Melittin inhibits NSCLC metastasis by targeting USP10 and promoting RNF20-mediated ubiquitination and degradation of PSMA7.

BACKGROUND AND AIMS: Non-small cell lung cancer (NSCLC) accounts for > 80% of lung cancer cases, and its mortality is predominantly attributed to its metastatic nature. Therefore, developing novel therapeutic drugs and treatment methods to improve the prognosis of patients with NSCLC is critical. PURPOSE: This study examined the effect of Melittin (MEL) on NSCLC metastasis and explored the underlying regulatory mechanisms. METHODS: The effects of different doses of MEL on NSCLC cells was examined using Transwell and wound healing assays. RT-qPCR and western blotting were performed to assess the mRNA and protein expression of proteasome 20S subunit alpha 7 (PSMA7) and epithelial-mesenchymal transition-related genes such as E-cadherin and N-cadherin. A PSMA7 overexpressing lentiviral vector was constructed and transfected into HCC1833 and A549 cells to examine the inhibitory effect of MEL on NSCLC malignant progression. Proteomics analyses were performed to identify differentially expressed proteins in NSCLC cells following MEL treatment. The potential involvement of the ubiquitin degradation pathway was examined using cycloheximide and MG132. Co-immunoprecipitation (Co-IP) assays were performed to detect interactions between PSMA7, ubiquitin-specific peptidase (USP)-10, and ring finger protein (RNF)-20. An in vivo lung metastasis model was used to evaluate the effects of MEL on NSCLC metastasis. RESULTS: MEL treatment suppressed the malignant migration of NSCLC cells, as shown in Transwell and wound healing assays. MEL treatment also inhibited NSCLC lung metastasis in vivo. Proteomics analysis showed that MEL inhibited PSMA7 expression. Existing studies have shown that PSMA7 affects EMT process mainly by regulating the protein stability of key EMT factors. MEL downregulated EMT key factors, N-cadherin and upregulated E-cadherin, and it activated the ubiquitin degradation pathway, as shown by cycloheximide and MG132 treatments. Co-IP experiments showed that PSMA7 interacts with USP10 and RNF20. Molecular docking validated the interaction of MEL with USP10, confirming the involvement of the ubiquitin pathway in the effects of MEL on promoting the degradation of PSMA7. PSMA7 overexpression significantly reversed the inhibitory effect of MEL on NSCLC cell metastasis in vitro. CONCLUSION: MEL suppresses the metastasis of NSCLC by targeting USP10 and promoting RNF20-mediated ubiquitination and degradation ofPSMA7.