Suppressor of cytokine signaling 3 expression in anaplastic large cell lymphoma

Protective role of pretreatment with Anisodamine against sepsis-induced diaphragm atrophy via inhibiting JAK2/STAT3 pathway

There is an increasing tendency for sepsis patients to suffer from diaphragm atrophy as well as mortality. Therefore, reducing diaphragm atrophy could benefit sepsis patients' prognoses. Studies have shown that Anisodamine (Anis) can exert antioxidant effects when blows occur. However, the role of Anisodamine in diaphragm atrophy in sepsis patients has not been reported. Therefore, this study investigated the antioxidant effect of Anisodamine in sepsis-induced diaphragm atrophy and its mechanism. We used cecal ligation aspiration (CLP) to establish a mouse septic mode and stimulated the C2C12 myotube model with lipopolysaccharide (LPS). After treatment with Anisodamine, we measured the mice's bodyweight, diaphragm weight, fiber cross-sectional area and the diameter of C2C12 myotubes. The malondialdehyde (MDA) levels in the diaphragm were detected using the oxidative stress kit. The expression of MuRF1, Atrogin1 and JAK2/STAT3 signaling pathway components in the diaphragm and C2C12 myotubes was measured by RT-qPCR and Western blot. The mean fluorescence intensity of ROS in C2C12 myotubes was measured by flow cytometry. Meanwhile, we also measured the levels of Drp1 and Cytochrome C (Cyt-C) in vivo and in vitro by Western blot. Our study revealed that Anisodamine alleviated the reduction in diaphragmatic mass and the loss of diaphragmatic fiber cross-sectional area and attenuated the atrophy of the C2C12 myotubes by inhibiting the expression of E3 ubiquitin ligases. In addition, we observed that Anisodamine inhibited the JAK2/STAT3 signaling pathway and protects mitochondrial function. In conclusion, Anisodamine alleviates sepsis-induced diaphragm atrophy, and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway.

Obesity and Risk for Lymphoma: Possible Role of Leptin

Obesity, which is considered a pandemic due to its high prevalence, is a risk factor for many types of cancers, including lymphoma, through a variety of mechanisms by promoting an inflammatory state. Specifically, over the last few decades, obesity has been suggested not only to increase the risk of lymphoma but also to be associated with poor clinical outcomes and worse responses to different treatments for those diseases. Within the extensive range of proinflammatory mediators that adipose tissue releases, leptin has been demonstrated to be a key adipokine due to its pleotropic effects in many physiological systems and diseases. In this sense, different studies have analyzed leptin levels and leptin/leptin receptor expressions as a probable bridge between obesity and lymphomas. Since both obesity and lymphomas are prevalent pathophysiological conditions worldwide and their incidences have increased over the last few years, here we review the possible role of leptin as a promising proinflammatory mediator promoting lymphomas.

Requirement of DNMT1 to orchestrate epigenomic reprogramming for NPM-ALK-driven lymphomagenesis

Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T-cell-specific lymphoma model based on the human oncogenic nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK-positive tumors show a loss of associated methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis.

Cell of Origin and Immunologic Events in the Pathogenesis of Breast Implant-Associated Anaplastic Large-Cell Lymphoma

Breast implant–associated anaplastic large-cell lymphoma (BIA-ALCL) is a CD30-positive, anaplastic lymphoma kinase–negative T-cell lymphoma. Nearly all cases have been associated with textured implants. Most cases are of effusion-limited, indolent disease, with an excellent prognosis after implant and capsule removal. However, capsular invasion and tumor mass have a more aggressive course and a fatal outcome risk. This review summarizes the current knowledge on BIA-ALCL cell of origin and immunologic factors underlying its pathogenesis. Cytokine expression profiling of BIA-ALCL cell lines and clinical specimens reveals a predominantly type 17 helper T-cell (Th17)/Th1 signature, implicating this as its cell of origin. However, a Th2 allergic inflammatory response is suggested by the presence of IL-13, with infiltration of eosinophils and IgE-coated mast cells in clinical specimens of BIA-ALCL. The microenvironment-induced T-cell plasticity, a factor increasingly appreciated, may partially explain these divergent results. Mutations resulting in constitutive Janus kinase (JAK)–STAT activation have been detected and associated with BIA-ALCL pathogenesis in a small number of cases. One possible scenario is that an inflammatory microenvironment stimulates an immune response, followed by polyclonal expansion of Th17/Th1 cell subsets with release of inflammatory cytokines and chemokines and accumulation of seroma. JAK-STAT3 gain-of-function mutations within this pathway and others may subsequently lead to monoclonal T-cell proliferation and clinical BIA-ALCL. Current research suggests that therapies targeting JAK proteins warrant investigation in BIA-ALCL.

Programmed death-ligand 1 (PD-L1) characterization of circulating tumor cells (CTCs) in muscle invasive and metastatic bladder cancer patients

Background

While programmed death 1 (PD-1) and programmed death-ligand 1 (PD-L1) checkpoint inhibitors have activity in a proportion of patients with advanced bladder cancer, strongly predictive and prognostic biomarkers are still lacking. In this study, we evaluated PD-L1 protein expression on circulating tumor cells (CTCs) isolated from patients with muscle invasive (MIBC) and metastatic (mBCa) bladder cancer and explore the prognostic value of CTC PD-L1 expression on clinical outcomes.

Methods

Blood samples from 25 patients with MIBC or mBCa were collected at UCSF and shipped to Epic Sciences. All nucleated cells were subjected to immunofluorescent (IF) staining and CTC identification by fluorescent scanners using algorithmic analysis. Cytokeratin expressing (CK)⁺ and (CK)⁻CTCs (CD45⁻, intact nuclei, morphologically distinct from WBCs) were enumerated. A subset of patient samples underwent genetic characterization by fluorescence in situ hybridization (FISH) and copy number variation (CNV) analysis.

Results

CTCs were detected in 20/25 (80 %) patients, inclusive of CK⁺ CTCs (13/25, 52 %), CK⁻CTCs (14/25, 56 %), CK⁺ CTC Clusters (6/25, 24 %), and apoptotic CTCs (13/25, 52 %). Seven of 25 (28 %) patients had PD-L1⁺ CTCs; 4 of these patients had exclusively CK⁻/CD45⁻/PD-L1⁺ CTCs. A subset of CTCs were secondarily confirmed as bladder cancer via FISH and CNV analysis, which revealed marked genomic instability. Although this study was not powered to evaluate survival, exploratory analyses demonstrated that patients with high PD-L1⁺/CD45⁻CTC burden and low burden of apoptotic CTCs had worse overall survival.

Conclusions

CTCs are detectable in both MIBC and mBCa patients. PD-L1 expression is demonstrated in both CK⁺ and CK⁻CTCs in patients with mBCa, and genomic analysis of these cells supports their tumor origin. Here we demonstrate the ability to identify CTCs in patients with advanced bladder cancer through a minimally invasive process. This may have the potential to guide checkpoint inhibitor immune therapies that have been established to have activity, often with durable responses, in a proportion of these patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2758-3) contains supplementary material, which is available to authorized users.

Biomarkers Provide Clues to Early Events in the Pathogenesis of Breast Implant-Associated Anaplastic Large Cell Lymphoma

Almost 200 women worldwide have been diagnosed with breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). The unique location and specific lymphoma type strongly suggest an etio-pathologic link between breast implants and BIA-ALCL. It is postulated that chronic inflammation via bacterial infection may be an etiological factor. BIA-ALCL resembles primary cutaneous ALCL (pcALCL) in morphology, activated T-cell phenotype, and indolent clinical course. Gene expression array analysis, flow cytometry, and immunohistochemistry were used to study pcALCL and BIA-ALCL cell lines. Clinical samples were also studied to characterize transcription factor and cytokine profiles of tumor cells and surrounding lymphocytes. BIA-ALCL and pcALCL were found to have common expression of transcription factors SOCS3, JunB, SATB1, and a cytokine profile suggestive of a Th1 phenotype. Similar patterns were observed in a CD30+ cutaneous lymphoproliferative disorder (LPD). The patterns of cytokine and transcription factor expression suggest that BIA-ALCL is likely to arise from chronic bacterial antigen stimulation of T-cells. Further analysis of cytokine and transcription factor profiles may allow early detection and treatment of BIA-ALCL leading to better prognosis and survival. LEVEL OF EVIDENCE 5: Risk.

Endogenous transmembrane protein UT2 inhibits pSTAT3 and suppresses hematological malignancy

Regulation of STAT3 activation is critical for normal and malignant hematopoietic cell proliferation. Here, we have reported that the endogenous transmembrane protein upstream-of-mTORC2 (UT2) negatively regulates activation of STAT3. Specifically, we determined that UT2 interacts directly with GP130 and inhibits phosphorylation of STAT3 on tyrosine 705 (STAT3Y705). This reduces cytokine signaling including IL6 that is implicated in multiple myeloma and other hematopoietic malignancies. Modulation of UT2 resulted in inverse effects on animal survival in myeloma models. Samples from multiple myeloma patients also revealed a decreased copy number of UT2 and decreased expression of UT2 in genomic and transcriptomic analyses, respectively. Together, these studies identify a transmembrane protein that functions to negatively regulate cytokine signaling through GP130 and pSTAT3Y705 and is molecularly and mechanistically distinct from the suppressors of cytokine signaling (SOCS) family of genes. Moreover, this work provides evidence that perturbations of this activation-dampening molecule participate in hematologic malignancies and may serve as a key determinant of multiple myeloma pathophysiology. UT2 is a negative regulator shared across STAT3 and mTORC2 signaling cascades, functioning as a tumor suppressor in hematologic malignancies driven by those pathways.

Titanium dioxide nanoparticles augment allergic airway inflammation and Socs3 expression via NF-κB pathway in murine model of asthma

Titanium dioxide nanoparticles (nTiO2) previously considered to possess relatively low toxicity both in vitro and in vivo, although classified as possibly carcinogenic to humans. Also, their adjuvant potential has been reported to promote allergic sensitization and modulate immune responses. Previously, in OVA induced mouse model of asthma we found high expression of Socs3 and low expression of Stat3 and IL-6. However, a clear understanding regarding the signaling pathways associated with nTiO2 adjuvant effect in mouse model of asthma is lacking. In the present study we investigated the status of Stat3/IL-6 and Socs3 and their relationship with NF-κB, with nTiO2 as an adjuvant in mouse model of asthma. nTiO2 when administered with ovalbumin (OVA) during sensitization phase augmented airway hyper-responsiveness (AHR), biochemical markers of lung damage and a mixed Th2/Th1 dependent immune response. At the same time, we observed significant elevation in the levels of Stat3, Socs3, NF-κB, IL-6 and TNF-α. Furthermore, transient in vivo blocking of NF-κB by NF-κB p65 siRNA, downregulated the expression of Socs3, IL-6 and TNF-α. Our study, thus, shows that nTiO2 exacerbate the inflammatory responses in lungs of pre-sensitized allergic individuals and that these changes are regulated via NF-κB pathway.

The role of suppressors of cytokine signalling in human neoplasms

Suppressors of cytokine signalling 1-7 (SOCS1-7) and cytokine-inducible SH2-containing protein (CIS) are a group of intracellular proteins that are well known as JAK-STAT and several other signalling pathways negative feedback regulators. More recently several members have been identified as tumour suppressors and dysregulation of their biological roles in controlling cytokine and growth factor signalling may contribute to the development of many solid organ and haematological malignancies. This review explores their biological functions and their possible tumour suppressing role in human neoplasms.

Intrinsic and extrinsic mechanisms contribute to maintain the JAK/STAT pathway aberrantly activated in T-type large granular lymphocyte leukemia

The JAK/STAT pathway is altered in T-cell large granular lymphocytic leukemia. In all patients, leukemic LGLs display upregulation of phosphorylated STAT3 (P-STAT3) that activates expression of many antiapoptotic genes. To investigate the mechanisms maintaining STAT3 aberrantly phosphorylated using transcriptional protein and functional assays, we analyzed interleukin (IL)-6 and suppressor of cytokine signaling-3 (SOCS3), 2 key factors of the JAK/STAT pathway that induce and inhibit STAT3 activation, respectively. We showed that IL-6 was highly expressed and released by the patients' peripheral blood LGL-depleted population, accounting for a trans-signaling process. By neutralizing IL-6 or its specific receptor with specific antibodies, a significant reduction of P-STAT3 levels and, consequently, LGL survival was demonstrated. In addition, we found that SOCS3 was down-modulated in LGL and unresponsive to IL-6 stimulation. By treating neoplastic LGLs with a demethylating agent, IL-6-mediated SOCS3 expression was restored with consequent P-STAT3 and myeloid cell leukemia-1 down-modulation. Methylation in the SOCS3 promoter was not detectable, suggesting that an epigenetic inhibition mechanism occurs at a different site. Our data indicate that loss of the inhibitor SOCS3 cooperates with IL-6 to maintain JAK/STAT pathway activation, thus contributing to leukemic LGL survival, and suggest a role of demethylating agents in the treatment of this disorder.

Inhibition of DNA methyltransferase induces G2 cell cycle arrest and apoptosis in human colorectal cancer cells via inhibition of JAK2/STAT3/STAT5 signalling

DNA methyltransferase inhibitors (MTIs) have recently emerged as promising chemotherapeutic or preventive agents for cancer, despite their poorly characterized mechanisms of action. The present study shows that DNA methylation is integral to the regulation of SH2-containing protein tyrosine phosphatase 1 (SHP1) expression, but not for regulation of suppressors of cytokine signalling (SOCS)1 or SOCS3 in colorectal cancer (CRC) cells. SHP1 expression correlates with down-regulation of Janus kinase/signal transducers and activators of transcription (JAK2/STAT3/STAT5) signalling, which is mediated in part by tyrosine dephosphorylation events and modulation of the proteasome pathway. Up-regulation of SHP1 expression was achieved using a DNA MTI, 5-aza-2'-deoxycytidine (5-aza-dc), which also generated significant down-regulation of JAK2/STAT3/STAT5 signalling. We demonstrate that 5-aza-dc suppresses growth of CRC cells, and induces G2 cell cycle arrest and apoptosis through regulation of downstream targets of JAK2/STAT3/STAT5 signalling including Bcl-2, p16(ink4a), p21(waf1/cip1) and p27(kip1). Although 5-aza-dc did not significantly inhibit cell invasion, 5-aza-dc did down-regulate expression of focal adhesion kinase and vascular endothelial growth factor in CRC cells. Our results demonstrate that 5-aza-dc can induce SHP1 expression and inhibit JAK2/STAT3/STAT5 signalling. This study represents the first evidence towards establishing a mechanistic link between inhibition of JAK2/STAT3/STAT5 signalling and the anticancer action of 5-aza-dc in CRC cells that may lead to the use of MTIs as a therapeutic intervention for human colorectal cancer.

Gene expression profiling of isolated tumour cells from anaplastic large cell lymphomas: insights into its cellular origin, pathogenesis and relation to Hodgkin lymphoma

Anaplastic large cell lymphoma (ALCL) is a main type of T-cell lymphomas and comprises three distinct entities: systemic anaplastic lymphoma kinase (ALK) positive, systemic ALK(-) and cutaneous ALK(-) ALCL (cALCL). Little is known about their pathogenesis and their cellular origin, and morphological and immunophenotypical overlap exists between ALK(-) ALCL and classical Hodgkin lymphoma (cHL). We conducted gene expression profiling of microdissected lymphoma cells of five ALK(+) and four ALK(-) systemic ALCL, seven cALCL and sixteen cHL, and of eight subsets of normal T and NK cells. The analysis supports a derivation of ALCL from activated T cells, but the lymphoma cells acquired a gene expression pattern hampering an assignment to a CD4(+), CD8(+) or CD30(+) T-cell origin. Indeed, ALCL display a down-modulation of many T-cell characteristic molecules. All ALCL types show significant expression of NFkappaB target genes and upregulation of genes involved in oncogenesis (e.g. EZH2). Surprisingly, few genes are differentially expressed between systemic and cALCL despite their different clinical behaviour, and between ALK(-) ALCL and cHL despite their different cellular origin. ALK(+) ALCL are characterized by expression of genes regulated by pathways constitutively activated by ALK. This study provides multiple novel insights into the molecular biology and pathogenesis of ALCL.

Loss of protein inhibitors of activated STAT-3 expression in glioblastoma multiforme tumors: implications for STAT-3 activation and gene expression

PURPOSE

STATs activate transcription in response to numerous cytokines, controlling proliferation, gene expression, and apoptosis. Aberrant activation of STAT proteins, particularly STAT-3, is implicated in the pathogenesis of many cancers, including GBM, by promoting cell cycle progression, stimulating angiogenesis, and impairing tumor immune surveillance. Little is known about the endogenous STAT inhibitors, the PIAS proteins, in human malignancies. The objective of this study was to examine the expression of STAT-3 and its negative regulator, PIAS3, in human tissue samples from control and GBM brains.

EXPERIMENTAL DESIGN

Control and GBM human tissues were analyzed by immunoblotting and immunohistochemistry to determine the activation status of STAT-3 and expression of the PIAS3 protein. The functional consequence of PIAS3 inhibition by small interfering RNA or PIAS3 overexpression in GBM cells was determined by examining cell proliferation, STAT-3 transcriptional activity, and STAT-3 target gene expression. This was accomplished using [(3)H]TdR incorporation, STAT-3 dominant-negative constructs, reverse transcription-PCR, and immunoblotting.

RESULTS AND CONCLUSIONS

STAT-3 activation, as assessed by tyrosine and serine phosphorylation, was elevated in GBM tissue compared with control tissue. Interestingly, we observed expression of PIAS3 in control tissue, whereas PIAS3 protein expression in GBM tissue was greatly reduced. Inhibition of PIAS3 resulted in enhanced glioblastoma cellular proliferation. Conversely, PIAS3 overexpression inhibited STAT-3 transcriptional activity, expression of STAT-3-regulated genes, and cell proliferation. We propose that the loss of PIAS3 in GBM contributes to enhanced STAT-3 transcriptional activity and subsequent cell proliferation.

Signal transducer and activator of transcription-3: a molecular hub for signaling pathways in gliomas

Glioblastoma is the most common and severe primary brain tumor in adults. Its aggressive and infiltrative nature renders the current therapeutics of surgical resection, radiation, and chemotherapy relatively ineffective. Accordingly, recent research has focused on the elucidation of various signal transduction pathways in glioblastoma, particularly aberrant activation. This review focuses on the signal transducer and activator of transcription-3 (STAT-3) signal transduction pathway in the context of this devastating tumor. STAT-3 is aberrantly activated in human glioblastoma tissues, and this activation is implicated in controlling critical cellular events thought to be involved in gliomagenesis, such as cell cycle progression, apoptosis, angiogenesis, and immune evasion. There are no reports of gain-of-function mutations in glioblastoma; rather, the activation of STAT-3 is thought to be a consequence of either dysregulation of upstream kinases or loss of endogenous inhibitors. This review provides detailed insight into the multiple mechanisms of STAT-3 activation in glioblastoma, as well as describing endogenous and chemical inhibitors of this pathway and their clinical significance. In glioblastoma, STAT-3 acts a molecular hub to link extracellular signals to transcriptional control of proliferation, cell cycle progression, and immune evasion. Because STAT-3 plays this central role in glioblastoma signal transduction, it has significant potential as a therapeutic target.

SOCS regulation of the JAK/STAT signalling pathway

The suppressor of cytokine signalling (SOCS) proteins were, as their name suggests, first described as inhibitors of cytokine signalling. While their actions clearly now extend to other intracellular pathways, they remain key negative regulators of cytokine and growth factor signalling. In this review we focus on the mechanics of SOCS action and the complexities of the mouse models that have underpinned our current understanding of SOCS biology.

Dicarbonyl/L-xylulose reductase: a potential biomarker identified by laser-capture microdissection-micro serial analysis of gene expression of human prostate adenocarcinoma

To identify genes involved in prostate carcinogenesis, we used laser-capture microdissection-micro serial analysis of gene expression to construct libraries of paired cancer and normal cells from human tissue samples. After computational comparison of the two libraries, we identified dicarbonyl/l-xylulose reductase (DCXR), an enzyme that catalyzes alpha-dicarbonyl and l-xylulose, as being significantly up-regulated in prostate cancer cells. The specificity of DCXR up-regulation for prostate cancer tissues was confirmed by quantitative real-time reverse transcriptase-PCR, virtual Northern blot, and Western blot analyses. Furthermore, DCXR expression at the protein level was assessed using fresh-frozen tissues and a tissue microarray consisting of 46 cases of organ-confined early-stage prostate cancer and 29 cases of chemohormonally treated prostate cancer. In most normal prostate epithelial cells, DCXR was expressed at low levels and was localized predominantly in the cytoplasmic membrane. In contrast, in virtually all grades of early-stage prostate cancer and in all chemohormonally treated cases, DCXR was strikingly overexpressed and was localized predominantly in the cytoplasm and nucleus. In all samples, the stromal cells were completely devoid of DCXR expression. Based on these findings, we suggest that DCXR overexpression has the potential to be an additional useful biomarker for prostate cancer.

Reciprocal regulation of SOCS 1 and SOCS3 enhances resistance to ionizing radiation in glioblastoma multiforme

PURPOSE

The expression of suppressors of cytokine signaling 1 (SOCS1) and SOCS3 genes is dysregulated in several solid tumors, causing aberrant activation of cell growth and survival signaling pathways. In this study, we analyzed SOCS1 and SOCS3 gene expression in glioblastoma multiforme (GBM) and studied the role of each protein in GBM cell signaling and radiation resistance.

EXPERIMENTAL DESIGN

SOCS1 and SOCS3 gene expression was analyzed in 10 GBM cell lines by reverse transcription-PCR and Western blotting. SOCS3 expression was also studied in 12 primary GBM tissues by immunohistochemistry. The methylation status of the SOCS1 and SOCS3 loci was determined by methylation-specific PCR. Extracellular signal-regulated kinase (ERK)-mitogen-activated protein kinase (MAPK) activation in GBM cell lines overexpressing SOCS1 or lacking SOCS3 was determined by phosphorylated-specific Western blotting. Radiation responses in SOCS1-positive and SOCS3-deficient GBM cell lines and fibroblasts from wild-type and SOCS1 or SOCS3 knockout mice were studied in a clonogenic survival assay.

RESULTS

All GBM cell lines tested lacked SOCS1 expression, whereas GBM cell lines and primary GBM tumor samples constitutively expressed SOCS3. SOCS1 gene repression was linked to hypermethylation of the SOCS1 genetic locus in GBM cells. Reintroduction of SOCS1 or blocking SOCS3 expression sensitized cells to radiation and decreased the levels of activated ERK MAPKs in GBM cells.

CONCLUSIONS

SOCS1 and SOCS3 are aberrantly expressed in GBM cell lines and primary tissues. Altered SOCS gene expression leads to increased cell signaling through the ERK-MAPK pathway and may play a role in disease pathogenesis by enhancing GBM radioresistance.

Pathobiology of ALK+ anaplastic large-cell lymphoma

Anaplastic large-cell lymphoma (ALCL) was initially recognized on the basis of morphologic features and the consistent expression of CD30. It then became evident that the majority of these tumors are derived from lymphoid cells of T or null immunophenotype. The subsequent finding that t(2;5)(p23;q35) occurs in 40% to 60% of ALCL patients established a distinct clinicopathologic entity. This chromosomal translocation induces the formation of the chimeric protein nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), which possesses significant oncogenic potential resulting from the constitutive activation of the tyrosine kinase ALK. In addition to its specific pathophysiologic events, NPM-ALK-expressing lymphoma presents with consistent clinical manifestations. Only 13 years after the identification of NPM-ALK, tremendous progress has been made in our understanding of this molecule because of the relentless efforts of multiple investigators who have dissected its biologic roles using in vitro and in vivo experimental models. Several upstream modulators, cross-reacting oncogenes, and downstream effectors of NPM-ALK have been identified and characterized. Understanding these interacting oncogenic systems is expected to facilitate the design of new therapeutic strategies and agents. In this review, we briefly discuss ALCL and focus on NPM-ALK.

Constitutive Suppressor of Cytokine Signaling 3 Expression Confers a Growth Advantage to a Human Melanoma Cell Line

The growth of melanocytes and many early stage melanoma cells can be inhibited by cytokines, whereas late stage melanoma cells have often been reported to be "multi-cytokine-resistant." Here, we analyzed the melanoma cell line 1286, resistant towards the growth-inhibitory effects of interleukin 6 (IL-6), and oncostatin M (OSM), to better understand the mechanisms underlying cytokine resistance. Although the relevant receptors gp130 and OSMR are expressed at the cell surface of these cells, cytokine stimulation hardly led to the activation of Janus kinase 1 and signal transducer and activator of transcription (STAT)3 and STAT1. We found a high-level constitutive expression of suppressors of cytokine signaling 3 (SOCS3) that did not further increase after cytokine treatment. Importantly, upon suppression of SOCS3 by short interfering RNA, cells became susceptible towards OSM and IL-6: they showed an enhanced STAT3 phosphorylation and a dramatically increased STAT1 phosphorylation. Moreover, suppression of SOCS3 rendered 1286 cells sensitive to the antiproliferative action of IL-6 and OSM, but not of IFN-alpha. Interestingly, SOCS3-short interfering RNA treatment also increased the growth-inhibitory effect in cytokine-sensitive WM239 cells expressing SOCS3 in an inducible way. Thus, SOCS3 expression confers a growth advantage to these cell lines. Constitutive SOCS3 mRNA expression, although at lower levels than in 1286 cells, was found in nine additional human melanoma cell lines and in normal human melanocytes, although at the protein level, SOCS3 expression was marginal at best. However, in situ analysis of human melanoma specimens revealed SOCS3 immunoreactivity in 3 out of 10 samples, suggesting that in vivo SOCS3 may possibly play a role in IL-6 resistance in at least a fraction of tumors.

c-Jun Expression and Activation are Restricted to CD30+ Lymphoproliferative Disorders

Cellular Jun (c-Jun), a member of the JUN family, is an activator protein-1 transcription factor involved in cell differentiation, proliferation, and apoptosis that can be activated by phosphorylation at serine-73 and -63 residues. Using tissue microarrays and immunohistochemistry, we investigated c-Jun expression and serine-73 phosphorylation in 112 CD30 lymphomas and 232 CD30 lymphomas of B- or T-cell lineage, and 24 cases of lymphomatoid papulosis. c-Jun was expressed exclusively by CD30 lymphoproliferative disorders including 41/41 (100%) classical Hodgkin lymphoma (cHL), 20/23 (87%) anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL), 18/26 (69%) ALK- ALCL, 5/9 (56%) primary cutaneous ALCL, 4/11 (36%) CD30 diffuse large B-cell lymphoma (DLBCL), and 11/24 (46%) cases of lymphomatoid papulosis. The percentage of c-Jun-positive tumor cells was highest in cHL and ALCL (P=0.002). In contrast, all CD30 lymphomas, including nodular lymphocyte predominant HL and CD30 non-Hodgkin lymphomas of B- or T-cell lineage were negative for c-Jun. Serine-73 phosphorylated c-Jun (p-c-Jun), the activated form of c-Jun, was expressed more frequently and at a higher level in cHL and ALK+ ALCL than other CD30 tumors. The percentage of p-c-Jun-positive tumor cells correlated significantly with the percentage of total c-Jun-positive cells (P<0.0001), suggesting that activated c-Jun positively regulates total c-Jun levels in CD30 lymphomas through a well-established positive feedback loop. We conclude that CD30 lymphomas are characterized by common patterns of c-Jun expression and activation suggesting a potential role of c-Jun in the pathogenesis of these tumors.

Inhibition of ALK enzymatic activity in T-cell lymphoma cells induces apoptosis and suppresses proliferation and STAT3 phosphorylation independently of Jak3

Aberrant expression of the ALK tyrosine kinase as a chimeric protein with nucleophosmin (NPM) and other partners plays a key role in malignant cell transformation of T-lymphocytes and other cells. Here we report that two small-molecule, structurally related, quinazoline-type compounds, WHI-131 and WHI-154, directly inhibit enzymatic activity of NPM/ALK as demonstrated by in vitro kinase assays using a synthetic tyrosine-rich oligopeptide and the kinase itself as the substrates. The inhibition of NPM/ALK activity resulted in malignant T cells in suppression of their growth, induction of apoptosis and inhibition of tyrosine phosphorylation of STAT3, the key effector of the NPM/ALK-induced oncogenesis. We also show that the STAT3 tyrosine phosphorylation is mediated in the malignant T cells by NPM/ALK independently of Jak3 kinase as evidenced by the presence of STAT3 phosphorylation in the NPM/ALK-transfected BaF3 cells that do not express detectable Jak3 and in the NPM/ALK-positive malignant T cells with either Jak3 activity impaired by a pan-Jak or Jak3-selective inhibitor or Jak3 expression abrogated by Jak3 siRNA. The above results represent the 'proof-of-principle' experiments with regard to the ALK enzymatic activity as an attractive therapeutic target in T-cell lymphomas and other malignancies that express the kinase in an active form.

JunB expression is a common feature of CD30+ lymphomas and lymphomatoid papulosis

JunB is a member of the Jun family of proteins that are components of the AP-1 transcription factor complex. AP-1 is involved in cell proliferation and apoptosis. Recent evidence suggests that Hodgkin and Reed-Sternberg cells overexpress JunB and that JunB facilitates constitutive CD30 expression by binding to an AP-1 site in the CD30 promoter. In this study we surveyed JunB expression in a variety of CD30+ lymphoma types including 42 cases of anaplastic large cell lymphoma, 36 classical Hodgkin lymphoma, 15 cutaneous anaplastic large cell lymphoma, and 11 CD30+ diffuse large B-cell lymphoma. In addition, seven cases of nodular lymphocyte-predominant Hodgkin lymphoma and 42 diffuse large B-cell lymphoma, known to be CD30-, were analyzed. JunB expression was assessed using tissue microarrays, immunohistochemistry and a monoclonal antibody specific for JunB. Expression of JunB was observed in 41 of 42 cases of anaplastic large cell lymphoma, including all 21 cases positive for anaplastic lymphoma kinase and 20 of 21 (95%) negative for anaplastic lymphoma kinase. JunB was also expressed in all cases of classical Hodgkin lymphoma, cutaneous anaplastic large cell lymphoma and CD30+ diffuse large B-cell lymphoma, and in lymphomatoid papulosis. By contrast, all nodular lymphocyte-predominant Hodgkin lymphomas and diffuse large B-cell lymphomas that were CD30- were also JunB-. We conclude that JunB is expressed in virtually all CD30+ lymphomas and is a potential target for experimental therapy in patients with these tumors.