Stage-related increase in PIM2 expression in mycosis fungoides

The oncogene PIM2 is upregulated in several malignancies but has never been investigated in mycosis fungoides (MF), the most common type of cutaneous T-cell lymphoma (CTCL). PIM2 is a well-known oncogene and is regulated by cell signaling pathways like the JAK/STAT- and NF-kB-pathway, key regulators in the pathogenesis of CTCL. The aim of this study was to examine the role of PIM2 in MF. PIM2 gene expression was measured in 81 formalin-fixed paraffin-embedded skin biopsies from patients with MF and 46 control biopsies from healthy skin (HS) and benign inflammatory skin disease (BID). Validation of PIM2 protein expression was performed on selected biopsies with immunohistochemical staining. We found a significant difference in gene expression levels between both early stage MF and HS (p < 0.0001), and BID (p < 0.0001). In addition, the PIM2 gene expression was higher in advanced-stage MF compared to early stage disease (p = 0.0001). No significant difference in gene expression levels was found between patients with and without disease progression. In conclusion, we found PIM2 expression is significantly increased in MF compared to controls, and in advanced-stage MF compared to early stage MF. These findings could potentially have diagnostic value in discriminating early stage MF from BID.

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.

JAK3 Is Expressed in the Nucleus of Malignant T Cells in Cutaneous T Cell Lymphoma (CTCL)

Simple Summary

JAK3 plays an important role in the pathogenesis of cutaneous T cell lymphoma. JAK3 belongs to the Janus kinase family of receptor-associated tyrosine kinases located in cytoplasm adjacent to the plasma membrane. In this study, we show that JAK3 can also be ectopically expressed in the nucleus in CTCL cell lines and primary cells from CTCL patients. Importantly, JAK3 interacts with the nuclear protein RNA polymerase II and phosphorylates Histone H3. Thus, our data provide first evidence for nuclear expression of JAK3 and interactions with key nuclear proteins in malignant T cells suggesting a novel non-canonical role in CTCL.

Abstract

Perturbation in JAK-STAT signaling has been reported in the pathogenesis of cutaneous T cell lymphoma (CTCL). JAK3 is predominantly associated with the intra-cytoplasmic part of IL-2Rγc located in the plasma membrane of hematopoietic cells. Here we demonstrate that JAK3 is also ectopically expressed in the nucleus of malignant T cells. We detected nuclear JAK3 in various CTCL cell lines and primary malignant T cells from patients with Sézary syndrome, a leukemic variant of CTCL. Nuclear localization of JAK3 was independent of its kinase activity whereas STAT3 had a modest effect on nuclear JAK3 expression. Moreover, JAK3 nuclear localization was only weakly affected by blockage of nuclear export. An inhibitor of the nuclear export protein CRM1, Leptomycin B, induced an increased expression of SOCS3 in the nucleus, but only a weak increase in nuclear JAK3. Importantly, immunoprecipitation experiments indicated that JAK3 interacts with the nuclear protein POLR2A, the catalytic subunit of RNA Polymerase II. Kinase assays showed tyrosine phosphorylation of recombinant human Histone H3 by JAK3 in vitro—an effect which was blocked by the JAK inhibitor (Tofacitinib citrate). In conclusion, we provide the first evidence of nuclear localization of JAK3 in malignant T cells. Our findings suggest that JAK3 may have a cytokine-receptor independent function in the nucleus of malignant T cells, and thus a novel non-canonical role in CTCL.

Suppressed microRNA-195-5p expression in mycosis fungoides promotes tumor cell proliferation

BACKGROUND

Several cancers, including mycosis fungoides (MF), have reported dysregulation of miR-195-5p. miR-195-5p plays a role in cell cycle regulation in several malignant diseases.

OBJECTIVES

This study aimed to investigate: (a) the expression level of miR-195-5p in lesional MF skin biopsies and (b) the potential regulatory roles of miR-195-5p in MF.

METHODS

Quantitative real-time polymerase chain reaction (RT-qPCR) was used to determine miR-195-5p expression in MF skin biopsies and cell lines. The effect of miR-195-5p and ADP-ribosylation factor-like protein 2 (ARL2) on cell cycle and apoptosis was measured by flow cytometry assays. Changes in ARL2 expression were determined by RT-qPCR and Western blotting (WB).

RESULTS

We found lower expression levels of miR-195-5p in lesional skin from MF patients compared with non-lesional MF skin and skin from healthy volunteers. Additionally, miR-195-5p showed lower expression levels in the skin from patients with disease progression compared with patients with stable disease. In vitro studies showed that overexpression of miR-195-5p induced a cell cycle arrest in G0G1. Using microarray analysis, we identified several genes that were regulated after miR-195-5p overexpression. The most downregulated gene after miR-195-5p mimic transfection was ARL2. RT-qPCR and WB analyses confirmed downregulation of ARL2 following transfection with miR-195-5p mimic. Lastly, transfection with siRNA against ARL2 also induced a G0G1 arrest.

CONCLUSION

Upregulation of miR-195-5p in MF inhibits cycle arrest by downregulation of ARL2. miR-195-5p may thus function as a tumor suppressor in MF and low miR-195-5p expression in lesional MF skin may promote disease progression.

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.