Mitogenic signals initiated via interleukin-6 receptor complexes in cooperation with other transmembrane molecules in myelomas

Network-Based Analysis of Bortezomib Pharmacodynamic Heterogeneity in Multiple Myeloma Cells

The objective of this study is to evaluate the heterogeneity in pharmacodynamic response in four in vitro multiple myeloma cell lines to treatment with bortezomib, and to assess whether such differences are associated with drug-induced intracellular signaling protein dynamics identified via a logic-based network modeling approach. The in vitro pharmacodynamic-efficacy of bortezomib was evaluated through concentration-effect and cell proliferation dynamical studies in U266, RPMI8226, MM.1S, and NCI-H929 myeloma cell lines. A Boolean logic-based network model incorporating intracellular protein signaling pathways relevant to myeloma cell growth, proliferation, and apoptosis was developed based on information available in the literature and used to identify key proteins regulating bortezomib pharmacodynamics. The time-course of network-identified proteins was measured using the MAGPIX protein assay system. Traditional pharmacodynamic modeling endpoints revealed variable responses of the cell lines to bortezomib treatment, classifying cell lines as more sensitive (MM.1S and NCI-H929) and less sensitive (U266 and RPMI8226). Network centrality and model reduction identified key proteins (e.g., phosphorylated nuclear factor-κB, phosphorylated protein kinase B, phosphorylated mechanistic target of rapamycin, Bcl-2, phosphorylated c-Jun N-terminal kinase, phosphorylated p53, p21, phosphorylated Bcl-2-associated death promoter, caspase 8, and caspase 9) that govern bortezomib pharmacodynamics. The corresponding relative expression (normalized to 0-hour untreated-control cells) of proteins demonstrated a greater magnitude and earlier onset of stimulation/inhibition in cells more sensitive (MM.1S and NCI-H929) to bortezomib-induced cell death at 20 nM, relative to the less sensitive cells (U266 and RPMI8226). Overall, differences in intracellular signaling appear to be associated with bortezomib pharmacodynamic heterogeneity, and key proteins may be potential biomarkers to evaluate bortezomib responses.

The prohibitin protein complex promotes mitochondrial stabilization and cell survival in hematologic malignancies

Prohibitins (PHB1 and PHB2) have been proposed to play important roles in cancer development and progression, however their oncogenic mechanism of action has not been fully elucidated. Previously, we showed that the PHB1 and PHB2 protein complex is required for mitochondrial homeostasis and survival of normal human lymphocytes. In this study, novel evidence is provided that indicates mitochondrial prohibitins are overexpressed in hematologic tumor cells and promote cell survival under conditions of oxidative stress. Immunofluorescent confocal microscopy revealed both proteins to be primarily confined to mitochondria in primary patient lymphoid and myeloid tumor cells and tumor cell lines, including Kit225 cells. Subsequently, siRNA-mediated knockdown of PHB1 and PHB2 in Kit225 cells significantly enhanced sensitivity to H₂O₂-induced cell death, suggesting a protective or anti-apoptotic function in hematologic malignancies. Indeed, PHB1 and PHB2 protein levels were significantly higher in tumor cells isolated from leukemia and lymphoma patients compared to PBMCs from healthy donors. These findings suggest that PHB1 and PHB2 are upregulated during tumorigenesis to maintain mitochondrial integrity and therefore may serve as novel biomarkers and molecular targets for therapeutic intervention in certain types of hematologic malignancies.

MDX-1097 induces antibody-dependent cellular cytotoxicity against kappa multiple myeloma cells and its activity is augmented by lenalidomide

MDX-1097 is an antibody specific for a unique B cell antigen called kappa myeloma antigen (KMA) that consists of cell membrane-associated free kappa light chain (κFLC). KMA was detected on kappa human multiple myeloma cell lines (κHMCLs), on plasma cells (PCs) from kappa multiple myeloma (κMM) patients and on κPC dyscrasia tissue cryosections. In primary κMM samples, KMA was present on CD38+ cells that were CD138 and CD45 positive and/or negative. MDX-1097 exhibited a higher affinity for KMA compared to κFLC and the latter did not abrogate binding to KMA. MDX-1097-mediated antibody-dependent cellular cytotoxicity (ADCC) and in vitro exposure of target cells to the immunomodulatory drug lenalidomide resulted in increased KMA expression and ADCC. Also, in vitro exposure of peripheral blood mononuclear cells (PBMCs) to lenalidomide enhanced MDX-1097-mediated ADCC. PBMCs obtained from myeloma patients after lenalidomide therapy elicited significantly higher levels of MDX-1097-mediated ADCC than cells obtained prior to lenalidomide treatment. These data establish KMA as a relevant cell surface antigen on MM cells that can be targeted by MDX-1097. The ADCC-inducing capacity of MDX-1097 and its potentiation by lenalidomide provide a powerful rationale for clinical evaluation of MDX-1097 alone and in combination with lenalidomide.

Molecular events underlying interleukin-6 independence in a subclone of the CMA-03 multiple myeloma cell line

We explored the molecular mechanisms involved in the establishement of CMA-03/06, an IL-6-independent variant of the multiple myeloma cell line CMA-03 previously generated in our Institution. CMA-03/06 cells grow in the absence of IL-6 with a doubling time comparable with that of CMA-03 cells; neither the addition of IL6 (IL-6) to the culture medium nor co-culture with multipotent mesenchymal stromal cells increases the proliferation rate, although they maintain the responsiveness to IL-6 stimulation as demonstrated by STAT1, STAT3, and STAT5 induction. IL-6 independence of CMA-03/06 cells is not apparently due to the development of an autocrine IL-6 loop, nor to the observed moderate constitutive activation of STAT5 and STAT3, since STAT3 silencing does not affect cell viability or proliferation. When compared to the parental cell line, CMA-03/06 cells showed an activated pattern of the NF-κB pathway. This finding is supported by gene expression profiling (GEP) analysis identifying an appreciable fraction of modulated genes (28/308) in the CMA-03/06 subclone reported to be involved in this pathway. Furthermore, although more resistant to apoptotic stimuli compared to the parental cell line, CMA-03/06 cells display a higher sensibility to NF-κB inhibition induced by bortezomib. Finally, GEP analysis suggests an involvement of a number of cytokines, which might contribute to IL-6 independence of CMA-03/06 by stimulating growth and antiapoptotic processes. In conclusion, the parental cell-line CMA-03 and its variant CMA-03/06 represent a suitable model to further investigate molecular mechanisms involved in the IL-6-independent growth of myeloma cells.

An integrin-targeted, pan-isoform, phosphoinositide-3 kinase inhibitor, SF1126, has activity against multiple myeloma in vivo

PURPOSE

Multiple reports point to an important role for the phosphoinositide-3 kinase (PI3K) and AKT signaling pathways in tumor survival and chemoresistance in multiple myeloma (MM). The goals of our study were: (1) to generate the preclinical results necessary to justify a Phase I clinical trial of SF1126 in hematopoietic malignancies including MM and (2) to begin combining pan-PI3K inhibitors with other agents to augment antitumor activity of this class of agent in preparation for combination therapy in Phase I/II trials.

METHODS

We determined the in vitro activity of SF1126 with 16 human MM cell lines. In vivo tumor growth suppression was determined with human myeloma (MM.1R) xenografts in athymic mice. In addition, we provide evidence that SF1126 has pharmacodynamic activity in the treatment of patients with MM.

RESULTS

SF1126 was cytotoxic to all tested MM lines, and potency was augmented by the addition of bortezomib. SF1126 affected MM.1R cell line signaling in vitro, inhibiting phospho-AKT, phospho-ERK, and the hypoxic stabilization of HIF1α. Tumor growth was 94 % inhibited, with a marked decrease in both cellular proliferation (PCNA immunostaining) and angiogenesis (tumor microvessel density via CD31 immunostaining). Our clinical results demonstrate pharmacodynamic knockdown of p-AKT in primary patient-derived MM tumor cells in vivo.

CONCLUSIONS

Our results establish three important points: (1) SF1126, a pan-PI3K inhibitor has potent antitumor activity against MM in vitro and in vivo, (2) SF1126 displays augmented antimyeloma activity when combined with proteasome inhibitor, bortezomib/Velcade(®), and (3) SF1126 blocks the IGF-1-induced activation of AKT in primary MM tumor cells isolated from SF1126-treated patients The results support the ongoing early Phase I clinical trial in MM and suggest a future Phase I trial in combination with bortezomib in hematopoietic malignancies.

Cardiotrophin-1 reduces ischemia/reperfusion injury during liver transplant

BACKGROUND

Orthotopic liver transplantation (OLT) is currently the elective treatment for advanced liver cirrhosis and acute liver failure. Ischemia/reperfusion damage may jeopardize graft function during the postoperative period. Cardiotrophin-1 (CT-1) has demonstrated cytoprotective properties in different experimental models of liver injury. There is no evidence to demonstrate its potential use in the prevention of the ischemia/reperfusion injury that occurs during OLT. The present study is the first report to show that the administration of CT-1 to donors would benefit the outcome of OLT.

MATERIALS AND METHODS

We tested the cytoprotective effect of CT-1 administered to the donor prior to OLT in an experimental pig model. Hemodynamic changes, hepatic histology, cell death parameters, activation of cell signaling pathways, oxidative and nitrosative stress, and animal survival were analyzed.

RESULTS

Our data showed that CT-1 administration to donors increased animal survival, improved cardiac and respiratory functions, and reduced hepatocellular injury as well as oxidative and nitrosative stress. These beneficial effects, related to the activation of AKT, ERK, and STAT3, reduced caspase-3 activity and diminished IL-1β and TNF-α expression together with IL-6 upregulation in liver tissue.

CONCLUSIONS

The administration of CT-1 to donors reduced ischemia/reperfusion injury and improved survival in an experimental pig model of OLT.

Multifaceted link between cancer and inflammation

Increasing evidence from epidemiological, preclinical and clinical studies suggests that dysregulated inflammatory response plays a pivotal role in a multitude of chronic ailments including cancer. The molecular mechanism(s) by which chronic inflammation drives cancer initiation and promotion include increased production of pro-inflammatory mediators, such as cytokines, chemokines, reactive oxygen intermediates, increased expression of oncogenes, COX-2 (cyclo-oxygenase-2), 5-LOX (5-lipoxygenase) and MMPs (matrix metalloproteinases), and pro-inflammatory transcription factors such as NF-κB (nuclear factor κB), STAT3 (signal transducer and activator of transcription 3), AP-1 (activator protein 1) and HIF-1α (hypoxia-inducible factor 1α) that mediate tumour cell proliferation, transformation, metastasis, survival, invasion, angiogenesis, chemoresistance and radioresistance. These inflammation-associated molecules are activated by a number of environmental and lifestyle-related factors including infectious agents, tobacco, stress, diet, obesity and alcohol, which together are thought to drive as much as 90% of all cancers. The present review will focus primarily on the role of various inflammatory intermediates responsible for tumour initiation and progression, and discuss in detail the critical link between inflammation and cancer.

Metastatic cells can escape the proapoptotic effects of TNF-α through increased autocrine IL-6/STAT3 signaling

The liver is a common site for cancer metastases in which the entrance of tumor cells has been shown to trigger a rapid inflammatory response. In considering how an inflammatory response may affect metastatic colonization in this setting, we hypothesized that tumor cells may acquire resistance to the proapoptotic and tumoricidal effects of TNF-α, a cytokine that is elevated in a proinflammatory tissue microenvironment. In this study, we investigated molecular mechanisms by which such resistance may emerge using tumor cells in which the overexpression of the type I insulin-like growth factor receptor (IGF-IR) enhanced the inflammatory and metastatic capacities of poorly metastatic cells in the liver. Mechanistic investigations in vitro revealed that IGF-IR overexpression increased cell survival in the presence of high levels of TNF-α, in a manner associated with increased autocrine production of interleukin-6 (IL)-6. In turn, tumor cell-derived IL-6 induced gp130 and IL-6R-dependent activation of STAT3, leading to reduced caspase-3 activation and apoptosis. We found that IL-6 production and cell death resistance were dose dependent with increasing TNF-α levels. In addition, RNA interference-mediated knockdown of either IL-6 or gp130 that established a blockade to autocrine STAT3 induction was sufficient to abolish the prosurvival effect of TNF-α and to inhibit liver metastasis. Taken together, our findings define an IGF-IR-mediated mechanism of cancer cell survival that is critical for metastatic colonization of the liver.

Flow cytometric immunophenotypic characteristics of 36 cases of plasma cell leukemia

Prospective flow cytometric analysis of antigens expression on bone marrow and peripheral blood plasma cells of 36 plasma cell leukemia (PCL) patients enabled to establish the following immunophenotype of leukemic plasma cell: CD38(++), CD138(+), CD54(+), CD49d(+), CD29(+), CD44(+), CD126(+), CD19(-), CD45(-). In one-third of patients PCL cells express CD56, CD71 and CD117. Expression of CD54 on plasma cells was higher as compared to expression of adhesion molecules CD11a, CD18 and CD11b (p<0.01). Expression of CD18, CD11a, CD11b was lower on bone marrow and higher on peripheral blood cells. In conclusion, impaired expression of adhesion molecules such as CD11a/CD18 or CD56 may explain hematogenic dissemination characterizing PCL.

Reversible phosphorylation in haematological malignancies: potential role for protein tyrosine phosphatases in treatment?

Most aspects of leukocyte physiology are under the control of reversible tyrosine phosphorylation. It is clear that excessive phosphorylation of signal transduction elements is a pivotal element of many different pathologies including haematological malignancies and accordingly, strategies that target such phosphorylation have clinically been proven highly successful for treatment of multiple types of leukemias and lymphomas. Cellular phosphorylation status is dependent on the resultant activity of kinases and phosphatases. The cell biology of the former is now well understood; for most cellular phosphoproteins we now know the kinases responsible for their phosphorylation and we understand the principles of their aberrant activity in disease. With respect to phosphatases, however, our knowledge is much patchier. Although the sequences of whole genomes allow us to identify phosphatases using in silico methodology, whereas transcription profiling allows us to understand how phosphatase expression is regulated during disease, most functional questions as to substrate specificity, dynamic regulation of phosphatase activity and potential for therapeutic intervention are still to a large degree open. Nevertheless, recent studies have allowed us to make meaningful statements on the role of tyrosine phosphatase activity in the three major signaling pathways that are commonly affected in leukemias, i.e. the Ras-Raf-ERK1/2, the Jak-STAT and the PI3K-PKB-mTOR pathways. Lessons learned from these pathways may well be applicable elsewhere in leukocyte biology as well.

Cell cycle inhibition without disruption of neurogenesis is a strategy for treatment of central nervous system diseases

Classically, the cell cycle is regarded as the process leading to cellular proliferation. However, increasing evidence over the last decade supports the notion that neuronal cell cycle re-entry results in post-mitotic death. A mature neuron that re-enters the cell cycle can neither advance to a new G0 quiescent state nor revert to its earlier G0 state. This presents a critical dilemma to the neuron from which death may be an unavoidable but necessary outcome for adult neurons attempting to complete the cell cycle. In contrast, tumor cells that undergo aberrant cell cycle re-entry divide and can survive. Thus, cell cycle inhibition strategies are of interest in cancer treatment but may also represent an important means of protecting neurons. In this review, we put forth the concept of the "expanded cell cycle" and summarize the cell cycle proteins, signal transduction events and mitogenic molecules that can drive a neuron into the cell cycle in various CNS diseases. We also discuss the pharmacological approaches that interfere with the mitogenic pathways and prevent mature neurons from attempting cell cycle re-entry, protecting them from cell death. Lastly, future attempts at blocking the cell cycle to rescue mature neurons from injury should be designed so as to not block normal neurogenesis.

A comparison of cytokine production in 2-dimensional and 3-dimensional cultures of bone marrow stromal cells of multiple myeloma patients in response to RPMI8226 myeloma cells

We examined cytokine production by bone marrow stromal cells (BMSCs) of patients with multiple myeloma (MM) in response to contact with myeloma RPMI8226 cells in standard 2-dimensional (2D) cultures and in 3-dimensional (3D) cultures on a gelatine sponge scaffold. It was detected that BMSCs in the 3D cultures produced more IL-11 and HGF and less IL-10 than in the 2D cultures. Moreover, RPMI8226 cells after contact with BMSCs in 3D cultures produced more sIL-6R than in the classic 2D cultures. We concluded that 3D cultures of BMSCs with myeloma cells offered a promising model for in vitro examination of interactions between myeloma cells and the bone marrow stroma and for examination of potent antimyeloma agents.

New targets and treatments in multiple myeloma: Src family kinases as central regulators of disease progression

Multiple myeloma is a malignant condition that most commonly occurs in the seventh decade of life. Recent improvements in treatment may result in a more favourable outlook for recently diagnosed patients. Multiple myeloma is an incurable clonal B-cell malignancy, which is initially responsive to conventional chemotherapy; one-third of the patients achieve complete remission but multidrug resistance eventually develops. Although autologous stem cell transplantation remains an important option, many older patients are less tolerant to the toxicity associated with conditioning treatment, as well as being intrinsically less likely to do well after transplantation. Most patients eventually relapse with or without transplantation, and salvage therapy is only moderately effective. Thalidomide and subsequently, lenalidomide and bortezomib, have demonstrated improved outcomes for these patients, as well as proving efficacious in front-line regimens. A deeper understanding of the molecular mechanisms underlying multiple myeloma has given rise to novel targeted approaches. This review will focus in particular on Src-dependent signalling pathways, reflecting the expanding realisation of the critical and ubiquitous role of Src family kinases (SFKs) in normal and abnormal hematopoiesis.

Validation of PDGFRbeta and c-Src tyrosine kinases as tumor/vessel targets in patients with multiple myeloma: preclinical efficacy of the novel, orally available inhibitor dasatinib

Inhibition of multiple myeloma (MM) plasma cells in their permissive bone marrow microenvironment represents an attractive strategy for blocking the tumor/vessel growth associated with the disease progression. However, target specificity is an essential aim of this approach. Here, we identified platelet-derived growth factor (PDGF)-receptor beta (PDGFRbeta) and pp60c-Src as shared constitutively activated tyrosine-kinases (TKs) in plasma cells and endothelial cells (ECs) isolated from MM patients (MMECs). Our cellular and molecular dissection showed that the PDGF-BB/PDGFRbeta kinase axis promoted MM tumor growth and vessel sprouting by activating ERK1/2, AKT, and the transcription of MMEC-released proangiogenic factors, such as vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). Interestingly, pp60c-Src TK-activity was selectively induced by VEGF in MM tumor and ECs, and the use of small-interfering (si)RNAs validated pp60c-Src as a key signaling effector of VEGF loop required for MMEC survival, migration, and angiogenesis. We also assessed the antitumor/vessel activity of dasatinib, a novel orally bioactive PDGFRbeta/Src TK-inhibitor that significantly delayed MM tumor growth and angiogenesis in vivo, showing a synergistic cytotoxicity with conventional and novel antimyeloma drugs (ie, melphalan, prednisone, bor-tezomib, and thalidomide). Overall data highlight the biologic and therapeutic relevance of the combined targeting of PDGFRbeta/c-Src TKs in MM, providing a framework for future clinical trials.

Interleukin-6 induces proliferation in adult spinal cord-derived neural progenitors via the JAK2/STAT3 pathway with EGF-induced MAPK phosphorylation

INTRODUCTION

In a previous study, we observed cell proliferation 3 days after spinal cord injury, and levels of interleukin-6 (IL-6) and epidermal growth factor (EGF) had significantly increased in the region of the injury.

OBJECTIVES

The purpose of the new study described here was to evaluate the roles of IL-6 and EGF after traumatic damage to the spinal cord having isolated neural progenitor cells (NPC) from adult mice.

METHODS AND RESULTS

Evidence provided by the trypan blue dye exclusion assay, 5-bromodeoxyuridine immunoreactivity and Western blot analysis indicated that IL-6 and EGF induced proliferation of these spinal cord-derived NPCs via phosphorylation of Janus-activated kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinases (MAPK), respectively. Combined treatment with IL-6 and EGF accelerated proliferation of cells synergistically and phosphorylation of STAT3 and extracellular signal-regulated kinase 1/2 (Erk1/2). Furthermore, AG490 and AG1478, JAK2 inhibitor and EGFR inhibitor, respectively, prevented the IL-6- and EGF-induced proliferation of the cells. Interestingly, IL-6-activated MAPKs but EGF did not influence JAK2/STAT3 activation; AG490 specifically inhibited IL-6-induced Erk1/2 phosphorylation without affecting IL-6-induced phosphorylation of Raf and MEK1/2. These results indicate that IL-6 is directly involved in Erk1/2 activation via JAK2 and that Erk1/2 provides a signal bridge between the IL-6-induced JAK2/STAT3 pathway and EGF-induced MAPK pathway.

CONCLUSIONS

Our study is the first demonstration of IL-6- and EGF-stimulated proliferation of spinal cord progenitor cells via JAK2/STAT3 and MAPK signalling pathways. These pathways play key roles in repopulation and regeneration of spinal cord tissue after injury. It may represent novel therapeutic targets for pharmacological intervention in central nervous system disease, including spinal cord injury.

Abnormal cytokine production by bone marrow stromal cells of multiple myeloma patients in response to RPMI8226 myeloma cells

INTRODUCTION

Recent studies indicate that bone marrow stromal cells (BMSCs) derived from patients with multiple myeloma (MM) differ from those of healthy donors in their expression of extracellular matrix compounds and in cytokine production. It is not known whether these abnormalities are primary or are acquired by BMSCs on contact with MM cells.

MATERIALS AND METHODS

Interleukin (IL)-6, IL-11, IL-10, and tumor necrosis factor (TNF)-alpha production by CD166+ mesenchymal BMSCs and the CD38+/CD138+ RPMI8226 myeloma cell line cultivated in vitro in monocultures or co-cultivated under cell-to-cell contact or non-contact conditions in the presence of a tissue culture insert were measured. Intracellular cytokines were measured by flow cytometry analysis as the percentage of cytokine-producing cells or by mean fluorescence intensity as the level of cytokine expression in cells. Additionally, ELISA was used to measure IL-6, soluble IL-6 receptor (sIL-6R), IL-11, IL-10, TNF-alpha, B-cell-activating factor of the TNF family (BAFF), hepatocyte growth factor (HGF), and osteopontin (OPN) production in the supernatants of the cultures and co-cultures.

RESULTS

A higher ability of the BMSCs of MM patients than in controls was detected to produce IL-6, IL-10, TNF-alpha, OPN, and especially HGF and BAFF in response to the RPMI8226 cells. Moreover, the BMSCs of the MM patients significantly enhanced the production of sIL-6R by the RPMI8226 cells.

DISCUSSION

Cytokines over-expressed by BMSCs of MM patients can function as growth factors for myeloma cells (IL-6, IL-10, HGF), migration stimulatory factors for tumor plasma cells (TNF-alpha, HGF), adhesion stimulatory factors (HGF, BAFF and OPN), stimulators of osteoclastogenesis (IL-6, TNF-alpha), and angiogenic factors (TNF-alpha). The results of this experiment strongly suggest that the BMSCs from MM patients differed in spontaneous and myeloma cell-induced production of cytokines, especially of HGF and BAFF, and these abnormalities were both primary and acquired by the BMSCs on contact with the MM cells. This in turn suggests the presence of an undefined, autocrine stimulation pathway resulting in a prolonged production of cytokines even in long-term cultures in vitro and in vivo. These abnormalities might provide optimal conditions for the proliferation and differentiation of residual tumor cells or their precursors in the affected bone marrow.

JAK-STAT pathway in carcinogenesis: Is it relevant to cholangiocarcinoma progression

The features of JAK-STAT signaling in liver cells are discussed in the current review. The role of this signaling cascade in carcinogenesis is accentuated. The possible involvement of this pathway and alteration of its elements are compared for normal cholangiocytes, cholangiocarcinoma predisposition and development. Prolactin and interleukin-6 are described in detail as the best studied examples. In addition, the non-classical nuclear translocation of cytokine receptors is discussed in terms of its possible implication to cholangiocarcinoma development.

Interleukin-6 and its receptor in cancer: implications for translational therapeutics

Interleukin-6 (IL-6) plays a major role in the response to injury or infection and is involved in the immune response, inflammation, and hematopoiesis. Its deregulation impacts numerous disease states, including many types of cancer. Consequently, modulating IL-6 may be an innovative therapeutic strategy in several diseases. A review of relevant published literature regarding IL-6 and its receptor was performed. In addition, a review of the relevance of this cytokine system to human illness, particularly in cancer, was undertaken. IL-6 is a pleiotropic cytokine that is involved in the physiology of virtually every organ system. Aberrant expression of this cytokine has been implicated in diverse human illnesses, most notably inflammatory and autoimmune disorders, coronary artery and neurologic disease, gestational problems, and neoplasms. In cancer, high levels of circulating IL-6 are observed in almost every type of tumor studied and predict a poor outcome. Furthermore, elevated IL-6 levels are associated strongly with several of the striking phenotypic features of cancer. Several molecules have been developed recently that target the biologic function of IL-6. Early results in the clinic suggest that this strategy may have a significant salutary impact on diverse tumors. The field of cytokine research has yielded a deep understanding of the fundamental role of IL-6 and its receptor in health and disease. Therapeutic targeting of IL-6 and its receptor in cancer has strong biologic rationale, and there is preliminary evidence suggesting that targeting of the IL-6 system may be beneficial in the treatment of cancer.

Changes in cytokine production and morphology of murine lymphoma NK/Ly cells in course of tumor development

The main goal of this study was to evaluate if specific cytokine expression in the NK/Ly lymphoma cells might be involved in development of intoxication in the tumor-bearing animals. RT-PCR analysis was used to study an expression of mRNA coding for IL-1α, IL-6, TNF-α, TNF-β and VEGF. ELISA was used to evaluate IL-6 and IFN-γ concentration in the ascitic fluid. Cytomorphological investigation of tumor cells was done after standard Romanovsky-Giemsa staining, and chromatin staining was performed with hematoxyline and neutral red. Lactate dehydrogenase and acid phosphatase release from tumor cells was estimated. It was revealed that the level of mRNA coding for VEGF and IL-6 was significant in the lymphoma cells. The level of VEGF mRNA was initially high and did not change during tumor progression, while the level of expression of IL6 mRNA was low at the initial stages of tumor growth and markedly increased (up to 5-fold) at the terminal stages. The obtained data on IL-6 mRNA expression were confirmed by ELISA, which showed more than 6-fold increase (from 90 to 570 pg/ml) in the IL-6 concentration in the ascitic fluid at late stages of NK/Ly tumor development. On the contrary to IL-6, concentration of IFN-γ in the ascitic fluid was very high at early stages of tumor development (1,000 pg/ml) and it markedly decreased (up to 30-fold, 30 pg/ml) at the terminal stages of tumor development. The high levels of IL-6 mRNA in tumor cells and IL-6 content in extracellular medium correlated with cell deterioration, as revealed by cytomorphologic study and the release of intracellular enzymes into extracellular medium. We suggest that an enhanced production and release of IL-6 by lymphoma cells can cause intoxication and exhaustion of the organism observed at terminal stages of tumor growth.