Primary B-cell non-Hodgkin lymphoma of the parotid gland: An analysis based on the SEER database.

Primary malignant lymphoma of the parotid gland is a rare entity. The disease is often misdiagnosed, and its survival factors remain unclear. This study included patients diagnosed with primary B-cell non-Hodgkin lymphoma of the parotid gland from 1987 to 2016 in the surveillance, epidemiology, and end results program. Univariate survival analysis was conducted using the Kaplan-Meier method, and multivariate analysis was performed using the Cox proportional hazards regression model. A competing risks regression model was applied to estimate the specific risks associated with parotid lymphoma mortality. A total of 1443 patients were identified. The overall survival of indolent primary B-cell lymphoma of the parotid gland was higher than that of aggressive lymphoma (hazard ratio 0.53, 95% confidence interval 0.44-0.64, P < .001), and older patients (≥70 years) exhibited inferior overall survival. Histological subtype and age are important prognostic factors in patients with primary B-cell non-Hodgkin lymphoma of the parotid gland.

ETS1 and SP1 drive DHX15 expression in acute lymphoblastic leukaemia.

DHX15 plays a role in leukaemogenesis and leukaemia relapse. However, the mechanism underlying the transcriptional regulation of DHX15 in ALL has not been elucidated. Our present study aimed to explore the functional promoter region of DHX15 and to investigate the transcription factors controlling the transcription of this gene. A luciferase assay performed with several truncated constructs identified a 501-bp region as the core promoter region of DHX15. Site-directed mutagenesis, electrophoretic mobility shift and chromatin immunoprecipitation assays showed that ETS1 and SP1 occupied the DHX15 promoter. Furthermore, knockdown of ETS1 and SP1 resulted in suppression of DHX15, whereas the overexpression of these genes led to up-regulation of DHX15. Interestingly, in samples obtained from patients with ALL at diagnosis, both ETS1 and SP1 correlated positively with DHX15 expression. Additionally, differences in methylation of the DHX15 core promoter region were not observed between the patients and controls. In conclusion, we identified the core promoter region of DHX15 and demonstrated that ETS1 and SP1 regulated DHX15 expression in ALL.

DHX15 is associated with poor prognosis in acute myeloid leukemia (AML) and regulates cell apoptosis via the NF-kB signaling pathway.

The role of DHX15, a newly identified DEAH-box RNA helicase, in leukemogenesis remains elusive. Here, we identified a recurrent mutation in DHX15 (NM_001358:c.664C>G: p.(R222G)) in one familial AML patient and 4/240 sporadic AML patients. Additionally, DHX15 was commonly overexpressed in AML patients and associated with poor overall survival (OS) (P=0.019) and relapse-free survival (RFS) (P=0.032). In addition, we found a distinct expression pattern of DHX15. DHX15 was highly expressed in hematopoietic stem cells and leukemia cells but was lowly expressed in mature blood cells. DHX15 was down-regulated when AML patients achieved disease remission or when leukemia cell lines were induced to differentiate. DHX15 silencing greatly inhibited leukemia cell proliferation and induced cell apoptosis and G1-phase arrest. In contrast, the restoration of DHX15 expression rescued cell viability and reduced cell apoptosis. In addition, we found that DHX15 was down-regulated when cell apoptosis was induced by ATO (arsenic trioxide); overexpression of DHX15 caused dramatic resistance to ATO-induced cell apoptosis, suggesting an important role for DHX15 in cell apoptosis. We further explored the mechanism of DHX15 in apoptosis and found that overexpression of DHX15 activated NF-kB transcription. Knockdown of DHX15 inhibited the nuclear translocation and activation of the NF-kB subunit P65 in leukemia cells. Several downstream targets of the NF-kB pathway were also down-regulated, and apoptosis-associated genes CASP3 and PARP were activated. In conclusion, this study represents the first demonstration that DHX15 plays an important role in leukemogenesis via the NF-kB signaling pathway and may serve as an independent prognostic marker for AML.