BACKGROUND: The suppressor of cytokine signaling (SOCS) family of proteins are inhibitors of the cytokine-activated Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway. We aimed at evaluation of expression of SOCS genes in breast cancer.
METHODS: We evaluated expression of SOCS1-3 and SOCS5 genes in breast cancer samples compared with the corresponding adjacent non-cancerous tissues (ANCTs).
RESULTS: All assessed SOCS genes were significantly downregulated in tumoral tissues compared with ANCTs. SOCS1 and SOCS2 genes were significantly overexpressed in higher grade samples, but SOCS3 had the opposite trend. Significant correlations were found between expression levels of SOCS genes. The SOCS1 and SOCS2 expression levels had the best specificity and sensitivity values respectively for breast cancer diagnosis.
CONCLUSION: The current study provides further evidence for contribution of SOCS genes in breast cancer.

Although gastric cancer (GC) is one of the most common cancers, knowledge of its development, and carcinogenesis is limited. The present study explored the involvement of ceramide synthase 6 (CERS6) in GC carcinogenesis and prognosis. RT-PCR, immunoblotting, and immunohistochemistry were used to examine the expression of CERS6. Transfection and small hairpin RNA technology were used to investigate the effect of CERS6 manipulation on cell proliferation and spread as well as the underlying mechanism. Moreover, xenograft proliferation was employed to explore the influence of CERS6 on tumor growth in animals. It was found that overexpression of CERS6 was significantly correlated with several clinicopathologic parameters and poor disease-free survival. The overexpression and silencing of CERS6 in GC cells facilitated and suppressed cell proliferation and spread as well as xenograft proliferation, respectively. Mechanistic studies further revealed that CERS6 influenced cell proliferation and spread by regulating cell cycle control and metastasis-related protein through the SOCS2/JAK2/STAT3 signaling pathway. Collectively, this study suggests that CERS6 overexpression could be a useful biomarker for predicting the outcomes of GC patients and that CERS6 targeting represents a potential modality for treating GC.

BACKGROUND: Laryngeal squamous cell carcinoma (LSCC) has the second highest incidence among the head and neck malignancies. Additionally, the incidence of LSCCs has been recently increasing. Therefore, understanding the mechanisms of LSCC tumorigenesis and identifying novel biomarkers to accurately predict and improve the prognosis of patients with LSCC is extremely important.
METHODS: miR-196b and SOCS2 expression was measured by qRT-PCR and western blot. Their correlation was analyzed with the Pearson test. TU212 and TU177 cells were cultured and transfected for MTT, Transwell, and apoptosis assays upon miR-196b knockdown, SOSC2 overexpression or SOCS2 silencing. Dual-luciferase reporter assay were conducted to identify the relationship between miR-196b and SOCS2. Moreover, the correlation between clinicopathological parameters and miR-196b/SOCS2 expression in patients was analyzed. Univariate and multivariate analysis and log-rank tests were used to determine if miR-196 was an independent LSCC prognostic factors.
RESULTS: We reported the aberrant expression and inverse correlation of miR-196b and SOCS2 in LSCC samples. miR-196b promoted LSCC cells proliferation and invasion, and suppressed apoptosis by directly inhibiting SOCS2 expression in vitro. Moreover, we also revealed that miR-196b/SOCS2 expression correlated with T stage and cervical metastasis. miR-196b was demonstrated to be an independent prognostic factor for overall survival of patients with LSCC.
CONCLUSIONS: Overexpression of miR-196b suppresses SOCS2 in human LSCC resulting in tumor progression and poor prognosis. miR-196b is a potential marker for prognosis assessment and targeting miR-196b may be a novel valuable strategy for the treatment of LSCC.

Altered expression of suppressor of cytokine signaling (SOCS) is found in various tumors. However, regulation of SOCS2 by upstream molecules has yet to be clearly elucidated, particularly in tumor cells. SCOCS2 expression was examined in tumor cells transfected with an inducible p53 expression system. The impact of SOCS2 on cell proliferation was measured with in vitro assays. Inhibition of tumorigenicity by SOCS2 knockdown was assessed via a mouse model. Expression profiles were compared and genes differentially expressed were identified using four types of p53-null cells (Saos, HLK3, PC3, and H1299) and the same cells stably expressing p53. Twelve kinds of target genes were simultaneously upregulated or downregulated by p53 in three or more sets of p53-null cells. SOCS2 expression was reciprocally inhibited by inducible p53 expression in p53-null cells, even colon cancer cells. SOCS2 promoter activity was inhibited by wild type but not mutant p53. SOCS2 knockdown inhibited tumor growth in vitro and in an animal xenograph model. SOCS2 overexpression was detected in a murine model of azoxymethane/dextran sulfate sodium-induced colitis-associated colon cancer compared to mock-treated controls. SOCS2 expression was heterogeneously upregulated in some human colon cancers. Thus, SOCS2 was upregulated by p53 dysfunction and seemed to be associated with the tumorigenic potential of colon cancer.

The strength and duration of STAT3 signaling are tightly controlled by multiple negative feedback mechanisms under physical conditions. However, how these serial feedback loops are simultaneously disrupted in cancers, leading to constitutive activation of STAT3 signaling in hepatocellular carcinoma (HCC), remains obscure. Here we report that miR-589-5p is elevated in HCC tissues, which is caused by recurrent gains. Overexpression of miR-589-5p correlates with poor overall and relapse-free survival in HCC patients. Upregulating miR-589-5p enhances spheroid formation ability, fraction of CD133 positive and side population cells, expression of cancer stem cell factors and the mitochondrial potential, and represses the apoptosis induced by doxorubicin in vitro and tumorigenicity in vivo in HCC cells; conversely, silencing miR-589-5p yields an opposite effect. Our findings further demonstrate miR-589-5p promotes the cancer stem cell characteristics and chemoresistance via targeting multiple negative regulators of STAT3 signaling pathway, including SOCS2, SOCS5, PTPN1 and PTPN11, leading to constitutive activation of STAT3 signaling. Collectively, our results unravel a novel mechanism by which miR-589-5p promotes the maintenance of stemness and chemoresistance in HCC, providing a potential rational registry of anti-miR-589-5p combining with conventional chemotherapy against HCC.

Both humans and mice lacking functional growth hormone (GH) receptors are known to be resistant to cancer. Further, autocrine GH has been reported to act as a cancer promoter. Here we present the first example of a variant of the GH receptor (GHR) associated with cancer promotion, in this case lung cancer. We show that the GHRP495T variant located in the receptor intracellular domain is able to prolong the GH signal in vitro using stably expressing mouse pro-B-cell and human lung cell lines. This is relevant because GH secretion is pulsatile, and extending the signal duration makes it resemble autocrine GH action. Signal duration for the activated GHR is primarily controlled by suppressor of cytokine signalling 2 (SOCS2), the substrate recognition component of the E3 protein ligase responsible for ubiquitinylation and degradation of the GHR. SOCS2 is induced by a GH pulse and we show that SOCS2 binding to the GHR is impaired by a threonine substitution at Pro 495. This results in decreased internalisation and degradation of the receptor evident in TIRF microscopy and by measurement of mature (surface) receptor expression. Mutational analysis showed that the residue at position 495 impairs SOCS2 binding only when a threonine is present, consistent with interference with the adjacent Thr494. The latter is key for SOCS2 binding, together with nearby Tyr487, which must be phosphorylated for SOCS2 binding. We also undertook nuclear magnetic resonance spectroscopy approach for structural comparison of the SOCS2 binding scaffold Ile455-Ser588, and concluded that this single substitution has altered the structure of the SOCS2 binding site. Importantly, we find that lung BEAS-2B cells expressing GHRP495T display increased expression of transcripts associated with tumour proliferation, epithelial-mesenchymal transition and metastases (TWIST1, SNAI2, EGFR, MYC and CCND1) at 2 h after a GH pulse. This is consistent with prolonged GH signalling acting to promote cancer progression in lung cancer.

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide, because recurrence often occurs in most HCC patients undergoing hepatectomy. It is necessary to identify patients with high risk for recurrence and adopt effective therapies. An obstacle to monitor patients at high risk for poor prognosis has been the lack of useful predictive biomarkers. Fortunately, recent progress in system biology allows to screen the biomarkers for HCC prognosis in a high-throughput manner. In this study, we performed systematic Kaplan-Meier survival analysis of the whole mRNA transcriptomics based on the Cancer Genome Atlas project (TCGA) and developed a three-gene prognostic signature composing of three genes UPB1, SOCS2 and RTN3. The model was validated in two independent microarray data sets retrieved from Gene Expression Omnibus (GEO) and the expression pattern of these three predictive genes in HCC was confirmed by western blot and immunohistochemistry with our HCC samples. In conclusion, our results showed that this three-gene signature has prognostic value for HCC patients.

Certain viruses use microRNAs to regulate the expression of their own genes, host genes, or both. A number of microRNAs expressed by herpes simplex virus type 2 have been confirmed by previous studies. However, whether these microRNAs play a role in the metastasis of lung cancers and how these viral microRNAs precisely regulated the tumor biological process in lung cancer bone metastasis remain obscure. We recently identified the high expression of an acutely and latently expressed viral microRNA, Hsv2-miR-H9-5p, encoded by herpes simplex virus type 2 latency-associated transcript through microarray and quantitative polymerase chain reaction analyses which compared the expression of microRNAs in bone metastasis from lung cancer with primary lung cancers. We now reported that Hsv2-miR-H9-5p was highly expressed in bone metastasis and closely associated with pathological and metastatic processes of lung cancers. The functions of Hsv2-miR-H9-5p were determined by overexpression which results in an increase in survival, migration, and invasion of lung cancer cells in vitro. We determined that Hsv2-miR-H9-5p directly targeted SOCS2 mechanistically by dual-luciferase reporter assay. Then, we investigated the functions of SOCS2 in the progress of lung cancers. Reduction of SOCS2 dosage by hsv2-miR-H9-5p induced increased migration and invasion of lung cancer cells. Overexpression of SOCS2 inverted these phenotypes generated by hsv2-miR-H9-5p, indicating the potential roles of SOCS2 in Hsv2-miR-H9-5p-driven metastasis in lung cancers. The results highlighted that Hsv2-miR-H9-5p regulated and contributed to bone metastasis of lung cancers. We proposed that Hsv2-miR-H9-5p could be used as a potential target in lung cancer therapy.

BACKGROUND: Molecular heterogeneity accounts for the variable and often poor prognosis in acute myeloid leukemia (AML). The current risk stratification strategy in clinical practice is limited to karyotyping and limited molecular studies screening for genetic mutations such as FLT-3 and NPM1. There is opportunity to identify further molecular prognostic markers, which may also lay the groundwork for the development of novel targeted therapies. Complex molecular technologies require transition into widely available laboratory platforms, for better integration into routine clinical practice.
METHOD: In a defined subset (MYC/BCL2 or MYC/BCL2) of AML patients (n=20), we examined expression signature of several genes (n=12) of established prognostic value in AML. RNA expression and MYC/BCL2 protein pattern was correlated with 3 cytogenetic risk groups and overall survival.
RESULTS: K-means++ unsupervised clustering defined 2 distinct groups with high and low transcript levels of BAALC/MN1/MLLT11/EVI1/SOCS2 genes (>2.5-fold difference; P<0.001). This mRNA signature trended with higher prevalence of MYC/BCL2 coexpression (P<0.057) and poor overall survival (P<0.036), but did not correlate with conventional cytogenetic risk groups (P<0.084).
CONCLUSIONS: This pilot study provides useful data, which may help further refine the prognostic scheme of AML patients outside conventional cytogenetic risk groups. It also presents some biological rationale for future studies to explore the use of novel agents targeting MYC and/or BCL2 genes in combination with conventional chemotherapy protocols for AML.

SOCS2 is a pleiotropic E3 ligase. Its deficiency is associated with gigantism and organismal lethality upon inflammatory challenge. However, mechanistic understanding of SOCS2 function is dismal due to our unawareness of its protein substrates. We performed a mass spectrometry based proteomic profiling upon SOCS2 depletion and yield quantitative data for ~4200 proteins. Through this screen we identify a novel target of SOCS2, the serine-threonine kinase NDR1. Over-expression of SOCS2 accelerates turnover, while its knockdown stabilizes, endogenous NDR1 protein. SOCS2 interacts with NDR1 and promotes its degradation through K48-linked ubiquitination. Functionally, over-expression of SOCS2 antagonizes NDR1-induced TNFα-stimulated NF-κB activity. Conversely, depletion of NDR1 rescues the effect of SOCS2-deficiency on TNFα-induced NF-κB transactivation. Using a SOCS2

Glioblastomas (GBM) are very difficult to treat and their aggressiveness is one of the main reasons for this as well as for the frequent recurrences. MicroRNAs post-transcriptionally regulate their target genes through interaction between their seed sequence and 3'UTR of the target mRNAs. We previously reported that miR-296-3p is regulated by neurofibromatosis 2 (NF2) and enhances the invasiveness of GBM cells via SOCS2/STAT3. In this study, we investigated whether miR-296-5p, which originates from the same precursor miRNA as miR-296-3p, can increase the invasiveness of GBM cells. It was observed that miR-296-5p potentiated the invasion of various GBM cells including LN229, T98G, and U87MG. Through bioinformatics approaches, two genes were identified as miR-296-5p targets: caspase-8 (CASP8) and nerve growth factor receptor (NGFR). From results obtained from Ago2 immunoprecipitation and luciferase assays, we found that miR-296-5p downregulates CASP8 and NGFR through direct interaction between seed sequence of the miRNA and 3'UTR of the target mRNA. Knockdown of CASP8 or NGFR also increased the invasive ability of GBM cells, indicating that CASP8 and NGFR are involved in potentiation of invasiveness by miR-296-5p. Consistent with our findings, CASP8 was downregulated in brain metastatic lung cancer cells, which have a high level of miR-296-5p, compared to parental cells, suggesting that miR-296-5p may be generally associated with the acquisition of invasiveness. Collectively, our results implicate miR-296-5p as a potential cause of invasiveness in cancer and suggest it as a promising therapeutic target for GBM.

BACKGROUND: Previous work characterized variants of the EL4 murine lymphoma cell line. Some are non-metastatic, and others metastatic, in syngenic mice. In addition, metastatic EL4 cells were stably transfected with phospholipase D2 (PLD2), which further enhanced metastasis.
MATERIALS AND METHODS: Microarray analyses of mRNA expression was performed for non-metastatic, metastatic, and PLD2-expressing metastatic EL4 cells.
RESULTS: Many differences were observed between non-metastatic and metastatic cell lines. One of the most striking new findings was up-regulation of mRNA for the matricellular protein WNT1-inducible signaling pathway protein 1 (CCN4) in metastatic cells; increased protein expression was verified by immunoblotting and immunocytochemistry. Other differentially expressed genes included those for reproductive homeobox 5 (Rhox5; increased in metastatic) and cystatin 7 (Cst7; decreased in metastatic). Differences between PLD2-expressing and parental cell lines were limited but included the signaling proteins Ras guanyl releasing protein 1 (RGS18; increased with PLD2) and suppressor of cytokine signaling 2 (SOCS2; decreased with PLD2).
CONCLUSION: The results provide insights into signaling pathways potentially involved in conferring metastatic ability on lymphoma cells.

Hepatocellular carcinoma (HCC) is a common cause of cancer-related death worldwide, and its incidence continues to increase. However, the mechanism underlying the development and progression of HCC remains unknown. The suppressor of cytokine signaling 2 (SOCS2) is a member of the SOCS family and influences the carcinogenesis of multiple types of tumors, but the biological roles of SOCS2 in HCC remain unclear. In this study, we found that SOCS2 expression was reduced in HCC tissues compared with matched noncancerous liver tissues. Moreover, decreased SOCS2 expression was significantly associated with the presence of intrahepatic metastasis and high histological grade in HCC patients. Colony formation assays and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays demonstrated that overexpression of SOCS2 or knockdown of endogenous SOCS2 did not significantly affect cell proliferation and tumorigenicity in HCC cells in vitro and in vivo. However, SOCS2 overexpression significantly inhibited the migration and invasion of HCC cells in vitro and inhibited metastasis in vivo. Consistent with these findings, the knockdown of endogenous SOCS2 enhanced migration and invasion in HCC cells in vitro. Our study demonstrated that SOCS2 inhibited human HCC metastasis, and SOCS2 might provide a new potential therapeutic strategy for treating HCC.

Long noncoding RNAs (lncRNA) have been associated with the development of cancer. However, the interplay between lncRNAs and androgen receptor (AR) signaling in prostate cancer is still unclear. Here, we identified lncRNAs induced by androgen in AR-positive prostate cancer cells, where induction was abolished by AR knockdown as well as an anti-androgen, bicalutamide. By combining these data, we identified an androgen-regulated lncRNA, suppressor of cytokine signaling 2-antisense transcript 1 (SOCS2-AS1), the expression of which was higher in castration-resistant prostate cancer model cells, i.e long-term androgen-deprived (LTAD) cells, than in parental androgen-dependent LNCaP cells. SOCS2-AS1 promoted castration-resistant and androgen-dependent cell growth. We found that SOCS2-AS1 knockdown up-regulated genes related to the apoptosis pathway, including tumor necrosis factor superfamily 10 (TNFSF10), and sensitized prostate cancer cells to docetaxel treatment. Moreover, we also demonstrated that SOCS2-AS1 promotes androgen signaling by modulating the epigenetic control for AR target genes including TNFSF10 These findings suggest that SOCS2-AS1 plays an important role in the development of castration-resistant prostate cancer by repressing apoptosis.

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.

Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor derived from non-neuronal glial cells. Neurofibromatosis 2 (NF2) protein, also termed as merlin, is a well-known tumor suppressor; however, the molecular mechanism underlying this effect has not yet been fully defined. To investigate the role of NF2 in the invasiveness of GBM, we used two GBM cell lines: NF2-expressing T98G cells and NF2-deficient A172 cells. Knockdown of NF2 increased the invasiveness of T98G cells, whereas NF2-overexpressing A172 cells showed decreased invasive activity. Moreover, re-expression of NF2 reversed the high invasiveness of NF2-silenced T98G cells, indicating that NF2 negatively regulates GBM invasiveness. We further found that the NF2-mediated regulation of invasiveness was dependent on YAP and TEAD2 expression levels. NF2 also controlled the expression of YAP targets, including cysteine-rich angiogenic inducer 61 (CYR61/CCN1), by regulating the nuclear localization of YAP. Silencing of CYR61/CCN1 blocked the increased invasiveness of T98G cells, suggesting that CYR61/CCN1 is required for NF2-mediated invasiveness. Through microRNA microarray analysis, we found that NF2 negatively regulates the expression of miR-296-3p. Overexpression of miR-296-3p suppressed the expression of STAT5A, induced the phosphorylation of STAT3 by downregulating SOCS2, and increased the invasiveness of T98G cells. Taken together, we demonstrate that NF2 negatively controls the invasiveness of GBM through YAP-dependent induction of CYR61/CCN1 and miR-296-3p.

Acquired resistance to lapatinib is a highly problematic clinical barrier that has to be overcome for a successful cancer treatment. Despite efforts to determine the mechanisms underlying acquired lapatinib resistance (ALR), no definitive genetic factors have been reported to be solely responsible for the acquired resistance in breast cancer. Therefore, we performed a cross-platform meta-analysis of three publically available microarray datasets related to breast cancer with ALR, using the R-based RankProd package. From the meta-analysis, we were able to identify a total of 990 differentially expressed genes (DEGs, 406 upregulated, 584 downregulated) that are potentially associated with ALR. Gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEGs showed that "response to organic substance" and "p53 signaling pathway" may be largely involved in ALR process. Of these, many of the top 50 upregulated and downregulated DEGs were found in oncogenesis of various tumors and cancers. For the top 50 DEGs, we constructed the gene coexpression and protein-protein interaction networks from a huge database of well-known molecular interactions. By integrative analysis of two systemic networks, we condensed the total number of DEGs to six common genes (LGALS1, PRSS23, PTRF, FHL2, TOB1, and SOCS2). Furthermore, these genes were confirmed in functional module eigens obtained from the weighted gene correlation network analysis of total DEGs in the microarray datasets ("GSE16179" and "GSE52707"). Our integrative meta-analysis could provide a comprehensive perspective into complex mechanisms underlying ALR in breast cancer and a theoretical support for further chemotherapeutic studies.

To study the effect of chronic excess growth hormone on adipose tissue, we performed RNA sequencing in adipose tissue biopsies from patients with acromegaly (n = 7) or non-functioning pituitary adenomas (n = 11). The patients underwent clinical and metabolic profiling including assessment of HOMA-IR. Explants of adipose tissue were assayed ex vivo for lipolysis and ceramide levels. Patients with acromegaly had higher glucose, higher insulin levels and higher HOMA-IR score. We observed several previously reported transcriptional changes (IGF1, IGFBP3, CISH, SOCS2) that are known to be induced by GH/IGF-1 in liver but are also induced in adipose tissue. We also identified several novel transcriptional changes, some of which may be important for GH/IGF responses (PTPN3 and PTPN4) and the effects of acromegaly on growth and proliferation. Several differentially expressed transcripts may be important in GH/IGF-1-induced metabolic changes. Specifically, induction of LPL, ABHD5, and NRIP1 can contribute to enhanced lipolysis and may explain the elevated adipose tissue lipolysis in acromegalic patients. Higher expression of TCF7L2 and the fatty acid desaturases FADS1, FADS2 and SCD could contribute to insulin resistance. Ceramides were not different between the two groups. In summary, we have identified the acromegaly gene expression signature in human adipose tissue. The significance of altered expression of specific transcripts will enhance our understanding of the metabolic and proliferative changes associated with acromegaly.

Hematopoietic stem cells (HSC) promptly adapt hematopoiesis to stress conditions, such as infection and cancer, replenishing bone marrow-derived circulating populations, while preserving the stem cell reservoir. SOCS2, a feedback inhibitor of JAK-STAT pathways, is expressed in most primitive HSC and is upregulated in response to STAT5-inducing cytokines. We demonstrate that Socs2 deficiency unleashes HSC proliferation in vitro, sustaining STAT5 phosphorylation in response to IL3, thrombopoietin, and GM-CSF. In vivo, SOCS2 deficiency leads to unrestricted myelopoietic response to 5-fluorouracil (5-FU) and, in turn, induces exhaustion of long-term HSC function along serial bone marrow transplantations. The emerging role of SOCS2 in HSC under stress conditions prompted the investigation of malignant hematopoiesis. High levels of SOCS2 characterize unfavorable subsets of acute myeloid and lymphoblastic leukemias, such as those with MLL and BCR/ABL abnormalities, and correlate with the enrichment of genes belonging to hematopoietic and leukemic stemness signatures. In this setting, SOCS2 and its correlated genes are part of regulatory networks fronted by IKZF1/Ikaros and MEF2C, two transcriptional regulators involved in normal and leukemic hematopoiesis that have never been linked to SOCS2. Accordingly, a comparison of murine wt and Socs2(-/-) HSC gene expression in response to 5-FU revealed a significant overlap with the molecular programs that correlate with SOCS2 expression in leukemias, particularly with the oncogenic pathways and with the IKZF1/Ikaros and MEF2C-predicted targets. Lentiviral gene transduction of murine hematopoietic precursors with Mef2c, but not with Ikzf1, induces Socs2 upregulation, unveiling a direct control exerted by Mef2c over Socs2 expression.

Polo-like kinase 1 (PLK1) is highly expressed in many cancers and therefore a biomarker of transformation and potential target for the development of cancer-specific small molecule drugs. RO3280 was recently identified as a novel PLK1 inhibitor; however its therapeutic effects in leukemia treatment are still unknown. We found that the PLK1 protein was highly expressed in leukemia cell lines as well as 73.3% (11/15) of pediatric acute myeloid leukemia (AML) samples. PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Kaplan-Meier survival analysis revealed that shorter survival time correlated with high tumor PLK1 expression (p = 0.002). The 50% inhibitory concentration (IC50) of RO3280 for acute leukemia cells was between 74 and 797 nM. The IC50 of RO3280 in primary acute lymphocytic leukemia (ALL) and AML cells was between 35.49 and 110.76 nM and 52.80 and 147.50 nM, respectively. RO3280 induced apoptosis and cell cycle disorder in leukemia cells. RO3280 treatment regulated several apoptosis-associated genes. The regulation of DCC, CDKN1A, BTK, and SOCS2 was verified by western blot. These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.

Several microRNAs (miRNA) have been implicated in H. pylori related gastric cancer (GC). However, the molecular mechanism of miRNAs in gastric cancer has not been fully understood. In this study, we reported that miR-101 is significantly down-regulated in H. pylori positive tissues and cells and in tumor tissues with important functional consequences. Ectopic expression of miR-101 dramatically suppressed cell proliferation and colony formation by inducing G1-phase cell-cycle arrest. We found that miR-101 strongly reduced the expression of SOCS2 oncogene in GC cells. Similar to the restoring miR-26 expression, SOCS2 down-regulation inhibited cell growth and cell-cycle progression, whereas SOCS2 over-expression rescued the suppressive effect of miR-101. Mechanistic investigations revealed that miR-101 suppressed the expression of c-myc, CDK2, CDK4, CDK6, CCND2, CCND3, and CCNE2, while promoted tumor suppressor p14, p16, p21 and p27 expression. In clinical specimens, SOCS2 was over-expressed in tumors and H. pylori positive tissues and its mRNA levels were inversely correlated with miR-101 expression. Taken together, our results indicated that miR-101 functions as a growth-suppressive miRNA in H. pylori related GC, and that its suppressive effects are mediated mainly by repressing SOCS2 expression.

BACKGROUND: The JAK-STAT pathway is an important signaling pathway downstream of multiple cytokine and growth factor receptors. Dysregulated JAK-STAT signaling has been implicated in the pathogenesis of multiple human malignancies.
OBJECTIVE: Given this pivotal role of JAK-STAT dysregulation, it is important to identify patients with an overactive JAK-STAT pathway for possible treatment with JAK inhibitors.
METHODS: We developed a gene signature assay to detect overactive JAK-STAT signaling. The cancer cell line encyclopedia and associated gene-expression data were used to correlate the activation status of STAT5 with the induction of a set of STAT5 target genes.
RESULTS: Four target genes were identified (PIM1, CISH, SOCS2, and ID1), the expression of which correlated significantly with pSTAT5 status in 40 hematologic tumor cell lines. In pSTAT5-positive models, the expression of the gene signature genes decreased following ruxolitinib treatment, which corresponded to pSTAT5 downmodulation. In pSTAT5-negative cell lines, neither pSTAT5 modulation nor a change in signature gene expression was observed following ruxolitinib treatment.
CONCLUSIONS: The gene signature can potentially be used to stratify or enrich for patient populations with activated JAK-STAT5 signaling that might benefit from treatments targeting JAK-STAT signaling. Furthermore, the 4-gene signature is a predictor of the pharmacodynamic effects of ruxolitinib.

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway is involved in immune function and cell growth; genetic variation in this pathway could influence breast cancer risk. We examined 12 genes in the JAK/STAT/SOCS signaling pathway with breast cancer risk and mortality in an admixed population of Hispanic (2,111 cases, 2,597 controls) and non-Hispanic white (1,481 cases, 1,585 controls) women. Associations were assessed by Indigenous American (IA) ancestry. After adjustment for multiple comparisons, JAK1 (three of ten SNPs) and JAK2 (4 of 11 SNPs) interacted with body mass index (BMI) among pre-menopausal women, while STAT3 (four of five SNPs) interacted significantly with BMI among post-menopausal women to alter breast cancer risk. STAT6 rs3024979 and TYK2 rs280519 altered breast cancer-specific mortality among all women. Associations with breast cancer-specific mortality differed by IA ancestry; SOCS1 rs193779, STAT3 rs1026916, and STAT4 rs11685878 associations were limited to women with low IA ancestry, and associations with JAK1 rs2780890, rs2254002, and rs310245 and STAT1 rs11887698 were observed among women with high IA ancestry. JAK2 (5 of 11 SNPs), SOCS2 (one of three SNPs), and STAT4 (2 of 20 SNPs) interacted with cigarette smoking status to alter breast cancer-specific mortality. SOCS2 (one of three SNPs) and all STAT3, STAT5A, and STAT5B SNPs significantly interacted with use of aspirin/NSAIDs to alter breast cancer-specific mortality. Genetic variation in the JAK/STAT/SOCS pathway was associated with breast cancer-specific mortality. The proportion of SNPs within a gene that significantly interacted with lifestyle factors lends support for the observed associations.

BACKGROUND: Over the past years, some members of the family of suppressor of cytokine signalling (SOCS) proteins have emerged as potential tumour suppressors. This study aimed at investigating the clinical significance of SOCS proteins in colorectal carcinoma (CRC).
METHODS: We integrated publicly available microarray expression data on CRC in humans, analysed the expression pattern of SOCSs and assessed the predictive power of SOCS2 and SOCS6 for diagnostic purposes by generating receiver operating characteristic curves. Using laser microdissected patient material we assessed SOCS expression on RNA and protein levels as well as their methylation status in an independent CRC patient cohort. Finally, we investigated the prognostic value of SOCS2 and SOCS6.
RESULTS: The meta-analysis as well as the independent patient cohort analysis reveal a stage-independent downregulation of SOCS2 and SOCS6 and identify both molecules as diagnostic biomarkers for CRC. We demonstrate a different methylation pattern within the SOCS2 promoter between tumour tissue and normal control tissue in 25% of CRC patients. Furthermore, early CRC stage patients with low expression of SOCS2 display significantly shorter disease-free survival.
CONCLUSIONS: Our data offers evidence that SOCS2 and SOCS6 levels are reduced in CRC and may serve as diagnostic biomarkers for CRC patients.

About 30% of patients with acute myeloid leukemia (AML) harbour mutations of the receptor tyrosine kinase FLT3, mostly internal tandem duplications (ITD) and point mutations of the second tyrosine kinase domain (TKD). It was the aim of this study to comprehensively analyze clinical and functional properties of various FLT3 mutants. In 672 normal karyotype AML patients FLT3-ITD, but not FLT3-TKD mutations were associated with a worse relapse free and overall survival in multivariate analysis. In paired diagnosis-relapse samples FLT3-ITD showed higher stability (70%) compared to FLT3-TKD (30%). In vitro, FLT3-ITD induced a strong activating phenotype in Ba/F3 cells. In contrast, FLT3-TKD mutations and other point mutations--including two novel mutations--showed a weaker but clear gain-of-function phenotype with gradual increase in proliferation and protection from apoptosis. The pro-proliferative capacity of the investigated FLT3 mutants was associated with cell surface expression and tyrosine 591 phosphorylation of the FLT3 receptor. Western blot experiments revealed STAT5 activation only in FLT3-ITD positive cell lines, in contrast to FLT3-non-ITD mutants, which displayed an enhanced signal of AKT and MAPK activation. Gene expression analysis revealed distinct difference between FLT3-ITD and FLT3-TKD for STAT5 target gene expression as well as deregulation of SOCS2, ENPP2, PRUNE2 and ART3. FLT3-ITD and FLT3 point mutations show a gain-of-function phenotype with distinct signalling properties in vitro. Although poor prognosis in AML is only associated with FLT3-ITD, all activating FLT3 mutations can contribute to leukemogenesis and are thus potential targets for therapeutic interventions.

Deregulated cytokine signaling is a characteristic feature of acute myeloid leukemia (AML), and expression signatures of cytokines and chemokines have been identified as a significant prognostic factor in this disease. Given this aberrant signaling, we hypothesized that expression of suppressor of cytokine signaling-2 (SOCS2), a negative regulator of cytokine signaling, might be altered in AML and could provide predictive information. Among 188 participants of the Children's Oncology Group AAML03P1 trial, SOCS2 mRNA levels varied > 6000-fold. Higher (> median) SOCS2 expression was associated with inferior overall (60 ± 10% vs. 75 ± 9%, p = 0.026) and event-free (44 ± 10% vs. 59 ± 10%, p = 0.031) survival. However, these differences were accounted for by higher prevalence of high-risk and lower prevalence of low-risk disease among patients with higher SOCS2 expression, limiting the clinical utility of SOCS2 as a predictive marker. It remains untested whether high SOCS2 expression identifies a subset of leukemias with deregulated cytokine signaling that could be amenable to therapeutic intervention.

Myelofibrosis is a myeloproliferative neoplasm that occurs de novo (primary myelofibrosis) or results from the progression of polycythemia vera or essential thrombocytemia (hereafter designated as secondary myelofibrosis or post-polycythemia vera/ essential thrombocythemia myelofibrosis). To progress in the understanding of myelofibrosis and to find molecular prognostic markers we studied 104 samples of primary and secondary myelofibrosis at chronic (n=68) and acute phases (n=12) from 80 patients, by using array-comparative genomic hybridization and sequencing of 23 genes (ASXL1, BMI1, CBL, DNMT3A, EZH2, IDH1/2, JAK2, K/NRAS, LNK, MPL, NF1, PPP1R16B, PTPN11, RCOR1, SF3B1, SOCS2, SRSF2, SUZ12, TET2, TP53, TRPS1). We found copy number aberrations in 54% of samples, often involving genes with a known or potential role in leukemogenesis. We show that cases carrying a del(20q), del(17) or del(12p) evolve in acute myeloid leukemia (P=0.03). We found that 88% of the cases were mutated, mainly in signaling pathway (JAK2 69%, NF1 6%) and epigenetic genes (ASXL1 26%, TET2 14%, EZH2 8%). Overall survival was poor in patients with more than one mutation (P=0.001) and in patients with JAK2/ASXL1 mutations (P=0.02). Our study highlights the heterogeneity of myelofibrosis, and points to several interesting copy number aberrations and genes with diagnostic and prognostic impact.

Persistent inflammation together with genetic/epigenetic aberrations is strongly associated with chronic Hepatitis B virus (HBV) infection-related hepatocarcinogenesis. Here, we investigated the alterations of the suppressor of cytokine signalling (SOCS) family genes in HBV-related hepatocellular carcinoma (HCC). A total of 116 patients with HCC were enrolled in this study. The methylation statuses of SOCS1-7 and CISH genes were quantitatively measured and clinicopathological significance of SOCS1 methylation was statistically analysed. The gene copy number variation was assayed by aCGH. Luciferase reporter assay and Western blot were used to detect the involvement of SOCS1 in p53 signalling. We found high frequencies of SOCS1 gene hypermethylation in both tumour (56.03%) and adjacent nontumour tissues (54.31%), but tumour tissues exhibited increased methylation intensity (24.01% vs 13.11%, P < 0.0001), particularly in patients with larger tumour size or cirrhosis background (P < 0.0001). In addition, the frequency and intensity of SOCS1 hypermethylation in tumour tissues were both significantly higher than those in nontumour tissues in male gender patients and in patients ≥45 years old (P = 0.0214 and P < 0.0001, P = 0.0232 and P < 0.0001, respectively). SOCS1 gene deletion was found in 8 of 25 aCGH assayed tumour specimens, which was associated with lower SOCS1 mRNA expression (P = 0.0448). Furthermore, ectopic SOCS1 overexpression could activate the p53 signalling pathway in HCC cell lines. Hypermethylation of SOCS2-7 and CISH genes was seldom found in HCC. Our results suggested that the gene loss and epigenetic silencing of SOCS1 were strongly associated with HBV-related HCC.

Suppressors of cytokine signaling (SOCS) proteins have been identified as negative feedback regulators of cytokine-mediated signaling in various tissues, and demonstrated to play critical roles in tumorigenesis and tumor development of different cancers. The involvement of SOCSs in human prostate cancer (PCa) has not been fully elucidated. Thus, the aim of this study is to investigate the expression patterns and the clinical significance of SOCSs in PCa. The expression changes of SOCSs at mRNA and protein levels in human PCa tissues compared with adjacent benign prostate tissues were, respectively, detected by using real-time quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) and immunohistochemistry analyses. The associations of SOCSs expression with clinicopathological features and clinical outcome of PCa patients were further statistically analyzed. Among SOCSs, both QRT-PCR and immunohistochemistry analyses found that SOCS2 expression was upregulated (at mRNA level: change ratio = 1.98, P = 0.031; at protein level: 5.12 ± 0.60 vs. 2.68 ± 0.37, P = 0.016) and SOCS6 expression was downregulated (at mRNA level: change ratio = -1.65, P = 0.008; at protein level: 3.03 ± 0.32 vs. 4.0.72 ± 0.39, P = 0.004) in PCa tissues compared with those in non-cancerous prostate tissues. In addition, the upregulation of SOCS2 in PCa tissues was correlated with the lower Gleason score (P < 0.001), the absence of metastasis (P < 0.001) and the negative PSA failure (P = 0.009); the downregulation of SOCS6 tended to be found in PCa tissues with the higher Gleason score (P = 0.016), the advanced pathological stage (P = 0.007), the positive metastasis (P = 0.020), and the positive PSA failure (P = 0.032). Furthermore, both univariate and multivariate analyses showed that the downregulation of SOCS2 was an independent predictor of shorter biochemical recurrence-free survival. Our data offer the convincing evidence for the first time that the dysregulation of SOCS2 and SOCS6 may be associated with the aggressive progression of PCa. SOCS2 may be potential markers for prognosis in PCa patients.

The suppressor of cytokine signaling 2 (SOCS2) is a member of the SOCS family of E3 ubiquitin ligases. SOCS2 is known to regulate signal transduction by cytokine receptors and receptor tyrosine kinases. The receptor tyrosine kinase FLT3 is of importance for proliferation, survival and differentiation of hematopoietic cells and is frequently mutated in acute myeloid leukemia. We observed that SOCS2 associates with activated FLT3 through phosphotyrosine residues 589 and 919, and co-localizes with FLT3 in the cell membrane. SOCS2 increases FLT3 ubiquitination and accelerates receptor degradation in proteasomes. SOCS2 negatively regulates FLT3 signaling by blocking activation of Erk 1/2 and STAT5. Furthermore, SOCS2 expression leads to a decrease in FLT3-ITD-mediated cell proliferation and colony formation. Thus, we suggest that SOCS2 associates with activated FLT3 and negatively regulates the FLT3 signaling pathways.