Abstract: This study aimed to investigate the molecular mechanism by which astrocyte elevated gene 1 protein (AEG-1) upregulates the transcriptional expression of eukaryotic translation initiation factor 4E (eIF4E) and its role in the sensitivity of gastric cancer cells to cisplatin (CDDP). Transcriptomic and correlation analyses based on The Cancer Genome Atlas (TCGA) database were performed to screen potential transcriptional regulatory mechanisms of AEG-1. In gastric cancer cell lines, plasmid overexpression, siRNA interference, and pharmacological inhibition were applied, combined with luciferase reporter assay, qRT-PCR, and Western blot to detect the transcriptional and expression changes of eIF4E. Co-immunoprecipitation (Co-IP) was used to verify the interaction between AEG-1 and E1A binding protein p300 (p300), as well as their binding changes upon CXC chemokine ligand 12 (CXCL12) stimulation. Sulforhodamine B colorimetric assay and flow cytometry were employed to evaluate CDDP sensitivity and apoptosis levels, respectively. The transcriptomic and database analyses suggested that AEG-1 may regulate eIF4E expression through acetylation-related mechanisms, and that EP300 was positively correlated with both MTDH and EIF4E in gastric cancer tissues. Functional experiments confirmed that AEG-1 upregulated the transcriptional expression of eIF4E in a p300-dependent manner, and that phosphorylation of AEG-1 at the site of serine 426 (S426) inhibited this effect. CXCL12 stimulation enhanced the protein-protein interaction between AEG-1 and p300. In addition, AEG-1 reduced the sensitivity of gastric cancer cells to CDDP, whereas phosphorylated AEG-1 enhanced cellular sensitivity to CDDP. In conclusion, AEG-1 enhances eIF4E transcriptional expression in a p300-dependent manner, and the phosphorylation status of AEG-1 at the S426 site serves as a key regulatory switch. The AEG-1/p300/eIF4E axis modulates CDDP chemotherapy sensitivity in gastric cancer, providing a new theoretical basis and potential intervention target for precision therapy of gastric cancer.