Inhibition of MDM2 and RNF6 in GC cells by GLA.
Glaucocalyxin A Inhibits the Malignancies of Gastric Cancer Cells by Downregulating MDM2 and RNF6 via MiR-3658 and the SMG1-UPF mRNA Decay Pathway
Paper
2022
Frontiers in Oncology |
DOI
Background
This study investigates Glaucocalyxin A (GLA), a natural ent-kauranoid diterpene, in gastric cancer (GC). GLA inhibited proliferation, adhesion, invasion, and promoted apoptosis in multiple GC cell lines. Mechanistically, GLA downregulated oncoproteins MDM2 and RNF6 by restoring tumor-suppressive miR-3658 through demethylation and blocking EZH2-mediated epigenetic silencing. GLA also activated the SMG1-UPF nonsense-mediated mRNA decay pathway, accelerating MDM2 and RNF6 mRNA degradation. In vivo, GLA reduced H. pylori/MNU-induced gastric tumors and MDM2/RNF6 expression, supporting its therapeutic potential via posttranscriptional oncogene regulation.
Key Findings
GLA dose-dependently inhibited proliferation, adhesion, and invasion, and induced apoptosis (increased caspase-3 activity, cleaved caspase-3/PARP) in HGT-1, SNU-1, SNU-6, and NCI-N87 GC cells without significantly affecting normal GES-1/Hs738.St/Int cells at lower doses. MDM2 and RNF6 were overexpressed in GC cells and downregulated by GLA; their ectopic restoration reversed GLA's inhibitory effects. MDM2 and RNF6 were validated as direct targets of miR-3658, which is downregulated in GC and upregulated by GLA. GLA restored miR-3658 by demethylation and by blocking EZH2/H3K27me3-mediated epigenetic silencing. Additionally, GLA activated the SMG1-UPF mRNA decay pathway, enhancing MDM2 and RNF6 mRNA degradation; SMG1 silencing reduced this effect. In H. pylori/MNU-induced gastric cancer mice, GLA decreased tumor incidence, mucosal inflammation (MPO, IL-1β, TNF-α), and MDM2/RNF6 expression. Thus GLA suppresses GC malignancy via miR-3658-MDM2/RNF6 and SMG1-UPF posttranscriptional mechanisms.
Contribution
Creative Biogene supplied human MDM2 and RNF6 lentivirus particles used to ectopically overexpress these oncogenes in HGT-1 and SNU-1 gastric cancer cells. These reagents enabled rescue experiments showing that restored MDM2/RNF6 expression reverses GLA-induced suppression of proliferation, adhesion, and invasion.
This study investigates Glaucocalyxin A (GLA), a natural ent-kauranoid diterpene, in gastric cancer (GC). GLA inhibited proliferation, adhesion, invasion, and promoted apoptosis in multiple GC cell lines. Mechanistically, GLA downregulated oncoproteins MDM2 and RNF6 by restoring tumor-suppressive miR-3658 through demethylation and blocking EZH2-mediated epigenetic silencing. GLA also activated the SMG1-UPF nonsense-mediated mRNA decay pathway, accelerating MDM2 and RNF6 mRNA degradation. In vivo, GLA reduced H. pylori/MNU-induced gastric tumors and MDM2/RNF6 expression, supporting its therapeutic potential via posttranscriptional oncogene regulation.
Key Findings
GLA dose-dependently inhibited proliferation, adhesion, and invasion, and induced apoptosis (increased caspase-3 activity, cleaved caspase-3/PARP) in HGT-1, SNU-1, SNU-6, and NCI-N87 GC cells without significantly affecting normal GES-1/Hs738.St/Int cells at lower doses. MDM2 and RNF6 were overexpressed in GC cells and downregulated by GLA; their ectopic restoration reversed GLA's inhibitory effects. MDM2 and RNF6 were validated as direct targets of miR-3658, which is downregulated in GC and upregulated by GLA. GLA restored miR-3658 by demethylation and by blocking EZH2/H3K27me3-mediated epigenetic silencing. Additionally, GLA activated the SMG1-UPF mRNA decay pathway, enhancing MDM2 and RNF6 mRNA degradation; SMG1 silencing reduced this effect. In H. pylori/MNU-induced gastric cancer mice, GLA decreased tumor incidence, mucosal inflammation (MPO, IL-1β, TNF-α), and MDM2/RNF6 expression. Thus GLA suppresses GC malignancy via miR-3658-MDM2/RNF6 and SMG1-UPF posttranscriptional mechanisms.
Contribution
Creative Biogene supplied human MDM2 and RNF6 lentivirus particles used to ectopically overexpress these oncogenes in HGT-1 and SNU-1 gastric cancer cells. These reagents enabled rescue experiments showing that restored MDM2/RNF6 expression reverses GLA-induced suppression of proliferation, adhesion, and invasion.