A novel nude mice model of human extranodal nasal type NK/T-cell lymphoma

Selective drug combination vulnerabilities in STAT3- and TP53-mutant malignant NK cells

Mature natural killer (NK) cell neoplasms are rare but very aggressive types of cancers. With currently available treatments, they have a very poor prognosis and, as such, are an example of group of cancers in which the development of effective precision therapies is needed. Using both short- and long-term drug sensitivity testing, we explored novel ways to target NK-cell neoplasms by combining the clinically approved JAK inhibitor ruxolitinib with other targeted agents. We profiled 7 malignant NK-cell lines in drug sensitivity screens and identified that these exhibit differential drug sensitivities based on their genetic background. In short-term assays, various classes of drugs combined with ruxolitinib seemed highly potent. Strikingly, resistance to most of these combinations emerged rapidly when explored in long-term assays. However, 4 combinations were identified that selectively eradicated the cancer cells and did not allow for development of resistance: ruxolitinib combined with the mouse double-minute 2 homolog (MDM2) inhibitor idasanutlin in STAT3-mutant, TP53 wild-type cell lines; ruxolitinib combined with the farnesyltransferase inhibitor tipifarnib in TP53-mutant cell lines; and ruxolitinib combined with either the glucocorticoid dexamethasone or the myeloid cell leukemia-1 (MCL-1) inhibitor S63845 but both without a clear link to underlying genetic features. In conclusion, using a new drug sensitivity screening approach, we identified drug combinations that selectively target mature NK-cell neoplasms and do not allow for development of resistance, some of which can be applied in a genetically stratified manner.

ATP-binding cassette sub-family C member 4 (ABCC4) is overexpressed in human NK/T-cell lymphoma and regulates chemotherapy sensitivity: Potential as a functional therapeutic target

Nasal-type natural killer/T-cell (NK/T-cell) lymphomas are subtypes of non-Hodgkin's lymphoma (NHL), which are typically more clinically aggressive. There is, however relatively little understanding of nasal-type NK/T-cell lymphoma molecular pathogenesis. Thus, in this study we applied RNA sequencing to systematically screen for altered gene expression in human NK/T-cell lymphoma cell lines YTS and SNK-6 versus normal NK cells. We found that ATP-binding cassette sub-family C Member 4 (ABCC4) levels were significantly upregulated both in human NK/T-cell lymphoma YTS and SNK-6 cells, as compared with normal NK cells. These expression levels were further confirmed by real-time PCR. Protein levels of ABCC4 were also significantly higher in YTS and SNK-6 cells as compared with normal NK cells. Clinically relevant, ABCC4 expression levels were significantly higher in human NK/T-cell lymphoma tissues as compared with control nasal mucosa tissues, confirmed by immunohistochemical staining. In addition, we explored the biological function of such ABCC4 upregulation. Overexpression of ABCC4 by lentivirus transfection induced chemotherapy resistance to epirubicin (EPI) and cisplatin (DDP) in YTS cells. In contrast, knockdown of ABCC4 expression by shRNA contributed to chemotherapy sensitivity by both EPI and DDP. Furthermore, overexpression of ABCC4 inhibited, while downregulation of ABCC4 increased, YTS cell apoptosis following treatment by EPI or DDP. Therefore, the present study identified ABCC4 to be overexpressed in human NK/T-cell lymphoma cells, to regulate chemotherapy sensitivity to EPI and DDP, and possibly to be a functional therapeutic target. These findings may provide a basic rationale for new approaches in the effort to develop anti-tumor therapeutics for NK/T-cell lymphoma.

Identification of immunophenotypic subtypes with different prognoses in extranodal natural killer/T-cell lymphoma, nasal type

To analyze the differentiation characteristics of extranodal natural killer/T-cell lymphoma, nasal type, one nude mouse model, cell lines SNK6 and SNT8, and 16 fresh human samples were analyzed by flow cytometry immunophenotyping and immunohistochemistry staining; and 115 archived cases were used for phenotypic detection and prognostic analysis. We found that CD25 was expressed by most tumor cells in all samples, and CD56(+)CD25(+) cells were the predominant population in the mouse model, the 2 cell lines, and 10 of the 16 fresh tumor samples; in the other 6 fresh tumor samples, the predominant cell population was of the CD16(+)CD25(+) phenotype, and only a minor population showed the CD56(+)CD25(+) phenotype. The phenotype detected by immunohistochemistry staining generally was consistent with the phenotype found by flow cytometry immunophenotyping. According to the expression of CD56 and CD16, 115 cases could be classified into 3 phenotypic subtypes: CD56(-)CD16(-), CD56(+)CD16(-), and CD56(dim/-)CD16(+). Patients with tumors of the CD56(dim/-)CD16(+) phenotype had a poorer prognosis than patients with tumors of the other phenotypes. Differentiation of extranodal natural killer/T-cell lymphoma, nasal type apparently resembles the normal natural killer cell developmental pattern, and these tumors can be classified into 3 phenotypic subtypes of different aggressiveness. Expression of CD56(dim/-)CD16(+) implies a poorer prognosis.

Mucor irregularis infection and lethal midline granuloma: a case report and review of published literature

Mucor irregularis (Rhizomucor variabilis) infection and lethal midline granuloma (LMG) are characterized by progressive swelling, ulceration, and destruction of the central face that is usually fatal. Pathological features are inflammation, necrosis, and granulation. LMG has been called by various names, and in recent years, it has been known as NK/T cell lymphoma. However, diagnosis still relies on the progressive necrosis course rather than malignancy in histology. The disease has long challenged physicians, particularly when it worsens with radiotherapy or chemotherapy but sometimes achieves total remission without anti-malignancy therapies. We describe a 35-year-old man who had typical clinical-pathological symptoms of LMG, which turned out to be primary M. irregularis infection; that was diagnosed by positive tissue culture and fungal elements in histology. The patient was successfully treated with antifungal therapy (liposomal amphotericin B, total 4,600 mg and amphotericin B total 277 mg, over a duration of 70 days). We hereby review current knowledge about the epidemiology, clinical manifestations, radiographic characteristics, and pathologic features of LMG with those of M. irregularis infection and their associations. We conclude that primary M. irregulars infection can mimic the clinico-pathological symptoms of LMG and the condition responds favorably to aggressive antifungal therapy.

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

Extranodal natural killer (NK)/T-cell lymphoma of nasal type (NKTCL) is a malignant disorder of cytotoxic lymphocytes of NK or more rarely T cells associated with clonal Epstein-Barr virus infection. Extranodal NKTCL is rare in Western countries, but in Asia and Central and South America it can account for up to 10% of non-Hodgkin's lymphomas. It is an aggressive neoplasm with very poor prognosis. Although the pathogenesis of extranodal NKTCL remains poorly understood, some insights have been gained in the recent years, especially from genome-wide studies. Based on our own experience and knowledge of the literature, we here review some of the genomic and functional pathway alterations observed in NKTCL that could provide a rationale for the development of innovative therapeutic strategies.

STAT3 transcription factor is constitutively activated and is oncogenic in nasal-type NK/T-cell lymphoma

Nasal-type natural killer (NK) cell lymphoma is an infrequent aggressive malignant disease with very poor prognosis. We aimed to explore the possible role of the transcription factor STAT3 in the pathophysiology of this malignancy, as it was involved in oncogenesis and chemoresistance. For this, we established and characterized a continuous interleukin 2-dependent NK cell line (MEC04) from a patient with a fatal nasal-type NK-cell lymphoma. Cells harbored poor cytotoxic activity against K562 cells, and spontaneously secreted interferon-gamma, interleukin-10 and vascular-endothelium growth factor in vitro. STAT3 was phosphorylated in Y705 dimerization residue in MEC04 cells and restricted to the nucleus. Y705 STAT3 phosphorylation involved JAK2, as exposure of cells to AG490 inhibitor inhibited Y705 STAT3 phosphorylation. By using recombinant transducible TAT-STAT3-beta (beta isoform), TAT-STAT3Y705F (a STAT3 protein mutated on Y705 residue, which prevents STAT3 dimerization) and peptides inhibiting specifically STAT3 dimerization, we inhibited STAT3 phosphorylation and cell growth, with cell death induction. Finally, STAT3 was phosphorylated in Y705 residue in the nuclei of lymphoma cells in eight/nine patients with nasal-type NK/T-cell lymphoma and in YT, another NK cell line. Our results suggest that STAT3 protein has a major role in the oncogenic process of nasal-type NK-cell lymphomas, and may represent a promising therapeutical target.

Gastric involvement of extranodal NK/T-cell lymphoma, nasal type: a report of 3 cases with literature review

Gastric involvement of extranodal natural killer/T-cell lymphoma, nasal type is extremely rare, and its clinicopathologic features are also poorly understood. Until now, only 4 cases have been reported in literature. In this article, 3 cases of extranodal natural killer/T-cell lymphoma, nasal type are reported. In this current series, one patient (case 2) was admitted to emergency due to life-threatened hemorrhage of the upper-digestive tract and the volume of blood loss was about 2000 mL. For case 3, the sample was a small piece of gastroendoscopy biopsy tissue. It is a challenge for pathologist to make the diagnosis for this special type of tumor. In all, 2 of 3 cases had a relevant history of midfacial extranodal natural killer/T-cell lymphoma, nasal type before. The other patient died of tumor 2 months later with no history of the tumor when she was alive. Literature review was carried out; The cases reported in this article are documented and compared with the 4 previously reported cases of tumor.