Histone deacetylase 1 induced by neddylation inhibition contributes to drug resistance in acute myelogenous leukemia.

OBJECTIVE: This study aimed to investigate the function and mechanism of neddylation of HDAC1 underlying drug resistance of AML cells. METHODS: Evaluation experiments of effects of HDAC1 on drug resistance of AML cells were performed with AML cell transfected with constructs overexpressing HDAC1 or multi-drug resistance AML cells transfected with siRNA for HDAC1 through observing cell viability, percentage of apoptotic cell, doxorubicin-releasing index and multidrug resistance associated protein 1 (MRP1) expression. Neddylation or ubiquitination of HDAC1 was determined by immunoprecipitation or Ni2+ pull down assay followed by western blot. The role of HDAC1 was in vivo confirmed by xenograft in mice. RESULTS: HDAC1 was significantly upregulated in refractory AML patients, and in drug-resistant AML cells (HL-60/ADM and K562/A02). Intracellular HDAC1 expression promoted doxorubicin resistance of HL-60, K562, and primary bone marrow cells (BMCs) of remission AML patients as shown by increasing cell viability and doxorubicin-releasing index, inhibiting cell apoptosis. Moreover, HDAC1 protein level in AML cells was regulated by the Nedd8-mediated neddylation and ubiquitination, which further promoted HDAC1 degradation. In vivo, HDAC1 overexpression significantly increased doxorubicin resistance; while HDACs inhibitor Panobinostat markedly improved the inhibitory effect of doxorubicin on tumor growth. Furthermore, HDAC1 silencing by Panobinostat and/or lentivirus mediated RNA interference against HDAC1 effectively reduced doxorubicin resistance, resulting in the inhibition of tumor growth in AML bearing mice. CONCLUSION: Our findings suggested that HDAC1 contributed to the multidrug resistance of AML and its function turnover was regulated, at least in part, by post-translational modifications, including neddylation and ubiquitination.

Asparagine synthetase expression is associated with the sensitivity to asparaginase in extranodal natural killer/T-cell lymphoma in vivo and in vitro.

BACKGROUND: Although asparagine synthetase (AsnS) is associated with drug resistance in leukemia, its function in extranodal natural killer (NK)/T-cell lymphoma (ENKTL) remains unclear. METHODS: The present study investigated the relationship between baseline AsnS mRNA levels and response to asparaginase in ENKTL cell lines. It also determined whether upregulating or downregulating the AsnS mRNA level induces or reverses asparaginase-resistant phenotype. RESULTS: Interestingly, considerable differences were observed in the sensitivity to asparaginase of the five ENKTL cell lines. The AsnS expression levels were positively correlated with the IC50 values. In addition, the asparaginase resistance was induced or reversed by upregulating or downregulating the AsnS mRNA level in vivo and in vitro. Functional analyses indicated that AsnS did not affect the proliferation and apoptosis of ENKTL cells in the absence of asparaginase. CONCLUSION: Together, the data stress the importance of AsnS in the sensitivity to asparaginase in ENKTL and suggest a different therapeutic strategy for patients with a different level of AsnS expression.

Comparison of Hematological Aspects between Neuroblastoma Patients with and without Bone Marrow Infiltration.

Bone marrow involvement in neuroblastoma indicates an advanced stage of the disease. In this study, we retrospectively analyzed the bone marrow infiltration status and hematological parameters of 111 cases of neuroblastoma. Among the 111 cases, 62 (55.9%) exhibited marrow infiltration. Erythrocytopenia, anemia, and thrombocytopenia were significantly (p<0.05) associated with marrow infiltration of >10% malignant cells. The evaluation of blood cell count parameters with receiver operating characteristic curves indicated that erythrocytopenia can substantially improve the accurate prediction of the risk of bone marrow involvement with a Youden index of 0.60. The sensitivity and specificity were 90% and 70%, respectively, which correspond to a cut-off value of 4.015×10^12/L. Hematological aspects with diagnostic value are different among neuroblastoma patients with and without bone marrow infiltration.

Clinical significance of serum soluble interleukin-2 receptor-α in extranodal natural killer/T-cell lymphoma (ENKTL): a predictive biomarker for treatment efficacy and valuable prognostic factor.

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is an aggressive disease, and no standard treatment and validated prognostic model were established. Serum sIL-2Rα levels were measured in 94 ENKTL patients to evaluate its relationship with clinical features, treatment response, and prognosis. Serum sIL-2Rα level was 2964 ± 1613.6 ng/L in ENKTL patients, higher than in normal healthy controls (p < 0.05). Using median level (2508.5 ng/L) as cutoff, patients were divided into higher- and lower-level group (N = 47 for each). The complete remission and overall remission rate were significantly higher in lower-level group (p < 0.05). After a median follow-up time of 22.0 months, 2-year overall survival and progression-free survival rates were 60.0 and 53.0 %, respectively. Lower sIL-2Rα level significantly correlated with better progression-free survival (PFS) and overall survival (OS) (p = 0.001 and 0.002, respectively). IPI score and treatment responses after 2 cycles of chemotherapy significantly correlated with PFS and OS (p < 0.05). In a multivariate Cox regression model that included IPI score, treatment responses, and sIL-2Rα level, all three parameters were independent prognostic factors for OS (p = 0.043, 0.001, and 0.025, respectively), and the last two parameters were also independent factors for PFS (p = 0.005 and 0.005, respectively). Elevated serum sIL-2Rα level was related to poor responses to treatments and can be used as a valuable biomarker for disease activity. Moreover, serum sIL-2Rα was an independent prognostic factor for both OS and PFS. These results need to be validated in prospective trials and may support the incorporation of anti-CD25 targeted therapy into the treatment realm of ENKTL.