RHOJ Derived Peptide Promotes Chemosensitivity by Inhibiting Glutamine Metabolism in Gastric Cancer

Abstract Background Chemoresistance is a cause of the failure of chemotherapy in gastric cancer (GC) treatment. Recent studies have highlighted that dysregulation of glutamine metabolism plays a pivotal role in promoting chemoresistance. While small molecule inhibitors targeting glutamine metabolism have been investigated, peptide-based compounds have gained increasing attention due to their high specificity and low toxicity. Endogenous or rationally designed peptides have shown potential in inducing apoptosis, disrupting cancer-related signaling pathways, and overcoming drug resistance in various cancers. However, the potential of functional peptides to target glutamine metabolism and reverse drug resistance in GC has not been thoroughly explored. Methods We performed proteomic profiling to identify proteins upregulated in cisplatin-sensitive GC cells, from which peptides were derived for functional screening. A RHOJ-derived peptide (peptide 1) was identified and validated as a candidate chemosensitizer. Untargeted metabolomics, flow cytometry, molecular docking, molecular dynamics simulations, fluorescence imaging, and a subcutaneous xenograft model were employed to investigate the mechanism by which peptide 1 modulates GLUL-mediated glutamine metabolism and reverses cisplatin resistance. Results In this study, we found glutamine metabolism was enhanced in the cisplatin resistant GC cells, and identified a peptide which derived from RHOJ (named peptide 1) could increase the sensitivity of resistant cells to chemotherapy in GC. Molecular docking analysis revealed that this peptide could bind to the key enzyme glutamine synthetase in glutamine metabolism pathway. Mechanistically, peptide 1 inhibited glutamine production, increased ROS levels, induced DNA damage, and promoted apoptosis in resistant cells, ultimately restoring cisplatin sensitivity both in vitro and in vivo. Conclusions Our study demonstrated that glutamine metabolism plays a vital role in chemoresistance of GC, and RHOJ-derived peptide 1 enhances the chemosensitivity of drug-resistant GC cells through targeting GLUL, depleting glutamine, inducing ROS accumulation, and promoting DNA damage. This mechanism ultimately restores chemosensitivity in drug-resistant cells and highlights peptide 1 as a promising therapeutic strategy for overcoming chemoresistance in GC.