Nasal-type Natural Killer Cell Lymphoma Research Articles

JAK3 deregulation by activating mutations confers invasive growth advantage in extranodal nasal-type natural killer cell lymphoma

Extranodal, nasal-type natural killer (NK)/T-cell lymphoma (NKCL) is an aggressive malignancy with poor prognosis in which, usually, signal transducer and activator of transcription 3 (STAT3) is constitutively activated and oncogenic. Here, we demonstrate that STAT3 activation mostly results from constitutive Janus kinase (JAK)3 phosphorylation on tyrosine 980, as observed in three of the four tested NKCL cell lines and in 20 of the 23 NKCL tumor samples under study. In one of the cell lines and in 4 of 19 (21%) NKCL primary tumor samples, constitutive JAK3 activation was related to an acquired mutation (A573V or V722I) in the JAK3 pseudokinase domain. We then show that constitutive activation of the JAK3/STAT3 pathway has a major role in NKCL cell growth and survival and in the invasive phenotype. Indeed, NKCL cell growth was slowed down in vitro by targeting JAK3 with chemical inhibitors or small-interfering RNAs. In a human NKCL xenograft mouse model, tumor growth was significantly delayed by the JAK3 inhibitor CP-690550. Altogether, the constitutive activation of JAK3, which can result from JAK3-activating mutations, is a frequent feature of NKCL that deserves to be tested as a therapeutic target.

Flow cytometric immunophenotyping is of great value to diagnosis of natural killer cell neoplasms involving bone marrow and peripheral blood

Natural killer (NK) cell neoplasms are unusual disorders. In this study we compared results of flow cytometric immunophenotype (FCI) with cytomorphology, histopathology and clinical findings in a series of patients with NK cell neoplasms with peripheral blood and/or bone marrow involvement, and the FCI of neoplastic and normal NK cells were compared. Retrospective data and specimens (bone marrow aspiration or peripheral blood) from 71 cases of NK cell neoplasms were obtained. All patients have been demonstrated laboratory and clinical features consistent with NK cell neoplasms, and the subtypes were determined by integrated clinical estimation. Routine 4-color flow cytometry (FCM) using a NK/T cell related antibody panels was performed. NK cell neoplasms were divided into two major subtypes by FCI, namely malignant NK cell lymphoma, including extranodal nasal type NK cell lymphoma (ENKL, 11 cases) and aggressive NK cell lymphoma/leukemia (ANKL, 43 cases), and relative indolent chronic lymphoproliferative disorder of NK cell (CLPD-NK, 17 cases). The former exhibited stronger CD56-expressing, larger forward scatter (FSC) and more usually CD7- and CD16-missing. FCI of CLPD-NK was similar to normal NK cells, but CD56-expressing was abnormal, which was negative in five cases and partially or dimly expressed in eight cases. Cytomorphologic abnormal cells were found on bone marrow slides of 4 cases of ENKL and 30 cases of ANKL. Eight cases of ENKL were positive in bone marrow biopsies, and other three cases were negative. In 32 cases of ANKL which bone marrow biopsies were applied, 21 cases were positive in the first biopsies. Lymphocytosis was found only in six cases of CLPD-NK by cytomorphology, and biopsy pathology was not much useful for diagnosing CLPD-NK. These results suggest that FCM analysis of bone marrow and peripheral blood was superior to cytomorphology, bone marrow biopsy, and immunohistochemistry in sensitivity and early diagnosis for ANKL, stage III/IV ENKL and CLPD-NK. FCI could not only define abnormal NK cells but also determine the malignant classification. It is beneficial for clinical management and further study of NK cell neoplasms.

Skp2/p27 expression profile is correlated with Epstein–Barr virus status in extranodal nasal-type natural killer cell lymphoma

Extranodal nasal-type natural killer cell lymphoma (ENKL) is a high-grade malignancy and is associated with Epstein-Barr virus (EBV) latent infection. Little is known about its molecular abnormalities. Here, we studied the expression of Skp2 and p27 proteins in 48 cases of ENKL, and we evaluated their correlations with EBV status and clinical outcomes. EBV infection was observed in 90% of the cases. In all, 71% of the ENKLs were positive to Skp2 and 73% were negative to p27. A significant negative correlation was observed between the expression of Skp2 and p27 proteins (P = 0.022). Fifty-eight percent of the cases were Skp2+/p27- phenotype and correlated with EBV status (P = 0.047). The overall survival was influenced by the expression of Skp2, p27, and Skp2/p27. Patients with Skp2+, p27-, and Skp2+/p27- phenotypes had worse overall survival (P < 0.01, P = 0.016, and P < 0.01, respectively). Multivariance analysis showed the Skp2/p27 expression profile was an independent prognostic factor for overall survival (RR = 3.09, P < 0.01, 95% CI: 1.27-7.51). In conclusion, the Skp2/p27 expression profile is a helpful prognostic factor for ENKL. Latent EBV infection may increase the expression levels of Skp2, and consequently, p27 protein degradation is accelerated. EBV may be a good target for treatment of EBV-associated ENKL.

Involvement of STAT3 Transcription Factor in Disseminated Nasal-Type Natural Killer Cell Lymphomas.

Disseminated nasal-type natural killer (NK) cell lymphoma is an aggressive disease with very poor prognosis. The usual chemoresistance of this disease led us to explore the possible role of the transcription factor STAT3 in oncogenesis. For this, we established and characterized a continuous interleukin (IL)2-dependent NK cell line (MEC04) from a patient with a fatal nasal-type NK cell lymphoma. MEC04 cells phenotype was CD3−, CD7+, TCR−, CD16−, CD56+bright, p58−, p70−, NKP−, and NKG2A+, they harbored poor cytotoxic activity against K562 cells, and spontaneously secreted interferon-γ, IL-10 and vascular-endothelium growth factor in vitro, suggesting that malignant cells arise from the CD56+bright regulatory NK cell population. Injection of MEC04 cells to NOD/SCID mice led to a fatal multiorgan infiltration by malignant cells. We show by immunohistochemistry that STAT3 is phosphorylated in Y705 dimerization residue in MEC04 and YT cell lines, and on biopsies from 6/6 patients with nasal-type NK cell lymphoma, suggesting that STAT3 may be oncogenic in this disease. By contrast, Y705 residue was not phosphorylated on 2 patients with hepatosplenic γδT-cell lymphoma. By confocal microscopy, we showed that STAT3 was located in nucleus in MEC04 cells. Y705 STAT3 phosphorylation involved JAK2, since exposure of cells to AG490 inhibitor inhibited Y705 STAT3 phosphorylation, and correlated in a dose-dependent growth inhibition at 24 hours and 48 hours. By using transducible TAT-STAT3b or TAT-STAT3Y705F recombinant proteins (a dominant-negative form of STAT3 [STAT3b isoform], and a STAT3 protein mutated on Y705 residue which prevents STAT3 dimerization [STAT3Y705F]), we were able to demonstrate that inhibition of STAT3 activation increased mortality and decreased proliferation by more than 50 p. cent at 24 hours and 48 hours, which correlated with decreased expression of 2 STAT3 target genes (Bcl-XL and c-Myc). These results suggest that STAT3 protein has a major role in the oncogenic process of nasal-type NK cell lymphomas, and may thus represent a promising therapeutical target.

A Case of Adolescent Primary Adrenal Natural Killer Cell Lymphoma

Primary adrenal lymphoma is uncommon, and the majority cases of this disorder are found in elderly individuals. We describe a 17-year-old boy with persistent fever, hemophagocytic lymphohistiocytosis, and a bilateral tumor of the adrenal glands. The disease was progressive and did not respond to treatment such as immunosuppression therapy or plasma exchange. Postmortem analysis revealed nasal-type natural killer cell lymphoma in association with Epstein-Barr virus infection. To our knowledge, this case is the first of primary adrenal lymphoma with the natural killer cell phenotype to be reported. The characterization of this unusual case should be included in the differential diagnosis of adrenal gland tumors.

Leukemia and lymphoma of natural killer lineage cells.

Natural killer (NK) cells are lymphocytes with a large granular lymphocyte morphology, a CD3- CD56+ phenotype, a non-major histocompatibility complex-restricted cytotoxicity, and germline configuration T-cell receptor genes. NK cell lineage tumors originate from either precursor NK cells or mature NK cells. Tumors originating conceivably from precursor NK cells include myeloid/NK cell precursor acute leukemia, precursor NK cell acute lymphoblastic leukemia, and blastic NK cell lymphoma. However, because the developmental pathway of normal NK cells and the characteristics of these NK precursors are not fully understood, the definition and characterization of the tumors are only provisional. Tumors of mature NK cell origin include aggressive NK cell leukemia/lymphoma, nasal-type NK cell lymphoma, and chronic NK lymphocytosis, but the last disorder seems to be reactive in most cases. Because NK cell tumors are rare and difficult to manage, vigorous studies are required for their understanding and management.

Rapidly Progressive, Acute Polyradiculopathies and Cranial Neuropathies Resulting From Leptomeningeal Nasal-Type NK Cell Lymphoma

Lymphomas may cause polyradiculopathies by several pathogenic mechanisms. However, such a presentation of a nasal-type NK (natural killer) cell lymphoma is rare. We report a previously healthy man who developed acute, axon-loss radiculopathies and cranial neuropathies. Despite the lack of a nasal or midline facial mass, cerebrospinal fluid cytologic and flow cytometric immurtophenotypic studies disclosed that the patient's rapid demise was the result of a nasal-type NK cell lymphoma with leptomeningeal involvement.

Comparative Genomic Hybridization Analysis of Natural Killer Cell Lymphoma/Leukemia: Recognition of Consistent Patterns of Genetic Alterations

Putative natural killer (NK) cell lymphoma/leukemia is a rare group of recently characterized hematolymphoid malignancies. They are highly aggressive and frequently present in extranodal sites, including the nasal area and the upper aerodigestive system, and nonnasal areas such as the skin and the gastrointestinal tract. According to clinicopathological features, they can be classified into nasal NK cell lymphoma, nasal-type NK cell lymphoma occurring in nonnasal areas, and NK cell lymphoma/leukemia. Genetic alterations in NK cell lymphoma/leukemia are not well defined. In this study, we have performed comparative genomic hybridization (CGH) on DNA extracted from fresh or frozen tissues of 10 patients with NK cell lymphoma/leukemia. They comprised four nasal NK cell lymphomas, one nasal-type NK cell lymphoma, and five NK cell lymphomas/leukemias. CGH showed frequent deletions at 6q16-q27 (four cases), 13q14-q34 (three cases), 11q22-q25 (two cases), 17p13 (two cases), and loss of the whole chromosome X (two cases). DNA amplification was observed in a majority of the chromosomes. Five cases showed DNA gains at region 1p32-pter. Frequent DNA gains were also found in chromosomes 6p, 11q, 12q, 17q, 19p, 20q, and Xp (three cases each). Interestingly, DNA gains were more frequent in nasal/nasal-type NK cell lymphomas than NK cell lymphoma/leukemia. These genetic alterations correlated well with karyotypic features found in some of the cases. The frequent DNA losses at 6q and 13q suggest that the presence of tumor suppressor genes at these regions is important in NK cell transformation. In addition to establishing novel patterns of genomic imbalances in these rare NK cell malignancies, which may be targets for future molecular analysis, this study also provides important information on genetic alterations in NK cell lymphomas that may be useful in defining their positions in current lymphoma classification schemes, which are increasingly focusing on phenotypic and genotypic correlations.