title: Nucleophosmin Mutations Induce Chemosensitivity in THP-1 Leukemia Cells by Suppressing NF-κB Activity and Regulating Bax/Bcl-2 Expression.
abstract: Nucleophosmin(NPM1) - a gene that encodes for a nuclear protein with multiple functions. Mutations inNPM1are seen in approximately one-third of acute myeloid leukemia (AML) and are generally associated with good response to induction chemotherapy. However, the mechanisms underlying this chemosensitivity are still unknown. Recent studies have established that nuclear factor-κB (NF-κB) activation is a key response of leukemia cell to chemotherapy. In this study, we transfected human monocytic leukemia THP-1 cells with the vector expressing NPM1 mutation variant (NPM1mA), and confirmed overexpression of NPM1mA at mRNA and protein levels by reverse transcription PCR (RT-PCR) and immunohistochemistry, respectively. The effects of NPM1 mutations on chemotherapeutical agents induced apoptosis, NF-κB activity and gene expression were examined using flow cytometry, luciferase reporter assays, quantitative real time PCR (qRT-PCR) and Western blot. We found that overexpression of NPM1mA in THP-1 cells sensitized these cells to apoptosis induced by chemotherapeutical agents such as daunorubicin (DNR) and cytarabine (Ara-C). Moreover, we demonstrated that expression of NPM1 mA reduced the NF-κB transcription activity of THP-1 cells upon drug treatment. In addition, restoration of NF-κB activity via TNF-α stimulation could attenuate the effect of NPM1mA overexpression on DNR-and Ara-C-induced apoptosis. Interestingly, expression of NPM1mA could upregulate Bax and downregulate Bcl-2 at mRNA and protein levels in THP-1 cells when treated with DNR or Ara-C. We also demonstrated that restoration of NF-κB activity via TNF-α pre-treatment reversed the effect of NPM1mA on the Bax/Bcl-2 expression. Furthermore, evaluation of gene expression data from The Cancer Genome Atlas (TCGA) dataset revealed that NPM1-mutated patients showed a higher expression of Bax and a lower expression of Bcl-2. These results suggest that the NPM1 gene mutations could confer increased sensitivity to chemotherapeutic agents, at least in part, by suppressing NF-κB activity and regulating Bax/Bcl-2 expression.
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Shuaishuai
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of clinical laboratory, Liuzhou Worker's Hospital, Guangxi, China.
authors.forename: Fengxian
authors.initials: F
authors.lastname: Qin
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Yang
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Jingrong
authors.initials: J
authors.lastname: Xian
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Zou
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Jin
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, College of Laboratory Medicine, Chongqing Medical University, Chongqing, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
keywords: Bax; Bcl-2; NF-κB; acute myeloid leukemia.; chemosensitivity; nucleophosmin, gene mutation