer (NK) cells may offer a solution to some of these bottlenecks.

Gold nanoparticles attenuate the interferon-γ induced SOCS1 expression and activation of NF-κB p65/50 activity via modulation of microRNA-155-5p in triple-negative breast cancer cells

Objective

Triple-negative breast cancer (TNBC) is a very aggressive form of cancer that grows and spreads very fast and generally relapses. Therapeutic options of TNBC are limited and still need to be explored completely. Gold nanoparticles conjugated with citrate (citrate-AuNPs) are reported to have anticancer potential; however, their role in regulating microRNAs (miRNAs) in TNBC has never been investigated. This study investigated the potential of citrate-AuNPs against tumorigenic inflammation via modulation of miRNAs in TNBC cells.

Methods

Gold nanoparticles were chemically synthesized using the trisodium-citrate method and were characterized by UV-Vis spectrophotometry and dynamic light scattering studies. Targetscan bioinformatics was used to analyze miRNA target genes. Levels of miRNA and mRNA were quantified using TaqMan assays. The pairing of miRNA in 3'untranslated region (3'UTR) of mRNA was validated by luciferase reporter clone, containing the entire 3'UTR of mRNA, and findings were further re-validated via transfection with miRNA inhibitors.

Results

Newly synthesized citrate-AuNPs were highly stable, with a mean size was 28.3 nm. The data determined that hsa-miR155-5p is a direct regulator of SOCS1 (suppressor-of-cytokine-signaling) expression and citrate-AuNPs inhibits SOCS1 mRNA/protein expression via modulating hsa-miR155-5p expression. Transfection of TNBC MDA-MB-231 cells with anti-miR155-5p markedly increased SOCS1 expression (p<0.001), while citrate-AuNPs treatment significantly inhibited anti-miR155-5p transfection-induced SOCS1 expression (p<0.05). These findings were validated by IFN-γ-stimulated MDA-MB-231 cells. Moreover, the data also determined that citrate-AuNPs also inhibit IFN-γ-induced NF-κB p65/p50 activation in MDA-MB-231 cells transfected with anti-hsa-miR155-5p.

Conclusion

Newly generated citrate-AuNPs were stable and non-toxic to TNBC cells. Citrate-AuNPs inhibit IFN-γ-induced SOCS1 mRNA/protein expression and deactivate NF-κB p65/50 activity via negative regulation of hsa-miR155-5p. These novel pharmacological actions of citrate-AuNPs on IFN-γ-stimulated TNBC cells provide insights that AuNPs inhibit IFN-γ induced inflammation in TNBC cells by modulating the expression of microRNAs.

Inactivation of interleukin-30 in colon cancer stem cells via CRISPR/Cas9 genome editing inhibits their oncogenicity and improves host survival

BACKGROUND

Progression of colorectal cancer (CRC), a leading cause of cancer-related death worldwide, is driven by colorectal cancer stem cells (CR-CSCs), which are regulated by endogenous and microenvironmental signals. Interleukin (IL)-30 has proven to be crucial for CSC viability and tumor progression. Whether it is involved in CRC tumorigenesis and impacts clinical behavior is unknown.

METHODS

IL30 production and functions, in stem and non-stem CRC cells, were determined by western blot, immunoelectron microscopy, flow cytometry, cell viability and sphere formation assays. CRISPR/Cas9-mediated deletion of the IL30 gene, RNA-Seq and implantation of IL30 gene transfected or deleted CR-CSCs in NSG mice allowed to investigate IL30's role in CRC oncogenesis. Bioinformatics and immunopathology of CRC samples highlighted the clinical implications.

RESULTS

We demonstrated that both CR-CSCs and CRC cells express membrane-anchored IL30 that regulates their self-renewal, via WNT5A and RAB33A, and/or proliferation and migration, primarily by upregulating CXCR4 via STAT3, which are suppressed by IL30 gene deletion, along with WNT and RAS pathways. Deletion of IL30 gene downregulates the expression of proteases, such as MMP2 and MMP13, chemokine receptors, mostly CCR7, CCR3 and CXCR4, and growth and inflammatory mediators, including ANGPT2, CXCL10, EPO, IGF1 and EGF. These factors contribute to IL30-driven CR-CSC and CRC cell expansion, which is abrogated by their selective blockade. IL30 gene deleted CR-CSCs displayed reduced tumorigenicity and gave rise to slow-growing and low metastatic tumors in 80% of mice, which survived much longer than controls. Bioinformatics and CIBERSORTx of the 'Colorectal Adenocarcinoma TCGA Nature 2012' collection, and morphometric assessment of IL30 expression in clinical CRC samples revealed that the lack of IL30 in CRC and infiltrating leucocytes correlates with prolonged overall survival.

CONCLUSIONS

IL30 is a new CRC driver, since its inactivation, which disables oncogenic pathways and multiple autocrine loops, inhibits CR-CSC tumorigenicity and metastatic ability. The development of CRISPR/Cas9-mediated targeting of IL30 could improve the current therapeutic landscape of CRC.

Identification pyroptosis-related gene signature to predict prognosis and associated regulation axis in colon cancer

Background: Pyroptosis is an important component of the tumor microenvironment and associated with the occurrence and progression of cancer. As the expression of pyroptosis-related genes and its impact on the prognosis of colon cancer (CC) remains unclear, we constructed and validated a pyroptosis-related genes signature to predict the prognosis of patients with CC.

Methods: Microarray datasets and the follow-up clinical information of CC patients were obtained from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) databases. Candidate genes were screened out for further analysis. Various methods were combined to construct a robust pyroptosis-related genes signature for predicting the prognosis of patients with CC. Based on the gene signature and clinical features, a decision tree and nomogram were developed to improve risk stratification and quantify risk assessment for individual patients.

Results: The pyroptosis-related genes signature successfully discriminated CC patients with high-risk in the training cohorts. The prognostic value of this signature was further confirmed in independent validation cohort. Multivariable Cox regression and stratified survival analysis revealed this signature was an independent prognostic factor for CC patients. The decision tree identified risk subgroups powerfully, and the nomogram incorporating the gene signature and clinical risk factors performed well in the calibration plots.

Conclusion: Pyroptosis-related genes signature was an independent prognostic factor, and can be used to predict the prognosis of patients with CC.

SOCS1 counteracts ROS-mediated survival signals and promotes apoptosis by modulating cell cycle to increase radiosensitivity of colorectal cancer cells

As negative regulators of cytokine signaling pathways, suppressors of cytokine signaling (SOCS) proteins have been reported to possess both pro-tumor and anti-tumor functions. Our recent studies have demonstrated suppressive effects of SOCS1 on epithelial to mesenchymal signaling in colorectal cancer cells in response to fractionated ionizing radiation or oxidative stress. The objective of the present study was to determine the radiosensitizing action of SOCS1 as an anti-tumor mechanism in color-ectal cancer cell model. In HCT116 cells exposed to ionizing radiation, SOCS1 over-expression shifted cell cycle arrest from G2/M to G1 and promoted radiation-induced apoptosis in a p53-dependent manner with down-regulation of cyclin B and up-regulation of p21. On the other hand, SOCS1 knock-down resulted in a reduced apoptosis with a decrease in G1 arrest. The regulatory action of SOCS1 on the radiation response was mediated by inhibition of radiation-induced Jak3/STAT3 and Erk activities, thereby blocking G1 to S transition. Radiation-induced early ROS signal was responsible for the activation of Jak3/Erk/STAT3 that led to cell survival response. Our data col-lectively indicate that SOCS1 can promote radiosensitivity of colorectal cancer cells by counteracting ROS-mediated survival signal, thereby blocking cell cycle progression from G1 to S. The resulting increase in G1 arrest with p53 activation then contributes to the promotion of apoptotic response upon radiation. Thus, induction of SOCS1 expression may increase therapeutic efficacy of radiation in tumors with low SOCS1 levels.

Semantic clustering analysis of E3-ubiquitin ligases in gastrointestinal tract defines genes ontology clusters with tissue expression patterns

Background

Ubiquitin ligases (Ub-ligases) are essential intracellular enzymes responsible for the regulation of proteome homeostasis, signaling pathway crosstalk, cell differentiation and stress responses. Individual Ub-ligases exhibit their unique functions based on the nature of their substrates. They create a complex regulatory network with alternative and feedback pathways to maintain cell homeostasis, being thus important players in many physiological and pathological conditions. However, the functional classification of Ub-ligases needs to be revised and extended.

Methods

In the current study, we used a novel semantic biclustering technique for expression profiling of Ub-ligases and ubiquitination-related genes in the murine gastrointestinal tract (GIT). We accommodated a general framework of the algorithm for finding tissue-specific gene expression clusters in GIT. In order to test identified clusters in a biological system, we used a model of epithelial regeneration. For this purpose, a dextran sulfate sodium (DSS) mouse model, following with in situ hybridization, was used to expose genes with possible compensatory features. To determine cell-type specific distribution of Ub-ligases and ubiquitination-related genes, principal component analysis (PCA) and Uniform Manifold Approximation and Projection technique (UMAP) were used to analyze the Tabula Muris scRNA-seq data of murine colon followed by comparison with our clustering results.

Results

Our established clustering protocol, that incorporates the semantic biclustering algorithm, demonstrated the potential to reveal interesting expression patterns. In this manner, we statistically defined gene clusters consisting of the same genes involved in distinct regulatory pathways vs distinct genes playing roles in functionally similar signaling pathways. This allowed us to uncover the potentially redundant features of GIT-specific Ub-ligases and ubiquitination-related genes. Testing the statistically obtained results on the mouse model showed that genes clustered to the same ontology group simultaneously alter their expression pattern after induced epithelial damage, illustrating their complementary role during tissue regeneration.

Conclusions

An optimized semantic clustering protocol demonstrates the potential to reveal a readable and unique pattern in the expression profiling of GIT-specific Ub-ligases, exposing ontologically relevant gene clusters with potentially redundant features. This extends our knowledge of ontological relationships among Ub-ligases and ubiquitination-related genes, providing an alternative and more functional gene classification. In a similar way, semantic cluster analysis could be used for studding of other enzyme families, tissues and systems.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02265-2.

SOCS1 counteracts ROS-mediated survival signals and promotes apoptosis by modulating cell cycle to increase radiosensitivity of colorectal cancer cells

As negative regulators of cytokine signaling pathways, suppressors of cytokine signaling (SOCS) proteins have been reported to possess both pro-tumor and anti-tumor functions. Our recent studies have demonstrated suppressive effects of SOCS1 on epithelial to mesenchymal signaling in colorectal cancer cells in response to fractionated ionizing radiation or oxidative stress. The objective of the present study was to determine the radiosensitizing action of SOCS1 as an anti-tumor mechanism in colorectal cancer cell model. In HCT116 cells exposed to ionizing radiation, SOCS1 over-expression shifted cell cycle arrest from G2/M to G1 and promoted radiation-induced apoptosis in a p53-dependent manner with down-regulation of cyclin B and up-regulation of p21. On the other hand, SOCS1 knock-down resulted in a reduced apoptosis with a decrease in G1 arrest. The regulatory action of SOCS1 on the radiation response was mediated by inhibition of radiation-induced Jak3/STAT3 and Erk activities, thereby blocking G1 to S transition. Radiation-induced early ROS signal was responsible for the activation of Jak3/Erk/STAT3 that led to cell survival response. Our data collectively indicate that SOCS1 can promote radiosensitivity of colorectal cancer cells by counteracting ROS-mediated survival signal, thereby blocking cell cycle progression from G1 to S. The resulting increase in G1 arrest with p53 activation then contributes to the promotion of apoptotic response upon radiation. Thus, induction of SOCS1 expression may increase therapeutic efficacy of radiation in tumors with low SOCS1 levels. [BMB Reports 2022; 55(4): 198-203].

Clinical and molecular assessment of an onco-immune signature with prognostic significance in patients with colorectal cancer

Understanding the complex tumor microenvironment is key to the development of personalized therapies for the treatment of cancer including colorectal cancer (CRC). In the past decade, significant advances in the field of immunotherapy have changed the paradigm of cancer treatment. Despite significant improvements, tumor heterogeneity and lack of appropriate classification tools for CRC have prevented accurate risk stratification and identification of a wider patient population that may potentially benefit from targeted therapies. To identify novel signatures for accurate prognostication of CRC, we quantified gene expression of 12 immune‐related genes using a medium‐throughput NanoString quantification platform in 93 CRC patients. Multivariate prognostic analysis identified a combined four‐gene prognostic signature (TGFB1, PTK2, RORC, and SOCS1) (HR: 1.76, 95% CI: 1.05–2.95, *p < 0.02). The survival trend was captured in an independent gene expression data set: GSE17536 (177 patients; HR: 3.31, 95% CI: 1.99–5.55, *p < 0.01) and GSE14333 (226 patients; HR: 2.47, 95% CI: 1.35–4.53, *p < 0.01). Further, gene set enrichment analysis of the TCGA data set associated higher prognostic scores with epithelial–mesenchymal transition (EMT) and inflammatory pathways. Comparatively, a lower prognostic score was correlated with oxidative phosphorylation and MYC and E2F targets. Analysis of immune parameters identified infiltration of T‐reg cells, CD8⁺ T cells, M2 macrophages, and B cells in high‐risk patient groups along with upregulation of immune exhaustion genes. This molecular study has identified a novel prognostic gene signature with clinical utility in CRC. Therefore, along with prognostic features, characterization of immune cell infiltrates and immunosuppression provides actionable information that should be considered while employing personalized medicine.

Opposing Roles of Type I Interferons in Cancer Immunity

The immune system is tasked with identifying malignant cells to eliminate or prevent cancer spread. This involves a complex orchestration of many immune cell types that together recognize different aspects of tumor transformation and growth. In response, tumors have developed mechanisms to circumvent immune attack. Type I interferons (IFN-Is) are a class of proinflammatory cytokines produced in response to viruses and other environmental stressors. IFN-Is are also emerging as essential drivers of antitumor immunity, potently stimulating the ability of immune cells to eliminate tumor cells. However, a more complicated role for IFN-Is has arisen, as prolonged stimulation can promote feedback inhibitory mechanisms that contribute to immune exhaustion and other deleterious effects that directly or indirectly permit cancer cells to escape immune clearance. We review the fundamental and opposing functions of IFN-Is that modulate tumor growth and impact immune function and ultimately how these functions can be harnessed for the design of new cancer therapies.

Exosomal circular RNA_400068 promotes the development of renal cell carcinoma via the miR‑210‑5p/SOCS1 axis

Renal cell carcinoma (RCC) is a common type of malignancy in the kidney, which accounts for ~80% of the cases within adult patients. The pathogenesis of RCC is complicated and involves alterations at both genetic and epigenetic levels. The aim of the present study was to investigate the roles of circRNAs in the pathogenesis of RCC. In the current study, exosomes were isolated via gradient centrifugation and identified using transmission electron microscope. The expression levels of circular RNA (circ)_400068, microRNA (miR)‑210‑5p and suppressor of cytokine signaling 1 (SOCS1) were examined using reverse transcription‑quantitative PCR. Cell proliferation was evaluated using a Cell Counting Kit‑8 assay, and the apoptotic rate was determined in transfected cells using flow cytometry. The protein expression levels of proliferation‑ and apoptosis‑associated genes were assessed via western blot analysis. Upregulation of circ_400068 was detected in RCC plasma exosomes, tissue samples and cells. Additionally, treatment with exosomal circ_400068 promoted the proliferation and inhibited the apoptosis of healthy kidney cells, which were abrogated by short hairpin RNA‑circ_400068. The results suggested that miR‑210‑5p was a potential downstream molecule of circ_400068, and SOCS1 was a novel target of miR‑210‑5p. Moreover, circ_400068 regulated the proliferation of HK‑2 cells by targeting the miR‑210‑5p/SOCS1 axis, as the effects on cell proliferation caused by treatment using exosomes isolated from the culture media of RCC cells were abolished by miR‑210‑5p mimics. It was found that enhanced cell proliferation induced by miR‑210‑5p inhibitors was attenuated by the knockdown of SOCS1, while the influences triggered by miR‑210‑5p mimics were reversed by SOCS1 overexpression. Collectively, the present findings provided a novel insight into the crucial regulatory functions of circ_400068 in RCC, and the circ_400068/miR‑210‑5p/SOCS1 axis could be a candidate therapeutic target for the treatment of patients with RCC.

SOCS Proteins Participate in the Regulation of Innate Immune Response Caused by Viruses

The host immune system has multiple innate immune receptors that can identify, distinguish and react to viral infections. In innate immune response, the host recognizes pathogen-associated molecular patterns (PAMP) in nucleic acids or viral proteins through pathogen recognition receptors (PRRs), especially toll-like receptors (TLRs) and induces immune cells or infected cells to produce type I Interferons (IFN-I) and pro-inflammatory cytokines, thus when the virus invades the host, innate immunity is the earliest immune mechanism. Besides, cytokine-mediated cell communication is necessary for the proper regulation of immune responses. Therefore, the appropriate activation of innate immunity is necessary for the normal life activities of cells. The suppressor of the cytokine signaling proteins (SOCS) family is one of the main regulators of the innate immune response induced by microbial pathogens. They mainly participate in the negative feedback regulation of cytokine signal transduction through Janus kinase signal transducer and transcriptional activator (JAK/STAT) and other signal pathways. Taken together, this paper reviews the SOCS proteins structures and the function of each domain, as well as the latest knowledge of the role of SOCS proteins in innate immune caused by viral infections and the mechanisms by which SOCS proteins assist viruses to escape host innate immunity. Finally, we discuss potential values of these proteins in future targeted therapies.

Interpreting pathways to discover cancer driver genes with Moonlight

Cancer driver gene alterations influence cancer development, occurring in oncogenes, tumor suppressors, and dual role genes. Discovering dual role cancer genes is difficult because of their elusive context-dependent behavior. We define oncogenic mediators as genes controlling biological processes. With them, we classify cancer driver genes, unveiling their roles in cancer mechanisms. To this end, we present Moonlight, a tool that incorporates multiple -omics data to identify critical cancer driver genes. With Moonlight, we analyze 8000+ tumor samples from 18 cancer types, discovering 3310 oncogenic mediators, 151 having dual roles. By incorporating additional data (amplification, mutation, DNA methylation, chromatin accessibility), we reveal 1000+ cancer driver genes, corroborating known molecular mechanisms. Additionally, we confirm critical cancer driver genes by analysing cell-line datasets. We discover inactivation of tumor suppressors in intron regions and that tissue type and subtype indicate dual role status. These findings help explain tumor heterogeneity and could guide therapeutic decisions.

Control of Tyrosine Kinase Signalling by Small Adaptors in Colorectal Cancer

Tyrosine kinases (TKs) phosphorylate proteins on tyrosine residues as an intracellular signalling mechanism to coordinate intestinal epithelial cell communication and fate decision. Deregulation of their activity is ultimately connected with carcinogenesis. In colorectal cancer (CRC), it is still unclear how aberrant TK activities contribute to tumour formation because TK-encoding genes are not frequently mutated in this cancer. In vertebrates, several TKs are under the control of small adaptor proteins with potential important physiopathological roles. For instance, they can exert tumour suppressor functions in human cancer by targeting several components of the oncogenic TK signalling cascades. Here, we review how the Src-like adaptor protein (SLAP) and the suppressor of cytokine signalling (SOCS) adaptor proteins regulate the SRC and the Janus kinase (JAK) oncogenic pathways, respectively, and how their loss of function in the intestinal epithelium may influence tumour formation. We also discuss the potential therapeutic value of these adaptors in CRC.

MiR-29a inhibits invasion and metastasis of cervical cancer via modulating methylation of tumor suppressor SOCS1

Aims: To investigate roles of miR-29a-DNMT1-SOCS1 axis in cervical cancer invasion and migration. Materials & methods: The methylation level of SOCS1 was determined by methylation specific PCR. The cell apoptosis, proliferation, migration and invasion were examined by Annexin-V/PI staining, MTT and colony formation assays, plus scratch and transwell assays respectively. The expressions of epithelial-mesenchymal transition and NF-κB related proteins were determined by western blotting. Results: MiR-29a was downregulated, accompanied with DNMT1 upregulation and SOCS1 downregulation in cervical cancer tissues. MiR-29a suppressed DNMT1, inhibited SOCS1 promoter methylation and upregulated its expression. Moreover, miR-29a promoted cell apoptosis, suppressed proliferation, inhibited migration and invasion via inactivation of NF-κB signaling pathway in cervical cancer cells. Conclusion: MiR-29a-DNMT1-SOCS1 axis plays an important role on invasion and metastasis in cervical cancer via NF-κB signaling pathway.

Therapeutic Implication of SOCS1 Modulation in the Treatment of Autoimmunity and Cancer

The suppressor of cytokine signaling (SOCS) family of intracellular proteins has a vital role in the regulation of the immune system and resolution of inflammatory cascades. SOCS1, also called STAT-induced STAT inhibitor (SSI) or JAK-binding protein (JAB), is a member of the SOCS family with actions ranging from immune modulation to cell cycle regulation. Knockout of SOCS1 leads to perinatal lethality in mice and increased vulnerability to cancer, while several SNPs associated with the SOCS1 gene have been implicated in human inflammation-mediated diseases. In this review, we describe the mechanism of action of SOCS1 and its potential therapeutic role in the prevention and treatment of autoimmunity and cancer. We also provide a brief outline of the other JAK inhibitors, both FDA-approved and under investigation.

Deficiency in STAT1 Signaling Predisposes Gut Inflammation and Prompts Colorectal Cancer Development

Signal transducer and activator of transcription 1 (STAT1) is part of the Janus kinase (JAK/STAT) signaling pathway that controls critical events in intestinal immune function related to innate and adaptive immunity. Recent studies have implicated STAT1 in tumor⁻stroma interactions, and its expression and activity are perturbed during colon cancer. However, the role of STAT1 during the initiation of inflammation-associated cancer is not clearly understood. To determine the role of STAT1 in colitis-associated colorectal cancer (CAC), we analyzed the tumor development and kinetics of cell recruitment in wild-type WT or STAT1^-/- mice treated with azoxymethane (AOM) and dextran sodium sulfate (DSS). Following CAC induction, STAT1^-/- mice displayed an accelerated appearance of inflammation and tumor formation, and increased damage and scores on the disease activity index (DAI) as early as 20 days after AOM-DSS exposure compared to their WT counterparts. STAT1^-/- mice showed elevated colonic epithelial cell proliferation in early stages of injury-induced tumor formation and decreased apoptosis in advanced tumors with over-expression of the anti-apoptotic protein Bcl2 at the colon. STAT1^-/- mice showed increased accumulation of Ly6G⁺Ly6C^-CD11b⁺ cells in the spleen at 20 days of CAC development with concomitant increases in the production of IL-17A, IL-17F, and IL-22 cytokines compared to WT mice. Our findings suggest that STAT1 plays a role as a tumor suppressor molecule in inflammation-associated carcinogenesis, particularly during the very early stages of CAC initiation, modulating immune responses as well as controlling mechanisms such as apoptosis and cell proliferation.

Structural insights into suppressor of cytokine signaling 1 protein- identification of new leads for type 2 diabetes mellitus

The study considers the Suppressor of cytokine signaling 1 (SOCS1) protein as a novel Type 2 diabetes mellitus (T2DM) drug target. T2DM in human beings is also triggered by the over expression of SOCS proteins. The SOCS1 acts as a ubiquitin ligase (E3), degrades Insulin Receptor Substrate 1 and 2 (IRS1 and IRS2) proteins, and causes insulin resistance. Therefore, the structure of the SOCS1 protein was evaluated using homology-modeling and molecular dynamics methods and validated using standard computational protocols. The Protein-Protein docking study of SOCS1 with its natural substrates, IRS1 and IRS2, and subsequent solvent accessible surface area analysis gave insight into the binding region of the SOCS1 protein. The in silico active site prediction tools highlight the residues Val155 to Ile211 in SOCS1 being implicated in the ubiquitin mediated protein degradation of the proteins IRS1 and IRS2. Virtual screening in the active site region, using large structural databases, results in selective lead structures with 3-Pyridinol, Xanthine, and Alanine moieties as Pharmacophore. The virtual screening study shows that the residues Glu149, Gly187, Arg188, Leu191, and Ser205 of the SOCS1 are important for binding. The docking study with current anti-diabetic therapeutics shows that the drugs Glibenclamide and Glyclopyramide have a partial affinity towards SOCS1. The predicted ADMET and IC₅₀ properties for the identified ligands are within the acceptable range with drug-like properties. The structural data of SOCS1, its active site, and the identified lead structures are expedient in the development of new T2DM therapeutics.

SOCS1 is associated with clinical progression and acts as an oncogenic role in triple-negative breast cancer

Suppressors of cytokine signaling 1 (SOCS1) is a member of SOCS family and acts as negative regulators of cytokine signaling by direct inhibition of receptor-associated janus kinases. The clinical significance and biological function of SOCS1 in variant tumor tissues and at variant tumor stages is still controversial. The aim of our study is to confirm the expression status of SOCS1 in triple-negative breast cancer (TNBC) tissues and cell lines, and explore the clinical value and biological function of SOCS1 in TNBC. In microarray data sets (GDS2250 and GDS817), we observed SOCS1 was overexpressed in TNBC tissues and cell line compared with normal mammary tissues and mammary epithelial cell line, or non-TNBC tissues and cell line. Furthermore, SOCS1 mRNA and protein overexpression were confirmed in TNBC tissues and cell lines compared with normal mammary tissues and mammary epithelial cell lines or non-TNBC tissues and cell lines. SOCS1 protein overexpression was obviously associated with advanced clinical stage, large tumor size, more lymph node metastasis, present distant metastasis, and malign histological grade. Downregulation of SOCS1 expression suppressed TNBC cells proliferation and promoted cell apoptosis. In conclusion, SOCS1 is associated with clinical progression in TNBC patients and acts as an oncogenic role in regulating TNBC cells proliferation and apoptosis. © 2018 IUBMB Life, 70(4):320-327, 2018.

SOCS Proteins as Regulators of Inflammatory Responses Induced by Bacterial Infections: A Review

Severe bacterial infections can lead to both acute and chronic inflammatory conditions. Innate immunity is the first defense mechanism employed against invading bacterial pathogens through the recognition of conserved molecular patterns on bacteria by pattern recognition receptors (PRRs), especially the toll-like receptors (TLRs). TLRs recognize distinct pathogen-associated molecular patterns (PAMPs) that play a critical role in innate immune responses by inducing the expression of several inflammatory genes. Thus, activation of immune cells is regulated by cytokines that use the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway and microbial recognition by TLRs. This system is tightly controlled by various endogenous molecules to allow for an appropriately regulated and safe host immune response to infections. Suppressor of cytokine signaling (SOCS) family of proteins is one of the central regulators of microbial pathogen-induced signaling of cytokines, principally through the inhibition of the activation of JAK/STAT signaling cascades. This review provides recent knowledge regarding the role of SOCS proteins during bacterial infections, with an emphasis on the mechanisms involved in their induction and regulation of antibacterial immune responses. Furthermore, the implication of SOCS proteins in diverse processes of bacteria to escape host defenses and in the outcome of bacterial infections are discussed, as well as the possibilities offered by these proteins for future targeted antimicrobial therapies.

NOD1 modulates IL-10 signalling in human dendritic cells

NOD1 belongs to the family of NOD-like receptors, which is a group of well-characterised, cytosolic pattern-recognition receptors. The best-studied function of NOD-like receptors is their role in generating immediate pro-inflammatory and antimicrobial responses by detecting specific bacterial peptidoglycans or by responding to cellular stress and danger-associated molecules. The present study describes a regulatory, peptidoglycan-independent function of NOD1 in anti-inflammatory immune responses. We report that, in human dendritic cells, NOD1 balances IL-10-induced STAT1 and STAT3 activation by a SOCS2-dependent mechanism, thereby suppressing the tolerogenic dendritic cell phenotype. Based on these findings, we propose that NOD1 contributes to inflammation not only by promoting pro-inflammatory processes, but also by suppressing anti-inflammatory pathways.

Mechanism of suppressors of cytokine signaling 1 inhibition of epithelial-mesenchymal transition signaling through ROS regulation in colon cancer cells: suppression of Src leading to thioredoxin up-regulation

Reactive oxygen species (ROS) participate in malignant progression of cancers including epithelial-mesenchymal transition (EMT). We have investigated the role of suppressors of cytokine signaling (SOCS)1 as an inhibitor of ROS-induced EMT using colon cancer cell lines transduced with SOCS1 and shSOCS1. Hydrogen peroxide treatment induced EMT features such as elevation of vimentin and Snail with a corresponding reduction of E-cadherin. The EMT markers are significantly decreased upon SOCS1 over-expression while increased under SOCS1 knock-down. SOCS1 inhibited ROS signaling pathways associated with EMT such as Src, Jak, and p65. Of note, strong up-regulation of Src activity in SOCS1-ablated cells was responsible for the elevated signaling leading to EMT, as shSrc or Src inhibitor abolished the shSOCS1-induced promotion of EMT response. Suppression of ROS-inducible EMT markers and invasion in SOCS1 over-expressing cells correlated with significantly low intracellular ROS levels in these cells. Analysis of antioxidant enzymes in SOCS1-transduced cells revealed a selective up-regulation of thioredoxin (Trx1), while thioredoxin ablation restored ROS levels and the associated EMT markers. As a mechanism of thioredoxin up-regulation by SOCS1, inhibition of Src activity promoting nuclear translocation of Nrf-2 is proposed. Taken together, our data strongly indicate that SOCS1 antagonizes EMT by suppressing Src activity, leading to thioredoxin expression and down-regulation of ROS levels in colon cancer cells.

Integrating Immunologic Signaling Networks: The JAK/STAT Pathway in Colitis and Colitis-Associated Cancer

Cytokines are believed to be crucial mediators of chronic intestinal inflammation in inflammatory bowel diseases (IBD) such as Crohn's disease (CD) and ulcerative colitis (UC). Many of these cytokines trigger cellular effects and functions through signaling via janus kinase (JAK) and signal transducer and activator of transcription (STAT) molecules. In this way, JAK/STAT signaling controls important events like cell differentiation, secretion of cytokines or proliferation and apoptosis in IBD in both adaptive and innate immune cells. Moreover, JAK/STAT signaling, especially via the IL-6/STAT3 axis, is believed to be involved in the transition of inflammatory lesions to tumors leading to colitis-associated cancer (CAC). In this review, we will introduce the main cellular players and cytokines that contribute to pathogenesis of IBD by JAK/STAT signaling, and will highlight the integrative function that JAK/STATs exert in this context as well as their divergent role in different cells and processes. Moreover, we will explain current concepts of the implication of JAK/STAT signaling in CAC and finally discuss present and future therapies for IBD that interfere with JAK/STAT signaling.