Ginsenoside Rg5 Inhibits Human Osteosarcoma Cell Proliferation and Induces Cell Apoptosis through PI3K/Akt/mTORC1-Related LC3 Autophagy Pathway.

Ming-Yang Liu,Hai-Jun Li,Fei Liu,Chen Yang,Yan-Jiao Li,Jian-Guo Liu,Jia-Ning Yin,Yan-Li Gao,Xin-Yue Wang,Marco Cordani

doi:10.1155/2021/5040326

Abstract

The function and mechanism underlying the suppression of human osteosarcoma cells by ginsenoside-Rg5 (Rg5) was investigated in the present study. MG-63, HOS, and U2OS cell proliferation was determined by MTT assay after Rg5 treatment for 24 h. Rg5 inhibited human osteosarcoma cell proliferation effectively in a dose-dependent manner. The range of effective inhibitory concentrations was 160-1280 nM. Annexin V-FITC and PI double-staining assay revealed that Rg5 induced human osteosarcoma cell apoptosis. Western blotting, qRT-PCR, and FACS experiments revealed that Rg5 inhibited human osteosarcoma cells via caspase-3 activity which was related to the LC3-mediated autophagy pathway. Rg5 decreased the phosphorylation of PI3K, Akt, and mTORC1 activation. In contrast, LC3-mediated autophagy and caspase-3 activity increased significantly. A PI3K/AKT stimulator, IGF-1, reversed Rg5-induced cell autophagy and apoptosis in MG-63 cells. Collectively, the current study demonstrated that Rg5 induced human osteosarcoma cell apoptosis through the LC3-mediated autophagy pathway. Under physiological conditions, activation of PI3K/AKT/mTORC1 inhibits LC3 activity and caspase-3-related cell apoptosis. However, Rg5 activated LC3 activity by inhibiting the activation of PI3K/AKT/mTORC1. The present study indicated that Rg5 could be a promising candidate as a chemotherapeutic agent against human osteosarcoma.

Highlights

Osteosarcoma (OS) causes a 2.4% death rate in child cancers, which is a fatal malignancy in pediatric patients [1]
MG-63, HOS, and U2OS cells were treated with Rg5 (0, 10, 20, 40, 80, 160, 320, 640, and 1280 nM) for 24 h; cell proliferation was determined by MTT assay (Figure 1(a))
The numbers of apoptotic cells decreased significantly in LC3-silenced MG-63 cells compared to those of the control cells (Figure 4(f), p < 0:01). These results proved that the LC3 autophagy pathway is a key factor in MG-63 cell apoptosis initiated by Rg5

Summary

Introduction

Osteosarcoma (OS) causes a 2.4% death rate in child cancers, which is a fatal malignancy in pediatric patients [1]. The 5-year survival rate is no more than 70% because there are limited effective therapies except for surgical treatment [2]. OS is believed to be derived from malignant mesenchymal stem cells of the long bones [3,4,5,6]. Chemotherapy is still suitable for patients who are not suitable for surgery. Side effects and drug resistance limited the use of chemotherapy drugs [7]. Herbal medicines and natural products have drawn increasing attention to novel anticancer agents because of the outstanding effectiveness and safety [8,9,10]

Methods

Results

Conclusion