Oncogenic role of microRNA-155 in mycosis fungoides: an in vitro and xenograft mouse model study

Determination of T-cell clonality and expression profiles of Toll-like receptors signaling pathway genes and related miRNAs in patients with mycosis fungoides

Cutaneous T-cell lymphomas (CTCL) encompass a group of diseases characterized by the presence of malignant clonal CD4+ T lymphocytes in the skin. Mycosis fungoides (MF) is the most prevalent form of CTCL, accounting for approximately 60 % of cutaneous T-cell lymphomas and 50 % of all primary cutaneous lymphomas. Despite ongoing research, the precise pathogenesis of MF remains incompletely understood. Toll-like receptors (TLRs) have the ability to specifically recognize ligands, subsequently induce the expression of diverse genes and activate innate immunity within the cell. Furthermore, miRNAs play a crucial role in regulating various aspects of immune cell function. The aim of our study was to explore the potential roles of TLRs and the genes implicated in their signal transduction, along with the expression status of miRNAs in the mechanisms underlying MF. Additionally, we assessed the clonal status and compared it with clinicopathological data using a T-cell clonality assay. To determine the expression status of TLR pathway genes and miRNAs, we conducted RT-PCR analysis on 52 MF samples and 50 control paraffin block materials. Pathway analysis were conducted using the KEGG database. T-cell receptor (TCR) gamma clonality changes were evaluated. Results from the study revealed increased expressions of TLR-1, -4, -8, IRF7, TRAF3, MEK1, MEK2, Elk1, NFkB, hsa-miR-21-5p, and hsa-miR-155-5p, as well as decreased expressions of hsa-miR-130a-3p, hsa-miR-210-3p, and hsa-let-7e-5p in the MF group. TCR gamma clonal change analysis demonstrated that 55.5 % of the analysed DNAs exhibited monoclonal and biallelic patterns, while 45.5 % displayed polyclonality. These findings collectively suggest the potential influence and therapeutic possibilities of the TLR signalling pathway in the molecular pathogenesis of MF.

mAb14, a Monoclonal Antibody against Cell Surface PCNA: A Potential Tool for Sezary Syndrome Diagnosis and Targeted Immunotherapy

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common types of primary cutaneous T-cell lymphoma (CTCL). Proliferating cell nuclear antigen (PCNA) is expressed on the cell surface of cancer cells (csPCNA), but not on normal cells. It functions as an immune checkpoint ligand by interacting with natural killer (NK) cells through the NK inhibitory receptor NKp44, leading to the inhibition of NK cytotoxicity. A monoclonal antibody (mAb14) was established to detect csPCNA on cancer cells and block their interaction with NKp44. In this study, three CTCL cell lines and peripheral blood mononuclear cells (PBMCs) from patients with SS and healthy donors were analyzed for csPCNA using mAb14, compared to monoclonal antibody PC10, against nuclear PCNA (nPCNA). The following assays were used: immunostaining, imaging flow cytometry, flow cytometry, cell sorting, cell cycle analysis, ELISA, and the NK-cell cytotoxic assay. mAb14 successfully detected PCNA on the membrane and in the cytoplasm of viable CTCL cell lines associated with the G2/M phase. In the Sézary PBMCs, csPCNA was expressed on lymphoma cells that had an atypical morphology and not on normal cells. Furthermore, it was not expressed on PBMCs from healthy donors. In the co-culture of peripheral blood NK (pNK) cells with CTCL lines, mAb14 increased the secretion of IFN-γ, indicating the reactivation of pNK activity. However, mAb14 did not enhance the cytotoxic activity of pNK cells against CTCL cell lines. The unique expression of csPCNA detected by mAb14 suggests that csPCNA and mAb14 may serve as a potential biomarker and tool, respectively, for detecting malignant cells in SS and possibly other CTCL variants.

Non-coding RNAs in the epigenetic landscape of cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a type of cancer that affects skin, and is characterized by abnormal T-cells in the skin. Epigenetic changes have been found to play a significant role in the development and progression of CTCL. Recently, non-coding RNAs (ncRNAs), such as microRNAs and long non-coding RNAs, have been identified as key players in the regulation of gene expression in CTCL. These ncRNAs can alter the expression of genes involved in cell growth, differentiation, and apoptosis, leading to the development and progression of CTCL. In this review, we summarize the current understanding of the role of ncRNAs in CTCL, including their involvement in DNA methylation, and other biological processes. We also discuss the types of ncRNAs, their role as oncogenic or tumor suppressive, and their putative use as diagnostic and prognostic biomarkers, based on the emerging evidence from laboratory-based as well as patients-based studies. Moreover, we also present the potential targets and pathways affected by ncRNAs. A better understanding of the complex epigenetic landscape of CTCL, including the role of ncRNAs, has the potential to lead to the development of novel targeted therapies for this disease.

MicroRNAs and their signaling pathway in mycosis fungoides

BACKGROUND

Oncogenic microRNAs, a kind of stable epigenetic inhibitors, often deregulated in Mycosis fungoides (MF) which affect the skin and tend to transform and spread.

RESULTS

Previous studies investigating the de-expression of microRNA in MF patients skin biopsies identified that they were not only regulated by signaling pathway, but also regulated other signaling pathway. Furthermore, studies have elucidated the molecular mechanisms of the STAT signaling pathway that can promote a great diversity of miRNA expression via cytokine binding receptors, activating Janus kinase-3 and STAT proteins. But some non-STAT signaling pathway with mircoRNA de-expression in MF was incomplete.

CONCLUSION

Taken together, these studies demonstrate that microRNA may be used as the prognosis, progression and diagnose of MF, as they can not only control MF cell proliferation, but also induce MF cell apoptosis.

Challenging Cutaneous T-Cell Lymphoma: What Animal Models Tell us So Far

Cutaneous T-cell lymphomas are characterized by heterogeneity of clinical variants, further complicated by genomic and microenvironmental variables. Furthermore, in vitro experiments are hampered by the low culture efficiency of these malignant cells. Animal models are essential for understanding the pathogenetic mechanisms underlying malignancy and for discovering new anticancer treatments. They are divided into two main categories: those in which tumors arise in the host owing to genetic modifications and those that use tumor cell transplantation. In this review, we summarize the attempts to decipher the complexity of the pathogenesis of cutaneous T-cell lymphoma by exploiting genetically modified and xenograft models.

The Role of microRNA in Pathogenesis, Diagnosis, Different Variants, Treatment and Prognosis of Mycosis Fungoides

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma (CTCL), accounting for approximately 50% of all CTCLs. Although various molecular changes in MF have been described in existing studies, no obvious disease-specific changes have been found thus far. microRNAs (miRs) are short, noncoding RNA molecules that play roles in the post-transcriptional regulation of oncogenes and tumor suppressor genes in various diseases. Recently, there has been rapidly expanding experimental evidence for the role of miRs in the progression, early diagnosis, prognosis prediction for MF. Efforts to improve early diagnosis and develop personalized therapy options have become more important in recent years. Here, we provide an overview and update of recent advances regarding miRs associated with MF. Furthermore, we provide insights into future opportunities for miR-based therapies.

Genetic and epigenetic insights into cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL) constitute a heterogeneous group of non-Hodgkin T-cell lymphomas that present in the skin. In recent years significant progress has been made in the understanding of the pathogenesis of CTCL. Progress in CTCL classifications combined with technical advances, in particular next generation sequencing (NGS), enabled a more detailed analysis of the genetic and epigenetic landscape and transcriptional changes in clearly defined diagnostic entities. These studies not only demonstrated extensive heterogeneity between different CTCL subtypes but also identified recurrent alterations that are highly characteristic for diagnostic subgroups of CTCL. The identified alterations in particular involve epigenetic remodelling, cell cycle regulation, and the constitutive activation of targetable, oncogenic pathways. In this respect, aberrant JAK-STAT signaling is a recurrent theme, however not universal for all CTCL and with seemingly different underlaying causes in different entities. A number of the mutated genes identified are potentially actionable targets for the development of novel therapeutic strategies. Moreover, these studies have produced an enormous amount of information that will be critically important for the further development of improved diagnostic and prognostic biomarkers that can assist in the clinical management of CTCL patients. In the present review the main findings of these studies in relation to their functional impact on the malignant transformation process are discussed for different subtypes of CTCL.

Cutaneous T cell lymphoma

Primary cutaneous T cell lymphomas (CTCLs) are a heterogeneous group of lymphomas that present in the skin with no evidence of extracutaneous disease at the time of diagnosis. CTCL subtypes demonstrate a variety of clinical, histological, and molecular features, and can follow an indolent or a very aggressive course. The underlying pathogenetic mechanisms are not yet entirely understood. The pathophysiology of CTCL is complex and a single initiating factor has not yet been identified. Diagnosis is based on clinicopathological correlation and requires an interdisciplinary team. Treatment decision is made based on short-term and long-term goals. Therapy options comprise skin-directed therapies, such as topical steroids or phototherapy, and systemic therapies, such as monoclonal antibodies or chemotherapy. So far, the only curative treatment approach is allogeneic haematopoietic stem cell transplantation. Novel therapies, such as chimeric antigen receptor T cells, monoclonal antibodies or small molecules, are being investigated in clinical trials. Patients with CTCL have reduced quality of life and a lack of effective treatment options. Further research is needed to better identify the underlying mechanisms of CTCL development and course as well as to better tailor treatment strategies to individual patients.

Mycosis fungoides-derived exosomes promote cell motility and are enriched with microRNA-155 and microRNA-1246, and their plasma-cell-free expression may serve as a potential biomarker for disease burden

BACKGROUND

Literature regarding exosomes as mediators in intercellular communication to promote progression in mycosis fungoides (MF) is lacking.

OBJECTIVES

To characterize MF-derived exosomes and their involvement in the disease.

METHODS

Exosomes were isolated by ultracentrifugation from cutaneous T-cell lymphoma (CTCL) cell lines, and from plasma of patients with MF and controls (healthy individuals). Exosomes were confirmed by electron microscopy, NanoSight and CD81 staining. Cell-line exosomes were profiled for microRNA array. Exosomal microRNA (exomiRNA) expression and uptake, and plasma-cell-free microRNA (cfmiRNA) were analysed by reverse-transcriptase quantitative polymerase chain reaction. Exosome uptake was monitored by fluorescent labelling and CD81 immunostaining. Migration was analysed by transwell migration assay.

RESULTS

MyLa- and MJ-derived exosomes had a distinctive microRNA signature with abundant microRNA (miR)-155 and miR-1246. Both microRNAs were delivered into target cells, but only exomiR-155 was tested, demonstrating a migratory effect on target cells. Plasma levels of cfmiR-1246 were significantly highest in combined plaque/tumour MF, followed by patch MF, and were lowest in controls (plaque/tumour > patch > healthy), while cfmiR-155 was upregulated only in plaque/tumour MF vs. controls. Specifically, exomiR-1246 (and not exomiR-155) was higher in plasma of plaque/tumour MF than in healthy controls. Plasma exosomes from MF but not from controls increased cell migration.

CONCLUSIONS

Our findings show that MF-derived exosomes promote cell motility and are enriched with miR-155, a well-known microRNA in MF, and miR-1246, not previously reported in MF. Based on their plasma expression we suggest that they may serve as potential biomarkers for tumour burden.

Staphylococcus aureus Induces Signal Transducer and Activator of Transcription 5‒Dependent miR-155 Expression in Cutaneous T-Cell Lymphoma

Staphylococcal enterotoxins are believed to fuel disease activity in cutaneous T-cell lymphoma. Recent data support this by showing that antibiotics inhibit malignant T cells in skin lesions in mycosis fungoides and Sézary syndrome, the most common forms of cutaneous T-cell lymphoma. Yet, it remains incompletely characterized how staphylococcal enterotoxins fuel disease activity. In this study, we show that staphylococcal enterotoxins induce the expression of the oncogenic microRNA miR-155 in primary malignant T cells. Thus, staphylococcal enterotoxins and Staphyloccocus aureus isolates from lesional skin of patients induce miR-155 expression at least partly through the IL-2Rg‒Jak‒signal transducer and activator of transcription 5 pathway, and the effect is augmented by the presence of nonmalignant T cells. Importantly, mycosis fungoides lesions harbor S. aureus, express Y-phosphorylated signal transducer and activator of transcription 5, and display enhanced miR-155 expression, when compared with nonlesional and healthy skin. Preliminary data show that aggressive antibiotic therapy is associated with decreased Y-phosphorylated signal transducer and activator of transcription 5 and miR-155 expression in lesional skin in two patients with Sézary syndrome. In conclusion, we show that S. aureus and its enterotoxins induce enhanced expression of oncogenic miR-155, providing mechanistic insight into the role of S. aureus in cutaneous T-cell lymphoma. Our findings support that environmental stimuli such as bacteria can fuel disease progression in 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.

Diagnosis and treatment of lymphomas in the era of epigenetics

Lymphomas represent a heterogeneous group of cancers characterized by clonal lymphoproliferation. Over the past decades, frequent epigenetic dysregulations have been identified in hematologic malignancies including lymphomas. Many of these impairments occur in genes with established roles and well-known functions in the regulation and maintenance of the epigenome. In hematopoietic cells, these dysfunctions can result in abnormal DNA methylation, erroneous chromatin state and/or altered miRNA expression, affecting many different cellular functions. Nowadays, it is evident that epigenetic dysregulations in lymphoid neoplasms are mainly caused by genetic alterations in genes encoding for enzymes responsible for histone or chromatin modifications. We summarize herein the recent epigenetic modifiers findings in lymphomas. We focus also on the most commonly mutated epigenetic regulators and emphasize on actual epigenetic therapies.

Gene Expression Comparison between Sézary Syndrome and Lymphocytic-Variant Hypereosinophilic Syndrome Refines Biomarkers for Sézary Syndrome

Sézary syndrome (SS), an aggressive cutaneous T-cell lymphoma (CTCL) with poor prognosis, is characterized by the clinical hallmarks of circulating malignant T cells, erythroderma and lymphadenopathy. However, highly variable clinical skin manifestations and similarities with benign mimickers can lead to significant diagnostic delay and inappropriate therapy that can lead to disease progression and mortality. SS has been the focus of numerous transcriptomic-profiling studies to identify sensitive and specific diagnostic and prognostic biomarkers. Benign inflammatory disease controls (e.g., psoriasis, atopic dermatitis) have served to identify chronic inflammatory phenotypes in gene expression profiles, but provide limited insight into the lymphoproliferative and oncogenic roles of abnormal gene expression in SS. This perspective was recently clarified by a transcriptome meta-analysis comparing SS and lymphocytic-variant hypereosinophilic syndrome, a benign yet often clonal T-cell lymphoproliferation, with clinical features similar to SS. Here we review the rationale for selecting lymphocytic-variant hypereosinophilic syndrome (L-HES) as a disease control for SS, and discuss differentially expressed genes that may distinguish benign from malignant lymphoproliferative phenotypes, including additional context from prior gene expression studies to improve understanding of genes important in SS.

MicroRNAs in the Pathogenesis, Diagnosis, Prognosis and Targeted Treatment of Cutaneous T-Cell Lymphomas

Cutaneous T-cell lymphoma (CTCL) represents a heterogeneous group of potentially devastating primary skin malignancies. Despite decades of intense research efforts, the pathogenesis is still not fully understood. In the early stages, both clinical and histopathological diagnosis is often difficult due to the ability of CTCL to masquerade as benign skin inflammatory dermatoses. Due to a lack of reliable biomarkers, it is also difficult to predict which patients will respond to therapy or progress towards severe recalcitrant disease. In this review, we discuss recent discoveries concerning dysregulated microRNA (miR) expression and putative pathological roles of oncogenic and tumor suppressive miRs in CTCL. We also focus on the interplay between miRs, histone deacetylase inhibitors, and oncogenic signaling pathways in malignant T cells as well as the impact of miRs in shaping the inflammatory tumor microenvironment. We highlight the potential use of miRs as diagnostic and prognostic markers, as well as their potential as therapeutic targets. Finally, we propose that the combined use of miR-modulating compounds with epigenetic drugs may provide a novel avenue for boosting the clinical efficacy of existing anti-cancer therapies in CTCL.

Expression of the Voltage-Gated Potassium Channel Kv1.3 in Lesional Skin from Patients with Cutaneous T-Cell Lymphoma and Benign Dermatitis

BACKGROUND

The voltage-gated potassium channel Kv1.3 (KCNA3) is expressed by effector memory T cells (TEM) and plays an important role in their activation and proliferation. Mycosis fungoides (MF), the most common subtype of cutaneous T-cell lymphoma (CTCL), was recently proposed to be a malignancy of skin-resident TEM. However, the expression of Kv1.3 in CTCL has not been investigated.

OBJECTIVES

This study aims to examine the expression of Kv1.3 in situ and in vitro in CTCL.

METHODS

The expression of Kv1.3 was examined by immunohistochemistry in skin lesions from 38 patients with MF, 4 patients with Sézary syndrome (SS), and 27 patients with benign dermatosis. In 4 malignant T-cell lines of CTCL (Myla2059, PB2B, SeAx, and Mac2a) and a non-malignant T-cell line (MyLa1850), the expression of Kv1.3 was determined by flow cytometry. The proliferation of those cell lines treated with various concentrations of Kv1.3 inhibitor ShK was measured by 3H-thymdine incorporation.

RESULTS

Half of the MF patients (19/38) displayed partial Kv1.3 expression including 1 patient with moderate Kv1.3 positivity, while the other half (19/38) exhibited Kv1.3 negativity. An almost identical distribution was observed in patients with benign conditions, that is, 44.4% (12/27) were partially positive for Kv1.3 including 1 patient with moderate Kv1.3 positivity, while 55.6% (15/27) were Kv1.3 negative. In contrast, 3 in 4 SS patients displayed partial Kv1.3 positivity including 2 patients with weak staining and 1 with moderate staining, while 1 in 4 SS patients was Kv1.3 negative. In addition, all malignant T-cell lines, and a non-malignant T-cell line, displayed low Kv1.3 surface expression with a similar pattern. Whereas 2 cell lines (PB2B and Mac2a) were sensitive to Kv1.3 blockade, the other 2 (Myla2059 and SeAx) were completely resistant.

CONCLUSIONS

We provide the first evidence of a heterogeneous Kv1.3 expression in situ in CTCL lesions.

CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies

Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets.

Cobomarsen, an oligonucleotide inhibitor of miR-155, co-ordinately regulates multiple survival pathways to reduce cellular proliferation and survival in cutaneous T-cell lymphoma

miR-155, a microRNA associated with poor prognosis in lymphoma and leukaemia, has been implicated in the progression of mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL). In this study, we developed and tested cobomarsen (MRG-106), a locked nucleic acid-modified oligonucleotide inhibitor of miR-155. In MF and human lymphotropic virus type 1 (HTLV-1+) CTCL cell lines in vitro, inhibition of miR-155 with cobomarsen de-repressed direct miR-155 targets, decreased expression of multiple gene pathways associated with cell survival, reduced survival signalling, decreased cell proliferation and activated apoptosis. We identified a set of genes that are significantly regulated by cobomarsen, including direct and downstream targets of miR-155. Using clinical biopsies from MF patients, we demonstrated that expression of these pharmacodynamic biomarkers is dysregulated in MF and associated with miR-155 expression level and MF lesion severity. Further, we demonstrated that miR-155 simultaneously regulates multiple parallel survival pathways (including JAK/STAT, MAPK/ERK and PI3K/AKT) previously associated with the pathogenesis of MF, and that these survival pathways are inhibited by cobomarsen in vitro. A first-in-human phase 1 clinical trial of cobomarsen in patients with CTCL is currently underway, in which the panel of proposed biomarkers will be leveraged to assess pharmacodynamic response to cobomarsen therapy.

MicroRNA Signatures in Diagnosis and Prognosis of Cutaneous T-Cell Lymphoma

Cutaneous T cell lymphoma (CTCL) can have clinical and histological features resembling benign inflammatory dermatosis and can be difficult to diagnose. Very limited biomarkers are available for CTCL prognosis. We aimed to identify microRNA (miR) signatures to facilitate diagnostic and prognostic evaluations of CTCL. A cross-platform miR microarray identified 10 miRs that were differentially expressed between CTCL and benign inflammatory dermatosis patients. Subsequent reverse transcription polymerase chain reaction validation was used to generate a 5-miR-based diagnosing classifier, which showed high diagnostic accuracy in CTCL (area under the curve = 0.985 and 0.956 for training and testing set, respectively). Association between miR expressions and patient prognosis was studied. miR-155 and miR-200b were significantly associated with overall survival in CTCL patients, outperformed Ki-67. miR expressions were combined with Ki-67 to create a classifier for 5-year overall survival in CTCL patients. Our work provided miR signatures to facilitate CTCL diagnosis and prognosis with satisfying accuracy.