[Prognostic value of palmitoyl-protein thioesterase-1 in gastric cancer and its regulatory role in tumor cell lipid metabolism].

OBJECTIVES

To investigate palmitoyl-protein thioesterase-1 (PPT1) expression in gastric cancer (GC), its prognostic significance, and its regulatory role in tumor cell lipid metabolism.

METHODS

PPT1 expression was analyzed using TCGA-STAD data and immunohistochemistry of clinical samples. In a retrospective cohort of 136 GC patients undergoing radical resection, the association between PPT1 and 5-year survival was evaluated using Kaplan-Meier and Cox regression analyses, and a nomogram was constructed and validated by ROC analysis. GO and REACTOME enrichment analyses were conducted to identify the pathways involved. In cultured GC cell lines with PPT1 knockdown or overexpression, the changes in cell proliferation, migration and invasion were assessed using CCK-8 and Transwell assays. Oil Red O staining, Western blotting and U0126 rescue experiments were performed to explore the role of PPT1-mediated ERK signaling in tumor cell lipid metabolism.

RESULTS

PPT1 protein, localized in the cytoplasm, was significantly upregulated in GC tissues compared with adjacent normal tissues. High PPT1 expression was closely correlated with elevated serum CEA and CA19-9 levels and advanced T and N stages (P<0.05), and was an independent risk factor for reduced 5-year postoperative survival. The nomogram incorporating PPT1 showed good predictive accuracy (C-index=0.812) with an AUC of 0.837. In cultured GC cells, PPT1 knockdown significantly suppressed while PPT1 overexpression promoted cell proliferation, migration and invasion. PPT1 overexpression induced abnormal intracellular lipid accumulation in GC cells and significantly upregulated the expressions of the key lipogenic proteins SREBP 1 and FASN, and this pro-lipogenic effect and subsequent ERK signaling activation were effectively reversed by U0126.

CONCLUSIONS

PPT1 is overexpressed in GC tissues and predicts poor prognosis. PPT1 overexpression promotes GC progression by activating the ERK signaling pathway and thereby modulating lipid metabolism, suggesting its potential as a novel prognostic biomarker and a therapeutic target for GC.