Interferon resistance of cutaneous T-cell lymphoma-derived clonal T-helper 2 cells allows selective viral replication

Defects in interferon pathways as potential biomarkers of sensitivity to oncolytic viruses

Increased sensitivity of cancer cells to viruses is a prerequisite for the success of oncolytic virotherapy. One of the major causes of such a phenotype is the disruption of innate antiviral defenses associated with dysfunction of type 1 interferons (IFNs) that permits unlimited replication of viruses in cancer cells. Defects in IFN pathways help cancer progression by providing additional advantages to tumor cells. However, while these defects promote the survival and accelerated proliferation of malignant cells, they facilitate viral replication and thus enhance the efficiency of viral oncolysis. This review describes a broad spectrum of defects in genes that participate in IFN induction and IFN response pathways. Expression levels and/or functional activities of these genes are frequently low or absent in cancer cells, making them sensitive to virus infection. Therefore, certain specific defects in IFN signaling cascades might serve as potential biomarkers to help in identifying individual cancer patients who are likely to benefit from oncolytic virotherapy.

Inactivation of RUNX3/p46 Promotes Cutaneous T-Cell Lymphoma

The key role of RUNX3 in physiological T-cell differentiation has been extensively documented. However, information on its relevance for the development of human T-cell lymphomas or leukemias is scarce. Here, we show that alterations of RUNX3 by either heterozygous deletion or methylation of its distal promoter can be observed in the tumor cells of 15 of 21 (71%) patients suffering from Sézary syndrome, an aggressive variant of cutaneous T-cell lymphoma. As a consequence, mRNA levels of RUNX3/p46, the isoform controlled by the distal promoter, are significantly lower in Sézary syndrome tumor cells. Re-expression of RUNX3/p46 reduces cell viability and promotes apoptosis in a RUNX3/p46^low cell line of cutaneous T-cell lymphoma. Based on this, we present evidence that RUNX3 can act as a tumor suppressor in a human T-cell malignancy and suggest that this effect is predominantly mediated through transcripts from its distal promoter, in particular RUNX3/p46.

T cell-tumor interaction directs the development of immunotherapies in head and neck cancer

The competent immune system controls disease effectively due to induction, function, and regulation of effector lymphocytes. Immunosurveillance is exerted mostly by cytotoxic T-lymphocytes (CTLs) while specific immune suppression is associated with tumor malignancy and progression. In squamous cell carcinoma of the head and neck, the presence, activity, but also suppression of tumor-specific CTL have been demonstrated. Functional CTL may exert a selection pressure on the tumor cells that consecutively escape by a combination of molecular and cellular evasion mechanisms. Certain of these mechanisms target antitumor effector cells directly or indirectly by affecting cells that regulate CTL function. This results in the dysfunction or apoptosis of lymphocytes and dysregulated lymphocyte homeostasis. Another important tumor-escape mechanism is to avoid recognition by dysregulation of antigen processing and presentation. Thus, both induction of functional CTL and susceptibility of the tumor and its microenvironment to become T cell targets should be considered in CTL-based immunotherapy.

Current and emerging treatment strategies for cutaneous T-cell lymphoma

Cutaneous T-cell lymphomas (CTCLs) are a rare group of mature T-cell lymphomas presenting primarily in the skin. The most common subtypes of CTCL are mycosis fungoides and its leukaemic variant Sézary's syndrome. Patients with early-stage disease frequently have an indolent clinical course; however, those with advanced stages have a shortened survival. For the treating physician, the question of how to choose a particular therapy in the management of CTCL is important. These diseases span the disciplines of dermatology, medical oncology and radiation oncology. Other than an allogeneic stem cell transplant, there are no curative therapies for this disease. Hence, many treatment modalities need to be offered to the patient over the course of their life. An accepted treatment approach has been to delay traditional chemotherapy, which can cause excessive toxicity without durable benefit. More conservative treatment strategies in the initial management of CTCL have led to the development of newer biological and targeted therapies. These therapies include biological immune enhancers such as interferon alpha and extracorporeal photopheresis that exert their effect by stimulating an immune response to the tumour cells. Retinoids such as bexarotene have been shown to be effective and well tolerated with predictable adverse effects. The fusion toxin denileukin diftitox targets the interleukin-2 receptor expressed on malignant T cells. Histone deacetylase inhibitors such as vorinostat and romidepsin (depsipeptide) may reverse the epigenetic states associated with cancer. Forodesine is a novel inhibitor of purine nucleoside phosphorylase and leads to apoptosis of malignant T cells. Pralatrexate is a novel targeted antifolate that targets the reduced folate carrier in cancer cells. Lastly, systemic chemotherapy including transplantation is used when rapid disease control is needed or if all other biological therapies have failed. As response rates to most of the biological agents used to treat CTCL are 25-30%, it is also reasonable to consider clinical trials with novel agents if one or two front-line therapies have failed, especially before considering chemotherapy. CTCL is largely an incurable disease with significant morbidity and more active agents are needed.

Vorinostat interferes with the signaling transduction pathway of T-cell receptor and synergizes with phosphoinositide-3 kinase inhibitors in cutaneous T-cell lymphoma

BACKGROUND

Vorinostat (suberoylanilide hydroxamic acid, SAHA), an inhibitor of class I and II histone deacetylases, has been approved for the treatment of cutaneous T-cell lymphoma. In spite of emerging information on the effect of vorinostat in many types of cancer, little is yet known about this drug's mechanism of action, which is essential for its proper use in combination therapy. We investigated alterations in gene expression profile over time in cutaneous T-cell lymphoma cells treated with vorinostat. Subsequently, we evaluated inhibitors of PI3K, PIM and HSP90 as potential combination agents in the treatment of cutaneous T-cell lymphoma.

DESIGN AND METHODS

The genes significantly up- or down-regulated by vorinostat over different time periods (2-fold change, false discovery rate corrected P value<0.05) were selected using the short-time series expression miner. Cell viability was assessed in vitro in cutaneous T-cell lymphoma cells through measuring intracellular ATP content. Drug interactions were analyzed by the combination index method with CalcuSyn software.

RESULTS

The functional analysis suggests that vorinostat modifies signaling of T-cell receptor, MAPK, and JAK-STAT pathways. The phosphorylation studies of ZAP70 (Tyr319, Tyr493) and its downstream target AKT (Ser473) revealed that vorinostat inhibits phosphorylation of these kinases. With regards to effects on cutaneous T-cell lymphoma cells, combining vorinostat with PI3K inhibitors resulted in synergy while cytotoxic antagonism was observed when vorinostat was combined with HSP90 inhibitor.

CONCLUSIONS

These results demonstrate the potential targets of vorinostat, underlining the importance of T-cell receptor signaling inhibition following vorinostat treatment. Additionally, we showed that combination therapies involving histone deacetylase inhibitors and inhibitors of PI3K are potentially efficacious for the treatment of cutaneous T-cell lymphoma.

Vesicular stomatitis virus: re-inventing the bullet

As our understanding of the molecular aspects of human disease increases, it is becoming possible to create designer therapeutics that are exquisitely targeted and have greater efficacy and fewer side effects. One class of targeted biological agents that has benefited from recent advances in molecular biology is designer viruses. Vesicular stomatitis virus (VSV) is normally relatively innocuous but can be engineered to target cancer cells or to stimulate immunity against diseases such as AIDS or influenza. Strains of VSV that induce or direct the production of interferon are superior to wild-type strains of the virus for inducing oncolysis. These strains might also make better vaccine vectors. In this review, some of the features that make VSV an excellent platform for the development of a range of viral therapeutics are discussed.

Type I IFN innate immune response to adenovirus-mediated IFN-gamma gene transfer contributes to the regression of cutaneous lymphomas

The fact that adenoviral vectors activate innate immunity and induce type I IFNs has not been fully appreciated in the context of cancer gene therapy. Type I IFNs influence different aspects of human immune response and are believed to be crucial for efficient tumor rejection. We performed transcriptional profiling to characterize the response of cutaneous lymphomas to intralesional adenovirus-mediated IFN-gamma (Ad-IFN-gamma) gene transfer. Gene expression profiles of skin lesions obtained from 19 cutaneous lymphoma patients before and after treatment with Ad-IFN-gamma revealed a distinct gene signature consisting of IFN-gamma- and numerous IFN-alpha-inducible genes (type II- and type I-inducible genes, respectively). The type I IFN response appears to have been induced by the vector itself, and its complexity, in terms of immune activation, was potentiated by the IFN-gamma gene insert. Intralesional IFN-gamma expression together with the induction of a combined type I/II IFN response to Ad-IFN-gamma gene transfer seem to underlie the objective (measurable) clinical response of the treated lesions. Biological effects of type I IFNs seem to enhance those set in motion by the transgene, in our case IFN-gamma. This combination may prove to be of therapeutic importance in cytokine gene transfer using Ads.

Mycosis fungoides--analysis of the duration of disease stages in patients who progress and the time point of high-grade transformation

BACKGROUND

Mycosis fungoides (MF) is a low-grade malignant primary cutaneous T-cell lymphoma which, in its evolution, passes through five distinct stages (patch, plaque, and tumor stages, lymph node infiltration, and, finally, multiple organ infiltration). Furthermore, a blast transformation into a high-grade malignant lymphoma can occur. In order to better understand the dynamics of the disease and the prognostic implications in patients who progress, we studied the duration of each stage and the time at which blast transformation occurred.

METHODS

We reviewed the records of 48 MF patients who had been followed in the lymphoma clinic of the Department of Dermatology, University Hospital Zurich, Zurich, Switzerland for a median of 10 years. Forty-two cases were eligible for evaluation.

RESULTS

Our study showed that MF in patients who progress is a disease which, after an initial patch stage with an average duration of 7.2 years, a plaque stage lasting for an average of 2.3 years, and a tumor stage with an average duration of 1.8 years, leads to a stage of lymph node infiltration with an average duration of 0.6 years, internal organ infiltration lasting for an average of 0.5 years and, finally, a fatal outcome. Consequently, the overall average disease duration in progressing patients is 12.4 years. Blast transformation occurs in 85% of all cases in the tumor stage.

CONCLUSIONS

The course of progressing MF is chronic and advancing. The progression is initially slow and later accelerates. Important prognostic factors are the stage of disease and the presence of blast transformation. The prognosis is better in the early stage and when blast transformation is absent.

Efficacy and tolerability of currently available therapies for the mycosis fungoides and Sezary syndrome variants of cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas are a heterogenous group of non-Hodgkin lymphomas. The characteristic clinicopathologic and immunophenotypic features and prognoses of the various cutaneous lymphomas have been recently described by the World Health Organization and European Organization for Research and Treatment of Cancer. Cutaneous T-cell lymphoma variants include mycosis fungoides and Sezary syndrome, which are generally associated, respectively, with indolent and aggressive clinical courses and are the subject of this review. Currently utilized treatments for cutaneous T-cell lymphoma include skin-directed therapies (topical agents such as corticosteroids, mechlorethamine, carmustine, and retinoids, phototherapy, superficial radiotherapy, and total skin electron beam therapy), systemic therapies (photophoresis, retinoids, denileukin diftitox, interferons, and chemotherapy), and stem cell transplantation (autologous and allogeneic). This review will describe recent advances in our understanding of the biology (immunologic, cytogenetic, and genetic) of cutaneous T-cell lymphomas and discuss the efficacy and tolerability of the current therapeutic options for cutaneous T-cell lymphomas. Disease progression in over 20% of patients with early stages of disease and the current lack of a definitive treatment which produces durable responses in advanced stages of disease indicates a critical unmet need in CTCL. New insights into the molecular and immunologic changes associated with cutaneous T-cell lymphomas should ultimately lead to the identification of novel therapeutic targets and the development of improved therapeutic options for patients with these malignancies.

Recombinant Measles Virus Induces Cytolysis of Cutaneous T-Cell Lymphoma In Vitro and In Vivo

Measles virus (MV) has shown promise as an oncolytic virus in the treatment of different tumor models for human B-cell lymphoma, multiple myeloma, ovarian cancer, and glioma. We have shown that, in a phase I clinical trial, MV vaccine induces tumor regression in cutaneous T-cell lymphoma (CTCL) patients. Here, we investigated in detail, the effect of recombinant MV (rMV) vaccine strain in CTCL cell cultures, and in vivo in established CTCL xenografts in nude mice. The susceptibility of three CTCL cell lines, originating from patients, to rMV was tested by determination of cell surface expression of MV receptors. All cell lines expressed the receptors CD150 and CD46 and were easily infected by rMV and induced complete cell lysis. The cytoreductive activity was apparent in cells forming aggregates, indicating a cell-to-cell spread of MV and cytolysis owing to virus infection. Intratumoral (i.t.) injection of rMV, expressing enhanced green fluorescent protein induced complete regression of large established human CTCL tumors in nude mice, whereas tumors with control treatment progressed exponentially. Immunohistochemical analysis of tumor biopsies, after i.t. treatment, for MV-NP protein complex demonstrated replication of MV within the tumors. The data demonstrate the potential of MV as a therapeutic agent against CTCL.

Cutaneous malignant lymphomas: Update 2006

Cutaneous lymphomas represent a unique group of lymphomas and are the second most frequent extranodal lymphomas. As with other neoplasias, the pathogenesis is based mainly on a stepwise accumulation of mutations of suppressor genes and oncogenes caused by genetic, environmental or infectious factors. The diagnostic work-up includes clinical, histological, imaging and hematological investigations and in many cases immunohistochemical and molecular biological analyses. The current WHO/EORTC classification of cutaneous lymphomas differentiates "mature T-cell and NK-cell lymphomas", "mature B-cell lymphomas" and "immature hematopoietic malignancies", their variants and subgroups. It is compatible with the WHO classification for neoplasias of the hematopoietic and lymphoid tissue and respects the organ-specific peculiarities of primary cutaneous lymphomas. The assignment of the various types of cutaneous lymphomas into prognostic categories (pre-lymphomatous "abortive" disorders; definite malignant lymphomas of low-grade malignancy; definite malignant lymphomas of high-grade malignancy) provides essential information on the biological behavior and allows an appropriate planning of the therapeutic strategy, which may be topical or systemic and aggressive or non-aggressive. Besides the classical options for therapy, there are new and "experimental" strategies, the efficacy of which has to be studied in clinical trials.

Pathogenesis and therapy of cutaneous lymphomas--progress or impasse?

The cutaneous environment hosts a number of hematopoietic neoplasms that are dominated by primary cutaneous (PC) T-cell lymphomas. Recent progress in molecular biology and immunology has provided tools to investigate the pathogenesis and the biology of these neoplasms. This review highlights newest findings concerning the immune biology of CD4+ CD56+ hematodermic neoplasms, and PC T-cell and B-cell lymphomas, speculating how these can be translated into more sophisticated, biology-based treatment approaches in the near future.

Emerging drugs in cutaneous T-cell lymphomas

Cutaneous T-cell lymphomas are a heterogeneous group of rare lympho-proliferative disorders. In most cases, they are characterised by the accumulation of clonal CD4+ lymphocytes in the skin. Extracutaneous involvement is present in late stages only. Unfortunately, only few drugs are registered for these disfiguring diseases. Skin-directed therapies using topical formulations are the preferred first-line modalities for cutaneous lesions in early stages. In this field there are interesting developments using topical retinoids and gene therapy products, such as adeno-IFN-gamma. Systemic treatment uses biologicals, such as fusion molecules, monoclonal antibodies and immune response modifiers (IFNs, retinoids), and well-tolerated antiproliferative drugs, such as histone deacetylase inhibitors or liposomal doxorubicin.

Future perspectives in the treatment of cutaneous T-cell lymphoma (CTCL)

Over the last 20 years the treatment of cutaneous T-cell lymphoma has been in a state of continual change. New therapies are constantly emerging as the search continues for more effective and tolerable disease-specific agents that satisfy medical needs. Therapies under investigation include topical retinoids, fusion molecules like denileukin diftitox, pegylated interferon, interleukin-2, and interleukin-12. Pegylated liposomal doxorubicin, gemcitabine, and chlorodeoxyadenosine also appear to have clinical potential. Other identified agents include vaccines and monoclonal antibodies. This article reviews some of the most recent clinical innovations.

Paucity of FOXP3+ cells in skin and peripheral blood distinguishes Sézary syndrome from other cutaneous T-cell lymphomas

Cutaneous T-cell lymphomas (CTCL) are mainly comprised of two variants: mycosis fungoides (MF) with CD4(+) tumor cells confined to the skin and the leukemic Sézary syndrome with tumor cell spread to the blood. In this study, we investigated cutaneous expression of the regulatory T-cell (T(reg)) marker FOXP3 in 30 CTCL patients. Immunohistochemical analysis revealed significantly lower numbers of CD4(+)FOXP3(+) cells within the dermal lymphomononuclear infiltrate of Sézary patients (16% FOXP3(+) cells of CD4(+) cells) in contrast to MF (43% FOXP3(+) cells (P<0.05)) and rare types of CTCL (45% FOXP3(+) cells). Furthermore, CD4(+)FOXP3(+) T cells were also markedly reduced in the CD4(+) population within the peripheral blood of Sézary patients compared to controls as determined by fluorescence-activated cell sorter, quantitative PCR and functional analyses. The data support the conclusion that the neoplastic cells in CTCL do not express the T(reg) marker FOXP3. Our data also identify Sézary syndrome as, to our knowledge, the first reported neoplastic disease with a clear reduction in T(reg) numbers within the CD4(+) population. This lack of T(reg) might account for the more aggressive nature of Sézary syndrome compared with other CTCL.

Standard and experimental therapy in cutaneous T-cell lymphomas

Cutaneous T-cell lymphomas are a heterogeneous group of lymphoproliferative disorders, characterized by the accumulation of clonal lymphocytes in the skin. Skin-directed therapies are the preferred first-line modalities. There are interesting new developments in topical therapy using retinoids and gene-therapy products such as adenovirus- interferon (IFN)-gamma. Systemic treatment uses biologicals such as fusion molecules, monoclonal antibodies and immune response modifiers (IFNs and retinoids), and well-tolerated antiproliferative drugs such as methotrexate. Evidence-based treatment recommendation exists but is hampered by the lack of large multicenter randomized trials.

Oncolytic measles virus in cutaneous T-cell lymphomas mounts antitumor immune responses in vivo and targets interferon-resistant tumor cells

Some cutaneous T-cell lymphomas, (CTCLs) clonal T cells are deficient in interferon signaling, making them promising targets for viral oncolysis. We evaluated cytopathic effects of measles virus (MV) in CTCL. CTCL cell lines and infiltrating lymphocytes in CTCL expressed MV receptors CD150 and CD46. In a phase 1 dose escalation trial a total of 16 injections of live MV, Edmonston-Zagreb vaccine strain, were given intratumorally to 5 patients with CTCL. Patients had antimeasles-serum antibodies and were pretreated with interferon-alpha to prevent uncontrolled virus spread. The well-tolerated treatment with MV resulted in clinical responses. Evaluation of biopsies, before and at 11 days after injection, by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated local viral activity with positive staining for MV nucleoprotein (NP), an increase of the interferon gamma (IFN-gamma)/CD4 and IFN-gamma/CD8 mRNA ratios and a reduced CD4/CD8 ratio. All patients demonstrated an increased antimeasles antibody titer after therapy. The data demonstrate that CTCLs are promising targets for an MV-based oncolytic therapy.

Vesicular stomatitis virus: a potential therapeutic virus for the treatment of hematologic malignancy

Certain strains of vesicular stomatitis virus (VSV) have been shown to be oncolytic in a wide variety of solid tumors. In the present study, we tested the leukemolytic properties of VSV using established leukemia cell lines and primary patient material. VSV efficiently killed essentially all leukemic cell lines. In contrast, however, normal clonogenic bone marrow progenitor cells and peripheral blood cells were remarkably refractory to infection by VSV. By exploiting this large difference in susceptibility to infection we successfully purged contaminating leukemic cells from cultures of peripheral blood progenitor cells (PBPC) using VSV. VSV was also able to infect and kill leukemic cells in primary samples taken from patients with multiple myeloma (MM). This study demonstrates the potential utility of VSV in the treatment, both ex vivo and in vivo, of hematologic malignancies.

GBP-5 Splicing Variants: New Guanylate-Binding Proteins with Tumor-Associated Expression and Antigenicity

We have identified a new gene, gbp-5, with high homology to the guanylate binding proteins (GBP) belonging to the GTPase superfamily including the ras gene. gbp-5 is transcribed at least into three splicing variants (gbp-5a, -5b, and -5ta) leading to two different proteins (GBP-5a/b, GBP-5ta). GBP-5ta is C-terminally truncated by 97aa and has therefore lost its isoprenylation site. Although RT-PCR results indicated expression of GBP-5 members in selected normal tissues, western blotting using two newly generated antibodies revealed that expression of both proteins is restricted to peripheral blood monocytes with GBP-5ta at lower levels. In contrast, cutaneous T-cell lymphoma (CTCL) tumor tissues (seven of seven) were positive solely for GBP-5ta, and four of four CTCL cell lines expressed both proteins. Eight of nine melanoma cell lines expressed GBP-5a/b and four of nine additionally low levels of GBP-5ta. SEREX retesting using CTCL sera indicated a higher immunogenicity for GBP-5ta (nine of 16) than for GBP-5a/b (two of 11). Treatment of CTCL cell lines with interferon-gamma did not alter protein expression of GBP-5ta or GBP-5a/b. The restricted expression pattern of both GBP-5ta and GBP-5a/b and the pivotal role of many known members of the GTP-binding proteins in proliferation and differentiation suggest possible cancer-related functions of gbp-5.

Interferon resistance promotes oncolysis by influenza virus NS1-deletion mutants

NS1 protein of influenza virus is a virulence factor that counteracts Type I interferon (IFN)-mediated antiviral response by the host. A recombinant influenza A virus that lacks the NS1 protein only replicates efficiently in systems that contain defective IFN pathways. We demonstrate that the conditional replication properties of NS1-modified influenza A virus mutants can be exploited for the virus-mediated oncolysis of IFN-resistant tumor cells. IFN resistance in analyzed tumor cell lines correlated with a reduced expression of STAT1. Addition of exogenous IFNalpha or supernatant of virus-infected endothelial cells inhibited viral oncolysis in IFN-sensitive but not in IFN-resistant cell lines. The oncolytic potential of NS1-modified influenza A virus mutants could be exploited in vivo in a SCID mouse model of a subcutaneously-implanted human IFN-resistant melanoma. The data indicate that IFN-resistant tumors are a suitable target for oncolysis induced by NS1-modified influenza virus mutants. STAT1 might serve as a marker to identify these IFN-resistant tumors.

Toward novel vaccines and therapies based on negative-strand RNA viruses

The study of negative-strand RNA viruses has suggested new strategies to produce more attenuated viruses. Reverse genetics has allowed the implementation of the strategies, and new or improved monovalent vaccines are being developed. In addition, recombinant viruses expressing foreign proteins or epitopes have been produced with the aim of developing multivalent vaccines capable of stimulating humoral and cellular immune responses against more than one pathogen. Finally, recombinant viruses that selectively enter cells expressing tumor markers or the HIV envelope protein have been engineered and shown to lyse target cells. Preclinical and clinical trials of improved and multivalent vaccines and therapeutic (oncolytic) viruses are ongoing.

IGF-1 down-regulates IFN-gamma R2 chain surface expression and desensitizes IFN-gamma/STAT-1 signaling in human T lymphocytes

The ability of insulin-like growth factor-1 (IGF-1) to regulate surface expression of the interferon-gamma receptor 2 (IFN-gamma R2) transducing chain and activation of IFN-gamma-induced signal transducer and activator of transcription-1 (STAT-1) in human T cells was analyzed. We show that, especially in the absence of serum (which contains IGF-1), IGF-1 down-regulated surface expression of the IFN-gamma R2 chain and inhibited both IFN-gamma-dependent STAT-1 activation and apoptosis in T-cell lines ST4, Jurkat, and Molt-4. IFN-gamma R2 down-regulation resulted from its enhanced internalization since IGF-1 completely restored the uptake of anti-IFN-gamma R2 monoclonal antibody (mAb) in serum-deprived T-cell lines. When the interaction between IGF-1 and its receptor was blocked by anti-IGF-1R mAb, enhancement of IFN-gamma R2 surface expression, STAT-1 activation, and reinstatement of IFN-gamma-induced apoptosis were observed. Enhanced expression of IFN-gamma R2 was also observed in phytohemagglutinin (PHA)-activated T lymphoblasts cultured in the presence of anti-IGF-1R mAb, whereas IGF-1 or anti-IGF-1R mAb did not modify the high IFN-gamma R2 expression in B and myeloid cell lines. Both IGF-1 and anti-IGF-1R mAb did not modify the constitutive expression of IFN-gamma R2 mRNA in T cells as well as the high IFN-gamma R1 binding chain surface expression in T, B, and myeloid cells. These data indicate that IGF-1 plays a critical role in the desensitization of IFN-gamma/STAT-1 signaling in T lymphocytes by delivering a signal for IFN-gamma R2 internalization.

A novel attenuated replication-competent adenovirus for melanoma therapy

To generate a replication-competent adenovirus (Ad) with specificity for melanoma, we constructed a tissue-specific promoter restricting E1A expression to melanoma cells. The combination of four copies of a mouse tyrosinase enhancer element (TE) fused to the human tyrosinase promoter (TP) yielded up to 2000-fold higher luciferase reporter activity in tyrosinase-expressing melanoma cells than in nonmelanoma cells. Insertion of the composite TETP construct upstream of the E1A gene was combined with deleting as far as possible the intertwined endogenous Ad enhancer/promoter (EP). The resulting AdDeltaEP-TETP vector, also deleted for the E3 region, was found to replicate in tyrosinase-positive melanoma cells, such as SK-Mel23 as efficiently as wild-type Ad5, but at a more than 50-fold reduced level in nonmelanoma tumour cells and primary human cells. Injection of AdDeltaEP-TETP into xenotransplanted melanomas, but not into HeLa-derived tumours led to long-lasting tumour regression in nude mice. This AdDeltaEP-TETP virus might be useful for the treatment of accessible lesions in advanced melanoma patients.

From inflammation to neoplasia: new concepts in the pathogenesis of cutaneous lymphomas

Mycosis fungoides is a clinicopathologic term which describes a neoplasm of cerebriform T lymphocytes that form plaques and tumors. We further suggest that mycosis fungoides arises in a background of chronic inflammation or as a response to chronic antigenic stimulation. Subsequently, a series of mutations results in the stepwise progression from eczematous patches, to plaques, tumors and eventual hematogenous dissemination. The pathogenetic process is driven by various, probably individually different, exogenous factors, e.g. environmental foreign antigens, bacterial superantigen, and/or endogenous factors, e.g. autocrine cytokine loops, CD40/CD40L and B7/CD28 interaction.

The interferon inhibiting cytokine IK is overexpressed in cutaneous T cell lymphoma derived tumor cells that fail to upregulate major histocompatibility complex class II upon interferon-gamma stimulation

Cutaneous T cell lymphomas are characterized by an accumulation of malignant clonal lymphocytes in the skin and occasionally in the blood. We compared gene transcription profiles from cultured clonal lymphocytes with autologous healthy blood lymphocytes by microarray hybridization. Cutaneous T cell lymphoma derived cells transcribed high amounts of an interferon inhibiting cytokine factor. The presence of an interferon inhibiting cytokine factor was confirmed in 12 skin biopsies of mycosis fungoides and Sézary syndrome derived blood lymphocytes by reverse transcriptase-polymerase chain reaction. The presence of interferon inhibiting cytokine factor mRNA in Sézary syndrome derived lymphocytes was associated with a lack of HLA class II upregulation after stimulation with interferon-alpha and interferon-gamma. This was not due to a loss of the interferon signaling cascade as the presence of interferon-signaling components was confirmed by reverse transcriptase--polymerase chain reaction on the transcriptional level. The elevated constitutive interferon inhibiting cytokine factor expression observed in cutaneous T cell lymphoma derived cells was insensitive to interferon-gamma stimulation, but was enhanced in normal peripheral blood mononuclear cells. We suggest that interferon inhibiting cytokine factor contributes to the lack of HLA class II upregulation in lymphoma cells. Interferon inhibiting cytokine factor may participate in providing a microenvironment at the tumor site insensitive to interferon-gamma stimulation and thus prevents an efficient local immune response.