Extranodal NK/T-cell lymphoma: toward the identification of clinical molecular targets

Activated hippo signal pathway inhibits cell proliferation and promotes apoptosis in NK/T cell lymphoma cells

Background

Natural Killer T–Cell Lymphoma (NKTCL) is a subtype of Non‐Hodgkin's Lymphoma, and its morbidity is ranked the first of T‐Cell Lymphoma. Hippo signaling pathway is involved in the pathogenesis of tumors. However, the role of Hippo signaling pathway in the oncogenesis of NKTCL still remains unclear.

Methods

The expressions of mammalian sterile 20‐like kinase 1 (MST1) and Yes‐associated protein (YAP) were investigated by RT‐PCR and Western blotting. Cell viability was detected by MTT assays. Cell cycle and cell apoptosis were determined by flow cytometry. Cell proliferative capacity was detected by colony formation assay. Nude mice xenograft models were established and the tumor sections were analyzed by immunohistochemistry (IHC) staining.

Results

The expression of MST1 was significantly down‐regulated in NKTCL tissues (n = 30) and cell lines, while the expression of YAP was significantly up‐regulated, and the phosphorylation of YAP was inhibited. Overexpression of MST1, knockdown of YAP, or verteporfin (VP) treatment could inhibit cell proliferation, and promote cell cycle arrest and apoptosis in NKTCL cells, while knockdown of MST1 and overexpression of YAP promoted cell proliferation. Additionally, Bcl‐2/Bax ratio and downstream effectors of Hippo signaling pathway (c‐myc, survivin, cyclinD1, CTGF, and TEAD) were significantly decreased when MST1 was overexpressed and YAP was knocked down or after VP treatment. Furthermore, our mice model demonstrated that activation of Hippo signal pathway suppressed the tumorigenesis of NKTCL.

Conclusion

The activation of Hippo signal pathway via overexpressing MST1 or down‐regulating YAP can inhibit the tumorigenesis of NKTCL.

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.

Extranodal NK/T-cell lymphoma: Updates in biology and management strategies

Extranodal NK/T-cell lymphoma, nasal type (ENKL), is a rare lymphoma subtype of peripheral T/NK-cell lymphoma that is very common in East Asia and Latin America. Two-thirds of patients have localized disease in the nasal cavity or adjacent sites. Large retrospective studies have revealed the clinicopathologic features of ENKL patients, identified risk factors for short survival time, and developed prognostic models. Next-generation sequencing studies have provided a comprehensive list of recurrent mutations in ENKL. Since the early 2000s, disease-specific therapeutic approaches have been developed, and the standard of care for ENKL has markedly changed. Non-anthracycline-containing chemotherapy with or without radiotherapy is the current standard approach for ENKL treatment. Emerging therapies, including the use of immune checkpoint inhibitors, are being investigated.

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.

Novel findings from the Asian Lymphoma Study Group: focus on T and NK-cell lymphomas

T and NK-cell lymphomas are aggressive neoplasms with a unique epidemiological distribution, demonstrating higher prevalence in Asian countries compared to the West. Through the efforts of international collaboration, significant progress has been made especially on the biological understanding and clinical management of rare lymphoma subtypes including NK/T-cell lymphomas and monomorphic epitheliotropic intestinal T-cell lymphoma. In this review, we summarize the current status of lymphoma research conducted by the Asian Lymphoma Study Group and highlight key updates on the advancement of T and NK-cell lymphoma research.

Serum EBV EA-IgA and VCA-IgA antibodies can be used for risk group stratification and prognostic prediction in extranodal NK/T cell lymphoma: 24-year experience at a single institution

Although extranodal NK/T cell lymphoma (ENKTCL) is consistently associated with Epstein-Barr virus (EBV) infection, the manifestation and prognostic value of serum EBV antibodies still remain unknown. One hundred and forty-one patients with ENKTCL were evaluated for serum EBV EA-IgA and VCA-IgA antibodies levels in the past 24 years in our institution. Their correlation with clinicopathological features, plasma EBV DNA load, and patients’ outcomes was analyzed. EBV EA-IgA ≥1:10 and VCA-IgA ≥1:160 were found in 18.4 and 16.3% of patients, respectively. They correlated with adverse ENKTCL profile and inferior overall survival (OS) and progression-free survival (PFS). EA-IgA ≥1:10 was an independent prognostic factor on OS (RR = 2.276, p = 0.008) and associated with lower complete response (CR) rate (34.8 vs 70.6%, p = 0.001) and higher relapse rate in CR patients (62.5 vs 34.7%, p = 0.016). In subgroup analysis, both EA-IgA ≥1:10 and VCA-IgA ≥1:160 significantly correlated with inferior OS and PFS in patients with stage I/II, IPI score 0–1, plasma EBV DNA (+), and CR. Patients with plasma EBV DNA (+) and EA-IgA ≥1:10 (or VCA-IgA ≥1:160) had significantly shorter periods of OS and PFS in comparison with other corresponding groups. Elevated serum EBV EA-IgA and VCA-IgA levels were related to adverse ENKTCL profile and correlated with poor treatment response, early relapse, and poor prognosis in patients with ENKTCL. These findings provide convincing evidence for the use of serum EBV EA-IgA and VCA-IgA antibodies for risk group stratification and prognostic prediction in ENKTCL.

Mutational Analysis of Extranodal NK/T-Cell Lymphoma Using Targeted Sequencing with a Comprehensive Cancer Panel

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (NKTCL), is a malignant disorder of cytotoxic lymphocytes of NK or T cells. It is an aggressive neoplasm with a very poor prognosis. Although extranodal NKTCL reportedly has a strong association with Epstein-Barr virus, the molecular pathogenesis of NKTCL has been unexplored. The recent technological advancements in next-generation sequencing (NGS) have made DNA sequencing cost- and time-effective, with more reliable results. Using the Ion Proton Comprehensive Cancer Panel, we sequenced 409 cancer-related genes to identify somatic mutations in five NKTCL tissue samples. The sequencing analysis detected 25 mutations in 21 genes. Among them, KMT2D, a histone modification-related gene, was the most frequently mutated gene (four of the five cases). This result was consistent with recent NGS studies that have suggested KMT2D as a novel driver gene in NKTCL. Mutations were also found in ARID1A, a chromatin remodeling gene, and TP53, which also recurred in recent NGS studies. We also found mutations in 18 novel candidate genes, with molecular functions that were potentially implicated in cancer development. We suggest that these genes may result in multiple oncogenic events and may be used as potential bio-markers of NKTCL in the future.

Orphan diseases of the nose and paranasal sinuses: Pathogenesis - clinic - therapy

Rare rhinological diseases are a diagnostic challenge. Sometimes it takes months or even years from the primary manifestation of the disease until the definitive diagnosis is establibshed. During these times the disease proceeds in an uncontrolled or insufficiently treated way. (Irreversible) damage results and sometimes life-threatening situations occur. The unexpected course of a (misdiagnosed) disease should lead to further diagnostic reflections and steps in order to detect also rare diseases as early as possible. The present paper discusses granulomatous diseases of the nose and paranasal sinuses caused by mycobacteria, treponema, Klebsiella, fungi, and protozoa as well as vasculitis, sarcoidosis, rosacea, cocaine-induced midline destruction, nasal extranodal NK/T cell lymphoma, and cholesterol granuloma. Furthermore, diseases with disorders of the mucociliary clearance such as primary ciliary dyskinesia and cystic fibrosis are presented, taking into consideration the current literature.

A TNM Staging System for Nasal NK/T-Cell Lymphoma

Ann Arbor stage has limited utility in the prognostication and treatment decision making in patients with NK/T-cell lymphoma (NKTCL), as NKTCL is almost exclusively extranodal and the majority is localized at presentation for which radiotherapy is the most important treatment and local invasiveness is the most important prognostic factor. In this study, we attempted to establish a TNM (Tumor-Node-Metastasis) staging system for nasal NKTCL (N-NKTCL). The staging rules of other head and neck cancers were used as reference along with the data of our 271 eligible patients. The primary tumor was classified into T1 to T4, and cervical lymph node metastasis was classified into N0 to N2 according to the extent of involvement. Any lesions outside the head and neck were classified as M1. N-NKTCL thereby was classified into four stages: stage I comprised T1-2N0M0; stage II comprised T1-2N1M0 and T3N0M0; stage III comprised T3N1M0, T1-3N2M0, and T4N0-2M0; and stage IV comprised TanyNanyM1. This staging system showed excellent performance in prognosticating survival. In the current series, the 5-year survival rates of patients with stages I, II, III, and IV N-NKTCL were 92%, 64%, 23%, and 0, respectively. Moreover, the predictive value of several currently used factors was abrogated in the presence of the TNM stage. The TNM staging system is highly effective in stratifying tumor burden and survival risk, which may have significant implications in the treatment decision making for patients with N-NKTCL.

Controlling distant metastasis and surgical treatment are crucial for improving clinical outcome in uncommon head and neck malignancies, such as non-squamous cell carcinoma

The objective of this study was to elucidate the clinical characteristics of uncommon head and neck malignancies, such as non-squamous cell carcinoma (SCC), in order to improve patient outcomes. A total of 463 head and neck malignancies were retrospectively analyzed, with 43 cases (9.3%) diagnosed as non-SCC. The overall survival rate of patients with adenoid cystic carcinoma was significantly worse compared to that of patients with SCC. The 5-year survival rates were <50% for patients with malignant melanoma, adenocarcinoma, small-cell carcinoma and sarcomas. Distant metastasis to the lung was frequently observed in cases with a poor outcome. Non-SCC malignancies treated without surgery were associated with a worse outcome. Some non-SCC patients had a poor prognosis and distant metastasis was associated with an unsatisfactory outcome. Timely treatment and control of distant metastasis are essential and surgical treatment should be prioritized in non-SCC cases to improve patient outcomes.

Primary extranodal NK/T-cell lymphoma of the lung: Mimicking bronchogenic carcinoma

Primary extranodal natural killer/T- cell lymphoma, nasal type (NK/TCL) in the lung is extremely rare and associated with Epstein-Barr virus (EBV) infection. An 80-year-old male presented with hemoptysis, which had lasted three days. Physical examination revealed inspiratory crackles at the left lung base and massive splenomegaly. Chest radiograph shows a mass-like lesion in the left lower lung but no active lesion six months earlier. Computed tomography demonstrated a soft tissue mass (size: 6.6 × 5.1 cm) with increased ground-glass opacities in the left lower lobe, several pulmonary nodules, and mediastinal lymphadenopathy. Transthoracic needle biopsy of the left-lower-lobe lung mass was performed. The pathology revealed atypical lymphoid cell infiltration, which is immunoreactive for cytoplasmic CD3, CD30 and CD56, but not reactive for CK and CD20. EBV-encoded RNA (EBER) was also detected in these atypical lymphoid cells. The serum EBV DNA level was 7.03 × 10(6) copies/mL and subtype 1 EBV was identified. No evidence of lymphoma involvement was found in the extrathoracic site. Primary pulmonary lymphoma showing nasal-type NK/T-cell subtype was diagnosed. Chemotherapy with cyclophosphamide and prednisolone was initiated immediately but the patient deteriorated and died three weeks later. In conclusion, patients presenting with rapidly growing lung mass and massive splenomegaly raise the possibility of aggressive pulmonary lymphoma. Extranodal NK/T-cell lymphoma with high baseline plasma EBV DNA levels signifies poor prognosis. Identifying young high-risk patients may have benefits for early aggressive and successful treatment.

Non-healing pharyngeal ulcer in a middle-aged Caucasian man

Extranodal natural killer NK/T-cell lymphoma is a rare malignancy. The disease is common in some Asian countries such as China, Japan as well as in South America. We present a case of extranodal NK/T-cell lymphoma which presented as a pharyngeal ulcer in a 35-year-old Caucasian man.