Protective Effects of Pretreatment with Quercetin Against Lipopolysaccharide-Induced Apoptosis and the Inhibition of Osteoblast Differentiation via the MAPK and Wnt/β-Catenin Pathways in MC3T3-E1 Cells

Abstract

Background/Aims: Quercetin, a flavonoid found in onions and other vegetables, has potential inhibitory effects on bone resorption in vivo and in vitro. In our previous study, we found that quercetin treatment reversed lipopolysaccharide (LPS)-induced inhibition of osteoblast differentiation through the mitogen-activated protein kinase (MAPK) pathway in MC3T3-E1 cells. In this study, we investigated the underlying mechanisms of pretreatment with quercetin on apoptosis and the inhibition of osteoblast differentiation in MC3T3-E1 cells induced by LPS. Methods: MC3T3-E1 osteoblasts were treated with quercetin for 2 h; cells were then incubated with LPS in the presence of quercetin for the indicated times. Cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay, and cell apoptosis was evaluated using Hoechst 33258 staining. The mRNA expression levels of osteoblast-specific genes, Bax and caspase-3 were determined by real-time quantitative polymerase chain reaction (qPCR). Protein levels of osteoblast-specific genes, caspase-3, Bax, cytochrome c, Bcl-2, Bcl-XL, phosphorylated MAPKs and Wnt/β-catenin were measured using Western blot assays. The MAPK and Wnt/β-catenin signalling pathways were blocked prior to pretreatment with quercetin. Results: Pretreatment with quercetin significantly restored LPS-suppressed bone mineralization and the mRNA and protein expression levels of osteoblast-specific genes such as Osterix (OSX), runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteocalcin (OCN) in a dose-dependent manner. Pretreatment with quercetin also inhibited osteoblast apoptosis, significantly restored the down-regulated expression of Bcl-2 and Bcl-XL and decreased the upregulated expression of caspase-3, Bax, and cytochrome c in MC3T3-E1 cells induced by LPS. Furthermore, pretreatment with quercetin not only decreased the abundance of phosphorylated p38 MAPK and increased the abundance of phosphorylated extracellular signal regulated kinase (ERK), but also triggered the Wnt/β-catenin pathway through enhancing expression of Wnt3 and β-catenin. Pretreatment with MAPK inhibitors or the Wnt/β-catenin inhibitor XAV939 blocked the protective effects of quercetin against LPS-induced apoptosis and the inhibition of osteoblast differentiation. Conclusions: Our findings suggest that pretreatment with quercetin may be a potential drug for preventing abnormal human bone loss induced by LPS in bacteria-induced bone diseases.

Cyclocarya paliurus Leaves Tea Improves Dyslipidemia in Diabetic Mice: A Lipidomics-Based Network Pharmacology Study

“…The ALOX, BCL-2, CYP 2C9, PLA2G(s) and PI3K(s) families, PLD2 and PTEN were determined as quercetin and kaempferol targets on diabetic dyslipidemia (Guo et al, 2017). PTPN1, PI3K(s) family and PLD2 were determined as targets of saponins such as quadranoside IV and asiatic acid (Ramachandran and Saravanan, 2015), whilst BCL-2, PI3K(s) family, PLD2 and PTEN were determined as action targets of gallic acid and 4-hydrobenzoic acids ( Figure 4 ).…”

Protective effect of Agrimonia pilosa polysaccharides on dexamethasone‐treated MC3T3‐E1 cells via Wnt/β‐Catenin pathway

“…20 While, as a key signalling member of the TGF-β super family, BMP-2 is indispensable for osteoblast proliferation and osteogenic differentiation and accounts for osteogenic effect of osteoblasts to a great extent. 20 While, as a key signalling member of the TGF-β super family, BMP-2 is indispensable for osteoblast proliferation and osteogenic differentiation and accounts for osteogenic effect of osteoblasts to a great extent.…”

“…Runx2 is a master transcription factor in the early-stage of osteoblast differentiation and is closely correlated with the expression of osteoblast marker genes and related proteins in the late-stage molecular events of osteoblast differentiation, such as OSX and OCN. 20 While, as a key signalling member of the TGF-β super family, BMP-2 is indispensable for osteoblast proliferation and osteogenic differentiation and accounts for osteogenic effect of osteoblasts to a great extent. 21,22 Furthermore, the changes in the expression of Runx2, BMP-2, OSX and OCN were also investigated in MC3T3-E1 cells in response to different and so on.…”

Quercetin augments apoptosis of canine osteosarcoma cells by disrupting mitochondria membrane potential and regulating PKB and MAPK signal transduction

“…22 In addition, it was revealed in a previous study that pretreated-quercetin suppresses lipopolysaccharide-induced programmed cell death and osteoblast differentiation by regulating MAPK and Wnt/β-catenin signal transduction in mouse osteoblasts. 23 Moreover, quercetin induces the death of human endometrial cells through mitochondria membrane permeabilization, lipid peroxidation, MAPK and PI3K/AKT signal inactivation, and regulation of cyclin D1. 24 In accord with previous evidence, in the present study, quercetin was reported to induce apoptosis through DNA fragmentation, changes of cell cycle, and ROS production in canine osteosarcoma cells.…”