Arctigenin Inhibits Glioblastoma Proliferation through the AKT/mTOR Pathway and Induces Autophagy.

Yong’an Jiang,Jiayu Liu,Ru’en Liu,Xiaowei Fei,Wangwang Hong

doi:10.1155/2020/3542613

Abstract

Purpose Arctigenin (ARG) is a natural lignan compound extracted from Arctium lappa and has displayed anticancer function and therapeutic effect in a variety of cancers. Arctigenin is mainly from Arctium lappa extract. It has been shown to induce autophagy in various cancers. However, as for whether arctigenin induces autophagy in gliomas or not, the specific mechanism is still worth exploring. Methods Using CCK8, the monoclonal experiment was made to detect the proliferation ability. The scratch experiment and the transwell experiment were applied to the migration and invasion ability. PI/RNase and FITC-conjugated anti-annexin V were used to detect the cell cycle and apoptosis. Western blotting was used to determine the specified protein level, and constructed LC3B-GFP plasmid was used for analysis of autophagy.Results Our research showed that ARG inhibited the growth and proliferation and invasion and migration of glioma cells in a dose-dependent manner (U87MG and T98G) and arrested the cell cycle and induced apoptosis. Interestingly, ARG induced autophagy in a dose-dependent manner. We applied Western blotting to measure the increase in the key autophagy protein LC3B, as well as some other autophagy-related proteins (increase in Beclin-1 and decrease in P62). In order to further explore the mechanism that ARG passed initiating autophagy to inhibit cell growth, we further found by Western blotting that AKT and mTOR phosphorylation proteins (P-AKT, P-mTOR) were reduced after ARG treatment, and we used AKT agonists to rescue, and the phosphorylated proteins of AKT and mTOR increased, and we found that the autophagy-related proteins were also reversed. And interestingly, the protein of apoptosis was also reversed along with autophagy. Conclusions We thought ARG inhibited the proliferation of glioma cells by inducing autophagy and apoptosis through the AKT/mTOR pathway.

Highlights

Glioma is the most common central nervous system tumor, and about 50% is glioblastoma [1]
Arctigenin (ARG) is a bioactive lignan extracted from Arctium lappa [3] and has various biological activities such as anticancer [4], neuroprotection [5], antioxidation effects [6], antiproliferation [7], and antiviral [8], and ARG exerted a certain therapeutic effect on the treatment of colorectal cancer [9], liver cancer [10], retinoblastoma [11], and prostate cancer [12], and ARG enhances the sensitivity of cisplatin-resistant colorectal cancer cells by activating autophagy and upregulates the levels of apoptosis proteins caspase-3 and caspase-9, triggering autophagy-related proteins (LC3 and P62) [9]
Dulbecco’s modified Eagle’s medium (DMEM) and fetal bovine serum (FBS) (Cambridge, MA) were purchased from Gibco (Grand Island, USA), and antibodies against AKT, P-AKT, mTOR, P-mTOR, MMP2, MMP9, Bax, cleaved caspase-3, Bad, Bcl-2, cyclin E, cyclin-dependent kinase 2 (CDK2), P62, Beclin-1, LC3B, and β-actin were purchased from Abcam, and the AKT activator (SC79) was purchased from Beyotime

Summary

Introduction

Glioma is the most common central nervous system tumor, and about 50% is glioblastoma [1]. There is an urgent need to discover new targets or novel drugs for the treatment of glioma. GSK3β-dependent Wnt/β-catenin signaling pathway [13] It has been reported in the literature that ARG inhibits the proliferation of retinoblastoma Y79 and promotes apoptosis by downregulating JAG-1 [11]. Autophagy can be used as a new target for the treatment of tumors and even gliomas. We studied the potential activity of ARG in the treatment of glioma cells, and we confirmed that autophagy did occur in glioma cells treated with ARG. We identified the ARGinduced autophagy pathway, namely, the AKT/mTOR pathway These results provided new ideas for us to treat glioma patients and develop new therapeutic targets to apply clinically

Materials and Methods

Results

Discussions