Activation of ER Stress-Dependent miR-216b Has a Critical Role in Salviamiltiorrhiza Ethanol-Extract-Induced Apoptosis in U266 and U937 Cells.

Changmin Kim,Hojung Park,Bonglee Kim,Hyo-Sook Song

doi:10.3390/ijms19041240

Abstract

Although Salvia miltiorrhiza has been reported to have anti-cancer mechanisms, such as caspase activation, cell cycle arrest, an anti-angiogenesis effect, and Bcl-2 family regulation, its underlying mechanism of endoplasmic reticulum (ER) stress-mediated apoptosis has never been demonstrated. Thus, in this current study, ER stress-related apoptosis via miR-216b of the ethanol extract of Salvia miltiorrhiza (SM) is elucidated for the first time. SM treatment inhibited the viability of U266 and U937 cells in a concentration-dependent manner. However, SM-exposed Raw264.7 cells were intact compared to U266 or U937 cells. Treatment with SM significantly elevated the generation of reactive oxygen species (ROS). The anti-proliferative effect of SM was reversed by pretreatment with the ROS scavenger, N-acetyl-l-cysteine (NAC), compared to cells treated only with SM. Also, SM treatment increased the ER stress by elevation of phosphorylated activating transcription factor 4 (p-ATF4), phosphorylated eukaryotic Initiation Factor 2 (p-eIF2), and phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (p-PERK) expression. Caspase-3 and Poly (ADP-ribose) polymerase (PARP) were cleaved and CCAAT-enhancer-binding protein homologous protein (CHOP) was activated by SM treatment. PARP cleavage and CHOP activation were attenuated by NAC pretreatment. Furthermore, SM increased the tumor suppressor, miR-216b, and suppressed its target, c-Jun. miR-216b inhibitor attenuated the apoptotic effect of SM. Taken together, SM treatment induced apoptosis through regulation of miR-216b and ROS/ER stress pathways. SM could be a potential drug for treatment of multiple myeloma and myeloid leukemia.

Highlights

Myeloid-originated hematological malignancies, including multiple myeloma and myeloid leukemia, have been continuously increasing worldwide [1,2]
Human myeloid leukemia represents an increase in the number of myeloid cells and their abnormal differentiation in the bone marrow, leading to hematopoietic insufficiency
We indicated that Salvia miltiorrhiza (SM) induced protein kinase RNA-like ER kinase (PERK)-dependent C/EBP-homologous protein (CHOP) expression and increased the apoptotic marker cleaved Poly (ADP-ribose) polymerase (PARP), which is in accordance with previous studies (Figure 4) [50,51]

Summary

Introduction

Myeloid-originated hematological malignancies, including multiple myeloma and myeloid leukemia, have been continuously increasing worldwide [1,2]. Patients with multiple myeloma often suffer from hypercalcemia, fractures, renal insufficiency, and neuropathy [3,4]. Human myeloid leukemia represents an increase in the number of myeloid cells and their abnormal differentiation in the bone marrow, leading to hematopoietic insufficiency. Myeloid-originated hematological malignancies are able to escape programmed cell death or suppression of proliferation and metastasis. Recent studies have suggested that endoplasmic reticulum (ER) stress mediates apoptosis in cancer cells [13,14]. Several studies relevant to ER stress-mediated apoptosis in myeloid-originated hematological malignancies have been reported [8,15,16]

Methods

Results

Conclusion