Loss of expression and function of SOCS3 is an early event in HNSCC: altered subcellular localization as a possible mechanism involved in proliferation, migration and invasion

SOCS1 and SOCS3 as key checkpoint molecules in the immune responses associated to skin inflammation and malignant transformation

SOCS are a family of negative inhibitors of the molecular cascades induced by cytokines, growth factors and hormones. At molecular level, SOCS proteins inhibit the kinase activity of specific sets of receptor-associated Janus Activated Kinases (JAKs), thereby suppressing the propagation of intracellular signals. Of the eight known members, SOCS1 and SOCS3 inhibit activity of JAKs mainly induced by cytokines and can play key roles in regulation of inflammatory and immune responses. SOCS1 and SOCS3 are the most well-characterized SOCS members in skin inflammatory diseases, where their inhibitory activity on cytokine activated JAKs and consequent anti-inflammatory action has been widely investigated in epidermal keratinocytes. Structurally, SOCS1 and SOCS3 share the presence of a N-terminal domain containing a kinase inhibitory region (KIR) motif able to act as a pseudo-substrate for JAK and to inhibit its activity. During the last decades, the design and employment of SOCS1 and SOCS3-derived peptides mimicking KIR domains in experimental models of dermatoses definitively established a strong anti-inflammatory and ameliorative impact of JAK inhibition on skin inflammatory responses. Herein, we discuss the importance of the findings collected in the past on SOCS1 and SOCS3 function in the inflammatory responses associated to skin immune-mediated diseases and malignancies, for the development of the JAK inhibitor drugs. Among them, different JAK inhibitors have been introduced in the clinical practice for treatment of atopic dermatitis and psoriasis, and others are being investigated for skin diseases like alopecia areata and vitiligo.

Theranostic Potential of EFNB2 for Cetuximab Resistance in Head and Neck Cancer

Only 13% of head and neck cancer (HNC) patients respond to cetuximab therapy despite its target (EGFR) is expressed in about 80-90% of HNC patients. However, this problem remained unresolved till date despite of numerous efforts. Thus, the current study aimed to establish hub genes involved in cetuximab resistance via series of bioinformatics approach. The GSE21483 dataset was analysed for differentially expressed genes (DEGs) using GEO2R and enrichment analysis was carried out using DAVID. STRING 11.5 and Cytoscape 3.7.2 were used for protein-protein interactions and hub genes respectively. The significant hub genes (p < 0.05) were validated using ULCAN and Human protein atlas. Validated genes were further queried for tumor infiltration using TIMER2.0. Out of total 307 DEGs, 38 hub genes were identified of which IL1A, EFNB2, SPRR1A, ROBO1 and SOCS3 were the significant hub genes associated with both mRNA expression and overall survival. IL1A, ROBO1, and SOCS3 were found to be downregulated whereas EFNB2 and SPRR1A were found to be upregulated in our study. However, using UALCAN, we found that high expression of IL1A, EFNB2, SOCS3 negatively affects overall survival whereas high expression of SPRR1A and ROBO1 positively affects overall survival. Protein level for EFNB2 and SPRR1A expression was significant in tumor HNC tissue as compared to normal HNC tissue. EFNB2 was found to be a key regulator of CTX resistance among HNC patients. Targeting EFNB2 and associated PPI circuits might improve the response rate to CTX. Thus, EFNB2 has potential to be theranostic marker for CTX resistance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03739-9.

Inhibition of anti-inflammatory pathway through suppressors of cytokine signalling (Socs2/Socs3) in the initiation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a leading cause of cancer related deaths is predominantly driven by chronic inflammatory responses. Due to asymptomatic nature and lack of early patient biopsies, precise involvement of inflammation in hepatic injury initiation remains unidentified. Aim of the study was to elucidate the regulation patterns of inflammatory signalling from initiation of hepatic injury to development of HCC. HCC mice model was established using DEN followed by repeated doses of CCl₄ and sacrificed at three different stages of disease comprising 7, 14 and 21 weeks. Serum biochemical tests, hepatic lipids quantification, histopathology and qPCR analyses were conducted to characterize the initiation and progression of liver injury and inflammatory signalling. Notably, at 7 weeks, we observed hepatocyte damage and periportal necrotic bodies coupled with induction of Socs2/Socs3 and anti-inflammatory cytokine Il-10. At 14 weeks, mice liver showed advancement of liver injury with micro-vesicular steatosis and moderate collagen deposition around portal zone. With progression of injury, the expression of Socs3 was declined with further reduction of Il-10 and Tgf-β indicating the disturbance of anti-inflammatory mechanism. In contrast, pro-inflammatory cytokines Il1-β, Il6 and Tnf-α were upregulated contributing inflammation. Subsequently, at 21 weeks severe liver damage was estimated as characterized by macro-vesicular steatosis, perisinusoidal collagen bridging, immune cell recruitment and significant upregulation of Col-1α and α-Sma. In parallel, there was significant upregulation of pro/anti-inflammatory cytokines highlighting the commencement of chronic inflammation.

Findings of the study suggest that differential regulation of cytokine suppressors and inflammatory cytokines might play role in the initiation and progression of hepatic injury leading towards HCC.

Blockade of STAT3 signaling alleviates progression of acute kidney injury-to-chronic kidney disease through anti-apoptosis

Signal transducer and activator of transcription 3 (STAT3) is a pivotal mediator of IL-6-type cytokine signaling. However, the roles of its full-length and truncated isoforms in acute kidney injury (AKI) and its transition to chronic kidney disease (CKD) remain elusive. Herein, the role of STAT3 isoforms in AKI-to-CKD transition was characterized using an ischemia-reperfusion injury (IRI) mouse model. IRI was induced in C57BL/6 mice. Stattic^®, a STAT3 inhibitor, was administered to the mice 3 h prior to IRI. Intrarenal cytokine expression was quantified using real-time PCR, and FACS analysis was performed. The effect of Stattic^® on human tubular epithelial cells (TECs) cultured under hypoxic conditions was also evaluated. Phosphorylated STAT3 isoforms were detected by western blotting. Stattic^® treatment attenuated IRI-induced tubular damage and inflammatory cytokine/chemokine expression, while decreasing macrophage infiltration and fibrosis in mouse unilateral IRI and UUO models. Similarly, in vitro STAT3 inhibition downregulated fibrosis and apoptosis in 72-h hypoxia-induced human TECs and reduced pSTAT3α-mediated inflammation. Moreover, pSTAT3 expression was increased in human acute tubular necrosis and CKD tissues. STAT3 activation is associated with IRI progression, and STAT3-α may be a significant contributor. Hence, STAT3 may affect AKI-to-CKD transition, suggesting a novel strategy for AKI management with STAT3 inhibitors.

Emerging roles of suppressor of cytokine signaling 3 in human cancers

As a member of the suppressor of cytokine signaling (SOCS) family, SOCS3 is a cytokine-inducible protein that inhibits cytokine signaling in a variety of signaling pathways. Increasing evidence shows that SOCS3 regulates tumor development through multiple pathological and physiological processes. It is worth mentioning that SOCS3 negatively regulates JAK/STAT signaling by binding to JAK/cytokine receptors or phosphorylation docking sites on STAT receptors, thus preventing tumor cell proliferation and inhibiting tumor cell invasion and metastasis. The kinase inhibitory region KIR of SOCS3 is the key to JAK inhibition. In addition, SOCS3 may also regulate tumor progression through other molecules or signaling pathways, such as microRNAs (miRNAs), IL-6 and NF-κB signaling pathway. MicroRNAs inhibit SOCS3 expression by binding to the 3' untranslated region of SOCS3 mRNA, thus regulating tumor development processes, including tumor cell proliferation, invasion, metastasis, differentiation, cell cycle and apoptosis, as well as tumor metastasis and chemotherapy resistance. On the whole, SOCS3 acts as an inhibitor of the majority of tumors through various pathways. In the present review, the role of SOCS3 in multitudinous tumors was comprehensively summarized, the molecular mechanisms and modes of action of SOCS3 in tumors were discussed, and the association between SOCS3 expression and the clinical characteristics of patients with cancer were emphasized.

The Expression Levels of IL-4/IL-13/STAT6 Signaling Pathway Genes and SOCS3 Could Help to Differentiate the Histopathological Subtypes of Non-Small Cell Lung Carcinoma

Background

The interleukin (IL)-4/IL-13/signal transducer and activator of transcription (STAT) 6 signaling pathway and the SOCS3 gene, one of its main regulators, constitute an important link between the inflammation process in the epithelial cells and inflammatory-related tumorigenesis. The present study is the first to evaluate IL-4, IL-13, STAT6, and SOCS3 mRNA expression in non-small cell lung carcinoma (NSCLC) histopathological subtypes.

Methods

Gene expression levels were assessed using TaqMan^® probes by quantitative reverse transcription PCR (qRT-PCR) in lung tumor samples and unchanged lung tissue samples.

Results

Increased expression of IL-4, IL-13, and STAT6 was observed in all histopathological NSCLC subtypes (squamous cell carcinoma [SCC], adenocarcinoma [AC], and large cell carcinoma [LCC]). Significantly higher expression of IL-13 and STAT6 (p = 0.019 and p = 0.008, respectively) was found in SCC than in LCC. No statistically significant differences were found for IL-4. Significantly higher SOCS3 expression was found in LCC than in AC (p = 0.027). A negative correlation (rho = –0.519) was observed for the STAT6 and SOCS3 genes in SCC (p = 0.005). No associations were found between gene expression and tumor staging (post-operative Tumor Node Metastasis [pTNM], American Joint Committee on Cancer [AJCC]), patients’ age, sex, or history of smoking.

Conclusions

As the number of LCC cases in our study was quite low, the statistically significant results obtained should be confirmed in a larger group of patients, particularly as the relationships identified between increased IL-4, IL-13, and STAT6 mRNA expression and decreased SOCS3 expression suggest that these genes may serve as potential diagnostic markers for differentiating between NSCLC histopathological subtypes.

Integrative transcriptome analysis identifies genes and pathways associated with enzalutamide resistance of prostate cancer

BACKGROUND

Enzalutamide, a novel androgen receptor (AR) signaling inhibitor, has been widely used to increase survival in patients with castration-resistant prostate cancer. However, resistance to enzalutamide invariably develops.

METHODS

To understand the underlying mechanisms of resistance to enzalutamide, we performed integrative analysis on multiple transcriptome datasets to identify those genes constantly up- or down-regulated in response to enzalutamide treatment.

RESULTS

There were 703 and 581 differentially expressed genes derived from enzalutamide-sensitive and -resistant cell lines, respectively. Functional enrichment analysis on these genes demonstrated that biological processes of cell proliferation and ubiquitin mediated proteolysis pathway are specifically disturbed in sensitive cell lines but not resistant ones. Such divergence explained why enzalutamide ineffective for resistant prostate cancer.

CONCLUSIONS

Taken together, the present study revealed a set of critical genes, which can provide etiologic clues as to enzalutamide-resistant prostate cancer and guide novel therapeutic approaches.

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.

SOCS3 inhibits the pathological effects of IL-22 in non-melanoma skin tumor-derived keratinocytes

Basal cell carcinomas (BCC) and squamous-cell carcinomas (SCC) are common malignancies in humans, caused by neoplastic transformation of keratinocytes of the basal or suprabasal layers of epidermis, respectively. Tumor-infiltrating lymphocytes (TILs) are frequently found in BCC and SCC, and functionally promote epithelial carcinogenesis. TILs secreting IL-22, in particular, participate to BCC and SCC growth by inducing keratinocyte proliferation and migration, as well as the expression of inflammatory, anti-apoptotic and pro-angiogenic genes.In this study, we identified SOCS3 as a valid candidate to be manipulated for suppressing tumorigenic functions in BCC and SCC. We found that SOCS3 and SOCS1 expression was reduced in vivo, in tumor lesions of BCC and SCC, as compared to other skin inflammatory conditions such as psoriasis, despite the high number of IL-22-secreting TILs. Moreover, IL-22 was not able to induce in vitro the transcriptional expression of SOCS3 in BCC-or SCC-derived keratinocytes, contrarily to healthy cells. Aimed at rescuing SOCS3 activity in these tumor contexts, a SOCS3-derived peptide, named KIR-ESS, was synthesized, and its ability in suppressing IL-22-induced responses was evaluated in healthy and transformed keratinocytes. We found that KIR-ESS peptide efficiently suppressed the IL-22 molecular signaling in keratinocytes, by acting on STAT3 and Erk1/2 cascade, as well as on the expression of STAT3-dependent downstream genes. Interestingly, after treatment with peptide, both healthy and transformed keratinocytes could no longer aberrantly proliferate and migrate in response to IL-22. Finally, treatment of athymic nude mice bearing SCC xenografts with KIR-ESS peptide concomitantly reduced tumor growth and activated STAT3 levels. As a whole, these data provides the rationale for the use in BCC and SCC skin tumors of SOCS3 mimetics, being able to inhibit the deleterious effects of IL-22 in these contexts.

Effects of potentially functional polymorphisms in suppressor of cytokine signaling 3 (SOCS3) on the risk of head and neck squamous cancer

BACKGROUND

Suppressor of cytokine signaling 3 (SOCS3) has been identified as an inhibitor of JAK/STAT pathway that plays a significant role in carcinogenesis. SOCS3 and JAK2 polymorphisms may influence the gene expression or function, contributing to the disease susceptibility; however, such effect has not been evaluated in head and neck squamous cell carcinoma (HNSCC).

METHODS

A case-control study was performed to test the associations of SOCS3 and JAK2 polymorphisms with risk of HNSCC in 576 cases and 1552 cancer-free controls from China. Seven potentially functional polymorphisms predicted by bioinformatics tools were genotyped using Infinium BeadChip platform. The association between genotypes and HNSCC risk was estimated by computing odds ratios (ORs) and 95% confidence intervals (CIs) in univariate and multivariate logistic regression models.

RESULTS

We found that rs2280148 located at 3'-untranslated region of SOCS3 was significantly associated with an increased risk of HNSCC (additive model: adjusted OR = 1.21, 95% CI = 1.03-1.43, P = 0.021). Moreover, rs8064821 located in the promoter region of SOCS3 was linked with a decreased risk of the cancer (additive model: adjusted OR = 0.83, 95% CI = 0.71-0.97, P = 0.022). Combined analysis of these variants by the number of risk alleles showed a significant locus-dosage effect on the risk of HNSCC (P_trend = 0.006).

CONCLUSIONS

We provided the first evidence that SOCS3 polymorphisms may influence the risk of HNSCC, which could be applied as novel biomarkers to identify individuals at high risk of the disease.

SOCS3 revisited: a broad regulator of disease, now ready for therapeutic use?

Since their discovery, SOCS have been characterised as regulatory cornerstones of intracellular signalling. While classically controlling the JAK/STAT pathway, their inhibitory effects are documented across several cascades, underpinning their essential role in homeostatic maintenance and disease. After 20 years of extensive research, SOCS3 has emerged as arguably the most important family member, through its regulation of both cytokine- and pathogen-induced cascades. In fact, low expression of SOCS3 is associated with autoimmunity and oncogenesis, while high expression is linked to diabetes and pathogenic immune evasion. The induction of SOCS3 by both viruses and bacteria and its impact upon inflammatory disorders, underscores this protein's increasing clinical potential. Therefore, with the aim of highlighting SOCS3 as a therapeutic target for future development, this review revisits its multi-faceted immune regulatory functions and summarises its role in a broad ranges of diseases.

Disarming an Electrophilic Warhead: Retaining Potency in Tyrosine Kinase Inhibitor (TKI)-Resistant CML Lines While Circumventing Pharmacokinetic Liabilities

Pharmacologic blockade of the activation of signal transducer and activator of transcription 3 (STAT3) in tyrosine kinase inhibitor (TKI)-resistant chronic myeloid leukemia (CML) cell lines characterized by kinase-independent resistance was shown to re-sensitize CML cells to TKI therapy, suggesting that STAT3 inhibitors in combination with TKIs are an effective combinatorial therapeutic for the treatment of CML. Benzoic acid- and hydroxamic acid-based STAT3 inhibitors SH-4-054 and SH-5-007, developed previously in our laboratory, demonstrated promising activity against these resistant CML cell lines. However, pharmacokinetic studies in murine models (CD-1 mice) revealed that both SH-4-054 and SH-5-007 are susceptible to glutathione conjugation at the para position of the pentafluorophenyl group via nucleophilic aromatic substitution (SN Ar). To determine whether the electrophilicity of the pentafluorophenyl sulfonamide could be tempered, an in-depth structure-activity relationship (SAR) study of the SH-4-054 scaffold was conducted. These studies revealed that AM-1-124, possessing a 2,3,5,6-tetrafluorophenylsulfonamide group, retained STAT3 protein affinity (Ki =15 μm), as well as selectivity over STAT1 (Ki >250 μm). Moreover, in both hepatocytes and in in vivo pharmacokinetic studies (CD-1 mice), AM-1-124 was found to be dramatically more stable than SH-4-054 (t1/2 =1.42 h cf. 10 min, respectively). AM-1-124 is a promising STAT3-targeting inhibitor with demonstrated bioavailability, suitable for evaluation in preclinical cancer models.

IL-8 induces miR-424-5p expression and modulates SOCS2/STAT5 signaling pathway in oral squamous cell carcinoma

Suppressor of cytokine signaling (SOCS) proteins are negative feedback regulators of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Dysregulation of SOCS protein expression in cancers can be one of the mechanisms that maintain STAT activation, but this mechanism is still poorly understood in oral squamous cell carcinoma (OSCC). Here, we report that SOCS2 protein is significantly downregulated in OSCC patients and its levels are inversely correlated with miR‐424‐5p expression. We identified the SOCS2 protein, which modulates STAT5 activity, as a direct target of miR‐424‐5p. The miR‐424‐5p‐induced STAT5 phosphorylation, matrix metalloproteinases (MMPs) expression, and cell migration and invasion were blocked by SOCS2 restoration, suggesting that miR‐424‐5p exhibits its oncogenic activity through negatively regulating SOCS2 levels. Furthermore, miR‐424‐5p expression could be induced by the cytokine IL‐8 primarily through enhancing STAT5 transcriptional activity rather than NF‐κB signaling. Antagomir‐mediated inactivation of miR‐424‐5p prevented the IL‐8‐induced cell migration and invasion, indicating that miR‐424‐5p is required for IL‐8‐induced cellular invasiveness. Taken together, these data indicate that STAT5‐dependent expression of miR‐424‐5p plays an important role in mediating IL‐8/STAT5/SOCS2 feedback loop, and scavenging miR‐424‐5p function using antagomir may have therapeutic potential for the treatment of OSCC.

miR‐424‐5p is overexpressed in OSCC.

miR‐424‐5p directly targets SOCS2, leading to increased cell migration and invasion.

STAT5 activation is required for IL‐8‐mediated miR‐424‐5p transcription.

miR‐424‐5p plays an important role in mediating IL‐8/STAT5/SOCS2 feedback loop.

Overexpression of Bcl-2, SOCS 1, 3 and Cdh 1, 2 are associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model

BACKGROUND

The objective was to assess histopathological changes and the expression of proliferating cell nuclear antigen (PCNA), Bcl-2, suppressor of cytokine signaling (SOCS) 1 and 3, Vimentin, TWIST1, and Cdh 1 and 2 in early stages of experimental oral carcinogenesis process using a shorter period of exposure to 4-nitroquinoline oxide (4-NQO) model.

METHODS

In this study, 20 rats were divided into control group (n = 10), sacrificed on the first day of the experiment, and experimental group (n = 10) treated with 50 ppm of 4-NQO solution dissolved in drinking water for 8 and 12 weeks. The histological sections were stained with H&E or subjected to immunohistochemistry for detecting PCNA, Bcl-2, SOCS 1 and 3, and STAT 3. Some specimens were used for verification of Vimentin expression, Cdh 1, Cdh 2, and TWIST1 by RT-qPCR.

RESULTS

At both 8 and 12 weeks, morphological changes occurred mainly in the posterior portion of the tongue and were limited to the epithelial tissue, including moderate to severe dysplasia at 8 weeks, and severe dysplasia with exacerbation of atypical cells at 12 weeks. Expression of SOCS 1 and 3 increased from 8 to 12 weeks (P < 0.05), whereas STAT 3 expression was reduced mainly at 12 weeks (P < 0.05) in comparison with the control group. The expression of all epithelial-mesenchymal transition markers (EMT) was increased after 12 weeks, reaching statistical significance (P < 0.05) for Cdh 1 and 2.

CONCLUSIONS

Together, the results suggested that overexpression of Bcl-2, SOCS 1 and 3, and Cdh 1 and 2 is associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model.

The Prognostic Role of SOCS3 and A20 in Human Cholangiocarcinoma

As an antagonist of the JAK/STAT pathway, suppressor of cytokine signaling 3 (SOCS3) plays an integral role in shaping the inflammatory environment, tumorigenesis and disease progression in cholangiocarcinoma (CCA); however, its prognostic significance remains unclear. Although tumor necrosis factor α-induced protein 3 (TNFAIP3, also known as A20) can decrease SOCS3 expression and is involved in the regulation of tumorigenesis in certain malignancies, its role in CCA remains unknown. In this study, we investigated the expression of SOCS3 and A20 in human CCA tissues to assess the prognostic significance of these proteins. The expression of SOCS3 and A20 was initially detected by western blot in 22 cases of freshly frozen CCA tumors with corresponding peritumoral tissues and 22 control normal bile duct tissues. Then, these proteins were investigated in 86 CCA patients by immunohistochemistry (IHC) and were evaluated for their association with clinicopathological parameters in human CCA. The results indicated that SOCS3 expression was significantly lower in CCA tumor tissues than in corresponding peritumoral biliary tissues and normal bile duct tissues. Conversely, A20 was overexpressed in CCA tissues. Thus, an inverse correlation between the expression of SOCS3 and A20 was discovered. Furthermore, patients with low SOCS3 expression or high A20 expression showed a dramatically lower overall survival rate. These proteins were both associated with CCA lymph node metastasis, postoperative recurrence and overall survival rate. However, only A20 showed a significant association with the tumor node metastasis (TNM) stage, while SOCS3 showed a significant association with tumor differentiation. Multivariate Cox analysis revealed that SOCS3 and A20 were independent prognostic indicators for overall survival in CCA. Thus, our study demonstrated that SOCS3 and A20 represent novel prognostic factors for human CCA.

Enhanced expression of suppresser of cytokine signaling 3 inhibits the IL-6-induced epithelial-to-mesenchymal transition and cholangiocarcinoma cell metastasis

It was recently demonstrated that interleukin-6 (IL-6) induces the epithelial-to-mesenchymal transition (EMT) in cholangiocarcinoma (CCA), but the underlying molecular mechanism remains to be explored. In this study, we studied the role of suppresser of cytokine signaling 3 (SOCS3), a negative feedback regulator of IL-6/STAT3, in the IL-6-induced EMT in CCA. Treatment with IL-6 induced the EMT by decreasing the E-cadherin expression and increasing the expression of N-cadherin and vimentin. Using wound healing and invasion assays, we found that IL-6 promoted cell motility. Further, a stably transfected cell line overexpressing SOCS3 was constructed. Enhanced SOCS3 expression decreased IL-6-induced cell invasion and EMT in parallel with downregulating the IL-6/STAT3 pathway. In contrast, SOCS3 silencing using siRNA exhibited no effect on the cell invasive ability and EMT. Finally, an in vivo study indicated that the enhancement of SOCS3 expression decreased metastasis compared with the control, and this effect was achieved by the repression of p-STAT3, N-cadherin and vimentin, and the induction of E-cadherin assessed by Western blot analysis. Our results suggest that enhanced expression of SOCS3 can antagonize IL-6-induced EMT and cell metastasis by abrogating the IL-6/STAT3 pathway. These data establish that SOCS3 plays a role in the EMT in CCA and may provide novel therapeutic strategies for CCA.

Significance of suppressor of cytokine signaling-3 expression in bladder urothelial carcinoma in relation to proinflammatory cytokines and tumor histopathological grading

BACKGROUND

Bladder cancer is among the five most common malignancies worldwide. Altered expression of suppressor of cytokine signaling -3 (SOCS-3) has been implicated in various types of human cancers; however, its role in bladder cancer is not well established.

AIM

The present study was undertaken to investigate the mRNA expression of SOCS-3 in normal and cancerous bladder tissue and to explore its correlation with urinary levels of some proinflammatory cytokines, cytokeratin-18 (CK -18) and with tumor histopathological grading, in order to evaluate their role as potential diagnostic markers.

MATERIALS AND METHODS

SOCS3 mRNA expression levels were evaluated using quantitative real time PCR. Urinary levels of interleukins 6 and 8 were estimated by enzyme linked immunosorbent assay (ELISA). Cytokeratin-18 expression was analyzed by immuunohistochemistry then validated by ELISA.

RESULTS

SOC3 m RNA expression levels were significantly lower in high grade urothelial carcinoma (0.36±0.12) compared to low grade carcinoma (1.22±0.38) and controls (4.08±0.88), (p<0.001). However, in high grade urothelial carcinoma the urinary levels of IL-6, IL-8, total CK-18(221.33±22.84 pg/ml, 325.2±53.6 pg/ ml, 466.7±57.40 U/L respectively) were significantly higher than their levels in low grade carcinoma (58.6±18.6 pg/ ml, 58.3±50.2 pg/ml, 185.5±60.3 U/L respectively) and controls (50.9±23.0 pg/ml, 7.12±2.74 pg/ml, 106.7±47.3U/L respectively), (p<0.001).

CONCLUSIONS

Advanced grade of urothelial bladder carcinoma is significantly associated with lowered mRNA expression of SOC3 as well as elevated urinary levels of proinflammatory cytokines and CK-18. Furthermore, our results suggested that urinary IL-8, IL-6 and CK-18 may benefit as noninvasive biomarkers for early detection as well as histopathological subtyping of urothelial carcinoma.

Monoclonal Antibodies Specific for STAT3β Reveal Its Contribution to Constitutive STAT3 Phosphorylation in Breast Cancer

Since its discovery in mice and humans 19 years ago, the contribution of alternatively spliced Stat3, Stat3β, to the overall functions of Stat3 has been controversial. Tyrosine-phosphorylated (p) Stat3β homodimers are more stable, bind DNA more avidly, are less susceptible to dephosphorylation, and exhibit distinct intracellular dynamics, most notably markedly prolonged nuclear retention, compared to pStat3α homodimers. Overexpression of one or the other isoform in cell lines demonstrated that Stat3β acted as a dominant-negative of Stat3α in transformation assays; however, studies with mouse strains deficient in one or the other isoform indicated distinct contributions of Stat3 isoforms to inflammation. Current immunological reagents cannot differentiate Stat3β proteins derived from alternative splicing vs. proteolytic cleavage of Stat3α. We developed monoclonal antibodies that recognize the 7 C-terminal amino acids unique to Stat3β (CT7) and do not cross-react with Stat3α. Immunoblotting studies revealed that levels of Stat3β protein, but not Stat3α, in breast cancer cell lines positively correlated with overall pStat3 levels, suggesting that Stat3β may contribute to constitutive Stat3 activation in this tumor system. The ability to unambiguously discriminate splice alternative Stat3β from proteolytic Stat3β and Stat3α will provide new insights into the contribution of Stat3β vs. Stat3α to oncogenesis, as well as other biological and pathological processes.

Sphingosine kinase 1 mediates head & neck squamous cell carcinoma invasion through sphingosine 1-phosphate receptor 1

Background

Head and neck squamous cell carcinoma (HNSCC) is characterized by aggressive loco-regional invasion. Sphingosine kinase1 (SphK1), an enzyme in sphingolipid metabolism, is emerging as a key player in HNSCC pathology. The observation that SphK1 is overexpressed in all HNSCC stages and is associated with depth of tumor invasion, metastasis and clinical failure underscores the importance of SphK1 in HNSCC pathology. Still, the mechanisms underlying SphK1 regulation of invasion have not been delineated. Therefore, we sought to mechanistically describe how SphK1 regulates invasion in HNSCC.

Methods

Invasion assays were used to measure invasive ability of SphK1 overexpressing human tongue squamous cell carcinoma (SCC-25 cells). Western blotting, quantitative qPCR, ELISA and zymography were used to measure the effect of SphK1 and sphingosine 1-phoshate receptor 1 (S1P₁) on invasion measures, MMP-2/9, E-cadherin, EGFR, IL-6/STAT3, in SCC-25 cells.

Results

SphK1 expression is elevated in cells with an invasive phenotype as compared to non-invasive phenotype. We show SphK1 overexpression increased EGF-induced EGFR/ERK and AKT activity, increased matrix metalloproteinase (MMP)-2/9 mRNA and reduced E-cadherin. SphK1 overexpression also increased IL-6 concentration and EGF-induced STAT3 phosphorylation, exemplifying that SphK1 modulates IL-6/STAT3 signaling. Notably, we show that S1P₁ knockdown reduced IL-6/STAT3 signaling, representing another pathway by which SphK1/S1P regulates invasion.

Conclusions

Taken together, our data suggest that SphK1 sits at the hub of multiple key signaling cascades, all which have been implicated in the regulation of invasiveness, making SphK1 an attractive target for the development of HNSCC therapies.

Combined STAT3 and BCR-ABL1 inhibition induces synthetic lethality in therapy-resistant chronic myeloid leukemia

Mutations in the BCR-ABL1 kinase domain are an established mechanism of tyrosine kinase inhibitor (TKI) resistance in Philadelphia chromosome-positive leukemia, but fail to explain many cases of clinical TKI failure. In contrast, it is largely unknown why some patients fail TKI therapy despite continued suppression of BCR-ABL1 kinase activity, a situation termed BCRABL1 kinase-independent TKI resistance. Here, we identified activation of signal transducer and activator of transcription 3 (STAT3) by extrinsic or intrinsic mechanisms as an essential feature of BCR-ABL1 kinase-independent TKI resistance. By combining synthetic chemistry, in vitro reporter assays, and molecular dynamics-guided rational inhibitor design and high-throughput screening, we discovered BP-5-087, a potent and selective STAT3 SH2 domain inhibitor that reduces STAT3 phosphorylation and nuclear transactivation. Computational simulations, fluorescence polarization assays, and hydrogen-deuterium exchange assays establish direct engagement of STAT3 by BP-5-087 and provide a high-resolution view of the STAT3 SH2 domain/BP-5-087 interface. In primary cells from CML patients with BCR-ABL1 kinase-independent TKI resistance, BP-5-087 (1.0 μM) restored TKI sensitivity to therapy-resistant CML progenitor cells, including leukemic stem cells (LSCs). Our findings implicate STAT3 as a critical signaling node in BCR-ABL1 kinase-independent TKI resistance, and suggest that BP-5-087 has clinical utility for treating malignancies characterized by STAT3 activation.

Human metapneumovirus inhibits the IL-6-induced JAK/STAT3 signalling cascade in airway epithelium

The host cytokine IL-6 plays an important role in host defence and prevention of lung injury from various pathogens, making IL-6 an important mediator in the host's susceptibility to respiratory infections. The cellular response to IL-6 is mediated through a Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signal transduction pathway. Human metapneumovirus (hMPV) is an important causative agent of viral respiratory infections known to inhibit the IFN-mediated activation of STAT1. However, little is known about the interactions between this virus and other STAT signalling cascades. Herein, we showed that hMPV can attenuate the IL-6-mediated JAK/STAT3 signalling cascade in lung epithelial cells. HMPV inhibited a key event in this pathway by impeding the phosphorylation and nuclear translocation of STAT3 in A549 cells and in primary normal human bronchial epithelial cells. Further studies established that hMPV interrupted the IL-6-induced JAK/STAT pathway early in the signal transduction pathway by blocking the phosphorylation of JAK2. By antagonizing the IL-6-mediated JAK/STAT3 pathway, hMPV perturbed the expression of IL-6-inducible genes important for apoptosis, cell differentiation and growth. Infection with hMPV also differentially regulated the effects of IL-6 on apoptosis. Thus, hMPV regulation of these genes could usurp the protective roles of IL-6, and these data provide insight into an important element of viral pathogenesis.