Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Apr 26, 2018; 10(4): 34-42
Published online Apr 26, 2018. doi: 10.4252/wjsc.v10.i4.34
NF-κB promotes the stem-like properties of leukemia cells by activation of LIN28B
Jianbiao Zhou, Jing-Yuan Chooi, Ying Qing Ching, Jessie Yiying Quah, Sabrina Hui-Min Toh, Yvonne Ng, Tuan Zea Tan, Wee-Joo Chng
Jianbiao Zhou, Ying Qing Ching, Jessie Yiying Quah, Sabrina Hui-Min Toh, Yvonne Ng, Tuan Zea Tan, Wee-Joo Chng, Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
Jianbiao Zhou, Jing-Yuan Chooi, Wee-Joo Chng, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore
Wee-Joo Chng, Department of Hematology-Oncology, National University Cancer Institute, Singapore 119228, Singapore
Author contributions: Zhou J and Chng WJ conceptualized the original idea, designed the experiments and analyzed the data; Zhou J performed the experiments, wrote the paper; Chooi JY, Ching YQ, Quah JY, Toh SHM and Ng Y performed the experiments; Tan TZ conducted the bioinformatics analysis; all authors read and approved the final manuscript.
Supported by the Singapore National Research Foundation and the Ministry of Education under the Research Center of Excellence Program to WJ Chng and NMRC Clinician-Scientist IRG Grant CNIG11nov38 (Zhou J); Chng WJ is also supported by NMRC Clinician Scientist Investigator award; This study is also partially supported by the RNA Biology Center at CSI Singapore, NUS, from funding by the Singapore Ministry of Education’s Tier 3 Grants, No. MOE2014-T3-1-006.
Conflict-of-interest statement: No potential conflicts of interest relevant to this article were reported.
Data sharing statement: The datasets supporting the conclusions of this article are included within the article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Jianbiao Zhou, MD, PhD, Senior Scientist, Cancer Science Institute of Singapore, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore. csizjb@nus.edu.sg
Telephone: +65-6-5161118
Received: March 6, 2018
Peer-review started: March 6, 2018
First decision: March 13, 2018
Revised: March 21, 2018
Accepted: April 10, 2018
Article in press: April 10, 2018
Published online: April 26, 2018
Processing time: 51 Days and 17.6 Hours
ARTICLE HIGHLIGHTS
Research background

Acute myeloid leukemia (AML) is a common blood cancer adult. The current standard chemotherapy can’t cure the disease, as most of the patient relapse and become refractory to treatment. Leukemia stem cells (LSCs) are a small subpopulation that sustain the disease and often resistant to chemotherapy. LSCs are responsible for the disease relapse. So, a better understanding molecular biology of AML and novel therapies are urgently needed for AML patients.

Research motivation

The nuclear factor kappa B (NF-κB) is a pivotal transcription factor, playing different roles in all most all cellular functions. Aberrant activation of NF-κB has been found specifically in LSCs, but not in normal hematopoietic progenitor cells. LIN28 and LIN28B are RNA-binding protein and transcriptional regulators, which are used to create induced pluripotent stem cells (iPS). However, the detailed molecular basis of how NF-κB contributes to the LSC-like properties of AML cells is not well-understood.

Research objectives

In this study, we aim to explore the relationship between NF-κB and LIN28B expression, as well as to assess their roles in LSC-like properties. It will help us to better understand the formation of LSCs, and provide the opportunity to target LSCs.

Research methods

Several NF-κB inhibitors with different mode-of-actions was used to treat leukemia cells, then followed by assessment of cell viability. Western blot and qRT-PCR was employed to examine the correlation between NF-κB and LIN28B protein and mRNA levels. Luciferase reporter was constructed and applied to explore the transcriptional regulation of LIN28B. Colony forming and serial replating assays are functional assays for LSC-like properties.

Research results

Treatment of leukemia cells with direct and indirect NF-κB inhibitors significantly decreased LIN28B protein and mRNA levels and reduced cell viability. Mechanistically, the region of -819 to -811 region on the LIN28B promoter contains specific, consensus NF-κB binding motif, and mutations in this region compromised transcription activity and LIN28B expression. On contrast, transfection of NFκB1 increased LIN28B protein. Overexpression of LIN28B partially rescued the self-renewal capacity impaired by pharmacological inhibition of NF-κB activity. The functional role of NF-κB and LIN28B regulatory axis in LSCs was confirmed.

Research conclusions

Our data demonstrated the existing of NF-κB/LIN28B regulatory axis in AML, which plays a pivotal role in the formation of LSCs. This study provides a deep understanding of the previous finding that NF-κB is activated in CD34+CD38- AML cells. LIN28B is a critical downstream target of NF-κB pathway. This study also highlights the targeting NF-κB or LIN28B as an effective approach for eradication LSCs in AML.

Research perspectives

In summary, we characterized the NF-κB/LIN28B regulatory axis and its functional roles in maintenance of LSC-like properties of AML cells. We proposed that targeting either NF-κB or LIN28B could be an effective way to eradication of LSCs, which are known to resist to chemotherapy. Although NF-κB inhibitors are available, their side-effects should be carefully examined as NF-κB play important roles in multiple cellular processes, like immune defense. Furthermore, specific LIN28B inhibitor is currently not available. The development of novel class of small molecular inhibitors or drug-like compounds to inhibit LIN28B should be the focus of the future research.