Overexpression of TRIM26 suppresses the proliferation,metastasis, and glycolysis in papillary thyroid carcinoma cells

Papillary thyroid carcinoma (PTC) is the common subtype of thyroid cancer, which is a common endocrine malignancy. Tripartite motif 26 (TRIM26) has been found to act as a tumor suppressor in several cancers. However, the functional roles of TRIM26 in PTC remain unknown. In this study, we examined the TRIM26 expression in PTC and evaluated the effects of TRIM26 on proliferation, metastasis, and glycolysis in PTC cells. The results proved that TRIM26 was significantly downregulated in PTC tissues and cell lines. TRIM26 overexpression inhibited cell proliferation, migration, and invasion in PTC cells. TRIM26 overexpression also suppressed the epithelial-to-mesenchymal transition process. Besides, overexpression of TRIM26 caused significant decrease in glucose uptake and lactate production in PTC cells. Further investigations revealed that TRIM26 overexpression inhibited the activation of PI3K/Akt pathway. Treatment with an activator (740Y-P) of the PI3K/AKT pathway reversed the antitumor effects of TRIM26 on PTC cells. These findings provided evidence that TRIM26 acted as a tumor suppressor in PTC.     

Ciliary Neurotrophic Factor Protects Mice Against Streptozotocin-induced Type 1 Diabetes through SOCS3: THE ROLE OF STAT1/STAT3 RATIO IN β-CELL DEATH*

Type 1 diabetes is characterized by a loss of islet β-cells. Ciliary neurotrophic factor (CNTF) protects pancreatic islets against cytokine-induced apoptosis. For this reason, we assessed whether CNTF protects mice against streptozotocin-induced diabetes (a model of type 1 diabetes) and the mechanism for this protection. WT and SOCS3 knockdown C57BL6 mice were treated for 5 days with citrate buffer or 0.1 mg/kg CNTF before receiving 80 mg/kg streptozotocin. Glycemia in non-fasted mice was measured weekly from days 0–28 after streptozotocin administration. Diabetes was defined as a blood glucose > 11.2 mmol/liter. Wild-type (WT) and SOCS3 knockdown MIN6 cells were cultured with CNTF, IL1β, or both. CNTF reduced diabetes incidence and islet apoptosis in WT but not in SOCS3kd mice. Likewise, CNTF inhibited apoptosis in WT but not in SOCS3kd MIN6 cells. CNTF increased STAT3 phosphorylation in WT and SOCS3kd mice and MIN6 cells but reduced STAT1 phosphorylation only in WT mice, in contrast to streptozotocin and IL1β. Moreover, CNTF reduced NFκB activation and required down-regulation of inducible NO synthase expression to exert its protective effects. In conclusion, CNTF protects mice against streptozotocin-induced diabetes by increasing pancreatic islet survival, and this protection depends on SOCS3. In addition, SOCS3 expression and β-cell fate are dependent on STAT1/STAT3 ratio.     

Cell proliferation and STAT6 pathways are negatively regulated in T cells by STAT1 and suppressors of cytokine signaling

Suppressor of cytokine signaling (SOCS) proteins have emerged as important regulators of cytokine signals in lymphocytes. In this study, we have investigated regulation of SOCS expression and their role in Th cell growth and differentiation. We show that SOCS genes are constitutively expressed in naive Th cells, albeit at low levels, and are differentially induced by Ag and Th-polarizing cytokines. Whereas cytokines up-regulate expression of SOCS1, SOCS2, SOCS3, and cytokine-induced Src homology 2 protein, Ags induce down-regulation of SOCS3 within 48 h of Th cell activation and concomitantly up-regulate SOCS1, SOCS2, and cytokine-induced Src homology 2 protein expression. We further show that STAT1 signals play major roles in inducing SOCS expression in Th cells and that induction of SOCS expression by IL-4, IL-12, or IFN-gamma is compromised in STAT1-deficient primary Th cells. Surprisingly, IL-4 is a potent inducer of STAT1 activation in Th2 but not Th1 cells, and SOCS1 or SOCS3 expression is dramatically reduced in STAT1(-/-) Th2 cells. To our knowledge, this is the first report of IL-4-induced STAT1 activation in Th cells, and suggests that its induction of SOCS, may in part, regulate IL-4 functions in Th2 cells. In fact, overexpression of SOCS1 in Th2 cells represses STAT6 activation and profoundly inhibits IL-4-induced proliferation, while depletion of SOCS1 by an anti-sense SOCS1 cDNA construct enhances cell proliferation and induces constitutive activation of STAT6 in Th2 cells. These results are consistent with a model where IL-4 has dual effects on differentiating T cells: it simulates proliferation/differentiation through STAT6 and autoregulates its effects on Th2 growth and effector functions via STAT1-dependent up-regulation of SOCS proteins.     

Long non-coding RNA SNHG1 suppresses cell migration and invasion and upregulates SOCS2 in human gastric carcinoma

Gastric carcinoma (GC) is one of the most common malignancies and the third leading cause of cancer-related deaths worldwide. Long noncoding RNAs (lncRNAs) may be an important class of functional regulators involved in human gastric cancers development. In this study, we investigated the clinical significance and function of lncRNA SNHG1 in GC. SNHG1 was significantly downregulated in GC tumor tissues compared with adjacent noncancerous tissues. Overexpression of SNHG1 in BGC-823 cells remarkably inhibited not only cell proliferation, migration, invasion in vitro, but also tumorigenesis and lung metastasis in the chick embryo chorioallantoic membrane (CAM) assay in vivo. Conversely, inhibition of SNHG1 by transfection of siRNA in AGS cells resulted in opposite phenotype changes. Mechanically, SNHG1 was found interacted with ILF3, NONO and SFPQ. RNA-seq combined with bioinformatic analysis identified a serial of downstream genes of SNHG1, including SOCS2, LOXL2, LTBP3, LTBP4. Overexpression of SNHG1 induced SOCS2 expression whereas knockdown of SNHG1 decreased SOCS2 expression. In addition, knockdown of SNHG1 promoted the activation of JAK2/STAT signaling pathway. Taken together, our data suggested that SNHG1 suppressed aggressive phenotype of GC cells and regulated SOCS2/JAK2/STAT pathway.     

MiR-34a targets GAS1 to promote cell proliferation and inhibit apoptosis in papillary thyroid carcinoma via PI3K/Akt/Bad pathway

MicroRNAs (miRNAs) are fundamental regulators of cell proliferation, differentiation, and apoptosis, and are implicated in tumorigenesis of many cancers. MiR-34a is best known as a tumor suppressor through repression of growth factors and oncogenes. Growth arrest specific1 (GAS1) protein is a tumor suppressor that inhibits cancer cell proliferation and induces apoptosis through inhibition of RET receptor tyrosine kinase. Both miR-34a and GAS1 are frequently down-regulated in various tumors. However, it has been reported that while GAS1 is down-regulated in papillary thyroid carcinoma (PTC), miR-34a is up-regulated in this specific type of cancer, although their potential roles in PTC tumorigenesis have not been examined to date. A computational search revealed that miR-34a putatively binds to the 3′-UTR of GAS1 gene. In the present study, we confirmed previous findings that miR-34a is up-regulated and GAS1 down-regulated in PTC tissues. Further studies indicated that GAS1 is directly targeted by miR-34a. Overexpression of miR-34a promoted PTC cell proliferation and colony formation and inhibited apoptosis, whereas knockdown of miR-34a showed the opposite effects. Silencing of GAS1 had similar growth-promoting effects as overexpression of miR-34a. Furthermore, miR-34a overexpression led to activation of PI3K/Akt/Bad signaling pathway in PTC cells, and depletion of Akt reversed the pro-growth, anti-apoptotic effects of miR-34a. Taken together, our results demonstrate that miR-34a regulates GAS1 expression to promote proliferation and suppress apoptosis in PTC cells via PI3K/Akt/Bad pathway. MiR-34a functions as an oncogene in PTC.     

AZD1480 Blocks Growth and Tumorigenesis of RET- Activated Thyroid Cancer Cell Lines

Persistent RET activation is a frequent event in papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC). In these cancers, RET activates the ERK/MAPK, the PI3K/AKT/mTOR and the JAK/STAT3 pathways. Here, we tested the efficacy of a JAK1/2- inhibitor, AZD1480, in the in vitro and in vivo growth of thyroid cancer cell lines expressing oncogenic RET. Thyroid cancer cell lines harboring RET/PTC1 (TPC-1), RET M918T (MZ-CRC1) and RET C634W (TT) alterations, as well as TPC-1 xenografts, were treated with JAK inhibitor, AZD1480. This inhibitor led to growth inhibition and/or apoptosis of the thyroid cancer cell lines in vitro, as well as to tumor regression of TPC-1 xenografts, where it efficiently blocked STAT3 activation in tumor and stromal cells. This inhibition was associated with decreased proliferation, decreased blood vessel density, coupled with increased necrosis. However, AZD1480 repressed the growth of STAT3- deficient TPC-1 cells in vitro and in vivo, demonstrating that its effects in this cell line were independent of STAT3 in the tumor cells. In all cell lines, the JAK inhibitor reduced phospho-Y1062 RET levels, and mTOR effector phospho-S6, while JAK1/2 downregulation by siRNA did not affect cell growth nor RET and S6 activation. In conclusion, AZD1480 effectively blocks proliferation and tumor growth of activated RET- thyroid cancer cell lines, likely through direct RET inhibition in cancer cells as well as by modulation of the microenvironment (e.g. via JAK/phospho-STAT3 inhibition in endothelial cells). Thus, AZD1480 should be considered as a therapeutic agent for the treatment of RET- activated thyroid cancers.     

TRIM25-mediated ubiquitination of G3BP1 regulates the proliferation and migration of human neuroblastoma cells

Neuroblastoma is one of the most severe malignant tumors and accounts for substantial cancer-related mortality in children. Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is highly expressed in various cancers and acts as an important biomarker of poor prognosis. The ablation of G3BP1 inhibited the proliferation and migration of human SHSY5Y cells. Because of its important role in neuroblastoma, the regulation of G3BP1 protein homeostasis was probed. TRIM25, which belongs to the tripartite motif (TRIM) family of proteins, was identified as an interacting partner for G3BP1 using the yeast two-hybrid (Y2H) method. TRIM25 mediates the ubiquitination of G3BP1 at multiple sites and stabilizes its protein level. Then, our study found that TRIM25 knockdown also inhibited the proliferation and migration of neuroblastoma cells. The TRIM25 and G3BP1 double knockdown SHSY5Y cell line was generated, and double knockdown cells exhibited lower proliferation and migration ability than cells with only TRIM25 or G3BP1 knockdown. Further study demonstrated that TRIM25 promotes the proliferation and migration of neuroblastoma cells in a G3BP1-dependent manner. Tumor xenograft assays indicated that the ablation of TRIM25 and G3BP1 synergistically suppressed the tumorigenicity of neuroblastoma cells in nude mice, and TRIM25 promoted the tumorigenicity of G3BP1 intact SHSY5Y cells but not G3BP1 knockout cells. Thus, TRIM25 and G3BP1, two oncogenic genes, are suggested as potential therapeutic targets for neuroblastoma.     

Retracted: MicroRNA-520a-3p suppresses epithelial–mesenchymal transition,invasion, and migration of papillary thyroid carcinoma cells via the JAK1-mediated JAK/STAT signaling pathway

Papillary thyroid cancer (PTC) is a kind of thyroid cancer and frequently presents with epithelial–mesenchymal transition (EMT). MicroRNAs (miRNAs) were previously reported to be associated with PTC. Thus, this study aims to define the role of microRNA-520a-3p (miR-520a-3p) in PTC through the JAK/STAT signaling pathway by targeting JAK1. The PTC and normal thyroid tissues of 137 PTC patients were collected. First of all, the expression pattern of miR-520a-3p, JAK1, JAK2, STAT3, E-cadherin, and vimentin in PTC was identified. The relationship between miR-520a-3p and JAK1 was predicted and analyzed. And a series of miR-520a-3p mimic or inhibitor, or siRNA JAK1 introduced into PTC cells were applied to examine the effect of miR-520a-3p on PTC cell viability, migration, invasion, cell cycle, apoptosis, and EMT. Meanwhile, the regulatory effect of miR-520a-3p and JAK1 on the JAK/STAT signaling pathway was also determined. The expression of JAK1, JAK2, STAT3, and vimentin increased yet miR-520a-3p and E-cadherin decreased in PTC tissue. JAK1 was negatively regulated by miR-520a-3p. Functionally, EMT induction was prevented by miR-520a-3p upregulation through downregulating JAK1. When upregulating miR-520a-3p or silencing JAK1 in PTC cells, PTC cell viability, migration, and invasion were inhibited yet cell apoptosis promoted with cells arrested at G1 phase, indicating that miR-520a-3p prevented PTC progression by downregulating JAK1. Moreover, miR-520a-3p elevation or JAK1 inhibition inactivated the JAK/STAT signaling pathway. Collectively, miR-520a-3p prevents cancer progression through inactivating the JAK/STAT signaling pathway by downregulating JAK1 in PTC.     

Suppressor of cytokine signaling 1 regulates an endogenous inhibitor of a mast cell protease

Suppressor of cytokine signaling 1 (SOCS1) is a negative regulator of c-Kit and interleukin-3 (IL-3) receptor signaling. We examined the role of SOCS1 in regulating IL-3-induced cell growth of primary bone marrow-derived mast cells (BMMCs) from SOCS1-/- mice. Instead of showing increased proliferation, SOCS1-deficient BMMCs responded poorly to IL-3 and stem cell factor. SOCS1-/- BMMCs showed increased apoptosis and defective cell cycle entry. We show that the growth retardation of SOCS1-/- BMMCs was due to a cell intrinsic defect. Protein tyrosine phosphorylation following IL-3 stimulation was markedly diminished in SOCS1-/- BMMCs. Intriguingly, JAK2 and STAT5 proteins were selectively diminished in SOCS1-/- BMMCs, which also showed lower molecular mass products of p85 and Vav suggesting proteolytic degradation. Incubation of the SOCS1-/- BMMC lysate with STAT5, p85, and Vav immunoprecipitated from SOCS1+/+ cells directly demonstrated the dysregulated proteolytic activity in SOCS1-/- BMMCs. The proteolytic activity in SOCS1-/- BMMCs was selectively inhibited by phenylmethylsulfonyl fluoride and soybean trypsin inhibitor, suggesting that the protease regulated by SOCS1 is a tryptase. The dysregulated tryptase in SOCS1-/- BMMCs is unlikely to be mMCP6 or mMCP7, because the enzyme activity was not inhibited by Polybrene but was inhibited by normal mouse plasma. SOCS1+/+ BMMC lysate inhibited the proteolytic activity present in SOCS1-/- BMMC lysate, indicating that SOCS1-/- BMMCs lack an endogenous protease inhibitor. These results show that SOCS1 is required for the expression and/or stability of an endogenous protease inhibitor, which protects mast cells from their own proteolytic enzymes.     

Suppressors of cytokine signaling regulate Fc receptor signaling and cell activation during immune renal injury

Suppressors of cytokine signaling (SOCS) are cytokine-inducible proteins that modulate receptor signaling via tyrosine kinase pathways. We investigate the role of SOCS in renal disease, analyzing whether SOCS regulate IgG receptor (FcgammaR) signal pathways. In experimental models of immune complex (IC) glomerulonephritis, the renal expression of SOCS family genes, mainly SOCS-3, significantly increased, in parallel with proteinuria and renal lesions, and the proteins were localized in glomeruli and tubulointerstitium. Induction of nephritis in mice with a deficiency in the FcgammaR gamma-chain (gamma(-/-) mice) resulted in a decrease in the renal expression of SOCS-3 and SOCS-1. Moreover, blockade of FcgammaR by Fc fragment administration in rats with ongoing nephritis selectively inhibited SOCS-3 and SOCS-1, without affecting cytokine-inducible Src homology 2-containing protein and SOCS-2. In cultured human mesangial cells (MC) and monocytes, IC caused a rapid and transient induction of SOCS-3 expression. Similar kinetics was observed for SOCS-1, whereas SOCS-2 expression was very low. MC from gamma(-/-) mice failed to respond to IC activation, confirming the participation of FcgammaR. Interestingly, IC induced tyrosine phosphorylation of SOCS-3 and Tec tyrosine kinase, and both proteins coprecipitated in lysates from IC-stimulated MC, suggesting intracellular association. IC also activated STAT pathway in MC, which was suppressed by SOCS overexpression, mainly SOCS-3. In SOCS-3 knockdown studies, specific antisense oligonucleotides inhibited mesangial SOCS-3 expression, leading to an increase in the IC-induced STAT activation. Our results indicate that SOCS may play a regulatory role in FcgammaR signaling, and implicate SOCS as important modulators of cell activation during renal inflammation.