Structure and Functional Characterization of the Conserved JAK Interaction Region in the Intrinsically Disordered N-Terminus of SOCS5

LincRNAs and snoRNAs in Breast Cancer Cell Metastasis: The Unknown Players

Recent advances in research have led to earlier diagnosis and targeted therapies against breast cancer, which has resulted in reduced breast cancer-related mortality. However, the majority of breast cancer-related deaths are due to metastasis of cancer cells to other organs, a process that has not been fully elucidated. Among the factors and genes implicated in the metastatic process regulation, non-coding RNAs have emerged as crucial players. This review focuses on the role of long intergenic noncoding RNAs (lincRNAs) and small nucleolar RNAs (snoRNAs) in breast cancer cell metastasis. LincRNAs are transcribed between two protein-coding genes and are longer than 200 nucleotides, they do not code for a specific protein but function as regulatory molecules in processes such as cell proliferation, apoptosis, epithelial-to-mesenchymal transition, migration, and invasion while most of them are highly elevated in breast cancer tissues and seem to function as competing endogenous RNAs (ceRNAs) inhibiting relevant miRNAs that specifically target vital metastasis-related genes. Similarly, snoRNAs are 60-300 nucleotides long and are found in the nucleolus being responsible for the post-transcriptional modification of ribosomal and spliceosomal RNAs. Most snoRNAs are hosted inside intron sequences of protein-coding and non-protein-coding genes, and they also regulate metastasis-related genes affecting related cellular properties.

Long Noncoding RNA and Circular RNA: Two Rising Stars in Regulating Epithelial-Mesenchymal Transition of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with especially poor prognosis. However, the molecular mechanisms of pancreatic oncogenesis and malignant progression are not fully elucidated. Epithelial-mesenchymal transition (EMT) process is important to drive pancreatic carcinogenesis. Recently, long noncoding RNAs (lncRNAs) and circular RNAs(circRNAs) have been characterized to participate in EMT in PDAC, which can affect the migration and invasion of tumor cells by playing important roles in epigenetic processes, transcription, and post-transcriptional regulation. LncRNAs can act as competing endogenous RNAs (ceRNA) to sequester target microRNAs(miRNAs), bind to the genes which localize physically nearby, and directly interact with EMT-related proteins. Currently known circRNAs mostly regulate the EMT process in PDAC also by acting as a miRNA sponge, directly affecting the protein degradation process. Therefore, exploring the functions of lncRNAs and circRNAs in EMT during pancreatic cancer might help pancreatic cancer treatments.

STAT3-EMT axis in tumors: modulation of cancer metastasis, stemness and therapy response

Epithelial-to-mesenchymal transition (EMT) mechanism is responsible for metastasis of tumor cells and their spread to various organs and tissues of body, providing undesirable prognosis. In addition to migration, EMT increases stemness and mediates therapy resistance. Hence, pathways involved in EMT regulation should be highlighted. STAT3 is an oncogenic pathway that can elevate growth rate and migratory ability of cancer cells and induce drug resistance. The inhibition of STAT3 signaling impairs cancer progression and promotes chemotherapy-mediated cell death. Present review focuses on STAT3 and EMT interaction in modulating cancer migration. First of all, STAT3 is an upstream mediator of EMT and is able to induce EMT-mediated metastasis in brain tumors, thoracic cancers and gastrointestinal cancers. Therefore, STAT3 inhibition significantly suppresses cancer metastasis and improves prognosis of patients. EMT regulators such as ZEB1/2 proteins, TGF-β, Twist, Snail and Slug are affected by STAT3 signaling to stimulate cancer migration and invasion. Different molecular pathways such as miRNAs, lncRNAs and circRNAs modulate STAT3/EMT axis. Furthermore, we discuss how STAT3 and EMT interaction affects therapy response of cancer cells. Finally, we demonstrate targeting STAT3/EMT axis by anti-tumor agents and clinical application of this axis for improving patient prognosis.

The LINC01119-SOCS5 axis as a critical theranostic in triple-negative breast cancer

The development of triple-negative breast cancer (TNBC) is critically regulated by certain tumor-microenvironment-associated cells called mesenchymal stem/stromal cells (MSCs), which we and others have shown promote TNBC progression by activating pro-malignant signaling in neighboring cancer cells. Characterization of these cascades would better our understanding of TNBC biology and bring about therapeutics that eliminate the morbidity and mortality associated with advanced disease. Here, we focused on the emerging class of RNAs called long non-coding RNAs or lncRNAs and utilized a MSC-supported TNBC progression model to identify specific family members of functional relevance to TNBC pathogenesis. Indeed, although some have been described to play functional roles in TNBC, activities of lncRNAs as mediators of tumor-microenvironment-driven TNBC development remain to be fully explored. We report that MSCs stimulate robust expression of LINC01119 in TNBC cells, which in turn induces suppressor of cytokine signaling 5 (SOCS5), leading to accelerated cancer cell growth and tumorigenesis. We show that LINC01119 and SOCS5 exhibit tight correlation across multiple breast cancer gene sets and that they are highly enriched in TNBC patient cohorts. Importantly, we present evidence that the LINC01119-SOCS5 axis represents a powerful prognostic indicator of adverse outcomes in TNBC patients, and demonstrate that its repression severely impairs cancer cell growth. Altogether, our findings identify LINC01119 as a major driver of TNBC development and delineate critical non-coding RNA theranostics of potential translational utility in the management of advanced TNBC, a class of tumors in most need of effective and targeted therapy.

lncRNA HAND2-AS1 Inhibits Liver Cancer Cell Proliferation and Migration by Upregulating SOCS5 to Inactivate the JAK-STAT Pathway

Objective: lncRNA HAND2 antisense RNA 1 (HAND2-AS1) is consistently well recognized to suppress multiple tumors, while its function was uncertified in liver cancer. Materials and Methods: qRT-PCR analysis and TCGA database discovered the expression in liver cancer. CCK-8 and Transwell migration assay demonstrated the impact of HAND2-AS1 on cell proliferation and migration. Bioinformatic analysis and luciferase reporter assay were utilized to monitor the binding between HAND2-AS1 or SOCS5 mRNA and miR-3118. The function of SOCS5 on inactivating the JAK-STAT pathway was confirmed through Western blot assays. Rescue experiments unmasked that HAND2-AS1-mediated SOCS5 affected cell proliferation and migration through the JAK-STAT pathway in liver cancer. Results: The authors discovered the downregulated HAND2-AS1 in liver cancer cells. HAND2-AS1 augmentation apparently impaired the capacity of liver cancer viability, proliferation, and migration. Cytoplasmic HAND2-AS1 directly bound to miR-3118 and released SOCS5, leading to upregulation of SOCS5. Next, the negative regulator role of SOCS5 in the adjusting JAK-STAT pathway was reconfirmed in this study. Conclusions: HAND2-AS1 enhanced inactivation of the JAK-STAT pathway through sponging miR-3118 and facilitating SOCS5 to retard cell proliferation and migration in liver cancer.

LncRNA H19-Derived miR-675-3p Promotes Epithelial-Mesenchymal Transition and Stemness in Human Pancreatic Cancer Cells by targeting the STAT3 Pathway

Objective: The functional role and mechanism of the long noncoding RNA (lncRNA) H19 in regulating human pancreatic cancer (PC) cell stemness and invasion have not been completely elucidated. This study aimed to evaluate the role of H19 in regulating the stemness, epithelial-mesenchymal transition (EMT), invasion and chemosensitivity of PC cells. Methods: The sphere-forming ability was assessed using serum-free floating-culture systems. Chemosensitivity was evaluated via CCK-8 and flow cytometry assays in vitro. Migration and invasion were evaluated by transwell assays. The expression of stemness and EMT markers was detected by flow cytometry, qRT-PCR and western blot analyses. Xenograft initiation, growth and sensitivity were examined; Ki-67 nuclear staining intensity was evaluated by immunohistochemistry; and in situ apoptosis was evaluated by a TUNEL assay. Results: H19 played an important role in maintaining PC cell stemness. Upregulated H19 expression in CAPAN-1 cells promoted tumor cell migration, invasion, EMT and chemoresistance. In contrast, downregulated H19 expression in PANC-1 cells yielded the opposite results. These effects were mediated by positively modulating the STAT3 pathway. Furthermore, SOCS5, an endogenous inhibitor of the STAT3 pathway, was a direct target of miR-675-3p, which was positively regulated by H19 in PC cells. Conclusions: The H19/miR-675-3p signaling axis plays a critical role in maintaining the EMT process and stemness of PC cells by directly targeting SOCS5 to activate the STAT3 pathway. These data provide new insights into the oncogenic function of H19 in human PC and reveal potential targets for the development of optimal treatment approaches for this disease.

MiR-151a-3p Promotes Postmenopausal Osteoporosis by Targeting SOCS5 and Activating JAK2/STAT3 Signaling

Postmenopausal osteoporosis, the most common type of primary osteoporosis, poses a significant threat to women's health worldwide. However, detailed molecular mechanism and therapeutic strategy for postmenopausal osteoporosis remain insufficient. Increasing evidence suggests that microRNAs contributed to the pathogenesis of osteoporosis and could be considered as potential therapeutic targets. In this study, we found that miR-151a-3p was upregulated in osteoporosis samples. Experiments in MC3T3-E1 cells indicated that miR-151a-3p significantly inhibited cell viability and promoted lactate dehydrogenase release, as well as increased RANKL/OPG ratio and decreased Runx2 and BMP2 expressions. SOCS5 was identified as a direct target gene of miR-151a-3p, which was confirmed by luciferase reporter assay. Moreover, an inverse correlation between miR-151a-3p and SOCS5 was observed in osteoporosis femurs. In addition, JAK2/STAT3 pathway was found to be involved in the progress of osteoporosis mediated by miR-151a-3p-SOCS5 axis. In vivo, ovariectomized (OVX) rat model was established to simulate postmenopausal osteoporosis. The results revealed that miR-151a-3p significantly decreased the bone mineral density and biomechanical parameters of femurs in OVX rats by targeting SOCS5, and that JAK2/STAT3 pathway is a downstream target of miR-151a-3p-SOCS5 axis in OVX rats. In conclusion, our findings suggested that miR-151a-3p contributed to the pathogenesis of postmenopausal osteoporosis, and promoted its progress by targeting SOCS5 and activating JAK2/STAT3 signaling. Thus, anti-miR-151a-3p could be a potential therapeutic strategy for postmenopausal osteoporosis.

Molecular Cloning and Expression Analysis of Three Suppressors of Cytokine Signaling Genes (SOCS5, SOCS6, SOCS7) in the Mealworm Beetle Tenebrio molitor

Suppressors of cytokine signaling (SOCS) influence cytokine and growth factor signaling by negatively regulating the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway to maintain homeostasis during immune responses. However, functional characterization of SOCS family members in invertebrates is limited. Here, we identified and evaluated three SOCS genes (type I sub-family) in the mealworm beetle Tenebrio molitor. The full-length open reading frames (ORFs) of TmSOCS5, TmSOCS6, and TmSOCS7 comprised of 1389, 897, and 1458 nucleotides, encoding polypeptides of 462, 297, and 485 amino acids, respectively. The SH2 and SOCS box domains of the TmSOCS C-terminal region were highly conserved. Phylogenetic analysis revealed that these SOCS genes were clustered within the type I subfamily that exhibits the highest amino acid identity with Tribolium castaneum SOCS genes. Contrary to TmSOCS7 expression, the expression levels of TmSOCS5 and TmSOCS6 were lower in the larval, pupal, and adult stages. In larvae and adults, the expression levels of TmSOCS5 and TmSOCS6 were highest in the hemocytes and ovaries, respectively. SOCS transcripts were also highly upregulated in the hemocytes of T. molitor larvae within 3–6 h post-infection with the fungus Candida albicans. Collectively, these results provide valuable information regarding the involvement of TmSOCS type-I subfamily in the host immune response of insects.

Understanding SOCS protein specificity

The development and activity of our immune system are largely controlled by the action of pleiotropic cytokines and growth factors, small secreted proteins, which bind to receptors on the surface of immune cells to initiate an appropriate physiological response. Cytokine signalling is predominantly executed by intracellular proteins known as the Janus kinases (JAKs) and the signal transducers and activators of transcriptions (STATs). Although the 'nuts and bolts' of cytokine-activated pathways have been well established, the nuanced way in which distinct cellular outcomes are achieved and the precise molecular details of the proteins that regulate these pathways are still being elucidated. This is highlighted by the intricate role of the suppressor of cytokine signalling (SOCS) proteins. The SOCS proteins act as negative feedback inhibitors, dampening specific cytokine signals to prevent excessive cellular responses and returning the cell to a homeostatic state. A great deal of study has demonstrated their ability to inhibit these pathways at the receptor complex, either through direct inhibition of JAK activity or by targeting the receptor complex for proteasomal degradation. Detailed analysis of individual SOCS proteins is slowly revealing the complex and highly controlled manner by which they can achieve specificity for distinct substrates. However, for many of the SOCS, a level of detail is still lacking, including confident identification of the full suite of tyrosine phosphorylated targets of their SH2 domain. This review will highlight the general mechanisms which govern SOCS specificity of action and discuss the similarities and differences between selected SOCS proteins, focusing on CIS, SOCS1 and SOCS3. Because of the functional and sequence similarities within the SOCS family, we will also discuss the evidence for functional redundancy.

Simple approach for ranking structure determining residues

Mutating residues has been a common task in order to study structural properties of the protein of interest. Here, we propose and validate a simple method that allows the identification of structural determinants; i.e., residues essential for preservation of the stability of global structure, regardless of the protein topology. This method evaluates all of the residues in a 3D structure of a given globular protein by ranking them according to their connectivity and movement restrictions without topology constraints. Our results matched up with sequence-based predictors that look up for intrinsically disordered segments, suggesting that protein disorder can also be described with the proposed methodology.

Japanese Encephalitis Virus exploits the microRNA-432 to regulate the expression of Suppressor of Cytokine Signaling (SOCS) 5

Japanese encephalitis virus (JEV) is a plus strand RNA virus, which infects brain. MicroRNAs are regulatory non-coding RNAs which regulate the expression of various genes in cells. Viruses modulate the expression of various microRNAs to suppress anti-viral signaling and evade the immune response. SOCS (Suppressor of cytokine signalling) family of proteins are negative regulators of anti-viral Jak-STAT pathway. In this study, we demonstrated the regulatory role of SOCS5 in Jak-STAT signaling and its exploitation by JEV through a microRNA mediated mechanism. JEV infection in human brain microglial cells (CHME3) downregulated the expression of miR-432, and upregulated SOCS5 levels. SOCS5 was validated as a target of miR-432 by using 3'UTR clone of SOCS5 in luciferase vector along with miR-432 mimic. The overexpression of miR-432 prior to JEV infection enhanced the phosphorylation of STAT1 resulting into increased ISRE activity and cellular inflammatory response resulting into diminished viral replication. The knockdown of SOCS5 resulted into increased STAT1 phosphorylation and suppressed viral replication. JEV infection mediated downregulation of miR-432 leads to SOCS5 upregulation, which helps the virus to evade cellular anti-viral response. This study demonstrated that JEV utilizes this microRNA mediated strategy to manipulate cellular immune response promoting JEV pathogenesis.