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

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.

Natural Compounds in Glioblastoma Therapy: Preclinical Insights, Mechanistic Pathways, and Outlook

“…Downstream, Akt upregulates the mammalian target of rapamycin (mTOR) and nuclear factor κappa of activated B cells (NF-κB), which induce proliferation. However, arctigenin, curcumin, diosgenin, and berberine downregulate (p-)mTOR, while diosgenin downregulates NF-κB [ 29 , 54 , 61 ]. Moreover, galbanic acid exerts antiproliferative, anti-metastatic, and pro-apoptotic effects via PI3K/Akt/mTOR signaling, while N45, a natural steroidal saponin, upregulates apoptosis through ROS/PI3K/Akt signaling in TMZ-resistant GBM cells [ 65 , 66 ].…”

“…Downstream, cytochrome c, Bad, and Bim promote the activation of caspase 9, which in turn activates caspase 3. A blockade of Akt/mTOR signaling mediated by arctigenin or osthole enhances the activity of Beclin-1, which supports caspase 3 activation [ 61 , 64 ]. Caspase 3 specifically blocks the inhibitor of caspase-activated DNAse (ICAD), allowing CAD to cause DNA fragmentation—an effect observed after diosgenin application [ 54 ].…”

“…However, arctigenin and osthole upregulate Beclin-1 mRNA and protein levels. Beclin-1 interestingly has dual roles in apoptosis and autophagy, and upregulates light chain 3B (LC3B), which promotes autophagosome formation [ 61 , 64 ]. Moreover, arctigenin may increase autophagy through the upregulation of phosphorylated P62 (p-P62) [ 61 ].…”

Integrative cBioPortal Analysis Revealed Molecular Mechanisms That Regulate EGFR-PI3K-AKT-mTOR Pathway in Diffuse Gliomas of the Brain

“…One of the reasons why we focused our interest on EGFR-PI3K-AKT-mTOR signaling pathway is that our previous investigation, using Array Comparative Genomic Hybridization (aCGH) and bioinformatics utilizing a Bioconductor package, Genomic Identification of Significant Targets in Cancer (GISTIC) 2.0.23 and DAVID software, identified main actors of the PI3K-AKT pathway activated in human astrocytomas and suggested that DNA copy number alterations play important roles in its etiology and progression [ 7 ]. Furthermore, the AKT signaling pathway mediates cell regulation, cell proliferation, cell cycle, and carbohydrate metabolism by further phosphorylation of GSK3β (glycogen synthase kinase 3 beta), Bad (bcl-2 bound death promoter), caspase-9, NF-κB (nuclear factor κB), mTOR (target molecule of rapamycin in mammals) and p21 protein [ 8 , 9 , 10 , 11 , 12 , 13 ]. Since recent studies have revealed the essential role of EGFR-PI3K-AKT-mTOR signaling in human tumors [ 14 ], we were interested in the molecular characteristics of this pathway across the three pathohistological types and grades of diffuse brain gliomas.…”

Knockdown of ETV4 promotes autophagy‑dependent apoptosis in GBM cells by reducing the transcriptional activation of EMP1

“…These findings indicated that inhibiting the ETV4/EMP1 signaling axis may play an important role in promoting autophagy and apoptosis in LN-229 GBM cells. mTOR has been reported to be upregulated in GBM, and the PI3K/AKT/mTOR signaling pathway was discovered to play a crucial role in regulating cell proliferation, apoptosis and autophagy (22). In the present study, LN-229 cells were co-incubated with RAP, si-ETV4 and Oe-EMP1 alone or in combination, and the expression levels of p-AKT and p-mTOR, which indicate that the PI3K/AKT/mTOR signaling pathway has been activated, were measured.…”