Resistance to Activation-Induced Cell Death and Bystander Cytotoxicity Via the Fas/Fas Ligand Pathway Are Implicated in the Pathogenesis of Cutaneous T Cell Lymphomas

The Tumor Microenvironment as a Therapeutic Target in Cutaneous T Cell Lymphoma

Cutaneous T cell lymphomas (CTCLs) are a heterogeneous group of non-Hodgkin lymphomas, with mycosis fungoides and Sézary syndrome being the two common subtypes. Despite the substantial improvement in early-stage diagnosis and treatments, some patients still progress to the advanced stage with an elusive underpinning mechanism. While this unsubstantiated disease mechanism coupled with diverse clinical outcomes poses challenges in disease management, emerging evidence has implicated the tumor microenvironment in the disease process, thus revealing a promising therapeutic potential of targeting the tumor microenvironment. Notably, malignant T cells can shape their microenvironment to dampen antitumor immunity, leading to Th2-dominated responses that promote tumor progression. This is largely orchestrated by alterations in cytokines expression patterns, genetic dysregulations, inhibitory effects of immune checkpoint molecules, and immunosuppressive cells. Herein, the recent insights into the determining factors in the CTCL tumor microenvironment that support their progression have been highlighted. Also, recent advances in strategies to target the CTCL tumor micromovement with the rationale of improving treatment efficacy have been discussed.

Evaluation of Sézary cell marker expression and cell death behaviour upon in vitro treatment by flow cytometry in Sézary syndrome patients

The diagnosis of Sézary syndrome (SS) relies on the identification of blood Sézary cells (SC) by different markers via flow cytometry. Treatment of SS is challenging since its pathogenesis is characterized by cell death resistance rather than hyperproliferation. In this study, we establish an integrated approach that considers both the expression of SC markers and sensitivity to cell death both spontaneously and upon in vitro treatment. Peripheral blood mononuclear cells were isolated from 20 SS patients and analysed for the SC markers CD7 and CD26 loss as well as CD158k and PD1 gain. The cells were then treated with different established and experimental therapies in vitro and cell death was measured. Spontaneous and therapeutically induced cell death were measured and correlated to cellular marker profiles. In the marker-positive cells, spontaneous cell death sensitivity was reduced. Different treatments in vitro managed to specifically induce cell death in the putative CTCL cell populations. Interestingly, a repeated analysis after 3 months of treatment revealed the CTCL cell death sensitivity to be restored by therapy. We propose this novel integrated approach comprising the evaluation of SC marker expression and analysis of cell death sensitivity upon treatment that can also enable a better therapy stratification.

What Does the Future Hold for Biomarkers of Response to Extracorporeal Photopheresis for Mycosis Fungoides and Sézary Syndrome?

Extracorporeal photopheresis (ECP) is an FDA-approved immunotherapy for cutaneous T-cell lymphoma, which can provide a complete response in some patients. However, it is still being determined who will respond well, and predictive biomarkers are urgently needed to target patients for timely treatment and to monitor their response over time. The aim of this review is to analyze the current state of the diagnostic, prognostic, and disease state-monitoring biomarkers of ECP, and outline the future direction of the ECP biomarker discovery. Specifically, we focus on biomarkers of response to ECP in mycosis fungoides and Sézary syndrome. The review summarizes the current knowledge of ECP biomarkers, including their limitations and potential applications, and identifies key challenges in ECP biomarker discovery. In addition, we discuss emerging technologies that could revolutionize ECP biomarker discovery and accelerate the translation of biomarker research into clinical practice. This review will interest researchers and clinicians seeking to optimize ECP therapy for cutaneous T-cell lymphoma.

Epigenetics of cutaneous T-cell lymphoma: biomarkers and therapeutic potentials

Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of skin-homing non-Hodgkin lymphomas. There are limited options for effective treatment of patients with advanced-stage CTCL, leading to a poor survival rate. Epigenetics plays a pivotal role in regulating gene expression without altering the DNA sequence. Epigenetic alterations are involved in virtually all key cancer-associated pathways and are fundamental to the genesis of cancer. In recent years, the epigenetic hallmarks of CTCL have been gradually elucidated and their potential values in the diagnosis, prognosis, and therapeutic intervention have been clarified. In this review, we summarize the current knowledge of the best-studied epigenetic modifications in CTCL, including DNA methylation, histone modifications, microRNAs, and chromatin remodelers. These epigenetic regulators are essential in the development of CTCL and provide new insights into the clinical treatments of this refractory disease.

Cellular Interactions and Inflammation in the Pathogenesis of Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) comprises a group of lymphoproliferative diseases characterized by the accumulation of malignant T cells in chronically inflamed skin lesions. In early stages, the disease presents as skin patches or plaques covering a limited area of the skin and normally follows an indolent course. However, in a subset of patients the cutaneous lesions develop into tumors and the malignant T cells may spread to the lymphatic system, blood and internal organs with fatal consequences. Despite intensive research, the mechanisms driving disease progression remain incompletely understood. While most studies have focused on cancer cell-intrinsic oncogenesis, such as genetic and epigenetic events driving malignant transformation and disease progression, an increasing body of evidence shows that the interplay between malignant T cells and non-malignant cells plays a crucial role. Here, we outline some of the emerging mechanisms by which tumor, stromal and epidermal interactions may contribute to the progression of CTCL with particular emphasis on the crosstalk between fibroblasts, keratinocytes and malignant T cells.

JNK1 and ERK1/2 modulate lymphocyte homeostasis via BIM and DRP1 upon AICD induction

The Activation-Induced Cell Death (AICD) is a stimulation-dependent form of apoptosis used by the organism to shutdown T-cell response once the source of inflammation has been eliminated, while allowing the generation of immune memory. AICD is thought to progress through the activation of the extrinsic Fas/FasL pathway of cell death, leading to cytochrome-C release through caspase-8 and Bid activation. We recently described that, early upon AICD induction, mitochondria undergo structural alterations, which are required to promote cytochrome-C release and execute cell death. Here, we found that such alterations do not depend on the Fas/FasL pathway, which is instead only lately activated to amplify the cell death cascade. Instead, such alterations are primarily dependent on the MAPK proteins JNK1 and ERK1/2, which, in turn, regulate the activity of the pro-fission protein Drp1 and the pro-apoptotic factor Bim. The latter regulates cristae disassembly and cooperate with Drp1 to mediate the Mitochondrial Outer Membrane Permeabilization (MOMP), leading to cytochrome-C release. Interestingly, we found that Bim is also downregulated in T-cell Acute Lymphoblastic Leukemia (T-ALL) cells, this alteration favouring their escape from AICD-mediated control.

Analysis of the Effect of Gentian Violet on Apoptosis and Proliferation in Cutaneous T-Cell Lymphoma in an In Vitro Study

Importance

Triggering the extrinsic apoptotic pathway is an effective way to kill cutaneous T-cell lymphoma (CTCL) cells in vitro and ex vivo.

Objective

To compare small molecules that induce extrinsic apoptosis in CTCL to identify and analyze compounds that induce high levels of tumor cell death and block tumor cell growth.

Design, Setting, and Participants

From November 5, 2014, to January 30, 2018, this study performed high-throughput small molecule screening of 1710 compounds followed by detailed analysis of the ability of gentian violet (GV) to promote apoptosis and inhibit proliferation of CTCL cells.

Exposures

In vitro and ex vivo analyses using enzyme-linked immunosorbent assays, flow cytometry, and immunoblotting.

Main Outcomes and Measures

Apoptosis, cleaved caspases, extrinsic apoptotic death receptors and ligands, cell proliferation, nuclear factor-κB expression, and other factors.

Results

This study used high-throughput screening to detect cleaved caspase 8 induced in CTCL cells by 1710 unique compounds. The nonprescription, topical antimicrobial remedy GV induced more total apoptosis than did nitrogen mustard (mechlorethamine). Furthermore, GV induced 4 to 6 times greater apoptosis in CTCL lines than in normal keratinocytes, suggesting a favorable topical toxicity profile. In addition to increasing caspase 8, GV also upregulated death receptors 4 and 5, tumor necrosis factor (TNF)-related apoptosis-inducing ligand, and Fas ligand but not the Fas receptor, TNF receptor, or TNF-α ligand. These results are consistent with induction of extrinsic apoptosis via the Fas and TNF-related apoptosis-inducing ligand pathways. Increased phosphorylation of phospholipase C-γ1, Ca2+ influx, and reactive oxygen species were also detected, indicating that the mechanism of Fas ligand upregulation involves key elements of the activation-induced cell death pathway. In ex vivo studies, 1-μmol/L GV induced up to 90% CTCL apoptosis in Sézary blood cells. In addition, GV reduced expression of antiapoptotic myeloid cell leukemia 1 and proproliferative nuclear factor-κB components and increased inhibitory κB levels. This finding was associated with cell cycle arrest and reduced CTCL tumor cell proliferation. Furthermore, the CTCL killing associated with GV was augmented when used in combination with methotrexate.

Conclusions and Relevance

This study found that GV attacked tumor viability and growth in CTCL. Although purple at neutral pH, GV can be rendered colorless by altering its pH. These preclinical findings may help to broaden knowledge of the antineoplastic features of GV and provide a rationale for clinical studies of its use as a novel, inexpensive, topical therapy for CTCL that is available worldwide.

Combined inhibition of Bcl-2 and NFκB synergistically induces cell death in cutaneous T-cell lymphoma

Therapeutic options for cutaneous T-cell lymphoma (CTCL) are limited and curative treatment regimens are not available. Thus, new targeted and well-tolerated therapeutic approaches are urgently needed. In this respect, we have recently shown that dimethyl fumerate (DMF) inhibits NF-κB acting as a survival factor in CTCL. Similarly, inhibition of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) has been shown to induce cell death in CTCL especially when combined with histone deacetylase inhibitors. Therefore, we hypothesized that inhibition of Bcl-2 should potentiate NF-κB inhibition in a novel combination treatment of CTCL. We show that, in vitro, the Bcl-2 inhibitors ABT-199 and ABT-263 induced specific cell death in primary CD4⁺ cells from CTCL patients as well as in the CTCL cell line SeAx, but not in T cells of healthy donors nor in the CTCL cell line HH, which lacks Bcl-2. Combined treatment with ABT-199 and DMF caused synergistic cell death specifically in CTCL cells engaging 2 independent signaling pathways. To verify these findings in vivo, we performed combined ABT-199 and DMF treatment in a xenograft mouse model for CTCL. The combined treatment effectively reduced tumor growth and increased overall survival via synergistic induction of CTCL cell death and suppression of tumor cell proliferation. Essentially, the combination treatment was superior to ABT-199 monotherapy with respect to both efficacy and tolerability. To sum up, our data provide proof of principle for the therapeutic potential of combining Bcl-2 and NF-κB inhibitors in treating CTCL. Next, this potential should be explored further in a clinical study.

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.

Malignant inflammation in cutaneous T-cell lymphoma-a hostile takeover

Cutaneous T-cell lymphomas (CTCL) are characterized by the presence of chronically inflamed skin lesions containing malignant T cells. Early disease presents as limited skin patches or plaques and exhibits an indolent behavior. For many patients, the disease never progresses beyond this stage, but in approximately one third of patients, the disease becomes progressive, and the skin lesions start to expand and evolve. Eventually, overt tumors develop and the malignant T cells may disseminate to the blood, lymph nodes, bone marrow, and visceral organs, often with a fatal outcome. The transition from early indolent to progressive and advanced disease is accompanied by a significant shift in the nature of the tumor-associated inflammation. This shift does not appear to be an epiphenomenon but rather a critical step in disease progression. Emerging evidence supports that the malignant T cells take control of the inflammatory environment, suppressing cellular immunity and anti-tumor responses while promoting a chronic inflammatory milieu that fuels their own expansion. Here, we review the inflammatory changes associated with disease progression in CTCL and point to their wider relevance in other cancer contexts. We further define the term "malignant inflammation" as a pro-tumorigenic inflammatory environment orchestrated by the tumor cells and discuss some of the mechanisms driving the development of malignant inflammation in CTCL.

Genomic profiling of Sézary syndrome identifies alterations of key T cell signaling and differentiation genes

Sézary syndrome is a rare leukemic form of cutaneous T cell lymphoma characterized by generalized redness, scaling, itching and increased numbers of circulating atypical T lymphocytes. It is rarely curable, with poor prognosis. Here we present a multiplatform genomic analysis of 37 patients with Sézary syndrome that implicates dysregulation of cell cycle checkpoint and T cell signaling. Frequent somatic alterations were identified in TP53, CARD11, CCR4, PLCG1, CDKN2A, ARID1A, RPS6KA1 and ZEB1. Activating CCR4 and CARD11 mutations were detected in nearly one-third of patients. ZEB1, encoding a transcription repressor essential for T cell differentiation, was deleted in over one-half of patients. IL32 and IL2RG were overexpressed in nearly all cases. Our results demonstrate profound disruption of key signaling pathways in Sézary syndrome and suggest potential targets for new therapies.

NSAID-manufacturing plant effluent induces geno- and cytotoxicity in common carp (Cyprinus carpio)

The pharmaceutical industry generates wastewater discharges of varying characteristics and contaminant concentrations depending on the nature of the production process. The main chemicals present in these effluents are solvents, detergents, disinfectants - such as sodium hypochlorite (NaClO) - and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the geno- and cytotoxicity induced in the common carp Cyprinus carpio by the effluent emanating from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. Carp were exposed to the lowest observed adverse effect level (LOAEL, 0.1173%) for 12, 24, 48, 72 and 96 h, and biomarkers of genotoxicity (comet assay and micronucleus test) and cytotoxicity (caspase-3 activity and TUNEL assay) were evaluated. A significant increase with respect to the control group (p<0.05) occurred with all biomarkers from 24h on. Significant positive correlations were found between NSAID concentrations and biomarkers of geno- and cytotoxicity, as well as among geno- and cytotoxicity biomarkers. In conclusion, exposure to this industrial effluent induces geno- and cytotoxicity in blood of C. carpio.

The effect of extracorporeal photopheresis alone or in combination therapy on circulating CD4(+) Foxp3(+) CD25(-) T cells in patients with leukemic cutaneous T-cell lymphoma

PURPOSE

Extracorporeal photopheresis (ECP) alone or in combination therapy is effective for treatment of leukemic cutaneous T-cell lymphoma (L-CTCL), but its mechanism(s) of action remain unclear. This study was designed to investigate the effect of ECP on regulatory T cells and CD8(+) T cells in L-CTCL patients.

EXPERIMENTAL DESIGN

Peripheral blood from 18 L-CTCL patients at baseline, Day 2, 1 month, 3 month, and 6 month post-ECP therapy was analyzed by flow cytometry for CD4(+) CD25(+/high) , CD4(+) Foxp3(+) CD25(+/-) , CD3(+) CD8(+) , CD3(+) CD8(+) CD69(+) , and CD3(+) CD8(+) IFN-γ(+) T cells. Clinical responses were assessed and correlated with changes in these T-cell subsets.

RESULTS

Twelve of 18 patients achieved clinical responses. The average baseline number of CD4(+) CD25(+/high) T cells of PBMCs in L-CTCL patients was normal (2.2%), but increased at 6-month post-therapy (4.3%, P < 0.01). The average baseline number of CD4(+) Foxp3(+) T cells out of CD4(+) T cells in nine evaluable patients was high (66.8 ± 13.7%), mostly CD25 negative. The levels of CD4(+) Foxp3(+) T cells in responders were higher (n = 6, 93.1 ± 5.7%) than nonresponders (n = 3, 14.2 ± 16.0%, P < 0.01), and they declined in parallel with malignant T cells. The numbers of CD3(+) CD8(+) CD69(+) and CD3(+) CD8(+) IFN-γ(+) T cells increased at 3-month post-therapy in five of six patients studied.

CONCLUSIONS

Extracorporeal photopheresis alone or in combination therapy might be effective in L-CTCL patients whose malignant T cells have a CD4(+) Foxp3(+) CD25(-) phenotype.

SIRT1 is upregulated in cutaneous T-cell lymphoma, and its inhibition induces growth arrest and apoptosis

Silent information regulator type-1 (SIRT1) is the best-studied member of the Sirtuin (Sir2) family of nicotinamide dinucleotide (NAD)-dependent class III histone deacetylases (HDACs), but has not yet been explored in cutaneous T-cell lymphoma (CTCL). We analyzed five CTCL cell lines and lesional tissues using flow cytometry, immunostaining, immunoblotting, cell death, viability, and apoptosis assays, small-molecule inhibitors, and shRNA knockdown. We found strong SIRT1 expression among CTCL lines relative to normal lymphocytes. CTCL cells in lesional tissues also expressed SIRT1 strongly. SIRT1 knockdown resulted in reduced cellular metabolism and proliferation, increased apoptosis, and PARP cleavage products. Tenovin-1, which reversibly inhibits class III HDACs (SIRT1 and SIRT2), reduced SIRT enzymatic activity and SIRT1 expression and led to increased apoptosis. These alterations were accompanied by increased forkhead box O3 (FoxO3) in several cell lines and increased nuclear p53, as well as acetylated p53 in wtp53 MyLa CTCL line. A combination of class I/II and class III HDACIs (vorinostat and tenovin-1) produced significantly greater growth inhibition, cell death via apoptosis, as well as superior p53 promoter upregulation in wtp53 MyLa cells as compared with either agent alone. This occurred in a partially p53-dependent manner, as these effects were blunted by p53 knockdown. Our results indicate that SIRT1 is strongly expressed in CTCL. Its inhibition results in reduced growth and increased apoptosis of CTCL cells. Furthermore, our findings suggest that some CTCL patients, such as those with wtp53, might benefit more from treatment with a combination of different classes of HDACIs than with a single agent.

Suppression of endogenous hydrogen sulfide contributes to the radiation-induced bystander effects on hypoxic HepG2 cells

Radiation-induced bystander effects may have important implications in radiotherapy, but it is still not well known if radiation-induced bystander effects can be triggered in hypoxic tumor cells and what are the related bystander signals. Using human hepatoma cells of HepG2, the present study found that micronuclei (MN) could be induced in the nonirradiated cells after treatment with conditioned medium (CM) harvested from irradiated cells under hypoxic conditions. Bystander effects were diminished when the irradiated cells were pretreated with sodium hydrosulfide (NaHS, an exogenous H(2)S donor) (≤100 μM). However, the bystander effects were increased when the irradiated cells were pretreated with an inhibitor of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), the synthases of endogenous hydrogen sulfide (H(2)S). Western blotting showed that the expressions of CSE and CBS were increased in the irradiated hypoxic cells, but were reduced in the CM treated bystander cells. The ratio of Bcl-2/Bax, a molecular marker of apoptosis, decreased with CM treatment time. However, the activity of caspase-3 increased in the hypoxic bystander cells, and this could be regulated by both NaHS and the inhibitor of endogenous H(2)S. These results demonstrate that under hypoxic conditions irradiated hepatoma cells induce bystander responses by depressing the generation of endogenous H(2)S and altering Bcl-2/Bax ratios as well as caspase-3 dependent damage in the bystander cells.

Hydrochlorothiazide and cutaneous T cell lymphoma: prospective analysis and case series

BACKGROUND

Mycosis fungoides (MF) and leukemic Sézary syndrome (SS) are the most common cutaneous T cell lymphomas (CTCL), but their etiology remains unknown. After patients were observed with hydrochlorothiazide (HCTZ)-associated CTCL, HCTZ was examined as a putative chronic antigen in a cohort of prospectively staged patients.

METHODS

Demographic and drug exposure data was examined from 1443 confirmed MF and SS patients. Hypertensive CTCL patients were divided into HCTZ users or nonusers for statistical analysis by chi-square and t tests. Causality in a case series was rated by the Naranjo Adverse Drug Reaction Probability Scale.

RESULTS

A total of 815 of 1443 MF and SS patients (56.5%) were hypertensive; 205 (25.2%) were taking HCTZ at initial staging. Comparing stage of patients who were using or not using HCTZ, the most significant difference was between stage I and stage IV (odds ratio of 0.45; 95% confidence interval of 0.25-0.78, P = .003), demonstrating reduced likelihood of being stage IV in patients who were on HCTZ. Seventy-seven percent of the MF patients on HCTZ were stage I. A total of 125 patients of 196 (63.8%) started HCTZ prior to developing CTCL lesions, and 35 of 121 (28.0%) started within 1 year of first skin rash. Thirty-six of 125 patients (28.8%) experienced complete or partial remissions after discontinuing HCTZ. A monoclonal T cell receptor rearrangement was detected more frequently in the hypertensive stage I patients not taking HCTZ as compared with those who were (55.3% vs 69.1%, P = .032). Three patients were rechallenged and developed MF lesions that resolved or improved with discontinuation.

CONCLUSIONS

HCTZ is commonly prescribed and may be a putative antigen in a small subset of early MF patients. Careful drug histories and a trial off medication are warranted.

Increased Twist expression in advanced stage of mycosis fungoides and Sézary syndrome

BACKGROUND

The mechanisms of tumor progression in mycosis fungoides (MF) and Sézary syndrome (SS) are poorly understood. Twist, a transcription factor, is thought to promote solid tumor progression by blocking p53 and inhibiting c-myc-induced apoptosis. Whether Twist expression is correlated to MF/SS stages remains unknown.

METHODS

Twist, c-myc and p53 proteins in 68 MF/SS lesions across all T stages were examined by immunohistochemistry, and mRNA levels in peripheral blood CD4+ T-cells from SS patients were measured by real-time quantitative polymerase chain reaction.

RESULTS

Positive staining for Twist was found in 12.5% (2/16) of T1 and 33.3% (7/21) of T2 early stage patches/plaques compared to 50.0% (9/18) of T3 tumors and 84.6% (11/13) of T4 erythroderma. Most T4 erythroderma were positive for Twist in dermal lymphocytes, with the strongest staining. Positive staining for c-myc was higher in T3/T4 lesions (29/31, 93.5%) than T1/T2 lesions (25/37, 67.6%, p < 0.05), with strongest staining in T3 tumors. Aberrant p53 expression was more common in T3/T4 lesions (8/31, 25.8%) than in T1/T2 lesions (2/37, 5.4%, p < 0.05). Twist mRNA was detected in all CD4+ T cells from SS patients but not in normal donors.

CONCLUSIONS

Increased Twist protein expression in advanced MF/SS lesions suggests that Twist expression may correlate with MF/SS stages.

HDAC inhibitors for the treatment of cutaneous T-cell lymphomas

Epigenetic modification by small-molecule histone deacetylase inhibitors (HDAC-Is) has been a promising new antineoplastic approach for various solid and hematological malignancies, particularly for cutaneous T-cell lymphoma (CTCL). Vorinostat, a pan-HDAC-I and, most recently, romidepsin, a bicyclic pan-HDAC-I, have been US FDA approved for treatment of relapsed or refractory CTCL. However, because many patients do not reach the 50% partial response mark and response is not always sustainable, overcoming HDAC-I resistance by adding other agents or finding more selective molecules is an important clinical problem in realizing the full clinical potential of HDAC-Is. In this review, we discuss the molecular basis for HDAC-I function in cancer, the clinical response and side-effect profile experienced by CTCL patients, and the progress made in attempting to identify biomarkers of response and resistance, as well as synergistic combination therapies.

Loss of nuclear pro-IL-16 facilitates cell cycle progression in human cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCLs) represent a heterogeneous group of non-Hodgkin lymphomas that affect the skin. The pathogenesis of these conditions is poorly understood. For example, the signaling mechanisms contributing to the dysregulated growth of the neoplastic T cells are not well defined. Here, we demonstrate that loss of nuclear localization of pro-IL-16 facilitates CTCL cell proliferation by causing a decrease in expression of the cyclin dependent-kinase inhibitor p27Kip1. The decrease in p27Kip1 expression was directly attributable to an increase in expression of S-phase kinase-associated protein 2 (Skp2). Regulation of Skp2 is in part attributed to the nuclear presence of the scaffold protein pro-IL-16. T cells isolated from 11 patients with advanced CTCL, but not those from healthy controls or patients with T cell acute lymphocytic leukemia (T-ALL), demonstrated reduction in nuclear pro-IL-16 levels. Sequence analysis identified the presence of mutations in the 5' end of the PDZ1 region of pro-IL-16, a domain required for association of pro-IL-16 with the nuclear chaperone HSC70 (also known as HSPA8). HSC70 knockdown led to loss of nuclear translocation by pro-IL-16 and subsequent increases in Skp2 levels and decreases in p27Kip1 levels, which ultimately enhanced T cell proliferation. Thus, our data indicate that advanced CTCL cell growth is facilitated, at least in part, by mutations in the scaffold protein pro-IL-16, which directly regulates Skp2 synthesis.

Over-expressed Fas improves the apoptosis of malignant T-cells in vitro and vivo

Fas play a critical role in T-cell apoptosis by functioning as a major cell-surface death receptor. To explore a potential method that can improve the sensitivity to Fas-mediated apoptosis in malignant precursor T-cells. Fas gene was stable transfected into Jurkat cells to establish a new cell line named Jurkat-Fas with over-expressed Fas. RT-PCR, real-time RT-PCR, flow cytometry, and confocal microscopy assay were performed to detect the Fas level of mRNA and protein in the two cell lines. The sensitivities to Fas-mediated apoptosis of the two cell lines were evaluated by flow cytometry with Alexa Fluor 488 annexin V/PI staining in vitro. Tumor xenograft models were prepared with Jurkat and Jurkat-Fas cells for in vivo study. Fas mRNA and protein levels in Jurkat-Fas cell line were higher than that in Jurkat cell line. Compared to Jurkat cells, apoptosis rates of Jurkat-Fas cells were remarkably higher in vitro, and the tumor growth of Jurkat-Fas cells in nude mice was significantly inhibited in vivo. Stable over-expression of extrinsic Fas gene can significantly ameliorate the sensitivity to Fas-mediated apoptosis in human malignant T-cell, which indicates a novel strategy to improve therapeutic effects on precursor T-cell malignancy.

Deficiency of SATB1 expression in Sezary cells causes apoptosis resistance by regulating FasL/CD95L transcription

Sézary syndrome (SS) is an aggressive subtype of cutaneous T-cell lymphoma that is characterized by circulating leukemic Sézary cells. The accumulation of these malignant cells has been shown to be the result of the resistance to apoptosis, in particular, activation-induced cell death. However, the mechanism of apoptosis resistance remains unknown. By characterizing the gene transcription profiles of purified CD4(+)CD7(-) Sézary cells from patients with SS and cultured Sézary cells, it was found that Sézary cells are deficient in the expression of special AT-rich region binding protein 1 (SATB1), a key regulator of T-cell development and maturation. Retrovirus-mediated gene transduction revealed that SATB1 restoration in cultured Sézary cells (Hut78) triggered spontaneous cell death and sensitized Hut78 cells to activation-induced cell death, with associated activation of caspase 8 and caspase 3. Furthermore, endogenous expression of FasL in Sézary cells was increased in transcriptional and translational levels on restoration of SATB1 expression in cultured Sézary cells. These results suggest that deficiency in SATB1 expression in Sézary cells plays an important role in SS pathogenesis by causing apoptosis resistance. Thus, restoration of SATB1 expression may represent a potential molecular targeted therapy for SS, which does not have a cure at present.

Programmed cell death-10 enhances proliferation and protects malignant T cells from apoptosis

The programmed cell death-10 (PDCD10; also known as cerebral cavernous malformation-3 or CCM3) gene encodes an evolutionarily conserved protein associated with cell apoptosis. Mutations in PDCD10 result in cerebral cavernous malformations, an important cause of cerebral hemorrhage. PDCD10 is associated with serine/threonine kinases and phosphatases and modulates the extracellular signal-regulated kinase pathway suggesting a role in the regulation of cellular growth. Here we provide evidence of a constitutive expression of PDCD10 in malignant T cells and cell lines from peripheral blood of cutaneous T-cell lymphoma (Sezary syndrome) patients. PDCD10 is associated with protein phosphatase-2A, a regulator of mitogenesis and apoptosis in malignant T cells. Inhibition of oncogenic signal pathways [Jak3, Notch1, and nuclear factor-κB (NF-κB)] partly inhibits the constitutive PDCD10 expression, whereas an activator of Jak3 and NF-κB, interleukin-2 (IL-2), enhances PDCD10 expression. Functional data show that PDCD10 depletion by small interfering RNA induces apoptosis and decreases proliferation of the sensitive cells. To our knowledge, these data provide the first functional link between PDCD10 and cancer.

Increased programmed death-1 expression on CD4+ T cells in cutaneous T-cell lymphoma: implications for immune suppression

OBJECTIVES

To investigate the expression profile of programmed death-1 (PD-1) on T cells derived from patients with cutaneous T-cell lymphoma (CTCL), analyze a potential mechanism responsible for upregulation of PD-1, and assess the correlation between blockade of its signaling pathway and improvement in immunological function.

DESIGN

Translation research study.

SETTING

University medical center.

PARTICIPANTS

Patients with Sézary syndrome, patients with mycosis fungoides, and healthy volunteers.

MAIN OUTCOME MEASURES

Programmed death-1 expression on T cells by flow cytometry and interferon γ (IFN-γ) production by enzyme-linked immunosorbent assay.

RESULTS

We report significantly increased PD-1 expression on CD4(+) T cells from patients with Sézary syndrome compared with CD4(+) T cells from patients with mycosis fungoides and healthy volunteers. Both CD26(-) and CD26(+) populations of CD4(+) T cells demonstrated increased expression of PD-1, which was upregulated by the engagement of the T-cell receptor with anti-CD3/CD28 antibodies. In addition, blockade of the signaling pathway with blocking antibodies to PD-1 or its ligand PD-L1 led to an increase in the capacity to produce IFN-γ among some patients. Finally, longitudinal studies of 1 patient revealed a progressive decrease in PD-1 expression on CD4(+) T cells with improvement of clinical disease.

CONCLUSION

Our data imply that increased PD-1 expression in Sézary syndrome may play a role in attenuating the immune response and provide further insight into the immunosuppressive nature of CD4(+) T cells in Sézary syndrome and suggest another potential means of targeted therapy for these patients.

STAT3 knockdown by siRNA induces apoptosis in human cutaneous T-cell lymphoma line Hut78 via downregulation of Bcl-xL

Cutaneous T-cell lymphomas (CTCLs) are non-Hodgkin's lymphomas resulting from clonal expansion and localization of malignant T-lymphocytes to the skin. CTCL cells have defective apoptosis. Signal transducers and activators of transcription (STAT) are a family of transcription factors known to play important roles in the development and progression of several human cancers by promoting cell proliferation and protecting against apoptosis. In this study, we investigated the specific role of STAT3, a major component of the STAT family, in growth and survival of human CTCL cell line Hut78. Western immunoblot analysis showed elevated expression of STAT3 and phospho-STAT3(Y705) in human CTCL cells as compared to freshly isolated peripheral blood lymphocytes (PBLs). Specific knockdown of STAT3 expression in Hut78 cells by RNA interference induced morphological and biochemical changes indicating apoptotic cell death. Moreover, STAT3 inhibition downregulated the expression of Bcl2 family of anti-apoptotic gene Bcl-xL. These observations suggest that STAT3 is required for the survival of CTCL cells and strongly indicate that targeting STAT3 using siRNA techniques may serve a novel therapeutic strategy for the treatment of CTCL.

Low FAS/CD95 expression by CTCL correlates with reduced sensitivity to apoptosis that can be restored by FAS upregulation

FAS expression was generally low in 30 of 31 cutaneous T-cell lymphoma (CTCL) cases (mycosis fungoides/Sezary syndrome, SS) as well as in 5 of 6 large plaque parapsoriasis cases (a CTCL precursor). To investigate this phenomenon, we explored FAS transcript levels, cell-surface FAS protein expression and susceptibility to FAS-mediated apoptosis in four CTCL lines (MyLa, HH, SZ4, and SeAx), freshly isolated leukemic cells from a patient with SS, an acute lymphoblastic leukemia T-cell line (Jurkat), and JFL (a FAS-low variant of Jurkat). Results confirmed low FAS expression by the leukemic SS cells, HH, SZ4, SeAx, and JFL relative to normal peripheral blood mononuclear leukocytes and the other cell lines. There was a direct correlation among FAS transcript level, FAS protein level, and FAS-mediated apoptotic sensitivity in the CTCL samples. When the FAS-deficient cell lines were transfected with a wild-type FAS construct, FAS expression and sensitivity to FAS-mediated apoptosis were restored. In aggregate, these findings provide evidence that like normal T cells, CTCL cells exhibit a mechanistic connection between transcriptional regulation of FAS and sensitivity to FAS-mediated apoptosis, point to the development of FAS deficiency as one molecular mechanism responsible for acquired resistance to apoptosis in CTCL, and indicate that upregulation of FAS expression can restore sensitivity to apoptosis.

Optimizing denileukin diftitox (Ontak®) therapy

Denileukin diftitox (Ontak®) is a novel recombinant fusion protein consisting of peptide sequences for the enzymatically active and membrane translocation domain of diphtheria toxin linked to human IL-2. Denileukin diftitox specifically binds to IL-2 receptors on the cell membrane, is internalized via receptor-mediated endocytosis and inhibits protein synthesis by ADP ribosylation of elongation factor 2, resulting in cell death. This article focuses on the clinical trial that led to the US FDA approval of the drug for cutaneous T-cell lymphoma in 1999, and other investigational studies for hematologic malignancies, recurrent and refractory chronic lymphocytic leukemia, non-Hodgkin B-cell lymphoma, graft-versus-host disease and autoimmune disease, demonstrating the activity and adverse effects of the drug.

Primary Cutaneous Small/Medium CD4+ T-Cell Lymphomas: A Heterogeneous Group of Tumors With Different Clinicopathologic Features and Outcome

Purpose

To define the clinical and pathologic characteristics of primary cutaneous small/medium CD4+ T-cell lymphoma (PCSM-TCL) and identify parameters of prognostic significance.

Patients and Methods

We have investigated 24 patients with primary cutaneous lymphomas composed of small/medium mature T-cells with a βF1, CD3, CD4+ and/or noncytotoxic, CD8– and CD30– phenotype. The proliferation index and CD8+ infiltrating cells were quantified with an automated image analysis system.

Results

Sixteen patients presenting with solitary or localized plaques or small nodules (< 3 cm) had an indolent course. Only three patients experienced repeated cutaneous relapses, and none of them died as a result of the disease after 1 to 168 months (median, 17 months) of follow-up. The tumors had a low proliferation (median Ki-67, 9% ± 5%) and an intense infiltrate of reactive CD8+ (median, 20% ± 11.7%). Five patients presenting with rapidly evolving large tumors or nodules (≥ 5 cm) had an aggressive disease and died with extracutaneous dissemination 18 to 36 months after diagnosis (median, 23 months). These tumors had a significantly higher proliferation (median Ki-67, 22% ± 11.3%; P < .05) and lower number of infiltrating CD8+ (median, 1% ± 3%; P < .05) than the previous group. A third group of three patients had a peculiar clinical presentation with multifocal relapsing lesions without extracutaneous dissemination after a long period of follow-up ranging from 41 to 92 months. Histologically, these cases had an intense infiltrate of eosinophils.

Conclusion

PCSM-TCL is a heterogeneous group of tumors with differentiated clinical and pathological characteristics with impact in the outcome of the patients.

Avicin D selectively induces apoptosis and downregulates p-STAT-3, bcl-2, and survivin in cutaneous T-cell lymphoma cells

Avicin D, a natural triterpenoid saponin, inhibits cell growth and induces apoptosis in transformed tumor cell lines in vitro and mouse skin carcinogenesis models in vivo. To investigate the anti-tumor effects of avicin D in cutaneous T-cell lymphomas (CTCL), we compared three CTCL cell lines and Sézary cells from three Sézary syndrome (SS) patients with normal CD4+ and activated CD4+ T cells from three healthy donors. Avicin D at 0.5-5 mug ml(-1) induced apoptosis in a time- and dose-dependent manner in three cell lines: MJ (-0.2 to 13% and 0.6-37%), Hut78 (2-39% and 3-53%), and HH (13-83% and 44-89%) at 24 and 48 hours, respectively. Avicin D at 0.5-5 microg ml(-1) for 48 hours caused more apoptosis in patients' Sézary cells than in healthy donors' CD4+ T cells and activated CD4+ T cells. The general caspase inhibitor Z-VAD-FMK and caspase-3 inhibitor Z-DEVD-FMK decreased avicin D-induced apoptosis in CTCL cells. Caspase-3 was activated and poly (ADP-ribose) polymerase was cleaved after avicin D treatment. Avicin D did not change the expression of signal transducer and activator of transcription-3 (STAT-3) but decreased phospho-signal transducer and activator of transcription-3 (p-STAT-3) protein levels in all three cell lines and two patients' Sézary cells. Avicin D also decreased expression of the inhibitor of apoptosis protein survivin, the anti-apoptotic protein bcl-2, but not the pro-apoptotic protein bax in these CTCL cells. In summary, avicin D selectively induced apoptosis, inhibited STAT-3 activation, and decreased apoptosis inhibitors (bcl-2 and survivin) in CTCL cell lines and SS patients' Sézary cells. Our findings underlie the therapeutic potential of avicin D in patients with SS.

Resistance to FasL and tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in Sezary syndrome T-cells associated with impaired death receptor and FLICE-inhibitory protein expression

Because of the low proliferative potential of tumor cells in patients with Sézary syndrome (SzS), their accumulation has been suggested to be due to defective regulation of apoptosis. We analyzed the sensitivity to soluble Fas-ligand (FasL) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), 2 members of the TNF superfamily in peripheral blood leukocytes (PBL) from patients with SzS. Compared with healthy donors, CD4(+) cells from patients with SzS were completely resistant to FasL in 9 of 16 cases. Of these 9 FasL-resistant cases, 4 revealed a loss in Fas (CD95) expression, whereas the remaining 5 exhibited normal or enhanced Fas expression. In the latter 5 cases, the apoptosis inhibitor cFLIP was overexpressed in CD4(+)/CD26(-) tumor cells compared with CD4(+)/CD26(-) cells from Fas-expressing FasL-sensitive patients and healthy donors. Furthermore, resistance to TRAIL and tumor cell-restricted loss of TRAIL-receptor 2 were observed in 16 of 16 SzS PBLs. It is noteworthy that resistance to FasL could be overcome by the use of a hexameric FasL or upon exposure of SzS cells to interferon-alpha (IFN-alpha) or IFN-gamma, the latter by an increase of Fas expression. Our data on primary SzS lymphocytes reveal frequent resistance to apoptosis induced by FasL and TRAIL, which may contribute to their accumulation in patients with SzS and be relevant at a therapeutic level.

Mycosis fungoides with coccidioidomycosis

Mycosis fungoides is an indolent, epidermotropic, cutaneous T-cell lymphoma of helper/memory T cells that presents as heterogeneous, papulosquamous patches, plaques, and tumors. We present a patient with mycosis fungoides and infection with Coccidioides immitis of the skin, which has not been previously reported.

New insights into the molecular biology and targeted therapy of cutaneous T-cell lymphomas

Cutaneous T-cell lymphoma is an extra-nodal non-Hodgkin lymphoma of mature T cells. These tumor cells home to and persist in the skin,producing a broad spectrum of clinical entities. Recent results of basic research on tumor biology and tumor immunology as well as molecular genetics of cutaneous T-cell lymphoma have fostered the development of new therapeutic approaches. Several clinical trials testing these targeted therapies have shown encouraging results. This article provides an overview of recent research developments and therapeutic strategies for cutaneous T-cell lymphoma.

Selective induction of apoptosis by histone deacetylase inhibitor SAHA in cutaneous T-cell lymphoma cells: relevance to mechanism of therapeutic action

Suberoylanilide hydroxamic acid (SAHA), an orally administered inhibitor of histone deacetylases, is currently in phase II clinical trials for cutaneous T cell lymphomas (CTCL), but the mechanism of SAHA action is unknown. In this study, we investigated the anti-tumor effects of SAHA in CTCL cell lines and freshly isolated peripheral blood lymphocytes (PBL) from CTCL patients with high percentage of circulating malignant T cells. Three cell lines (MJ, Hut78, and HH) and PBL from 11 patients and three healthy donors were treated with SAHA (1, 2.5, and 5 microM) for 24 and/or 48 h. Apoptosis was determined by flow cytometry analysis of sub-G1 hypodiploid nuclei and/or annexin V binding populations. Acetylated histones and apoptosis-associated proteins were detected by Western blotting. SAHA at 1-5 microM for 24 and 48 h induced apoptosis in a concentration- and time-dependent manner in three cell lines: MJ (0%-7% and 1%-32%), Hut78 (4%-36% and 5%-54%), and HH (4%-67% and 8%-81%). SAHA at 1-5 muM for 48 h also induced more apoptosis of patients' PBL than healthy donors' (15%-32%versus 6%-13%, p < 0.05). SAHA treatment caused an accumulation of acetylated histones (H2B, H3, and H4), an increase of p21(WAF1) and bax proteins, a decrease of Stat6 and phospho-Stat6 proteins, and activation of caspase-3 in CTCL cells. Our data suggest that selective induction of malignant T cell apoptosis and modulation of acetylated histones, p21(WAF1), bax, Stat6, and caspase-3 may underlie the therapeutic action of SAHA in CTCL patients.