Upregulation of Inflammatory Cytokines and Oncogenic Signal Pathways Preceding Tumor Formation in a Murine Model of T-Cell Lymphoma in Skin

Mycosis fungoides and IL-4/13 inhibitors: what is known and unmet needs

INTRODUCTION

Dupilumab is a monoclonal antibody that inhibits the IL-4 receptor alpha, preventing the binding of IL-4 and IL-13 and the subsequent signal transduction. Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common form of cutaneous T-cell lymphoma (CTCL). Several cases of MF have been reported following the initiation of dupilumab in patients previously diagnosed with atopic dermatitis.

AREAS COVERED

This article is a narrative review of the current state of knowledge regarding the correlation between dupilumab and the development of CTCL. Clinical studies on this topic are reviewed, with a particular focus on the pathogenetic theories proposed to date. Finally, we present a new theory, previously undescribed, regarding the potential role of the cytokine microenvironment in triggering CTCL in patients treated with dupilumab.

EXPERT OPINION

Dupilumab could unmask CTCLs by inhibiting IL-4. In fact, a recent study observed that IL-4 plays a key role in maintaining the 'equilibrium phase' between tumor and microenvironment cells. Disruption of this balance could promote the escape of tumor cells and lead to the unmasking of CTCLs.

"Next top" mouse models advancing CTCL research

This review systematically describes the application of in vivo mouse models in studying cutaneous T-cell lymphoma (CTCL), a complex hematological neoplasm. It highlights the diverse research approaches essential for understanding CTCL's intricate pathogenesis and evaluating potential treatments. The review categorizes various mouse models, including xenograft, syngeneic transplantation, and genetically engineered mouse models (GEMMs), emphasizing their contributions to understanding tumor-host interactions, gene functions, and studies on drug efficacy in CTCL. It acknowledges the limitations of these models, particularly in fully replicating human immune responses and early stages of CTCL. The review also highlights novel developments focusing on the potential of skin-targeted GEMMs in studying natural skin lymphoma progression and interactions with the immune system from onset. In conclusion, a balanced understanding of these models' strengths and weaknesses are essential for accelerating the deciphering of CTCL pathogenesis and developing treatment methods. The GEMMs engineered to target specifically skin-homing CD4+ T cells can be the next top mouse models that pave the way for exploring the effects of CTCL-related genes.

Betulin and Its Derivatives Reduce Inflammation and COX-2 Activity in Macrophages

Betulin is a heavily studied natural compound for its use as an anticancer or pro-regenerative agent. The structural similarity between betulin to steroids gives rise to the idea that the substance may as well act as an anti-inflammatory drug. This study is the first to describe the anti-inflammatory properties of betulinic acid, betulin, and its derivatives with amino acids 1,4-diaminebutane (Dab), 1,3-diaminepropane (Dap), Ornithine (Orn), and lysine (Lys) on murine macrophages from lymphoma site. The compounds were compared to dexamethasone. To establish the response of the macrophages to the natural compounds, we tested the viability as well as sensitivity to the inflammatory signaling (IFNγR). IL-6 secretory properties and HSP-70 content in the cells were examined. Furthermore, we characterized the effects of compounds on the inhibition of cyclooxygenase-2 (COX-2) activity both in the enzymatic assays and molecular docking studies. Then, the changes in COX-2 expression after betulin treatment were assessed. Betulin and betulinic acid are the low-cytotoxicity compounds with the highest potential to decrease inflammation via reduced IL-6 secretion. To some extent, they induce the reorganization of IFNγR with nearly no effect on COX-2 activity. Conversely, Bet-Orn and Bet-Lys are highly cytotoxic and induce the aggregation of IFNγR. Besides, Bet-Lys reduces the activity of COX-2 to a higher degree than dexamethasone. Bet-Orn is the only one to increase the HSP-70 content in the macrophages. In case of IL-6 reduction, all compounds were more potent than dexamethasone.

Validation of AAC-11-Derived Peptide Anti-Tumor Activity in a Single Graft Sézary Patient-Derived Xenograft Mouse Model

Sézary syndrome (SS) is an aggressive cutaneous T cell lymphoma with poor prognosis mainly characterized by the expansion of a tumor CD4⁺ T cell clone in both skin and blood. So far, the development of new therapeutic strategies has been hindered by a lack of reproducible in vivo models closely reflecting patients’ clinical features. We developed an SS murine model consisting of the intravenous injection of Sézary patients’ PBMC, together with a mixture of interleukins, in NOD-SCID-gamma mice. Thirty-four to fifty days after injection, mice showed skin disorders similar to that observed in patients, with the detection of epidermis thickening and dermal tumor T cell infiltrates. Although experimental variability was observed, Sézary cells could be tracked in the blood stream, confirming that our model could efficiently exhibit both skin and blood involvement. Using this model, we evaluated the therapeutic potential of RT39, a cell-penetrating peptide derived from the survival protein anti-apoptosis clone 11 (AAC-11), that we previously characterized as specifically inducing apoptosis of Sézary patients’ malignant clone ex vivo. Systemic administration of RT39 led to cutaneous tumor T cells depletion, demonstrating efficient malignant cells’ targeting and a favorable safety profile. These preclinical data confirmed that RT39 might be an innovative therapeutic tool for Sézary syndrome.

Sézary syndrome patient-derived models allow drug selection for personalized therapy

Patient-derived SS cells show highly heterogeneous drug responses.

We have developed a joint in vitro/in vivo platform to predict SS therapy response.

Current therapeutic approaches for Sézary syndrome (SS) do not achieve a significant improvement in long-term survival of patients, and they are mainly focused on reducing blood tumor burden to improve quality of life. Eradication of SS is hindered by its genetic and molecular heterogeneity. Determining effective and personalized treatments for SS is urgently needed. The present work compiles the current methods for SS patient–derived xenograft (PDX) generation and management to provide new perspectives on treatment for patients with SS. Mononuclear cells were recovered by Ficoll gradient separation from fresh peripheral blood of patients with SS (N = 11). A selected panel of 26 compounds that are inhibitors of the main signaling pathways driving SS pathogenesis, including NF-kB, MAPK, histone deacetylase, mammalian target of rapamycin, or JAK/STAT, was used for in vitro drug sensitivity testing. SS cell viability was evaluated by using the CellTiter-Glo_3D Cell Viability Assay and flow cytometry analysis. We validated one positive hit using SS patient–derived Sézary cells xenotransplanted (PDX) into NOD-SCID-γ mice. In vitro data indicated that primary malignant SS cells all display different sensitivities against specific pathway inhibitors. In vivo validation using SS PDX mostly reproduced the responses to the histone deacetylase inhibitor panobinostat that were observed in vitro. Our investigations revealed the possibility of using high-throughput in vitro testing followed by PDX in vivo validation for selective targeting of SS tumor cells in a patient-specific manner.

T cells in the skin: lymphoma and inflammatory skin disease

T cells are established contributors to the pathogenesis of atopic dermatitis (AD) and psoriasis, yet whether they are the key drivers or simply unwitting participants remains incompletely understood. Conversely, malignant T cells are the undisputed culprits of cutaneous T cell lymphoma (CTCL), a group of diseases that share key clinical, histopathological and molecular features with inflammatory skin disease (ISD). Here, we compare the pathogenesis of ISD and CTCL and discuss the resulting insights. Recurrent, skin-limited disease implicates skin-resident T cells (T_RM) in both ISD and CTCL. In CTCL, malignant T cells recruit benign T cells into inflammatory skin lesions, a disease-amplifying function also proposed for pathogenic T cells in ISD. Mechanistically, cytokines produced by malignant T cells in CTCL and by pathogenic T cells in ISD, respectively, are likely both necessary and sufficient to drive skin inflammation and pruritus, which in turn promotes skin barrier dysfunction and dysbiosis. Therapies for ISD target T cell effector functions but do not address the chronicity of disease while treatments for CTCL target malignant T cells but not primarily the symptoms of the disease. By integrating our understanding of ISD and CTCL, important insights into pathogenesis and therapy can be made which may improve the lives of sufferers of both disease groups.

Understanding Cell Lines, Patient-Derived Xenograft and Genetically Engineered Mouse Models Used to Study Cutaneous T-Cell Lymphoma

Cutaneous T cell lymphoma (CTCL) is a spectrum of lymphoproliferative disorders caused by the infiltration of malignant T cells into the skin. The most common variants of CTCL include mycosis fungoides (MF), Sézary syndrome (SS) and CD30⁺ Lymphoproliferative disorders (CD30⁺ LPDs). CD30⁺ LPDs include primary cutaneous anaplastic large cell lymphoma (pcALCL), lymphomatoid papulosis (LyP) and borderline CD30⁺ LPD. The frequency of MF, SS and CD30⁺ LPDs is ~40–50%, <5% and ~10–25%, respectively. Despite recent advances, CTCL remains challenging to diagnose. The mechanism of CTCL carcinogenesis still remains to be fully elucidated. Hence, experiments in patient-derived cell lines and xenografts/genetically engineered mouse models (GEMMs) are critical to advance our understanding of disease pathogenesis. To enable this, understanding the intricacies and limitations of each individual model system is highly important. Presently, 11 immortalized patient-derived cell lines and different xenograft/GEMMs are being used to study the pathogenesis of CTCL and evaluate the therapeutic efficacy of various treatment modalities prior to clinical trials. Gene expression studies, and the karyotyping analyses of cell lines demonstrated that the molecular profile of SeAx, Sez4, SZ4, H9 and Hut78 is consistent with SS origin; MyLa and HH resemble the molecular profile of advanced MF, while Mac2A and PB2B represent CD30⁺ LPDs. Molecular analysis of the other two frequently used Human T-Cell Lymphotropic Virus-1 (HTLV-1)⁺ cell lines, MJ and Hut102, were found to have characteristics of Adult T-cell Leukemia/Lymphoma (ATLL). Studies in mouse models demonstrated that xenograft tumors could be grown using MyLa, HH, H9, Hut78, PB2B and SZ4 cells in NSG (NOD Scid gamma mouse) mice, while several additional experimental GEMMs were established to study the pathogenesis, effect of drugs and inflammatory cytokines in CTCL. The current review summarizes cell lines and xenograft/GEMMs used to study and understand the etiology and heterogeneity of CTCL.

The pivotal role of cytotoxic NK cells in mediating the therapeutic effect of anti-CD47 therapy in mycosis fungoides

CD47 is frequently overexpressed on tumor cells and is an attractive therapeutic target. The mechanism by which anti-CD47 immunotherapy eliminates cutaneous lymphoma has not been explored. We utilized CRISPR/Cas-9 CD47 knock-out, depletion of NK cells, and mice genetically deficient in IFN-γ to elucidate the mechanism of anti-CD47 therapy in a murine model of cutaneous T cell lymphoma (CTCL). CD47 was found to be a crucial factor for tumor progression since CD47 KO CTCL exhibited a delay in tumor growth. The treatment of CD47 WT murine CTCL with anti-CD47 antibodies led to a significant reduction in tumor burden as early as four days after the first treatment and accompanied by an increased percentage of cytotoxic NK cells at the tumor site. The depletion of NK cells resulted in marked attenuation of the anti-tumor effect of anti-CD47. Notably, the treatment of CD47 WT tumors in IFN-γ KO mice with anti-CD47 antibodies was efficient, demonstrating that IFN-γ was not required to mediate anti-CD47 therapy. We were able to potentiate the therapeutic effect of anti-CD47 therapy by IFN-α. That combination resulted in an increased number of cytotoxic CD107a + IFN-γ-NK1.1 cells and intermediate CD62L + NKG2a-NK1.1. Correlative data from a clinical trial (clinicaltrials.gov, NCT02890368) in patients with CTCL utilizing SIRPαFc to block CD47 confirmed our in vivo observations.

The synergistic proapoptotic effect of PARP-1 and HDAC inhibition in cutaneous T-cell lymphoma is mediated via Blimp-1

The therapy of advanced mycosis fungoides (MF) presents a therapeutic challenge, and the search for new therapeutic targets is ongoing. Poly(ADP-ribose) polymerase 1 was shown to be upregulated in patients with advanced MF and could be druggable by a new class of chemotherapeutic agents, PARP-1 inhibitors, which are already in clinical trials for other malignancies; however, the role of PARP-1 inhibitors in MF has never been established. We examined the efficacy of talazoparib in the murine model of cutaneous T-cell lymphoma. The cytotoxic effect of talazoparib on Moloney MuLV-induced T-cell lymphoma (MBL2) cells was a result of G2/M cell cycle arrest via the upregulation of p53. The in vivo experiments confirmed the clinical impact of talazoparib on MF tumors. When talazoparib was combined with the histone deacetylase (HDAC) inhibitor, romidepsin, the cytotoxic effect was synergized via downregulation of the DNA-repair genes Fanconianemia complementation group A (FANCA), Fanconi anemia complementation group D2 (FANCD2), and DNA topoisomerase II binding protein 1(TOPBP1)and stimulation of apoptosis via Blimp-1 (PRDM1)/Bax axis. Romidepsin increased the expression of IRF8 and Bcl-6, leading to upregulation of Blimp1and Bax; whereas talazoparib upregulated Blimp-1 and Bax via upregulation of interferon regulatory factor 4 (IRF4), leading to cleavage of caspases 6 and 7. Thus, a combination of talazoparib with romidepsin demonstrated the synergistic antilymphoma effect and warranted further investigation in a clinical trial.

Xenograft and cell culture models of Sézary syndrome reveal cell of origin diversity and subclonal heterogeneity

Sézary Syndrome (SS) is a rare aggressive epidermotropic cutaneous T-cell lymphoma (CTCL) defined by erythroderma, pruritis, and a circulating atypical CD4 + T-cell clonal population. The diversity of Sézary cell (SC) phenotype and genotype may reflect either plasticity or heterogeneity, which was difficult to evaluate dynamically until the achievement of long-term SC expansion. Therefore, we developed six defined culture conditions allowing for the expansion of SC defined by their phenotype and monoclonality in four of seven SS cases. Engraftment of SC through the intrafemoral route into immunodeficient NOD.Cg-Prkdc(scid)Il2rg(tm1Wjll)/SzJ (NSG) mice was achieved in 2 of 14 SS cases. Secondary xenograft by percutaneous injection mimicked most of the features of SS with dermal infiltration, epidermotropism, and blood spreading. These models also allowed assessing the intra-individual heterogeneity of patient SC. Subclones sharing the same TCR gene rearrangement evolved independently according to culture conditions and/or after xenografting. This clonal selection was associated with some immunophenotypic plasticity and limited genomic evolution both in vitro and in vivo. The long-term amplification of SC allowed us to develop eight new SC lines derived from four different patients. These lines represent the cell of origin diversity of SC and provide new tools to evaluate their functional hallmarks and response to therapy.

Animal Models in Microbeam Radiation Therapy: A Scoping Review

BACKGROUND

Microbeam Radiation Therapy (MRT) is an innovative approach in radiation oncology where a collimator subdivides the homogeneous radiation field into an array of co-planar, high-dose beams which are tens of micrometres wide and separated by a few hundred micrometres.

OBJECTIVE

This scoping review was conducted to map the available evidence and provide a comprehensive overview of the similarities, differences, and outcomes of all experiments that have employed animal models in MRT.

METHODS

We considered articles that employed animal models for the purpose of studying the effects of MRT. We searched in seven databases for published and unpublished literature. Two independent reviewers screened citations for inclusion. Data extraction was done by three reviewers.

RESULTS

After screening 5688 citations and 159 full-text papers, 95 articles were included, of which 72 were experimental articles. Here we present the animal models and pre-clinical radiation parameters employed in the existing MRT literature according to their use in cancer treatment, non-neoplastic diseases, or normal tissue studies.

CONCLUSIONS

The study of MRT is concentrated in brain-related diseases performed mostly in rat models. An appropriate comparison between MRT and conventional radiotherapy (instead of synchrotron broad beam) is needed. Recommendations are provided for future studies involving MRT.

Blood transcriptional profiling reveals IL-1 and integrin signaling pathways associated with clinical response to extracorporeal photopheresis in patients with leukemic cutaneous T-cell lymphoma

Extracorporeal photopheresis (ECP) is a frontline therapy for patients with leukemic cutaneous T-cell lymphoma (L-CTCL), but its mechanisms of action are not fully understood. This study was to explore the molecular mechanisms underlying clinical response versus non-response in patients with L-CTCL. We performed blood transcriptional profiling of ten L-CTCL patients at Day 2 and 1 month post- ECP compared to pre-ECP baseline using Agilent Whole Human Genome Microarray technology. Differentially expressed genes (DEGs) between five clinically-responsive patients and five clinically-resistant patients were cross-compared. Higher numbers of genes were modulated in responders than non-responders after ECP at both Day 2 and 1 month, with two thirds of DEGs down-regulated. The down-regulated DEGs at 1 month post-ECP were related to inflammatory, immune and/or stress responses, platelet functions, and chromatin remodeling. Upregulated DEGs were mainly related to functions of the nucleolus. Pathway analysis revealed that integrin and IL-1 signaling pathways were the top pathways affected in responders, which were minimally affected in non-responders. The top upstream transcription regulators affected were IL1B, EGR1, FAS, and TGFB1. Our results suggest that the modulation of cell adhesion and suppression of IL-1β induced inflammation may underlie the efficacy of ECP in L-CTCL.

A Microbiota-Dependent, STAT3-Driven Mouse Model of Cutaneous T-Cell Lymphoma

In recent years, much has been learned about the molecular genetics of cutaneous T-cell lymphomas. Fanok et al. (2018) translate knowledge from systematic genomic and transcriptomic analyses to develop a mouse model that tests the hypothesis that activated STAT3 in CD4⁺ T cells may be a driver of cutaneous T-cell lymphomas. The transgenic mouse that they developed exhibits clinical features of mycosis fungoides, as well as Sezary syndrome, two well-known entities in the cutaneous T-cell lymphoma spectrum. Furthermore, these authors show that TCR engagement and microbiota are required for development of the complete clinical phenotype. This mouse model, which develops progressive disease, provides a new tool to understand cutaneous T-cell lymphoma biology and to potentially test new therapies.

IL-10 is overexpressed in human cutaneous T-cell lymphoma and is required for maximal tumor growth in a mouse model

A crucial question pertains to a role of IL-10 as a tumorigenic factor, or just a marker of advanced disease in cutaneous T-cell lymphoma (CTCL). Herein, we measured significantly elevated IL-10 mRNA in a cohort of skin samples of patients with CTCL. Increased IL-10 was also detected in the tumor microenvironment of an established inflammation-dependent murine model of using MBL2 T lymphoma cells. Conditioned media from MBL2 cells was able to stimulate IL-10 production in bone marrow-derived macrophages in an IL-4-dependent manner. Implanted MBL2 T-cell lymphomas in IL-10KO mice were 50% smaller, accompanied by decreased numbers of infiltrating macrophages and reduced efficiency of M2-polarization compared with wild-type mice. With anti-IL-10R mAb treatment, both wild-type tumor-bearing mice and IL-10KO mice exhibited a further growth inhibition. Our data indicate that targeting IL-10 signaling with neutralizing antibodies to IL-10 or its receptor may have a great potential for advanced CTCL therapy.

Role of Dysregulated Cytokine Signaling and Bacterial Triggers in the Pathogenesis of Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma is a heterogeneous group of lymphomas characterized by the accumulation of malignant T cells in the skin. The molecular and cellular etiology of this malignancy remains enigmatic, and what role antigenic stimulation plays in the initiation and/or progression of the disease remains to be elucidated. Deep sequencing of the tumor genome showed a highly heterogeneous landscape of genetic perturbations, and transcriptome analysis of transformed T cells further highlighted the heterogeneity of this disease. Nonetheless, using data harvested from high-throughput transcriptional profiling allowed us to develop a reliable signature of this malignancy. Focusing on a key cytokine signaling pathway previously implicated in cutaneous T-cell lymphoma pathogenesis, JAK/STAT signaling, we used conditional gene targeting to develop a fully penetrant small animal model of this disease that recapitulates many key features of mycosis fungoides, a common variant of cutaneous T-cell lymphoma. Using this mouse model, we show that T-cell receptor engagement is critical for malignant transformation of the T lymphocytes and that progression of the disease is dependent on microbiota.

Novel phosphorylated TAK1 species with functional impact on NF-κB and β-catenin signaling in human Cutaneous T-cell lymphoma

Cutaneous T-cell lymphomas (CTCLs) represent different subtypes of lymphoproliferative disorders with no curative therapies for the advanced forms of the disease (namely mycosis fungoides and the leukemic variant, Sézary syndrome). Molecular events leading to CTCL progression are heterogeneous, however recent DNA and RNA sequencing studies highlighted the importance of NF-κB and β-catenin pathways. We here show that the kinase TAK1, known as essential in B-cell lymphoma, is constitutively activated in CTCL cells, but tempered by the MYPT1/PP1 phosphatase complex. Blocking PP1 activity, both pharmacologically and genetically, resulted in TAK1 hyperphosphorylation at residues T344, S389, T444, and T511, which have functional impact on canonical NF-κB signaling. Inhibition of TAK1 precluded NF-κB and β-catenin signaling and induced apoptosis of CTCL cell lines and primary Sézary syndrome cells both in vitro and in vivo. Detection of phosphorylated TAK1 at T444 and T344 is associated with the presence of lymphoma in a set of 60 primary human samples correlating with NF-κB and β-catenin activation. These results identified TAK1 as a potential biomarker and therapeutic target for CTCL therapy.

The therapeutic potential of iron-targeting gallium compounds in human disease: From basic research to clinical application

Gallium, group IIIa metal, shares certain chemical characteristics with iron which enable it to function as an iron mimetic that can disrupt iron-dependent tumor cell growth. Gallium may also display antimicrobial activity by disrupting iron homeostasis in certain bacteria and fungi. Gallium's action on iron homeostasis leads to inhibition of ribonucleotide reductase, mitochondrial function, and changes in proteins of iron transport and storage. In addition, gallium induces an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Early clinical trials evaluated the efficacy of the simple gallium salts, gallium nitrate and gallium chloride. However, newer gallium-ligands such as Tris(8-quinolinolato)gallium(III) (KP46) and gallium maltolate have been developed and are undergoing clinical evaluation. Additional gallium-ligands that demonstrate antitumor activity in preclinical studies have emerged. Their mechanisms of action and their spectrum of antitumor activity may extend beyond the earlier generations of gallium compounds and warrant further investigation. This review will focus on the evolution and potential of gallium-based therapeutics.

STAT3/5-Dependent IL9 Overexpression Contributes to Neoplastic Cell Survival in Mycosis Fungoides

PURPOSE

Sustained inflammation is a key feature of mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL). Resident IL9-producing T cells have been found in skin infections and certain inflammatory skin diseases, but their role in MF is currently unknown.

EXPERIMENTAL DESIGN

We analyzed lesional skin from patients with MF for the expression of IL9 and its regulators. To determine which cells were producing IL9, high-throughput sequencing was used to identify malignant clones and Vb-specific antibodies were employed to visualize malignant cells in histologic preparations. To explore the mechanism of IL9 secretion, we knocked down STAT3/5 and IRF4 by siRNA transfection in CTCL cell lines receiving psoralen+UVA (PUVA) ± anti-IL9 antibody. To further examine the role of IL9 in tumor development, the EL-4 T-cell lymphoma model was used in C57BL/6 mice.

RESULTS

Malignant and reactive T cells produce IL9 in lesional skin. Expression of the Th9 transcription factor IRF4 in malignant cells was heterogeneous, whereas reactive T cells expressed it uniformly. PUVA or UVB phototherapy diminished the frequencies of IL9- and IL9r-positive cells, as well as STAT3/5a and IRF4 expression in lesional skin. IL9 production was regulated by STAT3/5 and silencing of STAT5 or blockade of IL9 with neutralizing antibodies potentiated cell death after PUVA treatment in vitro IL9-depleted mice exhibited a reduction of tumor growth, higher frequencies of regulatory T cells, and activated CD4 and CD8 T lymphocytes.

CONCLUSIONS

Our results suggest that IL9 and its regulators are promising new targets for therapy development in mycosis fungoides. Clin Cancer Res; 22(13); 3328-39. ©2016 AACR.

Rapamycin Suppresses Tumor Growth and Alters the Metabolic Phenotype in T-Cell Lymphoma

The mTOR pathway is a master regulator of cellular growth and metabolism. The biosynthetic and energetic demand of rapidly proliferating cells such as cancer cells is met by metabolic adaptations such as an increased glycolytic rate known as the Warburg effect. Herein, we characterize the anti-tumor effect of rapamycin in a mouse model of T-cell lymphoma and examine the metabolic effects in vitro. The murine T-cell lymphoma line, MBL2, and human cutaneous T-cell lymphoma (CTCL) lines, HH and Hut78, were used in syngeneic or standard NSG mouse models to demonstrate a marked suppression of tumor growth by rapamycin accompanied by inhibition of mTORC1/2. Analysis of the metabolic phenotype showed a substantial reduction in the glycolytic rate and glucose utilization in rapamycin-treated lymphoma cells. This was associated with reduced expression of glucose transporters and glycolytic enzymes in cultured cells and xenograft tumors. As a result of the decrease in glycolytic state, rapamycin-treated cells displayed reduced sensitivity to low-glucose conditions but continued to rely on mitochondrial oxidative phosphorylation (OXPHOS) with sensitivity to inhibition of OXPHOS. Taken together, we demonstrate that rapamycin suppresses growth of T-cell lymphoma tumors and leads to a reduction in aerobic glycolysis counteracting the Warburg effect of cancer cells.

Gallium maltolate inhibits human cutaneous T-cell lymphoma tumor development in mice

Cutaneous T-cell lymphomas (CTCLs) represent a heterogeneous group of non-Hodgkin's lymphoma characterized by an accumulation of malignant CD4 T cells in the skin. The group IIIa metal salt, gallium nitrate, is known to have antineoplastic activity against B-cell lymphoma in humans, but its activity in CTCLs has not been elaborated in detail. Herein, we examined the antineoplastic efficacy of a gallium compound, gallium maltolate (GaM), in vitro and in vivo with murine models of CTCLs. GaM inhibited cell growth and induced apoptosis of cultured CTCL cells. In human CTCL xenograft models, peritumoral injection of GaM limited the growth of CTCL cells, shown by fewer tumor formations, smaller tumor sizes, and decreased neovascularization in tumor microenvironment. To identify key signaling pathways that have a role in GaM-mediated reduction of tumor growth, we analyzed inflammatory cytokines, as well as signal transduction pathways in CTCL cells treated by GaM. IFN-γ-induced chemokines and IL-13 were found to be notably increased in GaM-treated CTCL cells. However, immunosuppressive cytokines, such as IL-10, were decreased with GaM treatment. Interestingly, both oxidative stress and p53 pathways were involved in GaM-induced cytotoxicity. These results warrant further investigation of GaM as a therapeutic agent for CTCLs.

Andrographolide induces apoptosis of C6 glioma cells via the ERK-p53-caspase 7-PARP pathway

BACKGROUND

Glioma is the most malignant tumor of the central nervous system. Efforts on the development of new chemotherapy are mandatory. Andrographolide (AND), a diterpenoid lactone isolated from the Andrographis paniculata, has been shown to have antitumor activities in several types of cancer cells. Whether AND can exert its antitumor activity in glioblastoma cells remains unknown. This study examined the anticancer effects of AND, both in vitro and in vivo.

METHODS

Cell apoptosis was assayed by flow cytometry and nuclear staining. The signaling pathway for AND was determined by western blotting. The effects of AND on tumor growth was evaluated in a mouse model.

RESULTS AND CONCLUSION

In vitro, with application of specific inhibitors and siRNA, AND-induced apoptosis was proven through ROS-ERK-P53-caspase 7-PARP signaling pathway. In vivo, AND significantly retarded tumor growth and caused regression of well-formed tumors in vivo. Furthermore, AND did not induce apoptosis or activate ERK and p53 in primary cultured astrocyte cells, and it may serve as a potential therapeutic candidate for the treatment of glioma.

Depletion of M2-like tumor-associated macrophages delays cutaneous T-cell lymphoma development in vivo

Macrophages have key roles in tumor development and invasion in several human cancers, but little is known about their pathogenic role in cutaneous T-cell lymphoma (CTCL). Herein, we used PCR arrays to profile the expression of inflammatory cytokines in 12 patients with mycosis fungoides (MF), the most common variant of CTCL. Compared with normal controls, MF skin displayed increased mRNA levels of macrophage-related cytokines. Moreover, we detected CD163, a reliable marker of tumor-associated macrophages, in the tumor microenvironment of MF biopsies. To demonstrate that macrophages had a role in CTCL tumorigenesis, we xenografted human CTCL tumor cells in immunocompromised mice and compared tumor development using clodronate-containing liposomes to deplete macrophages in mice. Mice treated with clodronate-containing liposomes show markedly less tumor growth compared with mice treated with phosphate-buffered saline-containing liposomes (P<0.001). We also noted a strong correlation between macrophage depletion and decreased expression of vascular marker, CD31, and lymphatic marker, podoplanin, suggesting a role for macrophages in angiogenesis. In vitro, clodronate-containing liposomes killed activated murine M2 macrophages, but not Hut78 cells, demonstrating selective ability to induce apoptosis in macrophages. Our data indicate that macrophages have a critical role in the progression of Hut78 cell tumor formation in skin, thus providing a new therapeutic strategy for CTCL.

Association of the numbers of CD163(+) cells in lesional skin and serum levels of soluble CD163 with disease progression of cutaneous T cell lymphoma

BACKGROUND

Classically activated macrophages produce IL-12, IL-23, and TNF-α, whereas alternatively activated macrophages (M2 cells) produce IL-10 and express several receptors such as mannose receptor and CD163. Tumor-associated macrophages exhibit M2 phenotype, whose presence has been associated with poor prognosis in various tumors.

OBJECTIVES

To investigate distribution of CD163(+) cells in lesional skin and serum levels of soluble CD163 (sCD163) in patients with cutaneous T cell lymphoma (CTCL), atopic dermatitis (AD), or psoriasis.

METHODS

The numbers of CD163(+) and CD68(+) cells in lesional skin of CTCL, AD, or psoriasis, and in normal skin were examined by immunohistochemistry. Serum soluble CD163 (sCD163) levels were quantified by enzyme-linked immunosorbent assay.

RESULTS

The numbers of CD163(+) cells in lesional skin of CTCL, AD, or psoriasis were significantly larger than in normal skin. In CTCL, the numbers of CD163(+) or CD68(+) cells increased as more tumor cells infiltrated and they decreased after treatment with topical steroid and ultraviolet light. Moreover, CTCL patients with an increased number of CD163(+) cells showed worse prognosis. Serum sCD163 levels in patients with CTCL, AD, or psoriasis were significantly higher than those in normal controls. In CTCL patients, serum sCD163 levels significantly correlated with serum soluble interleukin-2 receptor and CCL17 levels. In AD patients, serum sCD163 levels correlated with serum IgE levels.

CONCLUSION

The numbers of CD163(+) cells in lesional skin and serum sCD163 levels were associated with disease progression of CTCL. Further study focusing on CD163(+) cells in CTCL lesional skin would be an interesting research field.

Mast cells play a protumorigenic role in primary cutaneous lymphoma

Primary cutaneous lymphomas (PCLs) are clonal T- or B-cell neoplasms, which originate in the skin. In recent years, mast cells were described as regulators of the tumor microenvironment in different human malignancies. Here, we investigated the role of mast cells in the tumor microenvironment of PCL. We found significantly increased numbers of mast cells in skin biopsies from patients with cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (CBCL). Mast cell infiltration was particularly prominent in the periphery, at lymphoma rims. Interestingly, CTCL and CBCL patients with a progressive course showed higher mast cell counts than stable patients, and mast cell numbers in different stages of CTCL correlated positively with disease progression. In addition, mast cell numbers positively correlated with microvessel density. Incubating primary CTCL cells with mast cell supernatant, we observed enhanced proliferation and production of cytokines. In line with our in vitro experiments, in a mouse model of cutaneous lymphoma, tumor growth in mast cell-deficient transgenic mice was significantly decreased. Taken together, these experiments show that mast cells play a protumorigenic role in CTCL and CBCL. Our data provide a rationale for exploiting tumor-associated mast cells as a prognostic marker and therapeutic target in PCL.