Epstein–Barr virus-associated T/natural killer-cell lymphoproliferative disorder in children and young adults has similar molecular signature to extranodal nasal natural killer/T-cell lymphoma but shows distinctive stem cell-like phenotype

Epstein-Barr virus-associated T- and NK-cell lymphoproliferative diseases: an update and diagnostic approach

Epstein-Barr virus (EBV)-positive T-cell and natural killer (NK)-cell lymphoproliferative diseases (EBV-TNKLPD) are a group of uncommon disorders characterised by EBV infection of T- and NK-cells. As a group, EBV-TNKLPD are more commonly encountered in Asians and Native Americans from Central and South America compared to Western populations. They encompass a spectrum of entities that range from non-neoplastic lesions such as EBV-associated haemophagocytic lymphohistiocytosis (EBV-HLH) to more chronic conditions with variable outcomes such as chronic active EBV infections (CAEBV) of T- and NK-cell type (cutaneous and systemic forms) and malignant diseases such as systemic EBV-positive T-cell lymphoma of childhood, aggressive NK-cell leukaemia, extranodal NK/T-cell lymphoma, nasal-type, and primary EBV-positive nodal T/NK-cell lymphoma. Due to their rarity, broad clinicopathological spectrum and significant morphological and immunophenotypic overlap, the diagnosis and precise classification of EBV-TNKLPD often pose a challenge to clinicians and pathologists. Correct classification of this group of rare diseases relies heavily on the age of onset, disease presentation, duration of symptoms and cell of origin (T- vs NK-cell lineage). In this review, we provide an update on the clinicopathological and molecular features of the various EBV-TNKLPD entities occurring in non-immunocompromised patients and present a practical algorithmic approach for the general pathologist who is confronted with these disorders in routine clinical practice.

Molecular pathogenic pathways in extranodal NK/T cell lymphoma

Extranodal NK/T cell lymphoma, nasal type (ENKTL) is an aggressive malignancy with a dismal prognosis. Although L-asparaginase-based chemotherapy has resulted in improved response rates, relapse occurs in up to 50% of patients with disseminated disease. There is hence an urgent need for effective targeted therapy, especially for patients with relapsed or refractory disease. Novel insights gleaned from high-throughput molecular and genomic profiling studies in recent years have contributed significantly to the understanding of the molecular biology of ENKTL, which exemplifies many of the hallmarks of cancer. Deregulated pro-proliferative signaling pathways, such as the Janus-associated kinase/signal transducer and activator of transcription (JAK/STAT), platelet-derived growth factor (PDGF), Aurora kinase, MYC, and NF-κB, have been identified as potential therapeutic targets. The discovery of the non-canonical function of EZH2 as a pro-proliferative transcriptional co-activator has shed further light on the pathogenesis of ENKTL. Loss of key tumor suppressor genes located on chromosome 6q21 also plays an important role. The best-studied examples include PR domain zinc finger protein 1(PRDM1), protein tyrosine phosphatase kappa (PTPRK), and FOXO3. Promoter hypermethylation has been shown to result in the downregulation of other tumor suppressor genes in ENKTL, which may be potentially targeted through hypomethylating agents. Deregulation of apoptosis through p53 mutations and upregulation of the anti-apoptotic protein, survivin, may provide a further growth advantage to this tumor. A deranged DNA damage response as a result of the aberration of ataxia telangiectasia-related (ATR) kinases can lead to significant genomic instability and may contribute to chemoresistance of ENKTL. Recently, immune evasion has emerged as a critical pathway for survival in ENKTL and may be a consequence of HLA dysregulation or STAT3-driven upregulation of programmed cell death ligand 1 (PD-L1). Immunotherapy via inhibition of programmed cell death 1 (PD-1)/PD-L1 checkpoint signaling holds great promise as a novel therapeutic option. In this review, we present an overview of the key molecular and pathogenic pathways in ENKTL, organized using the framework of the "hallmarks of cancer" as described by Hanahan and Weinberg, with a focus on those with the greatest translational potential.

The Genomics and Molecular Biology of Natural Killer/T-Cell Lymphoma: Opportunities for Translation

Extranodal NK/T-cell lymphoma, nasal type (ENKTL), is an aggressive malignancy with a poor prognosis. While the introduction of L-asparaginase in the treatment of this disease has significantly improved the prognosis, the outcome of patients relapsing after asparaginase-based chemotherapy, which occurs in up to 50% of patients with disseminated disease, remains dismal. There is hence an urgent need for effective targeted therapy especially in the relapsed/refractory setting. Gene expression profiling studies have provided new perspectives on the molecular biology, ontogeny and classification of ENKTL and further identified dysregulated signaling pathways such as Janus associated kinase (/Signal Transducer and activation of transcription (JAK/STAT), Platelet derived growth factor (PDGF), Aurora Kinase and NF-κB, which are under evaluation as therapeutic targets. Copy number analyses have highlighted potential tumor suppressor genes such as PR Domain Zinc Finger Protein 1 (PRDM1) and protein tyrosine phosphatase kappa (PTPRK) while next generation sequencing studies have identified recurrently mutated genes in pro-survival and anti-apoptotic pathways. The discovery of epigenetic dysregulation and aberrant microRNA activity has broadened our understanding of the biology of ENKTL. Importantly, immunotherapy via Programmed Cell Death -1 (PD-1) and Programmed Cell Death Ligand1 (PD-L1) checkpoint signaling inhibition is emerging as an attractive therapeutic strategy in ENKTL. Herein, we present an overview of the molecular biology and genomic landscape of ENKTL with a focus on the most promising translational opportunities.

Transcriptomic Abnormalities in Epstein Barr Virus Associated T/NK Lymphoproliferative Disorders

Epstein Barr virus positive T/NK lymphoproliferative disorders (EBV-TNKLPD) comprise a spectrum of neoplasms ranging from cutaneous lymphoid proliferations to aggressive lymphomas. The spectrum includes extranodal NK/T-cell lymphoma (ENKTL), aggressive NK-cell leukemia, and a group of EBV-TNKLPDs affecting children which are poorly characterized in terms of their molecular biology. Gene and miRNA expression profiling has elucidated RNA abnormalities which impact on disease biology, classification, and treatment of EBV-TNKLPD. Pathways promoting proliferation, such as Janus associated kinase/ Signal Transducer and Activator of Transcription (JAK/STAT) and nuclear factor kB, are upregulated in ENKTL while upregulation of survivin and deregulation of p53 inhibit apoptosis in both ENKTL and chronic active EBV infection (CAEBV). Importantly, immune evasion via the programmed cell death-1 and its ligand, PD-1/PD-L1 checkpoint pathway, has been demonstrated to play an important role in ENKTL. Other pathogenic mechanisms involve EBV genes, microRNA deregulation, and a variety of other oncogenic signaling pathways. The identification of EBV-positive Peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) as a tumor with a distinct molecular signature and clinical characteristics highlights the important contribution of the knowledge derived from gene and miRNA expression profiling in disease classification. Novel therapeutic targets identified through the study of RNA abnormalities provide hope for patients with EBV-TNKLPD, which often has a poor prognosis. Immune checkpoint inhibition and JAK inhibition in particular have shown promise and are being evaluated in clinical trials. In this review, we provide an overview of the key transcriptomic aberrancies in EBV-TNKLPD and discuss their translational potential.

Resveratrol inhibits Extranodal NK/T cell lymphoma through activation of DNA damage response pathway

Background

Extranodal NK/T cell lymphoma (NKTCL) is a highly aggressive non-Hodgkin lymphoma with poor prognosis. Resveratrol (RSV, 3,5,4′-trihydroxystilbene), a natural nontoxic phenolic compound found in the skin of grapes and some other spermatophytes, performs multiple bioactivities, such as antioxidant activity, anti-aging activity, reduction of cardiovascular disease risk and anticarcinogenic effect. Here we report the anti-tumor effect of RSV in NKTCL cell lines SNT-8, SNK-10 and SNT-16.

Results

RSV inhibited NKTCL cell proliferation in a dose- and time-dependent manner and arrested cell cycle at S phase. It induced NKTCL cells apoptosis through mitochondrial pathway, shown as down-regulation of MCl-1 and survivin, up-regulation of Bax and Bad, and activation of caspase-9 and caspase-3. In addition, we found that RSV suppressed the phosphorylation level of AKT and Stat3, and activated DNA damage response (DDR) pathway directly or through up-regulation of Zta of Epstein-Barr virus (EBV). Furthermore, using KU55933 as the inhibitor of pATM, we verified that DDR played an important role in RSV inducing NKTCL apoptosis. RSV also showed synergistic effect on activating DDR pathway in combination with etoposide or ionizing radiation, which resulted in cell proliferation inhibition and apoptosis.

Conclusions

Our results provide in vitro evidence that RSV produces anti-tumor effect by activating DDR pathway in an ATM/Chk2/p53 dependent manner. So we suggest that RSV may be worthy for further study as an anti-tumor drug for NKTCL treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0601-6) contains supplementary material, which is available to authorized users.