Integrative analysis of differential miRNA and functional study of miR-21 by seed-targeting inhibition in multiple myeloma cells in response to berberine.

Xiaochuang Luo,Rongxuan Zhu,Jingyi Gu,Maoxiao Feng,Jia Fei,Xuejiao Zhu,Yumin Li

doi:10.1186/1752-0509-8-82

Abstract

BackgroundBerberine is a natural alkaloid derived from a traditional Chinese herbal medicine. It is known to modulate microRNA (miRNA) levels, although the mechanism for this action is unknown. Here, we previously demonstrate that the expression of 87 miRNAs is differentially affected by berberine in multiple myeloma cells. Among 49 miRNAs that are down-regulated, nine act as oncomirs, including miR-21. Integrative analysis showed that 28 of the down-regulated miRNAs participate in tumor protein p53 (TP53) signaling and other cancer pathways. miR-21 is involved in all these pathways, and is one of the most important oncomirs to be affected by berberine in multiple myeloma cells.ResultsWe confirmed that berberine down-regulated miRNA-21 expression and significantly up-regulated the expression of programmed cell death 4 (PDCD4), a predicted miR-21 target. Luciferase reporter assays confirmed that PDCD4 was directly regulated by miR-21. Bioinformatic analysis revealed that the miR-21 promoter can be targeted by signal transducer and activator of transcription 3 (STAT3). Down-regulation of interleukin 6 (IL6) by berberine might lead to inhibition of miR-21 transcription through STAT3 down-regulation in multiple myeloma. Furthermore, both berberine and seed-targeting anti-miR-21 oligonucleotide induced apoptosis, G2-phase cell cycle arrest and colony inhibition in multiple myeloma cell lines. Depletion of PDCD4 by short interfering RNA could rescue berberine-induced cytotoxicity in multiple myeloma cells.ConclusionsOur results suggest that berberine suppresses multiple myeloma cell growth, at least in part, by down-regulating miR-21 levels possibly through IL6/STAT3. This led to increased PDCD4 expression, which is likely to result in suppression of the p53 signaling pathway. These findings may also provide new mechanistic insight into the anti-cancer effects of certain compounds in traditional Chinese herbal medicines.

Highlights

Berberine is a natural alkaloid derived from a traditional Chinese herbal medicine
Multiple myeloma (MM) is a clonal B cell malignancy characterized by proliferation of plasma cells (PCs) within the bone marrow (BM)
Among the 49 down-regulated miRNAs, mirFocus software identified 28 that are involved in p53 signaling, the cell cycle and other cancer pathways (Figure 1)

Summary

Introduction

Berberine is a natural alkaloid derived from a traditional Chinese herbal medicine. It is known to modulate microRNA (miRNA) levels, the mechanism for this action is unknown. We previously demonstrate that the expression of 87 miRNAs is differentially affected by berberine in multiple myeloma cells. MiR-21 is involved in all these pathways, and is one of the most important oncomirs to be affected by berberine in multiple myeloma cells. MM is characterized by profound genomic instability involving both miRNAs are a newly discovered class of endogenous non-coding small RNAs that regulate gene expression through degrading target mRNAs and/or suppressing their translation by binding to the 3′-untranslated region (3′UTR) of target genes. Bioinformatic predictions indicate that 30% of all human genes are regulated by miRNAs. miRNAs are involved in a variety of biological processes, from development and differentiation to survival, apoptosis, and senescence [7,8,9]. Termed “oncomirs”, these oncogene miRNAs usually promote tumor development by negatively regulating tumor suppressor genes that control various biological processes. Altering oncomir expression might be a valuable strategy for cancer treatment [10,11]

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